A moisture stable high-entropy halide electrolyte with performance recovery capability for all-solid-state batteries

Abstract

The practical application of halide solid electrolytes (HSEs) is hindered by poor moisture stability. The optimization of electrolyte moisture stability relies on a high content of the single element indium, which increase the cost of HSEs. In this work, a new strategy for enhancing moisture stability has been developed, we report a novel high-entropy halide electrolyte, Li2.65Zr0.25Ta0.25In0.16Zn0.16Fe0.16Cl6 (HE-25), which exhibits enhanced moisture tolerance and performance recovery capability. The introduction of theoretically moisture stable and low-cost constituent elements (Zn, Fe) optimizes the moisture stability of HE-25 and distinctly reduces its cost. After moisture exposure, HE-25 exhibits a distinct ionic conductivity recovery upon mild annealing at 150 °C, the electrolyte recovered nearly all of its original performance. Structural analyses reveal that performance degradation stems from reversible water adsorption rather than irreversible damage. All-solid-state batteries (ASSBs) using reheated HE-25 with an NCM89 cathode deliver a first-cycle discharge capacity of 211.4 mAh·g⁻¹ and 91.1% coulombic efficiency and good cycling stability (73.2% capacity retention after 500 cycles). This work demonstrates an effective high-entropy strategy to develop reduced cost, moisture resistant HSEs with performance recovery capability, paving the way for practical ASSBs.