Electrochemical cell assembly

Abstract

The invention relates to an electrochemical cell assembly, comprising a stack of cell units, wherein each cell unit has a periphery and a central portion surrounded by the periphery, the periphery has a first flange portion (90-1) and an opposite second flange portion (90-2), the flange portions of adjacent cell units overlie one another and are separated by a gap (88-1, 88-2), wherein between two adjacent cell units, there is provided a fluid flow path comprising an inner flow path between the central portions of adjacent cell units and an outer flow through said gaps, and a flow restriction device (112) comprising at least one flow restriction member (114-1, 114-2), said flow restriction device being configured to reduce or prevent fluid flow along the outer flow path.

Description

[0001] Description

[0002] Title

[0003] [Electrochemical cell assembly]

[0004] State of the Art

[0005] The invention relates to the field of electrochemical cell stacks, in particular, fuel cell stacks and electrolyser cell stacks. More specifically, the invention relates to an electrochemical cell assembly.

[0006] Fuel cells and electrolyser cells are examples of electrochemical cells. Fuel cells are energy conversion devices that allow for conversion of electrochemical fuel (e.g. H2) to electricity. Electrolyser cells may be considered fuels cells running in reverse mode, i.e. using electricity to decompose a compound into its constituent parts, for example water into hydrogen or oxygen. Reversible cells are capable of operating in both modes. Such electrochemical cells typically comprise electrochemically active layers that may be configured to allow for conversion of electrochemical fuel to electricity (fuel cells) or for decomposing a compound into its constituent parts using electricity (electrolyser cells).

[0007] The present invention specifically relates to solid oxide cells (SOCs). Such solid oxide cells (SOCs) typically comprise an electrolyte layer formed from a solid oxide, e.g. from Yttria-stabilized zirconia (YSZ), Gadolinia-doped Ceria, or Cerium Gadolinium Oxide (CGO). SOCs can be run as solid oxide fuel cell (SOFC) or as solid oxide electrolyser cell (SOEC).

[0008] As described, for example, in WO 2020 / 126486 A1 , such cell units typically have a periphery and a central portion surrounded by the periphery, wherein the central portion carries the electrochemically active layers over a porous region. The periphery may have flange portions on part or all of its extent, said flange portions, for example, forming a weld area for joining a support plate and an interconnector plate of the cell unit. To supply fuel to the cell units, the cell units may each have at least one fluid port, said fluid ports being in communication with the electrochemical layers via the porous region. Typically, multiple of such cell units are stacked upon one another to form a “stack” of cell units (also referred to as ‘cell repeat units’). Said stack is commonly arranged between two end plates provided on opposite sides of the stack, thus forming an electrochemical cell assembly. The stack may be surrounded by a housing, said housing enclosing a fluid volume around the stack of cell units. The cell units define a fluid flow path between adjacent cell units for the fluid to flow to the electrochemically active layers.

[0009] It is an object of the present invention to increase performance and stability of an electrochemical cell assembly.

[0010] Description of the Invention

[0011] According to the invention, there is provided an electrochemical cell assembly according to claim 1. Preferably, the electrochemical cell assembly is a fuel cell assembly or an electrolysis cell assembly. The electrochemical cell assembly comprises a stack of cell units comprising a plurality of cell units that are stacked upon one another along a stacking direction. Preferably, the electrochemical cell assembly comprises a first end plate, a second end plate, and a stack of cell units arranged, preferably held in compression, between said first end plate and said second end plate. The first end plate may be a base plate of the electrochemical cell assembly. The second end plate may be a top plate of the electrochemical cell assembly. Each cell unit extends, preferably in a cell plane, perpendicular to the stacking direction in a first direction, preferably longitudinal direction, and in a second direction, preferably width direction, perpendicular to the first direction. Each cell unit has a periphery and a central portion surrounded by the periphery. The periphery preferably defines an external perimeter of the cell units in the cell plane. The central portion preferably comprises, e.g. carries, electrochemically active layers. Thus, the central portion may form an active area of the cell units. The periphery has two opposed flange portions (also referred to as flanged perimeter features), that is a first flange portion and an opposite second flange portion. The first and second flange portions extend parallel to each other, each in the first direction. The central portion, and thus the electrochemically active layers, is located between said first flange portion and said second flange portion. The flange portions of adjacent cell units overlie one another and are separated from each other in stacking direction by a respective gap. That is, the first flange portions of adjacent cell units overlie one another and are separated from each other in stacking direction by a first gap and the second flange portions of adjacent cell units overlie one another and are separated from each other in stacking direction by a second gap. Preferably, the flange portions of adjacent cell units align with one another. The cell units define a respective fluid flow path between adjacent cell units for first fluid to flow in the first direction, preferably from a fluid inlet port to a fluid outlet port of the electrochemical cell assembly. Thus, the cell units are configured such that between two adjacent cell units there is provided a fluid flow path for first fluid to flow in the first direction, preferably from a fluid inlet port to a fluid outlet port of the electrochemical cell assembly. Preferably, the cell units define fluid passageways between adjacent cell units for first fluid to flow in the first direction. The fluid flow path between adjacent cell units comprises an inner flow path between the central portions of adjacent cell units, in particular over the electrochemically active layers. The fluid flow path between adjacent cell units further comprises an outer flow path through the gaps formed between the flange portions of adjacent cell units. Thus, the outer flow path comprises a first partial outer flow path through the first gap between the first flange portions of adjacent cell units and a second partial outer flow path through the second gap between the second flange portions of adjacent cell units. The outer fluid flow path forms a fluid bypass for first fluid to bypass the central portion carrying the electrochemically active layers. Thus, the gaps form fluid bypass gaps for fluid to bypass the central portion. According to the invention, there is provided a flow restriction device, preferably fluid blocking device, between adjacent cell units, said flow restriction device being configured to, preferably selectively, reduce or prevent, in particular block, fluid flow along the outer flow path, i.e. through either or both gaps between the flange portions of adjacent cell units. The flow restriction device comprises at least one, i.e. one or more, flow restriction member, preferably fluid blocking member, said at least one flow restriction member preferably being located between the flange portions of adjacent cell units.

[0012] The proposed configuration allows for increased performance of the electrochemical cell assembly. Specifically, reducing or blocking fluid flow between the (electrochemically inactive) flange portions of the cell units helps to guide and, thus, increase fluid flow to the active areas of the cell units, i.e. the central portions carrying the electrochemically active layers, thus ensuring sufficient and homogeneous fluid supply to the electrochemically active layers. In addition, enhanced fluid flow via the active area has proven advantageous with regards to a thermal management of the cell units. Specifically, increasing fluid flow over the central portion helps to homogenise a temperature distribution inside the cell unit and, in particular, to decrease peak temperatures. This further increases performance and helps to avoid damaging of the electrochemically active layers.

