Light-thermal-electric energy conversion based on polyethylene glycol infiltrated carboxymethylcellulose sodium-derived carbon aerogel

Organic phase change materials (PCMs) based latent heat energy storage and release media are promising candidate for the utilization of thermal energy from the solar irradiation. However, the poor photo-absorption ability and intrinsic poor thermal conductivity of organic PCMs results in leakage problem and slow thermal energy charging/discharging rates, which makes them unable to utilize directly for thermal energy conversion. Herein, we fabricate a three-dimensional (3D) carboxymethylcellulose sodium-derived carbon aerogel (CCA) and organic PCM composite with highly efficient light-thermal-electric energy conversion and storage capability. The porous and interconnected CCA15 is prepared firstly through crosslinking, freeze-drying and pyrolysis of carboxymethylcellulose sodium-based hydrogel. The organic PCM of polyethylene glycol (PEG) is then impregnated into the porous CCA15 via vacuum infiltration technique to obtain the PEG/CCA15 composite that had good form-stability, fusion enthalpy at 185.3 J/g, thermal conductivity at 0.351 W/m·K, and reasonable light-thermal energy conversion efficiency of 71.5% under solar irradiation with intensity of 215 mW/cm2. Further results proved that the PEG/CCA15 composite exhibited light-electric energy transformation, storage, and release abilities. The stored thermal energy in the PEG/CCA15 composite absorbed from irradiated solar light could release to power an electronic fan to rotate continuously for 5 min when the solar light was turned off. Hence, the PEG/CCA15 composite has great potential for sustainable solar energy utilization.