Design and Analysis of Battery Thermal Management System Using Phase Change Material for Lithium-Ion Batteries in Electric Vehicles

Battery thermal management system (BTMS) plays an imperative role in keeping the temperature of batteries in electric vehicles below 35°C to avoid power degradation and thermal runaway. The BTMS using phase change material (PCM) has advantages over other cooling techniques. It provides more cooling capacity than air cooling, more compact and less expensive than liquid cooling, more battery surface contact than heat pipes and temperature uniformity during phase change of PCM. However, it has disadvantage of low thermal conductivity. Many studies recommended the addition of fins and additives to increase heat transfer in PCM but generate the need to design a PCM BTMS for whole battery pack while considering these improvements which is the sole purpose of this study. The simulation of battery pack of 25 Samsung INR18650 lithium- ion cells under full discharging at 3C rate is conducted which shows temperature decreases from 55°C to 36°C using commercially available paraffin PCM with 0.2 W/mK thermal conductivity. Circular fins are the most appropriate fins in battery pack and decrease the temperature to 35°C. Using PCM with expanded graphite additive decreases temperature to 33°C. It shows that thermal conductivity enhanced by additives has more effect on PCM performance than fins and effect of increasing thermal conductivity on decreasing maximum temperature reduces exponentially.