Thermal Characteristics of Stagger-Arranged Battery Pack with Holding Plates Cooled by Longitudinal Airflow

Abstract

The charging/discharging characteristics and life cycle of a lithium-ion battery are significantly dependent on the battery thermal performance. In this study, the three-dimensional numerical model was developed to explore the effects of thermal conductivities of the battery, holding plate, and diameter of venting holes on the thermal behaviors of the stagger-arranged battery pack cooled by longitudinal airflow. The numerical model was validated by our previous experimental results. Numerical results illustrated that the thermal conductivities of the battery and holding plate have nearly no effect on the thermal behaviors of the 18650 lithium-ion battery pack; therefore, the traditional epoxy (khp=0.2 W·m−1·K−1) is an effective material for the holding plate with the advantages of low cost, excellent insulation, and thermal conductivity properties. The heat-transfer coefficient between the air coolant and battery or holding plates does not gradually decrease along the horizontal airflow direction due to the periodic thinning and damaging of the flow boundary layer caused by the venting holes, which indicates that the venting holes can improve the overall heat-transfer performance of the battery pack. At last, comprehensively considering the effects of the diameter of the venting holes on thermal characteristics, cooling efficiency, and structural strength, the appropriate diameter of the venting holes should be 4 mm for the 18650 lithium-ion battery with holding plates.