Electrolytic cell unit having a flat separator and method for manufacturing the electrolytic cell unit

Abstract

The present invention relates to an electrolytic cell unit having a cell layer (1314) comprising an electrochemically active cell region (1350), the cell layer (1314) having a first side (1315a) and a second side (1315b). The cell unit defines a first fluid flow region (1360) for delivering fuel to the first side (1315a) of the cell layer (1314) and a second fluid flow region (1365) for discharging fluid from the second side (1315b) of the cell layer (1314). The cross-sectional area of ​​the second fluid flow region (1365) is smaller than the cross-sectional area of ​​the first fluid flow region (1360).

Description

Technical Field

[0001] The present invention relates to an electrochemical cell unit having a flat separator, particularly a fuel cell unit and an electrolysis cell unit, a stack including such cell units, a method for manufacturing a separator plate (interconnect) for use in such cell units, a separator plate formed in this way, and the use of such cell units. The cell units of the present invention include solid oxide, polymer electrolyte membrane, and molten carbonate type cells. More specifically, the present invention relates to solid oxide fuel cell (SOFC) units and solid oxide electrolysis cell (SOEC) units, which may include metal-supported solid oxide fuel cell (MS-SOFC) units or metal-supported electrolysis cell (MS-SOEC) units.

Background Art

[0002] Some electrochemical cell units can generate electricity by using an electrochemical conversion process that oxidizes a fuel to generate electricity. Some electrochemical cell units can also, or alternatively, operate as a regenerative fuel cell (or reversible fuel cell) unit, often referred to as an electrolysis cell unit, for example, to generate hydrogen and oxygen from water or carbon monoxide and oxygen from carbon dioxide. They can have a tubular or planar form. Planar electrochemical cell units can be arranged to overlap each other in a stack arrangement (e.g., 100 to 200 electrochemical cell units in a stack), and individual electrochemical cell units are arranged, for example, electrically in series.

[0003] Solid oxide fuel cells (SOFCs), which generate electricity, are based on a solid oxide electrolyte that conducts negative oxygen ions from the cathode to the anode, located on either side of the electrolyte. For this purpose, the fuel or reformed fuel is in contact with the anode (fuel electrode), and the oxidizer, such as air or an oxygen-rich fluid, is in contact with the cathode (air electrode). Conventional ceramic-supported (e.g., anode-supported) SOFCs have low mechanical strength and are prone to breakage. Therefore, metal-supported SOFCs, which have an active fuel cell component layer supported on a metal substrate, have been developed. In these cells, the ceramic layer can be very thin because it only performs electrochemical functions. That is, the ceramic layer is not self-supporting, but rather a thin coating / film placed on and supported by the metal substrate. Such metal-supported SOFC stacks are more robust, lower cost, have better thermal properties, and can be manufactured using conventional metal welding techniques than ceramic-supported SOFCs.

[0004] Solid oxide electrolytic cells (SOECs) can have the same structure as SOFCs, but essentially, SOFCs operate in reverse or regenerative mode to achieve electrolysis of water and / or carbon dioxide by inputting electrical energy, while using a solid oxide electrolyte to produce hydrogen gas and / or carbon monoxide, as well as oxygen.

[0005] This invention relates to electrochemical cell units and the design of separator plates therefor. Therefore, the invention is applicable to various types of fuel and electrolytic cells, for example, based on solid oxide electrolytes, polymer electrolyte membranes, or fused electrolytes. For convenience, the term "cell unit" is used to refer to an "electrochemical cell unit" including a fuel or electrolytic cell unit.

[0006] Each cell unit in a stack of cell units typically includes a cell layer comprising an electrochemically active cell region (such as a metal-supported electrochemically active cell region) and a separator plate. The separator plate typically contacts one side of the cell layer of a cell unit and may also contact the opposite side of the cell layer of a neighboring cell unit in the stack of cell units. In a stack of cell units, the separator plate that contacts one side of the cell layer of a cell unit and the opposite side of the cell layer of a neighboring cell unit may be referred to as an "interconnect."

[0007] Figure 1 is an exploded perspective view of a cell unit with two gaskets, extracted from the applicant's earlier application, UK Patent Application Publication No. 2603665(A), which discusses an electrochemical cell unit and a stack comprising multiple such electrochemical cell units having raised elements. The cell unit 10 in Figure 1 comprises a flat (i.e., planar) metal support plate 14 stacked next to a separator plate 12. The separator plate 12 is shown to have a flanged periphery 18 on its edge. The flanged periphery 18 extends from the main plane of the sheet, as seen in the central fluid volume region, forming a concave surface (and a convex surface on the outer surface) on the separator plate. This concave surface forms a fluid volume within the cell unit when the cell unit is assembled.

[0008] In the configuration shown in Figure 1, the cell unit 10 has rounded ends and parallel sides, and has fluid ports 22 extending toward each end of both the separator plate 12 and the metal support plate 14. Other shapes, sizes, and numbers of each cell feature are possible depending on the required output and dimensions of the final stack assembly.

[0009] A molded port feature portion 24 is provided around the fluid port of the separator plate 12. The molded port feature portion 24 is provided as a plurality of elements in the form of circular dimples extending from the plane of the base of the fluid volume by a distance corresponding to the height of the flanged periphery portion 18, that is, it is provided so as to have the same height as the flanged periphery portion 18. This is so that when the cell unit 10 is assembled, the molded port feature portion 24, like the flanged periphery portion 18, will contact the opposing surface of the metal support plate 14. As a result, when the flanged periphery portion 18 is joined to the metal support plate 14, for example by welding, the molded port feature portion 24 will also contact the metal support plate 14.

[0010] In the central portion of the cell unit 10, an electrochemically active layer 50 is provided on a metal support plate. In this example, the electrochemically active layer 50 is located outside the closed fluid volume.

[0011] The electrochemically active region 50 includes an anode, a cathode, and an electrolyte (not shown) positioned between the anode and the cathode. The anode, electrolyte, and cathode may together be referred to as the electrochemically active layer 50, the active electrochemical cell layer, or the electrochemically active region. The electrolyte conducts either negative oxygen ions or positive hydrogen ions between the anode and the cathode. The stack 20 may comprise a stack of cell units based on one of a solid oxide electrolyte, a polymer electrolyte membrane, or a molten electrolyte, or any other variant capable of electrochemical action.

[0012] The concave structure can impart to the associated plate the appearance of a bordered tray with a corresponding convex outer shape (outward relative to the cell unit) and usually a planar base, and thus the concave surface defines the fluid volume (e.g., a portion thereof) within the assembled cell unit. In this concave structure, the flanged periphery extends from the plane of the original sheet of the separator plate and / or the metal support plate toward the respective opposing surfaces of the separator plate and the other metal support plate.

[0013] Therefore, the fluid volume is bounded by flanged periphery formed by press working using die pressing, hydroforming, or stamping. These are simple processes already performed in the formation of central protrusions within the fluid volume (described below), similarly seen on conventional separator plates, to support and electrically connect adjacent cells via an electrochemically active layer.

[0014] Figure 2 is an exploded bottom perspective view of the cell unit of Figure 1. The metal support plate 14 (e.g., metal foil) is provided with a number of small holes or pores 48 to allow the fluid in the fluid volume to come into contact with the side of the electrochemical layer closest to the metal support plate 14. These form porous regions bounded by non-porous regions. The anode (fuel electrode) layer is located close to the small holes / pores, and the (closed) fluid volume within the cell unit has a fuel flow volume supplied by fuel entering and exiting through the fluid port 22, and thus the fluid port 22 is the fuel port 22. The cathode (air electrode) layer is located on the opposite side of the electrochemically active layer 50, i.e., on its outer surface, and is exposed to air flowing across its layer during use of the cell unit 10. Figure 2a is a simplified cross-sectional view of the configuration shown in Figures 1 and 2.

[0015] The cell unit shown in Figures 1 and 2 requires only two layers (components): a metal support plate and a separator plate.

[0016] Furthermore, there are central upward-facing projections 32 and central downward-facing projections 36, which include internal and external projections (up and down as shown) extending between the inner opposing surfaces of the two plates and the outer surface of the electrochemically active layer of the cell unit adjacent to the outward-facing projections. The central upward-facing projections 32 define a fluid path for fuel between or within them, the fluid path passing through a closed fluid volume between the fluid ports at each end of the cell unit. The central downward-facing projections 36 define a fluid path for an oxidizer (such as air) between or within them, passing through a fluid volume defined between the downward-facing projection and the outer surface of the electrochemically active layer of the cell unit adjacent to the downward-facing projection.

[0017] Each gasket, for example, gasket 34 (also called a "seal"), performs a primary sealing function and is typically a compressible gasket that is subjected to high compressive forces near the port.

[0018] The gasket is sized to cover all of the molded port features 24 of each fluid port 22, thereby preventing fluids (such as fuel) that may move through the fluid ports 22 in the stack from leaching out from between the outside of the cell unit 10 and the gasket (e.g., gasket 24) into the area outside the cell unit, i.e., the fluid surrounding the cell unit 10 (such as oxidizer), or from leaching out in the other direction, i.e., into the fluid ports. This is important to prevent any mixing of the fluid inside the cell unit 10 and the fluid outside the cell unit 10 (which are fuel and oxidizer). The polarity of the electrochemically active layer 50 determines which direction this is.

[0019] The gasket may also electrically insulate the first cell unit 10 from the adjacent fluid cell unit 10 to prevent short circuits. The gasket may be any suitable cell gasket (sealing ring), such as a vermiculite-based gasket, such as Thermiculite®.

[0020] Cell stacks have various internal resistance sources. One such resistance source is the contact resistance between the separator plate and the adjacent cell layer.

[0021] The cell stack has upper and lower compression plates connected to each other by bolts or other means, allowing the cell units (including multiple) between them to be compressed relative to each other. The compressive force applied to the stack is sufficient to form a seal to prevent leaching from the cell units (including multiple) and / or to prevent fluid from outside the fluid port from leaching into the fluid port.

[0022] The compressive force within the stack in the planar area of ​​the electrochemically active region is necessary for good electrical contact and, consequently, good conductivity through the stack. The central upward projection 32 and central downward projection 36 create the necessary electrical contact between cell units and also serve as support for the cell units in the central region, extending upward to the lower surface of the metal support plate 14 in the area of ​​the small holes or pores 48 and downward to the opposing surface of the electrochemically active layer of the cell below. Furthermore, the molded port feature 24 around the port 22 helps transmit the compressive force within the stack at the peripheral ends of each unit cell, generating the compressive force necessary to form a seal. To minimize contact resistance between the separator plate and the adjacent cell layer, it is necessary to maintain pressure between the separator plate and the adjacent cell layer. This is the function of the upward projection 32. However, including such upward projection 32 also has its own disadvantages. For example, the upward projection 32 can block the holes or pores 48 in the metal support plate 14, hindering the flow of fuel to the electrochemically active cell region. In practice, these protrusions reduce the efficiency of the cell unit by reducing fluid access to (and discharge of products from) the electrochemically active cell region through the pores 48. Those skilled in the art will understand that the electrodes supplied by the pores 48 are adapted to move reactants into the electrolyte themselves, and therefore, the pores blocked by the protrusions 32 reduce the supply to (and discharge from) the electrochemically active cell region, but do not render inoperable the portion of the electrochemically active cell region adjacent to the blocked pores. The upward-facing protrusions 32 may further obstruct the flow of fluid (such as fuel) across the cell unit, reducing the volume capacity for the flow of the fluid. [Overview of the Initiative] [Problems that the invention aims to solve]

[0023] The present invention aims to address, overcome, or mitigate at least one of the disadvantages of the prior art. [Means for solving the problem]

[0024] In a first aspect, there is provided an electrochemical cell unit comprising a cell layer having an electrochemically active cell region, the cell layer having a first side (e.g., a lower side) and a second side (e.g., an upper side), and a separator plate having a first side (e.g., a lower side) and a second side (e.g., an upper side), the separator plate comprising a metal sheet, the second side of the separator plate extending across the first side of the cell layer and being spaced apart therefrom to form a first fluid volume for a first fluid therebetween, and the separator plate being opposed to the first side of the cell layer. The separator plate has a region extending at least across (e.g., beneath) the electrochemically active cell region, the region being free or substantially free of protrusions directed towards the first side of the cell layer (i.e., free of protrusions protruding into the first fluid volume). The region is substantially free (preferably completely free) of other components for separating the separator plate from the cell layer. The separator plate is adapted to be exposed to a pressure difference between the first side and the second side of the separator plate in order to maintain the spaced-apart arrangement forming the first fluid volume. Preferably, the pressure difference is a fluid pressure difference, more specifically a gas pressure difference.

[0025] The second side of the separator plate extends across the first side of the cell layer in an overlapping arrangement (downward / upward). In the figure, the first side of the cell layer overlaps the second side of the separator plate.

[0026] The region extending across the electrochemically active cell region is completely or substantially flat and mostly free or substantially free or completely free of protrusions or raised features directed towards the first side of the cell layer (of the cell unit of which the separator is a component). Such protrusions may include channels, ridges, or dimples and may typically be formed by pressing, etching, or machining. There is no support structure within the first volume for maintaining that volume.

[0027] The region extending across the electrochemically active cell region can coincide with the planar view area (i.e., the range) of the electrochemically active cell region. That is, the second side of the separator does not contact the first side of the cell layer within the planar view area (i.e., the range) of the electrochemically active cell region, and this region does not include other components for separating the separator plate from the cell layer.

[0028] In the operating mode of the electrochemical cell unit, the pressure difference between the first side and the second side of the separator plate (i.e., the positive pressure difference between the first fluid volume and the second fluid volume) maintains or increases the separation between the second side of the separator plate and the first side of the cell layer. In the non-operating mode, the separation can decrease when the pressures on each of the first side and the second side of the separator plate are the same.

[0029] Preferably, the structure of the cell layer is selected from one of a metal support structure, an anode support structure, an electrolyte support structure, or a cathode support structure. That is, the cell layer is one of a metal-supported cell layer, an anode-supported cell layer, an electrolyte-supported cell layer, or a cathode-supported cell layer.

[0030] More preferably, the cell layer is a metal-supported cell layer, the first side of the cell layer is the first side of the metal support plate, the second side of the cell layer is the second side of the metal support plate opposite to the first side of the metal support plate, and the second side supports the electrochemically active cell region. Further, any reference to the cell layer throughout the description can be exchanged with a cell layer supported by a metal support plate, or a "metal plate-supported cell layer", etc.

[0031] The electrochemical cell unit further comprises an inlet to a first fluid volume and an outlet from the first fluid volume, which are preferably positioned toward opposing edges of the cell unit, with an electrochemically active cell region positioned between them. The inlet to the first fluid volume may be a type of port for the flow of fluid (such as reformed fuel) into the first fluid volume formed by the separation arrangement of the cell layer and the separator plate. The outlet from the first fluid volume may be a type of port for the flow of fluid (such as reformed fuel) into the first fluid volume formed by the separation arrangement of the cell layer and the separator plate.

[0032] The electrochemical cell unit preferably comprises a plurality of first protrusions extending outward from a first side of the separator plate in a direction away from the cell layer. The protrusions are raised features or components of the separator plate, attached to or integrally formed with the separator plate. If the protrusions are integrally formed with the separator plate, they may be formed by press working of the separator plate. Preferably, the plurality of first protrusions are located in a region of the cell unit that overlaps with at least the electrochemically active cell region.

[0033] The projections may have circular, square, cruciate, pentagonal, or hexagonal cross-sections. The projections may also have elliptical or irregular polygonal cross-sections, but ideally, they should have a width-to-length aspect ratio of less than 10, preferably less than 5, and more preferably less than 2. Alternatively, or additionally, the length of any projection may be less than half of the characteristic lateral dimensions (e.g., length, width, or diameter) of the electrochemically active cell region.

[0034] Furthermore, one or both of the separator plate and the cell layer of the electrochemical cell unit may be provided with a second plurality of projections (raised features or components) that extend outward toward and contact the other of the separator plate and the cell layer at a plurality of contact points on the cell layer surrounding the inlet for the flow of fluid into the first fluid volume and the outlet for the flow of fluid from the first fluid volume.

[0035] The electrochemical cell unit may further comprise a flanged periphery on at least one of the separator plate and the cell layer. The flanged periphery may be attached to the separator plate and the cell layer, or may be integrally formed with the separator plate and / or the cell layer by press forming. The flanged periphery may be used to join the separator plate and the cell layer. For example, the separator plate and the cell layer may be joined directly at the flanged periphery to form a first fluid volume between them. The flanged periphery of the separator plate and the cell layer may optionally be welded or directly joined by some other means.

[0036] The electrochemical cell unit may, alternatively, include a spacer plate positioned and sandwiched between a separator plate and a metal support plate. The spacer plate can separate the metal support plate from the separator plate. For example, the spacer plate may be positioned and sandwiched between the separator plate and the metal support plate so as to form a first fluid volume between them. These three plates can be sealed and fixed to each other, for example, by welding their periphery.

[0037] The separator plate of an electrochemical cell unit may be configured or adapted to be exposed to a pressure on its first side that is lower than the pressure on its second side. That is, the separator plate may be configured to withstand a dual-pressure environment without critical damage or deformation. A dual-pressure environment may be provided to the separator plate by supplying fluids of different pressures to different sides of the separator plate, thereby creating a pressure difference between them. The separator plate may be configured or adapted to maintain a first fluid volume formed between the separator plate and the cell layer in the presence of a pressure difference between its first side and its second side when it is in its original position in a stack of cell units (including multiple units).

[0038] For example, the pressure of the first fluid on the second side of the separator plate may be higher than the pressure of the second fluid on the first side of the separator plate, where the first fluid is, for example, fuel and the second fluid is, for example, an oxidizer.

[0039] The pressure difference between the first and second sides of the separator plate can be controlled by any number of means well known to those skilled in the art. For example, the pressure difference can be established by the use of pumps to pump fluids at different speeds and pressures. Alternatively, or additionally, features such as valves and chokes may be provided in the conduits or flow paths of the first and second fluids, respectively, to control the pressure difference between the first and second fluids. The pressure difference between the first and second fluids may be in the range of 50 mbar to 2 bar, preferably 100 mbar to 1.5 bar, and more preferably 200 mbar to 800 mbar. Those skilled in the art will understand that the pressure difference used may be adjusted to maintain the gap between the separator plate and the cell layer, and that the pressure difference may depend on the flexibility of the cell layer and the separator plate (its metal sheet).

[0040] By providing features in the first and second fluid flow paths, the initial pressures at the inlets of the first and second fluid volumes can be controlled to control the pressure difference between the first and second fluid volumes (for fuel cell operation, for electrolytic cell operation, only the first fluid is supplied and its initial pressure can be controlled). Additionally, or alternatively, the pressures at the respective outlets of the first and second fluid volumes can be controlled to create a pressure difference between the first and second fluid volumes.

[0041] The separator plate may be configured or adapted to flex when subjected to a pressure difference between its first and second sides. That is, the pressure difference the separator plate experiences may be such that it flexes away from the cell layer or toward the cell layer. Preferably, the separator plate may be configured to flex away from the cell layer as a positive function of the pressure difference when exposed to it. By flexing away from the cell layer, the separation between the separator and the cell layer is maintained (or increased), the fluid volume between them is maintained (its height is maintained or increased), and contact with adjacent cell units may be improved.

