Advantage of PCM Over Air in Battery Thermal Management: To What Extent Does PCM Perform Better?

In this study, the competition between phase change material (PCM) and air in battery cooling was investigated in two scenarios. In the first scenario, three cases were introduced. In Case I, the battery heat is removed by the airflow. In Case II, the battery was cooled by PCM as well as air simultaneously. In Case III, the battery heat is fully absorbed by the PCM and then rejected to the ambient. In a battery cooling system, the effect of PCM depends on the C-rate and coefficient of heat transfer (CHT). For C-rate within 1C–10C and CHT lower than 30 W m⁻² K⁻¹, calculations showed that Case III (which only uses PCM) provided better cooling than Case I (airflow) and Case II (airflow + PCM). At CHT = 10 W m⁻² K⁻¹, Case III can cool the battery up to 17.28°C compared to Case I and up to 8.76°C compared to Case II. When CHT reaches 30 W m⁻² K⁻¹, the superiority of Case III diminishes. In this case, Case III can cool the battery up to 11.5 and 5.5°C compared to Case I and Case II, respectively. In the second scenario, the question was answered under what conditions PCM is preferable to airflow in battery cooling. At C-rate = 1, up to CHT = 30 W m⁻² K⁻¹, PCM is superior to airflow. When the C-rate rises, the competitive ability of PCM intensifies so that in C-rate = 5, PCM up to CHT = 60 W m⁻² K⁻¹ is preferable to airflow. At C-rate = 10, PCM up to CHT = 80 W m⁻² K⁻¹ is superior to airflow.