Preparation of Carbon-tolerant Solid Oxide Fuel Cell Anodes for Direct Utilization of CH4 using Microwave Irradiation

Date
2013-02-21
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Abstract
Solid oxide fuel cells (SOFC) are highly efficient electrochemical devices that directly convert the chemical energy of a fuel into electricity. The conventional Ni/YSZ anode of SOFC accumulates carbon when operated in CH4. The accumulated carbon at the anode degrades cell performance and eventually damages the anode microstructure. In this thesis, the effect of experimental parameters on carbon accumulation was identified and subsequently carbon-tolerance enhancing materials such as Cu and BaO were added to the Ni/YSZ anodes by microwave irradiation. First, the effect of experimental parameters such as the quality of sealing, current, humidity of the fuel, and the current collector configuration on carbon accumulation was studied. The salient results showed that variations in any of these experimental parameters could significantly increase or decrease the amount of carbon accumulation on the Ni/YSZ anodes. Thus, it is emphasised that for the purpose of comparing different anode materials, cells should be tested under similar, if not identical, experimental conditions. After perfecting the standard procedures for fabrication and testing of SOFC button cells, the microwave irradiation technique was used to deposit Cu nanoparticles on the Ni/YSZ anode of an electrolyte-supported SOFC. The advantage of using the microwave irradiation method is the reduced time required for anode preparation. The irradiation times are on the order of seconds in comparison to impregnation that usually requires multiple steps and hours if not days for the preparation of similar anodes. However, Cu is not thermally stable at the SOFC testing temperature of 1073 K. This preliminary study with Cu paves the way for using the microwave technique to incorporate BaO, which helps adsorb H2O and gasify carbon deposits from the Ni surface. With the conventional technique (impregnation), BaO is distributed both on the Ni and YSZ grains. The BaO is stable on Ni but diffuses into YSZ causing a volume expansion of YSZ, which is problematic for the long term performance. The microwave technique was developed to selectively deposit BaO on Ni and these cells perform as well electrochemically as conventional Ni/YSZ anodes in CH4 and accumulate less carbon when operated in CH4 at 1073 K.
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Keywords
Engineering--Chemical
Citation
Islam, S. (2013). Preparation of Carbon-tolerant Solid Oxide Fuel Cell Anodes for Direct Utilization of CH4 using Microwave Irradiation (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/27416