Synergistic Effect of Crosslinked Organic–Inorganic Composite Protective Layer for High Performance Lithium Metal Batteries

Abstract Maintaining a stable interface of lithium metal anodes (LMAs) by implementing a protective layer is a promising approach in extending the cycle life of lithium metal batteries (LMBs). Nevertheless, designing a protective layer with desired physicochemical properties is still a challenging task. Herein, an inorganic–organic composite protective layer consisting of fluorinated graphene oxide (FGO) (inorganic part) and polyacrylic acid (PAA) (organic part) that are in situ crosslinked via poly(ethylene glycol) diglycidyl ether (PEGDE) into a robust network is reported. The mechanical strength of FGO and the elasticity of the polymeric network jointly suppress the unwanted dendritic Li growth while fluorine‐functional groups in FGO induce an LiF‐enriched interface. This balanced inorganic–organic composite protective layer facilitates charge transfer kinetics for enhanced lithium‐ion diffusion at the interface. Utilizing this protective layer, LMB full‐cells with LiFePO 4 demonstrate negligible capacity loss for 100 cycles even under an extreme negative/positive capacity (N/P) ratio of 1.0. This study uncovers the possibility of highly robust, reliable LMBs by a sophisticatedly designed protective layer of widely used inorganic and organic components.