Renewable flexible supercapacitors based on all-lignin-based hydrogel electrolytes and nanofiber electrodes

In the quest for renewable and highly efficient energy storage devices, all-lignin-based flexible supercapacitors are fabricated by integrating chemically cross-linked lignin hydrogel electrolytes with electrospun lignin/polyacrylonitrile nanofiber electrodes. The cross-linked networks of lignin-based hydrogel electrolytes show high ionic conductivity and mechanical integrity, whereas the free-standing flexible composite electrode achieves outstanding charge storage capability and kinetics arising from interconnected porous channels. The resulting devices demonstrate a high capacitance of 129.23 F g^-1 and capacitance retention of 95% over 10000 cycles as well as flexibility and durability under diverse bending angles. Moreover, these renewable flexible supercapacitors deliver a maximum energy and power density of 4.49 W h kg^-1 and 2.63 kW kg^-1, respectively.