四种晶型MnO_2超级电容器电极材料的电化学性能研究

An Investigation on Electrochemical Performances of Supercapacitor Electrode Materials Prepared by MnO_2 with Four Different Crystal Forms

用尽量简便的方法制备出δ、α、β及γ型4种MnO2粉末.通过X射线衍射(XRD)、场发射扫描电镜(FSEM)、热重分析(TGA)与比表面积测试(BET)等方法对样品粉末性质进行分析,并对4种不同粉末制成的电极进行循环伏安、恒流充放电及稳定性测试.结果表明,4种MnO2都具有良好的电容特性,其中α-MnO2具有最高的比表面积与孔隙率,故其电极比容量最高,但其大电流放电时的倍率特性较差.其余3种MnO2比表面积相当,而β-MnO2虽然比容量较低,但其简单的孔隙结构使其拥有最好的倍率特性与稳定性.

Four types of a-MnO2,β-MnO2, γ-MnO2 and/δ-MnO2 powders were synthesized by relatively simple methods. The differences in crystal structures and surface morphologies for these forms of MnO2 were investigated by using X-ray diffraction （XRD）, field emission scanning electron microscopy （FESEM）, thermogravimetric analysis （TGA） and specific surface area analysis （BET）. The electrochemical performances were characterized by cyclic voltammetry （CV） and stability analysis. Based on the ex- perimental results, four kinds of MnO2 electrodes showed good capacity properties, and the α-MnO2 electrode had the largest specif- ic capacity due to the highest specific surface area and porosity. The remaining three types of MnO2 electrodes had similar specific surface areas, and the β-Mn02 electrode had better rate discharge property and stability due to its lower developed pore structure.