Ceria-Based Anodes for Next Generation Solid Oxide Fuel Cells

Mirfakhraei, Behzad

Ceria-Based Anodes for Next Generation Solid Oxide Fuel Cells

atmire.migration.oldid	3177
dc.contributor.advisor	Birss, Viola
dc.contributor.advisor	Thangadurai, Venkataraman
dc.contributor.author	Mirfakhraei, Behzad
dc.date.accessioned	2015-05-01T17:22:22Z
dc.date.available	2015-06-22T07:00:50Z
dc.date.issued	2015-05-01
dc.date.submitted	2015	en
dc.description.abstract	Mixed ionic and electronic conducting materials (MIECs) have been suggested to represent the next generation of solid oxide fuel cell (SOFC) anodes, primarily due to their significantly enhanced active surface area and their tolerance to fuel components. In this thesis, the main focus has been on determining and tuning the physicochemical and electrochemical properties of ceria-based MIECs in the versatile perovskite or fluorite crystal structures. In one direction, BaZr0.1Ce0.7Y0.1M0.1O3-δ (M = Fe, Ni, Co and Yb) (BZCY-M) perovskites were synthesized using solid-state or wet citric acid combustion methods and the effect of various transition metal dopants on the sintering behavior, crystal structure, chemical stability under CO2 and H2S, and electrical conductivity, was investigated. BZCY-Ni, synthesized using the wet combustion method, was the best performing anode, giving a polarization resistance (RP) of 0.4 Ω.cm2 at 800 oC. Scanning electron microscopy and X-ray diffraction analysis showed that this was due to the exsolution of catalytic Ni nanoparticles onto the oxide surface. Evolving from this promising result, the effect of Mo-doped CeO2 (nCMO) or Ni nanoparticle infiltration into a porous Gd-doped CeO2 (GDC) anode (in the fluorite structure) was studied. While 3 wt. % Ni infiltration lowered RP by up to 90 %, giving 0.09 Ω.cm2 at 800 oC and exhibiting a ca. 5 times higher tolerance towards 10 ppm H2S, nCMO infiltration enhanced the H2S stability by ca. 3 times, but had no influence on RP. In parallel work, a first-time study of the Ce3+ and Ce4+ redox process (pseudocapacitance) within GDC anode materials was carried out using cyclic voltammetry (CV) in wet H2 at high temperatures. It was concluded that, at 500-600 oC, the Ce3+/Ce4+ reaction is diffusion controlled, probably due to O2- transport limitations in the outer 5-10 layers of the GDC particles, giving a very high capacitance of ca. 70 F/g. Increasing the temperature ultimately diminished the observed capacitance, likely as the chemical reduction of GDC at high temperatures is irreversible.	en_US
dc.identifier.citation	Mirfakhraei, B. (2015). Ceria-Based Anodes for Next Generation Solid Oxide Fuel Cells (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/25245	en_US
dc.identifier.doi	http://dx.doi.org/10.11575/PRISM/25245
dc.identifier.uri	http://hdl.handle.net/11023/2219
dc.language.iso	eng
dc.publisher.faculty	Graduate Studies
dc.publisher.institution	University of Calgary	en
dc.publisher.place	Calgary	en
dc.rights	University 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.subject	Chemistry--Physical
dc.subject	Energy
dc.subject	Materials Science
dc.subject.classification	Solid Oxide Fuel Cell	en_US
dc.subject.classification	Electrochemical Characterization	en_US
dc.subject.classification	H2S Poisoning	en_US
dc.subject.classification	Materials Synthesis	en_US
dc.subject.classification	SOFC Anode	en_US
dc.title	Ceria-Based Anodes for Next Generation Solid Oxide Fuel Cells
dc.type	doctoral thesis
thesis.degree.discipline	Chemistry
thesis.degree.grantor	University of Calgary
thesis.degree.name	Doctor of Philosophy (PhD)
ucalgary.item.requestcopy	true