Comparison of microstructural evolution of fuel electrodes in solid oxide fuel cells and electrolysis cells

M. Trini, A. Hauch, S. De Angelis, X. Tong, P. Vang Hendriksen, M. Chen*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

Solid oxide cells are electrochemical devices used for the conversion of chemical energy to electrical energy (Solid Oxide Fuel Cells-SOFC) and vice versa (Solid Oxide Electrolysis Cells-SOEC). However, long-term performance degradation impedes the widespread commercialization of the technology. To investigate the effects of operation mode on the degradation of Ni/yttria-stabilized zirconia (YSZ) electrodes, two cells from the same production batch are tested for 1000 h at 800 °C; one as SOFC and the other as SOEC. The cells are fed with the same gas composition at the fuel inlet side (p(H2O)/p(H2) = 0.5/0.5) while the direction of the current (±1 A cm−2) is reversed. It is found that Ni coarsening occurs to a similar extent in both operation modes while Ni depletion is only observed in SOEC mode, in the region close to the electrode/electrolyte interface. Here, the Ni/(Ni + Zr + Y) atomic ratio decreases from ~0.49 before operating the cell to ~ 0.28 and the SOEC shows a pronounced decrease in percolating triple phase boundaries (TPBs). The wettability of Ni on YSZ is studied and hypotheses are presented to correlate the phenomena of Ni coarsening and Ni depletion with the cell operation mode.
Original languageEnglish
Article number227599
JournalJournal of Power Sources
Volume450
Number of pages10
ISSN0378-7753
DOIs
Publication statusPublished - 2020

Keywords

  • Solid oxide cell
  • Fuel electrode
  • Ni-yttria stabilized zirconia
  • Microstructure
  • Coarsening
  • Depletion

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