Enhanced Air and Electrochemical Stability of Li₇P₃S₁₁–Based Solid Electrolytes Enabled by Aliovalent Substitution of SnO₂

Sulfide solid electrolytes are excessively investigated on account of the high ionic conductivity. However, their applications are hindered by the air-sensitivity and poor interfacial compatibility against lithium metal. Herein, Sn and O co-doping strategy is designed to enhance the stability of the sulfide-based solid state electrolyte towards air moisture and lithium metal. The ionic conductivity of Li₇Sn_0.1P_2.8S_10.5O_0.2 is twice of that of the pristine Li₇P₃S₁₁ due to the synergistic effect of Sn and O prepared by the solvent-assisted ball milling method. Impressively, with partial substitution of S by O and P by Sn in Li₇P₃S₁₁, the newly-designed electrolyte largely suppresses the hydrolysis in the air. Furthermore, galvanostatic cycling of symmetric cells demonstrate that Li₇Sn_0.1P_2.8S_10.5O_0.2 enables improved interfacial compatibility towards lithium metal. Hence, the all-solid-state batteries with Li₇Sn_0.5xP_3−xS_11−2.5xO_x significantly elevate the cyclability and the reversible capacity. The co-doping strategy provides a promising approach to achieve excellent chemical and electrochemical stability for the large-scale application of sulfide-based solid state electrolytes.