Preparation And Regulation Of Mesoporous Carbon As Electrode Materials For Supercapacitor

Mesoporous carbon (MC) has received considerable attention as electrode materials for supercapacitor because of its advantageous properties.In this paper, mesoporous carbons with different pore structures were prepared by templating method using asphaltene or phenolic resin as carbon source and gas phase made silicon dioxide or magnesium citrate as hard template. In the following step, MCs were activated by CO2 or doped with nitrogen in order to improve the electrochemical behavior. The micro-structure of MCs were characterized by SEM, TEM, XRD, N2 adsorption and ultimate analysis. And the electrochemical properties were investigated with cyclic voltammetry, AC impedance and constant-current charge-discharge. The main results are shown as follows:1) MCs with bimodal distribution can be prepared by mixing the asphaltene with tetrahydrofuran solution containing gas phase made silicon dioxide, followed by carbonization and template dissolution. And at the optimum mass ratio of asphaltene to gas phase made silicon dioxide of 1:1.2, the resulted MC showed the pore volume of 2.3 cm3/g, the average pore size of 12.9 nm and the specific capacitance of 108 F/g at a current density of 1000 mA/g.2) CO2 activation improved the properties of the MC mentioned above. The specific surface area of MC has an increase of 53%, which is from 722 m2/g before activation to 1103 m2/g after activation at 900℃for 120 minutes. And the specific capacitance of MC activated at 900℃for 120 min under a CO2 flow rate of 100 mL/min is 135 F/g at the current density of 1000 mA/g and the retention rate of specific capacitance is 93% after 10000 charge-discharge cycles.3) MCs were prepared using magnesium citrate as the template and asphaltene or phenolic resin as carbon source. The maximum specific surface area and the maximum specific capacitance of MC from phenolic resin are 2020 m2/g and 205F/g respectively while those of the MC from coal-based asphaltene are 1634m2/g and 176 F/g respectively. However, the specific capacitances of MCs with the same pore structure from asphaltene and phenolic resin are different, with the former being 176 F/g and the latter being 114 F/g; The electrochemical performance of MC from phenolic resin is improved after doping with nitrogen.