[0013] The first fluid may be fuel or oxidant (e.g., air or oxygen), preferably oxidant. Thus, the gaps between the flange portions of adjacent cell units may form fuel bypass gaps or air / oxidant bypass gaps. For operation as a fuel cell, preferably the first fluid is air / oxidant. For operation as an electrolysis cell, the oxidant may primarily be produced by the electrolysis reaction.

[0014] In some embodiments, the periphery of each cell unit has two longitudinal edges extending along the first direction and two transversal edges extending in the second direction, wherein the flange portions are provided at least at the longitudinal edges.

[0015] In some embodiments, each cell unit is generally rectangular, having two opposed long sides extending in the first direction and two opposed short sides extending in the second direction. In such embodiments, the flange portions are preferably provided at least along the long sides.

[0016] In some embodiments the periphery of each cell unit has two opposed straight sides extending in the first direction and shaped ends. In such embodiments, the flange portions may be provided at the straight sides.

[0017] The cell units may be flat or planar. The cell units may each have flange portions around all of its periphery. Thus, the periphery of a cell unit may be formed by a circumferential flange portion.

[0018] The cell units may each comprise one or more plates. In preferred embodiments, each cell unit (active or inactive) comprises a, preferably shaped, interconnector plate (also referred to as interconnect or separator plate) and a, preferably flat, support plate (also referred to as substrate), which are stacked upon each other along the stacking direction. Preferably, the interconnector plate and the support plate are attached to each other, preferably by welding, and enclose a cell volume (fluid or air volume) therebetween. Preferably, the interconnector plate and the support plate are formed from metal, preferably stainless steel. Preferably, the support plate carries cell chemistry layers in its central portion. The support plate may comprise a porous region in its central portion, said porous region carrying the electrochemically active layers. The cell volume may be in fluid communication with the electrochemically active layers via said porous region.

[0019] In preferred embodiments, the support plate has a periphery and a central portion surrounded by the periphery, wherein the central portion of the support plate has a porous region and the cell chemistry layers are disposed on a surface of said porous region that is facing away from the interconnector plate, wherein the interconnector plate has a periphery and a central portion surrounded by the periphery, wherein the support plate and the interconnector plate are stacked upon one another along the stacking direction, wherein the periphery of the support plate is sealingly attached to the periphery of the interconnector plate, wherein the central portion of the support plate and the central portion of the interconnector plate enclose a cell volume (fluid volume) therebetween.

[0020] The interconnector plate may have flanged perimeter features formed along part or all of its periphery. The support plate and the interconnector plate may be attached at said flanged perimeter features, thus forming the flange portions. The flanged perimeter features may be formed by pressing the periphery of the interconnector plate, preferably such that the flanged perimeter features extend out of a plane of the original plate. In preferred embodiments, the interconnector plate has a tub-like-shape such that the periphery of the interconnector plate having the flanged perimeter features lies in a first plane offset from a second plane in which the central portion of the interconnector plate extends.

[0021] The inner and outer fluid flow paths may each comprise multiple flow paths, and they may be straight or convoluted dependent upon the design of cell units, with a net flow direction in the first direction. The cell units may define first fluid passageways, preferably air or oxidant passageways, between the central portions of adjacent cell units, said first fluid passageways forming said inner fluid flow path. In some embodiments each cell unit comprises shaped outward projections formed in its central portion, said outward projections defining said first fluid passageway. Preferably, he shaped outward projections are configured for partially separating adjacent cell units. In some embodiments, the outward projections of a first cell unit engage at their ends against an outer surface of an electrochemically active layer of an adjacent cell unit, thus forming fluid passageways therebetween. In addition to said first fluid passageways, each cell unit may define second fluid passageways, preferably fuel passageways, internal of the cell units, e.g. between upper and lower plates (preferably support plate and interconnector plate) of each cell unit. The second fluid passageways may be in communication with the fluid ports of the cell units.

[0022] In some embodiments, at least one fluid port, preferably fuel port, is provided in each of cell units. Preferably, the at least one fluid port of a respective cell unit is in communication with a second fluid passageway in the cell unit. Each cell may have at least one fuel inlet port and at least one fuel outlet port, wherein the cell unit extends between said at least one fuel inlet port and said at least one fuel outlet port in the first direction. Preferably, the respective fluid ports of adjacent cell units are aligned along the stacking direction to form an internal fluid manifold of the stack.

[0023] In some embodiments, the cell units are solid oxide fuel cell units (SOFCs). In some embodiments, the cell units are solid oxide electrolyser cell units (SOECs). Preferably, the cell units are metal-supported solid oxide fuel cell units.

[0024] The electrochemically active layers (also referred to as cell chemistry layers) preferably comprise a fuel electrode layer, an electrolyte layer and an air / oxidant electrode layer. The electrochemically active layers may be deposited (e.g. as thin coatings or films) on and supported by a mechanical support plate, e.g. by the above-described support plate.

[0025] In some embodiments, the electrochemical cell assembly may comprise a housing surrounding the stack of cell units around the stacking direction. The housing may be a stack enclosure defining a fluid volume containing the stack of cell units. The housing may be welded to the first and second plates. The housing, the first end plate and the second endplate together may form a stack enclosure defining a fluid volume containing the stack of cell units. The housing may be single piece. The housing may be formed of at least two parts, joined together at their seams, for example by welding. The housing may comprise or consist of a skirt around the cell units.

[0026] The stack of cell units may further comprise gaskets, preferably in the form of sealing rings, that are interposed between the cell units. The gaskets may surround respective fluid ports of the cell units.

[0027] In embodiments comprising a housing, the electrochemical cell assembly preferably comprises a fluid inlet port for supplying fluid, preferably first fluid (typically air or oxidant), from the exterior of the electrochemical cell assembly to a (first) fluid volume enclosed by the housing, and a fluid outlet port for removing (first) fluid (preferably exhaust air or oxidant), from the first fluid volume. Preferably, the electrochemical cell assembly comprises an air or oxidant inlet port and an air or oxidant outlet port. Thus, the fluid flow path provided between adjacent cell units preferably is a (first) fluid flow path, preferably air or oxidant flow path, for first fluid, preferably air or oxidant, to flow from the fluid inlet port to the fluid outlet port. Accordingly, there is provided a fluid flow path from the fluid inlet port to the fluid outlet port through the stack. The fluid inlet port and the fluid outlet port may be formed by a respective through-hole formed in the first or second end plate.

[0028] In preferred embodiments, the cell units extend between the fluid inlet port and the fluid outlet port in the first direction perpendicular to the stacking direction. Thus, the first direction may be a main flow direction for fluid to flow from the fluid inlet port to the fluid outlet port.

[0029] Reducing fluid flow along the outer flow path may comprise reducing a crosssection of the outer flow path, in particular reducing a cross-sectional area of one or both of the gaps between the flange portions of adjacent cell units. In some embodiments, the flow restriction device is configured to reduce a cross-section of the outer fluid path, preferably a cross-section of each gap, by at least 50%, preferably at least 60% more preferably at least 70%, more preferably at least 90%.

