互通多孔碳/二氧化锰纳米复合材料的原位水热合成及电化学性能

摘要

以互通多孔碳(IPC)为载体,水热条件下在碳表面原位反应生成纳米结构的二氧化锰(MnO2),制备互通多孔碳/二氧化锰纳米(IPC/MnO2)复合电极材料.采用扫描电镜(SEM),透射电镜(TEM), X射线衍射(XRD),热重分析(TGA)对其结构进行表征；采用循环伏安法、恒流充放电和交流阻抗对其电化学性能进行研究.结果表明：生成的MnO2均匀地负载在碳的表面,形成多层次结构,并且随着温度的升高IPC表面负载的MnO2由纳米颗粒变为纳米片状结构； MnO2纳米片具有典型的 K-Birnessite 型晶体结构；复合物中 MnO2的含量约为34%(w).在100°C制备的IPC/MnO2复合材料在三电极系统中最高比电容达到了411 F∙g-1；随着反应温度的升高,比容量先增长后基本保持不变.以IPC/MnO2为正极,活性炭(AC)为负极,1 mol∙L-1 Na2SO4溶液为电解液组装成IPC/MnO2//AC混合超级电容器,发现IPC/MnO2电极的电容器其电位窗口从1 V扩展到1.8 V,容量可达86 F∙g-1,且表现出良好的电容特性和大电流放电性能.%This article describes the electrochemical performance of a novel interconnected porous carbon/MnO2 (IPC/MnO2) composite prepared by in situ self-limiting deposition under hydrothermal condition. The morphology and structure were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA), and the electrochemical behavior was investigated using cyclic voltammetry (CV), charge-discharge tests, electrochemical impedance spectroscopy (EIS), and cycle life tests. The results showed that MnO2 grew homogeneously on the IPC surface, forming a hierarchical microstructure. The MnO2 had a typical K-Birnessite-type crystal structure and the MnO2 content was about 34% (w). At high synthetic temperatures, the MnO2 particles on the IPC surface were smal er. The prepared electrode material exhibited a good electrochemical capacitance performance. As the reaction temperature increased, the specific capacitance of the IPC/MnO2 composite first increased and then remained constant. The IPC/MnO2 composite synthesized at 100 °C had the maximum specific capacitance, 411 F∙g-1, in a three-electrode system. An asymmetric supercapacitor was constructed with the IPC/MnO2 composite as the positive electrode and activated carbon (AC) as the negative electrode, in a 1 mol∙L-1 Na2SO4 electrolyte.The results showed that the corresponding potential window increased from 1 to 1.8 V. The maximum specific capacitance of the asymmetric supercapacitor was 86 F∙g-1 and a good rate capability was achieved.