Triple-doped Argyrodite Sulfide Electrolyte with Improved Air Stability and Lithium Compatibility for All-Solid-State Li-Metal Batteries

Abstract

The shift to electric vehicles has highlighted challenges associated with lithium-ion batteries, and the need for safer and higher-energy–density all-solid-state batteries. However, sulfide-based solid electrolytes face problems with moisture reactivity and poor Li metal compatibility. In this study, we synthesized a Li5.4Al0.1P1−xSbxS4.7−2.5xO2.5xCl1.3 electrolyte, employing a dual-doping strategy inspired by the “hard and soft acids and bases” theory to enhance ionic conductivity, air stability, and Li metal compatibility. Sb–O dopants were introduced into Cl–Al-doped argyrodite solid electrolytes, achieving an optimized electrolyte with controlled dopant concentration. The electrolyte exhibited high ionic conductivity, excellent air stability, and Li metal compatibility. The all-solid-state Li metal battery showed promising initial discharge capacity. The improved air stability of Sb–O-doped electrolytes is attributed to the formation of Sb–S and P–O bonds, which reduces H2S emission by 78 % upon moisture exposure, effectively suppressing reactions with moisture. Enhanced Li metal compatibility induces the formation of Li–Sb alloy at the anode interface, inhibiting the growth of Li-dendrites. The Li symmetric cell demonstrates high critical current density and outstanding cycling stability. This study offers a sulfide electrolyte design for all-solid-state Li metal batteries, showcasing its potential for practical application with high air stability and Li metal compatibility.