EP4533576A1

EP4533576A1 - Cell unit with securely fixed seal around manifold opening

Info

Publication number: EP4533576A1
Application number: EP22732469.6A
Authority: EP
Inventors: Timo Kegel; Tomasz DOMANSKI
Original assignee: Robert Bosch GmbH; Ceres Power Ltd
Current assignee: Robert Bosch GmbH; Ceres Power Ltd
Priority date: 2022-05-31
Filing date: 2022-05-31
Publication date: 2025-04-09
Also published as: CN119301782A; WO2023232236A1; TW202349775A

Abstract

The invention relates to a cell unit, comprising a support plate (12), an interconnector plate, and at least one gasket (18), wherein a through-hole (34) is provided in the cell unit, said through-hole extending through the support plate and the interconnector plate to form a fluid port (36), said through-hole being provided with a gasket located on a side of the support plate facing away from the interconnector plate, said gasket comprising an opening (40) delimited by an inner surface (42) of said gasket and being in alignment with said through-hole, wherein the cell unit (10) further comprises a positioning fixture (46) being configured and arranged to contact said gasket on its inner surface and to hold said gasket aligned with said through-hole by a form-fit in the plane perpendicular to the stacking direction. The invention also relates to a cell stack and a method of manufacturing a cell stack.

Description

Title

CELL UNIT WITH SECURELY FIXED SEAL AROUND MANIFOLD OPENING

State of the Art

The invention relates to the field of electrochemical cell units and stacks thereof, and, in particular, relates to the field of fuel cells and electrolyser cells, and stacks thereof. More specifically, the invention relates to the field of solid oxide cells (SOCs), including metal-supported solid oxide cells of either the oxidizer type (SOFC) or electrolyser type (SOEC), and stacks thereof.

Fuel cells and electrolyser cells are examples of electrochemical cells. Fuel cells are energy conversion devices that allow for conversion of electrochemical fuel to electricity. Electrolyser cells are fuels cells running in reverse mode, i.e. using electricity to generate chemicals. Reversible cells are capable of operating in both modes. Such electrochemical cells typically comprise three electrochemical layers, that is a fuel electrode, an electrolyte, and an air or oxidant electrode, which are commonly arranged in layers. Said electrochemical layers may be configured to allow for conversion of electrochemical fuel to electricity (fuel cells) or for generating chemicals using electricity (electrolyser cells).

Solid oxide cells (SOCs) are a particular class of electrochemical cells, with the electrolyte layer being formed from a solid oxide, such as e.g. 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). SOFCs use an electrochemical conversion process that oxidises fuel to produce electricity. For this, a fuel, or reformed fuel, contacts an fuel electrode and an oxidant, such as air or an oxygen rich fluid, contacts the oxidant electrode. The solid oxide electrolyte then conducts negative oxygen ions from the oxidant electrode to the fuel electrode. Hence, for SOFCs, the fuel electrode constitutes the anode and the air or oxidant electrode constitutes the cathode. SOECs are SOCs run in reverse mode compared to SOFCs and are commonly used for the electrolysis of water, in particular for generating hydrogen and oxygen gas. In this case, the fuel electrode constitutes the cathode and the air or oxidant electrode constitutes the anode.

The electrochemical layers may be arranged in layers on a mechanical support plate, e.g. on a metal plate (so-called "metal-supported electrochemical cells"). Such cells typically comprise an interconnector plate overlying the support plate on a side that is facing away from the electrochemical layers, such that a fluid volume (cell space) is enclosed between the support plate and the interconnector plate. In this case, the support plate may have a porous region with the electrochemical layers being deposited upon said porous region such that fuel (e.g. gases) may pass through the pores from the cell space to the electrochemical layers. Furthermore, the cell units usually comprise fluid ports, e.g. in the form of through-holes, to allow for fuel supply to the cell space.

Typically, multiple of such cells are stacked upon one another to form a cell "stack". Then, the fluid ports of a cell may be sealed against the neighbouring cell in the stack by respective gaskets. When such a stack is assembled, usually, significant time and effort must be expended in retaining each gasket in an appropriate location relative to the fluid port.

The present invention seeks to provide a cell unit and a cell stack, that can be manufactured in a cost-efficient and straightforward manner.

