Electrodeposition of Ni-Mg alloys from 1-butyl-3-methylimidazolium chloride/glycerin eutectic-based ionic liquid

Abstract

The electrodeposition of Ni-Mg alloys in 1-butyl-3-methylimidazolium chloride/glycerin (BMIC/GL, 1:1 M ratio) eutectic-based ionic liquid containing 0.1 M MgCl₂ and 0.05 M NiCl₂ was investigated. It is found by cyclic voltammograms and analysis of the chronoamperometric transient that Mg can be co-deposited with Ni under the inducement effect of Ni in this solvent, and the co-electrodeposition of Ni and Mg on a glassy carbon electrode is a diffusion-controlled process, which follows an instantaneous nucleation and three-dimensional growth pattern. In addition, the composition, surface morphology, structure, and property for hydrogen storage of Ni-Mg alloy deposits were characterized by inductively coupled plasma atomic emission spectrometry (ICP-AES), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopic (SEM), and charge and discharge test, respectively. The deposition potential plays a central role in controlling the composition, surface morphology as well as the electrochemical hydrogen storage capacity of the resultant Ni-Mg alloys. The alloy obtained at −1.2 V (vs. Ag) is a two-phase mixture consisting of a solid solution and an amorphous phase, which exhibits the best electrochemical capacity of 81.6 mAh g⁻¹.