The effects of activation method on the pore structure and electrochemical properties of ordered mesoporous carbons used as the electrode materials of supercapacitors

An ordered mesoporous carbon (OMC) synthesized by the soft-template method was activated by (a) CO₂ at 900℃ for 4 h, (b) H₂O at 800℃ for 20 min, and (c) H₂O at 800℃ for 20 min followed by CO₂ at 900℃ for 4 h to produce three micro-mesoporous carbons, A1, A2 and A3, respectively. Their pore structures were investigated by XRD, TEM, SEM and N₂ adsorption. Their electrochemical properties as the electrode materials of supercapacitors were investigated by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. Results indicated that the highly ordered 2D hexagonal original mesostructure of the OMC was well retained after activation. The increasing order of the extent of activation is A1 < A2 < A3. The specific surface area, pore volume and the specific capacitance of A3 compared to OMC respectively increased significantly from 673 to 2404 m²/g, from 0.98 to 2.24 cm³/g and from 70 to 175 F/g at a current density of 500 mA/g. The increasing order of the capacitance retention ratios of the activated samples at high current densities is A1 < A2 < A3.