Yi Cui

All Publications

• Household Materials Selection for Homemade Cloth Face Coverings and Their Filtration Efficiency Enhancement with Triboelectric Charging. Nano letters Zhao, M., Liao, L., Xiao, W., Yu, X., Wang, H., Wang, Q., Lin, Y. L., Kilinc-Balci, F. S., Price, A., Chu, L., Chu, M. C., Chu, S., Cui, Y. 2020

  Abstract

  The COVID-19 pandemic is currently causing a severe disruption and shortage in the global supply chain of necessary personal protective equipment (e.g., N95 respirators). The U.S. CDC has recommended use of household cloth by the general public to make cloth face coverings as a method of source control. We evaluated the filtration properties of natural and synthetic materials using a modified procedure for N95 respirator approval. Common fabrics of cotton, polyester, nylon, and silk had filtration efficiency of 5-25%, polypropylene spunbond had filtration efficiency 6-10%, and paper-based products had filtration efficiency of 10-20%. An advantage of polypropylene spunbond is that it can be simply triboelectrically charged to enhance the filtration efficiency (from 6 to >10%) without any increase in pressure (stable overnight and in humid environments). Using the filtration quality factor, fabric microstructure, and charging ability, we are able to provide an assessment of suggested fabric materials for homemade facial coverings.

  View details for DOI 10.1021/acs.nanolett.0c02211

  View details for PubMedID 32484683

• Incorporating the nanoscale encapsulation concept from liquid electrolytes into solid-state lithium-sulfur batteries. Nano letters Gao, X., Zheng, X., Wang, J., Zhang, Z., Xiao, X., Wan, J., Ye, Y., Chou, L., Lee, H. K., Wang, J., Vila, R. A., Yang, Y., Zhang, P., Wang, L., Cui, Y. 2020

  Abstract

  Lithium-sulfur (Li-S) batteries are attractive due to their high specific energy and low-cost prospect. Most studies in the past decade are based on these batteries with liquid electrolytes, where many exciting material/structural designs are realized at the nanoscale to address problems of Li-S chemistry. Recently, there is a new promising direction to develop Li-S batteries with solid polymer electrolytes, although it is unclear whether the concepts from liquid electrolytes are applicable in the solid state to improve battery performance. Here we demonstrate that the nanoscale encapsulation concept based on Li2S-TiS2 core-shell particles, originally developed in liquid electrolytes, is very effective in solid polymer electrolytes. Using in situ optical cell measurement and sulfur K-edge X-ray absorption near edge spectroscopy, we find that polysulfides form and are well trapped inside individual particles by the nanoscale TiS2 encapsulation. This TiS2 encapsulation layer also functions to catalyze the oxidation reaction of Li2S to sulfur, even in solid-state electrolytes, proved by both experiments and density functional theory calculations. A high cell-level specific energy of 427 W∙h∙kg-1 at 60 °C (including the mass of the anode, cathode, and solid-state electrolyte, but excluding the current collector and packaging) is achieved by integrating TiS2 encapsulated Li2S cathode with ultrathin polyethylene oxide-based solid polymer electrolyte (10~20 m) and lithium metal anode. The solid-state cells show excellent stability over 150 charge/discharge cycles at 0.8 C at 80 °C. This study points to the fruitful direction of borrowing concepts from liquid electrolytes into solid-state Li-S batteries.

  View details for DOI 10.1021/acs.nanolett.0c02033

  View details for PubMedID 32515973

• Stretchable electrochemical energy storage devices. Chemical Society reviews Mackanic, D. G., Chang, T., Huang, Z., Cui, Y., Bao, Z. 2020

  Abstract

  The increasingly intimate contact between electronics and the human body necessitates the development of stretchable energy storage devices that can conform and adapt to the skin. As such, the development of stretchable batteries and supercapacitors has received significant attention in recent years. This review provides an overview of the general operating principles of batteries and supercapacitors and the requirements to make these devices stretchable. The following sections provide an in-depth analysis of different strategies to convert the conventionally rigid electrochemical energy storage materials into stretchable form factors. Namely, the strategies of strain engineering, rigid island geometry, fiber-like geometry, and intrinsic stretchability are discussed. A wide range of materials are covered for each strategy, including polymers, metals, and ceramics. By comparing the achieved electrochemical performance and strain capability of these different materials strategies, we allow for a side-by-side comparison of the most promising strategies for enabling stretchable electrochemical energy storage. The final section consists of an outlook for future developments and challenges for stretchable supercapacitors and batteries.

  View details for DOI 10.1039/d0cs00035c

  View details for PubMedID 32483575

• Electrode roughness dependent electrodeposition of sodium at the nanoscale NANO ENERGY Zeng, Z., Barai, P., Lee, S., Yang, J., Zhang, X., Zheng, W., Liu, Y., Bustillo, K. C., Ercius, P., Guo, J., Cui, Y., Srinivasan, V., Zheng, H. 2020; 72

  View details for DOI 10.1016/j.nanoen.2020.104721

  View details for Web of Science ID 000532793600005

• An approaching-theoretical-capacity anode material for aqueous battery: Hollow hexagonal prism Bi2O3 assembled by nanoparticles ENERGY STORAGE MATERIALS Zan, G., Wu, T., Hu, P., Zhou, Y., Zhao, S., Xu, S., Chen, J., Cui, Y., Wu, Q. 2020; 28: 82–90

  View details for DOI 10.1016/j.ensm.2020.02.027

  View details for Web of Science ID 000529908800010

• Can N95 Respirators Be Reused after Disinfection? How Many Times? ACS nano Liao, L., Xiao, W., Zhao, M., Yu, X., Wang, H., Wang, Q., Chu, S., Cui, Y. 2020

  Abstract

  The coronavirus disease 2019 (COVID-19) pandemic has led to a major shortage of N95 respirators, which are essential for protecting healthcare professionals and the general public who may come into contact with the virus. Thus, it is essential to determine how we can reuse respirators and other personal protective equipment in these urgent times. We investigated multiple commonly used disinfection schemes on media with particle filtration efficiency of 95%. Heating was recently found to inactivate the virus in solution within 5 min at 70 °C and is among the most scalable, user-friendly methods for viral disinfection. We found that heat (≤85 °C) under various humidities (≤100% relative humidity, RH) was the most promising, nondestructive method for the preservation of filtration properties in meltblown fabrics as well as N95-grade respirators. At 85 °C, 30% RH, we were able to perform 50 cycles of heat treatment without significant changes in the filtration efficiency. At low humidity or dry conditions, temperatures up to 100 °C were not found to alter the filtration efficiency significantly within 20 cycles of treatment. Ultraviolet (UV) irradiation was a secondary choice, which was able to withstand 10 cycles of treatment and showed small degradation by 20 cycles. However, UV can potentially impact the material strength and subsequent sealing of respirators. Finally, treatments involving liquids and vapors require caution, as steam, alcohol, and household bleach all may lead to degradation of the filtration efficiency, leaving the user vulnerable to the viral aerosols.

  View details for DOI 10.1021/acsnano.0c03597

  View details for PubMedID 32368894

• Electrolytes for microsized silicon NATURE ENERGY Wang, J., Cui, Y. 2020

  View details for DOI 10.1038/s41560-020-0608-7

  View details for Web of Science ID 000529587700001

• A High-Rate Lithium Manganese Oxide-Hydrogen Battery. Nano letters Zhu, Z., Wang, M., Meng, Y., Lin, Z., Cui, Y., Chen, W. 2020

  Abstract

  Rechargeable hydrogen gas batteries show promises for the integration of renewable yet intermittent solar and wind electricity into the grid energy storage. Here, we describe a rechargeable, high-rate, and long-life hydrogen gas battery that exploits a nanostructured lithium manganese oxide cathode and a hydrogen gas anode in an aqueous electrolyte. The proposed lithium manganese oxide-hydrogen battery shows a discharge potential of 1.3 V, a remarkable rate of 50 C with Coulombic efficiency of 99.8%, and a robust cycle life. A systematic electrochemical study demonstrates the significance of the electrocatalytic hydrogen gas anode and reveals the charge storage mechanism of the lithium manganese oxide-hydrogen battery. This work provides opportunities for the development of new rechargeable hydrogen batteries for the future grid-scale energy storage.

  View details for DOI 10.1021/acs.nanolett.0c00044

  View details for PubMedID 32302150

• Advanced Textiles for Personal Thermal Management and Energy JOULE Peng, Y., Cui, Y. 2020; 4 (4): 724–42

  View details for DOI 10.1016/j.joule.2020.02.011

  View details for Web of Science ID 000527264500009

• Tortuosity Effects in Lithium-Metal Host Anodes JOULE Chen, H., Pei, A., Wan, J., Lin, D., Vila, R., Wang, H., Mackanic, D., Steinruck, H., Huang, W., Li, Y., Yang, A., Xie, J., Wu, Y., Wang, H., Cui, Y. 2020; 4 (4): 938–52

  View details for DOI 10.1016/j.joule.2020.03.008

  View details for Web of Science ID 000527264500022

• Improving Lithium Metal Composite Anodes with Seeding and Pillaring Effects of Silicon Nanoparticles. ACS nano Wang, H., Cao, X., Gu, H., Liu, Y., Li, Y., Zhang, Z., Huang, W., Wang, H., Wang, J., Xu, W., Zhang, J., Cui, Y. 2020

  Abstract

  Metallic lithium (Li) anodes are crucial for the development of high specific energy batteries yet are plagued by their poor cycling efficiency. Electrode architecture engineering is vital for maintaining a stable anode volume and suppressing Li corrosion during cycling. In this paper, a reduced graphene oxide "host" framework for Li metal anodes is further optimized by embedding silicon (Si) nanoparticles between the graphene layers. They serve as Li nucleation seeds to promote Li deposition within the framework even without prestored Li. Meanwhile, the LixSi alloy particles serve as supporting "pillars" between the graphene layers, enabling a minimized thickness shrinkage after full stripping of metallic Li. Combined with a Li compatible electrolyte, a 99.4% Coulombic efficiency over 600 cycles is achieved, and stable cycling of a Li||NMC532 full cell for 380 cycles with negligible capacity decay is realized.

  View details for DOI 10.1021/acsnano.0c00184

  View details for PubMedID 32271533

• A New Class of Ionically Conducting Fluorinated Ether Electrolytes with High Electrochemical Stability. Journal of the American Chemical Society Amanchukwu, C. V., Yu, Z., Kong, X., Qin, J., Cui, Y., Bao, Z. 2020

  Abstract

  Increasing battery energy density is greatly desired for applications such as portable electronics and transportation. However, many next-generation batteries are limited by electrolyte selection because high ionic conductivity and poor electrochemical stability are typically observed in most electrolytes. For example, ether-based electrolytes have high ionic conductivity but are oxidatively unstable above 4 V, which prevents the use of high-voltage cathodes that promise higher energy densities. In contrast, hydrofluoroethers (HFEs) have high oxidative stability but do not dissolve lithium salt. In this work, we synthesize a new class of fluorinated ether electrolytes that combine the oxidative stability of HFEs with the ionic conductivity of ethers in a single compound. We show that conductivities of up to 2.7 * 10-4 S/cm (at 30 °C) can be obtained with oxidative stability up to 5.6 V. The compounds also show higher lithium transference numbers compared to typical ethers. Furthermore, we use nuclear magnetic resonance (NMR) and molecular dynamics (MD) to study their ionic transport behavior and ion solvation environment, respectively. Finally, we demonstrate that this new class of electrolytes can be used with a Ni-rich layered cathode (NMC 811) to obtain over 100 cycles at a C/5 rate. The design of new molecules with high ionic conductivity and high electrochemical stability is a novel approach for the rational design of next-generation batteries.

  View details for DOI 10.1021/jacs.9b11056

  View details for PubMedID 32233433

• Resolving Nanoscopic and Mesoscopic Heterogeneity of Fluorinated Species in Battery Solid-Electrolyte Interphases by Cryogenic Electron Microscopy ACS ENERGY LETTERS Huang, W., Wang, H., Boyle, D. T., Li, Y., Cui, Y. 2020; 5 (4): 1128–35

  View details for DOI 10.1021/acsenergylett.0c00194

  View details for Web of Science ID 000526315900015

• Scalable synthesis of nanoporous silicon microparticles for highly cyclable lithium-ion batteries NANO RESEARCH Wang, J., Huang, W., Kim, Y., Jeong, Y., Kim, S., Heo, J., Lee, H., Liu, B., Nah, J., Cui, Y. 2020

  View details for DOI 10.1007/s12274-020-2770-4

  View details for Web of Science ID 000524406500005

• Aspects of the synthesis of thin film superconducting infinite-layer nickelates APL MATERIALS Lee, K., Goodge, B. H., Li, D., Osada, M., Wang, B., Cui, Y., Kourkoutis, L. F., Hwang, H. Y. 2020; 8 (4)

  View details for DOI 10.1063/5.0005103

  View details for Web of Science ID 000526748400002

• High-purity electrolytic lithium obtained from low-purity sources using solid electrolyte NATURE SUSTAINABILITY Lang, J., Jin, Y., Liu, K., Long, Y., Zhang, H., Qi, L., Wu, H., Cui, Y. 2020

  View details for DOI 10.1038/s41893-020-0485-x

  View details for Web of Science ID 000517740000003

• A novel battery scheme: Coupling nanostructured phosphorus anodes with lithium sulfide cathodes NANO RESEARCH Wu, D., Zhou, G., Mao, E., Sun, Y., Liu, B., Wang, L., Wang, J., Shi, F., Cui, Y. 2020

  View details for DOI 10.1007/s12274-020-2645-8

  View details for Web of Science ID 000517717600001

• A binder-free high silicon content flexible anode for Li-ion batteries ENERGY & ENVIRONMENTAL SCIENCE Wang, H., Fu, J., Wang, C., Wang, J., Yang, A., Li, C., Sun, Q., Cui, Y., Li, H. 2020; 13 (3): 848–58

  View details for DOI 10.1039/c9ee02615k

  View details for Web of Science ID 000524490200019

• Efficient synthesis of high-sulfur-content cathodes for high-performance Li-S batteries based on solvothermal polysulfide chemistry JOURNAL OF POWER SOURCES Weng, Y., Wang, H., Lee, R., Huang, C., Huang, S., Abdollahifar, M., Kuo, L., Hwang, B., Kuo, C., Cui, Y., Wu, N. 2020; 450

  View details for DOI 10.1016/j.jpowsour.2019.227676

  View details for Web of Science ID 000517663800036

• A Fireproof, Lightweight, Polymer-Polymer Solid-State Electrolyte for Safe Lithium Batteries. Nano letters Cui, Y., Wan, J., Ye, Y., Liu, K., Chou, L., Cui, Y. 2020

  Abstract

  Safety issues in lithium-ion batteries have raised serious concerns due to their ubiquitous utilization and close contact with the human body. Replacing flammable liquid electrolytes, solid-state electrolytes (SSEs) is thought to address this issue as well as provide unmatched energy densities in Li-based batteries. However, among the most intensively studied SSEs, polymeric solid electrolyte and polymer/ceramic composites are usually flammable, leaving the safety issue unattended. Here, we report the first design of a fireproof, ultralightweight polymer-polymer SSE. The SSE is composed of a porous mechanic enforcer (polyimide, PI), a fire-retardant additive (decabromodiphenyl ethane, DBDPE), and a ionic conductivepolymer electrolyte (poly(ethylene oxide)/lithium bis(trifluoromethanesulfonyl)imide). The whole SSE is made from organic materials, with a thin, tunable thickness (10-25 mum), which endorse the energy density comparable to conventional separator/liquid electrolytes. The PI/DBDPE film is thermally stable, nonflammable, and mechanically strong, preventing Li-Li symmetrical cells from short-circuiting after more than 300 h of cycling. LiFePO4/Li half cells with our SSE show a high rate performance (131 mAh g-1 at 1 C) as well as cycling performance (300 cycles at C/2 rate) at 60 °C. Most intriguingly, pouch cells made with our polymer-polymer SSE still functioned well even under flame abuse tests.

  View details for DOI 10.1021/acs.nanolett.9b04815

  View details for PubMedID 32020809

• Membrane-Free Zn/MnO2 Flow Battery for Large-Scale Energy Storage ADVANCED ENERGY MATERIALS Li, G., Chen, W., Zhang, H., Gong, Y., Shi, F., Wang, J., Zhang, R., Chen, G., Jin, Y., Wu, T., Tang, Z., Cui, Y. 2020

  View details for DOI 10.1002/aenm.201902085

  View details for Web of Science ID 000510226100001

• Robust ultraclean atomically thin membranes for atomic-resolution electron microscopy. Nature communications Zheng, L., Chen, Y., Li, N., Zhang, J., Liu, N., Liu, J., Dang, W., Deng, B., Li, Y., Gao, X., Tan, C., Yang, Z., Xu, S., Wang, M., Yang, H., Sun, L., Cui, Y., Wei, X., Gao, P., Wang, H., Peng, H. 2020; 11 (1): 541

  Abstract

  The fast development of high-resolution electron microscopy (EM) demands a background-noise-free substrate to support the specimens, where atomically thin graphene membranes can serve as an ideal candidate. Yet the preparation of robust and ultraclean graphene EM grids remains challenging. Here we present a polymer- and transfer-free direct-etching method for batch fabrication of robust ultraclean graphene grids through membrane tension modulation. Loading samples on such graphene grids enables the detection of single metal atoms and atomic-resolution imaging of the iron core of ferritin molecules at both room- and cryo-temperature. The same kind of hydrophilic graphene grid allows the formation of ultrathin vitrified ice layer embedded most protein particles at the graphene-water interface, which facilitates cryo-EM 3D reconstruction of archaea 20S proteasomes at a record high resolution of ~2.36A. Our results demonstrate the significant improvements in image quality using the graphene grids and expand the scope of EM imaging.

  View details for DOI 10.1038/s41467-020-14359-0

  View details for PubMedID 31992713

• High-Energy-Density Solid-Electrolyte-Based Liquid Li-S and Li-Se Batteries JOULE Jin, Y., Liu, K., Lang, J., Jiang, X., Zheng, Z., Su, Q., Huang, Z., Long, Y., Wang, C., Wu, H., Cui, Y. 2020; 4 (1): 262–74

  View details for DOI 10.1016/j.joule.2019.09.003

  View details for Web of Science ID 000507640500023

• From Intercalation to Alloying Chemistry: Structural Design of Silicon Anodes for the Next Generation of Lithium-ion Batteries CHINESE JOURNAL OF STRUCTURAL CHEMISTRY Yang Yu-Fei, Yang Jin-Long, Pan Feng, Cui Yi 2020; 39 (1): 16–19

  View details for DOI 10.14102/j.cnki.0254-5861.2011-2715

  View details for Web of Science ID 000509743600003

• Synergistic enhancement of electrocatalytic CO2 reduction to C2 oxygenates at nitrogen-doped nanodiamonds/Cu interface. Nature nanotechnology Wang, H., Tzeng, Y., Ji, Y., Li, Y., Li, J., Zheng, X., Yang, A., Liu, Y., Gong, Y., Cai, L., Li, Y., Zhang, X., Chen, W., Liu, B., Lu, H., Melosh, N. A., Shen, Z., Chan, K., Tan, T., Chu, S., Cui, Y. 2020

  Abstract

  To date, effective control over the electrochemical reduction of CO2 to multicarbon products (C≥2) has been very challenging. Here, we report a design principle for the creation of a selective yet robust catalytic interface for heterogeneous electrocatalysts in the reduction of CO2 to C2 oxygenates, demonstrated by rational tuning of an assembly of nitrogen-doped nanodiamonds and copper nanoparticles. The catalyst exhibits a Faradaic efficiency of ~63% towards C2 oxygenates at applied potentials of only -0.5V versus reversible hydrogen electrode. Moreover, this catalyst shows an unprecedented persistent catalytic performance up to 120h, with steady current and only 19% activity decay. Density functional theory calculations show that CO binding is strengthened at the copper/nanodiamond interface, suppressing CO desorption and promoting C2 production by lowering the apparent barrier for CO dimerization. The inherent compositional and electronic tunability of the catalyst assembly offers an unrivalled degree of control over the catalytic interface, and thereby the reaction energetics and kinetics.

  View details for DOI 10.1038/s41565-019-0603-y

  View details for PubMedID 31907442

• Electrochemical generation of liquid and solid sulfur on two-dimensional layered materials with distinct areal capacities. Nature nanotechnology Yang, A. n., Zhou, G. n., Kong, X. n., Vilá, R. A., Pei, A. n., Wu, Y. n., Yu, X. n., Zheng, X. n., Wu, C. L., Liu, B. n., Chen, H. n., Xu, Y. n., Chen, D. n., Li, Y. n., Fakra, S. n., Hwang, H. Y., Qin, J. n., Chu, S. n., Cui, Y. n. 2020

  Abstract

  It has recently been shown that sulfur, a solid material in its elementary form S8, can stay in a supercooled state as liquid sulfur in an electrochemical cell. We establish that this newly discovered state could have implications for lithium-sulfur batteries. Here, through in situ studies of electrochemical sulfur generation, we show that liquid (supercooled) and solid elementary sulfur possess very different areal capacities over the same charging period. To control the physical state of sulfur, we studied its growth on two-dimensional layered materials. We found that on the basal plane, only liquid sulfur accumulates; by contrast, at the edge sites, liquid sulfur accumulates if the thickness of the two-dimensional material is small, whereas solid sulfur nucleates if the thickness is large (tens of nanometres). Correlating the sulfur states with their respective areal capacities, as well as controlling the growth of sulfur on two-dimensional materials, could provide insights for the design of future lithium-sulfur batteries.

  View details for DOI 10.1038/s41565-019-0624-6

  View details for PubMedID 31988508

• Design Principles of Artificial Solid Electrolyte Interphases for Lithium-Metal Anodes Cell Reports Physical Science Yu, Z., Cui, Y., Bao, Z. 2020; 1 (7): 100119

  View details for DOI 10.1016/j.xcrp.2020.100119

• High-temperature, spectrally-selective, scalable, and flexible thin-film Si absorber and emitter OPTICAL MATERIALS EXPRESS Zhou, Z., Tian, H., Hymel, T. M., Reddy, H., Shalaev, V. M., Cui, Y., Bermel, P. 2020; 10 (1): 208–21

  View details for DOI 10.1364/OME.381680

  View details for Web of Science ID 000511128900022

• Supercooled liquid sulfur maintained in three-dimensional current collector for high-performance Li-S batteries. Science advances Zhou, G. n., Yang, A. n., Gao, G. n., Yu, X. n., Xu, J. n., Liu, C. n., Ye, Y. n., Pei, A. n., Wu, Y. n., Peng, Y. n., Li, Y. n., Liang, Z. n., Liu, K. n., Wang, L. W., Cui, Y. n. 2020; 6 (21): eaay5098

  Abstract

  In lithium-sulfur (Li-S) chemistry, the electrically/ionically insulating nature of sulfur and Li2S leads to sluggish electron/ion transfer kinetics for sulfur species conversion. Sulfur and Li2S are recognized as solid at room temperature, and solid-liquid phase transitions are the limiting steps in Li-S batteries. Here, we visualize the distinct sulfur growth behaviors on Al, carbon, Ni current collectors and demonstrate that (i) liquid sulfur generated on Ni provides higher reversible capacity, faster kinetics, and better cycling life compared to solid sulfur; and (ii) Ni facilitates the phase transition (e.g., Li2S decomposition). Accordingly, light-weight, 3D Ni-based current collector is designed to control the deposition and catalytic conversion of sulfur species toward high-performance Li-S batteries. This work provides insights on the critical role of the current collector in determining the physical state of sulfur and elucidates the correlation between sulfur state and battery performance, which will advance electrode designs in high-energy Li-S batteries.

  View details for DOI 10.1126/sciadv.aay5098

  View details for PubMedID 32494732

  View details for PubMedCentralID PMC7244266

• A molten battery consisting of Li metal anode, AlCl3-LiCl cathode and solid electrolyte ENERGY STORAGE MATERIALS Lang, J., Liu, K., Jin, Y., Long, Y., Qi, L., Wu, H., Cui, Y. 2020; 24: 412–16

  View details for DOI 10.1016/j.ensm.2019.07.027

  View details for Web of Science ID 000500484000042

• Mechanical rolling formation of interpenetrated lithium metal/lithium tin alloy foil for ultrahigh-rate battery anode. Nature communications Wan, M. n., Kang, S. n., Wang, L. n., Lee, H. W., Zheng, G. W., Cui, Y. n., Sun, Y. n. 2020; 11 (1): 829

  Abstract

  To achieve good rate capability of lithium metal anodes for high-energy-density batteries, one fundamental challenge is the slow lithium diffusion at the interface. Here we report an interpenetrated, three-dimensional lithium metal/lithium tin alloy nanocomposite foil realized by a simple calendering and folding process of lithium and tin foils, and spontaneous alloying reactions. The strong affinity between the metallic lithium and lithium tin alloy as mixed electronic and ionic conducting networks, and their abundant interfaces enable ultrafast charger diffusion across the entire electrode. We demonstrate that a lithium/lithium tin alloy foil electrode sustains stable lithium stripping/plating under 30 mA cm-2 and 5 mAh cm-2 with a very low overpotential of 20 mV for 200 cycles in a commercial carbonate electrolyte. Cycled under 6 C (6.6 mA cm-2), a 1.0 mAh cm-2 LiNi0.6Co0.2Mn0.2O2 electrode maintains a substantial 74% of its capacity by pairing with such anode.

  View details for DOI 10.1038/s41467-020-14550-3

  View details for PubMedID 32047149

• Transient Voltammetry with Ultramicroelectrodes Reveals the Electron Transfer Kinetics of Lithium Metal Anodes Adv. Energy Lett. Boyle, D., Kong, X., Pei, A., Rudnicki, P., Shi, F., Huang, W., Bao, Z., Qin, J., Cui, Y. 2020; 5: 701-709

  View details for DOI 10.1021/acsenergylett.0c00031

• Electrochemical generation of liquid and solid sulfur on two-dimensional layered materials with distinct areal capacities Nature Nanotechnology Yang, A., Zhou, G., et al 2020

  View details for DOI 10.1038/s41565-019-0624-6

• A Single-Ion Conducting Borate Network Polymer as a Viable Quasi-Solid Electrolyte for Lithium Metal Batteries. Advanced materials (Deerfield Beach, Fla.) Shin, D. M., Bachman, J. E., Taylor, M. K., Kamcev, J. n., Park, J. G., Ziebel, M. E., Velasquez, E. n., Jarenwattananon, N. N., Sethi, G. K., Cui, Y. n., Long, J. R. 2020: e1905771

  Abstract

  Lithium-ion batteries have remained a state-of-the-art electrochemical energy storage technology for decades now, but their energy densities are limited by electrode materials and conventional liquid electrolytes can pose significant safety concerns. Lithium metal batteries featuring Li metal anodes, solid polymer electrolytes, and high-voltage cathodes represent promising candidates for next-generation devices exhibiting improved power and safety, but such solid polymer electrolytes generally do not exhibit the required excellent electrochemical properties and thermal stability in tandem. Here, an interpenetrating network polymer with weakly coordinating anion nodes that functions as a high-performing single-ion conducting electrolyte in the presence of minimal plasticizer, with a wide electrochemical stability window, a high room-temperature conductivity of 1.5 × 10-4 S cm-1 , and exceptional selectivity for Li-ion conduction (tLi+ = 0.95) is reported. Importantly, this material is also flame retardant and highly stable in contact with lithium metal. Significantly, a lithium metal battery prototype containing this quasi-solid electrolyte is shown to outperform a conventional battery featuring a polymer electrolyte.

  View details for DOI 10.1002/adma.201905771

  View details for PubMedID 31985110

• Theoretical Calculation Guided Design of Single-Atom Catalysts toward Fast Kinetic and Long-Life Li-S Batteries. Nano letters Zhou, G. n., Zhao, S. n., Wang, T. n., Yang, S. Z., Johannessen, B. n., Chen, H. n., Liu, C. n., Ye, Y. n., Wu, Y. n., Peng, Y. n., Liu, C. n., Jiang, S. P., Zhang, Q. n., Cui, Y. n. 2020

  Abstract

  Lithium-sulfur (Li-S) batteries are promising next-generation energy storage technologies due to their high theoretical energy density, environmental friendliness, and low cost. However, low conductivity of sulfur species, dissolution of polysulfides, poor conversion from sulfur reduction, and lithium sulfide (Li2S) oxidation reactions during discharge-charge processes hinder their practical applications. Herein, under the guidance of density functional theory calculations, we have successfully synthesized large-scale single atom vanadium catalysts seeded on graphene to achieve high sulfur content (80 wt % sulfur), fast kinetic (a capacity of 645 mAh g-1 at 3 C rate), and long-life Li-S batteries. Both forward (sulfur reduction) and reverse reactions (Li2S oxidation) are significantly improved by the single atom catalysts. This finding is confirmed by experimental results and consistent with theoretical calculations. The ability of single metal atoms to effectively trap the dissolved lithium polysulfides (LiPSs) and catalytically convert the LiPSs/Li2S during cycling significantly improved sulfur utilization, rate capability, and cycling life. Our work demonstrates an efficient design pathway for single atom catalysts and provides solutions for the development of high energy/power density Li-S batteries.

  View details for DOI 10.1021/acs.nanolett.9b04719

  View details for PubMedID 31887051

• Electrotunable liquid sulfur microdroplets. Nature communications Zhou, G. n., Yang, A. n., Wang, Y. n., Gao, G. n., Pei, A. n., Yu, X. n., Zhu, Y. n., Zong, L. n., Liu, B. n., Xu, J. n., Liu, N. n., Zhang, J. n., Li, Y. n., Wang, L. W., Hwang, H. Y., Brongersma, M. L., Chu, S. n., Cui, Y. n. 2020; 11 (1): 606

  Abstract

  Manipulating liquids with tunable shape and optical functionalities in real time is important for electroactive flow devices and optoelectronic devices, but remains a great challenge. Here, we demonstrate electrotunable liquid sulfur microdroplets in an electrochemical cell. We observe electrowetting and merging of sulfur droplets under different potentiostatic conditions, and successfully control these processes via selective design of sulfiphilic/sulfiphobic substrates. Moreover, we employ the electrowetting phenomena to create a microlens based on the liquid sulfur microdroplets and tune its characteristics in real time through changing the shape of the liquid microdroplets in a fast, repeatable, and controlled manner. These studies demonstrate a powerful in situ optical battery platform for unraveling the complex reaction mechanism of sulfur chemistries and for exploring the rich material properties of the liquid sulfur, which shed light on the applications of liquid sulfur droplets in devices such as microlenses, and potentially other electrotunable and optoelectronic devices.

  View details for DOI 10.1038/s41467-020-14438-2

  View details for PubMedID 32001696

• An ultrathin ionomer interphase for high efficiency lithium anode in carbonate based electrolyte. Nature communications Weng, Y., Liu, H., Pei, A., Shi, F., Wang, H., Lin, C., Huang, S., Su, L., Hsu, J., Fang, C., Cui, Y., Wu, N. 2019; 10 (1): 5824

  Abstract

  High coulombic efficiency and dendrite suppression in carbonate electrolytes remain challenges to the development of high-energy lithium ion batteries containing lithium metal anodes. Here we demonstrate an ultrathin (≤100nm) lithium-ion ionomer membrane consisting of lithium-exchanged sulfonated polyether ether ketone embedded with polyhedral oligosilsesquioxane as a coating layer on copper or lithium for achieving efficient and stable lithium plating-stripping cycles in a carbonate-based electrolyte. Operando analyses and theoretical simulation reveal the remarkable ability of the ionomer coating to enable electric field homogenization over a considerably large lithium-plating surface. The membrane coating, serving as an artificial solid-electrolyte interphase filter in minimizing parasitic reactions at the electrolyte-electrode interface, enables dendrite-free lithium plating on copper with outstanding coulombic efficiencies at room and elevated (50°C) temperatures. The membrane coated copper demonstrates itself as a promising current collector for manufacturing high-quality pre-plated lithium thin-film anode.

  View details for DOI 10.1038/s41467-019-13783-1

  View details for PubMedID 31862992

• A Water Stable, Near-Zero-Strain O3-Layered Titanium-Based Anode for Long Cycle Sodium-Ion Battery ADVANCED FUNCTIONAL MATERIALS Cao, Y., Zhang, Q., Wei, Y., Guo, Y., Zhang, Z., Huang, W., Yang, K., Chen, W., Zhai, T., Li, H., Cui, Y. 2019

  View details for DOI 10.1002/adfm.201907023

  View details for Web of Science ID 000502900800001

• Improved Oxygen Reduction Reaction Activity of Nanostructured CoS2 through Electrochemical Tuning ACS APPLIED ENERGY MATERIALS Zhao, W., Bothra, P., Lu, Z., Li, Y., Mei, L., Liu, K., Zhao, Z., Chen, G., Back, S., Siahrostami, S., Kulkarni, A., Norskov, J. K., Bajdich, M., Cui, Y. 2019; 2 (12): 8605–14

  View details for DOI 10.1021/acsaem.9b01527

  View details for Web of Science ID 000504953500030

• Artificial Solid Electrolyte Interphase for Suppressing Surface Reactions and Cathode Dissolution in Aqueous Zinc Ion Batteries ACS ENERGY LETTERS Guo, J., Ming, J., Lei, Y., Zhang, W., Xia, C., Cui, Y., Alshareef, H. N. 2019; 4 (12): 2776–81

  View details for DOI 10.1021/acsenergylett.9b02029

  View details for Web of Science ID 000503114500002

• Decoupling of mechanical properties and ionic conductivity in supramolecular lithium ion conductors. Nature communications Mackanic, D. G., Yan, X., Zhang, Q., Matsuhisa, N., Yu, Z., Jiang, Y., Manika, T., Lopez, J., Yan, H., Liu, K., Chen, X., Cui, Y., Bao, Z. 2019; 10 (1): 5384

  Abstract

  The emergence of wearable electronics puts batteries closer to the human skin, exacerbating the need for battery materials that are robust, highly ionically conductive, and stretchable. Herein, we introduce a supramolecular design as an effective strategy to overcome the canonical tradeoff between mechanical robustness and ionic conductivity in polymer electrolytes. The supramolecular lithium ion conductor utilizes orthogonally functional H-bonding domains and ion-conducting domains to create a polymer electrolyte with unprecedented toughness (29.3 MJ m-3) and high ionic conductivity (1.2*10-4 S cm-1 at 25°C). Implementation of the supramolecular ion conductor as a binder material allows for the creation of stretchable lithium-ion battery electrodes with strain capability of over 900% via a conventional slurry process. The supramolecular nature of these battery components enables intimate bonding at the electrode-electrolyte interface. Combination of these stretchable components leads to a stretchable battery with a capacity of 1.1 mAh cm-2 that functions even when stretched to 70% strain. The method reported here of decoupling ionic conductivity from mechanical properties opens a promising route to create high-toughness ion transport materials for energy storage applications.

  View details for DOI 10.1038/s41467-019-13362-4

  View details for PubMedID 31772158

• Energy storage: The future enabled by nanomaterials. Science (New York, N.Y.) Pomerantseva, E., Bonaccorso, F., Feng, X., Cui, Y., Gogotsi, Y. 2019; 366 (6468)

  Abstract

  Lithium-ion batteries, which power portable electronics, electric vehicles, and stationary storage, have been recognized with the 2019 Nobel Prize in chemistry. The development of nanomaterials and their related processing into electrodes and devices can improve the performance and/or development of the existing energy storage systems. We provide a perspective on recent progress in the application of nanomaterials in energy storage devices, such as supercapacitors and batteries. The versatility of nanomaterials can lead to power sources for portable, flexible, foldable, and distributable electronics; electric transportation; and grid-scale storage, as well as integration in living environments and biomedical systems. To overcome limitations of nanomaterials related to high reactivity and chemical instability caused by their high surface area, nanoparticles with different functionalities should be combined in smart architectures on nano- and microscales. The integration of nanomaterials into functional architectures and devices requires the development of advanced manufacturing approaches. We discuss successful strategies and outline a roadmap for the exploitation of nanomaterials for enabling future energy storage applications, such as powering distributed sensor networks and flexible and wearable electronics.

  View details for DOI 10.1126/science.aan8285

  View details for PubMedID 31753970

• Unravelling Degradation Mechanisms and Atomic Structure of Organic-Inorganic Halide Perovskites by Cryo-EM JOULE Li, Y., Zhou, W., Li, Y., Huang, W., Zhang, Z., Chen, G., Wang, H., Wu, G., Rolston, N., Vila, R., Chiu, W., Cui, Y. 2019; 3 (11): 2854–66

  View details for DOI 10.1016/j.joule.2019.08.016

  View details for Web of Science ID 000497987900024

• A Dynamic, Electrolyte-Blocking, and Single-Ion-Conductive Network for Stable Lithium-Metal Anodes JOULE Yu, Z., Mackanic, D. G., Michaels, W., Lee, M., Pei, A., Feng, D., Zhang, Q., Tsao, Y., Amanchukwu, C., Yan, X., Wang, H., Chen, S., Liu, K., Kang, J., Qin, J., Cui, Y., Bao, Z. 2019; 3 (11): 2761–76

  View details for DOI 10.1016/j.joule.2019.07.025

  View details for Web of Science ID 000497987900018

• Minimized lithium trapping by isovalent isomorphism for high initial Coulombic efficiency of silicon anodes. Science advances Zhu, B., Liu, G., Lv, G., Mu, Y., Zhao, Y., Wang, Y., Li, X., Yao, P., Deng, Y., Cui, Y., Zhu, J. 2019; 5 (11): eaax0651

  Abstract

  Silicon demonstrates great potential as a next-generation lithium ion battery anode because of high capacity and elemental abundance. However, the issue of low initial Coulombic efficiency needs to be addressed to enable large-scale applications. There are mainly two mechanisms for this lithium loss in the first cycle: the formation of the solid electrolyte interphase and lithium trapping in the electrode. The former has been heavily investigated while the latter has been largely neglected. Here, through both theoretical calculation and experimental study, we demonstrate that by introducing Ge substitution in Si with fine compositional control, the energy barrier of lithium diffusion will be greatly reduced because of the lattice expansion. This effect of isovalent isomorphism significantly reduces the Li trapping by ~70% and improves the initial Coulombic efficiency to over 90%. We expect that various systems of battery materials can benefit from this mechanism for fine-tuning their electrochemical behaviors.

  View details for DOI 10.1126/sciadv.aax0651

  View details for PubMedID 31763449

• Two-dimensional inorganic molecular crystals. Nature communications Han, W., Huang, P., Li, L., Wang, F., Luo, P., Liu, K., Zhou, X., Li, H., Zhang, X., Cui, Y., Zhai, T. 2019; 10 (1): 4728

  Abstract

  Two-dimensional molecular crystals, consisting of zero-dimensional molecules, are very appealing due to their novel physical properties. However, they are mostly limited to organic molecules. The synthesis of inorganic version of two-dimensional molecular crystals is still a challenge due to the difficulties in controlling the crystal phase and growth plane. Here, we design a passivator-assisted vapor deposition method for the growth of two-dimensional Sb2O3 inorganic molecular crystals as thin as monolayer. The passivator can prevent the heterophase nucleation and suppress the growth of low-energy planes, and enable the molecule-by-molecule lateral growth along high-energy planes. Using Raman spectroscopy and in situ transmission electron microscopy, we show that the insulating alpha-phase of Sb2O3 flakes can be transformed into semiconducting beta-phase under heat and electron-beam irradiation. Our findings can be extended to the controlled growth of other two-dimensional inorganic molecular crystals and open up opportunities for potential molecular electronic devices.

  View details for DOI 10.1038/s41467-019-12569-9

  View details for PubMedID 31624241

• Nonpolar Alkanes Modify Lithium-Ion Solvation for Improved Lithium Deposition and Stripping ADVANCED ENERGY MATERIALS Amanchukwu, C., Kong, X., Qin, J., Cui, Y., Bao, Z. 2019

  View details for DOI 10.1002/aenm.201902116

  View details for Web of Science ID 000487515200001

• Design of Hollow Nanostructures for Energy Storage, Conversion and Production ADVANCED MATERIALS Wang, J., Cui, Y., Wang, D. 2019; 31 (38)

  View details for DOI 10.1002/adma.201801993

  View details for Web of Science ID 000486253200004

• Monolithic solid-electrolyte interphases formed in fluorinated orthoformate-based electrolytes minimize Li depletion and pulverization NATURE ENERGY Cao, X., Ren, X., Zou, L., Engelhard, M. H., Huang, W., Wang, H., Matthews, B. E., Lee, H., Niu, C., Arey, B. W., Cui, Y., Wang, C., Xiao, J., Liu, J., Xu, W., Zhang, J. 2019; 4 (9): 796–805

  View details for DOI 10.1038/s41560-019-0464-5

  View details for Web of Science ID 000486098400014

• Preventing Li depletion and pulverization by monolithic SEI layer generated in fluorinated orthoformate based electrolytes Cao, X., Ren, X., Zou, L., Engelhard, M., Huang, W., Wang, H., Matthews, B., Lee, H., Niu, C., Arey, B., Cui, Y., Wang, C., Xiao, J., Liu, J., Xu, W., Zhang, J. AMER CHEMICAL SOC. 2019

  View details for Web of Science ID 000525055505258

• Intrinsically flexible redox-active polyurethanes for electrochemical energy storage Mackanic, D., Cui, Y., Bao, Z. AMER CHEMICAL SOC. 2019

  View details for Web of Science ID 000525055505221

• Scalable and facile preparation of SSNs for lithium metal stabilization Mackanic, D., Yu, Z., Cui, Y., Bao, Z. AMER CHEMICAL SOC. 2019

  View details for Web of Science ID 000525061501099

• Dynamic single-ion-conductive network as a stable lithium metal artificial solid electrolyte interphase in carbonate electrolyte Mackanic, D., Yu, Z., Cui, Y., Bao, Z. AMER CHEMICAL SOC. 2019

  View details for Web of Science ID 000525061504597

• Decoupling of mechanical properties and ionic conductivity in supramolecular stretchable battery materials Mackanic, D., Cui, Y., Bao, Z. AMER CHEMICAL SOC. 2019

  View details for Web of Science ID 000525061505168

• Understanding and redesigning metallic lithium for next-generation batteries Liu, Y., Lin, D., Lin, Y., Chen, G., Pei, A., Lie, Y., Cui, Y. AMER CHEMICAL SOC. 2019

  View details for Web of Science ID 000525061501211

• Self-Selective Catalyst Synthesis for CO2 Reduction JOULE Wang, H., Liang, Z., Tang, M., Chen, G., Li, Y., Chen, W., Lin, D., Zhang, Z., Zhou, G., Li, J., Lu, Z., Chan, K., Tan, T., Cui, Y. 2019; 3 (8): 1927–36

  View details for DOI 10.1016/j.joule.2019.05.023

  View details for Web of Science ID 000482204600015

• Cryo-EM Structures of Atomic Surfaces and Host-Guest Chemistry in Metal-Organic Frameworks MATTER Li, Y., Wang, K., Zhou, W., Li, Y., Vila, R., Huang, W., Wang, H., Chen, G., Wu, G., Tsao, Y., Wang, H., Sinclair, R., Chiu, W., Cui, Y. 2019; 1 (2): 428–38

  View details for DOI 10.1016/j.matt.2019.06.001

  View details for Web of Science ID 000519688200015

• Improving cyclability of Li metal batteries at elevated temperatures and its origin revealed by cryo-electron microscopy NATURE ENERGY Wang, J., Huang, W., Pei, A., Li, Y., Shi, F., Yu, X., Cui, Y. 2019; 4 (8): 664–70

  View details for DOI 10.1038/s41560-019-0413-3

  View details for Web of Science ID 000481484400014

• Superconductivity in an infinite-layer nickelate. Nature Li, D., Lee, K., Wang, B. Y., Osada, M., Crossley, S., Lee, H. R., Cui, Y., Hikita, Y., Hwang, H. Y. 2019; 572 (7771): 624–27

  Abstract

  The discovery of unconventional superconductivity in (La,Ba)2CuO4 (ref. 1) has motivated the study of compounds with similar crystal and electronic structure, with the aim of finding additional superconductors and understanding the origins of copper oxide superconductivity. Isostructural examples include bulk superconducting Sr2RuO4 (ref. 2) and surface-electron-doped Sr2IrO4, which exhibits spectroscopic signatures consistent with a superconducting gap3,4, although a zero-resistance state has not yet been observed. This approach has also led to the theoretical investigation of nickelates5,6, as well as thin-film heterostructures designed to host superconductivity. One such structure is the LaAlO3/LaNiO3 superlattice7-9, which has been recently proposed for the creation of an artificially layered nickelate heterostructure with a singly occupied [Formula: see text] band. The absence of superconductivity observed in previous related experiments has been attributed, at least in part, to incomplete polarization of the eg orbitals10. Here we report the observation of superconductivity in an infinite-layer nickelate that is isostructural to infinite-layer copper oxides11-13. Using soft-chemistry topotactic reduction14-20, NdNiO2 and Nd0.8Sr0.2NiO2 single-crystal thin films are synthesized by reducing the perovskite precursor phase. Whereas NdNiO2 exhibits a resistive upturn at low temperature, measurements of the resistivity, critical current density and magnetic-field response of Nd0.8Sr0.2NiO2 indicate a superconducting transition temperature of about 9 to 15 kelvin. Because this compound is a member of a series of reduced layered nickelate crystal structures21-23, these results suggest the possibility of a family of nickelate superconductors analogous to copper oxides24 and pnictides25.

  View details for DOI 10.1038/s41586-019-1496-5

  View details for PubMedID 31462797

• Challenges and opportunities towards fast-charging battery materials NATURE ENERGY Liu, Y., Zhu, Y., Cui, Y. 2019; 4 (7): 540–50

  View details for DOI 10.1038/s41560-019-0405-3

  View details for Web of Science ID 000474920100010

• An Autotransferable g-C3N4 Li+-Modulating Layer toward Stable Lithium Anodes ADVANCED MATERIALS Guo, Y., Niu, P., Liu, Y., Ouyang, Y., Li, D., Zhai, T., Li, H., Cui, Y. 2019; 31 (27)

  View details for DOI 10.1002/adma.201900342

  View details for Web of Science ID 000477981200010

• Surface-engineered mesoporous silicon microparticles as high-Coulombic-efficiency anodes for lithium-ion batteries NANO ENERGY Wang, J., Liao, L., Lee, H., Shi, F., Huang, W., Zhao, J., Pei, A., Tang, J., Zheng, X., Chen, W., Cui, Y. 2019; 61: 404–10

  View details for DOI 10.1016/j.nanoen.2019.04.070

  View details for Web of Science ID 000471201800048

• Temperature Regulation in Colored Infrared-Transparent Polyethylene Textiles JOULE Cai, L., Peng, Y., Xu, J., Zhou, C., Zhou, C., Wu, P., Lin, D., Fan, S., Cui, Y. 2019; 3 (6): 1478–86

  View details for DOI 10.1016/j.joule.2019.03.015

  View details for Web of Science ID 000472067900014

• Uniform High Ionic Conducting Lithium Sulfide Protection Layer for Stable Lithium Metal Anode ADVANCED ENERGY MATERIALS Chen, H., Pei, A., Lin, D., Xie, J., Yang, A., Xu, J., Lin, K., Wang, J., Wang, H., Shi, F., Boyle, D., Cui, Y. 2019; 9 (22)

  View details for DOI 10.1002/aenm.201900858

  View details for Web of Science ID 000471132800020

• Ultrathin, flexible, solid polymer composite electrolyte enabled with aligned nanoporous host for lithium batteries. Nature nanotechnology Wan, J., Xie, J., Kong, X., Liu, Z., Liu, K., Shi, F., Pei, A., Chen, H., Chen, W., Chen, J., Zhang, X., Zong, L., Wang, J., Chen, L., Qin, J., Cui, Y. 2019

  Abstract

  The urgent need for safer batteries is leading research to all-solid-state lithium-based cells. To achieve energy density comparable to liquid electrolyte-based cells, ultrathin and lightweight solid electrolytes with high ionic conductivity are desired. However, solid electrolytes with comparable thicknesses to commercial polymer electrolyte separators (~10mum) used in liquid electrolytes remain challenging to make because of the increased risk of short-circuiting the battery. Here, we report on a polymer-polymer solid-state electrolyte design, demonstrated with an 8.6-mum-thick nanoporous polyimide (PI) film filled with polyethylene oxide/lithium bis(trifluoromethanesulfonyl)imide (PEO/LiTFSI) that can be used as a safe solid polymer electrolyte. The PI film is nonflammable and mechanically strong, preventing batteries from short-circuiting even after more than 1,000h of cycling, and the vertical channels enhance the ionic conductivity (2.3*10-4Scm-1 at 30°C) of the infused polymer electrolyte. All-solid-state lithium-ion batteries fabricated with PI/PEO/LiTFSI solid electrolyte show good cycling performance (200 cycles at C/2 rate) at 60°C and withstand abuse tests such as bending, cutting and nail penetration.

  View details for DOI 10.1038/s41565-019-0465-3

  View details for PubMedID 31133663

• Direct/Alternating Current Electrochemical Method for Removing and Recovering Heavy Metal from Water Using Graphene Oxide Electrode. ACS nano Liu, C., Wu, T., Hsu, P., Xie, J., Zhao, J., Liu, K., Sun, J., Xu, J., Tang, J., Ye, Z., Lin, D., Cui, Y. 2019

  Abstract

  Treatment of heavy-metal pollution in both point-of-use water and industrial wastewater is critical in protecting human health and the environment. Current methods for heavy-metal treatment in both sources have limitations. For point-of-use water, current methods usually suffer from limited capacity and difficulties in spontaneously removing multiple heavy metals. For industrial wastewater, current methods greatly reduce the value of heavy metal by precipitating them as sludge which requires further treatment. Here we developed an electrochemical method that can treat both low-concentration and high-concentration heavy-metal pollution using either direct current (DC) or alternating current (AC) electrodeposition with graphene-oxide-modified carbon felt electrode (CF-GO). The graphene oxide provides a high density of surface functional groups to assist the electrodeposition. The electrodeposition method showed 2 orders of magnitude higher capacity (>29 g heavy metal for 1 g of graphene oxide) compared with traditional adsorption methods. For low levels of heavy-metal pollution in point-of-use water, DC electrodeposition with a CF-GO electrode can reduce single heavy-metal ion pollution (Cu, Cd, and Pb) as well as multiple ion mixtures to below safe water drinking levels. This method can tolerate a much wider range of heavy-metal pollution in point-of-use water than traditional adsorption methods. For high-level pollution in industrial wastewater, AC electrodeposition can recover >99.9% heavy-metal ions. By tuning the AC frequency and voltage, the electrodeposition method can further selectively recover Cu, Cd, and Pb separately, which adds values to the heavy-metal removal process.

  View details for DOI 10.1021/acsnano.8b09301

  View details for PubMedID 31117369

• Fast lithium growth and short circuit induced by localized-temperature hotspots in lithium batteries. Nature communications Zhu, Y., Xie, J., Pei, A., Liu, B., Wu, Y., Lin, D., Li, J., Wang, H., Chen, H., Xu, J., Yang, A., Wu, C., Wang, H., Chen, W., Cui, Y. 2019; 10 (1): 2067

  Abstract

  Fast-charging and high-energy-density batteries pose significant safety concerns due to high rates of heat generation. Understanding how localized high temperatures affect the battery is critical but remains challenging, mainly due to the difficulty of probing battery internal temperature with high spatial resolution. Here we introduce a method to induce and sense localized high temperature inside a lithium battery using micro-Raman spectroscopy. We discover that temperature hotspots can induce significant lithium metal growth as compared to the surrounding lower temperature area due to the locally enhanced surface exchange current density. More importantly, localized high temperature can be one of the factors to cause battery internal shorting, which further elevates the temperature and increases the risk of thermal runaway. This work provides important insights on the effects of heterogeneous temperatures within batteries and aids the development of safer batteries, thermal management schemes, and diagnostic tools.

  View details for PubMedID 31061393

• Fast lithium growth and short circuit induced by localized-temperature hotspots in lithium batteries NATURE COMMUNICATIONS Zhu, Y., Xie, J., Pei, A., Liu, B., Wu, Y., Lin, D., Li, J., Wang, H., Chen, H., Xu, J., Yang, A., Wu, C., Wang, H., Chen, W., Cui, Y. 2019; 10

  View details for DOI 10.1038/s41467-019-09924-1

  View details for Web of Science ID 000466871300003

• High-Rate and Large-Capacity Lithium Metal Anode Enabled by Volume Conformal and Self-Healable Composite Polymer Electrolyte ADVANCED SCIENCE Xia, S., Lopez, J., Liang, C., Zhang, Z., Bao, Z., Cui, Y., Liu, W. 2019; 6 (9)

  View details for DOI 10.1002/advs.201802353

  View details for Web of Science ID 000467524500005

• Bright sub-20-nm cathodoluminescent nanoprobes for electron microscopy NATURE NANOTECHNOLOGY Prigozhin, M. B., Maurer, P. C., Courtis, A. M., Liu, N., Wisser, M. D., Siefe, C., Tian, B., Chan, E., Song, G., Fischer, S., Aloni, S., Ogletree, D., Barnard, E. S., Joubert, L., Rao, J., Alivisatos, A., Macfarlane, R. M., Cohen, B. E., Cui, Y., Dionne, J. A., Chu, S. 2019; 14 (5): 420-+

  View details for DOI 10.1038/s41565-019-0395-0

  View details for Web of Science ID 000467053100016

• Designing polymers for advanced battery chemistries NATURE REVIEWS MATERIALS Lopez, J., Mackanic, D. G., Cui, Y., Bao, Z. 2019; 4 (5): 312–30

  View details for DOI 10.1038/s41578-019-0103-6

  View details for Web of Science ID 000467301000006

• Aqueous Zinc-Ion Storage in MoS2 by Tuning the Intercalation Energy NANO LETTERS Liang, H., Cao, Z., Ming, F., Zhang, W., Anjum, D. H., Cui, Y., Cavallo, L., Alshareef, H. N. 2019; 19 (5): 3199–3206

  View details for DOI 10.1021/acs.nanolett.9b00697

  View details for Web of Science ID 000467781900056

• In Situ X-ray Absorption Spectroscopic Investigation of the Capacity Degradation Mechanism in Mg/S Batteries NANO LETTERS Xu, Y., Ye, Y., Zhao, S., Feng, J., Li, J., Chen, H., Yang, A., Shi, F., Jia, L., Wu, Y., Yu, X., Glans-Suzuki, P., Cui, Y., Guo, J., Zhang, Y. 2019; 19 (5): 2928–34

  View details for DOI 10.1021/acs.nanolett.8b05208

  View details for Web of Science ID 000467781900021

• Amidoxime-Functionalized Macroporous Carbon Self-Refreshed Electrode Materials for Rapid and High-Capacity Removal of Heavy Metal from Water. ACS central science Wu, T., Liu, C., Kong, B., Sun, J., Gong, Y., Liu, K., Xie, J., Pei, A., Cui, Y. 2019; 5 (4): 719–26

  Abstract

  Heavy metal pollution continues to be one of the most serious environmental problems which has attracted major global concern. Here, a rapid, high-capacity, yet economical strategy for deep cleaning of heavy metals ions in water is reported based on amidoxime-functionalized macroporous carbon electrode materials. The active sites of our material can be self-refreshed during the electrochemical removal process, which is different from traditional methods. The novel filter device in this work can purify contaminated water very rapidly (3000 L h-1 m-2), and can decrease heavy metal ion concentrations to below 5 ppb with a very short contact time (only 3 s). The original treatment efficiency of the device can be retained even after 1 week of continuous device operation. An extremely high removal capacity of over 2300 mg g-1 can be achieved with 2-3 orders of magnitude higher efficiency than that of surface adsorption-based commercial filters without any decay. Additionally, the cost of energy consumed in our method is lower than $6.67 * 10-3 per ton of wastewater. We envision that this approach can be routinely applied for the rapid, efficient, and thorough removal of heavy metals from both point-of-use water and industrial wastewater.

  View details for PubMedID 31041392

• Amidoxime-Functionalized Macroporous Carbon Self-Refreshed Electrode Materials for Rapid and High-Capacity Removal of Heavy Metal from Water ACS CENTRAL SCIENCE Wu, T., Liu, C., Kong, B., Sun, J., Gong, Y., Liu, K., Xie, J., Pei, A., Cui, Y. 2019; 5 (4): 719–26

  View details for DOI 10.1021/acscentsci.9b00130

  View details for Web of Science ID 000465530600020

• Design of Red Phosphorus Nanostructured Electrode for Fast-Charging Lithium-Ion Batteries with High Energy Density JOULE Sun, Y., Wang, L., Li, Y., Li, Y., Lee, H., Pei, A., He, X., Cui, Y. 2019; 3 (4): 1080–93

  View details for DOI 10.1016/j.joule.2019.01.017

  View details for Web of Science ID 000465149000019

• Aqueous Zinc-Ion Storage in MoS2 by Tuning the Intercalation Energy. Nano letters Liang, H., Cao, Z., Ming, F., Zhang, W., Anjum, D. H., Cui, Y., Cavallo, L., Alshareef, H. N. 2019

  Abstract

  Aqueous Zn-ion batteries present low-cost, safe, and high-energy battery technology but suffer from the lack of suitable cathode materials because of the sluggish intercalation kinetics associated with the large size of hydrated zinc ions. Herein we report an effective and general strategy to transform inactive intercalation hosts into efficient Zn2+ storage materials through intercalation energy tuning. Using MoS2 as a model system, we show both experimentally and theoretically that even hosts with an originally poor Zn2+ diffusivity can allow fast Zn2+ diffusion. Through simple interlayer spacing and hydrophilicity engineering that can be experimentally achieved by oxygen incorporation, the Zn2+ diffusivity is boosted by 3 orders of magnitude, effectively enabling the otherwise barely active MoS2 to achieve a high capacity of 232 mAh g-1, which is 10 times that of its pristine form. The strategy developed in our work can be generally applied for enhancing the ion storage capacity of metal chalcogenides and other layered materials, making them promising cathodes for challenging multivalent ion batteries.

  View details for PubMedID 30986352

• Practical Challenges and Future Perspectives of All-Solid-State Lithium-Metal Batteries CHEM Xia, S., Wu, X., Zhang, Z., Cui, Y., Liu, W. 2019; 5 (4): 753–85

  View details for DOI 10.1016/j.chempr.2018.11.013

  View details for Web of Science ID 000464241700008

• In Situ X-ray Absorption Spectroscopic Investigation of the Capacity Degradation Mechanism in Mg/S Batteries. Nano letters Xu, Y., Ye, Y., Zhao, S., Feng, J., Li, J., Chen, H., Yang, A., Shi, F., Jia, L., Wu, Y., Yu, X., Glans-Suzuki, P., Cui, Y., Guo, J., Zhang, Y. 2019

  Abstract

  The Mg/S battery is attractive because of its high theoretical energy density and the abundance of Mg and S on the earth. However, its development is hindered by the lack of understanding to the underlying electrochemical reaction mechanism of its charge-discharge processes. Here, using a unique in situ X-ray absorption spectroscopic tool, we systematically study the reaction pathways of the Mg/S cells in Mg(HMDS)2-AlCl3 electrolyte. We find that the capacity degradation is mainly due to the formation of irreversible discharge products, such as MgS and Mg3S8, through a direct electrochemical deposition or a chemical disproportionation of intermediate polysulfide. In light of the fundamental understanding, we propose to use TiS2 as a catalyst to activate the irreversible reaction of low-order MgS x and MgS, which results in an increased discharging capacity up to 900 mAh·g-1 and a longer cycling life.

  View details for PubMedID 30932498

• Quasi-Ballistic Thermal Transport Across MoS2 Thin Films NANO LETTERS Sood, A., Xiong, F., Chen, S., Cheaito, R., Lian, F., Asheghi, M., Cui, Y., Donadio, D., Goodson, K. E., Pop, E. 2019; 19 (4): 2434–42

  View details for DOI 10.1021/acs.nanolett.8b05174

  View details for Web of Science ID 000464769100032

• Fast galvanic lithium corrosion involving a Kirkendall-type mechanism NATURE CHEMISTRY Lin, D., Liu, Y., Li, Y., Li, Y., Pei, A., Xie, J., Huang, W., Cui, Y. 2019; 11 (4): 382–89

  View details for DOI 10.1038/s41557-018-0203-8

  View details for Web of Science ID 000462046600017

• Effects of polymer coatings on electrodeposited lithium metal Lopez, J., Pei, A., Cui, Y., Bao, Z. AMER CHEMICAL SOC. 2019

  View details for Web of Science ID 000478860505895

• Designing a Quinone-Based Redox Mediator to Facilitate Li2S Oxidation in Li-S Batteries JOULE Tsao, Y., Lee, M., Miller, E. C., Gao, G., Park, J., Chen, S., Katsumata, T., Tran, H., Wang, L., Toney, M. F., Cui, Y., Bao, Z. 2019; 3 (3): 872–84

  View details for DOI 10.1016/j.joule.2018.12.018

  View details for Web of Science ID 000462010600022

• Quasi-Ballistic Thermal Transport Across MoS2 Thin Films. Nano letters Sood, A., Xiong, F., Chen, S., Cheaito, R., Lian, F., Asheghi, M., Cui, Y., Donadio, D., Goodson, K. E., Pop, E. 2019

  Abstract

  Layered two-dimensional (2D) materials have highly anisotropic thermal properties between the in-plane and cross-plane directions. Conventionally, it is thought that cross-plane thermal conductivities (kappa z) are low, and therefore c-axis phonon mean free paths (MFPs) are small. Here, we measure kappa z across MoS2 films of varying thickness (20-240 nm) and uncover evidence of very long c-axis phonon MFPs at room temperature in these layered semiconductors. Experimental data obtained using time-domain thermoreflectance (TDTR) are in good agreement with first-principles density functional theory (DFT). These calculations suggest that 50% of the heat is carried by phonons with MFP > 200 nm, exceeding kinetic theory estimates by nearly 2 orders of magnitude. Because of quasi-ballistic effects, the kappa z of nanometer-thin films of MoS2 scales with theirthickness and the volumetric thermal resistance asymptotes to a nonzero value, 10 m2 K GW-1. This contributes as much as 30% to the total thermal resistance of a 20 nm thick film, the rest being limited by thermal interface resistance with the SiO2 substrate and top-side aluminum transducer. These findings are essential for understanding heat flow across nanometer-thin films of MoS2 for optoelectronic and thermoelectric applications.

  View details for PubMedID 30808167

• Bright sub-20-nm cathodoluminescent nanoprobes for electron microscopy. Nature nanotechnology Prigozhin, M. B., Maurer, P. C., Courtis, A. M., Liu, N., Wisser, M. D., Siefe, C., Tian, B., Chan, E., Song, G., Fischer, S., Aloni, S., Ogletree, D. F., Barnard, E. S., Joubert, L., Rao, J., Alivisatos, A. P., Macfarlane, R. M., Cohen, B. E., Cui, Y., Dionne, J. A., Chu, S. 2019

  Abstract

  Electron microscopy has been instrumental in our understanding of complex biological systems. Although electron microscopy reveals cellular morphology with nanoscale resolution, it does not provide information on the location of different types of proteins. An electron-microscopy-based bioimaging technology capable of localizing individual proteins and resolving protein-protein interactions with respect to cellular ultrastructure would provide important insights into the molecular biology of a cell. Here, we synthesize small lanthanide-doped nanoparticles and measure the absolute photon emission rate of individual nanoparticles resulting from a given electron excitation flux (cathodoluminescence). Our results suggest that the optimization of nanoparticle composition, synthesis protocols and electron imaging conditions can lead to sub-20-nm nanolabels that would enable high signal-to-noise localization of individual biomolecules within a cellular context. In ensemble measurements, these labels exhibit narrow spectra of nine distinct colours, so the imaging of biomolecules in a multicolour electron microscopy modality may be possible.

  View details for PubMedID 30833691

• Composite lithium electrode with mesoscale skeleton via simple mechanical deformation. Science advances Liang, Z., Yan, K., Zhou, G., Pei, A., Zhao, J., Sun, Y., Xie, J., Li, Y., Shi, F., Liu, Y., Lin, D., Liu, K., Wang, H., Wang, H., Lu, Y., Cui, Y. 2019; 5 (3): eaau5655

  Abstract

  Lithium metal-based batteries are attractive energy storage devices because of high energy density. However, uncontrolled dendrite growth and virtually infinite volume change, which cause performance fading and safety concerns, have limited their applications. Here, we demonstrate that a composite lithium metal electrode with an ion-conducting mesoscale skeleton can improve electrochemical performance by locally reducing the current density. In addition, the potential for short-circuiting is largely alleviated due to side deposition of mossy lithium on the three-dimensional electroactive surface of the composite electrode. Moreover, the electrode volume only slightly changes with the support of a rigid and stable scaffold. Therefore, this mesoscale composite electrode can cycle stably for 200 cycles with low polarization under a high areal current density up to 5 mA/cm2. Most attractively, the proposed fabrication process, which only involves simple mechanical deformation, is scalable and cost effective, providing a new strategy for developing high performance and long lifespan lithium anodes.

  View details for PubMedID 30899782

• Pathways for practical high-energy long-cycling lithium metal batteries NATURE ENERGY Liu, J., Bao, Z., Cui, Y., Dufek, E. J., Goodenough, J. B., Khalifah, P., Li, Q., Liaw, B., Liu, P., Manthiram, A., Meng, Y., Subramanian, V. R., Toney, M. F., Viswanathan, V. V., Whittingham, M., Xiao, J., Xu, W., Yang, J., Yang, X., Zhang, J. 2019; 4 (3): 180–86

  View details for DOI 10.1038/s41560-019-0338-x

  View details for Web of Science ID 000461124600009

• Breathing-Mimicking Electrocatalysis for Oxygen Evolution and Reduction JOULE Li, J., Zhu, Y., Chen, W., Lu, Z., Xu, J., Pei, A., Peng, Y., Zheng, X., Zhang, Z., Chu, S., Cui, Y. 2019; 3 (2): 557–69

  View details for DOI 10.1016/j.joule.2018.11.015

  View details for Web of Science ID 000460076100021

• Improving a Mg/S Battery with YCl3 Additive and Magnesium Polysulfide ADVANCED SCIENCE Xu, Y., Zhou, G., Zhao, S., Li, W., Shi, F., Li, J., Feng, J., Zhao, Y., Wu, Y., Guo, J., Cui, Y., Zhang, Y. 2019; 6 (4): 1800981

  Abstract

  Rechargeable magnesium/sulfur (Mg/S) batteries are widely regarded as one of the alternatives to lithium-ion batteries. However, a key factor restricting their application is the lack of suitable electrolyte. Herein, an electrolyte additive that can reduce the polarization voltage is developed and 98.7% coulombic efficiency is realized. The as-prepared Mg-ion electrolyte exhibits excellent Mg plating/stripping performance with a low overpotential of 0.11 V for plating process, and high anodic stability up to 3.0 V (vs Mg/Mg2+). When it is coupled with magnesium polysulfide, which has high reactivity and is homogeneously distributed on carbon matrix, the Mg/S cells deliver a good cycling stability with a high discharge capacity over 1000 mAh g-1 for more than 50 cycles.

  View details for PubMedID 30828520

• An Interconnected Channel-Like Framework as Host for Lithium Metal Composite Anodes ADVANCED ENERGY MATERIALS Wang, H., Lin, D., Xie, J., Liu, Y., Chen, H., Li, Y., Xu, J., Zhou, G., Zhang, Z., Pei, A., Zhu, Y., Liu, K., Wang, K., Cui, Y. 2019; 9 (7)

  View details for DOI 10.1002/aenm.201802720

  View details for Web of Science ID 000458912300009

• Wrinkled Graphene Cages as Hosts for High-Capacity Li Metal Anodes Shown by Cryogenic Electron Microscopy. Nano letters Wang, H., Li, Y., Li, Y., Liu, Y., Lin, D., Zhu, C., Chen, G., Yang, A., Yan, K., Chen, H., Zhu, Y., Li, J., Xie, J., Xu, J., Zhang, Z., Vila, R., Pei, A., Wang, K., Cui, Y. 2019

  Abstract

  Lithium (Li) metal has long been considered the "holy grail" of battery anode chemistry but is plagued by low efficiency and poor safety due to its high chemical reactivity and large volume fluctuation, respectively. Here we introduce a new host of wrinkled graphene cage (WGC) for Li metal. Different from recently reported amorphous carbon spheres, WGC show highly improved mechanical stability, better Li ion conductivity, and excellent solid electrolyte interphase (SEI) for continuous robust Li metal protection. At low areal capacities, Li metal is preferentially deposited inside the graphene cage. Cryogenic electron microscopy characterization shows that a uniform and stable SEI forms on the WGC surface that can shield the Li metal from direct exposure to electrolyte. With increased areal capacities, Li metal is plated densely and homogeneously into the outer pore spaces between graphene cages with no dendrite growth or volume change. As a result, a high Coulombic efficiency (CE) of 98.0% was achieved under 0.5 mA/cm2 and 1-10 mAh/cm2 in commercial carbonate electrolytes, and a CE of 99.1% was realized with high-concentration electrolytes under 0.5 mA/cm2 and 3 mAh/cm2. Full cells using WGC electrodes with prestored Li paired with Li iron phosphate showed greatly improved cycle lifetime. With 10 mAh/cm2 Li metal deposition, the WGC/Li compositeanodewas able to provide a high specific capacity of 2785 mAh/g. With its roll-to-roll compatible fabrication procedure, WGC serves as a highly promising material for the practical realization of Li metal anodes in next-generation high energy density secondary batteries.

