Al<sub>2</sub>O<sub>3</sub> Fiber-Reinforced Polymer Solid Electrolyte Films with Excellent Lithium-Ion Transport Properties for High-Voltage Solid-State Lithium Batteries
Jie Li, Mao‐xiang Jing, Rui Li, Lin‐xin Li, Zhen-hao Huang, Hua Yang, Ming‐quan Liu, Shahid Hussain, Jun Xiang, Xiangqian Shen
Abstract
Composite solid electrolytes (CSEs) with high ionic conductivity and good interfacial compatibility are the basis for the practical application of solid-state lithium batteries. The combination of suitable polymers and inorganic fillers is the key to the preparation of CSEs with excellent performance. In this work, a flexible-rigid composite solid electrolyte film was prepared by incorporating different weight ratios (5–20 wt %) of γ-Al2O3 fibers into flexible polypropylene oxide (PPO) polymer electrolytes. Due to the addition of γ-Al2O3 fibers, the ion migration path is shortened and the ion migration rate is effectively improved. At the same time, the Lewis acid groups of γ-Al2O3 fibers react with TFSI– to release more Li+, which increases the number of lithium-ion migration. Therefore, when the content of γ-Al2O3 fibers is 15 wt %, the room-temperature ionic conductivity reaches 3.38 × 10–4 S cm–1, the ion migration number is 0.70, and the electrochemical window is 5.6 V. In addition, lithiophilic γ-Al2O3 reacts with Li metal to generate a Li–Al–O transition layer, which promotes Li+ interfacial transport and Li uniform deposition, and further inhibits the growth of Li dendrites. This Al2O3 fiber-reinforced CSE improves the lithium-ion transport properties and interface stability between lithium and the electrolyte and has positive practical applications in solid-state lithium batteries.