Sang Cheol Kim

All Publications

• Asymmetric ether solvents for high-rate lithium metal batteries NATURE ENERGY Choi, I., Chen, Y., Shah, A., Florian, J., Serrao, C., Holoubek, J., Lyu, H., Zhang, E., Lee, J., Lin, Y., Kim, S., Park, H., Zhang, P., Lee, J., Qin, J., Cui, Y., Bao, Z. 2025

  View details for DOI 10.1038/s41560-025-01716-w

  View details for Web of Science ID 001421539700001

• Monofluorinated acetal electrolyte for high-performance lithium metal batteries. Proceedings of the National Academy of Sciences of the United States of America Zhang, E., Chen, Y., Holoubek, J., Yu, Z., Zhang, W., Lyu, H., Choi, I. R., Kim, S. C., Serrao, C., Cui, Y., Bao, Z. 2025; 122 (2): e2418623122

  Abstract

  High degree of fluorination for ether electrolytes has resulted in improved cycling stability of lithium metal batteries due to stable solid electrolyte interphase (SEI) formation and good oxidative stability. However, the sluggish ion transport and environmental concerns of high fluorination degree drive the need to develop less fluorinated structures. Here, we depart from the traditional ether backbone and introduce bis(2-fluoroethoxy)methane (F2DEM), featuring monofluorination of the acetal backbone. High coulombic efficiency and stable long-term cycling in Li||Cu half cells can be achieved with F2DEM even under fast Li metal plating conditions. The performance of F2DEM is further compared with diethoxymethane (DEM) and 2-[2-(2,2-difluoroethoxy)ethoxy]-1,1,1-trifluoroethane (F5DEE). A significantly lower overpotential is observed with F2DEM, which improves energy efficiency and enables its application in high-rate conditions. Comparative studies of F2DEM with DEM and F5DEE in anode-free lithium iron phosphate (LiFePO4) LFP pouch cells and high-loading LFP coin cells further show improved capacity retention of F2DEM electrolyte, demonstrating its practical applicability. More importantly, we also extensively investigate the underlying mechanism for the superior performance of F2DEM through various techniques, including X-ray photoelectron spectroscopy, scanning electron microscopy, cryogenic electron microscopy, focused ion beam, electrochemical impedance spectroscopy, and titration gas chromatography. Overall, F2DEM facilitates improved Li deposition morphology with reduced amount of dead Li. This enables F2DEM to show superior performance, especially under higher charging and slower discharging rate conditions.

  View details for DOI 10.1073/pnas.2418623122

  View details for PubMedID 39772742

• Hyperconjugation-controlled molecular conformation weakens lithium-ion solvation and stabilizes lithium metal anodes. Chemical science Chen, Y., Liao, S. L., Gong, H., Zhang, Z., Huang, Z., Kim, S. C., Zhang, E., Lyu, H., Yu, W., Lin, Y., Sayavong, P., Cui, Y., Qin, J., Bao, Z. 2024

  Abstract

  Tuning the solvation structure of lithium ions via electrolyte engineering has proven effective for lithium metal (Li) anodes. Further advancement that bypasses the trial-and-error practice relies on the establishment of molecular design principles. Expanding the scope of our previous work on solvent fluorination, we report here an alternative design principle for non-fluorinated solvents, which potentially have reduced cost, environmental impact, and toxicity. By studying non-fluorinated ethers systematically, we found that the short-chain acetals favor the [gauche, gauche] molecular conformation due to hyperconjugation, which leads to weakened monodentate coordination with Li+. The dimethoxymethane electrolyte showed fast activation to >99% coulombic efficiency (CE) and high ionic conductivity of 8.03 mS cm-1. The electrolyte performance was demonstrated in anode-free Cu‖LFP pouch cells at current densities up to 4 mA cm-2 (70 to 100 cycles) and thin-Li‖high-loading-LFP coin cells (200-300 cycles). Overall, we demonstrated and rationalized the improvement in Li metal cyclability by the acetal structure compared to ethylene glycol ethers. We expect further improvement in performance by tuning the acetal structure.

