Free-standing carbon network with enhanced capacitive performance synthesized via green H2O2 activation

Carbon materials are widely used in supercapacitors due to their abundant raw materials, controllable structure, stable performance and low cost. In this work, the common commercial cotton cloth (CC) was used as the precursor to prepare hierarchical porous carbon electrodes with high capacitance performance by carbonization and H2O2 activation. The effects of H2O2 activation temperature on pore characteristics and capacitance properties of carbon networks were systematically studied and compared. The optimal sample (CC-120) exhibited the highest specific surface area (874.69 m2 g−1) and the largest micropore volume (0.31 cm3 g−1). The specific capacitance of CC-120 extended to 243 F g−1 at 0.5 A g−1, which owing to the large number of micropores and wrinkles on its surface, and the large specific surface area providing abundant active sites. CC-120 was used as electrode to prepare symmetrical supercapacitor, which displayed a specific capacitance of 116 F g−1 at 0.2 A g−1 with energy and power density of 15.9 Wh kg−1 and 24.9 kW kg−1, respectively. Under the current density of 30 A g−1, 85% of the initial capacitance was maintained after 15,000 cycles. The green and cost-effective H2O2 activation provides options for the value-added utilization of cotton cloth and other biomass derivatives.