Description of the Invention

According to the invention, there is provided a cell unit, preferably an electrochemical cell unit. The cell unit comprises an areally extending support plate for supporting electrochemical layers, an areally extending interconnector (or separator) plate, and at least one gasket. Said support plate and said interconnector plate are overlying one another, and are extending perpendicular to a stacking direction. That is to say, the support plate and the interconnector plate are stacked upon one another along a stacking direction, with the support plate and the interconnector plate being areally extending perpendicular to said stacking direction. Preferably, the support plate and the interconnector plate are arranged in parallel to each other and, optionally, contact each other in areal fashion. According to the invention, at least one through-hole is provided in the cell unit, said through-hole extending through the support plate and the interconnector plate to form a fluid port of the cell unit for supplying fluid, in particular fuel, to the cell unit. Preferably, at least one through-hole is provided in each of the support plate and the interconnector plate of the cell unit, said through-hole of the support plate and the said through-hole of interconnector plate being arranged coaxially to each other. According to the invention, said through-hole (fluid port) of the cell unit is provided with a gasket. This, however, does not exclude that the cell unit may comprise additional through-holes that fulfill different purpose and are not provided with a gasket. The gasket preferably is configured to seal the through-hole of the cell unit (fluid port) against a neighboring cell in a cell stack. The gasket is located on a side of the support plate that is facing away from the interconnector plate. Preferably, the gasket is supported by the support plate. More preferably, the gasket is in direct contact with a surface of the support plate, said surface facing away from the interconnector plate, and preferably extending perpendicular to the stacking direction. The gasket comprises an opening, said opening being delimited by an inner surface of said gasket and being in alignment with said through-hole (fluid port) of the cell unit such that the gasket is arranged around said through-hole (i.e. around the fluid port). The cell unit further comprises a positioning fixture for said gasket. The positioning fixture is configured to hold the gasket aligned by a form-fit perpendicular to the stacking direction. More specifically, the positioning fixture is configured and arranged to contact the gasket on its inner surface and to hold the gasket aligned with said through-hole (fluid port) of the cell unit by a form-fit in the plane perpendicular to the stacking direction. Preferably, the positioning fixture is arranged within the extent of the through-hole through the support plate.

Thus, the positioning fixture provides an integrated measure to hold the gasket aligned with respect to the through-hole assigned to it. In particular, the positioning fixture may hold the gasket in position during assembly of a cell stack comprising multiple of such cell units. This allows for easy manufacturing of the cell stack, as the time and effort typically required for retaining each gasket in an appropriate location during assembly can be eliminated. For example, the usual gluing of the gaskets to the support plate or the interconnector plate can be omitted. Preferably, the positioning fixture is configured to define an exterior periphery for accommodating the inner surface of the gasket such that the gasket is held aligned with said through-hole by a form-fit in the plane perpendicular to the stacking direction.

It may be further advantageous if the positioning fixture is configured such that the gasket is force-fittingly (i.e. by a friction lock) held in place by the positioning fixture along the stacking direction, that is in a direction perpendicular to the areal extent of the support plate. For this, the positioning fixture may by configured such that the positioning fixture is biased against the inner surface of the gasket in a direction perpendicular to the stacking direction. Thus, the gasket may be held in a loss-proof manner by the positioning fixture.

Preferably, the support plate and/or the interconnector plate are formed from metal or metal alloy. That is to say, the support plate and/or the interconnector plate preferably are metal or metal alloy plates, e.g. metal foils.

The cell unit may further comprise, in particular planar, electrochemical layers (cell chemistry layers) to form a cell. The electrochemical layers may comprise a fuel electrode layer, an electrolyte layer and an air or oxidant electrode layer. The electrochemical layers preferably are arranged (preferably deposited as thin coatings or films) on and supported by the support plate. The support plate may have a porous region surrounded by a non-porous region with the electrochemical layers being deposited upon the porous region (preferably on the side that is facing away from the interconnector plate). Thus, fuel (e.g. gases) may pass through the pores to the electrochemical layers. The support plate and the interconnector plate may be configured such that a cell space (fluid volume) is enclosed between the support plate and the interconnector plate. Thus, fluid may pass form the cell space through the pores of the porous region to the electrochemical layers. The cell repeat units may be fuel cell units, electrolyser cell units or reversible cell units. The cell repeat units may be solid oxide fuel cell units or solid oxide electrolyser cell units.

Preferably, the positioning fixture extends beyond a surface of the support plate, said surface facing away from the interconnector plate along the stacking direction. That is to say, the positioning fixture preferably protrudes over the surface of the support plate that is facing away from the interconnector plate along the stacking direction. The positioning fixture preferably protrudes into the opening of the gasket. Preferably, the positioning fixture bears against the inner surface of the gasket such that the gasket is held by a form-fit perpendicular to the stacking direction, and optionally, also by a friction-lock along the stacking direction. Preferably, the positioning fixture protrudes over the surface of the support plate to an extent that is less than the thickness of the gasket along the stacking direction, thus allowing for gasket compression during a stacking process. In this context, the positioning fixture may provide a hard stop during assembly and stacking of a stack of cell units.

