活化方式对有序介孔炭孔结构及电化学性能的影响

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

采用软模板法合成有序介孔炭(OMC),并通过不同的活化方式对OMC进行活化处理,以制备出具有较高比表面积的微/介孔炭材料。利用小角X射线衍射、氮气吸附、扫描及透射电镜对活化前后介孔炭的孔结构进行表征;循环伏安、恒流充放电、交流阻抗等方法测试其电化学性能。探讨不同活化方式对介孔炭孔结构和电化学性能的影响。结果表明:高温活化在保持介孔炭的有序性及其二维六角结构的基础上,在其孔隙结构中形成了大量微孔结构,有效地提高了介孔炭的孔体积及比表面积,比表面积由674 m^2/g提高到2 404 m^2/g,孔体积由0.98 cm^3/g提高到2.24 cm^3/g,并进一步提高了介孔炭的电化学性能,在500 mA/g电流密度下,其比电容可达175 F/g。活化方式对活化后的介孔炭的孔结构及电化学性能有很大的影响。

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,SEMand 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 m A/g. The increasing order of the capacitance retention ratios of the activated samples at high current densities is A1 〈 A2 〈 A3.