A localized high-concentration electrolyte with lithium bis(fluorosulfonyl) imide (LiFSI) salt and F-containing cosolvents to enhance the performance of Li||LiNi0.8Co0.1Mn0.1O2 lithium metal batteries

Abstract

A localized high-concentration electrolyte (LHCE) with lithium bis(fluorosulfonyl) imide (LiFSI) salt and F-containing multicomponent cosolvents is developed to match the aggressive requirements of high-performance lithium metal batteries (LMBs) with a LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) cathode. The synergistic effect of LiFSI, 1,2-dimethoxyethane, fluoroethylene carbonate and 1H, 1H, 5H-Octafluoropentyl-1,1,2,2-tetrafluoroethyl ether in the LHCE promotes the formation of a uniform and robust LiF layer on the lithium anode, which enables the uniform deposition of Li and enhances the cycling lifespan of LMBs. The capacity retention rate of the cell with LHCE increased from 14.4% to 91.4% after 140 cycles compared to the carbonate-based electrolyte. And at a current density of 1 mA cm⁻², the coulombic efficiency (CE) of the Li||Cu cell with LHCE remained at 98.9% after 200 cycles, and the Li||Li cell remained stable after cycling for 1150 h. The molecular dynamics (MD) simulation and spectroscopic characterization reveal the advantages of the 3D network structure possessed by LHCE and explain the formation mechanism of the F-containing electrode–electrolyte interface (EEI). This work provides a new idea to advance the commercialization of LIBs by resolving the low coulombic efficiency, fast capacity fade, and disordered growth of Li dendrites in Li anode.