[0042] A cell stack is provided comprising a plurality of cell units as described above, wherein the second side (e.g., upper side) of the separator plate of a first cell unit faces the first side (e.g., lower side) of the cell layer of the first cell unit, spaced apart to form a first fluid volume for a first fluid, and the first side (e.g., lower side) of the separator plate of the first cell unit faces the electrochemically active cell region of a second adjacent cell unit in the stack of cell units, defining a second fluid volume between them.

[0043] A cell stack is provided comprising a plurality of cell units, each cell unit comprising a cell layer having an electrochemically active cell region, having a first side and a second side, the second side of which carries the electrochemically active cell region; and a separator plate having a first side and a second side, comprising a metal sheet, the second side of the separator plate (e.g., upper side) overlapping the first side of the cell layer (e.g., lower side) and positioned apart to form a first fluid volume for a first fluid between them, facing the first side of the cell layer. The first side of the separator plate extends across the electrochemically active cell regions of adjacent cell units in the cell stack and faces the electrochemically active cell regions, positioned apart to form a second fluid volume for a second fluid between them. The separator plate has a region that extends at least over an electrochemically active cell region, and this region does not include any protrusions directed towards the cell layer or other components for separating the separator plate from the metal support plate. The separator plate is adapted to be exposed to a pressure difference between a first side and a second side of the separator plate in order to maintain a separation arrangement that forms a first fluid volume.

[0044] In operation as a fuel cell, the cell stack is configured such that a first fluid volume is for fuel and a second fluid volume is for oxidizer. For example, the fuel may be a hydrogen-rich reformed oil flow (e.g., converted from a hydrocarbon fuel flow such as natural gas). The oxidizer may be air or oxygen. In operation as an electrolytic cell, the first fluid volume is for steam.

[0045] The cell stack may further be configured such that the first side of the separator plate contacts the outermost layer of the electrochemically active cell region of a neighboring cell unit, resulting in electrical contact between them, and having a contact resistance that decreases as the pressure difference between the first and second sides of the separator plate increases. For example, as described above, the pressure difference experienced by the separator plate may be due to the pressure difference between the pressure of the first fluid in the first fluid volume and the pressure of the oxidizing agent, such as air or oxygen, on the opposite side of the separator plate, i.e., the second fluid volume.

[0046] In other words, by introducing a pressure difference on both sides of the separator plate within a single cell unit, the separator plate is deflected toward the electrochemically active region of the adjacent cell unit, thereby bringing the downward projections (or dimples) of the separator plate into contact with the electrochemically active region of the adjacent cell unit. This deflection can be achieved across the entire active region without the need for extensive projections on the other side of the separator plate that would impart force in that direction. By bringing the downward projections into contact with the electrochemically active region of the adjacent cell unit, contact resistance is reduced, i.e., conductivity through the stack is improved.

[0047] Thus, the separator plate is adapted to be exposed to a pressure difference between the first and second sides of the separator plate in order to maintain a separated arrangement that forms a first fluid volume.

[0048] (To the extent that protrusions may be present on the second side of the separator plate (over a portion of its area, e.g., 10% or 20%), such protrusions may be separated under pressure from the first side of the metal support plate, lifting away from the holes / pores within it, allowing fuel to enter the porous region of the support plate. Also note that even if the number of protrusions on the second side of the separator plate is small, it will still be fewer than the number on the first side. Fluid pressure imparts uniform pressure across the plate, eliminating the need for protrusions on the second side throughout the active region.

[0049] A method for manufacturing a cell unit is provided. The method includes the steps of: preparing a planar metal sheet for a separator plate having a first side and a second side, the planar metal sheet having protrusions; preparing a cell layer having an electrochemically active cell region, the cell layer having a first side and a second side; and superimposing the separator plate and the cell layer such that the separator plate is separated to form a first fluid volume, the first side of the cell layer faces the first side, and the separator plate has a region extending at least over the electrochemically active cell region. This region does not include protrusions directed toward the cell layer or other components for separating the separator plate from the cell layer.

[0050] The method may include the step of preparing a metal support plate having a cell layer comprising electrochemically active cell regions, wherein the first side of the cell layer is the first side of the metal support plate, and the second side of the cell layer is the second side of the metal support plate opposite to the first side, and the second side supports the electrochemically active cell regions. The method may also include the step of press-forming a planar metal sheet to provide planar projections extending from the surface of the planar metal sheet.

[0051] At least one of the separator plate and the cell layer (or the metal support plate supporting the cell layer) may be processed to form a flanged periphery. The flanged periphery of the separator plate and / or cell layer (or the metal support plate supporting the cell layer) may be formed integrally with the separator plate and / or cell layer (or the metal support plate supporting the cell layer) by press working. During manufacturing, the separator plate and the cell layer may be joined directly at the flanged periphery and optionally by welding to form a first fluid volume between them.

[0052] Instead of (or in addition to) the flanged periphery, a spacer plate may be provided between the separator plate and the metal support plate. The spacer plate may extend around the periphery of the separator plate and / or the cell layer. The spacer plate may serve to separate these plates and define a first fluid volume.

[0053] A method for manufacturing a cell unit stack is provided. The method includes the steps of preparing a plurality of cell units, each of which is manufactured as described above, and stacking one cell unit on top of / below another cell unit of the plurality of cell units such that a projection on the separator plate of one cell unit of the plurality of cell units extends and contacts an electrochemically active cell region of another cell unit of the plurality of cell units. The stacking / below step further includes the step of providing a gasket between one of the plurality of cell units and another of the plurality of cell units.

[0054] A method for operating a cell stack of a cell unit is provided. The cell stack is as described above, and the method includes the steps of supplying a first fluid to a first fluid volume, supplying a second fluid to a second fluid volume, and adjusting the pressure difference between the first fluid volume and the second fluid volume to maintain a separation arrangement that forms the first fluid volume.

[0055] One aspect of the present invention provides a method for operating a cell stack of cell units. In this method, each cell unit in the cell stack comprises a cell layer having a first side and a second side, comprising an electrochemically active cell region; and a separator plate having a first side and a second side, electrically connected to the cell layer, the second side of the separator plate extending across the first side of the cell layer and facing the first side of the cell layer in a spaced position to form a first fluid volume between them; and the first side of the separator plate having a projection directed toward the second side of the cell layer of an adjacent cell unit in a direction away from the first side of the cell layer to form a second fluid volume. The method includes the steps of supplying a first fluid to a first fluid volume; supplying a second fluid to a second fluid volume; and adjusting the pressure difference between the first fluid volume and the second fluid volume to maintain the spaced position to form a first fluid volume. In this way, the electrical connection between the protrusion and the second side of the cell layer of the adjacent cell unit can be controlled by the pressure difference.

[0056] In another aspect of the present invention, an electrochemical cell unit is provided, comprising a cell layer having an electrochemically active cell region and having a first side and a second side, and a separator plate electrically connected to the cell layer and having a first side and a second side, wherein the second side of the separator plate is facing the first side of the cell layer, with the second side extending across the first side of the cell layer and spaced apart to form a first fluid volume between them, and the first side of the separator plate has a projection directed toward the second side of the cell layer of an adjacent cell unit in a direction away from the first side of the cell layer, wherein the separator plate is adapted to be exposed to a pressure difference between the first and second sides of the separator plate in order to maintain the spaced arrangement that forms the first fluid volume and to bias the projection toward the second side of the cell layer of an adjacent cell unit. In this way, the electrical connection between the projection and the second side of the cell layer of an adjacent cell unit can be controlled by the pressure difference.

[0057] In another aspect of the present invention, a method for manufacturing a cell stack comprising a plurality of electrochemical cell units, each cell unit comprising: a cell layer having an electrochemically active cell region and having a first side and a second side; a separator plate electrically connected to the cell layer and having a first side and a second side, wherein the second side of the separator plate extends across the first side of the cell layer and is positioned apart to form a first fluid volume between them, facing the first side of the cell layer, and the first side of the separator plate has a projection directed away from the first side of the cell layer; and a step of preparing a plurality of cell units. A manufacturing method is provided, comprising the step of stacking a plurality of cell units such that the first side of the separator plate of the first cell unit faces the second side of the second adjacent cell unit in the stack of cell units, defining a second fluid volume between them, wherein the projection of the separator plate of the first cell unit is directed toward the second side of the cell layer of the adjacent cell unit, and the separator plate of the first cell unit is adapted to be exposed to the pressure difference between the first and second sides of the separator plate in order to maintain a separation arrangement that forms the first fluid volume and to bias the projection toward the second side of the cell layer of the adjacent cell unit.

[0058] If the cell unit is an electrolytic cell unit, it should be noted that the second fluid is produced by the reaction. That is, the supplying step includes supplying the initial reactants (from an external source to the cell unit) and supplying (or generating by the cell unit) the products of the electrochemical reaction in the cell unit. For example, in the operation of an electrolytic cell, the first fluid volume of the cell unit is supplied with fuel (in the form of vapor from an external source to the cell unit) and the products of the electrolytic reaction, the products being hydrogen if the electrolyte is oxygen ion conductive, and oxygen if the electrolyte is hydrogen ion conductive. Thus, the second fluid volume of the cell unit may be supplied only with the products of the electrolytic reaction, the products being oxygen if the electrolyte is oxygen ion conductive, and hydrogen if the electrolyte is hydrogen ion conductive (in the example of vapor as fuel). A sweep gas (e.g., oxygen or air) may optionally be supplied to the second fluid volume from an external source to the cell unit. Such a sweep gas can help to remove the products of the electrolytic reaction from the second fluid volume.

[0059] A method for operating a cell stack may include a fuel supply step of supplying fuel (for example, reformed hydrocarbon fuel or hydrogen in fuel cell operation, or vapor in electrolytic cell operation, and the products of the above reaction) to the fuel volume of each cell unit of the cell stack, wherein the fuel volume of each cell unit is formed between the respective separator plate and the respective cell layer of each cell unit; an air or oxygen supply step of supplying air or oxygen (from an external source to the cell unit in fuel cell operation, and as a product of the reaction, or as a sweep gas in electrolytic cell operation) to the oxidizer fluid volume of each cell unit of the cell stack, wherein the oxidizer fluid volume of each cell unit is formed between the cell units of the cell stack; and a step of adjusting the pressure difference between the fuel volume and the oxidizer volume by adjusting the pressure of the reformed hydrocarbon fuel and the pressure of the air or oxygen, respectively.

[0060] The pressure difference between the first fluid volume and the second fluid volume can be adjusted to be in the range of 50 mbar to 2 bar, preferably 100 mbar to 1.5 bar, and more preferably 200 mbar to 800 mbar.

[0061] The pressure difference is preferably adjusted to reduce the electrical contact resistance between the separator plate and the electrochemically active cell region of a second adjacent cell unit in the stack of cell units. By increasing the pressure difference, the electrical contact resistance can be reduced, resulting in improved stack efficiency.

[0062] The pressure difference can be adjusted, for example, by (i) the use of pumps to pump the first and second fluids at different rates, (ii) chokes such as valves or convergence-divergence nozzles (such as Laval nozzles) in conduits or flow paths that supply fluid to the first and second fluid inlets of the cell unit and / or the entire cell stack, or (iii) orifice plates in conduits or flow paths to help adjust the pressure difference between the first and second fluids. Other methods and apparatus that can be used to establish the pressure difference between the first and second fluids will be readily apparent to those skilled in the art.

[0063] In a further embodiment, an electrolytic cell unit is provided comprising a cell layer having a first side and a second side, each having an electrochemically active cell region; a first fluid flow region for supplying fuel to the first side of the cell layer; and a second fluid flow region for discharging fluid from the second side of the cell layer. The cross-sectional area of ​​the second fluid flow region may be smaller than that of the first fluid flow region. The cell layer may be self-supporting. Since the first (second) side of the electrochemically active cell region borders the first (second) fluid flow region, reference to the first (second) side of the cell layer is interchangeable with reference to the first (second) side of the electrochemically active cell region unless the context indicates otherwise. In some cases, the electrochemically active cell region is supported by a support plate (e.g., a metal), in which case one side of the electrochemically active cell region (typically the first side) is supported by one side of the support plate (typically the second side), and the other side of the support plate (typically the first side) may be considered the first side of the cell layer.

[0064] Reducing the relative volume of the discharge side (second fluid flow region) to the fuel side (first fluid flow region) has been shown to have many advantages, including the following: • Simpler separator design and manufacturing • Higher volumetric power density (more cells per unit volume and smaller stacks for the same output) - Avoid the possibility of damaging the separator plate when pressing it, including the possibility of damaging the protective layer on the separator plate. • The flatness of the repeating units is more consistent. • Faster turnaround time in development • Improvement of electrical contact • Avoidance of localized fuel depletion through better current distribution.

[0065] Cell units with substantially symmetrical separator plate designs are known, and electrolytic cell units can readily operate in the reverse direction of fuel cell units, and vice versa, if desired. Fuel cell units require cooling, which is often achieved by supplying an additional oxidant (in addition to the one used in the fuel cell reaction) as a coolant.

[0066] The claimed invention identifies that the coolant volume used in a cell unit (provided for operation as a fuel cell) is not required for reverse operation as an electrolytic cell unit. A higher volumetric power density can be achieved for an electrolytic cell unit by providing an electrolytic cell unit in which the cross-sectional area of ​​the second fluid flow region is smaller than that of the first fluid flow region. The relatively small size required for the second fluid flow region allows for different means to achieve the second fluid flow region, thereby reducing the complexity of design and manufacture compared to the typically used press-formed or molded dimples. The relatively reduced flow rate required in the second fluid flow region and / or the means used to achieve the second fluid flow region can increase the contact area between the first side of the separator plate and the second side of the cell layer (compared to using molded or press-formed dimples and / or having a higher flow rate in the second fluid flow region), thereby reducing the contact resistance between the components and improving the power density of the cell unit and its stack.

[0067] The first fluid flow region may further be a region for discharging the first product of the electrolytic reaction, which is generated on the first side of the electrochemically active cell region. The fluid discharged from the second side of the electrochemically active cell region may be the second product of the electrolytic reaction, which is generated on the second side of the electrochemically active cell region. The second fluid flow region may further be a region for circulating a sweep gas to assist in the discharge of the fluid from the second side of the electrochemically active cell region (i.e., the discharge of the second product of the electrolytic reaction). The flow rate of the sweep gas (and the cross-sectional area required therefor) may be one-third, preferably one-fifth, and more preferably one-tenth of the fuel flow rate.

[0068] The electrolytic cell unit preferably comprises a separator plate having a first side and a second side, the second side of the separator plate overlapping the first side of the cell layer and facing the first side of the cell layer, spaced apart to form a first fluid flow region. In this case, the second fluid flow region may be defined by the region between the second side of the cell layer and the first side of the separator plate of the adjacent electrolytic cell unit. Such a configuration is relatively easy to manufacture and can reduce the resistance of the stack of cell units because each cell unit is at the same potential.

[0069] Alternatively, the electrolytic cell unit comprises a separator plate having a first side and a second side, wherein the first side of the separator plate overlaps the second side of the cell layer and faces the second side of the cell layer, spaced apart to form a second fluid flow region between them. In this case, the first fluid flow region may be defined by the region between the first side of the cell layer and the second side of the separator plate of the adjacent electrolytic cell unit. With such a configuration, the electrochemically active cell region can be surrounded within the cell unit and protected by the cell unit.

[0070] The second fluid flow region can be defined by the topology of the first side layer of the separator plate. In other words, it is not necessary to deform the separator plate to form the second fluid flow region. To put it another way, the feature that defines the second fluid flow region is not a pressed or molded feature. The feature defines the second fluid flow region and transmits the stack compressive force through the stack, resulting in good electrical contact between the second side of the cell layer and the second side of the separator plate. This simplifies the manufacturing of the separator plate, reduces stress within the separator plate caused by the manufacturing process, and improves the reliability of the cell unit. In addition, the contact area between the first side of the separator plate and the cell layer is increased, reducing the contact resistance between them, and consequently improving the efficiency of the cell unit.

[0071] On the first side of the separator plate, a feature area may be provided which is deposited or printed to form a second fluid flow region. Depositing or printing the feature area to form the second fluid flow region is cost-effective, rapid, and produces a feature area with a consistent height.

[0072] The first side of the separator plate may be provided with a feature formed in the layer above it to form a second fluid flow region. In some cases, it may be preferable to remove material from the layer on the first side of the separator plate to form the second fluid flow region. The layer may be deposited or printed as a rapidly repeatable homogeneous layer. The feature may then be formed by selectively removing a portion of the layer, for example, by etching or machining.

[0073] The feature portion provided on the first side of the separator plate is Multiple ribs extending from the second side of the separator toward the first side of the cell layer, Multiple discrete protrusions extending from the second side of the separator toward the first side of the cell layer, or Porous layer It may have at least one of the following.

[0074] In either case, the vertices(s) of the feature portion contact the first side of the cell layer in the cell unit and / or stack of cell units. This enables good electrical contact and uniform transmission of compressive force through the stack. That is, the vertices of the discrete protrusions or ribs form a plane that intersects with the first side of the cell layer. The discrete protrusions may comprise a material supported or coated on the first side of the separator plate, as opposed to press-formed or molded dimples. The porous layer is preferably uniform in thickness and porosity to facilitate good electrical contact and uniform transmission of compressive force through the stack. This simplifies the manufacture of the separator plate, reduces stress within the separator plate caused by the manufacturing process, and improves the reliability of the cell unit. It also increases the contact area between the first side of the separator plate and the cell layer, reducing contact resistance between them, and consequently improving the efficiency of the cell unit.

[0075] The separator plate may have a region that overlaps at least a portion of the planar electrochemically active cell region, and this region does not have press-formed or molded protrusions oriented away from the first side of the cell layer. That is, the separator plate does not need to be bent in the direction described above in the region. This can improve the integrity of the separator plate and the lifespan of the electrolytic cell unit. Preferably, the separator plate is formed from a sheet (e.g., a metal sheet) which has a region that overlaps at least a portion (optionally, all) of the planar electrochemically active cell region, and this region does not have press-formed or molded protrusions (also called dimpled protrusions or dimples) oriented away from the first side of the cell layer (towards the second side of the cell layer). This reduces the stress on the separator plate caused by the manufacturing of the separator plate, improving the reliability of the cell unit. In addition, the contact area between the first side of the separator plate and the cell layer is increased, reducing the contact resistance between them, and as a result, the efficiency of the cell unit is improved.

[0076] The separator plate may have a region overlapping at least a portion of the electrochemically active cell region, the region being provided with a plurality of press-formed or molded protrusions directed toward the first side of the cell layer to form a first fluid flow region, these press-formed or molded protrusions extending outward from the second side of the separator plate, thereby forming a convex protrusion on the second side of the separator plate and a concave recess on the first side of the separator plate. These press-formed or molded protrusions transmit compressive forces through the stack and promote good electrical contact between the second side of the cell layer and the first side of the separator plate (i.e., between adjacent cell units or within a cell unit).

[0077] Alternatively, the separator plate may be provided with a number of press-formed or molded ribs extending from a second side of the separator plate toward the first side of the cell layer to form a first fluid flow region, the corresponding concave side of each rib forming a channel toward the first side of the separator plate to form a second fluid flow region. In this case, the manufacture of the separator plate is simplified and costs are reduced by a single feature created in a press-formed / molding step that forms both the first and second fluid flow regions.

