Degradation Mechanism in La0.8Sr0.2CoO3 [La subscript 0.8 Sr subscript 0.2 CoO subscript 3] as Contact Layer on the Solid Oxide Electrolysis Cell Anode
Detailed chemical and structural analyses are presented for the degradation mechanism of La0.8Sr0.2CoO3 [La subscript 0.8 Sr subscript 0.2 CoO subscript 3]] (LSC) as the contact layer of solid oxide electrolysis cell (SOEC) anodes. SOEC stack cells, which were operated in the presence of Cr-contain...
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| Format: | Article |
| Language: | en_US |
| Published: |
Electrochemical Society
2011
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| Online Access: | http://hdl.handle.net/1721.1/66223 https://orcid.org/0000-0002-2688-5666 |
| Summary: | Detailed chemical and structural analyses are presented for the degradation mechanism of La0.8Sr0.2CoO3 [La subscript 0.8 Sr subscript 0.2 CoO subscript 3]] (LSC) as the contact
layer of solid oxide electrolysis cell (SOEC) anodes. SOEC stack cells, which were operated in the presence of Cr-containing
interconnects, and reference half-cells, which were tested with Pt interconnects, were investigated. The as-prepared surface
chemistry of LSC showed a spatially uniform A-site (La and Sr) enrichment. Undesirable secondary phases of Cr2O3 [Cr subscript 2 O subscript 3], LaCrO3 [LaCrO subscript 3],
La2CrO6 [La subscript 2 CrO subscript 6], and Co3O4 [Co subscript 3 O subscript 4] were identified in the contact layer of the SOEC stack cells, which had significantly reduced electrochemical
performance after long-term testing. Auger electron spectroscopy and analytical transmission electron microscopy showed the
presence of Cr throughout the layer cross section on the surface and in the bulk, respectively, with significant variations in the local
chemistry at the micro- to nanoscale. Particularly, a long-range transport of Sr and Co cations out of the LSC phase to the top of
the contact layer was evident. However, when tested with electrolytic potential and current without a Cr environment, the LSC
contact layer composition remained stable. The dissociation of the LSC in the SOEC stack cells can be, most probably, driven by
the La–Cr–O related thermodynamics under the electrolytic potential and oxygen pressure at the anode. |
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