Sulfurized Polyacrylonitrile Cathodes With Rapid Redox Kinetics for High‐Capacity and Long‐Cycle‐Life Lithium‐Sulfur Batteries

Abstract The quasi‐solid‐state reaction process in sulfurized polyacrylonitrile (SPAN) has emerged as a promising strategy to mitigate the polysulfide shuttle effect in lithium‐sulfur (Li‐S) batteries. However, the practical implementation of SPAN cathodes in ether‐based electrolytes remains challenging due to solvation‐induced structural rearrangement stemming from sluggish redox kinetics. Herein, a hierarchically structured composite (denoted as HSPAN) is developed through pyrolytic transformation of polystyrene (PS) templates coupled with carbon nanotubes (CNTs) network integration. This engineered architecture establishes dual electron‐ion transport channels, which synergistically enhance sulfur redox kinetics, suppress short‐chain sulfur dissolution, and enable stable charge/discharge cycling in ether electrolytes. The optimized HSPAN cathode delivers a specific discharge capacity of 1145 mAh g⁻¹ at 1 C rate with a sulfur content of 50%, maintaining 82% capacity retention over 800 cycles. Density functional theory (DFT) calculations reveal that the sulfurization treatment significantly narrows the HOMO‐LUMO energy gap by modulating the electronic structure of polyacrylonitrile, thereby enhancing the conductivity and redox activity of the material, providing a theoretical basis for designing high‐performance lithium‐sulfur battery cathodes. This work provides fundamental insights into the solvation dynamics of sulfurized polymers and demonstrates a viable pathway toward practical high‐energy‐density Li‐S batteries through rational electrode engineering.