Integrated Solid Oxide Fuel Cells
INVENTION: Northwestern researchers have devised a new integrated solid oxide fuel cell (ISOFC) construct that combines the advantages of tubular and planar stack designs. An operating 4 cell unit has been demonstrated. The ISOFC is well suited for hydrogen or direct hydrocarbon oxidation.
ADVANTAGES: The ISOFC provides a simplified robust assembly with fewer seals, reduced electrical losses, optimal mechanical properties, and greater overall cell-volume efficiency. A straightforward fabrication process promises scaleable unit manufacture.
SUMMARY: Solid oxide fuel cells (SOFCs) are of increasing interest for clean power generation. Utilization of coal gasification by-products or hydrocarbons directly with these devices has significantly advanced over the past decade. Present day tubular cell stack designs minimize seal and manifold problems but have poor cell-volume efficiency and can exhibit significant ohmic losses. Planar cell stack configurations provide greater power/volume ratios but are mechanically less robust and require excellent seals. The ISOFC of this invention incorporates the advantages of both designs in a stack fuel cell with (1) a mechanically durable support that is not part of the electrical system, (2) no separate interconnects and less seals, (3) flatten tube cell seal-less design having high power/volume ratios, (4) reduced electrical losses and (5) greater overall stack performance.
The ISOFC incorporates an improved partially stabilized zirconia (PSZ) support composition exhibiting excellent porosity, mechanical properties and low leakage current (< 1% @ 600°C), improved anode (1 x 103 S/cm @ 500-800°C) and cathode compositions, and simple screen printing patterning fabrication. A demonstration four cell ISOFC unit has been constructed and successfully operated at 700°C employing air and humidified hydrogen fuel. Processing and materials optimizations to utilize hydrocarbon fuels have been accomplished.
STATUS: A patent application has been filed.
Scott Barnett, Jiang Liu, and Tammy Lai
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