The Polymer Society of Korea

Abstract

Battery thermal runaway causes fire and explosion risks, emphasizing the need for flame-retardant strategies. Adding flame-retardant additives to electrolyte is common, but it raises viscosity and lowers ionic conductivity. Herein, an organic–inorganic hybrid flame-retardant separator was developed by coating both sides of a polyethylene (PE) separator with 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO)-containing cross-linked polymer and Boehmite ceramic particles, inspired by conventional ceramic-coated separators. The DOPO moieties provide radical scavenging and char-forming effects, while Boehmite contributes an endothermic effect through water release upon heating. The cross-linked polymer matrix effectively encapsulates the ceramic particles, mitigating interfacial resistance caused by direct contact between ceramic particles and the electrode. Furthermore, the organic–inorganic material hybridization yields a porous structure that ensures favorable ionic conductivity.