Coral-like sulfurized polyacrylonitrile/graphene hybrid film with amorphous ZnS clusters for ultra-stable lithium-sulfur batteries

Sulfonated polyacrylonitrile (SPAN) is considered a highly promising cathode active material owing to its unique solid-solid conversion mechanism, which effectively mitigates the shuttle effect. However, its practical application is hindered by relatively low sulfur content and sluggish reaction kinetics, leading to reduced energy density. This work designs and prepares a coral-like self-supporting composite cathode composed of sulfonated polyacrylonitrile, graphene, and amorphous zinc sulfide through a simple liquid-phase exchange and subsequent sulfidation strategy. This coral-like architecture features a large specific surface area and a three-dimensionally connected porous framework, effectively promoting electrolyte penetration and offering abundant channels for Li + ion transport. More importantly, the amorphous ZnS that is generated in situ and uniformly anchored in the framework acts as highly active polar sites, demonstrating strong chemical adsorption and catalytic conversion capabilities toward polysulfides. Thanks to the synergistic effect of the three-dimensional porous structure and chemical anchoring of the coral-like structure, the obtained composite film cathode exhibits outstanding electrochemical performance: it has a high initial discharge specific capacity of 1824 mAh g −1 at 0.5C, and it can still maintain a stable capacity of 1247 mAh g −1 after 500 cycles, with a capacity decay rate of each cycle as low as 0.063%. This study highlights the dual role of microstructure regulation and active site design, providing a promising candidate for the positive electrode material of advanced lithium‑sulfur batteries.