La<sub>2</sub>O<sub>3</sub> Filler's Stabilization of Residual Solvent in Polymer Electrolyte for Advanced Solid‐State Lithium‐Metal Batteries
Yaping Zeng, Le Zhao, Jiaming Zhang, Qiuping Li, Dan Sun, Yu Ren, Yougen Tang, Guanhua Jin, Haiyan Wang
Abstract
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) polymer SEs have gained increased attention for their high dielectric constants, high ionic conductivity, and excellent flexibility. However, severe side reactions at the interface caused by the decomposition of residual DMF solvent significantly reduce the cycle life of PVDF‐HFP‐based SSBs. Herein, La 2 O 3 nanoparticles are used as new inorganic fillers to form a PVDF‐HFP/LiFSI/La 2 O 3 ‐40% composite polymer electrolyte (PVDF‐HFP/La 2 O 3 CPE). Benefiting from the interaction between La 2 O 3 and N,N ‐dimethylformamide (DMF) solvent molecules, the cell cycling stability is greatly improved. In addition, the PVDF‐HFP/LiFSI solid electrolyte (PVDF‐HFP SE) containing 40 wt% La 2 O 3 has the highest ionic conductivity of 1.33 × 10 −3 S cm −1 at 25 °C. It also exhibits a higher lithium‐ion transference number of 0.52 and lower polarization. The PVDF‐HFP/La 2 O 3 CPE here ensures high ionic conductivity and stable interface chemistry in SSB, demonstrating a promising application potential.