γ‐Ray Controlled Topological Evolution of Binders for Stable and Activated Li─S Battery Cathodes

ABSTRACT γ‐ray irradiation facilitates controllable, clean, and reagent‐free cross‐linking of polymer networks without side reactions. Leveraging these merits, we precisely tune the irradiation dose to engineer a three‐dimensional (3D) poly(vinyl alcohol) (PVA) binder network for lithium‐sulfur (Li─S) batteries. By integrating multiscale synchrotron radiation X‐ray characterization techniques, we elucidate how the γ‐ray irradiation dose governs the 3D network structure and consequently regulates sulfur cathode stability and sulfur reaction kinetics without using catalysts. The optimal dose of 3 kGy yields a favorable PVA binder network featuring a dense framework, favorable connectivity, and homogeneous spatial distribution. The interpenetrating structure composed of binder, sulfur, and conductive agent leads to coupling of the mechanical architecture with the electron‐conductive network, accompanied by high‐flux lithium‐ion diffusion, thereby relieving cathode volume variation and promoting sulfur interconversion kinetics. This resulting sulfur cathode delivers a capacity decay rate of only 0.045% per cycle over 1000 cycles at 1 C. Moreover, a 1.23 Ah‐level pouch cell fabricated with the 3 kGy dose‐enabled PVA (3‐PVA) binder achieves an energy density of 390.2 Wh kg −1 . This study highlights γ‐ray irradiation as a clean and controllable strategy to engineer binder topological structure, disclosing dose‐dependent structure–property relationships that govern electrode mechanics and electrochemistry.