Preparation And Electrochemical Performance Study Of Porous Nickel Oxide Thin Films

With the rapid development of global economy and the continuous growth of the population throughout the world, as well as the rapid expanded market of the portable electronic devices and hybrid vehicles, the consumption of global energy grows at an alarming rate. Thus, to develop advanced, low-cost, environmental friendly energy conversion and storage devices is as important as the development of clean, renewable and sustainable alternative energy(solar energy, wind energy, tidal power).The main advantages of the supercapacitors include large capacity, long cycle life, high energy density and high specific power density and non-toxicity toward environment. In addition, the high power density, good stability and low maintenance cost make it become the research hotspot in the field of chemical power source and lightspot of emerging industry. All of these excellent properties of supercapacitors promote their extensive application prospect in grid-connected renewable energy, electric vehicles, aerospace and other fields. Electrode materials play a main role in all of the related elements that can influence the performance of supercapacitor. Therefore, the development of environmental friendly and inexpensive electrode material is the key to solve the problem.In this paper, the structure of electrode materials was controlled by optimizing the synthesis conditions. The nickel oxide film with porous structure were synthesized and applied in the electrode materials. The main research contents are as follows:Typically, the transition metal element nickel has multiple oxidation states, When used as supercapacitor electrode materials, it can involve in redox reaction in the electrolyte(oxidation state between vice versa) and store charge. Nickel oxide has the advantages of high theoretical specific capacitance, environmental friendly, etc. However, its poor electrical conductivity, low electrochemical utilization rate of large electrical flow and poor-rate performance limited their practical application.In this paper, the nickel oxide film with porous structure was obtained by the hydrothermal and heat treatment method, using nickel nitrate as the source of nickel, ethylenediamine tetraacetic acid(EDTA) as the structure-directing agent and fluorine doped tin oxide conductive glass(FTO) as current collector. The effects of different solvothermal reaction time, different calcination temperature and the presence or absence of structure-directing agent EDTA on nickel oxide film morphology and electrochemical properties of the final samples were investigated. The scanning electron microscope(SEM) photos showed that the obtained film was composed of many complexed nanometer sheets. The capacitance can reach 651.6 F·g-1 at a current density of 2 A·g-1, and it can be maintained 71.6% of the initial value after 1000 cycle circle. High energy density of 21.67 Wh ·kg-1 can also be achieved. The good performance of the nickel oxide film comes from the open channel structure, which is favorable for the contact between the electrolyte ion and the active material, increasing the utilization ratio of the material accordingly.This result proves the feasibility of application of nickel based materials for capacitors in theory, and provides new opportunities for nickel based materials for new energy storage system...