Mn(Ⅱ)在LiCl-KCl-MgCl_2-MnCl_2熔盐体系中的电化学行为

Electrochemical Behavior of Mn(Ⅱ) in the Melt LiCl-KCl-MgCl_2-MnCl_2

采用循环伏安和计时电位等电化学技术研究了Mn(Ⅱ)在LiCl-KCl-MgCl2-MnCl2熔盐体系中的电还原过程和Mg-Li-Mn合金的共沉积条件.结果显示,在LiCl-KCl-MgCl2-MnCl2熔盐体系中,Mn(Ⅱ),Mg(Ⅱ)和Li(Ⅰ)的还原电位分别为-1.14,-1.78和-2.19 V.Mn先析出,在钼电极表面沉积;Mg在Mn上欠电位沉积生成Mg-Mn合金;而Li在Mg-Mn合金上欠电位沉积形成Mg-Li-Mn合金.实验结果表明,Mn(Ⅱ)在熔盐中的还原电极过程受扩散控制.Mn(Ⅱ)在熔盐中的扩散系数约为10-5 cm2/s.运用XRD技术对恒电流电解制备的Mg-Li-Mn合金进行了分析,结果表明,Mg-Li-Mn合金中含有β-Li,α-Mg和Mn 3个相.

The reduction of Mn（Ⅱ） on a molybdenum electrode in the melt LiCl-KCl-MgCl2-MnCl2 at 898 K and the conditions of the co-deposition of Mg-Li-Mn alloys were investigated.Cyclic voltammetry and chronopotentiometry show that the reductions of Mn（Ⅱ）,Mg（Ⅱ） and Li（Ⅰ） start at-1.14,-1.78 and-2.19 V,respectively.And the underpotential deposition of magnesium on pre-deposited manganese leads to the formation of a liquid Mg-Mn solution,then a liquid Mg-Li-Mn solution forms for the succeeding underpotential deposition of lithium on pre-deposited Mg-Mn.The diffusion coefficient of Mn（Ⅱ） in the melts was also calculated with different methods,which was about 10-5 cm2/s.The analysis of X-ray diffraction indicats that there are three phases（β-Li,α-Mg and Mn） in the Mg-Li-Mn alloy.