[0078] Preferably, the press-formed or molded ribs are longer than the length of the electrochemically active cell region, and the concave side of each rib is configured to discharge the first fluid (i.e., the products of the electrolytic reaction) from the second side of the cell layer with low pressure loss. That is, one end of the rib may protrude (in the longitudinal direction of the rib) beyond at least one end of the electrochemically active cell region. Preferably, each end of the rib protrudes (in the longitudinal direction of the rib) beyond the opposing end of the electrochemically active cell region. This may allow both ends of the rib to discharge the second fluid (i.e., the products of the electrolytic reaction) from the second fluid flow region, or may allow the use of a sweep gas in the second fluid flow region supplied to one end of each rib and discharged (along with the products of the electrolytic reaction) at the opposite end of each rib. The ribs may be fitted to contact the first side of the cell layer at the apex of each convex side of the rib (on the second side of the separator plate).

[0079] The separator plate may have a region overlapping at least a portion of an electrochemically active cell region, which is provided with a plurality of pressed or molded protrusions facing a first side of the cell layer, and the concave side of each rib is fluidly connected to the protrusion (the concave side thereof). In such a case, the ribs and protrusions (specifically, their concave sides) form a second fluid flow region. The ribs may connect the protrusions to their nearest adjacent protrusions (i.e., a given protrusion provided with a plurality of ribs, and the ribs connecting it to each of its nearest adjacent protrusions). The ribs may connect the protrusions from one end of the cell unit to the protrusions at the opposing end of the cell unit (optionally, with ribs from the protrusions at one or both ends extending beyond the edge of the electrochemically active cell region), and these are called interconnecting ribs. The interconnecting ribs (a network of protrusions and ribs between them) have a range longer than the length of the electrochemically active cell region, and the interconnecting ribs are configured to discharge a second fluid (i.e., products of electrolytic reactions) from the second side of the cell layer with low pressure loss. In other words, one end of the interconnecting rib may project (in the longitudinal direction of the rib) beyond at least one end of the electrochemically active cell region. Preferably, each end of the interconnecting rib may project (in the longitudinal direction of the rib) beyond the opposing end of the electrochemically active cell region. This may allow both ends of each interconnecting rib to discharge the second fluid (i.e., the products of the electrolytic reaction) from the second fluid flow region, or may allow the use of a sweep gas in the second fluid flow region, supplied to one end of each interconnecting rib and discharged (along with the products of the electrolytic reaction) at the opposite end of each interconnecting rib. The interconnecting rib may further interconnect with one or more fluid ports for supplying and / or discharging the second fluid flow region.

[0080] The projections may be adapted to contact a first side of the cell layer, while the ribs (the convex side) may be adapted not to contact the first side of the cell layer. That is, the projections may have a greater height than the ribs. In other words, the projections define a first fluid flow region, while the ribs do not obstruct the flow within the first fluid flow region. Nevertheless, the ribs define a second fluid flow region, enabling fluid communication within it.

[0081] The separator plate may, as an addition or alternative, have a region extending at least over the electrochemically active cell region, which does not contain any projections (i.e., press-formed or molded protrusions, also called dimples) directed toward the cell layer or other components for separating the separator plate from the metal support plate. That is, the separator plate is perfectly flat (over its entire region or at least within the planar area extending over the electrochemically active cell region). Preferably, the separator plate comprises a metal sheet, the metal sheet being flat (planar) within the region. In such a case, the separator plate may be adapted to be exposed to a pressure difference between a first side and a second side of the separator plate in order to maintain a separation arrangement that forms a first fluid flow region. The region extending over the electrochemically active cell region is perfectly or nearly perfectly flat and, for the most part, nearly or completely, does not contain any projections or raised features directed toward the first side of the cell layer (of the cell unit in which the separator is a component). In this case, there are no supporting structures within the first volume to maintain that volume (including the fluid flow region).

[0082] In the operating mode of the electrochemical cell unit, the pressure difference between the first and second sides of the separator plate (i.e., the positive pressure difference between the first fluid flow region / first fluid volume and the second fluid flow region / second fluid volume) maintains or increases the separation between the second side of the separator plate and the first side of the cell layer. In the non-operating mode, when the pressures on the first and second sides of the separator plate are equal, the separation may decrease.

[0083] The pressure difference between the first and second sides of the separator plate can be controlled by any number of means well known to those skilled in the art. For example, the pressure difference can be established by the use of pumps to pump fuel at different speeds and pressures. Alternatively, or additionally, features such as valves and chokes may be provided in the fuel conduit or flow path to control the pressure difference between the first and second sides of the separator plate. The pressure difference between the first and second sides of the separator plate may be in the range of 50 mbar to 2 bar, preferably 100 mbar to 1.5 bar, more preferably 200 mbar to 800 mbar. Those skilled in the art will understand that the pressure difference used may be adjusted to maintain the gap between the separator plate and the cell layer (e.g., to a desired value, and / or to maintain the contact resistance at a desired value, so that increasing the pressure difference decreases the contact resistance), and that the pressure difference may depend on the flexibility of the cell layer and the separator plate (its metal sheet).

[0084] The first fluid flow region can be defined by the topology of the second side layer of the separator plate. That is, the separator plate and cell layer are flat, and it is not necessary to deform the separator plate to form the first fluid flow region. In other words, the feature that defines the first fluid flow region is not a pressed or molded feature. The feature defines the first fluid flow region and transmits stack compressive force through the stack, resulting in good electrical contact between the second side of the cell layer and the second side of the separator plate.

[0085] The second side of the separator plate may have a feature deposited thereon to form a first fluid flow region. The deposition or printing of the feature to form the second fluid flow region is cost-effective, rapid, and produces a feature with a consistent height. Such deposition can ensure cleanliness and reduce processing steps. The feature can be deposited by screen printing or inkjet printing.

[0086] Alternatively, or as an addition, the second side of the separator plate may have a feature formed therein to form a second fluid flow region. In such a case, the feature may be created by partial removal of a layer initially deposited or printed on the second side of the separator plate. The layer may be deposited or printed as a rapidly repeatable homogeneous layer. The feature may then be formed by selectively removing a portion of the layer, for example, by etching or machining. In some cases, such a homogeneous layer may already be present on the second side of the separator plate (e.g., a protective layer), and a portion of such a layer may be removed, which can reduce the number of processing steps and the number of different layers and materials in the cell unit.

[0087] The distinctive feature provided on the second side of the separator plate is, Multiple ribs extending from the second side of the separator toward the first side of the cell layer, Multiple discrete protrusions extending from the second side of the separator toward the first side of the cell layer, or Porous layer It may have at least one of the following.

[0088] Multiple discrete protrusions (similar to the discrete projections described above) may be provided around ports passing through the cell layer (metal support plate), separator plate, and, if used, spacer plate, to enable fluid communication between the ports and the fluid volume surrounded within the cell unit (for example, between the first side of the cell layer and the second side of the separator plate, or between the second side of the cell layer and the first side of the separator plate).

[0089] The second fluid flow region can be defined by the topology of the second side of the cell layer, preferably the electrochemically active cell region. In other words, it is not necessary to deform the separator plate to form the second fluid flow region. To put it another way, the feature defining the second fluid flow region is not a pressed or molded feature. The feature defines the second fluid flow region and transmits stack compressive force through the stack, resulting in good electrical contact between the second side of the cell layer and the second side of the separator plate.

[0090] The topology of the layer on the second side of the cell layer, preferably the second side of the electrochemically active cell region, may include feature regions deposited thereon to form a second fluid flow region. Such feature region deposition can ensure cleanliness and reduce processing steps. The feature regions may be deposited by screen printing or inkjet printing.

[0091] Alternatively, the topology of the layer on the second side of the cell layer, preferably the layer on the second side of the electrochemically active cell region, may include a feature formed thereon to form a second fluid flow region. That is, the feature can be formed on the outermost layer of the electrochemically active cell region (e.g., the cathode or anode) by etching or machining, for example. This reduces the number of processing steps and the number of different layers and materials within the cell unit.

[0092] The feature portion formed on the second side of the cell layer, preferably on the second side of the electrochemically active cell region, Multiple ribs on the second side of the cell layer, preferably on the second side of the electrochemically active cell region, or Multiple discrete protrusions on the second side of the cell layer, preferably on the second side of the electrochemically active cell region It may have at least one of the following.

[0093] The discrete protrusions are similar to those that can be provided on the separator plate. The ribs are provided in a similar manner to the discrete protrusions. Neither the discrete protrusions nor the ribs constitute a channel and therefore do not restrict the flow in the second fluid flow region.

[0094] Alternatively, the feature portion forming the second fluid flow region comprises a porous layer. The porous layer may be coated or deposited on the second side of the cell layer, preferably on the second side of the electrochemically active cell region, or it may be self-supporting. By using a layer that does not require patterning, the number of processing steps can be reduced.

[0095] Preferably, the ratio of the cross-sectional area of ​​the second flow region to the cross-sectional area of ​​the first flow region is 1:3 or less, and arbitrarily 1:10 or less. The above ratio may be greater than 1:25, and arbitrarily greater than 1:20. This increases the power density of the cell unit by preparing a cell unit with a lower height.

[0096] Preferably, the height of the second fluid flow region is lower than the height of the first fluid flow region. This increases the power density of the cell unit by providing a cell unit with a lower height. Such a height difference may result in a smaller cross-sectional area of ​​the second fluid flow region than the cross-sectional area of ​​the first fluid flow region (and the planar area (length and width) of the cell unit can typically be assumed to be similar or the same for the first and second fluid flow regions).

[0097] The height of the second fluid flow region may be at least one-third, preferably at least one-tenth, of the height of the first fluid flow region. This height may be at least one-twenty-fifth, and optionally at least one-twentyth, of the height of the first fluid flow region.

[0098] The electrolytic cell unit can be adapted so that the ratio of the fluid flow rate in the second fluid flow region to the fluid flow rate in the first fluid flow region is 1:3 or greater, and optionally 1:10 or greater. The above flow rate ratio may be up to 1:25, and optionally up to 1:20.

[0099] The electrochemically active cell region may comprise an oxygen ion-conducting electrolyte, and the second fluid flow region is for discharging oxygen from the second side of the cell layer, preferably from the second side of the electrochemically active cell region. For example, the electrolytic cell unit may be a solid oxide electrolytic cell (SOEC). The fuel may be water (preferably in the form of vapor), in which case hydrogen is produced on the first side of the electrochemically active cell region and discharged from the first side of the electrochemically active cell region (along with unused water) by the first fluid flow region. In this case, oxygen is produced on the second side of the electrochemically active cell region and discharged from the second side of the electrochemically active cell region (along with similarly supplied sweep gas) by the second fluid flow region. A fuel other than water (e.g., carbon dioxide) can be used, in which case carbon monoxide is produced on the first side of the electrochemically active cell region and discharged from the first side of the electrochemically active cell region (along with unused carbon dioxide) by the first fluid flow region. In this case, oxygen is generated on the second side of the electrochemically active cell region and discharged from the second side of the electrochemically active cell region (along with the similarly supplied sweep gas) by the second fluid flow region.

[0100] Alternatively, the electrochemically active cell region may comprise a proton-conducting electrolyte, and the second fluid flow region is for discharging hydrogen from the second side of the cell layer, preferably from the second side of the electrochemically active cell region. For example, the electrolytic cell unit may be a proton-exchange membrane electrolytic cell (PEMEC). The fuel may be water, in which case oxygen is produced on the first side of the electrochemically active cell region and discharged from the first side of the electrochemically active cell region (along with unused water) by the first fluid flow region. In this case, hydrogen is produced on the second side of the electrochemically active cell region and discharged from the second side of the electrochemically active cell region (along with similarly supplied sweep gas) by the second fluid flow region. Other fuels may be used.

[0101] Preferably, the first side of the cell layer is the cathode of the electrochemically active cell region, and / or the second side of the cell layer is the anode of the electrochemically active cell region.

[0102] The structure of the cell layer can be selected from one of the following: a metal-supported structure, an anode-supported structure, an electrolyte-supported structure, or a cathode-supported structure.

[0103] Preferably, the cell layer is a metal-supported cell layer comprising an electrochemically active cell region supported by a metal support plate. The metal support plate may have a first side and a second side, where the first side of the electrochemically active cell region (preferably a fuel electrode, e.g., a cathode for electrolytic cell operation) is supported (or carried) by the second side of the metal support plate, and the second side of the separator plate is opposite the first side of the metal support plate, overlapping the first side of the metal support plate and spaced apart to form a first fluid flow region between them. A porous region may be provided in the metal support plate for fluid communication between the first side of the metal support plate and the first side of the electrochemically active cell region.

[0104] One or both of the metal support plate and the separator plate may be provided with flanges (e.g., on the periphery of one or each plate), and the electrolytic cell unit may be sealed around the flanges by welding the two plates together so as to surround either a first fluid flow region or a second fluid flow region. When surrounded in this manner, the first fluid flow region forms a first fluid volume, and the second fluid flow region forms a second fluid volume. The metal support plate and the separator plate abut (i.e., touch) each other around the flanges. The flange of the first plate of the metal support plate and separator plate extends toward the other plate of the metal support plate and separator plate (and vice versa if both components are provided with flanges).

[0105] Alternatively (as an alternative to flanges), a spacer plate may be provided between the metal support plate and the separator plate, and the electrolytic cell unit is sealed at the periphery of the plate so as to surround either a first fluid flow region or a second fluid flow region. Optionally, the electrolytic cell unit is sealed at the periphery of the plates by welding through the spacer plate, the metal support plate, and the separator plate so as to surround either a first fluid flow region or a second fluid flow region. The spacer may comprise a frame or flat peripheral component (positioned beyond the electrochemically active cell region) sandwiched between the metal support plate and the separator plate, forming a volume for the fluid flow region or volume (e.g., first fluid flow region / volume) surrounded by the plates, sealing and surrounding it.

[0106] According to one embodiment, an electrolytic cell unit is provided characterized in that the discharge volume is smaller than the fuel volume. For example, the electrochemically active cell region of the electrolytic cell unit may have an electrolyte that conducts oxygen ions, in which case the fuel may be water supplied to a first side of the electrochemically active cell region, and the discharge volume may be the volume for oxygen produced on a second side of the electrochemically active cell region. The fuel volume may further discharge hydrogen produced on the first side of the electrochemically active cell region.

[0107] In a further embodiment, an asymmetric separator plate for an electrolytic cell unit is provided.

[0108] In a further embodiment, an electrolytic cell unit is provided. This electrolytic cell unit comprises a metal support plate having a first side and a second side, the second side of which carries an electrochemically active cell region, and a separator plate having a first side and a second side, wherein the second side of the separator plate overlaps the first side of the metal support plate and is positioned apart from the first side of the metal support plate to form a first fluid volume for a first fluid between them. The separator plate has a region that overlaps at least a portion (optionally, the entire) of the planar electrochemically active cell region, the region having no projections directed away from the metal support plate, and the electrolytic cell unit comprises a fluid flow region for a second fluid, the fluid flow region being, The outermost layer of the electrochemically active cell region (the fluid flow region is the region for the delivery and / or discharge of a second fluid to / from the outermost layer of the electrochemically active cell region), and The first side of the separator plate (the fluid flow region is the region for the delivery and / or discharge of the second fluid to / from the outermost layer of the electrochemically active cell region of the adjacent electrolytic cell unit) To form part of one or both of them.

[0109] The delivery of the second fluid may include the delivery of a sweep gas to the fluid flow region.

[0110] In a further embodiment, an electrolytic cell unit is provided, comprising a metal support plate having a first side and a second side, the second side of which carries an electrochemically active cell region; and a separator plate having a metal sheet having a first side and a second side, the second side of which overlaps the first side of the metal support plate and faces the first side of the metal support plate. In such a case, the metal sheet overlaps at least a portion (optionally, the entire) of the planar electrochemically active cell region, and the first side may have a region without protrusions directed away from the metal support plate, the electrolytic cell unit comprising a fluid flow region overlapping the first side of the metal sheet, the fluid flow region comprising a mesh, and the fluid flow region being a region for delivering a first fluid to the outermost layer of the cell chemical layer.

[0111] A kit of parts may be provided. The kit of parts may comprise two or more electrolytic cell units according to any one of claims 2 to 33, adapted to be stacked. The kit of parts may further comprise gaskets surrounding each fluid port provided through the electrolytic cell unit.

[0112] Preferably, at least one fluid port, typically at least one inlet port and at least one outlet port, is provided as an opening through the cell layer (e.g., its metal support plate) and the separator plate, respectively, and each fluid port is aligned with the others in the stacking direction and communicates with the fluid flow region (fluid volume) surrounded within the cell unit.

[0113] Preferably, at least the separator plate (and, optionally, additionally or alternatively, a metal support plate, if present) is provided with a molded port feature formed around its port, which extends inward within the fluid volume enclosed within the cell unit, the elements of which are laterally separated from each other to define the fluid path between the elements from the port, and allowing the passage of fluid from the port into the enclosed fluid volume and fluid flow region. The molded port feature may preferably be a dimpled projection formed by press working, which may be press-formed simultaneously with the flanged periphery. Instead of a dimpled projection, the molded port feature may be a discrete projection. The molded port feature transmits compressive force through the cell unit for use in compressing a gasket (enclosing and sealing the port) between adjacent cell units.

[0114] An electrolytic cell stack is provided. The electrolytic cell stack comprises a plurality of electrolytic cell units, the electrolytic cell units being stacked on top of each other, and adjacent electrolytic cell units being electrically connected by a fluid flow region between them.

[0115] A method for manufacturing an electrolytic cell unit is provided. The method includes the steps of: preparing a separator plate having a first side and a second side (optionally, preparing a planar metal sheet for the separator plate); preparing a cell layer having an electrochemically active cell region and having a first side and a second side; and superimposing the separator plate and the cell layer such that the second side of the separator plate overlaps the first side of the cell layer and faces the first side of the cell layer. The cell layer and / or separator plate form a first fluid flow region for delivering fuel to the first side of the cell layer (e.g., the first side of the electrochemically active region) and a second fluid flow region for discharging fluid from the second side of the cell layer (e.g., the second side of the electrochemically active region), wherein the cross-sectional area of ​​the second fluid flow region is smaller than the cross-sectional area of ​​the first fluid flow region.

[0116] The method may further include the step of processing at least one of a separator plate (e.g., a planar metal sheet) and a cell layer to form a second fluid flow region, the second fluid flow region being The outermost layer of the electrochemically active cell region (the second fluid flow region is the region from which the fluid is discharged from the outermost layer of the electrochemically active cell region), and One side of the separator plate (for example, its planar metal sheet) (the second fluid flow region is the region for fluid discharge from the outermost layer of the electrochemically active cell region of the adjacent electrolytic cell unit) By printing or depositing a material that forms a second fluid flow region on one or both of the above, or It is formed by patterning the outermost layer of the electrochemically active cell region (the second fluid flow region is the region from which the fluid is discharged from the outermost layer of the electrochemically active cell region).

[0117] The method may further include the step of preparing a cell layer by providing a metal support plate that supports an electrochemically active cell region, and the step of overlapping the separator plate and the cell layer further includes the step of overlapping the separator plate and the metal support plate. Optionally, the method may include the step of directly joining the metal support plate and the separator plate at their peripheries (for example, by a flange provided on at least one periphery of the plates).

[0118] Alternatively, the method further includes the steps of preparing a spacer plate, positioning the spacer plate between a separator plate and a metal support plate, and joining the separator plate, spacer plate and metal support plate by welding their periphery, preferably the three plates.

