Nitrogen-doped Carbon Layer on Cellulose Derived Free-Standing Carbon Paper for High-Rate Supercapacitors

Free-standing porous carbon have risen to prominent electrode materials for high-rate solid-state super-capacitors, yet they are still plagued by uneconomical petrochemical feedstocks, tedious slurry-casting processes, and suboptimal performance. Herein, a dual-strategy of combining free-standing nitrogen-doped carbon nano -wire array coating and pore engineering is designed to boost the performance of cellulose-derived carbon electrodes. Polyformamide-derived carbon nanowire arrays are in-situ synthesized as N-containing carbon coatings for cellulose-based carbon fibers. More intriguingly, H2O2 activation further enhances the hierarchical porous structure. Benefiting from the synergistic effect of free-standing feature, high electrolyte compatibility, interconnected conductive fiber networks, well-developed hierarchical porous structure and stable heteroatom-doped carbon coatings, the designed electrodes possess high accessibility of electrolyte ions and effective ion/ electron transport channels. Thus, the specific capacitance reaches 275.6 F g-1 at 0.5 A g-1 for aqueous supercapacitor. The solid-state symmetric supercapacitor demonstrates the specific capacitance of 126.5 F g-1 at 0.5 A g-1 with the capacitance retention of 64.5% even when the current densities increased by 40-folds. Their promising energy density (17.5 Wh kg-1) and power density (12.3 kW kg-1) closing to the state-of-the-art biomass-derived free-standing solid-state symmetric supercapacitors. This breakthrough symbolizes a step for-ward in the advancement of biomass as high-performance electrodes for supercapacitors.