Experimental study on the comparative thermal performance of lithium-ion battery cooling strategies

With the increasing heat generation of lithium-ion batteries under high-power operation, selecting an appropriate battery thermal management system (BTMS) has become essential for ensuring thermal safety and operational stability. In this study, a unified experimental platform was established to systematically compare four representative cooling strategies, including natural convection cooling, forced-air cooling, phase change material (PCM) cooling, and pool boiling cooling. Experiments were conducted using a seven-cell Samsung INR21700-50G lithium-ion battery module under discharge rates ranging from 0.5 to 2.5C. Microencapsulated n-Eicosane PCM was employed for PCM cooling, while dielectric KEY-116 coolant was used in the pool boiling cooling system. The thermal performance of each cooling strategy was evaluated in terms of maximum temperature and temperature uniformity. The results show that natural convection cooling exhibits insufficient heat dissipation capability at high discharge rates, with the maximum battery temperature reaching 88.8°C at 2.5C. Forced-air cooling reduces the temperature rise but suffers from poor temperature uniformity due to non-uniform airflow distribution. PCM cooling effectively suppresses the initial temperature rise at low to moderate discharge rates. However, its cooling performance deteriorates significantly once the latent heat capacity is exhausted under sustained high heat-flux conditions. In contrast, pool boiling cooling demonstrates the best overall thermal management performance, maintaining the maximum battery temperature at approximately 51.4°C and reducing the maximum temperature difference to around 3.1°C at 2.5C. Compared with natural convection cooling, pool boiling reduces the peak temperature and temperature difference by approximately 42% and 67%, respectively. The results indicate that pool boiling cooling is particularly suitable for sustained high-power battery applications, while other cooling strategies involve different trade-offs among thermal performance, energy consumption, system complexity, and engineering applicability. This study provides experimental guidance for the selection and design of BTMS under different operating conditions.