Abstract: Phase change materials (PCMs) have great potential in thermal energy management, but their low thermal conductivity, easy leakage, and poor thermal stability limit their wide application. After constructing the biomimetic leaf-vein-like three-dimensional (3D) structure of boron nitride (BN) and impregnated with polyethylene glycol (PEG), the comprehensive properties of phase change composites were effectively enhanced under low filler content. The PEG is stored in the 3D structure of BN, which can prevent leakage at high temperatures and enhance the composites’ thermal stability and storage modulus. As a fast channel of transmission of phonons, the BN skeleton can effectively reduce thermal resistance. When the amount of filler is 10 vol%, the highest thermal conductivity of the composite PCMs is 2.62 W m^-1 K^-1, which is 10.1 times than that of pure PEG. Under the infrared camera, the composite PCMs yielded excellent battery thermal management performance, indicating that the material has great potential in thermal management.

Key words: Phase change materials (PCMs), Boron nitride, Thermal conductivity, Thermal management