Highly thermal conductive phase change composites containing Ag-welding graphene framework with excellent solar-thermal conversion and rapid heat transfer ability

The anisotropic three-dimensional (3D) Ag-welding graphene framework prepared by unidirectional ice-templating freezing casting, was used to encapsulate polyethylene glycol (PEG) as phase change material (PCM) composite in this work. Arising from the decreased interfacial thermal resistance (ITR) in graphene skeleton by Ag-welding and the vertically oriented graphene skeleton as phonon transfer paths, the obtained PCM composite exhibited a high thermal conductivity of 4.3 W m −1  K −1 at graphene loading of ∼6.25 vol%, which improved significantly the heat transfer rate during the heat charging/discharging processes. Meanwhile, the graphene framework gave the PCM composite an excellent solar-thermal conversion ability, which could be further enhanced by Ag-welding strategy. Besides, the 3D porous framework with huge capillary and surface tension forces effectively improved the shape stability and avoided leakage of PCM, with meanwhile remaining high energy storage capacities (147.4–165.9 J g −1 ). Therefore, the Ag-welding 3D graphene framework reveals the high potential to encapsulate PCM using in solar-thermal conversion field.