当前和下一代锂离子电池电解液的原子尺度微观认识和研究进展

电解液及构筑电极电解液界面对于开发和应用高比容量储能系统至关重要。具体来说,电解液的机械（抗压性、粘度）、热（热导率和热容）、化学（溶解性、活度、反应性）、输运和电化学（界面及界面层）等性质,与其所组成的储能器件的性能直接相关。目前,大量的实验研究通过调控电解液的物理和/或化学组成来改善电解液性能,以满足新型电极材料的工作运行。与此同时,理论模拟方法近年来得到了迅速发展,使人们可以从原子尺度来理解电解液在控制离子输运和构筑功能化界面的作用。站在理论模拟研究的前沿上,人们可以利用其所揭示的机理性认识对新型电解液开展理性设计。本文首先总结了传统电解液的组成、溶剂化结构和输运性质以及电极电解液界面层的形成机理,进一步讨论了利用新型电解液设计稳定电极电解液界面层的方法,包括使用电解液添加剂、高浓电解液和固态电解质,并着重讨论了对这些新型电解液体系进行原子尺度模拟的最新进展,为了解和认识电解液提供更为基本的理解,并为未来电解液的设计提供系统的指导。最后,作者对新型电解液的理论筛选进行了展望。

Advances and Atomistic Insights of Electrolytes for Lithium-Ion Batteries and Beyond

Electrolytes and the associated electrode-electrolyte interfaces are crucial for the development and application of high-capacity energy storage systems. Specifically, a variety of electrolyte properties, ranging from mechanical (compressibility, viscosity), thermal (heat conductivity and capacity), to chemical (solubility, activity, reactivity), transport, and electrochemical (interfacial and interphasial), are correlated to the performance of the resultant full energy storage device. In order to facilitate the operation of novel electrode materials, extensive experimental efforts have been devoted to improving these electrolyte properties by tuning the physical design and/or chemical composition. Meanwhile, the recent development of theoretical modeling methods is providing atomistic understandings of the electrolyte’s role in regulating the ion transport and enabling a functional interface. In this regard, we stand at a new frontier to take advantage of the revealed mechanistic insights into rationally design novel electrolyte systems. In this review, we first summarize the composition, solvation structure, and transport properties of conventional electrolytes as well as the formation mechanism of the electrode-electrolyte interphase. Moreover, some of the promising energy storage systems are briefly introduced. Further, approaches to stabilize the electrode-electrolyte interphase using novel electrolyte design, including electrolyte additives, high-concentration electrolytes, and solid-state electrolytes, are discussed. Some recent advances in the atomistic modeling of these aspects are particularly focused to provide a fundamental understanding of electrolytes and a comprehensive guide for future electrolyte design. Finally, we highlight the prospects of theoretical screening of novel electrolytes.