Electrochemical formation of Al-Li Alloys by codeposition of Al and Li from LiCl-KCl-AlF₃ melts at 853 K

Abstract

The electrochemical behavior of Al(III) ions was studied in molten LiCl-KCl melts on a molybdenum electrode. Cyclic voltammetry, chronopotentiometry and chronoamperometry were used to explore the deposition mechanism of Al and Li. Cyclic voltammetry expriment indicates that under potential deposition(UPD) of lithium on pre-deposited aluminium led to the formation of liquid Al-Li alloys at 853 K. The diffusion coefficient of Al(III) ions at 853 K in LiCl-KCl-AlF₃(1%, mass fraction) melts was determined to be (2.79±0.05)×10⁻⁵ cm²/s. Chronopotentiograms and chronoamperograms demonstrate that the codeposition of Al(III) and Li(I) ions formed Al-Li alloys at cathodic current densities higher than −0.28 A/cm² or cathodic potentials more negative than −2.20 V. X-Ray diffraction( XRD) pattern indicates that Al-Li alloys with different phases formed via galvanostatic electrolysis. Inductively coupled plasma(ICP) analyses of the samples obtained by electrolysis show that lithium and aluminium contents of Al-Li alloys could be controlled by AlF3 concentration and current intensity.

Keywords

Electrochemistry / Al-Li alloy / Codeposition / Cyclic voltammetry

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