WO2025119498A1

WO2025119498A1 - Electrochemical cell stack and method of manufacturing thereof

Info

Publication number: WO2025119498A1
Application number: PCT/EP2023/084962
Authority: WO
Inventors: Tomasz DOMANSKI; Jonathan SKILTON; Cameron VICKERY
Original assignee: Robert Bosch GmbH; Ceres Power Ltd
Current assignee: Robert Bosch GmbH; Ceres Power Ltd
Priority date: 2023-12-08
Filing date: 2023-12-08
Publication date: 2025-06-12
Anticipated expiration: 2026-06-08

Abstract

The invention relates to an electrochemical cell stack, comprising a plurality of electrochemical cell units (12) that are stacked upon one another along a stacking direction (14), wherein each cell unit comprises a cell layer having at least one electrochemically active cell chemistry region, and an interconnector plate (18), said cell layer and said interconnector plate overlie one another and are attached to each other to enclose a fluid volume therebetween, adjacent cell units cooperate with each other such that movement of the cell units relative to each other in a direction perpendicular to the stacking direction is limited or blocked. The invention also relates to electrochemical cell units and a method of manufacturing an electrochemical cell stack.

Description

Title: Electrochemical cell stack and method of manufacturing thereof

Specification

The invention relates to the field of electrochemical cell units, in particular, fuel cell units and electrolyser cell units. More specifically, the invention relates to an electrochemical cell stack, an electrochemical cell unit, and a method of manufacturing an electrochemical cell stack.

Fuel cells and electrolyser cells are examples of electrochemical cells. Fuel cells are energy conversion devices that allow for conversion of fuel 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 H2O into hydrogen and 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).

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).

Each electrochemical cell unit typically comprises a cell layer comprising the electrochemically active layers, and an interconnector plate attached to the cell layer such that an inner fluid volume is enclosed between the cell layer and the interconnector plate. The fluid volume serves to supply operating fluid (e.g. fuel in case of fuel cells) to the electrochemically active layers.

Examples of such electrochemical cell units are known e.g. from WO 2020/126486 Al or WO 2021/110539 Al. Typically, multiple of such cell units are stacked upon one another to form a "stack" of cell units, also referred to as electrochemical cell stack.

The present invention seeks to increase stability and thus performance of an electrochemical cell stack.

According to the invention, there is provided an electrochemical cell stack according to claim 1. Preferably, the electrochemical cell stack is a fuel cell stack or an electrolyser cell stack. The electrochemical cell stack comprises a plurality of electrochemical cell units that are stacked upon one another along a stacking direction. Each cell unit comprises a cell layer having at least one electrochemically active cell chemistry region, and an interconnector plate. The cell layer and the interconnector plate overlie one another and are, preferably sealingly, attached to each other such that a fluid volume is enclosed between the cell layer and the interconnector plate. The fluid volume preferably serves to supply operating fluid (e.g. fuel in case of fuel cells) to the at least one electrochemically active cell chemistry region. The electrochemical cell units are configured and arranged in the electrochemical cell stack such that adjacent cell units cooperate with each other to limit or block movement of the cell units relative to each other in a direction perpendicular to the stacking direction. Preferably, adjacent cell units in the electrochemical cell stack cooperate with each other such a translational and/or a rotational movement of the cell units relative to each other in a plane perpendicular to the stacking direction is limited or blocked. Thus, adjacent cell units may cooperate with each other such that they cannot translate relative to each other in a direction perpendicular to the stacking direction and/or rotate relative to each other about a rotational axis parallel to the stacking direction.

The proposed configuration allows for precise positioning of the cell units relative to each other and aids maintaining the cell units in fixed position relative to each other in the electrochemical cell stack, thus increasing stability of the cell stack. The proposed configuration also eases manufacture of the cell stack as it can hold the cell units in place during assembly or preconditioning of the.

The adjacent cell units may cooperate directly with each other. Thus, adjacent cell units may contact each other to limit or block movement (sometimes with an electrically insulating coating on one of their interfacing surfaces). Alternatively, the adjacent cell units may cooperate indirectly with each other, e.g. via a further component arranged between them. For example, the cell stack may comprise gaskets that are interposed between adjacent cell units. In such embodiments, adjacent cell units may cooperate with each other via one or more of said gaskets.

The cell layer may comprise a support plate, preferably metal support plate (e.g. metal foil) having at least one electrochemically active cell chemistry region. In such embodiments, the support plate and the interconnector plate may overlay one another and may be, preferably sealingly, attached to each other to enclose a fluid volume therebetween. In preferred implementations, the support plate carries electrochemically active layers on a side that faces away from the interconnector plate. Preferably, the support plate carries the electrochemically active layers over a porous region such that such that fluid (e.g. fuel in case of fuel cells) may pass through the pores from the fluid volume to the electrochemically active layers.

Alternatively, the cell layer may comprise self-supporting electrochemically active layers. In such embodiments, the interconnector plate may be attached directly to the electrochemically active layers.

The electrochemical cell stack may comprise further components additional to the electrochemical cell units.

The electrochemical cell stack may comprise one or more gaskets. Preferably, the electrochemical cell stack comprises a plurality of gaskets that are interposed between the cell units. Preferably, between adjacent cell units, at least one gasket is disposed.

In some embodiments, the cell units may each comprise at least one, preferably two or more fluid ports, preferably in the form of through-holes, said fluid ports allowing for fluid entering and exiting the fluid volume between the cell layer and the interconnector plate. The through-holes may take any shape, for example rectangular or hexagonal, but are preferably circular. In such embodiments, the electrochemical cell stack may comprise gaskets around said fluid ports.

Preferably, the gaskets are electrically insulating. Preferably, the gaskets are formed from a vermiculite material. In some preferred embodiments, adjacent cell units are held aligned relative to each other in a plane perpendicular to the stacking direction by a form-fit connection or interlocking connection acting between them. That is to say, adjacent cell units may cooperate in a form-fitting or interlocking manner.

The form-fit connection may be formed by a face of a first cell unit, in particular a face of the interconnector plate or the cell layer (support plate), said face being directed radially outwards with respect to the stacking direction, and by a face of a second, adjacent cell unit, said face being directed radially inwards and opposed to said face of the first cell unit. The face of the first cell unit and the face of the second, adjacent cell unit may abut each other. Alternatively, the face of the first cell unit and the face of the second, adjacent cell unit may cooperate via an additional component, e.g. a gasket, disposed between them.

In some embodiments, each cell unit comprises at least one first connection portion and at least one second connection portion. Preferably, the first connection portion of a cell unit is configured to cooperate with a second connection portion of an adjacent cell unit, in particular to limit or block movement of the adjacent cell units relative to each other in a direction perpendicular to the stacking direction.

In the cell stack, preferably, the cell units are arranged such that a first connection portion of a cell unit (directly or indirectly, e.g. via a gasket positioned therebetween) cooperates with a corresponding second connection portion of an adjacent cell unit, in particular to limit or block movement of the adjacent cell units relative to each other in a direction perpendicular to the stacking direction and/or to prevent rotational movement of the cell units about a rotational axis parallel to the stacking direction.

Preferably, each first connection portion of a cell unit is associated with a corresponding second connection portion of an adjacent cell unit.

In preferred embodiments, the first connection portion of a cell unit cooperates with an associated second connection portion of an adjacent cell unit to form a form-fit connection acting in a plane perpendicular to the stacking direction. The first and second connection portions of adjacent cell units may be in direct contact with each other. Alternatively, the first and second connection portions of adjacent cell units may cooperate indirectly via a component disposed between them.

