Scalable and Sustainable Approach toward Highly Compressible, Anisotropic, Lamellar Carbon Sponge

Here, we demonstrate that wood can be directly converted into a highly compressible wood carbon sponge (WCS) by lignin and hemicellulose removal followed by carbonization. The significant removal of lignin and hemicellulose via chemical treatment destroys the thin cell walls of natural wood, giving rise to a lamellar structure with numerous stacked arched layers. The lamellar structure can be well preserved even after high-temperature carbonization. Interestingly, such a lamellar structure renders a high compressibility up to 80% and high fatigue resistance of 10,000 compression cycles at 50% strain. Further experimental and modeling studies reveal that WCS can accommodate substantial compression from the bending and flattening of the curved layers, resulting in minimum stretching of individual layers. The WCS also demonstrates a sensitive electrical conductivity change upon compression. Using this lamellar sponged structure and the excellent mechanical and electrical properties of WCS as an example, we demonstrate the great potential of WCS for highly sensitive strain sensors.