Effect of Cu doping on the electrochemical properties and structural phases of La0.8Sr0.2Mn1 − xCuxO3 (0 ≤ x ≤ 0.2) at elevated temperature

•The addition of Cu to LSM increased the Mn4 + concentration.•The increased Mn4 + promoted the rhombohedral-to-cubic phase transformation.•The additional Mn4 + led to the generation of additional oxygen vacancies.•Cu doping improved the electrode performance of the LSM cathode.

The electrochemical properties of La0.8Sr0.2Mn1 − xCuxO3 (0 ≤ x ≤ 0.2)–Gd0.2Ce0.8O2 − δ (GDC) composite cathodes are determined in the intermediate-temperature range (600–850 °C), and their cathode performance is analyzed in the context of their phase transition behavior at elevated temperatures. The addition of Cu to LSM forces Mn3 + to Mn4 +, thereby increasing the Mn4 + concentration with increasing Cu doping. The increased Mn4 + concentration increases the cubic phase fraction, and thus enhances the low-temperature performance of the LSM cathode. The La0.8Sr0.2Mn0.8Cu0.2O3–GDC yields the greatest low-temperature cubic phase fraction and shows the smallest area specific resistance (0.49 Ω cm2 at 750 °C) of the compositions tested.