In preferred embodiments, there is provided at least one gasket between the first connection portion of a cell unit and the cooperating second connection portion of an adjacent cell unit. Preferably, the at least one gasket is arranged such that forces between said first and second connection portions of adjacent cell units are transmitted via said gasket. Preferably, the at least one gasket is electrically insulating.

Preferably, the at least one first connection portion and the at least one second connection portion of a cell unit are located on opposite sides of said cell unit. Thus, each cell unit may comprise at least one first connection portion on a first side of the cell unit, and at least one second connection portion on an opposing second side of the cell unit. In preferred implementations, the at least one first connection portion is located on the outwardly facing side of the interconnector plate and the at least one second connection portion is located on the outwardly facing side of the cell layer, in particular of the support plate.

In some embodiments, the first and second connection portions of a cell unit protrude in opposite directions along the stacking direction.

In some embodiments, the at least one first connection portion of a cell unit is provided by, preferably integrally formed with, the interconnector plate of said cell unit.

In some embodiments, the least one second connection portion of a cell unit is provided by the cell layer. Preferably, the cell layer comprises a support plate which carries the at least one electrochemically active cell chemistry region, and the least one second connection portion is provided by, preferably integrally formed with, said support plate.

In some embodiments, the at least one first connection portion of a cell unit is provided by, preferably integrally formed with, the interconnector plate of said cell unit and the at least one second connection portion of said cell unit is provided by, preferably integrally formed with, the support plate of the cell layer.

In other embodiments, both of the at least one first connection portion and the at least one second connection portion of a cell unit are provided by the same plate, i.e. either by the interconnector plate or the support plate. For example, both of the at least one first connection portion and the at least one second connection may be provided by, preferably integrally formed with, the interconnector plate. Alternatively, wherein the cell layer comprises a support plate, both of the at least one first connection portion and the at least one second connection portion may be provided by, preferably integrally formed with, the support plate. This eases manufacturing of the cell units as forming the connection portions is limited to one of the two plates.

In some embodiments, each cell unit comprises a single first connection portion and a single second connection portion. In other embodiments, each cell unit comprises at least two first connection portions and at least two second connection portions.

In some embodiments, each pair of associated first and second connection portions of adjacent cell units itself is configured and cooperates such that translational and rotational movement of adjacent cell units relative to each other in a plane perpendicular to the stacking direction is limited or blocked.

In some embodiments, the at least one first connection portion comprises at least two (spatially separated) first connection portions and the at least one second connection portion comprises at least two (spatially separated) second connection portions, wherein the first and second portions are arranged and configured such that such that rotational movement around the stacking direction, preferably translational and rotational movement of adjacent cell units relative to each other in a plane perpendicular to the stacking direction, is limited or blocked. In such embodiments, each pair of cooperating first and second connection portions itself may allow for rotational movement of the adjacent cell units but the presence of a further pair of cooperating first and second connection portions means that rotational movement of adjacent cell units is limited or blocked. For example, a first pair of cooperating first and second connection portions may surround a first fluid port and a second pair of cooperating first and second connection portions may surround a second fluid port. The first and second connection portions may take various shapes and may be arranged at various positions on the cell unit.

In some embodiments, the at least one first connection portion is one of an outward protrusion and a depression (or recess), and the at least one second connection portion is the other one of a protrusion and a depression (or recess). Preferably, said protrusion and said depression (or recess) are configured such that the protrusion of a cell unit may be received in the depression (or recess) of an adjacent cell unit. In the cell stack, preferably, the protrusion (first or second connection portion) of a cell unit is received in an associated depression or recess (second or first connection portion) of an adjacent cell unit, preferably such that a form-fit connection acting in a plane perpendicular to the stacking direction is formed. Such a configuration is easy to manufacture (e.g. by pressing respective parts of the cell units) and allows for secure alignment of the cell units.

In some embodiments, the interconnector plate has one of a protrusion and a depression (or recess) and cell layer (in particular the support plate of the cell layer) has the other one of a protrusion and a depression (or recess), said protrusion being configured to be received in said depression or recess, preferably to form a form-fit connection. Preferably, said protrusion is integrally formed with the interconnector plate or the support plate. Preferably, said depression or recess is integrally formed with the other one of the interconnector plate and the support plate. The protrusion and/or depression (or recess) may be formed by pressing the interconnector plate or support plate.

In some embodiments, the at least one first connection portion or the at least one second connection portion takes the form of a through-hole formed in the interconnector plate or in the cell layer (in particular in the support plate of the cell layer). Preferably, said through-hole forms a fluid port for transporting fluid between the fluid volume and an exterior of the cell unit. The through-hole(s) may take any shape, for example rectangular or hexagonal, but are preferably circular.

In some embodiments, each cell unit has at least one fluid port for transporting fluid between the fluid volume and an exterior of the cell unit. Preferably, each fluid port is formed by a respective through- hole formed in the cell unit. Preferably, the or each through-hole extends through both of the interconnector plate and the cell layer, in particular through both of the interconnector plate and the support plate of the cell layer, along the stacking direction. In some implementations, the or each fluid port may be formed by a through-hole formed in the interconnector plate and an associated through- hole formed in the cell layer (in particular in the support plate of the cell layer), said through-holes being aligned along the stacking direction.

Preferably, the fluid ports (through-holes) of adjacent cell units are aligned such that they overlay along the stacking direction. A column of aligned fluid ports (through-holes) may form part of a fluid manifold for transporting fluid through the stack along the stacking direction.

In preferred embodiments, the or each through-hole is associated with a first connection portion and a second connection portion. Thus, when optional features are described in the following with regard to "the first connection portion and the second connection portion", this may refer to any pair of first and second connection portions associated with a through-hole.

In some embodiments, the or each through-hole may at least partially be surrounded by a protrusion or a rim of protrusions (or webs). Said protrusion or rim of protrusions may form one of said first and second connection portions. Preferably, the protrusion(s) extend around at least half of the, preferably the full, circumference of the through-hole. Preferably, said protrusion(s) extend along the stacking direction. Such a configuration eases manufacture of the cell units as it allows the connecting portions to be formed together with the through-holes, e.g., by pressing the interconnector plate or the support plate.

In some embodiments, the or each through-hole is delimited by a (circumferential) wall of the interconnector plate or the cell layer (preferably support plate of the cell layer), said wall forming one of said first and second connection portions. In such embodiments, the other one of said first and second connections portions may be take the form of a protrusion extending into the through-hole, preferably such that a radially outward surface of said protrusion abuts said wall.

Preferably, the or each through-hole is associated with a gasket surrounding it, said gasket being disposed between two adjacent cell units. Preferably, said gasket takes the form of a sealing ring having a gasket opening. Preferably, the gasket opening is aligned with the associated through-hole such that the gasket is arranged around said through-hole. Preferably, said gasket is electrically insulating. Preferably, said gasket is formed from a vermiculite material. Preferably, the first connection portion of a cell unit and the second connection portion of an adjacent cell unit (indirectly) cooperate with each other via said gasket surrounding the through-hole. In preferred implementations, each through-hole is associated with a gasket surrounding it, preferably in the form of a sealing ring, and each through-hole is associated with a first connection portion and a second connection portion, wherein said first and second connection portions cooperate with each other via the gasket surrounding said through-hole.

