Highly efficient thermal energy storage enabled by a hierarchical structured hypercrosslinked polymer/expanded graphite composite

摘要

Thermal energy storage and release is of great interest in solving mismatch between energy supply and demand. Latent heat capacity and thermal conductivity are the two main factors needed to be considered for practical applications of shape-stabilization phase change materials (PCMs). Herein, a hierarchical hypercrosslinked polymer (HCP)/expanded graphite (EG) composite, could fulfill both superior high specific surface area and thermal conductivity requirements, was synthesized via an in-situ growth protocol in the pore of expanded graphite. It was suggested that a synergistic working mechanism existed between EG and HCP, where EG acted as a macro pore system for the inhibition of HCP aggregation, which could thus enable a better encapsulation rate of PCM in HCP; while HCP played a role for the highly efficient encapsulation owing to its high specific surface area. Hierarchical structured HCP/EG composite exhibits promising performance when used as a PCM supporting material that the encapsulation rate of the composite could reach to 89.4% without observation of any leakage, and the thermal conductivity is up to 3.7 W•m~(-1)•K~(-1). Additionally, the prepared PCM composites display a superior heat energy storage and light-to-thermal conversion performance over pure paraffin, indicating its great potential to be used in thermal energy storage.