[0119] According to an alternative embodiment, a method for manufacturing an electrolytic cell unit, The steps include: preparing a separator plate having a first side and a second side (optionally, a flat metal sheet therefor), The steps include: preparing a metal support plate having a first side and a second side, wherein the second side supports an electrochemically active cell region; • Process at least one of the separator plate (e.g., its flat metal sheet) and the metal support plate, • The outermost layer of the cell chemical layer (the region for fluid delivery to the outermost layer of the cell region where the fluid flow region is electrochemically active), and • One side of the separator plate (e.g., its planar metal sheet) (the fluid flow region is the region for fluid discharge from the outermost layer of the electrochemically active cell region of the adjacent electrolytic cell unit) By printing or depositing a material that forms a fluid flow region on one or both of these, Alternatively, the process involves forming a fluid flow region by patterning the outermost layer of an electrochemically active cell region (the region through which the fluid flow region delivers fluid to the outermost layer of the electrochemically active cell region), The step of overlapping the separator plate and the metal support plate such that the second side of the separator plate overlaps the first side of the metal support plate and faces the first side of the metal support plate. A manufacturing method including this is provided.

[0120] A method for operating an electrolytic cell unit is provided. The method includes the steps of supplying fuel to a first fluid flow region to deliver fuel to a first side (e.g., a first side of a cell layer) of an electrochemically active cell region (e.g., a cell layer comprising an electrochemically active cell region); discharging fluid from a second fluid flow region to discharge fluid from a second side (e.g., a second side of a cell layer) of an electrochemically active cell region; and controlling the flow rate of the fluid in the first fluid flow region to at least twice the flow rate of the fluid in the second fluid flow region. Preferably, the flow rate of the fluid in the first fluid flow region is controlled to at least three times, more preferably at least five times, and even more preferably at least ten times, the flow rate of the fluid in the second fluid flow region.

[0121] A method for operating an electrolytic cell unit may include the step of supplying sweep gas to a second fluid flow region, the control step of further configuring the flow rate of fuel supplied to the first fluid flow region to be at least 3 times, optionally at least 5 times, and optionally at least 10 times, the flow rate of sweep gas supplied to the second fluid flow region.

[0122] The control step may be further configured to adjust the pressure difference between the first fluid flow region and the second fluid flow region in order to maintain the separation arrangement between the cell layer forming the first fluid volume and the separator plate.

[0123] The pressure difference between the first fluid flow region and the second fluid flow region can be adjusted to a range of 50 mbar to 2 bar, preferably 100 mbar to 1.5 bar, and more preferably 200 mbar to 800 mbar. The pressure difference is preferably adjusted to reduce the electrical contact resistance between the separator plate and the electrochemically active cell region of the second adjacent cell unit in the stack of cell units. By increasing the pressure difference, the electrical contact resistance can be reduced, resulting in improved stack efficiency.

[0124] The pressure difference can be adjusted, for example, by (i) the use of pumps to pump the first fluid in the first fluid flow region and the second fluid in the second fluid flow region at different rates; (ii) chokes such as valves or convergence-divergence nozzles (such as Laval nozzles) in conduits or flow paths that supply fluid to the first fluid inlet to the first fluid flow region and the second fluid inlet to the second fluid flow region or the second fluid outlet from the second fluid flow region of the entire cell unit and / or cell stack; or (iii) orifice plates in conduits or flow paths to help adjust the pressure difference between the first fluid in the first fluid flow region and the second fluid in the second fluid flow region. Other methods and apparatus that can be used to establish a pressure difference between the first fluid flow region and the second fluid flow region will be readily apparent to those skilled in the art. [Brief explanation of the drawing]

[0125] [Figure 1] This is a disassembled perspective view of the fuel cell unit and two gaskets. [Figure 2] This is a second perspective view of the configuration shown in Figure 1, viewed from a different angle. [Figure 2a] These are simplified cross-sectional views of the configuration shown in Figures 1 and 2. [Figure 3] This is a first exploded perspective view of a first configuration comprising a stack of two cell units separated by a gasket, each cell having two fluid ports. [Figure 4] Figure 3 is a lower exploded perspective view of the configuration. [Figure 5] This is a cross-sectional view of the configuration shown in Figure 3. [Figure 6] This is a first exploded perspective view of a second configuration, which comprises a stack of two cell units separated by a gasket, with each cell having four fluid ports. [Figure 7] Figure 6 is a lower exploded perspective view of the configuration. [Figure 8] This is a first exploded perspective view of a third configuration, comprising a stack of two cell units separated by a gasket, each cell having four fluid ports and a spacer plate. [Figure 9]Figure 8 is a lower exploded perspective view of the configuration. [Figure 10] This is a cross-sectional view of the configuration shown in Figure 8. [Figure 11] This figure shows a method for manufacturing a cell unit according to the present invention. [Figure 12] This figure shows a method for operating a cell unit in a steady state according to the present invention. [Figure 13A] This is a schematic cross-sectional view of an electrolytic cell unit. [Figure 13B] This is an exploded perspective view of a fourth configuration, which includes a stack of two electrolytic cell units separated by a gasket, with each electrolytic cell unit having four fluid ports. [Figure 14] This is an exploded perspective view of a fifth configuration, comprising a stack of two electrolytic cell units separated by a gasket, with each electrolytic cell unit having four fluid ports. [Figure 15] This is an exploded perspective view of a sixth configuration, comprising a stack of two electrolytic cell units separated by a gasket, with each electrolytic cell unit having two fluid ports. [Figure 16] This is an exploded perspective view of a seventh configuration, comprising a stack of two electrolytic cell units separated by a gasket, with each electrolytic cell unit having four fluid ports. [Figure 17] This is an exploded perspective view of an eighth configuration, comprising a stack of two electrolytic cell units separated by a gasket, with each electrolytic cell unit having four fluid ports. [Figure 18] This is an exploded perspective view of a ninth configuration, comprising a stack of two electrolytic cell units separated by a gasket, each electrolytic cell unit having four fluid ports and a spacer plate. [Figure 19A-B] A first exploded perspective view and a second exploded perspective view of a 10th configuration, which comprises a stack of two electrolytic cell units separated by a gasket, with each electrolytic cell unit having four fluid ports. [Figure 20] Figures 19A and 19B show two cross-sectional views of the tenth configuration. [Figure 21A-B]A first exploded perspective view and a second exploded perspective view of an eleventh configuration, comprising a stack of two electrolytic cell units separated by a gasket, each electrolytic cell unit having four fluid ports. [Figure 22] Figures 21A and 21B show two cross-sectional views of the 11th configuration. [Figure 23A-C] This is an exploded perspective view of a 12th configuration, comprising a stack of two electrolytic cell units separated by a gasket, with each electrolytic cell unit having four fluid ports. [Figure 24A-H] This is a simplified cross-sectional view of the electrolytic cell unit of the present invention. [Figure 25A-C] This is a plan view and related cross-sectional view of the further configuration of the electrolytic cell unit. [Figure 26] This figure shows a method for manufacturing an electrolytic cell unit according to the present invention. [Modes for carrying out the invention]

[0126] For illustrative purposes only, the figure shows only two electrochemical cell units in a stack (hereinafter each referred to simply as a "cell unit"). In various embodiments, multiple cells are provided. In further embodiments (not shown), multiple electrochemical cell stacks are provided, and in even further embodiments, multiple electrochemical cell stacks are provided, each comprising multiple electrochemical cells. It will be understood that the anode inlet and cathode inlet, outlet (off-gas), ducts, and manifolds, and their configurations, are modified to suit such embodiments and will be readily apparent to those skilled in the art.

[0127] Referring to Figure 3, the cell unit 300 comprises a flat (i.e., planar) metal support plate 314 stacked next to the separator plate 312. The metal support plate 314 is shown to have a flanged peripheral feature 318 on its periphery. The flanged peripheral feature 318 extends from the main plane of the sheet, as seen in the central fluid volume region, forming a concave surface (and a convex surface on the outer surface) on the metal support plate 314. This concave surface forms a first fluid volume 360 ​​within the cell unit when the cell unit is assembled. The separator plate comprises a metal sheet, having a first side and a second side. The second side of the separator plate extends across the first side of the cell layer and faces the first side of the cell layer. The two plates are sealed (e.g., welded) around their periphery to surround / seal the first closed fluid volume.

[0128] The cell unit 300 has rounded ends and parallel sides, and has one fluid port 322 toward each end of both the separator plate 312 and the metal support plate 314. Other shapes, sizes, and numbers of each cell feature are possible depending on the required output and dimensions of the final stack assembly.

[0129] In the central portion of the cell unit 300, an electrochemically active layer 350 is provided on the cell layer (here, a metal support plate having the cell layer is shown). In this embodiment, the electrochemically active layer 350 is located outside the first fluid volume 360.

[0130] The electrochemically active region 350 includes an anode, a cathode, and an electrolyte (not shown) positioned between the anode and the cathode. The anode, electrolyte, and cathode may together be referred to as the electrochemically active layer 350, the active electrochemical cell layer, or the electrochemically active region. The electrochemically active region may be a continuous, substantially rectangular region, which may be generally uninterrupted. Alternatively, the electrochemically active cell region may cover the fluid port to increase the proportion of the electrochemically active cell unit region, thereby increasing the power density of the cell unit stack. That is, near the port, the edge of the active cell region is molded to match the shape of the port. The edge of the active cell region forms a concentric subcircle with the port. The edge of the active cell region is separated from the edge of the port to provide space for molded port features and / or gaskets positioned around the port.

[0131] Electrolytes conduct either negative oxygen ions or positive hydrogen ions between the anode and cathode.

[0132] The stack may comprise a stack of cell units based on one of the following: a solid oxide electrolyte, a polymer electrolyte membrane, or a fused electrolyte, or any other variant capable of electrochemical action.

[0133] Figure 4 is a view of the same cell unit 300 as in Figure 3, but from a different angle. Figure 5 is a cross-sectional view of Figure 3. The cross-section is cut from the left rear to the right front, towards the rear of the center. A molded port feature 324 is provided around the fluid port of the metal support 314. The molded port feature 324 is provided as a plurality of elements in the form of projections extending from the plane of the base of the fluid volume by a distance corresponding to the height of the flanged periphery 318, i.e., provided to have the same height as the flanged periphery 318. This is so that when the cell unit 300 is assembled, the molded port feature 324, like the flanged periphery 318, will contact the opposing surface of the separator plate 312. As a result, when the flanged periphery 318 is joined to the separator plate 312, for example by welding, the molded port feature 324 will also contact the separator plate 312. The projections may have a circular, square, cruciate, pentagonal, or hexagonal cross-section. The protrusion may also have an elliptical or irregular polygonal cross-section.

[0134] The concave structure can impart to the associated plate the appearance of a bordered tray having a corresponding convex outer shape (outward relative to the cell unit) and usually a planar base, and thus the concave surface defines the first fluid volume 360 ​​(e.g., a portion thereof) within the assembled cell unit. In this concave structure, the flanged periphery 318 extends from the plane of the original sheet of the separator plate and / or the metal support plate toward the respective opposing surfaces of the separator plate and the other metal support plate.

[0135] Therefore, the first fluid volume 360 ​​is bounded by a flanged periphery 318 formed by press working, such as by die pressing, hydroforming, or stamping.

[0136] The metal support plate 314 (e.g., metal foil) is provided with a number of small holes or pores 348 so that the first fluid in the first fluid volume 360 ​​can communicate fluidly with the electrochemical layer supported by the second side (upper side as shown) of the cell layer / metal support plate. These holes or pores form porous regions bounded by non-porous regions. The anode (fuel electrode) layer is located adjacent to the small holes / pores, and the (closed) fluid volume 360 ​​in the cell unit comprises the first fluid volume 360 ​​supplied by the first fluid entering and leaving through the fluid port 322.

[0137] The first fluid may be a fuel (reformed hydrocarbon or other fuel (e.g., ammonia) if operating as a fuel cell, or vapor if operating as an electrolytic cell), in which case the fluid port 322 becomes the fuel port 322. The anode (fuel electrode) layer may be coated onto the metal support plate 314 or otherwise deposited. The cathode (air electrode) layer is on the opposite side of the electrochemically active layer 350, i.e., on its outer surface, and is exposed to air flowing across its layer during use of the cell unit.

[0138] The cell units shown in Figures 3, 4, and 5 require only two layers (components): a metal support plate and a separator plate.

[0139] Furthermore, the separator plate 312 is provided with projections 336 extending from the separator plate 312 toward the adjacent cell unit (i.e., toward the metal support plate 314 of the cell unit, of which the separator plate is a component). These downward projections 336 (within the planar area of ​​the electrochemically active layer), including outward (downward as shown) projections, extend from the separator plate 312 and, within the stack of cell units, contact the outer surface of the electrochemically active layer of the cell unit adjacent to the separator plate. The central downward projections 336 define a fluid path for an oxidizer (such as air) through a second fluid volume 365 defined between or within them and between the downward projections and the outer surface of the electrochemically active layer of the cell unit adjacent to the downward projection.

[0140] When formed in a stack of cell units, the second side of the separator plate of the first cell unit faces the first side of the cell layer of the first cell unit, spaced apart to form a first fluid volume for the first fluid, and the first side of the separator plate of the first cell unit faces the electrochemically active cell region of a second adjacent cell unit in the stack of cell units, defining a second fluid volume between them. The first fluid volume is the volume for the first fluid (fuel in the form of reformed hydrocarbon fuel or other fuel (e.g., ammonia) in fuel cell operation, or vapor in electrolytic cell operation, etc.), and the second fluid volume is the volume for the second fluid (oxidizer in fuel cell operation, or generated oxygen in electrolytic cell operation, etc.). Between each cell unit in the stack, two or more gaskets 334 are provided beneath each cell unit (one surrounding each port, and there may be three or more gaskets), i.e., the gaskets are positioned between adjacent cell units in the stack. Multiple inlet ports and multiple outlet ports may exist.

[0141] Each gasket 334 (also called a "seal") provides a primary sealing function and is preferably a compressible gasket. The gasket performs its sealing function by being subjected to compressive force in the vicinity of the port, for example, through means to which compressive force can be applied. The gasket is sized to cover all of the molded port features 324 of each fluid port 322, thereby preventing a first fluid that can move through the fluid port 322 (such as (reformed) hydrocarbon fuel or other fuels (e.g., ammonia) in fuel cell operation, or vapor in electrolytic cell operation) from leaching out from between the outside of the cell unit 300 and the gasket 334 into an area outside the cell unit, i.e., a second fluid volume surrounding the cell unit 300 (such as an oxidizer in fuel cell operation, or generated oxygen in electrolytic cell operation), or preventing fluid outside the fluid port from leaching in the other direction, i.e., into the fluid port. This helps prevent any mixing of the fluid inside the cell unit 300 with the fluid outside the cell unit 300 (which may be fuel and oxidizer), and the polarity of the electrochemically active layer 350 determines which direction this is.

[0142] The gasket can also provide electrical insulation between the first cell unit and the adjacent fluid cell unit to prevent short circuits. The gasket can be any suitable cell gasket (sealing ring), such as Thermiculite®.

[0143] Compressive forces within the stack near the electrochemically active layer are typically required for good electrical contact between cell units within the stack, and consequently for good conductivity through the stack. The central downward projection 336 creates the necessary electrical contact between cell units (and the joining, preferably by welding, of the separator and cell layer means that these components are electrically connected). For example, in a stack configuration, the central downward projection 336 on the first side of the separator plate 312 of the first cell unit in the stack contacts the outermost layer of the electrochemically active cell region of a neighboring cell unit in the stack, resulting in their electrical contact.

[0144] Unlike the prior art shown in Figures 1 and 2, the first configuration does not have a central projection, i.e., a projection extending between the inner opposing surfaces of the two plates (i.e., the separator plate and the cell layer / metal support plate). Therefore, the fuel enters the first fluid volume 360 ​​through the fluid port 322 and can flow freely across the entire surface of the separator plate 312 and throughout the entire first fluid volume.

[0145] Furthermore, as shown in Figures 3, 4, and 5, the region of the separator plate 312 beneath the electrochemically active layer 350 of the cell lacks any other components that could act to separate the separator plate 312 from the metal support plate 314.

[0146] Furthermore, unlike the conventional technology shown in Figures 1 and 2, the first configuration does not have a central upward projection extending between the inner opposing surfaces of the two plates. Therefore, there are no feature parts within the cell unit that serve as support for the cell unit in the central region, extending toward the metal support plate (or upward toward the underside of the metal support plate, as shown in Figures 3, 4, and 5) in the region of small holes (also called the porous region, corresponding to the planar view area of ​​the electrochemically active layer).

[0147] In previous designs (e.g., Figures 1 and 2), cell units are stacked with gaskets 34 between each repeating unit. Before compression, the gaskets 34 are thicker than the height of the projections 36, and the projections do not contact the next unit. When the stack is compressed, initially the compressive force acts only through the gaskets (because the projections are not in contact). At some point, the gaskets 34 are compressed enough that the projections make contact. As the stack is further compressed, the compressive force acts through both the gaskets 34 and the projections 36. This can lead to the problems described above.

[0148] In the new concept, since there are no protrusions directed toward the cell layer 348, the gasket 334 can be compressed as needed, and the compressive force does not act through protrusions or other structures near the active cell region (there may be some movement of the substrate / interconnect depending on the stiffness of the plate, etc., but such movement is minor). Therefore, compression in the active cell region is decoupled from gasket compression and is controllable by a pressure difference, such a pressure difference acting to push the cell layer (its metal support plate 314) and the interconnect 312 of the cell unit (which consists of the cell layer and interconnect) apart. The interconnect of the cell unit is then biased toward an adjacent cell unit (typically the electrochemically active layer of the cell layer of the adjacent cell unit) and comes into contact with it, thereby creating the necessary electrical contact between adjacent cell units. In this new configuration, the force transmitted by the protrusions 316 can be greatly reduced. The final force through the protrusions and the active region is achieved by the pressure difference.

[0149] Referring to Figures 6 and 7, the cell unit 600 is similar to the cell unit 300 in Figures 3, 4, and 5, except that the separator plate 612 of the cell unit 600 has a flanged periphery 618 instead of a metal support plate 614, and that molded port features are provided on the separator plate 618, providing a different configuration of fluid ports. The flanged periphery 618 extends from the main plane of the sheet, as seen in the central fluid volume region, forming a concave surface (and a convex surface on the outer surface) on the separator plate. This concave surface forms a first fluid volume 660 within the cell unit during assembly.

[0150] It should be noted that the configurations in Figures 6 and 7 can be modified in the same way as already described in relation to the configurations in Figures 3, 4, and 5. For example, the first fluid volume may be formed by the flanged periphery of either or both of the separator plate and the metal support plate. If both have flanges, the molded port feature may have the same total height as the sum of the flanges of both plates. One plate may have a flange and the other may have a port feature. Three or more ports may be present.

[0151] The cell unit 600 has rounded ends and parallel sides, and has one fluid port 622 toward each corner of both the separator plate 612 and the metal support plate 614, thereby bringing the total number of fluid ports 622 to four. Other shapes, sizes, and numbers of each cell feature are possible depending on the required output and dimensions of the final stack assembly.

[0152] A molded port feature similar to the molded port feature 324 of the cell unit 300 is provided around the fluid port 622 of the separator plate 612. The molded port feature is provided as multiple elements in the form of projections extending from the base plane of the fluid volume 660 by a distance corresponding to the height of the flanged periphery 618, i.e., provided to have a common height with the flanged periphery 618. This is so that when the cell unit 600 is assembled, the molded port feature, like the flanged periphery 618, will contact the opposing surface of the metal support plate 614. As a result, when the flanged periphery 618 is joined to the metal support plate 614, for example by welding, the molded port feature will also contact the metal support plate 614. The projection may have a circular, square, cruciate, pentagonal, or hexagonal cross-section. The projection may also have an elliptical or irregular polygonal cross-section.

