The Polymer Society of Korea

Abstract

 Commercial polyolefin separators for Li-ion batteries suffer from severe thermal shrinkage and hydrophobicity, which limit their safety and performance. Ceramic coatings often delaminate because binders rely on weak non-covalent interactions. Here, we report a multifunctional flame-retardant separator based on a photoactive binder, benzophenone-functionalized polyacrylic acid (BPA). The BPA-boehmite water-based slurry is covalently anchored to polyethylene (PE) separators via ultraviolet (UV) irradiation. This process generates C-C bonds with the PE surface while inducing self-cross-linking, creating a network that acts as a rigid thermal skeleton and hydrophilic interface. This architecture provides superior heat resistance and adhesion, while the boehmite layer enhances Li⁺ transport and provides flame retardancy via endothermic dehydration. This covalent anchoring strategy offers a scalable platform for advanced separators, ensuring high safety and long-term reliability.