Li ₂ S Cathode Mediated by Diphenyl Chalcogenides in All‐Solid‐State Batteries

Abstract Lithium sulfide (Li ₂ S), as one of the critical cathodes in all‐solid‐state batteries, shows promising potential. However, its ion and electron blocking characteristics necessitate a high charge overpotential for activation, which can result in the decomposition of sulfide‐based solid‐state electrolytes. In this study, diphenyl chalcogenides are applied as redox mediators to reduce the initial charge voltage and improve the utilization of Li ₂ S in all solid‐state lithium‐sulfur batteries. Among them, diphenyl ditelluride (DPDTe) enables the highest initial charge capacity (963.1 mAh g ⁻¹ ) of Li ₂ S. The Li ₂ S‐DPDTe composite cathode, along with Li ₇ P ₃ S ₁₁ sulfide electrolyte and In‐Li anode, exhibits a low charge voltage of 2.4 V. After 360 cycles, the battery demonstrates an average areal discharge capacity of 0.9 mAh cm ⁻² at a current density of 0.2 mA cm ⁻² (706.8 mAh g ⁻¹ based on the mass of Li ₂ S). This study aims to use diphenyl chalcogenides as mediators to lower the initial overpotential of Li ₂ S, thereby aligning with the narrow electrochemical window of sulfide electrolytes and providing valuable insights for high‐energy‐density all‐solid‐state batteries.