Synthesis And Lithium Storage Electrochemical Performance Of ZnO/C Composites By Electrodeposition

Zinc oxide (ZnO) is a promising anode material for lithium-ion batteries. ZnO behaves alot of advantages such as high theoretical capacity, high security, and low cost. However, theproblems of ZnO, such as poor electrical conductivity and large volume expansion caused bycharge-discharge cycles, limit its application. In order to improve the the electrochemicalproperties of lithium storage in ZnO anode material, the morphology regulation of nanometerZnO and compositing materials with good electric conductivity were studied in the presentdissertation. We firstly investigated nanostructural ZnO using electrochemical depositionprocess, then studied C-ZnO layer composite thin film anode and C/ZnO powder anodematerials, and finally prepared the thin film athode with ZnO nano arrays by a combination ofelectrochemical deposition and electron beam lithography for the first time.The electrochemical deposition process for preparing nanostructural ZnO was firstlystudied, including the influence of electrochemical deposition process’s parameters on themicrostructure, such as working voltage, solution temperature and working electrode on themicrostructure of zinc oxide anode materials. The results indicate that the pureone-dimensional ZnO nanorods films on the copper foil surface could be obtained byelectrochemical deposition with1hour, under the condition of temperature80℃, and in theworking voltage values of-0.6V and-0.9V, respectively.The C-ZnO layer thin film composite electrodes were prepared by means of the coatedgraphite of copper foil as working electrode, and the electrochemical deposition process andelectrochemical properties of C-ZnO layer thin film composite electrode were studied.Compared with ZnO nano film materials, the electroconductivity of C-ZnO layer thin film isgreatly improved because of the composing with a good conductor layer of graphite. Whenthe ZnO content in the composite film materials increases, the irreversible capacity of the firsttime increased significantly, while the coulomb efficiency reduced, and its cycling stabilityalso reduced for the battery.We also obtained one-dimensional zinc oxide materials powders with morphology ofnanotubes and nanorods by electrochemical deposition process in the electrolyte. ZnO/Ccomposite anodes through a mixture of one-dimensional ZnO materials and graphite behave good electrical conductivity, and their electroconductivety are greatly better than that of ZnOnanorods anodes, but worse than that of ZnO-C layer anode. ZnO powders and graphitecomposite with different mass ratio of anode materials have been studied. The results showthat ZnO: C=2:8has a more stable discharge platform than the ZnO: C=4:6during thecycles; with the increase of ZnO content, the anode provides a large first charge and dischargecapacity, but also makes a loss of cycle stability performance.Finally, we studied the electron beam lithography for preparing the ZnO nano arrays.The ZnO nano arrays with different sizes have been successfully synthesized by means of theelectrochemical deposition and the electron beam lithography with the advantages of flexible,controllable, and high precision, and electrochemical deposition, which provides the basementfurther research and development to prepare the micro(nano)sized, shape controllable, andhigh performance ZnO/Cu film anodes.