[0153] Referring to Figures 8, 9, and 10, the cell unit 800 is the same as the cell units 300 and 600 described above (as shown in the same figures), except that neither the separator plate 812 nor the metal support plate 814 of the cell unit have flanged periphery portions. A spacer plate 816 is provided between the separator plate 812 and the metal support plate 814 to form a first closed fluid volume 860 between the separator plate 812 and the metal support plate 814 of the cell unit 800.

[0154] The cell unit 800 has rounded ends and parallel sides, and has one fluid port 822 facing each corner of the separator plate 812, metal support plate 814, and spacer plate 816, resulting in a total of four fluid ports 822. Other shapes, sizes, and numbers of each cell feature are possible depending on the required output and dimensions of the final stack assembly.

[0155] When the spacer plate 816 is in a predetermined position within the cell unit, it overlaps the periphery of the separator plate 812 above / below and the periphery of the metal support plate 814 below / below. The central hollow portion 817 of the spacer plate 816 is at least above / below the central downward projection 836 that extends between the separator plate 812 and the region of the electrochemically active layer of the cell unit adjacent to the outward projection. The hollow central portion 817 is further at least below / below the porous region (multiple small holes) provided in the metal support plate 812, allowing the fluid in the first fluid volume to communicate with the side of the electrochemical layer closest to the metal support plate 814. When the hollow portion 817 of the spacer plate 816 is sandwiched between the separator plate 812 and the metal support plate 814, it forms a fuel volume between the separator plate 812 and the metal support plate 814.

[0156] Unlike the first and second configurations, the third configuration does not have molded port features around the fluid port of the separator plate. The spacer plate acts to separate the metal support plate of the cell unit from the separator plate. The throat of the spacer plate allows fluid communication between the port and the first fluid volume.

[0157] In each of the above configurations, since there is no central upward projection extending between the inner opposing surfaces of the two plates (i.e., the separator plate and the cell layer / metal support plate), means are provided to establish and maintain the first fluid volumes 360, 660, 860 between the metal support plates 314, 614, 814 and the separator plates 312, 612, 812 during the operation of the cell unit.

[0158] If cell units 300, 600, and 800 are fuel cell units (or stacks of fuel cell units), then fuel (i.e., anode inlet gas, e.g., hydrocarbon fuel, reformed hydrocarbon fuel, H2, ammonia) is supplied to the anode inlet of the cell unit and enters a first fluid volume (fuel volume) between the separator plates 312, 612, and 812 and the cell layer (or metal support plates 314, 614, and 814) via ports 332, 632, and 832. Simultaneously, oxidizer (i.e., cathode inlet gas) is supplied to the cathode inlet of the cell unit and flows to either side of the separator plates 312, 612, and 812 and the cell layer (or metal support plates 314, 614, and 814). The fuel and oxidizer may flow in a parallel flow configuration such that they flow in the same direction across each side of the cell unit. Alternatively, the fuel and oxidizer may flow in a counterflow or direct-to-alternating configuration.

[0159] If the cell units 300, 600, and 800 are fuel cell units, the fuel and oxidizer are supplied to the fuel cell units at different pressures, creating a pressure difference between the fuel and oxidizer as they pass through the fuel cell units. This creates a pressure difference between the first side (closer to the oxidizer) and the second side (closer to the fuel) of the separator plates 312, 612, and 812. By creating a pressure difference between the first and second sides, the separation between the separator plate (the second side) and the cell layer (the first side) (or the first side of the metal support plates 314, 614, and 814) can be controlled. For example, the separation can be maintained or increased to form and maintain a first fluid volume.

[0160] The separator plates can be adapted or configured to flex when exposed to a pressure difference so that the separation between the separator plates 312, 612, 812 and the cell layers (or metal support plates 314, 614, 814) can be maintained or increased by creating a pressure difference between the first side and the second side. For example, when exposed to a pressure difference, the separator plate can flex away from the cell layers (or metal support plates) of the cell units (and toward adjacent cell units) as the pressure difference increases; that is, the separator plate can be adapted to flex away from the cell layers (or metal support plates) when exposed to a pressure difference as a positive function of the pressure difference.

[0161] In a stacked configuration, the central downward projections 336, 636, 836 on the first side of the separator plates 312, 612, 812 of the first cell unit in the stack contact the outermost layer of the electrochemically active cell region of a neighboring cell unit in the stack, resulting in electrical contact between them.

[0162] When each separator plate 312, 612, 812 is exposed to a pressure difference and bends away from the cell layer of the corresponding cell unit (or metal support plates 314, 614, 814), the contact resistance between the central downward projections 336, 636, 836 and the outermost layer of the electrochemically active cell region of the adjacent cell unit decreases. That is, the contact resistance between the central downward projections 336, 636, 836 and the outermost layer of the electrochemically active cell region of the adjacent cell unit decreases as the pressure difference between the first and second sides of the separator plate increases.

[0163] During operation, the pressure difference between the first and second sides of the separator plate can be controlled to be in the range of 50 mbar to 2 bar, preferably 100 mbar to 1.5 bar, and more preferably 200 mbar to 800 mbar.

[0164] A method for manufacturing any of the cell units described in any of the embodiments above includes several steps / operations. This method includes the following steps:

[0165] In step 1110, a separator plate having a first side and a second side is prepared, for example, by cutting or stamping. The separator plate may be, for example, a non-porous planar metal sheet or any other non-porous planar sheet, and acts to separate one cell unit in the stack from adjacent cell units. The separator plate may be provided with projections extending from the plate of the separator plate, which may be provided by pressing / forming in the same step as cutting / stamping.

[0166] In step 1120, a cell layer is prepared that includes an electrochemically active cell region comprising an anode, a cathode, and an electrolyte (not shown) positioned between the anode and the cathode. The cell layer has a first side and a second side, and is preferably a metal-supported cell layer. The step of adding the cell layer may include, for example, depositing or coating the cell layer onto a planar metal sheet by printing the electrochemically active cell region onto the cell layer, thereby forming a metal-supported cell layer having porous regions (holes) that allow fluid communication from the first side to the electrode supported on its second side by a metal support plate. Alternatively, the cell layer may be self-supporting. For example, the cell layer may have an anode-supported, electrolyte-supported, or cathode-supported structure. For illustrative purposes only, the term “metal support plate” is used below, but is interchangeable with “cell layer” or “metal plate-supported cell layer.”

[0167] Step 1110 or step 1120 preferably includes preparing either a cell layer (or metal plate support cell layer) having a flanged periphery 318, or a separator plate having a flanged periphery 618. The flanged periphery 318 or 618 extends from the main plane of the metal plate support plate 314 or from the separator plate 618, respectively.

[0168] The flanged periphery 318 forms a concave surface (and a convex surface on the outer surface) on the metal support plate 314. This concave surface forms a first fluid volume 360 ​​within the cell unit during assembly. The flanged periphery 618 forms a concave surface (and a convex surface on the outer surface) within the separator plate. This concave surface forms a fluid volume within the cell unit during assembly. The flanged periphery of either the separator plate or the metal support plate can be manufactured by press-forming the separator plate or the metal support plate (of the cell layer), respectively.

[0169] Instead of a flanged periphery, a spacer plate may be provided and sandwiched between the separator plate and the metal support plate to form a first fluid volume between the separator plate and the metal support plate.

[0170] Steps 1110 and 1120 further include providing a plurality of fluid ports 322, 622, 822 in both the separator plate and the metal support plate to enable the flow of fluid (such as reformed fuel) through the cell units (and ultimately through the stack of cell units) to supply fuel to each cell unit, in particular to supply fuel to the first fluid volume of each cell unit.

[0171] In step 1130, the separator plate and the metal support plate are superimposed in a manner that they are spaced apart to form a first fluid volume between them. Thus, the separator plate has a region that extends at least over the electrochemically active cell region. In step 1130, the separator plate and the metal support plate are superimposed such that when the cell units are arranged in a stack configuration, the projections extending from the plane of the separator plate are oriented away from the first fluid volume toward the adjacent cell unit. That is, there is a continuous region that extends at least over the electrochemically active cell region and does not include any projections directed toward the metal support plate. Nor does it include any other components configured to resist stack compressive forces and transmit such forces to projections connecting adjacent cell units. Thus, within the first fluid volume, there are no components between the separator plate and the metal support plate to help physically separate them from each other (especially during operation).

[0172] In step 1130, the separator plate and the metal support plate may be directly joined (and sealed) at the flanged periphery described above to form a first fluid volume between them. The separator plate and the metal support plate may optionally be directly joined by welding.

[0173] In an alternative configuration without a flanged periphery, a spacer plate is provided and sandwiched between the separator plate and the metal support plate to form a first fluid volume between them, but in step 1130, the three plates are sealed and fixed to each other, for example, by welding their peripheries.

[0174] When forming a stack of cell units, the method may be continued, and the second side of the separator plate of the first cell unit (formed as described above) is positioned to overlap above / below the second cell unit, such that the first side of the separator plate of the first cell unit faces the electrochemically active cell region of the second adjacent cell unit in the stack of cell units, and surrounds the second fluid volume between them. When forming the stack, multiple gaskets are provided corresponding to multiple fluid ports of the cell unit. Each gasket is positioned around the fluid port of a neighboring cell unit in the stack. The function of the gaskets has already been described above.

[0175] The method for operating the cell stack of the cell unit as described in the above embodiment includes several steps / operations, as follows:

[0176] In step 1210, a first fluid is supplied to a first fluid volume formed between the separator plate and the metal support plate. The first fluid may be a fuel. To operate as a fuel cell, the first fluid may be a hydrocarbon fuel, a reformed hydrocarbon fuel, ammonia, H2, methanol, etc. To operate as an electrolytic cell, the first fluid is typically vapor.

[0177] In step 1220, a second fluid is supplied to a second fluid volume formed between the separator plate of the first cell unit in the stack and the electrochemically active cell region of the second adjacent cell unit in the stack. The second fluid may be an oxidizing fluid. To operate as a fuel cell, the second fluid may be an oxidizing fluid, such as air or oxygen supplied to the second fluid volume via the inlet. To operate as an electrolytic cell, the second fluid is typically oxygen produced in an electrolytic reaction.

[0178] In step 1230, the pressure difference between the first fluid volume and the second fluid volume is adjusted to maintain the separation configuration that forms the first fluid volume. For example, the pressures of the first fluid (e.g., fuel) and the second fluid (e.g., air / oxygen) may be adjusted to create a pressure difference between the two fluids. This pressure difference can then cause the separator plate to flex, increasing the separation between the separator plate and the metal support plate, thereby forming and maintaining the separation configuration that forms the first fluid volume. The pressure difference between the first fluid volume and the second fluid volume may be in the range of 50 mbar to 2 bar, preferably 100 mbar to 1.5 bar, more preferably 200 mbar to 800 mbar. Adjusting the pressure difference may also reduce the electrical contact resistance between the separator plate and the electrochemically active cell region of the second adjacent cell unit in the stack (the pressure in the first fluid volume is controlled to be higher than the pressure in the second fluid volume, and as the pressure difference increases, the contact resistance decreases).

[0179] The pressure difference can be adjusted through the use of pressure pumps to pump the first and second fluids at different rates. Alternatively, or additionally, the flow of the first and / or second fluids may be choked by providing valves or convergence-divergence nozzles (such as Laval nozzles) in the conduits or flow paths that supply fluid to the cell units of the stack. Alternatively, or additionally, orifice plates can be provided in the conduits or flow paths to help adjust the pressure difference. Other methods and apparatus that may be used to establish a pressure difference will be readily apparent to those skilled in the art.

[0180] The cell units described with reference to Figures 3 to 10 may be fuel cell units or electrolytic cell units. Next, with reference to Figures 13 to 24, further electrolytic cell units having features that can be combined with the features described with reference to Figures 3 to 10 (described with reference to Figures 19 to 24) will be described. Referring to Figure 13A, a simplified diagram of an electrolytic cell unit is shown. The electrolytic cell unit of Figure 13A may be a special case of the cell units described with reference to Figures 3 to 10, and it will be understood that the terminology and configuration of the cell layers and separator plates of the cell unit (i.e., repeating unit) are consistent with all examples described herein.

[0181] Figure 13A shows a cell layer 1314 and two proximity separator plates 1312a and 1312b. These three components are merely examples, and it will be understood that a cell unit (i.e., an iterative unit) consists of one cell layer 1314 and one separator plate 1312, and multiple cell units can be stacked on top of each other to form a stack of cell units.

[0182] The cell layer includes electrochemically active cell regions 1350. These electrochemically active cell regions 1350 may be self-supporting (in which case the cell layer may consist of electrochemically active cell regions 1350) or may be supported by a support plate (the support plate having porous regions for fluid communication between the electrochemically active cell regions 1350 and a first fluid flow region).

[0183] The cell layer 1314 and the separator plates 1312a and 1312b each have a first side and a second side. The first side 1313a of each separator plate 1312 faces the second side 1315b of each cell layer 1314. The second side 1313b of each separator plate 1312 faces the first side 1315a of each cell layer 1314.

[0184] The first fluid flow region 1360 is defined between the first side 1315a of the cell layer 1314 and the second side 1313b of the separator plate 1312. The second fluid flow region 1365 is defined between the second side 1315b of the cell layer 1314 and the first side 1313a of the separator plate 1312.

[0185] The first fluid flow region 1360 is a region for delivering fuel to the first side of the cell layer 1314 (i.e., to the layer of electrochemically active cell region 1350 that is in fluid communication with the first fluid flow region 1360, optionally via the porous region 1355 of the support plate, if the cell layer 1314 comprises a support plate supporting an electrochemically active cell region 1350). The first fluid flow region 1360 further discharges the products of the electrolytic reaction in the electrochemically active cell region 1350 (and discharges unused fuel).

[0186] The second fluid flow region 1365 is for the discharge of products of electrolytic reactions in the electrochemically active cell region 1350. In some cases, a sweep gas may also be supplied (and discharged) through the second fluid flow region, which helps to discharge the off-gas. If the off-gas is oxygen, exhaust gas accumulation can be dangerous, especially when operating at high pressure and high temperature. The sweep gas may be, for example, oxygen, an oxidizer, air, or another suitable gas.

[0187] Figure 13A shows that the cross-sectional area of ​​the second fluid flow region 1365 is smaller than that of the first fluid flow region 1360. This difference in cross-sectional area can be defined by the height h2(1366) of the second fluid flow region 1365 being smaller than the height h1(1361) of the first fluid flow region 1360. Alternatively, or additionally, the cross-sectional area may be defined by multiple channels, protrusions, or other features (see Figures 14-24 and the relevant descriptions below). The ratio of cross-sectional area (and in specific cases, height) may be less than or equal to 1:2, less than or equal to 1:3, or less than or equal to 1:10.

[0188] The intention of such a configuration is to reduce contact resistance by increasing the contact area between the second side of the cell layer and the first side of the separator plate (i.e., which may be the air side in the case of SOEC). This can be achieved by forming a separator plate having a "flat" first side (sometimes called a "flat" air-side separator plate in the case of SOEC). In this context, "flat" means that the separator plate itself (e.g., the metal sheet forming the separator plate) does not have any features that essentially protrude outward. The separator plate may have concave formations and / or a series of discrete protrusions deposited thereon to form a second fluid flow region (which may also be called a region for the discharge of fluid generated in the electrochemically active cell region, and which may be called an air volume in the case of SOEC). In such a case, a larger contact area is available instead of dimple vertices (see Figures 1 and 2), thereby reducing resistance within or between cell units and improving the performance of the electrolytic cell unit and its stack.

[0189] The separator plate 1312 (also called the interconnect), having a "flat" first side 1313a (the "air side" in the case of SOEC), allows for this increase in contact area, which is manifested by the fact that the cross-sectional area of ​​the second fluid flow region (the region for the second fluid discharged from the second side of the electrochemically active cell region and produced by the electrochemically active cell region, e.g., oxygen in the case of SOEC) is smaller than the cross-sectional area of ​​the first fluid flow region (the region for the first fluid, e.g., fuel such as water in the case of SOEC).

[0190] The volumetric flow rate in the second fluid flow region ("air side") may be significantly lower than that in the first fluid flow region of the electrolytic cell ("fuel side"), partly because, unlike fuel cell operation, the endothermic electrolysis reaction does not require the cooling properties of airflow, and therefore the cross-sectional area can be reduced accordingly. However, as will be explained below, reducing this excessively risks creating an unacceptably high pressure difference between the air side and the fuel side, which could damage the cell.

[0191] As will be explained below, in some examples this can also mean that the separator plate requires less molding / pressing. Such interconnects can be more robust and / or reliable (e.g., fewer defects during manufacturing). This can lead to cost reductions in the manufacturing process (even considering the cost of increased quantities of such materials if ceramic materials are used to form the fluid flow regions).

[0192] Area resistivity has been found to decrease by up to 10% in some configurations where a "flat" air-side separator plate is used, and therefore, power density increases by the same amount.

[0193] In particularly advantageous embodiments, both sides 1313a, 1313b of the separator plate are "flat," and layers of discrete protrusions and / or electrochemically active regions 1315b on the separator plate form their respective fluid flow regions. Such embodiments are shown in Figures 19–23 and 24F.

[0194] An electrolytic cell unit (i.e., a repeating unit, a set of units forming a stack) comprises one cell layer 1314 and one separator plate 1312. In one example, an electrolytic cell unit 1300 is formed from a cell layer 1314 and a separator plate 1312a, the components enclosing a first fluid flow region 1360 between a second side 1313b of the separator plate and a first side 1315a of the cell layer, and when so enclosing, the first fluid flow region may be called the first fluid volume. When two electrolytic cell units 1300 are stacked, a second fluid flow volume 1365 is bounded between the second side 1315b of the cell layer 1314 of the first cell unit 1300 and the first side 1313a of the separator plate 1312b of the second adjacent (also called proximity) cell unit 1300, and may be called the second fluid volume.

[0195] In one example, an electrolytic cell unit 1370 is formed from a cell layer 1314 and a separator plate 1312b, the components enclosing a second fluid flow region 1365 between a first side 1313a of the separator plate and a second side 1315b of the cell layer, which, when enclosed, may be called a second fluid volume. When two electrolytic cell units 1370 are stacked, a first fluid flow volume 1360 is bounded between the first side 1315a of the cell layer 1314 of the first cell unit 1300 and the second side 1313b of the separator plate 1312a of the second adjacent (also called proximity) cell unit 1370, and may be called a first fluid volume.

[0196] The cell layer is typically planar, at least within the planar area of ​​the electrochemically active cell region 1350. The separator plate is typically formed from a planar sheet, such as a metal sheet. In the electrolytic cell units of Figures 13 to 22, the separator plate has no protrusions from its first side 1313a, at least within the planar area of ​​the electrochemically active cell region 1350. That is, unlike in Figures 1 and 2, the separator plate (specifically, the (e.g., metal) sheet forming the separator plate) does not have any formations or press-formed dimples that protrude into the second fluid flow region 1365. Instead, to form the second fluid flow region 1365, features are provided within or on the second side 1315b of the cell layer 1314 and / or on the first side 1313a of the separator plate 1312. These features may be ribs or discrete projections provided within or on the second side 1315b of the cell layer 1314 and / or on the first side 1313a of the separator plate 1312, forming contact points between the first side 1313a of the separator plate 1312 and the second side 1315b of the cell layer 1314, resulting in electrical contact (and / or transmission of compressive force) through or between cell units. The ribs or discrete projections will be described with reference to Figures 13B to 24. Alternatively, the features may be a porous layer between the second side 1315b of the cell layer 1314 and the first side 1313a of the separator plate 1312. This porous layer may be deposited or coated on either or both of the second side 1315b of the cell layer 1314 and the first side 1313a of the separator plate 1312, or may be a component (e.g., an expanded metal sheet or mesh) between them.

