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

Graphical Due to the Sb- and O-cosubstitution , the Li 10 SnP 1.84 Sb 0.16 S 11.6 O 0.4 sulfide electrolyte with high ionic conductivity, broad electrochemical window, and high air stability was prepared for high-performance all-solid-state battery. Electrochemical measurement and postmortem analysis of cycled electrodes results revealed that the mechanism of improving cell stability is the inhibition of electrolyte side reaction in the cathode. Sb- and O-cosubstituted sulfide electrolyte was demonstrated to be a promising solid electrolyte for practical all-solid-state battery. 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.