Simultaneously Enhance Humidity Tolerance and Ionic Conductivity of Halide Electrolytes by Cation–Anion Co-Doping

Halide solid-state electrolytes (SSEs) with high ionic conductivity and oxidation stability show significant potentials for the commercialization of all-solid-state batteries (ASSBs). However, their practical applications are limited by poor humidity tolerance and decreased ionic conductivity. Herein, the Li 3/3- x In 1- x M x Cl 5.6 F 0.4 ( M = Hf, Zr, Fe, and Y; x = 0.015, 0.02, 0.025, 0.075, 0.1, 0.125, and 0.15) are synthesized by co-doping Li 3 InCl 6 with M and F ions for high-performance ASSBs. Li 2.98 In 0.98 Hf 0.02 Cl 5.6 F 0.4 achieves the highest ionic conductivity of 1.04 mS cm −1 at room temperature and good humidity tolerance of 87.96% conductivity retention after 24 h exposure. The analysis of experiments combining BVSE and AIMD simulations indicates that it benefits from the enhanced rigid structure that is thermodynamically stable to water caused by Cl − doping with F − and higher Li + vacancies concentration that facilitates Li + conduction generated by In 3+ doping with Hf 4+ . Moreover, an all-solid-state battery ensembled with Li 2.98 In 0.98 Hf 0.02 Cl 5.6 F 0.4 , LiCoO 2 and Li–In alloy, exhibits a high discharge capacity of 83.6 mAh g −1 and 78.6% capacity retention after 100 cycles under 0.5 C at 25 °C. This work provides a reliable strategy for designing advanced halide SSEs for commercial applications in ASSBs by cation–anion co-doping.