SOC stack including connection plate

Abstract

The solid oxide cell stack has at least one connecting plate between the solid oxide cell stack and one adjacent end plate, two adjacent end plates, and / or between adjacent solid oxide cell sub-stacks.

Description

Technical Field

[0001] The present invention relates to a solid oxide cell (SOC) stack, particularly a solid oxide electrolysis cell (SOEC) stack or a solid oxide fuel cell (SOFC) stack, comprising connection plates between the SOC stack and the current collector and / or between SOC sub-stacks.

Background Art

[0002] This invention can generally be used in an SOC stack and thus can be used in both the SOEC mode and the SOFC mode. However, for the sake of simplicity, some of the following descriptions relate to the SOEC mode.

[0003] In an SOC stack having an operating temperature between 600°C and 1000°C, preferably between 600°C and 850°C, several cell units are assembled to form a stack and are interconnected by interconnects. The interconnects serve as a gas barrier to separate the anode side and the cathode side of adjacent cell units, and at the same time they enable current conduction between adjacent cells, that is, between the anode of one cell and the cathode of the adjacent cell. Further, the interconnects usually have a plurality of flow channels for the passage of process gas provided on both sides of the interconnect. To optimize the performance of the SOC stack, a series of advantageous values should be maximized without resulting in unacceptable consequences for another series of related disadvantageous values that should be minimized. The following are some of these values:

[0004] Values to be maximized Values to be minimized - Process gas utilization rate - Cost - Electrical efficiency - Dimensions - Lifetime - Manufacturing time - Failure rate - Number of components - Parasitic losses (heating, cooling, blower...) - Material usage

[0005] Almost all of the values ​​listed above are interrelated, meaning that changing one value will affect the others. Here are some of the relationships between the characteristics of the process gas flow in the cell and the above values:

[0006] Process gas utilization rate: The flow paths in the interconnect should be designed so that an equal amount of process gas is obtained in each cell in the stack, that is, there should be no "shortcuts" in the flow through the stack.

[0007] Parasitic losses: The design of process gas flow paths in SOC stacks and their cell units should aim to achieve low pressure loss per flow volume, which reduces parasitic losses related to the blower.

[0008] Electrical efficiency: An interconnect conducts current between the anode and cathode layers of adjacent cells. Therefore, to reduce internal resistance, the conductive contact points of the interconnect (hereinafter simply referred to as "contact points") should be designed to establish good electrical contact with the electrodes (anode and cathode), and there should be no contact points that are far apart. If they are far apart, the current is forced to flow through longer distances between the electrodes, resulting in higher internal resistance.

[0009] lifespan: It is desirable to maximize the lifespan of the SOC stack, that is, to use it to generate as much electricity as possible in SOFC mode and to maximize the amount of electrolytic products (e.g., H2 and / or CO) in SOEC mode. Stack lifespan depends on many factors, including the selection of interconnects and spacers, the flow distribution on both process gas sides of the interconnects, uniformly distributed protective coatings on the material, operating conditions (temperature, current density, voltage, etc.), cell design and materials, edge re-oxidation which reduces lifespan, and many other factors.

[0010] cost: The cost contribution of interconnects (and spacers) can be reduced by not using expensive materials, by reducing the manufacturing time of interconnects and spacers, by minimizing the number of components, and by minimizing material loss (the amount of material discarded during the manufacturing process).

[0011] size: If the interconnect design ensures a high utilization rate of the active cell area, the overall dimensions of the fuel stack can be reduced. Dead areas with low process gas flow rates should be minimized, and inert areas on sealing surfaces should be reduced.

[0012] Manufacturing time: Manufacturing time for interconnects and spacers themselves should be minimized, and interconnect design should also contribute to the rapid assembly of the entire stack. Generally, each component that becomes unnecessary through interconnect design can be saved in terms of manufacturing time.

[0013] Failure rate: The methods and materials for manufacturing interconnects and spacers should enable a low interconnect failure rate (e.g., undesirable holes in the interconnect gas barrier, inconsistent material thickness or properties). Furthermore, by designing the interconnects to reduce the total number of components to be assembled and the length and number of sealing surfaces, the failure rate of the assembled cell stack can be reduced.

[0014] Number of components: In addition to minimizing the errors and assembly time mentioned above, reducing the number of components leads to cost reduction.

[0015] The anode and cathode gas flows are distributed within the SOC stack by having a common manifold for each of the two process gases. The manifold may be internal or external. The manifold supplies the process gas to individual layers in the SOC stack through channels to each layer. The channels are typically located in one layer of repeating elements in the SOC stack, i.e., in a spacer or interconnect.

