Thermal Management Optimization of a Lithium-Ion Battery Module with Graphite Sheet Fins and Liquid Cold Plates

Abstract

Temperature uniformity of lithium-ion batteries and maintaining the temperature within the range for efficient operation are addressed. First, Liquid cold plates are placed on the sides of a prismatic battery, and fins made of aluminum alloy or graphite sheets are applied between battery cells to improve the heat transfer performance. Then a simulation model is built with 70 battery cells and 6 liquid cold plates, and the performance is analyzed according to the flow rate, liquid temperature, and discharge rate. Finally, the results show that temperature differences are mainly caused by the liquid cold plates. The fin surface determines the equivalent thermal conductivity of the battery. The graphite sheets have heterogeneous thermal conductivity, which help improve temperature uniformity and reduce the temperature gradient. With lower density than the aluminum alloy, they offer a lower gravimetric power density for the same heat transfer capacity. In addition to the equivalent thermal conductivity, the temperature difference between the cooling liquid and battery surface is an important parameter for temperature uniformity. Optimizing the fin thickness is found to be an effective way to reduce the temperature difference between the liquid and battery during cooling and improve the temperature uniformity.