Stanford Advisors

All Publications

  • High-Capacity Rechargeable Li/Cl2 Batteries with Graphite Positive Electrodes. Journal of the American Chemical Society Zhu, G., Liang, P., Huang, C. L., Huang, C. C., Li, Y. Y., Wu, S. C., Li, J., Wang, F., Tian, X., Huang, W. H., Jiang, S. K., Hung, W. H., Chen, H., Lin, M. C., Hwang, B. J., Dai, H. 2022


    Developing new types of high-capacity and high-energy density rechargeable batteries is important to future generations of consumer electronics, electric vehicles, and mass energy storage applications. Recently, we reported ∼3.5 V sodium/chlorine (Na/Cl2) and lithium/chlorine (Li/Cl2) batteries with up to 1200 mAh g-1 reversible capacity, using either a Na or a Li metal as the negative electrode, an amorphous carbon nanosphere (aCNS) as the positive electrode, and aluminum chloride (AlCl3) dissolved in thionyl chloride (SOCl2) with fluoride-based additives as the electrolyte [Zhu et al., Nature, 2021, 596 (7873), 525-530]. The high surface area and large pore volume of aCNS in the positive electrode facilitated NaCl or LiCl deposition and trapping of Cl2 for reversible NaCl/Cl2 or LiCl/Cl2 redox reactions and battery discharge/charge cycling. Here, we report an initially low surface area/porosity graphite (DGr) material as the positive electrode in a Li/Cl2 battery, attaining high battery performance after activation in carbon dioxide (CO2) at 1000 °C (DGr_ac) with the first discharge capacity ∼1910 mAh g-1 and a cycling capacity up to 1200 mAh g-1. Ex situ Raman spectroscopy and X-ray diffraction (XRD) revealed the evolution of graphite over battery cycling, including intercalation/deintercalation and exfoliation that generated sufficient pores for hosting LiCl/Cl2 redox. This work opens up widely available, low-cost graphitic materials for high-capacity alkali metal/Cl2 batteries. Lastly, we employed mass spectrometry to probe the Cl2 trapped in the graphitic positive electrode, shedding light into the Li/Cl2 battery operation.

    View details for DOI 10.1021/jacs.2c07826

    View details for PubMedID 36450002

  • A Non-Flammable High-Voltage 4.7 V Anode-Free Lithium Battery. Advanced materials (Deerfield Beach, Fla.) Liang, P., Sun, H., Huang, C., Zhu, G., Tai, H., Li, J., Wang, F., Wang, Y., Huang, C., Jiang, S., Lin, M., Li, Y., Hwang, B., Wang, C., Dai, H. 2022: e2207361


    Anode-free lithium metal batteries employ in-situ lithium plated current collectors as negative electrodes to afford optimal mass and volumetric energy densities. The main challenges to such batteries include their poor cycling stability and safety issues of flammable organic electrolytes. Here, we report a high-voltage 4.7V anode-free lithium metal battery using a Cu foil coated with a layer ( 950nm) of silicon-polyacrylonitrile (Si-PAN, 25.5mug cm-2 ) as the negative electrode, a high-voltage cobalt-free LiNi0.5 Mn1.5 O4 (LNMO) as the positive electrode and a safe, non-flammable ionic liquid electrolyte comprised of 4.5M lithium bis(fluorosulfonyl)imide (LiFSI) salt in N-methyl-N-propyl pyrrolidiniumbis(fluorosulfonyl)imide (Py13 FSI) with 1 wt% lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as additive. The Si-PAN coating was found to seed the growth of lithium during charging, and reversibly expand/shrink during lithium plating/stripping over battery cycling. The wide voltage-window electrolyte containing a high concentration of FSI- and TFSI- facilitated the formation of stable solid-electrolyte interphase, affording a 4.7V anode-free Cu@Si-PAN/LiNi0.5 Mn1.5 O4 battery with a reversible specific capacity of 120 mAh g-1 and high cycling stability (80% capacity retention after 120 cycles). These results represent the first anode-free Li battery with a high 4.7V discharge voltage and high safety. This article is protected by copyright. All rights reserved.