Advantageously, the first connection portion of a cell unit and the second connection portion of an adjacent cell unit associated with a respective through-hole may cooperate with the gasket surrounding said through-hole such that said gasket is held aligned with its associated through-hole. In preferred embodiments, the first connection portion of a cell unit and the second connection portion of an adjacent cell unit associated with a respective through-hole together form a positioning fixture for the gasket surrounding said through-hole, preferably to hold said gasket aligned with the associated through-hole by a form-fit connection in a plane perpendicular to the stacking direction. Thus, the first and second connection portions may fulfill two functions, i.e. a locking function for limiting or blocking relative movement of adjacent cell units, and a positioning function for positioning the gasket relative to the associated through-hole.

In preferred embodiments, the gasket surrounding a respective through-hole takes the form of a sealing ring having an outer perimeter and an inner perimeter, said inner perimeter defining a gasket opening of the gasket. In such embodiments, preferably, the first connection portion of a respective cell unit is configured to engage against, preferably to contact, the outer perimeter of the gasket, and the second connection portion is configured to engage against, preferably to contact, the inner perimeter. In the cell stack, preferably, the first connection portion of a cell unit engages against, preferably contacts, the outer perimeter of the associated gasket and the corresponding second connection portion of an adjacent cell unit protrudes into the gasket opening and engages against, preferably contacts, the inner perimeter of said gasket.

In some embodiments, the first connection portion and the second connection portion each take the form of a, preferably ring-shaped, protrusion or a rim of circumferentially distributed protrusions, wherein the protrusion or protrusions forming the first connection portion and the protrusion or protrusions forming the second connection portion extend in opposite directions along the stacking direction.

In some embodiments, both of the first connection portion, in particular said protrusion or rim of protrusions, and the second connection portion, in particular said protrusion or rim of protrusions, of a cell unit are provided by, preferably integrally formed with, the same one of the interconnector plate or the cell layer (preferably support plate of the cell layer). Preferably, both of the first connection portion, in particular said protrusion or rim of protrusions, and the second connection portion, in particular said protrusion or rim of protrusions, of a cell unit are provided by the interconnector plate. This eases manufacturing as it allows to form the protrusions in the same manufacturing step, e.g. by pressing, which may be the same manufacturing step as other features are provided in the interconnector plate.

In some embodiments, the first connection portion, in particular said protrusion or rim of protrusions, is formed by an inner edge portion or inner edge portions of one of the interconnector plate and the cell layer (preferably support plate of the cell layer) bent in a direction pointing away from the other one of the interconnector plate and the cell layer, said inner edge portion surrounding the through-hole. Thus, the first connection portion may have a component of its direction along the stacking direction.

In some embodiments, the second connection portion, in particular said protrusion or rim of protrusions, is formed by an outer edge portion or outer edge portions of the periphery of one of the interconnector plate and the cell layer (preferably support plate of the cell layer) bent towards the other one of the interconnector plate and the cell layer. Thus, the second connection portion may have a component of its direction antiparallel to the direction of the first connection portion along the stacking direction.

In embodiments in which the second connection portion is provided by, preferably formed integrally with, one of the interconnector plate and the cell layer (preferably support plate of the cell layer), advantageously, said second connection portion may extend around an external perimeter of the other one of said interconnector plate and cell layer or may extend through the other one of said interconnector plate and cell layer, preferably such that the first connection portion, in particular said protrusion or protrusions, protrudes over a surface of said other one of the interconnector plate and the cell layer. According to a further aspect, in embodiments comprising at least one through-hole, said through-hole may be surrounded, preferably delimited, by a conically shaped portion of the cell layer (preferably the support plate of the cell layer) and/or the interconnector plate. The conically shaped portion may take the form of a tapered hollow cylinder surrounding the through-hole. The conically shaped portion may form one or both of said first and second connection portions. Such a configuration - in addition to a secure interlocking of adjacent cell units - facilitates stacking of the cell units as the conically shaped portions provide for a self-aligning function.

In some embodiments, an outer surface of said conically shaped portion forms the first connection portion and an inner surface of said conically shaped portion forms the second connection portion of a cell unit. As used herein, the term "outer surface" of a conically shaped portion refers to the surface of the conically shaped portion that is facing away from the through-hole. As used herein, the term "inner surface" of a conically shaped portion refers to the surface of the conically shaped portion that delimits the through-hole.

Preferably, the conically shaped portion extends out of a predominant plane of the interconnector plate and/or the cell layer (preferably support plate of the cell layer). Preferably, an extent of the conical shaped portion in the stacking direction is at least 2 times, preferably at least 5 times, more preferably at least 10 times, a plate thickness of the interconnector plate or the cell layer along the stacking direction.

In preferred embodiments, the interconnector plate and the cell layer (preferably the support plate of the cell layer) of a cell unit each have a conically shaped portion surrounding the through-hole formed therein. Preferably, said conically shaped portions extend in the same direction along the stacking direction. Preferably, one of said conically shaped portions of a cell unit protrudes into the other one of said conically shaped portions. That is to say, the conically shaped portion of one of said interconnector plate and cell layer (support plate), preferably of the support plate, protrudes into the conically shaped portion of the other one of said interconnector plate and support plate

Preferably, in the cell stack, the conically shaped portions of adjacent cell units protrude into one another. Preferably, the conically shaped portion that protrudes into the other conically shaped portion, particularly an inner surface of said conically shaped portion, forms the second connection portion, and the other conically shaped portion, particularly an outer surface of said other conically shaped portion, forms the first connection portion.

Advantageously, the conically shaped portion of at least one of the interconnector plate and the cell layer (support plate) may have shaped port features, e.g. in the form of dimples, that extend towards the conically shaped portion of the other one of the interconnector plate and the cell layer to keep a fluid flow path between the interconnector plate and the cell layer open.

The conically shaped portions of adjacent cell units may be in direct contact with each other (sometimes with an electrically insulating layer on one or other of the interfacing surfaces). In other embodiments, there is provided a gasket between the conically shaped portion of the interconnector plate of a cell unit and the conically shaped portion of the cell layer (preferably of the support plate of the cell layer) of an adjacent cell unit. Preferably, the gasket is arranged such that forces between the conically shaped portions of adjacent cell units are transmitted via said gasket. Preferably, the gasket is a conical gasket. Most preferably, the gasket is a conical gasket having a circumferential collar. Preferably, the gasket is electrically insulating. Preferably, the gasket is formed from a vermiculite material.

The conically shaped portions may be formed by shaping the interconnector plate and/or the cell layer (support plate). In some implementations, the conically shaped portion of the interconnector plate is formed by bending a portion of the interconnector plate that is surrounding the through-hole out of a predominant plane of the original plate. The conically shaped portion of the cell layer may be formed by bending a portion of the cell layer, preferably of a support plate of the cell layer, that is surrounding the through-hole out of a predominant plane of the original plate.

According to a general aspect, at least some of the cell units, preferably each cell unit, may comprise - alternatively or additionally to the above-described implementations comprising first and second connection portions - a corrugation, wherein the corrugations of adjacent cell units (directly or indirectly) cooperate with each other such that a movement of the cell units relative to each other in a direction perpendicular to the stacking direction and/or a rotational movement of the cell units relative to each other around a rotational axis parallel to the stacking direction is limited or blocked. Such corrugation is easy to manufacture and provides for precise alignment of the cell units relative to each other.

Preferably, each cell unit has a periphery, which surrounds the at least one electrochemically active cell chemistry region, and said periphery comprises the corrugation.

Advantageously, each corrugation comprises at least one upward protrusion extending out of the plane of one side of the cell unit (e.g. forming the first connection portion of the cell unit) and at least one, preferably neighbouring, downward protrusion extending out of the plane of the other side of the cell unit (e.g. forming the second connection portion). The at least one upward protrusion may extend in the stacking direction and the at least one downward protrusion may extend in a direction opposite the stacking direction. Thus, the at least one upward protrusion and the at least one downward protrusion may extend in antiparallel directions.

