Preparation of a composite phase change material with high thermal storage capacity using modified expanded graphite as the matrix

Abstract The inorganic hydrated salt has a potential application in thermal energy management as the phase change material. High thermal response rate and high thermal energy storage are the needs for the application. In order to prevent the leakage of inorganic hydrated salt, which is usually encapsulated in a porous matrix. Expanded graphite has been demonstrated as the effective matrix for phase change materials to ensure a high thermal response rate. In this work, modified expanded graphite proceeded with hydrophilic modification by forming SiO2 with different sizes and Na2HPO4·12H2O was encapsulated into the modified expanded graphite pores. Thermal energy storage mainly depends on the encapsulation ratio of phase change materials. This rule was confirmed by the porosity test and X-ray diffraction characterization. SiO2 particles and salt hydrates in pores of the modified expanded graphite were observed by scanning electron microscopy. The high latent heat of the composite phase change material reaches 224 J/g.