Fundamentals of ion transport in polyethylene oxide- and polyvinylidene fluoride-based battery polymer solid electrolytes

Solid polymer electrolytes (SPEs) are promising candidates for next-generation solid-state lithium batteries, but their practical application is limited by insufficient room-temperature ionic conductivity and incomplete mechanistic understanding of ion transport. Previous reviews have largely discussed polyethylene oxide (PEO)- and polyvinylidene fluoride (PVDF)-based electrolytes separately or have focused primarily on material modification and electrochemical performance. Here, we provide a mechanism-centered comparison of these two representative polymer matrices, emphasizing how their distinct chemical structures determine salt dissociation, Li⁺ coordination, and long-range ion migration. In PEO-based electrolytes, Li + migration is governed by coordination with ether oxygen atoms and segmental motion within the amorphous phase, with conductivity strongly influenced by crystallinity, salt dissociation, anion structure, and ceramic fillers. In contrast, PVDF-based electrolytes rely on solvent-coordinated complexes, dipole-assisted interactions, and interfacial transport pathways in composite architectures, where residual solvents, crystalline-phase composition ( α / β / γ ), and filler-induced space-charge effects play critical roles. By clarifying the structure–transport relationships in these two representative polymer matrices, this work provides mechanistic insights to guide the rational design of high-performance polymer electrolytes for solid-state lithium batteries.