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Title: Advanced Measurement and Modeling Techniques for Improved SOFC Cathodes

Abstract

The goal of this project was to develop an improved understanding of factors governing performance and degradation of mixed-conducting SOFC cathodes. Two new diagnostic tools were developed to help achieve this goal: (1) microelectrode half-cells for improved isolation of cathode impedance on thin electrolytes, and (2) nonlinear electrochemical impedance spectroscopy (NLEIS), a variant of traditional impedance that allows workers to probe nonlinear rates as a function of frequency. After reporting on the development and efficacy of these tools, this document reports on the use of these and other tools to better understand performance and degradation of cathodes based on the mixed conductor La{sub 1-x}Sr{sub x}CoO{sub 3-{delta}} (LSC) on gadolinia or samaria-doped ceria (GDC or SDC). We describe the use of NLEIS to measure O{sub 2} exchange on thin-film LSC electrodes, and show that O{sub 2} exchange is most likely governed by dissociative adsorption. We also describe parametric studies of porous LSC electrodes using impedance and NLEIS. Our results suggest that O{sub 2} exchange and ion transport co-limit performance under most relevant conditions, but it is O{sub 2} exchange that is most sensitive to processing, and subject to the greatest degradation and sample-to-sample variation. We recommend further work that focuses onmore » electrodes of well-defined or characterized geometry, and probes the details of surface structure, composition, and impurities. Parallel work on primarily electronic conductors (LSM) would also be of benefit to developers, and to improved understanding of surface vs. bulk diffusion.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Univ. of Washington, Seattle, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
911844
DOE Contract Number:
FC26-02NT41566
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
30 DIRECT ENERGY CONVERSION; ADSORPTION; CATHODES; DIFFUSION; ELECTRODES; ELECTROLYTES; GEOMETRY; IMPEDANCE; IMPURITIES; PERFORMANCE; PROBES; PROCESSING; SIMULATION; SOLID OXIDE FUEL CELLS; SPECTROSCOPY; TRANSPORT

Citation Formats

Stuart Adler, L. Dunyushkina, S. Huff, Y. Lu, and J. Wilson. Advanced Measurement and Modeling Techniques for Improved SOFC Cathodes. United States: N. p., 2006. Web. doi:10.2172/911844.
Stuart Adler, L. Dunyushkina, S. Huff, Y. Lu, & J. Wilson. Advanced Measurement and Modeling Techniques for Improved SOFC Cathodes. United States. doi:10.2172/911844.
Stuart Adler, L. Dunyushkina, S. Huff, Y. Lu, and J. Wilson. Sun . "Advanced Measurement and Modeling Techniques for Improved SOFC Cathodes". United States. doi:10.2172/911844. https://www.osti.gov/servlets/purl/911844.
@article{osti_911844,
title = {Advanced Measurement and Modeling Techniques for Improved SOFC Cathodes},
author = {Stuart Adler and L. Dunyushkina and S. Huff and Y. Lu and J. Wilson},
abstractNote = {The goal of this project was to develop an improved understanding of factors governing performance and degradation of mixed-conducting SOFC cathodes. Two new diagnostic tools were developed to help achieve this goal: (1) microelectrode half-cells for improved isolation of cathode impedance on thin electrolytes, and (2) nonlinear electrochemical impedance spectroscopy (NLEIS), a variant of traditional impedance that allows workers to probe nonlinear rates as a function of frequency. After reporting on the development and efficacy of these tools, this document reports on the use of these and other tools to better understand performance and degradation of cathodes based on the mixed conductor La{sub 1-x}Sr{sub x}CoO{sub 3-{delta}} (LSC) on gadolinia or samaria-doped ceria (GDC or SDC). We describe the use of NLEIS to measure O{sub 2} exchange on thin-film LSC electrodes, and show that O{sub 2} exchange is most likely governed by dissociative adsorption. We also describe parametric studies of porous LSC electrodes using impedance and NLEIS. Our results suggest that O{sub 2} exchange and ion transport co-limit performance under most relevant conditions, but it is O{sub 2} exchange that is most sensitive to processing, and subject to the greatest degradation and sample-to-sample variation. We recommend further work that focuses on electrodes of well-defined or characterized geometry, and probes the details of surface structure, composition, and impurities. Parallel work on primarily electronic conductors (LSM) would also be of benefit to developers, and to improved understanding of surface vs. bulk diffusion.},
doi = {10.2172/911844},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Dec 31 00:00:00 EST 2006},
month = {Sun Dec 31 00:00:00 EST 2006}
}

Technical Report:

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