Core–shell-like structured graphene aerogel encapsulating paraffin: shape-stable phase change material for thermal energy storage

Abstract

The development of energy storage materials is critical to the growth of sustainable energy infrastructures in the coming years. Here, a composite phase change material (PCM) based on graphene and paraffin was designed and prepared through a modified hydrothermal method. Graphene oxide sheets were reduced and self-assembled into three-dimensional graphene aerogels consisting of numerous hollow graphene cells, and paraffin was simultaneously encapsulated into the cells in the form of micrometer-scale droplets during the hydrothermal process. The resulting core–shell-like structured, composite PCM exhibits a high encapsulation ratio of paraffin, large phase change enthalpy, and excellent cycling performance. Due to the unique encapsulated structure and continuous graphene network in the matrix, such a composite PCM holds a good shape-stable property, which prevents the leakage of paraffin above its melting point. In addition, it inherits the intrinsic thermally and electrically conductive nature of the embedded graphene, and thus shows enhanced thermal and electrical conductivity compared to pure paraffin. This novel composite PCM can realize efficient thermal energy storage and demonstrates the potential to be directly used as an actual thermal storage device without containers.