Fabrication Of MnO₂ Hollow Microsphere And Its Application

were widely investigated as electrode material for supercapacitor with good electrochemical properties, high energy density,low cost and no pollution. In this paper, first is to made MnCO3 precursor by NH4HCO3 or Na2CO3,then use the precursor to made MnO2 hollow microspheres by the way of thermal oxidation or hydration. By cyclic voltammetry, charge-discharge testing techniques, XRD, EDX, SEM and other techniques MnO2 supercapacitor is tested.The hollow synthesize by hydration may form from the reaction between HCl and interior MnCO3 staying away from being oxidized by KMnO4 in the previous step. By thermal oxidation MnCO3 changes to MnO2 and CO2. CO2 is a gas and leaves throw the hole and then MnO2 becomes hollow synthesize.Prepared by thermal oxidation is simple and saving time. The capacitance performance of electrode materials prepared by thermal oxidation is superior to the the one prepared by hydration. The main impact of changes in pH are particle size of microspheres,capacitance and impedance. Temperature effects on the thermal oxidation can produce different products, when the temperature is higher MnO2 prepared by thermal oxidation is the better. Heating time on the impact of thermal oxidation is increased with time after the performance worse before getting better.MnO2 electrode materials prepared with Na2CO3 are in the low capacitance, high charge and discharge efficiency; MnO2 electrode materials prepared with NH4HCO3 are in the high capacitance, a little low charge and discharge efficiency.but generally speaking,electrode materials prepared with Na2CO3 is superior to the one prepared with NH4HCO3.On study of pH, time, temperature, molar ratio of starting material, pH is the greatest impact on the preparation of the morphology and electrochemical properties of MnO2, the best performance of MnO2 microspheres conditions is precursor prepared by Na2CO3 under the conditions in the pH of 10.0 and then MnO2 prepared by thermal oxidation.Testing the electrochemical properties of MnO2 in 0.5 mol/L Na2SO4 electrolyte on 5 mA constant current charging and discharging capacitance, specific capacitance is 267.10 F/g.