Phase Formation and Kinetics of Electrochemical Intercalation of Lithium into Intermetallic Compounds MgCd and MgCd3

Electrochemical intercalation of lithium into intermetallic compounds (IMC) MgCd and MgCd₃ out of propylene carbonate solutions of LiBF₄ is studied. According to chronopotentiometry data, during the intercalation, lithium forms compounds with cadmium: Li₃Cd on MgCd or LiCd and Li₃Cd on MgCd₃. Reactions of solid-phase substitution, which occur on the electrodes, are accompanied by the destruction of initial IMC and generation of magnesium atoms. Chronoamperometry of MgCd–(Li) and MgCd₃–(Li) shows the lithium intercalation to be limited by nonstationary diffusion of lithium in the solid phase. The lithium diffusion in MgCd is slower and that in MgCd₃is faster than in Cd. The calculated potential dependences of the diffusion coefficient for lithium in MgCd and MgCd₃ are linear in semilogarithmic coordinates.