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

Abstract

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.