Lamellar-Structured Graphene Aerogel-Based Phase Change Composites for Applications in Thermal Energy Management

The current repertoire of organic phase change materials (PCMs) feature low thermal conductivities, undergo facile leakage of latent heat storage media during solid–liquid phase transitions, and have weak absorption capacities, all of which limit their applications in advanced thermal energy storage systems. However, annealing graphene aerogels (AGAs), which feature a three-dimensional structure, offer a promising solution for these problems. In this work, composite PCMs were prepared by introducing lamellar-structured AGAs into polyethylene glycol (PEG). The lamellar-structured AGAs provided continuous heat conduction that improved the thermal conductivity of PEG while maintaining the shape stability of the material. Notably, despite the relatively low graphene loading, the preconstructed three-dimensional graphene aerogel framework enables continuous phonon transport pathways, resulting in a disproportionately high enhancement in thermal conductivity. Compared to pure PEG, the latent heat capacity decreased by 10.9%, and the thermal conductivity was 4.13 W·m–1·K–1, which was 15.9 times higher than that of pure PEG. The PEG/AGA series composites also exhibited strong absorbances throughout the entire UV–vis–NIR spectrum. The highest solar-thermal conversion efficiency was 96.4% when the graphene content was 1.5 vol % when illuminated under AM 1.5 simulated solar light (100 mW·cm–2). We also demonstrated that the composite PCMs could serve as thermal interface materials for electronic device cooling. Therefore, the high-performance, thermally conductive composite PCMs have excellent application value and prospects in thermal energy storage and thermal management.