Preparation of porous doped carbons and the high performance in electrochemical capacitors

Abstract

Porous doped carbons were synthesized by casting technique using zeolite 13X as the template through a polymerization reaction between ethylenediamine and carbon tetrachloride. The nitrogen contents and pore structures were further tailored by carbon dioxide and potassium hydroxide activations. These parameters played important roles in the electrochemical capacitors. The nitrogen- and oxygen-containing functional groups can make pseudocapacitance contribution to the overall capacitance, but face the disadvantage of blocking the electrolyte ions into pores. The investigation of relationship between the capacitance and the surface area or volume of the micropores indicated that high capacitance can be obtained for the carbon with large surface area and volume of micropores. Moreover, the mesopores in the carbons can be favor for smooth ion transfer. The porous doped carbon material with large specific surface area up to 2970 m 2 g −1 and volume of the micropores up to 1.04 cm 3 g −1 was achieved after the KOH activation, which exhibits the optimized electrochemical behavior with the gravimetric capacitances of 259 F g −1 in 6 M potassium hydroxide electrolyte and 176 F g −1 in acetonitrile solution containing 1.5 M tetraethylammonium tetrafluoroborate electrolyte at the current density of 0.25 A g −1.