Graphene aerogel based/polyethylene glycol composite thermal storage materials with high enthalpy and low thermal conductivity for space thermal protection

Abstract

Novel thermal insulation materials that integrate lightweight, latent heat storage, and sensible heat storage play a crucial role in advancing aerospace thermal insulation materials. However, high-energy irradiation in the space environment can affect the structure of aerospace thermal insulation materials, thus impacting their thermal insulation performance. We first simulate and screen the existing non-metallic thermal insulation aerogels to identify graphene aerogel (GA) as having the best irradiation resistance. Then we prepare GA with hierarchical porous and low thermal conductivity characteristics through hydrothermal reduction and freeze-drying / supercritical CO₂ drying. Subsequently, we load polyethylene glycol (PEG) in the skeleton to obtain graphene aerogel composite (GAC). GAC possesses high latent heat (156.80 J·g⁻¹), low thermal conductivity (0.29 W·m⁻¹·K⁻¹), excellent long-term thermal insulation performance, microwave absorption performance (RL_min can reach −50.30 dB), and mechanical strength (7.09 MPa). Finally, we simulate a high-energy irradiation field using Co⁶⁰ irradiation experiments to verify the irradiation resistance of GAC. The results indicate that high-energy irradiation may break and modify some of the molecular chains of PEG. The thermal stability and thermal conductivity of the composite remain basically unchanged, the latent heat decreases slightly, and the supercooling degree decreases significantly. GAC shows potential application prospects in aerospace thermal protection and energy storage fields.