[0016] Solid oxide electrolytic cells (SOECs) can be used to convert H2O to H2, CO2 to CO, or a combination of H2O and CO2 to syngas (H2 and CO). This conversion occurs on the cathode side (fuel side) of the SOEC, where the cell contains nickel-containing layers in their reduced state. On the oxy side (anode) of the SOEC, oxygen is produced, which is usually flushed with air.

[0017] When solid oxide cells are stacked to form a SOC stack, the cells are connected in series – separated by interconnects in an assembly known as a Single Repeat Unit (SRU). During the manufacturing of the stack, the series-connected layers are heated and compressed together to form a tightly packed stack. During this process, the mechanical loads used to compress the stack components together induce stress in the ceramic cells. A common failure mode is cell cracking, where the ceramic cells break due to the applied stress. If a single cell in the stack cracks, the entire stack must be discarded because the cracked cell will cause internal combustion in the stack during operation, damaging the rest of the stack. Therefore, if one cell in a 100-cell stack fails during manufacturing, the entire stack must be discarded, regardless of whether the remaining 99 cells are fine.

[0018] To mitigate the problem of discarding numerous well-functioning single repeating units (SRUs) when a crack occurs in one cell during stack manufacturing, smaller stacks (stacks with fewer SRUs) can be manufactured. These smaller sub-stacks can then be combined after manufacturing to form a full-size stack; for example, four sub-stacks with 25 SRUs each can be combined to form a full 100-cell stack. If a crack occurs in one cell in a 25-cell sub-stack, only 24 well-functioning SRUs are discarded, increasing the overall yield. Furthermore, sub-stacks are easier to handle, which can benefit certain parts of production.

[0019] When substacks are combined to form a full-size stack, the substacks overlap each other to form a single, continuously connected stack. There are two requirements for the connection of substacks: 1) Since the substacks are connected in series, the connection must be able to transmit current from one substack to the next. This current transfer must be uniform across the stack footprint to avoid causing an undesirable distribution in the substacks. 2) The connections between substacks must be hermetically sealed.

[0020] These described requirements also apply to interfaces at the ends of a full-size stack, specifically between the stack itself and any current collectors that may be present at each end of the full-size stack.

[0021] When connecting sub-stacks to each other, or full-size stacks to adjacent current collectors as described above, the following challenges exist (in particular): 1) enabling uniform current transfer from one sub-stack to the next, or from a full-size stack to an adjacent current collector, with minimal loss (voltage drop); and 2) creating an airtight connection between sub-stacks and / or between a full-size stack and a current collector. [Overview of the Initiative]

[0022] The present invention aims to achieve this with a simple and robust design that requires no sealing step before operating an assembled stack (consisting of sub-stacks and / or connected adjacent current collectors) with fewer components. A further problem to be solved by the present invention is to achieve the above with elements having a coefficient of thermal expansion (TEC) close to that of the sub-stack and thus of the full-size stack.

[0023] US2005016729 (Patent Document 1) discloses a ceramic fuel cell supported in a thermally conductive interconnect plate, where a plurality of plates form a conductive heater called a stack. By connecting a plurality of stacks, a rod-shaped fuel cell is formed. By connecting the plurality of stacks end to end, a fuel cell string is formed. The length of the string can be 1,000 feet or more and can be sized to penetrate a subterranean resource layer, such as an oil layer. A preheater raises the string to an operating temperature above 700°C, and then the fuel cell maintains its temperature via a plurality of conduits that supply fuel cell fuel and an oxidant, and moves exhaust gas to the planetary surface. A manifold can be used between the string and the planetary surface to connect the plurality of conduits and act as a heat exchanger between the exhaust gas and the oxidant / fuel.

[0024] None of the above-known technologies provide a concise and efficient solution to the above problems.

[0025] Therefore, referring to the considerations mentioned above, a simple, easy, yet robust, effective, and precise solution is needed for manufacturing a SOC stack including contact plates.

[0026] These and other objects are achieved by the present invention described below.

[0027] Summary of the Invention A solution for the assembly of sub-stacks, or for the connection between a full-size stack and an adjacent current collector, is a simple and robust connection consisting of the following 1) and 2): 1) a thin plate made of conductive material for conducting current between sub-stacks and / or between a full-size stack and an adjacent current collector, and 2) an axial gasket to ensure leak tightness between sub-stacks or between a full-size stack and an adjacent current collector.

[0028] The aforementioned thin plate is made of a conductive material suitable for the operating conditions, such as high-temperature steel (Crofer). The plate is very thin, for example, 0.5 mm in this case, in order to reduce the thermomechanical forces arising from the difference in TEC (Thermal Expansion Coefficient) between the sub-stack and the connecting plate, or between the full-size stack and the adjacent current collector, as described above.

