Study On The Preparation Method Of Electrode Materials In Electrochemical Supercapacitors

Electrochemical supercapacitor is a new energy storage equipment and component between battery and electrostatic capacitor, which has higher energy density than electrostatic capacitor and higher power density than battery. When working with batteries, they can meet the high power out-put need of electric vehicles when starting-up or accelerating. It can also be applied into many fields such as hybrid electric vehicle, fuel cell mobile telephone and microcomputer. According to the principle of energy-storage, there are two types of capacitors: electric double-layer capacitor and faradaic pseudocapacitor. Electrode material mainly includes carbon material, metal oxide and conducting polymer.A series of experiments were conducted on several subjects like electrode materials and electrolytes by the measure methods such as cyclic voltammetric measurement(CV), constant charge/discharge measurements, Ac-impedance, X-rays diffraction(XRD), scan electronic microscope(SEM), TG-DAT and so on.The powder NiO was prepared with sol-gel procedure. The parameters of preparation and mechanism of NiO pseudocapacitance, and the action of the electrolytes relative to NiO capacitance were simply discussed according to the theory of XRD and charge-discharge method. The redox reaction of the pseudocapacitance is NiO + OH^- → NiOOH + e^-; NiO capacitance is within the range from 0 to 0.5 V. The coexistence of LiOH and KOH is suitable for the forming of NiO pseudocapacitance due to the more reactivity of Li⁺ and the enhanced conductivity by K⁺. The capacitance of power NiO is composed of electrical double-layer capacitance, space charge capacitance and mostly pseudocapacitance. The highest specific capacitance, namely about 25F/g, was obtained when mole ratio of Ni(NO₃)₂·6H₂O to tartaricacid is 1:1, and calcination temperature is 300℃.The films of nickel hydroxide were electrochemically precipitated on nickel substrate and then annealed in air to obtain films of nickel oxide. Thermogravimetric analysis indicates that nickel hydroxide begins to turn into nickel oxide when the annealing temperature reaches 230℃. XRD identifies that there is only one single nickel oxide phase in the annealed films. Cyclic voltammetry and charge/discharge tests were employed to determine the specific capacitance. The effect on the...