Research On The Technique And Character For Functional Material Of Nickel Oxide Prepared By Electrochemical Deposition Method

Supercapacitor which power density could be tens times higher than that of batterie and energy density could be tens times higher than that of electrostatic capacitor, is a new type of electrochemical energy storage devices between rechargeable battery and dielectric capacitor. It could be widely used in many fields such as electric vehicle's accelerating and braking system, moving communication, information technology, aviation and spaceflight, national defensive technology and so on. Interest in electrochemical capacitor has risen in recent years. The dissertation focuses on the exparimental parameter's influence on the electric cunent efficiency and specific capacitance of the material. The material's components and properties were characterized by some experiments methods and testing measures such as cyclic voltammetry(CV), powder X-ray diffraction(XRD), thermal adsorb(DTA), Fourier transform mfrared(FTIR), atomic adsorb spectrum(AAS) and so on. The main results are as follows.(1)The electric current efficiency was influenced by many kinds of factors in the process of electrodeposition. The film studied here was deposited at 20(?)C in a bath containing 1.3mol·L-1[Ni2+] and 3.74mol·L-1 [NO3-] in a solvent of 50 vol% ethanol. A cathodic current density of 5 mA/cm2 was applied for about 1h. The initial pH is about 7.5.(2) There are oxidative peak at -0.05V and reductive peak at 0.35V in the cyclic voltammetric curve of the sample that was calcined at 250(?)C or below, whereas there is no redox peak in the cyclic voltammetric curve of the sample that was calcined at 300(?)C. It has shown that oxide nickel is a suitable supercapacitor electrode material. In the potential window between 0 and 0.7V, the cyclic voltammetric curve shows the character of capacitior: the square-like shape. The sample should be calcined at 300(?)C or above for at least lh. Otherwise, the redox peaks will appear on the cyclic voltammetric curve because of nickel hydroxide havenot transformed into nickel oxide completely.(3)The scan rate of cyclic voltammetry has effect on the specific capacitance of the electrode material. As the sample is sweeped from 0.02V/S to 0.05V/s, the decrease of capacitance is observed. It is not suitable to the rapid charge-discharge condition. So, how to prepare electrode materials which can perform high specific capacitance at a high scan rate is one of the study goals. On this aspect, the work should be improved still. If a electrode material can show high specific capacitance after many times of cyclic voltammetric scan, it is proved that this material is stability and has a long cycle life. The sample showed no obviouse decrease in specific capacitance after 200 cycles. The capacitance is a bit decrease after 500 cycles which is still above 100F/g.(4)The cyclic voltammetric curve of NiOx-CoOy shows lower redox peaks than that of pure CoO. Compared with the cyclic voltammetric curve of pure CoO, the potential window get broader and the specific capacitor decreased. Compared with MnO, there is not significant change in the specific capacitance of NiOx-MnOy. In the mixed system, the cyclic voltammetric curves show different peaks shapes and locations due to different electrolyte composition. The principle of scan range chosen is to get an approximate-rectangle curve. The specific capacitance of NiOx-CoOy is lower than that of pure CoO. In the Ni-Mn mixed system, the specific capacitance of the material get lower as the Mn2+ content in electrolyte get higher.