The intrinsic flame retardant multifunctional composite phase change material with phosphorus pentoxide for battery thermal safety system

Abstract

The temperature distribution has severely affected the performance of lithium-ion battery modules in electric vehicles (EVs), composite phase change material (CPCM) with excellent temperature controlling function as a passive battery thermal management system is essential to ensure the safety of battery module. In this study, the polyethylene glycol phosphate ester (PEGP) has been synthesized by esterification of phosphorus pentoxide and polyethylene glycol through the reaction of PEGP and melamine (MA), the network crosslinking structure has been built to greatly improve the anti-leakage performance. The flame-retardant CPCM containing PEGP/expanded graphite /epoxy resin/MA (PPEM) has been successfully designed and prepared. The results indicate that PPEM2 containing 20 wt% melamine and 7 wt% epoxy resin exhibit excellent antileakage and prominent flame retardant properties comprehensively. It should be noted that the peak heat release rate of PPEM2 has been reached to 352.41 KW/m2, which is obviously decreased by 47.55 % comparing with pure PEG. The main reason is that the grafting flame retardant elements (P) and melamine onto polyethylene glycol molecular chain by chemical reaction. In addition, it can maintain the operating temperature below 36 °C at 23 A discharge current. The battery module with PPEM2 can transfer the heat timely and promptly, exhibiting outstanding flame-retardant effect to avoid thermal runaway. With these prominent performances, this intrinsic flame-retardant CPCM can not only exhibit an excellent thermal management effect but also provide a promising approach to inhibit the thermal runaway propagation.