Enhancing Moisture and Electrochemical Stability of the Li 5.5 PS 4.5 Cl 1.5 Electrolyte by Oxygen Doping.

Chlorine-rich argyrodite-type solid electrolyte Li 5.5 PS 4.5 Cl 1.5 has been a promising choice for solid-state batteries (SSBs) because of its ultrafast Li-ion conduction. However, the poor air/moisture stability and low electrochemical stability with pristine high-voltage cathodes hinder their applications. Herein, O-substituted Li 5.5 PS 4.5- x O x Cl 1.5 ( x = 0, 0.075, 0.175, and 0.25) solid electrolytes are successfully synthesized. Among them, Li 5.5 PS 4.425 O 0.075 Cl 1.5 delivers high ionic conductivity, improved moisture resistance, and enhanced electrochemical stability in higher voltage windows. SSBs using Li 5.5 PS 4.425 O 0.075 Cl 1.5 show higher capacities and superior cyclability than those using Li 5.5 PS 4.5 Cl 1.5 combined with a pristine LiNi 0.8 Mn 0.1 Co 0.1 O 2 cathode when operated at a high end-of-charge voltage of 4.5 V (vs Li + /Li 0 ). Moreover, the batteries exhibit outstanding performance in a wide temperature range. This work provides a strategy to modify the inherent drawbacks of sulfide electrolytes, promoting their practical applications.