Sb‐ and O‐Cosubstituted Li10SnP2S12 with High Electrochemical and Air Stability for All‐Solid‐State Lithium Batteries

Abstract The development of solid‐state electrolytes with high ionic conductivity, broad electrochemical stability, and high air stability is the key to realizing the practical application of all‐solid‐state batteries. Herein, Sb‐ and O‐cosubstituted Li 10 SnP 2 S 12 sulfide electrolytes are prepared for the first time. An appropriate amount of Sb and O substitution provides the optimized Li 10 SnP 1.84 Sb 0.16 S 11.6 O 0.4 electrolyte with the highest ionic conductivity of 2.58 mS ⋅ cm −1 at RT. Furthermore, the cyclic voltammetry analysis results demonstrate that the Li 10 SnP 1.84 Sb 0.16 S 11.6 O 0.4 electrolyte displays a broader electrochemical window of 1.4–5.0 V vs. Li + /Li than that of 1.7–2.4 V vs. Li + /Li for the nonsubstituted Li 10 SnP 2 S 12 . Moreover, benefitting from the soft acid Sb 5+ and hard base O 2− dual substitution, the air stability of electrolyte has been improved. Furthermore, the LiNbO 3 @LiCoO 2 /Li−In cell assembled with the Li 10 SnP 1.84 Sb 0.16 S 11.6 O 0.4 electrolytes exhibits a high initial discharge specific capacity of 124.7 mAh ⋅ g −1 at 0.05 C and maintains 85 % capacity retention after 200 cycles at 0.5 C and 25 °C, which is much higher than that of the cell assembled with the Li 10 SnP 2 S 12 electrolytes. XPS measurement results revealed that the mechanism of improving cell stability is the inhibition of electrolyte side reaction in the cathode. Sb‐ and O‐cosubstituted Li 10 SnP 2 S 12 was demonstrated to be a promising solid electrolyte for practical all‐solid‐state batteries.