Effects of the structure arrangement and spacing on the thermal characteristics of Li-ion battery pack at various discharge rates

The structure arrangement and the spacing of cells are key factors related to the thermal safety of the Li-ion battery pack. To explore their effects on thermal performance of the cell module, a series of discharge tests on cell packs were carried out, and the temperature distribution were monitored along cells with various structure arrangements and cell-to-cell distances. Thereafter, the heat generation and heat dissipation of the cells were calculated based on the monitored temperature to quantitatively analyze the thermal balance. Results showed that the temperature of cells with ring structure rose faster than the other two cases with line and square respectively, and its maximum temperature was highest. Its temperature difference was up to 8.5 degrees C, and its discharge time was nearly 200 s less than the other two structures, which indicated its worst thermal performance. Increasing of cell-to-cell distance improved the thermal performance, while the improvement was rather slight once the distance is more than 7 mm. In addition, the heat transfer under different discharge rates were also discussed, which showed that the temperature rise was controlled by heat dissipation and generation for 1C and 3C, respectively, while controlled by their coupling effects at 2C.