Anisotropic Rotunda‐Shaped Carboxymethylcellulose/Carbon Nanotube Aerogels Supported Phase Change Materials for Efficient Solar‐Thermal Energy Conversion

Abstract For the drawbacks of phase change materials such as poor shape stability and weak solar‐thermal conversion ability, a rotunda‐shaped carboxymethylcellulose/carbon nanotube aerogel (CA) with three‐dimensional network was constructed by freeze casting with a special mold, and then impregnated with polyethylene glycol (PEG) in this work. The PEG/CA had an enthalpy of 183.21 J/g, and a thermal conductivity of 0.324 W m −1 K −1 , which was 57 % higher than the pure PEG. The ability of PEG/CA to convert solar energy to thermal energy was a positive correlation between the inclusion of CNTs and the composite material‘s thermal conductivity. Under simulated sunlight, its solar‐thermal conversion efficiency reaches 94.41 %, and after 10 min of irradiation, the surface temperature can reach 65 °C and the internal temperature can reach 44.67 °C. This rotunda‐shaped PEG/CA is promising for the efficient use of renewable solar energy due to its strong solar‐thermal conversion and thermal storage capabilities.