Thermal management performance of lithium-ion battery based on phase change materials

As one of the most widely used power batteries, lithium-ion battery (LIB) plays an important role in electric vehicles and other industries. Temperature is an important factor affecting LIB performance and safety, and thus battery thermal management (BTM) is very important. At present, phase change material (PCM) has become a research hotspot because of high latent heat and no additional power consumption. In this study, the performance of 8 parallel 18650 LIB pack was numerically simulated, and the temperature variation characteristics of LIB was experimentally studied. The LIB heat generation model was established, and the temperature change of single LIB during the discharge process was tested. The influence of thermophysical parameters of composite phase change material (CPCM), such as thermal conductivity, melting point, latent heat and thickness, on the BTM characteristics of LIB pack designed in this paper were studied. The results showed that pure paraffin used in BTM can reduce the maximum battery temperature under 3C discharge by 28.0%. Adding expanded graphite to paraffin can further improve the thermal management performance of CPCM. When the thermal conductivity of CPCM was 2.0W/(m·K), the maximum temperature of battery under 3C discharge can be further reduced by 5.42℃, and the increase of the thermal conductivity of CPCM had little effect on the improvement of thermal management performance. Considering the maximum temperature and temperature uniformity of the battery pack, in order to obtain the best thermal management performance of the lithium-ion battery pack designed in this paper, the thermal conductivity of CPCM should be 2.0W/(m·K), the melting point of CPCM should be between 36—38℃, the latent heat of phase transition was about 212J/g, and the thickness of CPCM was 4mm. © 2022 Chemical Industry Press. All rights reserved.