Please use this identifier to cite or link to this item: http://hdl.handle.net/1946/7058
Formation of lanthanum zirconates in solid oxide electrolysis cells : experimental studies
Versa Power Systems solid oxide cells were tested with the objective of performing long term electrolysis testing and studying their degradation and, more specifically, the creation of insulating phases of lanthanum zirconates. Three cells were tested but only one sustained long term electrolysis testing. The other two fractured due to excessive fuel flow and lack of heating in inlet tubes. A different sealing method and bubbler were used in the third tested cell. This cell showed good initial performance with power densities around 0.32 W/cm2 and with an ASR of 0.59 Ω.cm2 running on 175sccm H2 / 175sccm H20. The cell ran in electrolysis mode for 290 hours showing a steady degradation that eventually stabilized and even recovered in the last tens of hours. These are thought to be passivation and activation processes due to the silica based sealant (Hauch A. E., 2008). Scanning electron microscopy (SEM) and x-ray diffraction (XRD) measurements were performed after cell testing. They showed no significant microstructural changes and no presence of the insulating phase. A previous report on another VPS cell showed the possibility of the presence of this phase in an XRD test. Yet when a second XRD test was done these phases were not found. This might be explained if we consider that these phases form under the places where platinum paste is present, which conforms to the two different microstructural areas found in the SEM images in the previous tested cell.
RES Master´s Thesis
Verkefnið er unnið í tengslum við Háskóla Íslands og Háskólann á Akureyri