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 LiFePO4 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.