Argyrodite-structured lithium-ion conductors have garnered widespread attention due to their high room-temperature lithium-ion conductivity and low cost. However, these materials often suffer from poor air stability and limited chemical and electrochemical stability windows, which restrict their practical applications. In this study, we propose a Bi/O/Br tri-doped argyrodite (Li_5.5PS_4.5Cl_1.5) electrolyte. At a Bi substitution level of x = 0.02, the material (Li_5.5+2xP_1-xBi_xS_4.5-1.5xO_1.5xCl_0.8Br_0.7) achieves a high ionic conductivity of 9.34 mS·cm^-1 at room temperature. Furthermore, Li symmetric cells with this electrolyte exhibit an ultra-high critical current density of 1.2 mA·cm^-2 and stable Li⁺ plating/stripping behavior for over 1200 hours at 0.3 mA·cm^-2 /0.3 mAh·cm⁻². This stability is attributed to the formation of Li-Bi alloys, which suppress lithium dendrite growth and enhance ionic transport and interfacial compatibility. This work offers a promising solution for the development of sulfide-based electrolyte toward all-solid-state batteries.

Argyrodite, Sulfide-based electrolyte, All-solid-state batteries, Tri-doping