  View details for PubMedID 30676759

• Mitigation of Shuttle Effect in Li-S Battery Using a Self-Assembled Ultrathin Molybdenum Disulfide Interlayer ACS APPLIED MATERIALS & INTERFACES Yu, X., Zhou, G., Cui, Y. 2019; 11 (3): 3080–86

  Abstract

  Lithium-sulfur batteries are promising for low-cost and high energy storage, but their applications are still limited by poor cycling stability owing to soluble lithium polysulfide shuttling during battery operation. Avoiding shuttle effect is challenging but essential to avoid active material loss and prevent performance decay. Here we use an ultrathin layer of MoS2 with thickness of 10-40 nm, which is 1-2 orders of magnitude thinner than conventional interlayers, for Li-S batteries to mitigate polysulfide shuttling. The MoS2 layer formed by exfoliated nanoflakes is deposited by a scalable liquid-based self-assembly method. With less than 1% of additional weight in the cathode, the MoS2 interlayer with complete coverage inhibits polysulfide diffusion across the separator, and therefore remarkably improves the battery performances. Reversible specific capacity reaches 1010 mA h g-1 and 600 mAh g-1 at 0.5 C and 2 C rate, respectively, which decay slowly over 400 cycles (0.11% per cycle). Moreover, the MoS2 film with high density of catalytic active flake edges enable high areal sulfur loading up to 10 mg cm-2 and areal capacity up to 9.7 mA h cm-2 at 3.2 mA cm-2 current density.

  View details for PubMedID 30588794

• Machine Learning-Assisted Discovery of Solid Li-Ion Conducting Materials CHEMISTRY OF MATERIALS Sendek, A. D., Cubuk, E. D., Antoniuk, E. R., Cheon, G., Cui, Y., Reed, E. J. 2019; 31 (2): 342–52

  View details for DOI 10.1021/acs.chemmater.8b03272

  View details for Web of Science ID 000456749800007

• Fast galvanic lithium corrosion involving a Kirkendall-type mechanism. Nature chemistry Lin, D., Liu, Y., Li, Y., Li, Y., Pei, A., Xie, J., Huang, W., Cui, Y. 2019

  Abstract

  Developing a viable metallic lithium anode is a prerequisite for next-generation batteries. However, the low redox potential of lithium metal renders it prone to corrosion, which must be thoroughly understood for it to be used in practical energy-storage devices. Here we report a previously overlooked mechanism by which lithium deposits can corrode on a copper surface. Voids are observed in the corroded deposits and a Kirkendall-type mechanism is validated through electrochemical analysis. Although it is a long-held view that lithium corrosion in electrolytes involves direct charge-transfer through the lithium-electrolyte interphase, the corrosion observed here is found to be governed by a galvanic process between lithium and the copper substrate-a pathway largely neglected by previous battery corrosion studies. The observations are further rationalized by detailed analyses of the solid-electrolyte interphase formed on copper and lithium, where the disparities in electrolyte reduction kinetics on the two surfaces can account for the fast galvanic process.

  View details for PubMedID 30664717

• Direct electrochemical generation of supercooled sulfur microdroplets well below their melting temperature. Proceedings of the National Academy of Sciences of the United States of America Liu, N., Zhou, G., Yang, A., Yu, X., Shi, F., Sun, J., Zhang, J., Liu, B., Wu, C., Tao, X., Sun, Y., Cui, Y., Chu, S. 2019

  Abstract

  Supercooled liquid sulfur microdroplets were directly generated from polysulfide electrochemical oxidation on various metal-containing electrodes. The sulfur droplets remain liquid at 155 °C below sulfur's melting point (T m = 115 °C), with fractional supercooling change (T m - T sc)/T m larger than 0.40. In operando light microscopy captured the rapid merging and shape relaxation of sulfur droplets, indicating their liquid nature. Micropatterned electrode and electrochemical current allow precise control of the location and size of supercooled microdroplets, respectively. Using this platform, we initiated and observed the rapid solidification of supercooled sulfur microdroplets upon crystalline sulfur touching, which confirms supercooled sulfur's metastability at room temperature. In addition, the formation of liquid sulfur in electrochemical cell enriches lithium-sulfur-electrolyte phase diagram and potentially may create new opportunities for high-energy Li-S batteries.

  View details for PubMedID 30602455

• Remediation of heavy metal contaminated soil by asymmetrical alternating current electrochemistry. Nature communications Xu, J. n., Liu, C. n., Hsu, P. C., Zhao, J. n., Wu, T. n., Tang, J. n., Liu, K. n., Cui, Y. n. 2019; 10 (1): 2440

  Abstract

  Soil contamination by heavy metals constitutes an important environmental problem, whereas field applicability of existing remediation technologies has encountered numerous obstacles, such as long operation time, high chemical cost, large energy consumption, secondary pollution, and soil degradation. Here we report the design and demonstration of a remediation method based on a concept of asymmetrical alternating current electrochemistry that achieves high degrees of contaminant removal for different heavy metals (copper, lead, cadmium) at different initial concentrations (from 100 to 10,000 ppm), all reaching corresponding regulation levels for residential scenario after rational treatment time (from 30 min to 6 h). No excessive nutrient loss in treated soil is observed and no secondary toxic product is produced. Long-term experiment and plant assay show the high sustainability of the method and its feasibility for agricultural use.

  View details for DOI 10.1038/s41467-019-10472-x

  View details for PubMedID 31164649

• Charge-Free Mixing Entropy Battery Enabled by Low-Cost Electrode Materials. ACS omega Ye, M. n., Pasta, M. n., Xie, X. n., Dubrawski, K. L., Xu, J. n., Liu, C. n., Cui, Y. n., Criddle, C. S. 2019; 4 (7): 11785–90

  Abstract

  Salinity gradients are a vast and untapped energy resource. For every cubic meter of freshwater that mixes with seawater, approximately 0.65 kW h of theoretically recoverable energy is lost. For coastal wastewater treatment plants that discharge to the ocean, this energy, if recovered, could power the plant. The mixing entropy battery (MEB) uses battery electrodes to convert salinity gradient energy into electricity in a four-step process: (1) freshwater exchange; (2) charging in freshwater; (3) seawater exchange; and (4) discharging in seawater. Previously, we demonstrated a proof of concept, but with electrode materials that required an energy investment during the charging step. Here, we introduce a charge-free MEB with low-cost electrodes: Prussian Blue (PB) and polypyrrole (PPy). Importantly, this MEB requires no energy investment, and the electrode materials are stable with repeated cycling. The MEB equipped with PB and PPy achieved high voltage ratios (actual voltages obtained divided by the theoretical voltages) of 89.5% in wastewater effluent and 97.6% in seawater, with over 93% capacity retention after 50 cycles of operation and 97-99% over 150 cycles with a polyvinyl alcohol/sulfosuccinic acid (PVA/SSA) coating on the PB electrode.

  View details for DOI 10.1021/acsomega.9b00863

  View details for PubMedID 31460286

  View details for PubMedCentralID PMC6682144

• A Two-Dimensional MoS2 Catalysis Transistor by Solid-State Ion Gating Manipulation and Adjustment (SIGMA). Nano letters Wu, Y. n., Ringe, S. n., Wu, C. L., Chen, W. n., Yang, A. n., Chen, H. n., Tang, M. n., Zhou, G. n., Hwang, H. Y., Chan, K. n., Cui, Y. n. 2019

  Abstract

  A variety of methods including tuning chemical compositions, structures, crystallinity, defects and strain, and electrochemical intercalation have been demonstrated to enhance the catalytic activity. However, none of these tuning methods provide direct dynamical control during catalytic reactions. Here we propose a new method to tune the activity of catalysts through solid-state ion gating manipulation and adjustment (SIGMA) using a catalysis transistor. SIGMA can electrostatically dope the surface of catalysts with a high electron concentration over 5 × 1013 cm-2 and thus modulate both the chemical potential of the reaction intermediates and their electrical conductivity. The hydrogen evolution reaction (HER) on both pristine and defective MoS2 were investigated as model reactions. Our theoretical and experimental results show that the overpotential at 10 mA/cm2 and Tafel slope can be in situ, continuously, dynamically, and reversibly tuned over 100 mV and around 100 mV/dec, respectively.

  View details for DOI 10.1021/acs.nanolett.9b02888

  View details for PubMedID 31499003

• Nanowires for Electrochemical Energy Storage. Chemical reviews Zhou, G. n., Xu, L. n., Hu, G. n., Mai, L. n., Cui, Y. n. 2019

  Abstract

  Nanomaterials provide many desirable properties for electrochemical energy storage devices due to their nanoscale size effect, which could be significantly different from bulk or micron-sized materials. Particularly, confined dimensions play important roles in determining the properties of nanomaterials, such as the kinetics of ion diffusion, the magnitude of strain/stress, and the utilization of active materials. Nanowires, as one of the representative one-dimensional nanomaterials, have great capability for realizing a variety of applications in the fields of energy storage since they could maintain electron transport along the long axis and have a confinement effect across the diameter. In this review, we give a systematic overview of the state-of-the-art research progress on nanowires for electrochemical energy storage, from rational design and synthesis, in situ structural characterizations, to several important applications in energy storage including lithium-ion batteries, lithium-sulfur batteries, sodium-ion batteries, and supercapacitors. The problems and limitations in electrochemical energy storage and the advantages in utilizing nanowires to address the issues and improve the device performance are pointed out. At the end, we also discuss the challenges and demonstrate the prospective for the future development of advanced nanowire-based energy storage devices.

  View details for DOI 10.1021/acs.chemrev.9b00326

  View details for PubMedID 31566351

• Elaboration of Aggregated Polysulfide Phases: From Molecules to Large Clusters and Solid Phases. Nano letters Xiao, J. n., Zhou, G. n., Chen, H. n., Feng, X. n., Legut, D. n., Fan, Y. n., Wang, T. n., Cui, Y. n., Zhang, Q. n. 2019

  Abstract

  With the increasing strategies aimed at repressing shuttle problems in the lithium-sulfur battery, dissolved contents of polysulfides are significantly reduced. Except for solid-state Li2S2 and Li2S, aggregated phases of polysulfides remain unexplored, especially in well confined cathode material systems. Here, we report a series of nanosize polysulfide clusters and solid phases from an atomic perspective. The calculated phase diagram and formation energy evolution process demonstrate their stabilities and cohesive tendency. It is interesting to find that Li2S6 can stay in the solid state and contains short S3 chains, further leading to the unique stability and dense structure. Simulated electronic properties indicate reduced band gaps when polysulfides are aggregated, especially for solid phase Li2S6 with a band gap as low as 0.47 eV. Their dissolution behavior and conversion process are also investigated, which provides a more realistic model and gives further suggestions on the future design of the lithium-sulfur battery.

  View details for DOI 10.1021/acs.nanolett.9b03297

  View details for PubMedID 31509421

• Dynamic Structure and Chemistry of the Silicon Solid-Electrolyte Interphase Visualized by Cryogenic Electron Microscopy Matter Huang, W., Wang, J., Braun, M. R., Zhang, Z., Li, Y., Boyle, D. T., McIntyre, P. C., Cui, Y. 2019; 1 (5)

  View details for DOI 10.1016/j.matt.2019.09.020

• Nanostructural and Electrochemical Evolution of the Solid-Electrolyte Interphase on CuO Nanowires Revealed by Cryogenic-Electron Microscopy and Impedance Spectroscopy ACS NANO Huang, W., Boyle, D. T., Li, Y., Li, Y., Pei, A., Chen, H., Cui, Y. 2019; 13 (1): 737–44

  Abstract

  Battery performance is critically dependent on the nanostructure and electrochemical properties of the solid-electrolyte interphase (SEI) - a passivation film that exists on most lithium battery anodes. However, knowledge of how the SEI nanostructure forms and its impact on ionic transport remains limited due to its sensitivity to transmission electron microscopy and difficulty in accurately probing the SEI impedance. Here, we track the voltage-dependent, stepwise evolution of the nanostructure and impedance of the SEI on CuO nanowires using cryogenic-electron microscopy (cryo-EM) and electrochemical impedance spectroscopy (EIS). In carbonate electrolyte, the SEI forms at 1.0 V vs Li/Li+ as a 3 nm-thick amorphous SEI and grows to 4 nm at 0.5 V; as the potential approaches 0.0 V vs Li/Li+, the SEI on the CuO nanowires forms an 8 nm-thick inverted multilayered nanostructure in ethylene carbonate/diethyl carbonate (EC/DEC) electrolyte with 10 vol. % fluoroethylene carbonate (FEC) and a mosaic nanostructure in EC/DEC electrolyte. Upon Li deposition, the total SEI thickness grows to 16 nm and significant growth of the inner amorphous layer takes place in the inverted multilayered nanostructure, indicating electrolyte permeates the SEI. Using a refined EIS methodology, we isolate the SEI impedance on Cu and find that the SEI nanostructure directly correlates to macroscopic Li-ion transport through the SEI. The inverted layered nanostructure decreases the interfacial impedance upon formation, whereas the mosaic nanostructure continually increases the interfacial impedance during growth. These structural and electrochemical findings illustrate a more complete portrait of SEI formation and guide further improvements in engineered SEI.

  View details for DOI 10.1021/acsnano.8b08012

  View details for Web of Science ID 000456749900075

  View details for PubMedID 30589528

• Temperature-dependent Nucleation and Growth of Dendrite-free Lithium Metal Anodes. Angewandte Chemie (International ed. in English) Yan, K. n., Wang, J. n., Zhao, S. n., Zhou, D. n., Sun, B. n., Cui, Y. n., Wang, G. n. 2019

  Abstract

  It is essential to develop a facile and effective method to enhance the electrochemical performance of lithium (Li) metal anodes for building high-energy-density Li-metal based batteries. Herein, we explored the temperature-dependent Li nucleation and growth behavior and constructed a dendrite-free Li metal anode by elevating temperature from room temperature (20 °C) to 60 °C. A series of ex situ and in situ microscope investigations demonstrate that increasing Li deposition temperature results in large nuclei size, low nucleation density and compact growth of Li metal. We reveal that the enhanced lithiophilicity and the increased Li ion diffusion coefficient in aprotic electrolytes at high temperature are essential factors contributing to the dendrite-free Li growth behavior. As anodes in both half cells and full cells, the compact deposited Li with minimized specific surface area delivered high Coulombic efficiencies and long cycling stability at 60 °C.

  View details for DOI 10.1002/anie.201905251

  View details for PubMedID 31148342

• An Autotransferable g-C3 N4 Li+ -Modulating Layer toward Stable Lithium Anodes. Advanced materials (Deerfield Beach, Fla.) Guo, Y. n., Niu, P. n., Liu, Y. n., Ouyang, Y. n., Li, D. n., Zhai, T. n., Li, H. n., Cui, Y. n. 2019: e1900342

  Abstract

  Commercial deployment of lithium anodes has been severely impeded by the poor battery safety, unsatisfying cycling lifespan, and efficiency. Recently, building artificial interfacial layers over a lithium anode was regarded as an effective strategy to stabilize the electrode. However, the fabrications reported so far have mostly been conducted directly upon lithium foil, often requiring stringent reaction conditions with indispensable inert environment protection and highly specialized reagents due to the high reactivity of metallic lithium. Besides, the uneven lithium-ion flux across the lithium surface should be more powerfully tailored via mighty interfacial layer materials. Herein, g-C3 N4 is employed as a Li+ -modulating material and a brand-new autotransferable strategy to fabricate this interfacial layer for Li anodes without any inert atmosphere protection and limitation of chemical regents is developed. The g-C3 N4 film is filtrated on the separator in air using a common alcohol solution and then perfectly autotransferred to the lithium surface by electrolyte wetting during normal cell assembly. The abundant nitrogen species within g-C3 N4 nanosheets can form transient LiN bonds to powerfully stabilize the lithium-ion flux and thus enable a CE over 99% for 900 cycles and smooth deposition at high current densities and capacities, surpassing most previous works.

  View details for PubMedID 31095799

• Membrane curvature underlies actin reorganization in response to nanoscale surface topography. Proceedings of the National Academy of Sciences of the United States of America Lou, H. Y., Zhao, W. n., Li, X. n., Duan, L. n., Powers, A. n., Akamatsu, M. n., Santoro, F. n., McGuire, A. F., Cui, Y. n., Drubin, D. G., Cui, B. n. 2019

  Abstract

  Surface topography profoundly influences cell adhesion, differentiation, and stem cell fate control. Numerous studies using a variety of materials demonstrate that nanoscale topographies change the intracellular organization of actin cytoskeleton and therefore a broad range of cellular dynamics in live cells. However, the underlying molecular mechanism is not well understood, leaving why actin cytoskeleton responds to topographical features unexplained and therefore preventing researchers from predicting optimal topographic features for desired cell behavior. Here we demonstrate that topography-induced membrane curvature plays a crucial role in modulating intracellular actin organization. By inducing precisely controlled membrane curvatures using engineered vertical nanostructures as topographies, we find that actin fibers form at the sites of nanostructures in a curvature-dependent manner with an upper limit for the diameter of curvature at ∼400 nm. Nanotopography-induced actin fibers are branched actin nucleated by the Arp2/3 complex and are mediated by a curvature-sensing protein FBP17. Our study reveals that the formation of nanotopography-induced actin fibers drastically reduces the amount of stress fibers and mature focal adhesions to result in the reorganization of actin cytoskeleton in the entire cell. These findings establish the membrane curvature as a key linkage between surface topography and topography-induced cell signaling and behavior.

  View details for DOI 10.1073/pnas.1910166116

  View details for PubMedID 31591250

• Diatomite derived hierarchical hybrid anode for high performance all-solid-state lithium metal batteries. Nature communications Zhou, F. n., Li, Z. n., Lu, Y. Y., Shen, B. n., Guan, Y. n., Wang, X. X., Yin, Y. C., Zhu, B. S., Lu, L. L., Ni, Y. n., Cui, Y. n., Yao, H. B., Yu, S. H. 2019; 10 (1): 2482

  Abstract

  Lithium metal based anode with hierarchical structure to enable high rate capability, volume change accommodation, and dendritic suppression is highly desirable for all-solid-state lithium metal battery. However, the fabrication of hierarchical lithium metal based anode is challenging due to the volatility of lithium. Here, we report that natural diatomite can act as an excellent template for constructing hierarchical silicon-lithium based hybrid anode for high performance all-solid-state lithium metal battery. This hybrid anode exhibits stable lithium stripping/plating performance over 1000 h with average overpotential lower than 100 mV without any short circuit. Moreover, all-solid-state full cell using this lithium metal composite anode to couple with lithium iron phosphate cathode shows excellent cycling stability (0.04% capacity decay rate for 500 cycles at 0.5C) and high rate capability (65 mAh g-1 at 5C). The present natural diatomite derived hybrid anode could further promote the fabrication of high performance all-solid-state lithium batteries from sustainable natural resources.

  View details for DOI 10.1038/s41467-019-10473-w

  View details for PubMedID 31171790

• Evolution of the Solid-Electrolyte Interphase on Carbonaceous Anodes Visualized by Atomic-Resolution Cryogenic Electron Microscopy. Nano letters Huang, W. n., Attia, P. M., Wang, H. n., Renfrew, S. E., Jin, N. n., Das, S. n., Zhang, Z. n., Boyle, D. T., Li, Y. n., Bazant, M. Z., McCloskey, B. D., Chueh, W. C., Cui, Y. n. 2019

  Abstract

  The stability of modern lithium-ion batteries depends critically on an effective solid-electrolyte interphase (SEI), a passivation layer that forms on the carbonaceous negative electrode as a result of electrolyte reduction. However, a nanoscopic understanding of how the SEI evolves with battery aging remains limited due to the difficulty in characterizing the structural and chemical properties of this sensitive interphase. In this work, we image the SEI on carbon black negative electrodes using cryogenic transmission electron microscopy (cryo-TEM) and track its evolution during cycling. We find that a thin, primarily amorphous SEI nucleates on the first cycle, which further evolves into one of two distinct SEI morphologies upon further cycling: (1) a compact SEI, with a high concentration of inorganic components that effectively passivates the negative electrode; and (2) an extended SEI spanning hundreds of nanometers. This extended SEI grows on particles that lack a compact SEI and consists primarily of alkyl carbonates. The diversity in observed SEI morphologies suggests that SEI growth is a highly heterogeneous process. The simultaneous emergence of these distinct SEI morphologies highlights the necessity of effective passivation by the SEI, as large-scale extended SEI growths negatively impact lithium-ion transport, contribute to capacity loss, and may accelerate battery failure.

  View details for DOI 10.1021/acs.nanolett.9b01515

  View details for PubMedID 31322896

• Theory-guided Sn/Cu alloying for efficient CO2 electroreduction at low overpotentials NATURE CATALYSIS Zheng, X., Ji, Y., Tang, J., Wang, J., Liu, B., Steinruck, H., Lim, K., Li, Y., Toney, M. F., Chan, K., Cui, Y. 2019; 2 (1): 55–61

  View details for DOI 10.1038/s41929-018-0200-8

  View details for Web of Science ID 000455845400012

• High-Rate and Large-Capacity Lithium Metal Anode Enabled by Volume Conformal and Self-Healable Composite Polymer Electrolyte. Advanced science (Weinheim, Baden-Wurttemberg, Germany) Xia, S. n., Lopez, J. n., Liang, C. n., Zhang, Z. n., Bao, Z. n., Cui, Y. n., Liu, W. n. 2019; 6 (9): 1802353

  Abstract

  The widespread implementation of lithium-metal batteries (LMBs) with Li metal anodes of high energy density has long been prevented due to the safety concern of dendrite-related failure. Here a solid-liquid hybrid electrolyte consisting of composite polymer electrolyte (CPE) soaked with liquid electrolyte is reported. The CPE membrane composes of self-healing polymer and Li+-conducting nanoparticles. The electrodeposited lithium metal in a uniform, smooth, and dense behavior is achieved using a hybrid electrolyte, rather than dendritic and pulverized structure for a conventional separator. The Li foil symmetric cells can deliver remarkable cycling performance at ultrahigh current density up to 20 mA cm-2 with an extremely low voltage hysteresis over 1500 cycles. A large areal capacity of 10 mAh cm-2 at 10 mA cm-2 could also be obtained. Furthermore, the Li|Li4Ti5O12 cells based on the hybrid electrolyte achieve a higher specific capacity and longer cycling life than those using conventional separators. The superior performances are mainly attributed to strong adhesion, volume conformity, and self-healing functionality of CPE, providing a novel approach and a significant step toward cost-effective and large-scalable LMBs.

  View details for PubMedID 31065528

• A Gradient Lithiophilic-Lithiophobic Strategy for Lithium Metal Anode Protection ACTA PHYSICO-CHIMICA SINICA Cui Yi 2019; 35 (7): 661–62

  View details for DOI 10.3866/PKU.WHXB201809053

  View details for Web of Science ID 000465363400003

• Reversible and selective ion intercalation through the top surface of few-layer MoS2. Nature communications Zhang, J., Yang, A., Wu, X., van de Groep, J., Tang, P., Li, S., Liu, B., Shi, F., Wan, J., Li, Q., Sun, Y., Lu, Z., Zheng, X., Zhou, G., Wu, C., Zhang, S., Brongersma, M. L., Li, J., Cui, Y. 2018; 9 (1): 5289

  Abstract

  Electrochemical intercalation of ions into the van der Waals gap of two-dimensional (2D) layered materials is a promising low-temperature synthesis strategy to tune their physical and chemical properties. It is widely believed that ions prefer intercalation into the van der Waals gap through the edges of the 2D flake, which generally causes wrinkling and distortion. Here we demonstrate that the ions can also intercalate through the top surface of few-layer MoS2 and this type of intercalation is more reversible and stable compared to the intercalation through the edges. Density functional theory calculations show that this intercalation is enabled by the existence of natural defects in exfoliated MoS2 flakes. Furthermore, we reveal that sealed-edge MoS2 allows intercalation of small alkali metal ions (e.g., Li+ and Na+) and rejects large ions (e.g., K+). These findings imply potential applications in developing functional 2D-material-based devices with high tunability and ion selectivity.

  View details for PubMedID 30538249

• Reversible and selective ion intercalation through the top surface of few-layer MoS2 NATURE COMMUNICATIONS Zhang, J., Yang, A., Wu, X., van de Groep, J., Tang, P., Li, S., Liu, B., Shi, F., Wan, J., Li, Q., Sun, Y., Lu, Z., Zheng, X., Zhou, G., Wu, C., Zhang, S., Brongersma, M. L., Li, J., Cui, Y. 2018; 9

  View details for DOI 10.1038/s41467-018-07710-z

  View details for Web of Science ID 000452777900013

• Lithium Electrochemical Tuning for Electrocatalysis ADVANCED MATERIALS Lu, Z., Jiang, K., Chen, G., Wang, H., Cui, Y. 2018; 30 (48)

  View details for DOI 10.1002/adma.201800978

  View details for Web of Science ID 000451568400021

• A Li-ion sulfur full cell with ambient resistant Al-Li alloy anode ENERGY STORAGE MATERIALS Sun, J., Zeng, Q., Lv, R., Lv, W., Yang, Q., Amal, R., Wang, D. 2018; 15: 209–17

  View details for DOI 10.1016/j.ensm.2018.04.003

  View details for Web of Science ID 000449521500022

• Energy Materials Research at the University of Science and Technology of China. Advanced materials (Deerfield Beach, Fla.) Xiong, Y., Cui, Y. 2018; 30 (48): e1806572

  View details for PubMedID 30488500

• An electrochemical thermal transistor NATURE COMMUNICATIONS Sood, A., Xiong, F., Chen, S., Wang, H., Selli, D., Zhang, J., McClellan, C. J., Sun, J., Donadio, D., Cui, Y., Pop, E., Goodson, K. E. 2018; 9

  View details for DOI 10.1038/s41467-018-06760-7

  View details for Web of Science ID 000448710400004

• Shell-Protective Secondary Silicon Nanostructures as Pressure-Resistant High-Volumetric-Capacity Anodes for Lithium-Ion Batteries. Nano letters Wang, J., Liao, L., Li, Y., Zhao, J., Shi, F., Yan, K., Pei, A., Chen, G., Li, G., Lu, Z., Cui, Y. 2018

  Abstract

  The nanostructure design of a prereserved hollow space to accommodate 300% volume change of silicon anodes has created exciting promises for high-energy batteries. However, challenges with weak mechanical stability during the calendering process of electrode fabrication and poor volumetric energy density remain to be solved. Here we fabricated a pressure-resistant silicon structure by designing a dense silicon shell coating on secondary micrometer particles, each consisting of many silicon nanoparticles. The silicon skin layer significantly improves mechanical stability, while the inner porous structure efficiently accommodates the volume expansion. Such a structure can resist a high pressure of over 100 MPa and is well-maintained after the calendering process, demonstrating a high volumetric capacity of 2041 mAh cm-3. In addition, the dense silicon shell decreases the surface area and thus increases the initial Coulombic efficiency. With further encapsulation with a graphene cage, which allows the silicon core to expand within the cage while retaining electrical contact, the silicon hollow structure exhibits a high initial Coulombic efficiency and fast rise of later Coulombic efficiencies to >99.5% and superior stability in a full-cell battery.

  View details for PubMedID 30339401

• An electrochemical thermal transistor. Nature communications Sood, A., Xiong, F., Chen, S., Wang, H., Selli, D., Zhang, J., McClellan, C. J., Sun, J., Donadio, D., Cui, Y., Pop, E., Goodson, K. E. 2018; 9 (1): 4510

  Abstract

  The ability to actively regulate heat flow at the nanoscale could be a game changer for applications in thermal management and energy harvesting. Such a breakthrough could also enable the control of heat flow using thermal circuits, in a manner analogous to electronic circuits. Here we demonstrate switchable thermal transistors with an order of magnitude thermal on/off ratio, based on reversible electrochemical lithium intercalation in MoS2 thin films. We use spatially-resolved time-domain thermoreflectance to map the lithium ion distribution during device operation, and atomic force microscopy to show that the lithiated state correlates with increased thickness and surface roughness. First principles calculations reveal that the thermal conductance modulation is due to phonon scattering by lithium rattler modes, c-axis strain, and stacking disorder. This study lays the foundation for electrochemically-driven nanoscale thermal regulators, and establishes thermal metrology as a useful probe of spatio-temporal intercalant dynamics in nanomaterials.

  View details for PubMedID 30375375

• Nickel-hydrogen batteries for large-scale energy storage. Proceedings of the National Academy of Sciences of the United States of America Chen, W., Jin, Y., Zhao, J., Liu, N., Cui, Y. 2018

  Abstract

  Large-scale energy storage is of significance to the integration of renewable energy into electric grid. Despite the dominance of pumped hydroelectricity in the market of grid energy storage, it is limited by the suitable site selection and footprint impact. Rechargeable batteries show increasing interests in the large-scale energy storage; however, the challenging requirement of low-cost materials with long cycle and calendar life restricts most battery chemistries for use in the grid storage. Recently we introduced a concept of manganese-hydrogen battery with Mn2+/MnO2 redox cathode paired with H+/H2 gas anode, which has a long life of 10,000 cycles and with potential for grid energy storage. Here we expand this concept by replacing Mn2+/MnO2 redox with a nickel-based cathode, which enables 10* higher areal capacity loading, reaching 35 mAh cm-2 We also replace high-cost Pt catalyst on the anode with a low-cost, bifunctional nickel-molybdenum-cobalt alloy, which could effectively catalyze hydrogen evolution and oxidation reactions in alkaline electrolyte. Such a nickel-hydrogen battery exhibits an energy density of 140 Wh kg-1 (based on active materials) in aqueous electrolyte and excellent rechargeability with negligible capacity decay over 1,500 cycles. The estimated cost of the nickel-hydrogen battery based on active materials reaches as low as $83 per kilowatt-hour, demonstrating attractive characteristics for large-scale energy storage.

  View details for PubMedID 30373834

• Flexible and stable high-energy lithium-sulfur full batteries with only 100% oversized lithium NATURE COMMUNICATIONS Chang, J., Shang, J., Sun, Y., Ono, L. K., Wang, D., Ma, Z., Huang, Q., Chen, D., Liu, G., Cui, Y., Qi, Y., Zheng, Z. 2018; 9

  View details for DOI 10.1038/s41467-018-06879-7

  View details for Web of Science ID 000448414100030

• Flexible and stable high-energy lithium-sulfur full batteries with only 100% oversized lithium. Nature communications Chang, J., Shang, J., Sun, Y., Ono, L. K., Wang, D., Ma, Z., Huang, Q., Chen, D., Liu, G., Cui, Y., Qi, Y., Zheng, Z. 2018; 9 (1): 4480

  Abstract

  Lightweight and flexible energy storage devices are urgently needed to persistently power wearable devices, and lithium-sulfur batteries are promising technologies due to their low mass densities and high theoretical capacities. Here we report a flexible and high-energy lithium-sulfur full battery device with only 100% oversized lithium, enabled by rationally designed copper-coated and nickel-coated carbon fabrics as excellent hosts for lithium and sulfur, respectively. These metallic carbon fabrics endow mechanical flexibility, reduce local current density of the electrodes, and, more importantly, significantly stabilize the electrode materials to reach remarkable Coulombic efficiency of >99.89% for a lithium anode and >99.82% for a sulfur cathode over 400 half-cell charge-discharge cycles. Consequently, the assembled lithium-sulfur full battery provides high areal capacity (3mAh cm-2), high cell energy density (288Whkg-1 and 360WhL-1), excellent cycling stability (260 cycles), and remarkable bending stability at a small radius of curvature (<1mm).

  View details for PubMedID 30367063

• A Dual-Crosslinking Design for Resilient Lithium-Ion Conductors ADVANCED MATERIALS Lopez, J., Sun, Y., Mackanic, D. G., Lee, M., Foudeh, A. M., Song, M., Cui, Y., Bao, Z. 2018; 30 (43)

  View details for DOI 10.1002/adma.201804142

  View details for Web of Science ID 000448786000025

• Tuning Cu/Cu2 O Interfaces for the Reduction of Carbon Dioxide to Methanol in Aqueous Solutions. Angewandte Chemie (International ed. in English) Chang, X., Wang, T., Zhao, Z., Yang, P., Greeley, J., Mu, R., Zhang, G., Gong, Z., Luo, Z., Chen, J., Cui, Y., Ozin, G. A., Gong, J. 2018

  Abstract

  Artificial photosynthesis can be used to store solar energy and reduce CO2 into fuels to potentially alleviate global warming and the energy crisis. Compared to the generation of gaseous products, it remains a great challenge to tune the product distribution of artificial photosynthesis to liquid fuels, such as CH3 OH, which are suitable for storage and transport. Herein, we describe the introduction of metallic Cu nanoparticles (NPs) on Cu2 O films to change the product distribution from gaseous products on bare Cu2 O to predominantly CH3 OH by CO2 reduction in aqueous solutions. The specifically designed Cu/Cu2 O interfaces balance the binding strengths of H* and CO* intermediates, which play critical roles in CH3 OH production. With a TiO2 model photoanode to construct a photoelectrochemical cell, a Cu/Cu2 O dark cathode exhibited a Faradaic efficiency of up to 53.6% for CH3 OH production. This work demonstrates the feasibility and mechanism of interface engineering to enhance the CH3 OH production from CO2 reduction in aqueous electrolytes.

  View details for PubMedID 30329205

• Correlating Structure and Function of Battery Interphases at Atomic Resolution Using Cryoelectron Microscopy JOULE Li, Y., Huang, W., Li, Y., Pei, A., Boyle, D., Cui, Y. 2018; 2 (10): 2167–77

  View details for DOI 10.1016/j.joule.2018.08.004

  View details for Web of Science ID 000447735000021

• Catalyst: How Cryo-EM Shapes the Development of Next-Generation Batteries CHEM Li, Y., Li, Y., Cui, Y. 2018; 4 (10): 2250–52

  View details for DOI 10.1016/j.chempr.2018.09.007

  View details for Web of Science ID 000447051500003

• Concentrated mixed cation acetate "water-in-salt" solutions as green and low-cost high voltage electrolytes for aqueous batteries ENERGY & ENVIRONMENTAL SCIENCE Lukatskaya, M. R., Feldblyum, J. I., Mackanic, D. G., Lissel, F., Michels, D. L., Cui, Y., Bao, Z. 2018; 11 (10): 2876–83

  View details for DOI 10.1039/c8ee00833g

  View details for Web of Science ID 000448339100011

• Design of Hollow Nanostructures for Energy Storage, Conversion and Production. Advanced materials (Deerfield Beach, Fla.) Wang, J., Cui, Y., Wang, D. 2018: e1801993

  Abstract

  Hollow nanostructures have shown great promise for energy storage, conversion, and production technologies. Significant efforts have been devoted to the design and synthesis of hollow nanostructures with diverse compositional and geometric characteristics in the past decade. However, the correlation between their structure and energy-related performance has not been reviewed thoroughly in the literature. Here, some representative examples of designing hollow nanostructure to effectively solve the problems of energy-related technologies are highlighted, such as lithium-ion batteries, lithium-metal anodes, lithium-sulfur batteries, supercapacitors, dye-sensitized solar cells, electrocatalysis, and photoelectrochemical cells. The great effect of structure engineering on the performance is discussed in depth, which will benefit the better design of hollow nanostructures to fulfill the requirements of specific applications and simultaneously enrich the diversity of the hollow nanostructure family. Finally, future directions of hollow nanostructure design to solve emerging challenges and further improve the performance of energy-related technologies are also provided.

  View details for PubMedID 30238544

• Stretchable Lithium Metal Anode with Improved Mechanical and Electrochemical Cycling Stability JOULE Liu, K., Kong, B., Liu, W., Sun, Y., Song, M., Chen, J., Liu, Y., Lin, D., Pei, A., Cui, Y. 2018; 2 (9): 1857–65

  View details for DOI 10.1016/j.joule.2018.06.003

  View details for Web of Science ID 000445021000021

• Effects of Polymer Coatings on Electrodeposited Lithium Metal JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Lopez, J., Pei, A., Oh, J., Wang, G., Cui, Y., Bao, Z. 2018; 140 (37): 11735–44

  Abstract

  The electrodeposition of lithium metal is a key process in next-generation, high energy density storage devices. However, the high reactivity of the lithium metal causes short cycling lifetimes and dendrite growth that can pose a serious safety issue. Recently, a number of approaches have been pursued to stabilize the lithium metal-electrolyte interface, including soft polymeric coatings that have shown the ability to enable high-rate and high-capacity lithium metal cycling, but a clear understanding of how to design and modify these coatings has not yet been established. In this work, we studied the effects of several polymers with systematically varied chemical and mechanical properties as coatings on the lithium metal anode. By examining the early stages of lithium metal deposition, we determine that the morphology of the lithium particles is strongly influenced by the chemistry of the polymer coating. We have identified polymer dielectric constant and surface energy as two key descriptors of the lithium deposit size. Low surface energy polymers were found to promote larger deposits with smaller surface areas. This may be explained by a reduced interaction between the coating and the lithium surface and thus an increase in the interfacial energy. On the other hand, high dielectric constant polymers were found to increase the exchange current and gave larger lithium deposits due to the decreased overpotentials at a fixed current density. We also observed that the thickness of the polymer coating should be optimized for each individual polymer. Furthermore, polymer reactivity was found to strongly influence the Coulombic efficiency. Overall, this work offers new fundamental insights into lithium electrodeposition processes and provides direction for the design of new polymer coatings to better stabilize the lithium metal anode.

  View details for DOI 10.1021/jacs.8b06047

  View details for Web of Science ID 000445439700030

  View details for PubMedID 30152228

• Lithium Electrochemical Tuning for Electrocatalysis. Advanced materials (Deerfield Beach, Fla.) Lu, Z., Jiang, K., Chen, G., Wang, H., Cui, Y. 2018: e1800978

  Abstract

  Electrocatalysis is of great importance to a variety of energy conversion processes, where developing highly efficient catalysts is critical. While common strategies involve screening a wide range of materials with new chemical compositions or structures, a different approach to continuously, controllably, and effectively tune the electronic properties of existing catalytic materials for optimized activities has been demonstrated recently. Inspired by studies in lithium-ion batteries, systematical lithium electrochemical tuning (LiET) methods such as Li intercalation, extraction, cycling, and strain engineering, are employed to effectively tune the electronic structures of different existing catalysts and thus improve their catalytic activities dramatically. Herein, the advantages of the LiET method in electrocatalysis are introduced, and then some recent representative examples in improving the performances of important electrochemical reactions are reviewed briefly. Lastly, a few promising directions on extending the applications of the LiET method in electrocatalysis are proposed.

  View details for PubMedID 30203515

• A Dual-Crosslinking Design for Resilient Lithium-Ion Conductors. Advanced materials (Deerfield Beach, Fla.) Lopez, J., Sun, Y., Mackanic, D. G., Lee, M., Foudeh, A. M., Song, M., Cui, Y., Bao, Z. 2018: e1804142

  Abstract

  Solid-state electrolyte materials are attractive options for meeting the safety and performance needs of advanced lithium-based rechargeable battery technologies because of their improved mechanical and thermal stability compared to liquid electrolytes. However, there is typically a tradeoff between mechanical and electrochemical performance. Here an elastic Li-ion conductor with dual covalent and dynamic hydrogen bonding crosslinks is described to provide high mechanical resilience without sacrificing the room-temperature ionic conductivity. A solid-state lithium-metal/LiFePO4 cell with this resilient electrolyte can operate at room temperature with a high cathode capacity of 152 mAh g-1 for 300 cycles and can maintain operation even after being subjected to intense mechanical impact testing. This new dual crosslinking design provides robust mechanical properties while maintaining ionic conductivity similar to state-of-the-art polymer-based electrolytes. This approach opens a route toward stable, high-performance operation of solid-state batteries even under extreme abuse.

  View details for PubMedID 30199111

• Solubility-mediated sustained release enabling nitrate additive in carbonate electrolytes for stable lithium metal anode. Nature communications Liu, Y., Lin, D., Li, Y., Chen, G., Pei, A., Nix, O., Li, Y., Cui, Y. 2018; 9 (1): 3656

  Abstract

  The physiochemical properties of the solid-electrolyte interphase, primarily governed by electrolyte composition, have a profound impact on the electrochemical cycling of metallic lithium. Herein, we discover that the effect of nitrate anions on regulating lithium deposition previously known in ether-based electrolytes can be extended to carbonate-based systems, which dramatically alters the nuclei from dendritic to spherical, albeit extremely limited solubility. This is attributed to the preferential reduction of nitrate during solid-electrolyte interphase formation, and the mechanisms behind which are investigated based on the structure, ion-transport properties, and charge transfer kinetics of the modified interfacial environment. To overcome the solubility barrier, a solubility-mediated sustained-release methodology is introduced, in which nitrate nanoparticles are encapsulated in porous polymer gel and can be steadily dissolved during battery operation to maintain a high concentration at the electroplating front. As such, effective dendrite suppression and remarkably enhanced cycling stability are achieved in corrosive carbonate electrolytes.

  View details for PubMedID 30194431

• Solubility-mediated sustained release enabling nitrate additive in carbonate electrolytes for stable lithium metal anode NATURE COMMUNICATIONS Liu, Y., Lin, D., Li, Y., Chen, G., Pei, A., Nix, O., Li, Y., Cui, Y. 2018; 9

  View details for DOI 10.1038/s41467-018-06077-5

  View details for Web of Science ID 000444014100031

• Crosslinked Poly(tetrahydrofuran) as a Loosely Coordinating Polymer Electrolyte ADVANCED ENERGY MATERIALS Mackanic, D. G., Michaels, W., Lee, M., Feng, D., Lopez, J., Qin, J., Cui, Y., Bao, Z. 2018; 8 (25)

  View details for DOI 10.1002/aenm.201800703

  View details for Web of Science ID 000443674100005

• Fundamental study on the wetting property of liquid lithium ENERGY STORAGE MATERIALS Wang, J., Wang, H., Xie, J., Yang, A., Pei, A., Wu, C., Shi, F., Liu, Y., Lin, D., Gong, Y., Cui, Y. 2018; 14: 345–50

  View details for DOI 10.1016/j.ensm.2018.05.021

  View details for Web of Science ID 000441981000035

• Strategy for Boosting Li-Ion Current in Silicon Nanoparticles ACS ENERGY LETTERS Song, M., Chang, G., Jung, D., Kwon, M., Li, P., Ku, J., Choi, J., Zhang, K., Yi, G., Cui, Y., Park, J. 2018; 3 (9): 2252–58

  View details for DOI 10.1021/acsenergylett.8b01114

  View details for Web of Science ID 000445052900032

• An intermediate temperature garnet-type solid electrolyte-based molten lithium battery for grid energy storage NATURE ENERGY Jin, Y., Liu, K., Lang, J., Zhuo, D., Huang, Z., Wang, C., Wu, H., Cui, Y. 2018; 3 (9): 732–38

  View details for DOI 10.1038/s41560-018-0198-9

  View details for Web of Science ID 000444121800013

• Resonance-Enhanced Absorption in Hollow Nanoshell Spheres with Omnidirectional Detection and High Responsivity and Speed ADVANCED MATERIALS Lien, D., Dong, Z., Retamal, J., Wang, H., Wei, T., Wang, D., He, J., Cui, Y. 2018; 30 (34): e1801972

  Abstract

  Optical resonance formed inside a nanocavity resonator can trap light within the active region and hence enhance light absorption, effectively boosting device or material performance in applications of solar cells, photodetectors (PDs), and photocatalysts. Complementing conventional circular and spherical structures, a new type of multishelled spherical resonant strategy is presented. Due to the resonance-enhanced absorption by multiple convex shells, ZnO nanoshell PDs show improved optoelectronic performance and omnidirectional detection of light at different incidence angles and polarization. In addition, the response and recovery speeds of these devices are improved (0.8 and 0.7 ms, respectively) up to three orders of magnitude faster than in previous reports because of the existence of junction barriers between the nanoshells. The general design principles behind these hollow ZnO nanoshells pave a new way to improve the performance of sophisticated nanophotonic devices.

  View details for PubMedID 30019787

• Dual-crosslinking design for resilient lithium ion conductor Lopez, J., Sun, Y., Cui, Y., Bao, Z. AMER CHEMICAL SOC. 2018

  View details for Web of Science ID 000447609104413

• Insights on the interaction of polymer coatings with electrodeposited lithium metal Lopez, J., Pei, A., Cui, Y., Bao, Z. AMER CHEMICAL SOC. 2018

  View details for Web of Science ID 000447609104232

• Understanding the influence of polymer properties on the stability of high capacity silicon and lithium metal anodes Lopez, J., Pei, A., Cui, Y., Bao, Z. AMER CHEMICAL SOC. 2018

  View details for Web of Science ID 000447609104226

• Cryo-electron microscopy for battery materials Li, Y., Cui, Y. AMER CHEMICAL SOC. 2018

  View details for Web of Science ID 000447600005408

• Stabilization of Hexaaminobenzene in a 2D Conductive Metal-Organic Framework for High Power Sodium Storage JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Park, J., Lee, M., Feng, D., Huang, Z., Hinckley, A. C., Yakoyenko, A., Zou, X., Cui, Y., Bao, Z. 2018; 140 (32): 10315–23

  Abstract

  Redox-active organic materials have gained growing attention as electrodes of rechargeable batteries. However, their key limitations are the low electronic conductivity and limited chemical and structural stability under redox conditions. Herein, we report a new cobalt-based 2D conductive metal-organic framework (MOF), Co-HAB, having stable, accessible, dense active sites for high-power energy storage device through conjugative coordination between a redox-active linker, hexaaminobenzene (HAB), and a Co(II) center. Given the exceptional capability of Co-HAB for stabilizing reactive HAB, a reversible three-electron redox reaction per HAB was successfully demonstrated for the first time, thereby presenting a promising new electrode material for sodium-ion storage. Specifically, through synthetic tunability of Co-HAB, the bulk electrical conductivity of 1.57 S cm-1 was achieved, enabling an extremely high rate capability, delivering 214 mAh g-1 within 7 min or 152 mAh g-1 in 45 s. Meanwhile, an almost linear increase of the areal capacity upon increasing active mass loading up to 9.6 mg cm-2 was obtained, demonstrating 2.6 mAh cm-2 with a trace amount of conducting agent.

  View details for DOI 10.1021/jacs.8b06020

  View details for Web of Science ID 000442183700037

  View details for PubMedID 30041519

• An Ultrastrong Double-Layer Nanodiamond Interface for Stable Lithium Metal Anodes JOULE Liu, Y., Tzeng, Y., Lin, D., Pei, A., Lu, H., Melosh, N. A., Shen, Z., Chu, S., Cui, Y. 2018; 2 (8): 1595–1609

  View details for DOI 10.1016/j.joule.2018.05.007

  View details for Web of Science ID 000441627400022

• A Silica-Aerogel-Reinforced Composite Polymer Electrolyte with High Ionic Conductivity and High Modulus ADVANCED MATERIALS Lin, D., Yuen, P., Liu, Y., Liu, W., Liu, N., Dauskardt, R. H., Cui, Y. 2018; 30 (32)

  View details for DOI 10.1002/adma.201802661

  View details for Web of Science ID 000440813300028

• Lithium metal stripping beneath the solid electrolyte interphase. Proceedings of the National Academy of Sciences of the United States of America Shi, F., Pei, A., Boyle, D. T., Xie, J., Yu, X., Zhang, X., Cui, Y. 2018

  Abstract

  Lithium stripping is a crucial process coupled with lithium deposition during the cycling of Li metal batteries. Lithium deposition has been widely studied, whereas stripping as a subsurface process has rarely been investigated. Here we reveal the fundamental mechanism of stripping on lithium by visualizing the interface between stripped lithium and the solid electrolyte interphase (SEI). We observed nanovoids formed between lithium and the SEI layer after stripping, which are attributed to the accumulation of lithium metal vacancies. High-rate dissolution of lithium causes vigorous growth and subsequent aggregation of voids, followed by the collapse of the SEI layer, i.e., pitting. We systematically measured the lithium polarization behavior during stripping and find that the lithium cation diffusion through the SEI layer is the rate-determining step. Nonuniform sites on typical lithium surfaces, such as grain boundaries and slip lines, greatly accelerated the local dissolution of lithium. The deeper understanding of this buried interface stripping process provides beneficial clues for future lithium anode and electrolyte design.

  View details for PubMedID 30082382

• Efficient electrocatalytic CO2 reduction on a three-phase interface NATURE CATALYSIS Li, J., Chen, G., Zhu, Y., Liang, Z., Pei, A., Wu, C., Wang, H., Lee, H., Liu, K., Chu, S., Cui, Y. 2018; 1 (8): 592–600

  View details for DOI 10.1038/s41929-018-0108-3

  View details for Web of Science ID 000446621900009

• Core-Shell Nanofibrous Materials with High Particulate Matter Removal Efficiencies and Thermally Triggered Flame Retardant Properties. ACS central science Liu, K., Liu, C., Hsu, P., Xu, J., Kong, B., Wu, T., Zhang, R., Zhou, G., Huang, W., Sun, J., Cui, Y. 2018; 4 (7): 894–98

  Abstract

  Dust filtration is a crucial process for industrial waste gas treatment. Great efforts have been devoted to improve the performance of dust filtration filters both in industrial and fundamental research. Conventional air-filtering materials are limited by three key issues: (1) Low filtration efficiency, especially for particulate matter (PM) below 1 mum; (2) large air pressure drops across the filter, which require a high energy input to overcome; and (3) safety hazards such as dust explosions and fires. Here, we have developed a "smart" multifunctional material which can capture PM with high efficiency and an extremely low pressure drop, while possessing a flame retardant design. This multifunctionality is achieved through a core-shell nanofiber design with the polar polymer Nylon-6 as the shell and the flame retardant triphenyl phosphate (TPP) as the core. At 80% optical transmittance, the multifunctional materials showed capture efficiency of 99.00% for PM2.5 and >99.50% for PM10-2.5, with a pressure drop of only 0.25 kPa (0.2% of atmospheric pressure) at a flow rate of 0.5 m s-1. Moreover, during direct ignition tests, the multifunctional materials showed extraordinary flame retardation; the self-extinguishing time of the filtrate-contaminated filter is nearly instantaneous (0 s/g) compared to 150 s/g for unmodified Nylon-6.

  View details for PubMedID 30062118

• Spectrally Selective Nanocomposite Textile for Outdoor Personal Cooling. Advanced materials (Deerfield Beach, Fla.) Cai, L., Song, A. Y., Li, W., Hsu, P., Lin, D., Catrysse, P. B., Liu, Y., Peng, Y., Chen, J., Wang, H., Xu, J., Yang, A., Fan, S., Cui, Y. 2018: e1802152

  Abstract

  Outdoor heat stress poses a serious public health threat and curtails industrial labor supply and productivity, thus adversely impacting the wellness and economy of the entire society. With climate change, there will be more intense and frequent heat waves that further present a grand challenge for sustainability. However, an efficient and economical method that can provide localized outdoor cooling of the human body without intensive energy input is lacking. Here, a novel spectrally selective nanocomposite textile for radiative outdoor cooling using zinc oxide nanoparticle-embedded polyethylene is demonstrated. By reflecting more than 90% solar irradiance and selectively transmitting out human body thermal radiation, this textile can enable simulated skin to avoid overheating by 5-13 °C compared to normal textile like cotton under peak daylight condition. Owing to its superior passive cooling capability and compatibility with large-scale production, this radiative outdoor cooling textile is promising to widely benefit the sustainability of society in many aspects spanning from health to economy.

  View details for PubMedID 30015999

• Engineering stable interfaces for three-dimensional lithium metal anodes. Science advances Xie, J., Wang, J., Lee, H. R., Yan, K., Li, Y., Shi, F., Huang, W., Pei, A., Chen, G., Subbaraman, R., Christensen, J., Cui, Y. 2018; 4 (7): eaat5168

  Abstract

  Lithium metal has long been considered one of the most promising anode materials for advanced lithium batteries (for example, Li-S and Li-O2), which could offer significantly improved energy density compared to state-of-the-art lithium ion batteries. Despite decades of intense research efforts, its commercialization remains limited by poor cyclability and safety concerns of lithium metal anodes. One root cause is the parasitic reaction between metallic lithium and the organic liquid electrolyte, resulting in continuous formation of an unstable solid electrolyte interphase, which consumes both active lithium and electrolyte. Until now, it has been challenging to completely shut down the parasitic reaction. We find that a thin-layer coating applied through atomic layer deposition on a hollow carbon host guides lithium deposition inside the hollow carbon sphere and simultaneously prevents electrolyte infiltration by sealing pinholes on the shell of the hollow carbon sphere. By encapsulating lithium inside the stable host, parasitic reactions are prevented, resulting in impressive cycling behavior. We report more than 500 cycles at a high coulombic efficiency of 99% in an ether-based electrolyte at a cycling rate of 0.5 mA/cm2 and a cycling capacity of 1 mAh/cm2, which is among the most stable Li anodes reported so far.

  View details for PubMedID 30062125

• Quantitative investigation of polysulfide adsorption capability of candidate materials for Li-S batteries ENERGY STORAGE MATERIALS Wu, D., Shi, F., Zhou, G., Zu, C., Liu, C., Liu, K., Liu, Y., Wang, J., Peng, Y., Cui, Y. 2018; 13: 241–46

  View details for DOI 10.1016/j.ensm.2018.01.020

  View details for Web of Science ID 000436924800028

• A Silica-Aerogel-Reinforced Composite Polymer Electrolyte with High Ionic Conductivity and High Modulus. Advanced materials (Deerfield Beach, Fla.) Lin, D., Yuen, P. Y., Liu, Y., Liu, W., Liu, N., Dauskardt, R. H., Cui, Y. 2018: e1802661

  Abstract

  High-energy all-solid-state lithium (Li) batteries have great potential as next-generation energy-storage devices. Among all choices of electrolytes, polymer-based systems have attracted widespread attention due to their low density, low cost, and excellent processability. However, they are generally mechanically too weak to effectively suppress Li dendrites and have lower ionic conductivity for reasonable kinetics at ambient temperature. Herein, an ultrastrong reinforced composite polymer electrolyte (CPE) is successfully designed and fabricated by introducing a stiff mesoporous SiO2 aerogel as the backbone for a polymer-based electrolyte. The interconnected SiO2 aerogel not only performs as a strong backbone strengthening the whole composite, but also offers large and continuous surfaces for strong anion adsorption, which produces a highly conductive pathway across the composite. As a consequence, a high modulus of 0.43 GPa and high ionic conductivity of 0.6 mS cm-1 at 30 °C are simultaneously achieved. Furthermore, LiFePO4 -Li full cells with good cyclability and rate capability at ambient temperature are obtained. Full cells with cathode capacity up to 2.1 mAh cm-2 are also demonstrated. The aerogel-reinforced CPE represents a new design principle for solid-state electrolytes and offers opportunities for future all-solid-state Li batteries.

  View details for PubMedID 29939433

• Sea-Sponge-like Structure of Nano-Fe3O4 on Skeleton-C with Long Cycle Life under High Rate for Li-Ion Batteries ACS APPLIED MATERIALS & INTERFACES Chen, S., Wu, Q., Wen, M., Wu, Q., Li, J., Cui, Y., Pinna, N., Fan, Y., Wu, T. 2018; 10 (23): 19656–63

  Abstract

  To meet the demands of long cycle life under high rate for lithium-ion batteries, the advancement of anode materials with stable structural properties is necessarily demanded. Such promotion needs to design reasonable structure to facilitate the transportation of electron and lithium ions (Li+). Herein, a novel C/Fe3O4 sea-sponge-like structure was synthesized by ultrasonic spray pyrolysis following thermal decomposition process. On the basis of sea-sponge carbon (SSC) excellences in electronic conductivity and short Li+ diffusion pathway, nano-Fe3O4 anchored on stable SSC skeleton can deliver high electrochemical performance with long cycle life under high rate. During electrochemical cycling, well-dispersed nano-Fe3O4 in ∼6 nm not only averts excessive pulverization and is enveloped by solid electrolyte interphase film, but also increases Li+ diffusion efficiency. The much improved electrochemical properties showed a capacity of around 460 mAh g-1 at a high rate of 1.5C with a retention rate of 93%, which is maintained without degradation up to 1000 cycles (1C = 1000 mA g-1).

  View details for PubMedID 29851459

• Materials for lithium-ion battery safety. Science advances Liu, K., Liu, Y., Lin, D., Pei, A., Cui, Y. 2018; 4 (6): eaas9820

  Abstract

  Lithium-ion batteries (LIBs) are considered to be one of the most important energy storage technologies. As the energy density of batteries increases, battery safety becomes even more critical if the energy is released unintentionally. Accidents related to fires and explosions of LIBs occur frequently worldwide. Some have caused serious threats to human life and health and have led to numerous product recalls by manufacturers. These incidents are reminders that safety is a prerequisite for batteries, and serious issues need to be resolved before the future application of high-energy battery systems. This Review aims to summarize the fundamentals of the origins of LIB safety issues and highlight recent key progress in materials design to improve LIB safety. We anticipate that this Review will inspire further improvement in battery safety, especially for emerging LIBs with high-energy density.

  View details for PubMedID 29942858

• Morphology and property investigation of primary particulate matter particles from different sources NANO RESEARCH Zhang, R., Liu, C., Zhou, G., Sun, J., Liu, N., Hsu, P., Wang, H., Qiu, Y., Zhao, J., Wu, T., Zhao, W., Cui, Y. 2018; 11 (6): 3182–92

  View details for DOI 10.1007/s12274-017-1724-y

  View details for Web of Science ID 000433048600021

• Wood-Inspired High-Performance Ultrathick Bulk Battery Electrodes ADVANCED MATERIALS Lu, L., Lu, Y., Xiao, Z., Zhang, T., Zhou, F., Ma, T., Ni, Y., Yao, H., Yu, S., Cui, Y. 2018; 30 (20): e1706745

  Abstract

  Ultrathick electrode design is a promising strategy to enhance the specific energy of Li-ion batteries (LIBs) without changing the underlying materials chemistry. However, the low Li-ion conductivity caused by ultralong Li-ion transport pathway in traditional random microstructured electrode heavily deteriorates the rate performance of ultrathick electrodes. Herein, inspired by the vertical microchannels in natural wood as the highway for water transport, the microstructures of wood are successfully duplicated into ultrathick bulk LiCoO2 (LCO) cathode via a sol-gel process to achieve the high areal capacity and excellent rate capability. The X-ray-based microtomography demonstrates that the uniform microchannels are built up throughout the whole wood-templated LCO cathode bringing in 1.5 times lower of tortuosity and ≈2 times higher of Li-ion conductivity compared to that of random structured LCO cathode. The fabricated wood-inspired LCO cathode delivers high areal capacity up to 22.7 mAh cm-2 (five times of the existing electrode) and achieves the dynamic stress test at such high areal capacity for the first time. The reported wood-inspired design will open a new avenue to adopt natural hierarchical structures to improve the performance of LIBs.

  View details for PubMedID 29603415

• Ionically Conductive Self-Healing Binder for Low Cost Si Microparticles Anodes in Li-Ion Batteries ADVANCED ENERGY MATERIALS Munaoka, T., Yan, X., Lopez, J., To, J. F., Park, J., Tok, J., Cui, Y., Bao, Z. 2018; 8 (14)

  View details for DOI 10.1002/aenm.201703138

  View details for Web of Science ID 000435713600020

• Vertically Aligned and Continuous Nanoscale Ceramic-Polymer Interfaces in Composite Solid Polymer Electrolytes for Enhanced Ionic Conductivity. Nano letters Zhang, X., Xie, J., Shi, F., Lin, D., Liu, Y., Liu, W., Pei, A., Gong, Y., Wang, H., Liu, K., Xiang, Y., Cui, Y. 2018

  Abstract

  Among all solid electrolytes, composite solid polymer electrolytes, comprised of polymer matrix and ceramic fillers, garner great interest due to the enhancement of ionic conductivity and mechanical properties derived from ceramic-polymer interactions. Here, we report a composite electrolyte with densely packed, vertically aligned, and continuous nanoscale ceramic-polymer interfaces, using surface-modified anodized aluminum oxide as the ceramic scaffold and poly(ethylene oxide) as the polymer matrix. The fast Li+ transport along the ceramic-polymer interfaces was proven experimentally for the first time, and an interfacial ionic conductivity higher than 10-3 S/cm at 0 °C was predicted. The presented composite solid electrolyte achieved an ionic conductivity as high as 5.82 * 10-4 S/cm at the electrode level. The vertically aligned interfacial structure in the composite electrolytes enables the viable application of the composite solid electrolyte with superior ionic conductivity and high hardness, allowing Li-Li cells to be cycled at a small polarization without Li dendrite penetration.

  View details for PubMedID 29727578

• Hierarchical assembly and superior sodium storage properties of a sea-sponge structured C/SnS@C nanocomposite JOURNAL OF MATERIALS CHEMISTRY A Chen, S., Xing, K., Wen, J., Wen, M., Wu, Q., Cui, Y. 2018; 6 (17): 7631–38

  View details for DOI 10.1039/c8ta00833g

  View details for Web of Science ID 000431621700035

• A manganese-hydrogen battery with potential for grid-scale energy storage NATURE ENERGY Chen, W., Li, G., Pei, A., Li, Y., Liao, L., Wang, H., Wan, J., Liang, Z., Chen, G., Zhang, H., Wang, J., Cui, Y. 2018; 3 (5): 428–35

  View details for DOI 10.1038/s41560-018-0147-7

  View details for Web of Science ID 000433029700018

• Spatially controlled doping of two-dimensional SnS2 through intercalation for electronics NATURE NANOTECHNOLOGY Gong, Y., Yuan, H., Wu, C., Tang, P., Yang, S., Yang, A., Li, G., Liu, B., van de Groep, J., Brongersma, M. L., Chisholm, M. F., Zhang, S., Zhou, W., Cui, Y. 2018; 13 (4): 294-+

  Abstract

  Doped semiconductors are the most important building elements for modern electronic devices 1 . In silicon-based integrated circuits, facile and controllable fabrication and integration of these materials can be realized without introducing a high-resistance interface2,3. Besides, the emergence of two-dimensional (2D) materials enables the realization of atomically thin integrated circuits4-9. However, the 2D nature of these materials precludes the use of traditional ion implantation techniques for carrier doping and further hinders device development 10 . Here, we demonstrate a solvent-based intercalation method to achieve p-type, n-type and degenerately doped semiconductors in the same parent material at the atomically thin limit. In contrast to naturally grown n-type S-vacancy SnS2, Cu intercalated bilayer SnS2 obtained by this technique displays a hole field-effect mobility of ~40 cm2 V-1 s-1, and the obtained Co-SnS2 exhibits a metal-like behaviour with sheet resistance comparable to that of few-layer graphene 5 . Combining this intercalation technique with lithography, an atomically seamless p-n-metal junction could be further realized with precise size and spatial control, which makes in-plane heterostructures practically applicable for integrated devices and other 2D materials. Therefore, the presented intercalation method can open a new avenue connecting the previously disparate worlds of integrated circuits and atomically thin materials.

  View details for PubMedID 29483599

• Gate-Induced Metal-Insulator Transition in MoS2 by Solid Superionic Conductor LaF3 NANO LETTERS Wu, C., Yuan, H., Li, Y., Gong, Y., Hwang, H. Y., Cui, Y. 2018; 18 (4): 2387–92

  Abstract

  Electric-double-layer (EDL) gating with liquid electrolyte has been a powerful tool widely used to explore emerging interfacial electronic phenomena. Due to the large EDL capacitance, a high carrier density up to 1014 cm-2 can be induced, directly leading to the realization of field-induced insulator to metal (or superconductor) transition. However, the liquid nature of the electrolyte has created technical issues including possible side electrochemical reactions or intercalation, and the potential for huge strain at the interface during cooling. In addition, the liquid coverage of active devices also makes many surface characterizations and in situ measurements challenging. Here, we demonstrate an all solid-state EDL device based on a solid superionic conductor LaF3, which can be used as both a substrate and a fluorine ionic gate dielectric to achieve a wide tunability of carrier density without the issues of strain or electrochemical reactions and can expose the active device surface for external access. Based on LaF3 EDL transistors (EDLTs), we observe the metal-insulator transition in MoS2. Interestingly, the well-defined crystal lattice provides a more uniform potential distribution in the substrate, resulting in less interface electron scattering and therefore a higher mobility in MoS2 transistors. This result shows the powerful gating capability of LaF3 solid electrolyte for new possibilities of novel interfacial electronic phenomena.

  View details for PubMedID 29580055

• Tuning of Plasmons in Transparent Conductive Oxides by Carrier Accumulation ACS PHOTONICS Liu, X., Kang, J., Yuan, H., Park, J., Cui, Y., Hwang, H. Y., Brongersma, M. L. 2018; 5 (4): 1493–98

  View details for DOI 10.1021/acsphotonics.7b01517

  View details for Web of Science ID 000430642500044

• An Aqueous Inorganic Polymer Binder for High Performance Lithium-Sulfur Batteries with Flame-Retardant Properties ACS CENTRAL SCIENCE Zhou, G., Liu, K., Fan, Y., Yuan, M., Liu, B., Liu, W., Shi, F., Liu, Y., Chen, W., Lopez, J., Zhuo, D., Zhao, J., Tsao, Y., Huang, X., Zhang, Q., Cui, Y. 2018; 4 (2): 260–67

  Abstract

  Lithium-sulfur (Li-S) batteries are regarded as promising next-generation high energy density storage devices for both portable electronics and electric vehicles due to their high energy density, low cost, and environmental friendliness. However, there remain some issues yet to be fully addressed with the main challenges stemming from the ionically insulating nature of sulfur and the dissolution of polysulfides in electrolyte with subsequent parasitic reactions leading to low sulfur utilization and poor cycle life. The high flammability of sulfur is another serious safety concern which has hindered its further application. Herein, an aqueous inorganic polymer, ammonium polyphosphate (APP), has been developed as a novel multifunctional binder to address the above issues. The strong binding affinity of the main chain of APP with lithium polysulfides blocks diffusion of polysulfide anions and inhibits their shuttling effect. The coupling of APP with Li ion facilitates ion transfer and promotes the kinetics of the cathode reaction. Moreover, APP can serve as a flame retardant, thus significantly reducing the flammability of the sulfur cathode. In addition, the aqueous characteristic of the binder avoids the use of toxic organic solvents, thus significantly improving safety. As a result, a high rate capacity of 520 mAh g-1 at 4 C and excellent cycling stability of ∼0.038% capacity decay per cycle at 0.5 C for 400 cycles are achieved based on this binder. This work offers a feasible and effective strategy for employing APP as an efficient multifunctional binder toward building next-generation high energy density Li-S batteries.

  View details for PubMedID 29532026

  View details for PubMedCentralID PMC5833002

• Deformable Organic Nanowire Field-Effect Transistors ADVANCED MATERIALS Lee, Y., Oh, J., Kim, T., Gu, X., Kim, Y., Wang, G., Wu, H., Pfattner, R., To, J. F., Katsumata, T., Son, D., Kang, J., Matthews, J. R., Niu, W., He, M., Sinclair, R., Cui, Y., Tok, J., Lee, T., Bao, Z. 2018; 30 (7)

  View details for DOI 10.1002/adma.201704401

  View details for Web of Science ID 000424891900009

• Nanoporous polyethylene microfibres for large-scale radiative cooling fabric NATURE SUSTAINABILITY Peng, Y., Chen, J., Song, A. Y., Catrysse, P. B., Hsu, P., Cai, L., Liu, B., Zhu, Y., Zhou, G., Wu, D. S., Lee, H., Fan, S., Cui, Y. 2018; 1 (2): 105–12

  View details for DOI 10.1038/s41893-018-0023-2

  View details for Web of Science ID 000439122700012

• Deformable Organic Nanowire Field-Effect Transistors. Advanced materials (Deerfield Beach, Fla.) Lee, Y., Oh, J. Y., Kim, T. R., Gu, X., Kim, Y., Wang, G. N., Wu, H. C., Pfattner, R., To, J. W., Katsumata, T., Son, D., Kang, J., Matthews, J. R., Niu, W., He, M., Sinclair, R., Cui, Y., Tok, J. B., Lee, T. W., Bao, Z. 2018; 30 (7)

  Abstract

  Deformable electronic devices that are impervious to mechanical influence when mounted on surfaces of dynamically changing soft matters have great potential for next-generation implantable bioelectronic devices. Here, deformable field-effect transistors (FETs) composed of single organic nanowires (NWs) as the semiconductor are presented. The NWs are composed of fused thiophene diketopyrrolopyrrole based polymer semiconductor and high-molecular-weight polyethylene oxide as both the molecular binder and deformability enhancer. The obtained transistors show high field-effect mobility >8 cm2 V-1 s-1 with poly(vinylidenefluoride-co-trifluoroethylene) polymer dielectric and can easily be deformed by applied strains (both 100% tensile and compressive strains). The electrical reliability and mechanical durability of the NWs can be significantly enhanced by forming serpentine-like structures of the NWs. Remarkably, the fully deformable NW FETs withstand 3D volume changes (>1700% and reverting back to original state) of a rubber balloon with constant current output, on the surface of which it is attached. The deformable transistors can robustly operate without noticeable degradation on a mechanically dynamic soft matter surface, e.g., a pulsating balloon (pulse rate: 40 min-1 (0.67 Hz) and 40% volume expansion) that mimics a beating heart, which underscores its potential for future biomedical applications.

