Divalent magnesium ion conducting characteristics in phosphate based solid electrolyte composites

Abstract

The divalent Mg2+ ion conducting solid electrolyte was synthesized with a composite form by intentionally changing the starting material mixing ratio to the nonstoichiometric region. By such a preparation technique, spontaneous and microscopic dispersion of the secondary Zr2O(PO4)2 phase was successfully realized and the Mg2+ ion conductivity was considerably enhanced by dispersing the secondary phase, showing the highest conductivity among the Mg2+ ionic conducting solid electrolytes reported. The Mg2+ migration in the composite solid was clearly demonstrated by dc electrolysis and the Mg2+ ion transference number was precisely determined to be unity by a modified Tubandt method. The development of pure Mg2+ ion conducting phosphate based solid electrolytes with high stability and considerably high ionic conductivity contributes greatly to opening a new door for the application of advanced materials such as rechargeable batteries and other specific sensor elements.