Preparation of thermally conductive composite phase change materials and its application in lithium-ion batteries thermal management

Phase change material (PCM) cooling performs excellently in lithium-ion battery (LIB) thermal management. In order to improve the thermal conductivity of PCM, the new thermally-conductive composite phase change material (CPCM) was prepared with the paraffin wax (PA), expanded graphite (EG), and SiC/SiO2 by physical adsorption method. The structure and thermal properties of different materials were analyzed by XRD, SEM, thermal conductivity and latent heat tests. Seven kinds of CPCMs (CPCM-1 to CPCM-7) are prepared by adding different proportions of SiC and SiO2. The thermal conductivity and latent heat range of CPCM 1 to 7 is 0.2383–4.086 W/(m·K) and 114.1–154.8 (J/g). The CPCM-5 with 10% EG and 10% SiC has the maximum thermal conductivity of 4.086 W/(m·K) and latent heat of 122.2 J/g, which can meet the requirements of LIB thermal management. The average highest temperature of Sanyo LIB and LiFePO4 LIB under CPCM cooling was 39.3 °C and 28.6 °C, which decreases by 7.8 °C and 3.6 °C compared with natural convection in the 2 C charging-discharging cycles. Compared with natural convection cooling, the average highest temperature of the Sanyo LIB with CPCM cooling decreased by 1.4 °C and 3.9 °C for 1 C and 2 C discharging, respectively. The CPCM-5 demonstrated the highest cooling efficiency and practicability. These tests can provide a theoretical basis for thermal management of LIB.