Solvation Regulation via Hydrogen Bonding to Mitigate Al Current Collector Corrosion for High‐Voltage Li‐Ion Batteries

Abstract

AbstractThe exceptional thermal stability and conductivity of lithium bis(fluorosulfonyl)imide (LiFSI) have made it a preferred salt for lithium‐ion batteries (LIBs). However, the corrosion of aluminum (Al) current collectors by LiFSI at low potentials (3.8 V vs Li/Li+) poses a persistent challenge, hindering the application of LiFSI in 4 V‐class LIBs. Herein, 2,2,2‐trifluoroethyl methanesulfonate (TFMS) is proposed as a versatile co‐solvent to address the issue of Al current collector corrosion. It is demonstrated that incorporating TFMS into a conventional LiFSI‐based carbonate electrolyte can precisely tailor the Li+ solvation structure by hydrogen bonding interactions with dimethyl carbonate (DMC) solvent. This weakens the coordination between DMC and Li+ while increasing the participation of FSI− anions in the primary solvation shell, effectively suppressing the Al current collector caused by free FSI− anions attacking. Furthermore, TFMS and FSI− synergically induce the formation of an inorganic‐rich and compact cathode electrolyte interphase, significantly avoiding undesired side reactions. As a result, the TFMS‐electrolyte enables 1.2 Ah‐graphite||NCM811 (LiNi0.8Co0.1Mn0.1O2) pouch‐cells to achieve 89.9% capacity retention with high average Coulombic efficiency of >99.9% for 200 cycles at a cut‐off voltage of 4.4 V, opening up opportunities for the development of advanced high‐voltage LIBs.