Development of Oxygen Electrodes for Reversible Solid Oxide Fuel Cells

Simple item page
atmire.migration.oldid5600
dc.contributor.advisorBirss, Viola
dc.contributor.authorMolero Sánchez, Beatriz
dc.contributor.committeememberTrudel, Simon
dc.contributor.committeememberThangadurai, Venkataraman
dc.contributor.committeememberPonnurangam, Sathish
dc.contributor.committeememberBarnett, Scott
dc.date.accessioned2017-05-18T18:22:15Z
dc.date.available2017-05-18T18:22:15Z
dc.date.issued2017
dc.date.submitted2017en
dc.description.abstractThe primary focus of this thesis has been to develop high performance stable oxygen electrodes, with a primary emphasis on a mixed conducting La0.3Ca0.7Cr0.3Fe0.7O3-δ (LCFCr) perovskite, for use in advanced reversible solid oxide fuel cells (RSOFCs). RSOFCs are single unit electrochemical devices that can operate in both the fuel cell (SOFC) and electrolysis (SOEC) mode, thus acting as flexible and efficient energy conversion systems. The interest in LCFCr arose from earlier work with LSFCr (La0.3Sr0.7Cr0.3Fe0.7O3-δ), shown to be a very promising SOFC cathode. Thus, this thesis began with a rigorous study of the oxygen evolution (OER) and reduction (ORR) reactions at the LSFCr material, including understanding how to interpret the electrochemical results. However, LSFCr has a thermal expansion coefficient (TEC) that does not match with common solid electrolytes and thus its long time stability is questionable. For this reason, the Ca analogue (LCFCr), a new electrode material, was synthesized and shown to have a much more suitable TEC. Extensive 2-electrode and 3-electrode half-cell studies revealed two slow steps during the OER and ORR, including oxygen/LCFCr surface reactions and O2- transfer at the LCFCr/electrolyte interface. It was also shown that LCFCr is more active in the electrolysis mode (OER) than in the SOFC mode (ORR). Further, the infiltration of ceria or co-infiltration of ceria+LCFCr led to substantial improvements in LCFCr performance, also providing further insights into the processes that control the reaction rates. It was shown that, after 200 h of operation in either the SOFC or SOEC modes, the main source of degradation was from the series resistance (the LCFCr/Au current collector interface), suggestive of Au sintering. The low frequency process, related to the LCFCr/air interface, also deteriorated somewhat, while the underlying LCFCr/electrolyte interface remained stable. This was confirmed from both electrochemistry and high-resolution TEM, showing the retention of a very high quality interface at the atomic level. A novel and very promising SOC powder and cell sintering methodology was also developed using microwave technology, significantly lowering the manufacturing temperature, processing, and energy requirements, due also to the much lower energy demand of the MW furnace. This translates to significant manufacturing cost savings, making MW processing of complete solid oxide cells a promising route for the future.en_US
dc.identifier.citationMolero Sánchez, B. (2017). Development of Oxygen Electrodes for Reversible Solid Oxide Fuel Cells (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/25686en_US
dc.identifier.doihttp://dx.doi.org/10.11575/PRISM/25686
dc.identifier.urihttp://hdl.handle.net/11023/3833
dc.language.isoeng
dc.publisher.facultyGraduate Studies
dc.publisher.institutionUniversity of Calgaryen
dc.publisher.placeCalgaryen
dc.rightsUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.
dc.subjectChemistry--Physical
dc.subject.otherSolid Oxide Fuel Cell (SOFC)
dc.subject.otherSolid Oxide Electrolysis Cell (SOEC)
dc.subject.otherRSOFCs
dc.subject.otherElectrochemistry
dc.subject.otherHigh temperature electrolysis
dc.subject.otherMicrowave synthesis
dc.subject.otherMicrowave sintering
dc.subject.otherOxygen electrode
dc.subject.otherPerovskite
dc.subject.otherOxygen reduction
dc.subject.otherOxygen evolution
dc.subject.otherORR
dc.subject.otherOER
dc.subject.otherImpedance spectroscopy (EIS)
dc.titleDevelopment of Oxygen Electrodes for Reversible Solid Oxide Fuel Cells
dc.typedoctoral thesis
thesis.degree.disciplineChemistry
thesis.degree.grantorUniversity of Calgary
thesis.degree.nameDoctor of Philosophy (PhD)
ucalgary.item.requestcopytrue
Files
Collections
Open Theses and Dissertations