Interface chemistry in LSM–YSZ composite SOFC cathodes
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| Title: | Interface chemistry in LSM–YSZ composite SOFC cathodes |
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| Authors: | Backhaus-Ricoult, M.1 backhausm@corning.com |
| Source: | Solid State Ionics. Oct2006, Vol. 177 Issue 19-25, p2195-2200. 6p. |
| Subjects: | Cathodes, Nonmetals, Manganese, Oxide minerals |
| Abstract: | Abstract: (La,Sr)MnO3–3YSZ interface chemistry in air-annealed and operated SOFC cathodes has been studied by high spatial resolution TEM/EELS. Major changes in Mn L2,3 and O K ELNES were observed. A mixture of manganese 3+/4+ is found in the LSM bulk phase. In contact with LSM, zirconia forms a solid solution with dissolved lanthanum and manganese. Manganese is always divalent in this solid solution. After processing and annealing in air, the (La,Sr)MnO3–3YSZ interface shows no ELNES features that distinguish from the adjacent bulk phases. After single cell SOFC operation in air/hydrogen, a strong enrichment of Mn2+ at the cathode interfaces is found with Mn–O interfacial bond contributions. Due to the high Mn2+ level at the interface, the local oxygen vacancy concentration in zirconia at the interface is increased and the electron transfer for the oxygen incorporation in the electrolyte is made easier. Thus, in the operating composite cathode, oxygen incorporation from the gas into the electrolyte is promoted by a Mn2+ enrichment at the triple phase boundaries. Cathodic polarization in the operating single cell is the cause for the Mn2+ enrichment. Interface point defect modeling is used to evaluate interface defect concentrations at LSM/YSZ interfaces. Mn4+ interfacial clusters are the dominant interface defects at very high oxygen partial pressure, while the concentration of Mn2+ interfacial defects increases with decreasing oxygen chemical potential or under polarization. This finding is in agreement with the experimental ELNES results. Model and experiments suggest that cathodic oxygen exchange is promoted under oxygen deficient conditions. [Copyright &y& Elsevier] |
| Copyright of Solid State Ionics is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Engineering Source |
| FullText | Text: Availability: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Interface chemistry in LSM–YSZ composite SOFC cathodes – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Backhaus-Ricoult%2C+M%2E%22">Backhaus-Ricoult, M.</searchLink><relatesTo>1</relatesTo><i> backhausm@corning.com</i> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Solid+State+Ionics%22">Solid State Ionics</searchLink>. Oct2006, Vol. 177 Issue 19-25, p2195-2200. 6p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Cathodes%22">Cathodes</searchLink><br /><searchLink fieldCode="DE" term="%22Nonmetals%22">Nonmetals</searchLink><br /><searchLink fieldCode="DE" term="%22Manganese%22">Manganese</searchLink><br /><searchLink fieldCode="DE" term="%22Oxide+minerals%22">Oxide minerals</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Abstract: (La,Sr)MnO3–3YSZ interface chemistry in air-annealed and operated SOFC cathodes has been studied by high spatial resolution TEM/EELS. Major changes in Mn L2,3 and O K ELNES were observed. A mixture of manganese 3+/4+ is found in the LSM bulk phase. In contact with LSM, zirconia forms a solid solution with dissolved lanthanum and manganese. Manganese is always divalent in this solid solution. After processing and annealing in air, the (La,Sr)MnO3–3YSZ interface shows no ELNES features that distinguish from the adjacent bulk phases. After single cell SOFC operation in air/hydrogen, a strong enrichment of Mn2+ at the cathode interfaces is found with Mn–O interfacial bond contributions. Due to the high Mn2+ level at the interface, the local oxygen vacancy concentration in zirconia at the interface is increased and the electron transfer for the oxygen incorporation in the electrolyte is made easier. Thus, in the operating composite cathode, oxygen incorporation from the gas into the electrolyte is promoted by a Mn2+ enrichment at the triple phase boundaries. Cathodic polarization in the operating single cell is the cause for the Mn2+ enrichment. Interface point defect modeling is used to evaluate interface defect concentrations at LSM/YSZ interfaces. Mn4+ interfacial clusters are the dominant interface defects at very high oxygen partial pressure, while the concentration of Mn2+ interfacial defects increases with decreasing oxygen chemical potential or under polarization. This finding is in agreement with the experimental ELNES results. Model and experiments suggest that cathodic oxygen exchange is promoted under oxygen deficient conditions. [Copyright &y& Elsevier] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Solid State Ionics is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1016/j.ssi.2006.08.011 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 6 StartPage: 2195 Subjects: – SubjectFull: Cathodes Type: general – SubjectFull: Nonmetals Type: general – SubjectFull: Manganese Type: general – SubjectFull: Oxide minerals Type: general Titles: – TitleFull: Interface chemistry in LSM–YSZ composite SOFC cathodes Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Backhaus-Ricoult, M. IsPartOfRelationships: – BibEntity: Dates: – D: 15 M: 10 Text: Oct2006 Type: published Y: 2006 Identifiers: – Type: issn-print Value: 01672738 Numbering: – Type: volume Value: 177 – Type: issue Value: 19-25 Titles: – TitleFull: Solid State Ionics Type: main |
| ResultId | 1 |
