Hierarchical porous carbon derived from eucalyptus-bark as sustainable electrodes for high-performance solid-state supercapacitor
We report the synthesis and characterization of a novel activated carbon derived from waste eucalyptus bark through chemical and physical activation processes to use as potential electrode for symmetric electrical double layer capacitors (EDLCs). A porous polymer film prepared by simple phase-inversion method and activated by an ionic liquid electrolyte has been used as a flexible, high ion-conducting, mechanically and electrochemically stable electrolyte for the EDLCs. The use of waste eucalyptus bark to produce activated carbon (AC) with a straightforward activation process, and a simple phase-inversion method to produce porous polymer electrolytes (PPEs), make possible the preparation of ecofriendly, safe, and flexible EDLCs. The derived AC powder, possesses a hierarchical porous interior having micro- and meso-porosity. EDLC, constructed using the optimized AC, shows high specific capacitance of 155 F g-1, and offers better rate capability than commercial AC-based device. EIS studies reveal superior charge-transfer characteristics of optimized AC electrodes, as compared to the commercial AC. Galvanostatic charge-discharge measurements highlight the high specific energy and maximum power (32.8 Wh kg-1 and 57 kW kg-1, respectively) of the optimized AC based EDLC. This device maintains its performance for at least 10,000 charge-discharge cycles with high (96%) capacitance retention.