Supercapacitive behaviors of the nitrogen-enriched activated mesocarbon microbead in aqueous electrolytes

摘要

The activated nitrogen-enriched novel carbons (a-NENCs) have been prepared by direct carbonization of polyaniline/activated mesocarbon microbead composites and further activated by 16 M HNO_3. The electrochemical performances and supercapacitive behaviors of the a-NENCs in 6 M KOH, 1 M H _2SO_4, and 0.5 M K_2SO_4 solutions are evaluated by cyclic voltammetry, galvanostatic charge/discharge, electrochemical impedance spectroscopy, cyclic life, leakage current, and self-discharge measurements. The results demonstrate that the supercapacitors perform definitely supercapacitive behaviors; especially in 6 M KOH electrolyte, the supercapacitor represents much better electrochemical performance with more excellent reversibility, shorter relaxation time of 1.11 s, and nearly ideal polarizability. The maximum specific capacitance of the supercapacitors using a-NENCs as active electrode material is 85.1 F g~(-1) at a rate of 500 mA g~(-1) in 6 M KOH. These outcomes indicate that the 6 M KOH aqueous solution is a promising electrolyte for the supercapacitor with a-NENCs as electrode material.