Preparation and thermal characterization of boron nitride reinforced polyethylene glycol/expanded graphite composite phase change material.

A sizable composite phase change material (CPCM) that can be used for battery thermal management is prepared by blending expanded graphite (EG) and boron nitride (BN) with hot melt method and taking polyethylene glycol (PEG1000) as the raw material. The effects of the addition of EG and BN on the thermophysical properties of CPCM were investigated by adjusting the amounts of EG and BN. The chemical structure, phase change characteristics and thermal stability of CPCM were investigated based on infrared spectroscopy, differential scanning calorimetry and thermogravimetric analysis. A thermal conductivity test device was built based on the steady-state method to measure and calculate the thermal conductivity of CPCM. The results show that when the mass fraction of both EG and BN is 5%, the CPCM of PEG1000/5% EG/5 % BN has good thermal stability and the best thermal torage effect, with the latent heat of 126.72 kJ/kg, and the subcooling degree decreasing by 0.63 °C compared with that of PEG1000. The thermal conductivity of PEG1000/5% EG/5 % BN can reach 2.09 W/( m·K), which is 226.6% higher than that of PEG1000, and 27.4% larger than that of PEG1000/5% EG. Overall, PEG1000/5% EG/5% BN has a simple preparation process and a thermal conductivity greater than 2 W/(m·K) and a latent heat greater than 120 kJ/kg, making it suitable for battery thermal management systems. [ABSTRACT FROM AUTHOR]