Experimental and numerical investigation of a battery thermal management system using a novel EVA-based thermal-induced flexible composite phase change material

The easy leakage, low thermal conductivity and poor flexibility of phase change materials (PCMs) limit their application in battery thermal management systems (BTMS). To address these problems, a novel form-stable flexible composite phase change material (CPCM) with ethylene-vinyl acetate (EVA), expanded graphite (EG) and paraffin (PA) is designed and applied to battery module. EVA with a skeleton structure is employed as supporting material and EG is the thermal conductive filler. The effects of EVA content on the microstructure and cooling performances of CPCM are investigated under different cooling conditions. The temperature distribution of battery module and the liquid fraction of CPCM were visualized by numerical simulation. The results show the addition of EVA greatly improves the antileakage and shape stability properties of CPCM. When the content of EVA is higher than 30 wt%, the physical shape of CPCM remains nearly unchanged after 75 times of thermal cycling. The maximum temperature of battery module with CPCM is 49.2 °C at 4C discharge rate, which is reduced by 14.2 °C in comparison with that under natural convection. Furthermore, the maximum temperature difference of the battery module is kept within 5 °C during the 4C charge-discharge cycling tests.