Lightweight and Superelastic Wood Carbon Sponges Enabled by Wood Cell Wall Reconfiguration

Elastic wood carbon sponges have gained increasing momentum due to their combination of compressive elasticity, wood orientation structure, and carbon nature. However, the pursuit of lightweight and superelasticity in these sponges remains a significant challenge, as their boundaries are constrained by the solidified wood cell walls. Here, an innovative "stripping-expansion-carbonization" strategy is proposed for producing wood carbon sponges with low density and superelasticity via breaking the spatial confinement of the original cell wall. This strategy integrates the removal of non-skeletal components from cell wall, the formation of bubble-assisted lamellar structure, and a high-temperature carbonization process. The resultant expanded wood carbon sponges (EWCS) demonstrate a low density of 14.18 ± 1.07 mg cm-3, temperature-insensitive superelasticity, and reliable cycling stability. Additionally, the incorporation of the lightweight, electrical conductivity, and superelasticity nature endows EWCS with remarkable versatility, enabling applications such as pressure sensor for monitoring human movement, tunable electromagnetic interference shielding, and efficient and recyclable oil-water separation. This strategy realizes the layer-wise reconfiguration of the solid wood cell structure, providing a new design route for engineering wood carbon sponges.