Einfluß der chemischen Festkörperreaktionen auf die Funktion von Kathodenmaterialien und Elektrolytmaterialien der Hochtemperaturbrennstoffzelle (SOFC)
Einfluß der chemischen Festkörperreaktionen auf die Funktion von Kathodenmaterialien und Elektrolytmaterialien der Hochtemperaturbrennstoffzelle (SOFC)
For solid oxide fuel cells, the high processing temperatures (> 1200$^{\circ}$C necessary in the production and the prolonged service lives of more than 40.000 h at operating temperatures around 950$^{\circ}$C require a high defree of chemical compatibility between anode, electrolyte and cathode....
Saved in:
Personal Name(s): | Stochniol, G. (Corresponding author) |
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Naoumidis, A. / Nickel, Hubertus | |
Contributing Institute: |
Publikationen vor 2000; PRE-2000; Retrocat |
Imprint: |
Jülich
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag
1996
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Physical Description: |
133 p. |
Document Type: |
Report Book |
Research Program: |
ohne Topic |
Series Title: |
Berichte des Forschungszentrums Jülich
3226 |
Link: |
OpenAccess OpenAccess |
Publikationsportal JuSER |
For solid oxide fuel cells, the high processing temperatures (> 1200$^{\circ}$C necessary in the production and the prolonged service lives of more than 40.000 h at operating temperatures around 950$^{\circ}$C require a high defree of chemical compatibility between anode, electrolyte and cathode. The currently used cathode materials are modified LaMnO$_{3}$ (YSZ). Interdiffusion processes that occur during operation lead to changes in the material properties and to the formation of reaction layers, which may cause deterioration in the efficiency and service life. The investigated cathode materials were perovskites based on LaMnO$_{3}$ produced by a spray-drying technique. In order to improve material properties, different partial replacements of La by Ca or Sr and of Mn by Co and Fe werte tested. Furthermore the A-site stoichiometry was varied. It was shown that the partial replacement of La by Ca decreased the perocskite reactivity with regard to La$_{2}$Zr$_{2}$O$_{7}$-formation more than a partial replacement by Sr, but at the same time a considerable diffusion of Ca into the electrolyte material took place. The partial substitution fo Mn by Co increased the reactivity of the perovskite materials, but also here compositions such as La$_{0.75}$Sr$_{0.2}$Mn$_{0.9}$Co$_{0.1}$O$_{3}$ exist which demonstrate a high chemical compatibility with the electrolyte material. The partial replacement of Mn by Fe increased the chemical compatibility if the perovskites but was accompanied by a decrease in the electrical condutivity. To investigate the influence of possible interdiffusion processes on the electrolyte material, the elements Ca, Mn, Co and Fe were added by solid state reactions and their solubility limits in YSZ were determined by X-ray diffraction. The different influences of these elements on the electrical conductivity of YSZ were investigated. Additions of Ca decreased, and additions the of Mn and Co increased the electrical conductivity, although the contribution of electronic conductivity could not be excluded. Electron paramagnetic resonance measurements were carried out to determine the oxidational states of the d-elements in YSZ. |