电解质组成对氯化物体系熔盐电解Mg-La合金的影响（英文）

在Mg Cl2-LaCl3-KCl熔盐体系中,系统研究了恒电位电解过程中,电解质组成对平均电解电流、电解效率和合金成分的影响。用XRD、SEM和EDS对Mg-La合金样品进行了表征。随着初始电解质中LaCl3浓度的增加,平均电解电流逐渐降低。这是由于与Mg Cl2相比,LaCl3较低的电导率引起的。当LaCl3在初始电解质中的浓度为15%～20%（质量分数）时,电流效率超过90%。合金组成可通过改变电解质组成来调节。

Effect of oxide and fluoride addition on electrolytic preparation of Mg-La alloy in chloride molten salt

Mg-La alloys were prepared by constant voltage electrolysis in the molten salt system of MgC12-LaC13-KC1 at 750℃, with a graphite crucible as the anode and a tungsten rod as the cathode. The effect of oxide and fluoride addition on the electrolysis was investigated comprehensively. X-ray diffraction （XRD） was used to characterize some of the Mg-La alloy products and the sludges. As the content of MgO or La203 in the electrolyte increased, both the current efficiency and the mass of alloy product decreased, indicating that both MgO and La203 may take part in the reactions in the electrolyte. When the same mass of the oxide was added, compared with La203, MgO had a more pronounced effect on both the current efficiency and the mass of alloy product. XRD studies confirmed the formation of LaOC1 when MgO or LazO3 was added into the electrolyte. The formation of LaOCl sludge would be the main reason for the negative effect of the oxide addition on both the current efficiency and the mass of alloy. In the electrolytic system, the addition of CaF2 was not helpful to suppress the negative effect of MgO on the electrolysis, probably due to the complex reactions of the La compounds in the electrolyte.

Preparation of Mg-Li-La alloys by electrolysis in molten salt

An electrochemical method was used to prepare Mg-Li-La alloys in a molten LiCl-KCl-KF-MgCl2 containing La2O3 at 943 K. The results showed preparation of Mg-Li-La alloys by electrolysis is feasible. The Mg-Li-La alloys were analyzed by means of X-ray diffraction （XRD）, optical micrograph （OM） and scanning electron microscopy （SEM）. XRD analysis indicates that α＋Mg17La2, α＋β＋Mg17La2 and β＋LaMg3 Mg-Li-La alloys with different lithium and lanthanum contents were obtained via galvanostatic electrolysis. The microstructures of typical α＋Mg17La2 and β＋LaMg3 phases of Mg-Li-La alloys were characterized by optical microscopy （OM） and scanning electron microscopy （SEM）. The analysis of energy dispersive spectrometry （EDS） shows that the element of Mg distributes homogeneously in the Mg-Li-La alloy and the element of La mostly exists at grain boundaries to restrain the grain growth rate due to the larger ionic radius and lower electronegativity compared with Mg.

Corrosion and discharge behavior of Mg−xLa alloys(x=0.0−0.8) as anode materials

The corrosion and discharge performances of binary Mg−xLa(x=0.2−0.8,wt.%)alloys as anode materials for Mg-based batteries were evaluated.Microstructure,hydrogen evolution,mass loss,electrochemical behavior,and half-cell discharge capabilities were characterized.The results show that the corrosion rate of the Mg matrix was decreased by alloying with La,and this could be attributed to the formation of a protective La2O3-containing film on the surface of the alloy.The Mg−0.2La alloy displayed the lowest corrosion rate,i.e.,2.4 mm/a in a 3.5 wt.%NaCl solution,Furthermore,the discharge performance of Mg−0.4La alloy was superior to that of pure Mg and other Mg−La alloys;this could be associated with the modified microstructure of the Mg−0.4La alloy,which decreased the self-corrosion and accelerated the detachment of the discharge products.

Discharge performance of Mg-Al-Pb-La anode for Mg-air battery

b The discharge performance of Mg-Al-Pb-La anode was investigated by electrochemical techniques and compared withthat of Mg-Al-Pb alloy. The results indicate that the Mg-Al-Pb-La anode provides enhanced corrosion resistance at open circlepotential, and exhibits better discharge activity than the Mg-Al-Pb alloy. The utilization efficiency of Mg-Al-Pb-La anode ishigher than that of commercial Mg-Al-Zn （AZ） and Mg-Al-Mn （AM） alloys. A single Mg-air battery with Mg-Al-Pb-La alloy asthe anode and air as the cathode has an average discharge potential of 1.295 V and a discharge capacity of 1370 mA·h/g duringdischarge at 10 mA/cm2, which is higher than that of batteries using Mg-Li anodes. The enhancement in discharge performance ofthe Mg-Al-Pb-La anode is caused by its modified microstructure, which reduces the self-corrosion and accelerates the spalling ofoxidation products during battery discharge. Furthermore, the dissolution mechanism of Mg-Al-Pb-La anode during the dischargeprocess was analyzed.