[0029] In one embodiment, the connecting plate has holes / holes in the manifold that need to be sealed, which are slightly larger than the manifold holes in the sub-stack or full-size stack. These slightly larger holes are fabricated to accommodate space for an axial gasket (which may be circular, for example) placed within the connecting plate. By inserting a single gasket into the holes rather than inserting two gaskets from each side into grooves (for each gas connection), a much thinner connecting plate can be fabricated.

[0030] In one embodiment, the axial type gasket is made of a high-temperature gasket material, such as Flexitallic. The gasket is initially thicker than the connecting plate, for example, 1 mm thick for a 0.5 mm connecting plate. The reason the gasket is thicker than the connecting plate is that it can be compressed to obtain a tight interface to each sub-stack and tightness between the gasket itself, or between the full-size stack and the adjacent current collector.

[0031] When substacks are assembled together, or a full-size stack is assembled with an adjacent current collector, and operational compression is applied to the assembled stack, the gaskets (inserted in the connecting plate) between substacks or between a full-size stack and an adjacent current collector are compressed to the thickness of the connecting plate. This compression ensures that the gaskets are compressed and that electrical contact is created between substacks or between a full-size stack and an adjacent current collector across the entire stack footprint when the connecting plate is compressed.

[0032] In one embodiment, an inner metal ring can be inserted inside a gasket inserted into a connecting plate. This inner ring is the same height as (or slightly lower than) the connecting plate and is made of the same material as (or a similar material to) the connecting plate. The idea of ​​the inner ring is to support the gasket to prevent blow-in when the gasket is subjected to high external pressures, for example, on the order of 1 to 20 bar. Thus, the inner ring can be seen as a means of reinforcing the gasket solution of a sub-stack connection or full-size stack and a connection between adjacent current collectors, so that it can adapt to large pressure differences across the gasket.

[0033] The effect of the present invention is that sub-stacks, or full-size stacks and adjacent current collectors, are connected / tightened by compressible gaskets and are not bonded, reinforced, glassed, or welded together, so that sub-stacks, or full-size stacks and adjacent current collectors, can be disassembled / taken apart after operation.

[0034] In another embodiment, a solution to the sealing / gasket problem for compressing the gasket to achieve tightness with respect to electrical contact on the remaining surface is to insert the gasket into a recess in the connecting plate. The recess can be located on either side of the connecting plate where airtightness is required, and the recess may also be on both sides of the connecting plate to achieve tightness toward both sub-stacks or between the full-size stack and the adjacent current collector.

[0035] Manufacturing sub-stacks and combining them to form a full-size stack has the aforementioned effect of increasing manufacturing yield, as mentioned in the background of the invention. The proposed sub-stack connection, or connection between a full-size stack and an adjacent current collector, minimizes the thermal gradient at the sub-stack or full-size stack end, which is due to its small thermal mass being closer to the mass of the component, e.g., the interconnect of the SRU. This allows for the achievement of optimal operating conditions, ensuring that mechanical stress is minimized at the sub-stack and / or full-size stack end, thereby minimizing the risk of failure.

[0036] The proposed sub-stack connection, or connection between a full-size stack and an adjacent current collector, is a simple and robust solution involving only a few components. This solution is easy to assemble and does not require any manufacturing steps to assemble the sub-stack and / or the full-size stack and the adjacent current collector; they are simply stacked and ready to operate.

[0037] The large contact surface of the connecting plate ensures well-distributed contact and current to the sub-stack and / or full-size stack, while the small axial gasket minimizes the sealing area and thus increases the tightness of the connection.

[0038] Inserting a thicker gasket into the connecting plate and compressing the gasket to the thickness of the connecting plate is a simple and robust method to ensure good and uniform electrical contact between sub-stacks and / or between full-size stacks and adjacent current collectors, and to ensure sufficient compression of the compressible gasket to ensure tightness.

[0039] Optionally, adding a metal reinforcing ring of the same or slightly thinner thickness to the inner diameter of the gasket protects the gasket from blow-in when the gasket is subjected to large pressure differences in the range of 1 to 20 bar.

