Synergistic effects of temperature and polarization on Cr poisoning of La <inf>0.6</inf> Sr <inf>0.4</inf> Co <inf>0.2</inf> Fe <inf>0.8</inf> O <inf>3-: δ</inf> solid oxide fuel cell cathodes
File(s)
Accepted version
Supporting information
Author(s)
Ni, N
Wang, CC
Jiang, SP
Skinner, SJ
Type
Journal Article
Abstract
La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) solid oxide fuel cell cathodes were poisoned by Cr at different temperatures and polarization conditions with a Cr-Fe alloy as the interconnect. Cr induced degradation was analysed by electrochemical impedance spectroscopy (EIS) focusing on the electrochemical resistance (R chem ) that reflects the cathode electrochemical properties. It was found that R chem increased more with increasing temperatures. However cathodic polarization exhibited a synergistic effect with the temperature, which accelerated the LSCF cathode degradation at 800 °C while lowering the degree of degradation at 900 °C. By correlating complementary micro- and nano-scale microstructure characterization with the impedance analysis, the degradation mechanisms were investigated. A new Cr incorporation mechanism involving preferential formation of nanometre size Fe-Co-Cr-O spinel particles within the cathode up to the cathode/electrolyte interface was found to be responsible for the reduced degradation at 900 °C combined with cathodic polarization. The new mechanism reveals that the activity of B site elements in LSCF and possibly other perovskite cathodes plays an important role under certain combined temperature and polarization conditions, therefore future research in designing Cr resistant perovskite cathode materials may consider strategies that utilize the exsolution of B site elements for the formation of beneficial spinel phases.
Date Issued
2019-04-21
Date Acceptance
2019-03-20
Citation
Journal of Materials Chemistry A, 2019, 7 (15), pp.9253-9262
ISSN
2050-7496
Publisher
Royal Society of Chemistry
Start Page
9253
End Page
9262
Journal / Book Title
Journal of Materials Chemistry A
Volume
7
Issue
15
Replaces
10044/1/69642
Copyright Statement
© 2019 The Royal Society of Chemistry.
Publication Status
Published
Date Publish Online
2019-03-20