High packing density and rich pseudocapactive nitrogen doped nanocarbon boosts superior volumetric-supercapacitor performance

Abstract

Carbon-based electrodes are usually poor in volumetric supercapacitor performance in terms of volumetric capacitance (<200 F/cm3) and energy density (usually <10 Wh/L) resulted from low packing density. Herein, we propose a strategy for the preparation of nanocarbon electrodes that are ultrahigh in volumetric supercapacitor performance by creating nanocarbon with high packing density and rich pseudocapacitive nitrogen doping, in which the nitrogen doping is to provide extra capacitance. The derived nanocarbons (ZHNCs) have not only large packing density of 1.14–1.49 g/cm3 and rich nitrogen content (12.3–24.8 atom%), but also homogeneous element distribution. Benefited from the synergetic effect of the above characteristics, the ZHNCs-based electrodes exhibit superior volumetric performances of ultrahigh capacitance of 528 F/cm3 in 1.0 M H2SO4 and 465 F/cm3 in 6.0 M KOH, large energy density of 26.8 Wh/L at 2682 W/L, and impressive cycling stability with about 95% capacitance retention after continual charge/discharge of 20 000 cycles at current density of 20 A/g, indicative of potential applications in the fields of energy storage.