Preferably, the positioning fixture extends through the through-hole formed in the support plate along the entire thickness of the support plate, and protrudes into the opening of the gasket. That is to say, the positioning fixture preferably extends from the side of the support plate that is facing the interconnector plate through the through-hole in the support plate, and protrudes beyond the surface of the support plate that is facing away from the interconnector plate. This has the advantage, that the positioning fixture may additionally perform a locating function for the support plate.

The positioning fixture may be provided as a separate element. For example, the positioning fixture may be provided by an insert, said insert being held between the interconnector plate and the support plate. Preferably, the positioning fixture forms an integral part or component of the cell stack, for example, such that it is not removable from the cell stack after its assembly. For example, the positioning fixture may comprise a planar part, preferably a metal planar part, that is laid up interleaved between other planar components of the cell stack such as the support plate and interconnector plate.

In some embodiments, the at least one positioning fixture may be provided by the interconnector plate. More preferably, the positioning fixture is integrally formed with the interconnector plate. This allows for easy manufacturing of the cell unit as the number of individual parts can be reduced. In addition, such a positioning fixture may perform a locating function for providing a fixed position for the support plate relative to the interconnector plate. Preferably, the positioning fixture is constituted by one or more raised members integrally formed with the interconnector plate, said raised members preferably extending in a direction locally orthogonal to the areal extent of the interconnector plate, and towards the support plate.

In some embodiments, the positioning fixture may be formed by at least one portion of the interconnector plate bent towards the support plate, preferably bent in a direction locally orthogonal to the areal extent of the interconnector plate. That is to say, the positioning fixture may be formed by bending one or more portions of the interconnector plate in a direction towards the support plate, i.e. along the stacking direction. For this, it may be advantageous if the interconnector plate ist formed from metal. Preferably, the at least one portion is a portion surrounding the through-hole in the interconnector plate.

According to a general aspect, the positioning fixture may comprise two or more positioning projections, said two or more positioning projections extending towards the support plate, preferably in a direction locally orthogonal to the areal extent of the interconnector plate. The positioning projections preferably are circumferentially, more preferably evenly, distributed around the fluid port of the cell unit. Thus, the positioning fixture may comprise a plurality of raised members that are arranged to define a perimeter for accommodating a gasket outside of the raised members. The two or more positioning projections may be spacedapart from each other by circumferential gaps. Said gaps preferably are configured to allow for fluid flowing from the fluid port to a cell space formed between the support plate and the interconnector plate. In some embodiments, the two or more positioning projections may be formed by bending arc-shaped segments or tongues of material of the interconnector plate that is surrounding the through-hole. For this, arc-shaped sections or tongues may be formed in the interconnector plate, preferably before bending (e.g. by embossing or cutting the interconnector plate).

In some embodiments, the positioning fixture may be a ring shaped projection, said ring-shaped projection preferably extending towards the support plate, more preferably locally orthogonal to the areal extend of the interconnector plate. The ring-shaped projection preferably is configured to define an outer perimeter for accommodating the inner surface of the gasket. That is, in the cell unit, the inner surface of the gasket preferably abuts an outer surface of the ring-shaped projection. Preferably, an outer diameter of the ring-shaped projection equals a diameter of the opening of the gasket. In some embodiments, the ring shaped projection may be formed by bending a circular portion of the interconnector plate surrounding the through-hole in a direction locally orthogonal to the areal extent of the interconnector plate. Thus, the ring-shaped projection may delimit the through-hole in the insulation plate.

The ring shaped projection may comprise openings, e.g. bores or stamped shapes, preferably extending radially, that is perpendicular to the stacking direction. Said openings preferably are configured and arranged to allow fluid flow from the fluid port (through-hole) to a cell space formed between the support plate and the interconnector plate.

In some embodiments, the positioning fixture may be constituted by several segments of a ring shaped projection. Thus, each segment may form a positioning projection of the positioning fixture. The segments may be spaced apart by circumferential gaps. Said gaps preferably are configured and arranged to allow fluid flow from the fluid port to a cell space formed between the support plate and the interconnector plate. As set out above with respect to the ringshaped projection, this allows for fluid, in particular fuel, entering and exiting the cell space, and thus supplying the optional electrochemical layers with fluid.

