Flame-Retardant Gel Electrolytes Reinforced by PVDF-HFP/Ceramic Nanofiber Mat for Lithium Metal Batteries

Gel polymer electrolytes (GPEs) have become a viable substitute for liquid electrolytes (LEs) in lithium metal batteries (LMBs) for their excellent ionic conductivity and enhanced interfacial compatibility. However, as semisolid electrolytes, GPEs face significant challenges, including low mechanical strength and flammability. Herein, we fabricate a porous poly(vinylidene fluoride-<i>co</i>-hexafluoropropylene) (PVDF-HFP) mat (PHL) enriched with oxide ceramics as a support matrix, and fluorine-rich compounds are incorporated by in situ polymerization to construct a flame-retardant cross-linked GPE network with improved interfacial compatibility. The PHL-based GPE (PHL-GPE) exhibits ultralong cycling stability of over 2000 h with lithium metal. When applying Li|PHL-GPE|LiFePO₄ (LFP) cells, the PHL-GPE enables stable cycling for over 500 cycles with a capacity retention of 92.3% under high current density (1C) and high active material mass loading (11.25 mg cm^-2). This study provides an approach to address key challenges in the commercialization of LMBs.