Accelerated degradation of yttria stabilized zirconia electrolyte during high-temperature water electrolysis

Aziz Nechache (Corresponding Author), Bernard A. Boukamp, Michel Cassir, Armelle Ringuedé (Corresponding Author)

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

The accelerated degradation of a commercial LSCF/YDC/YSZ/Ni-YSZ solid oxide electrolyzer cell (La0.6Sr0.4Co0.2Fe0.8O3-δ/Y0.1CeO1.95/Y0.08Zr0.92O1.96/Ni-YSZ) contaminated by Si-containing impurities is studied with time under up to − 1.7 A cm−2 applied. Above ~ − 0.6 A cm−2, a new region appears in the polarization curve. This region corresponds to electronic conduction in the yttria-stabilized zirconia (YSZ) electrolyte, induced by the reduction under high current conditions. A shift in the typical frequencies (relaxation times) toward lower frequencies is then observed for the entire impedance spectra. This shift results finally in the disappearance of the positive loop related to the polarization resistance and the appearance of a negative (inductance type) loop which crosses the real axis (Z’) at the lowest frequencies to become positive again. This is characteristic for an electrode process mode in which the electrochemical redox reactions vanish while the cell current becomes mainly electronic due to the reduction of the YSZ electrolyte. This trend increases with time. Such a characterization of the electronic conduction of the YSZ electrolyte by electrochemical impedance spectroscopy has not been reported to date under electrolysis mode, to the best of our knowledge. Post-mortem analysis by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDX) shows detrimental degradation of the electrolyte after only 360 h of overall testing duration with numerous micropores in the YSZ volume, and cracks and delamination at the yttria-doped ceria (YDC)/YSZ interface. EDX analysis reveals (i) a migration of La, Sr, Co, and Fe elements from lanthanum strontium cobalt ferrite (LSCF) anode to YDC layer and YSZ electrolyte and (ii) a very important shift of Ni from Ni-YSZ cathode to YSZ and YDC, and also to LSCF anode in a lower proportion. This study highlights the critical issue that impurities represent for solid oxide electrolysis cell operation.

Original languageEnglish
Pages (from-to)871-881
Number of pages11
JournalJournal of solid state electrochemistry
Volume23
Issue number3
DOIs
Publication statusPublished - 1 Mar 2019

Fingerprint

Yttria stabilized zirconia
electrolysis
yttria-stabilized zirconia
Electrolysis
Electrolytes
electrolytes
degradation
Degradation
Water
water
Yttrium oxide
Cerium compounds
Lanthanum
Strontium
Temperature
Regenerative fuel cells
lanthanum
strontium
Ferrite
ferrites

Keywords

  • Degradation
  • Electrochemical impedance spectroscopy
  • Electrolyte electronic conduction
  • Hydrogen
  • Solid oxide electrolysis cell
  • Yttria stabilized zirconia

Cite this

@article{9308738f092140a9873b65101161bdfa,
title = "Accelerated degradation of yttria stabilized zirconia electrolyte during high-temperature water electrolysis",
abstract = "The accelerated degradation of a commercial LSCF/YDC/YSZ/Ni-YSZ solid oxide electrolyzer cell (La0.6Sr0.4Co0.2Fe0.8O3-δ/Y0.1CeO1.95/Y0.08Zr0.92O1.96/Ni-YSZ) contaminated by Si-containing impurities is studied with time under up to − 1.7 A cm−2 applied. Above ~ − 0.6 A cm−2, a new region appears in the polarization curve. This region corresponds to electronic conduction in the yttria-stabilized zirconia (YSZ) electrolyte, induced by the reduction under high current conditions. A shift in the typical frequencies (relaxation times) toward lower frequencies is then observed for the entire impedance spectra. This shift results finally in the disappearance of the positive loop related to the polarization resistance and the appearance of a negative (inductance type) loop which crosses the real axis (Z’) at the lowest frequencies to become positive again. This is characteristic for an electrode process mode in which the electrochemical redox reactions vanish while the cell current becomes mainly electronic due to the reduction of the YSZ electrolyte. This trend increases with time. Such a characterization of the electronic conduction of the YSZ electrolyte by electrochemical impedance spectroscopy has not been reported to date under electrolysis mode, to the best of our knowledge. Post-mortem analysis by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDX) shows detrimental degradation of the electrolyte after only 360 h of overall testing duration with numerous micropores in the YSZ volume, and cracks and delamination at the yttria-doped ceria (YDC)/YSZ interface. EDX analysis reveals (i) a migration of La, Sr, Co, and Fe elements from lanthanum strontium cobalt ferrite (LSCF) anode to YDC layer and YSZ electrolyte and (ii) a very important shift of Ni from Ni-YSZ cathode to YSZ and YDC, and also to LSCF anode in a lower proportion. This study highlights the critical issue that impurities represent for solid oxide electrolysis cell operation.",
keywords = "Degradation, Electrochemical impedance spectroscopy, Electrolyte electronic conduction, Hydrogen, Solid oxide electrolysis cell, Yttria stabilized zirconia",
author = "Aziz Nechache and Boukamp, {Bernard A.} and Michel Cassir and Armelle Ringued{\'e}",
year = "2019",
month = "3",
day = "1",
doi = "10.1007/s10008-018-04184-3",
language = "English",
volume = "23",
pages = "871--881",
journal = "Journal of solid state electrochemistry",
issn = "1432-8488",
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Accelerated degradation of yttria stabilized zirconia electrolyte during high-temperature water electrolysis. / Nechache, Aziz (Corresponding Author); Boukamp, Bernard A.; Cassir, Michel; Ringuedé, Armelle (Corresponding Author).

