Nitrogen-containing carbon microspheres for supercapacitor electrodes

Nitrogen-containing carbon microspheres (NCMs) were prepared via directed carbonization of poly(1,5-diaminonapthalene) at different temperatures which was synthesized from 1,5-diaminonapthalene with ammonium persulfate as oxidizing agent. The NCMs were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), N-2 adsorption-desorption analysis, thermogravimetric-differential thermal analysis (TG-DTA) and X-ray photoelectron spectroscopy (XPS). A typical sample (NCM-700) shows a specific surface area of 403m(2) g(-1), nitrogen content of 5.94 at.%, and regular spherical geometry (0.2-0.5 mu m in diameter). The electrochemical properties of the NCMs electrodes were investigated by cyclic voltanmetry and galvanostatic charge-discharge measurement. NCM-700 electrode shows a high specific capacitance of 228 F g(-1) at a current density of 1.0 Ag-1 in 6M KOH aqueous electrolyte, indicating good capacitive behavior. Besides, the electrode still remains 196 F g(-1) (with capacitance retention of 86%) after 5000 charge/discharge cycles, suggesting excellent cycling stability. (C) 2015 Elsevier Ltd. All rights reserved.