Optimized La0.6Sr0.4CoO3–δ Thin-Film Electrodes with Extremely Fast Oxygen-Reduction Kinetics



La0.6Sr0.4CoO3–δ (LSC) thin-film electrodes are prepared on yttria-stabilized zirconia (YSZ) substrates by pulsed laser deposition at different deposition temperatures. The decrease of the film crystallinity, occurring when the deposition temperature is lowered, is accompanied by a strong increase of the electrochemical oxygen exchange rate of LSC. For more or less X-ray diffraction (XRD)-amorphous electrodes deposited between ca. 340 and 510 °C polarization resistances as low as 0.1 Ω cm2 can be obtained at 600 °C. Such films also exhibit the best stability of the polarization resistance while electrodes deposited at higher temperatures show a strong and fast degradation of the electrochemical kinetics (thermal deactivation). Possible reasons for this behavior and consequences with respect to the preparation of high-performance solid oxide fuel cell (SOFC) cathodes are discussed.