Study of activated nitrogen-enriched carbon and nitrogen-enriched carbon/carbon aerogel composite as cathode materials for supercapacitors

Abstract

An activated nitrogen-enriched carbon (ANC) material and a novel activated nitrogen-enriched carbon/carbon aerogel (ANC/ACA) composite were prepared by carbonization and activation of melamine resin and melamine resin/carbon aerogel composite. These were characterized by SEM, XPS, nitrogen adsorption/desorption and electrochemical measurements. Findings indicated than the materials had a highly porous nanometer-sized honeycomb structure and high specific surface area. ANC and ANC/ACA contained 2.22% and 2.12% nitrogen, respectively. The introduction of activated carbon aerogel (ACA) with high conductivity improved the conductivity of ANC. Compared to ACA, greater specific capacitance was obtained for both ANC and ANC/ACA. Asymmetric supercapacitors were assembled with Ni(OH) 2/Co(OH) 2 as anode and our ANC or novel ANC/ACA as cathodes. Electrochemical properties of the supercapacitors with different mass ratios of the two electrodes at different current densities were measured by a galvanostatic charge/discharge technique. When the mass ratio of cathode to anode was 2.2:1 and the current density was 7.5 mA cm −2, the specific capacitance and specific energy of the asymmetric supercapacitor with ANC/ACA as cathode were 110.60 F g −1 and 17.28 Wh kg −1, higher that those of asymmetric supercapacitors with ANC or ACA as cathodes. For ANC/ACA, the attenuation ratio of specific capacitance was only 8.39% after 10,000 cycles. ANC/ACA was found to be a suitable cathode material for use in supercapacitors.