Kim Sang Cheol, Kong Xian, Vilá Rafael A, Huang William, Chen Yuelang, Boyle David T, Yu Zhiao, Wang Hansen, Bao Zhenan, Qin Jian, Cui Yi
Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States.
Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States.
J Am Chem Soc. 2021 Jul 14;143(27):10301-10308. doi: 10.1021/jacs.1c03868. Epub 2021 Jun 29.
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 () 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.
电解质在锂离子电池中起着关键作用，因为它几乎影响电池性能的各个方面。然而，我们对电解质的理解，尤其是锂的溶剂化作用，与其重要性相比仍显滞后。在这项工作中，我们引入了一种电位测量技术来探测电池电解质中锂的相对溶剂化能。通过测量具有对称电极和不对称电解质的电池中的开路电位，我们定量表征了浓度、阴离子和溶剂对不同电解质溶剂化能的影响。利用该技术，我们建立了电池电位（）与锂金属阳极高性能电解质循环稳定性之间的相关性，发现具有更负电池电位和正溶剂化能的溶剂——即与锂结合较弱的溶剂——可提高循环稳定性。低温电子显微镜显示，较弱的溶剂化作用会导致由阴离子衍生的固体电解质界面，从而稳定循环。通过使用电位测量来表征电解质，我们建立了一种相关性，可指导锂金属阳极有效电解质的工程设计。
