Preparation Of Nano-Structure Oxide And Its Application In The Supercapacitors

As everyone knows electric vehicles can solve the problem of envinment pollution of automobile commendably, lots of related researchs have been doing all over the world in recent years. Supercapacitors, a new energy storage components between batteries and electrostatic capacitors, when work with batteries, can meet the high power out-put need of electric vehicles when starting-up or acceleration for their power density could be tens times higher than that of batteries. They could also be used as electric components and power sources for small electrical equipment and direct current switches. Now supercapacitors have become a hotspot in research, and in many countries other than China, supercapacitors have been sucessfully used in electric vehicles, there isn't any report on applicable supercapacitors techniques or products in our country. For all purposes, it's very important to have study on supercapacitors for the promotion of electric vehicles in our nation. We conducted a series of experiments to research on electrode materials, electrolytes, preparation and assemble techniques and other related techniques with the aids of the measure methods such as cyclic voltammetric measurements(CV), constant charge/discharge measurements, X-rays diffraction(XRD), transmission electronic microscope measurements(TEM), IR and so on. By experiments we got the conclusions as follows:1. The actived carbon electrode can provide better capacitance character in potassium hydroxide solution, and its specific capacitance increased obviously with the increase of KOH solution concentration. When the concentration reached thirty percent, specific capacitance of the electrode got to 200F/g which is maximal,and the capacitance could maintain at ninety percent after 5000 cycles. We also found that it was the smaller capacitance of the positive electrode that limits the performance of the AC electrode, and the capacitor character reached optimization when the ratio between the mass of positive actived material and that of negative actived material.'2. In ammonium sulfate solution, the AC electrode could also perform better capacitance, which potential range get to 1.5V. That made the energy density and power density of the capacitor inhanced greatly.3. Nano-NiO was obtained by heated nano-Ni(OH)2 in 3 00 癈,which was prepared by mixing aqueous solutions of Ni(NC>3 )2 and KOH in the ammonia water. As the positive active material, nano-NiO can performanced good capacitance in the KOH solution. The nano-NiO electrode can provide a specific capacitance of llOF/g, and the capacitance could maintain at ninety percent after 5000 cycles.4. Hydrous nano-MnOi was synthesized by oxidation of aqueous MnSCU in KMnC>4 solution. In Na2SC>4 and (NH^SC^ aqueous electrolytes the material proved to be an excellent positive electrode material for faradic capacitor. And its specific capacitance, which could maintain at ninety percent after 5000 cycles, reached 189.5F/g and 158.9F/g respectively.5. By using MnO2 as positive electrode and actived carbon as cathode ,we could assemble a hybrid capacitor in (NHt^SC^ aqueous electrolyte . The mass ratio between actived materials of the positive electrode and that of cathode effected the specific capacitance of the capacitor. The experimental results showed, when the mass ratio was 1.28, that the capacitor could provide the highest specific capacitance of 42.8F/g, and the highest working voltage of 1.5V, which enhanced the power density to 3 times and energy density to 1.5 times that of carbon based capacitor.Through the optimization of the electrode preparation techniques, we found the best way to manufacture electrodes and sucessfully assembled a applied hybrid capacitor whose performance is close to that of the similar products made in U.S.A.. It will be a promising applied future .