反应温度对隐甲锰矿型MnO_2微纳结构和超级电容性能的影响

The effect of reaction temperature on the micro-nano structure and the capacitance properties of cryptomelane-type manganese oxide

采用简单的水热法制备了具有均一八面分子筛（OMSG2）结构的隐甲锰矿型二氧化锰（MnO2）;通过水热反应温度控制MnO2的微纳结构,研究反应温度对其超级电容器性能的影响.采用扫描电子显微镜（SEM）、X射线衍射（XRD）和透射电子显微镜（TEM）表征材料的结构特点;采用循环伏安和恒流充放电测试其电化学电容性能.结果表明,制备的MnO2具有纳米刺或纳米棒形成放射状结构,随着反应温度的增加,MnO2晶体逐渐生长完全,从针状纳米刺转变成四方形纳米棒;制备的MnO2具有双电层电容和法拉第准电容的双重特征,在5mA/cm^2的电流密度下,最高比电容达到了603F/g;在100-180℃的范围内,比容量随着反应温度的升高而逐渐降低.

In this article,the uniform cryptomelane-type manganese oxide with an octahedral molecular sieves structure was prepared under mild hydrothermal condition;the effects of hydrothermal temperature on the mi-cro-nanostructure and supercapacitance properties of manganese dioxide were studied in detail.The structures were characterized by SEM,XRD and TEM;and the supercapacitive behaviors were investigated with cyclic voltammetry,galvanostatic charge and discharge tests.The experiment results suggested that:the prepared nanoparticles can be self-organized into dendritic nanostructures,and the nanocluster arrays are composed of nanoneedles or tetragonal prism nanorods;with the increase of reaction temprature,the crystal morphology of manganese oxide was gradually improving,and was trasformed from nanoneedles to tetragonal prism nanorods;the capacitance of MnO2 electrode was a combined contribution of electrical double-layer capacitance and pseud-ocapacitance,and the best specific capacitance value of MnO2 electrode was 603 F/g corresponding to the charge/discharge current density of 5 mA/cm2;with the increase of reaction temperature ranging from 100-180℃,the specific capacitance of manganese oxide gradually decline.