Experimental Study on Battery Thermal Management of Cpcm Coupled with Micro-Grooves Flat Heat Pipe at Low Temperature

Abstract

In the low temperature environment in winter, lithium-ion batteries will have significant performance degradation and life decay, and there are also startup difficulties and safety issues. To prevent the low temperature of the batteries, a set of battery thermal management system (BTMS) combining the composite phase change material (CPCM) and micro-groove flat heat pipe (FHP) was established in this study. By absorbing and storing the heat production of the batteries through CPCM, BTMS can not only prevent the batteries from high temperature, but also release heat during non-working periods to achieve heat preservation of the batteries. The performance of BTMS at different battery discharge rates and ambient temperatures was studied. The results show that under the action of CPCM-FHP BTMS, the maximum temperature of the batteries at discharge rate 5C and below does not exceed 45℃, while the maximum temperature of the batteries at 5C without thermal management has reached more than 60℃. In the -20℃ environment, the batteries reduced from 40.17℃ to 0℃ for more than 5.8h with the CPCM-FHP thermal management after 5C rate discharge, the average cooling rate during the standing period was about 6.65℃/h, and the batteries could also be maintained above 0℃ for at least 3h at 1C. However, the temperature of the batteries without thermal management has been reduced to -10℃ or below in the same time, and the cooling rate is about 1.3-2 times that of the CPCM-FHP thermal management with a significant difference. It is proved that the BTMS can significantly reduce the cooling rate of the battery during the low temperature static placement and can both heat dissipation and heat preservation.

Keywords: Thermal management, Micro-grooves flat heat pipe, Phase change material, Low temperature, Heat Transfer