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).