The gasket may be a sealing sheet. The sealing sheet may comprise at least one recess forming the opening of the gasket. The recess may be complementary to the shape of the through-hole. Preferably, the gasket is a sealing ring. Preferably, the gasket, in particular the sealing ring, is arranged coaxially to the through-hole (fluid port) of the cell unit.

According to a general aspect, there may be provided at least one spacer between the support plate and the interconnector plate. The spacer preferably is configured and arranged such that a cell space (fluid volume) is formed between the support plate and the interconnector plate, when the support plate and the interconnector plate are connected.

Preferably, the spacer is arranged around the fluid port provided by the through- hole of the cell unit. The fluid port may for example be a fuel port. Preferably, the spacer comprises an opening in alignment with said fluid port (through-hole of the cell unit). The spacer may be a spacer ring. Alternatively, the spacer may be a spacer plate or spacer sheet having a through-hole forming the opening.

In some embodiments, each fluid port may be provided with a spacer, e.g. in the form of a spacer ring. Alternatively, the cell unit may comprise a single spacer, preferably in the form of a spacer plate, said spacer plate comprising openings, preferably through-holes, at positions locally correspoinding to the through-holes in the support plate and the interconnector plate.

The spacer may be held by the positioning fixture in alignment with said fluid port (through-hole of the cell unit) by a form-fit in the plane perpendicular to the stacking direction. For this, the positioning fixture may extend through the opening in the spacer, when the cell unit is assembled. Preferablythe positioning fixture is configured to contact an inner surface of the spacer, said inner surface delimiting said opening in the spacer, such that the spacer is held aligned with the fluid port assigned to it (through-hole of the cell unit) by a form-fit in the plane perpendicular to the stacking direction. This further eases manufacturing of the cell unit.

Alternatively, the at least one positioning fixture may be provided by the spacer. Thus, the positioning fixture may act as locating feature for the spacer, when being inserted into the through-hole in the support plate. Preferably, the positioning fixture is integrally formed with the spacer. This allows for easy manufacturing of the cell unit as the number of individual parts can be reduced. For example, the positioning fixture may comprise a plurality of circumferentially distributed positioning projections formed integrally with the spacer. The positioning projections may be spaced apart by circumferential gaps allowing for fluid flowing from the fluid port to the cell space formed between the support plate and the interconnector plate. As set out above, the positioning fixture may be a ring shaped projection or may be constituted by several segments of a ring shaped projection formed integrally with the spacer. The ring shaped projection may comprise openings or the segments of the ring shaped projection may be spaced apart by circumferential gaps, said openings or gaps preferably being configured and arranged to allow fluid flow from the fluid port to the cell space formed between the support plate and the interconnector plate. The spacer may comprise radially extending channels or openings to allow fluid flow from the respective fluid port to the cell space formed between the support plate and the interconnector plate. Said channels or openings may be provided by recesses formed in an outer surface of the spacer. Alternatively, said channels or openings may be formed by radial bores in a spacer material. The channels or openings may be provided in the spacer regardless of whether the positioning fixture is provided by the spacer or by any other component of the cell stack, e.g. by the interconnector plate.

Preferably, the spacer is configured and arranged such that the circumferential location of the channels or openings in the spacer overlaps with gaps between positioning projections of the positioning projection (e.g. gaps between a plurality of circumferentially distributed positioning projections or gaps between segments of a ring-shaped projection, see above), or openings defined in a ring-shaped projection. That is to say, the spacer may comprise channels or openings, said channels or openings being arranged at circumferential locations around the fluid port, said locations corresponding to the locations of gaps between positioning projections of the positioning fixture, or to the locations of openings of a ringshaped projection of the positioning fixture. Thus, the spacer may comprise channels or openings, said channels or openings being arranged such that the channels or openings in the spacer are located between adjacent positioning projections (if multiple are present) or (in case of a ring-shaped projection) at positions locally corresponding to the positions of the radial openings of a ring shaped projection. This allows for fluid flowing from the fluid port to the cell space.

Alternatively or in addition to providing a spacer between the support plate and the interconnector plate, the cell unit may comprise shaped port features located around the fluid ports. The shaped port feautres preferably are configured and arranged such that a cell space is formed between the support plate and the interconnector plate, when the support plate and the interconnector plate are connected. The shaped port features may be provided by at least one of the interconnector plate or the support plate. The shaped port features may be provided by pressing. The shaped port features may extend towards the other plate. The shaped port features may be dimples. Preferably, elements of the shaped port features are spaced from one another to define fluid pathways between the elements from the fluid port to enable passage of fluid from the fluid port to the cell space. For example, the shaped port features may be configured as described in applicant's earlier WO2020/126486A1 , which is hereby incorporated by reference.