[0197] Similar features in the form of porous layers, ribs, or discrete protrusions are provided on the second side 1313b of the separator plate 1312, or on or within the first side 1315a of the cell layer 1314, to form contact points between the second side 1313b of the separator plate 1312 and the first side 1315a of the cell layer 1314, or on or within the first side 1315a of the cell layer 1314, to provide electrical contact and / or to transmit compressive forces through or between cell units. Alternatively, molded or press-formed dimples (not shown) may protrude from the second side 1313b of the separator plate 1312 toward the first side 1315a of the cell layer 1314 and in contact with the first side 1315a of the cell layer 1314, the dimples being part of the metal sheet forming the base of the separator plate. Alternatively, or as an addition, the separator plate may be configured to be exposed to the pressure difference between the first fluid flow region and the second fluid flow region, as will be described with reference to Figures 3–12, 19 and 20. The pressure difference eliminates the need for dimpled protrusions in the first fluid flow region. Ribs or discrete protrusions, or dimples, or the pressure difference are used to maintain the height 1361 of the first fluid flow region 1360, as will be further described with reference to Figures 13B–24.

[0198] Referring to Figure 13B, two exemplary electrolytic cell units 1300 are shown in exploded perspective views, along with cross-sectional views AA, BB, and CC, through the two electrolytic cell units in a stacked arrangement (note that the height direction of the cross-section is exaggerated for clarity). The electrolytic cell unit 1300 comprises a cell layer having an electrochemically active cell region 1350, the electrochemically active cell region 1350 having a first side and a second side. A first fluid flow region 1360 is provided on the first side of the electrochemically active cell region 1350. A second fluid flow region 1365 is provided on the second side of the electrochemically active cell region 1350. In an exemplary electrolytic cell unit, a first fluid flow region is a region for supplying fuel to a first side of an electrochemically active cell region 1350, and a second fluid flow region is a region for discharging fluid from at least a second side of the electrochemically active cell region 1350, wherein the cross-sectional area of ​​the second fluid flow region is smaller than that of the first fluid flow region. The smaller cross-sectional area of ​​the second fluid flow region (due to its lower height) allows for an increase in the number of cell units at a given height (or, in other words, a decrease in the total stack height relative to a given number of cell units), thereby increasing the power density of the cell units (and their stacks).

[0199] In Figure 13B, the cell layer comprises a flat (i.e., planar) metal support plate 1314 supporting an electrochemically active cell region 1350, and the cell layer is stacked after a separator plate 1312 to form an electrolytic cell unit 1300. In this example, the cell unit 1300 is formed from the separator plate, with its second side 1313b facing the first side 1315a of the cell layer (and thus the first side of the electrochemically active cell region 1350). Conversely, the cell unit may be described as having the first side 1313a of the separator plate facing the second side 1315a of the cell layer (and thus the second side of the electrochemically active cell region 1350).

[0200] The cell unit 1300 has rounded ends and parallel sides, and has four fluid ports 1322 facing each corner of both the separator plate 1312 and the metal support plate 1314. Other shapes, sizes, and numbers of each cell feature are possible depending on the required output and dimensions of the final stack assembly.

[0201] The separator plate 1312 is shown to have a flange 1318 on its periphery. The flange 1318 extends from the main plane of the sheet, as seen in the central fluid volume region, forming a concave surface (and a convex surface on the outer surface) on the separator plate 1312. This concave surface forms a first fluid volume 1360 within the cell unit when the cell unit is assembled. The first fluid volume 1360 forms a first fluid flow region for the delivery and / or discharge of the first fluid, from which the first fluid is supplied and removed by ports in the separator plate and the metal support plate. The separator plate has a first side and a second side and comprises a metal sheet. The second side of the separator plate extends across the first side of the cell layer and faces the first side of the cell layer. The two plates are sealed (e.g., welded) around their periphery, enclosing and sealing the closed first fluid volume. Although flange 1318 is shown as being located within the separator plate, it will be understood in this example and subsequent examples that the flange may, alternatively, be located within the metal support plate, or the total height of the first fluid volume may be formed by corresponding flanges provided within the metal support plate and separator plate, which are opposite each other.

[0202] The concave structure can impart to the associated plate the appearance of a rimmed tray having a corresponding convex outer shape (outward relative to the closed volume of the cell unit) and usually a planar base, so that the concave surface defines the first fluid volume 1360 (e.g., a portion thereof) within the assembled cell unit. In this concave structure, the flange 1318 extends from the plane of the separator plate and / or the plane of the metal support plate toward the respective opposing surfaces of the separator plate and the other metal support plate.

[0203] Therefore, the first fluid volume 1360 is bounded by a flange 1318 which can be formed by press working such as die pressing, hydroforming, or stamping.

[0204] In the central portion of the cell unit 1300, the cell layer has an electrochemically active layer 1350 supported by a metal support plate 1314. In this example, the electrochemically active cell region 1350 is supported by the metal support plate on the side opposite to the first fluid volume 1360, and the porous region of the metal support plate allows fluid communication between the first fluid volume 1360 and one electrode of the electrochemically active cell region 1350. The use of the metal support plate allows the electrochemically active cell region 1350 to be coated or deposited on it. However, it will be understood that the cell layer may be formed by self-supporting electrochemically active cell regions.

[0205] The electrochemically active region 1350 includes an anode, a cathode, and an electrolyte (a layer not shown) positioned between the anode and the cathode. The anode, electrolyte, and cathode may together be referred to as the electrochemically active region 1350, the active electrochemical cell layer, or the electrochemically active region. The electrochemically active region may be a continuous, substantially rectangular region. Furthermore, the electrochemically active cell region may increase the proportion of the electrochemically active cell unit region by covering the fluid port, thereby increasing the current density of the stack of cell units. That is, in the vicinity of the port, the edge of the active cell region may be molded to match the shape of the port. For example, the edge of the electrochemically active cell region may form a concentric subcircle with the port. In such a case, the edge of the electrochemically active cell region is separated from the edge of the port, making space for the molded port feature and / or the gasket 1370 positioned around the port.

[0206] Depending on the specific type of electrochemically active cell region, the electrolyte conducts either negative oxygen ions or positive hydrogen ions between the anode and cathode. For example, a solid oxide electrolytic cell (SOEC) conducts oxygen ions from the fuel side of the electrochemically active cell region to the other side, thereby generating oxygen on the other side for emission by a second flow region. On the other hand, a proton exchange membrane (PEM) electrolytic cell conducts hydrogen ions from the fuel side of the electrochemically active cell region to the other side, thereby generating hydrogen on the other side for emission by a second flow region. Other types of electrochemically active cell regions, such as molten electrolytes, may exist and be used.

[0207] The metal support plate 1314 (e.g., a metal foil) is provided with a porous region (typically formed by a plurality of small holes or pores (shown in cross-sectional view AA)) so that a first fluid in a first fluid volume 1360 can fluidly communicate with the first side of an electrochemically active cell region 1350 supported by a second side (upper side as shown in the figure) of the metal support plate. This porous region is bounded by a non-porous region, and the electrochemically active cell region covers the entire porous region. The cathode (fuel electrode) layer is located adjacent to the small holes / pores, and the (closed) fluid volume 1360 within the cell unit comprises a first fluid volume 1360 through which the first fluid is supplied and discharged by entering and exiting through a fluid port 1322.

[0208] The first fluid may be a fuel for the electrolytic cell. The fuel for the electrolytic cell may be H2O (typically in vapor form). If the electrochemically active cell region 1350 conducts oxygen ions (e.g., an electrochemically active cell region of a solid oxide), the cathode (fuel electrode) layer may be coated onto the metal support plate 1314 or otherwise deposited. The anode (air electrode) layer is on the opposite side of the electrochemically active layer 1350, i.e., its outer surface. During use, the electrochemically active cell region 1350 conducts oxygen ions, and therefore oxygen is produced on the second (anode) side of the electrochemically active cell region 1350 for emission by the second fluid flow region, and hydrogen is produced on the first (cathode) side, i.e., the fuel side, of the electrochemically active cell region 1350 for emission by the first fluid flow region. When the electrochemically active cell region 1350 conducts hydrogen ions, it will be understood that hydrogen is produced on the second side of the electrochemically active cell region 1350 for emission by the second fluid flow region, and oxygen is produced on the first side of the electrochemically active cell region 1350, i.e., the fuel side, for emission by the first fluid flow region. Other fuels may be used, and it will be understood that the corresponding ions are conducted by the electrochemically active cell region 1350. For example, carbon dioxide may be used as fuel in the SOEC, and this fuel is reduced by the electrochemically active cell region 1350. A sweep gas can be supplied to the second fluid flow region to assist in the extraction of the products of the electrolytic reaction on the second side of the electrochemically active cell region.

[0209] A molded port feature 1324 is provided around the fluid port of the separator plate 1312. The molded port feature 1324 is provided as a plurality of elements in the form of projections extending from the base plane of the fluid volume by a distance corresponding to the height of the flange 1318, i.e., provided to have a common height with the flange 1318. This is so that when the cell unit 1300 is assembled, the molded port feature 1324, like the flange 1318, contacts the opposing surface of the metal support plate 1312. The flange and / or port feature may be provided on one or both of the metal support plate and the separator plate.

[0210] As a result, when the flange 1318 is joined to the metal support plate 1314, for example by welding, the molded port feature 1324 also comes into contact with the metal support plate 1314. The projections may have circular, square, cruciate, pentagonal, or hexagonal cross-sections. The projections may also have elliptical or irregular polygonal cross-sections. The projections are configured to transmit compressive force through the stack, which is used to compress the gasket 1370 between the cell units and seal the gasket 1370 against the contact surfaces (the second side 1315b of the cell layer 1314 and the first side 1313a of the separator plate 1312).

[0211] Furthermore, the separator plate 1312 is provided with a press-formed feature portion. This feature portion is a rib 1337 that protrudes from the second side 1313b of the separator plate (towards the cell layer of the cell unit) and forms a corresponding recess within the first side 1313b of the separator plate. The protruding portion of the rib 1337 that protrudes into the first fluid flow region contacts the cell layer of the cell unit, providing mechanical support and electrical contact throughout the cell unit. The recessed portion of the rib 1337 forms a second fluid flow region. The first side 1313a of the separator plate 1312 (specifically, its planar portion) contacts the outermost layer of the adjacent electrochemically active cell region 1350 (for example, in Figure 13B, the first side 1313a of the separator plate 1312 of the cell unit 1300 contacts the electrochemically active cell region 1350 of the adjacent cell unit). The rib 1337 extends along the length of the second side 1313b of the separator plate 1312 so as to extend beyond the edge of the electrochemically active cell region 1350 when the separator plate and the metal plate are in close proximity to each other. The rib 1337 protrudes from the separator plate 1312 toward the metal support plate 1314 of the cell unit, thereby forming a broad channel on the second side of the separator plate 1312. The opposite sides of these ribs 1337 form a concave channel on the first side of the separator plate that defines a second fluid flow region in the second fluid volume 1365. The second fluid flow region in the second fluid volume 1365 is defined between the outer surface of the electrochemically active cell region 1350 of the adjacent cell unit and the rib 1337 (the concave or recessed side). The ribs are longer than the length of the electrochemically active cell region 1350 and therefore extend beyond the edge of the electrochemically active cell region 1350, so that they can deliver and / or discharge the second fluid from the outermost layer of the electrochemically active cell region 1350 of the adjacent cell unit.

[0212] The number and cross-sectional area of ​​the ribs are configured such that the cross-sectional area of ​​the first fluid flow region is larger than the cross-sectional area of ​​the second fluid flow region. The ratio of the cross-sectional area of ​​the second flow region to the cross-sectional area of ​​the first flow region is 1:3 or less, and arbitrarily 1:10 or less.

[0213] When formed in a stack of cell units, the second side of the separator plate 1312 of the first cell unit faces the first side of the cell layer of the first cell unit, spaced apart to form a first fluid volume 1360 for the first fluid, and the first side of the separator plate of the first cell unit faces the second side of the cell layer of a second adjacent (i.e., nearby) cell unit in the stack of cell units, defining a second fluid volume 1365 between them. The first fluid volume is for the first fluid (typically a fuel such as vapor in the operation of an electrolytic cell), and the second fluid volume is for the second fluid (such as generated oxygen in the operation of an electrolytic cell). Gaskets 1370 are provided between adjacent (i.e., nearby) cell units in the stack. One gasket typically surrounds each port, and typically there are two or more, i.e., at least one inlet port to the first fluid volume and one outlet port from the first fluid volume. There may be multiple inlet ports and multiple outlet ports, each with its own corresponding gasket.

[0214] When formed in a stack of cell units, the stack is configured such that the cross-sectional area of ​​the first fluid flow region (which may be at least a portion of the first fluid volume within the planar area of ​​the electrochemically active cell region 1350) is larger than the cross-sectional area of ​​the second fluid flow region (which may be at least a portion of the second fluid volume within the planar area of ​​the electrochemically active cell region 1350). That is, the fluid volume for the fuel (e.g., steam) has a larger cross-sectional area than the second fluid volume for the product of the electrolytic reaction (e.g., oxygen for the electrochemically active cell region 1350 that conducts oxygen ions).

[0215] Each gasket 1370 (also called a "seal") performs a primary sealing function and is preferably a compressible gasket. The gasket performs its sealing function by being subjected to compressive force near the port, for example, through means to which compressive force can be applied. The gasket is sized to surround each fluid port 1322 so as to prevent a first fluid that can move through the fluid port 1322 (such as vapor in the operation of an electrolytic cell) from leaching out from between the outside of the cell unit 1300 and the gasket 1370 into the area outside the cell unit, i.e., into a second fluid volume surrounding the cell unit 1300 (such as generated oxygen for SOEC), or preventing fluid outside the fluid port from leaching in the other direction, i.e., into the fluid port. This prevents mixing of the fluid inside the cell unit 1300 with the fluid outside the cell unit 1300. The port feature portion 1324 of the separator plate contacts the cell layer of the same cell unit, transmitting compressive force through the cell unit and acting on the gasket throughout the entire stack.

[0216] The gasket can also provide electrical insulation between the first cell unit and the adjacent fluid cell unit to prevent short circuits. The gasket can be any suitable cell gasket (sealing ring), such as Thermiculite®.

[0217] The compressive force throughout the stack further acts to ensure good electrical and mechanical contact between the separator plate and the cell layer (metal support plate and / or electrochemically active cell region 1350).

[0218] Typically, fuel is supplied to a first fluid volume 1360 through two of the ports 1322 (e.g., the two ports on the right side of the diagram), flows through the first fluid flow region along the length of the cell unit, crosses the electrochemically active cell region 1350 (thus supplying the fuel to the electrochemically active cell region 1350), and the products of the electrolytic reaction (and unused fuel / unusable components) are discharged from the first fluid volume 1360 through the other two ports 1322 (the opposite ends of the cell unit, the ports on the left side of the diagram). In this case, the products of the electrolytic reaction are discharged through a second fluid flow region, and these products flow in a direction parallel or antiparallel to the first fluid flow region.

[0219] Referring to Figure 14, two exemplary electrolytic cell units 1400 are shown in exploded perspective views, along with cross-sectional views AA and BB through two electrolytic cell units in a stacked arrangement (note that the height direction of the cross-section is exaggerated for clarity). The electrolytic cell unit 1400 is similar to the cell unit 1300 in Figure 13B, except that a pattern of linear projections 1437 is provided on the side of the electrochemically active cell region 1450 adjacent to the second fluid volume 1465 in the assembled cell unit. These linear projections 1437 have apex that is higher than the outermost layer of the electrochemically active cell region 1450. This creates a second fluid flow region (i.e., between the outermost layer of the electrochemically active cell region 1450 on the side of the projections 1437 and the first side of the separator plate 1412 of the adjacent cell unit). This second fluid flow region is part of the second fluid volume 1465 for the discharge and / or delivery of the second fluid to the electrochemically active cell region 1450 (typically for the discharge of products of an electrolytic reaction). The linear projection 1437 is provided in place of the rib 1337 in Figure 13B and performs a similar function to the second side (concave side) of the rib 1337, as described above.

[0220] The linear projections 1437 may be made of a different material from the outermost layer material of the electrochemically active cell region 1450, and may be manufactured by depositing material onto the outermost layer of the electrochemically active cell region 1450 (e.g., by screen printing, inkjet printing, etc.). Alternatively, the linear projections may be made of the same material as the outermost layer material of the electrochemically active cell region 1450. This can be done by depositing additional material to form the projections, or by removing material from the outermost layer of the electrochemically active cell region 1450. Such removal can be done, for example, by etching or machining.

[0221] The linear projections 1437 are positioned parallel to the length of the cell unit (and parallel to the general direction of flow in the first fluid flow region). Thus, the second fluid flow region is parallel and / or antiparallel to the first fluid flow region, resulting in a parallel or counter-flow configuration of the cell unit. However, this is not required. The linear projections 1437 (and therefore the flow in the second fluid flow region) can have any orientation with respect to the first fluid flow region. In a preferred example, the linear projections 1437 are perpendicular to the first fluid flow region, resulting in a straight-across-direction configuration of the cell unit.

[0222] Furthermore, a plurality of dimpled protrusions 1436 are provided on the second side of the separator plate 1412, and these protrusions extend from the separator plate 1412 toward the metal support plate 1414 of the cell unit in which the separator plate is a component. These are provided in place of the rib 1337 in Figure 13B and perform a similar function to the first side (protruding side) of the rib 1337. The dimpled protrusions 1436 extend from the second side of the separator plate 1412 and contact the first side of the cell layer (in the case of Figure 14, the first side of the metal support plate 1414 opposite to the side of the metal support plate supporting the electrochemically active cell region 1450).

[0223] The dimpled projections may have a circular, square, cruciate, pentagonal, or hexagonal cross-section. The projections may also have an elliptical or irregular polygonal cross-section. The projections may have a length no more than three times their width. For this reason, the projections are also called dimples. The dimpled projections 1436 do not restrict the flow of fluid within the first fluid flow region / first fluid volume 1460. The dimpled projections 1436 are formed by press-forming (e.g., stamping or hydroforming) a metal sheet forming the separator plate 1412, resulting in the formation of convex projections on the second side 1313b and concave depressions on the first side 1313a of the separator plate.

[0224] A molded port feature similar to the molded port feature 1324 of the cell unit 1300 is provided around the fluid port 1322 of the separator plate 1412. The molded port feature 1324 and the dimpled projection 1436 are provided as multiple elements in the form of projections that extend from the plane of the separator plate by a distance corresponding to the height of the flange 1418, i.e., they are provided to have a common height with the flange 1418. This is so that when the cell unit 1400 is assembled, each of the flanges 1418, the molded port feature 1324, and the dimpled projection 1436 will contact the opposing surfaces of the cell layer (in this case, the metal support plate 1414).

