Lignin-derived 3D porous graphene on carbon cloth for flexible supercapacitors

In this work, we reported a new method to fabricate flexible carbon-based supercapacitor electrodes derived from a commercialized and low-cost lignin. The fabrication process skips traditional stabilization/carbonization/activation for lignin-based carbon production. Also, the process reported here was green and facile, with minimum solvent use and no pretreatment required. Characterization of the lignin showed that it has common properties among all types of lignin. The lignin was impregnated on carbon cloth and then subjected to direct laser writing to form the desired electrodes (LLC). The results showed that lignin was successfully bonded to carbon cloth. The LLC has a good porous carbon structure with a high I _G/I _D ratio of 1.39, and a small interlayer spacing d ₀₀₂ of 0.3436 nm, which are superior to most of the reported lignin-based carbons. Although not optimized, the fabricated LLC showed good supercapacitance behavior with an areal capacitance of 157.3 mF cm^-2 at 0.1 mA cm^-2. In addition, the superior flexibility of LLC makes it a promising electrode that can be used more widely in portable devices. Conceptually, this method can be generalized to all types of lignin and can define intriguing new research interests towards lignin applications.