Potassium ion conducting K1 − 2xCdxFeO2 solid electrolytes

New potassium ion conducting solid electrolytes based on potassium monoferrite have been prepared through partial substitution of the divalent cation Cd2+ on the potassium site, and their properties have been investigated. The introduction of cadmium cations sharply increases the electrical conductivity of KFeO2 over the entire temperature range studied. In addition to the maximum in conductivity at the boundary of the K1 − 2xCdxFeO2 solid solution, there is a maximum at a higher cadmium content (x = 0.30–0.35). The possible origins of this maximum are discussed.