Abstract
Oxygen partial pressure is an important thermodynamic state variable that affects both the performance and degradation of solid oxide electrolysis cells. In this work, a three-dimensional model developed from Virkar’s one-dimensional model has been applied to reconstructed and synthetic microstructures of solid oxide cells with hydrogen electrodes made from Ni and yttria stabilized zirconia (YSZ), and with oxygen electrodes made of gadolinium doped ceria (GDC) and lanthanum strontium cobalt ferrite (LSCF). The effect of microstructures, including the thickness of the YSZ and GDC layer, and the compositions of the hydrogen and oxygen electrodes on the distribution of oxygen partial pressure was investigated. The results show that the maximum oxygen partial pressure occurs on the interface between the GDC and YSZ layers. Under the constant current mode, a thicker GDC layer may decrease or increase the maximum oxygen partial pressure in the cell, depending on the rate of oxygen ion exchange between GDC and YSZ. A thicker YSZ layer lowers the maximum oxygen partial pressure in the hydrogen electrode but increases the maximum oxygen partial pressure in the cell. In addition, the Ni:YSZ/LSCF:GDC ratio and porosity also affect the distribution of oxygen partial pressure. These findings provide insights on mitigating degradation in solid oxide electrolysis cells by tuning the cell microstructures.
Published Version
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