The invention also relates to a cell stack comprising a plurality of cell units as described above. The features and advantages explained above in connection with the cell units as such are also applicable to the cell stack. In the stack, the cell units are stacked upon one another along the stacking direction such that the fluid ports of the cell units together form a fluid pathway along the stacking direction. In the stack, the gaskets are configured to seal the fluid ports of a respective cell unit against a neighbouring cell unit of the stack.

The invention also relates to a method of manufacturing a cell stack. The method comprises a step of providing a plurality of cell units, preferably cell units constituted as decribed above. The step of providing said cell units comprises the substeps of: providing a support plate having at least one through-hole; providing at least one gasket, preferably one gasket for each through-hole in the support plate; providing an interconnector plate having at least one through-hole and at least one positioning fixture for the at least one gasket, preferably one positioning fixture for each gasket; overlying the support plate and the interconnector plate one upon the other along a stacking direction such that the at least one positioning fixture of the interconnector plate extends through the at least one through-hole formed within the support plate; positioning the at least one gasket on a side of the support plate that is facing away from the interconnector plate such that the at least one gasket is arranged around the at least one through-hole (fluid port of the cell unit) and abuts the positioning fixture with its inner surface such that the gasket is form-fittingly held in place by the positioning fixture to be in alignment with the through-hole formed within the support plate.

The method further comprises a step of stacking the plurality of cell units one upon another along the stacking direction, preferably such that the fluid ports of the cell units together form a fluid pathway along the stacking direction. According to an alternative embodiment, the step of providing the cell units may comprise the substeps of: providing a support plate having at least one through-hole; providing an interconnector plate having at least one through-hole; providing at least one gasket, preferably one for each through-hole in the support plate providing at least one spacer, preferably a spacer plate, comprising at least one, preferably integrally formed, positioning fixture for the at least one gasket; overlying the support plate, the at least one spacer, and the interconnector plate one upon the other along a stacking direction such that the at least one positioning fixture of the spacer extends through the at least one through- hole formed within the support plate; positioning the at least one gasket on a side of the support plate that is facing away from the interconnector plate such that the at least one gasket is arranged around the at least one through-hole (fluid port of the cell unit) and abuts the positioning fixture with its inner surface such that the gasket is form-fittingly held in place by the positioning fixture to be in alignment with the through-hole formed within the support plate. The step of providing the at least one spacer may comprise the step of providing one spacer (e.g. in the form of a spacer ring) for each through-hole in the support plate, each spacer comprising one positioning fixture. Alternatively, the step of providing the at least one spacer may comprise the step of providing a, preferably single, spacer plate, said spacer plate comprising one or more through-holes and one or more positioning fixtures located at positions corresponding to the through-holes in the support plate and the interconnector plate.

As set above, the through-holes of the support plate preferably are located at positions locally corresponding to the through-holes of the interconnector plate. Thus, the support plate and the interconnector plate preferably are stacked one upon the other along the stacking direction such that the through-holes in the support plate and the through-holes in the interconnector plate are arranged coaxially to each other. The step of providing the cell units may further comprise a step of connecting the support plate and the interconnector plate of a respective cell unit, preferably using a welding process, more preferably using a laser welding process. As such, the interconnector plate and the support plate of a respective cell unit can be handled as one piece, thus allowing for ease of manufacture.

The method may further comprise a step of connecting adjacent cell units by joining the interconnector plate of one cell unit to the support plate of the adjacent cell unit, preferably using a welding process, more preferably a laser welding process.

The step of providing a support plate having at least one through-hole may comprise the substeps of providing a support plate and processing the support plate to form at least one through-hole, e.g. by drilling or stamping. The step of providing an interconnector plate having at least one through-hole may comprise the substeps of providing an interconnector plate and processing the interconnector plate to form at least one through-hole, e.g. by drilling or stamping.

The step of providing an interconnector plate having at least one positioning fixture may comprise the substeps of providing an interconnector plate and forming at least one positioning fixture, preferably one or more positioning projections, by bending at least one a section of the interconnector plate.

Further embodiments are derivable from the following description and the drawing.