In preferred embodiments, each corrugation comprises a plurality of alternating upward and downward protrusions. Thus, each corrugation may be a continuous up and down shape.

The corrugation, preferably each upward and downward protrusion, may be provided by forming or pressing the cell layer and/or the interconnector plate.

In the electrochemical cell stack, preferably, each upward protrusion of a cell unit cooperates with a downward protrusion of an adjacent cell unit, preferably such that a movement of the cell units relative to each other in a direction perpendicular to the stacking direction and/or a rotational movement of the cell units relative to each other around a rotational axis parallel to the stacking direction is limited or blocked.

The corrugations of adjacent cell units may abut, i.e. directly contact, each other (sometimes one or both of the contacting surfaces is provided with an electrically insulating coating). Alternatively, the corrugations of adjacent cell units may cooperate indirectly via a further component arranged therebetween. In preferred implementations, the electrochemical cell stack further comprises a gasket between corrugations of adjacent cell units. Preferably, said gasket is electrically insulating. The corrugation of a cell unit may circumscribe at least a portion of the periphery of said cell units. The corrugation of a cell unit may extend around the entire periphery of said cell unit. The corrugation of a cell unit may extend only along part of the periphery of said cell unit.

In some embodiments, the corrugation of a cell unit comprises several spatially separated corrugation segments, each segment extending along part of the periphery of said cell unit. In some embodiments, the corrugation of each cell unit is provided in at least two pairs of corrugation segments, each disposed to opposing sides of the at least one electrochemically active cell chemistry region. This allows for secure blocking of cell movement in multiple directions perpendicular to the stacking direction.

In some embodiments, each cell unit has a generally rectangular at least one electrochemically active cell chemistry region, wherein one pair of corrugation segments is arranged along (part of) one of the short sides and the long sides of the rectangle, and the other pair of corrugation segments is arranged along (part of) the other one of the short sides and the long sides of the rectangle.

The corrugation of a cell unit may be provided in both of the interconnector plate and the cell layer (preferably support plate of the cell layer) of said cell unit.

Alternatively, the corrugation of a cell unit may be provided in only one of the interconnector plate and the cell layer of said cell unit.

Alternatively, the at least one upward protrusion may be formed in one of the cell layer (preferably support plate of the cell layer) and the interconnector plate, and the at least one downward protrusion may be formed in the other one of the cell layer and the interconnector plate.

In some embodiments, one of the interconnector plate and the cell layer (preferably support plate of the cell layer) of a respective cell unit extends past the periphery of the other one of the interconnector plate and the cell layer. In such embodiments, the corrugation or corrugation segments may be provided in a portion of the periphery of said one of the interconnector plate and the cell layer (preferably of the support plate of the cell layer) that extends past the periphery of the other one of the interconnector plate and the cell layer. The above-described concept of limiting or blocking relative movement of adjacent cell units is applicable to cell units of various types. Preferably, the cell units are solid oxide cell units, more preferably solid oxide fuel cell units (SOFCs) or solid oxide electrolyser cell units (SOECs). Most preferably, the cell units are metal-supported solid oxide fuel cell units or electrolyser cell units.

The cell units may be flat or planar. 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.

The electrochemical cell stack may be arranged between end plates disposed to opposing ends of the cell stack, thus forming an electrochemical cell assembly. Preferably, the electrochemical cell stack is held in compression between said end plates.

The invention also relates to such an electrochemical cell assembly comprising an electrochemical cell stack and an end plate disposed to one end of the electrochemical cell stack, preferably two end plates each disposed to opposing ends of the electrochemical cell stack. The electrochemical cell assembly may further comprise a housing surrounding the electrochemical cell stack, preferably to define or enclose a fluid volume. The housing may be a stack enclosure defining a fluid volume containing the cell units. In embodiments comprising one or two end plates, the housing may be welded to one or both of said end plates.

The invention also relates to an electrochemical cell unit for use in an electrochemical cell stack described above. Additional preferred features of the electrochemical cell unit may be realised as described above in connection with the electrochemical cell stack.

The invention also related to an electrochemical cell unit comprising features configured to cooperate (directly or indirectly) with an adjacently stacked cell unit such that movement of the cell units relative to each other in a direction perpendicular to the stacking direction, preferably also rotational movement around a rotational axis parallel to the stacking direction, is limited or blocked. Said features may be configured as described above in connection with the electrochemical cell stack. For example, said features may comprise first and second connection portions as described above. Preferably, said features are configured to cooperate (directly or indirectly) with an adjacently stacked cell unit in an interlocking, in particular form-fitting, manner.

In some embodiments, the cell unit comprises at least one through-hole formed therein, and said features comprise a protrusion or a rim of protrusions (or webs) that at least partially surrounds said through-hole. Alternatively or additionally, the cell unit may comprise a corrugation, which circumscribes at least a portion of a periphery of the cell unit. Preferably, the cell unit comprises at least one electrochemically active cell chemistry region, and said periphery surrounds said at least one electrochemically active cell chemistry region.

Each cell unit may comprise a cell layer comprising at least one electrochemically active cell chemistry region, and an interconnector plate.

The invention also relates to a method of manufacturing an electrochemical cell stack, comprising:

- providing a plurality of cell units, wherein each cell unit comprises at least one first connection portion on a first side of the cell unit and at least one second connection portion on an opposite second side of the cell unit.

- stacking the cell units along a stacking direction such that the or each first connection portion of a respective cell unit cooperates with an associated second connection portion of an adjacent cell unit to limit or block movement of the cell units relative to each other in a direction perpendicular to the stacking direction and/or to limit or block rotational movement of the cell units relative to each other around a rotational axis parallel to the stacking direction.

The advantages and optional features described above in connection with the electrochemical cell assembly are also applicable to the method of manufacturing. In order to avoid unnecessary repetition, reference is made to the above disclosure.

Further embodiments are derivable from the following description and the drawings: Fig. 1 shows a schematic perspective view of an example implementation of an electrochemical cell assembly comprising an electrochemical cell stack;

Fig. 2 shows a cross-sectional view of the electrochemical cell assembly according to Figure 1;

Fig. 3 shows an exploded perspective view of an example implementation of an electrochemical cell unit;

Fig. 4 shows a detail of an electrochemical cell unit according to a first embodiment;

Fig. 5 shows a cross-sectional view of the electrochemical cell unit according to Figure 4;

Fig. 6 shows a detail of a stack comprising two electrochemical cell units according to Figure 4;

Fig. 7 shows an exploded perspective view of the stack according to Figure 6;

Fig. 8 shows a cross-sectional view of a detail of a stack comprising three electrochemical cell unit according to a second embodiment;

Fig. 9 shows a perspective cross-sectional view of the stack according to Figure 8;

Fig. 10 shows a cross-sectional view of a detail of a stack comprising three electrochemical cell unit according to a third embodiment;

Fig. 11 shows a perspective cross-sectional view of the stack according to Figure 10;

Fig. 12 shows a schematic side view of a stack comprising two electrochemical cell unit having a corrugation;

Fig. 13 shows a schematic top view of an electrochemical cell unit according to Figure 12; and

Fig. 14 shows a schematic top view of an electrochemical cell unit alternative to Figure 13.

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 example implementation of an electrochemical cell assembly 200. The electrochemical cell assembly 200 comprises an electrochemical cell stack 10 (hereinafter referred to as cell stack), which is interposed between two end plates 202, 204 disposed to opposing ends of the cell stack 10. Preferably, the cell stack 10 is held in a compressed state between said end plates 202, 204.

