A novel strategy of enhanced thermal performance in air cooled lithium-ion battery by wavy walls

Abstract

Electric vehicles (EVs) with rechargeable lithium-ion batteries are one of the most appealing choices for electrochemical energy storage to address global energy challenges and environmental concerns caused by rising carbon emissions. However, to maintain the performance and longevity of these high power batteries, a well-planned and effective cooling mechanism is required. Here, a novel air-based battery thermal management system (BTMS) is proposed to realize an improved cooling performance. We examined the thermal performance of an air-cooled lithium-ion battery pack of 3x5 Sony 18650 cells by introducing wavy (undulated) sidewalls for the discharge period of the cells. Influence of air inflow velocity (U0) and number of undulations on wavy wall have been delineated at a discharge rate of 2C and 3C. As obvious, the cooling improves with the increasing U0. Interestingly, a significant reduction (∼ 8-10 K) in the average and maximum cell temperature was seen simply by creating an optimal number of undulations on the walls as compared to the results obtained from straight walls. The highest cooling performance was observed when the undulations form a trough above the cells, however, the highest pressure drop was experienced in such cases. A trade-off between the cooling enhancement and power requirement (∼ pressure drop) has been presented by a performance plot. Finally, the efficacy of system was ensured by changing the number of rows and columns of the cell arrangement in the battery pack. An enhanced heat dissipation and thermal uniformity was seen in all the cases when wall undulations are present.