In the drawings:

Fig. 1 shows an exploded perspective view of an interconnector plate and a support plate of an exemplary embodiment of a cell unit;

Fig. 2 shows perspective view of a fluid port of a cell unit;

Fig. 3a shows a perspective sectional view of the fluid port according to Fig. 2 ; and Fig. 3b shows a detail of Fig 3a; Fig. 4 shows a perspective sectional view of an interconnector plate and a spacer.

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

Figure 1 schematically shows an exploded view of an assembly of a cell unit 10 according to an exemplary embodiment (simplified to illustrate certain aspects of the invention). The cell unit 10 comprises a support plate 12 and an interconnector plate 14, stacked upon one another along a stacking direction 16. As set out in detail below, the cell unit 10 further comprises a plurality of gaskets 18 (not shown in Fig. 1, see Fig. 2ff.).

The support plate 12 and the interconnector plate 14 preferably are connected such that a fluid volume (cell space 20) is enclosed between the support plate 12 and the interconnector plate 14. For this, the cell unit 10 may comprise at least one spacer 22 located between the support plate 12 and the interconnector plate 14 (details below). Alternatively, as set out above, the cell unit 10 may comprise shaped port features acting as spacers. Preferably, the support plate 12 and the interconnector plate 14 are bonded using a welding, in particular laser welding, process. Preferably, the support plate 12 and the interconnector plate are formed from metal or metal alloy.

As set out above, the cell unit 10 may comprise electrochemical layers (not shown) to form a fuel cell or electrolyser cell. Said electrochemical layers preferably are provided on a side 24 of the support plate 12 that is facing away from the interconnector plate 14, preferably as thin coatings on a surface 38 of the support plate 12. The support plate 12 may have a porous region 26 (only rectangular perimeter indicated in Fig. 1 ) surrounded by a non-porous region 28 with the electrochemical layers being deposited upon the porous region 26. Hence, fuel may pass through the pores from the cell space 20 to the electrochemical layers. For example, the support plate 12 may be provided with multiple small holes to enable fluid in the cell space 20 to be in contact with the side of the electrochemical layers that is closest to the support plate 12. As shown in Fig. 1 , the support plate 12 and the interconnector plate 14 each comprise four through-holes 30, 32 extending along the stacking direction 16. In embodiments not shown, the support plate 12 and the interconnector plate 14 may comprise more or less through-holes 30, 32. The through-holes 30 in the support plate 12 and the through-holes 32 in the interconnector plate 14 preferably are arranged coaxially to each other such that - when the support plate 12 and the interconnector plate 14 are connected - each pair of through- holes 30, 32 forms a through-hole 34 extending through the cell unit 10 along the stacking direction 16.

As set out in detail below, the through-holes 34 (through-holes 30, 32) are in fluid communication with the cell space 20, allowing for fluid exiting and entering the cell space 20. Thus, the through-holes 34 form fluid ports 36 of the cell unit 10.

Referring to Fig. 2, there is shown a detail of a cell unit 10 in the area of a fluid port 36 from a perspective view to the side 24 of the support plate 12 that is facing away from the interconnector plate 14. That is, the cell unit 10 shown in Fig. 2 is oriented upside down relative to the cell unit 10 shown in Fig. 1.

As can be seen from Fig. 2, the fluid port 36 (through-hole 34) is provided with a gasket 18, configured to seal the fluid port 36 against a neighbouring cell unit 10, when the cell unit 10 is integrated into a cell stack (not shown) comprising a plurality of cell units 10 stacked upon one another along the stacking direction 16.

The gasket 18 is located on the side 24 of the support plate 12 that is facing away from the interconnector plate 14. In the example, the gasket 18 is in direct contact with the surface 38 of the support plate 12, said surface 38 facing away from the interconnector plate 14. The gasket 18 comprises an opening 40, said opening 40 being delimited by an inner surface 42 of the gasket 18 (see Fig. 3b). Referring to Fig. 2, it can be seen that the opening 40 of the gasket 18 is positioned coaxially to the fluid port (36), that is coaxially to the through-hole 30 in the support plate 12 and to the through-hole 32 in the interconnector plate 14. In the example, the gasket 18 takes the form of a sealing ring 44.

The cell unit 10 futher comprises a positioning fixture 46 configured to hold the gasket 18 aligned with the fluid port 36 (through-hole 34) assigned to it. In the example, the positioning fixture 46 comprises a plurality of positioning projections 48 formed integrally with the interconnector plate 14 (see Fig. 2 and 3a). More specifically, a plurality of portions 50 (in the example four portions 50) of the interconnector plate 14, said portions 50 surrounding the through-hole 32 in the interconnector plate 14, are bent towards the support plate 12 to form the positioning projections 48 of the positioning fixture 46. Preferably, said portions 50 are bent such that they extend locally orthogonal to the areal extent of the interconnector plate 14 (see e.g. Fig. 3b). As shown in Fig. 2, the positioning projections 48 (bent portions 50) are, preferably evenly, distributed around the circumference of the fluid port 36, with circumferential gaps 52 being provided between adjacent positioning projections 48.