In the example, the electrochemical cell assembly 200 further comprises optional insulation plates 206 located between the end plates 202, 204 and the cell stack 10 (see Figures 1 and 2). The electrochemical cell assembly 200 may further comprise one or more current transmission plates (not shown). The current transmission plates may be located between the insulation plates 206 and the cell stack 10.

The electrochemical cell assembly 200 may further comprise a housing 208 surrounding the cell stack 10 (see Figure 2, not shown in Figure 1). The housing 208 may be configured to maintain the cell stack 10 in a compressed state between the end plates 202, 204.

The housing 208 and the end plates 202, 204 together may enclose a fluid volume 210 for first fluid around the cell stack 10. In operation, preferably the first fluid is air or oxidant. During operation of the cell stack 10, the fluid volume 210 may be supplied with first fluid and/or first fluid exhausted from the fluid volume 210 via respective fluid ports provided in one of the end plates 202, 204 or in the housing 208 (not shown).

Figures 1 and 2 are intended to primarily provide an overview of an exemplary use of the electrochemical cell stack 10. The invention, however, is not limited to this specific design.

The electrochemical cell stack 10 comprises a plurality of electrochemical cell units 12 (hereinafter referred to as 'cell units', also referred to as 'cell repeat units'), which are stacked upon one another along a stacking direction 14. In the example, the cell units 12 are configured essentially planar and extend perpendicular to the stacking direction 14.

As set out above, the cell units 12 may be fuel cell units, electrolyser cell units or reversible cell units comprising electrochemically active layers. A preferred configuration of a cell unit 12 will be described below with respect to Figures 2 and 3.

As shown in Figure 3, the cell unit 12 comprises a cell layer 16 and an interconnector plate 18 (also referred to as interconnect or separator plate), which are stacked upon each other along the stacking direction 14.

The cell layer 16 comprises an electrochemically active cell chemistry region 20. In the example, the cell layer 16 comprises a support plate 22 that carries electrochemically active layers 24 (which are deposited or coated) over a porous region (not shown). In other embodiments, the electrochemically active layers 24 may be self-supporting.

Preferably, the interconnector plate 18 and the support plate 22 are formed from metal, more preferably stainless steel.

The interconnector plate 18 and the support plate 22 each have a periphery 26, 28 and a central portion 30, 32 surrounded by the periphery 26, 28. The interconnector plate 18 and the support plate 22 are attached to each other at their peripheries 26, 28, preferably by welding, to enclose a (second) fluid volume 34 therebetween.

In the example, the support plate 22 is a flat component. The interconnector plate 18 is tub-shaped having flanged perimeter features 36 around its periphery 26, preferably formed by pressing the interconnector plate 18 to a concave configuration. As can be seen from Figure 3, the flanged perimeter features 36 extend out of the predominant plane of the interconnector plate 18 to create a concavity (and a convexity to the outside surface) in the interconnector plate 18. In the assembled state of the cell unit 12, said concavity forms the fluid volume 34 enclosed between the interconnector plate 18 and the support plate 22. The fluid volume 34 is in fluid communication with the electrochemically active cell chemistry region 20 (electrochemically active layers 24, specifically a lowermost layer thereof) via said porous region.

In the specific example, the interconnector plate 18 has a structured area 38 in its central portion 30. Specifically, the interconnector plate 18 has optional shaped inward protrusions 40 extending into the fluid volume 34. The inward protrusions 40 form a supporting structure helping to maintain the fluid volume 34 open. The inward protrusions 40 define fluid passageways therebetween. Preferably, the inward protrusions 40 abut the support plate 22.

In the example, the interconnector plate 18, in its structured area 38, further comprises shaped outward projections 42 (see also Figure 2). Said outward projections 42 form contact portions of the cell unit 12 for contacting an adjacent cell unit 12, specifically the electrochemically active cell chemistry region 20 (particularly an outermost layer of the electrochemically active layers 24) of an adjacent cell unit 12. More specifically, the outward projections 42 engage at their ends against an outer surface of the electrochemically active layer 24 of an adjacent cell unit 12. The outward projections 42 define fluid passageways 44 for first fluid (e.g., air or oxidant) to flow between adjacent cell units 18 (see Figure 7), those fluid passageways 44 being part of the first fluid volume 210.

As depicted in Fig. 3, the structured area 38 comprises a plurality of dimpled protrusions formed or pressed in the interconnector plate. In other embodiments, the interconnector plate may not have such a structured area 38, for example it may be formed from other features such as channels.

In order to supply (second) fluid, for example fuel, to the fluid volume 34 between the support plate 22 and the interconnector plate 18 (and thus to the lowermost/innermost layer of the electrochemically active layers 24) or to remove fluid from said fluid volume 34, each cell unit 12 has at least one, in the specific example four, fluid ports 46 in the form of through-holes 48 formed therein (see also Figure 2). Specifically, the interconnector plate 18 and the support plate 22 each have at least one, in the example four, through-holes 48 formed therein, wherein an aligned pair of a through-hole 48 formed in the interconnector plate 18 and the associated through-hole 48 formed in the support plate 22 forms a fluid port 46.

The cell stack 10 further comprises gaskets 50 that are interposed between the cell units 12 and surround the fluid ports 46 (through-holes 48) of the cell units 12. In the specific example, the gaskets 50 take the form of annular sealing rings having a gasket opening 52 (see Figure 3). The gaskets 50 may be formed from an exfoliated vermiculite material.

As shown in Figure 2, the through-holes 48 (fluid ports 46) of adjacent cell units 12 are aligned, wherein an aligned column of the through-holes 48 (fluid ports 46) of the cell units 12 and the gasket openings 52 together forms a fluid channel 54 (also referred to as fluid manifold or chimney) for transporting second fluid between the cell units 12 and the exterior of the cell stack 10.

In the specific example shown in Figure 2, one of said fluid channels 54 may be a fluid inlet channel and one of said fluid channels 54 may be a fluid outlet channel. For example, during use of the electrochemical cell stack 10, second fluid, in particular fuel, may flow along the fluid inlet channel in stacking direction 14 up, circulate through the cell units 12, and then (in the form of unspent first fluid and product of the electrochemical cell reaction) flow down in a direction opposite the stacking direction 14 along the fluid outlet channel.

As shown in Figure 2, at least one of the end plates 202, 204 may comprise one fluid access port 56 for each fluid channel 54 for transporting second fluid between the fluid channel 54 and an exterior of the cell assembly 200. In the example, the fluid access ports 56 are each formed by a respective through- hole 58 formed in the end plate 202.

In the example, the fluid access ports 56 in the end plate 202 are in fluidic communication with the associated fluid channel 54 via a flow path extending through the neighbouring insulation plate 206.

In the example (and those that follow), the through-holes are depicted as circular. It will be understood that the through-holes may take any shape, for example rectangular or hexagonal, but are preferably circular.

According to the invention, the cell units 12 comprise interlocking features to limit or block movement of adjacent cell units 12 relative to each other in a direction perpendicular to the stacking direction 14.

Figures 4 to 6 show an example implementation of such interlocking features according to a first embodiment. To increase visibility, Figures 4 to 6 only show a detail of a cell unit 12 in the area of one fluid port 46 (through-hole 48). However, it will be understood that the other fluid ports 46 can, preferably are, configured analogously.

As shown in Figures 4 and 5, the cell unit 12 has a conically shaped portion 60 around the fluid port 46 (through-hole 48). Specifically, the interconnector plate 18 and the support plate 22 each have a conically shaped portion 62, 64 around the fluid port 46.

