Solid potassium-cation-conducting electrolytes in the K1−2x BaxFeO2 and K1−2x PbxFeO2 systems

Abstract

Novel highly conductive potassium-cation solid electrolytes based on potassium monoferrite are synthesized via partial substitution of Ba2+ and Pb2+ for K+ and studied. Both additives lead to an abrupt increase in the conductivity of KFeO2. In the barium-containing system, the conductivity is slightly higher and the activation energy is somewhat lower. This can be explained by the effect of dimensional factor, because the Ba2+ cation is larger than the Pb2+ cation. The reasons for the conductivity increase in potassium monoferrite upon introducing the additives are the formation of potassium vacancies in the course of substitution K+ → M2+ + V’K and the extension of temperature range of existence of the high-temperature KFeO2 modification.