Abstract: Abstract In response to the issues of high carrier mass and insufficient thermal conductivity in existing composite phase change materials, this study prepared Graphene Oxide (GO) colloidal solution using an improved Hummers method and further fabricated them into Sponge-Like Graphene Oxide (SLGO) with a porous structure through freeze-drying technology. Utilizing SLGO as the carrier and Polyethylene Glycol (PEG) as the phase change medium, the SLGO/PEG composite phase change material was prepared by combining vacuum impregnation with ultrasonic-assisted processing. Characterization techniques such as Ultraviolet-Visible (UV-vis) spectroscopy, Scanning Electron Microscopy (SEM), Fourier-Transform Infrared (FTIR) spectroscopy, X-ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), and laser thermal conductivity analysis were comprehensively applied to investigate the microstructure and thermo-physical properties of the composite phase change material. The results indicate that the effective filling of PEG in the SLGO pores and the adsorption on the layers not only significantly increased the interlayer spacing of graphene but also formed a stable interaction with the oxygen-containing functional groups on the SLGO surface through hydrogen bonding. The composite phase change materials demonstrated a high latent heat value of over 179 J·g?1 and a crystallization enthalpy of 172.7 J·g?1, with a crystallinity of over 90%, highlighting its excellent phase change energy storage performance. Most importantly, the addition of SLGO significantly enhanced the thermal conductivity of the material, reaching 0.98 W·m?1·K?1 when the mass fraction of SLGO was increased to 1%. Furthermore, the shape-stabilization effect of the composite phase change material was significantly strengthened with the increase in SLGO content.

Key words: Composite phase change material, Sponge-like graphene oxide, Polyethylene glycol, Latent heat value, Thermal conductivity