Research On MnO₂Based Electrode Material For Supercapacitor

Abstract:Supercapacitor is an environmental energy storage device. It has high energy density, good reversibility and long cycle life. MnO2are very promising candidates as electrode materials in supercapacitors due to their low cost, low toxiclty and environment friendly characteristics.In the dissertation, MnO2was synthesized with chemical coprecipitation method by using KMnO4and Mn(AC)2aqueous solution as raw materials. The influence of different preparation factors on the electrochemical performance were investigated. The preparation process of MnO2electrodes was optimized and the electrochemical properties of MnO2/activated carbon composite electrode materials was studied. The results were as follows:(1) This Paper studied the impacts of the reaction temperatures, pH value, and reaction times on the physical properties and electrochemical properties of MnO2electrode. The experiment results showed that the optimal pH value was2, the optimal reaction time was6hours and the optimal temperature was70℃. The structure of synthesized samples was α-MnO2by XRD. The electrochemical performance was studied in1mol/L Et4NBF4/AN organic electrolyte. The results showed the specific capacitance was123.6F/g at20mA/cm3current density. And the internal resistance was2.49H.(2) The effect of Preparation process on the electrochemical performance of MnO2electrode which was made by Coating method using optimized MnO2powders. The experiment results showed that the ableting pressure was25MPa, the optimal drying temperature was100℃and the proportion of MnO2, acetylene black and PTFE was70:25:5. The electrochemical performance was studied in1mol/L Et4NBF4/AN organic electrolyte. The results showed the specific capacitance was146.5F/g, the internal resistance was1.35Ω at20mA/cm3current density and the internal resistance was1.35Ω.(3) The influence of AC contents on the manganese dioxide/activated carbon (AC) compound materials was applied for the supercapacitor electrode. The experiment results showed that MnO2 electrode mixed with AC had better electrochemical performance than MnO2eelectrode. The composite material with the ratio of MnO2:AC=3:2had the highest specific capacitance of194.6F/g, and had the smallest resistance of1.08Ω at20mA/cm3current density.