Delineating effects of cell arrangements, wall shapes, flow configurations, and phase change material on airflow-based lithium-ion battery thermal management

Lithium-ion batteries are commonly employed in electric and hybrid electric vehicles as the power source; however, they generate enormous heat during charging/discharging. Exceeding the desirable temperature range (20-40 degrees C) may detrimentally affect battery longevity, leading to thermal runaway. We studied the thermal response of an air-cooled battery thermal management system with alterations to cell arrangements, battery sidewalls, inflow/outflow configurations, and varying thicknesses of phase change material (PCM). A battery pack of cylindrical lithium-ion cells underwent comprehensive numerical testing at 1C and 3C discharge rates. The aim was to examine the impact of geometrical and flow modifications on the thermal performance. The evaluation focused on the average/maximum cell temperature, thermal uniformity, pressure drop, and performance evaluation criteria. At 1C, the zig-zag cell arrangement and trapezoidal/step walls delivered superior heat dissipation, reducing the maximum temperatures by 5 K (zig-zag) and 10 K (trapezoidal/step) compared to base cases with air cooling only. Furthermore, applying a 1 mm PCM significantly lowered the maximum temperature by 40 K (11.1 %) and improved the thermal uniformity by 24.4 K (79.7 %) compared to scenarios without PCM, particularly at 3C. Notably, the PCM thickness of 1.5 mm emerged as the most cost-effective solution for efficiently maintaining the battery temperature.