  View details for DOI 10.1002/adma.201704401

  View details for PubMedID 29315845

• In Situ Investigation on the Nanoscale Capture and Evolution of Aerosols on Nanofibers NANO LETTERS Zhang, R., Liu, B., Yang, A., Zhu, Y., Liu, C., Zhou, G., Sun, J., Hsu, P., Zhao, W., Lin, D., Liu, Y., Pei, A., Xie, J., Chen, W., Xu, J., Jin, Y., Wu, T., Huang, X., Cui, Y. 2018; 18 (2): 1130–38

  Abstract

  Aerosol-induced haze problem has become a serious environmental concern. Filtration is widely applied to remove aerosols from gas streams. Despite classical filtration theories, the nanoscale capture and evolution of aerosols is not yet clearly understood. Here we report an in situ investigation on the nanoscale capture and evolution of aerosols on polyimide nanofibers. We discovered different capture and evolution behaviors among three types of aerosols: wetting liquid droplets, nonwetting liquid droplets, and solid particles. The wetting droplets had small contact angles and could move, coalesce, and form axisymmetric conformations on polyimide nanofibers. In contrast, the nonwetting droplets had a large contact angle on polyimide nanofibers and formed nonaxisymmetric conformations. Different from the liquid droplets, the solid particles could not move along the nanofibers and formed dendritic structures. This study provides an important insight for obtaining a deep understanding of the nanoscale capture and evolution of aerosols and benefits future design and development of advanced filters.

  View details for PubMedID 29297691

• High-efficiency oxygen reduction to hydrogen peroxide catalysed by oxidized carbon materials NATURE CATALYSIS Lu, Z., Chen, G., Siahrostami, S., Chen, Z., Liu, K., Xie, J., Liao, L., Wu, T., Lin, D., Liu, Y., Jaramillo, T. F., Norskov, J. K., Cui, Y. 2018; 1 (2): 156–62

  View details for DOI 10.1038/s41929-017-0017-x

  View details for Web of Science ID 000428621500015

• Gate-Induced Interfacial Superconductivity in 1T-SnSe2 NANO LETTERS Zeng, J., Liu, E., Fu, Y., Chen, Z., Pan, C., Wang, C., Wang, M., Wang, Y., Xu, K., Cai, S., Yan, X., Wang, Y., Liu, X., Wang, P., Liang, S., Cui, Y., Hwang, H. Y., Yuan, H., Miao, F. 2018; 18 (2): 1410–15

  Abstract

  Layered metal chalcogenide materials provide a versatile platform to investigate emergent phenomena and two-dimensional (2D) superconductivity at/near the atomically thin limit. In particular, gate-induced interfacial superconductivity realized by the use of an electric-double-layer transistor (EDLT) has greatly extended the capability to electrically induce superconductivity in oxides, nitrides, and transition metal chalcogenides and enable one to explore new physics, such as the Ising pairing mechanism. Exploiting gate-induced superconductivity in various materials can provide us with additional platforms to understand emergent interfacial superconductivity. Here, we report the discovery of gate-induced 2D superconductivity in layered 1T-SnSe2, a typical member of the main-group metal dichalcogenide (MDC) family, using an EDLT gating geometry. A superconducting transition temperature Tc ≈ 3.9 K was demonstrated at the EDL interface. The 2D nature of the superconductivity therein was further confirmed based on (1) a 2D Tinkham description of the angle-dependent upper critical field Bc2, (2) the existence of a quantum creep state as well as a large ratio of the coherence length to the thickness of superconductivity. Interestingly, the in-plane Bc2 approaching zero temperature was found to be 2-3 times higher than the Pauli limit, which might be related to an electric field-modulated spin-orbit interaction. Such results provide a new perspective to expand the material matrix available for gate-induced 2D superconductivity and the fundamental understanding of interfacial superconductivity.

  View details for PubMedID 29385803

• Robust Pinhole-free Li3N Solid Electrolyte Grown from Molten Lithium. ACS central science Li, Y., Sun, Y., Pei, A., Chen, K., Vailionis, A., Li, Y., Zheng, G., Sun, J., Cui, Y. 2018; 4 (1): 97–104

  Abstract

  Lithium metal is the ultimate anode choice for high energy density rechargeable lithium batteries. However, it suffers from inferior electrochemical performance and safety issues due to its high reactivity and the growth of lithium dendrites. It has long been desired to develop a materials coating on Li metal, which is pinhole-free, mechanically robust without fracture during Li metal deposition and stripping, and chemically stable against Li metal and liquid electrolytes, all while maintaining adequate ionic conductivity. However, such an ideal material coating has yet to be found. Here we report a novel synthesis method by reacting clean molten lithium foil directly with pure nitrogen gas to generate instantaneously a pinhole-free and ionically conductive alpha-Li3N film directly bonded onto Li metal foil. The film consists of highly textured large Li3N grains (tens of mum) with (001) crystalline planes parallel to the Li metal surface. The bonding between textured grains is strong, resulting in a mechanically robust film which does not crack even when bent to a 0.8 cm curvature radius and is found to maintain pinhole-free coverage during Li metal deposition and stripping. The measured ionic conductivity is up to 5.2 * 10-4 S cm-1, sufficient for maintaining regular current densities for controllable film thicknesses ranging from 2 to 30 mum. This Li3N coating is chemically stable, isolating the reactive metallic lithium from liquid electrolyte, prevents continuous electrolyte consumption during battery cycling, and promotes dendrite-free uniform lithium plating/stripping underneath. We demonstrated Li|Li4Ti5O12 cells with stable and flat potential profiles for 500 cycles without capacity decay or an increase in potential hysteresis.

  View details for PubMedID 29392181

• Robust and conductive two-dimensional metal-organic frameworks with exceptionally high volumetric and areal capacitance NATURE ENERGY Feng, D., Lei, T., Lukatskaya, M. R., Park, J., Huang, Z., Lee, M., Shaw, L., Chen, S., Yakovenko, A. A., Kulkarni, A., Xiao, J., Fredrickson, K., Tok, J. B., Zou, X., Cui, Y., Bao, Z. 2018; 3 (1): 30–36

  View details for DOI 10.1038/s41560-017-0044-5

  View details for Web of Science ID 000419976100011

• A general prelithiation approach for group IV elements and corresponding oxides ENERGY STORAGE MATERIALS Zhao, J., Sun, J., Pei, A., Zhou, G., Yan, K., Liu, Y., Lin, D., Cui, Y. 2018; 10: 275–81

  View details for DOI 10.1016/j.ensm.2017.06.013

  View details for Web of Science ID 000418533600029

• Lithium Metal Anodes: A Recipe for Protection JOULE Liu, Y., Cui, Y. 2017; 1 (4): 649–50

  View details for DOI 10.1016/j.joule.2017.12.001

  View details for Web of Science ID 000425302500006

• Design of Complex Nanomaterials for Energy Storage: Past Success and Future Opportunity. Accounts of chemical research Liu, Y., Zhou, G., Liu, K., Cui, Y. 2017; 50 (12): 2895-2905

  Abstract

  The development of next-generation lithium-based rechargeable batteries with high energy density, low cost, and improved safety is a great challenge with profound technological significance for portable electronics, electric vehicles, and grid-scale energy storage. Specifically, advanced lithium battery chemistries call for a paradigm shift to electrodes with high Li to host ratio based on a conversion or alloying mechanism, where the increased capacity is often accompanied by drastic volumetric changes, significant bond breaking, limited electronic/ionic conductivity, and unstable electrode/electrolyte interphase. Fortunately, the rapid progress of nanotechnology over the past decade has been offering battery researchers effective means to tackle some of the most pressing issues for next-generation battery chemistries. The major applications of nanotechnology in batteries can be summarized as follows: First, by reduction of the dimensions of the electrode materials, the cracking threshold of the material upon lithiation can be overcome, at the same time facilitating electron/ion transport within the electrode. Second, nanotechnology also provides powerful methods to generate various surface-coating and functionalization layers on electrode materials, protecting them from side reactions in the battery environment. Finally, nanotechnology gives people the flexibility to engineer each and every single component within a battery (separator, current collector, etc.), bringing novel functions to batteries that are unachievable by conventional methods. Thus, this Account aims to highlight the crucial role of nanotechnology in advanced battery systems. Because of the limited space, we will mainly assess representative examples of rational nanomaterials design with complexity for silicon and lithium metal anodes, which have shown great promise in constraining their large volume changes and the repeated solid-electrolyte interphase formation during cycling. Noticeably, the roadmap delineating the gradual improvement of silicon anodes with a span of 11 generations of materials designs developed in our group is discussed in order to reflect how nanotechnology could guide battery research step by step toward practical applications. Subsequently, we summarize efforts to construct nanostructured composite sulfur cathodes with improved electronic conductivity and effective soluble species encapsulation for maximizing the utilization of active material, cycle life, and system efficiency. We emphasize carbon-based materials and, importantly, materials with polar surfaces for sulfur entrapment. We then briefly discuss nanomaterials strategies to improve the ionic conductivity of solid polymer electrolytes by means of incorporating high-surface-area and, importantly, high-aspect-ratio secondary-phase fillers for continuous, low-tortuosity ionic transport pathways. Finally, critical innovations that have been brought to the area of grid-scale energy storage and battery safety by nanotechnology are also succinctly reviewed.

  View details for DOI 10.1021/acs.accounts.7b00450

  View details for PubMedID 29206446

• Transition-Metal Single Atoms in a Graphene Shell as Active Centers for Highly Efficient Artificial Photosynthesis CHEM Jiang, K., Siahrostami, S., Akey, A. J., Li, Y., Lu, Z., Lattimer, J., Hu, Y., Stokes, C., Gangishetty, M., Chen, G., Zhou, Y., Hill, W., Cai, W., Bell, D., Chan, K., Norskov, J. K., Cui, Y., Wang, H. 2017; 3 (6): 950–60

  View details for DOI 10.1016/j.chempr.2017.09.014

  View details for Web of Science ID 000418335800008

• Nanoscale perspective: Materials designs and understandings in lithium metal anodes NANO RESEARCH Lin, D., Liu, Y., Pei, A., Cui, Y. 2017; 10 (12): 4003–26

  View details for DOI 10.1007/s12274-017-1596-1

  View details for Web of Science ID 000417196000004

• Photoinduced Field-Effect Passivation from Negative Carrier Accumulation for High-Efficiency Silicon/Organic Heterojunction Solar Cells ACS NANO Liu, Z., Yang, Z., Wu, S., Zhu, J., Guo, W., Sheng, J., Ye, J., Cui, Y. 2017; 11 (12): 12687–95

  Abstract

  Carrier recombination and light management of the dopant-free silicon/organic heterojunction solar cells (HSCs) based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) are the critical factors in developing high-efficiency photovoltaic devices. However, the traditional passivation technologies can hardly provide efficient surface passivation on the front surface of Si. In this study, a photoinduced electric field was induced in a bilayer antireflective coating (ARC) of polydimethylsiloxane (PDMS) and titanium oxide (TiO2) films, due to formation of an accumulation layer of negative carriers (O2- species) under UV (sunlight) illumination. This photoinduced field not only suppressed the silicon surface recombination but also enhanced the built-in potential of HSCs with 84 mV increment. In addition, this photoactive ARC also displayed the outstanding light-trapping capability. The front PEDOT:PSS/Si HSC with the saturated O2- received a champion PCE of 15.51% under AM 1.5 simulated sunlight illumination. It was clearly demonstrated that the photoinduced electric field was a simple, efficient, and low-cost method for the surface passivation and contributed to achieve a high efficiency when applied in the Si/PEDOT:PSS HSCs.

  View details for PubMedID 29215861

• Design of Complex Nanomaterials for Energy Storage: Past Success and Future Opportunity Published as part of the Accounts of Chemical Research special issue "Energy Storage: Complexities Among Materials and Interfaces at Multiple Length Scales" ACCOUNTS OF CHEMICAL RESEARCH Liu, Y., Zhou, G., Liu, K., Cui, Y. 2017; 50 (12): 2895–2905

  View details for DOI 10.1021/acs.accounts.7b00450

  View details for Web of Science ID 000418626000003

• Strong texturing of lithium metal in batteries PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Shi, F., Pei, A., Vailionis, A., Xie, J., Liu, B., Zhao, J., Gong, Y., Cui, Y. 2017; 114 (46): 12138–43

  Abstract

  Lithium, with its high theoretical specific capacity and lowest electrochemical potential, has been recognized as the ultimate negative electrode material for next-generation lithium-based high-energy-density batteries. However, a key challenge that has yet to be overcome is the inferior reversibility of Li plating and stripping, typically thought to be related to the uncontrollable morphology evolution of the Li anode during cycling. Here we show that Li-metal texturing (preferential crystallographic orientation) occurs during electrochemical deposition, which governs the morphological change of the Li anode. X-ray diffraction pole-figure analysis demonstrates that the texture of Li deposits is primarily dependent on the type of additive or cross-over molecule from the cathode side. With adsorbed additives, like LiNO3 and polysulfide, the lithium deposits are strongly textured, with Li (110) planes parallel to the substrate, and thus exhibit uniform, rounded morphology. A growth diagram of lithium deposits is given to connect various texture and morphology scenarios for different battery electrolytes. This understanding of lithium electrocrystallization from the crystallographic point of view provides significant insight for future lithium anode materials design in high-energy-density batteries.

  View details for PubMedID 29087316

• Stretchable Lithium-Ion Batteries Enabled by Device-Scaled Wavy Structure and Elastic-Sticky Separator ADVANCED ENERGY MATERIALS Liu, W., Chen, J., Chen, Z., Liu, K., Zhou, G., Sun, Y., Song, M., Bao, Z., Cui, Y. 2017; 7 (21)

  View details for DOI 10.1002/aenm.201701076

  View details for Web of Science ID 000414711100018

• Engineering the surface of LiCoO2 electrodes using atomic layer deposition for stable high-voltage lithium ion batteries NANO RESEARCH Xie, J., Zhao, J., Liu, Y., Wang, H., Liu, C., Wu, T., Hsu, P., Lin, D., Jin, Y., Cui, Y. 2017; 10 (11): 3754–64

  View details for DOI 10.1007/s12274-017-1588-1

  View details for Web of Science ID 000413100400014

• Stitching h-BN by atomic layer deposition of LiF as a stable interface for lithium metal anode. Science advances Xie, J., Liao, L., Gong, Y., Li, Y., Shi, F., Pei, A., Sun, J., Zhang, R., Kong, B., Subbaraman, R., Christensen, J., Cui, Y. 2017; 3 (11): eaao3170

  Abstract

  Defects are important features in two-dimensional (2D) materials that have a strong influence on their chemical and physical properties. Through the enhanced chemical reactivity at defect sites (point defects, line defects, etc.), one can selectively functionalize 2D materials via chemical reactions and thereby tune their physical properties. We demonstrate the selective atomic layer deposition of LiF on defect sites of h-BN prepared by chemical vapor deposition. The LiF deposits primarily on the line and point defects of h-BN, thereby creating seams that hold the h-BN crystallites together. The chemically and mechanically stable hybrid LiF/h-BN film successfully suppresses lithium dendrite formation during both the initial electrochemical deposition onto a copper foil and the subsequent cycling. The protected lithium electrodes exhibit good cycling behavior with more than 300 cycles at relatively high coulombic efficiency (>95%) in an additive-free carbonate electrolyte.

  View details for DOI 10.1126/sciadv.aao3170

  View details for PubMedID 29202031

  View details for PubMedCentralID PMC5707176

• A dual-mode textile for human body radiative heating and cooling SCIENCE ADVANCES Hsu, P., Liu, C., Song, A. Y., Zhang, Z., Peng, Y., Xie, J., Liu, K., Wu, C., Catrysse, P. B., Cai, L., Zhai, S., Majumdar, A., Fan, S., Cui, Y. 2017; 3 (11): e1700895

  Abstract

  Maintaining human body temperature is one of the most basic needs for living, which often consumes a huge amount of energy to keep the ambient temperature constant. To expand the ambient temperature range while maintaining human thermal comfort, the concept of personal thermal management has been recently demonstrated in heating and cooling textiles separately through human body infrared radiation control. Realizing these two opposite functions within the same textile would represent an exciting scientific challenge and a significant technological advancement. We demonstrate a dual-mode textile that can perform both passive radiative heating and cooling using the same piece of textile without any energy input. The dual-mode textile is composed of a bilayer emitter embedded inside an infrared-transparent nanoporous polyethylene (nanoPE) layer. We demonstrate that the asymmetrical characteristics of both emissivity and nanoPE thickness can result in two different heat transfer coefficients and achieve heating when the low-emissivity layer is facing outside and cooling by wearing the textile inside out when the high-emissivity layer is facing outside. This can expand the thermal comfort zone by 6.5°C. Numerical fitting of the data further predicts 14.7°C of comfort zone expansion for dual-mode textiles with large emissivity contrast.

  View details for PubMedID 29296678

• Stitching h-BN by atomic layer deposition of LiF as a stable interface for lithium metal anode SCIENCE ADVANCES Xie, J., Liao, L., Gong, Y., Li, Y., Shi, F., Pei, A., Sun, J., Zhang, R., Kong, B., Subbaraman, R., Christensen, J., Cui, Y. 2017; 3 (11)

  View details for DOI 10.1126/sciadv.aao3170

  View details for Web of Science ID 000418002000051

• High-performance sodium-organic battery by realizing four-sodium storage in disodium rhodizonate NATURE ENERGY Lee, M., Hong, J., Lopez, J., Sun, Y., Feng, D., Lim, K., Chueh, W. C., Toney, M. F., Cui, Y., Bao, Z. 2017; 2 (11)

  View details for DOI 10.1038/s41560-017-0014-y

  View details for Web of Science ID 000418243200002

• Atomic structure of sensitive battery materials and Interfaces revealed by cryo-electron microscopy SCIENCE Li, Y., Li, Y., Pei, A., Yan, K., Sun, Y., Wu, C., Joubert, L., Chin, R., Koh, A., Yu, Y., Perrino, J., Butz, B., Chu, S., Cui, Y. 2017; 358 (6362): 506–10

  Abstract

  Whereas standard transmission electron microscopy studies are unable to preserve the native state of chemically reactive and beam-sensitive battery materials after operation, such materials remain pristine at cryogenic conditions. It is then possible to atomically resolve individual lithium metal atoms and their interface with the solid electrolyte interphase (SEI). We observe that dendrites in carbonate-based electrolytes grow along the <111> (preferred), <110>, or <211> directions as faceted, single-crystalline nanowires. These growth directions can change at kinks with no observable crystallographic defect. Furthermore, we reveal distinct SEI nanostructures formed in different electrolytes.

  View details for PubMedID 29074771

• Transforming from planar to three-dimensional lithium with flowable interphase for solid lithium metal batteries SCIENCE ADVANCES Liu, Y., Lin, D., Jin, Y., Liu, K., Tao, X., Zhang, Q., Zhang, X., Cui, Y. 2017; 3 (10): eaao0713

  Abstract

  Solid-state lithium (Li) metal batteries are prominent among next-generation energy storage technologies due to their significantly high energy density and reduced safety risks. Previously, solid electrolytes have been intensively studied and several materials with high ionic conductivity have been identified. However, there are still at least three obstacles before making the Li metal foil-based solid-state systems viable, namely, high interfacial resistance at the Li/electrolyte interface, low areal capacity, and poor power output. The problems are addressed by incorporating a flowable interfacial layer and three-dimensional Li into the system. The flowable interfacial layer can accommodate the interfacial fluctuation and guarantee excellent adhesion at all time, whereas the three-dimensional Li significantly reduces the interfacial fluctuation from the whole electrode level (tens of micrometers) to local scale (submicrometer) and also decreases the effective current density for high-capacity and high-power operations. As a consequence, both symmetric and full-cell configurations can achieve greatly improved electrochemical performances in comparison to the conventional Li foil, which are among the best reported values in the literature. Noticeably, solid-state full cells paired with high-mass loading LiFePO4 exhibited, at 80°C, a satisfactory specific capacity even at a rate of 5 C (110 mA·hour g-1) and a capacity retention of 93.6% after 300 cycles at a current density of 3 mA cm-2 using a composite solid electrolyte middle layer. In addition, when a ceramic electrolyte middle layer was adopted, stable cycling with greatly improved capacity could even be realized at room temperature.

  View details for PubMedID 29062894

• Air-stable and freestanding lithium alloy/graphene foil as an alternative to lithium metal anodes. Nature nanotechnology Zhao, J., Zhou, G., Yan, K., Xie, J., Li, Y., Liao, L., Jin, Y., Liu, K., Hsu, P. C., Wang, J., Cheng, H. M., Cui, Y. 2017; 12 (10): 993-999

  Abstract

  Developing high-capacity anodes is a must to improve the energy density of lithium batteries for electric vehicle applications. Alloy anodes are one promising option, but without pre-stored lithium, the overall energy density is limited by the low-capacity lithium metal oxide cathodes. Recently, lithium metal has been revived as a high-capacity anode, but faces several challenges owing to its high reactivity and uncontrolled dendrite growth. Here, we show a series of Li-containing foils inheriting the desirable properties of alloy anodes and pure metal anodes. They consist of densely packed LixM (M = Si, Sn, or Al) nanoparticles encapsulated by large graphene sheets. With the protection of graphene sheets, the large and freestanding LixM/graphene foils are stable in different air conditions. With fully expanded LixSi confined in the highly conductive and chemically stable graphene matrix, this LixSi/graphene foil maintains a stable structure and cyclability in half cells (400 cycles with 98% capacity retention). This foil is also paired with high-capacity Li-free V2O5 and sulfur cathodes to achieve stable full-cell cycling.

  View details for DOI 10.1038/nnano.2017.129

  View details for PubMedID 28692059

• Non-encapsulation approach for high-performance Li-S batteries through controlled nucleation and growth NATURE ENERGY Pan, H., Chen, J., Cao, R., Murugesan, V., Rajput, N., Han, K., Persson, K., Estevez, L., Engelhard, M. H., Zhang, J., Mueller, K. T., Cui, Y., Shao, Y., Liu, J. 2017; 2 (10)

  View details for DOI 10.1038/s41560-017-0005-z

  View details for Web of Science ID 000415191200016

• Air-stable and freestanding lithium alloy/graphene foil as an alternative to lithium metal anodes NATURE NANOTECHNOLOGY Zhao, J., Zhou, G., Yan, K., Xie, J., Li, Y., Liao, L., Jin, Y., Liu, K., Hsu, P., Wang, J., Cheng, H., Cui, Y. 2017; 12 (10): 993–99

  View details for DOI 10.1038/NNANO.2017.129

  View details for Web of Science ID 000412432500018

• Warming up human body by nanoporous metallized polyethylene textile NATURE COMMUNICATIONS Cai, L., Song, A. Y., Wu, P., Hsu, P., Peng, Y., Chen, J., Liu, C., Catrysse, P. B., Liu, Y., Yang, A., Zhou, C., Zhou, C., Fan, S., Cui, Y. 2017; 8: 496

  Abstract

  Space heating accounts for the largest energy end-use of buildings that imposes significant burden on the society. The energy wasted for heating the empty space of the entire building can be saved by passively heating the immediate environment around the human body. Here, we demonstrate a nanophotonic structure textile with tailored infrared (IR) property for passive personal heating using nanoporous metallized polyethylene. By constructing an IR-reflective layer on an IR-transparent layer with embedded nanopores, the nanoporous metallized polyethylene textile achieves a minimal IR emissivity (10.1%) on the outer surface that effectively suppresses heat radiation loss without sacrificing wearing comfort. This enables 7.1 °C decrease of the set-point compared to normal textile, greatly outperforming other radiative heating textiles by more than 3 °C. This large set-point expansion can save more than 35% of building heating energy in a cost-effective way, and ultimately contribute to the relief of global energy and climate issues.Energy wasted for heating the empty space of the entire building can be saved by passively heating the immediate environment around the human body. Here, the authors show a nanophotonic structure textile with tailored infrared property for passive personal heating using nanoporous metallized polyethylene.

  View details for PubMedID 28928427

• Gated tuned superconductivity and phonon softening in monolayer and bilayer MoS2 NPJ QUANTUM MATERIALS Fu, Y., Liu, E., Yuan, H., Tang, P., Lian, B., Xu, G., Zeng, J., Chen, Z., Wang, Y., Zhou, W., Xu, K., Gao, A., Pan, C., Wang, M., Wang, B., Zhang, S., Cui, Y., Hwang, H. Y., Miao, F. 2017; 2

  View details for DOI 10.1038/s41535-017-0056-1

  View details for Web of Science ID 000410773600001

• Reactivation of dead sulfide species in lithium polysulfide flow battery for grid scale energy storage NATURE COMMUNICATIONS Jin, Y., Zhou, G., Shi, F., Zhuo, D., Zhao, J., Liu, K., Liu, Y., Zu, C., Chen, W., Zhang, R., Huang, X., Cui, Y. 2017; 8: 462

  Abstract

  Lithium polysulfide batteries possess several favorable attributes including low cost and high energy density for grid energy storage. However, the precipitation of insoluble and irreversible sulfide species on the surface of carbon and lithium (called "dead" sulfide species) leads to continuous capacity degradation in high mass loading cells, which represents a great challenge. To address this problem, herein we propose a strategy to reactivate dead sulfide species by reacting them with sulfur powder with stirring and heating (70 °C) to recover the cell capacity, and further demonstrate a flow battery system based on the reactivation approach. As a result, ultrahigh mass loading (0.125 g cm-3, 2 g sulfur in a single cell), high volumetric energy density (135 Wh L-1), good cycle life, and high single-cell capacity are achieved. The high volumetric energy density indicates its promising application for future grid energy storage.Lithium polysulfide batteries suffer from the precipitation of insoluble and irreversible sulfide species on the surface of carbon and lithium. Here the authors show a reactivation strategy by a reaction with cheap sulfur powder under stirring and heating to recover the cell capacity.

  View details for PubMedID 28878273

• Electrical tuning of a quantum plasmonic resonance NATURE NANOTECHNOLOGY Liu, X., Kang, H., Yuan, H., Park, J., Kim, S., Cui, Y., Hwang, H. Y., Brongersma, M. L. 2017; 12 (9): 866-+

  Abstract

  Surface plasmon (SP) excitations in metals facilitate confinement of light into deep-subwavelength volumes and can induce strong light-matter interaction. Generally, the SP resonances supported by noble metal nanostructures are explained well by classical models, at least until the nanostructure size is decreased to a few nanometres, approaching the Fermi wavelength λF of the electrons. Although there is a long history of reports on quantum size effects in the plasmonic response of nanometre-sized metal particles, systematic experimental studies have been hindered by inhomogeneous broadening in ensemble measurements, as well as imperfect control over size, shape, faceting, surface reconstructions, contamination, charging effects and surface roughness in single-particle measurements. In particular, observation of the quantum size effect in metallic films and its tuning with thickness has been challenging as they only confine carriers in one direction. Here, we show active tuning of quantum size effects in SP resonances supported by a 20-nm-thick metallic film of indium tin oxide (ITO), a plasmonic material serving as a low-carrier-density Drude metal. An ionic liquid (IL) is used to electrically gate and partially deplete the ITO layer. The experiment shows a controllable and reversible blue-shift in the SP resonance above a critical voltage. A quantum-mechanical model including the quantum size effect reproduces the experimental results, whereas a classical model only predicts a red shift.

  View details for PubMedID 28604706

• High performance lithium metal anode with a soft and flowable polymer coating Lopez, J., Pei, A., Cui, Y., Bao, Z. AMER CHEMICAL SOC. 2017

  View details for Web of Science ID 000429556704234

• Se. Nature nanotechnology Wu, J., Yuan, H., Meng, M., Chen, C., Sun, Y., Chen, Z., Dang, W., Tan, C., Liu, Y., Yin, J., Zhou, Y., Huang, S., Xu, H. Q., Cui, Y., Hwang, H. Y., Liu, Z., Chen, Y., Yan, B., Peng, H. 2017; 12 (6): 530-534

  Abstract

  High-mobility semiconducting ultrathin films form the basis of modern electronics, and may lead to the scalable fabrication of highly performing devices. Because the ultrathin limit cannot be reached for traditional semiconductors, identifying new two-dimensional materials with both high carrier mobility and a large electronic bandgap is a pivotal goal of fundamental research. However, air-stable ultrathin semiconducting materials with superior performances remain elusive at present. Here, we report ultrathin films of non-encapsulated layered Bi2O2Se, grown by chemical vapour deposition, which demonstrate excellent air stability and high-mobility semiconducting behaviour. We observe bandgap values of ∼0.8 eV, which are strongly dependent on the film thickness due to quantum-confinement effects. An ultrahigh Hall mobility value of >20,000 cm(2) V(-1) s(-1) is measured in as-grown Bi2O2Se nanoflakes at low temperatures. This value is comparable to what is observed in graphene grown by chemical vapour deposition and at the LaAlO3-SrTiO3 interface, making the detection of Shubnikov-de Haas quantum oscillations possible. Top-gated field-effect transistors based on Bi2O2Se crystals down to the bilayer limit exhibit high Hall mobility values (up to 450 cm(2) V(-1) s(-1)), large current on/off ratios (>10(6)) and near-ideal subthreshold swing values (∼65 mV dec(-1)) at room temperature. Our results make Bi2O2Se a promising candidate for future high-speed and low-power electronic applications.

  View details for DOI 10.1038/nnano.2017.43

  View details for PubMedID 28369044

• Nanoscale manipulation of membrane curvature for probing endocytosis in live cells. Nature nanotechnology Zhao, W., Hanson, L., Lou, H., Akamatsu, M., Chowdary, P. D., Santoro, F., Marks, J. R., Grassart, A., Drubin, D. G., Cui, Y., Cui, B. 2017

  Abstract

  Clathrin-mediated endocytosis (CME) involves nanoscale bending and inward budding of the plasma membrane, by which cells regulate both the distribution of membrane proteins and the entry of extracellular species. Extensive studies have shown that CME proteins actively modulate the plasma membrane curvature. However, the reciprocal regulation of how the plasma membrane curvature affects the activities of endocytic proteins is much less explored, despite studies suggesting that membrane curvature itself can trigger biochemical reactions. This gap in our understanding is largely due to technical challenges in precisely controlling the membrane curvature in live cells. In this work, we use patterned nanostructures to generate well-defined membrane curvatures ranging from +50 nm to -500 nm radius of curvature. We find that the positively curved membranes are CME hotspots, and that key CME proteins, clathrin and dynamin, show a strong preference towards positive membrane curvatures with a radius <200 nm. Of ten CME-related proteins we examined, all show preferences for positively curved membrane. In contrast, other membrane-associated proteins and non-CME endocytic protein caveolin1 show no such curvature preference. Therefore, nanostructured substrates constitute a novel tool for investigating curvature-dependent processes in live cells.

  View details for DOI 10.1038/nnano.2017.98

  View details for PubMedID 28581510

• Conformal Lithium Fluoride Protection Layer on Three-Dimensional Lithium by Nonhazardous Gaseous Reagent Freon. Nano letters Lin, D., Liu, Y., Chen, W., Zhou, G., Liu, K., Dunn, B., Cui, Y. 2017

  Abstract

  Research on lithium (Li) metal chemistry has been rapidly gaining momentum nowadays not only because of the appealing high theoretical capacity, but also its indispensable role in the next-generation Li-S and Li-air batteries. However, two root problems of Li metal, namely high reactivity and infinite relative volume change during cycling, bring about numerous other challenges that impede its practical applications. In the past, extensive studies have targeted these two root causes by either improving interfacial stability or constructing a stable host. However, efficient surface passivation on three-dimensional (3D) Li is still absent. Here, we develop a conformal LiF coating technique on Li surface with commercial Freon R134a as the reagent. In contrast to solid/liquid reagents, gaseous Freon exhibits not only nontoxicity and well-controlled reactivity, but also much better permeability that enables a uniform LiF coating even on 3D Li. By applying a LiF coating onto 3D layered Li-reduced graphene oxide (Li-rGO) electrodes, highly reduced side reactions and enhanced cycling stability without overpotential augment for over 200 cycles were proven in symmetric cells. Furthermore, Li-S cells with LiF protected Li-rGO exhibit significantly improved cyclability and Coulombic efficiency, while excellent rate capability (∼800 mAh g(-1) at 2 C) can still be retained.

  View details for DOI 10.1021/acs.nanolett.7b01020

  View details for PubMedID 28535068

• /Carbon Foam and Polymer. Nano letters Tao, X., Liu, Y., Liu, W., Zhou, G., Zhao, J., Lin, D., Zu, C., Sheng, O., Zhang, W., Lee, H., Cui, Y. 2017; 17 (5): 2967-2972

  Abstract

  An all solid-state lithium-ion battery with high energy density and high safety is a promising solution for a next-generation energy storage system. High interface resistance of the electrodes and poor ion conductivity of solid-state electrolytes are two main challenges for solid-state batteries, which require operation at elevated temperatures of 60-90 °C. Herein, we report the facile synthesis of Al(3+)/Nb(5+) codoped cubic Li7La3Zr2O12 (LLZO) nanoparticles and LLZO nanoparticle-decorated porous carbon foam (LLZO@C) by the one-step Pechini sol-gel method. The LLZO nanoparticle-filled poly(ethylene oxide) electrolyte shows improved conductivity compared with filler-free samples. The sulfur composite cathode based on LLZO@C can deliver an attractive specific capacity of >900 mAh g(-1) at the human body temperature 37 °C and a high capacity of 1210 and 1556 mAh g(-1) at 50 and 70 °C, respectively. In addition, the solid-state Li-S batteries exhibit high Coulombic efficiency and show remarkably stable cycling performance.

  View details for DOI 10.1021/acs.nanolett.7b00221

  View details for PubMedID 28388080

• for Oxygen Evolution Reaction. Journal of the American Chemical Society Lu, Z., Chen, G., Li, Y., Wang, H., Xie, J., Liao, L., Liu, C., Liu, Y., Wu, T., Li, Y., Luntz, A. C., Bajdich, M., Cui, Y. 2017; 139 (17): 6270-6276

  Abstract

  Identification of active sites for catalytic processes has both fundamental and technological implications for rational design of future catalysts. Herein, we study the active surfaces of layered lithium cobalt oxide (LCO) for the oxygen evolution reaction (OER) using the enhancement effect of electrochemical delithiation (De-LCO). Our theoretical results indicate that the most stable (0001) surface has a very large overpotential for OER independent of lithium content. In contrast, edge sites such as the nonpolar (112̅0) and polar (011̅2) surfaces are predicted to be highly active and dependent on (de)lithiation. The effect of lithium extraction from LCO on the surfaces and their OER activities can be understood by the increase of Co(4+) sites relative to Co(3+) and by the shift of active oxygen 2p states. Experimentally, it is demonstrated that LCO nanosheets, which dominantly expose the (0001) surface show negligible OER enhancement upon delithiation. However, a noticeable increase in OER activity (∼0.1 V in overpotential shift at 10 mA cm(-2)) is observed for the LCO nanoparticles, where the basal plane is greatly diminished to expose the edge sites, consistent with the theoretical simulations. Additionally, we find that the OER activity of De-LCO nanosheets can be improved if we adopt an acid etching method on LCO to create more active edge sites, which in turn provides a strong evidence for the theoretical indication.

  View details for DOI 10.1021/jacs.7b02622

  View details for PubMedID 28418250

• Three-dimensional stable lithium metal anode with nanoscale lithium islands embedded in ionically conductive solid matrix PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Lin, D., Zhao, J., Sun, J., Yao, H., Liu, Y., Yan, K., Cui, Y. 2017; 114 (18): 4613-4618

  Abstract

  Rechargeable batteries based on lithium (Li) metal chemistry are attractive for next-generation electrochemical energy storage. Nevertheless, excessive dendrite growth, infinite relative dimension change, severe side reactions, and limited power output severely impede their practical applications. Although exciting progress has been made to solve parts of the above issues, a versatile solution is still absent. Here, a Li-ion conductive framework was developed as a stable "host" and efficient surface protection to address the multifaceted problems, which is a significant step forward compared with previous host concepts. This was fulfilled by reacting overstoichiometry of Li with SiO. The as-formed LixSi-Li2O matrix would not only enable constant electrode-level volume, but also protect the embedded Li from direct exposure to electrolyte. Because uniform Li nucleation and deposition can be fulfilled owing to the high-density active Li domains, the as-obtained nanocomposite electrode exhibits low polarization, stable cycling, and high-power output (up to 10 mA/cm(2)) even in carbonate electrolytes. The Li-S prototype cells further exhibited highly improved capacity retention under high-power operation (∼600 mAh/g at 6.69 mA/cm(2)). The all-around improvement on electrochemical performance sheds light on the effectiveness of the design principle for developing safe and stable Li metal anodes.

  View details for DOI 10.1073/pnas.1619489114

  View details for PubMedID 28416664

• Solid-State Lithium Sulfur Batteries Operated at 37 degrees C with Composites of Nanostructured Li7La3Zr2O12/Carbon Foam and Polymer NANO LETTERS Tao, X., Liu, Y., Liu, W., Zhou, G., Zhao, J., Lin, D., Zu, C., Sheng, O., Zhang, W., Lee, H., Cui, Y. 2017; 17 (5): 2967-2972

  Abstract

  An all solid-state lithium-ion battery with high energy density and high safety is a promising solution for a next-generation energy storage system. High interface resistance of the electrodes and poor ion conductivity of solid-state electrolytes are two main challenges for solid-state batteries, which require operation at elevated temperatures of 60-90 °C. Herein, we report the facile synthesis of Al(3+)/Nb(5+) codoped cubic Li7La3Zr2O12 (LLZO) nanoparticles and LLZO nanoparticle-decorated porous carbon foam (LLZO@C) by the one-step Pechini sol-gel method. The LLZO nanoparticle-filled poly(ethylene oxide) electrolyte shows improved conductivity compared with filler-free samples. The sulfur composite cathode based on LLZO@C can deliver an attractive specific capacity of >900 mAh g(-1) at the human body temperature 37 °C and a high capacity of 1210 and 1556 mAh g(-1) at 50 and 70 °C, respectively. In addition, the solid-state Li-S batteries exhibit high Coulombic efficiency and show remarkably stable cycling performance.

  View details for DOI 10.1021/acs.nanolett.7b00221

  View details for Web of Science ID 000401307300033

• Sulfiphilic Nickel Phosphosulfide Enabled Li2S Impregnation in 3D Graphene Cages for Li-S Batteries ADVANCED MATERIALS Zhou, G., Sun, J., Jin, Y., Chen, W., Zu, C., Zhang, R., Qiu, Y., Zhao, J., Zhuo, D., Liu, Y., Tao, X., Liu, W., Yan, K., Lee, H. R., Cui, Y. 2017; 29 (12)

  Abstract

  A 3D graphene cage with a thin layer of electrodeposited nickel phosphosulfide for Li2S impregnation, using ternary nickel phosphosulphide as a highly conductive coating layer for stabilized polysulfide chemistry, is accomplished by the combination of theoretical and experimental studies. The 3D interconnected graphene cage structure leads to high capacity, good rate capability and excellent cycling stability in a Li2S cathode.

  View details for DOI 10.1002/adma.201603366

  View details for Web of Science ID 000396998800001

• . Nano letters Zhang, J., Sun, J., Li, Y., Shi, F., Cui, Y. 2017; 17 (3): 1741-1747

  Abstract

  Intercalation of exotic atoms or molecules into the layered materials remains an extensively investigated subject in current physics and chemistry. However, traditionally melt-growth and chemical interaction strategies are either limited by insufficiency of intercalant concentrations or destitute of accurate controllability. Here, we have developed a general electrochemical intercalation method to efficaciously regulate the concentration of zerovalent copper atoms into layered Bi2Se3, followed by comprehensive experimental characterization and analyses. Up to 57% copper atoms (Cu6.7Bi2Se3) can be intercalated with no disruption to the host lattice. Meanwhile the unconventional resistance dip accompanied by a hysteresis loop below 40 K, as well as the emergence of new Raman peak in CuxBi2Se3, is a distinct manifestation of the interplay between intercalated Cu atoms with Bi2Se3 host. Our work demonstrates a new methodology to study fundamentally new and unexpected physical behaviors in intercalated metastable materials.

  View details for DOI 10.1021/acs.nanolett.6b05062

  View details for PubMedID 28218538

• Reviving the lithium metal anode for high-energy batteries. Nature nanotechnology Lin, D., Liu, Y., Cui, Y. 2017; 12 (3): 194-206

  Abstract

  Lithium-ion batteries have had a profound impact on our daily life, but inherent limitations make it difficult for Li-ion chemistries to meet the growing demands for portable electronics, electric vehicles and grid-scale energy storage. Therefore, chemistries beyond Li-ion are currently being investigated and need to be made viable for commercial applications. The use of metallic Li is one of the most favoured choices for next-generation Li batteries, especially Li-S and Li-air systems. After falling into oblivion for several decades because of safety concerns, metallic Li is now ready for a revival, thanks to the development of investigative tools and nanotechnology-based solutions. In this Review, we first summarize the current understanding on Li anodes, then highlight the recent key progress in materials design and advanced characterization techniques, and finally discuss the opportunities and possible directions for future development of Li anodes in applications.

  View details for DOI 10.1038/nnano.2017.16

  View details for PubMedID 28265117

• An Artificial Solid Electrolyte Interphase with High Li-Ion Conductivity, Mechanical Strength, and Flexibility for Stable Lithium Metal Anodes. Advanced materials Liu, Y., Lin, D., Yuen, P. Y., Liu, K., Xie, J., Dauskardt, R. H., Cui, Y. 2017; 29 (10)

  Abstract

  An artificial solid electrolyte interphase (SEI) is demonstrated for the efficient and safe operation of a lithium metal anode. Composed of lithium-ion-conducting inorganic nanoparticles within a flexible polymer binder matrix, the rationally designed artificial SEI not only mechanically suppresses lithium dendrite formation but also promotes homogeneous lithium-ion flux, significantly enhancing the efficiency and cycle life of the lithium metal anode.

  View details for DOI 10.1002/adma.201605531

  View details for PubMedID 28032934

• Nanoscale Nucleation and Growth of Electrodeposited Lithium Metal. Nano letters Pei, A., Zheng, G., Shi, F., Li, Y., Cui, Y. 2017; 17 (2): 1132-1139

  Abstract

  Lithium metal has re-emerged as an exciting anode for high energy lithium-ion batteries due to its high specific capacity of 3860 mAh g(-1) and lowest electrochemical potential of all known materials. However, lithium has been plagued by the issues of dendrite formation, high chemical reactivity with electrolyte, and infinite relative volume expansion during plating and stripping, which present safety hazards and low cycling efficiency in batteries with lithium metal electrodes. There have been a lot of recent studies on Li metal although little work has focused on the initial nucleation and growth behavior of Li metal, neglecting a critical fundamental scientific foundation of Li plating. Here, we study experimentally the morphology of lithium in the early stages of nucleation and growth on planar copper electrodes in liquid organic electrolyte. We elucidate the dependence of lithium nuclei size, shape, and areal density on current rate, consistent with classical nucleation and growth theory. We found that the nuclei size is proportional to the inverse of overpotential and the number density of nuclei is proportional to the cubic power of overpotential. Based on this understanding, we propose a strategy to increase the uniformity of electrodeposited lithium on the electrode surface.

  View details for DOI 10.1021/acs.nanolett.6b04755

  View details for PubMedID 28072543

• Silicon/Organic Hybrid Solar Cells with 16.2% Efficiency and Improved Stability by Formation of Conformal Heterojunction Coating and Moisture-Resistant Capping Layer. Advanced materials He, J., Gao, P., Yang, Z., Yu, J., Yu, W., Zhang, Y., Sheng, J., Ye, J., Amine, J. C., Cui, Y. 2017

  Abstract

  Silicon/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) heterojunction solar cells with 16.2% efficiency and excellent stability are fabricated on pyramid-textured silicon substrates by applying a water-insoluble ester as capping layer. This shows that a conformal coating of PEDOT:PSS on textured silicon can greatly improve the junction quality with the main stability failure routes related to the moisture-induced poly(3,4-ethylenedioxythiophene) aggregations and the tunneling silicon oxide autothickening.

  View details for DOI 10.1002/adma.201606321

  View details for PubMedID 28151568

• Core-Shell Nanoparticle Coating as an Interfacial Layer for Dendrite Free Lithium Metal Anodes ACS CENTRAL SCIENCE Liu, W., Li, W., Zhuo, D., Zheng, G., Lu, Z., Liu, K., Cui, Y. 2017; 3 (2): 135-140

  Abstract

  Lithium metal based batteries represent a major challenge and opportunity in enabling a variety of devices requiring high-energy-density storage. However, dendritic lithium growth has limited the practical application of lithium metal anodes. Here we report a nanoporous, flexible and electrochemically stable coating of silica@poly(methyl methacrylate) (SiO2@PMMA) core-shell nanospheres as an interfacial layer on lithium metal anode. This interfacial layer is capable of inhibiting Li dendrite growth while sustaining ionic flux through it, which is attributed to the nanoscaled pores formed among the nanospheres. Enhanced Coulombic efficiencies during lithium charge/discharge cycles have been achieved at various current densities and areal capacities.

  View details for DOI 10.1021/acscentsci.6b00389

  View details for PubMedID 28280780

• Catalytic oxidation of Li2S on the surface of metal sulfides for Li-S batteries PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Zhou, G., Tian, H., Jin, Y., Tao, X., Liu, B., Zhang, R., Seh, Z. W., Zhuo, D., Liu, Y., Sun, J., Zhao, J., Zu, C., Wu, D. S., Zhang, Q., Cui, Y. 2017; 114 (5): 840-845

  Abstract

  Polysulfide binding and trapping to prevent dissolution into the electrolyte by a variety of materials has been well studied in Li-S batteries. Here we discover that some of those materials can play an important role as an activation catalyst to facilitate oxidation of the discharge product, Li2S, back to the charge product, sulfur. Combining theoretical calculations and experimental design, we select a series of metal sulfides as a model system to identify the key parameters in determining the energy barrier for Li2S oxidation and polysulfide adsorption. We demonstrate that the Li2S decomposition energy barrier is associated with the binding between isolated Li ions and the sulfur in sulfides; this is the main reason that sulfide materials can induce lower overpotential compared with commonly used carbon materials. Fundamental understanding of this reaction process is a crucial step toward rational design and screening of materials to achieve high reversible capacity and long cycle life in Li-S batteries.

  View details for DOI 10.1073/pnas.1615837114

  View details for PubMedID 28096362

• S Impregnation in 3D Graphene Cages for Li-S Batteries. Advanced materials Zhou, G., Sun, J., Jin, Y., Chen, W., Zu, C., Zhang, R., Qiu, Y., Zhao, J., Zhuo, D., Liu, Y., Tao, X., Liu, W., Yan, K., Lee, H. R., Cui, Y. 2017

  Abstract

  A 3D graphene cage with a thin layer of electrodeposited nickel phosphosulfide for Li2S impregnation, using ternary nickel phosphosulphide as a highly conductive coating layer for stabilized polysulfide chemistry, is accomplished by the combination of theoretical and experimental studies. The 3D interconnected graphene cage structure leads to high capacity, good rate capability and excellent cycling stability in a Li2S cathode.

  View details for DOI 10.1002/adma.201603366

  View details for PubMedID 28134456

• Extending the Life of Lithium-Based Rechargeable Batteries by Reaction of Lithium Dendrites with a Novel Silica Nanoparticle Sandwiched Separator ADVANCED MATERIALS Liu, K., Zhuo, D., Lee, H., Liu, W., Lin, D., Lu, Y., Cui, Y. 2017; 29 (4)

  Abstract

  A reaction-protective separator that slows the growth of lithium dendrites penetrating into the separator is produced by sandwiching silica nanoparticles between two polymer separators. The reaction between lithium dendrites and silica nanoparticles consumes the dendrites and can extend the life of the battery by approximately five times.

  View details for DOI 10.1002/adma.201603987

  View details for Web of Science ID 000392730500017

  View details for PubMedID 27874235

• Unsupervised clustering of quantitative image phenotypes reveals breast cancer subtypes with distinct prognoses and molecular pathways. Clinical cancer research : an official journal of the American Association for Cancer Research Wu, J., Cui, Y., Sun, X., Cao, G., Li, B., Ikeda, D. M., Kurian, A. W., Li, R. 2017

  Abstract

  To identify novel breast cancer subtypes by extracting quantitative imaging phenotypes of the tumor and surrounding parenchyma, and to elucidate the underlying biological underpinnings and evaluate the prognostic capacity for predicting recurrence-free survival (RFS).We retrospectively analyzed dynamic contrast-enhanced magnetic resonance imaging data of patients from a single-center discovery cohort (n=60) and an independent multi-center validation cohort (n=96). Quantitative image features were extracted to characterize tumor morphology, intra-tumor heterogeneity of contrast agent wash-in/wash-out patterns, and tumor-surrounding parenchyma enhancement. Based on these image features, we used unsupervised consensus clustering to identify robust imaging subtypes, and evaluated their clinical and biological relevance. We built a gene expression-based classifier of imaging subtypes and tested their prognostic significance in five additional cohorts with publically available gene expression data but without imaging data (n=1160).Three distinct imaging subtypes, i.e., homogeneous intratumoral enhancing, minimal parenchymal enhancing, and prominent parenchymal enhancing, were identified and validated. In the discovery cohort, imaging subtypes stratified patients with significantly different 5-year RFS rates of 79.6%, 65.2%, 52.5% (logrank P=0.025), and remained as an independent predictor after adjusting for clinicopathological factors (hazard ratio=2.79, P=0.016). The prognostic value of imaging subtypes was further validated in five independent gene expression cohorts, with average 5-year RFS rates of 88.1%, 74.0%, 59.5% (logrank P from <0.0001 to 0.008). Each imaging subtype was associated with specific dysregulated molecular pathways that can be therapeutically targeted.Imaging subtypes provide complimentary value to established histopathological or molecular subtypes, and may help stratify breast cancer patients.

  View details for DOI 10.1158/1078-0432.CCR-16-2415

  View details for PubMedID 28073839

• Flexible and Stretchable Energy Storage: Recent Advances and Future Perspectives ADVANCED MATERIALS Liu, W., Song, M., Kong, B., Cui, Y. 2017; 29 (1)

  Abstract

  Energy-storage technologies such as lithium-ion batteries and supercapacitors have become fundamental building blocks in modern society. Recently, the emerging direction toward the ever-growing market of flexible and wearable electronics has nourished progress in building multifunctional energy-storage systems that can be bent, folded, crumpled, and stretched while maintaining their electrochemical functions under deformation. Here, recent progress and well-developed strategies in research designed to accomplish flexible and stretchable lithium-ion batteries and supercapacitors are reviewed. The challenges of developing novel materials and configurations with tailored features, and in designing simple and large-scaled manufacturing methods that can be widely utilized are considered. Furthermore, the perspectives and opportunities for this emerging field of materials science and engineering are also discussed.

  View details for DOI 10.1002/adma.201603436

  View details for Web of Science ID 000392729000010

  View details for PubMedID 28042889

• Sulfur-Modulated Tin Sites Enable Highly Selective Electrochemical Reduction of CO2 to Formate Joule Zheng, X., De luna, P., de Arquer, F., Zhang, B., Becknell, N., Cui, Y., Du, X., Yang, P., Sargent, E. 2017

  View details for DOI 10.1016/j.joule.2017.09.014

• Direct Blow-Spinning of Nanofibers on a Window Screen for Highly Efficient PM2.5 Removal. Nano letters Khalid, B. n., Bai, X. n., Wei, H. n., Huang, Y. n., Wu, H. n., Cui, Y. n. 2017; 17 (2): 1140–48

  Abstract

  Particulate matter (PM) pollution has caused many serious public health issues. Whereas indoor air protection usually relies on expensive and energy-consuming filtering devices, direct PM filtration by window screens has attracted increasing attention. Recently, electrospun polymer nanofiber networks have been developed as transparent filters for highly efficient PM2.5 removal; however, it remains challenging to uniformly coat the nanofibers on window screens on a large scale and with low cost. Here, we report a blow-spinning technique that is fast, efficient, and free of high voltages for the large-scale direct coating of nanofibers onto window screens for indoor PM pollution protection. We have achieved a transparent air filter of 80% optical transparency with >99% standard removal efficiency level for PM2.5. A test on a real window (1 m × 2 m) in Beijing has proven that the nanofiber transparent air filter acquires excellent PM2.5 removal efficiency of 90.6% over 12 h under extremely hazy air conditions (PM2.5 mass concentration > 708 μg/m3). Moreover, we show that the nanofibers can be readily coated on the window screen for pollution protection and can be easily removed by wiping the screen after hazardous days.

  View details for PubMedID 28027642

• Continuous Draw Spinning of Extra-Long Silver Submicron Fibers with Micrometer Patterning Capability. Nano letters Bai, X. n., Liao, S. n., Huang, Y. n., Song, J. n., Liu, Z. n., Fang, M. n., Xu, C. n., Cui, Y. n., Wu, H. n. 2017; 17 (3): 1883–91

  Abstract

  Ultrathin metal fibers can serve as highly conducting and flexible current and heat transport channels, which are essential for numerous applications ranging from flexible electronics to energy conversion. Although industrial production of metal fibers with diameters of down to 2 μm is feasible, continuous production of high-quality and low-cost nanoscale metal wires is still challenging. Herein, we report the continuous draw spinning of highly conductive silver submicron fibers with the minimum diameter of ∼200 nm and length of more than kilometers. We obtained individual AgNO3/polymer fibers by continuous drawing from an aqueous solution at a speed of up to 8 m/s. With subsequent heat treatment, freestanding Ag submicron fibers with high mechanical flexibility and electric conductivity have been obtained. Woven mats of aligned Ag submicron fibers were used as transparent electrodes with high flexibility and high performance with sheet resistance of 7 Ω sq-1 at a transparency of 96%. Continuous draw spinning opened new avenues for scalable, flexible, and ultralow-cost fabrication of extra-long conductive ultrathin metal fibers.

  View details for PubMedID 28165744

• Revealing Nanoscale Passivation and Corrosion Mechanisms of Reactive Battery Materials in Gas Environments. Nano letters Li, Y. n., Li, Y. n., Sun, Y. n., Butz, B. n., Yan, K. n., Koh, A. L., Zhao, J. n., Pei, A. n., Cui, Y. n. 2017; 17 (8): 5171–78

  Abstract

  Lithium (Li) metal is a high-capacity anode material (3860 mAh g-1) that can enable high-energy batteries for electric vehicles and grid-storage applications. However, Li metal is highly reactive and repeatedly consumed when exposed to liquid electrolyte (during battery operation) or the ambient environment (throughout battery manufacturing). Studying these corrosion reactions on the nanoscale is especially difficult due to the high chemical reactivity of both Li metal and its surface corrosion films. Here, we directly generate pure Li metal inside an environmental transmission electron microscope (TEM), revealing the nanoscale passivation and corrosion process of Li metal in oxygen (O2), nitrogen (N2), and water vapor (H2O). We find that while dry O2 and N2 (99.9999 vol %) form uniform passivation layers on Li, trace water vapor (∼1 mol %) disrupts this passivation and forms a porous film on Li metal that allows gas to penetrate and continuously react with Li. To exploit the self-passivating behavior of Li in dry conditions, we introduce a simple dry-N2 pretreatment of Li metal to form a protective layer of Li nitride prior to battery assembly. The fast ionic conductivity and stable interface of Li nitride results in improved battery performance with dendrite-free cycling and low voltage hysteresis. Our work reveals the detailed process of Li metal passivation/corrosion and demonstrates how this mechanistic insight can guide engineering solutions for Li metal batteries.

  View details for PubMedID 28692280

• Surface Fluorination of Reactive Battery Anode Materials for Enhanced Stability. Journal of the American Chemical Society Zhao, J. n., Liao, L. n., Shi, F. n., Lei, T. n., Chen, G. n., Pei, A. n., Sun, J. n., Yan, K. n., Zhou, G. n., Xie, J. n., Liu, C. n., Li, Y. n., Liang, Z. n., Bao, Z. n., Cui, Y. n. 2017; 139 (33): 11550–58

  Abstract

  Significant increases in the energy density of batteries must be achieved by exploring new materials and cell configurations. Lithium metal and lithiated silicon are two promising high-capacity anode materials. Unfortunately, both of these anodes require a reliable passivating layer to survive the serious environmental corrosion during handling and cycling. Here we developed a surface fluorination process to form a homogeneous and dense LiF coating on reactive anode materials, with in situ generated fluorine gas, by using a fluoropolymer, CYTOP, as the precursor. The process is effectively a "reaction in the beaker", avoiding direct handling of highly toxic fluorine gas. For lithium metal, this LiF coating serves as a chemically stable and mechanically strong interphase, which minimizes the corrosion reaction with carbonate electrolytes and suppresses dendrite formation, enabling dendrite-free and stable cycling over 300 cycles with current densities up to 5 mA/cm2. Lithiated silicon can serve as either a pre-lithiation additive for existing lithium-ion batteries or a replacement for lithium metal in Li-O2 and Li-S batteries. However, lithiated silicon reacts vigorously with the standard slurry solvent N-methyl-2-pyrrolidinone (NMP), indicating it is not compatible with the real battery fabrication process. With the protection of crystalline and dense LiF coating, LixSi can be processed in anhydrous NMP with a high capacity of 2504 mAh/g. With low solubility of LiF in water, this protection layer also allows LixSi to be stable in humid air (∼40% relative humidity). Therefore, this facile surface fluorination process brings huge benefit to both the existing lithium-ion batteries and next-generation lithium metal batteries.

  View details for PubMedID 28743184

• Ultrahigh-current density anodes with interconnected Li metal reservoir through overlithiation of mesoporous AlF3 framework. Science advances Wang, H. n., Lin, D. n., Liu, Y. n., Li, Y. n., Cui, Y. n. 2017; 3 (9): e1701301

  Abstract

  Lithium (Li) metal is the ultimate solution for next-generation high-energy density batteries but is plagued from commercialization by infinite relative volume change, low Coulombic efficiency due to side reactions, and safety issues caused by dendrite growth. These hazardous issues are further aggravated under high current densities needed by the increasing demand for fast charging/discharging. We report a one-step fabricated Li/Al4Li9-LiF nanocomposite (LAFN) through an "overlithiation" process of a mesoporous AlF3 framework, which can simultaneously mitigate the abovementioned problems. Reaction-produced Al4Li9-LiF nanoparticles serve as the ideal skeleton for Li metal infusion, helping to achieve a near-zero volume change during stripping/plating and suppressed dendrite growth. As a result, the LAFN electrode is capable of working properly under an ultrahigh current density of 20 mA cm-2 in symmetric cells and manifests highly improved rate capability with increased Coulombic efficiency in full cells. The simple fabrication process and its remarkable electrochemical performances enable LAFN to be a promising anode candidate for next-generation lithium metal batteries.

  View details for PubMedID 28913431

• The path towards sustainable energy NATURE MATERIALS Chu, S., Cui, Y., Liu, N. 2017; 16 (1): 16-22

  Abstract

  Civilization continues to be transformed by our ability to harness energy beyond human and animal power. A series of industrial and agricultural revolutions have allowed an increasing fraction of the world population to heat and light their homes, fertilize and irrigate their crops, connect to one another and travel around the world. All of this progress is fuelled by our ability to find, extract and use energy with ever increasing dexterity. Research in materials science is contributing to progress towards a sustainable future based on clean energy generation, transmission and distribution, the storage of electrical and chemical energy, energy efficiency, and better energy management systems.

  View details for DOI 10.1038/nmat4834

  View details for Web of Science ID 000391343300010

• Shape-Controlled TiO2 Nanocrystals for Na-Ion Battery Electrodes: The Role of Different Exposed Crystal Facets on the Electrochemical Properties. Nano letters Longoni, G. n., Pena Cabrera, R. L., Polizzi, S. n., D'Arienzo, M. n., Mari, C. M., Cui, Y. n., Ruffo, R. n. 2017; 17 (2): 992–1000

  Abstract

  Rechargeable sodium-ion batteries are becoming a viable alternative to lithium-based technology in energy storage strategies, due to the wide abundance of sodium raw material. In the past decade, this has generated a boom of research interest in such systems. Notwithstanding the large number of research papers concerning sodium-ion battery electrodes, the development of a low-cost, well-performing anode material remains the largest obstacle to overcome. Although the well-known anatase, one of the allotropic forms of natural TiO2, was recently proposed for such applications, the material generally suffers from reduced cyclability and limited power, due to kinetic drawbacks and to its poor charge transport properties. A systematic approach in the morphological tuning of the anatase nanocrystals is needed, to optimize its structural features toward the electrochemical properties and to promote the material interaction with the conductive network and the electrolyte. Aiming to face with these issues, we were able to obtain a fine tuning of the nanoparticle morphology and to expose the most favorable nanocrystal facets to the electrolyte and to the conductive wrapping agent (graphene), thus overcoming the intrinsic limits of anatase transport properties. The result is a TiO2-based composite electrode able to deliver an outstandingly stability over cycles (150 mA h g-1 for more than 600 cycles in the 1.5-0.1 V potential range) never achieved with such a low content of carbonaceous substrate (5%). Moreover, it has been demonstrated for the first time than these outstanding performances are not simply related to the overall surface area of the different morphologies but have to be directly related to the peculiar surface characteristics of the crystals.

  View details for PubMedID 28027440

• Phase Separation of Dirac Electrons in Topological Insulators at the Spatial Limit NANO LETTERS Parra, C., Rodrigues da Cunha, T. H., Contryrnan, A. W., Kong, D., Montero-Silva, F., Rezende Goncalves, P. H., dos Reis, D. D., Giraldo-Gallo, P., Segura, R., Olivares, F., Niestemski, F., Cui, Y., Magalhaes-Paniago, R., Manoharan, H. C. 2017; 17 (1): 97-103

  Abstract

  In this work we present unique signatures manifested by the local electronic properties of the topological surface state in Bi2Te3 nanostructures as the spatial limit is approached. We concentrate on the pure nanoscale limit (nanoplatelets) with spatial electronic resolution down to 1 nm. The highlights include strong dependencies on nanoplatelet size: (1) observation of a phase separation of Dirac electrons whose length scale decreases as the spatial limit is approached, and (2) the evolution from heavily n-type to lightly n-type surface doping as nanoplatelet thickness increases. Our results show a new approach to tune the Dirac point together with reduction of electronic disorder in topological insulator (TI) nanostructured systems. We expect our work will provide a new route for application of these nanostructured Dirac systems in electronic devices.

  View details for DOI 10.1021/acs.nanolett.6b03506

  View details for Web of Science ID 000392036600015

  View details for PubMedID 28026959

• Two-dimensional limit of crystalline order in perovskite membrane films. Science advances Hong, S. S., Yu, J. H., Lu, D. n., Marshall, A. F., Hikita, Y. n., Cui, Y. n., Hwang, H. Y. 2017; 3 (11): eaao5173

  Abstract

  Long-range order and phase transitions in two-dimensional (2D) systems-such as magnetism, superconductivity, and crystallinity-have been important research topics for decades. The issue of 2D crystalline order has reemerged recently, with the development of exfoliated atomic crystals. Understanding the dimensional limit of crystalline phases, with different types of bonding and synthetic techniques, is at the foundation of low-dimensional materials design. We study ultrathin membranes of SrTiO3, an archetypal perovskite oxide with isotropic (3D) bonding. Atomically controlled membranes are released after synthesis by dissolving an underlying epitaxial layer. Although all unreleased films are initially single-crystalline, the SrTiO3 membrane lattice collapses below a critical thickness (5 unit cells). This crossover from algebraic to exponential decay of the crystalline coherence length is analogous to the 2D topological Berezinskii-Kosterlitz-Thouless (BKT) transition. The transition is likely driven by chemical bond breaking at the 2D layer-3D bulk interface, defining an effective dimensional phase boundary for coherent crystalline lattices.

  View details for PubMedID 29167822

  View details for PubMedCentralID PMC5696264

• Development and Validation of an Individualized Immune Prognostic Signature in Early-Stage Nonsquamous Non-Small Cell Lung Cancer. JAMA oncology Li, B. n., Cui, Y. n., Diehn, M. n., Li, R. n. 2017

  Abstract

  The prevalence of early-stage non-small cell lung cancer (NSCLC) is expected to increase with recent implementation of annual screening programs. Reliable prognostic biomarkers are needed to identify patients at a high risk for recurrence to guide adjuvant therapy.To develop a robust, individualized immune signature that can estimate prognosis in patients with early-stage nonsquamous NSCLC.This retrospective study analyzed the gene expression profiles of frozen tumor tissue samples from 19 public NSCLC cohorts, including 18 microarray data sets and 1 RNA-Seq data set for The Cancer Genome Atlas (TCGA) lung adenocarcinoma cohort. Only patients with nonsquamous NSCLC with clinical annotation were included. Samples were from 2414 patients with nonsquamous NSCLC, divided into a meta-training cohort (729 patients), meta-testing cohort (716 patients), and 3 independent validation cohorts (439, 323, and 207 patients). All patients underwent surgery with a negative surgical margin, received no adjuvant or neoadjuvant therapy, and had publicly available gene expression data and survival information. Data were collected from July 22 through September 8, 2016.Overall survival.Of 2414 patients (1205 men [50%], 1111 women [46%], and 98 of unknown sex [4%]; median age [range], 64 [15-90] years), a prognostic immune signature of 25 gene pairs consisting of 40 unique genes was constructed using the meta-training data set. In the meta-testing and validation cohorts, the immune signature significantly stratified patients into high- vs low-risk groups in terms of overall survival across and within subpopulations with stage I, IA, IB, or II disease and remained as an independent prognostic factor in multivariate analyses (hazard ratio range, 1.72 [95% CI, 1.26-2.33; P < .001] to 2.36 [95% CI, 1.47-3.79; P < .001]) after adjusting for clinical and pathologic factors. Several biological processes, including chemotaxis, were enriched among genes in the immune signature. The percentage of neutrophil infiltration (5.6% vs 1.8%) and necrosis (4.6% vs 1.5%) was significantly higher in the high-risk immune group compared with the low-risk groups in TCGA data set (P < .003). The immune signature achieved a higher accuracy (mean concordance index [C-index], 0.64) than 2 commercialized multigene signatures (mean C-index, 0.53 and 0.61) for estimation of survival in comparable validation cohorts. When integrated with clinical characteristics such as age and stage, the composite clinical and immune signature showed improved prognostic accuracy in all validation data sets relative to molecular signatures alone (mean C-index, 0.70 vs 0.63) and another commercialized clinical-molecular signature (mean C-index, 0.68 vs 0.65).The proposed clinical-immune signature is a promising biomarker for estimating overall survival in nonsquamous NSCLC, including early-stage disease. Prospective studies are needed to test the clinical utility of the biomarker in individualized management of nonsquamous NSCLC.

  View details for PubMedID 28687838

• Electrospun core-shell microfiber separator with thermal-triggered flame-retardant properties for lithium-ion batteries. Science advances Liu, K., Liu, W., Qiu, Y., Kong, B., Sun, Y., Chen, Z., Zhuo, D., Lin, D., Cui, Y. 2017; 3 (1)

  Abstract

  Although the energy densities of batteries continue to increase, safety problems (for example, fires and explosions) associated with the use of highly flammable liquid organic electrolytes remain a big issue, significantly hindering further practical applications of the next generation of high-energy batteries. We have fabricated a novel "smart" nonwoven electrospun separator with thermal-triggered flame-retardant properties for lithium-ion batteries. The encapsulation of a flame retardant inside a protective polymer shell has prevented direct dissolution of the retardant agent into the electrolyte, which would otherwise have negative effects on battery performance. During thermal runaway of the lithium-ion battery, the protective polymer shell would melt, triggered by the increased temperature, and the flame retardant would be released, thus effectively suppressing the combustion of the highly flammable electrolytes.

  View details for DOI 10.1126/sciadv.1601978

  View details for PubMedID 28097221

  View details for PubMedCentralID PMC5235334

• The path towards sustainable energy. Nature materials Chu, S., Cui, Y., Liu, N. 2016; 16 (1): 16-22

  Abstract

  Civilization continues to be transformed by our ability to harness energy beyond human and animal power. A series of industrial and agricultural revolutions have allowed an increasing fraction of the world population to heat and light their homes, fertilize and irrigate their crops, connect to one another and travel around the world. All of this progress is fuelled by our ability to find, extract and use energy with ever increasing dexterity. Research in materials science is contributing to progress towards a sustainable future based on clean energy generation, transmission and distribution, the storage of electrical and chemical energy, energy efficiency, and better energy management systems.

  View details for DOI 10.1038/nmat4834

  View details for PubMedID 27994253

• High-Efficiency Silicon/Organic Heterojunction Solar Cells with Improved Junction Quality and Interface Passivation ACS NANO He, J., Gao, P., Ling, Z., Ding, L., Yang, Z., Ye, J., Cui, Y. 2016; 10 (12): 11525-11531

  Abstract

  Silicon/organic heterojunction solar cells (HSCs) based on conjugated polymers, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), and n-type silicon (n-Si) have attracted wide attention due to their potential advantages of high efficiency and low cost. However, the state-of-the-art efficiencies are still far from satisfactory due to the inferior junction quality. Here, facile treatments were applied by pretreating the n-Si wafer in tetramethylammonium hydroxide (TMAH) solution and using a capping copper iodide (CuI) layer on the PEDOT:PSS layer to achieve a high-quality Schottky junction. Detailed photoelectric characteristics indicated that the surface recombination was greatly suppressed after TMAH pretreatment, which increased the thickness of the interfacial oxide layer. Furthermore, the CuI capping layer induced a strong inversion layer near the n-Si surface, resulting in an excellent field effect passivation. With the collaborative improvements in the interface chemical and electrical passivation, a competitive open-circuit voltage of 0.656 V and a high fill factor of 78.1% were achieved, leading to a stable efficiency of over 14.3% for the planar n-Si/PEDOT:PSS HSCs. Our findings suggest promising strategies to further exploit the full voltage as well as efficiency potentials for Si/organic solar cells.

