Chemistry: electrical current producing apparatus – product – and – With pressure equalizing means for liquid immersion operation
Reexamination Certificate
1999-03-01
2001-07-24
Huff, Mark F. (Department: 1756)
Chemistry: electrical current producing apparatus, product, and
With pressure equalizing means for liquid immersion operation
C429S006000, C429S006000, C429S006000, C429S006000, C429S006000
Reexamination Certificate
active
06265095
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to Solid Oxide Fuel Cells (“SOFC's”), and more particularly to an interconnect for use in solid oxide fuel cells.
2. Background Art
Two large barriers to market competitive SOFC's are interconnect functionality and cost. The design of a SOFC interconnect is important because the interconnect serves several functions, including, providing reactant gas separation and containment, providing mechanical support to the cells and providing a low resistance path for current to connect the cells in series. Although monolithic interconnects of lanthanum chromite and high chromium alloys have been used with some success, such interconnects have proven to be excessively costly and compromise certain aspects of interconnect functionality.
In particular, since the interconnect performs a multitude of functions, often it is necessary to compromise the performance of one function to enhance the performance with respect to another function of the interconnect. For example, the interconnect has an electrical function inasmuch as it provides a path by which to electrically connect cells in series, and the interconnect also has a mechanical function, namely, to provide mechanical support to the cell.
With respect to such functions, it is necessary to, for example, match coefficients of thermal expansion (CTE) between the cell and the interconnect, to provide support for the cell and also to facilitate gas containment. If the interconnect does not match the remainder of the cell with respect to the CTE, the structure may lose mechanical integrity and gas may leak out of the cell, thereby adversely affecting the efficiency of the cell. Often times, an interconnect, such as a monolithic interconnect that exhibits superior performance with respect to this mechanical function, may exhibit an unacceptable electrical conductive performance. Accordingly, to develop a suitable monolithic interconnect, it becomes necessary to sacrifice performance with respect to one function of the interconnect, such as the mechanical function, to increase performance with respect to another function of the interconnect, such as the electrical conductivity.
SUMMARY OF THE INVENTION
The invention comprises an interconnect for solid oxide fuel cells. The interconnect comprises a separator plate and a compliant material. The separator plate includes an anode side associateable with an anode of a first adjacent cell and a cathode side associateable with a cathode of a second adjacent cell. The compliant material is associated with at least one of the anode side of the separator plate and the cathode side of the separator plate. In turn, the compliant material provides mechanical support and electrical contact between the separator plate and the respective anode or cathode.
In a preferred embodiment, the at least one compliant sheet of material is positioned on the anode side of the separator plate. In such a preferred embodiment, another compliant sheet of material is positioned on the cathode side of the separator plate.
In another preferred embodiment, the at least one compliant sheet of material includes a plurality of openings extending therethrough. In such a preferred embodiment, the at least one compliant sheet of material includes a conductive coating applied to at least a portion of an upper and lower surface thereof. The coating may extend about a periphery of the at least one opening in the at least one compliant sheet of material. Thus, the coating on the upper surface and the lower surface are electrically connected. As an example, the coating may comprise AgPd or lanthanum cobaltite.
In yet another preferred embodiment, the at least one compliant material comprises a corrugated pattern having flutes. The at least one opening may comprise an elongated slot having its length substantially transverse to the flutes of the corrugated sheet.
In another preferred embodiment, the separator plate includes a coating applied to at least a portion of one of the cathode side and the anode side thereof.
In yet another preferred embodiment, the interconnect may further include means for sealing the anode side to the anode of the first adjacent cell and the cathode side to the cathode of a second adjacent cell. This, in turn, separates fuel and air flows past the cells.
The invention further comprises a method for manufacturing an interconnect for a solid oxide fuel cell comprising the steps of: providing the separator plate having the anode and cathode sides; associating the compliant sheet of material with one of the two sides; associating the anode side with an anode of a first adjacent cell; and associating the cathode side of the separator plate with a cathode of a second adjacent cell.
In a preferred embodiment, the step of associating the compliant sheet of material may further comprise the steps of: associating a first compliant sheet of material with the anode side of the separator plate, and associating a second compliant sheet of material with the cathode side of the separator plate.
In yet another preferred embodiment, wherein the compliant material includes an opening extending therethrough, the method further includes the step of applying a conductive coating to at least a portion of the first compliant sheet of material.
In another preferred embodiment, the method includes the step of applying a conductive coating on at least a portion of the separator plate.
The invention likewise includes a method for transferring electric current between two adjacent cells of a solid oxide fuel cell. The method comprises the steps of: providing a cathode side of a first adjacent cell; providing an anode side of a second adjacent cell; associating a compliant material with one of the anode and the cathode of the respective adjacent cells; positioning a separator plate between the compliant sheet of material and the other of the anode and the cathode which is not associated with the compliant sheet of material; and activating the first and second adjacent cells, to in turn, generate electrical current.
REFERENCES:
patent: 4857420 (1989-08-01), Maricle et al.
patent: 5460897 (1995-10-01), Gibson et al.
patent: 6054231 (2000-04-01), Virkar et al.
Elangovan Singaravelu
Hartvigsen Joseph Jay
Khandkar Ashok Chandrashekhar
Chacko-Davis Daborah
Factor & Partners
Huff Mark F.
Sofco
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