Highly stable solid-solid phase change materials for battery thermal management systems

Phase change material is an effective battery thermal management technology, which can reduce the temperature of the battery module and maintain the temperature uniformity of the module. In this study, a highly stable solid-solid phase change material (SSPCM) was prepared through copolymerization using non-toxic, safe, and high-enthalpy polyethylene glycol (with molecular weights of 3000, 4000, and 6000) as the matrix. Polyethylene glycol 4000 was identified as the most suitable thermal management material, considering its packaging effect, heat storage capacity, and phase change temperature. The study utilized Materials Studio 2020 simulation software to investigate the micro-mechanism between carbon nanotubes and SSPCM. The interaction energy and mechanical properties of different hydroxylated carbon nanotubes (CNT-OH) with SSPCM were compared, and it was found that 5 % hydroxylated carbon nanotubes were the most effective. A composite solid-solid phase change material (SSPCM-CNT) with high thermal conductivity and stability was then prepared by incorporating CNT-OH. A battery thermal management system was constructed to test the performance of SSPCM-CNT, and the results demonstrated its excellent thermal management ability. Even under high discharge rates (5 C), the system with SSPCM-CNT effectively addressed temperature non-uniformity, maintaining the system temperature within 50 °C (specifically 48.92 °C) and the temperature difference within 2.5 °C.