Numerical investigation of hybrid PCM–liquid cooling for lithium-ion battery thermal management

Abstract In order to ensure safety, efficiency and overall longevity of Li-ion battery it is important to maintain its thermal stability especially at higher discharge rate. In this study, the thermal behavior of a LiCoO₂ 26,650 lithium-ion cell is numerically investigated using ANSYS Workbench at discharge rates of 2 C, 3 C, and 4 C. Three configurations are evaluated for three different operating condition battery pack without cooling, battery pack with a phase change material (PCM)-based battery thermal management system (BTMS), and a PCM–liquid hybrid BTMS. In absence of thermal management system, the maximum cell temperatures are observed to be 328.31 K, 345.16 K, and 359.02 K at 2 C, 3 C, and 4 C, respectively, indicating significant temperature rise at higher C-rates. The implementation of a PCM-based BTMS reduces the peak temperatures to 315.53 K, 319.27 K and 333.41 K respectively. This corresponds to around 3.9%, 7.5% and 7.1% temperature reduction relative to the uncooled condition. However, complete melting of the PCM is observed at higher discharge rates, thereby limiting its effectiveness during prolonged operation under such conditions. To overcome this limitation, a PCM–liquid hybrid BTMS with water cooling channels operating at a coolant inlet velocity of 0.08 m/s is introduced. This hybrid system further reduces the maximum temperatures to 308.75 K, 317.70 K and 326.35 K at discharge rates of 2 C, 3 C and 4 C respectively. This corresponds to temperature reductions of around 6.0%, 8.0% and 9.1% when compared to the battery model without cooling. The simulation results show that the PCM-liquid hybrid BTMS offers better temperature control and improved uniformity, especially at higher discharge rates.