No abstract

Organic phase change materials (PCMs) with high enthalpies are ideal for heat storage and release, which are expected to promote the utilization of thermal energy and mitigate energy shortage. However, the inherent inferior light absorbance, poor thermal conduction, and weak shape stability of common organic PCMs severely restrict the absorption, conversion, and utilization of solar energy. Herein, high-quality anisotropic graphene aerogels derived from pre-oxidized polyacrylonitrile (OPAN)/graphene oxide (GO) components are designed for the first time by unidirectional freezing, freeze-drying, carbonization, and graphitization at 2800 °C. The GO component efficiently induces the orientation and graphitization of the OPAN component and converts it to graphitic carbon during graphitization. After vacuumassisted impregnation with paraffin, an optimal thermally conductive phase change composite (PCC) possessing an enhanced through-plane thermal conductivity of 4.36 W m −1 K −1 at a low graphene content of 1.07 vol %, improved shape stability, and a fairly high latent heat retention of 99.7% is obtained. Thanks to the remarkable light absorbance and solar−thermal conversion capacities, the PCC is efficient in applications of solar−thermal−electrical energy conversion with a competitive output voltage of 1181 mV under irradiation of a simulated solar light of 5 kW m −2 . By releasing the thermal energy stored in the PCC, it can continue to power a LED lamp even after solar light irradiation is stopped. This work provides a feasible and efficient methodology for fabricating thermally conductive PCCs with high latent heat retention for application of efficient solar−thermal−electrical energy conversion.