Enhanced performance of lithium‐sulfurized polyacrylonitrile batteries via multifunctional CoS ₂ /NiS ₂ heterostructures and intrinsic electric fields

Abstract Lithium‐sulfurized polyacrylonitrile (Li‐SPAN) batteries are an advanced class of Li–S energy storage systems that effectively mitigate the polysulfide shuttle effect. However, conventional SPAN cathodes experience low active material retention (< 40 wt%) and sluggish electrochemical kinetics, which limit their practical application. To address these challenges, this study introduces a CoS 2 /NiS 2 @SeSPAN composite nanofiber membrane as a high‐performance Li‐SPAN cathode. The cathode was synthesized through electrospinning Co/Ni salts with PAN, followed by hydrothermal deposition of Ni‐ZIF‐67 and SeS x ‐assisted thermal treatment to form a CoS 2 /NiS 2 heterostructure within the SeSPAN matrix. Experimental validation and density functional theory simulations confirmed that the cathode electrolyte interphase layer effectively encapsulated the active material, extending the solid‐state reaction pathway. This hierarchical porous architecture enabled a high active material loading of 59 wt%, which considerably exceeds that of conventional SPAN‐based cathodes. The three‐dimensional interconnected fiber network maximized the exposure of the CoS 2 /NiS 2 heterojunction, while the metal sulfides increased the conductivity to facilitate efficient electron and ion transport. The intrinsic electric field within the CoS 2 /NiS 2 heterostructure further enhanced polysulfide adsorption and catalytic conversion, accelerating the electrochemical kinetics. As a result, the CoS 2 /NiS 2 @SeSPAN cathode had an initial discharge capacity of 678 mAh g −1 at 0.2C, maintaining 634 mAh g −1 at 0.5C. Remarkably, the battery maintained 98.2% of its capacity after 800 cycles, highlighting its outstanding long‐term cycling stability. The substantial potential of CoS 2 /NiS 2 @SeSPAN for high‐performance Li‐SPAN batteries and the critical role of heterostructure engineering in next‐generation energy storage technologies are highlighted in this study.