Development of carbon-coated aluminosilicate nanolayers composite shape-stabilized phase change materials with enhanced photo-thermal conversion and thermal storage

Latent heat thermal energy storage (LHTES) system that centers on organic phase change materials (PCM) is regarded as an efficient strategy for the utilization of solar energy. The leakage problem and insensitivity to the sunlight of organic PCM significantly limit the large-scale application in the solar energy storage field. In the current study, a composite shape-stabilized phase change material (ss-PCM) for solar energy utilization was fabricated by incorporating stearic acid (SA) into the carbon-coated aluminosilicate nanolayers developed through intercalation of kaolinite with potassium acetate and then calcination. The resulting composite ss-PCM without leakage possesses excellent encapsulation ability (63.8%) and high latent enthalpy (132.0 J/g), which are ascribed to the higher specific surface area and pore volume of the carbon-coated aluminosilicate nanolayers, and good compatibility. The photo-thermal conversion efficiency of the final composite ss-PCM is up to 92.1%. After 500 heating-cooling cycles, the number of thermal cycles does not show an apparent effect on the enthalpy of the composite ss-PCM, implying its outstanding thermal cycle stability. The mechanism of leakage proof and photo-thermal conversion performance enhancement of composite ss-PCM were explored. The leakproof ability of composite ss-PCM is not only related to the solid capillary force and surface tension of carbon-coated aluminosilicate nanolayers but also the strong chemical bond between SA molecules and these nanolayers. The carbon layers of the supporting material provide an excellent light absorption property. Hence, this work may offer a new idea for designing and constructing the clay mineral (kaolinite) with a special nanolayer structure for preparing composite ss-PCM with superior photo-thermal conversion and solar energy storage capacity.