  View details for DOI 10.1021/acsnano.6b07511

  View details for Web of Science ID 000391079700101

  View details for PubMedID 27935280

• In Situ Electrochemically Derived Nanoporous Oxides from Transition Metal Dichalcogenides for Active Oxygen Evolution Catalysts NANO LETTERS Chen, W., Liu, Y., Li, Y., Sun, J., Qiu, Y., Liu, C., Zhou, G., Cui, Y. 2016; 16 (12): 7588-7596

  Abstract

  Transition metal dichalcogenides have been widely studied as active electrocatalysts for hydrogen evolution reactions. However, their properties as oxygen evolution reaction catalysts have not been fully explored. In this study, we systematically investigate a family of transition metal dichalcogenides (MX, M = Co, Ni, Fe; X = S, Se, Te) as candidates for water oxidation. It reveals that the transition metal dichalcogenides are easily oxidized in strong alkaline media via an in situ electrochemical oxidation process, producing nanoporous transition metal oxides toward much enhanced water oxidation activity due to their increased surface area and more exposed electroactive sites. The optimal cobalt nickel iron oxides that derived from their sulfides and selenides demonstrate a low overpotential of 232 mV at current density of 10 mA cm(-2), a small Tafel slope of 35 mV per decade, and negligible degradation of electrochemical activity over 200 h of electrolysis. This study represents the discovery of nanoporous transition metal oxides deriving from their chalcogenides as outstanding electrocatalysts for water oxidation.

  View details for DOI 10.1021/acs.nanolett.6b03458

  View details for PubMedID 27960466

• Improved Lithium Ionic Conductivity in Composite Polymer Electrolytes with Oxide-Ion Conducting Nanowires ACS NANO Liu, W., Lin, D., Sun, J., Zhou, G., Cui, Y. 2016; 10 (12): 11407-11413

  Abstract

  Solid Li-ion electrolytes used in all-solid-state lithium-ion batteries (LIBs) are being considered to replace conventional liquid electrolytes that have leakage, flammability, and poor chemical stability issues, which represents one major challenge and opportunity for next-generation high-energy-density batteries. However, the low mobility of lithium ions in solid electrolytes limits their practical applications. Here, we report a solid composite polymer electrolyte with Y2O3-doped ZrO2 (YSZ) nanowires that are enriched with positive-charged oxygen vacancies. The morphologies and ionic conductivities have been studied systemically according to concentration of Y2O3 dopant in the nanowires. In comparison to the conventional filler-free electrolyte with a conductivity of 3.62 × 10(-7) S cm(-1), the composite polymer electrolytes with the YSZ nanowires show much higher ionic conductivity. It indicates that incorporation of 7 mol % of Y2O3-doped ZrO2 nanowires results in the highest ionic conductivity of 1.07 × 10(-5) S cm(-1) at 30 °C. This conductivity enhancement originates from the positive-charged oxygen vacancies on the surfaces of the nanowires that could associate with anions and then release more Li ions. Our work demonstrates a composite polymer electrolyte with oxygen-ion conductive nanowires that could address the challenges of all-solid-state LIBs.

  View details for DOI 10.1021/acsnano.6b06797

  View details for PubMedID 28024352

• Stabilizing Lithium Metal Anodes by Uniform Li-Ion Flux Distribution in Nanochannel Confinement JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Liu, W., Lin, D., Pei, A., Cui, Y. 2016; 138 (47): 15443-15450

  Abstract

  The widespread implementation of high-energy-density lithium metal batteries has long been fettered by lithium dendrite-related failure. Here we report a new strategy to address the issue of dendrite growth by a polyimide-coating layer with vertical nanoscale channels of high aspect ratio. Smooth, granular lithium metal was deposited on the modified electrode instead of typical filamentary growths. In a comparison with the bare planar electrode, the modified electrode achieved greatly enhanced Coulombic efficiency and longer cycle life. Homogeneous Li(+) flux distribution above the modified electrode from the nanochannel confinement can account for a uniform Li nucleation and a nondendrite growth. We also demonstrated that the polyimide coating with microscale pores loses the confinement effects and fails to suppress lithium dendrites. This strategy of spatially defined lithium growth in vertical-aligned nanochannels provides a novel approach and a significant step toward stabilizing Li metal anodes.

  View details for DOI 10.1021/jacs.6b08730

  View details for Web of Science ID 000389160500022

  View details for PubMedID 27804300

• Direct and continuous strain control of catalysts with tunable battery electrode materials SCIENCE Wang, H., Xu, S., Tsai, C., Li, Y., Liu, C., Zhao, J., Liu, Y., Yuan, H., Abild-Pedersen, F., Prinz, F. B., Norskov, J. K., Cui, Y. 2016; 354 (6315): 1031-1036

  Abstract

  We report a method for using battery electrode materials to directly and continuously control the lattice strain of platinum (Pt) catalyst and thus tune its catalytic activity for the oxygen reduction reaction (ORR). Whereas the common approach of using metal overlayers introduces ligand effects in addition to strain, by electrochemically switching between the charging and discharging status of battery electrodes the change in volume can be precisely controlled to induce either compressive or tensile strain on supported catalysts. Lattice compression and tension induced by the lithium cobalt oxide substrate of ~5% were directly observed in individual Pt nanoparticles with aberration-corrected transmission electron microscopy. We observed 90% enhancement or 40% suppression in Pt ORR activity under compression or tension, respectively, which is consistent with theoretical predictions.

  View details for DOI 10.1126/science.aaf7680

  View details for PubMedID 27885028

• Entrapment of Polysulfides by a Black-Phosphorus-Modified Separator for Lithium-Sulfur Batteries ADVANCED MATERIALS Sun, J., Sun, Y., Pasta, M., Zhou, G., Li, Y., Liu, W., Xiong, F., Cui, Y. 2016; 28 (44): 9797-?

  Abstract

  A bifunctional separator modified by black-phosphorus nanoflakes is prepared to overcome the challenges associated with the polysulfide diffusion in lithium-sulfur batteries. It brings the benefits of the entrapment of various sulfur species via the strong binding energy and re-activation of the trapped sulfur species due to its high electron conductivity as well as Li-ion diffusivity.

  View details for DOI 10.1002/adma.201602172

  View details for Web of Science ID 000392721400016

  View details for PubMedID 27634105

• Development of an Activated Carbon-Based Electrode for the Capture and Rapid Electrolytic Reductive Debromination of Methyl Bromide from Postharvest Fumigations. Environmental science & technology Li, Y., Liu, C., Cui, Y., Walse, S. S., Olver, R., Zilberman, D., Mitch, W. A. 2016; 50 (20): 11200-11208

  Abstract

  Due to concerns surrounding its ozone depletion potential, there is a need for technologies to capture and destroy methyl bromide (CH3Br) emissions from postharvest fumigations applied to control agricultural pests. Previously, we described a system in which CH3Br fumes vented from fumigation chambers could be captured by granular activated carbon (GAC). The GAC was converted to a cathode by submergence in a high ionic strength solution and connection to the electrical grid, resulting in reductive debromination of the sorbed CH3Br. The GAC bed was drained and dried for reuse to capture and destroy CH3Br fumes from the next fumigation. However, the loose GAC particles and slow kinetics of this primitive electrode necessitated improvements. Here, we report the development of a cathode containing a thin layer of small GAC particles coating carbon cloth as a current distributor. Combining the high sorption potential of GAC for CH3Br with the conductivity of the carbon cloth current distributor, the cathode significantly lowered the total cell resistance and achieved 96% reductive debromination of CH3Br sorbed at 30% by weight to the GAC within 15 h at -1 V applied potential vs standard hydrogen electrode, a time scale and efficiency suitable for postharvest fumigations. The cathode exhibited stable performance over 50 CH3Br capture and destruction cycles. Initial cost estimates indicate that this technique could treat CH3Br fumes at ∼$5/kg, roughly one-third of the cost of current alternatives.

  View details for PubMedID 27611209

• Subzero-Temperature Cathode for a Sodium-Ion Battery ADVANCED MATERIALS You, Y., Yao, H., Xin, S., Yin, Y., Zuo, T., Yang, C., Guo, Y., Cui, Y., Wan, L., Goodenough, J. B. 2016; 28 (33): 7243-?

  Abstract

  A subzero-temperature cathode material is obtained by nucleating cubic prussian blue crystals at inhomogeneities in carbon nanotubes. Due to fast ionic/electronic transport kinetics even at -25 °C, the cathode shows an outstanding low-temperature performance in terms of specific energy, high-rate capability, and cycle life, providing a practical sodium-ion battery powering an electric vehicle in frigid regions.

  View details for DOI 10.1002/adma.201600846

  View details for PubMedID 27305570

• Radiative human body cooling by nanoporous polyethylene textile SCIENCE Hsu, P., Song, A. Y., Catrysse, P. B., Liu, C., Peng, Y., Xie, J., Fan, S., Cui, Y. 2016; 353 (6303): 1019-1023

  Abstract

  Thermal management through personal heating and cooling is a strategy by which to expand indoor temperature setpoint range for large energy saving. We show that nanoporous polyethylene (nanoPE) is transparent to mid-infrared human body radiation but opaque to visible light because of the pore size distribution (50 to 1000 nanometers). We processed the material to develop a textile that promotes effective radiative cooling while still having sufficient air permeability, water-wicking rate, and mechanical strength for wearability. We developed a device to simulate skin temperature that shows temperatures 2.7° and 2.0°C lower when covered with nanoPE cloth and with processed nanoPE cloth, respectively, than when covered with cotton. Our processed nanoPE is an effective and scalable textile for personal thermal management.

  View details for DOI 10.1126/science.aaf5471

  View details for PubMedID 27701110

• All-Integrated Bifunctional Separator for Li Dendrite Detection via Novel Solution Synthesis of a Thermostable Polyimide Separator. Journal of the American Chemical Society Lin, D., Zhuo, D., Liu, Y., Cui, Y. 2016; 138 (34): 11044-11050

  Abstract

  Safe operation is crucial for lithium (Li) batteries, and therefore, developing separators with dendrite-detection function is of great scientific and technological interest. However, challenges have been encountered when integrating the function into commercial polyolefin separators. Among all polymer candidates, polyimides (PIs) are prominent due to their good thermal/mechanical stability and electrolyte wettability. Nevertheless, it is still a challenge to efficiently synthesize PI separators, let alone integrate additional functions. In this work, a novel yet facile solution synthesis was developed to fabricate a nanoporous PI separator. Specifically, recyclable LiBr was utilized as the template for nanopores creation while the polymer was processed at the intermediate stage. This method proves not only to be a facile synthesis with basic lab facility but also to have promising potential for low-cost industrial production. The as-synthesized PI separator exhibited excellent thermal/mechanical stability and electrolyte wettability, the latter of which further improves the ionic conductivity and thus battery rate capability. Notably, stable full-cell cycling for over 200 cycles with a PI separator was further achieved. Based on this method, the fabrication of an all-integrated PI/Cu/PI bifunctional separator for dendrite detection can be fulfilled. The as-fabricated all-integrated separators prove efficient as early alarms of Li penetration, opening up the opportunity for safer battery design by separator engineering.

  View details for DOI 10.1021/jacs.6b06324

  View details for PubMedID 27498838

• Rapid water disinfection using vertically aligned MoS2 nanofilms and visible light. Nature nanotechnology Liu, C., Kong, D., Hsu, P., Yuan, H., Lee, H., Liu, Y., Wang, H., Wang, S., Yan, K., Lin, D., Maraccini, P. A., Parker, K. M., Boehm, A. B., Cui, Y. 2016

  Abstract

  Solar energy is readily available in most climates and can be used for water purification. However, solar disinfection of drinking water mostly relies on ultraviolet light, which represents only 4% of the total solar energy, and this leads to a slow treatment speed. Therefore, the development of new materials that can harvest visible light for water disinfection, and so speed up solar water purification, is highly desirable. Here we show that few-layered vertically aligned MoS2 (FLV-MoS2) films can be used to harvest the whole spectrum of visible light (∼50% of solar energy) and achieve highly efficient water disinfection. The bandgap of MoS2 was increased from 1.3 to 1.55 eV by decreasing the domain size, which allowed the FLV-MoS2 to generate reactive oxygen species (ROS) for bacterial inactivation in the water. The FLV-MoS2 showed a ∼15 times better log inactivation efficiency of the indicator bacteria compared with that of bulk MoS2, and a much faster inactivation of bacteria under both visible light and sunlight illumination compared with the widely used TiO2. Moreover, by using a 5 nm copper film on top of the FLV-MoS2 as a catalyst to facilitate electron-hole pair separation and promote the generation of ROS, the disinfection rate was increased a further sixfold. With our approach, we achieved water disinfection of >99.999% inactivation of bacteria in 20 min with a small amount of material (1.6 mg l(-1)) under simulated visible light.

  View details for DOI 10.1038/nnano.2016.138

  View details for PubMedID 27525474

• Evolution of the Valley Position in Bulk Transition-Metal Chalcogenides and Their Monolayer Limit. Nano letters Yuan, H., Liu, Z., Xu, G., Zhou, B., Wu, S., Dumcenco, D., Yan, K., Zhang, Y., Mo, S., Dudin, P., Kandyba, V., Yablonskikh, M., Barinov, A., Shen, Z., Zhang, S., Huang, Y., Xu, X., Hussain, Z., Hwang, H. Y., Cui, Y., Chen, Y. 2016; 16 (8): 4738-4745

  Abstract

  Layered transition metal chalcogenides with large spin orbit coupling have recently sparked much interest due to their potential applications for electronic, optoelectronic, spintronics, and valleytronics. However, most current understanding of the electronic structure near band valleys in momentum space is based on either theoretical investigations or optical measurements, leaving the detailed band structure elusive. For example, the exact position of the conduction band valley of bulk MoS2 remains controversial. Here, using angle-resolved photoemission spectroscopy with submicron spatial resolution (micro-ARPES), we systematically imaged the conduction/valence band structure evolution across representative chalcogenides MoS2, WS2, and WSe2, as well as the thickness dependent electronic structure from bulk to the monolayer limit. These results establish a solid basis to understand the underlying valley physics of these materials, and also provide a link between chalcogenide electronic band structure and their physical properties for potential valleytronics applications.

  View details for DOI 10.1021/acs.nanolett.5b05107

  View details for PubMedID 27357620

• Metallurgically lithiated SiOx anode with high capacity and ambient air compatibility PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Zhao, J., Lee, H., Sun, J., Yan, K., Liu, Y., Liu, W., Lu, Z., Lin, D., Zhou, G., Cui, Y. 2016; 113 (27): 7408-7413

  Abstract

  A common issue plaguing battery anodes is the large consumption of lithium in the initial cycle as a result of the formation of a solid electrolyte interphase followed by gradual loss in subsequent cycles. It presents a need for prelithiation to compensate for the loss. However, anode prelithiation faces the challenge of high chemical reactivity because of the low anode potential. Previous efforts have produced prelithiated Si nanoparticles with dry air stability, which cannot be stabilized under ambient air. Here, we developed a one-pot metallurgical process to synthesize LixSi/Li2O composites by using low-cost SiO or SiO2 as the starting material. The resulting composites consist of homogeneously dispersed LixSi nanodomains embedded in a highly crystalline Li2O matrix, providing the composite excellent stability even in ambient air with 40% relative humidity. The composites are readily mixed with various anode materials to achieve high first cycle Coulombic efficiency (CE) of >100% or serve as an excellent anode material by itself with stable cyclability and consistently high CEs (99.81% at the seventh cycle and ∼99.87% for subsequent cycles). Therefore, LixSi/Li2O composites achieved balanced reactivity and stability, promising a significant boost to lithium ion batteries.

  View details for DOI 10.1073/pnas.1603810113

  View details for PubMedID 27313206

• Layered reduced graphene oxide with nanoscale interlayer gaps as a stable host for lithium metal anodes NATURE NANOTECHNOLOGY Lin, D., Liu, Y., Liang, Z., Lee, H., Sun, J., Wang, H., Yan, K., Xie, J., Cui, Y. 2016; 11 (7): 626-?

  Abstract

  Metallic lithium is a promising anode candidate for future high-energy-density lithium batteries. It is a light-weight material, and has the highest theoretical capacity (3,860 mAh g(-1)) and the lowest electrochemical potential of all candidates. There are, however, at least three major hurdles before lithium metal anodes can become a viable technology: uneven and dendritic lithium deposition, unstable solid electrolyte interphase and almost infinite relative dimension change during cycling. Previous research has tackled the first two issues, but the last is still mostly unsolved. Here we report a composite lithium metal anode that exhibits low dimension variation (∼20%) during cycling and good mechanical flexibility. The anode is composed of 7 wt% 'lithiophilic' layered reduced graphene oxide with nanoscale gaps that can host metallic lithium. The anode retains up to ∼3,390 mAh g(-1) of capacity, exhibits low overpotential (∼80 mV at 3 mA cm(-2)) and a flat voltage profile in a carbonate electrolyte. A full-cell battery with a LiCoO2 cathode shows good rate capability and flat voltage profiles.

  View details for DOI 10.1038/NNANO.2016.32

  View details for PubMedID 26999479

• Lithium Sulfi de/Metal Nanocomposite as a High-Capacity Cathode Prelithiation Material ADVANCED ENERGY MATERIALS Sun, Y., Lee, H., Seh, Z. W., Zheng, G., Sun, J., Li, Y., Cui, Y. 2016; 6 (12)

  View details for DOI 10.1002/aenm.201600154

  View details for Web of Science ID 000379313400012

• Avoiding short circuits from zinc metal dendrites in anode by backside-plating configuration NATURE COMMUNICATIONS Higashi, S., Lee, S., Lee, J., Takechi, K., Cui, Y. 2016; 7: 11801

  Abstract

  Portable power sources and grid-scale storage both require batteries combining high energy density and low cost. Zinc metal battery systems are attractive due to the low cost of zinc and its high charge-storage capacity. However, under repeated plating and stripping, zinc metal anodes undergo a well-known problem, zinc dendrite formation, causing internal shorting. Here we show a backside-plating configuration that enables long-term cycling of zinc metal batteries without shorting. We demonstrate 800 stable cycles of nickel-zinc batteries with good power rate (20 mA cm(-2), 20 C rate for our anodes). Such a backside-plating method can be applied to not only zinc metal systems but also other metal-based electrodes suffering from internal short circuits.

  View details for PubMedID 27263471

• Efficient solar-driven water splitting by nanocone BiVO4-perovskite tandem cells. Science advances Qiu, Y., Liu, W., Chen, W., Chen, W., Zhou, G., Hsu, P., Zhang, R., Liang, Z., Fan, S., Zhang, Y., Cui, Y. 2016; 2 (6)

  Abstract

  Bismuth vanadate (BiVO4) has been widely regarded as a promising photoanode material for photoelectrochemical (PEC) water splitting because of its low cost, its high stability against photocorrosion, and its relatively narrow band gap of 2.4 eV. However, the achieved performance of the BiVO4 photoanode remains unsatisfactory to date because its short carrier diffusion length restricts the total thickness of the BiVO4 film required for sufficient light absorption. We addressed the issue by deposition of nanoporous Mo-doped BiVO4 (Mo:BiVO4) on an engineered cone-shaped nanostructure, in which the Mo:BiVO4 layer with a larger effective thickness maintains highly efficient charge separation and high light absorption capability, which can be further enhanced by multiple light scattering in the nanocone structure. As a result, the nanocone/Mo:BiVO4/Fe(Ni)OOH photoanode exhibits a high water-splitting photocurrent of 5.82 ± 0.36 mA cm(-2) at 1.23 V versus the reversible hydrogen electrode under 1-sun illumination. We also demonstrate that the PEC cell in tandem with a single perovskite solar cell exhibits unassisted water splitting with a solar-to-hydrogen conversion efficiency of up to 6.2%.

  View details for DOI 10.1126/sciadv.1501764

  View details for PubMedID 27386565

• Porous MoO2 Nanosheets as Non-noble Bifunctional Electrocatalysts for Overall Water Splitting ADVANCED MATERIALS Jin, Y., Wang, H., Li, J., Yue, X., Han, Y., Shen, P. K., Cui, Y. 2016; 28 (19): 3785-3790

  Abstract

  A porous MoO2 nanosheet as an active and stable bifunctional electrocatalyst for overall water splitting, is presented. It needs a cell voltage of only about 1.53 V to achieve a current density of 10 mA cm(-2) and maintains its activity for at least 24 h in a two-electrode configuration.

  View details for DOI 10.1002/adma.201506314

  View details for PubMedID 26996884

• 3D Porous Sponge-Inspired Electrode for Stretchable Lithium-Ion Batteries ADVANCED MATERIALS Liu, W., Chen, Z., Zhou, G., Sun, Y., Lee, H. R., Liu, C., Yao, H., Bao, Z., Cui, Y. 2016; 28 (18): 3578-?

  Abstract

  A stretchable Li4 Ti5 O12 anode and a LiFePO4 cathode with 80% stretchability are prepared using a 3D interconnected porous polydimethylsiloxane sponge based on sugar cubes. 82% and 91% capacity retention for anode and cathode are achieved after 500 stretch-release cycles. Slight capacity decay of 6% in the battery using the electrode in stretched state is observed.

  View details for DOI 10.1002/adma.201505299

  View details for PubMedID 26992146

• Schottky Barrier Catalysis Mechanism in Metal-Assisted Chemical Etching of Silicon. ACS applied materials & interfaces Lai, R. A., Hymel, T. M., Narasimhan, V. K., Cui, Y. 2016; 8 (14): 8875-8879

  Abstract

  Metal-assisted chemical etching (MACE) is a versatile anisotropic etch for silicon although its mechanism is not well understood. Here we propose that the Schottky junction formed between metal and silicon plays an essential role on the distribution of holes in silicon injected from hydrogen peroxide. The proposed mechanism can be used to explain the dependence of the etching kinetics on the doping level, doping type, crystallographic surface direction, and etchant solution composition. We used the doping dependence of the reaction to fabricate a novel etch stop for the reaction.

  View details for DOI 10.1021/acsami.6b01020

  View details for PubMedID 27018712

• Balancing surface adsorption and diffusion of lithium-polysulfides on nonconductive oxides for lithium-sulfur battery design NATURE COMMUNICATIONS Tao, X., Wang, J., Liu, C., Wang, H., Yao, H., Zheng, G., Seh, Z. W., Cai, Q., Li, W., Zhou, G., Zu, C., Cui, Y. 2016; 7

  Abstract

  Lithium-sulfur batteries have attracted attention due to their six-fold specific energy compared with conventional lithium-ion batteries. Dissolution of lithium polysulfides, volume expansion of sulfur and uncontrollable deposition of lithium sulfide are three of the main challenges for this technology. State-of-the-art sulfur cathodes based on metal-oxide nanostructures can suppress the shuttle-effect and enable controlled lithium sulfide deposition. However, a clear mechanistic understanding and corresponding selection criteria for the oxides are still lacking. Herein, various nonconductive metal-oxide nanoparticle-decorated carbon flakes are synthesized via a facile biotemplating method. The cathodes based on magnesium oxide, cerium oxide and lanthanum oxide show enhanced cycling performance. Adsorption experiments and theoretical calculations reveal that polysulfide capture by the oxides is via monolayered chemisorption. Moreover, we show that better surface diffusion leads to higher deposition efficiency of sulfide species on electrodes. Hence, oxide selection is proposed to balance optimization between sulfide-adsorption and diffusion on the oxides.

  View details for DOI 10.1038/ncomms11203

  View details for PubMedID 27046216

• A Stretchable Graphitic Carbon/Si Anode Enabled by Conformal Coating of a Self-Healing Elastic Polymer ADVANCED MATERIALS Sun, Y., Lopez, J., Lee, H., Liu, N., Zheng, G., Wu, C., Sun, J., Liu, W., Chung, J. W., Bao, Z., Cui, Y. 2016; 28 (12): 2455-2461

  Abstract

  A high-capacity stretchable graphitic carbon/Si foam electrode is enabled by a conformal self-healing elastic polymer coating. The composite electrode exhibits high stretchability (up to 88%) and endures 1000 stretching-releasing cycles at 25% strain with detrimental resistance increase. Meanwhile, the electrode delivers a high reversible specific capacity of 719 mA g(-1) and good cycling stability with 81% capacity retention after 100 cycles.

  View details for DOI 10.1002/adma.201504723

  View details for Web of Science ID 000372459600022

• Composite lithium metal anode by melt infusion of lithium into a 3D conducting scaffold with lithiophilic coating. Proceedings of the National Academy of Sciences of the United States of America Liang, Z., Lin, D., Zhao, J., Lu, Z., Liu, Y., Liu, C., Lu, Y., Wang, H., Yan, K., Tao, X., Cui, Y. 2016; 113 (11): 2862-7

  Abstract

  Lithium metal-based battery is considered one of the best energy storage systems due to its high theoretical capacity and lowest anode potential of all. However, dendritic growth and virtually relative infinity volume change during long-term cycling often lead to severe safety hazards and catastrophic failure. Here, a stable lithium-scaffold composite electrode is developed by lithium melt infusion into a 3D porous carbon matrix with "lithiophilic" coating. Lithium is uniformly entrapped on the matrix surface and in the 3D structure. The resulting composite electrode possesses a high conductive surface area and excellent structural stability upon galvanostatic cycling. We showed stable cycling of this composite electrode with small Li plating/stripping overpotential (<90 mV) at a high current density of 3 mA/cm(2) over 80 cycles.

  View details for DOI 10.1073/pnas.1518188113

  View details for PubMedID 26929378

  View details for PubMedCentralID PMC4801240

• A Stretchable Graphitic Carbon/Si Anode Enabled by Conformal Coating of a Self-Healing Elastic Polymer. Advanced materials Sun, Y., Lopez, J., Lee, H., Liu, N., Zheng, G., Wu, C., Sun, J., Liu, W., Chung, J. W., Bao, Z., Cui, Y. 2016; 28 (12): 2455-2461

  Abstract

  A high-capacity stretchable graphitic carbon/Si foam electrode is enabled by a conformal self-healing elastic polymer coating. The composite electrode exhibits high stretchability (up to 88%) and endures 1000 stretching-releasing cycles at 25% strain with detrimental resistance increase. Meanwhile, the electrode delivers a high reversible specific capacity of 719 mA g(-1) and good cycling stability with 81% capacity retention after 100 cycles.

  View details for DOI 10.1002/adma.201504723

  View details for PubMedID 26813780

• Roll-to-Roll Transfer of Electrospun Nanofiber Film for High-Efficiency Transparent Air Filter NANO LETTERS Xu, J., Liu, C., Hsu, P., Liu, K., Zhang, R., Liu, Y., Cui, Y. 2016; 16 (2): 1270-1275

  Abstract

  Particulate matter (PM) pollution in air has become a serious environmental issue calling for new type of filter technologies. Recently, we have demonstrated a highly efficient air filter by direct electrospinning of polymer fibers onto supporting mesh although its throughput is limited. Here, we demonstrate a high throughput method based on fast transfer of electrospun nanofiber film from roughed metal foil to a receiving mesh substrate. Compared with the direct electrospinning method, the transfer method is 10 times faster and has better filtration performance at the same transmittance, owing to the uniformity of transferred nanofiber film (>99.97% removal of PM2.5 at ∼73% of transmittance). With these advantages, large area freestanding nanofiber film and roll-to-roll production of air filter are demonstrated.

  View details for DOI 10.1021/acs.nanolett.5b04596

  View details for PubMedID 26789781

• In Situ Chemical Synthesis of Lithium Fluoride/Metal Nanocomposite for High Capacity Prelithiation of Cathodes NANO LETTERS Sun, Y., Lee, H., Zheng, G., Seh, Z. W., Sun, J., Li, Y., Cui, Y. 2016; 16 (2): 1497-1501

  Abstract

  The initial lithium loss during the formation stage is a critical issue that significantly reduces the specific capacity and energy density of current rechargeable lithium-ion batteries (LIBs). An effective strategy to solve this problem is using electrode prelithiation additives that can work as a secondary lithium source and compensate the initial lithium loss. Herein we show that nanocomposites of lithium fluoride and metal (e.g., LiF/Co and LiF/Fe) can be efficient cathode prelithiation materials. The thorough mixing of ultrafine lithium fluoride and metal particles (∼5 nm) allows lithium to be easily extracted from the nanocomposites via an inverse conversion reaction. The LiF/Co nanocomposite exhibits an open circuit voltage (OCV, 1.5 V) with good compatibility with that of existing cathode materials and delivers a high first-cycle "donor" lithium-ion capacity (516 mA h g(-1)). When used as an additive to a LiFePO4 cathode, the LiF/Co nanocomposite provides high lithium compensation efficiency. Importantly, the as-formed LiF/metal nanocomposites possess high stability and good compatibility with the regular solvent, binder, and existing battery processing conditions, in contrast with the anode prelithiation materials that usually suffer from issues of high chemical reactivity and instability. The facile synthesis route, high stability in ambient and battery processing conditions, and high "donor" lithium-ion capacity make the LiF/metal nanocomposites ideal cathode prelithiation materials for LIBs.

  View details for DOI 10.1021/acs.nanolett.5b05228

  View details for PubMedID 26784146

• Interwall Friction and Sliding Behavior of Centimeters Long Double-Walled Carbon Nanotubes NANO LETTERS Zhang, R., Ning, Z., Xu, Z., Zhang, Y., Xie, H., Ding, F., Chen, Q., Zhang, Q., Qian, W., Cui, Y., Wei, F. 2016; 16 (2): 1367-1374

  Abstract

  Here, we studied the interwall friction and sliding behaviors of double-walled carbon nanotubes (DWCNTs). The interwall friction shows a linear dependence on the pullout velocity of the inner wall. The axial curvature in DWCNTs causes the significant increase of the interwall friction. The axial curvature also affects the sliding behavior of the inner wall. Compared with the axial curvature, the opening ends of DWCNTs play tiny roles in their interwall friction.

  View details for DOI 10.1021/acs.nanolett.5b04820

  View details for Web of Science ID 000370215200080

  View details for PubMedID 26784439

• The Effects of Cross-Linking in a Supramolecular Binder on Cycle Life in Silicon Microparticle Anodes. ACS applied materials & interfaces Lopez, J., Chen, Z., Wang, C., Andrews, S. C., Cui, Y., Bao, Z. 2016; 8 (3): 2318-2324

  Abstract

  Self-healing supramolecular binder was previously found to enhance the cycling stability of micron-sized silicon particles used as the active material in lithium-ion battery anodes. In this study, we systematically control the density of cross-linking junctions in a modified supramolecular polymer binder in order to better understand how viscoelastic materials properties affect cycling stability. We found that binders with relaxation times on the order of 0.1 s gave the best cycling stability with 80% capacity maintained for over 175 cycles using large silicon particles (∼0.9 um). We attributed this to an improved balance between the viscoelastic stress relaxation in the binder and the stiffness needed to maintain mechanical integrity of the electrode. The more cross-linked binder showed markedly worse performance confirming the need for liquid-like flow in order for our self-healing polymer electrode concept to be effective.

  View details for DOI 10.1021/acsami.5b11363

  View details for PubMedID 26716873

• Lithium-coated polymeric matrix as a minimum volume-change and dendrite-free lithium metal anode. Nature communications Liu, Y., Lin, D., Liang, Z., Zhao, J., Yan, K., Cui, Y. 2016; 7: 10992-?

  Abstract

  Lithium metal is the ideal anode for the next generation of high-energy-density batteries. Nevertheless, dendrite growth, side reactions and infinite relative volume change have prevented it from practical applications. Here, we demonstrate a promising metallic lithium anode design by infusing molten lithium into a polymeric matrix. The electrospun polyimide employed is stable against highly reactive molten lithium and, via a conformal layer of zinc oxide coating to render the surface lithiophilic, molten lithium can be drawn into the matrix, affording a nano-porous lithium electrode. Importantly, the polymeric backbone enables uniform lithium stripping/plating, which successfully confines lithium within the matrix, realizing minimum volume change and effective dendrite suppression. The porous electrode reduces the effective current density; thus, flat voltage profiles and stable cycling of more than 100 cycles is achieved even at a high current density of 5 mA cm(-2) in both carbonate and ether electrolyte. The advantages of the porous, polymeric matrix provide important insights into the design principles of lithium metal anodes.

  View details for DOI 10.1038/ncomms10992

  View details for PubMedID 26987481

• Direct Intertube Cross-Linking of Carbon Nanotubes at Room Temperature. Nano letters Gao, Y. n., Chen, H. n., Ge, J. n., Zhao, J. n., Li, Q. n., Tang, J. n., Cui, Y. n., Chen, L. n. 2016; 16 (10): 6541–47

  Abstract

  Carbon nanotubes (CNTs) have long been regarded as an efficient free radical scavenger because of the large-conjugation system in their electronic structures. Hence, despite abundant reports on CNT reacting with incoming free radical species, current research has not seen CNT itself displaying the chemical reactivity of free radicals. Here we show that reactive free radicals can in fact be generated on carbon nanotubes via reductive defluorination of highly fluorinated single-walled carbon nanotubes (FSWNTs). This finding not only enriches the current understanding of carbon nanotube chemical reactivity but also opens up new opportunities in CNT-based material design. For example, spacer-free direct intertube cross-linking of carbon nanotubes was previously achieved only under extremely high temperature and pressure or electron/ion beam irradiation. With the free radicals on defluorinated FSWNTs, the nanotubes containing multiple radicals on the sidewall can directly cross-link with each other under ambient temperature through intertube radical recombination. It is demonstrated that carbon nanotube fibers reinforced via direct cross-linking displays much improved mechanical properties.

  View details for PubMedID 27658002

• Highly Nitridated Graphene-Li2S Cathodes with Stable Modulated Cycles ADVANCED ENERGY MATERIALS Qiu, Y., Rong, G., Yang, J., Li, G., Ma, S., Wang, X., Pan, Z., Hou, Y., Liu, M., Ye, F., Li, W., Seh, Z. W., Tao, X., Yao, H., Liu, N., Zhang, R., Zhou, G., Wang, J., Fan, S., Cui, Y., Zhang, Y. 2015; 5 (23)

  View details for DOI 10.1002/aenm.201501369

  View details for Web of Science ID 000367199600013

• Hybrid Metal-Semiconductor Nanostructure for Ultrahigh Optical Absorption and Low Electrical Resistance at Optoelectronic Interfaces. ACS nano Narasimhan, V. K., Hymel, T. M., Lai, R. A., Cui, Y. 2015; 9 (11): 10590-10597

  Abstract

  Engineered optoelectronic surfaces must control both the flow of light and the flow of electrons at an interface; however, nanostructures for photon and electron management have typically been studied and optimized separately. In this work, we unify these concepts in a new hybrid metal-semiconductor surface that offers both strong light absorption and high electrical conductivity. We use metal-assisted chemical etching to nanostructure the surface of a silicon wafer, creating an array of silicon nanopillars protruding through holes in a gold film. When coated with a silicon nitride anti-reflection layer, we observe broad-band absorption of up to 97% in this structure, which is remarkable considering that metal covers 60% of the top surface. We use optical simulations to show that Mie-like resonances in the nanopillars funnel light around the metal layer and into the substrate, rendering the metal nearly transparent to the incoming light. Our results show that, across a wide parameter space, hybrid metal-semiconductor surfaces with absorption above 90% and sheet resistance below 20 Ω/□ are realizable, suggesting a new paradigm wherein transparent electrodes and photon management textures are designed and fabricated together to create high-performance optoelectronic interfaces.

  View details for DOI 10.1021/acsnano.5b04034

  View details for PubMedID 26447932

• Nanopurification of silicon from 84% to 99.999% purity with a simple and scalable process PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Zong, L., Zhu, B., Lu, Z., Tan, Y., Jin, Y., Liu, N., Hu, Y., Gu, S., Zhu, J., Cui, Y. 2015; 112 (44): 13473-13477

  Abstract

  Silicon, with its great abundance and mature infrastructure, is a foundational material for a range of applications, such as electronics, sensors, solar cells, batteries, and thermoelectrics. These applications rely on the purification of Si to different levels. Recently, it has been shown that nanosized silicon can offer additional advantages, such as enhanced mechanical properties, significant absorption enhancement, and reduced thermal conductivity. However, current processes to produce and purify Si are complex, expensive, and energy-intensive. Here, we show a nanopurification process, which involves only simple and scalable ball milling and acid etching, to increase Si purity drastically [up to 99.999% (wt %)] directly from low-grade and low-cost ferrosilicon [84% (wt %) Si; ∼$1/kg]. It is found that the impurity-rich regions are mechanically weak as breaking points during ball milling and thus, exposed on the surface, and they can be conveniently and effectively removed by chemical etching. We discovered that the purity goes up with the size of Si particles going down, resulting in high purity at the sub-100-nm scale. The produced Si nanoparticles with high purity and small size exhibit high performance as Li ion battery anodes, with high reversible capacity (1,755 mAh g(-1)) and long cycle life (73% capacity retention over 500 cycles). This nanopurification process provides a complimentary route to produce Si, with finely controlled size and purity, in a diverse set of applications.

  View details for DOI 10.1073/pnas.1513012112

  View details for PubMedID 26483490

  View details for PubMedCentralID PMC4640800

• Magnetic Field-Controlled Lithium Polysulfide Semiliquid Battery with Ferrofluidic Properties NANO LETTERS Li, W., Liang, Z., Lu, Z., Tao, X., Liu, K., Yao, H., Cui, Y. 2015; 15 (11): 7394-7399

  Abstract

  Large-scale energy storage systems are of critical importance for electric grids, especially with the rapid increasing deployment of intermittent renewable energy sources such as wind and solar. New cost-effective systems that can deliver high energy density and efficiency for such storage often involve the flow of redox molecules and particles. Enhancing the mass and electron transport is critical for efficient battery operation in these systems. Herein, we report the design and characterization of a novel proof-of-concept magnetic field-controlled flow battery using lithium metal-polysulfide semiliquid battery as an example. A biphasic magnetic solution containing lithium polysulfide and magnetic nanoparticles is used as catholyte, and lithium metal is used as anode. The catholyte is composed of two phases of polysulfide with different concentrations, in which most of the polysulfide molecules and the superparamagnetic iron oxide nanoparticles can be extracted together to form a high-concentration polysulfide phase, in close contact with the current collector under the influence of applied magnetic field. This unique feature can help to maximize the utilization of the polysulfide and minimize the polysulfide shuttle effect, contributing to enhanced energy density and Coulombic efficiency. Additionally, owing to the effect of the superparamagnetic nanoparticles, the concentrated polysulfide phase shows the behavior of a ferrofluid that is flowable with the control of magnetic field, which can be used for a hybrid flow battery without the employment of any pumps. Our innovative design provides new insight for a broad range of flow battery chemistries and systems.

  View details for DOI 10.1021/acs.nanolett.5b02818

  View details for PubMedID 26422674

• A phosphorene-graphene hybrid material as a high-capacity anode for sodium-ion batteries. Nature nanotechnology Sun, J., Lee, H., Pasta, M., Yuan, H., Zheng, G., Sun, Y., Li, Y., Cui, Y. 2015; 10 (11): 980-985

  Abstract

  Sodium-ion batteries have recently attracted significant attention as an alternative to lithium-ion batteries because sodium sources do not present the geopolitical issues that lithium sources might. Although recent reports on cathode materials for sodium-ion batteries have demonstrated performances comparable to their lithium-ion counterparts, the major scientific challenge for a competitive sodium-ion battery technology is to develop viable anode materials. Here we show that a hybrid material made out of a few phosphorene layers sandwiched between graphene layers shows a specific capacity of 2,440 mA h g(-1) (calculated using the mass of phosphorus only) at a current density of 0.05 A g(-1) and an 83% capacity retention after 100 cycles while operating between 0 and 1.5 V. Using in situ transmission electron microscopy and ex situ X-ray diffraction techniques, we explain the large capacity of our anode through a dual mechanism of intercalation of sodium ions along the x axis of the phosphorene layers followed by the formation of a Na3P alloy. The presence of graphene layers in the hybrid material works as a mechanical backbone and an electrical highway, ensuring that a suitable elastic buffer space accommodates the anisotropic expansion of phosphorene layers along the y and z axial directions for stable cycling operation.

  View details for DOI 10.1038/nnano.2015.194

  View details for PubMedID 26344183

• Surface Coating Constraint Induced Self-Discharging of Silicon Nanoparticles as Anodes for Lithium Ion Batteries NANO LETTERS Luo, L., Zhao, P., Yang, H., Liu, B., Zhang, J., Cui, Y., Yu, G., Zhang, S., Wang, C. 2015; 15 (10): 7016-7022

  Abstract

  One of the key challenges of Si-based anodes for lithium ion batteries is the large volume change upon lithiation and delithiation, which commonly leads to electrochemi-mechanical degradation and subsequent fast capacity fading. Recent studies have shown that applying nanometer-thick coating layers on Si nanoparticle (SiNPs) enhances cyclability and capacity retention. However, it is far from clear how the coating layer function from the point of view of both surface chemistry and electrochemi-mechanical effect. Herein, we use in situ transmission electron microscopy to investigate the lithiation/delithiation kinetics of SiNPs coated with a conductive polymer, polypyrrole (PPy). We discovered that this coating layer can lead to "self-delithiation" or "self-discharging" at different stages of lithiation. We rationalized that the self-discharging is driven by the internal compressive stress generated inside the lithiated SiNPs due to the constraint effect of the coating layer. We also noticed that the critical size of lithiation-induced fracture of SiNPs is increased from ∼150 nm for bare SiNPs to ∼380 nm for the PPy-coated SiNPs, showing a mechanically protective role of the coating layer. These observations demonstrate both beneficial and detrimental roles of the surface coatings, shedding light on rational design of surface coatings for silicon to retain high-power and high capacity as anode for lithium ion batteries.

  View details for DOI 10.1021/acs.nanolett.5b03047

  View details for PubMedID 26414120

• In Situ Electrochemical Oxidation Tuning of Transition Metal Disulfides to Oxides for Enhanced Water Oxidation. ACS central science Chen, W., Wang, H., Li, Y., Liu, Y., Sun, J., Lee, S., Lee, J., Cui, Y. 2015; 1 (5): 244-251

  Abstract

  The development of catalysts with earth-abundant elements for efficient oxygen evolution reactions is of paramount significance for clean and sustainable energy storage and conversion devices. Our group demonstrated recently that the electrochemical tuning of catalysts via lithium insertion and extraction has emerged as a powerful approach to improve catalytic activity. Here we report a novel in situ electrochemical oxidation tuning approach to develop a series of binary, ternary, and quaternary transition metal (e.g., Co, Ni, Fe) oxides from their corresponding sulfides as highly active catalysts for much enhanced water oxidation. The electrochemically tuned cobalt-nickel-iron oxides grown directly on the three-dimensional carbon fiber electrodes exhibit a low overpotential of 232 mV at current density of 10 mA cm(-2), small Tafel slope of 37.6 mV dec(-1), and exceptional long-term stability of electrolysis for over 100 h in 1 M KOH alkaline medium, superior to most non-noble oxygen evolution catalysts reported so far. The materials evolution associated with the electrochemical oxidation tuning is systematically investigated by various characterizations, manifesting that the improved activities are attributed to the significant grain size reduction and increase of surface area and electroactive sites. This work provides a promising strategy to develop electrocatalysts for large-scale water-splitting systems and many other applications.

  View details for DOI 10.1021/acscentsci.5b00227

  View details for PubMedID 27162978

• A Sulfur Cathode with Pomegranate-Like Cluster Structure ADVANCED ENERGY MATERIALS Li, W., Liang, Z., Lu, Z., Yao, H., Seh, Z. W., Yan, K., Zheng, G., Cui, Y. 2015; 5 (16)

  View details for DOI 10.1002/aenm.201500211

  View details for Web of Science ID 000360368100015

• Polarization-sensitive broadband photodetector using a black phosphorus vertical p-n junction NATURE NANOTECHNOLOGY Yuan, H., Liu, X., Afshinmanesh, F., Li, W., Xu, G., Sun, J., Lian, B., Curto, A. G., Ye, G., Hikita, Y., Shen, Z., Zhang, S., Chen, X., Brongersma, M., Hwang, H. Y., Cui, Y. 2015; 10 (8): 707-713

  Abstract

  The ability to detect light over a broad spectral range is central to practical optoelectronic applications and has been successfully demonstrated with photodetectors of two-dimensional layered crystals such as graphene and MoS2. However, polarization sensitivity within such a photodetector remains elusive. Here, we demonstrate a broadband photodetector using a layered black phosphorus transistor that is polarization-sensitive over a bandwidth from ∼400 nm to 3,750 nm. The polarization sensitivity is due to the strong intrinsic linear dichroism, which arises from the in-plane optical anisotropy of this material. In this transistor geometry, a perpendicular built-in electric field induced by gating can spatially separate the photogenerated electrons and holes in the channel, effectively reducing their recombination rate and thus enhancing the performance for linear dichroism photodetection. The use of anisotropic layered black phosphorus in polarization-sensitive photodetection might provide new functionalities in novel optical and optoelectronic device applications.

  View details for DOI 10.1038/NNANO.2015.112

  View details for PubMedID 26030655

• Theory of Half-Space Light Absorption Enhancement for Leaky Mode Resonant Nanowires NANO LETTERS Jia, Y., Qiu, M., Wu, H., Cui, Y., Fan, S., Ruan, Z. 2015; 15 (8): 5513-5518

  Abstract

  Semiconductor nanowires supporting leaky mode resonances have been used to increase light absorption in optoelectronic applications from solar cell to photodetector and sensor. The light conventionally illuminates these devices with a wide range of different incident angles from half space. Currently, most of the investigated nanowires have centrosymmetric geometry cross section, such as circle, hexagon, and rectangle. Here we show that the absorption capability of these symmetrical nanowires has an upper limit under the half-space illumination. Based on the temporal coupled-mode equation, we develop a reciprocity theory for leaky mode resonances in order to connect the angle-dependent absorption cross section and the radiation pattern. We show that in order to exceed such a half-space limit the radiation pattern should be noncentrosymmetric and dominate in the direction reciprocal to the illumination. As an example, we design a metal trough structure to achieve the desired radiation pattern for an embedded nanowire. In comparison to a single nanowire case the trough structure indeed overcomes the half-space limit and leads to 39% and 64% absorption enhancement in TM and TE polarizations, respectively. Also the trough structure enables the enhancement over a broad wavelength range.

  View details for DOI 10.1021/acs.nanolett.5b02044

  View details for PubMedID 26171950

• Direct Imaging of Nanoscale Conductance Evolution in Ion-Gel-Gated Oxide Transistors. Nano letters Ren, Y., Yuan, H., Wu, X., Chen, Z., Iwasa, Y., Cui, Y., Hwang, H. Y., Lai, K. 2015; 15 (7): 4730-4736

  Abstract

  Electrostatic modification of functional materials by electrolytic gating has demonstrated a remarkably wide range of density modulation, a condition crucial for developing novel electronic phases in systems ranging from complex oxides to layered chalcogenides. Yet little is known microscopically when carriers are modulated in electrolyte-gated electric double-layer transistors (EDLTs) due to the technical challenge of imaging the buried electrolyte-semiconductor interface. Here, we demonstrate the real-space mapping of the channel conductance in ZnO EDLTs using a cryogenic microwave impedance microscope. A spin-coated ionic gel layer with typical thicknesses below 50 nm allows us to perform high resolution (on the order of 100 nm) subsurface imaging, while maintaining the capability of inducing the metal-insulator transition under a gate bias. The microwave images vividly show the spatial evolution of channel conductance and its local fluctuations through the transition as well as the uneven conductance distribution established by a large source-drain bias. The unique combination of ultrathin ion-gel gating and microwave imaging offers a new opportunity to study the local transport and mesoscopic electronic properties in EDLTs.

  View details for DOI 10.1021/acs.nanolett.5b01631

  View details for PubMedID 26061780

• Artificial Solid Electrolyte Interphase-Protected LixSi Nanoparticles: An Efficient and Stable Prelithiation Reagent for Lithium-Ion Batteries. Journal of the American Chemical Society Zhao, J., Lu, Z., Wang, H., Liu, W., Lee, H., Yan, K., Zhuo, D., Lin, D., Liu, N., Cui, Y. 2015; 137 (26): 8372-8375

  Abstract

  Prelithiation is an important strategy to compensate for lithium loss in lithium-ion batteries, particularly during the formation of the solid electrolyte interphase (SEI) from reduced electrolytes in the first charging cycle. We recently demonstrated that LixSi nanoparticles (NPs) synthesized by thermal alloying can serve as a high-capacity prelithiation reagent, although their chemical stability in the battery processing environment remained to be improved. Here we successfully developed a surface modification method to enhance the stability of LixSi NPs by exploiting the reduction of 1-fluorodecane on the LixSi surface to form a continuous and dense coating through a reaction process similar to SEI formation. The coating, consisting of LiF and lithium alkyl carbonate with long hydrophobic carbon chains, serves as an effective passivation layer in the ambient environment. Remarkably, artificial-SEI-protected LixSi NPs show a high prelithiation capacity of 2100 mA h g(-1) with negligible capacity decay in dry air after 5 days and maintain a high capacity of 1600 mA h g(-1) in humid air (∼10% relative humidity). Silicon, tin, and graphite were successfully prelithiated with these NPs to eliminate the irreversible first-cycle capacity loss. The use of prelithiation reagents offers a new approach to realize next-generation high-energy-density lithium-ion batteries.

  View details for DOI 10.1021/jacs.5b04526

  View details for PubMedID 26091423

• Large-Area Nanosphere Self-Assembly by a Micro-Propulsive Injection Method for High Throughput Periodic Surface Nanotexturing NANO LETTERS Gao, P., He, J., Zhou, S., Yang, X., Li, S., Sheng, J., Wang, D., Yu, T., Ye, J., Cui, Y. 2015; 15 (7): 4591-4598

  Abstract

  A high throughput surface texturing process for optical and optoelectric devices based on a large-area self-assembly of nanospheres via a low-cost micropropulsive injection (MPI) method is presented. The novel MPI process enables the formation of a well-organized monolayer of hexagonally arranged nanosphere arrays (NAs) with tunable periodicity directly on the water surface, which is then transferred onto the preset substrates. This process can readily reach a throughput of 3000 wafers/h, which is compatible with the high volume photovoltaic manufacturing, thereby presenting a highly versatile platform for the fabrication of periodic nanotexturing on device surfaces. Specifically, a double-sided grating texturing with top-sided nanopencils and bottom-sided inverted-nanopyramids is realized in a thin film of crystalline silicon (28 μm in thickness) using chemical etching on the mask of NAs to significantly enhance antireflection and light trapping, resulting in absorptions nearly approaching the Lambertian limit over a broad wavelength range of 375-1000 nm and even surpassing this limit beyond 1000 nm. In addition, it is demonstrated that the NAs can serve as templates for replicas of three-dimensional conformal amorphous silicon films with significantly enhanced light harvesting. The MPI induced self-assembly process may provide a universal and cost-effective solution for boosting light utilization, a problem of crucial importance for ultrathin solar cells.

  View details for DOI 10.1021/acs.nanolett.5b01202

  View details for PubMedID 26039258

• Roll-to-Roll Encapsulation of Metal Nanowires between Graphene and Plastic Substrate for High-Performance Flexible Transparent Electrodes NANO LETTERS Deng, B., Hsu, P., Chen, G., Chandrashekar, B. N., Liao, L., Ayitimuda, Z., Wu, J., Guo, Y., Lin, L., Zhou, Y., Aisijiang, M., Xie, Q., Cui, Y., Liu, Z., Peng, H. 2015; 15 (6): 4206-4213

  Abstract

  Transparent conductive film on plastic substrate is a critical component in low-cost, flexible, and lightweight optoelectronics. Industrial-scale manufacturing of high-performance transparent conductive flexible plastic is needed to enable wide-ranging applications. Here, we demonstrate a continuous roll-to-roll (R2R) production of transparent conductive flexible plastic based on a metal nanowire network fully encapsulated between graphene monolayer and plastic substrate. Large-area graphene film grown on Cu foil via a R2R chemical vapor deposition process was hot-laminated onto nanowires precoated EVA/PET film, followed by a R2R electrochemical delamination that preserves the Cu foil for reuse. The encapsulated structure minimized the resistance of both wire-to-wire junctions and graphene grain boundaries and strengthened adhesion of nanowires and graphene to plastic substrate, resulting in superior optoelectronic properties (sheet resistance of ∼8 Ω sq(-1) at 94% transmittance), remarkable corrosion resistance, and excellent mechanical flexibility. With these advantages, long-cycle life flexible electrochromic devices are demonstrated, showing up to 10000 cycles.

  View details for DOI 10.1021/acs.nanolett.5b01531

  View details for Web of Science ID 000356316900083

  View details for PubMedID 26020567

• Vertical nanopillars for in situ probing of nuclear mechanics in adherent cells. Nature nanotechnology Hanson, L., Zhao, W., Lou, H., Lin, Z. C., Lee, S. W., Chowdary, P., Cui, Y., Cui, B. 2015; 10 (6): 554-562

  Abstract

  The mechanical stability and deformability of the cell nucleus are crucial to many biological processes, including migration, proliferation and polarization. In vivo, the cell nucleus is frequently subjected to deformation on a variety of length and time scales, but current techniques for studying nuclear mechanics do not provide access to subnuclear deformation in live functioning cells. Here we introduce arrays of vertical nanopillars as a new method for the in situ study of nuclear deformability and the mechanical coupling between the cell membrane and the nucleus in live cells. Our measurements show that nanopillar-induced nuclear deformation is determined by nuclear stiffness, as well as opposing effects from actin and intermediate filaments. Furthermore, the depth, width and curvature of nuclear deformation can be controlled by varying the geometry of the nanopillar array. Overall, vertical nanopillar arrays constitute a novel approach for non-invasive, subcellular perturbation of nuclear mechanics and mechanotransduction in live cells.

  View details for DOI 10.1038/nnano.2015.88

  View details for PubMedID 25984833

• Understanding the Anchoring Effect of Two-Dimensional Layered Materials for Lithium-Sulfur Batteries NANO LETTERS Zhang, Q., Wang, Y., Seh, Z. W., Fu, Z., Zhang, R., Cui, Y. 2015; 15 (6): 3780-3786

  Abstract

  Although the rechargeable lithium-sulfur battery system has attracted significant attention due to its high theoretical specific energy, its implementation has been impeded by multiple challenges, especially the dissolution of intermediate lithium polysulfide (Li2Sn) species into the electrolyte. Introducing anchoring materials, which can induce strong binding interaction with Li2Sn species, has been demonstrated as an effective way to overcome this problem and achieve long-term cycling stability and high-rate performance. The interaction between Li2Sn species and anchoring materials should be studied at the atomic level in order to understand the mechanism behind the anchoring effect and to identify ideal anchoring materials to further improve the performance of Li-S batteries. Using first-principles approach with van der Waals interaction included, we systematically investigate the adsorption of Li2Sn species on various two-dimensional layered materials (oxides, sulfides, and chlorides) and study the detailed interaction and electronic structure, including binding strength, configuration distortion, and charge transfer. We gain insight into how van der Waals interaction and chemical binding contribute to the adsorption of Li2Sn species for anchoring materials with strong, medium, and weak interactions. We understand why the anchoring materials can avoid the detachment of Li2S as in carbon substrate, and we discover that too strong binding strength can cause decomposition of Li2Sn species.

  View details for DOI 10.1021/acs.nanolett.5b00367

  View details for Web of Science ID 000356316900019

  View details for PubMedID 25961805

• Realization of 13.6% Efficiency on 20 mu m Thick Si/Organic Hybrid Heterojunction Solar Cells via Advanced Nanotexturing and Surface Recombination Suppression ACS NANO He, J., Gao, P., Liao, M., Yang, X., Ying, Z., Zhou, S., Ye, J., Cui, Y. 2015; 9 (6): 6522-6531

  Abstract

  Hybrid silicon/polymer solar cells promise to be an economically feasible alternative energy solution for various applications if ultrathin flexible crystalline silicon (c-Si) substrates are used. However, utilization of ultrathin c-Si encounters problems in light harvesting and electronic losses at surfaces, which severely degrade the performance of solar cells. Here, we developed a metal-assisted chemical etching method to deliver front-side surface texturing of hierarchically bowl-like nanopores on 20 μm c-Si, enabling an omnidirectional light harvesting over the entire solar spectrum as well as an enlarged contact area with the polymer. In addition, a back surface field was introduced on the back side of the thin c-Si to minimize the series resistance losses as well as to suppress the surface recombination by the built high-low junction. Through these improvements, a power conversion efficiency (PCE) up to 13.6% was achieved under an air mass 1.5 G irradiation for silicon/organic hybrid solar cells with the c-Si thickness of only about 20 μm. This PCE is as high as the record currently reported in hybrid solar cells constructed from bulk c-Si, suggesting a design rule for efficient silicon/organic solar cells with thinner absorbers.

  View details for DOI 10.1021/acsnano.5b02432

  View details for PubMedID 26047260

• Ultrahigh Surface Area Three-Dimensional Porous Graphitic Carbon from Conjugated Polymeric Molecular Framework. ACS central science To, J. W., Chen, Z., Yao, H., He, J., Kim, K., Chou, H. H., Pan, L., Wilcox, J., Cui, Y., Bao, Z. 2015; 1 (2): 68-76

  Abstract

  Porous graphitic carbon is essential for many applications such as energy storage devices, catalysts, and sorbents. However, current graphitic carbons are limited by low conductivity, low surface area, and ineffective pore structure. Here we report a scalable synthesis of porous graphitic carbons using a conjugated polymeric molecular framework as precursor. The multivalent cross-linker and rigid conjugated framework help to maintain micro- and mesoporous structures, while promoting graphitization during carbonization and chemical activation. The above unique design results in a class of highly graphitic carbons at temperature as low as 800 °C with record-high surface area (4073 m(2) g(-1)), large pore volume (2.26 cm(-3)), and hierarchical pore architecture. Such carbons simultaneously exhibit electrical conductivity >3 times more than activated carbons, very high electrochemical activity at high mass loading, and high stability, as demonstrated by supercapacitors and lithium-sulfur batteries with excellent performance. Moreover, the synthesis can be readily tuned to make a broad range of graphitic carbons with desired structures and compositions for many applications.

  View details for DOI 10.1021/acscentsci.5b00149

  View details for PubMedID 27162953

  View details for PubMedCentralID PMC4827563

• Self-assembled three-dimensional and compressible interdigitated thin-film supercapacitors and batteries NATURE COMMUNICATIONS Nystrom, G., Marais, A., Karabulut, E., Wagberg, L., Cui, Y., Hamedi, M. M. 2015; 6

  Abstract

  Traditional thin-film energy-storage devices consist of stacked layers of active films on two-dimensional substrates and do not exploit the third dimension. Fully three-dimensional thin-film devices would allow energy storage in bulk materials with arbitrary form factors and with mechanical properties unique to bulk materials such as compressibility. Here we show three-dimensional energy-storage devices based on layer-by-layer self-assembly of interdigitated thin films on the surface of an open-cell aerogel substrate. We demonstrate a reversibly compressible three-dimensional supercapacitor with carbon nanotube electrodes and a three-dimensional hybrid battery with a copper hexacyanoferrate ion intercalating cathode and a carbon nanotube anode. The three-dimensional supercapacitor shows stable operation over 400 cycles with a capacitance of 25 F g(-1) and is fully functional even at compressions up to 75%. Our results demonstrate that layer-by-layer self-assembly inside aerogels is a rapid, precise and scalable route for building high-surface-area 3D thin-film devices.

  View details for DOI 10.1038/ncomms8259

  View details for Web of Science ID 000355539700001

  View details for PubMedID 26021485

  View details for PubMedCentralID PMC4458871

• Surface-Coating Regulated Lithiation Kinetics and Degradation in Silicon Nanowires for Lithium Ion Battery ACS NANO Luo, L., Yang, H., Yan, P., Travis, J. J., Lee, Y., Liu, N., Piper, D. M., Lee, S., Zhao, P., George, S. M., Zhang, J., Cui, Y., Zhang, S., Ban, C., Wang, C. 2015; 9 (5): 5559-5566

  Abstract

  Silicon (Si)-based materials hold promise as the next-generation anodes for high-energy lithium (Li)-ion batteries. Enormous research efforts have been undertaken to mitigate the chemo-mechanical failure due to the large volume changes of Si during lithiation and delithiation cycles. It has been found that nanostructured Si coated with carbon or other functional materials can lead to significantly improved cyclability. However, the underlying mechanism and comparative performance of different coatings remain poorly understood. Herein, using in situ transmission electron microscopy (TEM) through a nanoscale half-cell battery, in combination with chemo-mechanical simulation, we explored the effect of thin (∼5 nm) alucone and Al2O3 coatings on the lithiation kinetics of Si nanowires (SiNWs). We observed that the alucone coating leads to a "V-shaped" lithiation front of the SiNWs, while the Al2O3 coating yields an "H-shaped" lithiation front. These observations indicate that the difference between the Li surface diffusivity and bulk lithiation rate of the coatings dictates lithiation induced morphological evolution in the nanowires. Our experiments also indicate that the reaction rate in the coating layer can be the limiting step for lithiation and therefore critically influences the rate performance of the battery. Further, the failure mechanism of the Al2O3 coated SiNWs was also explored. Our studies shed light on the design of high capacity, high rate and long cycle life Li-ion batteries.

  View details for DOI 10.1021/acsnano.5b01681

  View details for PubMedID 25893684

• High-Areal-Capacity Silicon Electrodes with Low-Cost Silicon Particles Based on Spatial Control of Self-Healing Binder ADVANCED ENERGY MATERIALS Chen, Z., Wang, C., Lopez, J., Lu, Z., Cui, Y., Bao, Z. 2015; 5 (8)

  View details for DOI 10.1002/aenm.201401826

  View details for Web of Science ID 000353357600005

• Ionic Conductivity Enhancement of Polymer Electrolytes with Ceramic Nanowire Fillers NANO LETTERS Liu, W., Liu, N., Sun, J., Hsu, P., Li, Y., Lee, H., Cui, Y. 2015; 15 (4): 2740-2745

  Abstract

  Solid-state electrolytes provide substantial improvements to safety and electrochemical stability in lithium-ion batteries when compared with conventional liquid electrolytes, which makes them a promising alternative technology for next-generation high-energy batteries. Currently, the low mobility of lithium ions in solid electrolytes limits their practical application. The ongoing research over the past few decades on dispersing of ceramic nanoparticles into polymer matrix has been proved effective to enhance ionic conductivity although it is challenging to form the efficiency networks of ionic conduction with nanoparticles. In this work, we first report that ceramic nanowire fillers can facilitate formation of such ionic conduction networks in polymer-based solid electrolyte to enhance its ionic conductivity by three orders of magnitude. Polyacrylonitrile-LiClO4 incorporated with 15 wt % Li0.33La0.557TiO3 nanowire composite electrolyte exhibits an unprecedented ionic conductivity of 2.4 × 10(-4) S cm(-1) at room temperature, which is attributed to the fast ion transport on the surfaces of ceramic nanowires acting as conductive network in the polymer matrix. In addition, the ceramic-nanowire filled composite polymer electrolyte shows an enlarged electrochemical stability window in comparison to the one without fillers. The discovery in the present work paves the way for the design of solid ion electrolytes with superior performance.

  View details for DOI 10.1021/acs.nanolett.5b00600

  View details for PubMedID 25782069

• Electrically tunable coherent optical absorption in graphene with ion gel. Nano letters Thareja, V., Kang, J., Yuan, H., Milaninia, K. M., Hwang, H. Y., Cui, Y., Kik, P. G., Brongersma, M. L. 2015; 15 (3): 1570-1576

  Abstract

  We demonstrate electrical control over coherent optical absorption in a graphene-based Salisbury screen consisting of a single layer of graphene placed in close proximity to a gold back reflector. The screen was designed to enhance light absorption at a target wavelength of 3.2 μm by using a 600 nm-thick, nonabsorbing silica spacer layer. An ionic gel layer placed on top of the screen was used to electrically gate the charge density in the graphene layer. Spectroscopic reflectance measurements were performed in situ as a function of gate bias. The changes in the reflectance spectra were analyzed using a Fresnel based transfer matrix model in which graphene was treated as an infinitesimally thin sheet with a conductivity given by the Kubo formula. The analysis reveals that a careful choice of the ionic gel layer thickness can lead to optical absorption enhancements of up to 5.5 times for the Salisbury screen compared to a suspended sheet of graphene. In addition to these absorption enhancements, we demonstrate very large electrically induced changes in the optical absorption of graphene of ∼3.3% per volt, the highest attained so far in a device that features an atomically thick active layer. This is attributable in part to the more effective gating achieved with the ion gel over the conventional dielectric back gates and partially by achieving a desirable coherent absorption effect linked to the presence of the thin ion gel that boosts the absorption by 40%.

  View details for DOI 10.1021/nl503431d

  View details for PubMedID 25671369

• Nonfilling Carbon Coating of Porous Silicon Micrometer-Sized Particles for High-Performance Lithium Battery Anodes ACS NANO Lu, Z., Liu, N., Lee, H., Zhao, J., Li, W., Li, Y., Cui, Y. 2015; 9 (3): 2540-2547

  Abstract

  Silicon is widely recognized as one of the most promising anode materials for lithium-ion batteries due to its 10 times higher specific capacity than graphite. Unfortunately, the large volume change of Si materials during their lithiation/delithiation process results in severe pulverization, loss of electrical contact, unstable solid-electrolyte interphase (SEI), and eventual capacity fading. Although there has been tremendous progress to overcome these issues through nanoscale materials design, improved volumetric capacity and reduced cost are still needed for practical application. To address these issues, we design a nonfilling carbon-coated porous silicon microparticle (nC-pSiMP). In this structure, porous silicon microparticles (pSiMPs) consist of many interconnected primary silicon nanoparticles; only the outer surface of the pSiMPs was coated with carbon, leaving the interior pore structures unfilled. Nonfilling carbon coating hinders electrolyte penetration into the nC-pSiMPs, minimizes the electrode-electrolyte contact area, and retains the internal pore space for Si expansion. SEI formation is mostly limited to the outside of the microparticles. As a result, the composite structure demonstrates excellent cycling stability with high reversible specific capacity (∼1500 mAh g(-1), 1000 cycles) at the rate of C/4. The nC-pSiMPs contain accurate void space to accommodate Si expansion while not losing packing density, which allows for a high volumetric capacity (∼1000 mAh cm(-3)). The areal capacity can reach over 3 mAh cm(-2) with the mass loading 2.01 mg cm(-2). Moreover, the production of nC-pSiMP is simple and scalable using a low-cost silicon monoxide microparticle starting material.

  View details for DOI 10.1021/nn505410q

  View details for PubMedID 25738223

• In situ observation of divergent phase transformations in individual sulfide nanocrystals. Nano letters McDowell, M. T., Lu, Z., Koski, K. J., Yu, J. H., Zheng, G., Cui, Y. 2015; 15 (2): 1264-1271

  Abstract

  Inorganic nanocrystals have attracted widespread attention both for their size-dependent properties and for their potential use as building blocks in an array of applications. A complete understanding of chemical transformations in nanocrystals is important for controlling structure, composition, and electronic properties. Here, we utilize in situ high-resolution transmission electron microscopy to study structural and morphological transformations in individual sulfide nanocrystals (copper sulfide, iron sulfide, and cobalt sulfide) as they react with lithium. The experiments reveal the influence of structure and composition on the transformation pathway (conversion versus displacement reactions), and they provide a high-resolution view of the unique displacement reaction mechanism in copper sulfide in which copper metal is extruded from the crystal. The structural similarity between the initial and final phases, as well as the mobility of ions within the crystal, are seen to exert a controlling influence on the reaction pathway.

  View details for DOI 10.1021/nl504436m

  View details for PubMedID 25602713

• Vertical Heterostructure of Two-Dimensional MoS2 and WSe2 with Vertically Aligned Layers. Nano letters Yu, J. H., Lee, H. R., Hong, S. S., Kong, D., Lee, H., Wang, H., Xiong, F., Wang, S., Cui, Y. 2015; 15 (2): 1031-1035

  Abstract

  Two-dimensional (2D) layered materials consist of covalently bonded 2D atomic layers stacked by van der Waals interactions. Such anisotropic bonding nature gives rise to the orientation-dependent functionalities of the 2D layered materials. Different from most studies of 2D materials with their atomic layers parallel to substrate, we have recently developed layer vertically aligned 2D material nanofilms. Built on these developments, here, we demonstrate the synthesis of vertical heterostructure of n-type MoS2 and p-type WSe2 with vertically aligned atomic layers. Thin film of MoS2/WSe2 vertical structure was successfully synthesized without significant alloy formation. The heterostructure synthesis is scalable to a large area over 1 cm(2). We demonstrated the pn junction diode behavior of the heterostructure device. This novel device geometry opens up exciting opportunities for a variety of electronic and optoelectronic devices, complementary to the recent interesting vertical heterostructures with horizontal atomic layers.

