We prepared a series of three-dimensional graphene aerogel (3D-GA) encapsulated n-octadecane (OD) composite phase change materials (PCMs) through both solution and vacuum impregnation to ensure that a homogeneous dispersion of OD in the porous structure of 3D-GA was present. At the same time, we also investigated the micro-structure, thermal storage properties, and thermal conductivity of the composite PCMs. We used scanning electron microscopy and Fourier transform infrared spectroscopy to demonstrate that OD was encapsulated effectively in the porous structure of 3D-GA and that the composite PCMs were prepared successfully. Differential scanning calorimetry (DSC) results confirmed that the composite PCMs possess good phase change behavior, fast thermal-response rates and excellent thermal cycling stability. The melting enthalpy and crystallization enthalpy can reach 195.70 J g⁻¹ and 196.67 J g⁻¹, respectively, and have almost no change for 60 DSC thermal cycles. Temperature–time curves suggested that the composite PCMs have excellent thermal regulation properties, and their temperature can be maintained in the range of 21–27 °C for about 640 s in a heating procedure. Thermal conductivity analysis indicated that the thermal conductivities of the composite PCMs are improved significantly by the highly thermally conductive 3D-GA. All these results demonstrated that the composite PCMs possess good comprehensive properties that can be used widely in energy storage systems.

Carbon aerogels have been widely studied due to their high specific surface areas, strong adsorption capabilities and good thermal properties, which can be used to develop shape-stabilized phase change materials (PCMs). The porous framework of carbon aerogels plays a crucial role in enhancing the performance of composite PCMs. Here we report a lightweight and high strength three-dimensional (3D) carbon aerogel by using inexpensive biomass xanthan gum (XG) to eliminate the structural collapse and shrinkage observed in traditional polyimide (PI) carbon aerogels. The high stability of XG allows uniform dispersion of TiO₂ nanoparticles in the framework, endowing the carbon aerogel with high light–thermal transfer performance. PEG 6000 was encapsulated using the high strength PI/XG/TiO₂ carbon aerogel via vacuum impregnation, creating multi-functional carbon aerogel-based form-stable PCMs (CA-FSPCMs) with excellent thermal performance. The CA-FSPCMs demonstrated latent heat values up to 160.38 J g⁻¹, with excellent thermal reliability even after 100 thermal cycles. Furthermore, their light–thermal conversion and storage efficiency exceeded 94.23%, and their thermal conductivity improved up to 0.82 W m⁻¹ K⁻¹ thanks to the PI/XG/TiO₂ carbon aerogel. We also evaluated the morphology, anti-leakage performance, mechanical properties and thermal response properties of the CA-FSPCMs. The heat energy storage and release capabilities of the fabricated CA-FSPCMs are very promising for applications in temperature regulation.