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

doi:10.1088/2515-7655/ab59a6

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

Materials Science and Engineering

Research output: Contribution to journal › Article › peer-review

9 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 language	English (US)
Article number	014006
Journal	JPhys Energy
Volume	2
Issue number	1
DOIs	https://doi.org/10.1088/2515-7655/ab59a6
State	Published - Jan 2020

Funding

The authors gratefully acknowledge financial support by the US National Science Foundation (grant # DMR-1506925) for the experimental part of this paper and Department of Energy (grant # DE-EE0008079) on the theoretical part. The authors also acknowledge the assistance of the Electron Probe Instrumentation Center (EPIC) at the NUANCE Center-Northwestern University, which has received support from the MRSEC program (NSF DMR-1121262) at the Materials Research Center; the International Institute for Nanotechnology (IIN); and the State of Illinois, through the IIN.

Keywords

Degradation
Life tests
Ni-YSZ
Solid oxide fuel cell

ASJC Scopus subject areas

General Energy
Materials Chemistry
Materials Science (miscellaneous)

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10.1088/2515-7655/ab59a6

Cite this

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

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.",

keywords = "Degradation, Life tests, Ni-YSZ, Solid oxide fuel cell",

author = "Qinyuan Liu and Qian Zhang and Voorhees, {Peter W.} and Barnett, {Scott A.}",

note = "Publisher Copyright: {\textcopyright} 2019 The Author(s). Published by IOP Publishing Ltd",

year = "2020",

month = jan,

doi = "10.1088/2515-7655/ab59a6",

language = "English (US)",

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T1 - Effect of direct-current operation on the electrochemical performance and structural evolution of Ni-YSZ electrodes

AU - Liu, Qinyuan

AU - Zhang, Qian

AU - Voorhees, Peter W.

AU - Barnett, Scott A.

PY - 2020/1

Y1 - 2020/1

N2 - 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.

AB - 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.

KW - Degradation

KW - Life tests

KW - Ni-YSZ

KW - Solid oxide fuel cell

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

Abstract

Funding

Keywords

ASJC Scopus subject areas

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