[0030] In some embodiments, at least one flow restriction member is disposed in the gap between the first flange portions of adjacent cell units and / or at least one flow restriction member is disposed in the gap between the second flange portions of adjacent cell units.

[0031] In some embodiments, the at least one flow restriction member extends only part of the height of the gap in stacking direction. Thus, the flow restriction device may be configured to reduce fluid flow through the outer flow path. In some embodiments, the at least one flow restriction member extends the full height of the gap in stacking direction. In preferred embodiments, the at least one flow restriction member extends the full height of the respective gap in stacking direction and the full width of the respective gap in second direction. Thus, the flow restriction device may be configured to prevent fluid flow through the outer flow path.

[0032] In some embodiments, the at least one flow restriction member is formed from a, preferably elastically, deformable material to compensate for height changes of the gap along the stacking direction, e.g. due to compression of the cell stack and / or thermal expansion.

[0033] In preferred embodiments, the at least one flow restriction member is formed from a vermiculite material, preferably from an exfoliated vermiculite material. Vermiculite material has proven particularly advantageous with regards to mechanical compliance and reliable sealing performance at elevated temperatures. The exfoliated vermiculite material may comprise exfoliated vermiculite or consist of exfoliated vermiculite. The exfoliated vermiculite material may be thermally or chemically exfoliated.

[0034] In further preferred embodiments, the flow restriction member or at least one of the flow restriction members is formed from a ceramic material, preferably mica.

[0035] In some embodiments, the flow restriction member or at least one of the flow restriction members is elongate extending along the first direction. This helps to guide fluid flow through the inner flow path and particularly to reduce undesired transversal fluid flow from the central portion in second direction (i.e. away from the electrochemically active layers towards the periphery), thus increasing performance of the cell assembly.

[0036] In some embodiments, the flow restriction member or at least one of the flow restriction members extends only along part of the extension of the respective flange portion along the first direction. That is to say, a flow restriction member being positioned in the gap between the first flange portions of adjacent cell units may extend only along part of the extension of said first flange portions along the first direction. Analogously, a flow restriction member being positioned in the gap between the second flange portions of adjacent cell units may extend only along part of the extension of said second flange portions along the first direction. Thus, the at least one flow restriction member may overlay only a section of a respective flange portion along the first direction. This can be advantageous to enhance fluid flow only over selected regions of the central portion. The at least one flow restriction member may extend maximum half, preferably maximum one third, of the extension of the first or second flange portion along the first direction.

[0037] In some embodiments, the flow restriction member or at least one of the flow restriction members extends only along part of the extension of the respective flange portion along the first direction and is positioned at a downstream part of said flange portion. That is to say, a flow restriction member being positioned in the gap between the first flange portions of adjacent cell units may be positioned at a downstream part of the first flange portions. Analogously, a flow restriction member being positioned in the gap between the second flange portions of adjacent cell units may be positioned at a downstream part of the second flange portions. In other words, the flow restriction member or at least one of the flow restriction members may be positioned at a downstream portion of the gap formed between the first flange portions of adjacent cell units and / or the flow restriction member or at least one of the flow restriction members may be positioned at a downstream portion of the gap formed between the second flange portions of adjacent cell units. This configuration aids guiding fluid, preferably selectively, through the downstream part of the central portion. Said downstream part of the central portion typically becomes hottest during cell operation. Thus, the flow restriction member may aid cooling this part while keeping material costs low and reducing the pressure drop compared to a fully extended flow restriction member. In some embodiments, the flow restriction member or at least one of the flow restriction members may extend over, preferably at most, the downstream half, preferably the downstream third, of the respective flange portion along the stacking direction. Preferably, the downstream part of the respective flange portion is an end part of the flange portion in the first direction.

[0038] In some embodiments, the flow restriction member or at least one of the flow restriction members extends at least the full extension of the central portion in the first direction. In some embodiments, the flow restriction member or at least one of the flow restriction members extends the full length of the respective gap along the first direction.

[0039] In some embodiments, the flow restriction member or at least one of the flow restriction members is formed by a strip of a sealing material, said strip extending in the first direction. Thus, between the first flange portions of adjacent cell units and / or between the second flange portions of adjacent cell units, a strip of a sealing material may be provided, said strip extending along the first direction. Preferably, the sealing material is a, preferably elastically, deformable material to compensate for height changes of the gap along the stacking direction, e.g. due to compression of the cell stack and / or thermal expansion. Most preferably, the sealing material comprises or consists of a vermiculite material (see above).

[0040] In some embodiments, the flow restriction member or at least one of the flow restriction members is printed, preferably 3D-printed, on a flange portion of the cell unit. Thus, at least one flow restriction member may be printed on the first flange portion of a respective cell unit and / or at least one flow restriction member may be printed on the second flange portion of a respective cell unit. Printing the flow restriction member on the flange portion eases manufacturing since assembly procedures such as placing or gluing may be avoided. In addition, printing the flow restriction member makes it possible to easily vary a geometry of the flow restriction member, e.g. depending on the type of cell unit or on the relative position of a respective cell unit in the stack. In embodiments, wherein the cell unit comprises a support plate and interconnector plate, the flow restriction member is preferably printed on the support plate. Preferably, the flow restriction member is printed from a sealing material described above. In some embodiments, the flow restriction member or at least one of the flow restriction members is formed by a paste provided between adjacent cell units, preferably in the gap between the flange portions of adjacent cell units. This has proven advantageous with regards to easy manufacturing since the paste can easily be applied due to its deformability. The paste preferably solidifies upon heat treatment, e.g. in the course of a stack baking process known in the art. Preferably, the paste at least partially fills the gap between the flange portions of adjacent cell units. The paste may be applied to additional parts of the cell unit, e.g. to other parts of the peripheries of the cell units.

[0041] In preferred embodiments, the paste comprises a vermiculite material.

[0042] In some embodiments, the flow restriction member or at least one of the flow restriction members is provided by a clip that is positioned (e.g., pinned) on, preferably attached to, a flange portion of the cell unit. Thus, at least one clip may be positioned (e.g., pinned) on the first flange portion of a respective cell unit and / or at least one clip may be positioned (e.g., pinned) on the second flange portion of a respective cell unit. This has proven advantageous with regards to easy and, in particular, debris-free manufacturing of the cell assembly. In addition, the clip configuration makes it possible to attach the clip on the final stack, i.e. after having stacked the cell units and potentially after having performed optional stack baking processes. Preferably, the clip embraces the flange portion of a respective cell unit. In some embodiments, the clip has a II- shape. In some embodiments, the cell unit has a recess (notch) formed in an outer edge of the flange portion to accommodate the clip such that the clip does not extend radially over an outer perimeter of the (footprint of the) cell unit, preferably is flush with an outer perimeter of the cell units. In some embodiments, the clip is fixedly attached to the cell unit, preferably by welding.

