Determination of the reaction zone in gadolinia-doped ceria anode for solid oxide fuel cell

Takashi Nakamura, Keiji Yashiro, Atsushi Kaimai, Takanori Otake, Kazuhisa Sato, Tatsuya Kawada, Junichiro Mizusaki

Research output: Contribution to journalArticlepeer-review

54 Citations (Scopus)

Abstract

In order to elucidate the reaction zone in porous Ce0.9Gd 0.1 O1.95-δ anodes on yttria-stabilized zirconia (YSZ), ac impedance and steady-state polarization measurements are carried out in H2 - H2 O-Ar gas mixtures with different electrode thicknesses, 7, 20, and 45 μm anodes. Steady-state polarization current becomes larger as the electrode becomes thicker, while the current per unit surface area shows similar value. Therefore, the current seems to be a function of the electrode surface area. In ac impedance measurements, an extremely large pseudo-capacitance is observed to be as large as 105 - 106 μF cm-2. The measured pseudo-capacitance is caused by the nonstoichiometric perturbation of the oxygen content in the anode material. Both steady-state polarization and ac impedance measurements suggest that the reaction zone extends from the interface of YSZ/porous Ce0.9Gd 0.1 O1.95-δ anodes toward the outer gas phase. The distribution of electrochemically active zone is semiquantitatively estimated. The activity for the surface reaction gradually decreases with increasing the distance from the electrode/electrolyte interface, and the reduction rate of the activity becomes high as the electrode thickness increases.

Original languageEnglish
JournalJournal of the Electrochemical Society
Volume155
Issue number12
DOIs
Publication statusPublished - 2008 Nov 4

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry

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