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

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 ℃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86F·g^-1，且表现出良好的电容特性和大电流放电性能.

Hydrothermal Synthesis and Electrochemical Measurements of Interconnected Porous Carbon/MnO2 Composites

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 smaller. 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 ℃ 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.