[0043] In some embodiments, the flow restriction members of adjacent flow restriction devices are aligned such that they overlie along the stacking direction. Thus, the flow restriction members may form a column of flow restriction members along the stacking direction. This may be beneficial with regards to a homogeneous fluid flow through the stack and to improved mechanical stability of the stack. In some embodiments, flow restriction members of at least a subset of adjacent flow restriction devices are connected, preferably provided, by a common flow restriction piece. This helps to reduce part count during manufacturing. In some embodiments, flow restriction members of at least a subset of adjacent flow restriction devices may be single piece.

[0044] In some embodiments, the electrochemical cell assembly comprises at least one comb-like flow restriction piece, said comb-like flow restriction piece providing at least a subset of the flow restriction members. Preferably, the comb-like flow restriction piece has a shaft portion extending along the stacking direction and a series of projections (i.e. the "teeth" of comb) projecting from the shaft portion, preferably in a direction perpendicular to the stacking direction. Preferably, the comb-like flow restriction piece is arranged such that each of said projections extends in a respective gap provided between the flange portions of adjacent cell units, thus forming a respective flow restriction member. In preferred embodiments, the at least one comb-like flow restriction piece is formed from a ceramic material, preferably from mica. The comb-like flow restriction piece may be a block of machined mica. In some embodiments, the electrochemical cell assembly comprises two opposed comb-like flow restriction pieces provided on opposite sides of the stack of cell units.

[0045] In some embodiments, each cell unit has at least one recess (cut-out) formed in either or both the first and second flange portions. The respective recesses of adjacent cell units being aligned to define a recessed channel extending along the stacking direction, wherein the flow restriction members of at least a subset of adjacent flow restriction devices are formed by a beam, said beam extending in said recessed channel along the stacking direction. This configuration eases manufacturing of the electrochemical cell assembly since a part count is reduced. In addition, the beam may assist in cell retaining, thus improving stability over lifetime of the cell assembly.

[0046] Preferably, the beam is formed from a ceramic material, more preferably from mica or alumina. Preferably, the beam extends the full height of the stack along the stacking direction. Preferably, each recess extends the full width of the respective flange portion in the second direction. In some embodiments, each cell unit has at least one, preferably two, recesses formed in each of the first and second flange portions, these recesses preferably being aligned across the first direction of the cell unit.

[0047] In some embodiments, each cell unit comprises a support plate and an interconnector plate, said support plate and said interconnector plate overlying one another along the stacking direction, wherein the at least one recess is formed in both the interconnector plate and the support plate.

[0048] In some embodiments, the flow restriction member or at least one of the flow restriction members is provided by an outer edge portion of the periphery, preferably an outer edge portion of the respective flange portion, said outer edge portion being bent over such that it protrudes into the respective gap between the flange portions of adjacent cell units and at least partially fills said gap. This has proven advantageous with regards to easy manufacturing since additional flow restriction pieces can be avoided. In embodiments, in which the cell unit comprises a support plate and an interconnector plate, the outer edge portion of the periphery that is bent over may be formed by an outer edge portion of the support plate and / or an outer edge portion of the interconnector plate.

[0049] In some embodiments, the flow restriction member is formed by a weld bead, preferably butt weld. Said butt weld may be around a circumference of the cell unit.

[0050] In some embodiments, each cell unit comprises at least one fuel port, preferably in the form of a through-hole extending along the stacking direction, each fuel port being associated with a gasket surrounding it, wherein the flow restriction member or at least one of the flow restriction members is provided by said gasket. In preferred embodiments, said gasket is a flow restriction gasket, said flow restriction gasket having a main body surrounding the associated fuel port and a protrusion (extended portion) protruding from its main body, preferably along the second direction, into an adjacent gap formed between the flange portions of adjacent cell units. Thus, said protrusion forms a flow restriction member. Such a flow restriction gasket provides both a sealing function of the fuel port and a fluid blocking function, which reduces complexity. Preferably, the at least one gasket is formed from a vermiculite material. Preferably, the protrusion has a smaller thickness than the main body along the stacking direction. This helps to improve reliable sealing of the fuel ports.

[0051] In some embodiments, the periphery comprises a first flange portion and an opposite second flange portion, wherein the outer flow path comprises a first partial outer flow path through a first gap formed between the first flange portions of adjacent cell units and a second partial outer flow path through a second gap formed between the second flange portions of adjacent cell units.

[0052] In some embodiments, the flow restriction device is configured to selectively reduce or prevent fluid flow along one of said first and second partial outer flow paths, preferably to selectively reduce or prevent fluid flow through one of said first and second gaps formed between the flange portions of adjacent cell units. This configuration has surprisingly proven advantageous with regards to a stable (first) fluid, preferably air or oxidant, flow inside the cell assembly, because it improves mixing of (relatively cold) fluid bypass flows with the (relatively hot) fluid flows from the central portion (active area). In some embodiments, a flow restriction member may be provided only in one if the first and second gaps. That is to say, one of the first and second gaps may be devoid of a flow restriction member. Preferably, said flow restriction member is provided in a downstream portion of the gap. For example, the flow restriction member may extend only along part of the extension of the flange portion along the first direction and may be positioned at a downstream part of said flange portion (see above).

[0053] According to a second aspect there is provided a flow restriction device for an electrochemical cell assembly, preferably fuel cell assembly or electrolysis cell assembly, said flow restriction device comprising at least one flow restriction member and being configured to reduce or prevent fluid flow along an outer flow path through gaps between flange portions of adjacent cell units in an electrochemical cell assembly. The flow restriction device may be in accordance with the embodiments described above.

[0054] Further embodiments are derivable from the following description and the drawings. In the drawings:

[0055] Figure 1 shows a perspective view of an exemplary an electrochemical cell assembly;

[0056] Figure 2 shows a top view of the electrochemical cell assembly of Figure 1 ;

[0057] Figure 3 shows a cross-sectional view of the electrochemical cell assembly of Figure 1 ;

[0058] Figure 4 shows a schematic cross-sectional view of two adjacent cell units;

[0059] Figure 5 shows an exploded view of an exemplary cell unit;

[0060] Figure 6 shows a bottom view of the cell unit of Figure 5;

[0061] Figure 7 shows a schematic cross-sectional view according to Figure 4, albeit with a flow restriction device according to a first example;

[0062] Figure 8 shows a bottom view of the upper cell unit of Figure 7;

[0063] Figure 9 shows a schematic cross-sectional view of a stack of cell units with a flow restriction device according to a second example;

[0064] Figure 10 shows a detail of a cell unit with a flow restriction device according to a third example;

[0065] Figure 11 shows a bottom view of a stack of cell units with a flow restriction device according to a fourth example;

[0066] Figure 12 shows a cross-sectional view of the stack according to Figure 11 ;

[0067] Figure 13 shows a bottom view of a detail of a cell unit with a flow restriction device according to a fifth example; Figure 14 shows a schematic cross-section view of a detail of a cell unit with a flow restriction device according to a sixth example; and

[0068] Figure 15 shows a schematic cross-section view of a detail of a cell unit with a flow restriction device according to a seventh example.

