Feasible Catalytic-Insoluble Strategy Enabled by Sulfurized Polyacrylonitrile with In Situ Built Electrocatalysts for Ultrastable Lithium–Sulfur Batteries

To date, elemental sulfur has been considered as a prospective cathode material for exploring high-energy power systems with low cost and sustainability. However, its practical commercialization has been impeded by inherent drawbacks of notorious capacity decay, unsatisfied insulating nature, and sluggish conversion chemistry. To address these issues, for the first time, freestanding nanofibrous networks with hierarchical nanostructures are facilely constructed by inlaying electrocatalytic bimetallic chalcogenides (Fe_xMn_1–xS nanoparticles) into conductive graphene nanosheet (GN)-doped sulfurized polyacrylonitrile (SPAN) fiber matrices. Covalent-bonded SPAN featuring an insoluble mechanism serves as a reliable cathode substrate with enhanced electrostability and high sulfur utilization, while high-surface-area GN dopants promote conductivity improvement and rapid electron transfer. Meanwhile, the results prove that sulfiphilic Fe_xMn_1–xS nanoparticles with abundant electrochemically active sites facilitate construction of uniform deposition interfaces and efficient electrocatalysis conversion toward lithium polysufides. This feasible catalytic-insoluble cathode strategy drives the Li–S battery, which exhibits excellent electrochemical performances with a remarkable reversible discharge capacity of 967 mA h g^–1 and a capacity retention of 623 mA h g^–1 after 500 cycles. Moreover, the corresponding lithiation/delithiation mechanisms are systematically investigated through complementary morphological and spectral analyses, providing valuable insights into advanced metal–sulfur batteries.