Optimizing Electrode/Electrolyte Interphases and Li‐Ion Flux/Solvation for Lithium‐Metal Batteries with Qua‐Functional Heptafluorobutyric Anhydride

Abstract The safety and electrochemical performance of rechargeable lithium‐metal batteries (LMBs) are primarily influenced by the additives in the organic liquid electrolytes. However, multi‐functional additives are still rarely reported. Herein, we proposed heptafluorobutyric anhydride (HFA) as a qua‐functional additive to optimize the composition and structure of the solid electrolyte interphase (SEI) at the electrode/electrolyte interface. The reduction/oxidation decomposition of the fluorine‐rich HFA facilitate uniform inorganic‐rich SEI and compact cathode electrolyte interphase (CEI) formation, which enables stable lithium plating during charge and suppresses the dissolution of transition‐metal ions. Moreover, HFA optimizes the Li‐ion solvation for stable Li plating/stripping and serves as the surfactant to enhance the wettability of the separator by the electrolyte to increase Li‐ion flux. The symmetric Li∥Li cell with 1.0 wt % HFA electrolyte had an excellent cycling performance over 340 h at 1.0 mA cm −2 with a capacity of 0.5 mAh cm −2 while the Li∥NCM622 cell maintained high capacity retention after 250 cycles and outstanding rate performance even at 15 C.