Ultra‐Compact Cellular Structured Bio‐Carbon Aerogels Supported <scp>PCM</scp> for Exceptional Thermal Insulation and Radiation Shielding for Space Applications

Integrating phase change materials (PCM) into thermal insulation materials offers a novel approach to aerospace thermal protection. Herein, we used waste biomass as a template; by selecting the appropriate carbonization temperature, we obtained carbon aerogels (CCA) with extremely high porosity (95.8%) and high pore volume. After encapsulating PEG2000, we achieved high enthalpy (137.79 J g −1 , 91% of pure PEG2000) and low thermal conductivity (0.137 W (m·K) −1 , 45% of pure PEG2000). Thanks to the rich hierarchical nano‐micro porous structure of CCA and the high latent heat of PEG2000, CCA/PEG exhibits excellent thermal insulation properties (under a heating temperature of 131 °C, the material takes 1400 s to reach its maximum temperature and can be maintained below 65 °C) and cycle performance. Additionally, irradiation destroyed the structure of CCA/PEG, leading to the degradation of PEG and the formation of other carbonyl‐containing compounds, which decreased its latent heat (4.2%) and thermal conductivity (16.1%). However, the irradiation‐resistant CCA, acting as a protective layer, minimizes the impact of irradiation on PEG2000. Instead, irradiation enhances the hierarchical porous structure of the material, ultimately improving its thermal insulation performance. CCA/PEG has potential application prospects in thermal protection and aerospace and is a strong competitor for high‐efficiency thermal insulation materials.