Enhanced thermal conductivity and photo-to-thermal performance of diatomite-based composite phase change materials for thermal energy storage

Abstract With abundant reserves and natural high porosity, diatomite has been a candidate material in the matrix of composite phase change materials (PCMs). Diatomite-based composite phase change materials (PCMs) were fabricated by blending lauric acid-stearic acid (LA-SA) and diatomite matrix via the vacuum impregnation method. To improve the thermal conductivity and photo-to-thermal performance, the purified diatomite (Dp) was designed by a hydrothermal reaction to synthesize MnO2-decorated diatomite (Dp-M). Scanning electron microscopy and X-ray photoelectron spectroscopy analysis verified the existence of MnO2 in the diatomite surface. The LA-SA/Dp-M2 with 42.2% loadage of LA-SA melts at 26.81 °C and releases 66.74 J g−1 of heat, and the thermal conductivity was increased by 89.5% due to the addition of MnO2. Particularly, LA-SA/Dp-M2 has the best photo-to-thermal conversion ability compared with pure LA-SA and LA-SA/Dp, making it the potential to use solar energy efficiently. Meanwhile, LA-SA/Dp-M2 with higher thermal conductivity has an excellent performance in the heat storage/release process and transient temperature response. Therefore, the prepared composite possesses a potential application for thermal energy storage in the building envelope.