  View details for DOI 10.1039/d4sc05319b

  View details for PubMedID 39568883

  View details for PubMedCentralID PMC11575589

• Seawater alkalization via an energy-efficient electrochemical process for CO2 capture. Proceedings of the National Academy of Sciences of the United States of America Guan, X., Zhang, G., Li, J., Kim, S. C., Feng, G., Li, Y., Cui, T., Brest, A., Cui, Y. 2024; 121 (45): e2410841121

  Abstract

  Electrochemical pH-swing strategies offer a promising avenue for cost-effective and energy-efficient carbon dioxide (CO2) capture, surpassing the traditional thermally activated processes and humidity-sensitive techniques. The concept of elevating seawater's alkalinity for scalable CO2 capture without introducing additional chemical as reactant is particularly intriguing due to its minimal environmental impact. However, current commercial plants like chlor-alkali process or water electrolysis demand high thermodynamic voltages of 2.2 V and 1.23 V, respectively, for the production of sodium hydroxide (NaOH) from seawater. These high voltages are attributed to the asymmetric electrochemical reactions, where two completely different reactions take place at the anode and cathode. Here, we developed a symmetric electrochemical system for seawater alkalization based on a highly reversible and identical reaction taking place at the anode and cathode. We utilize hydrogen evolution reaction at the cathode, where the generated hydrogen is looped to the anode for hydrogen oxidation reaction. Theoretical calculations indicate an impressively low energy requirement ranging from 0.07 to 0.53 kWh/kg NaOH for established pH differences of 1.7 to 13.4. Experimentally, we achieved the alkalization with an energy consumption of 0.63 kWh/kg NaOH, which is only 38% of the theoretical energy requirements of the chlor-alkali process (1.64 kWh/kg NaOH). Further tests demonstrated the system's potential of enduring high current densities (~20 mA/cm2) and operating stability over an extended period (>110 h), showing its potential for future applications. Notably, the CO2 adsorption tests performed with alkalized seawater exhibited remarkably improved CO2 capture dictated by the production of hydroxide compared to the pristine seawater.

  View details for DOI 10.1073/pnas.2410841121

  View details for PubMedID 39467125

• Spontaneous lithium extraction and enrichment from brine with net energy output driven by counter-ion gradients NATURE WATER Zhang, G., Li, Y., Guan, X., Hu, G., Su, H., Xu, X., Feng, G., Shuchi, S., Kim, S., Zhou, J., Xu, R., Xiao, X., Wu, A., Cui, Y. 2024; 2 (11): 1091-1101

  View details for DOI 10.1038/s44221-024-00326-2

  View details for Web of Science ID 001390107600011

• Failure Process During Fast Charging of Lithium Metal Batteries with Weakly Solvating Fluoroether Electrolytes JOURNAL OF PHYSICAL CHEMISTRY C Chen, Y., Yu, Z., Gong, H., Zhang, W., Rudnicki, P. E., Huang, Z., Yu, W., Kim, S., Boyle, D. T., Sayavong, P., Celik, H., Xu, R., Lin, Y., Wang, S., Qin, J., Cui, Y., Bao, Z. 2024

  View details for DOI 10.1021/acs.jpcc.4c01740

  View details for Web of Science ID 001265561200001

• A New Lithium Thioborate-Lithium Iodide Solid-State Electrolyte with High Ionic Conductivity for Lithium Metal Batteries ACS ENERGY LETTERS Holmes, S. E., Zhang, W., Kim, S., Cui, Y. 2024

  View details for DOI 10.1021/acsenergylett.4c00057

  View details for Web of Science ID 001195912900001

• Solvation-property relationship of lithium-sulphur battery electrolytes. Nature communications Kim, S. C., Gao, X., Liao, S., Su, H., Chen, Y., Zhang, W., Greenburg, L. C., Pan, J., Zheng, X., Ye, Y., Kim, M. S., Sayavong, P., Brest, A., Qin, J., Bao, Z., Cui, Y. 2024; 15 (1): 1268

  Abstract

  The Li-S battery is a promising next-generation battery chemistry that offers high energy density and low cost. The Li-S battery has a unique chemistry with intermediate sulphur species readily solvated in electrolytes, and understanding their implications is important from both practical and fundamental perspectives. In this study, we utilise the solvation free energy of electrolytes as a metric to formulate solvation-property relationships in various electrolytes and investigate their impact on the solvated lithium polysulphides. We find that solvation free energy influences Li-S battery voltage profile, lithium polysulphide solubility, Li-S battery cyclability and the Li metal anode; weaker solvation leads to lower 1st plateau voltage, higher 2nd plateau voltage, lower lithium polysulphide solubility, and superior cyclability of Li-S full cells and Li metal anodes. We believe that relationships delineated in this study can guide the design of high-performance electrolytes for Li-S batteries.

