Preparation of graphite nanoplatelets 3D porous skeleton and its application as supporting material for form-stable phase change materials with high thermal storage capacity and excellent photothermal conversion efficiency

Form-stable phase change materials (FSPCMs) can be applied in a lot of heat-related fields. The properties of FSPCMs are largely depended on the supporting material. In this study, a novel 3D porous skeleton with graphite nanoplatelets (GNPs) as the construction element was prepared by simultaneously “welding” and “bonding” the adjacent GNPs with the help of ice-template method and heat treatment. Investigations on the preparation mechanism of the 3D porous skeleton revealed that cellulose and epichlorohydrin crosslinked the GNPs to build the preliminary 3D network gel at first. They were then carbonized to form amorphous carbon welding layer and weld the adjacent GNPs to form a stable 3D porous skeleton with the help of the inter-nanoplatelets bonds. The prepared GNPs 3D porous skeleton was then applied to absorb erythritol (ET) to prepare FSPCMs with very high latent heat storage capacity and excellent photothermal conversion efficiency. The encapsulation ratio of HT-ECG4/ET could attain 91.23 % with a melting enthalpy of 318.5 J/g and a photothermal conversion efficiency of 93.06 %. Besides, the supercooling of ET in the FSPCMs was greatly suppressed and the thermal conductivity was also improved. Meanwhile, the FSPCMs also showed good thermal reliability within 100 melting/crystallization cycles.