Journal
FUEL CELLS
Volume 21, Issue 5, Pages 415-429Publisher
WILEY-V C H VERLAG GMBH
DOI: 10.1002/fuce.202100072
Keywords
effect of impurities; effect of overpotential; effect of oxygen potential; nickel (Ni) migration; SOEC degradation; solid oxide cell (SOC); solid oxide electrolysis cell (SOEC); solid oxide fuel cell (SOFC)
Categories
Funding
- Villum Fonden through the Villum Center for the Science of Sustainable Fuels and Chemical (V-SUSTAIN) [9455]
Ask authors/readers for more resources
The degradation mechanism of Ni-YSZ electrodes in SOCs is complex and contradictory, characterized by loss of electrical contact between Ni particles and migration of Ni in the most active part. These issues are significant obstacles to the commercialization of SOC systems.
Severe degradation of Ni-YSZ (yttria stabilized zirconia) electrodes of solid oxide cells (SOCs) due to Ni migration is well known, but the literature contains apparent contradictions. The mechanisms are still under debate. Fine structured Ni-YSZ composite electrodes often degrade at operation temperature (700-950 degrees C), because Ni particles lose electrical contact with each other as larger Ni-particles grow on the expense of smaller ones. Another type of Ni migration, which may be very damaging, is the relocation of Ni in the most active part of the Ni-YSZ cermet electrode next to the dense YSZ electrolyte. Emphasis is put on the migration of Ni away from the YSZ electrolyte in solid oxide electrolysis cells (SOECs). This is seen as an important obstacle to the commercialization of SOC systems. Apart from temperature, degradation of Ni-YSZ electrodes in SOCs is related to Ni-YSZ electrode overpotential and the local redox potential of the gas mixture inside the porous Ni-YSZ electrode. A unifying Ni migration mechanism is proposed, and methods of alleviating the electrode degradation are discussed. The hypothesis is that Ni migrates via surface diffusion of Ni(OH)(x) species below ca. 800 degrees C and via Ni(OH)(x) species in gas phase above ca. 900 degrees C.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available