[0069] Repeat use of reference symbols in the present specification and drawings is intended to represent the same or analogous features or elements.

[0070] Referring to Figures 1 to 3, there is shown an exemplary configuration of an electrochemical cell assembly 10. The electrochemical cell assembly 10 comprises a first end plate 12, a second end plate 14 (see Fig. 3, not shown in Fig. 1), and a stack 16 of cell units 18 (also referred to as ‘cell repeat units’) arranged between the first end plate 12 and the second end plate 14. Preferably, the stack 16 is held in a compressed state between the first end plate 12 and the second end plate 14.

[0071] Figures 1 to 3 are intended to primarily provide an overview of the electrochemical cell assembly 10 and its components in general by way of example. The invention, however, is not limited to this specific design.

[0072] The stack 16 comprises a plurality of cell units 18 that are stacked upon each other along a stacking direction 20. As set out above, the cell units 18 may be fuel cell units, electrolyser cell units or reversible cell units. In the example, the cell units 18 are metal-supported solid oxide fuel cells (details see below).

[0073] As shown in Figure 1 , each cell unit 18 extends in a respective cell plane perpendicular to the stacking direction 20 in a first direction 22 and in a second direction 24 perpendicular to the first direction 22. Each cell unit 18 has a periphery 28 and a central portion 30 surrounded by the periphery 28, the central portion 30 carrying electrochemically active layers 32 (see Figure 2, details below).

[0074] In the example shown, the cell units 18 are generally rectangular, albeit with shaped corners 34. Specifically, each cell unit 18 has two opposed long sides 36- 1 , 36-2, preferably straight sides, that extend along the first direction 22, and two opposed short sides 38-1, 38-2 that extend along the second direction 24 (see Fig. 1).

[0075] In the example shown in Figure 1, in each of said shaped corners 34, an optional electrically insulating beam 40 is provided. In embodiments not shown, there may be beams 40 provided only on two of the shaped corners 34. In further embodiments not shown there may be no beams 40 provided (as, for example, in Fig. 2). In example, the electrically insulating beams 40 take the form of a circular shaped or tubular shaped beam, such as the pipe or tube as shown - with a central opening 42. In the preferred examples they will be made of mica, although other electrically insulating materials, including many ceramics, can also be used; preferably non-frangible electrically insulating materials are used.

[0076] Referring to Figure 3, it can be seen that the stack 16 of cell units 18 further comprises gaskets 44 that are interposed between the cell units 18. Exemplarily, the gaskets 44 are annular sealing rings having a central opening 46. The gaskets 44 surround respective through-holes 48 (fluid ports 50) of the cell units 18 (details see below).

[0077] An aligned column of the central openings 46 of the gaskets 44 and the through- holes 48 (fluid ports 50) of the cell units 18 forms a fluid manifold 52 extending throughout the stack 16 of cell units 18 along the stacking direction 20. In the example, the stack 16 of cell units 18 comprises two fluid manifolds 52 serving as (second fluid, e.g., fuel) inlet manifolds and two fluid manifolds 52 serving as (second fluid, e.g., fuel) outlet (exhaust) manifolds. In order to transport second fluid (e.g., fuel) between the exterior of the electrochemical cell assembly 10 and the fluid manifolds 52, the first end plate 12 comprises respective through-holes 54 arranged at a position corresponding to the assigned fluid manifold (see Figure 3). Thus, the through-holes 54 form fuel access ports 56 of the cell assembly 10.

[0078] The electrochemical cell assembly 10 preferably also comprises a current collection or delivery system (not shown). For example, the electrochemical cell assembly 10 may comprise one or more current collector plates, as known in the art. In addition, the current collection or delivery system may comprise one or more electrical connection members, such as busbars, for electrically connecting said current collector or delivery plates. In some embodiments, such an electrical connection member may extend in the central opening 42 of an electrically insulating beam 40.

[0079] In the example shown, between each end plate 12 and the stack 16 of cell units 18, there is provided an optional insulation plate 58 (see Fig. 3). The insulation plate 58 may be formed from mica.

[0080] The electrochemical cell assembly 10 further comprises a housing 60 circumscribing the stack 16 of cell units 18 around the stacking direction 20. In the example, the housing 42 is a skirt, which may be formed in plural sections 62- 1 , 62-2, which are joined together at a joint line 64, preferably by welding. In preferred examples, the housing 60 is formed from metal, preferably steel. The housing 60 may be welded to the end plates 12, 14. The housing 60 and the end plates 12, 14 together enclose a first fluid volume 66, preferably for air or oxidant, around the stack 16 of cell units 18.

[0081] The electrochemical cell assembly 10 further comprises two optional electrically insulating boards 68 located on opposite sides of the stack 16 of cell units 18. Specifically, each board 68 is located in a respective gap 70 provided between the housing 60 and the long sides 36-1 , 36-2 of the cell units 18. The boards 68 extend along the long sides 36-1 , 36-2 of the cell units 18 in the first direction 22 and in the stacking direction 20. In the preferred examples, the boards 68 will be made of mica, although other electrically insulating materials, including many ceramics, can also be used; preferably non-frangible electrically insulating materials are used.

[0082] In order to supply first fluid to the first fluid volume 66 enclosed by the housing 60, the electrochemical cell assembly 10 further comprises a first fluid inlet port 72 (which may, preferably, also be referred to as air inlet port 72) and an opposite first fluid outlet port 74 (which may, preferably, also be referred to as air outlet port 74), see Fig. 2. In the example, the first fluid inlet port 72 and the first fluid outlet port 74 are each provided by a respective through-hole 76, 78 formed in the first end plate 12. Referring to Figure 2, it can be seen that the cell units 18 extend between the first fluid inlet port 72 and the first fluid outlet port 74 in the first direction 22. As described in detail below, the cell units 18 define a fluid flow path 80 between adjacent cell units 18 for first fluid to flow from the first fluid inlet port 72 to the first fluid outlet port 74. Specifically, the fluid flow path 80 comprises an inner flow path 82 for fluid to flow between the central portions 30 of the adjacent the cell units 18 and an outer flow path 84 for fluid to flow between the peripheries 28 of adjacent cell units 18 (see Figure 2).

[0083] Referring to Figure 4, it can be seen that the inner flow path 82 extends through fluid passageways 86 (which may for example be channels or dimpled regions, providing tortuous flow paths) defined between the central portions 30 of adjacent cell units 18, and the outer flow path 84 extends through gaps 88-1 , 88-2 formed between the peripheries 28 of adjacent cell units 18.

