Fabrication of LiYO2 Galvanic Cells to Determine the Thermodynamic Properties of Lithium Alloys

Abstract

<p> LiYO2 is a lithium ion conductor stable to pure lithium metal. The goal of the present work was to design and construct an electrochemical cell and demonstrate the use of LiYO2 as an electrolyte since this has never been previously done. The electrolyte was fabricated by slip casting in powder molds. A Y2O3-MgO composition was identified and used to fabricate a lid for the cell. Impervious cells were obtained by liquid phase joining and sintering techniques. Heating rate was found to be a key parameter in the success of this procedure. The cell was evaluated in terms of stability as a sensor and chemical pump by measuring EMF for two different Li-Zn alloys between 250 and 600°C. The configuration was as follows: (RE) (-) Ta Li,Sn | LiYO2 | Li,Zn Ta (+) (WE)</p> <p> The cell showed no significant attack after 40 days working with pure lithium. Stability and reproducibility of EMF values was obtained for the concentrations of Li studied. Solidus and liquidus temperatures were determined for the 5 and 10 mol% Li compositions in good agreement with published phase diagrams. Variations of EMF with respect to temperature or concentration followed the expected thermodynamic relationships. Results indicate that the LiYO2 electrolyte cell could be useful in assessment of the thermodynamics of lithium alloys.</p>