Catalytic Interphases Enable Sulfur Redox Catalysis in All-Solid-State Lithium–Sulfur Batteries

Weak solid–solid contact with limited chemical and transport continuity is a common bottleneck in solid-state batteries, particularly in all-solid-state lithium–sulfur batteries (ASSLSBs), where Li2S/S8 conversion requires catalytic acceleration but lacks a continuous solid-state catalytic pathway. Here, we propose an interphase catalysis strategy for solid–solid sulfur conversion by transforming discrete catalyst/reactant interfaces into a chemically integrated reaction interphase. WO3 is identified as a suitable oxide to construct such a metastable mixed-anion S–W–O catalytic interphase on Li2S based on the work-function difference between the metal oxide catalyst and Li2S/S8, which serves as a practical screening rationale for evaluating the relative tendency toward sulfur–oxygen coordination exchange. The interphase contains unsaturated W centers and a polarized electronic environment, enabling coupled electron/Li+ transport and dynamically regulating sulfur redox through coupled sulfur-species exchange. This integrated interphase further stabilizes cathode interfaces during repeated Li2S/S8 conversion. As a result, the optimized cathode sustains stable cycling over 15000 cycles at 10 C and a temperature of 60 °C. A record-high Li2S loading of 30 mg cm–2 with an areal capacity of 21.2 mAh cm–2 is also achieved, demonstrating interphase catalysis as an effective route to overcome solid-state sulfur-conversion limitations in practical ASSLSBs.