[0084] Specifically, the periphery 28 of each cell unit 18 comprises a first flange portion 90-1 at its first long side 36-1 and an opposite second flange portion 90-2 at its second long side 36-2. The flange portions 90-1 , 90-2 preferably extend parallel to each other along the first direction 22 (see Figure 5). In the example, each cell unit 18 also comprises flange portions at their short sides 38-1 , 38-2. As shown in Figure 4, the flange portions 90-1 , 90-2 of adjacent cell units overlie one another along the stacking direction 20 and are separated by the above-mentioned gaps 88-1, 88-2. Said gaps 88-1, 88-2 each form a fluid bypass for fluid to bypass the central portion 30 and thus the electrochemically active layers 32 (see Figure 2).

[0085] In the following, an exemplary configuration of the cell units 18 will be described with reference to Figures 4 to 6.

[0086] In the example, the cell units 18 are metal-supported solid oxide fuel cells. Each cell unit 18 exemplarily comprises an interconnector plate 92 (also referred to as interconnect or separator plate) and a support plate 94 (also referred to as substrate), which are stacked upon each other along the stacking direction 20. The interconnector plate 92 and the support plate 94 are formed from metal, preferably stainless steel. It will be understood that other types of support for the electrochemically active layers may be used, for example electrolyte or anode supported. Referring to Figure 4, it can be seen that the interconnector plate 92 and the support plate 94 each have a periphery 28 and a central portion 30 surrounded by the periphery 28. The interconnector plate 92 and the support plate 94 are attached to each other at their peripheries 28, preferably by welding, to enclose a cell volume (also referred to as second fluid volume) 96 therebetween (see Figure 4).

[0087] The support plate 94, in its central portion 30, carries the electrochemically active layers 32 over a porous region 98 (see Fig. 4). The cell volume 96 is in fluid communication with the electrochemically active layers 32 via said porous region 98.

[0088] In the preferred examples, the interconnector plate 92 is tub-shaped having having flanged perimeter features 100 around its periphery 28, preferably formed by pressing the interconnector plate 92 to a concave configuration (alternatively or additionally by pressing the support plate 94 to a concave configuration). As can be seen from Figure 4, the support plate 94 and the interconnector plate 92 are joined at said flanged perimeter features 100 along the long sides 36-1, 36-2, preferably by welding, thus forming the said flange portions 90-1 , 90-2 of the cell unit 18.

[0089] As shown in Figure 4, the flanged perimeter features 100 are elevated over the central portion 30 of the interconnector plate 92 such that they extend in a first plane offset from a second plane in which the central portion 30 of the interconnector 92 extends, thus providing for the gaps 88-1 , 88-2 between the flange portions 90-1 , 90-2 of adjacent cell units.

[0090] As shown in Figures 4 and 6, the interconnector plate 92 has a structured area 102 in its central portion 30 having shaped outward projections 104 extending along the stacking direction 20. Said structured area 102 forms a contact area of the cell unit 18 for contacting an adjacent cell unit 18, specifically the electrochemically active layers 32 of an adjacent cell unit 18 (see Figure 4). More specifically, the outward projections 104 engage at their ends against an outer surface of the electrochemically active layer 32 of an adjacent cell unit 18, thus defining the above-mentioned first fluid passageways 86 between adjacent cell units 18. The projections 104 may be pressed or formed in the interconnector plate. Channels, instead of discrete projections, may be used.

[0091] In order to supply fluid, in particular fuel, to the cell volume 96 between the support plate 94 and the interconnector plate 92 (and thus to the electrochemically active layers 32) or to remove fluid from the cell volume 96, each cell unit 18 has at least one, in the specific example four, through-holes 48 formed therein, said through-holes 48 being in fluid communication with the electrochemically active layers 32 of the cell unit 18 via the cell volume 96 and the porous region 98. Specifically, both the support plate 94 and the interconnector plate 92 have respective through-holes 48. Those through-holes 48 form the above-mentioned fluid ports 50 of the cell unit 18. In the specific example, each cell unit 18 comprises two second fluid (e.g., fuel) inlet ports 106 and two second fluid (e.g., fuel) outlet ports 108 (see Fig. 2).

[0092] As schematically shown in Figure 2, within each cell unit 18, second fluid (e.g., fuel) flows from the two second fluid inlet ports 106 to the second fluid outlet ports 108, wherein a net fuel flow direction 110 extends along the first direction 22. In practice, there will be multiple flow paths through the cell volume 96, and they may be straight or convoluted, dependent upon the design of cell units 18. It will be understood that the second fluid ports 106 and second fluid ports 108 may alternatively be used as second fluid outlet and second fluid inlet ports, respectively.

[0093] According to the invention, between adjacent cell units 18 there is provided a flow restriction device 112 comprising at least one flow restriction member 114 for reducing or preventing (first) fluid flow, preferably air flow, via said outer flow path 84, i.e. through the gaps 88-1, 88-2 provided between the first and second flange portions 90-1, 90-2 of adjacent cell units 18.

[0094] Figure 7 show a first example, wherein the flow restriction device 100 comprises a first flow restriction member 114-1 located in the gap 88-1 between the first flange portions 90-1 of adjacent cell units 18 and a second flow restriction member 114-2 located in the gap 88-2 between the second flange portions 90-2. In the example of Figure 8, the flow restriction members 114-1, 114-2 of Fig. 7 take the form of strips 116, said strips 116 extending along the first direction 22. In the example, the strips 116 extend the full length of the central portion 30 in the first direction 22.

[0095] In other embodiments, the strips 116 may extend only along part of the extension of the respective flange portion 90-1, 90-2. In such embodiments, it may be advantageous if the strips 116 are located in a respective downstream part 117 of the flange portions 90-1 , 90-2.

[0096] In the example, the strips 116 extend the full height 118 of the respective gap 88- 1, 88-2 along the stacking direction 20. Thus, the strips 116 abut an upper surface of the support plate 94 of a cell unit 18 and a lower surface of the interconnector plate 92 of the adjacent cell unit 18 (see Fig. 7). In other embodiments, the strips 116 may extend only part of the height 118 of the respective gap 88-1, 88-2 along the stacking direction 20.

[0097] In preferred examples, the strips 116 are formed from a vermiculite material. The strips 116 may be bonded to the support plate 94 and / or the interconnector plate 94 by gluing.

[0098] In other embodiments, the strips 116 may be directly printed on the support plate 94, e.g. by 3D-printing.

[0099] In further embodiments, the flow restriction members 114-1, 114-2 may be provided by a paste applied in the respective gap 88-1, 88-2 between the flange portions 90-1, 90-2. In preferred examples, the paste is a vermiculite paste.

[0100] Figure 9 shows a second example, wherein the electrochemical cell assembly 10 comprises a comb-like flow restriction piece 120 having a shaft portion 122 extending along the stacking direction 20 and a series of projections 124 projecting from the shaft portion 122 along the second direction 24.