  View details for DOI 10.1021/nl503897h

  View details for PubMedID 25590995

• Personal thermal management by metallic nanowire-coated textile. Nano letters Hsu, P., Liu, X., Liu, C., Xie, X., Lee, H. R., Welch, A. J., Zhao, T., Cui, Y. 2015; 15 (1): 365-371

  Abstract

  Heating consumes large amount of energy and is a primary source of greenhouse gas emission. Although energy-efficient buildings are developing quickly based on improving insulation and design, a large portion of energy continues to be wasted on heating empty space and nonhuman objects. Here, we demonstrate a system of personal thermal management using metallic nanowire-embedded cloth that can reduce this waste. The metallic nanowires form a conductive network that not only is highly thermal insulating because it reflects human body infrared radiation but also allows Joule heating to complement the passive insulation. The breathability and durability of the original cloth is not sacrificed because of the nanowires' porous structure. This nanowire cloth can efficiently warm human bodies and save hundreds of watts per person as compared to traditional indoor heaters.

  View details for DOI 10.1021/nl5036572

  View details for PubMedID 25434959

• Pressure induced metallization with absence of structural transition in layered molybdenum diselenide. Nature communications Zhao, Z., Zhang, H., Yuan, H., Wang, S., Lin, Y., Zeng, Q., Xu, G., Liu, Z., Solanki, G. K., Patel, K. D., Cui, Y., Hwang, H. Y., Mao, W. L. 2015; 6: 7312-?

  Abstract

  Layered transition-metal dichalcogenides have emerged as exciting material systems with atomically thin geometries and unique electronic properties. Pressure is a powerful tool for continuously tuning their crystal and electronic structures away from the pristine states. Here, we systematically investigated the pressurized behavior of MoSe2 up to ∼60 GPa using multiple experimental techniques and ab-initio calculations. MoSe2 evolves from an anisotropic two-dimensional layered network to a three-dimensional structure without a structural transition, which is a complete contrast to MoS2. The role of the chalcogenide anions in stabilizing different layered patterns is underscored by our layer sliding calculations. MoSe2 possesses highly tunable transport properties under pressure, determined by the gradual narrowing of its band-gap followed by metallization. The continuous tuning of its electronic structure and band-gap in the range of visible light to infrared suggest possible energy-variable optoelectronics applications in pressurized transition-metal dichalcogenides.

  View details for DOI 10.1038/ncomms8312

  View details for PubMedID 26088416

• A reaction-controlled diffusion model for the lithiation of silicon in lithium-ion batteries Extreme Mechanics Letters Zhang, X., Lee, S., Lee, H., Cui, Y., Linder, C. 2015; 4: 61–75

  View details for DOI 10.1016/j.eml.2015.04.005

• Bifunctional non-noble metal oxide nanoparticle electrocatalysts through lithium-induced conversion for overall water splitting. Nature communications Wang, H., Lee, H., Deng, Y., Lu, Z., Hsu, P., Liu, Y., Lin, D., Cui, Y. 2015; 6: 7261-?

  Abstract

  Developing earth-abundant, active and stable electrocatalysts which operate in the same electrolyte for water splitting, including oxygen evolution reaction and hydrogen evolution reaction, is important for many renewable energy conversion processes. Here we demonstrate the improvement of catalytic activity when transition metal oxide (iron, cobalt, nickel oxides and their mixed oxides) nanoparticles (∼20 nm) are electrochemically transformed into ultra-small diameter (2-5 nm) nanoparticles through lithium-induced conversion reactions. Different from most traditional chemical syntheses, this method maintains excellent electrical interconnection among nanoparticles and results in large surface areas and many catalytically active sites. We demonstrate that lithium-induced ultra-small NiFeOx nanoparticles are active bifunctional catalysts exhibiting high activity and stability for overall water splitting in base. We achieve 10 mA cm(-2) water-splitting current at only 1.51 V for over 200 h without degradation in a two-electrode configuration and 1 M KOH, better than the combination of iridium and platinum as benchmark catalysts.

  View details for DOI 10.1038/ncomms8261

  View details for PubMedID 26099250

• Kinetics and fracture resistance of lithiated silicon nanostructure pairs controlled by their mechanical interaction. Nature communications Lee, S. W., Lee, H., Ryu, I., Nix, W. D., Gao, H., Cui, Y. 2015; 6: 7533-?

  Abstract

  Following an explosion of studies of silicon as a negative electrode for Li-ion batteries, the anomalous volumetric changes and fracture of lithiated single Si particles have attracted significant attention in various fields, including mechanics. However, in real batteries, lithiation occurs simultaneously in clusters of Si in a confined medium. Hence, understanding how the individual Si structures interact during lithiation in a closed space is necessary. Here, we demonstrate physical and mechanical interactions of swelling Si structures during lithiation using well-defined Si nanopillar pairs. Ex situ SEM and in situ TEM studies reveal that compressive stresses change the reaction kinetics so that preferential lithiation occurs at free surfaces when the pillars are mechanically clamped. Such mechanical interactions enhance the fracture resistance of lithiated Si by lessening the tensile stress concentrations in Si structures. This study will contribute to improved design of Si structures at the electrode level for high-performance Li-ion batteries.

  View details for DOI 10.1038/ncomms8533

  View details for PubMedID 26112834

• Transparent air filter for high-efficiency PM2.5 capture. Nature communications Liu, C., Hsu, P., Lee, H., Ye, M., Zheng, G., Liu, N., Li, W., Cui, Y. 2015; 6: 6205-?

  Abstract

  Particulate matter (PM) pollution has raised serious concerns for public health. Although outdoor individual protection could be achieved by facial masks, indoor air usually relies on expensive and energy-intensive air-filtering devices. Here, we introduce a transparent air filter for indoor air protection through windows that uses natural passive ventilation to effectively protect the indoor air quality. By controlling the surface chemistry to enable strong PM adhesion and also the microstructure of the air filters to increase the capture possibilities, we achieve transparent, high air flow and highly effective air filters of ~90% transparency with >95.00% removal of PM2.5 under extreme hazardous air-quality conditions (PM2.5 mass concentration >250 μg m(-3)). A field test in Beijing shows that the polyacrylonitrile transparent air filter has the best PM2.5 removal efficiency of 98.69% at high transmittance of ~77% during haze occurrence.

  View details for DOI 10.1038/ncomms7205

  View details for PubMedID 25683688

• A Highly Reversible Room-Temperature Sodium Metal Anode. ACS central science Seh, Z. W., Sun, J. n., Sun, Y. n., Cui, Y. n. 2015; 1 (8): 449–55

  Abstract

  Owing to its low cost and high natural abundance, sodium metal is among the most promising anode materials for energy storage technologies beyond lithium ion batteries. However, room-temperature sodium metal anodes suffer from poor reversibility during long-term plating and stripping, mainly due to formation of nonuniform solid electrolyte interphase as well as dendritic growth of sodium metal. Herein we report for the first time that a simple liquid electrolyte, sodium hexafluorophosphate in glymes (mono-, di-, and tetraglyme), can enable highly reversible and nondendritic plating-stripping of sodium metal anodes at room temperature. High average Coulombic efficiencies of 99.9% were achieved over 300 plating-stripping cycles at 0.5 mA cm(-2). The long-term reversibility was found to arise from the formation of a uniform, inorganic solid electrolyte interphase made of sodium oxide and sodium fluoride, which is highly impermeable to electrolyte solvent and conducive to nondendritic growth. As a proof of concept, we also demonstrate a room-temperature sodium-sulfur battery using this class of electrolytes, paving the way for the development of next-generation, sodium-based energy storage technologies.

  View details for PubMedID 27163006

• The synergetic effect of lithium polysulfide and lithium nitrate to prevent lithium dendrite growth. Nature communications Li, W., Yao, H., Yan, K., Zheng, G., Liang, Z., Chiang, Y., Cui, Y. 2015; 6: 7436-?

  Abstract

  Lithium metal has shown great promise as an anode material for high-energy storage systems, owing to its high theoretical specific capacity and low negative electrochemical potential. Unfortunately, uncontrolled dendritic and mossy lithium growth, as well as electrolyte decomposition inherent in lithium metal-based batteries, cause safety issues and low Coulombic efficiency. Here we demonstrate that the growth of lithium dendrites can be suppressed by exploiting the reaction between lithium and lithium polysulfide, which has long been considered as a critical flaw in lithium-sulfur batteries. We show that a stable and uniform solid electrolyte interphase layer is formed due to a synergetic effect of both lithium polysulfide and lithium nitrate as additives in ether-based electrolyte, preventing dendrite growth and minimizing electrolyte decomposition. Our findings allow for re-evaluation of the reactions regarding lithium polysulfide, lithium nitrate and lithium metal, and provide insights into solving the problems associated with lithium metal anodes.

  View details for DOI 10.1038/ncomms8436

  View details for PubMedID 26081242

• Physical and chemical tuning of two-dimensional transition metal dichalcogenides CHEMICAL SOCIETY REVIEWS Wang, H., Yuan, H., Hong, S. S., Li, Y., Cui, Y. 2015; 44 (9): 2664-2680

  Abstract

  The development of two-dimensional (2D) materials has been experiencing a renaissance since the adventure of graphene. Layered transition metal dichalcogenides (TMDs) are now playing increasingly important roles in both fundamental studies and technological applications due to their wide range of material properties from semiconductors, metals to superconductors. However, a material with fixed properties may not exhibit versatile applications. Due to the unique crystal structures, the physical and chemical properties of 2D TMDs can be effectively tuned through different strategies such as reducing dimensions, intercalation, heterostructure, alloying, and gating. With the flexible tuning of properties 2D TMDs become attractive candidates for a variety of applications including electronics, optoelectronics, catalysis, and energy.

  View details for DOI 10.1039/c4cs00287c

  View details for PubMedID 25474482

• Two-Dimensional Layered Chalcogenides: From Rational Synthesis to Property Control via Orbital Occupation and Electron Filling ACCOUNTS OF CHEMICAL RESEARCH Yuan, H., Wang, H., Cui, Y. 2015; 48 (1): 81-90

  Abstract

  Electron occupation of orbitals in two-dimensional (2D) layered materials controls the magnitude and anisotropy of the interatomic electron transfer and exerts a key influence on the chemical bonding modes of 2D layered lattices. Therefore, their orbital occupations are believed to be responsible for massive variations of the physical and chemical properties from electrocatalysis and energy storage, to charge density waves, superconductivity, spin-orbit coupling, and valleytronics. Especially in nanoscale structures such as nanoribbons, nanoplates, and nanoflakes, 2D layered materials provide opportunities to exploit new quantum phenomena. In this Account, we report our recent progress in the rational design and chemical, electrochemical, and electrical modulations of the physical and chemical properties of layered nanomaterials via modification of the electron occupation in their electronic structures. Here, we start with the growth and fabrication of a group of layered chalcogenides with varied orbital occupation (from 4d/5d electron configuration to 5p/6p electron configuration). The growth techniques include bottom-up methods, such as vapor-liquid-solid growth and vapor-solid growth, and top-down methods, such as mechanical exfoliation with tape and AFM tip scanning. Next, we demonstrate the experimental strategies for the tuning of the chemical potential (orbital occupation tuned with electron filling) and the resulting modulation of the electronic states of layered materials, such as electric-double-layer gating, electrochemical intercalation, and chemical intercalation with molecule and zerovalence metal species. Since the properties of layered chalcogenides are normally dominated by the specific band structure around which the chemical potential is sitting, their desired electronic states and properties can be modulated in a large range, showing unique phenomena including quantum electronic transport and extraordinary optical transmittance. As the most important part of this Account, we further demonstrate some representative examples for the tuning of catalytic, optical, electronic, and spintronic properties of 2D layered chalcogenides, where one can see not only edge-state induced enhancement of catalysis, quantum Aharonov-Bohm interference of the topological surface states, intercalation modulated extraordinary transmittance, and surface plasmonics but also external gating induced superconductivity and spin-coupled valley photocurrent. Since our findings reflect the critical influences of the electron filling of orbital occupation to the properties in 2D layered chalcogenides, we thus last highlight the importance and the prospective of orbital occupation in 2D layered materials for further exploring potential functionalized applications.

  View details for DOI 10.1021/ar5003297

  View details for PubMedID 25553585

• Integrated digital inverters based on two-dimensional anisotropic ReS2 field-effect transistors. Nature communications Liu, E., Fu, Y., Wang, Y., Feng, Y., Liu, H., Wan, X., Zhou, W., Wang, B., Shao, L., Ho, C., Huang, Y., Cao, Z., Wang, L., Li, A., Zeng, J., Song, F., Wang, X., Shi, Y., Yuan, H., Hwang, H. Y., Cui, Y., Miao, F., Xing, D. 2015; 6: 6991-?

  Abstract

  Semiconducting two-dimensional transition metal dichalcogenides are emerging as top candidates for post-silicon electronics. While most of them exhibit isotropic behaviour, lowering the lattice symmetry could induce anisotropic properties, which are both scientifically interesting and potentially useful. Here we present atomically thin rhenium disulfide (ReS2) flakes with unique distorted 1T structure, which exhibit in-plane anisotropic properties. We fabricated monolayer and few-layer ReS2 field-effect transistors, which exhibit competitive performance with large current on/off ratios (∼10(7)) and low subthreshold swings (100 mV per decade). The observed anisotropic ratio along two principle axes reaches 3.1, which is the highest among all known two-dimensional semiconducting materials. Furthermore, we successfully demonstrated an integrated digital inverter with good performance by utilizing two ReS2 anisotropic field-effect transistors, suggesting the promising implementation of large-scale two-dimensional logic circuits. Our results underscore the unique properties of two-dimensional semiconducting materials with low crystal symmetry for future electronic applications.

  View details for DOI 10.1038/ncomms7991

  View details for PubMedID 25947630

  View details for PubMedCentralID PMC4432591

• Enhancing the nanomaterial bio-interface by addition of mesoscale secondary features: crinkling of carbon nanotube films to create subcellular ridges. ACS nano Xie, X., Zhao, W., Lee, H. R., Liu, C., Ye, M., Xie, W., Cui, B., Criddle, C. S., Cui, Y. 2014; 8 (12): 11958-11965

  Abstract

  Biological cells often interact with their local environment through subcellular structures at a scale of tens to hundreds of nanometers. This study investigated whether topographic features fabricated at a similar scale would impact cellular functions by promoting the interaction between subcellular structures and nanomaterials. Crinkling of carbon nanotube films by solvent-induced swelling and shrinkage of substrate resulted in the formation of ridge features at the subcellular scale on both flat and three-dimensional substrates. Biological cells grown upon these crinkled CNT films had enhanced activity: neuronal cells grew to higher density and displayed greater cell polarization; exoelectrogenic micro-organisms transferred electrons more efficiently. The results indicate that crinkling of thin CNT films creates secondary mesoscale features that enhance attachment, growth, and electron transfer.

  View details for DOI 10.1021/nn504898p

  View details for PubMedID 25415858

• Large-Scale Production of Graphene Nanoribbons from Electrospun Polymers JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Liu, N., Kim, K., Hsu, P., Sokolov, A. N., Yap, F. L., Yuan, H., Xie, Y., Yan, H., Cui, Y., Hwang, H. Y., Bao, Z. 2014; 136 (49): 17284-17291

  Abstract

  Graphene nanoribbons (GNRs) are promising building blocks for high-performance electronics due to their high electron mobility and dimensionality-induced bandgap. Despite many past efforts, direct synthesis of GNRs with controlled dimensions and scalability remains challenging. Here we report the scalable synthesis of GNRs using electrospun polymer nanofiber templates. Palladium-incorporated poly(4-vinylphenol) nanofibers were prepared by electrospinning with controlled diameter and orientation. Highly graphitized GNRs as narrow as 10 nm were then synthesized from these templates by chemical vapor deposition. A transport gap can be observed in 30 nm-wide GNRs, enabling them to function as field-effect transistors at room temperature. Our results represent the first success on the scalable synthesis of highly graphitized GNRs from polymer templates. Furthermore, the generality of this method allows various polymers to be explored, which will lead to understanding of growth mechanism and rational control over crystallinity, feature size and bandgap to enable a new pathway for graphene electronics.

  View details for DOI 10.1021/ja509871n

  View details for PubMedID 25407608

• Charging-free electrochemical system for harvesting low-grade thermal energy PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Yang, Y., Lee, S. W., Ghasemi, H., Loomis, J., Li, X., Kraemer, D., Zheng, G., Cui, Y., Chen, G. 2014; 111 (48): 17011-17016

  Abstract

  Efficient and low-cost systems are needed to harvest the tremendous amount of energy stored in low-grade heat sources (<100 °C). Thermally regenerative electrochemical cycle (TREC) is an attractive approach which uses the temperature dependence of electrochemical cell voltage to construct a thermodynamic cycle for direct heat-to-electricity conversion. By varying temperature, an electrochemical cell is charged at a lower voltage than discharge, converting thermal energy to electricity. Most TREC systems still require external electricity for charging, which complicates system designs and limits their applications. Here, we demonstrate a charging-free TREC consisting of an inexpensive soluble Fe(CN)6(3-/4-) redox pair and solid Prussian blue particles as active materials for the two electrodes. In this system, the spontaneous directions of the full-cell reaction are opposite at low and high temperatures. Therefore, the two electrochemical processes at both low and high temperatures in a cycle are discharge. Heat-to-electricity conversion efficiency of 2.0% can be reached for the TREC operating between 20 and 60 °C. This charging-free TREC system may have potential application for harvesting low-grade heat from the environment, especially in remote areas.

  View details for DOI 10.1073/pnas.1415097111

  View details for PubMedID 25404325

• High Electrochemical Selectivity of Edge versus Terrace Sites in Two-Dimensional Layered MoS2 Materials NANO LETTERS Wang, H., Zhang, Q., Yao, H., Liang, Z., Lee, H., Hsu, P., Zheng, G., Cui, Y. 2014; 14 (12): 7138-7144

  Abstract

  Exploring the chemical reactivity of different atomic sites on crystal surface and controlling their exposures are important for catalysis and renewable energy storage. Here, we use two-dimensional layered molybdenum disulfide (MoS2) to demonstrate the electrochemical selectivity of edge versus terrace sites for Li-S batteries and hydrogen evolution reaction (HER). Lithium sulfide (Li2S) nanoparticles decorates along the edges of the MoS2 nanosheet versus terrace, confirming the strong binding energies between Li2S and the edge sites and guiding the improved electrode design for Li-S batteries. We also provided clear comparison of HER activity between edge and terrace sites of MoS2 beyond the previous theoretical prediction and experimental proof.

  View details for DOI 10.1021/nl503730c

  View details for PubMedID 25372985

• Optical transmission enhacement through chemically tuned two-dimensional bismuth chalcogenide nanoplates NATURE COMMUNICATIONS Yao, J., Koski, K. J., Luo, W., Cha, J. J., Hu, L., Kong, D., Narasimhan, V. K., Huo, K., Cui, Y. 2014; 5

  Abstract

  Layer-structured two-dimensional nanomaterials are a family of materials with strong covalent bonding within layers and weak van der Waals interaction between layers, whose vertical thickness can be thinned down to few nanometer and even single atomic layer. Bismuth chalcogenides are examples of such two-dimensional materials. Here, we present our discovery of significant enhancement of light transmission through thin nanoplates of layered bismuth chalcogenides by intercalation of copper atoms, which is on the contrary to most bulk materials in which doping reduces the light transmission. This surprising behaviour results from two mechanisms: chemical tuning effect of substantial reduction of material absorption after intercalation and nanophotonic effect of zero-wave anti-reflection unique to ultra-small thickness of nanoplates. We demonstrate that the synergy of these two effects in two-dimensional nanostructures can be exploited for various optoelectronic applications including transparent electrode. The intercalation mechanism allows potential dynamic tuning capability.

  View details for DOI 10.1038/ncomms6670

  View details for Web of Science ID 000346177300001

  View details for PubMedID 25430612

• Bifacial solar cell with SnS absorber by vapor transport deposition APPLIED PHYSICS LETTERS Wangperawong, A., Hsu, P., Yee, Y., Herron, S. M., Clemens, B. M., Cui, Y., Bent, S. F. 2014; 105 (17)

  View details for DOI 10.1063/1.4898092

  View details for Web of Science ID 000344588600079

• Ultrathin two-dimensional atomic crystals as stable interfacial layer for improvement of lithium metal anode. Nano letters Yan, K., Lee, H., Gao, T., Zheng, G., Yao, H., Wang, H., Lu, Z., Zhou, Y., Liang, Z., Liu, Z., Chu, S., Cui, Y. 2014; 14 (10): 6016-6022

  Abstract

  Stable cycling of lithium metal anode is challenging due to the dendritic lithium formation and high chemical reactivity of lithium with electrolyte and nearly all the materials. Here, we demonstrate a promising novel electrode design by growing two-dimensional (2D) atomic crystal layers including hexagonal boron nitride (h-BN) and graphene directly on Cu metal current collectors. Lithium ions were able to penetrate through the point and line defects of the 2D layers during the electrochemical deposition, leading to sandwiched lithium metal between ultrathin 2D layers and Cu. The 2D layers afford an excellent interfacial protection of Li metal due to their remarkable chemical stability as well as mechanical strength and flexibility, resulting from the strong intralayer bonds and ultrathin thickness. Smooth Li metal deposition without dendritic and mossy Li formation was realized. We showed stable cycling over 50 cycles with Coulombic efficiency ∼97% in organic carbonate electrolyte with current density and areal capacity up to the practical value of 2.0 mA/cm(2)and 5.0 mAh/cm(2), respectively, which is a significant improvement over the unprotected electrodes in the same electrolyte.

  View details for DOI 10.1021/nl503125u

  View details for PubMedID 25166749

• Static electricity powered copper oxide nanowire microbicidal electroporation for water disinfection. Nano letters Liu, C., Xie, X., Zhao, W., Yao, J., Kong, D., Boehm, A. B., Cui, Y. 2014; 14 (10): 5603-5608

  Abstract

  Safe water scarcity occurs mostly in developing regions that also suffer from energy shortages and infrastructure deficiencies. Low-cost and energy-efficient water disinfection methods have the potential to make great impacts on people in these regions. At the present time, most water disinfection methods being promoted to households in developing countries are aqueous chemical-reaction-based or filtration-based. Incorporating nanomaterials into these existing disinfection methods could improve the performance; however, the high cost of material synthesis and recovery as well as fouling and slow treatment speed is still limiting their application. Here, we demonstrate a novel flow device that enables fast water disinfection using one-dimensional copper oxide nanowire (CuONW) assisted electroporation powered by static electricity. Electroporation relies on a strong electric field to break down microorganism membranes and only consumes a very small amount of energy. Static electricity as the power source can be generated by an individual person's motion in a facile and low-cost manner, which ensures its application anywhere in the world. The CuONWs used were synthesized through a scalable one-step air oxidation of low-cost copper mesh. With a single filtration, we achieved complete disinfection of bacteria and viruses in both raw tap and lake water with a high flow rate of 3000 L/(h·m(2)), equivalent to only 1 s of contact time. Copper leaching from the nanowire mesh was minimal.

  View details for DOI 10.1021/nl5020958

  View details for PubMedID 25247233

• Ultrathin Two-Dimensional Atomic Crystals as Stable Interfacial Layer for Improvement of Lithium Metal Anode NANO LETTERS Yan, K., Lee, H., Gao, T., Zheng, G., Yao, H., Wang, H., Lu, Z., Zhou, Y., Liang, Z., Liu, Z., Chu, S., Cui, Y. 2014; 14 (10): 6016-6022

  Abstract

  Stable cycling of lithium metal anode is challenging due to the dendritic lithium formation and high chemical reactivity of lithium with electrolyte and nearly all the materials. Here, we demonstrate a promising novel electrode design by growing two-dimensional (2D) atomic crystal layers including hexagonal boron nitride (h-BN) and graphene directly on Cu metal current collectors. Lithium ions were able to penetrate through the point and line defects of the 2D layers during the electrochemical deposition, leading to sandwiched lithium metal between ultrathin 2D layers and Cu. The 2D layers afford an excellent interfacial protection of Li metal due to their remarkable chemical stability as well as mechanical strength and flexibility, resulting from the strong intralayer bonds and ultrathin thickness. Smooth Li metal deposition without dendritic and mossy Li formation was realized. We showed stable cycling over 50 cycles with Coulombic efficiency ∼97% in organic carbonate electrolyte with current density and areal capacity up to the practical value of 2.0 mA/cm(2)and 5.0 mAh/cm(2), respectively, which is a significant improvement over the unprotected electrodes in the same electrolyte.

  View details for DOI 10.1021/nl503125u

  View details for Web of Science ID 000343016400082

• Generation and electric control of spin-valley-coupled circular photogalvanic current in WSe2. Nature nanotechnology Yuan, H., Wang, X., Lian, B., Zhang, H., Fang, X., Shen, B., Xu, G., Xu, Y., Zhang, S., Hwang, H. Y., Cui, Y. 2014; 9 (10): 851-857

  Abstract

  The valley degree of freedom in layered transition-metal dichalcogenides provides an opportunity to extend the functionalities of spintronics and valleytronics devices. The achievement of spin-coupled valley polarization induced by the non-equilibrium charge-carrier imbalance between two degenerate and inequivalent valleys has been demonstrated theoretically and by optical experiments. However, the generation of a valley and spin current with the valley polarization in transition-metal dichalcogenides remains elusive. Here we demonstrate a spin-coupled valley photocurrent, within an electric-double-layer transistor based on WSe2, whose direction and magnitude depend on the degree of circular polarization of the incident radiation and can be further modulated with an external electric field. This room-temperature generation and electric control of a valley and spin photocurrent provides a new property of electrons in transition-metal dichalcogenide systems, and thereby enables additional degrees of control for quantum-confined spintronic devices.

  View details for DOI 10.1038/nnano.2014.183

  View details for PubMedID 25194947

• Manganese hexacyanomanganate open framework as a high-capacity positive electrode material for sodium-ion batteries NATURE COMMUNICATIONS Lee, H., Wang, R. Y., Pasta, M., Lee, S. W., Liu, N., Cui, Y. 2014; 5

  Abstract

  Potential applications of sodium-ion batteries in grid-scale energy storage, portable electronics and electric vehicles have revitalized research interest in these batteries. However, the performance of sodium-ion electrode materials has not been competitive with that of lithium-ion electrode materials. Here we present sodium manganese hexacyanomanganate (Na2MnII[MnII(CN)6]), an open-framework crystal structure material, as a viable positive electrode for sodium-ion batteries. We demonstrate a high discharge capacity of 209 mAh g(-1) at C/5 (40 mA g(-1)) and excellent capacity retention at high rates in a propylene carbonate electrolyte. We provide chemical and structural evidence for the unprecedented storage of 50% more sodium cations than previously thought possible during electrochemical cycling. These results represent a step forward in the development of sodium-ion batteries.

  View details for DOI 10.1038/ncomms6280

  View details for Web of Science ID 000343985900004

• Static Electricity Powered Copper Oxide Nanowire Microbicidal Electroporation for Water Disinfection NANO LETTERS Liu, C., Xie, X., Zhao, W., Yao, J., Kong, D., Boehm, A. B., Cui, Y. 2014; 14 (10): 5603-5608

  Abstract

  Safe water scarcity occurs mostly in developing regions that also suffer from energy shortages and infrastructure deficiencies. Low-cost and energy-efficient water disinfection methods have the potential to make great impacts on people in these regions. At the present time, most water disinfection methods being promoted to households in developing countries are aqueous chemical-reaction-based or filtration-based. Incorporating nanomaterials into these existing disinfection methods could improve the performance; however, the high cost of material synthesis and recovery as well as fouling and slow treatment speed is still limiting their application. Here, we demonstrate a novel flow device that enables fast water disinfection using one-dimensional copper oxide nanowire (CuONW) assisted electroporation powered by static electricity. Electroporation relies on a strong electric field to break down microorganism membranes and only consumes a very small amount of energy. Static electricity as the power source can be generated by an individual person's motion in a facile and low-cost manner, which ensures its application anywhere in the world. The CuONWs used were synthesized through a scalable one-step air oxidation of low-cost copper mesh. With a single filtration, we achieved complete disinfection of bacteria and viruses in both raw tap and lake water with a high flow rate of 3000 L/(h·m(2)), equivalent to only 1 s of contact time. Copper leaching from the nanowire mesh was minimal.

  View details for DOI 10.1021/nl5020958

  View details for Web of Science ID 000343016400019

• Dry-air-stable lithium silicide-lithium oxide core-shell nanoparticles as high-capacity prelithiation reagents NATURE COMMUNICATIONS Zhao, J., Lu, Z., Liu, N., Lee, H., McDowell, M. T., Cui, Y. 2014; 5

  Abstract

  Rapid progress has been made in realizing battery electrode materials with high capacity and long-term cyclability in the past decade. However, low first-cycle Coulombic efficiency as a result of the formation of a solid electrolyte interphase and Li trapping at the anodes, remains unresolved. Here we report LixSi-Li2O core-shell nanoparticles as an excellent prelithiation reagent with high specific capacity to compensate the first-cycle capacity loss. These nanoparticles are produced via a one-step thermal alloying process. LixSi-Li2O core-shell nanoparticles are processible in a slurry and exhibit high capacity under dry-air conditions with the protection of a Li2O passivation shell, indicating that these nanoparticles are potentially compatible with industrial battery fabrication processes. Both Si and graphite anodes are successfully prelithiated with these nanoparticles to achieve high first-cycle Coulombic efficiencies of 94% to >100%. The LixSi-Li2O core-shell nanoparticles enable the practical implementation of high-performance electrode materials in lithium-ion batteries.

  View details for DOI 10.1038/ncomms6088

  View details for Web of Science ID 000343978000005

• Two-dimensional layered transition metal disulphides for effective encapsulation of high-capacity lithium sulphide cathodes NATURE COMMUNICATIONS Seh, Z. W., Yu, J. H., Li, W., Hsu, P., Wang, H., Sun, Y., Yao, H., Zhang, Q., Cui, Y. 2014; 5

  Abstract

  Fully lithiated lithium sulphide (Li2S) is currently being explored as a promising cathode material for emerging energy storage applications. Like their sulphur counterparts, Li2S cathodes require effective encapsulation to reduce the dissolution of intermediate lithium polysulphide (Li2Sn, n=4-8) species into the electrolyte. Here we report, the encapsulation of Li2S cathodes using two-dimensional layered transition metal disulphides that possess a combination of high conductivity and strong binding with Li2S/Li2Sn species. In particular, using titanium disulphide as an encapsulation material, we demonstrate a high specific capacity of 503 mAh g(-1)(Li2S) under high C-rate conditions (4C) as well as high areal capacity of 3.0 mAh cm(-2) under high mass-loading conditions (5.3 mg(Li2S) cm(-2)). This work opens up the new prospect of using transition metal disulphides instead of conventional carbon-based materials for effective encapsulation of high-capacity electrode materials.

  View details for DOI 10.1038/ncomms6017

  View details for Web of Science ID 000342985900004

• Formation of stable phosphorus-carbon bond for enhanced performance in black phosphorus nanoparticle-graphite composite battery anodes. Nano letters Sun, J., Zheng, G., Lee, H., Liu, N., Wang, H., Yao, H., Yang, W., Cui, Y. 2014; 14 (8): 4573-4580

  Abstract

  High specific capacity battery electrode materials have attracted great research attention. Phosphorus as a low-cost abundant material has a high theoretical specific capacity of 2596 mAh/g with most of its capacity at the discharge potential range of 0.4-1.2 V, suitable as anodes. Although numerous research progress have shown other high capacity anodes such as Si, Ge, Sn, and SnO2, there are only a few studies on phosphorus anodes despite its high theoretical capacity. Successful applications of phosphorus anodes have been impeded by rapid capacity fading, mainly caused by large volume change (around 300%) upon lithiation and thus loss of electrical contact. Using the conducting allotrope of phosphorus, "black phosphorus" as starting materials, here we fabricated composites of black phosphorus nanoparticle-graphite by mechanochemical reaction in a high energy mechanical milling process. This process produces phosphorus-carbon bonds, which are stable during lithium insertion/extraction, maintaining excellent electrical connection between phosphorus and carbon. We demonstrated high initial discharge capacity of 2786 mAh·g(-1) at 0.2 C and an excellent cycle life of 100 cycles with 80% capacity retention. High specific discharge capacities are maintained at fast C rates (2270, 1750, 1500, and 1240 mAh·g(-1) at C/5, 1, 2, and 4.5 C, respectively).

  View details for DOI 10.1021/nl501617j

  View details for PubMedID 25019417

• Interconnected hollow carbon nanospheres for stable lithium metal anodes. Nature nanotechnology Zheng, G., Lee, S. W., Liang, Z., Lee, H., Yan, K., Yao, H., Wang, H., Li, W., Chu, S., Cui, Y. 2014; 9 (8): 618-623

  Abstract

  For future applications in portable electronics, electric vehicles and grid storage, batteries with higher energy storage density than existing lithium ion batteries need to be developed. Recent efforts in this direction have focused on high-capacity electrode materials such as lithium metal, silicon and tin as anodes, and sulphur and oxygen as cathodes. Lithium metal would be the optimal choice as an anode material, because it has the highest specific capacity (3,860 mAh g(-1)) and the lowest anode potential of all. However, the lithium anode forms dendritic and mossy metal deposits, leading to serious safety concerns and low Coulombic efficiency during charge/discharge cycles. Although advanced characterization techniques have helped shed light on the lithium growth process, effective strategies to improve lithium metal anode cycling remain elusive. Here, we show that coating the lithium metal anode with a monolayer of interconnected amorphous hollow carbon nanospheres helps isolate the lithium metal depositions and facilitates the formation of a stable solid electrolyte interphase. We show that lithium dendrites do not form up to a practical current density of 1 mA cm(-2). The Coulombic efficiency improves to ∼99% for more than 150 cycles. This is significantly better than the bare unmodified samples, which usually show rapid Coulombic efficiency decay in fewer than 100 cycles. Our results indicate that nanoscale interfacial engineering could be a promising strategy to tackle the intrinsic problems of lithium metal anodes.

  View details for DOI 10.1038/nnano.2014.152

  View details for PubMedID 25064396

• Electrolessly deposited electrospun metal nanowire transparent electrodes. Journal of the American Chemical Society Hsu, P., Kong, D., Wang, S., Wang, H., Welch, A. J., Wu, H., Cui, Y. 2014; 136 (30): 10593-10596

  Abstract

  Metal nanowire (MNW) transparent electrodes have been widely developed for their promising sheet resistance (Rs)-transmittance (T) performance, excellent mechanical flexibility, and facile synthesis. How to lower the junction resistance without compromising optical transmittance has become the key issue in enhancing their performance. Here we combine electrospinning and electroless deposition to synthesize interconnected, ultralong MNW networks. For both silver and copper nanowire networks, the Rs and T values reach around 10 Ω/sq and 90%, respectively. This process is scalable and takes place at ambient temperature and pressure, which opens new opportunities for flexible electronics and roll-to-roll large-scale manufacturing.

  View details for DOI 10.1021/ja505741e

  View details for PubMedID 25019606

• Metamaterial mirrors in optoelectronic devices. Nature nanotechnology Esfandyarpour, M., Garnett, E. C., Cui, Y., McGehee, M. D., Brongersma, M. L. 2014; 9 (7): 542-547

  Abstract

  The phase reversal that occurs when light is reflected from a metallic mirror produces a standing wave with reduced intensity near the reflective surface. This effect is highly undesirable in optoelectronic devices that use metal films as both electrical contacts and optical mirrors, because it dictates a minimum spacing between the metal and the underlying active semiconductor layers, therefore posing a fundamental limit to the overall thickness of the device. Here, we show that this challenge can be circumvented by using a metamaterial mirror whose reflection phase is tunable from that of a perfect electric mirror (φ = π) to that of a perfect magnetic mirror (φ = 0). This tunability in reflection phase can also be exploited to optimize the standing wave profile in planar devices to maximize light-matter interaction. Specifically, we show that light absorption and photocurrent generation in a sub-100 nm active semiconductor layer of a model solar cell can be enhanced by ∼20% over a broad spectral band.

  View details for DOI 10.1038/nnano.2014.117

  View details for PubMedID 24952475

• Electrochemical Tuning of MoS2 Nanoparticles on Three-Dimensional Substrate for Efficient Hydrogen Evolution. ACS nano Wang, H., Lu, Z., Kong, D., Sun, J., Hymel, T. M., Cui, Y. 2014; 8 (5): 4940-4947

  Abstract

  Molybdenum disulfide (MoS2) with the two-dimensional layered structure has been widely studied as an advanced catalyst for hydrogen evolution reaction (HER). Intercalating guest species into the van der Waals gaps of MoS2 has been demonstrated as an effective approach to tune the electronic structure and consequently improve the HER catalytic activity. In this work, by constructing nanostructured MoS2 particles with largely exposed edge sites on the three-dimensional substrate and subsequently conducting Li electrochemical intercalation and exfoliation processes, an ultrahigh HER performance with 200 mA/cm(2) cathodic current density at only 200 mV overpotential is achieved. We propose that both the high surface area nanostructure and the 2H semiconducting to 1T metallic phase transition of MoS2 are responsible for the outstanding catalytic activity. Electrochemical stability test further confirms the long-term operation of the catalyst.

  View details for DOI 10.1021/nn500959v

  View details for PubMedID 24716529

• Sulfur cathodes with hydrogen reduced titanium dioxide inverse opal structure. ACS nano Liang, Z., Zheng, G., Li, W., Seh, Z. W., Yao, H., Yan, K., Kong, D., Cui, Y. 2014; 8 (5): 5249-5256

  Abstract

  Sulfur is a cathode material for lithium-ion batteries with a high specific capacity of 1675 mAh/g. The rapid capacity fading, however, presents a significant challenge for the practical application of sulfur cathodes. Two major approaches that have been developed to improve the sulfur cathode performance include (a) fabricating nanostructured conductive matrix to physically encapsulate sulfur and (b) engineering chemical modification to enhance binding with polysulfides and, thus, to reduce their dissolution. Here, we report a three-dimensional (3D) electrode structure to achieve both sulfur physical encapsulation and polysulfides binding simultaneously. The electrode is based on hydrogen reduced TiO2 with an inverse opal structure that is highly conductive and robust toward electrochemical cycling. The relatively enclosed 3D structure provides an ideal architecture for sulfur and polysulfides confinement. The openings at the top surface allow sulfur infusion into the inverse opal structure. In addition, chemical tuning of the TiO2 composition through hydrogen reduction was shown to enhance the specific capacity and cyclability of the cathode. With such TiO2 encapsulated sulfur structure, the sulfur cathode could deliver a high specific capacity of ∼1100 mAh/g in the beginning, with a reversible capacity of ∼890 mAh/g after 200 cycles of charge/discharge at a C/5 rate. The Coulombic efficiency was also maintained at around 99.5% during cycling. The results showed that inverse opal structure of hydrogen reduced TiO2 represents an effective strategy in improving lithium sulfur batteries performance.

  View details for DOI 10.1021/nn501308m

  View details for PubMedID 24766547

• One-dimensional helical transport in topological insulator nanowire interferometers. Nano letters Hong, S. S., Zhang, Y., Cha, J. J., Qi, X., Cui, Y. 2014; 14 (5): 2815-2821

  Abstract

  The discovery of three-dimensional (3D) topological insulators opens a gateway to generate unusual phases and particles made of the helical surface electrons, proposing new applications using unusual spin nature. Demonstration of the helical electron transport is a crucial step to both physics and device applications of topological insulators. Topological insulator nanowires, of which spin-textured surface electrons form 1D band manipulated by enclosed magnetic flux, offer a unique nanoscale platform to realize quantum transport of spin-momentum locking nature. Here, we report an observation of a topologically protected 1D mode of surface electrons in topological insulator nanowires existing at only two values of half magnetic quantum flux (±h/2e) due to a spin Berry's phase (π). The helical 1D mode is robust against disorder but fragile against a perpendicular magnetic field breaking-time-reversal symmetry. This result demonstrates a device with robust and easily accessible 1D helical electronic states from 3D topological insulators, a unique nanoscale electronic system to study topological phenomena.

  View details for DOI 10.1021/nl500822g

  View details for PubMedID 24679125

• Light management for photovoltaics using high-index nanostructures NATURE MATERIALS Brongersma, M. L., Cui, Y., Fan, S. 2014; 13 (5): 451-460

  Abstract

  High-performance photovoltaic cells use semiconductors to convert sunlight into clean electrical power, and transparent dielectrics or conductive oxides as antireflection coatings. A common feature of these materials is their high refractive index. Whereas high-index materials in a planar form tend to produce a strong, undesired reflection of sunlight, high-index nanostructures afford new ways to manipulate light at a subwavelength scale. For example, nanoscale wires, particles and voids support strong optical resonances that can enhance and effectively control light absorption and scattering processes. As such, they provide ideal building blocks for novel, broadband antireflection coatings, light-trapping layers and super-absorbing films. This Review discusses some of the recent developments in the design and implementation of such photonic elements in thin-film photovoltaic cells.

  View details for DOI 10.1038/NMAT3921

  View details for Web of Science ID 000334845600014

  View details for PubMedID 24751773

• CoSe2 Nanoparticles Grown on Carbon Fiber Paper: An Efficient and Stable Electrocatalyst for Hydrogen Evolution Reaction. Journal of the American Chemical Society Kong, D., Wang, H., Lu, Z., Cui, Y. 2014; 136 (13): 4897-4900

  Abstract

  Development of a non-noble-metal hydrogen-producing catalyst is essential to the development of solar water-splitting devices. Improving both the activity and the stability of the catalyst remains a key challenge. In this Communication, we describe a two-step reaction for preparing three-dimensional electrodes composed of CoSe2 nanoparticles grown on carbon fiber paper. The electrode exhibits excellent catalytic activity for a hydrogen evolution reaction in an acidic electrolyte (100 mA/cm(2) at an overpotential of ∼180 mV). Stability tests though long-term potential cycles and extended electrolysis confirm the exceptional durability of the catalyst. This development offers an attractive catalyst material for large-scale water-splitting technology.

  View details for DOI 10.1021/ja501497n

  View details for PubMedID 24628572

• Tuning the threshold voltage of carbon nanotube transistors by n-type molecular doping for robust and flexible complementary circuits. Proceedings of the National Academy of Sciences of the United States of America Wang, H., Wei, P., Li, Y., Han, J., Lee, H. R., Naab, B. D., Liu, N., Wang, C., Adijanto, E., Tee, B. C., Morishita, S., Li, Q., Gao, Y., Cui, Y., Bao, Z. 2014; 111 (13): 4776-4781

  Abstract

  Tuning the threshold voltage of a transistor is crucial for realizing robust digital circuits. For silicon transistors, the threshold voltage can be accurately controlled by doping. However, it remains challenging to tune the threshold voltage of single-wall nanotube (SWNT) thin-film transistors. Here, we report a facile method to controllably n-dope SWNTs using 1H-benzoimidazole derivatives processed via either solution coating or vacuum deposition. The threshold voltages of our polythiophene-sorted SWNT thin-film transistors can be tuned accurately and continuously over a wide range. Photoelectron spectroscopy measurements confirmed that the SWNT Fermi level shifted to the conduction band edge with increasing doping concentration. Using this doping approach, we proceeded to fabricate SWNT complementary inverters by inkjet printing of the dopants. We observed an unprecedented noise margin of 28 V at VDD = 80 V (70% of 1/2VDD) and a gain of 85. Additionally, robust SWNT complementary metal-oxide-semiconductor inverter (noise margin 72% of 1/2VDD) and logic gates with rail-to-rail output voltage swing and subnanowatt power consumption were fabricated onto a highly flexible substrate.

  View details for DOI 10.1073/pnas.1320045111

  View details for PubMedID 24639537

• A pomegranate-inspired nanoscale design for large-volume-change lithium battery anodes. Nature nanotechnology Liu, N., Lu, Z., Zhao, J., McDowell, M. T., Lee, H., Zhao, W., Cui, Y. 2014; 9 (3): 187-192

  Abstract

  Silicon is an attractive material for anodes in energy storage devices, because it has ten times the theoretical capacity of its state-of-the-art carbonaceous counterpart. Silicon anodes can be used both in traditional lithium-ion batteries and in more recent Li-O2 and Li-S batteries as a replacement for the dendrite-forming lithium metal anodes. The main challenges associated with silicon anodes are structural degradation and instability of the solid-electrolyte interphase caused by the large volume change (∼300%) during cycling, the occurrence of side reactions with the electrolyte, and the low volumetric capacity when the material size is reduced to a nanometre scale. Here, we propose a hierarchical structured silicon anode that tackles all three of these problems. Our design is inspired by the structure of a pomegranate, where single silicon nanoparticles are encapsulated by a conductive carbon layer that leaves enough room for expansion and contraction following lithiation and delithiation. An ensemble of these hybrid nanoparticles is then encapsulated by a thicker carbon layer in micrometre-size pouches to act as an electrolyte barrier. As a result of this hierarchical arrangement, the solid-electrolyte interphase remains stable and spatially confined, resulting in superior cyclability (97% capacity retention after 1,000 cycles). In addition, the microstructures lower the electrode-electrolyte contact area, resulting in high Coulombic efficiency (99.87%) and volumetric capacity (1,270 mAh cm(-3)), and the cycling remains stable even when the areal capacity is increased to the level of commercial lithium-ion batteries (3.7 mAh cm(-2)).

  View details for DOI 10.1038/nnano.2014.6

  View details for PubMedID 24531496

• Facile synthesis of Li2S-polypyrrole composite structures for high-performance Li2S cathodes Energy and Environmental Science Seh, Z., W., Wang, H., Hsu, P., C., Zhang, Q., Li, W., Zheng, G., Cui, Y. 2014

  View details for DOI 10.1039/C3EE43395A

• An electrochemical system for efficiently harvesting low-grade heat energy. Nature communications Lee, S. W., Yang, Y., Lee, H., Ghasemi, H., Kraemer, D., Chen, G., Cui, Y. 2014; 5: 3942-?

  Abstract

  Efficient and low-cost thermal energy-harvesting systems are needed to utilize the tremendous low-grade heat sources. Although thermoelectric devices are attractive, its efficiency is limited by the relatively low figure-of-merit and low-temperature differential. An alternative approach is to explore thermodynamic cycles. Thermogalvanic effect, the dependence of electrode potential on temperature, can construct such cycles. In one cycle, an electrochemical cell is charged at a temperature and then discharged at a different temperature with higher cell voltage, thereby converting heat to electricity. Here we report an electrochemical system using a copper hexacyanoferrate cathode and a Cu/Cu(2+) anode to convert heat into electricity. The electrode materials have low polarization, high charge capacity, moderate temperature coefficients and low specific heat. These features lead to a high heat-to-electricity energy conversion efficiency of 5.7% when cycled between 10 and 60 °C, opening a promising way to utilize low-grade heat.

  View details for DOI 10.1038/ncomms4942

  View details for PubMedID 24845707

• Dry-air-stable lithium silicide-lithium oxide core-shell nanoparticles as high-capacity prelithiation reagents. Nature communications Zhao, J., Lu, Z., Liu, N., Lee, H., McDowell, M. T., Cui, Y. 2014; 5: 5088-?

  Abstract

  Rapid progress has been made in realizing battery electrode materials with high capacity and long-term cyclability in the past decade. However, low first-cycle Coulombic efficiency as a result of the formation of a solid electrolyte interphase and Li trapping at the anodes, remains unresolved. Here we report LixSi-Li2O core-shell nanoparticles as an excellent prelithiation reagent with high specific capacity to compensate the first-cycle capacity loss. These nanoparticles are produced via a one-step thermal alloying process. LixSi-Li2O core-shell nanoparticles are processible in a slurry and exhibit high capacity under dry-air conditions with the protection of a Li2O passivation shell, indicating that these nanoparticles are potentially compatible with industrial battery fabrication processes. Both Si and graphite anodes are successfully prelithiated with these nanoparticles to achieve high first-cycle Coulombic efficiencies of 94% to >100%. The LixSi-Li2O core-shell nanoparticles enable the practical implementation of high-performance electrode materials in lithium-ion batteries.

  View details for DOI 10.1038/ncomms6088

  View details for PubMedID 25277107

• Manganese hexacyanomanganate open framework as a high-capacity positive electrode material for sodium-ion batteries. Nature communications Lee, H., Wang, R. Y., Pasta, M., Woo Lee, S., Liu, N., Cui, Y. 2014; 5: 5280-?

  Abstract

  Potential applications of sodium-ion batteries in grid-scale energy storage, portable electronics and electric vehicles have revitalized research interest in these batteries. However, the performance of sodium-ion electrode materials has not been competitive with that of lithium-ion electrode materials. Here we present sodium manganese hexacyanomanganate (Na2MnII[MnII(CN)6]), an open-framework crystal structure material, as a viable positive electrode for sodium-ion batteries. We demonstrate a high discharge capacity of 209 mAh g(-1) at C/5 (40 mA g(-1)) and excellent capacity retention at high rates in a propylene carbonate electrolyte. We provide chemical and structural evidence for the unprecedented storage of 50% more sodium cations than previously thought possible during electrochemical cycling. These results represent a step forward in the development of sodium-ion batteries.

  View details for DOI 10.1038/ncomms6280

  View details for PubMedID 25311066

• Full open-framework batteries for stationary energy storage. Nature communications Pasta, M., Wessells, C. D., Liu, N., Nelson, J., McDowell, M. T., Huggins, R. A., Toney, M. F., Cui, Y. 2014; 5: 3007-?

  Abstract

  New types of energy storage are needed in conjunction with the deployment of renewable energy sources and their integration with the electrical grid. We have recently introduced a family of cathodes involving the reversible insertion of cations into materials with the Prussian Blue open-framework crystal structure. Here we report a newly developed manganese hexacyanomanganate open-framework anode that has the same crystal structure. By combining it with the previously reported copper hexacyanoferrate cathode we demonstrate a safe, fast, inexpensive, long-cycle life aqueous electrolyte battery, which involves the insertion of sodium ions. This high rate, high efficiency cell shows a 96.7% round trip energy efficiency when cycled at a 5C rate and an 84.2% energy efficiency at a 50C rate. There is no measurable capacity loss after 1,000 deep-discharge cycles. Bulk quantities of the electrode materials can be produced by a room temperature chemical synthesis from earth-abundant precursors.

  View details for DOI 10.1038/ncomms4007

  View details for PubMedID 24389854

• Improving lithium-sulphur batteries through spatial control of sulphur species deposition on a hybrid electrode surface. Nature communications Yao, H., Zheng, G., Hsu, P., Kong, D., Cha, J. J., Li, W., Seh, Z. W., McDowell, M. T., Yan, K., Liang, Z., Narasimhan, V. K., Cui, Y. 2014; 5: 3943-?

  Abstract

  Lithium-sulphur batteries are attractive owing to their high theoretical energy density and reasonable kinetics. Despite the success of trapping soluble polysulphides in a matrix with high surface area, spatial control of solid-state sulphur and lithium sulphide species deposition as a critical aspect has not been demonstrated. Herein, we show a clear visual evidence that these solid species deposit preferentially onto tin-doped indium oxide instead of carbon during electrochemical charge/discharge of soluble polysuphides. To incorporate this concept of spatial control into more practical battery electrodes, we further prepare carbon nanofibers with tin-doped indium oxide nanoparticles decorating the surface as hybrid three-dimensional electrodes to maximize the number of deposition sites. With 12.5 μl of 5 M Li2S8 as the catholyte and a rate of C/5, we can reach the theoretical limit of Li2S8 capacity ~\n1,470 mAh g(-1) (sulphur weight) under the loading of hybrid electrode only at 4.3 mg cm(-2).

  View details for DOI 10.1038/ncomms4943

  View details for PubMedID 24862162

• Electrochemical tuning of layered lithium transition metal oxides for improvement of oxygen evolution reaction. Nature communications Lu, Z., Wang, H., Kong, D., Yan, K., Hsu, P., Zheng, G., Yao, H., Liang, Z., Sun, X., Cui, Y. 2014; 5: 4345-?

  Abstract

  Searching for low-cost and efficient catalysts for the oxygen evolution reaction has been actively pursued owing to its importance in clean energy generation and storage. While developing new catalysts is important, tuning the electronic structure of existing catalysts over a wide electrochemical potential range can also offer a new direction. Here we demonstrate a method for electrochemical lithium tuning of catalytic materials in organic electrolyte for subsequent enhancement of the catalytic activity in aqueous solution. By continuously extracting lithium ions out of LiCoO2, a popular cathode material in lithium ion batteries, to Li0.5CoO2 in organic electrolyte, the catalytic activity is significantly improved. This enhancement is ascribed to the unique electronic structure after the delithiation process. The general efficacy of this methodology is demonstrated in several mixed metal oxides with similar improvements. The electrochemically delithiated LiCo0.33Ni0.33Fe0.33O2 exhibits a notable performance, better than the benchmark iridium/carbon catalyst.

  View details for DOI 10.1038/ncomms5345

  View details for PubMedID 24993836

• Two-dimensional layered transition metal disulphides for effective encapsulation of high-capacity lithium sulphide cathodes. Nature communications Seh, Z. W., Yu, J. H., Li, W., Hsu, P., Wang, H., Sun, Y., Yao, H., Zhang, Q., Cui, Y. 2014; 5: 5017-?

  Abstract

  Fully lithiated lithium sulphide (Li2S) is currently being explored as a promising cathode material for emerging energy storage applications. Like their sulphur counterparts, Li2S cathodes require effective encapsulation to reduce the dissolution of intermediate lithium polysulphide (Li2Sn, n=4-8) species into the electrolyte. Here we report, the encapsulation of Li2S cathodes using two-dimensional layered transition metal disulphides that possess a combination of high conductivity and strong binding with Li2S/Li2Sn species. In particular, using titanium disulphide as an encapsulation material, we demonstrate a high specific capacity of 503 mAh g(-1)(Li2S) under high C-rate conditions (4C) as well as high areal capacity of 3.0 mAh cm(-2) under high mass-loading conditions (5.3 mg(Li2S) cm(-2)). This work opens up the new prospect of using transition metal disulphides instead of conventional carbon-based materials for effective encapsulation of high-capacity electrode materials.

  View details for DOI 10.1038/ncomms6017

  View details for PubMedID 25254637

• Improving battery safety by early detection of internal shorting with a bifunctional separator. Nature communications Wu, H., Zhuo, D., Kong, D., Cui, Y. 2014; 5: 5193-?

  Abstract

  Lithium-based rechargeable batteries have been widely used in portable electronics and show great promise for emerging applications in transportation and wind-solar-grid energy storage, although their safety remains a practical concern. Failures in the form of fire and explosion can be initiated by internal short circuits associated with lithium dendrite formation during cycling. Here we report a new strategy for improving safety by designing a smart battery that allows internal battery health to be monitored in situ. Specifically, we achieve early detection of lithium dendrites inside batteries through a bifunctional separator, which offers a third sensing terminal in addition to the cathode and anode. The sensing terminal provides unique signals in the form of a pronounced voltage change, indicating imminent penetration of dendrites through the separator. This detection mechanism is highly sensitive, accurate and activated well in advance of shorting and can be applied to many types of batteries for improved safety.

  View details for DOI 10.1038/ncomms6193

  View details for PubMedID 25308055

• A residue-free green synergistic antifungal nanotechnology for pesticide thiram by ZnO nanoparticles. Scientific reports Xue, J., Luo, Z., Li, P., Ding, Y., Cui, Y., Wu, Q. 2014; 4: 5408-?

  Abstract

  Here we reported a residue-free green nanotechnology which synergistically enhance the pesticides efficiency and successively eliminate its residue. We built up a composite antifungal system by a simple pre-treating and assembling procedure for investigating synergy. Investigations showed 0.25 g/L ZnO nanoparticles (NPs) with 0.01 g/L thiram could inhibit the fungal growth in a synergistic mode. More importantly, the 0.25 g/L ZnO NPs completely degraded 0.01 g/L thiram under simulated sunlight irradiation within 6 hours. It was demonstrated that the formation of ZnO-thiram antifungal system, electrostatic adsorption of ZnO NPs to fungi cells and the cellular internalization of ZnO-thiram composites played important roles in synergy. Oxidative stress test indicated ZnO-induced oxidative damage was enhanced by thiram that finally result in synergistic antifungal effect. By reducing the pesticides usage, this nanotechnology could control the plant disease economically, more significantly, the following photocatalytic degradation of pesticide greatly benefit the human social by avoiding negative influence of pesticide residue on public health and environment.

  View details for DOI 10.1038/srep05408

  View details for PubMedID 25023938

• Iridium oxide nanotube electrodes for sensitive and prolonged intracellular measurement of action potentials. Nature communications Lin, Z. C., Xie, C., Osakada, Y., Cui, Y., Cui, B. 2014; 5: 3206-?

  Abstract

  Intracellular recording of action potentials is important to understand electrically-excitable cells. Recently, vertical nanoelectrodes have been developed to achieve highly sensitive, minimally invasive and large-scale intracellular recording. It has been demonstrated that the vertical geometry is crucial for the enhanced signal detection. Here we develop nanoelectrodes of a new geometry, namely nanotubes of iridium oxide. When cardiomyocytes are cultured upon those nanotubes, the cell membrane not only wraps around the vertical tubes but also protrudes deep into the hollow centre. We show that this nanotube geometry enhances cell-electrode coupling and results in larger signals than solid nanoelectrodes. The nanotube electrodes also afford much longer intracellular access and are minimally invasive, making it possible to achieve stable recording up to an hour in a single session and more than 8 days of consecutive daily recording. This study suggests that the nanoelectrode performance can be significantly improved by optimizing the electrode geometry.

  View details for DOI 10.1038/ncomms4206

  View details for PubMedID 24487777

• Effect of the alkali insertion ion on the electrochemical properties of nickel hexacyanoferrate electrodes. Faraday discussions Lee, H., Pasta, M., Wang, R. Y., Ruffo, R., Cui, Y. 2014; 176: 69-81

  Abstract

  Nickel hexacyanoferrate (NiHCFe) is an attractive cathode material in both aqueous and organic electrolytes due to a low-cost synthesis using earth-abundant precursors and also due to its open framework, Prussian blue-like crystal structure that enables ultra-long cycle life, high energy efficiency, and high power capability. Herein, we explored the effect of different alkali ions on the insertion electrochemistry of NiHCFe in aqueous and propylene carbonate-based electrolytes. The large channel diameter of the structure offers fast solid-state diffusion of Li(+), Na(+), and K(+) ions in aqueous electrolytes. However, all alkali ions in organic electrolytes and Rb(+) and Cs(+) in aqueous electrolytes show a quasi-reversible electrochemical behavior that results in poor galvanostatic cycling performance. Kinetic regimes in aqueous electrolyte were also determined, highlighting the effect of the size of the alkali ion on the electrochemical properties.

  View details for DOI 10.1039/c4fd00147h

  View details for PubMedID 25406368

• Light Trapping in Photonic Crystals Conference on Thin Films for Solar and Energy Technology VI Wang, K. X., Yu, Z., Liu, V., Raman, A., Cui, Y., Fan, S. SPIE-INT SOC OPTICAL ENGINEERING. 2014

  View details for DOI 10.1117/12.2061160

  View details for Web of Science ID 000349362600014

• Full open-framework batteries for stationary energy storage Nature Communications Pasta, M., Wessells, C., D., Liu, N., Nelson, J., McDowell, M., T., Huggins, R., A., Cui, Y. 2014; 3007 (5)
• Two-dimensional chalcogenide nanoplates as tunable metamaterials via chemical intercalation. Nano letters Cha, J. J., Koski, K. J., Huang, K. C., Wang, K. X., Luo, W., Kong, D., Yu, Z., Fan, S., Brongersma, M. L., Cui, Y. 2013; 13 (12): 5913-5918

  Abstract

  New plasmonic materials with tunable properties are in great need for nanophotonics and metamaterials applications. Here we present two-dimensional layered, metal chalcogenides as tunable metamaterials that feature both dielectric photonic and plasmonic modes across a wide spectral range from the infrared to ultraviolet. The anisotropic layered structure allows intercalation of organic molecules and metal atoms at the van der Waals gap of the host chalcogenide, presenting a chemical route to create heterostructures with molecular and atomic precision for photonic and plasmonic applications. This marks a departure from a lithographic method to create metamaterials. Monochromated electron energy-loss spectroscopy in a scanning transmission electron microscope was used to first establish the presence of the dielectric photonic and plasmonic modes in M2E3 (M = Bi, Sb; E = Se, Te) nanoplates and to observe marked changes in these modes after chemical intercalation. We show that these modal properties can also be tuned effectively by more conventional methods such as thickness control and alloy composition of the nanoplates.

  View details for DOI 10.1021/nl402937g

  View details for PubMedID 24266743

• Electrochemical tuning of vertically aligned MoS2 nanofilms and its application in improving hydrogen evolution reaction PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Wang, H., Lu, Z., Xu, S., Kong, D., Cha, J. J., Zheng, G., Hsu, P., Yan, K., Bradshaw, D., Prinz, F. B., Cui, Y. 2013; 110 (49): 19701-19706

  Abstract

  The ability to intercalate guest species into the van der Waals gap of 2D layered materials affords the opportunity to engineer the electronic structures for a variety of applications. Here we demonstrate the continuous tuning of layer vertically aligned MoS2 nanofilms through electrochemical intercalation of Li(+) ions. By scanning the Li intercalation potential from high to low, we have gained control of multiple important material properties in a continuous manner, including tuning the oxidation state of Mo, the transition of semiconducting 2H to metallic 1T phase, and expanding the van der Waals gap until exfoliation. Using such nanofilms after different degree of Li intercalation, we show the significant improvement of the hydrogen evolution reaction activity. A strong correlation between such tunable material properties and hydrogen evolution reaction activity is established. This work provides an intriguing and effective approach on tuning electronic structures for optimizing the catalytic activity.

  View details for DOI 10.1073/pnas.1316792110

  View details for PubMedID 24248362

• First-row transition metal dichalcogenide catalysts for hydrogen evolution reaction ENERGY & ENVIRONMENTAL SCIENCE Kong, D., Cha, J. J., Wang, H., Lee, H. R., Cui, Y. 2013; 6 (12): 3553-3558

  View details for DOI 10.1039/c3ee42413h

  View details for Web of Science ID 000327250300012

• Self-healing chemistry enables the stable operation of silicon microparticle anodes for high-energy lithium-ion batteries. Nature chemistry Wang, C., Wu, H., Chen, Z., McDowell, M. T., Cui, Y., Bao, Z. 2013; 5 (12): 1042-8

  Abstract

  The ability to repair damage spontaneously, which is termed self-healing, is an important survival feature in nature because it increases the lifetime of most living creatures. This feature is highly desirable for rechargeable batteries because the lifetime of high-capacity electrodes, such as silicon anodes, is shortened by mechanical fractures generated during the cycling process. Here, inspired by nature, we apply self-healing chemistry to silicon microparticle (SiMP) anodes to overcome their short cycle-life. We show that anodes made from low-cost SiMPs (~3-8 µm), for which stable deep galvanostatic cycling was previously impossible, can now have an excellent cycle life when coated with a self-healing polymer. We attain a cycle life ten times longer than state-of-art anodes made from SiMPs and still retain a high capacity (up to ~3,000 mA h g(-1)). Cracks and damage in the coating during cycling can be healed spontaneously by the randomly branched hydrogen-bonding polymer used.

  View details for DOI 10.1038/nchem.1802

  View details for PubMedID 24256869

• Elastic moduli of polycrystalline Li15Si4 produced in lithium ion batteries JOURNAL OF POWER SOURCES Zeng, Z., Liu, N., Zeng, Q., Ding, Y., Qu, S., Cui, Y., Mao, W. L. 2013; 242: 732-735

  View details for DOI 10.1016/j.jpowsour.2013.05.121

  View details for Web of Science ID 000323628100092

• Highly reversible open framework nanoscale electrodes for divalent ion batteries. Nano letters Wang, R. Y., Wessells, C. D., Huggins, R. A., Cui, Y. 2013; 13 (11): 5748-5752

  Abstract

  The reversible insertion of monovalent ions such as lithium into electrode materials has enabled the development of rechargeable batteries with high energy density. Reversible insertion of divalent ions such as magnesium would allow the creation of new battery chemistries that are potentially safer and cheaper than lithium-based batteries. Here we report that nanomaterials in the Prussian Blue family of open framework materials, such as nickel hexacyanoferrate, allow for the reversible insertion of aqueous alkaline earth divalent ions, including Mg(2+), Ca(2+), Sr(2+), and Ba(2+). We show unprecedented long cycle life and high rate performance for divalent ion insertion. Our results represent a step forward and pave the way for future development in divalent batteries.

  View details for DOI 10.1021/nl403669a

  View details for PubMedID 24147617

• Understanding the role of different conductive polymers in improving the nanostructured sulfur cathode performance. Nano letters Li, W., Zhang, Q., Zheng, G., Seh, Z. W., Yao, H., Cui, Y. 2013; 13 (11): 5534-5540

  Abstract

  Lithium sulfur batteries have brought significant advancement to the current state-of-art battery technologies because of their high theoretical specific energy, but their wide-scale implementation has been impeded by a series of challenges, especially the dissolution of intermediate polysulfides species into the electrolyte. Conductive polymers in combination with nanostructured sulfur have attracted great interest as promising matrices for the confinement of lithium polysulfides. However, the roles of different conductive polymers on the electrochemical performances of sulfur electrode remain elusive and poorly understood due to the vastly different structural configurations of conductive polymer-sulfur composites employed in previous studies. In this work, we systematically investigate the influence of different conductive polymers on the sulfur cathode based on conductive polymer-coated hollow sulfur nanospheres with high uniformity. Three of the most well-known conductive polymers, polyaniline (PANI), polypyrrole (PPY), and poly(3,4-ethylenedioxythiophene) (PEDOT), were coated, respectively, onto monodisperse hollow sulfur nanopsheres through a facile, versatile, and scalable polymerization process. The sulfur cathodes made from these well-defined sulfur nanoparticles act as ideal platforms to study and compare how coating thickness, chemical bonding, and the conductivity of the polymers affected the sulfur cathode performances from both experimental observations and theoretical simulations. We found that the capability of these three polymers in improving long-term cycling stability and high-rate performance of the sulfur cathode decreased in the order of PEDOT > PPY > PANI. High specific capacities and excellent cycle life were demonstrated for sulfur cathodes made from these conductive polymer-coated hollow sulfur nanospheres.

  View details for DOI 10.1021/nl403130h

  View details for PubMedID 24127640

• High-Efficiency Nanostructured Window GaAs Solar Cells. Nano letters Liang, D., Kang, Y., Huo, Y., Chen, Y., Cui, Y., Harris, J. S. 2013; 13 (10): 4850-4856

  Abstract

  Nanostructures have been widely used in solar cells due to their extraordinary optical properties. In most nanostructured cells, high short circuit current has been obtained due to enhanced light absorption. However, most of them suffer from lowered open circuit voltage and fill factor. One of the main challenges is formation of good junction and electrical contact. In particular, nanostructures in GaAs only have shown unsatisfactory performances (below 5% in energy conversion efficiency) which cannot match their ideal material properties and the record photovoltaic performances in industry. Here we demonstrate a completely new design for nanostructured solar cells that combines nanostructured window layer, metal mesa bar contact with small area, high quality planar junction. In this way, we not only keep the advanced optical properties of nanostructures such as broadband and wide angle antireflection, but also minimize its negative impact on electrical properties. High light absorption, efficient carrier collection, leakage elimination, and good lateral conductance can be simultaneously obtained. A nanostructured window cell using GaAs junction and AlGaAs nanocone window demonstrates 17% energy conversion efficiency and 0.982 V high open circuit voltage.

  View details for DOI 10.1021/nl402680g

  View details for PubMedID 24021024

• Microbial battery for efficient energy recovery PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Xie, X., Ye, M., Hsu, P., Liu, N., Criddle, C. S., Cui, Y. 2013; 110 (40): 15925-15930

  Abstract

  By harnessing the oxidative power of microorganisms, energy can be recovered from reservoirs of less-concentrated organic matter, such as marine sediment, wastewater, and waste biomass. Left unmanaged, these reservoirs can become eutrophic dead zones and sites of greenhouse gas generation. Here, we introduce a unique means of energy recovery from these reservoirs-a microbial battery (MB) consisting of an anode colonized by microorganisms and a reoxidizable solid-state cathode. The MB has a single-chamber configuration and does not contain ion-exchange membranes. Bench-scale MB prototypes were constructed from commercially available materials using glucose or domestic wastewater as electron donor and silver oxide as a coupled solid-state oxidant electrode. The MB achieved an efficiency of electrical energy conversion of 49% based on the combustion enthalpy of the organic matter consumed or 44% based on the organic matter added. Electrochemical reoxidation of the solid-state electrode decreased net efficiency to about 30%. This net efficiency of energy recovery (unoptimized) is comparable to methane fermentation with combined heat and power.

  View details for DOI 10.1073/pnas.1307327110

  View details for PubMedID 24043800

• Conducting nanosponge electroporation for affordable and high-efficiency disinfection of bacteria and viruses in water. Nano letters Liu, C., Xie, X., Zhao, W., Liu, N., Maraccini, P. A., Sassoubre, L. M., Boehm, A. B., Cui, Y. 2013; 13 (9): 4288-4293

  Abstract

  High-efficiency, affordable, and low energy water disinfection methods are in great need to prevent diarrheal illness, which is one of the top five leading causes of death over the world. Traditional water disinfection methods have drawbacks including carcinogenic disinfection byproducts formation, energy and time intensiveness, and pathogen recovery. Here, we report an innovative method that achieves high-efficiency water disinfection by introducing nanomaterial-assisted electroporation implemented by a conducting nanosponge filtration device. The use of one-dimensional (1D) nanomaterials allows electroporation to occur at only several volts, which is 2 to 3 orders of magnitude lower than that in traditional electroporation applications. The disinfection mechanism of electroporation prevents harmful byproduct formation and ensures a fast treatment speed of 15 000 L/(h·m(2)), which is equal to a contact time of 1 s. The conducting nanosponge made from low-cost polyurethane sponge coated with carbon nanotubes and silver nanowires ensures the device's affordability. This method achieves more than 6 log (99.9999%) removal of four model bacteria, including Escherichia coli, Salmonella enterica Typhimirium, Enterococcus faecalis, and Bacillus subtilis, and more than 2 log (99%) removal of one model virus, bacteriophage MS2, with a low energy consumption of only 100 J/L.

