ANODE, CATHODE AND THIN FILM STUDIES FOR LOW TEMPERATURE SOFC'S

Technical Report · Mon Nov 01 04:00:00 EST 1999

DOI:https://doi.org/10.2172/772380· OSTI ID:772380

Huebner, Wayne; Anderson, Harlan U

In this research the microstructure {leftrightarrow} property relations in solid oxide fuel cells (SOFC's) are being studied to better understand the mechanisms involved in cell performance. The overall aim is to fabricate SOFC's with controlled, stable, high performance microstructure. Most cathode studies were completed in the last DOE contract; studies during this year focused more on the influence of nonstoichiometry on the electrical performance. Studies indicate that nonstoichiometric La{sub x}Sr{sub 0.20}MnO{sub 3}(x = 0.70, 0.75, and 0.79) cathode compositions exhibit the best properties. A series of studies using these compositions fired on at temperatures of 1100, 1200, 1300 and 1400 C were performed. In all instances, 1200 C was the optimum, with the x = 0.70 composition being the best. It has an overpotential of only 0.04V at 1 A/cm{sup 2}. SEM analyses indicated no second phases or interdiffusion is detectable. Studies on optimization of anode compositions yielded the optimum volume fraction of Ni (45vol%), the best sintering temperature/time (1400 C/2 h), and the best starting materials (glycine-nitrate derived NiO and normal YSZ). In essence these results simply reflect the optimum microstructure. As such, they are being used to guide the development of optimized anodes for lower temperature operation based on Cu/CeO{sub 2} cermets. Marked success has been achieved on the placement of thin YSZ electrolytes on porous Ni/YSZ electrodes. The process being used is a transfer technique in which dense YSZ films are initially fabricated on NaCl or polymeric substrates, followed by partial dissolution of the substrate and placement of the film on the porous substrate. This technique has allowed us to produce structures with film thicknesses ranging from 70 to 3000 nm, and grain sizes ranging from 2 to 300 nm. Cells based on electrolytes this thick should operate in the 400--700 C range.

• Research Organization: Federal Energy Technology Center, Morgantown, WV (US); Federal Energy Technology Center, Pittsburgh, PA (US)
• Sponsoring Organization: US Department of Energy (US)
• DOE Contract Number: FG26-98FT40487
• OSTI ID: 772380
• Report Number(s): DE--FG26-98FT40487--01
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
36 MATERIALS SCIENCE
ANODES
CATHODES
CERIUM OXIDES
CERMETS
COPPER
GRAIN SIZE
LANTHANUM OXIDES
MANGANESE OXIDES
MICROSTRUCTURE
NICKEL
PERFORMANCE
SINTERING
SOLID ELECTROLYTE FUEL CELLS
SOLID ELECTROLYTES
STRONTIUM OXIDES
THIN FILMS
YTTRIUM OXIDES
ZIRCONIUM OXIDES