Degradation mechanisms of SOFC anodes in coal gas containing phosphorus

O. A. Marina, C. A. Coyle, E. C. Thomsen, D. J. Edwards, G. W. Coffey, L. R. Pederson

Research output: Contribution to journalArticle

48 Citations (Scopus)

Abstract

The interaction of phosphorus in synthetic coal gas with the nickel-based anode of solid oxide fuel cells has been investigated. Tests with both anode-supported and electrolyte-supported button cells were performed at 700 to 800 °C in synthetic coal gas containing 0.5 to 10 ppm phosphorus, which was introduced as phosphine. Two primary modes of degradation were observed. The most obvious was the formation of a series of bulk nickel phosphide phases, of which Ni3P, Ni5P2, Ni12P5 and Ni2P were identified. Phosphorus was essentially completely captured by the anode, forming a sharp boundary between converted and unconverted anode portions. These products partially coalesced into large grains, which eventually affected electronic percolation through the anode support. From thermodynamic calculations, formation of the first binary nickel phosphide phase is possible at phosphorus concentrations < 1 ppb in coal gas at typical fuel cell operating temperatures. A second mode of degradation is attributed to surface diffusion of phosphorus to the active anode/electrolyte interface to form an adsorption layer. Direct evidence for the presence of such an adsorption layer on nickel was obtained by surface spectroscopies on fracture surfaces. Further, cell performance losses were observed well before the entire anode was converted to bulk nickel phosphide. Impedance spectroscopy revealed that these losses were primarily due to growth in electrodic resistance, whereas large ohmic increases were visible when the entire anode was converted to nickel phosphide phases. The rate of resistance growth for anode-supported cells showed a low dependence on phosphorus concentration, attributed to phosphorus activity control within the anode by bulk nickel phosphide products.

Original languageEnglish
Pages (from-to)430-440
Number of pages11
JournalSolid State Ionics
Volume181
Issue number8-10
DOIs
Publication statusPublished - 29 Mar 2010
Externally publishedYes

Fingerprint

Coal gas
Solid oxide fuel cells (SOFC)
coal
Phosphorus
phosphorus
Anodes
anodes
Nickel
degradation
phosphides
Degradation
nickel
gases
phosphine
Electrolytes
electrolytes
cell anodes
buttons
Spectroscopy
adsorption

Keywords

  • Coal gas
  • Contaminant
  • Ni/YSZ anode
  • Nickel phosphide
  • Nickel phosphorus interaction
  • SOFC

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Chemistry(all)

Cite this

Marina, O. A., Coyle, C. A., Thomsen, E. C., Edwards, D. J., Coffey, G. W., & Pederson, L. R. (2010). Degradation mechanisms of SOFC anodes in coal gas containing phosphorus. Solid State Ionics, 181(8-10), 430-440. https://doi.org/10.1016/j.ssi.2010.01.018

Degradation mechanisms of SOFC anodes in coal gas containing phosphorus. / Marina, O. A.; Coyle, C. A.; Thomsen, E. C.; Edwards, D. J.; Coffey, G. W.; Pederson, L. R.

In: Solid State Ionics, Vol. 181, No. 8-10, 29.03.2010, p. 430-440.

Research output: Contribution to journalArticle

Marina, OA, Coyle, CA, Thomsen, EC, Edwards, DJ, Coffey, GW & Pederson, LR 2010, 'Degradation mechanisms of SOFC anodes in coal gas containing phosphorus', Solid State Ionics, vol. 181, no. 8-10, pp. 430-440. https://doi.org/10.1016/j.ssi.2010.01.018
Marina OA, Coyle CA, Thomsen EC, Edwards DJ, Coffey GW, Pederson LR. Degradation mechanisms of SOFC anodes in coal gas containing phosphorus. Solid State Ionics. 2010 Mar 29;181(8-10):430-440. https://doi.org/10.1016/j.ssi.2010.01.018
Marina, O. A. ; Coyle, C. A. ; Thomsen, E. C. ; Edwards, D. J. ; Coffey, G. W. ; Pederson, L. R. / Degradation mechanisms of SOFC anodes in coal gas containing phosphorus. In: Solid State Ionics. 2010 ; Vol. 181, No. 8-10. pp. 430-440.
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