Oxygen‐Induced Structural Disruption for Improved Li+ Transport and Electrochemical Stability of Li3PS4

The performance of all‐solid‐state batteries (ASSBs) relies on the Li+ transport and stability characteristics of solid electrolytes (SEs). Li3PS4 is notable for its stability against lithium metal, yet its ionic conductivity remains a limiting factor. This study leverages local structural disorder via O substitution to achieve an ionic conductivity of 1.38 mS cm−1 with an activation energy of 0.34 eV for Li3PS4−xOx (x = 0.31). Optimal O substitution transforms Li+ transport from 2D to 3D pathways with increased ion mobility. Li3PS3.69O0.31 exhibits improvements in the critical current density and stability against Li metal and retains its electrochemical stability window compared with Li3PS4. The practical implementation of Li3PS3.69O0.31 in ASSBs half‐cells, particularly when coupled with TiS2 as the cathode active material, demonstrates substantially enhanced capacity and rate performance. This work elucidates the utility of introducing local structural disorder to ameliorate SE properties and highlights the benefits of strategically combining the inherent strengths of sulfides and oxides via creating oxysulfide SEs.