Simple synthesis of hierarchical porous carbon with developed graphene domains for high performance supercapacitors

Abstract

Hierarchical porous carbons with localized graphene structure, high specific surface area and large pore volume are simply synthesized by the means of short-time pyrolysis at moderate temperatures and acid-washing. Citric acid and cobalt acetate were used as carbon source and template precursor, the effect of mass ratio of citric acid/cobalt acetate on the microstructures of the hierarchical porous carbon, including morphology, crystal structure, porosity, specific surface area and surface chemistry, have been investigated. The resultant hierarchical porous carbons possess high specific surface area of 1411 m2/g, a large pore volume of 2.34 cm3/g. Both three-electrode and two-electrode test were conducted to evaluate capacitive performance of the hierarchical porous carbon. The test of three-electrode system with 6 M KOH aqueous solution as electrolyte, the hierarchical porous carbon shows superior specific capacitance up to 239 F/g at 0.1 A/g. In 1 M Na2SO4 aqueous electrolyte. Moreover, the hierarchical porous carbon based two-electrode supercapacitors presents gravimetric energy density of 11.6 Wh/kg and power density of 250 W/kg. This work developed a facile way for high surface areas and large pore volume electrode materials for energy storage devices.