[0101] As shown in Figure 9, the comb-like flow restriction piece 120 is arranged such that each of said projections 124 extends in a respective gap 88-1 formed between the flange portions 90-1 of adjacent cell units 18, thus forming a flow restriction member 114. The projections 124 may extend at least the extent of the central portion 30 in the first direction 22 (in Figure 9 perpendicular to the drawing plane). The electrochemical cell assembly 10 preferably comprises a second flow restriction piece 120 (not shown) on the opposite side of the stack 16 (i.e. on the second long side of the cell units 18). The first and second flow restriction pieces 120 may be configured identically.

[0102] Figure 10 shows a third example, wherein the flow restriction device 112 comprises a u-shaped clip 126, which may be positioned or pinned on a respective flange portion 90 of a cell unit 18 (for simplicity, Figure 10 does not show the interconnector plate 92 and the support plate 94 as individual components). Preferably, the cell unit 18 has a recess 128 formed in an outer edge 130 (outer perimeter) of the flange portion 90 to accommodate the clip 126 such that the clip 126 does not extend radially over an outer perimeter or footprint of the flange portion 90. The clip 126 may be bonded to the cell unit 18 by welding.

[0103] Figures 11 and 12 show a fourth example, wherein each cell unit 18 has two recesses 132 formed in both the first flange portion 90-1 and the second flange portion 90-2. The recesses 132 of adjacent cell units 18 overlie each other along the staking direction 20 to define respective recessed channels extending along the stacking direction 20. In each of said channels, a flow restriction beam 134 is provided. As can be seen from Figure 12, the beams 134 extend along the stacking direction 20, preferably the full height of the stack 16, and locally reduce a cross-sectional area of the gaps 88-1, 88-2 formed between the flange portions 90-1, 90-2 of adjacent cell units 18. In preferred examples, the beams 134 are formed from mica. It will be understood that each cell unit 18 having two recesses 132 formed in both the first flange portion 90-1 and the second flange portion 90- 2 is exemplary in Fig. 11, and the flange portions may have a different number of recesses (preferably, but not necessarily, an equal number, opposing one another across the cell unit), for example one, three, and so forth.

[0104] Figure 13 shows a fifth example, wherein the flow restriction members 114 are provided by flow restriction gaskets 136. Specifically, at least a subset of the gaskets 44 of the stack 16, preferably at least the gaskets 44 surrounding the second fluid inlet ports 106 of a respective cell unit 18 are flow restriction gaskets 136. As shown in Figure 13, each flow restriction gasket 136 comprises a main body 138 that is surrounding the respective fluid port 106, and a protrusion 140 (extended portion) protruding from said main body 138 along the second direction 24. The protrusion 140 preferably comprises a shaped end portion 142 that extends into the corresponding gap 88-1, 88-2 formed between the flange portions 90-1, 90-2, thus blocking first fluid flow through said gaps 80-1, 80-2. The two gaskets 124 are separated from each other along the second direction 24 to allow fluid flow along the inner flow path 82. In preferred examples, the main body 138 of a respective flow restriction gasket 136 has a larger thickness in stacking direction 20 than the protrusions 140. In preferred examples, the flow restriction gaskets 136 are formed from a vermiculite material.

[0105] Figures 14 and 15 show a sixth and a seventh example, wherein an outer edge portion 144 of the respective flange portion 90 is bent over such that it protrudes into and at least partially fills the gap 80 between the flange portions 90 of adjacent cell units 18, thus restricting fluid flow through said gap. In the example of Figure 14, both the interconnector plate 92 and the support plate 94 are bent. In the example of Figure 15, only the support plate 94 is bent. In this case, the support plate 94 extends over the interconnector plate 92 in the cell plane. Alternatively, only the interconnector plate 92 is bent.

[0106] In embodiments not shown, several of the described variants of the flow restriction device 112 may be combined. For example, a flow restriction device 112 may comprise a flow restriction member 114 formed by a flow restriction gasket 136 and, additionally, a flow restriction member 114 formed by a strip 116 of vermiculite material.

Claims

Claims1. An electrochemical cell assembly (10), preferably fuel cell assembly or electrolysis cell assembly, comprising a stack (16) of cell units (18), comprising a plurality of cell units (18) stacked upon one another along a stacking direction (20), wherein: each cell unit (18) extends perpendicular to the stacking direction (20) in a first direction (22) and in a second direction (24) perpendicular to the first direction (22), each cell unit (18) has a periphery (28) and a central portion (30) surrounded by the periphery (28), said central portion (30) preferably comprising electrochemically active layers (32), the periphery (30) has a first flange portion (90-1) and an opposite second flange portion (90-2), said first and second flange portions (90-1, 90- 2) each extending in the first direction (22), the central portion (30) is located between said first and second flange portions (90-1 , 90-2), the flange portions (90-1, 90-2) of adjacent cell units (18) overlie one another and are separated by a gap (88-1, 88-2), between two adjacent cell units (18), there is provided a fluid flow path (80) for first fluid, said fluid flow path (80) comprising an inner flow path (82) between the central portions (30) of adjacent cell units (18) and an outer flow path (84) through said gaps (88-1 , 88-2) between the flange portions (90-1 , 90-2) of adjacent cell units (18), and a flow restriction device (112) comprising at least one flow restriction member (114-1, 114-2), said flow restriction device (112) being configured to reduce or prevent fluid flow along the outer flow path (84).

2. The electrochemical cell assembly (10) according to claim 1, wherein the flow restriction device (112) is configured to reduce a cross-section of the outer fluid path (84) by at least 50%, preferably at least 60% more preferably at least 70%, more preferably at least 90%.

3. The electrochemical cell assembly (10) according to claim 1 or 2, wherein at least one flow restriction member (114-1) is disposed in the gap (88-1) between the first flange portions (90-1) of adjacent cell units (118) and / or at least one flow restriction member (114-2) is disposed in the gap (88-2) between the second flange portions (90-2) of adjacent cell units (18).

4. The electrochemical cell assembly (10) according to the preceding claim, wherein the at least one flow restriction member (114) is elongate extending along the first direction (22).

5. The electrochemical cell assembly (10) according to the preceding claim, wherein the at least one flow restriction member (114) extends only along part of the extension of the respective flange portion (90-1, 90-2) along the first direction (22).

6. The electrochemical cell assembly (10) according to the preceding claim, wherein the at least one flow restriction member (114) is positioned at a downstream part (117) of the respective flange portion (90-1, 90-2).

7. The electrochemical cell assembly (10) according to claim 4, wherein the at least one flow restriction member (114) extends the full extension of the central portion (30) in the first direction (22).

8. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the at least one flow restriction member (114) is formed from a, preferably elastically, deformable material to compensate for height (118) changes of the gap (88-1, 88-2) along the stacking direction (20).

9. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the at least one flow restriction member (114) is formed from a vermiculite material10. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the flow restriction member (114) or at least one of the flow restriction members (114) is formed by a strip (116) of a vermiculite material, said strip (116) extending in the first direction (22).

11. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the flow restriction member (114) or at least one of the flow restriction members (114) is printed, preferably 3D-printed, on a flange portion (90-1 , 90-2) of the cell unit (18).

12. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the flow restriction member (114) or at least one of the flow restriction members (114) is formed by a paste provided between the adjacent cell units (18), preferably in the gap (80) between the flange portions (90) of adjacent cell units (18).

13. The electrochemical cell assembly (10) according to the preceding claim, wherein the paste comprises a vermiculite material.

14. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the flow restriction member (114) or at least one of the flow restriction members (114) is provided by a clip (126) that is positioned on the respective flange portion (90) of the cell unit (18).

15. The electrochemical cell assembly (10) according to the preceding claim, wherein the clip (126) has a U-shape.

16. The electrochemical cell assembly (10) according to claim 14 or 15, wherein the clip (126) is fixedly attached to the cell unit (18), preferably by welding.

17. The electrochemical cell assembly (10) according to any of claims 14 to 16, wherein the cell unit (18) has a recess (128) formed in an outer edge (130) of the flange portion (90) to accommodate the clip (126) such that the clip (126) does not extend radially over an outer perimeter of the cell unit (18).

18. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein flow restriction members (114) of adjacent flow restriction devices (112) are aligned such that they overlie along the stacking direction (20).

19. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein flow restriction members (114) of at least a subset of adjacent flow restriction devices (112) are connected, preferably provided, by a common flow restriction piece (120).

20. The electrochemical cell assembly (10) according to any one of the preceding claims, comprising at least one comb-like flow restriction piece (120), said comb-like flow restriction piece (120) having a shaft portion (122) extending along the stacking direction (20) and a series of projections (124) projecting from said shaft portion (122), preferably in a direction perpendicular to the stacking direction (20), wherein the comb-like flow restriction piece (120) is arranged such that each of said projections (124) extends in a respective gap (80) between the flange portions (90) of adjacent cell units (18) to form a flow restriction member (114).

21. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein each cell unit (18) has at least one recess (132) formed in either or both the first flange portion (90-1) and the second flange portion (90-2), the respective recesses (132) of adjacent cell units (18) being aligned to define a recessed channel extending along the stacking direction (20), wherein the flow restriction members (114) of at least a subset of adjacent flow restriction devices (112) are formed by a beam (134), said beam (134) extending in said recessed channel along the stacking direction (20).

22. The electrochemical cell assembly (10) according to the preceding claim, wherein the beam (134) is formed from a ceramic material, preferably from mica.

23. The electrochemical cell assembly (10) according to claim 21 or 22, wherein the beam (134) extends the full height of the stack (16) along the stacking direction (20).

24. The electrochemical cell assembly (10) according to any of claims 21 to 23, wherein each recess (134) extends the full width of the respective flange portion (90) in the second direction (24).

25. The electrochemical cell assembly (10) according to any of claims 21 to 24, wherein each cell unit (18) has at least one recess (134) formed in each of the first and second flange portions (90-10, 90-2), these recesses (134) being aligned across the first direction (22).

26. The electrochemical cell assembly (10) according to any of claims 21 to 25, wherein each cell unit (18) comprises a support plate (94) and an interconnector plate (92), wherein the support plate (94) and the interconnector plate (92) overly one another along the stacking direction (20), and preferably are attached to each other to enclose a cell volume (96) therebetween, wherein the at least one recess (134) is formed in both the interconnector plate (92) and the support plate (94).

27. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the flow restriction member (114) or at least one of the flow restriction members (114) is provided by an outer edge portion (144) of the periphery (28), preferably an outer edge portion (144) of the respective flange portion (90), said outer edge portion (144) being bent over such that it protrudes into and at least partially fills the gap (80) between the flange portions (90) of adjacent cell units (18).

28. The electrochemical cell assembly (10) according to the preceding claim, wherein each cell unit (18) comprises a support plate (94) and an interconnector plate (92), wherein the support plate (94) and the interconnector plate (92) overly one another along the stacking direction (20), and preferably are attached to each other to enclose a cell volume (96) therebetween, wherein the outer edge portion (144) of the periphery (28) is formed by an outer edge portion (144) of the support plate (94) and / or the interconnector plate (92).

29. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the flow restriction member (114) or at least one of the flow restriction members (114) is formed by a weld bead, preferably butt weld.

30. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein each cell unit (18) further comprises at least one fluid port (50) for second fluid, preferably in the form of a through-hole (48) extending along the stacking direction (20), said at least one fluid port (50) being associated with a gasket (44) surrounding it, wherein said gasket (44) is a flow restriction gasket (136), said flow restriction gasket (136) having a main body (138) surrounding the associated fluid port (50) and a protrusion(140) protruding from the main body (138) into the gap (80) between the flange portions (90) of adjacent cell units (18) forming a flow restriction member (114).

31. The electrochemical cell assembly (10) according to the preceding claim, wherein the protrusion (140) has a smaller thickness than the main body (138) along the stacking direction (20).

32. The electrochemical cell assembly according to any one of the preceding claims, wherein the periphery (28) comprises a first flange portion (90-1) and an opposite second flange portion (90-2), wherein the outer flow path (84) comprises a first partial outer flow path through a first gap (88-1) formed between the first flange portions (90-1) of adjacent cell units (18) and a second partial outer flow path through a second gap (88-2) formed between the second flange portions (90-2) of adjacent cell units (18), wherein the flow restriction device (112) is configured to selectively reduce or prevent fluid flow, through one of said first and second partial outer flow paths.

33. The electrochemical cell assembly according to the preceding claim, wherein a flow restriction member (114) is provided in one of said first and second gaps (88-1, 88-2), preferably in a downstream portion of said gap.

34. The electrochemical cell assembly (10) according to any one of the preceding claims, further comprising a housing (60) surrounding the stack (16) of cell units (18) to define or enclose a fluid volume (66); a fluid inlet port (72) for supplying fluid from the exterior of the electrochemical cell assembly (10) to the fluid volume (66); a fluid outlet port (74) for removing fluid from the fluid volume (66), wherein the cell units (18) extend from the fluid inlet port (72) to the fluid outlet port (74) in the first direction (22).

35. A flow restriction device for an electrochemical cell assembly (10), preferably fuel cell assembly or electrolysis cell assembly, said flow restriction device (112) comprising at least one flow restriction member (114-1 , 114-2) and being configured to reduce or prevent fluid flow along an outer flow path (84)through gaps (88-1 , 88-2) between flange portions (90-1 , 90-2) of adjacent cell units (18) in an electrochemical cell assembly (10).

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