Preparation Of Electrode Materials Based On Manganese Oxides For Supercapacitors And Study On Their Electrochemical Properties

Many countries of the world have taken many measures to develop supercapacitor to solve energy urgency and environment problems.Manganese oxides with the virtue of low price,high theoretical specific capacitance and environmental friendliness,has been widely studied as supercapacitor electrode material.In this paper,two types of MnOx electrodes were prepared by simple synthesis method.And a variety of physical and electrochemical characterizations were used to study their structure and electrochemical properties.The main contents are as follows:1.Hydrothermal preparation and study on electrochemical properties of manganese oxides electrode materials with different morphology and crystal structureIn this experiment chapters,potassium permanganate and the compound with catechol structure?dopamine hydrochloride,or 3-?3,4-dihydroxyphenyl?propionic acid?were used as two kinds of raw material.A variety of manganese-based compounds with different morphologies and different crystal structures were successfully prepared in hydrothermal system by adjusting the mole ratio of raw materials.The morphologies and crystal structures of these products were measured by TEM?SEM?XRD and FTIR,such as flower-like ?-MnO₂,rod-like MnOOH,Mn₃O₄ nanoparticles,cube and spindle-like MnCO₃.These compounds powder were coated to current collector to make into powder electrodes,and studied their electrochemical properties in 0.5 M Na2SO₄.The results show that Mn₃O₄ nanoparticles and MnCO₃ cube have minimum specific capacitance,and rod-like MnOOH and spindle-like MnCO₃ have litter higher specific capacitance.Besides,flower-like ?-MnO₂ has the highest specific capacitance of 307.4 F/g.And ?-MnO₂ powder electrode can keep 56.2% of capacitance retention after 500 cycles,which can be applied as supercapacitor electrode.2.Preparation and study on electrochemical properties of nickel foam/manganese dioxide composite for high-performance electrochemical supercapacitor electrodeIn this chapter,MnO₂ was directly loaded on the surface of nickel foam by the redox reaction between potassium permanganate and acetic acid,and this nickel foam/MnO₂ composite material can be used as electrode without further treatment.By TEM and SEM characterizations,we found MnO₂ nanosheets were interconnected and loaded on the surface of nickel foam successfully.And electrochemical properties of nickel foam/MnO₂ composite material were studied by electrochemical characterizations such as CV and GCD.In this composite material,MnO₂ provides high capacitance,and 3D porous nickel foam provides a large specific area and high electronic conductivity.So the electrochemical performances of nickel foam/MnO₂ electrode were obviously superior to MnO₂ power electrode.Electrochemical tests show that the nickel foam/MnO₂ electrode material has good electrochemical capacitance: specific capacitance as high as 1095 F/g at a scan rate of 5 mV/s,fast reflect of oxidation/reduction on high current changes?499 F/g at a scan rate of 100 mV/s?,low resistance and long cycle life?retain 54.5% of the initial specific capacitance after 1000 times charging and discharging cycle?.