Sn-doped mixed-halide Li6PS5Cl0.5Br0.5 argyrodite with enhanced chemical stability for all-solid-state batteries

Abstract

The synthesis and characterization of Sn-doped Li₆PS₅Cl_0.5Br_0.5 solid-state electrolytes are presented. By incorporating Cl and Br, the solubility of Sn dopants in the argyrodite framework is significantly improved without compromising the high ionic conductivity of material. Sn substitution for P enhances both the chemical robustness and interfacial stability of the electrolyte, addressing key challenges in electrolyte stability. The inclusion of Sn strengthens the structural integrity of Li₆PS₅Cl_0.5Br_0.5, mitigating atmospheric degradation. Electrochemical studies reveal that Sn doping markedly increases ionic conductivity and reduces the activation energy for Li-ion mobility, thereby improving battery performance. Structural analyses indicate that Sn incorporation expands the unit cell and facilitates the formation of a Li–Sn alloy at the electrolyte–electrode interface. This alloy formation promotes rapid Li-ion migration and stabilizes the interface, contributing to enhanced electrochemical stability. The findings underscore the synergistic benefits of halogen substitution and Sn doping, demonstrating their collective impact on the performance and durability of sulfide-based solid electrolytes.