[0225] Referring to Figure 15, two exemplary electrolytic cell units 1500 are shown in exploded perspective views, along with cross-sectional views AA and BB through the two electrolytic cell units in a stacked arrangement (note that the height direction of the cross-section is exaggerated for clarity). The electrolytic cell unit 1500 is similar to the cell unit 1400 in Figure 14, except that instead of linear projections 1437 for forming a second fluid flow region and a second fluid volume, discrete projections (or dimples) 1537 are provided extending upward from the surface of the electrochemically active region 1550. The discrete projections 1537, in combination with the electrochemically active cell region 1550 and the first side 1313a of the proximity separator plate, form a second fluid flow region 1365 in the same manner as described with respect to the linear projections 1437 in Figure 14. The discrete projections 1537 do not restrict the direction of fluid flow in the second fluid flow region.

[0226] The discrete projections 1537 are shown to have a circular cross-section (generally uniform in its height direction). This is not required. The projections may be tapered in height or length / width, and may have cross-sections other than circular, for example, circular, square, cruciate, pentagonal, or hexagonal. The projections may also have elliptical or irregular polygonal cross-sections. The projections may have a length no more than three times their width. In any case, the discrete projections 1537 do not restrict the fluid flow in the fluid flow region.

[0227] Discrete projections 1537 may be made of the same material as described for linear projections 1437 and manufactured in the same manner (for example, they may be deposited or printed as discrete projections, or etched / machined from layers).

[0228] The height of the discrete protrusions is lower than the height of the first fluid volume. For the reasons of conductivity and current density mentioned above, it is advantageous to reduce the second fluid volume, but if it is too small, a large pressure difference may occur between the fuel side and the air side, which may lead to inefficient operation and / or stack damage.

[0229] In one example where the height of the first fluid volume is 0.45 mm, discrete protrusions of 0.05 mm generate a relatively large pressure loss in the second fluid flow region; however, it has been found that such low heights can be acceptable in some cases.

[0230] A height of approximately 0.2 mm has been found to be a good compromise.

[0231] Therefore, the ratio of the height of the first fluid volume to the second fluid volume is greater than 1:1, preferably 10:1 to 1:1, more preferably 10:1 to 2:1, and more preferably 4:1 to 2:1.

[0232] In the example where the first volume has a height of 0.45 mm, the exemplary range is 0.01 mm to 0.45 mm, preferably 0.05 mm to 0.25 mm, more preferably 0.1 mm to 0.2 mm, or 0.1 mm to 0.15 mm, or 0.15 mm to 0.2 mm.

[0233] The same height is applied to the press-formed ribs in Figure 13B and the linear projections in Figure 14.

[0234] Furthermore, the exemplary cell unit 1500 is provided with only two fluid ports 1322. One fluid port is provided as an inlet to a first fluid volume, and the second fluid port is provided as an outlet from the first fluid volume (for supplying to and discharging from the first fluid flow region). Around the fluid ports 1322 of the separator plate 1512, molded port features similar to the molded port features 1324 of the cell unit 1300 are provided. The molded port features are provided as multiple elements in the form of protrusions extending from the plane of the separator plate 1512 by a distance corresponding to the height of the flange 1518 and the dimple 1536 (substantially similar to the dimple 1436 in Figure 14), i.e., provided to have a height common to the flange 1418 and the dimple 1536.

[0235] Although only two fluid ports 1322 are shown, other numbers of fluid ports 1322 are also possible. An example of a cell unit 1500 having four fluid ports 1322 is shown in Figure 16, which is otherwise similar to the cell unit described with respect to Figure 15.

[0236] Referring to Figure 17, two exemplary electrolytic cell units 1700 are shown in exploded perspective views, along with cross-sectional views AA and BB through the two electrolytic cell units in a stacked arrangement (note that the height direction of the cross-section is exaggerated for clarity). Cell unit 1700 is similar to cell unit 1600 in Figure 16, except that the discrete protrusions 1737b are located on the first side of the separator plate rather than on the outermost layer of the electrochemically active region. The discrete protrusions 1737b may be made of the same material as described with respect to the discrete protrusions 1537 on the outermost layer of the electrochemically active cell region and may be manufactured in the same manner. The dimples 1737a extend from the second side of the separator plate toward the first side of the cell layer (in this case, the metal support plate) and are the same as the dimples 1536 described with respect to Figure 15.

[0237] Note that Figure 17 is shown in a different perspective than that of Figures 13B to 16, so that the discrete protrusions 1737b are visible. This figure also allows visualization of multiple holes (or pores) passing through the metal support plate, which are collectively referred to herein as porous regions, and enable fluid communication between the first fluid flow region (first fluid volume) and the layer of electrochemically active cell regions closest to the metal support plate. These can be referred to as porous regions. The above porous regions are also present in Figures 13B to 16.

[0238] Referring to Figure 18, two exemplary electrolytic cell units 1800 are shown in exploded perspective views, along with cross-sectional views AA and BB through the two electrolytic cell units in a stacked arrangement (note that the height direction of the cross-section is exaggerated for clarity). Cell unit 1800 is similar to cell unit 1700 in Figure 17, except that a spacer plate 1816 is provided between the metal support plate 1814 and the separator plate 1812 instead of a flange. The spacer plate 1816 may extend to the periphery of the separator plate and / or cell layer. The spacer plate may serve to separate these plates and define a first fluid volume. If a spacer plate 1816 is provided, the separator plate 1812 may not be provided with the flange shown in cell units 1300 to 1700 in Figures 13 to 17.

[0239] When the spacer plate 1816 is in a predetermined position within the cell unit, it overlaps above / below the periphery of the separator plate 1812 and below / below the periphery of the metal support plate 1814. The central hollow portion 1817 of the spacer plate 1816 is at least above / below the electrochemically active cell region, dimpled protrusions, and discrete protrusions. The hollow central portion 1817 is further at least below the porous region (multiple small holes) provided within the metal support plate 1812, allowing the fluid in the first fluid volume to fluidly communicate with the side of the electrochemical layer closest to the metal support plate 1814. When the hollow portion 1817 of the spacer plate 1816 is sandwiched between the separator plate 1812 and the metal support plate 1814, it forms a first fuel volume between the separator plate 1812 and the metal support plate 1814. This fluid volume is typically used for fuel such as steam. The spacer plate has fluid ports similar to those provided in the metal support plate and separator plate, but the ports in the spacer plate have throats for fluid communication with the first fluid volume (i.e., similar to, and instead of, the port feature portion 1324, to allow fluid communication between the chimney formed by the aligned ports and gasket and the first fluid volume).

[0240] Referring to Figures 19A, 19B, and 20, two exemplary electrolytic cell units 1900 are shown in exploded perspective views of Figures 19A and 19B, along with cross-sectional views AA and BB of Figure 20 showing two electrolytic cell units in a stacked arrangement (note that the height direction of the cross-section is exaggerated for clarity). Cell unit 1900 is similar to cell unit 1700 of Figure 17, except that the second side of the separator plate 1912 does not have any dimpled protrusions (such as dimpled protrusions 1436) or other press-formed or molded features in the region extending at least over the electrochemically active cell region, so that the fluid flow in the first fluid volume is not obstructed, i.e., the fluid can flow freely over the second side of the separator plate 1912. That is, the region does not contain any (dimpled, e.g., press-formed) protrusions directed toward the cell layer or other components to separate the separator plate from the cell layer. Instead of such (dimpled) protrusions 1436, the separator plate is adapted to be exposed to a pressure difference between the first and second sides of the separator plate in order to maintain a separated arrangement that forms the first fluid volume. Thus, the pressure of the gas in the first fluid (fuel) volume maintains the rigidity of the cell unit. In this regard, the cell unit 1900 is adapted and functions in a similar manner to those described with respect to Figures 3 to 9.

[0241] The first side of the separator plate 1912 has discrete projections similar to those described with respect to discrete projections 1737b, discrete projections made of similar material, and discrete projections manufactured in a similar manner.

[0242] Referring to Figures 21A, 21B, and 22, two exemplary electrolytic cell units 2100 are shown in exploded perspective views of Figures 21A and 21B, along with cross-sectional views AA and BB of Figure 22 showing two electrolytic cell units in a stacked arrangement (note that the height direction of the cross-section is exaggerated for clarity). Cell unit 2100 is similar to cell unit 1700 in Figure 17, except that the only pressed feature of the separator plate 2112 is the flange. Discrete protrusions 2137b are provided on the first side of the separator plate and are similar to the discrete protrusions 1737b in Figure 17 (i.e., they form a second fluid flow region).

[0243] Furthermore, unlike cell unit 1900, the second side of the separator plate 2112 of cell unit 2100 has discrete projections 2137a extending toward the metal support plate of the same cell unit. The discrete projections 2137a act to maintain the separation arrangement between the first side of the separator plate 2112 and the metal support plate, thereby forming a first fluid flow region within the first fluid volume. The discrete projections 2137a on the second side of the separator plate 2112 are similar in form, material, and method of manufacture to the discrete projections 2137b on the first side of the separator plate 2112. The discrete projections 2137a on the second side of the separator plate 2112 are provided in place of the aforementioned dimpled projections 1436, 1536, eliminating the need for press working. Similarly, discrete projections 2137c are provided around port 2122 instead of press-formed port feature 1324, but they function in a similar manner, allowing the fluid to flow into / out of the fluid port 2122 from a first fluid volume.

[0244] Figures 23A, 23B, and 23C show a cell unit 2300 similar to those in Figures 21A, 21B, and 22, but in which the first fluid volume is surrounded by a spacer plate 2316 (similar to the spacer plate in Figures 8, 9, and 18) instead of a flange formed on the separator plate 2312.

[0245] Figures 24A to 24F are various simplified cross-sectional views corresponding to the previous figures. The correspondences are shown in Table 1 below. It will be understood that the flanged periphery shown in Figures 24A to 24E, Figure 24G and Figure 24H can be used in place of the spacer 1816 shown in Figure 24F, and the spacer shown in Figure 24F can be used in place of the flanged periphery shown in Figures 24A to 24E, Figure 24G and Figure 24H. In some cases, the flanged periphery may be less expensive than using a spacer (especially if the press-formed or molded features are located within the separator plate, as both can be molded or press-formed in the same step). In some cases, this may not be the case, and the reliability of a cell unit using a spacer may be improved compared to a cell unit having a flanged periphery (whose press-forming can generate stress).

[0246] Figures 24G and 24H are not corresponding to the previous figures. Both utilize “porous layers” 2437, 2436 to form a second fluid flow region (and second fluid volume) instead of any formations (discrete protrusions, linear protrusions, pressed ribs) on the electrochemically active cell region or interconnect. This layer can be applied (e.g., coated, bonded, and / or supported) to the top of the electrochemically active cell region (porous layer 2437 in Figure 24F) or the bottom of the interconnect (porous layer 2436 in Figure 24G).

[0247] Such porous layers allow the passage of a second fluid (e.g., an oxidizing agent for SOEC or hydrogen for PEM electrolytic cells) and are conductive.

[0248] In some examples, the porous material is an additional ceramic layer, which is optionally treated to increase its porosity. Such treatments include sintering, or applying additives that burn away leaving voids, or agents that "foam" the ceramic.

[0249] In another example, the porous layer is a metal mesh, preferably metal mesh strips. Steel is a suitable material because it can withstand the temperature inside the electrolytic cell and can be easily made into a mesh.

[0250] The thickness of the porous layer may be similar to the thickness of the characteristic parts described above (discrete protrusions, linear protrusions, press-formed or formed ribs), i.e., it may be 0.01 mm to 0.45 mm, preferably 0.05 mm to 0.25 mm, more preferably 0.1 mm to 0.2 mm, or 0.1 mm to 0.15 mm or 0.15 mm to 0.2 mm.

[0251] The porous layer in Figure 24G or Figure 24H may be used with a separator plate such as in Figure 24E or Figure 24F, in which the press-formed / molded ribs 1337, dimples 1436, or discrete dimples 2137a are absent.

[0252] In the case where the cell units described with respect to Figures 13 to 24 are electrolytic cell units (or arranged to form a stack of electrolytic cell units), and in the specific example where the cell units are solid oxide electrolytic cell units (or a stack thereof), the fuel (i.e., cathode inlet gas, e.g., H2O, typically in vapor form) enters a first fluid volume (fuel volume) between the separator plate and the cell layer (e.g., metal support plate) via the inlet port. In one example, a SOEC having H2O as the fuel (first fluid supplied to the first fluid volume) combines with electrons flowing to the cathode electrode of the electrochemically active layer of the cell unit to produce oxygen ions and hydrogen gas. The hydrogen gas is discharged from the first fluid volume via the cathode outlet. The oxygen ions move through the solid oxide electrolyte toward the anode (air side) of the electrochemically active layer. At the anode, the oxygen ions combine with electrons by reduction to produce oxygen molecules, which are then discharged from the cell unit at the anode outlet. The oxidation-reduction reactions that occur in a solid oxide electrolytic cell are as follows: [ka] [ka]

[0253] Simultaneously, to aid in the extraction of species generated on the second side of the electrochemically active cell region, a sweep gas (e.g., an oxidizing agent such as air or oxygen (i.e., anode inlet gas)) can be passed through the anode inlet of the cell unit and flow through the second fluid flow region (either the separator plate or the metal support plate side).

[0254] The fuel and electrochemically generated oxygen (and any additional sweep gas) may flow in a parallel flow configuration, such that the fuel and oxidizer flow in the same direction across each side of the cell unit. Alternatively, the fuel and electrochemically generated oxygen (and any additional sweep gas) may flow in a counterflow or direct-to-alternating configuration.

[0255] If cell units 1300, 1400, 1500, 1600, 1700, 1800, and 1900 are electrolytic cell units, the fuel may be supplied to the first fluid volume of the electrolytic cell unit at a pressure different from the pressure experienced in the second fluid volume, thereby creating a pressure difference between the first and second sides of the separator plate (and, in practice, the cell layer). By creating a pressure difference between the first and second sides, the separation between the separator plate (the second side) and the cell layer (the first side) (the first side of the metal support plate) can be controlled. For example, by using a higher pressure in the first fluid volume than in the second fluid volume, the separation can be maintained or increased, thereby forming and / or maintaining the first fluid volume.

[0256] To enable the separation between separator plates 1312, 1412, 1512, 1612, 1712, 1812, 1912 and the cell layers (metal support plates 1314, 1414, 1514, 1614, 1714, 1814, 1914) to be maintained or increased by creating a pressure difference between the first and second sides, the separator plates may be fitted or configured to flex when exposed to a pressure difference. For example, when exposed to a pressure difference, the separator plates may flex away from the cell layers (or metal support plates) of the cell units (and toward adjacent cell units) as the pressure difference increases; that is, the separator plates may be fitted to flex away from the cell layers (or metal support plates) when exposed to a pressure difference as a positive function of the pressure difference. Adjusting the pressure difference can adjust the contact resistance between the first side of the separator plate and the electrochemically active cell region of the adjacent cell unit (in particular, the higher the pressure in the first fluid volume relative to the second fluid volume, the greater the contact force between the separator plate and the electrochemically active cell region of the adjacent cell unit, thereby reducing the contact resistance between them). In electrolytic operation, the fuel can typically be vapor produced at relatively high pressure, and therefore the use of such high-pressure vapor is advantageous. Furthermore, the second fluid flow region / second fluid volume can be occupied solely by the products of the electrolytic reaction (or its products and sweep gas), the products of which are at a lower pressure than vapor and have lower volumetric flow requirements than the first fluid volume.

[0257] Figure 25 shows a simplified cell unit 2500 similar to those in Figures 13B and 24A, except that the separator plate 2512 is provided with both ribs 2538 and projections 1337. In this case, the ribs connect adjacent projections. Figure 25A is a simplified plan view showing the first side of the separator plate 2512 of the cell unit 2500. Figure 25B is a cross-sectional view of two cell units 2500 along line AA in Figure 25a. Figure 25C is a cross-sectional view of two cell units 2500 along line BB in Figure 25a. The projections 1337 protrude toward the first side of the cell layer 2514 on the second side of the separator plate 2512 and contact the first side of the cell layer 2514 (specifically, contact the first side of the support plate). The ribs 2538 protrude toward the first side of the cell layer on the second side of the separator plate. That is, the projections 1337 and ribs 2538 form a convex surface on the second side of the separator plate and a concave surface on the first side of the separator plate. However, the ribs 2538 do not contact the first side of the cell layer 2514. As a result, the projections 1337 define the height of the first fluid flow region 1360, but the ribs 2538 do not restrict the fluid flow within the first fluid flow region. On the first side of the separator plate, the ribs 2538 fluid-connect the projections 1337 (each concave side) to form a second fluid flow region 1365. Each projection 1337 is connected to its nearest adjacent projection by the corresponding rib 2538, thereby forming a network of interconnected ribs. The network of interconnected ribs may include end ribs 2538a, 2538b, which are fluid-connected to the projections 1337 at only one end. At their opposing ends, the end ribs 2538a and 2538b extend beyond the ends of the electrochemically active cell region 1350. As a result, the second fluid can flow through the end ribs 2538a and 2538b, the rib 2538, and the projection 1337, from or to the second side of the cell layer, within the second fluid flow region defined by the network of interconnected ribs. Figure 25 shows each projection connected to its nearest adjacent projection by a corresponding rib (in this case, each projection has four nearest adjacent projections and one rib for each of its nearest adjacent projections).Other configurations may be used. For example, the ribs may be aligned with the length or width direction of the cell unit and connect the dimples in that direction (in the simplified diagram of FIG. 25, three interconnecting ribs crossing the cell unit from left to right may be formed). In this case, both the ribs 2538 (including the end ribs) and the protrusions 1337 are pressed or formed within the separator plate, and the pressing / molding may be completed in the same step as forming other features (fluid ports, flanged peripheries) within the separator plate.

[0258] The above exemplary embodiments disclose various configurations for forming a second fluid volume having a cross-sectional area smaller than the first fluid volume. Generally, this can be achieved by one or more of the features of the interconnect, the features of the electrochemically active cell region, the presence of the separator plate, or the pressure difference.

[0259] The following table summarizes the similarities / differences in the methods of forming the second volume.

Table 1

[0260] The manufacturing method of any of the cell units described with respect to FIGS. 13 to 25 includes several steps / operations, as illustrated with respect to FIG. 26. This method includes the following steps.

[0261] In step 2610, a separator plate having a first side and a second side is prepared. The separator plate can be manufactured by cutting or stamping. The separator plate can be, for example, a non-porous planar metal sheet or any other non-porous planar sheet and serves to separate one cell unit in the stack from adjacent cell units. The separator plate can be provided with dimpled protrusions and / or flanges extending from the plane of the separator plate, which can be provided by pressing / molding in the same step as the cutting / stamping.

[0262] Step 2610 preferably further includes the step of preparing a separator plate having a flange. The flange extends from the main plane of the separator plate. The flange forms a concave surface (and a convex surface on the outer surface) within the separator plate. This concave surface forms a first fluid volume 1360, 1460, 1560, 1660, 1760, 1960 within this cell unit during assembly of the cell unit. The flange can be produced by pressing the separator plate or the metal support plate (of the cell layer) respectively.

[0263] Instead of a flange, in step 2630, a spacer plate 1816 can be provided and sandwiched between the separator plate 1812 and the metal support plate 1814 to form a first fluid volume therebetween.

[0264] Simultaneously with cutting or stamping the separator plate (to form ports, shape it, and / or create a flanged perimeter), the separator plate can also be provided with molded port features 1324, 1324, 1324, and / or ribs 1377, and / or dimpled protrusions 1436, 1536, 1737a.

