Superelastic wood‐based nanogenerators magnifying the piezoelectric effect for sustainable energy conversion

Abstract In the quest for sustainable energy materials, wood is discovered to be a potential piezoelectric material. However, the rigidity, poor stability, and low piezoelectric properties of wood impede its development. Here, we obtained a superelastic roasted wood nanogenerator (RW‐NG) by unraveling ray tissues through a sustainable roasting strategy. The increased compressibility of roasted wood intensifies the deformation of cellulose microfibrils, significantly enhancing the piezoelectric effect in wood. Roasted wood (15 × 15 × 15 mm³, longitudinal × radial × tangential) can generate a voltage and current outputs of 1.4 V and 14.5 nA, respectively, which are more than 70 times that of natural wood. The wood sample can recover 90% of its shape after 5000 compressions at 65% strain, exhibiting excellent elasticity and stability. Importantly, roasted wood does not add any toxic substances and can be safely applied on the human skin as a self‐powered sensor for detecting body movements. Moreover, it can also be assembled into self‐powered wooden floors for energy harvesting. These indicate that roasted wood has great potential for sustainable sensing and energy conversion.