Electrochemical Properties of Supercapacitor Electrode Materials Prepared by MnO2 with Different Crystal Forms

The β-typed and γ-typed electrodes were prepared by MnO2 powders with different crystal forms, and the electrochemical properties of the above-mentioned electrodes were studied by cyclic voltammetry method and constant-current charge and discharge test. The results show that both the β-typed and γ-typed electrodes had good capacitance property, and the γ-MnO2 electrode had better rate discharge property and was more suitable for charge-discharge of larger current. Under the condition of the current density of 300 mA·g-1, the β-MnO2 electrode became invalid but the capacitance retention of γ-MnO2 electrode was still as high as 89.2% after circulatory charge-discharge 5 000 cycles.