Phase change material with outstanding thermal stability and mechanical strength for battery thermal management

Effective thermal management is crucial for the reliability and efficiency of various systems, yet conventional phase change materials encounter limitations. This research introduces a novel solid-solid phase change material (SSPCM) designed for superior leak resistance and mechanical integrity. The SSPCM is synthesized via a polyurethane cross-linking reaction, employing polyethylene glycol (PEG) and hexamethylene diisocyanate (HDI) as precursors. This method chemically integrates phase change molecular chains into a thermosetting polymer matrix via polyurethane bonds, effectively mitigating leakage issues prevalent in traditional PCM composites while enhancing thermal stability. To augment thermal conductivity, we engineered a hybrid heat transfer network incorporating expanded graphite (EG), carbon nanotubes (CNTs), and advanced ceramic materials, including boron nitride (BN) and silicon carbide (SiC). Experimental evaluations reveal that the SSPCM achieves exceptional leak-proof performance, mechanical durability, and a significant improvement in thermal conductivity—up to 0.95 W/mK, marking a 4.13-fold enhancement over baseline values. Crucially, the developed SSPCM demonstrates remarkable efficacy in temperature regulation, maintaining the operational temperature of lithium battery packs within the optimal range of 20–55 °C under a 3C discharge rate. The internal temperature variation is kept below 3 °C, showcasing the material's potential in improving thermal management systems' reliability and performance.