MSE Ph.D. Proposal - Brian Doyle
Prof. Meilin Liu, Advisor, MSE
Prof. Mark Losego, MSE
Prof. Faisal Alamgir, MSE
Prof. Matthew McDowell, MSE/ME
Prof Lawrence Bottomely, ChBE
Title: Surface Modification of Solid Oxide Fuel Cell Electrodes Using Conformal Thin Film Transition Metal Oxides and Carbides
Solid oxide fuel cells (SOFCs) represent a promising energy generation technology limited by high operating temperatures and electrode performance. Because they rely on electrochemical energy conversion, they are not subject to Carnot-cycle limitations. In fact, combined heat and power SOFC systems are able to reach efficiencies on the order of 80%. Unfortunately, these completely solid state electrochemical cells require relatively high operating temperatures (~800-1000°C) for acceptable conductivity values. High temperatures require high-cost structural materials and contribute to chemical and mechanical degradation of the system. In order to realize operation at intermediate temperatures (400-800°C), the performance of the anode and cathode must be increased. For the anode, that translates into increased coking tolerance in order to operate on hydrocarbon fuels. For the cathode, that means increasing oxygen reduction activity. This proposal will develop the rationale for surface modification of the anode and cathode with transition metal oxides and carbides to increase coking tolerance (anode) and decrease polarization losses (cathode).
Surface modification on SOFC electrodes has been shown to drastically affect performance. Additionally, when transition metal oxides are deposited as thin films (<20nm), they exhibit non-intuitive behavior. For example, inert coatings (negligible ionic conductivity) have shown to decrease performance degradation in SOFC cathodes. In order to investigate the effect of surface modification on SOFC anodes and cathodes, atomic layer deposition (ALD) and surface sol-gel (SSG) will be used. Both strategies allow for precise control of thickness and conformal coatings for the 3-dimensional porosity found in solid oxide fuel cell anodes and cathodes. The cells will be physically characterized through TEM/SEM and electrochemically characterized through full cell testing, impedance spectroscopy, in-situ Raman spectroscopy and ex-situ X-ray photoelectron spectroscopy. The end product of the proposed research is a better understanding of how thin oxide and carbide films affect hydrocarbon oxidation and oxygen reduction in solid oxide fuel cells.