Alloy formation processes at electrochemical intercalation of lithium into intermetallic compounds of magnesium with zinc

摘要

A comparative study of alloy formation processes that occur during the electrochemical intercalation of lithium from lithium chloride solutions in dimethylformamide into intermetallic compounds of magnesium with zinc (MgZn2, Mg2Zn3) and the corresponding individual metals is studied by chronopotentiometric and voltammetric methods. Lithium-containing phases are formed in all samples studied; moreover, for MgZn2 and Mg2Zn3 electrodes, the phases formed are preferentially in the Li-Zn system. The largest number of lithium-containing phases is formed in zinc. It is shown that the electrochemical behavior of intermetallic electrodes is associated with their nature, where a single alloy component plays the key role, namely, zinc for MgZn2 and magnesium for Mg2Zn3. The cathodic intercalation of lithium into MgZn2 is characterized by anomalously low polarizability as compared with the other electrodes. The lithium extraction coefficient K-ex(Li) increases from the first to the tenth cycle for all electrode studied. The highest K-ex(Li) are typical of Zn and the lowest are typical of Mg2Zn3.