Study on thermal aspects of lithium-ion battery packs with phase change material and air cooling system

During the operation of the lithium batteries, due to energy loss, the heat will be generated. Therefore, effective heat dissipation technique is required for operation of the lithium batteries under the safe temperature limit. To increase the safety, efficiency, and lifetime of these batteries, the thermal management is an important key factor. Nickel cobalt lithium manganate (NCM) batteries have high energy ratio and high voltage output. The thermal performance of phase change material (PCM) and air cooling system, as a combined cooling system, employed for single battery and battery packs is investigated in this study. NCM-21700 lithium-ion battery is considered for investigation. With boosting DR, the internal temperature of the battery is increased rapidly, and the temperature uniformity is decreased. The analysis of single cell equipped with the PCM showed that the PCM with delta = 12 mm is the best choice at DR = 3C. In addition, it was concluded that under the synergistic effect of air cooling and PCM, since the PCM continuously takes away the heat of the battery, and the air can remove the heat absorbed by the PCM with high rate, the performance of the battery can be improved. The final battery surface temperatures are 30.53 degrees C, 29.97 degrees C, 29.71 degrees C, and 29.93 degrees C for the PCM thicknesses of 5, 10, 12, and 15 mm, respectively. During the discharge process, the battery temperature under the synergistic effect of the air and the PCM increases gently and reaches to 30.6 degrees C. The PCM cannot fully control the battery temperature change at high discharge rates. The low thermal conduction in PCM leads to the inability to effectively transfer heat to the external surface of the PCM.