The effect of TiO2 coating on the electrochemical performance of ZnO nanorod as the anode material for lithium-ion battery

ZnO nanorods were coated with TiO2 thin film using the atomic layer deposition (ALD) process. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were used to characterize the crystal structure and surface morphology of the coated composites. Results of galvanostatic charge and discharge tests and cyclic voltammograms suggest that lithium ions can reversibly intercalate into and deintercalate from TiO2-coated ZnO nanorods, and that stable cycling behavior in an ethylene carbonate-based electrolyte can be achieved. The TiO2 coating is believed to reduce the degree of reaction electrodes have with the electrolyte during the charge-discharge process since the inactive coating layer prevents the electrode from having direct contact with the electrolyte. Furthermore, the one-dimensional nanorods provide a relatively higher surface area than those of their bulk form or thin film, which allows a much greater portion of atoms on the surface to undergo the electrochemical reaction. The electrochemical study indicates that the TiO2-coated ZnO nanorod arrays might be a candidate for the anode material in Li-ion batteries.