A novel room temperature flexible composite phase change material based on thermoplastic polyamide elastomer and its thermal properties analysis

Abstract

Phase change material (PCM) has the characteristics of high latent heat, wide temperature range, and good thermal stability, which makes phase change cooling an excellent passive cooling technology, and it is worth exploring in the field of battery thermal management. However, common phase change materials have low thermal conductivity, high rigidity, and easy leakage of PCM at room temperature, which greatly limits their application. In order to solve the above problems, a new flexible composite phase change material (FCPCM) was prepared by physical melting and mixing methods, using paraffin wax (PA) as the phase change substrate, polyamide thermoplastic elastomer (TPAE) as the flexible support material, hexagonal boron nature (h-BN) as the first thermal conductivity additive, and expanded graphite (EG) as the second thermal conductivity additive. The shape stability, microscopic morphology, chemical characteristics, thermal properties, flexibility characteristics, thermal shape memory characteristics, and thermal cycle stability of FCPCM were further characterized. The results show that TPAE can not only prevent the leakage of PA but also give FCPCM heat-induced flexibility so that the composite phase change material has flexible properties at room temperature. Compared with a single thermal conductivity agent, the mixed thermal conductivity of h-BN and EG can greatly improve the thermal conductivity of FCPCM. When the thermal conductivity additive content is 15 % (h-BN = 7.5 %, EG = 7.5 %), the thermal conductivity of FCPCM is 0.51 W/mK, and the thermal conductivity is 255 % of pure PA. Finally, the performance of FCPCM with different heat transfer agent content was optimized, and the selected FCPCM samples were applied in single-cell thermal management. The results show that when the battery discharge rate is 2C, 3C, and 4C, the maximum temperature of the battery is reduced by 6.09 ℃, 6.99 ℃, and 7.56 ℃, respectively, compared with pure PA.