The conically shaped portions 62, 64 may, for example, be formed by bending (e.g., pressing or forming) a portion of the interconnector plate 18 and the support plate 22 that surrounds the fluid port 46 out of a predominant plane of the original plate. In the specific example, an extent 66 of the conical shaped portion 62 of the interconnector plate 18 in the stacking direction 14 is about 15 times a plate thickness 68 of the interconnector plate 18 along the stacking direction 14. Analogously, an extent of the conical shaped portion 64 of the support plate 22 in the stacking direction 14 may be about 15 times a plate thickness of the support plate 22 along the stacking direction 14. In other embodiments, these ratios can be larger or smaller (for example 5 times or 10 times).

As shown in Figure 5, the conically shaped portion 64 of the support plate 22 protrudes into the conically shaped portion 62 of the interconnector plate 18. In other embodiments, the conically shaped portion 62 of the interconnector plate 18 protrudes into the conically shaped portion 64 of the support plate 22.

In the example, the conically shaped portion 62 of the interconnector plate 18 comprises optional shaped port features 70, e.g. in the form of dimples, that protrude towards the support plate 22. As can be seen from Figure 5, said shaped port features 70 are configured to keep a distance between the interconnector plate 18 and the support plate 22 to allow fluid to flow from the fluid port 46 to the fluid volume 34 enclosed between the interconnector plate 18 and the support plate 22. Alternatively or additionally, the support plate 22 may have such shaped port features 70 (e.g., dimples) in its conically shaped portion 64.

Referring to Figure 6, it can be seen that in the cell stack 10, the fluid ports 46 of the cell units 12 are aligned such that the conically shaped portions 60 of adjacent cell units 12 protrude into one another, thus forming an interlocking connection (e.g., form-fit) between adjacent cell units 12.

Specifically, an outer surface 72 of the conically shaped portion 60 of a cell unit 12 (in the specific example, an outer surface 72 of the conically shaped portion 62 of the interconnector plate 18) forms a first connection portion 74, and an inner surface 76 of said conically shaped portion 60 (in the specific example, an inner surface 76 of the conically shaped portion 64 of the support plate 22) forms a second connection portion 78. The first and second connection portions 74, 78 cooperate in a form-fitting manner to limit or block translational movement of the adjacent cell units 12 in a direction perpendicular to the stacking direction. While each pair of cooperating conically shaped portions 60 of adjacent cell units 12 (in this example) may allow rotational movement of the cell units 12 relative to each other, it will be understood that providing at least two fluid ports 46 with such a conically shaped portion 60 allows to also block rotational movement of the cell units 12 around the stacking direction 14.

In the specific example, between the conically shaped portion 60 of a cell unit 12 and the conically shaped portion 60 of an adjacent cell unit 12 (specifically, between the outer surface 72 of the conically shaped portion 62 of the interconnector plate 18 of a cell unit 12 and the inner surface 76 of the conically shaped portion 64 of the support plate 22 of an adjacent cell unit 12) a gasket 50 is provided.

In the example, the gasket 50 is a conically shaped gasket 80 having a central gasket opening and a circumferential collar 82 (see Figure 7).

Figures 8 and 9 show an example implementation of interlocking features according to a second embodiment. In this embodiment, the first and second connection portions 74, 78 are integrally formed with one of the interconnector plate 18 and the support plate 22, in the example with the interconnector plate 18.

Specifically, an inner edge portion 84 of the interconnector plate 18 surrounding the fluid port 48 (through-hole 48) is bent in a direction away from the support plate 22 (of the same cell unit as the interconnector plate), thus forming ring-shaped protrusion 86. Said ring-shaped protrusion 86 forms the first connection portion 74.

The second connection portion 78 is formed by an outer edge portion 88 of the periphery 26 of interconnector plate 18 bent towards the support plate 22 (of the same cell unit as the interconnector plate). As can be seen from Figure 8, specifically, the outer edge portion 88 is bent such that it extends around an external perimeter 90 of the support plate 22 and protrudes over a surface of the support plate 22 that faces away from the interconnector plate 18.

In this embodiment, the fluid port 46 is surrounded by a gasket 50 in the form of a sealing ring. The gasket 50 (sealing ring) has an outer perimeter 92 and an inner perimeter 94, said inner perimeter 94 defining a gasket opening 52 of the gasket 50. Referring to Figure 8, it can be seen that in the assembled state, the first connection portion 74 (bent inner edge portion 84 / protrusion 86) of a respective cell unit 12 engages against the inner perimeter 94 of a neighbouring gasket 50, and the second connection portion 78 (bent outer edge portion 88) of an adjacent cell unit 12 engages against the outer perimeter 92 of said gasket 50. This means that the first connection portion (of a first cell unit) and the second connection (of a second cell unit) cooperate with each other (via the gasket 50) such that movement of the cell units (12) relative to each other in a direction perpendicular to the stacking direction (14) is limited or blocked. This also holds the gasket 50 aligned with the associated fluid port 46 (through-hole 48). Thus, the first and second connection portions may also form a positioning fixture for the gasket 50 during manufacture of the stack and subsequently.

Figures 10 and 11 show a further embodiment of a cell unit 12 having an interlocking feature. The cell unit 12 of this embodiment is identical to the cell unit 12 of Figures 8 and 9, except that the first connection portion 74 is provided by an (inner) rim 96 of spatially separated (and circumferentially distributed) protrusions instead of a ring-shaped protrusion 86. Similarly, the second connection portion 78 is provided by an (outer) rim 98 of spatially separated (and circumferentially distributed) protrusions.

In even further embodiments, one of the first and second connection portion 74, 78 may be a rim of protrusion and the other one of the first and second connection portion 74, 78 may be a ring-shaped protrusion.

In even further embodiments, the protrusion or protrusions may extend only partially around the fluid port 46 (through-hole 48), e.g. only around half of the fluid port 46.

In even further embodiments, the first and second connection portions 74, 78 may both be provided by an inner circumference of the through-hole 48. Each connection portion 74, 78 may be provided by an (inner) rim 96 of spatially separated (and circumferentially distributed) protrusions in one of the interconnector plate 18 and support plate 22, said protrusions being upward and downwards (e.g., alternating upward and downward). In some cases, the upward protrusions may be provided by one of the interconnector plate 18 and support plate 22 and the downward protrusions may be provided by the other of the interconnector plate 18 and support plate 22. Figures 12 and 13 show a further implementation of interlocking features that can be applied alternatively or additionally to the above-described interlocking features. To avoid repetition, aspects of Figures 12 and 13 that are generally the same as shown in the previous Figures, specifically in Figure 3, will not be described again, and like reference numerals are used to describe like features.

Figure 12 shows a portion of an example cell stack 10 comprising two cell units 12 that are stacked upon one another along the stacking direction 14. As schematically shown in Figure 12, each cell unit 12 comprises a corrugation 100 at their peripheries 26, 30, having at least one, preferably plural, upward protrusions 102, and at least one, preferably plural, downward protrusions 104 that extend in opposite directions along the stacking direction 14. In the example, the upward protrusions 102 protrude out of the plane of the cell layer 16 in a direction away from the interconnector plate 18, and the downward protrusions 104 protrude out of the plane of the interconnector plate 18 in a direction away from the cell layer 16 along the stacking direction 14.

Referring to Figure 12, it can be seen that in the assembled configuration, the upwards protrusions 102 of one cell unit 12 cooperate with the downward protrusion of an adjacent cell 12 to form an interlocking connection (form-fit) acting in a plane perpendicular to the stacking direction 14.

