Design and preparation of Ag modified expanded graphite based composite phase change materials with enhanced thermal conductivity and light-to-thermal properties

Phase change materials (PCMs) is an excellent performance candidate for thermal energy storage and utilization. However, low thermal conductivity and low light-to-thermal conversion efficiency of PCMs are the serious limitation factors for highly efficient energy storage and photothermal conversion. In this paper, we reported a novel composite PCM based on lauric acid (LA) as the PCM supported by Ag nanoparticles modified expanded graphite (Ag-EG). The composite PCM of Ag-EG/LA possessed good energy thermal storage properties, which melted at 47.2 °C with the latent heat of 129.5 J/g at the LA maximum loading of 70.2%. Meanwhile, based on the high thermal conductivity and local surface plasma resonance effect of Ag, the composite (Ag-EG/LA) exhibits improved thermal conductivities (2.85 W/(m•K)) and high light-to-thermal energy conversion efficiency (η=81.2%). Moreover, the TGA and thermal cycles test results shown that Ag-EG/LA have good thermal stability and reliability. Hence, this novel composite of Ag-EG/LA could be potentially applicated in solar energy harvesting system and electric devices for thermal energy management.