Journal of Power Sources, Vol.195, No.2, 667-673, 2010
MgO-templated nitrogen-containing carbons derived from different organic compounds for capacitor electrodes
Carbons containing nitrogen (C-N composites) were derived from three commercial organic compounds, poly(vinylpyrrolidone) (PVP), polyacrylamide (PAA), and trimethylolmelamine (TMM) using the MgO template method. The C-N composites formed in nitrogen at 700-1000 degrees C had nitrogen content, WN, of 3-23 mass% and the specific surface area by N-2 adsorption, S-BET, of 60-2000 m(2) g(-1) without activation. Generally high nitrogen content of the starting compound led to larger W-N, but W-N was not proportional to the N/C mole ratio in the compounds. The value of SBET strongly depended on the compound: SBET (PVP) > S-BET (PAA) >> S-BET (TMM). There was a tendency forWN to decrease with increasing S-BET. The capacitance measured in 1 mol dm(-3) H2SO4 by cyclic voltammetry, C-M in F g-1, suggested that both WN and SBET are influential in gaining large C-M. For the composites with WN > 5 mass%, the capacitance normalized by SBET, CA = C-M/S-BET, was 0.17-0.65 F m(-2), which was larger than the electric double layer capacitance (0.05-0.15 F m(-2)), indicating that the pseudo-capacitance contributes significantly to C-M. The value of C-A increased with increasing W-N, but a correlation between C-A and particular nitrogen species on the surface measured by XPS was obscure. It was suggested that the large C-A is not simply explained by redox reactions of the surface functional groups. The composite derived from PAA at 900 degrees C showed 234 F g-1 at 2 mV s(-1) and 181 F g(-1) at 100 mV s(-1) with acceptable yield of the composite. (C) 2009 Elsevier B. V. All rights reserved.
Keywords:Electrochemical capacitor;Carbon containing nitrogen;Carbonization;MgO template method;Pseudo-capacitance