[0040] In one embodiment of the present invention as described in claim 1, the solid oxide cell stack comprises a plurality of stacked single repeating units, each single repeating unit comprising a solid oxide cell and an interconnect, as described above, one interconnect separating one cell from an adjacent cell in the cell stack. The solid oxide cell stack further comprises at least one connecting plate. The connecting plate can provide a uniform electrical connection between the solid oxide cell stack and an adjacent end plate (e.g., a current collector end plate as described above) across the entire cross-sectional area of ​​the solid oxide cell stack. As a further important feature of the present invention, the connecting plate can further provide a gas sealing around at least one manifold hole / hole (which provides a passage for process fluids in the solid oxide cell stack). To achieve this gas sealing, the connecting plate comprises at least one gasket area. The gasket area comprises a hole in the connecting plate corresponding to a manifold hole in the solid oxide cell stack, and the gasket area also comprises at least one gasket. The at least one gasket region surrounds the at least one manifold hole, i.e., one gasket region surrounds one manifold hole. The thickness of the gasket region during compression of the solid oxide cell stack is equal to the thickness of the connecting plate. Therefore, when the solid oxide cell stack is compressed, for example during operation, one or more gasket regions will have a thickness equal to the thickness of the connecting plate, and thus the solid oxide cell stack and the adjacent end plate will face the flat surface of the connecting plate. Of course, since all components of the solid oxide cell stack, including the SRU and connecting plate, are manufactured within specific tolerances as is common in the art and industry, it will be understood that the thickness of the gasket region during compression is not necessarily mathematically exactly equal to the thickness of the connecting plate.

[0041] In a particular embodiment of the present invention, each of the gasket regions comprises only a single gasket. One gasket in each gasket region is positioned inside a gasket hole in the connecting plate. Having only one gasket in each gasket region has the advantage of being simple and having minimal parts. In order to provide the above gas sealing, the thickness of the gasket when it is not compressed is greater than the thickness of the connecting plate. Thus, when the solid oxide cell stack and the connecting plate are compressed, the gasket is pressed between two opposing surfaces (the nearest SRU of the solid oxide cell stack and the adjacent end plate), providing sealing. It will be understood that gaskets known in the art are compressible and / or deformable, and therefore result in sealing.

[0042] In a further embodiment of the present invention, the perimeter of the gasket hole is greater than the perimeter of the gasket. This provides space / volume for the gasket to deform, while also providing sealing when the solid oxide cell stack is subjected to compressive forces as already described.

[0043] In another embodiment of the present invention, each gasket region includes not one but two gaskets. The two gaskets in each gasket region are positioned opposite each other on both sides of the connecting plate and around the holes in the connecting plate corresponding to adjacent manifold holes. Corresponding may mean that the holes have the same or nearly the same center, but it will be understood that other meanings are also possible. In this embodiment, the connecting plate includes recesses on both sides in each gasket region, each recess facing the other, and each recess is adapted to accommodate a gasket, so that the position of the gasket relative to the connecting plate is provided to some extent by the recesses. The thickness of the connecting plate in both opposite recesses plus the thickness of the two gaskets is greater than the remaining thickness of the connecting plate when the gaskets are not compressed, which provides the desired sealing as described above when the solid oxide cell stack is compressed, for example, during operation.

[0044] Similar to embodiments of the present invention having one gasket for each gasket region, this embodiment of the present invention having two gaskets for each gasket region also has embodiments in which the outer circumference of the recess is greater than the circumference of the gasket. In this case as well, this has the advantage that when the gasket is compressed and / or deformed when the entire solid oxide cell stack is compressed, the excess space provided by the larger recess allows the gasket to deform into this space while providing a seal.

[0045] In one embodiment of the present invention, each gasket region further includes an inner stabilizing ring adapted to support the inner circumference of the at least one gasket. The inner stabilizing ring provides a clear, free cross-sectional area through which process fluid can pass and flow, thus preventing damage to this area by the gasket when it is compressed and / or deformed. More importantly, the stabilizing ring protects the at least one gasket from blow-in-out when the solid oxide cell stack is operated with interlayer pressure differences in the stack (e.g., between the anode and cathode, or between the SRU and adjacent end plates if a connecting plate is placed between them).

[0046] In one embodiment of the present invention, the inner stabilizing ring has an inner circumference equal to or greater than the corresponding manifold hole of the solid oxide cell stack, so that the flow of process fluid through the manifold hole is not restricted by the connecting plate. Furthermore, the inner stabilizing ring has an outer circumference smaller than the inner circumference of at least one gasket and a thickness equal to or thinner than the thickness of the connecting plate, so that the stabilizing ring does not restrict the compression of the solid oxide cell stack.

[0047] In one embodiment of the present invention, each hole in the connecting plate corresponding to the manifold hole has a larger circumference than the corresponding manifold hole and is large enough to provide an area for the at least one gasket without restricting the flow in the manifold. As discussed above, it is also important that the holes in the connecting plate and the corresponding manifold holes have the same center (within tolerance) in order not to restrict the flow.

[0048] In certain embodiments, each gasket, each manifold hole, and each hole in the connecting plate are circular. This offers advantages such as ease of manufacture, improved process fluid flow, and good sealing in the gasket area.

