Cross-Linked Polyurethane Phase Change Materials Based on Multiple Hydrogen Bonds with Excellent Mechanical, Flame Retardant and Energy Storage Properties for Novel Battery Jackets

This study designs and synthesizes a novel battery jacket material (PXHM2) through the polyurethane condensation reaction using polyethylene glycol (PEG) and m-xylylene diisocyanate (XDI) as main components and ammonia-based flame retardant additives as cross-linking agents. PXHM2 demonstrates superior performance in terms of flame retardant, mechanical properties, and energy storage capacity compared to a traditional PVC jacket material. In the flame retardant experiment, PXHM2 only experiences mild charring and melting without the occurrence of combustion, highlighting its excellent flame retardant characteristic. Additionally, PXHM2 effectively absorbs heat during short-time high-load operation of the battery, significantly lowering the overall temperature of the battery while enhancing safety. In the 3C discharge multiplier test, the PXHM2-wrapped commercial 18650-type battery shows effective temperature control below 58.9 °C, representing a 4.1 °C reduction in maximum operating temperature compared to PVC-wrapped battery under identical condition. Mechanical tests revealed that PXHM2 exhibits superior properties in terms of elongation at break and maximum stress, outperforming PVC encapsulant materials with higher mechanical performance. Further thermal energy storage experiments confirm that the phase change characteristics of PXHM2 can greatly improve the thermal energy storage capacity of battery jackets. This research provides an efficient and practical alternative for next-generation battery jacket materials, offering enhanced safety and passive thermal management capability.