LSM–SDC electrodes fabricated with an ion-impregnating process for SOFCs with doped ceria electrolytes

(La0.85Sr0.15)0.9MnO3−δ (LSM)–Sm0.2Ce0.8O1.9(SDC) composite electrodes were fabricated for intermediate-temperature solid oxide fuel cells with a two-step fabricating process including screen-printing and ion-impregnating. The ion-impregnated LSM–SDC electrodes showed better performance than those fabricated with conventional techniques. At 700 °C, the interfacial polarization resistance was only 0.23 Ω cm2 for an ion-impregnated cathode, while it was 0.72 Ω cm2 for a sol-gel derived cathode and 0.75 Ω cm2 for a slurry-coated cathode. The performance was gradually improved by increasing the amount of impregnated SDC. Impedance spectroscopy was used to study the oxygen reduction kinetics within the LSM–SDC electrodes. Oxygen ion transfer, charge transfer and surface diffusion of oxygen ions were found to be possible rate-limiting steps for the high-frequency arc, intermediate-frequency arc, and low-frequency arc of the impedance spectra.