Form-stable flexible composite multi-phase change material with high latent heat and enhanced thermal conductivity for thermal management

Form-stable flexible composite phase change materials (PCMs) are widely studied on the application of thermal management of batteries. Usually, the latent heat of composite PCMs is lower than that of pure PCMs due to the existence of additive materials. More composite PCMs are needed when their latent heat is too low to meet the requirements, which limits the development of the compact structure of the thermal management system. In this work, a novel paraffin (PA) -based composite multi-phase change material (m-PCM) with high latent heat was fabricated for thermal management. PA thickened by adding styrene ethylene butene styrene block copolymer (SEBS) and expanded graphite (EG) as enhanced thermal conductivity material were loaded in phase change polymer skeleton (PPS) synthesized from polyethylene glycol (PEG). One side, PPS not only played a role on preventing the leakage of paraffin as supporting material, but also provided the extra latent heat of phase change for the composite m-PCM. On the other side, SEBS was added by increasing the viscosity of PA to solve the problem of poor compatibility between the polymer skeleton and PA. Benefiting from the additional latent heat provided by PPS and the addition of EG, the composite m-PCM exhibited the phase change enthalpies as high as about 221.3 J·g−1 while ensuring the thermal conductivity as high as 1.46 W·m−1·K−1. When heated, the composite m-PCM exhibited the excellent shape-stability and flexibility. After 200 thermal cycles, the composite m-PCM performed the almost constant phase transition properties. The results demonstrate the composite m-PCM has extensive application prospects for efficient thermal management.