Research Progress on the Enhancement and Modification of PVDF-Based Polymer Electrolytes and Their Applications in Solid-State Lithium Metal Batteries

Traditional liquid electrolyte-based lithium-ion batteries (LIBs) are constrained by safety risks such as flammability and explosion, as well as a relatively low theoretical specific capacity (similar to 300 mAh g(-1)). Lithium-metal batteries (LMB), which offer higher energy density and enhanced safety, have emerged as competitive candidates for next-generation lithium-based batteries. As a key component of LMBs, polymer electrolytes are expected to exhibit excellent ionic conductivity, robust mechanical properties, and stable interfacial compatibility with electrode materials. Among the diverse range of polymer electrolytes, polyvinylidene fluoride (PVDF)-based polymer electrolytes stand out due to their unique properties. PVDF, with its high dielectric constant, effectively facilitates lithium salt dissociation and ion migration, while maintaining excellent mechanical flexibility. These characteristics position PVDF-based polymer electrolytes as a promising material for LMBs. This review begins by introducing the classification of polymer electrolytes and the mechanisms of lithium-ion migration within them. It then focuses on PVDF-based polymer electrolytes, systematically discussing the synthetic and modification strategies categorized into four main approaches: composite fabrication, inorganic filler doping, liquid additive modification, and multi-strategy modification. Finally, the challenges and future prospects of PVDF-based polymer electrolytes are reviewed to provide insights for developing high-performance polymer electrolytes in the future.