Fluorination Engineering for Stable Interfacial Chemistry in Deep Eutectic Amide‐Based Electrolytes Enables High‐Performance L i N i 0.8 C o 0.1 M n 0.1 O 2 /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.