The protrusions 102, 104 are - for simplicity - shown as cubes in Figure 12, but may have other cross- sectional shapes such as pyramids, flat-topped pyramids, cones, domes or bumps, and may be pressed or formed in one or both of the interconnector plate and support plate.

The upward and downward protrusions 102, 104 may be integrally formed with the interconnector plate 18 and the support plate 22, e.g., by pressing the interconnector plate 18 and the support plate 22. Alternatively, the upward and downward protrusions 102, 104 may be provided separately from the interconnector plate 18 and the support plate 22, and attached to the peripheries 26, 28 of the interconnector plate 18 and the support plate 22 (e.g., by printing, welding or gluing).

An insulator may be disposed between the upward and downward protrusions 102,104 (and a surrounding portion of the interconnector plate 18 and support plate 22). The insulator may be an insulative coating deposited or coated upon one or both of the interfacing surfaces. Alternatively, the insulator may be a separate component, for example a gasket similar to those described previously.

In the specific examples, the corrugation 100 comprises four corrugation segments 100-1, 100-2, 100-3, 100-4, each comprising a plurality of alternating upward and downward protrusions 102, 104. As shown in the example of Figure 13, the corrugation 100 of each cell unit is provided in two pairs of corrugation segments 100-1, 100-2, 100-3, 100-4, each disposed to opposing sides of the at least one electrochemically active cell chemistry region 20. Specifically, the cell unit 12 is generally rectangular having two long sides 106-1, 106-2 and two short sides 108-1, 108-2, wherein two corrugation segments 100-1, 100-3 are arranged along (part of) the long sides 106-1, 106-2 of the cell unit 12, and the other pair of corrugation segments 100-2, 100-4 is arranged along (part of) the short sides 108-1, 108-2 of the cell unit 12.

Alternatively, as shown in the example of Figure 14 the corrugations 100 may be elongate and the upward protrusions 102 parallel and interlock with the downward protrusions 104. In this case, one pair of upward and downward protrusions 102,104 are depicted in each corrugation segment. However corrugation segments may include more than one upward and one downward protrusion 102,104, for example corrugation segments may include two of one type of protrusion (e.g., upward protrusions 102) and one of the other type of protrusion (e.g., downward protrusion 104). Such cases may enable fewer corrugation segments since each segment blocks movement between cell units in along a direction perpendicular to their length.

Claims

1. An electrochemical cell stack (10), comprising a plurality of electrochemical cell units (12) that are stacked upon one another along a stacking direction (14), wherein: each cell unit (12) comprises a cell layer (16) having at least one electrochemically active cell chemistry region (20), and an interconnector plate (18), said cell layer (16) and said interconnector plate (18) overlie one another and are attached to each other to enclose a fluid volume (34) therebetween, adjacent cell units (12) cooperate with each other such that movement of the cell units (12) relative to each other in a direction perpendicular to the stacking direction (14) is limited or blocked.

2. The electrochemical cell stack according to claim 1, wherein adjacent cell units (12) are held aligned relative to each other by a form-fit connection.

3. The electrochemical cell stack according to claim 1 or 2, wherein each cell unit (12) comprises at least one first connection portion (74) and at least one second connection portion (78), wherein a first connection portion (74) of a cell unit (12) cooperates with a second connection portion (78) of an adjacent cell unit (12), preferably to form a form-fit connection acting in a plane perpendicular to the stacking direction (14).

4. The electrochemical cell stack according to the preceding claim, wherein between the first connection portion (74) of a cell unit (12) and the cooperating second connection portion (78) of an adjacent cell unit (12) at least one gasket (50) is provided, preferably such that forces between the first and second connection portions (74, 78) are transmitted via said gasket (50).

5. The electrochemical cell stack according to claim 3 or 4, wherein the at least one first connection portion (74) and the at least one second connection portion (78) of a cell unit (12) are located on opposite sides of said cell unit (12).

6. The electrochemical cell stack according to any one of claims 3 to 5, wherein said at least one first connection portion (74) is provided by, preferably integrally formed with, the interconnector plate (18) and/or wherein the cell layer (16) comprises a support plate (22) which carries the at least one electrochemically active cell chemistry region (20), and said at least one second connection portion (78) is provided by, preferably integrally formed with, the support plate (22).

7. The electrochemical cell stack according to any one of claims 3 to 5, wherein said at least one first connection portion (74) and said at least one second connection portion (78) are both provided by, preferably integrally formed with, the interconnector plate (18) or wherein the cell layer (16) comprises a support plate (22) which carries the at least one electrochemically active cell chemistry region (20), and said at least one first connection portion (74) and said at least one second connection portion (78) are both provided by, preferably integrally formed with, the support plate (22).

8. The electrochemical cell stack according to any one of claims 3 to 7, wherein the at least one first connection portion (74) comprises at least two first connection portions and the at least one second connection portion (78) comprises at least two second connection portions, wherein the first and second connection portions (74, 78) are arranged such that rotational movement of adjacent cell units (12) relative to each other around the stacking direction is limited or blocked.

9. The electrochemical cell stack according to any one of claims 3 to 8, wherein the at least one first connection portion (74) is one of a protrusion and a depression or recess, and the at least one second connection portion (78) is the other one of a protrusion and a depression or recess.

10. The electrochemical cell stack according to the preceding claim, wherein said protrusion of a cell unit (12) is received in a depression or recess of an adjacent cell unit (12).

11. The electrochemical cell stack according to claim 9 or 10, wherein said recess is formed by a through-hole (48) formed in the interconnector plate (18) or in the cell layer (16). 12. The electrochemical cell stack according to any one of claims 1 to 10, wherein each cell unit

(12) has at least one through-hole (48) formed therein, said through-hole (48) extending through both the interconnector plate (18) and the cell layer (16) along the stacking direction (14) and forming a fluid port (46) for transporting fluid between the fluid volume (34) and an exterior of the cell unit (12), wherein the through-holes (48) of adjacent cell units (12) are aligned such that they overlay along the stacking direction (14).

13. The electrochemical cell stack according to the preceding claim when referring to claim 3, wherein the or each through-hole (48) is at least partially surrounded by a protrusion (86) or a rim (96) of protrusions, said protrusion (86) or rim (96) of protrusions forming one of said first and second connection portions (74, 78).

14. The electrochemical cell stack according to claim 12 or 13 when referring to claim 3, wherein the or each through-hole (48) is delimited by a wall of the interconnector plate (18) or the cell layer (16), said wall forming one of said first and second connection portions (74, 78).

15. The electrochemical cell stack according to any one of claims 12 to 14 when referring to claim 3, wherein the or each through-hole (48) is associated with a gasket (50) surrounding it.

16. The electrochemical cell stack according to the preceding claim, wherein the first connection portion (74) of a cell unit (12) and an associated second connection portion (78) of an adjacent cell unit (12) cooperate with each other via said gasket (50).

17. The electrochemical cell stack according to claim 15 or 16, wherein the first connection portion (74) of a cell unit (12) and the second connection portion (78) of an adjacent cell unit (12) together form a positioning fixture for said gasket (50), preferably to hold said gasket (50) aligned with the associated through-hole (48) by a form-fit connection in a plane perpendicular to the stacking direction (14).

18. The electrochemical cell stack according to any one of claims 15 to 17, wherein said gasket (50) takes the form of a sealing ring having an outer perimeter (92) and an inner perimeter (94), said inner perimeter (94) defining a gasket opening (52) of the gasket (50), wherein the first connection portion (74) is configured to engage against, preferably contacts, the inner perimeter (94), and the second connection portion (78) is configured to engage against, preferably contacts, the outer perimeter (92).

