Study on the preparation of Mg–Li–Zn alloys by electrochemical codeposition from LiCl–KCl–MgCl 2–ZnCl 2 melts

Abstract

Electrochemical codeposition of Mg, Li, and Zn on a molybdenum electrode in LiCl–KCl–MgCl 2–ZnCl 2 melts at 943 K to form Mg–Li–Zn alloys was investigated. Cyclic voltammograms (CVs) showed that the potential of Li metal deposition, after the addition of MgCl 2 and ZnCl 2, is more positive than the one of Li metal deposition before the addition. Chronopotentiometry measurements indicated that the codeposition of Mg, Li, and Zn occurs at current densities lower than −0.78 A cm −2 in LiCl–KCl–MgCl 2 (8 wt.%) melts containing 1 wt.% ZnCl 2. Chronoamperograms demonstrated that the onset potential for the codeposition of Mg, Li, and Zn is −2.000 V, and the codeposition of Mg, Li, and Zn is formed when the applied potentials are more negative than −2.000 V. X-ray diffraction (XRD) indicated that Mg–Li–Zn alloys with different phases were prepared via galvanostatic electrolysis. The microstructure of typical α + β phase of Mg–Li–Zn alloy was characterized by optical microscope (OM) and scanning electron microscopy (SEM). The analysis of energy dispersive spectrometry (EDS) showed that the elements of Mg and Zn distribute homogeneously in the Mg–Li–Zn alloy. The results of inductively coupled plasma analysis showed that the chemical compositions of Mg–Li–Zn alloys are consistent with the phase structures of the XRD patterns, and that the lithium and zincum contents of Mg–Li–Zn alloys depend on the concentrations of MgCl 2 and ZnCl 2.