Flexible solid-solid phase change materials with high stability for thermal management

Phase change materials are considered as a promising technology to solve problems such battery thermal management. However, during the process of charging and discharge, the migration of microscopic components in PCM and the brittle fracture caused by high rigidity of PCM will hinder the application of PCM in the thermal management field. In this paper, a polyurethane (PU) phase change material was prepared, and by weighing the relationship between thermal storage capacity and mechanical properties of PCM, PU4000 was considered to be the best choice with latent heat and strain of 98.8 J/g and 10%. In addition, the interfacial interaction of carbon nanotubes (CNT) and hydroxylated carbon nanotubes (CNT-OH) with the PU was analyzed at the microscopic scale, and the results showed that CNT-OH has stronger interfacial binding energy with the phase change matrix. Therefore, CNT-OH was used to improve the heat transfer performance of PU4000. The thermal conductivity of the composites reached 1.3 W/(m·K) at 5% CNT-OH content. At 2C discharge rate, the phase change material keeps the maximum temperature and maximum temperature difference of the battery module within 50 and 2 °C.