[0049] In one embodiment of the present invention, the force for compressing the solid oxide cell stack is greater than the compressive force for the total number of gaskets on the connecting plate, and is large enough to provide uniform electrical connection between the solid oxide cell stack, the connecting plate, and the adjacent end plate across the entire cross-sectional area of ​​the solid oxide cell stack. Therefore, when compressing the solid oxide cell stack, there is not only enough force to compress and / or deform the total number of gaskets contained in the connecting plate, thereby providing effective sealing, but also an excess compressive force to ensure uniform contact between the stacked solid oxide cells and the adjacent end plate, and thus electrical connection, across the entire cross-sectional area of ​​the solid oxide cell stack.

[0050] In certain embodiments of the present invention, the thickness of the contact plate is small enough to conform to the surfaces and irregularities of the adjacent solid oxide cell stack and adjacent end plate, and large enough to stand upright during manufacturing. It will be understood that this thickness depends, among other things, on the material of the connecting plate and the size / area of ​​the connecting plate. Thus, in certain embodiments of the present invention, the thickness of the contact plate is 0.2 to 1.6 mm; in further embodiments of the present invention, the contact plate is made of steel or other suitable material. In further certain embodiments of the present invention, the thickness of the contact plate is equal to the thickness of the interconnect (within manufacturing and / or viable tolerances); in further embodiments, the contact plate is made of the same material as the interconnect. Both of these embodiments described above have the advantage, among other things, that the TEC of the connecting plate is very similar to the TEC of the solid oxide cell stack, or at least to a considerable extent, similar to the interconnect of the solid oxide cell stack (the interconnect has a flow field). In further embodiments of the present invention, the connecting plate is coated; in certain embodiments, the coating comprises Ni or Cu, or both Ni and Cu.

[0051] In one embodiment of the present invention, the surface area of ​​one or more single repeating units facing at least one gasket is a uniform surface area that is large enough to provide gas sealing to the gasket around the manifold hole, and thus the surface of the area facing at least one gasket is adapted to be best suited for effective sealing against process fluid leakage.

[0052] In a particular embodiment of the present invention, the solid oxide cell stack is a solid oxide electrolytic cell stack; in a further embodiment, the solid oxide cell stack is a solid oxide electrolytic cell stack, and the contact plate includes gaskets around one or more manifold holes. The contact plate may include gaskets around all manifold holes of the solid oxide electrolytic cell stack, but in a particular embodiment, the contact plate includes gaskets around one or more oxy-side (oxygen-side) manifold holes, but does not include a seal around at least one fuel-side manifold hole. This may be advantageous when a certain amount of process fluid flushing around the fuel-side manifold hole is desired depending on the process.

[0053] As discussed above, the connecting plate can be used not only between the entire solid oxide cell stack and adjacent end plates, but also between solid oxide cell substacks. Accordingly, in one embodiment of the present invention, the at least one connecting plate can further provide a uniform electrical connection across the entire cross-sectional area of ​​the solid oxide cell stack between one substack of the solid oxide cell stack and an adjacent substack of the solid oxide cell stack, and the connecting plate can further provide gas sealing around at least one manifold hole in the substack of the solid oxide cell stack. The advantages of dividing the entire solid oxide cell stack into multiple substacks are discussed above.

[0054] Features of the present invention 1. A solid oxide cell stack comprising a plurality of stacked single repeating units, each single repeating unit comprising a solid oxide cell and an interconnect, one interconnect separating one cell from an adjacent cell in the cell stack, the solid oxide cell stack further comprising at least one connecting plate between the solid oxide cell stack and an adjacent end plate, capable of providing a uniform electrical connection across the entire cross-sectional area of ​​the solid oxide cell stack, the connecting plate further capable of providing a gas seal around at least one manifold hole in the solid oxide cell stack, the connecting plate comprising at least one gasket region, the gasket region comprising a hole in the connecting plate corresponding to the manifold hole and comprising at least one gasket and surrounding the at least one manifold hole, the thickness of the gasket region during compression of the solid oxide cell stack being equal to the thickness of the connecting plate, the solid oxide cell stack.

[0055] 2. The solid oxide cell stack according to feature 1, wherein each gasket region includes one gasket positioned within a gasket hole in the connecting plate, and the thickness of the gasket when it is not compressed is greater than the thickness of the connecting plate.

[0056] 3. The solid oxide cell stack according to feature 2, wherein the circumference of the gasket hole is greater than the circumference of the gasket.

[0057] 4. The solid oxide cell stack according to Feature 1, wherein each gasket region includes two gaskets positioned opposite each other on both sides of the connecting plate and around a hole in the connecting plate, the hole corresponding to an adjacent manifold hole, the connecting plate includes recesses on both sides in each gasket region, the recesses are opposite each other, and the recesses are adapted to accommodate a gasket, and the sum of the thickness of the connecting plate and the thickness of the two gaskets within the opposing recesses is greater than the remaining thickness of the connecting plate when the gaskets are not compressed.