    View details for DOI 10.1002/adma.202207361

    View details for PubMedID 36193778

  • High-precision tumor resection down to few-cell level guided by NIR-IIb molecular fluorescence imaging. Proceedings of the National Academy of Sciences of the United States of America Wang, F., Qu, L., Ren, F., Baghdasaryan, A., Jiang, Y., Hsu, R., Liang, P., Li, J., Zhu, G., Ma, Z., Dai, H. 2022; 119 (15): e2123111119


    SignificanceSurgical removal of tumors has been performed to combat cancer for over a century by surgeons relying on visual inspection and experience to identify margins between malignant and healthy tissues. Herein, we present a rare-earth down-conversion nanoparticle-anti-CD105 conjugate for cancer targeting and a handheld imager capable of concurrent photographic imaging and fluorescence/luminescence imaging. An unprecedented tumor-to-muscle ratio was achieved by near-infrared-IIb (NIR-IIb, 1,500 to 1,700 nm) imaging during surgery, 100 times higher than previous organic dyes for unambiguous determination of tumor margin. The sensitivity/biocompatibility/safety of the probes and instrumentation developed here open a paradigm of imaging-guided surgery at the single-cell level, meeting all major requirements for clinical translation to combat cancer and save human lives.

    View details for DOI 10.1073/pnas.2123111119

    View details for PubMedID 35380898

  • Rechargeable Na/Cl2 and Li/Cl2 batteries. Nature Zhu, G., Tian, X., Tai, H., Li, Y., Li, J., Sun, H., Liang, P., Angell, M., Huang, C., Ku, C., Hung, W., Jiang, S., Meng, Y., Chen, H., Lin, M., Hwang, B., Dai, H. 2021; 596 (7873): 525-530


    Lithium-ion batteries (LIBs) are widely used in applications ranging from electric vehicles to wearable devices. Before the invention of secondary LIBs, the primary lithium-thionyl chloride (Li-SOCl2) battery was developed in the 1970s using SOCl2 as the catholyte, lithium metal as the anode and amorphous carbon as the cathode1-7. This battery discharges by lithium oxidation and catholyte reduction to sulfur, sulfur dioxide and lithium chloride, is well known for its high energy density and is widely used in real-world applications; however, it has not been made rechargeable since its invention8-13. Here we show that with a highly microporous carbon positive electrode, a starting electrolyte composed of aluminium chloride in SOCl2 with fluoride-based additives, and either sodium or lithium as the negative electrode, we can produce a rechargeable Na/Cl2 or Li/Cl2 battery operating via redox between mainly Cl2/Cl- in the micropores of carbon and Na/Na+ or Li/Li+ redox on the sodium or lithium metal. The reversible Cl2/NaCl or Cl2/LiCl redox in the microporous carbon affords rechargeability at the positive electrodeside and the thin alkali-fluoride-doped alkali-chloride solid electrolyte interfacestabilizesthe negative electrode, both are critical to secondary alkali-metal/Cl2 batteries.

    View details for DOI 10.1038/s41586-021-03757-z

    View details for PubMedID 34433941

  • Selective and High Current CO2 Electro-Reduction to Multicarbon Products in Near-Neutral KCl Electrolytes. Journal of the American Chemical Society Zhang, X., Li, J., Li, Y., Jung, Y., Kuang, Y., Zhu, G., Liang, Y., Dai, H. 2021


