Form-Stable phase change composites based on porous carbon derived from polyacrylonitrile hydrogel

How to improve thermal conductivity as well as energy conversion efficiencies and to prevent melting leakage of solid–liquid phase change materials (PCMs) has been the essential challenges for the development of energy storage technology for storing a tremendous amount of waste heat and renewable and sustainable solar energy. Here, we reported the fabrication of high-performance form-stable composite PCMs (CPCMs) using the thermal conductive 3D-HPC carriers produced from the pyrolysis of porous polyacrylonitrile (PAN) copolymer hydrogels to confine the polyethylene glycol (PEG) PCMs. The porous 3D network PAN gel templates generate hierarchical cavities with micro/mesopores on the skeleton after pyrolysis which provides more space as well as the capillary adsorption and chemical interaction for the storage of PEG PCMs. The 3D-HPC/PEG CPCMs show high energy storage density (as high as 173.5 J g−1), high phase transformation efficiency and excellent thermal cycle stability. The carbon scaffold highly enhanced the thermal conductivity of CPCMs ∼ 10 times of the pure PEG and ensured its optical/electric-thermal energy conversion performance. This study demonstrates a facile, efficient and green way to fabricate hierarchical porous carbon with controllable porosity and degree of graphitization for improving the energy storage density, thermal conductivity, shape stability and energy conversion performance of PCMs.