胜利褐煤基活性炭的制备及在双电层电容器中的应用研究

发布时间：2018-03-20 10:43

  本文选题：胜利褐煤　切入点：活性炭　出处：《中国矿业大学》2017年硕士论文　论文类型：学位论文

【摘要】：本论文以胜利褐煤为原料,KOH为活化剂,采用炭化活化法和HNO_3表面氧化改性法制备活性炭,采用扫描电子显微镜(SEM)、X射线衍射(XRD)、N2等温吸脱附、傅里叶变换红外光谱(FTIR)和X射线光电子能谱(XPS)等表征活性炭结构及表面性质。将所制备活性炭用于双电层电容器(EDLC)的电极材料,通过恒流充放电、循环伏安和交流阻抗等方法测试活性炭电极的电化学性能。重点考察了活性炭制备条件和HNO_3表面氧化改性对胜利褐煤基活性炭比表面积、孔结构及其电化学性能的影响。电化学性能测试表明,不同制备条件下的活性炭电极在6 mol L-1 KOH电解液中具有良好的充放电性能,且KOH体系下的比电容高于有机体系下的比电容。结果发现,增大活性炭的表面积可以提高活性炭电极的比电容,但两者不是简单的线性关系。比电容随着电流密度的增大呈现出不同程度的衰减,并且在高电流密度下具有较高的比电容保持率,表现出较好的大电流放电特性。经700 ℃炭化,800 ℃活化2 h(KOH/样品为4)制备的活性炭AC-K-4的比表面积为2550 m2g-1,孔容为1.24 cm3 g-1,比电容在电流密度是40 mA g-1时达到213 F g-1,200mA g-1时保持在175 F g-1。并且,该电极具有良好的循环稳定性,充放电循环1000次后,充放电效率保持在96%左右,表明制备的胜利褐煤基活性炭是EDLC适宜的电极材料。对活性炭进行HNO_3氧化改性,活性炭的比表面积和孔容有所降低,但增加了活性炭表面的含氧官能团,其中羟基和羧基含量增加最为明显。结果表明,60%HNO_3改性的活性炭电极AC-K-4在40 mA g-1时的比电容增加到245 F g-1,且活性炭表面引入的含氧官能团使其的润湿性有所增加,电荷迁移电阻和漏电流有所降低,进而提高了活性炭电极的能量密度。
[Abstract]:In this paper, activated carbon was prepared by carbonization activation and surface oxidation modification of HNO_3 with Shengli lignite as raw material and Koh as activator. The adsorption and desorption of activated carbon by scanning electron microscope (SEM) were studied by X-ray diffraction (XRD) and X-ray diffraction (XRD). Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were used to characterize the structure and surface properties of activated carbon. The electrochemical performance of activated carbon electrode was measured by cyclic voltammetry and AC impedance. The preparation conditions of activated carbon and the specific surface area of Shengli lignite based activated carbon modified by HNO_3 surface oxidation were investigated. The effects of pore structure and electrochemical properties on the electrochemical properties of activated carbon electrode were investigated. The results showed that the activated carbon electrode prepared under different conditions had good charge-discharge performance in 6 mol L-1 KOH electrolyte. The specific capacitance in KOH system is higher than that in organic system. The results show that the specific capacitance of activated carbon electrode can be increased by increasing the surface area of activated carbon. But the two are not simple linear relations. The specific capacitance attenuates with the increase of the current density, and has a higher specific capacitance retention rate under the high current density. The activated carbon AC-K-4 prepared at 700 鈩，

本文编号：1638728