In: Journal of solid state electrochemistry, Vol. 23, No. 3, 01.03.2019, p. 871-881.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Accelerated degradation of yttria stabilized zirconia electrolyte during high-temperature water electrolysis

AU - Nechache, Aziz

AU - Boukamp, Bernard A.

AU - Cassir, Michel

AU - Ringuedé, Armelle

PY - 2019/3/1

Y1 - 2019/3/1

N2 - The accelerated degradation of a commercial LSCF/YDC/YSZ/Ni-YSZ solid oxide electrolyzer cell (La0.6Sr0.4Co0.2Fe0.8O3-δ/Y0.1CeO1.95/Y0.08Zr0.92O1.96/Ni-YSZ) contaminated by Si-containing impurities is studied with time under up to − 1.7 A cm−2 applied. Above ~ − 0.6 A cm−2, a new region appears in the polarization curve. This region corresponds to electronic conduction in the yttria-stabilized zirconia (YSZ) electrolyte, induced by the reduction under high current conditions. A shift in the typical frequencies (relaxation times) toward lower frequencies is then observed for the entire impedance spectra. This shift results finally in the disappearance of the positive loop related to the polarization resistance and the appearance of a negative (inductance type) loop which crosses the real axis (Z’) at the lowest frequencies to become positive again. This is characteristic for an electrode process mode in which the electrochemical redox reactions vanish while the cell current becomes mainly electronic due to the reduction of the YSZ electrolyte. This trend increases with time. Such a characterization of the electronic conduction of the YSZ electrolyte by electrochemical impedance spectroscopy has not been reported to date under electrolysis mode, to the best of our knowledge. Post-mortem analysis by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDX) shows detrimental degradation of the electrolyte after only 360 h of overall testing duration with numerous micropores in the YSZ volume, and cracks and delamination at the yttria-doped ceria (YDC)/YSZ interface. EDX analysis reveals (i) a migration of La, Sr, Co, and Fe elements from lanthanum strontium cobalt ferrite (LSCF) anode to YDC layer and YSZ electrolyte and (ii) a very important shift of Ni from Ni-YSZ cathode to YSZ and YDC, and also to LSCF anode in a lower proportion. This study highlights the critical issue that impurities represent for solid oxide electrolysis cell operation.

AB - The accelerated degradation of a commercial LSCF/YDC/YSZ/Ni-YSZ solid oxide electrolyzer cell (La0.6Sr0.4Co0.2Fe0.8O3-δ/Y0.1CeO1.95/Y0.08Zr0.92O1.96/Ni-YSZ) contaminated by Si-containing impurities is studied with time under up to − 1.7 A cm−2 applied. Above ~ − 0.6 A cm−2, a new region appears in the polarization curve. This region corresponds to electronic conduction in the yttria-stabilized zirconia (YSZ) electrolyte, induced by the reduction under high current conditions. A shift in the typical frequencies (relaxation times) toward lower frequencies is then observed for the entire impedance spectra. This shift results finally in the disappearance of the positive loop related to the polarization resistance and the appearance of a negative (inductance type) loop which crosses the real axis (Z’) at the lowest frequencies to become positive again. This is characteristic for an electrode process mode in which the electrochemical redox reactions vanish while the cell current becomes mainly electronic due to the reduction of the YSZ electrolyte. This trend increases with time. Such a characterization of the electronic conduction of the YSZ electrolyte by electrochemical impedance spectroscopy has not been reported to date under electrolysis mode, to the best of our knowledge. Post-mortem analysis by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDX) shows detrimental degradation of the electrolyte after only 360 h of overall testing duration with numerous micropores in the YSZ volume, and cracks and delamination at the yttria-doped ceria (YDC)/YSZ interface. EDX analysis reveals (i) a migration of La, Sr, Co, and Fe elements from lanthanum strontium cobalt ferrite (LSCF) anode to YDC layer and YSZ electrolyte and (ii) a very important shift of Ni from Ni-YSZ cathode to YSZ and YDC, and also to LSCF anode in a lower proportion. This study highlights the critical issue that impurities represent for solid oxide electrolysis cell operation.

KW - Degradation

KW - Electrochemical impedance spectroscopy

KW - Electrolyte electronic conduction

KW - Hydrogen

KW - Solid oxide electrolysis cell

KW - Yttria stabilized zirconia

U2 - 10.1007/s10008-018-04184-3

DO - 10.1007/s10008-018-04184-3

M3 - Article

VL - 23

SP - 871

EP - 881

JO - Journal of solid state electrochemistry

JF - Journal of solid state electrochemistry

SN - 1432-8488

IS - 3

ER -