Green H2O2 activation of electrospun polyimide-based carbon nanofibers towards high-performance free-standing electrodes for supercapacitors

Free-standing carbon nanofibrous membranes are prepared by carbonization and H2O2 activation of electrospun polyimide nanofibrous membranes. The green and facile H2O2 activation method not only regulates the pore structure of carbon nanofibers but also introduces rich oxygen species, rendering a hierarchically porous and heteroatom-doped carbon electrode for supercapacitors. The optimal electrode (PI800-8) shows a high specific capacitance of 339.9 F g-1 (0.5 A g-1, 6 M KOH electrolyte) and excellent cycle durability with a capacitance retention of 98.4 % after 50,000 cycles (5 A g-1). Particularly, a non-aqueous symmetric supercapacitor assembled with 1 M Et4NBF4 electrolyte shows a high operating voltage of 2.8 V, and delivers the maximum energy/power density of 37.3 Wh kg-1 and 28.0 kW kg-1, respectively. The H2O2 activation method provides a green, efficient, and versatile strategy to improve the pore properties and chemical compositions of porous carbon materials towards energy applications.