Polarization resistance and composite cathode of Ce doped SrMnO3 system for intermediate temperature solid oxide fuel cells

• The addition of Ce to SrMnO3 increased the Mn3+ concentration.
• The increased Mn3+ caused the lattice volume expansion.
• The addition of Ce ions led to impede the formation of oxygen vacancies.
• Composite cathode with Sm0.2Ce0.8O2 presented the higher electrode performance than SCM.

Sr1 − xCexMnO3 (SCM, x = 0.1, 0.2, 0.3) materials synthesized through the EDTA citrate complexing process show a single perovskite structure, and the refined lattice volume increases with the concentration of Ce ions. An increase in the Mn3 + concentration with increasing Ce doping was confirmed by Mn L3,2-edge analysis, and we observe an expansion of the lattice volume due to the larger ionic radii of Mn3 +, as compared to that of Mn4 +. The change in the O K-edge caused by increasing Ce content presented an increase in the binding force of the oxygen ions. We hypothesize that the decrease in oxygen vacancy concentration caused by the increase in the oxygen binding force impedes the oxygen ion transfer process, which causes an increase in the polarization resistance (Rp) with the increasing concentration of Ce ions in the SCM system. The Rp value of Sr1− xCexMnO3/Sm0.2Ce0.8O2 (SCM/SDC) composite cathodes was lower than that of pure SCM cathodes at the measured temperature, especially the Rp value of SCM10/SDC (0.88 cm2 at 800 °C), which is about seven times lower than that of SCM10 at the same temperature.