Passive thermal management of 21700 Li-ion batteries using plant-based eutectic phase change materials

Lithium-ion batteries, essential for electric vehicles, must operate within a specific temperature range for safety and enhanced cycle life. Air or liquid-based active cooling systems consume extra power, reducing the driving range by 10 to 15 %. This study developed and evaluated a sustainable plant-based eutectic mixture of phase change materials (PCMs) of organic fatty acids, with a latent heat of 155 kJ/kg, as a passive thermal management system. A Samsung 21,700 cell battery pack in a 3P4S configuration was cycled at a C/1.5 rate with the PCM eutectic mixture, maintaining the battery pack temperature about 7 °C lower than without PCM over 300 h of continuous operation. The eutectic PCM mixture showed remarkable stability without any thermal degradation, even after 150 melting and solidification cycles over 75 charge-discharge cycles. These findings highlight the plant-based PCM mixture as a sustainable, efficient passive thermal management solution for electric vehicle batteries.