Multifunction composite phase change material with inorganic flame retardant and organic form stability for improving battery thermal safety

<p>Phase change materials (PCMs) with superior cooling capacity and temperature equalization have great potential to mitigate thermal accumulation, benefiting the safety of electric vehicles (EVs) drivers. Although the composite phase change materials (CPCMs) with organic form stable addition can prevent leakage, they are still restricted in battery module due to easy flammable performance. Another challenge is that the inorganic flame retardants always distribute unevenly in organic CPCMs. Herein, to overcome the drawback of uneven additives dispersion within paraffin, we proposed a novel CPCM with inorganic flame-retardant and organic form stable material, composed of Paraffin/Styrene-Ethylene-Butylene-Styrene/AmmoniumPolyphosphate/Silicon dioxide/Carbon micro-nano aggregates (PS/APP/SiO₂@C). The prepared material exhibits anti-leakage property with 99.5% mass retention after heating for 10 h at 70°C, and the smoke generation rate is only 0.01 m²·s^-1. The total heat releasing time is extended to 700 s, three times longer than that of PS. As for battery thermal management system, the maximum temperature and the temperature difference of battery module with PS/APP are 81.2°C and 5.6°C at 5 C discharge rate, respectively. In comparison, the maximum temperature and maximum temperature difference can be controlled to 58.5°C and 1.5°C, respectively, without heat accumulation during the twenty cycles. It indicates that the temperature is lower than the critical one to avoid thermal runaway of EVs. Therefore, this study presents CPCMs as an advanced thermal management approach that can enhance the thermal safety of battery packs, resulting in a significant impact on millions of drivers of EVs around the world.</p>