Thermally conductive phase change composites for efficient medium-temperature solar thermal storage

Global industrial heat constitutes approximately two-thirds of the energy demand within the industrial sector. The utilization of Phase Change Composites (PCCs) for storing solar energy presents a promising solution to decarbonize industrial heat consumption and the significant disparity between thermal energy demand and supply. However, low thermal conductivity phase change materials and heat losses make it difficult for PCCs to reach the temperatures required (80–250 °C) by industry applications. This work proposed a method to reduce the area of photothermal surfaces through applying light concentration techniques and a directional thermo-conductive framework, with the aim of enhancing heat storage and minimizing heat loss. Graphene skeletons exhibiting controllable thermal conductivity pathways were constructed through ice-template assembly. Furthermore, the photothermal conversion surface area of PCCs was reduced by 93.75 %. The PCC8, with a graphene skeleton mass ratio of 3.34 %, showed a phase transition temperature of 119 °C, latent heat of 327.6 J/g, and vertical thermal conductivity of 9.85 Wm −1 K −1 . An integrated photothermal storage device was constructed and heated by a Fresnel lens to concentrate the 1000 W/m 2 light from a solar simulator, and the heat storage efficiency was 69.2 %. This research had the potential to advance solar-thermal energy conversion and storage in the medium-temperature range. • An actinomorphic graphene aerogel directional thermo-conductive framework was prepared by the ice-template method. • The 119 °C phase change composites have been fabricated, exhibiting superior thermophysical properties. • Theoretical verification of the feasibility of achieving medium-temperature thermal storage by focusing sunlight • An integrated photothermal storage device achieved a heat storage efficiency of 69.2 %