Renewable Flexible Supercapacitors Based on Lignin Electrodes and Electrolytes

Lignin which is the second most abundant natural polymer is found to be the most promising candidate for environmentally benign energy storage materials because of its high carbon content, favorable functionality, biodegradability and economic feasibility. Also, the valorization of lignin (to produce something useful like materials, energy or chemicals) is considered as an effective way to minimize our reliance on depletion non-renewable energy sources and to explore novel feedstock for energy storage/conversion device. Therefore, in the quest for renewable and highly efficient energy storage devices, we have prepared lignin-based porous freestanding electrodes and chemically crosslinked hydrogel electrolytes. Ultimately we have fabricated all-solid-state flexible supercapacitor exhibiting a maximum energy density and power density of 4.49 Wh kg -1 and 2.63 kW kg -1 , respectively by integrating the lignin-PAN nanofiber electrodes and lignin hydrogel electrolytes. Our approach of using wood biomass based renewable materials for the flexible energy storage devices is expected to contribute to the expansion of sustainable chemistry.