Electrochemical behavior of MgCl2 and co-deposition mechanisms of Mg and Sr in SrCl2−KCl−MgCl2 melt

The electrochemical behavior of MgCl2 and the co-deposition mechanisms of Mg and Sr in the SrCl2−KCl eutectic system were evaluated using various electrochemical techniques, including cyclic voltammetry (CV), square wave voltammetry (SWV), and open-circuit potential (OCP) analysis. It was observed the Mg(II) reduction on the tungsten electrode in SrCl2−KCl melt occurred in a single-step process involving the transfer of two electrons, exhibiting a quasi-reversible mode. The electrochemical co-deposition of Mg and Sr in the SrCl2−KCl−MgCl2 melt involved the formation of two types of Mg−Sr intermetallic compounds. The evolution in the co-deposition mechanism of the nucleation type with changing overpotential was explored through chronoamperometry (CA). It is shown that the nucleation pattern on the electrode surface was depended on the substrate materials and the electrode reaction products. Early-stage nucleation was attributed to Mg(II) reduction under all overpotential conditions. With the co-deposition of Mg and Sr, Mg(II) was reduced to form the Mg nucleus on the electrode surface, followed by underpotential deposition of Sr(II) on the Mg surface accompanied by Mg deposition simultaneously. Additionally, increasing MgCl2 concentration in the SrCl2−KCl melt resulted in a higher current density during the Mg−Sr co-deposition process.