MoO₂‑Doped Li₇P₃S₁₁ for High-Performance All-Solid-State Lithium Batteries

Sulfide-based electrolytes are regarded as ideal materials for all-solid-state lithium batteries (ASSLBs) due to their amorphous structure and inherent mechanical softness. However, their practical application is hindered by limitations in ionic conductivity, lithium (Li) compatibility, and air stability. Herein, we propose a novel codoping strategy for glassy sulfide electrolytes by incorporating MoO₂ into traditional Li₇P₃S₁₁. The optimized sulfide solid electrolytes (SSEs) exhibiting an ionic conductivity of 2.57 mS/cm at room temperature attributed to the widening of Li⁺ transport pathway induced by Mo⁴⁺ doping. Furthermore, the introduction of O^2- enhances the air stability of sulfide-based solid-state electrolytes and suppresses H₂S generation by mitigating side reactions. By employing an advanced glassy sulfide electrolyte, symmetric cells have demonstrated stable cycling at 0.7 mA cm^-2 for over 400 h. Moreover, the full cell assembled with a MoO₂-doped (0.05%) Li₇P₃S₁₁ electrolyte and a composite LiCoO₂@LiNbO₃ (LCO@LNO) cathode (LCO@LNO/SSE/Li-In) delivered an initial discharge capacity of 122.47 mAh·g^-1 at a current density of 0.1 mA cm^-2. It exhibited excellent cycling stability with 77.31% capacity retention (88.32 mAh g^-1) and nearly 100% Coulombic efficiency after 100 cycles. The cell also exhibited excellent cycling performance and stability across rates ranging from 0.1 to 2C. This study offers valuable insights into the design of glassy sulfide electrolytes capable of suppressing dendrite growth and enhancing air stability.