Passive thermal management system for electric-hybrid vehicles—hot climate condition

Abstract To achieve net-zero emissions targets, electric vehicles and hybrid electric vehicles are prioritized for reducing CO₂ emissions in transportation. Among the available battery systems, lithium-based batteries are the most prominent due to their high energy storage density. The primary safety risk in lithium-ion batteries is thermal instability caused by overheating. Battery capacity drops significantly at operating temperatures >45°C. At higher temperatures, the battery undergoes thermal decomposition, and once it reaches a critical temperature, it enters an irreversible state of thermal instability, which can lead to an explosion. In our previous study, we developed flexible phase-change material (PCM) packages for passive thermal energy storage of heat from lithium-ion batteries in hybrid electric vehicles/electric vehicles, extending battery life and ensuring safety. In this paper, we present the results of applying these PCM packages under hot climate conditions. The test results show that both paraffin and composite PCMs can maintain lower temperatures compared to battery modules without PCM, ensuring safe operation. The PCM composite, which includes highly conductive materials, demonstrated better thermal performance than paraffin alone.