Engineering nanocellulose/graphene hybrid aerogel for form-stable composite phase change materials with high phase change enthalpy for energy storage

Lightweight cellulose nanocrystals/graphene hybrid aerogels (CGA) with highly porous and parallelarrangement three-dimensional networks were fabricated via freezing-thawing under natural drying condition, which were used as scaffolds to prepare PEG@CGA composite phase change materials (PCG PCMs) by vacuum impregnation. Relative to PEG@GA (PG), PEG was tightly anchored into CGA due to capillary force and strong hydrogen bonding, and PCG kept the shape stability without any leakage upon melting point of PEG even under compression. The latent heat storage energy of PCG attained 183.2 J/g, which was 94.6% of that of pure PEG, still maintaining 89.7% even after 100 heating-cooling cycles. Moreover, PCG exhibited a high thermal conductivity, 175% and 60% higher than that of PEG and PG due to reduction of interfacial thermal resistance. Such strategy exhibits a promising perspective to obtain composite phase change materials with excellent shape stability, energy storage capacity and thermal conductivity for applications in energy storage.