Enhanced Room-Temperature Performance of Polyvinylidene Fluoride-Hexafluoropropylene/C6M Solid Polymer Electrolytes for All-Solid-State Lithium Metal Batteries

Solid-state polymer electrolytes (SPEs) enabling stable operation at room temperature are crucial for advancing all-solid-state lithium metal batteries (ASSLMBs). Polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), with its high dielectric constant and strong lithium salt dissociation capability, is a promising candidate but suffers from low ionic conductivity and microstructural flaws. This study introduces a PVDF-HFP/C6M SPE (x-PLC) with a semi-interpenetrating polymer network structure; C6M is a liquid crystal polymer material, prepared via UV irradiation, which exhibits a smooth, defect-free microstructure, enhanced lithium salt dissociation and ion transport properties, and suppressed polymer degradation. The x-PLC SPE demonstrates an ionic conductivity of 2.78 × 10–4 S cm–1 and a lithium-ion transference number of 0.65 at 25 °C. It also forms a solid electrolyte interphase layer rich in LiF and Li2CO3, effectively inhibiting lithium dendrite growth and maintaining stable ionic conductivity. When integrated into a Li/x-PLC/LiFePO4 battery, it achieves a capacity retention rate of 99.4% after 1000 cycles at 1 C under ambient conditions, showcasing its potential for high-performance ASSLMB applications. This work provides a strategy for designing advanced SPEs, facilitating the development and practical deployment of solid-state lithium metal batteries.