硝酸改性无灰煤基多孔炭电极材料的制备

Preparation of hyper coal-porous carbon electrode material with HNO_3 modification

以褐煤基无灰煤为原料,采用KOH活化法制备多孔炭材料(PC),通过不同浓度HNO_3对多孔炭进行氧化改性,利用N_2等温吸附、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)等方法对多孔炭进行表征,结合恒流充放电(GC)、循环伏安(CV)和交流阻抗的测试结果,考察浓度对多孔炭孔结构、表面性质以及电化学性能的影响。研究表明,随着HNO_3浓度的增加,多孔炭的比表面积逐渐降低,润湿性提高;用1%HNO_3改性的多孔炭N-5、C—O及O—C—O含量增加明显,在50mA/g的电流密度下,比电容可达273F/g,相比未改性的多孔炭,比电容量增长了22.4%;在5 000mA/g的电流密度下,比电容保持率能达到80.4%,且在1 000次循环后,比电容仍具有95.2%的保持率,具有良好的电化学性能。

Hyper coal（HPC）was used to prepare porous carbon（PC）by KOH activation method.Then the PC was modified by different concentrations of HNO3.N（2 ）adsorption instrument,scanning electron microscopy（SEM）and X-ray photoelectron spectroscopy（XPS）were used to characterize the pore structure.Galvanostatic charge/discharge（GC）,cyclic voltammetry（CV）and electrochemical impedance spectroscopic analyses were used to test the electrochemical properties of PC.The results show that BET surface area of porous carbon decrease and wettability improved with the increase of HNO3concentration.The contents of N-5,C—O and O—CO increase significantly when the PC was modified by 1%HNO3.Specific capacitance of PC is 273F/g at a current density of 50mA/g with the concentrations of 1%,which is 22.4%higher than that of the unmodified PC.It still maintains 80.4%at a current density of 5 000mA/g.Even after 1 000cycles,it is clear that the specific capacitance still remains at about 95.4%,demonstrating good electrochemical performance.