    Reducing CO2 to value-added multicarbon (C2+) fuels and chemicals using renewable energy is a viable way to circumvent CO2 buildup in the atmosphere and facilitate closing the carbon cycle. To date it remains a challenge to achieve high product selectivity and long-term stability of electrocatalytic carbon dioxide reduction reaction (CO2RR) especially at practically relevant high current levels >100 mA cm-2. Here, we report a simple electrodeposited Cu electrocatalyst on a hydrophobic porous gas-diffusion layer (GDL) electrode affording stable and selective CO2RR to C2+ products in near-neutral KCl electrolytes. By directing the CO2 stream to fully submerged hydrophobic GDLs in a H-cell, high C2+ partial current densities near 100 mA cm-2 were achieved. In a flow-cell setup, the Cu/GDL cathode in 2 M KCl afforded stable CO2RR superior to that in widely used KOH electrolytes. We found that Cu etching/corrosion associated with trace oxygen played a role in the catalyst instability in alkaline media under cathodic CO2RR conditions, a problem largely suppressed in near-neutral electrolyte. A two-electrode CO2 electrolyzer was constructed with a Cu/GDL cathode in KCl catholyte and an anode comprised of nickel-iron hydroxide on nickel foam (NiFe/NF) in a KOH anolyte separated by Nafion membrane. By periodically adding HCl to the KCl catholyte to compensate the increasing pH and remove accumulated (bi)carbonates, we observed little decay over 30 h in flow-cell CO2RR activity and selectivity at 150 mA cm-2 with a high Faradaic efficiency (FE) of 75% and energy efficiency of 40% for C2+ products.

    View details for DOI 10.1021/jacs.0c13427

    View details for PubMedID 33617245

  • A high-performance potassium metal battery using safe ionic liquid electrolyte. Proceedings of the National Academy of Sciences of the United States of America Sun, H., Liang, P., Zhu, G., Hung, W. H., Li, Y., Tai, H., Huang, C., Li, J., Meng, Y., Angell, M., Wang, C., Dai, H. 2020


    Potassium secondary batteries are contenders of next-generation energy storage devices owing to the much higher abundance of potassium than lithium. However, safety issues and poor cycle life of K metal battery have been key bottlenecks. Here we report an ionic liquid electrolyte comprising 1-ethyl-3-methylimidazolium chloride/AlCl3/KCl/potassium bis(fluorosulfonyl) imide for safe and high-performance batteries. The electrolyte is nonflammable and exhibits a high ionic conductivity of 13.1 mS cm-1 at room temperature. A 3.6-V battery with K anode and Prussian blue/reduced graphene oxide cathode delivers a high energy and power density of 381 and 1,350 W kg-1, respectively. The battery shows an excellent cycling stability over 820 cycles, retaining 89% of the original capacity with high Coulombic efficiencies of 99.9%. High cyclability is also achieved at elevated temperatures up to 60 °C. Uniquely, robust K, Al, F, and Cl-containing passivating interphases are afforded with this electrolyte, which is key to superior battery cycling performances.

    View details for DOI 10.1073/pnas.2012716117

    View details for PubMedID 33106405

  • High-Safety and High-Energy-Density Lithium Metal Batteries in a Novel Ionic-Liquid Electrolyte. Advanced materials (Deerfield Beach, Fla.) Sun, H., Zhu, G., Zhu, Y., Lin, M., Chen, H., Li, Y., Hung, W. H., Zhou, B., Wang, X., Bai, Y., Gu, M., Huang, C., Tai, H., Xu, X., Angell, M., Shyue, J., Dai, H. 2020: e2001741


    Rechargeable lithium metal batteries are next generation energy storage devices with high energy density, but face challenges in achieving high energy density, high safety, and long cycle life. Here, lithium metal batteries in a novel nonflammable ionic-liquid (IL) electrolyte composed of 1-ethyl-3-methylimidazolium (EMIm) cations and high-concentration bis(fluorosulfonyl)imide (FSI) anions, with sodium bis(trifluoromethanesulfonyl)imide (NaTFSI) as a key additive are reported. The Na ion participates in the formation of hybrid passivation interphases and contributes to dendrite-free Li deposition and reversible cathode electrochemistry. The electrolyte of low viscosity allows practically useful cathode mass loading up to 16 mg cm-2 . Li anodes paired with lithium cobalt oxide (LiCoO2 ) and lithium nickel cobalt manganese oxide (LiNi0.8 Co0.1 Mn0.1 O2 , NCM 811) cathodes exhibit 99.6-99.9% Coulombic efficiencies, high discharge voltages up to 4.4 V, high specific capacity and energy density up to 199 mAh g-1 and 765 Wh kg-1 respectively, with impressive cycling performances over up to 1200 cycles. Highly stable passivation interphases formed on both electrodes in the novel IL electrolyte are the key to highly reversible lithium metal batteries, especially for Li-NMC 811 full batteries.

