Son Chang Yun, Wang Zhen-Gang
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
J Chem Phys. 2020 Sep 14;153(10):100903. doi: 10.1063/5.0016163.
Solid-state polymer electrolytes and high-concentration liquid electrolytes, such as water-in-salt electrolytes and ionic liquids, are emerging materials to replace the flammable organic electrolytes widely used in industrial lithium-ion batteries. Extensive efforts have been made to understand the ion transport mechanisms and optimize the ion transport properties. This perspective reviews the current understanding of the ion transport and polymer dynamics in liquid and polymer electrolytes, comparing the similarities and differences in the two types of electrolytes. Combining recent experimental and theoretical findings, we attempt to connect and explain ion transport mechanisms in different types of small-molecule and polymer electrolytes from a theoretical perspective, linking the macroscopic transport coefficients to the microscopic, molecular properties such as the solvation environment of the ions, salt concentration, solvent/polymer molecular weight, ion pairing, and correlated ion motion. We emphasize universal features in the ion transport and polymer dynamics by highlighting the relevant time and length scales. Several outstanding questions and anticipated developments for electrolyte design are discussed, including the negative transference number, control of ion transport through precision synthesis, and development of predictive multiscale modeling approaches.
固态聚合物电解质以及高浓度液体电解质，如水盐电解质和离子液体，是正在兴起的材料，用以替代工业锂离子电池中广泛使用的易燃有机电解质。人们已经做出了大量努力来理解离子传输机制并优化离子传输性能。本文综述了目前对液体和聚合物电解质中离子传输及聚合物动力学的理解，比较了这两种电解质的异同。结合近期的实验和理论发现，我们试图从理论角度关联并解释不同类型小分子和聚合物电解质中的离子传输机制，将宏观传输系数与微观分子性质联系起来，如离子的溶剂化环境、盐浓度、溶剂/聚合物分子量、离子配对以及相关离子运动。我们通过突出相关的时间和长度尺度来强调离子传输和聚合物动力学中的普遍特征。讨论了电解质设计的几个突出问题和预期发展，包括负迁移数、通过精确合成控制离子传输以及开发预测性多尺度建模方法。
