Dual‐Conductivity Optimization Toward High‐Rate and Ultralong Life All‐Solid‐State Lithium‐Sulfur Batteries

ABSTRACT All‐solid‐state lithium‐sulfur batteries (ASSLSBs) hold great promise as next‐generation energy storage systems due to their high energy density. However, the practical application of sulfur‐based cathodes are largely hampered by their sluggish reaction kinetics, especially under high current densities and long‐term cycling. Herein, by employing electronic structure modulation via same‐group element doping, we successfully engineer lithium sulfide to concurrently facilitate ionic diffusion and electronic conduction, thereby significantly boosting its reaction kinetics. The formation of Se─S bonds, achieved by partial Se substitution, reorganizes the electronic structure of Li 2 S. This effect concurrently weakens sulfur's electronegativity to facilitate Li + diffusion and narrows the bandgap to boost electronic conduction. As a result, the Li 2 Se 0.2 S 0.8 cathode exhibits remarkable high‐rate capability, retaining 97.5% of its capacity after 1000 cycles at 1 A g −1 . Moreover, a full cell combining Li 2 Se 0.2 S 0.8 with a Si anode delivers a high energy density of 1324 Wh kg −1 , highlighting the feasibility of high‐specific‐energy and high safety ASSLSBs. This work provides an effective strategy toward high‐energy and high‐power solid‐state batteries.