Concentration‐Gradient Solid‐State Sulfur Cathode Enabling Improved Energy Storage Under High Sulfur Loadings

ABSTRACT All‐solid‐state lithium‐sulfur battery (ASSLSB) represents one of the most promising energy storage technologies attributed to the high energy density, intrinsic safety, and economic viability. However, introducing solid‐state electrolytes (SEs) into the sulfur cathode triggers thorny problems of deficient sulfur loading, inadequate sulfur utilization, and severe interfacial degradation. Here, we demonstrate a spatially tailored sulfur cathode architecture with concentration‐gradient SE and conductive agent distribution. From the separator side to the current collector, SE concentration is decreased from 65 to 55 wt.%, which promotes lithium‐ion transport through continuous pathways and concentration‐driven forces. Conversely, the concentration of conductive agent increases from 5 to 15 wt.% to ensure efficient electron conduction. The mutually opposing concentration gradients simultaneously suppress the SE degradation by minimizing its interfacial contacts with conductive agents. As a result, the ASSLSB delivers enhanced sulfur utilization (1315 mAh g −1 ) under 7.6 mg cm −2 , while maintaining a low capacity fading rate of 0.05% per cycle over 225 cycles. Even further increasing the sulfur loading to 11.4 mg cm −2 , a high capacity of 10.96 mAh cm −2 is achieved.