  View details for DOI 10.1021/nl402053z

  View details for PubMedID 23987737

• Large-area free-standing ultrathin single-crystal silicon as processable materials. Nano letters Wang, S., Weil, B. D., Li, Y., Wang, K. X., Garnett, E., Fan, S., Cui, Y. 2013; 13 (9): 4393-4398

  Abstract

  Silicon has been driving the great success of semiconductor industry, and emerging forms of silicon have generated new opportunities in electronics, biotechnology, and energy applications. Here we demonstrate large-area free-standing ultrathin single-crystalline Si at the wafer scale as new Si materials with processability. We fabricated them by KOH etching of the Si wafer and show their uniform thickness from 10 to sub-2 μm. These ultrathin Si exhibits excellent mechanical flexibility and bendability more than those with 20-30 μm thickness in previous study. Unexpectedly, these ultrathin Si materials can be cut with scissors like a piece of paper, and they are robust during various regular fabrication processings including tweezer handling, spin coating, patterning, doping, wet and dry etching, annealing, and metal deposition. We demonstrate the fabrication of planar and double-sided nanocone solar cells and highlight that the processability on both sides of surface together with the interesting property of these free-standing ultrathin Si materials opens up exciting opportunities to generate novel functional devices different from the existing approaches.

  View details for DOI 10.1021/nl402230v

  View details for PubMedID 23876030

• 25th Anniversary Article: Understanding the Lithiation of Silicon and Other Alloying Anodes for Lithium-Ion Batteries ADVANCED MATERIALS McDowell, M. T., Lee, S. W., Nix, W. D., Cui, Y. 2013; 25 (36): 4966-4984

  Abstract

  Alloying anodes such as silicon are promising electrode materials for next-generation high energy density lithium-ion batteries because of their ability to reversibly incorporate a high concentration of Li atoms. However, alloying anodes usually exhibit a short cycle life due to the extreme volumetric and structural changes that occur during lithium insertion/extraction; these transformations cause mechanical fracture and exacerbate side reactions. To solve these problems, there has recently been significant attention devoted to creating silicon nanostructures that can accommodate the lithiation-induced strain and thus exhibit high Coulombic efficiency and long cycle life. In parallel, many experiments and simulations have been conducted in an effort to understand the details of volumetric expansion, fracture, mechanical stress evolution, and structural changes in silicon nanostructures. The fundamental materials knowledge gained from these studies has provided guidance for designing optimized Si electrode structures and has also shed light on the factors that control large-volume change solid-state reactions. In this paper, we review various fundamental studies that have been conducted to understand structural and volumetric changes, stress evolution, mechanical properties, and fracture behavior of nanostructured Si anodes for lithium-ion batteries and compare the reaction process of Si to other novel anode materials.

  View details for DOI 10.1002/adma.201301795

  View details for PubMedID 24038172

• Crab shells as sustainable templates from nature for nanostructured battery electrodes. Nano letters Yao, H., Zheng, G., Li, W., McDowell, M. T., Seh, Z., Liu, N., Lu, Z., Cui, Y. 2013; 13 (7): 3385-3390

  Abstract

  Rational nanostructure design has been a promising route to address critical materials issues for enabling next-generation high capacity lithium ion batteries for portable electronics, vehicle electrification, and grid-scale storage. However, synthesis of functional nanostructures often involves expensive starting materials and elaborate processing, both of which present a challenge for successful implementation in low-cost applications. In seeking a sustainable and cost-effective route to prepare nanostructured battery electrode materials, we are inspired by the diversity of natural materials. Here, we show that crab shells with the unique Bouligand structure consisting of highly mineralized chitin-protein fibers can be used as biotemplates to fabricate hollow carbon nanofibers; these fibers can then be used to encapsulate sulfur and silicon to form cathodes and anodes for Li-ion batteries. The resulting nanostructured electrodes show high specific capacities (1230 mAh/g for sulfur and 3060 mAh/g for silicon) and excellent cycling performance (up to 200 cycles with 60% and 95% capacity retention, respectively). Since crab shells are readily available due to the 0.5 million tons produced annually as a byproduct of crab consumption, their use as a sustainable and low-cost nanotemplate represents an exciting direction for nanostructured battery materials.

  View details for DOI 10.1021/nl401729r

  View details for PubMedID 23758646

• MoSe2 and WSe2 nanofilms with vertically aligned molecular layers on curved and rough surfaces. Nano letters Wang, H., Kong, D., Johanes, P., Cha, J. J., Zheng, G., Yan, K., Liu, N., Cui, Y. 2013; 13 (7): 3426-3433

  Abstract

  Two-dimensional (2D) layered materials exhibit high anisotropy in materials properties due to the large difference of intra- and interlayer bonding. This presents opportunities to engineer materials whose properties strongly depend on the orientation of the layers relative to the substrate. Here, using a similar growth process reported in our previous study of MoS2 and MoSe2 films whose layers were oriented vertically on flat substrates, we demonstrate that the vertical layer orientation can be realized on curved and rough surfaces such as nanowires (NWs) and microfibers. Such structures can increase the surface area while maintaining the perpendicular orientation of the layers, which may be useful in enhancing various catalytic activities. We show vertically aligned MoSe2 and WSe2 nanofilms on Si NWs and carbon fiber paper. We find that MoSe2 and WSe2 nanofilms on carbon fiber paper are highly efficient electrocatalysts for hydrogen evolution reaction (HER) compared to flat substrates. Both materials exhibit extremely high stability in acidic solution as the HER catalytic activity shows no degradation after 15 000 continuous potential cycles. The HER activity of MoSe2 is further improved by Ni doping.

  View details for DOI 10.1021/nl401944f

  View details for PubMedID 23799638

• Reliable reference electrodes for lithium-ion batteries ELECTROCHEMISTRY COMMUNICATIONS La Mantia, F., Wessells, C. D., Deshazer, H. D., Cui, Y. 2013; 31: 141-144

  View details for DOI 10.1016/j.elecom.2013.03.015

  View details for Web of Science ID 000319236800037

• The new skinny in two-dimensional nanomaterials. ACS nano Koski, K. J., Cui, Y. 2013; 7 (5): 3739-3743

  Abstract

  While the advent of graphene has focused attention on the extraordinary properties of two-dimensional (2D) materials, graphene's lack of an intrinsic band gap and limited amenability to chemical modification has sparked increasing interest in its close relatives and in other 2D layered nanomaterials. In this issue of ACS Nano, Bianco et al. report on the production and characterization of one of these related materials: germanane, a one-atom-thick sheet of hydrogenated puckered germanium atoms structurally similar to graphane. It is a 2D nanomaterial generated via mechanical exfoliation from GeH. Germanane has been predicted to have technologically relevant properties such as a direct band gap and high electron mobility. Monolayer 2D materials like germanane, in general, have attracted enormous interest for their potential technological applications. We offer a perspective on the field of 2D layered nanomaterials and the exciting growth areas and discuss where the new development of germanane fits in, now and in the foreseeable future.

  View details for DOI 10.1021/nn4022422

  View details for PubMedID 23678956

• A transparent electrode based on a metal nanotrough network. Nature nanotechnology Wu, H., Kong, D., Ruan, Z., Hsu, P., Wang, S., Yu, Z., Carney, T. J., Hu, L., Fan, S., Cui, Y. 2013; 8 (6): 421-425

  Abstract

  Transparent conducting electrodes are essential components for numerous flexible optoelectronic devices, including touch screens and interactive electronics. Thin films of indium tin oxide-the prototypical transparent electrode material-demonstrate excellent electronic performances, but film brittleness, low infrared transmittance and low abundance limit suitability for certain industrial applications. Alternatives to indium tin oxide have recently been reported and include conducting polymers, carbon nanotubes and graphene. However, although flexibility is greatly improved, the optoelectronic performance of these carbon-based materials is limited by low conductivity. Other examples include metal nanowire-based electrodes, which can achieve sheet resistances of less than 10Ω □(-1) at 90% transmission because of the high conductivity of the metals. To achieve these performances, however, metal nanowires must be defect-free, have conductivities close to their values in bulk, be as long as possible to minimize the number of wire-to-wire junctions, and exhibit small junction resistance. Here, we present a facile fabrication process that allows us to satisfy all these requirements and fabricate a new kind of transparent conducting electrode that exhibits both superior optoelectronic performances (sheet resistance of ∼2Ω □(-1) at 90% transmission) and remarkable mechanical flexibility under both stretching and bending stresses. The electrode is composed of a free-standing metallic nanotrough network and is produced with a process involving electrospinning and metal deposition. We demonstrate the practical suitability of our transparent conducting electrode by fabricating a flexible touch-screen device and a transparent conducting tape.

  View details for DOI 10.1038/nnano.2013.84

  View details for PubMedID 23685985

• Tuning the Dirac Point in CVD-Grown Graphene through Solution Processed n-Type Doping with 2-(2-Methoxyphenyl)-1,3-dimethyl-2,3-dihydro-1H-benzoimidazole. Nano letters Wei, P., Liu, N., Lee, H. R., Adijanto, E., Ci, L., Naab, B. D., Zhong, J. Q., Park, J., Chen, W., Cui, Y., Bao, Z. 2013; 13 (5): 1890-1897

  Abstract

  Controlling the Dirac point of graphene is essential for complementary circuits. Here, we describe the use of 2-(2-methoxyphenyl)-1,3-dimethyl-2,3-dihydro-1H-benzoimidazole (o-MeO-DMBI) as a strong n-type dopant for chemical-vapor-deposition (CVD) grown graphene. The Dirac point of graphene can be tuned significantly by spin-coating o-MeO-DMBI solutions on the graphene sheets at different concentrations. The transport of graphene can be changed from p-type to ambipolar and finally n-type. The electron transfer between o-MeO-DMBI and graphene was additionally confirmed by Raman imaging and photoemission spectroscopy (PES) measurements. Finally, we fabricated a complementary inverter via inkjet printing patterning of o-MeO-DMBI solutions on graphene to demonstrate the potential of o-MeO-DMBI n-type doping on graphene for future applications in electrical devices.

  View details for DOI 10.1021/nl303410g

  View details for PubMedID 23537351

• A membrane-free lithium/polysulfide semi-liquid battery for large-scale energy storage ENERGY & ENVIRONMENTAL SCIENCE Yang, Y., Zheng, G., Cui, Y. 2013; 6 (5): 1552-1558

  View details for DOI 10.1039/c3ee00072a

  View details for Web of Science ID 000317984700020

• High-performance hollow sulfur nanostructured battery cathode through a scalable, room temperature, one-step, bottom-up approach. Proceedings of the National Academy of Sciences of the United States of America Li, W., Zheng, G., Yang, Y., Seh, Z. W., Liu, N., Cui, Y. 2013; 110 (18): 7148-7153

  Abstract

  Sulfur is an exciting cathode material with high specific capacity of 1,673 mAh/g, more than five times the theoretical limits of its transition metal oxides counterpart. However, successful applications of sulfur cathode have been impeded by rapid capacity fading caused by multiple mechanisms, including large volume expansion during lithiation, dissolution of intermediate polysulfides, and low ionic/electronic conductivity. Tackling the sulfur cathode problems requires a multifaceted approach, which can simultaneously address the challenges mentioned above. Herein, we present a scalable, room temperature, one-step, bottom-up approach to fabricate monodisperse polymer (polyvinylpyrrolidone)-encapsulated hollow sulfur nanospheres for sulfur cathode, allowing unprecedented control over electrode design from nanoscale to macroscale. We demonstrate high specific discharge capacities at different current rates (1,179, 1,018, and 990 mAh/g at C/10, C/5, and C/2, respectively) and excellent capacity retention of 77.6% (at C/5) and 73.4% (at C/2) after 300 and 500 cycles, respectively. Over a long-term cycling of 1,000 cycles at C/2, a capacity decay as low as 0.046% per cycle and an average coulombic efficiency of 98.5% was achieved. In addition, a simple modification on the sulfur nanosphere surface with a layer of conducting polymer, poly(3,4-ethylenedioxythiophene), allows the sulfur cathode to achieve excellent high-rate capability, showing a high reversible capacity of 849 and 610 mAh/g at 2C and 4C, respectively.

  View details for DOI 10.1073/pnas.1220992110

  View details for PubMedID 23589875

  View details for PubMedCentralID PMC3645569

• Nanostructured paper for flexible energy and electronic devices MRS BULLETIN Zheng, G., Cui, Y., Karabulut, E., Wagberg, L., Zhu, H., Hu, L. 2013; 38 (4): 320-325

  View details for DOI 10.1557/mrs.2013.59

  View details for Web of Science ID 000317569900012

• Progress, Challenges, and Opportunities in Two-Dimensional Materials Beyond Graphene ACS NANO Butler, S. Z., Hollen, S. M., Cao, L., Cui, Y., Gupta, J. A., Gutierrez, H. R., Heinz, T. F., Hong, S. S., Huang, J., Ismach, A. F., Johnston-Halperin, E., Kuno, M., Plashnitsa, V. V., Robinson, R. D., Ruoff, R. S., Salahuddin, S., Shan, J., Shi, L., Spencer, M. G., Terrones, M., Windl, W., Goldberger, J. E. 2013; 7 (4): 2898-2926

  Abstract

  Graphene's success has shown that it is possible to create stable, single and few-atom-thick layers of van der Waals materials, and also that these materials can exhibit fascinating and technologically useful properties. Here we review the state-of-the-art of 2D materials beyond graphene. Initially, we will outline the different chemical classes of 2D materials and discuss the various strategies to prepare single-layer, few-layer, and multilayer assembly materials in solution, on substrates, and on the wafer scale. Additionally, we present an experimental guide for identifying and characterizing single-layer-thick materials, as well as outlining emerging techniques that yield both local and global information. We describe the differences that occur in the electronic structure between the bulk and the single layer and discuss various methods of tuning their electronic properties by manipulating the surface. Finally, we highlight the properties and advantages of single-, few-, and many-layer 2D materials in field-effect transistors, spin- and valley-tronics, thermoelectrics, and topological insulators, among many other applications.

  View details for DOI 10.1021/nn400280c

  View details for Web of Science ID 000318143300005

  View details for PubMedID 23464873

• CuInSe2 Nanowires from Facile Chemical Transformation of In2Se3 and Their Integration in Single-Nanowire Devices ACS NANO Schoen, D. T., Peng, H., Cui, Y. 2013; 7 (4): 3205-3211

  Abstract

  Nanowire solar cells are receiving a significant amount of attention for their potential to improve light absorption and charge collection in photovoltaics. Single-nanowire solar cells offer the ability to investigate performance limits for macroscale devices, as well as the opportunity for in-depth structural characterization and property measurement in small working devices. Copper indium selenide (CIS) is a material uniquely suited to these investigations. Not only could nanowire solar cells of CIS perhaps allow efficient macroscale photovoltaics to be fabricated while reducing the amount of CIS required, important for a system with possible resource limitations, but it is also a photovoltaic material for which fundamental understanding has been elusive. We here present a recipe for a scaled up vapor liquid solid based synthesis of CIS nanowires, in-depth material and property correlation of single crystalline CIS nanowires, and the first report of a single CIS nanowire solar cell. The synthesis was accomplished by annealing copper-coated In2Se3 nanowires at a moderate temperature of 350 °C, leading to solid-state reaction forming CIS nanowires. These nanowires are p-type with a resitivity of 6.5 Ωcm. Evidence is observed for a strong diameter dependence on the nanowire transport properties. The single-nanowire solar cells have an open-circuit voltage of 500 mV and a short-circuit current of 2 pA under AM 1.5 illumination.

  View details for DOI 10.1021/nn3058533

  View details for Web of Science ID 000318143300035

  View details for PubMedID 23413963

• Amphiphilic Surface Modification of Hollow Carbon Nanofibers for Improved Cycle Life of Lithium Sulfur Batteries NANO LETTERS Zheng, G., Zhang, Q., Cha, J. J., Yang, Y., Li, W., Seh, Z. W., Cui, Y. 2013; 13 (3): 1265-1270

  Abstract

  Tremendous effort has been put into developing viable lithium sulfur batteries, due to their high specific energy and relatively low cost. Despite recent progress in addressing the various problems of sulfur cathodes, lithium sulfur batteries still exhibit significant capacity decay over cycling. Herein, we identify a new capacity fading mechanism of the sulfur cathodes, relating to Li(x)S detachment from the carbon surface during the discharge process. This observation is confirmed by ex-situ transmission electron microscopy study and first-principles calculations. We demonstrate that this capacity fading mechanism can be overcome by introducing amphiphilic polymers to modify the carbon surface, rendering strong interactions between the nonpolar carbon and the polar Li(x)S clusters. The modified sulfur cathode show excellent cycling performance with specific capacity close to 1180 mAh/g at C/5 current rate. Capacity retention of 80% is achieved over 300 cycles at C/2.

  View details for DOI 10.1021/nl304795g

  View details for Web of Science ID 000316243800063

  View details for PubMedID 23394300

• Synthesis of MoS2 and MoSe2 Films with Vertically Aligned Layers NANO LETTERS Kong, D., Wang, H., Cha, J. J., Pasta, M., Koski, K. J., Yao, J., Cui, Y. 2013; 13 (3): 1341-1347

  Abstract

  Layered materials consist of molecular layers stacked together by weak interlayer interactions. They often crystallize to form atomically smooth thin films, nanotubes, and platelet or fullerene-like nanoparticles due to the anisotropic bonding. Structures that predominately expose edges of the layers exhibit high surface energy and are often considered unstable. In this communication, we present a synthesis process to grow MoS2 and MoSe2 thin films with vertically aligned layers, thereby maximally exposing the edges on the film surface. Such edge-terminated films are metastable structures of MoS2 and MoSe2, which may find applications in diverse catalytic reactions. We have confirmed their catalytic activity in a hydrogen evolution reaction (HER), in which the exchange current density correlates directly with the density of the exposed edge sites.

  View details for DOI 10.1021/nl400258t

  View details for PubMedID 23387444

• Hybrid nanostructured materials for high-performance electrochemical capacitors NANO ENERGY Yu, G., Xie, X., Pan, L., Bao, Z., Cui, Y. 2013; 2 (2): 213-234

  View details for DOI 10.1016/j.nanoen.2012.10.006

  View details for Web of Science ID 000318319700009

• Ambipolar field effect in Sb-doped Bi2Se3 nanoplates by solvothermal synthesis. Nano letters Kong, D., Koski, K. J., Cha, J. J., Hong, S. S., Cui, Y. 2013; 13 (2): 632-636

  Abstract

  A topological insulator is a new phase of quantum matter with a bulk band gap and spin-polarized surface states, which might find use in applications ranging from electronics to energy conversion. Despite much exciting progress in the field, high-yield solution synthesis has not been widely used for the study of topological insulator behavior. Here, we demonstrate that solvothermally synthesized Bi(2)Se(3) nanoplates are attractive for topological insulator studies. The carrier concentration of these Bi(2)Se(3) nanoplates is controlled by compensational Sb doping during the synthesis. In low-carrier-density, Sb-doped Bi(2)Se(3) nanoplates, we observe pronounced ambipolar field effect that demonstrates the flexible manipulation of carrier type and concentration for these nanostructures. Solvothermal synthesis offers an affordable, facile approach to produce high-quality nanomaterials to explore the properties of topological insulators.

  View details for DOI 10.1021/nl304212u

  View details for PubMedID 23323715

• Behaviors of Fe, Zn, and Ga Substitution in CuInS2 Nanoparticles Probed with Anomalous X-ray Diffraction CHEMISTRY OF MATERIALS Connor, S. T., Weil, B. D., Misra, S., Cui, Y., Toney, M. F. 2013; 25 (3): 320-325

  View details for DOI 10.1021/cm302794t

  View details for Web of Science ID 000315018500008

• Observation of Temperature-Induced Crossover to an Orbital-Selective Mott Phase in A(x)Fe(2-y)Se(2) (A = K, Rb) Superconductors PHYSICAL REVIEW LETTERS Yi, M., Lu, D. H., Yu, R., Riggs, S. C., Chu, J., Lv, B., Liu, Z. K., Lu, M., Cui, Y., Hashimoto, M., Mo, S., Hussain, Z., Chu, C. W., Fisher, I. R., Si, Q., Shen, Z. 2013; 110 (6)

  Abstract

  Using angle-resolved photoemission spectroscopy, we observe the low-temperature state of the A(x)Fe(2-y)Se(2) (A=K, Rb) superconductors to exhibit an orbital-dependent renormalization of the bands near the Fermi level-the d(xy) bands heavily renormalized compared to the d(xz)/d(yz) bands. Upon raising the temperature to above 150 K, the system evolves into a state in which the d(xy) bands have depleted spectral weight while the d(xz)/d(yz) bands remain metallic. Combined with theoretical calculations, our observations can be consistently understood as a temperature-induced crossover from a metallic state at low temperatures to an orbital-selective Mott phase at high temperatures. Moreover, the fact that the superconducting state of A(x)Fe(2-y)Se(2) is near the boundary of such an orbital-selective Mott phase constrains the system to have sufficiently strong on-site Coulomb interactions and Hund's coupling, highlighting the nontrivial role of electron correlation in this family of iron-based superconductors.

  View details for DOI 10.1103/PhysRevLett.110.067003

  View details for PubMedID 23432294

• Topological insulator nanostructures PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS Cha, J. J., Koski, K. J., Cui, Y. 2013; 7 (1-2): 15-25

  View details for DOI 10.1002/pssr.201206393

  View details for Web of Science ID 000318068800003

• In Situ TEM of Two-Phase Lithiation of Amorphous Silicon Nanospheres NANO LETTERS McDowell, M. T., Lee, S. W., Harris, J. T., Korgel, B. A., Wang, C., Nix, W. D., Cui, Y. 2013; 13 (2): 758-764

  Abstract

  To utilize high-capacity Si anodes in next-generation Li-ion batteries, the physical and chemical transformations during the Li-Si reaction must be better understood. Here, in situ transmission electron microscopy is used to observe the lithiation/delithiation of amorphous Si nanospheres; amorphous Si is an important anode material that has been less studied than crystalline Si. Unexpectedly, the experiments reveal that the first lithiation occurs via a two-phase mechanism, which is contrary to previous understanding and has important consequences for mechanical stress evolution during lithiation. On the basis of kinetics measurements, this behavior is suggested to be due to the rate-limiting effect of Si-Si bond breaking. In addition, the results show that amorphous Si has more favorable kinetics and fracture behavior when reacting with Li than does crystalline Si, making it advantageous to use in battery electrodes. Amorphous spheres up to 870 nm in diameter do not fracture upon lithiation; this is much larger than the 150 nm critical fracture diameter previously identified for crystalline Si spheres.

  View details for DOI 10.1021/nl3044508

  View details for Web of Science ID 000315079500072

  View details for PubMedID 23323680

• Transparent and conductive paper from nanocellulose fibers ENERGY & ENVIRONMENTAL SCIENCE Hu, L., Zheng, G., Yao, J., Liu, N., Weil, B., Eskilsson, M., Karabulut, E., Ruan, Z., Fan, S., Bloking, J. T., McGehee, M. D., Wagberg, L., Cui, Y. 2013; 6 (2): 513-518

  View details for DOI 10.1039/c2ee23635d

  View details for Web of Science ID 000313892400013

• Critical-temperature/Peierls-stress dependent size effects in body centered cubic nanopillars APPLIED PHYSICS LETTERS Han, S. M., Feng, G., Jung, J. Y., Jung, H. J., Groves, J. R., Nix, W. D., Cui, Y. 2013; 102 (4)

  View details for DOI 10.1063/1.4776658

  View details for Web of Science ID 000314723600032

• Sulphur-TiO2 yolk-shell nanoarchitecture with internal void space for long-cycle lithium-sulphur batteries. Nature communications Wei Seh, Z., Li, W., Cha, J. J., Zheng, G., Yang, Y., McDowell, M. T., Hsu, P., Cui, Y. 2013; 4: 1331-?

  Abstract

  Sulphur is an attractive cathode material with a high specific capacity of 1,673 mAh g(-1), but its rapid capacity decay owing to polysulphide dissolution presents a significant technical challenge. Despite much efforts in encapsulating sulphur particles with conducting materials to limit polysulphide dissolution, relatively little emphasis has been placed on dealing with the volumetric expansion of sulphur during lithiation, which will lead to cracking and fracture of the protective shell. Here, we demonstrate the design of a sulphur-TiO(2) yolk-shell nanoarchitecture with internal void space to accommodate the volume expansion of sulphur, resulting in an intact TiO(2) shell to minimize polysulphide dissolution. An initial specific capacity of 1,030 mAh g(-1) at 0.5 C and Coulombic efficiency of 98.4% over 1,000 cycles are achieved. Most importantly, the capacity decay after 1,000 cycles is as small as 0.033% per cycle, which represents the best performance for long-cycle lithium-sulphur batteries so far.

  View details for DOI 10.1038/ncomms2327

  View details for PubMedID 23299881

• A transparent electrode based on a metal nanotrough network Nature Nanotechnology Fan, S., H., Wu, H., Kong, S., D., Ruan et al., C., Z. 2013; 8 (6): 421-425

  Abstract

  Transparent conducting electrodes are essential components for numerous flexible optoelectronic devices, including touch screens and interactive electronics. Thin films of indium tin oxide-the prototypical transparent electrode material-demonstrate excellent electronic performances, but film brittleness, low infrared transmittance and low abundance limit suitability for certain industrial applications. Alternatives to indium tin oxide have recently been reported and include conducting polymers, carbon nanotubes and graphene. However, although flexibility is greatly improved, the optoelectronic performance of these carbon-based materials is limited by low conductivity. Other examples include metal nanowire-based electrodes, which can achieve sheet resistances of less than 10Ω □(-1) at 90% transmission because of the high conductivity of the metals. To achieve these performances, however, metal nanowires must be defect-free, have conductivities close to their values in bulk, be as long as possible to minimize the number of wire-to-wire junctions, and exhibit small junction resistance. Here, we present a facile fabrication process that allows us to satisfy all these requirements and fabricate a new kind of transparent conducting electrode that exhibits both superior optoelectronic performances (sheet resistance of ∼2Ω □(-1) at 90% transmission) and remarkable mechanical flexibility under both stretching and bending stresses. The electrode is composed of a free-standing metallic nanotrough network and is produced with a process involving electrospinning and metal deposition. We demonstrate the practical suitability of our transparent conducting electrode by fabricating a flexible touch-screen device and a transparent conducting tape.

  View details for DOI 10.1038/nnano.2013.84

• Stable Li-ion Battery Anodes by In-situ Polymerization of Conducting Hydrogel to Conformally Coat Silicon Nanoparticles Nature Comm. Wu, H., Yu, G., Pan, L., Liu, N., McDowell, M., T., Bao, Z. 2013; 4: 1943

  Abstract

  Silicon has a high-specific capacity as an anode material for Li-ion batteries, and much research has been focused on overcoming the poor cycling stability issue associated with its large volume changes during charging and discharging processes, mostly through nanostructured material design. Here we report incorporation of a conducting polymer hydrogel into Si-based anodes: the hydrogel is polymerized in-situ, resulting in a well-connected three-dimensional network structure consisting of Si nanoparticles conformally coated by the conducting polymer. Such a hierarchical hydrogel framework combines multiple advantageous features, including a continuous electrically conductive polyaniline network, binding with the Si surface through either the crosslinker hydrogen bonding with phytic acid or electrostatic interaction with the positively charged polymer, and porous space for volume expansion of Si particles. With this anode, we demonstrate a cycle life of 5,000 cycles with over 90% capacity retention at current density of 6.0 A g(-1).

  View details for DOI 10.1038/ncomms2941

• Performance enhancement of metal nanowire transparent conducting electrodes by mesoscale metal wires. Nature communications Hsu, P., Wang, S., Wu, H., Narasimhan, V. K., Kong, D., Ryoung Lee, H., Cui, Y. 2013; 4: 2522-?

  Abstract

  For transparent conducting electrodes in optoelectronic devices, electrical sheet resistance and optical transmittance are two of the main criteria. Recently, metal nanowires have been demonstrated to be a promising type of transparent conducting electrode because of low sheet resistance and high transmittance. Here we incorporate a mesoscale metal wire (1-5 μm in diameter) into metal nanowire transparent conducting electrodes and demonstrate at least a one order of magnitude reduction in sheet resistance at a given transmittance. We realize experimentally a hybrid of mesoscale and nanoscale metal nanowires with high performance, including a sheet resistance of 0.36 Ω sq(-1) and transmittance of 92%. In addition, the mesoscale metal wires are applied to a wide range of transparent conducting electrodes including conducting polymers and oxides with improvement up to several orders of magnitude. The metal mesowires can be synthesized by electrospinning methods and their general applicability opens up opportunities for many transparent conducting electrode applications.

  View details for DOI 10.1038/ncomms3522

  View details for PubMedID 24065116

• All-back-contact ultra-thin silicon nanocone solar cells with 13.7% power conversion efficiency. Nature communications Jeong, S., McGehee, M. D., Cui, Y. 2013; 4: 2950-?

  Abstract

  Thinner Si solar cells with higher efficiency can make a Si photovoltaic system a cost-effective energy solution, and nanostructuring has been suggested as a promising method to make thin Si an effective absorber. However, thin Si solar cells with nanostructures are not efficient because of severe Auger recombination and increased surface area, normally yielding <50% EQE with short-wavelength light. Here we demonstrate >80% EQEs at wavelengths from 400 to 800 nm in a sub-10-μm-thick Si solar cell, resulting in 13.7% power conversion efficiency. This significant improvement was achieved with an all-back-contact design preventing Auger recombination and with a nanocone structure having less surface area than any other nanostructures for solar cells. The device design principles presented here balance the photonic and electronic effects together and are an important step to realizing highly efficient, thin Si and other types of thin solar cells.

  View details for DOI 10.1038/ncomms3950

  View details for PubMedID 24335845

• Strengthening effect of single-atomic-layer graphene in metal-graphene nanolayered composites Nature Communications Kim, Y., Lee, J., Yeom, M, S., Shin, J., W., Kim, H., Cui, Y. 2013; 2114 (4)
• Performance enhancement of metal nanowire transparent conducting electrodes by mesoscale metal wires Nature Communications Hsu, P., C., Wang, S., Wu, H., Narasimhan, V., K., Kong, D., Lee, H., R., Cui, Y. 2013; 2522 (4)
• Self-healing chemistry enables the stable operation of silicon microparticle anodes for high-energy lithium-ion batteries Nature Chemistry Wang, C., Wu, H., Chen, Z., McDowell, M., T., Cui, Y., Bao, Z. 2013

  View details for DOI 10.1038/NCHEM.1802

• High-performance hollow sulfur nanostructured battery cathode through a scalable, room temperature, one-step, bottom-up approach PNAS Li, W., Zheng, G., Yang, Y., Seh, Z., W., Liu, N., Cui, Y. 2013: 7148–53

  Abstract

  Sulfur is an exciting cathode material with high specific capacity of 1,673 mAh/g, more than five times the theoretical limits of its transition metal oxides counterpart. However, successful applications of sulfur cathode have been impeded by rapid capacity fading caused by multiple mechanisms, including large volume expansion during lithiation, dissolution of intermediate polysulfides, and low ionic/electronic conductivity. Tackling the sulfur cathode problems requires a multifaceted approach, which can simultaneously address the challenges mentioned above. Herein, we present a scalable, room temperature, one-step, bottom-up approach to fabricate monodisperse polymer (polyvinylpyrrolidone)-encapsulated hollow sulfur nanospheres for sulfur cathode, allowing unprecedented control over electrode design from nanoscale to macroscale. We demonstrate high specific discharge capacities at different current rates (1,179, 1,018, and 990 mAh/g at C/10, C/5, and C/2, respectively) and excellent capacity retention of 77.6% (at C/5) and 73.4% (at C/2) after 300 and 500 cycles, respectively. Over a long-term cycling of 1,000 cycles at C/2, a capacity decay as low as 0.046% per cycle and an average coulombic efficiency of 98.5% was achieved. In addition, a simple modification on the sulfur nanosphere surface with a layer of conducting polymer, poly(3,4-ethylenedioxythiophene), allows the sulfur cathode to achieve excellent high-rate capability, showing a high reversible capacity of 849 and 610 mAh/g at 2C and 4C, respectively.

  View details for DOI 10.1073/pnas.1220992110

  View details for PubMedCentralID PMC3645569

• Stable cycling of lithium sulfide cathodes through strong affinity with a bifunctional binder Chemical Science Seh, Z., W., Zhang, Q., Li, W., Zheng, G., Yaoa, H., Cui, Y. 2013

  View details for DOI 10.1039/c3sc51476e

• Critical-temperature/Peierls-stress dependent size effects in body centered cubic nanopillars Applied Physics Letters Han, S., M., Feng, G., Jung, J., Y., Jung, H., J., Groves, J., R., Nix, W., D., Cui, Y. 2013; 102: 41910

  View details for DOI 10.1063/1.4776658

• Electrochemical tuning of vertically aligned MoS2 nanofilms and its application in improving hydrogen evolution reaction Wang, H., Lu, Z., Xu, S., Kong, D., Cha, J., J., Zheng, G., Cui, Y. 2013

  View details for DOI 10.1073/pnas.1316792110

• Conducting nano-sponge electroporation for affordable and high-efficiency disinfection of bacteria and viruses in water. Nano Letters Liu, C., Xie, X., Zhao, W., Liu, N., Maraccini, P., A., Sassoubre, L., M., Cui, Y. 2013; 9 (13): 4288-4293
• All-back-contact ultra-thin silicon nanocone solar cells with 13.7% power conversion efficiency Nature Communications Jeong, S., McGehee, M., D., Cui, Y. 2013; 2950 (4)
• Understanding the Role of Different Conductive Polymers in Improving the Nanostructured Sulfur Cathode Performance Nano Letters Li, W., Zhang, Q., Zheng, G., Seh, Z., W., Yao, H., Cui, Y. 2013; 13: 5534-5540
• Understanding the Lithiation of Silicon and Other Alloying Anodes for Lithium-Ion Batteries (25th Anniversary Article) Advanced Materials McDowell, M., T., Lee, S., W., Nix, W., D., Cui, Y. 2013

  View details for DOI 10.1002/adma.201301795

• Microbial battery for efficient energy recovery. PNAS Xie, X., Ye, M., Hsu, P., C., Liu, N., Criddle, C., S., Cui, Y. 2013: 15925–30

  Abstract

  By harnessing the oxidative power of microorganisms, energy can be recovered from reservoirs of less-concentrated organic matter, such as marine sediment, wastewater, and waste biomass. Left unmanaged, these reservoirs can become eutrophic dead zones and sites of greenhouse gas generation. Here, we introduce a unique means of energy recovery from these reservoirs-a microbial battery (MB) consisting of an anode colonized by microorganisms and a reoxidizable solid-state cathode. The MB has a single-chamber configuration and does not contain ion-exchange membranes. Bench-scale MB prototypes were constructed from commercially available materials using glucose or domestic wastewater as electron donor and silver oxide as a coupled solid-state oxidant electrode. The MB achieved an efficiency of electrical energy conversion of 49% based on the combustion enthalpy of the organic matter consumed or 44% based on the organic matter added. Electrochemical reoxidation of the solid-state electrode decreased net efficiency to about 30%. This net efficiency of energy recovery (unoptimized) is comparable to methane fermentation with combined heat and power.

  View details for DOI 10.1073/pnas.1307327110

  View details for PubMedCentralID PMC3791761

• Large-Area Free-Standing Ultrathin Single-Crystal Silicon as Processable Materials Nano Letters Wang, S., Weil, B., Li, Y., Wang, K., X., Garnett, E., Fan, S., Cui, Y. 2013: 4393–98

  Abstract

  Silicon has been driving the great success of semiconductor industry, and emerging forms of silicon have generated new opportunities in electronics, biotechnology, and energy applications. Here we demonstrate large-area free-standing ultrathin single-crystalline Si at the wafer scale as new Si materials with processability. We fabricated them by KOH etching of the Si wafer and show their uniform thickness from 10 to sub-2 μm. These ultrathin Si exhibits excellent mechanical flexibility and bendability more than those with 20-30 μm thickness in previous study. Unexpectedly, these ultrathin Si materials can be cut with scissors like a piece of paper, and they are robust during various regular fabrication processings including tweezer handling, spin coating, patterning, doping, wet and dry etching, annealing, and metal deposition. We demonstrate the fabrication of planar and double-sided nanocone solar cells and highlight that the processability on both sides of surface together with the interesting property of these free-standing ultrathin Si materials opens up exciting opportunities to generate novel functional devices different from the existing approaches.

  View details for DOI 10.1021/nl402230v

• First-row transition metal dichalcogenide catalysts for hydrogen evolution reaction Energy and Environmental Science Kong, D., Cha, J., J., Wang, H., Lee, H., R., Cui, Y. 2013; 3553 (6)
• Oxidation processes on conducting carbon additives for lithium-ion batteries JOURNAL OF APPLIED ELECTROCHEMISTRY La Mantia, F., Huggins, R. A., Cui, Y. 2013; 43 (1): 1-7

  View details for DOI 10.1007/s10800-012-0499-9

  View details for Web of Science ID 000312209600001

• Nanostructured sulfur cathodes CHEMICAL SOCIETY REVIEWS Yang, Y., Zheng, G., Cui, Y. 2013; 42 (7): 3018-3032

  Abstract

  Rechargeable Li/S batteries have attracted significant attention lately due to their high specific energy and low cost. They are promising candidates for applications, including portable electronics, electric vehicles and grid-level energy storage. However, poor cycle life and low power capability are major technical obstacles. Various nanostructured sulfur cathodes have been developed to address these issues, as they provide greater resistance to pulverization, faster reaction kinetics and better trapping of soluble polysulfides. In this review, recent developments on nanostructured sulfur cathodes and mechanisms behind their operation are presented and discussed. Moreover, progress on novel characterization of sulfur cathodes is also summarized, as it has deepened the understanding of sulfur cathodes and will guide further rational design of sulfur electrodes.

  View details for DOI 10.1039/c2cs35256g

  View details for Web of Science ID 000316869500024

  View details for PubMedID 23325336

• The mechanism of ultrafast structural switching in superionic copper (I) sulphide nanocrystals NATURE COMMUNICATIONS Miller, T. A., Wittenberg, J. S., Wen, H., Connor, S., Cui, Y., Lindenberg, A. M. 2013; 4

  Abstract

  Superionic materials are multi-component solids with simultaneous characteristics of both a solid and a liquid. Above a critical temperature associated with a structural phase transition, they exhibit liquid-like ionic conductivities and dynamic disorder within a rigid crystalline structure. Broad applications as electrochemical storage materials and resistive switching devices follow from this abrupt change in ionic mobility, but the microscopic pathways and speed limits associated with this switching process are largely unknown. Here we use ultrafast X-ray spectroscopy and scattering techniques to obtain an atomic-level, real-time view of the transition state in copper sulphide nanocrystals. We observe the transformation to occur on a twenty picosecond timescale and show that this is determined by the ionic hopping time.

  View details for DOI 10.1038/ncomms2385

  View details for Web of Science ID 000316614600039

  View details for PubMedID 23340409

• Nanoporous silicon networks as anodes for lithium ion batteries PHYSICAL CHEMISTRY CHEMICAL PHYSICS Zhu, J., Gladden, C., Liu, N., Cui, Y., Zhang, X. 2013; 15 (2): 440-443

  Abstract

  Nanoporous silicon (Si) networks with controllable porosity and thickness are fabricated by a simple and scalable electrochemical process, and then released from Si wafers and transferred to flexible and conductive substrates. These nanoporous Si networks serve as high performance Li-ion battery electrodes, with an initial discharge capacity of 2570 mA h g(-1), above 1000 mA h g(-1) after 200 cycles without any electrolyte additives.

  View details for DOI 10.1039/c2cp44046f

  View details for Web of Science ID 000311963600004

  View details for PubMedID 23183772

• Stable Li-ion battery anodes by in-situ polymerization of conducting hydrogel to conformally coat silicon nanoparticles. Nature communications Wu, H., Yu, G., Pan, L., Liu, N., McDowell, M. T., Bao, Z., Cui, Y. 2013; 4: 1943-?

  Abstract

  Silicon has a high-specific capacity as an anode material for Li-ion batteries, and much research has been focused on overcoming the poor cycling stability issue associated with its large volume changes during charging and discharging processes, mostly through nanostructured material design. Here we report incorporation of a conducting polymer hydrogel into Si-based anodes: the hydrogel is polymerized in-situ, resulting in a well-connected three-dimensional network structure consisting of Si nanoparticles conformally coated by the conducting polymer. Such a hierarchical hydrogel framework combines multiple advantageous features, including a continuous electrically conductive polyaniline network, binding with the Si surface through either the crosslinker hydrogen bonding with phytic acid or electrostatic interaction with the positively charged polymer, and porous space for volume expansion of Si particles. With this anode, we demonstrate a cycle life of 5,000 cycles with over 90% capacity retention at current density of 6.0 A g(-1).

  View details for DOI 10.1038/ncomms2941

  View details for PubMedID 23733138

• Rice husks as a sustainable source of nanostructured silicon for high performance Li-ion battery anodes. Scientific reports Liu, N., Huo, K., McDowell, M. T., Zhao, J., Cui, Y. 2013; 3: 1919-?

  Abstract

  The recovery of useful materials from earth-abundant substances is of strategic importance for industrial processes. Despite the fact that Si is the second most abundant element in the Earth's crust, processes to form Si nanomaterials is usually complex, costly and energy-intensive. Here we show that pure Si nanoparticles (SiNPs) can be derived directly from rice husks (RHs), an abundant agricultural byproduct produced at a rate of 1.2 × 10(8) tons/year, with a conversion yield as high as 5% by mass. And owing to their small size (10-40 nm) and porous nature, these recovered SiNPs exhibits high performance as Li-ion battery anodes, with high reversible capacity (2,790 mA h g(-1), seven times greater than graphite anodes) and long cycle life (86% capacity retention over 300 cycles). Using RHs as the raw material source, overall energy-efficient, green, and large scale synthesis of low-cost and functional Si nanomaterials is possible.

  View details for DOI 10.1038/srep01919

  View details for PubMedID 23715238

  View details for PubMedCentralID PMC3665957

• Magnetically ultraresponsive nanoscavengers for next-generation water purification systems. Nature communications Zhang, M., Xie, X., Tang, M., Criddle, C. S., Cui, Y., Wang, S. X. 2013; 4: 1866-?

  Abstract

  The development of sustainable, robust and energy efficient water purification technology is still challenging. Although use of nanoparticles is promising, methods are needed for their efficient recovery post treatment. Here we address this issue by fabrication of magnetically ultraresponsive 'nanoscavengers', nanoparticles containing synthetic antiferromagnetic core layers and functional capping layers. When dispersed in water, the nanoscavengers efficiently interact with contaminants to remove them from the water. They are then quickly collected (<5 min) with a permanent magnet, owing to their magnetically ultraresponsive core layers. Specifically, we demonstrate fabrication and deployment of Ag-capped nanoscavengers for disinfection followed by application of an external magnetic field for separation. We also develop and validate a collision-based model for pathogen inactivation, and propose a cyclical water purification scheme in which nanoscavengers are recovered and recycled for contaminant removal.

  View details for DOI 10.1038/ncomms2892

  View details for PubMedID 23673651

• Imaging state of charge and its correlation to interaction variation in an LiMn0.75Fe0.25PO4 nanorods-graphene hybrid CHEMICAL COMMUNICATIONS Zhou, J., Wang, J., Hu, Y., Regier, T., Wang, H., Yang, Y., Cui, Y., Dai, H. 2013; 49 (17): 1765-1767

  Abstract

  Visualization of the state of charge (SOC) in an LiMn(0.75)Fe(0.25)PO(4) nanorods-graphene hybrid nanostructure (LMFP-C) is realized by chemical mapping of the Fe valance state using scanning transmission X-ray microscopy (STXM). The LMFP-graphene interaction strength variation studied by C K-edge STXM has been correlated to SOC variation, i.e. a stronger interaction was observed for sample regions with a higher SOC in LMFP. Such structure-performance correlation opens new perspectives for a rational design of a better performance olivine cathode for lithium ion batteries.

  View details for DOI 10.1039/c3cc39015b

  View details for Web of Science ID 000314424700025

  View details for PubMedID 23340608

• Silicon-conductive nanopaper for Li-ion batteries NANO ENERGY Hu, L., Liu, N., Eskilsson, M., Zheng, G., McDonough, J., Wagberg, L., Cui, Y. 2013; 2 (1): 138-145

  View details for DOI 10.1016/j.nanoen.2012.08.008

  View details for Web of Science ID 000318050500020

• fSulphur-TiO2 yolk-shell nanoarchitecture with internal void space for long-cycle lithium-sulphur batteries NATURE COMMUNICATIONS Seh, Z. W., Li, W., Cha, J. J., Zheng, G., Yang, Y., McDowell, M. T., Hsu, P., Cui, Y. 2013; 4

  View details for DOI 10.1038/ncomms2327

  View details for Web of Science ID 000316614600001

• Nanoparticle and Microparticle Flow in Porous and Fractured Media-An Experimental Study SPE Annual Technical Conference and Exhibition Alaskar, M., Ames, M., Connor, S., Liu, C., Cui, Y., Li, K., Horne, R. SOC PETROLEUM ENG. 2012: 1160–71

  View details for Web of Science ID 000313300500017

• Reaction Front Evolution during Electrochemical Lithiation of Crystalline Silicon Nanopillars ISRAEL JOURNAL OF CHEMISTRY Lee, S. W., Berla, L. A., McDowell, M. T., Nix, W. D., Cui, Y. 2012; 52 (11-12): 1118-1123

  View details for DOI 10.1002/ijch.201200077

  View details for Web of Science ID 000312647100017

• Studying the Kinetics of Crystalline Silicon Nanoparticle Lithiation with In Situ Transmission Electron Microscopy ADVANCED MATERIALS McDowell, M. T., Ryu, I., Lee, S. W., Wang, C., Nix, W. D., Cui, Y. 2012; 24 (45): 6034-?

  Abstract

  In situ transmission electron microscopy (TEM) is used to study the electrochemical lithiation of high-capacity crystalline Si nanoparticles for use in Li-ion battery anodes. The lithiation reaction slows down as it progresses into the particle interior, and analysis suggests that this behavior is due not to diffusion limitation but instead to the influence of mechanical stress on the driving force for reaction.

  View details for DOI 10.1002/adma.201202744

  View details for Web of Science ID 000312130300007

  View details for PubMedID 22945804

• Nanoscale photon management in silicon solar cells JOURNAL OF VACUUM SCIENCE & TECHNOLOGY A Jeong, S., Wang, S., Cui, Y. 2012; 30 (6)

  View details for DOI 10.1116/1.4759260

  View details for Web of Science ID 000311458500002

• Characterization of the Cell-Nanopillar Interface by Transmission Electron Microscopy NANO LETTERS Hanson, L., Lin, Z. C., Xie, C., Cui, Y., Cui, B. 2012; 12 (11): 5815-5820

  Abstract

  Vertically aligned nanopillars can serve as excellent electrical, optical and mechanical platforms for biological studies. However, revealing the nature of the interface between the cell and the nanopillar is very challenging. In particular, a matter of debate is whether the cell membrane remains intact around the nanopillar. Here we present a detailed characterization of the cell-nanopillar interface by transmission electron microscopy. We examined cortical neurons growing on nanopillars with diameter 50-500 nm and heights 0.5-2 μm. We found that on nanopillars less than 300 nm in diameter, the cell membrane wraps around the entirety of the nanopillar without the nanopillar penetrating into the interior of the cell. On the other hand, the cell sits on top of arrays of larger, closely spaced nanopillars. We also observed that the membrane-surface gap of both cell bodies and neurites is smaller for nanopillars than for a flat substrate. These results support a tight interaction between the cell membrane and the nanopillars and previous findings of excellent sealing in electrophysiology recordings using nanopillar electrodes.

  View details for DOI 10.1021/nl303163y

  View details for Web of Science ID 000311244400064

  View details for PubMedID 23030066

• A high-rate and long cycle life aqueous electrolyte battery for grid-scale energy storage NATURE COMMUNICATIONS Pasta, M., Wessells, C. D., Huggins, R. A., Cui, Y. 2012; 3

  Abstract

  New types of energy storage are needed in conjunction with the deployment of solar, wind and other volatile renewable energy sources and their integration with the electric grid. No existing energy storage technology can economically provide the power, cycle life and energy efficiency needed to respond to the costly short-term transients that arise from renewables and other aspects of grid operation. Here we demonstrate a new type of safe, fast, inexpensive, long-life aqueous electrolyte battery, which relies on the insertion of potassium ions into a copper hexacyanoferrate cathode and a novel activated carbon/polypyrrole hybrid anode. The cathode reacts rapidly with very little hysteresis. The hybrid anode uses an electrochemically active additive to tune its potential. This high-rate, high-efficiency cell has a 95% round-trip energy efficiency when cycled at a 5C rate, and a 79% energy efficiency at 50C. It also has zero-capacity loss after 1,000 deep-discharge cycles.

  View details for DOI 10.1038/ncomms2139

  View details for Web of Science ID 000313514100059

  View details for PubMedID 23093186

• Optical Absorption Enhancement in Freestanding GaAs Thin Film Nanopyramid Arrays ADVANCED ENERGY MATERIALS Liang, D., Huo, Y., Kang, Y., Wang, K. X., Gu, A., Tan, M., Yu, Z., Li, S., Jia, J., Bao, X., Wang, S., Yao, Y., Wong, H. P., Fan, S., Cui, Y., Harris, J. S. 2012; 2 (10): 1254-1260

  View details for DOI 10.1002/aenm.201200022

  View details for Web of Science ID 000309595900014

• Designing nanostructured Si anodes for high energy lithium ion batteries NANO TODAY Wu, H., Cui, Y. 2012; 7 (5): 414-429

  View details for DOI 10.1016/j.nantod.2012.08.004

  View details for Web of Science ID 000310863200008

• High-capacity micrometer-sized Li2S particles as cathode materials for advanced rechargeable lithium-ion batteries. Journal of the American Chemical Society Yang, Y., Zheng, G., Misra, S., Nelson, J., Toney, M. F., Cui, Y. 2012; 134 (37): 15387-15394

  Abstract

  Li(2)S is a high-capacity cathode material for lithium metal-free rechargeable batteries. It has a theoretical capacity of 1166 mAh/g, which is nearly 1 order of magnitude higher than traditional metal oxides/phosphates cathodes. However, Li(2)S is usually considered to be electrochemically inactive due to its high electronic resistivity and low lithium-ion diffusivity. In this paper, we discover that a large potential barrier (~1 V) exists at the beginning of charging for Li(2)S. By applying a higher voltage cutoff, this barrier can be overcome and Li(2)S becomes active. Moreover, this barrier does not appear again in the following cycling. Subsequent cycling shows that the material behaves similar to common sulfur cathodes with high energy efficiency. The initial discharge capacity is greater than 800 mAh/g for even 10 μm Li(2)S particles. Moreover, after 10 cycles, the capacity is stabilized around 500-550 mAh/g with a capacity decay rate of only ~0.25% per cycle. The origin of the initial barrier is found to be the phase nucleation of polysulfides, but the amplitude of barrier is mainly due to two factors: (a) charge transfer directly between Li(2)S and electrolyte without polysulfide and (b) lithium-ion diffusion in Li(2)S. These results demonstrate a simple and scalable approach to utilizing Li(2)S as the cathode material for rechargeable lithium-ion batteries with high specific energy.

  View details for PubMedID 22909273

• Chemical Intercalation of Zerovalent Metals into 2D Layered Bi2Se3 Nanoribbons JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Koski, K. J., Wessells, C. D., Reed, B. W., Cha, J. J., Kong, D., Cui, Y. 2012; 134 (33): 13773-13779

  Abstract

  We have developed a chemical method to intercalate a variety of zerovalent metal atoms into two-dimensional (2D) layered Bi(2)Se(3) chalcogenide nanoribbons. We use a chemical reaction, such as a disproportionation redox reaction, to generate dilute zerovalent metal atoms in a refluxing solution, which intercalate into the layered Bi(2)Se(3) structure. The zerovalent nature of the intercalant allows superstoichiometric intercalation of metal atoms such as Ag, Au, Co, Cu, Fe, In, Ni, and Sn. We foresee the impact of this methodology in establishing novel fundamental physical behaviors and in possible energy applications.

  View details for DOI 10.1021/ja304925t

  View details for Web of Science ID 000307699000037

  View details for PubMedID 22830589

• Effects of Magnetic Doping on Weak Antilocalization in Narrow Bi2Se3 Nanoribbons NANO LETTERS Cha, J. J., Claassen, M., Kong, D., Hong, S. S., Koski, K. J., Qi, X., Cui, Y. 2012; 12 (8): 4355-4359

  Abstract

  We report low-temperature, magnetotransport measurements of ferrocene-doped Bi(2)Se(3) nanoribbons grown by vapor-liquid-solid method. The Kondo effect, a saturating resistance upturn at low temperatures, is observed in these ribbons to indicate presence of localized impurity spins. Magnetoconductances of the ferrocene-doped ribbons display both weak localization and weak antilocalization, which is in contrast with those of undoped ribbons that show only weak antilocalization. We show that the observed magnetoconductances are governed by a one-dimensional localization theory that includes spin orbit coupling and magnetic impurity scattering, yielding various scattering and dephasing lengths for Bi(2)Se(3). The power law decay of the dephasing length on temperature also reflects one-dimensional localization regime in these narrow Bi(2)Se(3) nanoribbons. The emergence of weak localization in ferrocene-doped Bi(2)Se(3) nanoribbons presents ferrocene as an effective magnetic dopant source.

  View details for DOI 10.1021/nl3021472

  View details for Web of Science ID 000307211000077

  View details for PubMedID 22830578

• External push and internal pull forces recruit curvature-sensing N-BAR domain proteins to the plasma membrane NATURE CELL BIOLOGY Galic, M., Jeong, S., Tsai, F., Joubert, L., Wu, Y. I., Hahn, K. M., Cui, Y., Meyer, T. 2012; 14 (8): 874-U212

  Abstract

  Many of the more than 20 mammalian proteins with N-BAR domains control cell architecture and endocytosis by associating with curved sections of the plasma membrane. It is not well understood whether N-BAR proteins are recruited directly by processes that mechanically curve the plasma membrane or indirectly by plasma-membrane-associated adaptor proteins that recruit proteins with N-BAR domains that then induce membrane curvature. Here, we show that externally induced inward deformation of the plasma membrane by cone-shaped nanostructures (nanocones) and internally induced inward deformation by contracting actin cables both trigger recruitment of isolated N-BAR domains to the curved plasma membrane. Markedly, live-cell imaging in adherent cells showed selective recruitment of full-length N-BAR proteins and isolated N-BAR domains to plasma membrane sub-regions above nanocone stripes. Electron microscopy confirmed that N-BAR domains are recruited to local membrane sites curved by nanocones. We further showed that N-BAR domains are periodically recruited to curved plasma membrane sites during local lamellipodia retraction in the front of migrating cells. Recruitment required myosin-II-generated force applied to plasma-membrane-connected actin cables. Together, our results show that N-BAR domains can be directly recruited to the plasma membrane by external push or internal pull forces that locally curve the plasma membrane.

  View details for DOI 10.1038/ncb2533

  View details for Web of Science ID 000307115900017

  View details for PubMedID 22750946

  View details for PubMedCentralID PMC3519285

• Unconventional Josephson Effect in Hybrid Superconductor-Topological Insulator Devices PHYSICAL REVIEW LETTERS Williams, J. R., Bestwick, A. J., Gallagher, P., Hong, S. S., Cui, Y., Bleich, A. S., Analytis, J. G., Fisher, I. R., Goldhaber-Gordon, D. 2012; 109 (5)

  Abstract

  We report on transport properties of Josephson junctions in hybrid superconducting-topological insulator devices, which show two striking departures from the common Josephson junction behavior: a characteristic energy that scales inversely with the width of the junction, and a low characteristic magnetic field for suppressing supercurrent. To explain these effects, we propose a phenomenological model which expands on the existing theory for topological insulator Josephson junctions.

  View details for DOI 10.1103/PhysRevLett.109.056803

  View details for Web of Science ID 000306944200002

  View details for PubMedID 23006196

• Rechargeable Li-O-2 batteries with a covalently coupled MnCo2O4-graphene hybrid as an oxygen cathode catalyst ENERGY & ENVIRONMENTAL SCIENCE Wang, H., Yang, Y., Liang, Y., Zheng, G., Li, Y., Cui, Y., Dai, H. 2012; 5 (7): 7931-7935

  View details for DOI 10.1039/c2ee21746e

  View details for Web of Science ID 000305530900032

• Improving the cycling stability of silicon nanowire anodes with conducting polymer coatings ENERGY & ENVIRONMENTAL SCIENCE Yao, Y., Liu, N., McDowell, M. T., Pasta, M., Cui, Y. 2012; 5 (7): 7927-7930

  View details for DOI 10.1039/c2ee21437g

  View details for Web of Science ID 000305530900031

• Hierarchical nanostructured conducting polymer hydrogel with high electrochemical activity PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Pan, L., Yu, G., Zhai, D., Lee, H. R., Zhao, W., Liu, N., Wang, H., Tee, B. C., Shi, Y., Cui, Y., Bao, Z. 2012; 109 (24): 9287-9292

  Abstract

  Conducting polymer hydrogels represent a unique class of materials that synergizes the advantageous features of hydrogels and organic conductors and have been used in many applications such as bioelectronics and energy storage devices. They are often synthesized by polymerizing conductive polymer monomer within a nonconducting hydrogel matrix, resulting in deterioration of their electrical properties. Here, we report a scalable and versatile synthesis of multifunctional polyaniline (PAni) hydrogel with excellent electronic conductivity and electrochemical properties. With high surface area and three-dimensional porous nanostructures, the PAni hydrogels demonstrated potential as high-performance supercapacitor electrodes with high specific capacitance (~480 F·g(-1)), unprecedented rate capability, and cycling stability (~83% capacitance retention after 10,000 cycles). The PAni hydrogels can also function as the active component of glucose oxidase sensors with fast response time (~0.3 s) and superior sensitivity (~16.7 μA · mM(-1)). The scalable synthesis and excellent electrode performance of the PAni hydrogel make it an attractive candidate for bioelectronics and future-generation energy storage electrodes.

  View details for DOI 10.1073/pnas.1202636109

  View details for Web of Science ID 000305511300024

  View details for PubMedID 22645374

  View details for PubMedCentralID PMC3386113

• Hybrid Silicon Nanocone-Polymer Solar Cells NANO LETTERS Jeong, S., Garnett, E. C., Wang, S., Yu, Z., Fan, S., Brongersma, M. L., McGehee, M. D., Cui, Y. 2012; 12 (6): 2971-2976

  Abstract

  Recently, hybrid Si/organic solar cells have been studied for low-cost Si photovoltaic devices because the Schottky junction between the Si and organic material can be formed by solution processes at a low temperature. In this study, we demonstrate a hybrid solar cell composed of Si nanocones and conductive polymer. The optimal nanocone structure with an aspect ratio (height/diameter of a nanocone) less than two allowed for conformal polymer surface coverage via spin-coating while also providing both excellent antireflection and light trapping properties. The uniform heterojunction over the nanocones with enhanced light absorption resulted in a power conversion efficiency above 11%. Based on our simulation study, the optimal nanocone structures for a 10 μm thick Si solar cell can achieve a short-circuit current density, up to 39.1 mA/cm(2), which is very close to the theoretical limit. With very thin material and inexpensive processing, hybrid Si nanocone/polymer solar cells are promising as an economically viable alternative energy solution.

  View details for DOI 10.1021/nl300713x

  View details for Web of Science ID 000305106400054

  View details for PubMedID 22545674

• A Yolk-Shell Design for Stabilized and Scalable Li-Ion Battery Alloy Anodes NANO LETTERS Liu, N., Wu, H., McDowell, M. T., Yao, Y., Wang, C., Cui, Y. 2012; 12 (6): 3315-3321

  Abstract

  Silicon is regarded as one of the most promising anode materials for next generation lithium-ion batteries. For use in practical applications, a Si electrode must have high capacity, long cycle life, high efficiency, and the fabrication must be industrially scalable. Here, we design and fabricate a yolk-shell structure to meet all these needs. The fabrication is carried out without special equipment and mostly at room temperature. Commercially available Si nanoparticles are completely sealed inside conformal, thin, self-supporting carbon shells, with rationally designed void space in between the particles and the shell. The well-defined void space allows the Si particles to expand freely without breaking the outer carbon shell, therefore stabilizing the solid-electrolyte interphase on the shell surface. High capacity (∼2800 mAh/g at C/10), long cycle life (1000 cycles with 74% capacity retention), and high Coulombic efficiency (99.84%) have been realized in this yolk-shell structured Si electrode.

  View details for DOI 10.1021/nl3014814

  View details for Web of Science ID 000305106400110

  View details for PubMedID 22551164

• Passivation Coating on Electrospun Copper Nanofibers for Stable Transparent Electrodes ACS NANO Hsu, P., Wu, H., Carney, T. J., McDowell, M. T., Yang, Y., Garnett, E. C., Li, M., Hu, L., Cui, Y. 2012; 6 (6): 5150-5156

  Abstract

  Copper nanofiber networks, which possess the advantages of low cost, moderate flexibility, small sheet resistance, and high transmittance, are one of the most promising candidates to replace indium tin oxide films as the premier transparent electrode. However, the chemical activity of copper nanofibers causes a substantial increase in the sheet resistance after thermal oxidation or chemical corrosion of the nanofibers. In this work, we utilize atomic layer deposition to coat a passivation layer of aluminum-doped zinc oxide (AZO) and aluminum oxide onto electrospun copper nanofibers and remarkably enhance their durability. Our AZO-copper nanofibers show resistance increase of remarkably only 10% after thermal oxidation at 160 °C in dry air and 80 °C in humid air with 80% relative humidity, whereas bare copper nanofibers quickly become insulating. In addition, the coating and baking of the acidic PEDOT:PSS layer on our fibers increases the sheet resistance of bare copper nanofibers by 6 orders of magnitude, while the AZO-Cu nanofibers show an 18% increase.

  View details for DOI 10.1021/nn300844g

  View details for PubMedID 22548313

• High-Efficiency Amorphous Silicon Solar Cell on a Periodic Nanocone Back Reflector ADVANCED ENERGY MATERIALS Hsu, C., Battaglia, C., Pahud, C., Ruan, Z., Haug, F., Fan, S., Ballif, C., Cui, Y. 2012; 2 (6): 628-633

  View details for DOI 10.1002/aenm.201100514

  View details for Web of Science ID 000305179000002

• In Situ X-ray Diffraction Studies of (De)lithiation Mechanism in Silicon Nanowire Anodes ACS NANO Misra, S., Liu, N., Nelson, J., Hong, S. S., Cui, Y., Toney, M. F. 2012; 6 (6): 5465-5473

  Abstract

  Silicon is a promising anode material for Li-ion batteries due to its high theoretical specific capacity. From previous work, silicon nanowires (SiNWs) are known to undergo amorphorization during lithiation, and no crystalline Li-Si product has been observed. In this work, we use an X-ray transparent battery cell to perform in situ synchrotron X-ray diffraction on SiNWs in real time during electrochemical cycling. At deep lithiation voltages the known metastable Li(15)Si(4) phase forms, and we show that avoiding the formation of this phase, by modifying the SiNW growth temperature, improves the cycling performance of SiNW anodes. Our results provide insight on the (de)lithiation mechanism and a correlation between phase evolution and electrochemical performance for SiNW anodes.

  View details for DOI 10.1021/nn301339g

  View details for Web of Science ID 000305661300100

  View details for PubMedID 22558938

• Electrodeposited gold nanoparticles on carbon nanotube-textile: Anode material for glucose alkaline fuel cells ELECTROCHEMISTRY COMMUNICATIONS Pasta, M., Hu, L., La Mantia, F., Cui, Y. 2012; 19: 81-84

  View details for DOI 10.1016/j.elecom.2012.03.019

  View details for Web of Science ID 000305767700022

• High-Density Chemical Intercalation of Zero-Valent Copper into Bi2Se3 Nanoribbons JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Koski, K. J., Cha, J. J., Reed, B. W., Wessells, C. D., Kong, D., Cui, Y. 2012; 134 (18): 7584-7587

  Abstract

  A major goal of intercalation chemistry is to intercalate high densities of guest species without disrupting the host lattice. Many intercalant concentrations, however, are limited by the charge of the guest species. Here we have developed a general solution-based chemical method for intercalating extraordinarily high densities of zero-valent copper metal into layered Bi(2)Se(3) nanoribbons. Up to 60 atom % copper (Cu(7.5)Bi(2)Se(3)) can be intercalated with no disruption to the host lattice using a solution disproportionation redox reaction.

  View details for DOI 10.1021/ja300368x

  View details for Web of Science ID 000303696200003

  View details for PubMedID 22524598

• Stable cycling of double-walled silicon nanotube battery anodes through solid-electrolyte interphase control. Nature nanotechnology Wu, H., Chan, G., Choi, J. W., Ryu, I., Yao, Y., McDowell, M. T., Lee, S. W., Jackson, A., Yang, Y., Hu, L., Cui, Y. 2012; 7 (5): 310-315

  Abstract

  Although the performance of lithium ion-batteries continues to improve, their energy density and cycle life remain insufficient for applications in consumer electronics, transport and large-scale renewable energy storage. Silicon has a large charge storage capacity and this makes it an attractive anode material, but pulverization during cycling and an unstable solid-electrolyte interphase has limited the cycle life of silicon anodes to hundreds of cycles. Here, we show that anodes consisting of an active silicon nanotube surrounded by an ion-permeable silicon oxide shell can cycle over 6,000 times in half cells while retaining more than 85% of their initial capacity. The outer surface of the silicon nanotube is prevented from expansion by the oxide shell, and the expanding inner surface is not exposed to the electrolyte, resulting in a stable solid-electrolyte interphase. Batteries containing these double-walled silicon nanotube anodes exhibit charge capacities approximately eight times larger than conventional carbon anodes and charging rates of up to 20C (a rate of 1C corresponds to complete charge or discharge in one hour).

  View details for DOI 10.1038/nnano.2012.35

  View details for PubMedID 22447161

• The effect of metallic coatings and crystallinity on the volume expansion of silicon during electrochemical lithiation/delithiation NANO ENERGY McDowell, M. T., Lee, S. W., Wang, C., Cui, Y. 2012; 1 (3): 401-410

  View details for DOI 10.1016/j.nanoen.2012.03.004

  View details for Web of Science ID 000318050200010

• Stable cycling of double-walled silicon nanotube battery anodes through solid-electrolyte interphase control NATURE NANOTECHNOLOGY Wu, H., Chan, G., Choi, J. W., Ryu, I., Yao, Y., McDowell, M. T., Lee, S. W., Jackson, A., Yang, Y., Hu, L., Cui, Y. 2012; 7 (5): 309-314

  Abstract

  Although the performance of lithium ion-batteries continues to improve, their energy density and cycle life remain insufficient for applications in consumer electronics, transport and large-scale renewable energy storage. Silicon has a large charge storage capacity and this makes it an attractive anode material, but pulverization during cycling and an unstable solid-electrolyte interphase has limited the cycle life of silicon anodes to hundreds of cycles. Here, we show that anodes consisting of an active silicon nanotube surrounded by an ion-permeable silicon oxide shell can cycle over 6,000 times in half cells while retaining more than 85% of their initial capacity. The outer surface of the silicon nanotube is prevented from expansion by the oxide shell, and the expanding inner surface is not exposed to the electrolyte, resulting in a stable solid-electrolyte interphase. Batteries containing these double-walled silicon nanotube anodes exhibit charge capacities approximately eight times larger than conventional carbon anodes and charging rates of up to 20C (a rate of 1C corresponds to complete charge or discharge in one hour).

  View details for DOI 10.1038/NNANO.2012.35

  View details for Web of Science ID 000303884800009

• Graphene-sponges as high-performance low-cost anodes for microbial fuel cells ENERGY & ENVIRONMENTAL SCIENCE Xie, X., Yu, G., Liu, N., Bao, Z., Criddle, C. S., Cui, Y. 2012; 5 (5): 6862-6866

  View details for DOI 10.1039/c2ee03583a

  View details for Web of Science ID 000303251500019

• In Operando X-ray Diffraction and Transmission X-ray Microscopy of Lithium Sulfur Batteries JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Nelson, J., Misra, S., Yang, Y., Jackson, A., Liu, Y., Wang, H., Dai, H., Andrews, J. C., Cui, Y., Toney, M. F. 2012; 134 (14): 6337-6343

  Abstract

  Rechargeable lithium-sulfur (Li-S) batteries hold great potential for high-performance energy storage systems because they have a high theoretical specific energy, low cost, and are eco-friendly. However, the structural and morphological changes during electrochemical reactions are still not well understood. In this Article, these changes in Li-S batteries are studied in operando by X-ray diffraction and transmission X-ray microscopy. We show recrystallization of sulfur by the end of the charge cycle is dependent on the preparation technique of the sulfur cathode. On the other hand, it was found that crystalline Li(2)S does not form at the end of discharge for all sulfur cathodes studied. Furthermore, during cycling the bulk of soluble polysulfides remains trapped within the cathode matrix. Our results differ from previous ex situ results. This highlights the importance of in operando studies and suggests possible strategies to improve cycle life.

