Electro-catalytically Active, High Surface Area Cathodes for Low Temperature SOFCs
This research focused on developing low polarization (area specific resistance, ASR) cathodes for intermediate temperature solid oxide fuel cells (IT-SOFCs). In order to accomplish this we focused on two aspects of cathode development: (1) development of novel materials; and (2) developing the relationships between microstructure and electrochemical performance. The materials investigated ranged from Ag-bismuth oxide composites (which had the lowest reported ASR at the beginning of this contract) to a series of pyrochlore structured ruthenates (Bi{sub 2-x}M{sub x}Ru{sub 2}O{sub 7}, where M = Sr, Ca, Ag; Pb{sub 2}Ru{sub 2}O{sub 6.5}; and Y{sub 2-2x}Pr{sub 2x}Ru{sub 2}O{sub 7}), to composites of the pyrochlore ruthenates with bismuth oxide. To understand the role of microstructure on electrochemical performance, we optimized the Ag-bismuth oxide and the ruthenate-bismuth oxide composites in terms of both two-phase composition and particle size/microstructure. We further investigated the role of thickness and current collector on ASR. Finally, we investigated issues of stability and found the materials investigated did not form deleterious phases at the cathode/electrolyte interface. Further, we established the ability through particle size modification to limit microstructural decay, thus, enhancing stability. The resulting Ag-Bi{sub 0.8}Er{sub 0.2}O{sub 1.5} and Bi{sub 2}Ru{sub 2}O{sub 7{sup -}}Bi{sub 0.8}Er{sub 0.2}O{sub 1.5} composite cathodes had ASRs of 1.0 {Omega} cm{sup 2} and 0.73 {Omega}cm{sup 2} at 500 C and 0.048 {Omega}cm{sup 2} and 0.053 {Omega}cm{sup 2} at 650 C, respectively. These ASRs are truly impressive and makes them among the lowest IT-SOFC ASRs reported to date.
- Research Organization:
- Univ. of Florida, Gainesville, FL (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- FC26-03NT41959
- OSTI ID:
- 909486
- Country of Publication:
- United States
- Language:
- English
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