Electrochemical formation of Mg-La-Mn alloys by coreduction of Mg(II), La(III) and Mn(II) in LiCl+KCl molten salts

Abstract In the present work, cyclic voltammetry (CV), square wave voltammetry (SWV) and chronopotentiometry(CP) were used to investigate the electrochemical coreduction behaviors of La(III) and Mg(II) as well as La(III), Mg(II) and Mn(II) on Mo electrode in LiCl+KCl molten salts. CV and SWV results exhibited that the coreduction mechanism of La (III) and Mg(II) on Mo electrode is La(III) to be reduced and formed Mg-La intermetallic compound, leading to the deposition potential of La(III) shifts to more positive one. The electrochemical signals pertaining to the formation of metallic La, Mg and Mn as well as Mg-La intermetallic compound were also observed by coreduction of La(III), Mg(II), and Mn(II) in LiCl+KCl molten salt on the inert Mo electrode. However, the electrochemical signal associated with the formation of La-Mn and Mg-Mn alloys were not observed, which meant the depolarization effect of La(III) and Mg(II) does not occur on pre-deposited Mn electrode. The Mg-La-Mn alloys were formed by co-deposition of La(III), Mg(II), and Mn(II) on Mo electrode at various concentration ratios of La(III) and Mg(II). The results of scanning electron microscopy equipped with energy dispersive spectroscopy and X-ray diffraction displayed that the Mg-La-Mn alloys were comprised of La-Mg compound Mg17La2, Mg and Mn phases. The concentration ratio of La(III) and Mn(II) has few effects on the alloy composition.