Cathode Engineering Enables Robust Interface Contact for High-Performance All-Sulfide-Based Li-SeS₂ Solid-State Batteries

All-solid-state Li-sulfur batteries are promising candidates for next-generation energy storage systems, owing to their high energy density and capability to address the safety concerns and electrochemical stability challenges (e.g., the shuttle effect) inherent to liquid-based batteries. However, the electronic insulating nature and limited reactivity of sulfur result in sluggish kinetics, low utilization, and restricted cathode mass loading. Herein, SeS₂ is proposed as a cathode active material due to its enhanced electronic conductivity compared to sulfur. SeS₂ composite cathodes prepared with varying composite strategies exhibited significant differences in the electrochemical performance. Benefiting from enhanced interaction at the three-phase interface, the ball-milled SeS₂/Li₆PS₅Cl/Ketjen Black composite cathode (SeS₂-BM@KB)-based cells delivered a reversible capacity of 673.5 mAh g^-1 after 300 cycles at 1 A g^-1 at 30 °C with a capacity retention of 80%. Furthermore, high loading cells achieved high areal capacities of up to 14.43 mAh cm^-2. This study highlights the potential of SeS₂ as an outstanding cathode material for developing high-energy-density all-solid-state batteries (ASSBs).