STABLE HIGH CONDUCTIVITY BILAYERED ELECTROLYTES FOR LOW TEMPERATURE SOLID OXIDE FUEL CELLS

Technical Report · Mon Sep 30 04:00:00 EDT 2002

DOI:https://doi.org/10.2172/834042· OSTI ID:834042

Wachsman, Eric D; Duncan, Keith L

A bilayer electrolyte consisting of acceptor-doped ceria (on the fuel/reducing side) and cubic-stabilized bismuth oxide (on the oxidizing side) was developed. The bilayer electrolyte that was developed showed significant improvement in open-circuit potential versus a typical ceria based SOFC. Moreover, the OCP of the bilayer cells increased as the thickness of the bismuth oxide layer increased relative to the ceria layer. Thereby, verifying the bilayer concept. Although, because of the absence of a suitable cathode (a problem we are still working assiduously to solve), we were unable to obtain power density curves, our modeling work predicts a reduction in electrolyte area specific resistance of two orders of magnitude over cubic-stabilized zirconia and projects a maximum power density of 9 W/m{sup 2} at 800 C and 0.09 W/m{sup 2} at 500 C. Towards the development of the bilayer electrolyte other significant strides were made. Among these were, first, the development of a, bismuth oxide based, oxide ion conductor with the highest conductivity (0.56 S/cm at 800 C and 0.043 S/cm at 500 C) known to date. Second, a physical model of the defect transport mechanisms and the driving forces for the ordering phenomena in bismuth oxide and other fluorite systems was developed. Third, a model for point defect transport in oxide mixed ionic-electronic conductors was developed, without the typical assumption of a uniform distribution of ions and including the effect of variable loads on the transport properties of an SOFC (with either a single or bilayer electrolyte).

• Research Organization: University of Florida (US)
• Sponsoring Organization: (US)
• DOE Contract Number: AC26-99FT40712
• OSTI ID: 834042
• Country of Publication: United States
• Language: English

Related Subjects

30 DIRECT ENERGY CONVERSION
BISMUTH OXIDES
CATHODES
DEFECTS
DISTRIBUTION
ELECTROLYTES
FLUORITE
OXIDES
POINT DEFECTS
POWER DENSITY
SIMULATION
SOLID OXIDE FUEL CELLS
THICKNESS
TRANSPORT