La ₂ O ₃ Filler's Stabilization of Residual Solvent in Polymer Electrolyte for Advanced Solid‐State Lithium‐Metal Batteries

Polymer solid electrolytes (SEs) with high safety and flexibility are ideal for advanced lithium-metal solid-state batteries (SSBs). Among various polymer SEs, polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP) SEs have gained increased attention their dielectric constants, ionic conductivity, excellent flexibility. However, severe side reactions at the interface caused by decomposition of residual DMF solvent significantly reduce cycle life PVDF-HFP-based SSBs. Herein, La2O3 nanoparticles used as new inorganic fillers to form a PVDF-HFP/LiFSI/La2O3-40% composite electrolyte (PVDF-HFP/La2O3 CPE). Benefiting from interaction between N,N-dimethylformamide (DMF) molecules, cell cycling stability is greatly improved. In addition, PVDF-HFP/LiFSI (PVDF-HFP SE) containing 40 wt% has highest conductivity 1.33 × 10−3 S cm−1 25 °C. It also exhibits higher lithium-ion transference number 0.52 lower polarization. The PVDF-HFP/La2O3 CPE here ensures stable chemistry in SSB, demonstrating promising application potential.