A Fluorine-Enriched Gel Electrolyte with Universal Compatibility for Advanced Lithium Metal Batteries

Abstract

Lithium (Li) metal batteries (LMBs) are among the most promising candidates for next-generation energy storage due to the ultrahigh theoretical capacity of Li metal anodes. However, their practical deployment is severely hindered by uncontrolled dendrite growth and safety risks associated with conventional liquid electrolytes. Here, we report a composite fluorine-rich gel polymer electrolyte (CF-GPE) comprising a physically cross-linked network of polyethylene oxide (PEO), polyvinylidene fluoride (PVDF), polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) and polytetrafluoroethylene (PTFE). The resulting CF-GPE features a high ionic conductivity (3.8 mS cm -1 ) and a Li + transference number of 0.64, along with excellent mechanical integrity, liquid retention, and intrinsic flame-retardant behavior that resists ignition under direct flame exposure.Moreover, the CF-GPE exhibits enhanced compatibilities in both high-voltage LiCoO 2 LMBs and Li-O 2 batteries. In LiCoO 2 LMBs, it delivers 85.3% capacity retention after 900 cycles at 1C. Even in the Li-O 2 system, it effectively suppresses redox mediator (LiBr and 2,2,6,6-tetramethylpiperidin-1-oxyl, TEMPO) shuttling, enabling long-term cycling with 160 stable cycles at low overpotential. These results underscore the potential of the CF-GPE as a universally compatible electrolyte for highperformance and safe LMBs.