  View details for DOI 10.1021/ja2121926

  View details for Web of Science ID 000302524800043

  View details for PubMedID 22432568

• Energy and environmental nanotechnology in conductive paper and textiles ENERGY & ENVIRONMENTAL SCIENCE Hu, L., Cui, Y. 2012; 5 (4): 6423-6435

  View details for DOI 10.1039/c2ee02414d

  View details for Web of Science ID 000301984200019

• Fracture of crystalline silicon nanopillars during electrochemical lithium insertion PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Lee, S. W., McDowell, M. T., Berla, L. A., Nix, W. D., Cui, Y. 2012; 109 (11): 4080-4085

  Abstract

  From surface hardening of steels to doping of semiconductors, atom insertion in solids plays an important role in modifying chemical, physical, and electronic properties of materials for a variety of applications. High densities of atomic insertion in a solid can result in dramatic structural transformations and associated changes in mechanical behavior: This is particularly evident during electrochemical cycling of novel battery electrodes, such as alloying anodes, conversion oxides, and sulfur and oxygen cathodes. Silicon, which undergoes 400% volume expansion when alloying with lithium, is an extreme case and represents an excellent model system for study. Here, we show that fracture locations are highly anisotropic for lithiation of crystalline Si nanopillars and that fracture is strongly correlated with previously discovered anisotropic expansion. Contrary to earlier theoretical models based on diffusion-induced stresses where fracture is predicted to occur in the core of the pillars during lithiation, the observed cracks are present only in the amorphous lithiated shell. We also show that the critical fracture size is between about 240 and 360 nm and that it depends on the electrochemical reaction rate.

  View details for DOI 10.1073/pnas.1201088109

  View details for Web of Science ID 000301426700019

  View details for PubMedID 22371565

  View details for PubMedCentralID PMC3306693

• Intracellular recording of action potentials by nanopillar electroporation NATURE NANOTECHNOLOGY Xie, C., Lin, Z., Hanson, L., Cui, Y., Cui, B. 2012; 7 (3): 185-190

  Abstract

  Action potentials have a central role in the nervous system and in many cellular processes, notably those involving ion channels. The accurate measurement of action potentials requires efficient coupling between the cell membrane and the measuring electrodes. Intracellular recording methods such as patch clamping involve measuring the voltage or current across the cell membrane by accessing the cell interior with an electrode, allowing both the amplitude and shape of the action potentials to be recorded faithfully with high signal-to-noise ratios. However, the invasive nature of intracellular methods usually limits the recording time to a few hours, and their complexity makes it difficult to simultaneously record more than a few cells. Extracellular recording methods, such as multielectrode arrays and multitransistor arrays, are non-invasive and allow long-term and multiplexed measurements. However, extracellular recording sacrifices the one-to-one correspondence between the cells and electrodes, and also suffers from significantly reduced signal strength and quality. Extracellular techniques are not, therefore, able to record action potentials with the accuracy needed to explore the properties of ion channels. As a result, the pharmacological screening of ion-channel drugs is usually performed by low-throughput intracellular recording methods. The use of nanowire transistors, nanotube-coupled transistors and micro gold-spine and related electrodes can significantly improve the signal strength of recorded action potentials. Here, we show that vertical nanopillar electrodes can record both the extracellular and intracellular action potentials of cultured cardiomyocytes over a long period of time with excellent signal strength and quality. Moreover, it is possible to repeatedly switch between extracellular and intracellular recording by nanoscale electroporation and resealing processes. Furthermore, vertical nanopillar electrodes can detect subtle changes in action potentials induced by drugs that target ion channels.

  View details for DOI 10.1038/NNANO.2012.8

  View details for Web of Science ID 000301186300012

  View details for PubMedID 22327876

  View details for PubMedCentralID PMC3356686

• Light Trapping in Solar Cells: Can Periodic Beat Random? ACS NANO Battaglia, C., Hsu, C., Soederstroem, K., Escarre, J., Haug, F., Charriere, M., Boccard, M., Despeisse, M., Alexander, D. T., Cantoni, M., Cui, Y., Ballif, C. 2012; 6 (3): 2790-2797

  Abstract

  Theory predicts that periodic photonic nanostructures should outperform their random counterparts in trapping light in solar cells. However, the current certified world-record conversion efficiency for amorphous silicon thin-film solar cells, which strongly rely on light trapping, was achieved on the random pyramidal morphology of transparent zinc oxide electrodes. Based on insights from waveguide theory, we develop tailored periodic arrays of nanocavities on glass fabricated by nanosphere lithography, which enable a cell with a remarkable short-circuit current density of 17.1 mA/cm(2) and a high initial efficiency of 10.9%. A direct comparison with a cell deposited on the random pyramidal morphology of state-of-the-art zinc oxide electrodes, replicated onto glass using nanoimprint lithography, demonstrates unambiguously that periodic structures rival random textures.

  View details for DOI 10.1021/nn300287j

  View details for Web of Science ID 000301945900098

  View details for PubMedID 22375932

• Exotic Topological Insulator States and Topological Phase Transitions in Sb2Se3-Bi2Se3 Heterostructures ACS NANO Zhang, Q., Zhang, Z., Zhu, Z., Schwingenschloegl, U., Cui, Y. 2012; 6 (3): 2345-2352

  Abstract

  Topological insulator is a new state of matter attracting tremendous interest due to its gapless linear dispersion and spin momentum locking topological states located near the surface. Heterostructures, which have traditionally been powerful in controlling the electronic properties of semiconductor devices, are interesting for topological insulators. Here, we studied the spatial distribution of the topological state in Sb(2)Se(3)-Bi(2)Se(3) heterostructures by first-principle simulation and discovered that an exotic topological state exists. Surprisingly, the state migrates from the nontrivial Bi(2)Se(3) into the trivial Sb(2)Se(3) region and spreads across the entire Sb(2)Se(3) slab, extending beyond the concept of "surface" state while preserving all of the topological surface state characteristics. This unusual topological state arises from the coupling between different materials and the modification of electronic structure near Fermi energy. Our study demonstrates that heterostructures can open up opportunities for controlling the real-space distribution of the topological state and inducing quantum phase transitions between topologically trivial and nontrivial states.

  View details for DOI 10.1021/nn2045328

  View details for Web of Science ID 000301945900048

  View details for PubMedID 22339126

• Ultra-low carrier concentration and surface-dominant transport in antimony-doped Bi2Se3 topological insulator nanoribbons NATURE COMMUNICATIONS Hong, S. S., Cha, J. J., Kong, D., Cui, Y. 2012; 3

  Abstract

  A topological insulator is the state of quantum matter possessing gapless spin-locking surface states across the bulk band gap, which has created new opportunities from novel electronics to energy conversion. However, the large concentration of bulk residual carriers has been a major challenge for revealing the property of the topological surface state by electron transport measurements. Here we report the surface-state-dominant transport in antimony-doped, zinc oxide-encapsulated Bi(2)Se(3) nanoribbons with suppressed bulk electron concentration. In the nanoribbon with sub-10-nm thickness protected by a zinc oxide layer, we position the Fermi levels of the top and bottom surfaces near the Dirac point by electrostatic gating, achieving extremely low two-dimensional carrier concentration of 2×10(11) cm(-2). The zinc oxide-capped, antimony-doped Bi(2)Se(3) nanostructures provide an attractive materials platform to study fundamental physics in topological insulators, as well as future applications.

  View details for DOI 10.1038/ncomms1771

  View details for Web of Science ID 000302630100046

  View details for PubMedID 22453830

• Self-limited plasmonic welding of silver nanowire junctions NATURE MATERIALS Garnett, E. C., Cai, W., Cha, J. J., Mahmood, F., Connor, S. T., Christoforo, M. G., Cui, Y., McGehee, M. D., Brongersma, M. L. 2012; 11 (3): 241-249

  Abstract

  Nanoscience provides many strategies to construct high-performance materials and devices, including solar cells, thermoelectrics, sensors, transistors, and transparent electrodes. Bottom-up fabrication facilitates large-scale chemical synthesis without the need for patterning and etching processes that waste material and create surface defects. However, assembly and contacting procedures still require further development. Here, we demonstrate a light-induced plasmonic nanowelding technique to assemble metallic nanowires into large interconnected networks. The small gaps that form naturally at nanowire junctions enable effective light concentration and heating at the point where the wires need to be joined together. The extreme sensitivity of the heating efficiency on the junction geometry causes the welding process to self-limit when a physical connection between the wires is made. The localized nature of the heating prevents damage to low-thermal-budget substrates such as plastics and polymer solar cells. This work opens new avenues to control light, heat and mass transport at the nanoscale.

  View details for DOI 10.1038/NMAT3238

  View details for Web of Science ID 000300625500025

  View details for PubMedID 22306769

• Absorption Enhancement in Ultrathin Crystalline Silicon Solar Cells with Antireflection and Light-Trapping Nanocone Gratings NANO LETTERS Wang, K. X., Yu, Z., Liu, V., Cui, Y., Fan, S. 2012; 12 (3): 1616-1619

  Abstract

  Enhancing the light absorption in ultrathin-film silicon solar cells is important for improving efficiency and reducing cost. We introduce a double-sided grating design, where the front and back surfaces of the cell are separately optimized for antireflection and light trapping, respectively. The optimized structure yields a photocurrent of 34.6 mA/cm(2) at an equivalent thickness of 2 μm, close to the Yablonovitch limit. This approach is applicable to various thicknesses and is robust against metallic loss in the back reflector.

  View details for DOI 10.1021/nl204550q

  View details for Web of Science ID 000301406800086

  View details for PubMedID 22356436

• High-Mobility Field-Effect Transistors from Large-Area Solution-Grown Aligned C-60 Single Crystals JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Li, H., Tee, B. C., Cha, J. J., Cui, Y., Chung, J. W., Lee, S. Y., Bao, Z. 2012; 134 (5): 2760-2765

  Abstract

  Field-effect transistors based on single crystals of organic semiconductors have the highest reported charge carrier mobility among organic materials, demonstrating great potential of organic semiconductors for electronic applications. However, single-crystal devices are difficult to fabricate. One of the biggest challenges is to prepare dense arrays of single crystals over large-area substrates with controlled alignment. Here, we describe a solution processing method to grow large arrays of aligned C(60) single crystals. Our well-aligned C(60) single-crystal needles and ribbons show electron mobility as high as 11 cm(2)V(-1)s(-1) (average mobility: 5.2 ± 2.1 cm(2)V(-1)s(-1) from needles; 3.0 ± 0.87 cm(2)V(-1)s(-1) from ribbons). This observed mobility is ~8-fold higher than the maximum reported mobility for solution-grown n-channel organic materials (1.5 cm(2)V(-1)s(-1)) and is ~2-fold higher than the highest mobility of any n-channel organic material (~6 cm(2)V(-1)s(-1)). Furthermore, our deposition method is scalable to a 100 mm wafer substrate, with around 50% of the wafer surface covered by aligned crystals. Hence, our method facilitates the fabrication of large amounts of high-quality semiconductor crystals for fundamental studies, and with substantial improvement on the surface coverage of crystals, this method might be suitable for large-area applications based on single crystals of organic semiconductors.

  View details for DOI 10.1021/ja210430b

  View details for Web of Science ID 000300460600049

  View details for PubMedID 22239604

• Weak Antilocalization in Bi-2(SexTe1-x)(3) Nanoribbons and Nanoplates NANO LETTERS Cha, J. J., Kong, D., Hong, S., Analytis, J. G., Lai, K., Cui, Y. 2012; 12 (2): 1107-1111

  Abstract

  Studying the surface states of Bi(2)Se(3) and Bi(2)Te(3) topological insulators has proven challenging due to the high bulk carrier density that masks the surface states. Ternary compound Bi(2)(Se(x)Te(1-x))(3) may present a solution to the current materials challenge by lowering the bulk carrier mobility significantly. Here, we synthesized Bi(2)(Se(x)Te(1-x))(3) nanoribbons and nanoplates via vapor-liquid-solid and vapor-solid growth methods where the atomic ratio x was controlled by the molecular ratio of Bi(2)Se(3) to Bi(2)Te(3) in the source mixture and ranged between 0 and 1. For the whole range of x, the ternary nanostructures are single crystalline without phase segregation, and their carrier densities decrease with x. However, the lowest electron density is still high (~10(19) cm(-3)) and the mobility low, suggesting that the majority of these carriers may come from impurity states. Despite the high carrier density, weak antilocalization (WAL) is clearly observed. Angle-dependent magnetoconductance study shows that an appropriate magnetic field range is critical to capture a true, two-dimensional (2D) WAL effect, and a fit to the 2D localization theory gives α of -0.97, suggesting its origin may be the topological surface states. The power law dependence of the dephasing length on temperature is ~T(-0.49) within the appropriate field range (~0.3 T), again reflecting the 2D nature of the WAL. Careful analysis on WAL shows how the surface states and the bulk/impurity states may interact with each other.

  View details for DOI 10.1021/nl300018j

  View details for Web of Science ID 000299967800098

  View details for PubMedID 22263839

• Engineering Empty Space between Si Nanoparticles for Lithium-Ion Battery Anodes NANO LETTERS Wu, H., Zheng, G., Liu, N., Carney, T. J., Yang, Y., Cui, Y. 2012; 12 (2): 904-909

  Abstract

  Silicon is a promising high-capacity anode material for lithium-ion batteries yet attaining long cycle life remains a significant challenge due to pulverization of the silicon and unstable solid-electrolyte interphase (SEI) formation during the electrochemical cycles. Despite significant advances in nanostructured Si electrodes, challenges including short cycle life and scalability hinder its widespread implementation. To address these challenges, we engineered an empty space between Si nanoparticles by encapsulating them in hollow carbon tubes. The synthesis process used low-cost Si nanoparticles and electrospinning methods, both of which can be easily scaled. The empty space around the Si nanoparticles allowed the electrode to successfully overcome these problems Our anode demonstrated a high gravimetric capacity (~1000 mAh/g based on the total mass) and long cycle life (200 cycles with 90% capacity retention).

  View details for DOI 10.1021/nl203967r

  View details for PubMedID 22224827

• TOPOLOGICAL INSULATORS The surface surfaces NATURE NANOTECHNOLOGY Cha, J. J., Cui, Y. 2012; 7 (2): 85-86

  View details for DOI 10.1038/nnano.2012.9

  View details for Web of Science ID 000300398900005

  View details for PubMedID 22306896

• Broadband light management using low-Q whispering gallery modes in spherical nanoshells NATURE COMMUNICATIONS Yao, Y., Yao, J., Narasimhan, V. K., Ruan, Z., Xie, C., Fan, S., Cui, Y. 2012; 3

  Abstract

  Light trapping across a wide band of frequencies is important for applications such as solar cells and photodetectors. Here, we demonstrate a new approach to light management by forming whispering-gallery resonant modes inside a spherical nanoshell structure. The geometry of the structure gives rise to a low quality-factor, facilitating the coupling of light into the resonant modes and substantial enhancement of the light path in the active material, thus dramatically improving absorption. Using nanocrystalline silicon (nc-Si) as a model system, we observe broadband absorption enhancement across a large range of incident angles. The absorption of a single layer of 50-nm-thick spherical nanoshells is equivalent to a 1-μm-thick planar nc-Si film. This light-trapping structure could enable the manufacturing of high-throughput ultra-thin film absorbers in a variety of material systems that demand shorter deposition time, less material usage and transferability to flexible substrates.

  View details for DOI 10.1038/ncomms1664

  View details for PubMedID 22314360

• Functionalization of silicon nanowire surfaces with metal-organic frameworks NANO RESEARCH Liu, N., Yao, Y., Cha, J. J., McDowell, M. T., Han, Y., Cui, Y. 2012; 5 (2): 109-116

  View details for DOI 10.1007/s12274-011-0190-1

  View details for Web of Science ID 000300315500005

• A Desalination Battery NANO LETTERS Pasta, M., Wessells, C. D., Cui, Y., La Mantia, F. 2012; 12 (2): 839-843

  Abstract

  Water desalination is an important approach to provide fresh water around the world, although its high energy consumption, and thus high cost, call for new, efficient technology. Here, we demonstrate the novel concept of a "desalination battery", which operates by performing cycles in reverse on our previously reported mixing entropy battery. Rather than generating electricity from salinity differences, as in mixing entropy batteries, desalination batteries use an electrical energy input to extract sodium and chloride ions from seawater and to generate fresh water. The desalination battery is comprised by a Na(2-x)Mn(5)O(10) nanorod positive electrode and Ag/AgCl negative electrode. Here, we demonstrate an energy consumption of 0.29 Wh l(-1) for the removal of 25% salt using this novel desalination battery, which is promising when compared to reverse osmosis (~ 0.2 Wh l(-1)), the most efficient technique presently available.

  View details for DOI 10.1021/nl203889e

  View details for Web of Science ID 000299967800052

  View details for PubMedID 22268456

• Tunable Reaction Potentials in Open Framework Nanoparticle Battery Electrodes for Grid-Scale Energy Storage ACS NANO Wessells, C. D., McDowell, M. T., Peddada, S. V., Pasta, M., Huggins, R. A., Cui, Y. 2012; 6 (2): 1688-1694

  Abstract

  The electrical energy grid has a growing need for energy storage to address short-term transients, frequency regulation, and load leveling. Though electrochemical energy storage devices such as batteries offer an attractive solution, current commercial battery technology cannot provide adequate power, and cycle life, and energy efficiency at a sufficiently low cost. Copper hexacyanoferrate and nickel hexacyanoferrate, two open framework materials with the Prussian Blue structure, were recently shown to offer ultralong cycle life and high-rate performance when operated as battery electrodes in safe, inexpensive aqueous sodium ion and potassium ion electrolytes. In this report, we demonstrate that the reaction potential of copper-nickel alloy hexacyanoferrate nanoparticles may be tuned by controlling the ratio of copper to nickel in these materials. X-ray diffraction, TEM energy dispersive X-ray spectroscopy, and galvanostatic electrochemical cycling of copper-nickel hexacyanoferrate reveal that copper and nickel form a fully miscible solution at particular sites in the framework without perturbing the structure. This allows copper-nickel hexacyanoferrate to reversibly intercalate sodium and potassium ions for over 2000 cycles with capacity retentions of 100% and 91%, respectively. The ability to precisely tune the reaction potential of copper-nickel hexacyanoferrate without sacrificing cycle life will allow the development of full cells that utilize the entire electrochemical stability window of aqueous sodium and potassium ion electrolytes.

  View details for DOI 10.1021/nn204666v

  View details for Web of Science ID 000300757900079

  View details for PubMedID 22283739

• Nanosecond in situ transmission electron microscope studies of the reversible Ge2Sb2Te5 crystalline double left right arrow amorphous phase transformation JOURNAL OF APPLIED PHYSICS Santala, M. K., Reed, B. W., Topuria, T., Raoux, S., Meister, S., Cui, Y., LaGrange, T., Campbell, G. H., Browning, N. D. 2012; 111 (2)

  View details for DOI 10.1063/1.3678447

  View details for Web of Science ID 000299792400078

• Nanofabricated optical and detector elements for light-field camera sensors Conference on Nanoengineering - Fabrication, Properties, Optics, and Devices IX Narasimhan, V. K., Cui, Y. SPIE-INT SOC OPTICAL ENGINEERING. 2012

  View details for DOI 10.1117/12.929264

  View details for Web of Science ID 000312959400008

• The surface surfaces Nature Nanotechnology Cha, J., J., Cui, Y. 2012; 7: 85-86
• High-capacity micrometer-sized Li(2)S particles as cathode materials for advanced rechargeable lithium-ion batteries JACS Yang, Y., Zheng, G., Misra, S., Nelson, J., Toney, M., F., Cui, Y. 2012; 37 (134): 15387-94
• Antimicrobial Nanomaterials for Water Disinfection in Nano-Antimicrobials Liu, C., Xie, X., Cui, Y. 2012: 465-494
• GaAs thin film nanostructure arrays for III-V solar cell applications Conference on Photonic and Phononic Properties of Engineered Nanostructures II Liang, D., Kang, Y., Huo, Y., Wang, K. X., Gu, A., Tan, M., Yu, Z., Lia, S., Jia, J., Bao, X., Wang, S., Yao, Y., Fan, S., Cui, Y., Harris, J. SPIE-INT SOC OPTICAL ENGINEERING. 2012

  View details for DOI 10.1117/12.909743

  View details for Web of Science ID 000302582400036

• The Effect of Insertion Species on Nanostructured Open Framework Hexacyanoferrate Battery Electrodes JOURNAL OF THE ELECTROCHEMICAL SOCIETY Wessells, C. D., Peddada, S. V., McDowell, M. T., Huggins, R. A., Cui, Y. 2012; 159 (2): A98-A103

  View details for DOI 10.1149/2.060202jes

  View details for Web of Science ID 000298637500005

• Carbon nanotube-coated macroporous sponge for microbial fuel cell electrodes ENERGY & ENVIRONMENTAL SCIENCE Xie, X., Ye, M., Hu, L., Liu, N., McDonough, J. R., Chen, W., Alshareef, H. N., Criddle, C. S., Cui, Y. 2012; 5 (1): 5265-5270

  View details for DOI 10.1039/c1ee02122b

  View details for Web of Science ID 000299046100016

• Nickel Hexacyanoferrate Nanoparticle Electrodes For Aqueous Sodium and Potassium Ion Batteries NANO LETTERS Wessells, C. D., Peddada, S. V., Huggins, R. A., Cui, Y. 2011; 11 (12): 5421-5425

  Abstract

  The electrical power grid faces a growing need for large-scale energy storage over a wide range of time scales due to costly short-term transients, frequency regulation, and load balancing. The durability, high power, energy efficiency, and low cost needed for grid-scale storage pose substantial challenges for conventional battery technology. (1, 2) Here, we demonstrate insertion/extraction of sodium and potassium ions in a low-strain nickel hexacyanoferrate electrode material for at least five thousand deep cycles at high current densities in inexpensive aqueous electrolytes. Its open-framework structure allows retention of 66% of the initial capacity even at a very high (41.7C) rate. At low current densities, its round trip energy efficiency reaches 99%. This low-cost material is readily synthesized in bulk quantities. The long cycle life, high power, good energy efficiency, safety, and inexpensive production method make nickel hexacyanoferrate an attractive candidate for use in large-scale batteries to support the electrical grid.

  View details for DOI 10.1021/nl203193q

  View details for Web of Science ID 000297950200055

  View details for PubMedID 22043814

• High-Performance Nanostructured Supercapacitors on a Sponge NANO LETTERS Chen, W., Rakhi, R. B., Hu, L., Xie, X., Cui, Y., Alshareef, H. N. 2011; 11 (12): 5165-5172

  Abstract

  A simple and scalable method has been developed to fabricate nanostructured MnO2-carbon nanotube (CNT)-sponge hybrid electrodes. A novel supercapacitor, henceforth referred to as "sponge supercapacitor", has been fabricated using these hybrid electrodes with remarkable performance. A specific capacitance of 1,230 F/g (based on the mass of MnO2) can be reached. Capacitors based on CNT-sponge substrates (without MnO2) can be operated even under a high scan rate of 200 V/s, and they exhibit outstanding cycle performance with only 2% degradation after 100,000 cycles under a scan rate of 10 V/s. The MnO2-CNT-sponge supercapacitors show only 4% of degradation after 10,000 cycles at a charge-discharge specific current of 5 A/g. The specific power and energy of the MnO2-CNT-sponge supercapacitors are high with values of 63 kW/kg and 31 Wh/kg, respectively. The attractive performances exhibited by these sponge supercapacitors make them potentially promising candidates for future energy storage systems.

  View details for DOI 10.1021/nl2023433

  View details for Web of Science ID 000297950200012

  View details for PubMedID 21923166

• Lithium-Ion Textile Batteries with Large Areal Mass Loading ADVANCED ENERGY MATERIALS Hu, L., La Mantia, F., Wu, H., Xie, X., McDonough, J., Pasta, M., Cui, Y. 2011; 1 (6): 1012-1017

  View details for DOI 10.1002/aenm.201100261

  View details for Web of Science ID 000297056500005

• Ambipolar field effect in the ternary topological insulator (BixSb1-x)(2)Te-3 by composition tuning NATURE NANOTECHNOLOGY Kong, D., Chen, Y., Cha, J. J., Zhang, Q., Analytis, J. G., Lai, K., Liu, Z., Hong, S. S., Koski, K. J., Mo, S., Hussain, Z., Fisher, I. R., Shen, Z., Cui, Y. 2011; 6 (11): 705-709

  Abstract

  Topological insulators exhibit a bulk energy gap and spin-polarized surface states that lead to unique electronic properties, with potential applications in spintronics and quantum information processing. However, transport measurements have typically been dominated by residual bulk charge carriers originating from crystal defects or environmental doping, and these mask the contribution of surface carriers to charge transport in these materials. Controlling bulk carriers in current topological insulator materials, such as the binary sesquichalcogenides Bi2Te3, Sb2Te3 and Bi2Se3, has been explored extensively by means of material doping and electrical gating, but limited progress has been made to achieve nanostructures with low bulk conductivity for electronic device applications. Here we demonstrate that the ternary sesquichalcogenide (Bi(x)Sb(1-x))2Te3 is a tunable topological insulator system. By tuning the ratio of bismuth to antimony, we are able to reduce the bulk carrier density by over two orders of magnitude, while maintaining the topological insulator properties. As a result, we observe a clear ambipolar gating effect in (Bi(x)Sb(1-x))2Te3 nanoplate field-effect transistor devices, similar to that observed in graphene field-effect transistor devices. The manipulation of carrier type and density in topological insulator nanostructures demonstrated here paves the way for the implementation of topological insulators in nanoelectronics and spintronics.

  View details for DOI 10.1038/NNANO.2011.172

  View details for Web of Science ID 000296737300007

  View details for PubMedID 21963714

• Opportunities in chemistry and materials science for topological insulators and their nanostructures NATURE CHEMISTRY Kong, D., Cui, Y. 2011; 3 (11): 845-849

  Abstract

  Electrical charges on the boundaries of topological insulators favour forward motion over back-scattering at impurities, producing low-dissipation, metallic states that exist up to room temperature in ambient conditions. These states have the promise to impact a broad range of applications from electronics to the production of energy, which is one reason why topological insulators have become the rising star in condensed-matter physics. There are many challenges in the processing of these exotic materials to use the metallic states in functional devices, and they present great opportunities for the chemistry and materials science research communities.

  View details for DOI 10.1038/NCHEM.1171

  View details for Web of Science ID 000296540100008

  View details for PubMedID 22024879

• Copper hexacyanoferrate battery electrodes with long cycle life and high power NATURE COMMUNICATIONS Wessells, C. D., Huggins, R. A., Cui, Y. 2011; 2

  Abstract

  Short-term transients, including those related to wind and solar sources, present challenges to the electrical grid. Stationary energy storage systems that can operate for many cycles, at high power, with high round-trip energy efficiency, and at low cost are required. Existing energy storage technologies cannot satisfy these requirements. Here we show that crystalline nanoparticles of copper hexacyanoferrate, which has an ultra-low strain open framework structure, can be operated as a battery electrode in inexpensive aqueous electrolytes. After 40,000 deep discharge cycles at a 17 C rate, 83% of the original capacity of copper hexacyanoferrate is retained. Even at a very high cycling rate of 83 C, two thirds of its maximum discharge capacity is observed. At modest current densities, round-trip energy efficiencies of 99% can be achieved. The low-cost, scalable, room-temperature co-precipitation synthesis and excellent electrode performance of copper hexacyanoferrate make it attractive for large-scale energy storage systems.

  View details for DOI 10.1038/ncomms1563

  View details for Web of Science ID 000297686500037

  View details for PubMedID 22109524

• Improving the Performance of Lithium-Sulfur Batteries by Conductive Polymer Coating ACS NANO Yang, Y., Yu, G., Cha, J. J., Wu, H., Vosgueritchian, M., Yao, Y., Bao, Z., Cui, Y. 2011; 5 (11): 9187-9193

  View details for DOI 10.1021/nn203436j

  View details for PubMedID 21995642

• Symmetrical MnO2-Carbon Nanotube-Textile Nanostructures for Wearable Pseudocapacitors with High Mass Loading ACS NANO Hu, L., Chen, W., Xie, X., Liu, N., Yang, Y., Wu, H., Yao, Y., Pasta, M., Alshareef, H. N., Cui, Y. 2011; 5 (11): 8904-8913

  Abstract

  While MnO(2) is a promising material for pseudocapacitor applications due to its high specific capacity and low cost, MnO(2) electrodes suffer from their low electrical and ionic conductivities. In this article, we report a structure where MnO(2) nanoflowers were conformally electrodeposited onto carbon nanotube (CNT)-enabled conductive textile fibers. Such nanostructures effectively decrease the ion diffusion and charge transport resistance in the electrode. For a given areal mass loading, the thickness of MnO(2) on conductive textile fibers is much smaller than that on a flat metal substrate. Such a porous structure also allows a large mass loading, up to 8.3 mg/cm(2), which leads to a high areal capacitance of 2.8 F/cm(2) at a scan rate of 0.05 mV/s. Full cells were demonstrated, where the MnO(2)-CNT-textile was used as a positive electrode, reduced MnO(2)-CNT-textile as a negative electrode, and 0.5 M Na(2)SO(4) in water as the electrolyte. The resulting pseudocapacitor shows promising results as a low-cost energy storage solution and an attractive wearable power.

  View details for DOI 10.1021/nn203085j

  View details for PubMedID 21923135

• Single Nanostructure Electrochemical Devices for Studying Electronic Properties and Structural Changes in Lithiated Si Nanowires ADVANCED ENERGY MATERIALS McDowell, M. T., Cui, Y. 2011; 1 (5): 894-900

  View details for DOI 10.1002/aenm.201100258

  View details for Web of Science ID 000295140100026

• Highly Conductive, Mechanically Robust, and Electrochemically Inactive TiC/C Nanofiber Scaffold for High-Performance Silicon Anode Batteries ACS NANO Yao, Y., Huo, K., Hu, L., Liu, N., Ha, J. J., McDowell, M. T., Chu, P. K., Cui, Y. 2011; 5 (10): 8346-8351

  Abstract

  Silicon has a high specific capacity of 4200 mAh/g as lithium-ion battery anodes, but its rapid capacity fading due to >300% volume expansion and pulverization presents a significant challenge for practical applications. Here we report a core-shell TiC/C/Si inactive/active nanocomposite for Si anodes demonstrating high specific capacity and excellent electrochemical cycling. The amorphous silicon layer serves as the active material to store Li(+), while the inactive TiC/C nanofibers act as a conductive and mechanically robust scaffold for electron transport during the Li-Si alloying process. The core-shell TiC/C/Si nanocomposite anode shows ∼3000 mAh g(-1) discharge capacity and 92% capacity retention after 100 charge/discharge cycles. The excellent cycling stability and high rate performance could be attributed to the tapering of the nanofibers and the open structure that allows facile Li ion transport and the high conductivity and mechanical stability of the TiC/C scaffold.

  View details for DOI 10.1021/nn2033693

  View details for Web of Science ID 000296208700090

  View details for PubMedID 21974912

• Metal nanogrids, nanowires, and nanofibers for transparent electrodes MRS BULLETIN Hu, L., Wu, H., Cui, Y. 2011; 36 (10): 760-765

  View details for DOI 10.1557/mrs.2011.234

  View details for Web of Science ID 000296090400010

• Hollow Carbon Nanofiber-Encapsulated Sulfur Cathodes for High Specific Capacity Rechargeable Lithium Batteries NANO LETTERS Zheng, G., Yang, Y., Cha, J. J., Hong, S. S., Cui, Y. 2011; 11 (10): 4462-4467

  Abstract

  Sulfur has a high specific capacity of 1673 mAh/g as lithium battery cathodes, but its rapid capacity fading due to polysulfides dissolution presents a significant challenge for practical applications. Here we report a hollow carbon nanofiber-encapsulated sulfur cathode for effective trapping of polysulfides and demonstrate experimentally high specific capacity and excellent electrochemical cycling of the cells. The hollow carbon nanofiber arrays were fabricated using anodic aluminum oxide (AAO) templates, through thermal carbonization of polystyrene. The AAO template also facilitates sulfur infusion into the hollow fibers and prevents sulfur from coating onto the exterior carbon wall. The high aspect ratio of the carbon nanofibers provides an ideal structure for trapping polysulfides, and the thin carbon wall allows rapid transport of lithium ions. The small dimension of these nanofibers provides a large surface area per unit mass for Li(2)S deposition during cycling and reduces pulverization of electrode materials due to volumetric expansion. A high specific capacity of about 730 mAh/g was observed at C/5 rate after 150 cycles of charge/discharge. The introduction of LiNO(3) additive to the electrolyte was shown to improve the Coulombic efficiency to over 99% at C/5. The results show that the hollow carbon nanofiber-encapsulated sulfur structure could be a promising cathode design for rechargeable Li/S batteries with high specific energy.

  View details for DOI 10.1021/nl2027684

  View details for PubMedID 21916442

• Enhancing the Supercapacitor Performance of Graphene/MnO2 Nanostructured Electrodes by Conductive Wrapping NANO LETTERS Yu, G., Hu, L., Liu, N., Wang, H., Vosgueritchian, M., Yang, Y., Cui, Y., Bao, Z. 2011; 11 (10): 4438-4442

  Abstract

  MnO2 is considered one of the most promising pseudocapactive materials for high-performance supercapacitors given its high theoretical specific capacitance, low-cost, environmental benignity, and natural abundance. However, MnO2 electrodes often suffer from poor electronic and ionic conductivities, resulting in their limited performance in power density and cycling. Here we developed a "conductive wrapping" method to greatly improve the supercapacitor performance of graphene/MnO2-based nanostructured electrodes. By three-dimensional (3D) conductive wrapping of graphene/MnO2 nanostructures with carbon nanotubes or conducting polymer, specific capacitance of the electrodes (considering total mass of active materials) has substantially increased by ∼20% and ∼45%, respectively, with values as high as ∼380 F/g achieved. Moreover, these ternary composite electrodes have also exhibited excellent cycling performance with >95% capacitance retention over 3000 cycles. This 3D conductive wrapping approach represents an exciting direction for enhancing the device performance of metal oxide-based electrochemical supercapacitors and can be generalized for designing next-generation high-performance energy storage devices.

  View details for DOI 10.1021/nl2026635

  View details for PubMedID 21942427

• Size-dependent fracture of Si nanowire battery anodes JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS Ryu, I., Choi, J. W., Cui, Y., Nix, W. D. 2011; 59 (9): 1717-1730

  View details for DOI 10.1016/j.jmps.2011.06.003

  View details for Web of Science ID 000295064300004

• Novel Size and Surface Oxide Effects in Silicon Nanowires as Lithium Battery Anodes NANO LETTERS McDowell, M. T., Lee, S. W., Ryu, I., Wu, H., Nix, W. D., Choi, J. W., Cui, Y. 2011; 11 (9): 4018-4025

  Abstract

  With its high specific capacity, silicon is a promising anode material for high-energy lithium-ion batteries, but volume expansion and fracture during lithium reaction have prevented implementation. Si nanostructures have shown resistance to fracture during cycling, but the critical effects of nanostructure size and native surface oxide on volume expansion and cycling performance are not understood. Here, we use an ex situ transmission electron microscopy technique to observe the same Si nanowires before and after lithiation and have discovered the impacts of size and surface oxide on volume expansion. For nanowires with native SiO(2), the surface oxide can suppress the volume expansion during lithiation for nanowires with diameters <∼50 nm. Finite element modeling shows that the oxide layer can induce compressive hydrostatic stress that could act to limit the extent of lithiation. The understanding developed herein of how volume expansion and extent of lithiation can depend on nanomaterial structure is important for the improvement of Si-based anodes.

  View details for DOI 10.1021/nl202630n

  View details for PubMedID 21827158

• Paper supercapacitors by a solvent-free drawing method ENERGY & ENVIRONMENTAL SCIENCE Zheng, G., Hu, L., Wu, H., Xie, X., Cui, Y. 2011; 4 (9): 3368-3373

  View details for DOI 10.1039/c1ee01853a

  View details for Web of Science ID 000294306900024

• Transparent lithium-ion batteries PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Yang, Y., Jeong, S., Hu, L., Wu, H., Lee, S. W., Cui, Y. 2011; 108 (32): 13013-13018

  Abstract

  Transparent devices have recently attracted substantial attention. Various applications have been demonstrated, including displays, touch screens, and solar cells; however, transparent batteries, a key component in fully integrated transparent devices, have not yet been reported. As battery electrode materials are not transparent and have to be thick enough to store energy, the traditional approach of using thin films for transparent devices is not suitable. Here we demonstrate a grid-structured electrode to solve this dilemma, which is fabricated by a microfluidics-assisted method. The feature dimension in the electrode is below the resolution limit of human eyes, and, thus, the electrode appears transparent. Moreover, by aligning multiple electrodes together, the amount of energy stored increases readily without sacrificing the transparency. This results in a battery with energy density of 10 Wh/L at a transparency of 60%. The device is also flexible, further broadening their potential applications. The transparent device configuration also allows in situ Raman study of fundamental electrochemical reactions in batteries.

  View details for DOI 10.1073/pnas.1102873108

  View details for PubMedID 21788483

• Prelithiated Silicon Nanowires as an Anode for Lithium Ion Batteries ACS NANO Liu, N., Hu, L., McDowell, M. T., Jackson, A., Cui, Y. 2011; 5 (8): 6487-6493

  Abstract

  Silicon is one of the most promising anode materials for the next-generation high-energy lithium ion battery (LIB), while sulfur and some other lithium-free materials have recently shown high promise as cathode materials. To make a full battery out of them, either the cathode or the anode needs to be prelithiated. Here, we present a method for prelithiating a silicon nanowire (SiNW) anode by a facile self-discharge mechanism. Through a time dependence study, we found that 20 min of prelithiation loads ∼50% of the full capacity into the SiNWs. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) studies show that the nanostructure of SiNWs is maintained after prelithiation. We constructed a full battery using our prelithiated SiNW anode with a sulfur cathode. Our work provides a protocol for pairing lithium-free electrodes to make the next-generation high-energy LIB.

  View details for DOI 10.1021/nn2017167

  View details for Web of Science ID 000294085400049

  View details for PubMedID 21711012

• Improved Solid Oxide Fuel Cell Performance with Nanostructured Electrolytes ACS NANO Chao, C., Hsu, C., Cui, Y., Prinz, F. B. 2011; 5 (7): 5692-5696

  Abstract

  Considerable attention has been focused on solid oxide fuel cells (SOFCs) due to their potential for providing clean and reliable electric power. However, the high operating temperatures of current SOFCs limit their adoption in mobile applications. To lower the SOFC operating temperature, we fabricated a corrugated thin-film electrolyte membrane by nanosphere lithography and atomic layer deposition to reduce the polarization and ohmic losses at low temperatures. The resulting micro-SOFC electrolyte membrane showed a hexagonal-pyramid array nanostructure and achieved a power density of 1.34 W/cm(2) at 500 °C. In the future, arrays of micro-SOFCs with high power density may enable a range of mobile and portable power applications.

  View details for DOI 10.1021/nn201354p

  View details for Web of Science ID 000293035200047

  View details for PubMedID 21657222

• Graphene-Wrapped Sulfur Particles as a Rechargeable Lithium-Sulfur Battery Cathode Material with High Capacity and Cycling Stability NANO LETTERS Wang, H., Yang, Y., Liang, Y., Robinson, J. T., Li, Y., Jackson, A., Cui, Y., Dai, H. 2011; 11 (7): 2644-2647

  Abstract

  We report the synthesis of a graphene-sulfur composite material by wrapping poly(ethylene glycol) (PEG) coated submicrometer sulfur particles with mildly oxidized graphene oxide sheets decorated by carbon black nanoparticles. The PEG and graphene coating layers are important to accommodating volume expansion of the coated sulfur particles during discharge, trapping soluble polysulfide intermediates, and rendering the sulfur particles electrically conducting. The resulting graphene-sulfur composite showed high and stable specific capacities up to ∼600 mAh/g over more than 100 cycles, representing a promising cathode material for rechargeable lithium batteries with high energy density.

  View details for DOI 10.1021/nl200658a

  View details for PubMedID 21699259

• Low-Temperature Self-Catalytic Growth of Tin Oxide Nanocones over Large Areas ACS NANO Jeong, S., McDowell, M. T., Cui, Y. 2011; 5 (7): 5800-5807

  Abstract

  Nanoscale texturing has been studied for various applications, but most of the methods used to make these nanostructures are expensive and not easily scalable. Some of these methods require etching steps or high-temperature processes, which limit the processes to certain materials, such as silicon. In this study, we report a non-etching nanoscale texturing technique that allows for controlled oxidation to create tin oxide nanocones over large areas. Similar results are obtained on different substrates, such as silicon, aluminum foil, quartz, and polyimide film, and this method can be employed at temperatures as low as 220 °C in ambient pressure. This simple and scalable nanotexturing process improves the anti-reflection effect in photovoltaic devices. The light absorption of a polycrystalline silicon substrate, a widely used photovoltaic material, is increased by 30% over the wavelength range of 400-850 nm after fabricating nanocones on the surface.

  View details for DOI 10.1021/nn2015216

  View details for Web of Science ID 000293035200058

  View details for PubMedID 21682321

• Interconnected Silicon Hollow Nanospheres for Lithium-Ion Battery Anodes with Long Cycle Life NANO LETTERS Yao, Y., McDowell, M. T., Ryu, I., Wu, H., Liu, N., Hu, L., Nix, W. D., Cui, Y. 2011; 11 (7): 2949-2954

  Abstract

  Silicon is a promising candidate for the anode material in lithium-ion batteries due to its high theoretical specific capacity. However, volume changes during cycling cause pulverization and capacity fade, and improving cycle life is a major research challenge. Here, we report a novel interconnected Si hollow nanosphere electrode that is capable of accommodating large volume changes without pulverization during cycling. We achieved the high initial discharge capacity of 2725 mAh g(-1) with less than 8% capacity degradation every hundred cycles for 700 total cycles. Si hollow sphere electrodes also show a Coulombic efficiency of 99.5% in later cycles. Superior rate capability is demonstrated and attributed to fast lithium diffusion in the interconnected Si hollow structure.

  View details for DOI 10.1021/nl201470j

  View details for Web of Science ID 000292849400066

  View details for PubMedID 21668030

• Solution-Processed Graphene/MnO2 Nanostructured Textiles for High-Performance Electrochemical Capacitors NANO LETTERS Yu, G., Hu, L., Vosgueritchian, M., Wang, H., Xie, X., McDonough, J. R., Cui, X., Cui, Y., Bao, Z. 2011; 11 (7): 2905-2911

  Abstract

  Large scale energy storage system with low cost, high power, and long cycle life is crucial for addressing the energy problem when connected with renewable energy production. To realize grid-scale applications of the energy storage devices, there remain several key issues including the development of low-cost, high-performance materials that are environmentally friendly and compatible with low-temperature and large-scale processing. In this report, we demonstrate that solution-exfoliated graphene nanosheets (∼5 nm thickness) can be conformably coated from solution on three-dimensional, porous textiles support structures for high loading of active electrode materials and to facilitate the access of electrolytes to those materials. With further controlled electrodeposition of pseudocapacitive MnO(2) nanomaterials, the hybrid graphene/MnO(2)-based textile yields high-capacitance performance with specific capacitance up to 315 F/g achieved. Moreover, we have successfully fabricated asymmetric electrochemical capacitors with graphene/MnO(2)-textile as the positive electrode and single-walled carbon nanotubes (SWNTs)-textile as the negative electrode in an aqueous Na(2)SO(4) electrolyte solution. These devices exhibit promising characteristics with a maximum power density of 110 kW/kg, an energy density of 12.5 Wh/kg, and excellent cycling performance of ∼95% capacitance retention over 5000 cycles. Such low-cost, high-performance energy textiles based on solution-processed graphene/MnO(2) hierarchical nanostructures offer great promise in large-scale energy storage device applications.

  View details for DOI 10.1021/nl2013828

  View details for PubMedID 21667923

• Anomalous Shape Changes of Silicon Nanopillars by Electrochemical Lithiation NANO LETTERS Lee, S. W., McDowell, M. T., Choi, J. W., Cui, Y. 2011; 11 (7): 3034-3039

  Abstract

  Silicon is one of the most attractive anode materials for use in Li-ion batteries due to its ∼10 times higher specific capacity than existing graphite anodes. However, up to 400% volume expansion during reaction with Li causes particle pulverization and fracture, which results in rapid capacity fading. Although Si nanomaterials have shown improvements in electrochemical performance, there is limited understanding of how volume expansion takes place. Here, we study the shape and volume changes of crystalline Si nanopillars with different orientations upon first lithiation and discover anomalous behavior. Upon lithiation, the initially circular cross sections of nanopillars with <100>, <110>, and <111> axial orientations expand into cross, ellipse, and hexagonal shapes, respectively. We explain this by identifying a high-speed lithium ion diffusion channel along the <110> direction, which causes preferential volume expansion along this direction. Surprisingly, the <111> and <100> nanopillars shrink in height after partial lithiation, while <110> nanopillars increase in height. The length contraction is suggested to be due to a collapse of the {111} planes early in the lithiation process. These results give new insight into the Si volume change process and could help in designing better battery anodes.

  View details for DOI 10.1021/nl201787r

  View details for Web of Science ID 000292849400080

  View details for PubMedID 21657250

• Silicon-Carbon Nanotube Coaxial Sponge as Li-Ion Anodes with High Areal Capacity ADVANCED ENERGY MATERIALS Hu, L., Wu, H., Gao, Y., Cao, A., Li, H., McDough, J., Xie, X., Zhou, M., Cui, Y. 2011; 1 (4): 523-527

  View details for DOI 10.1002/aenm.201100056

  View details for Web of Science ID 000293795800010

• Electrochemical characterization of LiCoO2 as rechargeable electrode in aqueous LiNO3 electrolyte 17th International Conference on Solid State Ionics Ruffo, R., La Mantia, F., Wessells, C., Huggins, R. A., Cui, Y. ELSEVIER SCIENCE BV. 2011: 289–92

  View details for DOI 10.1016/j.ssi.2010.05.043

  View details for Web of Science ID 000292848800062

• Rapid Surface Oxidation as a Source of Surface Degradation Factor for Bi2Se3 ACS NANO Kong, D., Cha, J. J., Lai, K., Peng, H., Analytis, J. G., Meister, S., Chen, Y., Zhang, H., Fisher, I. R., Shen, Z., Cui, Y. 2011; 5 (6): 4698-4703

  Abstract

  Bismuth selenide (Bi(2)Se(3)) is a topological insulator with metallic surface states (SS) residing in a large bulk bandgap. In experiments, synthesized Bi(2)Se(3) is often heavily n-type doped due to selenium vacancies. Furthermore, it is discovered from experiments on bulk single crystals that Bi(2)Se(3) gets additional n-type doping after exposure to the atmosphere, thereby reducing the relative contribution of SS in total conductivity. In this article, transport measurements on Bi(2)Se(3) nanoribbons provide additional evidence of such environmental doping process. Systematic surface composition analyses by X-ray photoelectron spectroscopy reveal fast formation and continuous growth of native oxide on Bi(2)Se(3) under ambient conditions. In addition to n-type doping at the surface, such surface oxidation is likely the material origin of the degradation of topological SS. Appropriate surface passivation or encapsulation may be required to probe topological SS of Bi(2)Se(3) by transport measurements.

  View details for DOI 10.1021/nn200556h

  View details for Web of Science ID 000292055200052

  View details for PubMedID 21568290

• Compressional Behavior of Bulk and Nanorod LiMn2O4 under Nonhydrostatic Stress JOURNAL OF PHYSICAL CHEMISTRY C Lin, Y., Yang, Y., Ma, H., Cui, Y., Mao, W. L. 2011; 115 (20): 9844-9849

  View details for DOI 10.1021/jp112289h

  View details for Web of Science ID 000290652200003

• Anisotropic Lithium Insertion Behavior in Silicon Nanowires: Binding Energy, Diffusion Barrier, and Strain Effect JOURNAL OF PHYSICAL CHEMISTRY C Zhang, Q., Cui, Y., Wang, E. 2011; 115 (19): 9376-9381

  View details for DOI 10.1021/jp11159777

  View details for Web of Science ID 000290427400009

• Batteries for Efficient Energy Extraction from a Water Salinity Difference NANO LETTERS La Mantia, F., Pasta, M., Deshazer, H. D., Logan, B. E., Cui, Y. 2011; 11 (4): 1810-1813

  Abstract

  The salinity difference between seawater and river water is a renewable source of enormous entropic energy, but extracting it efficiently as a form of useful energy remains a challenge. Here we demonstrate a device called "mixing entropy battery", which can extract and store it as useful electrochemical energy. The battery, containing a Na(2-x)Mn(5)O(10) nanorod electrode, was shown to extract energy from real seawater and river water and can be applied to a variety of salt waters. We demonstrated energy extraction efficiencies of up to 74%. Considering the flow rate of river water into oceans as the limiting factor, the renewable energy production could potentially reach 2 TW, or ∼13% of the current world energy consumption. The mixing entropy battery is simple to fabricate and could contribute significantly to renewable energy in the future.

  View details for DOI 10.1021/nl200500s

  View details for Web of Science ID 000289341500074

  View details for PubMedID 21413685

• Nano-structured textiles as high-performance aqueous cathodes for microbial fuel cells ENERGY & ENVIRONMENTAL SCIENCE Xie, X., Pasta, M., Hu, L., Yang, Y., McDonough, J., Cha, J., Criddle, C. S., Cui, Y. 2011; 4 (4): 1293-1297

  View details for DOI 10.1039/c0ee00793e

  View details for Web of Science ID 000289001400020

• In Situ Transmission Electron Microscopy Observation of Nanostructural Changes in Phase-Change Memory ACS NANO Meister, S., Kim, S., Cha, J. J., Wong, H. P., Cui, Y. 2011; 5 (4): 2742-2748

  Abstract

  Phase-change memory (PCM) has been researched extensively as a promising alternative to flash memory. Important studies have focused on its scalability, switching speed, endurance, and new materials. Still, reliability issues and inconsistent switching in PCM devices motivate the need to further study its fundamental properties. However, many investigations treat PCM cells as black boxes; nanostructural changes inside the devices remain hidden. Here, using in situ transmission electron microscopy, we observe real-time nanostructural changes in lateral Ge(2)Sb(2)Te(5) (GST) PCM bridges during switching. We find that PCM devices with similar resistances can exhibit distinct threshold switching behaviors due to the different initial distribution of nanocrystalline and amorphous domains, explaining variability of switching behaviors of PCM cells in the literature. Our findings show a direct correlation between nanostructure and switching behavior, providing important guidelines in the design and operation of future PCM devices with improved endurance and lower variability.

  View details for DOI 10.1021/nn1031356

  View details for Web of Science ID 000289742100038

  View details for PubMedID 21425849

• Vertical nanopillars for highly localized fluorescence imaging PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Xie, C., Hanson, L., Cui, Y., Cui, B. 2011; 108 (10): 3894-3899

  Abstract

  Observing individual molecules in a complex environment by fluorescence microscopy is becoming increasingly important in biological and medical research, for which critical reduction of observation volume is required. Here, we demonstrate the use of vertically aligned silicon dioxide nanopillars to achieve below-the-diffraction-limit observation volume in vitro and inside live cells. With a diameter much smaller than the wavelength of visible light, a transparent silicon dioxide nanopillar embedded in a nontransparent substrate restricts the propagation of light and affords evanescence wave excitation along its vertical surface. This effect creates highly confined illumination volume that selectively excites fluorescence molecules in the vicinity of the nanopillar. We show that this nanopillar illumination can be used for in vitro single-molecule detection at high fluorophore concentrations. In addition, we demonstrate that vertical nanopillars interface tightly with live cells and function as highly localized light sources inside the cell. Furthermore, specific chemical modification of the nanopillar surface makes it possible to locally recruit proteins of interest and simultaneously observe their behavior within the complex, crowded environment of the cell.

  View details for DOI 10.1073/pnas.1015589108

  View details for Web of Science ID 000288120400019

  View details for PubMedID 21368157

  View details for PubMedCentralID PMC3054026

• Recent results on aqueous electrolyte cells JOURNAL OF POWER SOURCES Wessells, C., Huggins, R. A., Cui, Y. 2011; 196 (5): 2884-2888

  View details for DOI 10.1016/j.jpowsour.2010.10.098

  View details for Web of Science ID 000286705100064

• Effects of Nanostructured Back Reflectors on the External Quantum Efficiency in Thin Film Solar Cells NANO RESEARCH Hsu, C., Burkhard, G. F., McGehee, M. D., Cui, Y. 2011; 4 (2): 153-158

  View details for DOI 10.1007/s12274-010-0064-y

  View details for Web of Science ID 000287974000001

• Low Reflectivity and High Flexibility of Tin-Doped Indium Oxide Nanofiber Transparent Electrodes JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Wu, H., Hu, L., Carney, T., Ruan, Z., Kong, D., Yu, Z., Yao, Y., Cha, J. J., Zhu, J., Fan, S., Cui, Y. 2011; 133 (1): 27-29

  Abstract

  Tin-doped indium oxide (ITO) has found widespread use in solar cells, displays, and touch screens as a transparent electrode; however, two major problems with ITO remain: high reflectivity (up to 10%) and insufficient flexibility. Together, these problems severely limit the applications of ITO films for future optoelectronic devices. In this communication, we report the fabrication of ITO nanofiber network transparent electrodes. The nanofiber networks show optical reflectivity as low as 5% and high flexibility; the nanofiber networks can be bent to a radius of 2 mm with negligible changes in the sheet resistance.

  View details for DOI 10.1021/ja109228e

  View details for Web of Science ID 000286351100009

  View details for PubMedID 21142042

• Si nanoparticle-decorated Si nanowire networks for Li-ion battery anodes CHEMICAL COMMUNICATIONS Hu, L., Wu, H., Hong, S. S., Cui, L., McDonough, J. R., Bohy, S., Cui, Y. 2011; 47 (1): 367-369

  Abstract

  We designed and fabricated binder-free, 3D porous silicon nanostructures for Li-ion battery anodes, where Si nanoparticles electrically contact current collectors via vertically grown silicon nanowires. When compared with a Si nanowire anode, the areal capacity was increased by a factor of 4 without having to use long, high temperature steps under vacuum that vapour-liquid-solid Si nanowire growth entails.

  View details for DOI 10.1039/c0cc02078h

  View details for Web of Science ID 000285068300076

  View details for PubMedID 20830432

• Carbon nanotube-coated macroporous sponge for microbial fuel cell electrodes Energy Environ. Sci. Xie, X., Ye, M., Hu, L., Liu, N., McDonough, J., R., Chen, W., Cui, Y. 2011

  View details for DOI 10.1039/C1EE02122B

• Symmetrical MnO2 Carbon Nanotube Textile Nanostructures for Wearable Pseudocapacitors with High Mass Loading ACS Nano Hu, L., Chen, W., Xie, X., Liu, N., Yang, Y., Wu, H., Cui, Y. 2011

  View details for DOI 10.1021/nn203085j

• Low-Temperature Self-CatalyticGrowth of Tin Oxide Nanocones overLarge Area ACS Nano Jeong, S., McDowell, M., T., Cui, Y. 2011; 5: 5800-5807
• Copper hexacyanoferrate battery electrodes with long cycle life and high power Nature Communications Wessells, C., D., Huggins, R., A., Cui, Y. 2011; 2:550

  View details for DOI 10.1038/ncomms1563

• Synthesis and Electrochemical Performance of a Lithium Titanium Phosphate Anode for Aqueous Lithium-Ion Batteries JOURNAL OF THE ELECTROCHEMICAL SOCIETY Wessells, C., La Mantia, F., Deshazer, H., Huggins, R. A., Cui, Y. 2011; 158 (3): A352-A355

  View details for DOI 10.1149/1.3536619

  View details for Web of Science ID 000286677900023

• Inorganic Glue Enabling High Performance of Silicon Particles as Lithium Ion Battery Anode JOURNAL OF THE ELECTROCHEMICAL SOCIETY Cui, L., Hu, L., Wu, H., Choi, J. W., Cui, Y. 2011; 158 (5): A592-A596

  View details for DOI 10.1149/1.3560030

  View details for Web of Science ID 000288867700023

• One dimensional Si/Sn - based nanowires and nanotubes for lithium-ion energy storage materials JOURNAL OF MATERIALS CHEMISTRY Choi, N., Yao, Y., Cui, Y., Cho, J. 2011; 21 (27): 9825-9840

  View details for DOI 10.1039/c0jm03842c

  View details for Web of Science ID 000292159700004

• One Nanometer Resolution Electrical Probe via Atomic Metal Filament Formation NANO LETTERS Hong, S. S., Cha, J. J., Cui, Y. 2011; 11 (1): 231-235

  Abstract

  Scanning probe microscopy has been widely used to investigate various interactions in microscopic nature. Particularly, conductive atomic force microscopy (C-AFM) can provide local electronic signals conveniently, but the probe resolution of C-AFM has been limited by the tip geometry. Here, we improve the probe resolution greatly by forming an atomic-size metallic filament on a commercial C-AFM tip. We demonstrate ∼1 nm lateral resolution in C-AFM using the metal filament tip. The filament tip is mechanically robust and electrically stable in repeated scans under ambient conditions since it is imbedded in a stable insulating matrix. The formation of the atomic filament is highly controllable and reproducible and can be easily integrated to existing AFM tip technologies to produce the next generation of high-resolution electrical and other scanning probes.

  View details for DOI 10.1021/nl103603v

  View details for Web of Science ID 000286029400039

  View details for PubMedID 21121667

• LiMn1-xFexPO4 Nanorods Grown on Graphene Sheets for Ultrahigh-Rate-Performance Lithium Ion Batteries ANGEWANDTE CHEMIE-INTERNATIONAL EDITION Wang, H., Yang, Y., Liang, Y., Cui, L., Casalongue, H. S., Li, Y., Hong, G., Cui, Y., Dai, H. 2011; 50 (32): 7364-7368

  View details for DOI 10.1002/anie.201103163

  View details for PubMedID 21710671

• Synthesis of Nanoscale Lithium-Ion Battery Cathode Materials Using a Porous Polymer Precursor Method JOURNAL OF THE ELECTROCHEMICAL SOCIETY Deshazer, H. D., La Mantia, F., Wessells, C., Huggins, R. A., Cui, Y. 2011; 158 (10): A1079-A1082

  View details for DOI 10.1149/1.3611428

  View details for Web of Science ID 000294063000003

• Nanowire Solar Cells ANNUAL REVIEW OF MATERIALS RESEARCH, VOL 41 Garnett, E. C., Brongersma, M. L., Cui, Y., McGehee, M. D. 2011; 41: 269-295

  View details for DOI 10.1146/annurev-matsci-062910-100434

  View details for Web of Science ID 000294028600011

• Three-Dimensional Carbon Nanotube-Textile Anode for High-Performance Microbial Fuel Cells NANO LETTERS Xie, X., Hu, L., Pasta, M., Wells, G. F., Kong, D., Criddle, C. S., Cui, Y. 2011; 11 (1): 291-296

  Abstract

  Microbial fuel cells (MFCs) harness the metabolism of microorganisms, converting chemical energy into electrical energy. Anode performance is an important factor limiting the power density of MFCs for practical application. Improving the anode design is thus important for enhancing the MFC performance, but only a little development has been reported. Here, we describe a biocompatible, highly conductive, two-scale porous anode fabricated from a carbon nanotube-textile (CNT-textile) composite for high-performance MFCs. The macroscale porous structure of the intertwined CNT-textile fibers creates an open 3D space for efficient substrate transport and internal colonization by a diverse microflora, resulting in a 10-fold-larger anolyte-biofilm-anode interfacial area than the projective surface area of the CNT-textile. The conformally coated microscale porous CNT layer displays strong interaction with the microbial biofilm, facilitating electron transfer from exoelectrogens to the CNT-textile anode. An MFC equipped with a CNT-textile anode has a 10-fold-lower charge-transfer resistance and achieves considerably better performance than one equipped with a traditional carbon cloth anode: the maximum current density is 157% higher, the maximum power density is 68% higher, and the energy recovery is 141% greater.

  View details for DOI 10.1021/nl103905t

  View details for Web of Science ID 000286029400050

  View details for PubMedID 21158405

• Plasmonic Dye-Sensitized Solar Cells ADVANCED ENERGY MATERIALS Ding, I., Zhu, J., Cai, W., Moon, S., Cai, N., Wang, P., Zakeeruddin, S. M., Graetzel, M., Brongersma, M. L., Cui, Y., McGehee, M. D. 2011; 1 (1): 52-57

  View details for DOI 10.1002/aenm.201000041

  View details for Web of Science ID 000291725000004

• Metal current collector-free freestanding silicon-carbon 1D nanocomposites for ultralight anodes in lithium ion batteries JOURNAL OF POWER SOURCES Choi, J. W., Hu, L., Cui, L., McDonough, J. R., Cui, Y. 2010; 195 (24): 8311-8316

  View details for DOI 10.1016/j.jpowsour.2010.06.108

  View details for Web of Science ID 000282251900058

• Microcompression of Fused Silica Nanopillars Synthesized Using Reactive Ion Etching NANOSCIENCE AND NANOTECHNOLOGY LETTERS Han, S. M., Xie, C., Cui, Y. 2010; 2 (4): 344-347

  View details for DOI 10.1166/nnl.2010.1105

  View details for Web of Science ID 000293211100014

• Nanostructured photon management for high performance solar cells MATERIALS SCIENCE & ENGINEERING R-REPORTS Zhu, J., Yu, Z., Fan, S., Cui, Y. 2010; 70 (3-6): 330-340

  View details for DOI 10.1016/j.mser.2010.06.018

  View details for Web of Science ID 000285706100017

• First principles study of lithium insertion in bulk silicon JOURNAL OF PHYSICS-CONDENSED MATTER Wan, W., Zhang, Q., Cui, Y., Wang, E. 2010; 22 (41)

  Abstract

  Si is an important anode material for the next generation of Li ion batteries. Here the energetics and dynamics of Li atoms in bulk Si have been studied at different Li concentrations on the basis of first principles calculations. It is found that Li prefers to occupy an interstitial site as a shallow donor rather than a substitutional site. The most stable position is the tetrahedral (T(d)) site. The diffusion of a Li atom in the Si lattice is through a T(d)-Hex-T(d) trajectory, where the Hex site is the hexagonal transition site with an energy barrier of 0.58 eV. We have also systematically studied the local structural transition of a Li(x)Si alloy with x varying from 0 to 0.25. At low doping concentration (x = 0-0.125), Li atoms prefer to be separated from each other, resulting in a homogeneous doping distribution. Starting from x = 0.125, Li atoms tend to form clusters induced by a lattice distortion with frequent breaking and reforming of Si-Si bonds. When x ≥ 0.1875, Li atoms will break some Si-Si bonds permanently, which results in dangling bonds. These dangling bonds create negatively charged zones, which is the main driving force for Li atom clustering at high doping concentration.

  View details for DOI 10.1088/0953-8984/22/41/415501

  View details for Web of Science ID 000282227500006

  View details for PubMedID 21386598

• Mn3O4-Graphene Hybrid as a High-Capacity Anode Material for Lithium Ion Batteries JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Wang, H., Cui, L., Yang, Y., Casalongue, H. S., Robinson, J. T., Liang, Y., Cui, Y., Dai, H. 2010; 132 (40): 13978-13980

  Abstract

  We developed two-step solution-phase reactions to form hybrid materials of Mn(3)O(4) nanoparticles on reduced graphene oxide (RGO) sheets for lithium ion battery applications. Selective growth of Mn(3)O(4) nanoparticles on RGO sheets, in contrast to free particle growth in solution, allowed for the electrically insulating Mn(3)O(4) nanoparticles to be wired up to a current collector through the underlying conducting graphene network. The Mn(3)O(4) nanoparticles formed on RGO show a high specific capacity up to ∼900 mAh/g, near their theoretical capacity, with good rate capability and cycling stability, owing to the intimate interactions between the graphene substrates and the Mn(3)O(4) nanoparticles grown atop. The Mn(3)O(4)/RGO hybrid could be a promising candidate material for a high-capacity, low-cost, and environmentally friendly anode for lithium ion batteries. Our growth-on-graphene approach should offer a new technique for the design and synthesis of battery electrodes based on highly insulating materials.

  View details for DOI 10.1021/ja105296a

  View details for PubMedID 20853844

• A new approach to glucose sensing at gold electrodes ELECTROCHEMISTRY COMMUNICATIONS Pasta, M., La Mantia, F., Cui, Y. 2010; 12 (10): 1407-1410

  View details for DOI 10.1016/j.elecom.2010.07.033

  View details for Web of Science ID 000284444500038

• Electrospun Metal Nanofiber Webs as High-Performance Transparent Electrode NANO LETTERS Wu, H., Hu, L., Rowell, M. W., Kong, D., Cha, J. J., McDonough, J. R., Zhu, J., Yang, Y., McGehee, M. D., Cui, Y. 2010; 10 (10): 4242-4248

  Abstract

  Transparent electrodes, indespensible in displays and solar cells, are currently dominated by indium tin oxide (ITO) films although the high price of indium, brittleness of films, and high vacuum deposition are limiting their applications. Recently, solution-processed networks of nanostructures such as carbon nanotubes (CNTs), graphene, and silver nanowires have attracted great attention as replacements. A low junction resistance between nanostructures is important for decreasing the sheet resistance. However, the junction resistances between CNTs and boundry resistances between graphene nanostructures are too high. The aspect ratios of silver nanowires are limited to ∼100, and silver is relatively expensive. Here, we show high-performance transparent electrodes with copper nanofiber networks by a low-cost and scalable electrospinning process. Copper nanofibers have ultrahigh aspect ratios of up to 100000 and fused crossing points with ultralow junction resistances, which result in high transmitance at low sheet resistance, e.g., 90% at 50 Ω/sq. The copper nanofiber networks also show great flexibility and stretchabilty. Organic solar cells using copper nanowire networks as transparent electrodes have a power efficiency of 3.0%, comparable to devices made with ITO electrodes.

  View details for DOI 10.1021/nl102725k

  View details for PubMedID 20738115

• Noninvasive Neuron Pinning with Nanopillar Arrays NANO LETTERS Xie, C., Hanson, L., Xie, W., Lin, Z., Cui, B., Cui, Y. 2010; 10 (10): 4020-4024

  Abstract

  Cell migration in a cultured neuronal network presents an obstacle to selectively measuring the activity of the same neuron over a long period of time. Here we report the use of nanopillar arrays to pin the position of neurons in a noninvasive manner. Vertical nanopillars protruding from the surface serve as geometrically better focal adhesion points for cell attachment than a flat surface. The cell body mobility is significantly reduced from 57.8 μm on a flat surface to 3.9 μm on nanopillars over a 5 day period. Yet, neurons growing on nanopillar arrays show a growth pattern that does not differ in any significant way from that seen on a flat substrate. Notably, while the cell bodies of neurons are efficiently anchored by the nanopillars, the axons and dendrites are free to grow and elongate into the surrounding area to develop a neuronal network, which opens up opportunities for long-term study of the same neurons in connected networks.

  View details for DOI 10.1021/nl101950x

  View details for Web of Science ID 000282727600038

  View details for PubMedID 20815404

  View details for PubMedCentralID PMC2955158

• Ultrathin Spinel LiMn2O4 Nanowires as High Power Cathode Materials for Li-Ion Batteries NANO LETTERS Lee, H., Muralidharan, P., Ruffo, R., Mari, C. M., Cui, Y., Kim, D. K. 2010; 10 (10): 3852-3856

  Abstract

  Ultrathin LiMn(2)O(4) nanowires with cubic spinel structure were synthesized by using a solvothermal reaction to produce α-MnO(2) nanowire followed by solid-state lithiation. LiMn(2)O(4) nanowires have diameters less than 10 nm and lengths of several micrometers. Galvanostatic battery testing showed that LiMn(2)O(4) nanowires deliver 100 and 78 mAh/g at very high rate (60C and 150C, respectively) in a larger potential window with very good capacity retention and outstanding structural stability. Such performances are due to both the favorable morphology and the high crystallinity of nanowires.

  View details for DOI 10.1021/nl101047f

  View details for Web of Science ID 000282727600008

  View details for PubMedID 20795626

• Thin, Flexible Secondary Li-Ion Paper Batteries ACS NANO Hu, L., Wu, H., La Mantia, F., Yang, Y., Cui, Y. 2010; 4 (10): 5843-5848

  Abstract

  There is a strong interest in thin, flexible energy storage devices to meet modern society needs for applications such as interactive packaging, radio frequency sensing, and consumer products. In this article, we report a new structure of thin, flexible Li-ion batteries using paper as separators and free-standing carbon nanotube thin films as both current collectors. The current collectors and Li-ion battery materials are integrated onto a single sheet of paper through a lamination process. The paper functions as both a mechanical substrate and separator membrane with lower impedance than commercial separators. The CNT film functions as a current collector for both the anode and the cathode with a low sheet resistance (∼5 Ohm/sq), lightweight (∼0.2 mg/cm(2)), and excellent flexibility. After packaging, the rechargeable Li-ion paper battery, despite being thin (∼300 μm), exhibits robust mechanical flexibility (capable of bending down to <6 mm) and a high energy density (108 mWh/g).

