Thermal Analysis of a Li-ion Battery System with Indirect Liquid Cooling Using Finite Element Analysis Approach

The performance and life of Li-ion battery packs for electric vehicle (EV), hybrid electrical vehicle (HEV), and plug-in hybrid electrical vehicle (PHEV) applications are influenced significantly by battery operation temperatures. Thermal management of a battery pack is one of the main factors to be considered in the pack design, especially for those with indirect air or indirect liquid cooling since the cooling medium is not in contact with the battery cells. In this paper, thermal behavior of Li-ion pouch cells in a battery system for PHEV applications is studied. The battery system is cooled indirectly with liquid through aluminum cooling fins in contact with each cell and a liquid cooled cold plate for each module in the battery pack. The aluminum cooling fins function as a thermal bridge between the cells and the cold plate. Cell temperature distributions are simulated using a finite element analysis approach under cell utilizations corresponding to PHEV applications. Both single cold plate cooling and dual cold plate cooling were analyzed. Influences of the cold plate surface temperature gradients on the cell temperature distributions were also studied. The studies show that dual cold plate cooling has about twice the cooling capacity of single cold plate cooling and that the dual cold plate configuration can also provide cell terminal and busbar cooling.