Thermal management system study of flame retardant solid–solid phase change material battery

The maximum temperature, temperature homogeneity and flame retardancy of the battery module are crucial to its safe and stable operation. In this paper, a new flame retardant solid–solid phase change material is successfully prepared for the battery thermal management system. Firstly, a new solid-solid phase change material was prepared by using polyethylene glycol (PEG) as the phase change matrix and N,N'-Methylenebisacrylamide (MBA) as the cross-linking agent. Next, a flame retardant material with high thermal conductivity was prepared using microcapsule-coated ammonium polyphosphate (MFAPP) as a flame retardant, expanded graphite (EG) as a thermal conductivity additive and expanded carbon source. The experimental results show that the composite phase change material with 19% MFAPP can provide good thermomechanical properties while having excellent flame-retardant properties. Its Limiting oxygen index (LOI) can reach 32.6 and pass the vertical combustion V-0 grade test. It also maintains good shape stability when heated at 250 °C for 30 min. In addition, the charging and discharging the battery module using CPCM as the heat dissipation medium and air cooling is compared. The results show the maximum temperature of the module is 18.83 °C lower at 2C discharge rate and the maximum temperature difference of the cycle is 7.511 °C lower.