An Anion‐Tuned Solid Electrolyte Interphase with Fast Ion Transfer Kinetics for Stable Lithium Anodes

作者：Zhenxing Wang, Fulai Qi, Lichang Yin, Ying Shi, Chengguo Sun, Baigang An, Hui–Ming Cheng, Feng Li · 发表于：Advanced Energy Materials · 年份：2020 · DOI：10.1002/aenm.201903843 · 被引用次数：345 · 研究领域：Advancements in Battery Materials、Advanced Battery Materials and Technologies、Advanced battery technologies research

Abstract The spatial distribution and transport characteristics of lithium ions (Li + ) in the electrochemical interface region of a lithium anode in a lithium ion battery directly determine Li + deposition behavior. The regulation of the Li + solvation sheath on the solid electrolyte interphase (SEI) by electrolyte chemistry is key but challenging. Here, 1 m lithium trifluoroacetate (LiTFA) is induced to the electrolyte to regulate the Li + solvation sheath, which significantly suppresses Li dendrite formation and enables a high Coulombic efficiency of 98.8% over 500 cycles. With its strong coordination between the carbonyl groups (CO) and Li + , TFA − modulates the environment of the Li + solvation sheath and facilitates fast desolvation kinetics. In addition, due to relatively smaller lowest unoccupied molecular orbital energy than solvents, TFA − has a preferential reduction to produce a stable SEI with uniform distribution of LiF and Li 2 O. Such stable SEI effectively reduces the energy barrier for Li + diffusion, contributing to low nucleation overpotential, fast ion transfer kinetics, and uniform Li + deposition with high cycling stability. This work provides an alternative insight into the design of interface chemistry in terms of regulating anions in the Li + solvation sheath. It is anticipated that this anion‐tuned strategy will pave the way to construct stable SEIs for other battery systems.