title: Model anodes and anode models for understanding the mechanism of hydrogen oxidation in solid oxide fuel cells.
abstract: This article presents a literature review and new results on experimental and theoretical investigations of the electrochemistry of solid oxide fuel cell (SOFC) model anodes, focusing on the nickel/yttria-stabilized zirconia (Ni/YSZ) materials system with operation under H(2)/H(2)O atmospheres. Micropatterned model anodes were used for electrochemical characterization under well-defined operating conditions. Structural and chemical integrity was confirmed by ex situ pre-test and post-test microstructural and chemical analysis. Elementary kinetic models of reaction and transport processes were used to assess reaction pathways and rate-determining steps. The comparison of experimental and simulated electrochemical behaviors of pattern anodes shows quantitative agreement over a wide range of operating conditions (p(H(2)) = 8×10(2) - 9×10(4) Pa, p(H(2)O) = 2×10(1) - 6×10(4) Pa, T = 400-800 °C). Previously published experimental data on model anodes show a strong scatter in electrochemical performance. Furthermore, model anodes exhibit a pronounced dynamics on multiple time scales which is not reproduced in state-of-the-art models and which is also not observed in technical cermet anodes. Potential origin of these effects as well as consequences for further steps in model anode and anode model studies are discussed.
authors.affiliation: German Aerospace Center (DLR), Institute of Technical Thermodynamics, Pfaffenwaldring 38-40, 70569 Stuttgart, Germany. wolfgang.bessler@dlr.de
authors.forename: Wolfgang G
authors.initials: WG
authors.lastname: Bessler
authors.forename: Marcel
authors.initials: M
authors.lastname: Vogler
authors.forename: Heike
authors.initials: H
authors.lastname: Störmer
authors.forename: Dagmar
authors.initials: D
authors.lastname: Gerthsen
authors.forename: Annika
authors.initials: A
authors.lastname: Utz
authors.forename: André
authors.initials: A
authors.lastname: Weber
authors.forename: Ellen
authors.initials: E
authors.lastname: Ivers-Tiffée