Journal
ENERGIES
Volume 15, Issue 8, Pages -Publisher
MDPI
DOI: 10.3390/en15082726
Keywords
modified Ni-GDC electrode; solid oxide electrolysis cells (SOECs); steam electrolysis; electrochemical performance; degradation; post-test analyses
Categories
Funding
- Fuel Cells and Hydrogen 2 Joint Undertaking under the project SElySOs [671481]
- European Union
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Ni-gadolinia-doped ceria (GDC) based electrode materials have attracted attention due to their mixed ionic conductivity and high electronic and catalytic activity. However, prolonged operation can result in Ni migration.
Ni-gadolinia-doped ceria (GDC) based electrode materials have drawn significant attention as an alternative fuel electrode for solid oxide cells (SOCs) owing to mixed ionic conductivity of GDC and high electronic and catalytic activity of Ni. Moreover, the catalytic activity and electrochemical performance of the Ni-GDC electrode can be further improved by dispersing small quantities of other metal additives, such as gold or molybdenum. Therefore, herein, we considered gold and molybdenum modified Ni-GDC electrodes and focused on the upscaling; hence, we prepared 5 x 5 cm(2) electrolyte-supported single cells. Their electrochemical performance was investigated at different temperatures and fuel gas compositions. The long-term steam electrolysis test, up to 1700 h, was performed at 900 degrees C with -0.3 A center dot cm(-2) current load. Lastly, post-test analyses of measured cells were carried out to investigate their degradation mechanisms. Sr-segregation and cobalt oxide formation towards the oxygen electrode side, and Ni-particle coarsening and depletion away from the electrolyte towards the fuel electrode side, were observed, and can be considered as a main reason for the degradation. Thus, modification of Ni/GDC with Au and Mo seems to significantly improve the electro-catalytic activity of the electrode; however, it does not significantly mitigate the Ni-migration phenomenon after prolonged operation.
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