Three-Dimensional Interpenetrating Network Phase-Change Composites with High Photothermal Conversion and Rapid Heat Storage and Release

Solar thermal energy conversion and storage have gained more attention for solving energy crisis and environment issues. Phase-change materials with excellent thermal conductivity, high photothermal conversion efficiency, rapid heat storage and release, and good stability are required for solar thermal applications. In this study, three-dimensional (3D) interpenetrating network phase-change composites are fabricated by taking graphene-oxide (GO) aerogel (GA) containing a small amount of carbon nanotubes (CNTs) and carbon spheres (CSs) as support materials and vacuum impregnation melting polyethylene glycol (PEG) as the phase-change material. The 3D structure and abundant functional groups greatly improve the stability of phase-change composites. The addition of CNTs and CSs greatly increases the thermal conductivity and photothermal conversion capability of PCMs. Compared with pure PEG, thermal conductivity is increased by 181.58%, and photothermal conversion efficiency reaches 89.3%. Simulated results also confirm that GA-based phase change composites exhibit better thermal conductivity. Less thermal conductivity fillers and more phase-change material (96.4%) exhibit excellent thermal conductivity, high photothermal conversion efficiency, and a greater energy-storage density. The 3D phase-change composites are also applied for thermoelectric generation and show a stable output voltage of 35 mV for 300 s after removing the light source. The 3D interpenetrating network form-stable phase change composites based on black GA shows broad prospects in solar thermal energy applications.