活性炭表面担载氧化锰复合电极的电化学电容性能

通过在两种商品活性炭XC-72(比表面250m2·g-1)和YEC-8(比表面1726m·2g-1)电极表面涂刷Mn(NO3)2,并在200℃进行热分解得到表面担载氧化锰的复合材料电极.采用扫描电子显微镜(SEM)和X射线衍射(XRD)表征电极的形貌和氧化锰的晶体结构,采用循环伏安、恒流充放电和交流阻抗考察了不同电极的电化学电容性能.结果表明,Mn(NO3)2在200℃的热解产物是α-Mn2O3和α-Mn3O4的混合物.当C和MnOx的质量比为2∶1和9∶1时,XC-72/MnOx中氧化锰的比电容分别达到499和435F·g-1,YEC-8/MnOx中氧化锰的比电容分别达到554和606F·g-1,表明氧化锰的赝电容对电极比电容的贡献十分显著.

Electrochemical Capacitance of Composites with MnOx Loaded on the Surface of Activated Carbon Electrodes

Activated carbon/manganese oxide (MnOx) composites were prepared by the thermal decomposition of Mn(NO₃)₂ that was impregnated on the surface of activated carbon XC-72 with a specific surface area of 250 m²·g^-1 and on YEC-8 with a specific surface area of 1726 m²·g^-1 at 200 ℃. The surface morphology and crystalline structure of the composites were investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The electrochemical properties of the composites were tested by cyclic voltammetry, galvanostatic charge-discharge, and impedance spectroscopy. We found that α-Mn₂O₃ and α-Mn₃O₄ were formed when the composites were annealed at 200 ℃. At mass ratios of C and MnOx of 2∶1 and 9∶1, the specific capacitance of MnO_x in the composites of XC-72/MnO_x was 499 and 435 F·g^-1 and the specific capacitance of MnOx in the composites of YEC-8/MnO_x was 554 and 606 F·g^-1, respectively. This suggests a significant contribution of pseudocapacitance from MnOx to the specific capacitance of the electrode.