The Effect of MgO‐MgF 2 Synthesis Method on the Electrolyte Binding Ability in Thermal Batteries

This paper describes a comparative study of synthesis (sol‐gel and suspension methods) of MgF 2 ‐MgO material used as an immobilizing agent of the electrolyte (KCl‐LiCl‐RbCl) for high temperature cells. Samples containing 20 mol.% MgF 2 obtained by the sol‐gel method, followed by calcination at 500 and 600 o C, were characterized by large specific surface areas greater than those of samples obtained by the suspension method. It was demonstrated that pellets containing 40 wt.% immobilizing agent composed of 20 mol.% MgF 2 – 80 mol.% MgO, obtained by the sol‐gel method, and calcinated at 500 °C, were good electrolyte immobilizers. This mixture remains dimensionally stable at 400 °C and under 60 kPa pressure (no leakage of the electrolyte was observed) and reveals good ionic conductivity during tests in a model cell ‐ the voltage was not less than 1.0 V and current more than 0.75 A for approximately 400 s.