Impurity features in Ni-YSZ-H2-H2O electrodes

A. Utz, Karin Vels Hansen, Kion Norrman, E. Ivers-Tiffée, Mogens Bjerg Mogensen

    Research output: Contribution to journalJournal articleResearchpeer-review

    Abstract

    The impurity content of previously electrochemically characterized patterned Ni anodes for SOFC (solid oxide fuel cells) has been analyzed with a combination of SEM (scanning electron microscopy), AFM (atomic force microscopy), XPS (X-ray photoelectron spectroscopy) and TOF-SIMS (time-of-flight secondary ion mass spectrometry). This analysis yields comprehensive information on composition and lateral distribution of impurity species as well as the size of impurity features. Small impurity striations are found at the triple phase boundary (TPB) as well as on the former electrode–electrolyte interface and the impurity features were found to be influenced by the electrode configuration and the initial behavior of the Ni electrode during thermal exposure (creep or shrinkage).Furthermore, the electrochemical performance (the line specific resistance LSR) was compared to data reported for Ni point anodes. Good agreement was obtained for data with comparable impurity features.Additionally, an order of magnitude estimation of the effect of SiO2 content on surface coverage with an impurity film is performed for different electrode designs (point, patterned and cermet anode) and shows different preconditions for model anodes and nano- or microstructured cermet anodes. With typical impurity levels, a complete coverage of the electrolyte surface with SiO2 seems almost inevitable in the case of model anodes.
    Original languageEnglish
    JournalSolid State Ionics
    Volume183
    Issue number1
    Pages (from-to)60-70
    ISSN0167-2738
    DOIs
    Publication statusPublished - 2011

    Keywords

    • Solid Oxide Fuel Cells

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