[0058] 5. The solid oxide cell stack according to feature 4, wherein the outer circumference of the recess is greater than the circumference of the gasket.

[0059] 6. The solid oxide cell stack according to feature 1, wherein each gasket region further includes an inner stabilizing ring adapted to support the inner circumference of at least one gasket.

[0060] 7. The solid oxide cell stack according to feature 6, wherein the inner stabilizing ring has an inner circumference equal to or greater than the corresponding manifold hole of the solid oxide cell stack, an outer circumference less than the inner circumference of the at least one gasket, and a thickness equal to or less than the thickness of the connecting plate.

[0061] 8. A solid oxide cell stack according to any one of features 1 to 7, wherein each hole in the connecting plate corresponding to a manifold hole has a larger circumference than the corresponding manifold hole and is large enough to provide an area for the at least one gasket without restricting the flow in the manifold.

[0062] 9. A solid oxide cell stack according to any one of features 1 to 8, wherein each gasket, each manifold hole, and each hole in the connecting plate are circular.

[0063] 10. The solid oxide cell stack according to any one of features 1 to 9, wherein the compressive force for the solid oxide cell stack is greater than the compressive force for the total number of gaskets in the connecting plate, and is sufficiently large to provide a uniform electrical connection between the solid oxide cell stack, the connecting plate, and the adjacent end plate, across the entire cross-sectional area of ​​the solid oxide cell stack.

[0064] 11. A solid oxide cell stack according to any one of features 1 to 10, wherein the thickness of the contact plate is thin enough to conform to the surface and irregularities of an adjacent solid oxide cell stack and an adjacent end plate, and thick enough to stand upright during manufacturing.

[0065] 12. A solid oxide cell stack according to any one of features 1 to 11, wherein the thickness of the contact plate is between 0.2 and 1.6 mm.

[0066] 13. The solid oxide cell stack according to any one of features 1 to 12, wherein the contact plate is made of steel or other suitable material.

[0067] 14. The solid oxide cell stack according to any one of features 1 to 13, wherein the connecting plate is coated.

[0068] 15. The solid oxide cell stack according to any one of features 1 to 14, wherein the connecting plate is coated with Ni or Cu, or with both Ni and Cu.

[0069] 16. The solid oxide cell stack according to any one of features 1 to 15, wherein the thickness of the contact plate is equal to the thickness of the interconnect.

[0070] 17. The solid oxide cell stack according to any one of features 1 to 16, wherein the contact plate is made of the same material as the interconnect.

[0071] 18. A solid oxide cell stack according to any one of features 1 to 17, wherein the surface area of ​​the one or more single repeating units facing the at least one gasket is a flat surface area that is large enough to provide gas sealing to the gasket around the manifold hole.

[0072] 19. The solid oxide cell stack according to any one of features 1 to 18, wherein the solid oxide cell stack is a solid oxide electrolytic cell stack.

[0073] 20. The solid oxide cell stack according to any one of features 1 to 19, wherein the solid oxide cell stack is a solid oxide electrolytic cell stack, and the contact plate includes a gasket around one or more manifold holes.

[0074] 21. The solid oxide cell stack according to any one of features 1 to 20, wherein the solid oxide cell stack is a solid oxide electrolytic cell stack, and the contact plate includes gaskets around one or more oxygen-side manifold holes, but does not include a seal around at least one fuel-side manifold hole.

[0075] 22. The solid oxide cell stack according to any one of features 1 to 21, wherein the at least one connecting plate is further capable of providing a uniform electrical connection across the entire cross-sectional area of ​​the solid oxide cell stack between one sub-stack of the solid oxide cell stack and an adjacent sub-stack of the solid oxide cell stack, and the connecting plate is further capable of providing gas sealing around at least one manifold hole in the sub-stack of the solid oxide cell stack. [Brief explanation of the drawing]

[0076] The present invention will be further explained with reference to the accompanying drawings illustrating examples of embodiments of the present invention.

[0077] Figure 1 shows an isometric top view of the connecting plate. Figure 2 shows an equiangled top view detail of the connecting plate shown in Figure 1. Figure 3 shows a top view of the connecting plate. Figure 4 shows a detailed side cross-sectional view of the connecting plate shown in Figure 3. Figure 5 shows a schematic top view of a single repeating unit SRU (the connecting plate and any further SRUs beneath it are hidden from view). Figure 6 shows a detailed side cross-sectional view of the SRU in Figure 5, as well as a connecting plate and further SRUs.