    View details for DOI 10.1002/adma.202001741

    View details for PubMedID 32449260

  • Electroreduction of CO2 to Formate on a Copper-Based Electrocatalyst at High Pressures with High Energy Conversion Efficiency. Journal of the American Chemical Society Li, J. n., Kuang, Y. n., Meng, Y. n., Tian, X. n., Hung, W. H., Zhang, X. n., Li, A. n., Xu, M. n., Zhou, W. n., Ku, C. S., Chiang, C. Y., Zhu, G. n., Guo, J. n., Sun, X. n., Dai, H. n. 2020


    Electrocatalytic CO2 reduction (CO2RR) to valuable fuels is a promising approach to mitigate energy and environmental problems, but controlling the reaction pathways and products remains challenging. Here a novel Cu2O nanoparticle film was synthesized by square-wave (SW) electrochemical redox cycling of high-purity Cu foils. The cathode afforded up to 98% Faradaic efficiency for electroreduction of CO2 to nearly pure formate under ≥45 atm CO2 in bicarbonate catholytes. When this cathode was paired with a newly developed NiFe hydroxide carbonate anode in KOH/borate anolyte, the resulting two-electrode high-pressure electrolysis cell achieved high energy conversion efficiencies of up to 55.8% stably for long-term formate production. While the high-pressure conditions drastically increased the solubility of CO2 to enhance CO2 reduction and suppress hydrogen evolution, the (111)-oriented Cu2O film was found to be important to afford nearly 100% CO2 reduction to formate. The results have implications for CO2 reduction to a single liquid product with high energy conversion efficiency.

    View details for DOI 10.1021/jacs.0c00122

    View details for PubMedID 32250611

  • Ionic Liquid Analogs of AlCl3 with Urea Derivatives as Electrolytes for Aluminum Batteries ADVANCED FUNCTIONAL MATERIALS Angell, M., Zhu, G., Lin, M., Rong, Y., Dai, H. 2019
  • A safe and non-flammable sodium metal battery based on an ionic liquid electrolyte. Nature communications Sun, H., Zhu, G., Xu, X., Liao, M., Li, Y., Angell, M., Gu, M., Zhu, Y., Hung, W. H., Li, J., Kuang, Y., Meng, Y., Lin, M., Peng, H., Dai, H. 2019; 10 (1): 3302


    Rechargeable sodium metal batteries with high energy density could be important to a wide range of energy applications in modern society. The pursuit of higher energy density should ideally come with high safety, a goal difficult for electrolytes based on organic solvents. Here we report a chloroaluminate ionic liquid electrolyte comprised of aluminium chloride/1-methyl-3-ethylimidazolium chloride/sodium chloride ionic liquid spiked with two important additives, ethylaluminum dichloride and 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide. This leads to the first chloroaluminate based ionic liquid electrolyte for rechargeable sodium metal battery. The obtained batteries reached voltages up to ~4V, high Coulombic efficiency up to 99.9%, and high energy and power density of ~420Whkg-1 and ~1766 W kg-1, respectively. The batteries retained over 90% of the original capacity after 700 cycles, suggesting an effective approach to sodium metal batteries with high energy/high power density, long cycle life and high safety.

