Nitrogen-doped porous carbons through KOH activation with superior performance in supercapacitors

Abstract

A series of nitrogen-doped porous carbons are prepared through KOH activation of a nonporous nitrogen-enriched carbon which is synthesized by pyrolysis of the polymerized ethylenediamine and carbon tetrachloride. The porosity and nitrogen content of the nitrogen-doped porous carbons depend strongly on the weight ratio of KOH/carbon. As the weight ratio of KOH/carbon increases from 0.5 to 2, the specific surface area increases from 521 to 1913m2g−1, while the nitrogen content decreases from 10.8 to 1.1wt.%. The nitrogen-doped porous carbon prepared with a moderate KOH/carbon weight ratio of 1, which possesses a balanced specific surface area (1463m2g−1) and nitrogen content (3.3wt.%), exhibits the largest specific capacitance of 363Fg−1 at a current density of 0.1Ag−1 in 1M H2SO4 aqueous electrolyte, attributed to the co-contribution of double-layer capacitance and pseudocapacitance. Moreover, it shows excellent rate capability (182Fg−1 remained at 20Ag−1) and good cycling stability (97% capacitance retention over 5000 cycles), making it a promising electrode material for supercapacitors.