[0078] Location number 01. Connection Plate 02. Manifold hole, center 03. Manifold holes 04. Gasket 05. Internal stabilization ring 06. Single Repeating Unit (SRU)

[0079] Detailed explanation Figure 1 shows an isometric top view of a connecting plate 01 according to one embodiment of the present invention. As described above, the connecting plate is adapted to be positioned between the solid oxide cell stack and the end plate (e.g., current collector), and / or between the solid oxide cell sub-stack. However, the sub-stack and end plate are known in the art and are therefore not shown in the figure. The connecting plate in this embodiment includes four manifold holes 03 located near the outer edge of the connecting plate and a central manifold hole 02 located in the center of the connecting plate within the tolerances already discussed.

[0080] A detailed isometric top view (G) of one of the manifold holes is shown in Figure 2. A gasket 04 is placed inside each manifold hole. As can be seen more clearly in some of the following figures, the thickness of the gasket is greater than the thickness of the connecting plate. Thus, as stated above, this is an embodiment of the present invention having only one gasket for each manifold hole. As can be seen from Figure 2, in this embodiment, the manifold holes in the connecting plate have a circumference greater than the outer diameter of the gasket when the gasket is not compressed and / or deformed as shown in Figure 2. As stated above, this has the advantage that the gasket can deform and fill the gap created between the inner wall of the connecting plate manifold hole and the outer diameter of the gasket, thus giving the entire solid oxide cell stack, including the connecting plate, the ability to seal while the gasket thickness is reduced to the thickness of the connecting plate when compressed, for example, during operation. Figure 2 also shows an inner stabilizing ring 05 placed inside the gasket. As described above, this ring stabilizes the sealing gasket against blow-in when subjected to a pressure difference on both sides of the gasket, and further provides a clear inner diameter in the resulting cross-sectional area, allowing for free process fluid flow through the manifold hole.

[0081] Figure 3 shows a diagram of the connecting plate that is almost identical to that in Figure 1, but here it is a top view. However, the detailed cross-sectional side view BB in Figure 4 shows in more detail how much thicker the gasket is than the connecting plate and inner stabilizing ring (when not subjected to compressive force). Also, the gap, i.e., the free space between the inner circumference of the manifold hole in the connecting plate and the outer diameter of the gasket, can be clearly seen.

[0082] The detailed side cross-sectional views in Figures 5 and 6(KK) illustrate an embodiment of the present invention in which a connecting plate is positioned between two solid oxide cell substacks. Only the first SRU06 of each solid oxide substack is shown, rather than the entire solid oxide substack, and the SRUs are adjacent to each other on each side of the connecting plate. As stated above, it will be understood that instead of two SRUs, the connecting plate may be positioned between one SRU (on one side) and an end plate (on the other side), according to another embodiment of the present invention and as described above. Between two SRUs, or between an SRU and an end plate, Figure 6 shows how, when the entire solid oxide cell stack and possibly the end plate(s) are subjected to compressive force, the gasket thickness decreases to the same thickness as the connecting plate, thus providing a seal around the manifold hole without requiring a more cumbersome glass seal. It can also be seen how the stabilizing ring provides internal stabilization of the gasket, thus preventing the gasket from blowing out or blowing in into the manifold hole when subjected to a pressure difference between the two sides of the gasket. The stabilizing ring does not need to be the same thickness as the connecting plate to provide the necessary stabilization; therefore, in one embodiment of the present invention, it will be understood that the thickness of the stabilizing ring may be slightly less than the thickness of the connecting plate to prevent the stabilizing ring from interfering when the entire solid oxide cell stack and possibly the end plates(s) are subjected to compressive forces. That is, as mentioned above, it is also an important feature of the connecting plate that the two SRUs, or the SRU and the end plates, provide element-to-element electrical contact on both sides of the connecting plate, even if it spans the entire cross-sectional area of ​​the connecting plate, because this is essential for the operation of the solid oxide cell stack. Therefore, as mentioned above, it may also be advantageous that the compressive force on the solid oxide cell stack and possibly the end plates(s) is greater than the force required to compress all the gaskets arranged on one or more connecting plates.

Claims

1. A solid oxide cell stack comprising a plurality of stacked single repeating units, each single repeating unit comprising a solid oxide cell and an interconnect, one interconnect separating one cell from an adjacent cell in the cell stack, the solid oxide cell stack further comprising at least one connecting plate 01 between the solid oxide cell stack and an adjacent end plate, capable of providing a uniform electrical connection across the entire cross-sectional area of ​​the solid oxide cell stack, the connecting plate further capable of providing a gas seal around at least one manifold hole 03 in the solid oxide cell stack, the connecting plate comprising at least one gasket region, the gasket region comprising a hole in the connecting plate corresponding to the manifold hole and comprising at least one gasket 04 and surrounding the at least one manifold hole, the thickness of the gasket region during compression of the solid oxide cell stack being equal to the thickness of the connecting plate, the solid oxide cell stack.

