Fluorination Engineering for Stable Interfacial Chemistry in Deep Eutectic Amide-Based Electrolytes Enables High-Performance LiNi0.8Co0.1Mn0.1O2/Li Batteries

Fluorinated amide electrolytes represent a promising solution for high-energy density lithium metal batteries, yet their application in Ni-rich layered oxide cathodes is hindered by interfacial instability. This study develops a non-flammable fluorinated amide-based deep eutectic electrolyte modified with fluoroethylene carbonate, which simultaneously enhances ionic conductivity (1.5 × 10 −4 S cm −1 ) and anodic stability (>4.4 V vs Li + /Li). Applied in Li/NCM811 batteries, the fluoroethylene carbonate-based electrolyte enables 83.2% capacity retention after 200 cycles at 0.5 C, significantly outperforming conventional counterparts. ToF-SMIS and XPS tests reveal that fluoroethylene carbonate facilitates the formation of a LiF-rich cathode-electrolyte interphase, suppressing parasitic reactions and improving Li + transport kinetics. Furthermore, the electrolyte demonstrates superior lithium metal compatibility, inhibiting dendrite growth while enhancing thermal safety. These findings underscore the critical role of fluorinated amide electrolytes in stabilizing Ni-rich cathodes and highlight their potential for next-generation high-voltage lithium metal batteries.