Numerical study of combined air and phase change cooling for lithium-ion battery during dynamic cycles

A combined thermal management system for lithium-ion battery, which conjugates the air cooling and phase change material (PCM) cooling, is proposed. Based on the three-dimensional flow and heat transfer models coupled with electrochemical reaction, the thermal performances of battery pack during the discharge-charge cycles with natural convection only, combined natural convection and PCM cooling, and combined forced convection and PCM cooling are investigated and compared. The results show that the maximum battery temperature with natural convection only exceeds the optimum temperature at 1C. The thermal performance of battery pack with combined forced convection and PCM is superior to that with combined natural convection and PCM, and the maximum temperature and maximum temperature difference are both controlled within the ideal range at 2C. For combined forced convection and PCM cooling, the recommended PCM thickness is 2 mm for application considering both cooling performance and cost. The phase change temperature of 35 °C is most advantageous to the proposed thermal management system at the ambient temperature of 26.5 °C, and the maximum temperature and maximum temperature difference can still fall within the optimal operation criteria even at the ambient temperature of 35 °C.