2. The solid oxide cell stack according to claim 1, wherein each gasket region includes one gasket positioned within a gasket hole in the connecting plate, and the thickness of the gasket when it is not compressed is greater than the thickness of the connecting plate.

3. The solid oxide cell stack according to claim 2, wherein the circumference of the gasket hole is greater than the circumference of the gasket.

4. The solid oxide cell stack according to claim 1, wherein each gasket region includes two gaskets positioned opposite each other on both sides of the connecting plate and around a hole in the connecting plate, the hole corresponding to an adjacent manifold hole, the connecting plate includes recesses on both sides in each gasket region, the recesses are opposite each other, and the recesses are adapted to accommodate a gasket, and the sum of the thickness of the connecting plate and the thickness of the two gaskets within the opposing recesses is greater than the remaining thickness of the connecting plate when the gaskets are not compressed.

5. The solid oxide cell stack according to claim 4, wherein the outer circumference of the recess is greater than the circumference of the gasket.

6. The solid oxide cell stack according to claim 1, wherein each gasket region further includes an inner stabilizing ring 05 adapted to support the inner circumference of at least one gasket.

7. The solid oxide cell stack according to claim 6, wherein the inner stabilizing ring has an inner circumference equal to or greater than the corresponding manifold hole of the solid oxide cell stack, an outer circumference less than the inner circumference of the at least one gasket, and a thickness equal to or less than the thickness of the connecting plate.

8. The solid oxide cell stack according to any one of claims 1 to 7, wherein each hole in the connecting plate corresponding to a manifold hole has a circumference greater than the corresponding manifold hole and is large enough to provide an area for the at least one gasket without restricting the flow in the manifold.

9. The solid oxide cell stack according to any one of claims 1 to 8, wherein each gasket, each manifold hole, and each hole in the connecting plate are circular.

10. The solid oxide cell stack according to any one of claims 1 to 9, wherein the compressive force for the solid oxide cell stack is greater than the compressive force for the total number of gaskets in the connecting plate, and is sufficiently large to provide a uniform electrical connection between the solid oxide cell stack, the connecting plate, and the adjacent end plate across the entire cross-sectional area of ​​the solid oxide cell stack.

11. The solid oxide cell stack according to any one of claims 1 to 10, wherein the thickness of the contact plate is thin enough to allow the contact plate to conform to the surface and irregularities of the adjacent solid oxide cell stack and adjacent end plate, and thick enough to stand upright during manufacturing.

12. The solid oxide cell stack according to any one of claims 1 to 11, wherein the thickness of the contact plate is between 0.2 and 1.6 mm.

13. The solid oxide cell stack according to any one of claims 1 to 12, wherein the contact plate is made of steel or other suitable material.

14. The solid oxide cell stack according to any one of claims 1 to 13, wherein the connecting plate is coated.

15. The solid oxide cell stack according to any one of claims 1 to 14, wherein the contact plate is coated with Ni or Cu, or with both Ni and Cu.

16. The solid oxide cell stack according to any one of claims 1 to 15, wherein the thickness of the contact plate is equal to the thickness of the interconnect.

17. The solid oxide cell stack according to any one of claims 1 to 16, wherein the connecting plate is made of the same material as the interconnect.

18. The solid oxide cell stack according to any one of claims 1 to 17, wherein the surface area of ​​the one or more single repeating units facing the at least one gasket is a flat surface area that is large enough to provide gas sealing to the gasket around the manifold hole.

19. The solid oxide cell stack according to any one of claims 1 to 18, wherein the solid oxide cell stack is a solid oxide electrolytic cell stack.

20. The solid oxide cell stack according to any one of claims 1 to 19, wherein the solid oxide cell stack is a solid oxide electrolytic cell stack, and the contact plate includes a gasket around one or more manifold holes.

21. The solid oxide cell stack according to any one of claims 1 to 20, wherein the solid oxide cell stack is a solid oxide electrolytic cell stack, and the contact plate includes gaskets around one or more oxygen-side manifold holes, but does not include a seal around at least one fuel-side manifold hole.

22. The solid oxide cell stack according to any one of claims 1 to 21, wherein the at least one connecting plate is further capable of providing a uniform electrical connection across the entire cross-sectional area of ​​the solid oxide cell stack between one sub-stack of the solid oxide cell stack and an adjacent sub-stack of the solid oxide cell stack, and the connecting plate is further capable of providing gas sealing around at least one manifold hole in the sub-stack of the solid oxide cell stack.

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