Multi‐Scale Synergistic Networks Enable Wood‐Derived Carbon Aerogels With High Compressibility and Temperature Thermal Insulation

Carbon aerogels enable exceptional thermal insulation at extreme temperatures, yet their inherent brittleness and lack of mechanical resilience constrain practical load-bearing applications. To address this strength-resilience trade-off, we report a sustainable alternative: A wood-derived carbon aerogel that turns ordinary wood into a carbon material with high-temperature thermal insulation capability under inert atmospheres. This is achieved by using a delignified wood carbon sponge scaffold infiltrated with phenolic carbon aerogels of variably controlled particle sizes (tunable via resorcinol/chitosan ratio adjustment). The natural cellulose skeleton provides elastic buckling capacity, while the multisized phenolic fillers reinforce cell walls and inhibit crack propagation, forming a synergistic load-bearing network. The WCS-CA50 sample exhibits a room-temperature thermal conductivity of 0.037 W/(m·K), a thermal conductivity of 0.13 W/(m·K) at 1100°C, and a compressive stress of 0.517 MPa at 50% strain, indicating a balanced combination of thermal insulation and mechanical performance. This strategy utilizes renewable wood biomass as the primary structural matrix, offering a renewable route to fabricating carbon-based thermal protection systems without reliance on synthetic fiber reinforcements.