Phase Change Materials Encapsulated in Coral-Inspired Organic–Inorganic Aerogels for Flame-Retardant and Thermal Energy Storage

Phase change materials (PCMs) are considered ideal candidates for improving the efficiency of solar energy utilization because of their outstanding heat storage capacity. However, the further application of PCMs is limited by the issues of inferior shape stability, high fire hazard, and low thermal conductivity. Enlightened by the porous structure of coral in nature, a coral-like organic–inorganic graphene-modified PVA aerogel (GP) was designed as a host for PEG, resulting in a PCMs (P-GP) which has superior flame retardancy, shape stability, and solar-responsive thermal storage capacity. The thermal conductivity of P-G2.0P2.0 was significantly up, reaching 0.7545 W/(m·K), about 1.6 times that of PEG. As expected, the obtained P-G2.0P2.0 nanocomposites showed an ultrahigh thermal storage density (141.8 J) and an excellent shape stability. Additionally, the peak heat release rate and total heat release of the P-G2.0P2.0 were decreased by 37.5% and 25%, respectively, compared to those of PEG, showing superior fire safety. Due to the inorganic graphene acted as an effective light captor and molecular heated under solar light, the P-GP nanocomposites reached 50 °C within 80 s, indicating an efficient solar energy conversion, which have great potentials in solar energy storage and waste heat recovery.