Model anodes and anode models for understanding the mechanism of hydrogen oxidation in solid oxide fuel cells

Model anodes and anode models for understanding the mechanism of hydrogenoxidation in solid oxidefuelcells

Wolfgang G. Bessler,*^ab Marcel Vogler,^ab Heike Störmer,^c Dagmar Gerthsen,^c Annika Utz,^d André Weber^d and Ellen Ivers-Tiffée^de

Author affiliations

* Corresponding authors

^a German Aerospace Center (DLR), Institute of Technical Thermodynamics, Pfaffenwaldring 38-40, 70569 Stuttgart, Germany
E-mail: wolfgang.bessler@dlr.de
Tel: +49 711 6862603

^b University of Stuttgart, Institute of Thermodynamics and Thermal Engineering (ITW), Pfaffenwaldring 38-40, 70569 Stuttgart, Germany

^c Laboratorium für Elektronenmikroskopie (LEM), Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany

^d Institut für Werkstoffe der Elektrotechnik (IWE), Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany

^e DFG Center for Functional Nanostructures (CFN), Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe, Germany

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 H₂/H₂O 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_H₂ = 8×10² – 9×10⁴ Pa, p_H₂O = 2×10¹ – 6×10⁴ 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.

Article information

https://doi.org/10.1039/C0CP00541J

Article type

Perspective

Submitted

12 May 2010

Accepted

20 Jul 2010

First published

31 Aug 2010

Download Citation

Phys. Chem. Chem. Phys., 2010,12, 13888-13903

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