High‐Resistance and Thermally Conductive Composite Phase Change Materials for Safe Lithium‐Ion Battery Thermal Management

ABSTRACT Lithium‐ion battery thermal management materials are required not only to provide efficient heat dissipation and latent heat buffering, but also to maintain reliable electrical insulation under practical operating conditions. In this work, a series of high‐resistance composite phase change materials (HPCMs) were developed using tetradecanol (TD) as the phase change matrix, SEBS as the supporting framework, and BN, BC, SiC, and EG as functional fillers via melt‐blending. The relationships among composition, microstructure, thermophysical properties, thermal stability, and electrical insulation were systematically investigated. The results show that filler type and network structure strongly influence the overall performance of the composites. With only 5 wt% EG, HPCM‐4 achieved a thermal conductivity of 1.5402 W/(m K), which was about 350% higher than that of pure TD, while all HPCMs maintained excellent electrical insulation with conductivity values generally below 10 −8 S/cm. HPCM‐6 exhibited the highest latent heat efficiency of 60.35%, indicating that the crystallization behavior of TD is highly dependent on the confinement effect imposed by the supporting framework and fillers. Battery thermal management tests further demonstrated that HPCM‐4 effectively suppressed temperature rise and improved temperature uniformity. At 30°C, the average surface temperature of the battery was reduced to 41.72°C and 44.00°C under 1C and 2C discharge conditions, respectively, while the maximum temperature difference was maintained below 3°C. These results confirm that rationally designed insulating composite PCMs can simultaneously provide efficient thermal regulation and intrinsic electrical safety, offering a feasible strategy for advanced battery thermal management applications.