Hydrogen-Bond Enabled Phosphite Based Intrinsic Flame-Retardant Solid-Solid Phase Change Materials Using Catalyst/Solvent-Free Multi-Component Reaction for Battery Thermal Management

Leakage and flammability are two critical safety issues limiting the practical application of organic phase change materials. Herein, a facile catalyst/solvent-free multicomponent reaction involving alcohols/amines/thiols, dimethyl phosphite, and benzaldehyde was developed to simultaneously address these drawbacks. The terminal phosphite groups endow intrinsic flame retardancy, while intermolecular interactions enhanced by P═O bonds transform the material into a viscous-to-solid state above its melting point, eliminating leakage. Notably, the reaction proceeds smoothly with quantitative yield under fully catalyst-free conditions as nucleophilicity increases from alcohols to thiols. Battery thermal management tests show the intrinsic flame-retardant solid-solid phase change materials extend the safe operation of lithium-ion batteries by 140%. Cone calorimeter tests reveal a 14 s ignition delay, and 37.6%, 29.8%, and 27.3% reductions in average heat release rate, total heat release, and total oxygen consumption compared to raw materials, confirming excellent flame retardancy. The material exhibits a maximum latent heat of 133.87 J/g, ensuring favorable thermal energy storage performance.