高比表面积活性炭基水系Na_2SO_4电化学电容器的制备

High specific surface area carbon/carbon electrochemical capacitor in aqueous Na_2SO_4 electrolyte

以石油焦为前驱体和KOH作为活化剂制备一种用于电化学电容器的高比表面积活性炭,采用廉价弱腐蚀性的Na_2SO_4电解液制备一种高电压的对称活性炭基水系电化学电容器,用N2吸附-脱附仪表征活性炭电极材料的孔结构参数,用循环伏安、恒流充放电和交流阻抗等电化学测试方法研究其电化学性能。研究结果表明,活性炭的比表面积为2855m^2/g,平均孔径为2.31nm;活性炭基水系电化学电容器在1.0mol/L Na_2SO_4电解液中扫描速率为2mV/s的比电容能达到188F/g,在功率密度为200W/kg时能量密度达到19.4Wh/kg,活性炭基水系电化学电容器在电压值为1.6V下展现了良好的循环性能,意味着Na_2SO_4电解液对开发能量密度高和环境友好的电化学电容器有着重要的意义。

The high speci/ic sur/ace area activated carbon for electrochemical capacitors was prepared by chemical ac- tivation method treated the petroleum coke with KOH served as activation agent. A high voltage symmetric carbon/carbon electrochemical capacitor was built with Na2SO4 aqueous solution for its cheap and non-corrosive characteristics. The nitro- gen adsorption-desorption at 77K was used to characterize pore parameters of samples. Electrochemical performances were investigated by cyclic voltammetry, galvanostatic charge-discharge and nyquist impedance spectra and so on. The results showed that the prepared activated carbon had a specific surface area of 2855m2 .g-1 and a mean pore diameter of 2.31nm, the specific capacitance of capacitor was 188F.g 1 in 1.0mol.L 1 Na2SO4 electrolyte at the scan rate of 2mV.s-1 ,and the energy density can be as high as 19.4Wh.kg^-1 at a power density of 200Wh.kg-1. Symmetric capacitors exhibited an excel- lent cycle life for voltage values up to 1.6V,showing the promise of Na2SO4 for developing high energy density and envi- ronment friendly systems.