  View details for DOI 10.1038/s41467-023-44527-x

  View details for PubMedID 38341443

• Recovery of isolated lithium through discharged state calendar ageing. Nature Zhang, W., Sayavong, P., Xiao, X., Oyakhire, S. T., Shuchi, S. B., Vilá, R. A., Boyle, D. T., Kim, S. C., Kim, M. S., Holmes, S. E., Ye, Y., Li, D., Bent, S. F., Cui, Y. 2024; 626 (7998): 306-312

  Abstract

  Rechargeable Li-metal batteries have the potential to more than double the specific energy of the state-of-the-art rechargeable Li-ion batteries, making Li-metal batteries a prime candidate for next-generation high-energy battery technology1-3. However, current Li-metal batteries suffer from fast cycle degradation compared with their Li-ion battery counterparts2,3, preventing their practical adoption. A main contributor to capacity degradation is the disconnection of Li from the electrochemical circuit, forming isolated Li4-8. Calendar ageing studies have shown that resting in the charged state promotes further reaction of active Li with the surrounding electrolyte9-12. Here we discover that calendar ageing in the discharged state improves capacity retention through isolated Li recovery, which is in contrast with the well-known phenomenon of capacity degradation observed during the charged state calendar ageing. Inactive capacity recovery is verified through observation of Coulombic efficiency greater than 100% on both Li||Cu half-cells and anode-free cells using a hybrid continuous-resting cycling protocol and with titration gas chromatography. An operando optical setup further confirms excess isolated Li reactivation as the predominant contributor to the increased capacity recovery. These insights into a previously unknown pathway for capacity recovery through discharged state resting emphasize the marked impact of cycling strategies on Li-metal battery performance.

  View details for DOI 10.1038/s41586-023-06992-8

  View details for PubMedID 38326593

  View details for PubMedCentralID 8580315

• Proximity Matters: Interfacial Solvation Dictates Solid Electrolyte Interphase Composition. Nano letters Oyakhire, S. T., Liao, S., Shuchi, S. B., Kim, M. S., Kim, S. C., Yu, Z., Vila, R. A., Rudnicki, P. E., Cui, Y., Bent, S. F. 2023

  Abstract

  The composition of the solid electrolyte interphase (SEI) plays an important role in controlling Li-electrolyte reactions, but the underlying cause of SEI composition differences between electrolytes remains unclear. Many studies correlate SEI composition with the bulk solvation of Li ions in the electrolyte, but this correlation does not fully capture the interfacial phenomenon of SEI formation. Here, we provide a direct connection between SEI composition and Li-ion solvation by forming SEIs using polar substrates that modify interfacial solvation structures. We circumvent the deposition of Li metal by forming the SEI above Li+/Li redox potential. Using theory, we show that an increase in the probability density of anions near a polar substrate increases anion incorporation within the SEI, providing a direct correlation between interfacial solvation and SEI composition. Finally, we use this concept to form stable anion-rich SEIs, resulting in high performance lithium metal batteries.

  View details for DOI 10.1021/acs.nanolett.3c02037

  View details for PubMedID 37565722

• High-entropy electrolytes for practical lithium metal batteries NATURE ENERGY Kim, S., Wang, J., Xu, R., Zhang, P., Chen, Y., Huang, Z., Yang, Y., Yu, Z., Oyakhire, S. T., Zhang, W., Greenburg, L. C., Kim, M., Boyle, D. T., Sayavong, P., Ye, Y., Qin, J., Bao, Z., Cui, Y. 2023

  View details for DOI 10.1038/s41560-023-01280-1

  View details for Web of Science ID 001023405800005

• Data-driven electrolyte design for lithium metal anodes. Proceedings of the National Academy of Sciences of the United States of America Kim, S. C., Oyakhire, S. T., Athanitis, C., Wang, J., Zhang, Z., Zhang, W., Boyle, D. T., Kim, M. S., Yu, Z., Gao, X., Sogade, T., Wu, E., Qin, J., Bao, Z., Bent, S. F., Cui, Y. 2023; 120 (10): e2214357120