  View details for DOI 10.1021/nn1018158

  View details for PubMedID 20836501

• High Speed Water Sterilization Using One-Dimensional Nanostructures NANO LETTERS Schoen, D. T., Schoen, A. P., Hu, L., Kim, H. S., Heilshorn, S. C., Cui, Y. 2010; 10 (9): 3628-3632

  Abstract

  The removal of bacteria and other organisms from water is an extremely important process, not only for drinking and sanitation but also industrially as biofouling is a commonplace and serious problem. We here present a textile based multiscale device for the high speed electrical sterilization of water using silver nanowires, carbon nanotubes, and cotton. This approach, which combines several materials spanning three very different length scales with simple dying based fabrication, makes a gravity fed device operating at 100000 L/(h m(2)) which can inactivate >98% of bacteria with only several seconds of total incubation time. This excellent performance is enabled by the use of an electrical mechanism rather than size exclusion, while the very high surface area of the device coupled with large electric field concentrations near the silver nanowire tips allows for effective bacterial inactivation.

  View details for DOI 10.1021/nl101944e

  View details for Web of Science ID 000281498200068

  View details for PubMedID 20726518

• Lithium Insertion In Silicon Nanowires: An ab Initio Study NANO LETTERS Zhang, Q., Zhang, W., Wan, W., Cui, Y., Wang, E. 2010; 10 (9): 3243-3249

  Abstract

  The ultrahigh specific lithium ion storage capacity of Si nanowires (SiNWs) has been demonstrated recently and has opened up exciting opportunities for energy storage. However, a systematic theoretical study on lithium insertion in SiNWs remains a challenge, and as a result, understanding of the fundamental interaction and microscopic dynamics during lithium insertion is still lacking. This paper focuses on the study of single Li atom insertion into SiNWs with different sizes and axis orientations by using full ab initio calculations. We show that the binding energy of interstitial Li increases as the SiNW diameter grows. The binding energies at different insertion sites, which can be classified as surface, intermediate, and core sites, are quite different. We find that surface sites are energetically the most favorable insertion positions and that intermediate sites are the most unfavorable insertion positions. Compared with the other growth directions, the [110] SiNWs with different diameters always present the highest binding energies on various insertion locations, which indicates that [110] SiNWs are more favorable by Li doping. Furthermore, we study Li diffusion inside SiNWs. The results show that the Li surface diffusion has a much higher chance to occur than the surface to core diffusion, which is consistent with the experimental observation that the Li insertion in SiNWs is layer by layer from surface to inner region. After overcoming a large barrier crossing surface-to-intermediate region, the diffusion toward center has a higher possibility to occur than the inverse process.

  View details for DOI 10.1021/nl904132v

  View details for Web of Science ID 000281498200004

  View details for PubMedID 20681548

• Fast and Scalable Printing of Large Area Monolayer Nanoparticles for Nanotexturing Applications NANO LETTERS Jeong, S., Hu, L., Lee, H. R., Garnett, E., Choi, J. W., Cui, Y. 2010; 10 (8): 2989-2994

  Abstract

  Recently, there have been several studies demonstrating that highly ordered nanoscale texturing can dramatically increase performance of applications such as light absorption in thin-film solar cells. However, those methods used to make the nanostructures are not compatible with large-scale fabrication. Here we demonstrate that a technique currently used in roll-to-roll processing to deposit uniform thin films from solution, a wire-wound rod coating method, can be adapted to deposit close-packed monolayers or multilayers of silica nanoparticles on a variety of rigid and flexible substrates. Amorphous silicon thin films deposited on these nanoparticle monolayers exhibit 42% higher absorption over the integrated AM 1.5 spectrum than the planar controls. This simple assembly technique can be used to improve solar cells, fuel cells, light emitting diodes and other devices where ordered nanoscale texturing is critical for optimal performance.

  View details for DOI 10.1021/nl101432r

  View details for Web of Science ID 000280728900043

  View details for PubMedID 20698612

• Ultrathin Topological Insulator Bi2Se3 Nanoribbons Exfoliated by Atomic Force Microscopy NANO LETTERS Hong, S. S., Kundhikanjana, W., Cha, J. J., Lai, K., Kong, D., Meister, S., Kelly, M. A., Shen, Z., Cui, Y. 2010; 10 (8): 3118-3122

  Abstract

  Ultrathin topological insulator nanostructures, in which coupling between top and bottom surface states takes place, are of great intellectual and practical importance. Due to the weak van der Waals interaction between adjacent quintuple layers (QLs), the layered bismuth selenide (Bi(2)Se(3)), a single Dirac-cone topological insulator with a large bulk gap, can be exfoliated down to a few QLs. In this paper, we report the first controlled mechanical exfoliation of Bi(2)Se(3) nanoribbons (>50 QLs) by an atomic force microscope (AFM) tip down to a single QL. Microwave impedance microscopy is employed to map out the local conductivity of such ultrathin nanoribbons, showing drastic difference in sheet resistance between 1-2 QLs and 4-5 QLs. Transport measurement carried out on an exfoliated (50 QLs) ribbons. These AFM-exfoliated thin nanoribbons afford interesting candidates for studying the transition from quantum spin Hall surface to edge states.

  View details for DOI 10.1021/nl1018E4h

  View details for PubMedID 20698625

• Mechanism of glucose electrochemical oxidation on gold surface ELECTROCHIMICA ACTA Pasta, M., La Mantia, F., Cui, Y. 2010; 55 (20): 5561-5568

  View details for DOI 10.1016/j.electacta.2010.04.069

  View details for Web of Science ID 000280422800006

• Light-Weight Free-Standing Carbon Nanotube-Silicon Films for Anodes of Lithium Ion Batteries ACS NANO Cui, L., Hu, L., Choi, J. W., Cui, Y. 2010; 4 (7): 3671-3678

  Abstract

  Silicon is an attractive alloy-type anode material because of its highest known capacity (4200 mAh/g). However, lithium insertion into and extraction from silicon are accompanied by a huge volume change, up to 300%, which induces a strong strain on silicon and causes pulverization and rapid capacity fading due to the loss of the electrical contact between part of silicon and current collector. Si nanostructures such as nanowires, which are chemically and electrically bonded to the current collector, can overcome the pulverization problem, however, the heavy metal current collectors in these systems are larger in weight than Si active material. Herein we report a novel anode structure free of heavy metal current collectors by integrating a flexible, conductive carbon nanotube (CNT) network into a Si anode. The composite film is free-standing and has a structure similar to the steel bar reinforced concrete, where the infiltrated CNT network functions as both mechanical support and electrical conductor and Si as a high capacity anode material for Li-ion battery. Such free-standing film has a low sheet resistance of approximately 30 Ohm/sq. It shows a high specific charge storage capacity (approximately 2000 mAh/g) and a good cycling life, superior to pure sputtered-on silicon films with similar thicknesses. Scanning electron micrographs show that Si is still connected by the CNT network even when small breaking or cracks appear in the film after cycling. The film can also "ripple up" to release the strain of a large volume change during lithium intercalation. The conductive composite film can function as both anode active material and current collector. It offers approximately 10 times improvement in specific capacity compared with widely used graphite/copper anode sheets.

  View details for DOI 10.1021/nn100619m

  View details for Web of Science ID 000280364800016

  View details for PubMedID 20518567

• Nanodome Solar Cells with Efficient Light Management and Self-Cleaning NANO LETTERS Zhu, J., Hsu, C., Yu, Z., Fan, S., Cui, Y. 2010; 10 (6): 1979-1984

  Abstract

  Here for the first time, we demonstrate novel nanodome solar cells, which have periodic nanoscale modulation for all layers from the bottom substrate, through the active absorber to the top transparent contact. These devices combine many nanophotonic effects to both efficiently reduce reflection and enhance absorption over a broad spectral range. Nanodome solar cells with only a 280 nm thick hydrogenated amorphous silicon (a-Si:H) layer can absorb 94% of the light with wavelengths of 400-800 nm, significantly higher than the 65% absorption of flat film devices. Because of the nearly complete absorption, a very large short-circuit current of 17.5 mA/cm(2) is achieved in our nanodome devices. Excitingly, the light management effects remain efficient over a wide range of incident angles, favorable for real environments with significant diffuse sunlight. We demonstrate nanodome devices with a power efficiency of 5.9%, which is 25% higher than the flat film control. The nanodome structure is not in principle limited to any specific material system and its fabrication is compatible with most solar manufacturing; hence it opens up exciting opportunities for a variety of photovoltaic devices to further improve performance, reduce materials usage, and relieve elemental abundance limitations. Lastly, our nanodome devices when modified with hydrophobic molecules present a nearly superhydrophobic surface and thus enable self-cleaning solar cells.

  View details for DOI 10.1021/nl9034237

  View details for Web of Science ID 000278449200002

  View details for PubMedID 19891462

• Aqueous supercapacitors on conductive cotton NANO RESEARCH Pasta, M., La Mantia, F., Hu, L., Deshazer, H. D., Cui, Y. 2010; 3 (6): 452-458

  View details for DOI 10.1007/s12274-010-0006-8

  View details for Web of Science ID 000278624100009

• Few-Layer Nanoplates of Bi2Se3 and Bi2Te3 with Highly Tunable Chemical Potential NANO LETTERS Kong, D., Dang, W., Cha, J. J., Li, H., Meister, S., Peng, H., Liu, Z., Cui, Y. 2010; 10 (6): 2245-2250

  Abstract

  A topological insulator (TI) represents an unconventional quantum phase of matter with insulating bulk band gap and metallic surface states. Recent theoretical calculations and photoemission spectroscopy measurements show that group V-VI materials Bi(2)Se(3), Bi(2)Te(3), and Sb(2)Te(3) are TIs with a single Dirac cone on the surface. These materials have anisotropic, layered structures, in which five atomic layers are covalently bonded to form a quintuple layer, and quintuple layers interact weakly through van der Waals interaction to form the crystal. A few quintuple layers of these materials are predicted to exhibit interesting surface properties. Different from our previous nanoribbon study, here we report the synthesis and characterizations of ultrathin Bi(2)Te(3) and Bi(2)Se(3) nanoplates with thickness down to 3 nm (3 quintuple layers), via catalyst-free vapor-solid (VS) growth mechanism. Optical images reveal thickness-dependent color and contrast for nanoplates grown on oxidized silicon (300 nm SiO(2)/Si). As a new member of TI nanomaterials, ultrathin TI nanoplates have an extremely large surface-to-volume ratio and can be electrically gated more effectively than the bulk form, potentially enhancing surface state effects in transport measurements. Low-temperature transport measurements of a single nanoplate device, with a high-k dielectric top gate, show decrease in carrier concentration by several times and large tuning of chemical potential.

  View details for DOI 10.1021/nl101260j

  View details for Web of Science ID 000278449200046

  View details for PubMedID 20486680

• CuInS2 Solar Cells by Air-Stable Ink Rolling JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Weil, B. D., Connor, S. T., Cui, Y. 2010; 132 (19): 6642-?

  Abstract

  Solution-based deposition techniques are widely considered to be a route to low-cost, high-throughput photovoltaic device fabrication. In this report, we establish a methodology for a highly scalable deposition process and report the synthesis of an air-stable, vulcanized ink from commercially available precursors. Using our air-stable ink rolling (AIR) process, we can make solar cells with an absorber layer that is flat, contaminant-free, and composed of large-grained CuInS(2). The current-voltage characteristics of the devices were measured in the dark and under 100 mW/cm(2) illumination intensity, and the devices were found to have J(sc) = 18.49 mA/cm(2), V(oc) = 320 mV, FF = 0.37, and eta = 2.15%. This process has the ability to produce flat, contaminant-free, large-grained films similar to those produced by vacuum deposition, and its versatility should make it capable of producing a variety of materials for electronic, optoelectronic, and memory devices.

  View details for DOI 10.1021/ja1020475

  View details for Web of Science ID 000277721500015

  View details for PubMedID 20423082

• Printed energy storage devices by integration of electrodes and separators into single sheets of paper APPLIED PHYSICS LETTERS Hu, L., Wu, H., Cui, Y. 2010; 96 (18)

  View details for DOI 10.1063/1.3425767

  View details for Web of Science ID 000277422000055

• Scalable Coating and Properties of Transparent, Flexible, Silver Nanowire Electrodes ACS NANO Hu, L., Kim, H. S., Lee, J., Peumans, P., Cui, Y. 2010; 4 (5): 2955-2963

  Abstract

  We report a comprehensive study of transparent and conductive silver nanowire (Ag NW) electrodes, including a scalable fabrication process, morphologies, and optical, mechanical adhesion, and flexibility properties, and various routes to improve the performance. We utilized a synthesis specifically designed for long and thin wires for improved performance in terms of sheet resistance and optical transmittance. Twenty Omega/sq and approximately 80% specular transmittance, and 8 ohms/sq and 80% diffusive transmittance in the visible range are achieved, which fall in the same range as the best indium tin oxide (ITO) samples on plastic substrates for flexible electronics and solar cells. The Ag NW electrodes show optical transparencies superior to ITO for near-infrared wavelengths (2-fold higher transmission). Owing to light scattering effects, the Ag NW network has the largest difference between diffusive transmittance and specular transmittance when compared with ITO and carbon nanotube electrodes, a property which could greatly enhance solar cell performance. A mechanical study shows that Ag NW electrodes on flexible substrates show excellent robustness when subjected to bending. We also study the electrical conductance of Ag nanowires and their junctions and report a facile electrochemical method for a Au coating to reduce the wire-to-wire junction resistance for better overall film conductance. Simple mechanical pressing was also found to increase the NW film conductance due to the reduction of junction resistance. The overall properties of transparent Ag NW electrodes meet the requirements of transparent electrodes for many applications and could be an immediate ITO replacement for flexible electronics and solar cells.

  View details for DOI 10.1021/nn1005232

  View details for Web of Science ID 000277976900057

  View details for PubMedID 20426409

• Stepwise Nanopore Evolution in One-Dimensional Nanostructures NANO LETTERS Choi, J. W., McDonough, J., Jeong, S., Yoo, J. S., Chan, C. K., Cui, Y. 2010; 10 (4): 1409-1413

  Abstract

  We report that established simple lithium (Li) ion battery cycles can be used to produce nanopores inside various useful one-dimensional (1D) nanostructures such as zinc oxide, silicon, and silver nanowires. Moreover, porosities of these 1D nanomaterials can be controlled in a stepwise manner by the number of Li-battery cycles. Subsequent pore characterization at the end of each cycle allows us to obtain detailed snapshots of the distinct pore evolution properties in each material due to their different atomic diffusion rates and types of chemical bonds. Also, this stepwise characterization led us to the first observation of pore size increases during cycling, which can be interpreted as a similar phenomenon to Ostwald ripening in analogous nanoparticle cases. Finally, we take advantage of the unique combination of nanoporosity and 1D materials and demonstrate nanoporous silicon nanowires (poSiNWs) as excellent supercapacitor (SC) electrodes in high power operations compared to existing devices with activated carbon.

  View details for DOI 10.1021/nl100258p

  View details for Web of Science ID 000276557100056

  View details for PubMedID 20334444

• New Nanostructured Li2S/Silicon Rechargeable Battery with High Specific Energy NANO LETTERS Yang, Y., McDowell, M. T., Jackson, A., Cha, J. J., Hong, S. S., Cui, Y. 2010; 10 (4): 1486-1491

  Abstract

  Rechargeable lithium ion batteries are important energy storage devices; however, the specific energy of existing lithium ion batteries is still insufficient for many applications due to the limited specific charge capacity of the electrode materials. The recent development of sulfur/mesoporous carbon nanocomposite cathodes represents a particularly exciting advance, but in full battery cells, sulfur-based cathodes have to be paired with metallic lithium anodes as the lithium source, which can result in serious safety issues. Here we report a novel lithium metal-free battery consisting of a Li(2)S/mesoporous carbon composite cathode and a silicon nanowire anode. This new battery yields a theoretical specific energy of 1550 Wh kg(-1), which is four times that of the theoretical specific energy of existing lithium-ion batteries based on LiCoO(2) cathodes and graphite anodes (approximately 410 Wh kg(-1)). The nanostructured design of both electrodes assists in overcoming the issues associated with using sulfur compounds and silicon in lithium-ion batteries, including poor electrical conductivity, significant structural changes, and volume expansion. We have experimentally realized an initial discharge specific energy of 630 Wh kg(-1) based on the mass of the active electrode materials.

  View details for DOI 10.1021/nl100504q

  View details for PubMedID 20184382

• Semitransparent Organic Photovoltaic Cells with Laminated Top Electrode NANO LETTERS Lee, J., Connor, S. T., Cui, Y., Peumans, P. 2010; 10 (4): 1276-1279

  Abstract

  We demonstrate semitransparent small molecular weight organic photovoltaic cells using a laminated silver nanowire mesh as a transparent, conductive cathode layer. The lamination process does not damage the underlying solar cell and results in a transparent electrode with low sheet resistance and high optical transmittance without impacting photocurrent collection. The resulting semitransparent phthalocyanine/fullerene organic solar cell has a power conversion efficiency that is 57% of that of a device with a conventional metal cathode due to differences in optical absorption.

  View details for DOI 10.1021/nl903892x

  View details for Web of Science ID 000276557100032

  View details for PubMedID 20350007

• Nanowire platform for mapping neural circuits PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Xie, C., Cui, Y. 2010; 107 (10): 4489-4490

  View details for DOI 10.1073/pnas.1000450107

  View details for Web of Science ID 000275368400001

  View details for PubMedID 20194753

  View details for PubMedCentralID PMC2842070

• Aharonov-Bohm interference in topological insulator nanoribbons NATURE MATERIALS Peng, H., Lai, K., Kong, D., Meister, S., Chen, Y., Qi, X., Zhang, S., Shen, Z., Cui, Y. 2010; 9 (3): 225-229

  Abstract

  Topological insulators represent unusual phases of quantum matter with an insulating bulk gap and gapless edges or surface states. The two-dimensional topological insulator phase was predicted in HgTe quantum wells and confirmed by transport measurements. Recently, Bi(2)Se(3) and related materials have been proposed as three-dimensional topological insulators with a single Dirac cone on the surface, protected by time-reversal symmetry. The topological surface states have been observed by angle-resolved photoemission spectroscopy experiments. However, few transport measurements in this context have been reported, presumably owing to the predominance of bulk carriers from crystal defects or thermal excitations. Here we show unambiguous transport evidence of topological surface states through periodic quantum interference effects in layered single-crystalline Bi(2)Se(3) nanoribbons, which have larger surface-to-volume ratios than bulk materials and can therefore manifest surface effects. Pronounced Aharonov-Bohm oscillations in the magnetoresistance clearly demonstrate the coherent propagation of two-dimensional electrons around the perimeter of the nanoribbon surface, as expected from the topological nature of the surface states. The dominance of the primary h/e oscillation, where h is Planck's constant and e is the electron charge, and its temperature dependence demonstrate the robustness of these states. Our results suggest that topological insulator nanoribbons afford promising materials for future spintronic devices at room temperature.

  View details for DOI 10.1038/NMAT2609

  View details for Web of Science ID 000274700900017

  View details for PubMedID 20010826

• PHOTOVOLTAICS More solar cells for less NATURE MATERIALS Zhu, J., Cui, Y. 2010; 9 (3): 183-184

  View details for DOI 10.1038/nmat2701

  View details for Web of Science ID 000274700900007

  View details for PubMedID 20168338

• Magnetic Doping and Kondo Effect in Bi2Se3 Nanoribbons NANO LETTERS Cha, J. J., Williams, J. R., Kong, D., Meister, S., Peng, H., Bestwick, A. J., Gallagher, P., Goldhaber-Gordon, D., Cui, Y. 2010; 10 (3): 1076-1081

  Abstract

  A simple surface band structure and a large bulk band gap have allowed Bi2Se3 to become a reference material for the newly discovered three-dimensional topological insulators, which exhibit topologically protected conducting surface states that reside inside the bulk band gap. Studying topological insulators such as Bi2Se3 in nanostructures is advantageous because of the high surface-to-volume ratio, which enhances effects from the surface states; recently reported Aharonov-Bohm oscillation in topological insulator nanoribbons by some of us is a good example. Theoretically, introducing magnetic impurities in topological insulators is predicted to open a small gap in the surface states by breaking time-reversal symmetry. Here, we present synthesis of magnetically doped Bi2Se3 nanoribbons by vapor-liquid-solid growth using magnetic metal thin films as catalysts. Although the doping concentration is less than approximately 2%, low-temperature transport measurements of the Fe-doped Bi2Se3 nanoribbon devices show a clear Kondo effect at temperatures below 30 K, confirming the presence of magnetic impurities in the Bi2Se3 nanoribbons. The capability to dope topological insulator nanostructures magnetically opens up exciting opportunities for spintronics.

  View details for DOI 10.1021/nl100146n

  View details for Web of Science ID 000275278200057

  View details for PubMedID 20131918

• Solution-Grown Silicon Nanowires for Lithium-Ion Battery Anodes ACS NANO Chan, C. K., Patel, R. N., O'Connell, M. J., Korgel, B. A., Cui, Y. 2010; 4 (3): 1443-1450

  Abstract

  Composite electrodes composed of silicon nanowires synthesized using the supercritical fluid-liquid-solid (SFLS) method mixed with amorphous carbon or carbon nanotubes were evaluated as Li-ion battery anodes. Carbon coating of the silicon nanowires using the pyrolysis of sugar was found to be crucial for making good electronic contact to the material. Using multiwalled carbon nanotubes as the conducting additive was found to be more effective for obtaining good cycling behavior than using amorphous carbon. Reversible capacities of 1500 mAh/g were observed for 30 cycles.

  View details for DOI 10.1021/nn901409q

  View details for Web of Science ID 000275858200025

  View details for PubMedID 20201547

• Stretchable, Porous, and Conductive Energy Textiles NANO LETTERS Hu, L., Pasta, M., La Mantia, F., Cui, L., Jeong, S., Deshazer, H. D., Choi, J. W., Han, S. M., Cui, Y. 2010; 10 (2): 708-714

  Abstract

  Recently there is strong interest in lightweight, flexible, and wearable electronics to meet the technological demands of modern society. Integrated energy storage devices of this type are a key area that is still significantly underdeveloped. Here, we describe wearable power devices using everyday textiles as the platform. With an extremely simple "dipping and drying" process using single-walled carbon nanotube (SWNT) ink, we produced highly conductive textiles with conductivity of 125 S cm(-1) and sheet resistance less than 1 Omega/sq. Such conductive textiles show outstanding flexibility and stretchability and demonstrate strong adhesion between the SWNTs and the textiles of interest. Supercapacitors made from these conductive textiles show high areal capacitance, up to 0.48F/cm(2), and high specific energy. We demonstrate the loading of pseudocapacitor materials into these conductive textiles that leads to a 24-fold increase of the areal capacitance of the device. These highly conductive textiles can provide new design opportunities for wearable electronics and energy storage applications.

  View details for DOI 10.1021/nl903949m

  View details for Web of Science ID 000274338800059

  View details for PubMedID 20050691

• FACETING AND DISORDER IN NANOWIRE SOLAR CELL ARRAYS 35th IEEE Photovoltaic Specialists Conference Pickett, E., Gu, A., Huo, Y., Garnett, E., Hu, S., Sarmiento, T., Thombare, S., Liang, D., Li, S., Cui, Y., McGehee, M., McIntyre, P., Harris, J. IEEE. 2010: 1848–1853

  View details for Web of Science ID 000287579502020

• High Speed Water Sterilization Using One-Dimentional Nanostructures Nano Letters Schoen, D., T., Schoen, A., P., Hu, L., Kim, H., S., Heilshorn, S., C., Cui, Y. 2010; 10: 3628-3632
• Silicon nanowire hybrid photovoltaics Garnett, E., C., Peters, C., Brongersma, M., Cui, Y., McGehee, M., D. 2010

  View details for DOI 10.1109/PVSC.2010.5614661,000934 - 000938

• Low Reflectivity and High Flexibility of Tin-Doped Indium Oxide Nanofiber Transparent Electrodes Journal of the American Chemical Society Wu, H., Hu, L., Carney, T., Ruan, Z., Kong, D., Yu, Z., Cui, Y. 2010
• More solar cells for less Nature Materials Zhu, J., Cui, Y. 2010; 9: 183-184
• DESIGN AND GROWTH OF III-V NANOWIRE SOLAR CELL ARRAYS ON LOW COST SUBSTRATES 35th IEEE Photovoltaic Specialists Conference Gu, A., Huo, Y., Hu, S., Sarmiento, T., Pickett, E., Liang, D., Li, S., Lin, A., Thombare, S., Yu, Z., Fan, S., McIntyre, P., Cui, Y., Harris, J. IEEE. 2010: 2034–2037

  View details for Web of Science ID 000287579502062

• Nanopore Patterned Pt Array Electrodes for Triple Phase Boundary Study in Low Temperature SOFC JOURNAL OF THE ELECTROCHEMICAL SOCIETY Kim, Y. B., Hsu, C., Connor, S. T., Guer, T. M., Cui, Y., Prinz, F. B. 2010; 157 (9): B1269-B1274

  View details for DOI 10.1149/1.3455046

  View details for Web of Science ID 000280348300008

• Topological Insulator Nanowires and Nanoribbons NANO LETTERS Kong, D., Randel, J. C., Peng, H., Cha, J. J., Meister, S., Lai, K., Chen, Y., Shen, Z., Manoharan, H. C., Cui, Y. 2010; 10 (1): 329-333

  Abstract

  Recent theoretical calculations and photoemission spectroscopy measurements on the bulk Bi(2)Se(3) material show that it is a three-dimensional topological insulator possessing conductive surface states with nondegenerate spins, attractive for dissipationless electronics and spintronics applications. Nanoscale topological insulator materials have a large surface-to-volume ratio that can manifest the conductive surface states and are promising candidates for devices. Here we report the synthesis and characterization of high quality single crystalline Bi(2)Se(3) nanomaterials with a variety of morphologies. The synthesis of Bi(2)Se(3) nanowires and nanoribbons employs Au-catalyzed vapor-liquid-solid (VLS) mechanism. Nanowires, which exhibit rough surfaces, are formed by stacking nanoplatelets along the axial direction of the wires. Nanoribbons are grown along [1120] direction with a rectangular cross-section and have diverse morphologies, including quasi-one-dimensional, sheetlike, zigzag and sawtooth shapes. Scanning tunneling microscopy (STM) studies on nanoribbons show atomically smooth surfaces with approximately 1 nm step edges, indicating single Se-Bi-Se-Bi-Se quintuple layers. STM measurements reveal a honeycomb atomic lattice, suggesting that the STM tip couples not only to the top Se atomic layer, but also to the Bi atomic layer underneath, which opens up the possibility to investigate the contribution of different atomic orbitals to the topological surface states. Transport measurements of a single nanoribbon device (four terminal resistance and Hall resistance) show great promise for nanoribbons as candidates to study topological surface states.

  View details for DOI 10.1021/nl903663a

  View details for Web of Science ID 000273428700055

  View details for PubMedID 20030392

• SILICON NANOWIRE HYBRID PHOTOVOLTAICS 35th IEEE Photovoltaic Specialists Conference Garnett, E. C., Peters, C., Brongersma, M., Cui, Y., McGehee, M. IEEE. 2010: 934–938

  View details for Web of Science ID 000287579501035

• Amorphous silicon core-shell nanowire solar cellls Zhu, J., Xu, Y., Wang, Q., Cui, Y. 2010
• Investigations of the Electrochemical Stability of Aqueous Electrolytes for Lithium Battery Applications ELECTROCHEMICAL AND SOLID STATE LETTERS Wessells, C., Ruffo, R., Huggins, R. A., Cui, Y. 2010; 13 (5): A59-A61

  View details for DOI 10.1149/1.3329652

  View details for Web of Science ID 000275660200002

• AMORPHOUS SILICON CORE-SHELL NANOWIRE Schottky SOLAR CELLS 35th IEEE Photovoltaic Specialists Conference Zhu, J., Xu, Y., Wang, Q., Cui, Y. IEEE. 2010: 453–456

  View details for Web of Science ID 000287579500090

• Hard X-ray Full Field Nano-imaging of Bone and Nanowires at SSRL 10th International Conference on Synchrotron Radiation Instrumentation Andrews, J. C., Pianetta, P., Meirer, F., Chen, J., Almeida, E., van der Meulen, M. C., Alwood, J. S., Lee, C., Zhu, J., Cui, Y. AMER INST PHYSICS. 2010: 79–82

  Abstract

  A hard X-ray full field microscope from Xradia Inc. has been installed at SSRL on a 54-pole wiggler end station at beam line 6-2. It has been optimized to operate from 5-14 keV with resolution as high as 30 nm. High quality images are achieved using a vertical beam stabilizer and condenser scanner with high efficiency zone plates with 30 nm outermost zone width. The microscope has been used in Zernike phase contrast, available at 5.4 keV and 8 keV, as well as absorption contrast to image a variety of biological, environmental and materials samples. Calibration of the X-ray attenuation with crystalline apatite enabled quantification of bone density of plate-like and rod-like regions of mouse bone trabecula. 3D tomography of individual lacuna revealed the surrounding cell canaliculi and processes. 3D tomography of chiral branched PbSe nanowires showed orthogonal branches around a central nanowire.

  View details for Web of Science ID 000283705500016

  View details for PubMedCentralID PMC2944249

• Nanostructured Photon Management for High Performance Solar Cells 3rd IEEE International NanoElectronics Conference (INEC)/Symposium on Nanoscience and Nanotechnology in China Cui, Y. IEEE. 2010: 32–33

  View details for Web of Science ID 000282026500015

• Highly conductive paper for energy-storage devices PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Hu, L., Choi, J. W., Yang, Y., Jeong, S., La Mantia, F., Cui, L., Cui, Y. 2009; 106 (51): 21490-21494

  Abstract

  Paper, invented more than 2,000 years ago and widely used today in our everyday lives, is explored in this study as a platform for energy-storage devices by integration with 1D nanomaterials. Here, we show that commercially available paper can be made highly conductive with a sheet resistance as low as 1 ohm per square (Omega/sq) by using simple solution processes to achieve conformal coating of single-walled carbon nanotube (CNT) and silver nanowire films. Compared with plastics, paper substrates can dramatically improve film adhesion, greatly simplify the coating process, and significantly lower the cost. Supercapacitors based on CNT-conductive paper show excellent performance. When only CNT mass is considered, a specific capacitance of 200 F/g, a specific energy of 30-47 Watt-hour/kilogram (Wh/kg), a specific power of 200,000 W/kg, and a stable cycling life over 40,000 cycles are achieved. These values are much better than those of devices on other flat substrates, such as plastics. Even in a case in which the weight of all of the dead components is considered, a specific energy of 7.5 Wh/kg is achieved. In addition, this conductive paper can be used as an excellent lightweight current collector in lithium-ion batteries to replace the existing metallic counterparts. This work suggests that our conductive paper can be a highly scalable and low-cost solution for high-performance energy storage devices.

  View details for DOI 10.1073/pnas.0908858106

  View details for Web of Science ID 000272994200007

  View details for PubMedID 19995965

  View details for PubMedCentralID PMC2799859

• Carbon nanofiber supercapacitors with large areal capacitances APPLIED PHYSICS LETTERS McDonough, J. R., Choi, J. W., Yang, Y., La Mantia, F., Zhang, Y., Cui, Y. 2009; 95 (24)

  View details for DOI 10.1063/1.3273864

  View details for Web of Science ID 000272954900056

• Single Nanorod Devices for Battery Diagnostics: A Case Study on LiMn2O4 NANO LETTERS Yang, Y., Xie, C., Ruffo, R., Peng, H., Kim, D. K., Cui, Y. 2009; 9 (12): 4109-4114

  Abstract

  This paper presents single nanostructure devices as a powerful new diagnostic tool for batteries with LiMn(2)O(4) nanorod materials as an example. LiMn(2)O(4) and Al-doped LiMn(2)O(4) nanorods were synthesized by a two-step method that combines hydrothermal synthesis of beta-MnO(2) nanorods and a solid state reaction to convert them to LiMn(2)O(4) nanorods. lambda-MnO(2) nanorods were also prepared by acid treatment of LiMn(2)O(4) nanorods. The effect of electrolyte etching on these LiMn(2)O(4)-related nanorods is investigated by both SEM and single-nanorod transport measurement, and this is the first time that the transport properties of this material have been studied at the level of an individual single-crystalline particle. Experiments show that Al dopants reduce the dissolution of Mn(3+) ions significantly and make the LiAl(0.1)Mn(1.9)O(4) nanorods much more stable than LiMn(2)O(4) against electrolyte etching, which is reflected by the magnification of both size shrinkage and conductance decrease. These results correlate well with the better cycling performance of Al-doped LiMn(2)O(4) in our Li-ion battery tests: LiAl(0.1)Mn(1.9)O(4) nanorods achieve 96% capacity retention after 100 cycles at 1C rate at room temperature, and 80% at 60 degrees C, whereas LiMn(2)O(4) shows worse retention of 91% at room temperature, and 69% at 60 degrees C. Moreover, temperature-dependent I-V measurements indicate that the sharp electronic resistance increase due to charge ordering transition at 290 K does not appear in our LiMn(2)O(4) nanorod samples, suggesting good battery performance at low temperature.

  View details for DOI 10.1021/nl902315u

  View details for Web of Science ID 000272395400027

  View details for PubMedID 19807129

• Silicon Nanotube Battery Anodes NANO LETTERS Park, M., Kim, M. G., Joo, J., Kim, K., Kim, J., Ahn, S., Cui, Y., Cho, J. 2009; 9 (11): 3844-3847

  Abstract

  We present Si nanotubes prepared by reductive decomposition of a silicon precursor in an alumina template and etching. These nanotubes show impressive results, which shows very high reversible charge capacity of 3247 mA h/g with Coulombic efficiency of 89%, and also demonstrate superior capacity retention even at 5C rate (=15 A/g). Furthermore, the capacity in a Li-ion full cell consisting of a cathode of LiCoO2 and anode of Si nanotubes demonstrates a 10 times higher capacity than commercially available graphite even after 200 cycles.

  View details for DOI 10.1021/nl902058c

  View details for Web of Science ID 000271566400031

  View details for PubMedID 19746961

• Carbon-Silicon Core-Shell Nanowires as High Capacity Electrode for Lithium Ion Batteries NANO LETTERS Cui, L., Yang, Y., Hsu, C., Cui, Y. 2009; 9 (9): 3370-3374

  Abstract

  We introduce a novel design of carbon-silicon core-shell nanowires for high power and long life lithium battery electrodes. Amorphous silicon was coated onto carbon nanofibers to form a core-shell structure and the resulted core-shell nanowires showed great performance as anode material. Since carbon has a much smaller capacity compared to silicon, the carbon core experiences less structural stress or damage during lithium cycling and can function as a mechanical support and an efficient electron conducting pathway. These nanowires have a high charge storage capacity of approximately 2000 mAh/g and good cycling life. They also have a high Coulmbic efficiency of 90% for the first cycle and 98-99.6% for the following cycles. A full cell composed of LiCoO(2) cathode and carbon-silicon core-shell nanowire anode is also demonstrated. Significantly, using these core-shell nanowires we have obtained high mass loading and an area capacity of approximately 4 mAh/cm(2), which is comparable to commercial battery values.

  View details for DOI 10.1021/nl901670t

  View details for Web of Science ID 000269654900049

  View details for PubMedID 19655765

• Impedance Analysis of Silicon Nanowire Lithium Ion Battery Anodes JOURNAL OF PHYSICAL CHEMISTRY C Ruffo, R., Hong, S. S., Chan, C. K., Huggins, R. A., Cui, Y. 2009; 113 (26): 11390-11398

  View details for DOI 10.1021/jp901594g

  View details for Web of Science ID 000267324600033

• Anisotropy of Chemical Transformation from In2Se3 to CuInSe2 Nanowires through Solid State Reaction JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Schoen, D. T., Peng, H., Cui, Y. 2009; 131 (23): 7973-?

  Abstract

  In(2)Se(3) nanowires synthesized by the VLS technique are transformed by solid-state reaction with copper into high-quality single-crystalline CuInSe(2) nanowires. The process is studied by in situ transmission electron microscopy. The transformation temperature exhibits a surprising anisotropy, with In(2)Se(3) nanowires grown along their [0001] direction transforming at a surprisingly low temperature of 225 degrees C, while nanowires in a [11(2)0] orientation require a much higher temperature of 585 degrees C. These results offer a route to the synthesis of CuInSe(2) nanowires at a relatively low temperature as well as insight into the details of a transformation commonly used in the fabrication of thin-film solar cells.

  View details for DOI 10.1021/ja901086t

  View details for Web of Science ID 000267623100018

  View details for PubMedID 19507900

• Printable Thin Film Supercapacitors Using Single-Walled Carbon Nanotubes NANO LETTERS Kaempgen, M., Chan, C. K., Ma, J., Cui, Y., Gruner, G. 2009; 9 (5): 1872-1876

  Abstract

  Thin film supercapacitors were fabricated using printable materials to make flexible devices on plastic. The active electrodes were made from sprayed networks of single-walled carbon nanotubes (SWCNTs) serving as both electrodes and charge collectors. Using a printable aqueous gel electrolyte as well as an organic liquid electrolyte, the performances of the devices show very high energy and power densities (6 W h/kg for both electrolytes and 23 and 70 kW/kg for aqueous gel electrolyte and organic electrolyte, respectively) which is comparable to performance in other SWCNT-based supercapacitor devices fabricated using different methods. The results underline the potential of printable thin film supercapacitors. The simplified architecture and the sole use of printable materials may lead to a new class of entirely printable charge storage devices allowing for full integration with the emerging field of printed electronics.

  View details for DOI 10.1021/nl8038579

  View details for Web of Science ID 000266157100026

  View details for PubMedID 19348455

• Surface chemistry and morphology of the solid electrolyte interphase on silicon nanowire lithium-ion battery anodes JOURNAL OF POWER SOURCES Chan, C. K., Ruffo, R., Hong, S. S., Cui, Y. 2009; 189 (2): 1132-1140

  View details for DOI 10.1016/j.jpowsour.2009.01.007

  View details for Web of Science ID 000265310300038

• Phase Transformation of Biphasic Cu2S-CuInS2 to Monophasic CuInS2 Nanorods JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Connor, S. T., Hsu, C., Weil, B. D., Aloni, S., Cui, Y. 2009; 131 (13): 4962-4966

  Abstract

  We synthesized wurtzite CuInS(2) nanorods (NRs) by colloidal solution-phase growth. We discovered that the growth process starts with nucleation of Cu(2)S nanodisks, followed by epitaxial overgrowth of CuInS(2) NRs onto only one face of Cu(2)S nanodisks, resulting in biphasic Cu(2)S-CISu heterostructured NRs. The phase transformation of biphasic Cu(2)S-CuInS(2) into monophasic CuInS(2) NRs occurred with growth progression. The observed epitaxial overgrowth and phase transformation is facile for three reasons. First, the sharing of the sulfur sublattice by the hexagonal chalcocite Cu(2)S and wurtzite CuInS(2) minimizes the lattice distortion. Second, Cu(2)S is in a superionic conducting state at the growth temperature of 250 degrees C wherein the copper ions move fluidly. Third, the size of the Cu(2)S nanodisks is small, resulting in fast phase transformation. Our results provide valuable insight into the controlled solution growth of ternary chalcogenide nanoparticles and will aid in the development of solar cells using ternary I-III-VI(2) semiconductors.

  View details for DOI 10.1021/ja809901u

  View details for Web of Science ID 000264806300071

  View details for PubMedID 19281233

• Vacancy Ordering and Lithium Insertion in III2VI3 Nanowires NANO RESEARCH Peng, H., Zhang, X. F., Twesten, R. D., Cui, Y. 2009; 2 (4): 327-335

  View details for DOI 10.1007/s12274-009-9030-y

  View details for Web of Science ID 000273939200006

• Structural and electrochemical study of the reaction of lithium with silicon nanowires 14th International Meeting on Lithium Batteries Chan, C. K., Ruffo, R., Hong, S. S., Huggins, R. A., Cui, Y. ELSEVIER SCIENCE BV. 2009: 34–39

  View details for DOI 10.1016/j.jpowsour.2008.12.047

  View details for Web of Science ID 000265317600007

• Tapping mode microwave impedance microscopy REVIEW OF SCIENTIFIC INSTRUMENTS Lai, K., Kundhikanjana, W., Peng, H., Cui, Y., Kelly, M. A., Shen, Z. X. 2009; 80 (4)

  Abstract

  We report tapping mode microwave impedance imaging based on atomic force microscope platforms. The shielded cantilever probe is critical to localize the tip-sample interaction near the tip apex. The modulated tip-sample impedance can be accurately simulated by the finite-element analysis and the result agrees quantitatively to the experimental data on a series of thin-film dielectric samples. The tapping mode microwave imaging is also superior to the contact mode in that the thermal drift in a long time scale is totally eliminated and an absolute measurement on the dielectric properties is possible. We demonstrated tapping images on working nanodevices, and the data are consistent with the transport results.

  View details for DOI 10.1063/1.3123406

  View details for Web of Science ID 000266597100023

  View details for PubMedID 19405666

• Nanoscale Electronic Inhomogeneity in In2Se3 Nanoribbons Revealed by Microwave Impedance Microscopy NANO LETTERS Lai, K., Peng, H., Kundhikanjana, W., Schoen, D. T., Xie, C., Meister, S., Cui, Y., Kelly, M. A., Shen, Z. 2009; 9 (3): 1265-1269

  Abstract

  Driven by interactions due to the charge, spin, orbital, and lattice degrees of freedom, nanoscale inhomogeneity has emerged as a new theme for materials with novel properties near multiphase boundaries. As vividly demonstrated in complex metal oxides (see refs 1-5) and chalcogenides (see refs 6 and 7), these microscopic phases are of great scientific and technological importance for research in high-temperature superconductors (see refs 1 and 2), colossal magnetoresistance effect (see ref 4), phase-change memories (see refs 5 and 6), and domain switching operations (see refs 7-9). Direct imaging on dielectric properties of these local phases, however, presents a big challenge for existing scanning probe techniques. Here, we report the observation of electronic inhomogeneity in indium selenide (In(2)Se(3)) nanoribbons (see ref 10) by near-field scanning microwave impedance microscopy (see refs 11-13). Multiple phases with local resistivity spanning 6 orders of magnitude are identified as the coexistence of superlattice, simple hexagonal lattice and amorphous structures with approximately 100 nm inhomogeneous length scale, consistent with high-resolution transmission electron microscope studies. The atomic-force-microscope-compatible microwave probe is able to perform a quantitative subsurface electrical study in a noninvasive manner. Finally, the phase change memory function in In(2)Se(3) nanoribbon devices can be locally recorded with big signals of opposite signs.

  View details for DOI 10.1021/nl900222j

  View details for Web of Science ID 000264142100060

• Efficient Multiple Exciton Generation Observed in Colloidal PbSe Quantum Dots with Temporally and Spectrally Resolved Intraband Excitation NANO LETTERS Ji, M., Park, S., Connor, S. T., Mokari, T., Cui, Y., Gaffney, K. J. 2009; 9 (3): 1217-1222

  Abstract

  We have spectrally resolved the intraband transient absorption of photogenerated excitons to quantify the exciton population dynamics in colloidal PbSe quantum dots (QDs). These measurements demonstrate that the spectral distribution, as well as the amplitude, of the transient spectrum depends on the number of excitons excited in a QD. To accurately quantify the average number of excitons per QD, the transient spectrum must be spectrally integrated. With spectral integration, we observe efficient multiple exciton generation in colloidal PbSe QDs.

  View details for DOI 10.1021/nl900103f

  View details for Web of Science ID 000264142100052

  View details for PubMedID 19226125

• Three-Dimensional Interconnected Silica Nanotubes Templated from Hyperbranched Nanowires SMALL Zhu, J., Peng, H., Connor, S. T., Cui, Y. 2009; 5 (4): 437-439

  View details for DOI 10.1002/smll.200801083

  View details for Web of Science ID 000264327500003

  View details for PubMedID 19189326

• Nanoscale Electronic Inhomogeneity in In(2)Se(3) Nanoribbons Revealed by Microwave Impedance Microscopy. Nano letters Lai, K., Peng, H., Kundhikanjana, W., Schoen, D. T., Xie, C., Meister, S., Cui, Y., Kelly, M. A., Shen, Z. X. 2009

  Abstract

  Driven by interactions due to the charge, spin, orbital, and lattice degrees of freedom, nanoscale inhomogeneity has emerged as a new theme for materials with novel properties near multiphase boundaries. As vividly demonstrated in complex metal oxides (see refs 1-5) and chalcogenides (see refs 6 and 7), these microscopic phases are of great scientific and technological importance for research in high-temperature superconductors (see refs 1 and 2), colossal magnetoresistance effect (see ref 4), phase-change memories (see refs 5 and 6), and domain switching operations (see refs 7-9). Direct imaging on dielectric properties of these local phases, however, presents a big challenge for existing scanning probe techniques. Here, we report the observation of electronic inhomogeneity in indium selenide (In(2)Se(3)) nanoribbons (see ref 10) by near-field scanning microwave impedance microscopy (see refs 11-13). Multiple phases with local resistivity spanning 6 orders of magnitude are identified as the coexistence of superlattice, simple hexagonal lattice and amorphous structures with approximately 100 nm inhomogeneous length scale, consistent with high-resolution transmission electron microscope studies. The atomic-force-microscope-compatible microwave probe is able to perform a quantitative subsurface electrical study in a noninvasive manner. Finally, the phase change memory function in In(2)Se(3) nanoribbon devices can be locally recorded with big signals of opposite signs.

  View details for DOI 10.1021/nl900222j

  View details for PubMedID 19215080

• Electrochemical behavior of LiCoO2 as aqueous lithium-ion battery electrodes ELECTROCHEMISTRY COMMUNICATIONS Ruffo, R., Wessells, C., Huggins, R. A., Cui, Y. 2009; 11 (2): 247-249

  View details for DOI 10.1016/j.elecom.2008.11.015

  View details for Web of Science ID 000263455600003

• Shape Evolution of Layer-Structured Bismuth Oxychloride Nanostructures via Low-Temperature Chemical Vapor Transport CHEMISTRY OF MATERIALS Peng, H., Chan, C. K., Meister, S., Zhang, X. F., Cui, Y. 2009; 21 (2): 247-252

  View details for DOI 10.1021/cm802041g

  View details for Web of Science ID 000262605200011

• Crystalline-Amorphous Core-Shell Silicon Nanowires for High Capacity and High Current Battery Electrodes NANO LETTERS Cui, L., Ruffo, R., Chan, C. K., Peng, H., Cui, Y. 2009; 9 (1): 491-495

  Abstract

  Silicon is an attractive alloy-type anode material for lithium ion batteries because of its highest known capacity (4200 mAh/g). However silicon's large volume change upon lithium insertion and extraction, which causes pulverization and capacity fading, has limited its applications. Designing nanoscale hierarchical structures is a novel approach to address the issues associated with the large volume changes. In this letter, we introduce a core-shell design of silicon nanowires for highpower and long-life lithium battery electrodes. Silicon crystalline-amorphous core-shell nanowires were grown directly on stainless steel current collectors by a simple one-step synthesis. Amorphous Si shells instead of crystalline Si cores can be selected to be electrochemically active due to the difference of their lithiation potentials. Therefore, crystalline Si cores function as a stable mechanical support and an efficient electrical conducting pathway while amorphous shells store Li(+) ions. We demonstrate here that these core-shell nanowires have high charge storage capacity ( approximately 1000 mAh/g, 3 times of carbon) with approximately 90% capacity retention over 100 cycles. They also show excellent electrochemical performance at high rate charging and discharging (6.8 A/g, approximately 20 times of carbon at 1 h rate).

  View details for DOI 10.1021/nl8036323

  View details for Web of Science ID 000262519100090

  View details for PubMedID 19105648

• Phase transformations in one-dimensional materials: applications in electronics and energy sciences JOURNAL OF MATERIALS CHEMISTRY Schoen, D. T., Meister, S., Peng, H., Chan, C., Yang, Y., Cui, Y. 2009; 19 (33): 5879-5890

  View details for DOI 10.1039/b820624d

  View details for Web of Science ID 000268885900002

• Optical Absorption Enhancement in Amorphous Silicon Nanowire and Nanocone Arrays NANO LETTERS Zhu, J., Yu, Z., Burkhard, G. F., Hsu, C., Connor, S. T., Xu, Y., Wang, Q., McGehee, M., Fan, S., Cui, Y. 2009; 9 (1): 279-282

  Abstract

  Hydrogenated amorphous Si (a-Si:H) is an important solar cell material. Here we demonstrate the fabrication of a-Si:H nanowires (NWs) and nanocones (NCs), using an easily scalable and IC-compatible process. We also investigate the optical properties of these nanostructures. These a-Si:H nanostructures display greatly enhanced absorption over a large range of wavelengths and angles of incidence, due to suppressed reflection. The enhancement effect is particularly strong for a-Si:H NC arrays, which provide nearly perfect impedance matching between a-Si:H and air through a gradual reduction of the effective refractive index. More than 90% of light is absorbed at angles of incidence up to 60 degrees for a-Si:H NC arrays, which is significantly better than NW arrays (70%) and thin films (45%). In addition, the absorption of NC arrays is 88% at the band gap edge of a-Si:H, which is much higher than NW arrays (70%) and thin films (53%). Our experimental data agree very well with simulation. The a-Si:H nanocones function as both absorber and antireflection layers, which offer a promising approach to enhance the solar cell energy conversion efficiency.

  View details for DOI 10.1021/nl802886y

  View details for Web of Science ID 000262519100052

  View details for PubMedID 19072061

• Void Formation Induced Electrical Switching in Phase-Change Nanowires NANO LETTERS Meister, S., Schoen, D. T., Topinka, M. A., Minor, A. M., Cui, Y. 2008; 8 (12): 4562-4567

  Abstract

  Solid-state structural transformation coupled with an electronic property change is an important mechanism for nonvolatile information storage technologies, such as phase-change memories. Here we exploit phase-change GeTe single-nanowire devices combined with ex situ and in situ transmission electron microscopy to correlate directly nanoscale structural transformations with electrical switching and discover surprising results. Instead of crystalline-amorphous transformation, the dominant switching mechanism during multiple cycling appears to be the opening and closing of voids in the nanowires due to material migration, which offers a new mechanism for memory. During switching, composition change and the formation of banded structural defects are observed in addition to the expected crystal-amorphous transformation. Our method and results are important to phase-change memories specifically, but also to any device whose operation relies on a small scale structural transformation.

  View details for DOI 10.1021/nl802808f

  View details for Web of Science ID 000261630700082

  View details for PubMedID 19367977

• Spinel LiMn2O4 Nanorods as Lithium Ion Battery Cathodes NANO LETTERS Kim, D. K., Muralidharan, P., Lee, H., Ruffo, R., Yang, Y., Chan, C. K., Peng, H., Huggins, R. A., Cui, Y. 2008; 8 (11): 3948-3952

  Abstract

  Spinel LiMn2O4 is a low-cost, environmentally friendly, and highly abundant material for Li-ion battery cathodes. Here, we report the hydrothermal synthesis of single-crystalline beta-MnO2 nanorods and their chemical conversion into free-standing single-crystalline LiMn2O4 nanorods using a simple solid-state reaction. The LiMn2O4 nanorods have an average diameter of 130 nm and length of 1.2 microm. Galvanostatic battery testing showed that LiMn2O4 nanorods have a high charge storage capacity at high power rates compared with commercially available powders. More than 85% of the initial charge storage capacity was maintained for over 100 cycles. The structural transformation studies showed that the Li ions intercalated into the cubic phase of the LiMn2O4 with a small change of lattice parameter, followed by the coexistence of two nearly identical cubic phases in the potential range of 3.5 to 4.3 V.

  View details for DOI 10.1021/nl8024328

  View details for Web of Science ID 000260888600070

  View details for PubMedID 18826287

• Wafer-scale silicon nanopillars and nanocones by Langmuir-Blodgett assembly and etching APPLIED PHYSICS LETTERS Hsu, C., Connor, S. T., Tang, M. X., Cui, Y. 2008; 93 (13)

  View details for DOI 10.1063/1.2988893

  View details for Web of Science ID 000259794100084

• Formation of chiral branched nanowires by the Eshelby Twist NATURE NANOTECHNOLOGY Zhu, J., Peng, H., Marshall, A. F., Barnett, D. M., Nix, W. D., Cui, Y. 2008; 3 (8): 477-481

  Abstract

  Manipulating the morphology of inorganic nanostructures, such as their chirality and branching structure, has been actively pursued as a means of controlling their electrical, optical and mechanical properties. Notable examples of chiral inorganic nanostructures include carbon nanotubes, gold multishell nanowires, mesoporous nanowires and helical nanowires. Branched nanostructures have also been studied and been shown to have interesting properties for energy harvesting and nanoelectronics. Combining both chiral and branching motifs into nanostructures might provide new materials properties. Here we show a chiral branched PbSe nanowire structure, which is formed by a vapour-liquid-solid branching from a central nanowire with an axial screw dislocation. The chirality is caused by the elastic strain of the axial screw dislocation, which produces a corresponding Eshelby Twist in the nanowires. In addition to opening up new opportunities for tailoring the properties of nanomaterials, these chiral branched nanowires also provide a direct visualization of the Eshelby Twist.

  View details for DOI 10.1038/nnano.2008.179

  View details for Web of Science ID 000258325800011

  View details for PubMedID 18685634

• Large anisotropy of electrical properties in layer-structured In2Se3 nanowires NANO LETTERS Peng, H., Xie, C., Schoen, D. T., Cui, Y. 2008; 8 (5): 1511-1516

  Abstract

  Layer-structured indium selenide (In 2Se 3) nanowires (NWs) have large anisotropy in both shape and bonding. In 2Se 3 NWs show two types of growth directions: [11-20] along the layers and [0001] perpendicular to the layers. We have developed a powerful technique combining high-resolution transmission electron microscopy (HRTEM) investigation with single NW electrical transport measurement, which allows us to correlate directly the electrical properties and structure of the same individual NWs. The NW devices were made directly on a 50 nm thick SiN x membrane TEM window for electrical measurements and HRTEM study. NWs with the [11-20] growth direction exhibit metallic behavior while the NWs grown along the [0001] direction show n-type semiconductive behavior. Excitingly, the conductivity anisotropy reaches 10 (3)-10 (6) at room temperature, which is 1-3 orders magnitude higher than the bulk ratio.

  View details for DOI 10.1021/nl080524d

  View details for Web of Science ID 000255906400043

  View details for PubMedID 18407699

• Solution-processed metal nanowire mesh transparent electrodes NANO LETTERS Lee, J., Connor, S. T., Cui, Y., Peumans, P. 2008; 8 (2): 689-692

  Abstract

  Transparent conductive electrodes are important components of thin-film solar cells, light-emitting diodes, and many display technologies. Doped metal oxides are commonly used, but their optical transparency is limited for films with a low sheet resistance. Furthermore, they are prone to cracking when deposited on flexible substrates, are costly, and require a high-temperature step for the best performance. We demonstrate solution-processed transparent electrodes consisting of random meshes of metal nanowires that exhibit an optical transparency equivalent to or better than that of metal-oxide thin films for the same sheet resistance. Organic solar cells deposited on these electrodes show a performance equivalent to that of devices based on a conventional metal-oxide transparent electrode.

  View details for DOI 10.1021/nl073296g

  View details for Web of Science ID 000253166200058

  View details for PubMedID 18189445

• High-performance lithium battery anodes using silicon nanowires NATURE NANOTECHNOLOGY Chan, C. K., Peng, H., Liu, G., Mcilwrath, K., Zhang, X. F., Huggins, R. A., Cui, Y. 2008; 3 (1): 31-35

  Abstract

  There is great interest in developing rechargeable lithium batteries with higher energy capacity and longer cycle life for applications in portable electronic devices, electric vehicles and implantable medical devices. Silicon is an attractive anode material for lithium batteries because it has a low discharge potential and the highest known theoretical charge capacity (4,200 mAh g(-1); ref. 2). Although this is more than ten times higher than existing graphite anodes and much larger than various nitride and oxide materials, silicon anodes have limited applications because silicon's volume changes by 400% upon insertion and extraction of lithium which results in pulverization and capacity fading. Here, we show that silicon nanowire battery electrodes circumvent these issues as they can accommodate large strain without pulverization, provide good electronic contact and conduction, and display short lithium insertion distances. We achieved the theoretical charge capacity for silicon anodes and maintained a discharge capacity close to 75% of this maximum, with little fading during cycling.

  View details for DOI 10.1038/nnano.2007.411

  View details for Web of Science ID 000252117000012

  View details for PubMedID 18654447

• Nanowire Batteries for Next Generation Electronics IEEE International Electron Devices Meeting Chan, C. K., Connor, S. T., Yang, Y., Hsu, C., Huggins, R. A., Cui, Y. IEEE. 2008: 175–178

  View details for Web of Science ID 000265829300039

• High capacity Li ion battery anodes using Ge nanowires NANO LETTERS Chan, C. K., Zhang, X. F., Cui, Y. 2008; 8 (1): 307-309

  Abstract

  Ge nanowire electrodes fabricated by using vapor-liquid-solid growth on metallic current collector substrates were found to have good performance during cycling with Li. An initial discharge capacity of 1141 mA.h/g was found to be stable over 20 cycles at the C/20 rate. High power rates were also observed up to 2C with Coulombic efficiency > 99%. Structural characterization revealed that the Ge nanowires remain intact and connected to the current collector after cycling. Nanowires connected directly to the current collector have facile strain relaxation and material durability, short Li diffusion distances, and good electronic conduction. Thus, Ge nanowire anodes are promising candidates for the development of high-energy-density lithium batteries.

  View details for DOI 10.1021/nl0727157

  View details for Web of Science ID 000252257700054

  View details for PubMedID 18095738

• Ordered vacancy compounds and nanotube formation in CulnSe(2)-CdS core-shell nanowires NANO LETTERS Peng, H., Xie, C., Schoen, D. T., Mcilwrath, K., Zhang, X. F., Cui, Y. 2007; 7 (12): 3734-3738

  View details for DOI 10.1021/nl0721463

  View details for Web of Science ID 000251581600033

• Towards electrically driven nanowire single-photon sources SMALL Zhu, J., Cui, Y. 2007; 3 (8): 1322-1323

  View details for DOI 10.1002/smll.200700237

  View details for Web of Science ID 000248641600002

  View details for PubMedID 17600801

• Electrical switching and phase transformation in silver selenide nanowires JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Schoen, D. T., Xie, C., Cui, Y. 2007; 129 (14): 4116-?

  View details for DOI 10.1021/ja068365s

  View details for Web of Science ID 000245723800004

  View details for PubMedID 17367137

• Hyperbranched lead selenide nanowire networks NANO LETTERS Zhu, J., Peng, H., Chan, C. K., Jarausch, K., Zhang, X. F., Cui, Y. 2007; 7 (4): 1095-1099

  Abstract

  Lead chalcogenide nanostructures are good potential candidates for applications in multiexciton solar cells, infrared photodetectors, and electroluminescence devices. Here we report the synthesis and electrical measurements of hyperbranched PbSe nanowire networks. Hyperbranched PbSe nanowire networks are synthesized via a vapor-liquid-solid (VLS) mechanism. The branching is induced by continuously feeding the PbSe reactant with the vapor of a low-melting-point metal catalyst including In, Ga, and Bi. The branches show very regular orientation relationships: either perpendicular or parallel to each other. The diameter of the individual NWs depends on the size of the catalyst droplets, which can be controlled by the catalyst vapor pressure. Significantly, the hyperbranched networks can be grown epitaxially on NaCl, a low-cost substrate for future device array applications. Electrical measurements across branched NWs show the evolution of charge carrier transport with distance and degree of branching.

  View details for DOI 10.1021/nl0700393

  View details for Web of Science ID 000245600500046

  View details for PubMedID 17348716

• Fast, completely reversible Li insertion in vanadium pentoxide nanoribbons NANO LETTERS Chan, C. K., Peng, H., Twesten, R. D., Jarausch, K., Zhang, X. F., Cui, Y. 2007; 7 (2): 490-495

  Abstract

  Layered-structure nanoribbons with efficient electron transport and short lithium ion insertion lengths are promising candidates for Li battery applications. Here we studied at the single nanostructure level the chemical, structural, and electrical transformations of V2O5 nanoribbons. We found that transformation of V2O5 into the omega-Li3V2O5 phase depends not only on the width but also the thickness of the nanoribbons. Transformation can take place within 10 s in thin nanoribbons, suggesting a Li diffusion constant 3 orders of magnitude faster than in bulk materials, resulting in a significant increase in battery power density (360 C power rate). For the first time, complete delithiation of omega-Li3V2O5 back to the single-crystalline, pristine V2O5 nanoribbon was observed, indicating a 30% higher energy density. These new observations are attributed to the ability of facile strain relaxation and phase transformation at the nanoscale. In addition, efficient electronic transport can be maintained to charge a Li3V2O5 nanoribbon within less than 5 s. These exciting nanosize effects can be exploited to fabricate high-performance Li batteries for applications in electric and hybrid electric vehicles.

  View details for DOI 10.1021/nl062883j

  View details for Web of Science ID 000244206500049

  View details for PubMedID 17256918

• Synthesis and phase transformation of In2Se3 and CuInSe2 nanowires JOURNAL OF THE AMERICAN CHEMICAL SOCIETY Peng, H., Schoen, D. T., Meister, S., Zhang, X. F., Cui, Y. 2007; 129 (1): 34-35

  View details for DOI 10.1021/ja067436k

  View details for Web of Science ID 000243195100017

  View details for PubMedID 17199275

• Phase-change nanowires for non volatile memory Symposium on Materials and Processes for Nonvolatile Memories II held at the 2007 MRS Spring Meeting Cui, Y., Meister, S., Peng, H. MATERIALS RESEARCH SOCIETY. 2007: 299–304

  View details for Web of Science ID 000252015300042

• Nanowires for Nanoscale Electronics, Biosensors and Energy Applications (invited paper) Meister, S., Chan, C., K., Peng, H., Cui, Y. 2007
• Mechanical and Electrical Properties of CdTe Tetrapods Studied by Atomic Force Microscopy J. Chem. Phys. Fang, L., Park, J., Y., Cui, Y., Alivisatos, P., Shcrier, J., Lee, B. 2007; 127: 184704
• Phase-Change Nanowires for Non Volatile Memory Meister, S., Peng, H., Cui, Y. 2007
• Morphology control of layer-structured gallium selenide nanowires NANO LETTERS Peng, H., Meister, S., Chan, C. K., Zhang, X. F., Cui, Y. 2007; 7 (1): 199-203

  Abstract

  Layer-structured group III chalcogenides have highly anisotropic properties and are attractive materials for stable photocathodes and battery electrodes. We report the controlled synthesis and characterization of layer-structured GaSe nanowires via a catalyst-assisted vapor-liquid-solid (VLS) growth mechanism during GaSe powder evaporation. GaSe nanowires consist of Se-Ga-Ga-Se layers stacked together via van der Waals interactions to form belt-shaped nanowires with a growth direction along the [11-20], width along the [1-100], and height along the [0001] direction. Nanobelts exhibit a variety of morphologies including straight, zigzag, and saw-tooth shapes. These morphologies are realized by controlling the growth temperature and time so that the actual catalysts have a chemical composition of Au, Au-Ga alloy, or Ga. The participation of Ga in the VLS catalyst is important for achieving different morphologies of GaSe. In addition, GaSe nanotubes are also prepared by a slow growth process.

  View details for DOI 10.1021/nl062047+

  View details for Web of Science ID 000243381300035

  View details for PubMedID 17212464

• Synthesis and characterization of phase-change nanowires NANO LETTERS Meister, S., Peng, H., Mcilwrath, K., Jarausch, K., Zhang, X. F., Cui, Y. 2006; 6 (7): 1514-1517

  Abstract

  Phase-change memory materials have stimulated a great deal of interest although the size-dependent behaviors have not been well studied due to the lack of method for producing their nanoscale structures. We report the synthesis and characterization of GeTe and Sb(2)Te(3) phase-change nanowires via a vapor-liquid-solid growth mechanism. The as-grown GeTe nanowires have three different types of morphologies: single-crystalline straight and helical rhombohedral GeTe nanowires and amorphous curly GeO(2) nanowires. All the Sb(2)Te(3) nanowires are single-crystalline.

  View details for DOI 10.1021/nl061102b

  View details for Web of Science ID 000238973100041

  View details for PubMedID 16834441

• Electrical Transport Through a Single Nanoscale Semiconductor Branch Point Nano Letters Cui, Y., Banin, U., Bj?rk, M., Alivisatos, A., P. 2005; 5: 1519-1523
• Multiplexed Electrical Detection of Cancer Markers with Nanowire Sensor Arrays Nature Biotech. Zheng, G., Patolsky, F., Cui, Y., Wang, W., U., Lieber, C., M. 2005; 23: 1294-1301
• Lithographically Directed Self-Assembly of Nanostructures J. Vac. Sci. Tech. Liddle, J., A., Cui, Y., Alivisatos, A., P. 2004; B22: 3409-3414
• Controlled Growth and Structures of Molecular-Scale Silicon Nanowires Nano Letters Wu, Y., Cui, Y., Huynh, L., Barlett, C., Lieber, C., M. 2004; 4: 433-436
• Integration of Colloidal Nanocrystals into Lithographicall Patterned Devices Nano Letters Cui, Y., Bj?rk, M., Liddle, J., A., S?nnichsen, C., Boussert, B., Alivisatos, A., P. 2004; 4: 1093-1098
• Colloidal Nanocrystal Heterostructures with Linear and Branched Topology Nature Milliron, D., Hughes, S., Cui, Y., Manna, L., Li, J., Wang, L., W. 2004; 430: 190-195
• in Molecular Nanoelectronics Nanowires as Building Blocks for Nanoscale Electronics and Optoelectronic Duan, X., Huang, Y., Cui, Y., Lieber, C., M. edited by Reed, M., Lee, T. American Scientific Publisher. 2003: 1
• Nanowire Crossbar Arrays as Address Decoders for Integrated Nanosystems Science Zhong, Z., Wang, D., Cui, Y., Bockrath, M., W., Lieber, C., M. 2003; 302: 1377-1379
• High Performance Silicon Nanowire Field Effect Transistors Nano Letters Cui, Y., Zhong, Z., Wang, D., Wang, W., U., Lieber, C., M. 2003; 3: 149-152
• Nanowires as Building Blocks for Nanoscale Electronics and Optoelectronics in Molecular Nanoelectronics Duan, X., Huang, Y., Cui, Y., Lieber, C., M. edited by Reed, M., Lee, T. American Scientific Publisher. 2003: 1
• in Nanowires and Nanobelts- Materials, Properties, and Devices Nanowires as Building Blocks for Nanoscale Science and Technology Cui, Y., Duan, X., Huang, Y., Lieber, C., M. edited by Wang, Z., L. Kluwer Academic/Plenum Publishers. 2003: 1
• Nanowires as Building Blocks for Nanoscale Science and Technology in Nanowires and Nanobelts- Materials, Properties, and Devices Cui, Y., Duan, X., C., Y., Huang edited by Wang, Z., L. Kluwer Academic/Plenum Publishers. 2003: 1
• Gallium Nitride Nanowire Nanodevices Nano Letters Huang, Y., Duan, X., Cui, Y., Lieber, C., M. 2002; 2: 101-104
• Diameter-Controlled Synthesis of Single Crystal Silicon Nanowires App. Phys. Lett. Cui, Y., Lauhon, L., J., Gudiksen, M., S., Wang, J., Lieber, C., M. 2001; 78: 2214-2216
• Functional Nanoscale Electronic Devices Assembled using Silicon Nanowire Building Block Scienc Cui, Y., Lieber, C., M. 2001; 291: 851-853
• Indium Phosphide Nanowires as Building Blocks for Nanoscale Electronic and Optoelectronic Devices Nature Duan, X., Huang, Y., Cui, Y., Wang, J., Lieber, C., M. 2001; 409: 66-69
• Logic Gates and Computation from Assembled Nanowire Building Blocks Science Huang, Y., Duan, X., Cui, Y., Lauhon, L., J., Kim, K., Lieber, C., M. 2001; 294: 1313-1317
• Nanowire Nanosensors for Highly-Sensitive, Selective and Integrated Detection of Biological and Chemical Species Scienc Cui, Y., Wei, Q., Park, H., Lieber, C., M. 2001; 293: 1289-1292
• Highly Polarized Photoluminescence and Polarization-Sensitive Photodetectors from Single Indium Phosphide Nanowirees Science Wang, J., Gudiksen, M., K., Duan, X., Cui, Y., Lieber, C., M. 2001; 293: 1455-1457
• Doping and Electrical Transport in Silicon Nanowires J. Phys. Chem. Cui, Y., Duan, X., Hu, J., Lieber, C., M. 2000; B 104: 5213-5216
• Two-dimensional chalcogenide nanoplates as tunable metamaterials via chemical intercalation Nano Letters Cha, J., J., Koski, K., J., Huang, K., C. Y., Wang, K., X., Luo, W., Kong, D., Cui, Y.

  View details for DOI 10.1021/nl402937g