Influence of humidified synthetic air feeding conditions on the stoichiometry of (La1-xSrx)yCoO3−δ and La0.6Sr0.4Co0.2Fe
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- 作者：I. Kivi ; J. Aruväli ; K. Kirsimäe ; P. Möller…
- 关键词：Solid oxide fuel cell ; Cathode ; In situ HT ; XRD ; Electrochemical impedance
- 刊名：Journal of Solid State Electrochemistry
- 出版年：2017
- 出版时间：February 2017
- 年：2017
- 卷：21
- 期：2
- 页码：361-369
- 全文大小：1021KB
- 刊物类别：Chemistry and Materials Science
- 刊物主题：Physical Chemistry; Electrochemistry; Energy Storage; Characterization and Evaluation of Materials; Analytical Chemistry; Condensed Matter Physics;
- 出版者：Springer Berlin Heidelberg
- ISSN：1433-0768
- 卷排序：21
文摘
The solid oxide fuel cell symmetrical cells with porous (La1-xSrx)yCoO3−δ and La0.6Sr0.4Co0.2Fe0.8O3−δ electrodes for intermediate temperature applications have been studied under electrochemical polarization and synthetic air + H2O vapor (so called moisturized cathode gas) feeding conditions using high-temperature electrochemical in situ X-ray diffraction method, chronoamperometry, cyclic voltammetry, and impedance spectroscopy methods. Changes in the lattice parameters and electrochemical activity of La0.6Sr0.4CoO3−δ, (La0.6Sr0.4)1.01CoO3−δ, (La0.6Sr0.4)0.99CoO3−δ and La0.6Sr0.4Co0.2Fe0.8O3−δ were calculated depending on the temperature (T), electrode potential (E), and oxygen partial pressure (pO2) applied. Influence of H2O vapor in synthetic air on (La1-xSrx)yCoO3−δ parameters was irreversible and continued expansion of (La1-xSrx)yCoO3−δ lattice observed in H2O vapor + synthetic air feeding conditions has been observed continuously after changing wet cathode gas to dry oxygen. Nearly, reversible behavior of La0.6Sr0.4Co0.2Fe0.8O3−δ lattice has been established and for La0.6Sr0.4Co0.2Fe0.8O3−δ, the cell volume and polarization resistance started to decrease after changing humidified synthetic air to dry synthetic air in the cathode compartment. For the slightly cationic deficient (La0.6Sr0.4)0.99CoO3−δ, the cathode structure is more stable and the electroreduction of the oxygen was faster. Detailed comparison of experimental data demonstrates that the dependence of the crystallographic parameters on the electrode potential and temperature applied is in a good agreement with the electrochemical impedance spectroscopy data, indicating that the electrocatalytic activity of the cathode decreases with the rise of Fe ion concentration in B-position of LSCF cathode.