  Abstract

  Improving Coulombic efficiency (CE) is key to the adoption of high energy density lithium metal batteries. Liquid electrolyte engineering has emerged as a promising strategy for improving the CE of lithium metal batteries, but its complexity renders the performance prediction and design of electrolytes challenging. Here, we develop machine learning (ML) models that assist and accelerate the design of high-performance electrolytes. Using the elemental composition of electrolytes as the features of our models, we apply linear regression, random forest, and bagging models to identify the critical features for predicting CE. Our models reveal that a reduction in the solvent oxygen content is critical for superior CE. We use the ML models to design electrolyte formulations with fluorine-free solvents that achieve a high CE of 99.70%. This work highlights the promise of data-driven approaches that can accelerate the design of high-performance electrolytes for lithium metal batteries.

  View details for DOI 10.1073/pnas.2214357120

  View details for PubMedID 36848560

• Graphene coating on silicon anodes enabled by thermal surface modification for high-energy lithium-ion batteries MRS BULLETIN Kim, S., Huang, W., Zhang, Z., Wang, J., Kim, Y., Jeong, Y., Oyakhire, S. T., Yang, Y., Cui, Y. 2022

  View details for DOI 10.1557/s43577-021-00191-4

  View details for Web of Science ID 000771066700003

• Suspension electrolyte with modified Li+ solvation environment for lithium metal batteries. Nature materials Kim, M. S., Zhang, Z., Rudnicki, P. E., Yu, Z., Wang, J., Wang, H., Oyakhire, S. T., Chen, Y., Kim, S. C., Zhang, W., Boyle, D. T., Kong, X., Xu, R., Huang, Z., Huang, W., Bent, S. F., Wang, L., Qin, J., Bao, Z., Cui, Y. 1800

  Abstract

  Designing a stable solid-electrolyte interphase on a Li anode is imperative to developing reliable Li metal batteries. Herein, we report a suspension electrolyte design that modifies the Li+ solvation environment in liquid electrolytes and creates inorganic-rich solid-electrolyte interphases on Li. Li2O nanoparticles suspended in liquid electrolytes were investigated as a proof of concept. Through theoretical and empirical analyses of Li2O suspension electrolytes, the roles played by Li2O in the liquid electrolyte and solid-electrolyte interphases of the Li anode are elucidated. Also, the suspension electrolyte design is applied in conventional and state-of-the-art high-performance electrolytes to demonstrate its applicability. Based on electrochemical analyses, improved Coulombic efficiency (up to ~99.7%), reduced Li nucleation overpotential, stabilized Li interphases and prolonged cycle life of anode-free cells (~70 cycles at 80% of initial capacity) were achieved with the suspension electrolytes. We expect this design principle and our findings to be expanded into developing electrolytes and solid-electrolyte interphases for Li metal batteries.

  View details for DOI 10.1038/s41563-021-01172-3

  View details for PubMedID 35039645

• Rational solvent molecule tuning for high-performance lithium metal battery electrolytes NATURE ENERGY Yu, Z., Rudnicki, P. E., Zhang, Z., Huang, Z., Celik, H., Oyakhire, S. T., Chen, Y., Kong, X., Kim, S., Xiao, X., Wang, H., Zheng, Y., Kamat, G. A., Kim, M., Bent, S. F., Qin, J., Cui, Y., Bao, Z. 2022

  View details for DOI 10.1038/s41560-021-00962-y

  View details for Web of Science ID 000742253900001

• Potentiometric Measurement to Probe Solvation Energy and Its Correlation to Lithium Battery Cyclability. Journal of the American Chemical Society Kim, S. C., Kong, X., Vila, R. A., Huang, W., Chen, Y., Boyle, D. T., Yu, Z., Wang, H., Bao, Z., Qin, J., Cui, Y. 2021

