Biobased Phase Change Material for Electric Vehicle Battery Thermal Management using Copper Fins: A numerical Investigation

Electric vehicles (EVs) are gaining popularity due to their zero tailpipe emissions, superior energy efficiency, and sustainable nature. EVs have various limitations, and crucial one is the occurrence of thermal runaway in the battery pack. During charging/discharging of EV battery pack which consists Li-ion cells generates significant amount of heat; thermal runaway in the battery pack happens due to excessive heat accumulation inside the cell because of ineffective cooling of the Li-ion cell/battery pack. It necessitates for the development of an effective EV battery thermal management system. In the present work thermal management of a 26650 Lithium iron phosphate (LFP) cell using natural air cooling, composite biobased phase change material (CBPCM) and its combination with copper fins is numerically investigated using multi-scale multi dimension - Newman, Tiedenann, Gu and Kim (MSMD-NTGK) battery model in Ansys Fluent at an ambient temperature of 306 K. Natural air cooling was found effective at discharge rates of 1C to 3C, maintaining cell temperature below the safe limit of 318 K. However, at 4C and 5C discharge rates, the temperature increased to 321.7 K and 325.4 K, respectively, indicating the inadequacy of natural air cooling for high-powered electric vehicles. Passive cooling techniques like CBPCM and CBPCM combined with fins were explored to resolve this limitation. Use of 4 mm thickness of CBPCM reduced the cell's maximum average temperatures to 312.7 K and 314.8 K for 4C and 5C discharge rates, respectively, while the integration of fins further reduced the temperatures to 310.7 K and 311.5 K. This reduction is due to the enhanced latent heat absorption of CBPCM and improved thermal conductivity provided by the fins. Overall, CBPCM combined with fins proved to be a more effective thermal management strategy than natural air cooling and standalone CBPCM. The findings suggest that CBPCM-based cooling systems, with enhanced heat transfer techniques, can maintain Li-ion cell temperatures within safe limits even under high discharge conditions, thereby reducing the risk of thermal runaway and improving the overall safety and efficiency of electric vehicle battery packs.