Mn valence state and electrode performance of perovskite-type cathode La 0·8 Sr 0·2 Mn 1 − x Cu x O 3 − δ ( x = 0, 0·2) for intermediate-temperature solid oxide fuel cells

Cu-free and Cu-doped LSM system, La 0·8 Sr 0·2 Mn 1 − x Cu x O 3 − δ ( x = 0, 0·2), with perovskite structure were prepared using an EDTA combined citrate process and the effects of Cu ion at B-site were investigated. Electrical conductivity and polarization resistance of the Cu-doped LSM were 210 S·cm − 1 at 750 °C, and 2·54 Ω · cm 2 at 800 °C, respectively which were better than those of the Cu-free LSM. This indicated that the electrode performance of LSM was improved by the addition of Cu. The oxidation state of Mn ions increased with addition of Cu. The increase in the oxidation state of Mn ions was due to the formation of Mn 4 + ions and oxygen vacancies. The addition of Cu ions to LSM systems could lead to enhanced electrode performance for oxygen reduction reactions originating from the change in valence of Mn ions.