Boosting Ion Conduction and Moisture Stability Through Zn2+ Substitution of Chloride Electrolytes for All-Solid-State Lithium Batteries

Abstract

The recently emerged chloride solid electrolytes have garnered significant attention due to their superior ionic conductivity, wide electrochemical stability window, and exceptional compatibility with high-voltage oxide cathodes. Nevertheless, the currently cost-effective Zr-based chloride solid electrolytes face significant challenges, including low ionic conductivity and poor moisture stability. Herein, a versatile Zn²⁺-doped Zr-based chloride electrolyte is presented, designed to meet the aforementioned requirements. The optimized Li_2.4Zr_0.8Zn_0.2Cl₆ exhibits an improved ionic conductivity of 1.13 mS cm⁻¹ at 30 °C. Simultaneously, the Li_2.4Zr_0.8Zn_0.2Cl₆ also demonstrates impressive moisture stability, maintaining its structural integrity after exposure to humid air. The mechanism underlying the enhanced moisture stability of Li_2.4Zr_0.8Zn_0.2Cl₆ is further elucidated by density functional theory calculations. Most notably, whether coupled with LiCoO₂ or LiNi_0.8Mn_0.1Co_0.1O₂ cathodes, Li_2.4Zr_0.8Zn_0.2Cl₆-based all-solid-state batteries demonstrate exceptional cycling stability and rate performance. This high ionic conduction and moisture-resistant chloride electrolyte holds great promise for significantly advancing the commercialization of all-solid-state lithium batteries.