Study On The Electrochemical Deposition Behavior Of Magnesium Thin Films In Organic Solvents

Magnesium is known as the "Green engineering material of the21st century" because of its high theoretical capacity, low cost, environmental-friendly and absorbing a great amount of hydrogen, So magnesium has attracted more and more attention in many fields, especially in new type of green batteries, anode materials and hydrogen storage materials. Compared with other methods, electrochemical deposition have some advantages such as simple process, easy operation, vironmental safety, less energy consumption and flexible production mode, etc, so it is an economical preparation methods for thin film and suitable for industrial production. In this paper, some compact and bright magnesium films were successfully prepared by electrochemical deposition technology, and the morphology, microstructure and composition of magnesium films were characterized by using Scanning electron microscope (SEM), X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS).Anhydrous ethylmagnesium chloride in THF (EtMgCl/THF) was prepared as electrolyte, and the initial electrochemical deposition behavior of magnesium on the copper matrix was studied by Cyclic voltammetry. The results show that the deposition of magnesium film followed the mechanism of nucleation and subsequent grain growth.The effects of various parameters, including deposition time, electrolyte concentration and current density, on the electrochemical deposition behavior of magnesium were studied by using direct-current plating method. The results show that the Growth pattern of magnesium film on the copper matrix followed Volmer Veber, and the deposition thickness and density gradually increases with the increase of electrolyte concentration and current density. While when the thickness increases to a certain extent, various defects such as deformation, cracks, binding reduced, peeling are appeared between the layers because of the internal stress. The minimum grain size of the deposit was prepared at0.54M EtMgCl/THF and-5mA/cm2.The effects of various parameters, including deposition time, current density and pulse duty cycle on the electrochemical deposition behavior of magnesium were studied by using pulse-current plating method, and the electrocrystallization mechanism was investigated in this paper. The effect of constant current electrodeposition and pulse electrodeposition method on the behavior of magnesium electrodeposition was comparatively studied. The results suggest a preferential orientation parallel to a certain crystallographic planes during the nucleation and growth process of the Mg crystals. With the increases of pulse current density, the deposition rate and the hardness of films increase. For different current densities, the preferred orientations of crystal growth are different. The grain sizes of deposites are reduced with the decrease of pulse duty cycle.