Li10Sn0.95P2S11.9−xOx: A new sulfide solid electrolyte for all-solid-state batteries

All-solid-state batteries (ASSBs) have high safety and high energy density. Li ₁₀SnP ₂S ₁₂ sulfide solid electrolyte has attracted extensive attention due to its low fabrication cost and outstanding performance in ASSBs. However, its ionic conductivity and stability to lithium and air need to be further improved. Here, in order to avoid the formation of impurities related to Sn-related compounds, the content of SnS ₂ in the raw materials is reduced, and to improve ionic conductivity and stability to lithium and air. The S site is doped with O by the solid-phase sintering method, and a series of Li ₁₀Sn _0.95P ₂S _11.9−xO _x (0 ≤x ≤ 1) electrolytes are prepared. Li ₁₀Sn _0.95P ₂S _11.4O _0.5 (LS _0.95PSO _0.5) has a high ionic conductivity of 3.96 mS cm ⁻¹ and low activation energy after cold pressing. According to the Hard-Soft-Acid-Base theory, doping O into the electrolyte in advance will improve the stability. The ionic conductivity decay of LS _0.95PSO _0.5 after exposure to air is smaller, which proves that O doping improves the air stability of the electrolyte. LS _0.95PSO _0.5 also shows good stability to lithium. The assembled LNO@LCO/LS _0.95PSO _0.5/Li-In ASSB exhibits a high first-cycle discharge capacity of 133 mA h g ⁻¹ and good cycling stability.