  Abstract

  The electrolyte plays a critical role in lithium-ion batteries, as it impacts almost every facet of a battery's performance. However, our understanding of the electrolyte, especially solvation of Li+, lags behind its significance. In this work, we introduce a potentiometric technique to probe the relative solvation energy of Li+ in battery electrolytes. By measuring open circuit potential in a cell with symmetric electrodes and asymmetric electrolytes, we quantitatively characterize the effects of concentration, anions, and solvents on solvation energy across varied electrolytes. Using the technique, we establish a correlation between cell potential (Ecell) and cyclability of high-performance electrolytes for lithium metal anodes, where we find that solvents with more negative cell potentials and positive solvation energies-those weakly binding to Li+-lead to improved cycling stability. Cryogenic electron microscopy reveals that weaker solvation leads to an anion-derived solid-electrolyte interphase that stabilizes cycling. Using the potentiometric measurement for characterizing electrolytes, we establish a correlation that can guide the engineering of effective electrolytes for the lithium metal anode.

  View details for DOI 10.1021/jacs.1c03868

  View details for PubMedID 34184873

• Correlating Li-Ion Solvation Structures and Electrode Potential Temperature Coefficients. Journal of the American Chemical Society Wang, H. n., Kim, S. C., Rojas, T. n., Zhu, Y. n., Li, Y. n., Ma, L. n., Xu, K. n., Ngo, A. T., Cui, Y. n. 2021

  Abstract

  Temperature coefficients (TCs) for either electrochemical cell voltages or potentials of individual electrodes have been widely utilized to study the thermal safety and cathode/anode phase changes of lithium (Li)-ion batteries. However, the fundamental significance of single electrode potential TCs is little known. In this work, we discover that the Li-ion desolvation process during Li deposition/intercalation is accompanied by considerable entropy change, which significantly contributes to the measured Li/Li+ electrode potential TCs. To explore this phenomenon, we compare the Li/Li+ electrode potential TCs in a series of electrolyte formulations, where the interaction between Li-ion and solvent molecules occurs at varying strength as a function of both solvent and anion species as well as salt concentrations. As a result, we establish correlations between electrode potential TCs and Li-ion solvation structures and further verify them by ab initio molecular dynamics simulations. We show that measurements of Li/Li+ electrode potential TCs provide valuable knowledge regarding the Li-ion solvation environments and could serve as a screening tool when designing future electrolytes for Li-ion/Li metal batteries.

  View details for DOI 10.1021/jacs.0c10587

  View details for PubMedID 33506677

• Underpotential lithium plating on graphite anodes caused by temperature heterogeneity. Proceedings of the National Academy of Sciences of the United States of America Wang, H., Zhu, Y., Kim, S. C., Pei, A., Li, Y., Boyle, D. T., Wang, H., Zhang, Z., Ye, Y., Huang, W., Liu, Y., Xu, J., Li, J., Liu, F., Cui, Y. 2020

  Abstract

  Rechargeability and operational safety of commercial lithium (Li)-ion batteries demand further improvement. Plating of metallic Li on graphite anodes is a critical reason for Li-ion battery capacity decay and short circuit. It is generally believed that Li plating is caused by the slow kinetics of graphite intercalation, but in this paper, we demonstrate that thermodynamics also serves a crucial role. We show that a nonuniform temperature distribution within the battery can make local plating of Li above 0 V vs. Li0/Li+ (room temperature) thermodynamically favorable. This phenomenon is caused by temperature-dependent shifts of the equilibrium potential of Li0/Li+ Supported by simulation results, we confirm the likelihood of this failure mechanism during commercial Li-ion battery operation, including both slow and fast charging conditions. This work furthers the understanding of nonuniform Li plating and will inspire future studies to prolong the cycling lifetime of Li-ion batteries.

  View details for DOI 10.1073/pnas.2009221117

  View details for PubMedID 33168752

• Ultralight and fire-extinguishing current collectors for high-energy and high-safety lithium-ion batteries NATURE ENERGY Ye, Y., Chou, L., Liu, Y., Wang, H., Lee, H., Huang, W., Wan, J., Liu, K., Zhou, G., Yang, Y., Yang, A., Xiao, X., Gao, X., Boyle, D., Chen, H., Zhang, W., Kim, S., Cui, Y. 2020; 5 (10): 786–93

  View details for DOI 10.1038/s41560-020-00702-8

  View details for Web of Science ID 000578091500012