Effect of direct-current operation on the electrochemical performance and structural evolution of Ni-YSZ electrodes

Qinyuan Liu, Qian Zhang, Peter W. Voorhees, Scott A. Barnett*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

The effect of electrolysis operations on Ni-YSZ fuel electrode stability was studied at different current densities and fuel mixtures during 1000 h life tests. For a typical electrolysis mixture of 50% H2/50% H2O and 0.6 A cm−2 current density, cell ohmic resistance values were reasonably stable and no structural changes occurred. However, for more reducing conditions (97% H2/3% H2O), increasing the current density above 0.4 A cm−2 increased the ohmic resistance accompanied by significant electrolyte degradation including fracture and void formation at grain boundaries. Numerical analysis was carried out to determine the effective oxygen partial pressure across the electrolyte. The results show that the oxygen partial pressure values at high current density and low steam content may be low enough to reduce zirconia to form a Ni-Zr alloy product, initiating the observed electrolyte structural degradation.

Original languageEnglish (US)
Article number014006
JournalJPhys Energy
Volume2
Issue number1
DOIs
StatePublished - Jan 2020

Keywords

  • Degradation
  • Life tests
  • Ni-YSZ
  • Solid oxide fuel cell

ASJC Scopus subject areas

  • Energy(all)
  • Materials Chemistry
  • Materials Science (miscellaneous)

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