Chemistry: electrical and wave energy – Apparatus – Electrolytic
Reexamination Certificate
1999-04-16
2001-03-20
Valentine, Donald R. (Department: 1741)
Chemistry: electrical and wave energy
Apparatus
Electrolytic
C204S258000, C429S010000
Reexamination Certificate
active
06203676
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an ionic conduction device which may be used for examples only, as an oxygen generating device or as a fuel cell.
DESCRIPTION OF THE PRIOR ART
Such devices are known which comprise a stack of layers, each layer comprising a membrane of a suitable electrolyte, having a pair of opposed surfaces with an electrode in contact with each opposed surface. Such layers are also known as tri-layers by virtue of their three main component construction. The layers are conventionally separated by interconnects which also provide for gas flow throughout the device, and electrical continuity throughout the device.
For example in an oxygen generating device, the interconnects may provide for an air flow from a plenum along one side of the stack, over one of opposed faces of the layers, oxygen passing through the layers to the other of the opposed faces of the layers, the oxygen depleted gas being collected in a plenum along another of the stack sides, whilst the oxygen generated at the other of the faces of the layers, being collected in another plenum along yet another side of the stack.
Such devices are complex to make, requiring a large number of high quality components to be assembled. For example flatness of the components to a high degree is necessary for a satisfactory device to be provided.
One example of such an ionic conduction device which suffers from this drawback is described in U.S. Pat. No. 5,298,138-A, and another in U.S. Pat. No. 5,649,983-A. In both of these examples, the device construction is complex, and thus the devices are costly to produce.
SUMMARY OF THE INVENTION
According to one aspect of the invention we provide an ionic conduction device comprising a stack of layers, each layer comprising an electrolyte membrane having a pair of opposed surfaces, a gas permeable electrode in contact with each opposed surface, and there being a plurality of interconnects in electrical contact with the electrodes of the layers, to provide electrical continuity through the stack, wherein there is at least one gas flow path though the layers and the interconnects of the stack.
Thus in contrast with previously known devices, gas flow is through the layers and interconnects of the stack rather than though the stack to and from plenems along the sides of the stack. This considerably facilitates manufacture and construction and thus results in a substantial cost saving.
Most conveniently the gas flow path through the layers and interconnects is provided by passage means, the passage means opening at one face of the layer into a space between the layer and the adjacent interconnect, and the passage means extending from a second face of the layer to the next adjacent interconnect.
For example, there may be provided between the interconnects and the layers at the first and second faces of the layers, spaces, there being a first gas flow path through the layers and interconnects of the stack which permits of gas flow through the stack, and the first gas flow path communicating with the spaces at the first of the opposed faces of the layers, and a second gas flow path through the layers and interconnects of the stack which permits of gas flow through the stack, and the second gas flow path communicating with the spaces at the second of the opposed faces of the layers.
Thus the first and second gas flow paths may be kept physically separate from one another whilst ions of gas may pass through the electrolyte membrane to provide for gas transfer from one of the gas flow paths to the other.
The device may be used as either an oxygen generating device or a fuel cell, for examples only. In each case there may be provided a third gas flow path through the layers and interconnects of the stack, the third gas flow path communicating with the spaces at the first of the opposed faces of the layers.
In the case of an oxygen generating device, the first gas flow path may be for air, and the second gas flow path for the generated oxygen. The third gas flow path where provided, may be for oxygen depleted air. In the case of a fuel cell the first gas flow path may be for a fuel gas such as hydrogen, the second gas flow path may be for a gas comprising oxygen, and the third gas flow path may be for exhaust gas.
In each case, the passage means through the layers will necessarily comprise edges of the electrolyte membranes and electrodes. To prevent gas leakage from one of the flow paths to the other or another of the flow paths, particularly through the electrode material, means may be provided to seal at least the edges of the electrodes in the passage means to prevent gas leakage from one gas flow path to the other.
Preferably, between the interconnects and the electrodes of the layers there are provided films of a conducting material which may serve to improve the electrical connection between the interconnects and the electrodes and facilitate gas sealing at that interface.
The stack may comprise four sides, and first and second ends, the gas flow paths extending through the stack in a direction between the first and second ends thereof, and the first gas flow path though the stack may be provided adjacent one side of the stack, the second gas flow path adjacent a second side of the stack and the third gas flow path, where provided, adjacent a third side of the stack.
At at least one of the sides of the stack and/or in the or at least one of the gas flow paths through the stack, the layers may provide a stepped configuration with the electrolyte membrane extending outwardly at the side and/or inwardly of the gas flow path respectively, beyond the electrodes in contact with the opposed surfaces of the electrolyte membrane, and the electrodes may each extend outwardly at the side and/or inwardly of the gas flow path respectively, beyond the interconnects in electrical contact with the electrodes.
Where there are provided films of a conducting material between the interconnects and the electrodes, the electrodes may extend outwardly at the side and/or inwardly of the gas flow path respectively, beyond the films, and the films may extend outwardly at the side and/or inwardly of the gas flow path respectively, beyond the interconnects.
According to a second aspect of the invention we provide an ionic conduction device comprising at least one layer comprising an electrolyte membrane having a pair of opposed surfaces, a gas permeable electrode in contact with each opposed surface, and an interconnect in electrical contact with each of the electrodes, wherein at at least one of the sides of the stack the layer provides a stepped configuration with the electrolyte membrane extending outwardly beyond the electrodes in contact with the opposed surfaces of the electrolyte membrane, and the electrodes each extending outwardly beyond the interconnects in electrical contact with the electrodes.
According to a third aspect of the invention we provide a method of operating an ionic conduction device comprising a stack of layers, each layer comprising an electrolyte membrane having a pair of opposed surfaces, a gas permeable electrode in contact with each opposed surface, and there being a plurality of interconnects in electrical contact with the electrodes of the layers, to provide electrical continuity through the stack, the method comprising feeding gas to an end of the stack, and causing the gas to flow along the stack between the ends thereof.
REFERENCES:
patent: 4853100 (1989-08-01), Hsu
patent: 5186806 (1993-02-01), Clark et al.
patent: 5298138 (1994-03-01), Nachles et al.
patent: 5649983 (1997-07-01), Akagi
patent: 5770326 (1998-06-01), Limaye
patent: 40 16 157 (1990-12-01), None
patent: 0 501 401 (1992-09-01), None
patent: 0 698 936 (1996-02-01), None
patent: 0 706 229 (1996-04-01), None
European Search Report for Application No. EP 99 10 7669, dated Nov. 18, 1999.
Kilner John Anthony
Lane Jonathan Andrew
Phillips Robert John
Simons Adrian
Sirman John Derrick
Marshall O'Toole Gerstein Murray & Borun
Normalair-Garrett (Holdings) Limited
Valentine Donald R.
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