Exemplarily, arc-shaped portions may be formed in the material of the interconnector plate 14 surrounding the through-hole 32 (e.g. by embossing or cutting the interconnector plate), whereby alternately one portion is bent (forming the positioning projections 48) and one portion is not bent (see arc-shaped portions 54 in Fig. 2 and 3a).

Referring to Fig. 3b, it can be seen that the positioning projections 48 (bent portions 50) extend through the through-hole 30 in the support plate 12, and protrude beyond the surface 38 of the support plate 12 into the opening 40 of the gasket 18. As shown in Fig. 3b, the positioning projections 48 are in contact with the inner surface 42 of the gasket 18, thus holding the gasket 18 in place by a form-fit perpendicular to the stacking direction.

In embodiments not shown, the positioning fixture 46 may comprise a ringshaped (circular) projection, e.g. formed by bending material surrounding the through-hole 32 in the interconnector plate 14 towards the support plate 12.

In the embodiment shown, the cell unit 10 further comprises an optional spacer 22, exemplarily in the form of a spacer ring 56. Preferably, each fluid port 36 is provided with a respective spacer 22.

As can be seen from Fig. 4, the spacer 22 (spacer ring 56) is supported by the interconnector plate 14. In the example, the spacer 22 is in direct contact with a surface 58 of the interconnector plate 14, said surface 58 facing the support plate 12. The spacer 22 is provided around the through-hole 32 in the interconnector plate 14 and comprises an opening 60 in alignment with the through-hole 32. Preferably, the opening 60 of the spacer 22 is located coaxially to the through- hole 32.

As shown in Fig. 4, the spacer 22 preferably is held in place by the positioning fixture 46 in an analogous fashion as the gasket 18. More specifically, the positioning projections 48 preferably are in contact with a inner surface 62 of the spacer 22 such that the spacer is held in fixed position by a form-fit perpendicular to the stacking direction 16.

In the example, the spacer 22 comprises radially extending channels 64 at circumferential positions locally corresponding the gaps 52 between the positioning projections 48 (bent portions 50), that is at positions corresponding to the arc-shaped portions 54. Thus, there is provided a fluid connection between the fluid port 36 and the cell space 20. In embodiments not shown, the channels 64 may take the form of openings or bores in the spacer 22.

In embodiments not shown, the spacer 22 may be a spacer sheet or spacer plate comprising through-holes complementary to the through-holes 32.

Claims

1. A cell unit (10), comprising: a support plate (12), an interconnector plate (14), and at least one gasket (18), the support plate (12) and the interconnector plate (14) overlying one another and extending perpendicular to a stacking direction (16), wherein at least one through-hole (34) is provided in the cell unit (10), said through-hole (34) extending through the support plate (12) and the interconnector plate (14) to form a fluid port (36) of the cell unit (10), said through-hole (34) being provided with the at least one gasket (18), said gasket (18) being located on a side (24) of the support plate (12) that is facing away from the interconnector plate (14), said gasket (18) comprising an opening (40), said opening (40) being delimited by an inner surface (42) of said gasket (18) and being in alignment with said through-hole (34) of the cell unit (10) such that said gasket (18) is arranged around said through-hole (34), wherein the cell unit (10) further comprises a positioning fixture (46) for said gasket (18), said positioning fixture (46) being configured and arranged to contact said gasket (18) on its inner surface (42) and to hold said gasket (18) aligned with said through-hole (34) by a form-fit in the plane perpendicular to the stacking direction (16).

2. A cell unit (10) according to claim 1 , wherein the positioning fixture (46) extends beyond a surface (38) of the support plate (12) that is facing away from the interconnector plate (14), and protrudes into the opening (40) of the gasket (18).

3. A cell unit (10) according to any one of the preceding claims, wherein the positioning fixture (46) extends through the through-hole (30) formed in the support plate (12) along the entire thickness of the support plate (12), and protrudes into the opening (40) of the gasket (18).

4. A cell unit (10) according to any one of the preceding claims, wherein the positioning fixture (46) is provided by the interconnector plate (14). . A cell unit (10) according to any one of the preceding claims, wherein the positioning fixture (46) is integrally formed with the interconnector plate (14).

