Cellulose/graphene aerogel supported phase change composites with high thermal conductivity and good shape stability for thermal energy storage

As phase change composites, high thermal conductivity, large latent heat of fusion and good shape stability are all required for practical applications. By combining defect-free graphene nanoplatelets (GNPs) and microcrystalline cellulose, lightweight cellulose/GNP aerogels are fabricated and their highly porous but strong three-dimensional networks benefit the encapsulation of polyethylene glycol (PEG) and prevent the leakage of PEG above its melting point. Phase change composites are prepared by vacuum-assisted impregnating of PEG into the cellulose/GNP aerogels, which exhibit high thermal conductivity, good shape stability and high latent heat of fusion. Even compressed upon the melting point of PEG, the phase change composites keep their shapes stable without any leakage. With only 5.3 wt% of GNPs, the composite exhibits a high thermal conductivity of 1.35 W m−1 K−1, 463% higher than that of the composite without GNPs. The highly porous cellulose network and the low loading of highly thermally conductive GNPs are responsible for the high loading of PEG in the composite with a satisfactory latent heat of fusion of 156.1 J g−1.