19. The electrochemical cell stack according to any one of claims 16 to 18, wherein the first connection portion (74) and the second connection portion (78) each take the form of a, preferably ring-shaped, protrusion (86) or a rim (96) of circumferentially distributed protrusions, wherein the protrusion or protrusions forming the first connection portion (74) and the protrusion or protrusions forming the second connection portion (78) extend in opposite directions along the stacking direction (14).

20. The electrochemical cell stack according to any one of claims 16 to 19, wherein the first connection portion (74) and the second connection portion (78) of a cell unit (12) are both provided by, preferably integrally formed with, the interconnector plate (18) or the cell layer (16).

21. The electrochemical cell stack according to any one of claims 16 to 20, wherein the first connection portion (74) is formed by an inner edge portion (84) or inner edge portions of said interconnector plate (18) or cell layer (16) bent in a direction pointing away from the other of the interconnector plate (18) and the cell layer (16), said inner edge portion (84) at least partially surrounding the through-hole.

22. The electrochemical cell stack according to the preceding claim, wherein the second connection portion (78) is formed by an outer edge portion (88) or outer edge portions of said interconnector plate (18) or cell layer (16) bent towards the other of the interconnector plate (18) and the cell layer (16).

23. The electrochemical cell stack according to any one of claims 20 to 22, wherein the second connection portion (78) of a cell unit (12) extends around an external perimeter of the other one of said interconnector plate (18) and cell layer (16), preferably cell layer (16), or extends through the other one of said interconnector plate (18) and cell layer (16), such that said second connection portion (78) protrudes over a surface of the other one of said interconnector plate (18) and cell layer (16).

24. The electrochemical cell stack according to claim 11 or 12 when referring to claim 3, wherein the or each through-hole (48) is surrounded, preferably delimited, by a conically shaped portion (62, 64) of the cell layer (16) and/or the interconnector plate (18), said conically shaped portion (62, 64) forming one or both of said first and second connection portions (74, 78).

25. The electrochemical cell stack according to the preceding claim, wherein an outer surface (72) of said conically shaped portion (62, 64) forms the first connection portion (74) and an inner surface (76) of said conically shaped portion (62, 64) forms the second connection portion (78) of a cell unit (12).

26. The electrochemical cell stack according to claim 24 or 25, wherein said conically shaped portion (62, 64) extends out of a predominant plane of the interconnector plate (18) and/or the cell layer (16).

27. The electrochemical cell stack according to the preceding claim, wherein an extent of the conical shaped portion (62, 64) in the stacking direction (14) is at least 2 times, preferably at least 5 times, more preferably at least 10 times, a thickness of the interconnector plate (18) or the cell layer (16) along the stacking direction (14).

28. The electrochemical cell stack according any one of claims 24 to 27, wherein the interconnector plate (18) and the cell layer (16) each have a conically shaped portion (62, 64) surrounding the through-hole (48), wherein one of said conically shaped portions (62, 64) protrudes into the other one of said conically shaped portions (62, 64).

29. The electrochemical cell stack according to the preceding claim, wherein the conically shaped portion (64) that protrudes into the other conically shaped portion (62) forms the second connection portion (78), and wherein the other conically shaped portion (62) forms the first connection portion (74).

30. The electrochemical cell stack according to claim 28 or 29, wherein between the conically shaped portion (62) of the interconnector plate (18) of a cell unit (12) and the conically shaped portion (64) of the cell layer (16) of an adjacent cell unit (12) a gasket (50) is provided.

31. The electrochemical cell stack according to the preceding claim, wherein said gasket (50) is a conical gasket (80).

32. The electrochemical cell stack according to any one of claims 24 to 31, wherein the conically shaped portion (62) of the interconnector plate (18) is formed by bending a portion of the interconnector plate (18) surrounding the through-hole (48) out of a predominant plane of the interconnector plate (18), or wherein the cell layer (16) comprises a support plate (22), and the conically shaped portion (62, 64) is formed in said support plate (22), said conically shaped portion (64) of the support plate (22) is formed by bending a portion of the support plate (22) surrounding the through- hole (48) out of a predominant plane of the support plate (22).

33. The electrochemical cell stack according to any one of the preceding claims, wherein each cell unit (12) comprises a periphery (26, 28) which surrounds the at least one electrochemically active cell chemistry region (20), said periphery (26, 28) comprising a corrugation (100), wherein the corrugations (100) of adjacent cell units (12) cooperate with each other such that movement of the cell units (12) relative to each other in a direction perpendicular to the stacking direction (14) is limited or blocked.

34. The electrochemical cell stack according to the preceding claim, wherein the corrugation (100) comprises at least one upward protrusion (102) that protrudes out of the plane of one side of the cell unit (12) and at least one downward protrusion (104) that protrudes out of the plane of the other side of the cell unit (12), preferably a plurality of alternating upward and downward protrusions (102, 104).

35. The electrochemical cell stack according to claim 33 or 34, further comprising a gasket (50) between the corrugations (100) of adjacent cell units (12).

36. The electrochemical cell stack according to any one of claims 33 to 35, wherein the corrugation (100) of each cell unit (12) is provided by several, spatially separated corrugation segments (100-1, 100-2, 100-3, 100-4).

37. The electrochemical cell stack according to any one of claims 33 to 36, wherein the corrugation (100) of each cell unit (12) is provided in at least two pairs of corrugation segments (100-1, 100-2, 100-3, 100-4), each disposed to opposing sides of the at least one electrochemically active cell chemistry region (20).

38. The electrochemical cell stack according to any one of claims 33 to 37, wherein the corrugation (10) of a cell unit (12) is provided in both of the interconnector plate (18) and the cell layer (16).

39. The electrochemical cell stack according to any one of claims 33 to 38, wherein one of the interconnector plate (18) and the cell layer (16) extends past the periphery (26, 28) of the other one of the interconnector plate (18) and the cell layer (16), wherein the corrugation (100) is provided in a portion of the periphery (26, 28) of said one of the interconnector plate (18) and the cell layer (16) that extends past the periphery (26, 28) of the other one of the interconnector plate (18) and the cell layer (16).

40. An electrochemical cell unit (12) for use in an electrochemical cell stack (10) according to any one of the preceding claims.

41. An electrochemical cell unit (12) comprising features configured to cooperate with an adjacently stacked cell unit (12) such that in an electrochemical cell stack (10) comprising a plurality of said cell units (12) stacked upon one another along the stacking direction (14), movement of the cell units (12) relative to each other in a direction perpendicular to said stacking direction (14) is limited or blocked, said features comprising at least one of: a) a protrusion (86) or a rim (96) of protrusions, said protrusion (86) or rim (96) of protrusions at least partially surrounding a through-hole (48) formed in said cell unit (12); and b) a corrugation (100) which circumscribes at least a portion of a periphery (26, 28) of said cell unit(12).

42. Method of manufacturing an electrochemical cell stack (10), comprising:

- providing a plurality of electrochemical cell units (12), wherein each cell unit (12) comprises at least one first connection portion (74) on a first side of the cell unit (12) and at least one second connection portion (78) on an opposite second side of the cell unit (12);

- stacking the cell units (12) along a stacking direction (14) such that the or each first connection portion (74) of a respective cell unit (12) cooperates with a second connection portion (78) of an adjacent cell unit (12) to limit or block movement of the cell units (12) relative to each other in a direction perpendicular to the stacking direction (14).