Collaborative Research: Three-Dimensional Microstructural and Chemical Mapping of Solid Oxide Fuel Cell Electrodes: Processing, Structure, Stability, and Electrochemistry

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Proposal Title: Collaborative Research: Three-Dimensional Microstructural andChemical Mapping of Solid Oxide Fuel Cell Electrodes: Processing,Structure, Stability, and ElectrochemistryInstitution: Northwestern UniversityAbstract Date: 06/11/09This award is funded under the American Recovery and Reinvestment Act of 2009(Public Law 111-5).NON-TECHNICAL DESCRIPTION:Solid oxide fuel cells (SOFCs) offer an important new option for converting fuels to electricity with increased efficiency, reduced pollution, and reduced greenhouse gas emissions. The race to reap the commercial and environmental benefits of this technology is largely being decided by practical issues, including cost and device reliability. The proposed project seeks to better understand how SOFC performance and reliability are linked to manufacturing methods and constituent materials properties, by the acquisition and analysis of three-dimensional images of the fuel cells. Such images can be used to determine what structures yield improved performance and hence reduced cost, find manufacturing conditions that yield the desired structure/chemistry, and examine the factors causing fuel cells to degrade over time.The improved structural and chemical information will be disseminated to the fuel cell research and development community where it will help enable critical connections, for example between industrial developers ? who need reliable performance/lifetime predictions ? and modelers ? who require good structural/chemical information to make such predictions. A substantial number of graduate and undergraduate students, in many cases from underrepresented groups, will receive training through this project. There are a number of other educational impacts, including high-school science teachers participating in summer research.TECHNICAL DETAILS:The limited quantitative information available on electrode structure and interfacial chemistry poses a major barrier to fundamental understanding of fuel cell performance and stability. This Focused Research Group is examining the relationships between the processing, structure, and electrochemical properties of key SOFC materials, utilizing a set of tools based on focused ion beam ? scanning electron microscopy (FIB-SEM) to determine the microstructure of SOFC electrodes in three-dimensions (3D). The projectincludes fabrication of state-of-the-art SOFCs, detailed electrochemical characterization using novel impedance spectroscopy methods, structural measurement using FIB-SEM, segmentation of the data into 3D phase maps, visualization of the microstructures, extraction of macrohomogeneous structural parameters, and simulations of microstructural coarsening and electrochemical polarization based directly on 3D data sets. Additional information regarding interdiffusion, accumulation of cation speciesand/or impurities at interfaces, and second phases is obtained with analytical scanning transmission electron microscope (TEM) analysis and synchrotron X-ray methods. Availability of this 3D microstructure information will be instrumental for transforming our understanding of how fuel cell electrodes work to a more quantitative science. Broad impacts of the project include the continued growth of a 3D structural data library available to researchers/developers nationwide, and development of analysis toolsrelevant to the broader 3D microstructure community. Students and teachers involved in the project receive training on state of the art tools for fuel-cell fabrication, electrochemical testing, microscopy, and materials modeling.