Integrated Flexible Planar Supercapacitors Based on Noncarbonized Wood

Flexible planar supercapacitors have garnered significant attention as potential power supplies for wearable and portable devices. In this work, we present a flexible planar supercapacitor utilizing delignified natural wood as the substrate and polypyrrole as the electrode material. The interdigitated polypyrrole electrodes are fabricated on the substrate via vapor deposition polymerization, with the polypyrrole thoroughly embedded within the wood substrate's channels across its thickness. This design significantly enhances the areal-specific capacitance and stability of the device. The electrodes achieve an impressive areal-specific capacitance of 1903.0 mF cm^-2, while the planar-integrated supercapacitor constructed with these electrodes exhibits an areal-specific capacitance of 172.0 mF cm^-2. Benefiting from the excellent flexibility of delignified wood, three-dimensional distribution, and strong binding to the substrate of polypyrrole, the planar supercapacitor demonstrates outstanding flexibility and mechanical stability. This study demonstrates an innovative approach to utilizing porous insulating substrates for fabricating planar supercapacitors and highlights possibilities for incorporating eco-friendly wood into energy storage applications.