Oriented composite phase change material with high thermal conductivity at low filler loading for battery thermal management

Conventional phase change materials (PCMs) use thermally conductive fillers to improve thermal conductivity and mitigate battery temperature rise. However, excessive filler addition inevitably weakens energy storage components and reduces the latent heat of phase change, making it challenging to balance thermal conductivity and latent heat. In this study, hexagonal boron nitride (h-BN) and spherical aluminum oxide (Al 2 O 3 ) were used as thermally conductive fillers, and paraffin (PA) served as the phase change matrix. An oriented composite phase change material (OCPCM) possessing both high thermal conductivity and high latent heat was prepared via freeze casting. Experimental results indicate that the prepared thermally conductive skeleton exhibits good orientation and structural support. After compounding with PA, it retained an intact microstructure, achieving high thermal conductivity (2.82 W/(m·K)) in the thickness direction while maintaining a high latent heat of phase change (145.66 J/g). Furthermore, the material exhibited good shape stability at high temperatures. When applied to battery modules, the OCPCM can reduce the surface temperature of the batteries by up to 10.3 °C, while keeping the temperature difference within the module consistently below 3 °C over multiple cycles, thereby achieving a more uniform temperature distribution. The excellent thermal performance of the OCPCM facilitates its application in battery thermal management systems.