New type of sodium ion conducting solid electrolyte based on lanthanum oxysulfate

A new type of sodium ion conducting solid electrolyte was prepared by forming a La2O2 SO4-Na2SO4 solid solution. Since the highly conductive Na2SO4-I phase was successfully preserved in the oxysulfate solid solution, the Na+ ion conductivity at 600 and 400degreesC, was enhanced more than 24 and 40 times, respectively, in comparison to those of pure Na2SO4. The oxysulfate solid solution has such a high durability at elevated temperatures as high as 1000degreesC and also shows a high Na+ ion conductivity down to room temperature by preserving the high Na+ ion conductive Na2SO4 I phase in the La2O2SO4 framework, the present new Na+ ion conducting solid electrolyte is greatly expected to be applied in various fields. (C) 2002 The Electrochemical Society.