[0265] Furthermore, where appropriate, discrete protrusions 1737b, 1937, 2137b may be provided on the first side of the separator plate, and / or discrete protrusion 2137a may be provided on the second side of the separator plate. The discrete protrusions may be provided after the cutting / stamping / pressing / forming steps to eliminate the possibility of damage during those steps, or they may be provided before those steps so that the discrete protrusions are provided on a planar sheet. The discrete protrusions may be manufactured by first depositing a homogeneous layer of material onto the separator plate, and then removing the excess material by etching or machining (after applying a suitable mask) to form the discrete protrusions, or by screen printing or inkjet printing of the discrete protrusions. The discrete protrusions may be made of ceramic or other materials.

[0266] A separator plate may be provided with a second fluid flow region on a second side of the separator plate. Such a fluid flow region is configured to deliver and control the flow of a second fluid to the outermost layer of the electrochemically active region. The step of providing the second fluid flow region may include printing or depositing material to form a fluid flow region on the first side of the separator plate. Alternatively, or additionally, the step of providing the second fluid flow region may include printing or depositing a homogeneous layer on the first side of the separator plate and selectively removing material from that layer to form a second fluid flow region. The selective removal step may include etching (after applying a suitable mask) or otherwise machining the material to form the second fluid flow region.

[0267] In step 2620, a cell layer is prepared. The cell layer comprises an electrochemically active cell region, the electrochemically active cell region having a first side and a second side. This may include the step of preparing a metal support plate having an electrochemically active region comprising an anode, a cathode, and an electrolyte positioned between the anode and the cathode. The metal support plate has a first side and a second side and typically has a central porous region which may be formed by providing a plurality of through holes from the first side to the second side of the metal support plate. The step of preparing the cell layer may include, for example, the step of coating an electrochemically active cell region onto a planar metal sheet by depositing or printing the electrochemically active cell region onto the metal support plate to form a metal-supported cell layer. The porous region provides fluid communication from the first side to the electrode supported on its second side by the metal support plate. Alternatively, the cell layer may be self-supporting. In such cases, the cell layer has an anode-supported, electrolyte-supported, or cathode-supported structure.

[0268] Step 2620 may further include providing a second fluid flow region within or on an electrochemically active cell region (a cell layer that can be supported by a metal support plate). Such a fluid flow region is configured to deliver and control a second fluid flow to the outermost layer of the electrochemically active cell region. Providing the second fluid flow region may include printing or depositing material to form a fluid flow region on the outermost layer of the electrochemically active cell region. The printing or depositing step may create discrete protrusions and / or ribs in a single step. Alternatively or additionally, the printing or depositing step may be printing or depositing a homogeneous layer, and the step providing the second fluid flow region further includes selectively removing material from that layer to form the second fluid flow region. Alternatively or additionally, the step providing the second fluid flow region may include selectively removing material from the outermost layer of the electrochemically active region to form the second fluid flow region. The above selective removal step may include etching the material (after applying a suitable mask) or otherwise machining it to form a second fluid flow region.

[0269] The second fluid flow region may take the form of ribs or discrete protrusions, as described above, and may be formed from ceramic or other materials.

[0270] Steps 2610 and 2620 further include providing a plurality of fluid ports 1332, 1432, 1532, 1632, 1732, 1832, 1932 in both the separator plate and the metal support plate (and optionally in the spacer plate having a throat) to allow the flow of fluid (such as steam) through the cell units (and ultimately through the stack of cell units) to supply fuel to the first fluid volume of each cell unit.

[0271] In step 2630, the separator plate and the cell layer are superimposed (together with a spacer plate between them, or with at least one of the separator plate and the cell layer having a flange) such that the second side of the separator plate overlaps the first side of the cell layer and faces the first side of the cell layer, and the cell layer and / or separator plate form a first fluid flow region for the delivery of fuel to the first side of the electrochemically active region and a second fluid flow region for the discharge of fluid from the second side of the electrochemically active region, the cross-sectional area of ​​the second fluid flow region being smaller than the cross-sectional area of ​​the first fluid flow region. In step 2630, the separator plate and the cell layer are superimposed such that when the cell units are arranged in a stack configuration, the second fluid flow region is oriented away from the first fluid volume toward the adjacent cell unit. The second fluid flow region is not made up of dimpled protrusions or ribs formed or pressed within the separator plate.

[0272] In step 2630, the separator plate and the cell layer may be superimposed in a separated manner such that a first fluid flow region is formed between them. The separator plate may be configured not to have dimpled protrusions projecting from its second side into the first fluid volume / towards the cell layer. That is, there exists a continuous region extending at least across the electrochemically active cell region that does not include any protrusions directed toward the cell layer (metal support plate) / outward from the second side of the separator plate. Furthermore, this region does not include any other components configured to resist stack compressive forces and transmit such forces to protrusions connecting adjacent cell units. Thus, within the first fluid volume, there are no components between the separator plate and the cell layer to help physically separate them from each other (especially during operation).

[0273] Once formed, the cross-sectional area of ​​the first fluid volume (also known as the first fluid flow region) of the electrolytic cell unit is larger than the cross-sectional area of ​​the second fluid volume (also known as the second fluid flow region).

[0274] In step 2630, the separator plate and the metal support plate may be directly joined (and sealed) by the flange described above to form a first fluid volume between them. The separator plate and the metal support plate may optionally be directly joined by welding.

[0275] In an alternative configuration without flanges, a spacer plate is provided and sandwiched between the separator plate and the metal support plate so as to form a first fluid volume between the separator plate and the metal support plate, and in step 2630, the three plates are sealed and fixed to each other, for example by welding their periphery.

[0276] The method may further include the step of preparing a plurality of cell units in accordance with the above, and forming a stack of electrolytic cell units by stacking a second cell unit on top of a first cell unit (and so on, thereby forming a stack having a given number of cell units).

[0277] As described above, each cell unit may include a separator plate and a cell layer, the second side of the separator plate overlapping the first side of the cell layer in a separated position and facing the first side of the cell layer (thus forming a first fluid flow region). In such a case, the step of superimposing a second cell unit on a first cell unit includes the step of superimposing the first side of the separator plate of the second cell unit facing the second side of the cell layer of the first cell unit (thus forming a second fluid flow region).

[0278] Alternatively, as described above, each cell unit may include a separator plate and a cell layer, with the first side of the separator plate overlapping the second side of the cell layer in a separated position and facing the second side of the cell layer (thus forming a second fluid flow region). In such a case, the step of superimposing the second cell unit onto the first cell unit includes the step of superimposing the second side of the separator plate of the first cell unit facing the first side of the cell layer of the second cell unit (thus forming a first fluid flow region).

[0279] When forming the stack, multiple gaskets are placed between adjacent cell units, with one gasket corresponding to each of the multiple fluid ports of the cell unit.

[0280] Next, a method for operating a stack of electrolytic cell units will be described. The method includes the step of supplying fuel (e.g., fuel for electrolysis) to a first fluid flow region, the first fluid flow region being a region for delivering fuel to a first side of an electrochemically active cell region, and the first fluid flow region being defined by the separation arrangement between the first side of the electrochemically active cell region and a second side of a proximity separator plate. The method further includes the step of discharging a second fluid (e.g., products of an electrolytic reaction) from a second fluid flow region. The second fluid flow region is a region for discharging fluid from a second side of an electrochemically active cell region. The second fluid flow region may be defined between a second side of a cell layer and a first side of a proximity separator plate. The method may further include the step of controlling the flow rate of the fluid in the first fluid flow region to at least twice the flow rate of the fluid in the second fluid flow region.

[0281] A sweep gas may be supplied to a second fluid flow region, in which case the control step is further configured to control the flow rate of the fuel supplied to the first fluid flow region to at least three times, and optionally five times, the flow rate of the sweep gas supplied to the second fluid flow region.

[0282] The method may further include adjusting (as part of, or alternatively to, the controlling step) the pressure difference between the first fluid flow region and the second fluid flow region in order to maintain a spaced-apart arrangement between the cell layer forming the first fluid flow region (and the first fluid volume) and the separator plate.

[0283] The pressure difference between the first fluid flow region (first fluid volume) and the second fluid flow region (second fluid volume) may be adjusted to be in the range of 50 mbar to 2 bar, preferably 100 mbar to 1.5 bar, more preferably 200 mbar to 800 mbar. The pressure difference between the first fluid volume and the second fluid volume may be adjusted to reduce the electrical contact resistance between the separator plate and the electrochemically active cell region of the second adjacent cell unit in the stack of cell units.

[0284] The present invention is not limited only to the above embodiments, and other embodiments will be readily apparent to those skilled in the art without departing from the scope of the appended claims.

[0285] These and other features of the present invention have been described above merely as examples. Detailed modifications may be made to the present invention within the scope of the claims.

Claims

1. A cell layer having an electrochemically active cell region, comprising a cell layer having a first side and a second side, A first fluid flow region for delivering fuel to the first side of the cell layer, A second fluid flow region for discharging fluid from the second side of the cell layer, wherein the cross-sectional area of ​​the second fluid flow region is smaller than the cross-sectional area of ​​the first fluid flow region. An electrolytic cell unit equipped with the following features.

2. The electrolytic cell unit according to claim 1, further comprising a separator plate having a first side and a second side, wherein the second side of the separator plate overlaps the first side of the cell layer and is positioned apart from the first side of the cell layer to form a first fluid flow region.

3. The electrolytic cell unit according to claim 2, wherein the second fluid flow region is defined by the region between the second side of the cell layer and the first side of the separator plate of the proximity electrolytic cell unit.

4. The electrolytic cell unit according to claim 1, further comprising a separator plate having a first side and a second side, wherein the first side of the separator plate overlaps the second side of the cell layer and is positioned apart from the second side of the cell layer to form a second fluid flow region.

5. The electrolytic cell unit according to claim 4, wherein the first fluid flow region is defined by the region between the first side of the cell layer and the second side of the separator plate of the proximity electrolytic cell unit.

6. The electrolytic cell unit according to any one of claims 2 to 5, wherein the second fluid flow region is defined by the topology of the first side layer of the separator plate.

7. The electrolytic cell unit according to any one of claims 2 to 6, wherein the first side of the separator plate comprises a feature portion deposited or printed thereon to form the second fluid flow region.

8. The electrolytic cell unit according to any one of claims 2 to 6, wherein the first side of the separator plate is provided with a feature portion formed in the layer above it to form the second fluid flow region.

9. The aforementioned feature part is, A plurality of ribs extending from the second side of the separator toward the first side of the cell layer, A plurality of discrete protrusions extending from the second side of the separator toward the first side of the cell layer, or Porous layer The electrolytic cell unit according to claim 7 or claim 8, comprising at least one of the following.

10. The electrolytic cell unit according to any one of claims 2 to 9, wherein the separator plate has a region that overlaps at least a portion of the planar electrochemically active cell region, and the region does not have press-formed or molded protrusions oriented away from the first side of the cell layer.

11. The electrolytic cell unit according to any one of claims 2 to 10, wherein the separator plate has a region that overlaps at least a portion of the electrochemically active cell region, and the region is provided with a plurality of pressed or molded protrusions directed toward the first side of the cell layer to form the first fluid flow region, and these pressed or molded protrusions extend outward from the second side of the separator plate, thereby forming a convex protrusion on the second side of the separator plate and a concave recess on the first side of the separator plate.

12. The electrolytic cell unit according to any one of claims 2 to 5, wherein the separator plate is provided with a plurality of press-formed or molded ribs extending from the second side of the separator plate toward the first side of the cell layer to form the first fluid flow region, and the corresponding concave side of each rib forms a channel toward the first side of the separator plate to form the second fluid flow region.

13. The electrolytic cell unit according to claim 12, wherein the separator plate has a region that overlaps at least a portion of the electrochemically active cell region, and the region is provided with a plurality of press-formed or molded protrusions directed toward the first side of the cell layer, and the concave side of each rib fluid-connects the protrusions, thereby the rib and the protrusions forming the second fluid flow region.

14. The electrolytic cell unit according to claim 13, wherein the projection is adapted to contact the first side of the cell layer, and the rib is adapted not to contact the first side of the cell layer.

15. The electrolytic cell unit according to any one of claims 2 to 14, wherein the separator plate has a region that extends at least over the electrochemically active cell region, and the region does not include any projections directed toward the cell layer or other components for separating the separator plate from the cell layer.

16. The electrolytic cell unit according to claim 15, wherein the separator plate is adapted to be exposed to a pressure difference between the first side and the second side of the separator plate in order to maintain the separated arrangement that forms the first fluid flow region.

17. The electrolytic cell unit according to any one of claims 2 to 10, wherein the first fluid flow region is defined by the topology of the second side layer of the separator plate.

18. The electrolytic cell unit according to claim 17, wherein the second side of the separator plate comprises a feature portion deposited thereon to form the first fluid flow region.

19. The electrolytic cell unit according to claim 17, wherein the second side of the separator plate comprises a feature portion formed therein to form the second fluid flow region.

20. The aforementioned feature part is, A plurality of ribs extending from the second side of the separator toward the first side of the cell layer, A plurality of discrete protrusions extending from the second side of the separator toward the first side of the cell layer, or Porous layer The electrolytic cell unit according to claim 18 or claim 19, comprising at least one of the above.

21. The electrolytic cell unit according to any one of claims 1 to 5, wherein the second fluid flow region is defined by the topology of the second side layer of the cell layer.

22. The electrolytic cell unit according to claim 21, wherein the topology of the layer on the second side of the cell layer comprises a feature deposited thereon to form the second fluid flow region.

23. The electrolytic cell unit according to claim 21, wherein the topology of the second side of the cell layer comprises a feature formed therein to form the second fluid flow region.

24. The aforementioned feature part is, The plurality of ribs on the second side of the cell layer, or Multiple discrete protrusions on the second side of the cell layer The electrolytic cell unit according to claim 22 or claim 23, comprising at least one of the above.

25. The electrolytic cell unit according to claim 22, wherein the aforementioned feature portion comprises a porous layer.

26. The electrolytic cell unit according to any one of claims 1 to 25, wherein the ratio of the cross-sectional area of ​​the second flow region to the cross-sectional area of ​​the first flow region is 1:3 or less, and arbitrarily 1:10 or less.

27. The electrolytic cell unit according to any one of claims 1 to 26, wherein the height of the second fluid flow region is lower than the height of the first fluid flow region.

28. The electrolytic cell unit according to claim 27, wherein the height of the second fluid flow region is at least one-third, preferably at least one-tenth, of the height of the first fluid flow region.

29. The electrolytic cell unit according to any one of claims 1 to 28, wherein the electrolytic cell unit is adapted such that the ratio of the fluid flow rate in the second fluid flow region to the fluid flow rate in the first fluid flow region is 1:3 or more, and optionally 1:10 or more.

30. The electrochemically active cell region comprises an oxygen ion conductive electrolyte, and the second fluid flow region is a region for discharging oxygen from the second side of the cell layer, according to any one of claims 1 to 29.

31. The electrolytic cell unit according to any one of claims 1 to 30, wherein the first side of the cell layer is the cathode of the electrochemically active cell region, and / or the second side of the cell layer is the anode of the electrochemically active cell region.

32. The electrolytic cell unit according to any one of claims 1 to 31, wherein the cell layer is a metal-supported cell layer comprising the electrochemically active cell region supported by a metal support plate.

33. The electrolytic cell unit according to claim 32, wherein one or both of the metal support plate and the separator plate are provided with flanges on the periphery of one or each plate, and the electrolytic cell unit is sealed around the flanges by welding the two plates together so as to surround either the first fluid flow region or the second fluid flow region.

34. The electrolytic cell unit according to claim 32, further comprising a spacer plate, the spacer plate being positioned between the metal support plate and the separator plate, and the electrolytic cell unit being sealed at the periphery of the plate so as to surround either the first fluid flow region or the second fluid flow region.

35. A metal support plate having a first side and a second side, wherein the second side supports an electrochemically active cell region, A separator plate having a first side and a second side, wherein the second side of the separator plate overlaps the first side of the metal support plate and faces the first side of the metal support plate in a manner that is spaced apart to form a first fluid volume of a first fluid, and An electrolytic cell unit comprising, The separator plate has a region that overlaps at least a portion (or optionally, the entire) of the planar electrochemically active cell region, and that region does not have any protrusions directed away from the metal support plate. The electrolytic cell unit comprises a fluid flow region for a second fluid, and the fluid flow region is The outermost layer of the electrochemically active cell region (the fluid flow region is the region for discharging the second fluid from the outermost layer of the electrochemically active cell region), and The first side of the separator plate (where the fluid flow region is the region for delivering and / or discharging the second fluid to the outermost layer of the electrochemically active cell region of the proximity electrolytic cell unit) An electrolytic cell unit that forms part of one or both of the above.

36. A kit of components comprising two or more electrolytic cell units according to any one of claims 2 to 35, adapted to be stackable.

37. An electrolytic cell stack comprising a plurality of electrolytic cell units according to any one of claims 2 to 35, wherein the electrolytic cell units are stacked on top of each other, and adjacent electrolytic cell units are electrically connected by the fluid flow region between them.

38. A method for manufacturing an electrolytic cell unit, The steps include preparing a separator plate having a first side and a second side, The steps include: preparing a cell layer having an electrochemically active cell region and having a first side and a second side; A step of overlapping the separator plate and the cell layer such that the second side of the separator plate overlaps the first side of the cell layer and faces the first side of the cell layer, wherein the cell layer and / or the separator plate form a first fluid flow region for delivering fuel to the first side of the cell layer and a second fluid flow region for discharging fluid from the second side of the cell layer, and the cross-sectional area of ​​the second fluid flow region is smaller than the cross-sectional area of ​​the first fluid flow region. A manufacturing method that includes this.

39. The process further includes the step of processing at least one of the separator plate and the cell layer to form the second fluid flow region, wherein the second fluid flow region is The material forming the second fluid flow region is The outermost layer of the electrochemically active cell region (the second fluid flow region is a region for discharging fluid from the outermost layer of the electrochemically active cell region), and One side of the separator plate (where the second fluid flow region is the region for discharging fluid from the outermost layer of the electrochemically active cell region of the proximity electrolytic cell unit) By printing or depositing on one or both of them, or By patterning the outermost layer of the electrochemically active cell region (the second fluid flow region is the region for discharging fluid from the outermost layer of the electrochemically active cell region) The method according to claim 38, which is formed.

40. The method according to claim 38 or 39, further comprising the step of preparing the cell layer by providing a metal support plate that supports the electrochemically active cell region, wherein the step of stacking the separator plate and the cell layer further comprises the step of stacking the separator plate and the metal support plate, and optionally the step of directly joining the metal support plate and the separator plate at their peripheral edges.

41. A method for operating an electrolytic cell unit, A step of supplying fuel to a first fluid flow region for delivering fuel to a first side of an electrochemically active cell region, The steps include: discharging fluid from a second fluid flow region for discharging fluid from the second side of the electrochemically active cell region; The steps include controlling the fluid flow rate in the first fluid flow region to at least twice the fluid flow rate in the second fluid flow region. Driving methods, including those mentioned above.

42. The method according to claim 41, further comprising the step of supplying sweep gas to the second fluid flow region, wherein the controlling step is further configured to control the flow rate of fuel supplied to the first fluid flow region to at least three times, and optionally five times, the flow rate of sweep gas supplied to the second fluid flow region.

43. The method according to claim 41 or 42, wherein the controlling step is further configured to adjust the pressure difference between the first fluid flow region and the second fluid flow region in order to maintain the separation arrangement between the cell layer forming the first fluid volume and the separator plate.

44. The method according to claim 43, wherein the pressure difference between the first fluid flow region and the second fluid flow region is adjusted to be in the range of 50 mbar to 2 bar, preferably 100 mbar to 1.5 bar, and more preferably 200 mbar to 800 mbar.

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