    View details for DOI 10.1038/s41467-019-11102-2

    View details for PubMedID 31341162

  • An electrodeposition approach to metal/metal oxide heterostructures for active hydrogen evolution catalysts in near-neutral electrolytes NANO RESEARCH Kenney, M. J., Huang, J., Zhu, Y., Meng, Y., Xu, M., Zhu, G., Hung, W., Kuang, Y., Lin, M., Sun, X., Zhou, W., Dai, H. 2019; 12 (6): 1431–35
  • Rechargeable aluminum batteries: effects of cations in ionic liquid electrolytes. RSC advances Zhu, G., Angell, M., Pan, C. J., Lin, M. C., Chen, H., Huang, C. J., Lin, J., Achazi, A. J., Kaghazchi, P., Hwang, B. J., Dai, H. 2019; 9 (20): 11322-11330


    Room temperature ionic liquids (RTILs) are solvent-free liquids comprised of densely packed cations and anions. The low vapor pressure and low flammability make ILs interesting for electrolytes in batteries. In this work, a new class of ionic liquids were formed for rechargeable aluminum/graphite battery electrolytes by mixing 1-methyl-1-propylpyrrolidinium chloride (Py13Cl) with various ratios of aluminum chloride (AlCl3) (AlCl3/Py13Cl molar ratio = 1.4 to 1.7). Fundamental properties of the ionic liquids, including density, viscosity, conductivity, anion concentrations and electrolyte ion percent were investigated and compared with the previously investigated 1-ethyl-3-methylimidazolium chloride (EMIC-AlCl3) ionic liquids. The results showed that the Py13Cl-AlCl3 ionic liquid exhibited lower density, higher viscosity and lower conductivity than its EMIC-AlCl3 counterpart. We devised a Raman scattering spectroscopy method probing ILs over a Si substrate, and by using the Si Raman scattering peak for normalization, we quantified speciation including AlCl4 -, Al2Cl7 -, and larger AlCl3 related species with the general formula (AlCl3) n in different IL electrolytes. We found that larger (AlCl3) n species existed only in the Py13Cl-AlCl3 system. We propose that the larger cationic size of Py13+ (142 Å3) versus EMI+ (118 Å3) dictated the differences in the chemical and physical properties of the two ionic liquids. Both ionic liquids were used as electrolytes for aluminum-graphite batteries, with the performances of batteries compared. The chloroaluminate anion-graphite charging capacity and cycling stability of the two batteries were similar. The Py13Cl-AlCl3 based battery showed a slightly larger overpotential than EMIC-AlCl3, leading to lower energy efficiency resulting from higher viscosity and lower conductivity. The results here provide fundamental insights into ionic liquid electrolyte design for optimal battery performance.

    View details for DOI 10.1039/c9ra00765b

    View details for PubMedID 35520252

    View details for PubMedCentralID PMC9062991

  • Rechargeable aluminum batteries: effects of cations in ionic liquid electrolytes RSC ADVANCES Zhu, G., Angell, M., Pan, C., Lin, M., Chen, H., Huang, C., Lin, J., Achazi, A. J., Kaghazchi, P., Hwang, B., Dai, H. 2019; 9 (20): 11322–30

    View details for DOI 10.1039/c9ra00765b

    View details for Web of Science ID 000466756100035

  • An operando X-ray diffraction study of chloroaluminate anion-graphite intercalation in aluminum batteries PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Pan, C., Yuan, C., Zhu, G., Zhang, Q., Huang, C., Lin, M., Angell, M., Hwang, B., Kaghazchi, P., Dai, H. 2018; 115 (22): 5670–75


    We investigated rechargeable aluminum (Al) batteries composed of an Al negative electrode, a graphite positive electrode, and an ionic liquid (IL) electrolyte at temperatures down to -40 °C. The reversible battery discharge capacity at low temperatures could be superior to that at room temperature. In situ/operando electrochemical and synchrotron X-ray diffraction experiments combined with theoretical modeling revealed stable AlCl4-/graphite intercalation up to stage 3 at low temperatures, whereas intercalation was reversible up to stage 4 at room temperature (RT). The higher-degree anion/graphite intercalation at low temperatures affords rechargeable Al battery with higher discharge voltage (up to 2.5 V, a record for Al battery) and energy density. A remarkable cycle life of >20,000 cycles at a rate of 6C (10 minutes charge time) was achievable for Al battery operating at low temperatures, corresponding to a >50-year battery life if charged/discharged once daily.

    View details for PubMedID 29760096