6. A cell unit (10) according to any one of the preceding claims, wherein the positioning fixture (36) is formed by at least one portion (50) of the interconnector plate (14) bent towards the support plate (12). . A cell unit (10) according to any one of the preceding claims, wherein the support plate (12) and/or the interconnector plate (14) are formed from metal. . A cell unit (10) according to any one of the preceding claims, wherein the positioning fixture (46) comprises a plurality of circumferentially distributed positioning projections (48). . A cell unit (10) according to the preceding claim, wherein the positioning projections (48) are spaced apart by circumferential gaps (52) allowing for fluid flowing from the fluid port (36) to a cell space (20) formed between the support plate (12) and the interconnector plate (14). 0. A cell unit (10) according to any one of claims 1 to 7, wherein the positioning fixture (46) is a ring shaped projection or is constituted by several segments of a ring shaped projection. 1. A cell unit (10) according to the preceding claim, wherein the ring shaped projection comprises openings or the segments of the ring shaped projection are spaced apart by circumferential gaps, said openings or gaps configured and arranged to allow fluid flow from the fluid port (36) to a cell space (20) formed between the support plate (12) and the interconnector plate (14). 2. A cell unit (10) according to any one of the preceding claims, wherein the gasket (18) in stacking direction (16) is force-fittingly held by the positioning fixture (46). 13. A cell unit (10) according to any one of the preceding claims, wherein the gasket (18) is a sealing ring (44) or sealing sheet.

14. A cell unit (10) according to any one of the preceding claims, wherein at least one spacer (22) is provided between the support plate (12) and the interconnector plate (14).

15. A cell unit (10) according to the preceding claim, wherein the spacer (22) is arranged around the fluid port (36) provided by the through-hole (34).

16. A cell unit (10) according to the preceding claim, wherein the spacer (22) comprises an opening (60) in alignment with said fluid port (36), and wherein the spacer (22) is held by the positioning fixture (46) in alignment with said fluid port (36) by a form-fit in the plane perpendicular to the stacking direction (16).

17. A cell unit (10) according to the any of claims 15 or 16, wherein the spacer (22) comprises radially extending channels (64) or openings to allow fluid flow from the respective fluid port (36) to a cell space (20) formed between the support plate (12) and the interconnector plate (14).

18. A cell unit (10) according to the preceding claim, wherein the circumferential location of the channels (64) or openings overlaps with gaps (52) between projections (48) of the positioning fixture (46).

19. A cell unit (10) according to any of claims 14 to 18 when referring to any of claims 1 to 3, wherein the positioning fixture (46) is provided by the spacer (22).

20. A cell stack comprising a plurality of cell units (10) according to any one of claims 1 to 19, the cell units (10) being stacked upon one another along the stacking direction (16) such that the fluid ports (36) of the cell units (10) together form at least one fluid pathway along the stacking direction (16).

21. Method of manufacturing a cell stack, comprising: a) providing a plurality of cell units (10), the step of providing said cell units (10) comprising: providing a support plate (12) having at least one through-hole (30); providing at least one gasket (18); providing an interconnector plate (14) having at least one through- hole (32), said interconnector plate (14) providing at least one positioning fixture (46) for the at least one gasket (18); overlying the support plate (12) and the interconnector plate (14) one upon the other along a stacking direction (16) such that the at least one positioning fixture (46) of the interconnector plate (14) extends through the at least one through-hole (30) formed within the support plate (12); positioning the at least one gasket (18) on a side (24) of the support plate (12) that is facing away from the interconnector plate (14) such that the at least one gasket (18) is arranged around the at least one through-hole (30) and is form-fittingly held in place by the positioning fixture (46) to be in alignment with the through-hole (30) formed within the support plate; b) stacking the plurality of cell units (10) one upon another along the stacking direction (16).

22. Method according to claim 21 , wherein the cell units (10) are in accordance with any one of claims 1 to 18.

23. Method according to any one of claims 21 or 22, further comprising: connecting the support plate (12) and the interconnector plate (14) of each cell unit (10) using a welding process, preferably using a laser welding process.

24. Method according to any one of claims 21 to 23, further comprising: connecting adjacent cell units (10) by joining the interconnector plate (14) of one cell unit (10) to the support plate (12) of the adjacent cell unit (10) using a welding process, preferably a laser welding process.

25. Method according to any one of claims 21 to 24, wherein the at least one positioning fixture (46) is formed by bending at least one a portion (50) of the interconnector plate (14).