Experimental study on flexible flame retardant phase change materials for reducing thermal runaway propagation of batteries

The current research on phase change materials (PCM) for Battery Thermal Management Systems (BTMS) often focuses on a single characteristic, either flame retardancy or flexibility. PCM with both flexibility and flame retardancy is relatively uncommon, and studies on flexible PCMs have lacked experimental validation of their effectiveness. This study explored the optimal ratio of aluminium hydroxide (ATH)/ magnesium hydroxide (MTH)/ ammonium polyphosphate (APP), successfully creating a flexible flame-retardant PCM and applying it to battery cooling. The ratio of ATH/MTH/APP was determined as 9: 3:8, providing features such as leak resistance, high thermal conductivity, flame retardancy, and flexibility. Compared to the blank sample without flame retardants, the Peak Heat Release Rate (PHRR) and Total smoke production (TSP) of the PCM decreased by 48 % and 24.3 %, respectively. When applied to BTMS, the PCM restricted the battery's surface peak temperature and maximum temperature difference to 48.76 °C and 4.07 °C, respectively, at a discharge rate of 6C. After applying pressure to leverage flexibility, the temperature difference was further reduced to 1.76 °C, demonstrating the effectiveness of flexibility. In Thermal Runaway (TR) experiments, the PCM delayed the time triggered by TR by 84 s and reduced the maximum temperature by 92.3 °C. This work successfully combines flame retardancy and flexibility, offering valuable insights for the application of flame retardant flexible CPCM in BTMS and other relevant fields.