Preparation And Study On Electrode Material Of Supercapacitor

As a new kind of energy storage component,supercapacitor is characterized with high energy density,high power density and high specific capacitance. The promising application of supercapacitor in such fields as electric vehicle, military force and mobile telecommunication,has been attracting more and more researcher all over the world. The performance of the electrode material is the most important factor affecting on the nature of supercapacitor. Studies on high performance electrode material of supercapacitors are mainly focused on the manganese oxide,carbon nanotubes,nickel oxide material. The main results of this dissertation are as the following:(1)MnO₂ powder wre prepared by chemical precipitation. The synthesized MnO₂ material under different heat-treat temperatures were tested by X-ray diffraction(XRD) and scanning electron microscopy(SEM).The results indicated that the MnO₂ material was granular and had particle size of about 200nm. Electrochemical properties of the synthesized MnO₂ were studied by using cyclic voltammetry(CV) and galvanostatic charge-discharge measurements. The CV profile indicated that the capacitive behavior of MnO₂ electrode material has an ideal rectangular shape. In the potential range of-0.2～+0.8V,the specific capacitance of MnO₂ was found to be 253.5F/g at scan rate of 1mV/s in a 1mol/L Na₂SO₄ aqueous electrolyte. The synthesized MnO₂ material heat-treat at 150℃showed a better cycling stability than the MnO₂ material heat-treat at 40℃.(2)The CV behavior and galvanostatic charge-discharge characteristic of carbon nanotubes(CNTs) was studied. It showed that CNTs has an ideal double-layer capacitive nature. In the potential range of -0.2～+0.8V,the specific capacitance of CNTs was found to be 27.3F/g at scan rate of 1mV/s in a 1 mol/L Na₂SO₄ aqueous electrolyte(3)The CNTs refluxed by nitric acid was tested by SEM and TEM. It indicated that the end of the CNTs had been opened after it was refluxed 80h.The specific discharge capacitance of the refluxed CNTs is 38.3F/g, and the specific discharge capacitance of the CNTs without being refluxed only reached 8.3F/g.(4)The alligned carbon nanotubes(ACNTs) electrode material was prepared by different catalyst on the foam nickel. The length of the ACNTs is 5um and its diameter is 100nm.The specific capacitance of the ACNTs electrode prepared by 0.1M Ni catalyst reached 278.2F/g in the potential range of -0.2⁺0.8V,at scan rate of 1mV/s in 1mol/L Na₂SO₄ aqueous electrolyte.(5)The MnO₂/CNTs composite electrode material was studied. It has the high specific capacitance of MnO₂ and the good chage-discharge cycling stability of CNTs.(6)Synthesized NiO was used as electrode material for supercapacitor. In the potential range of -0.2～+0.8V,at scan rate of 1mV/s in 1mol/L Na₂SO₄ aqueous electrolyte,the synthesized NiO material prepared by pH sulotion of 11.7 and heat-treat temperature of 500℃and heat-treat time of 8h has a high specific capacitance of 38.2F/g.