Improved gel polymer electrolyte via imidazolium ionic liquid for stabilizing the interface of Li metal batteries

The interface problem between Li anode and gel polymer electrolytes (GPEs) hinder the performance improvement and application of Li metal batteries (LMBs). Herein, a GPE showcasing high ionic conductivity (3.91 mS cm −1 ) and elastic modulus (6.04 MPa) as GPE based on poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) was devised by introducing ionic liquids (ILs). The reconfiguration of Li ion solvation environment and the formation of LiF-rich solid electrolyte interface (SEI) protective layer have improved the interface problem. The LMB assembled from an optimized GPE- ET0.25 has stable Li deposition and excellent electrochemical properties , making the Li||LiFePO 4 (LFP) battery attaining an impressive long-cycle capacity retention rate of 96.0 %. This study emphasizes the advantages of IL aligned GPEs design, and the significance of forming stable SEI to improve battery performance, and provides ideas for the design of flexible LMBs with high safety and high performance.