MgO-MgF2 system obtained by sol–gel method as an immobilizing agent of the electrolyte applied in the high temperature cells

A MgF2-MgO system was tested as an immobilizing agent for the electrolyte KCl–LiCl–RbCl in high temperature cells. Samples of MgF2-MgO with different contents of MgF2 (0–20 mol%) were prepared by one-step sol-gel method in the reaction of magnesium methoxide dissolved in methanol with aqueous solution of hydrofluoric acid. The immobilizing agents were characterized by X-ray powder diffraction, low-temperature nitrogen adsorption and thermogravimetric measurements. Dimensional stability, mechanical strength and unfilled spaces were characterized using pellets containing 40 wt% of immobilizing agents. Finally, the pellets were used in an electric cell at 400 °C and the changes in current and voltage were recorded in time. The introduction of MgF2 to MgO in the synthesis by the sol-gel method significantly improves the textural and mechanical properties of immobilizing agent and ensures longer and more stable work of high temperature cell.