Percolating MXene Networks and LDH Thermal Bridges in 3D Hierarchical Polyimide Aerogels for Rapid Thermal Charging, Leakage‐Resistant Solar–Thermal Phase‐Change Storage

ABSTRACT Although phase change materials (PCMs) can help improve solar thermal efficiency and balance energy supply and demand, their practical application prospects are limited by poor stability, low thermal conductivity, and weak photothermal absorption. In this study, a cobalt–molybdenum layered double hydroxide (Co–Mo LDH)/MXene/polyimide (PI) composite aerogel (PMT) is proposed as an advanced scaffold for phase‐change composites (PCC). The PMT aerogel is fabricated via a bidirectional ice‐templating method and subsequently impregnated with paraffin (PA) under vacuum. In this hybrid framework, Co–Mo LDH regulates the pore structure, generating a hierarchical network that ensures high PA loading while suppressing leakage. MXene provides efficient thermal pathways, enhancing heat transfer. The PI backbone ensures structural integrity and mechanical stability. Compared to neat PI aerogel, the composite aerogel exhibits a 4615% increase in specific surface area and a 70.7% increase in thermal conductivity. The fabricated PCC exhibits exceptional thermal stability, with a loading rate of 91.5%, melting enthalpy of 131.6 J/g, and relative enthalpy efficiency of 95.7%. The composite achieves high photothermal efficiency by combining enhanced light‐harvesting with rapid heat transfer, which mitigates PCM drawbacks and improves energy utilization. These findings can help guide the development of PCCs tailored for thermal energy storage.