Electrochemical cell assembly and method of manufacturing an electrochemical cell assembly

Abstract

The invention relates to an electrochemical cell assembly (10), the cell assembly comprising a base plate (24), a stack (12) having a plurality of cell units (14) that are stacked upon one another along a stacking direction (16), said stack being arranged upon the base plate, a housing (34) surrounding the stack of cell units and being movable relative to the base plate along the stacking direction, and a sealing device (74) that acts between the housing and the base plate, wherein the housing is connected to the base plate by at least one fastening device (50) that is configured to restrict movement of the housing relative to the base plate along the stacking direction in a first direction (52) away from the base plate.

Description

[0001] Title : Electrochemical cell assembly and method of manufacturing an electrochemical cell assembly

[0002] Specification

[0003] The invention relates to the field of electrochemical cell stacks , in particular, fuel cell stacks and electrolysis cell stacks . More speci fically, the invention relates to electrochemical cell assemblies , and to methods for manufacturing electrochemical cell assemblies .

[0004] Fuel cells and electrolysis cells are examples of electrochemical cells . Fuel cells are energy conversion devices that allow for conversion of electrochemical fuel to electricity . Electrolysis cells may be considered fuel 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 ( electrolysis cells ) . The present invention speci fically 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-stabilised Zirconia (YSZ ) , Gadolinia-doped Ceria, or Cerium Gadolinium Oxide ( CGO) . SOCs can be run as solid oxide fuel cells ( SOFC ) or as solid oxide electrolysis cell ( SOEC ) .

[0005] Typically, multiple of such electrochemical cell units are stacked upon one another to form a stack of cell units , also referred to as " cell repeat units" . Said stack of cell units is commonly arranged upon a base plate . Said base plate may also serve as an access point for providing a fuel such as hydrogen and / or an oxidant such as air to the stack of cell units . The cell units are typically surrounded by a housing . Said housing may serve to protect the stack of cell units from particles and the like . Commonly, the housing is welded to the base plate .

[0006] It is an obj ect of the invention to ease the manufacture of electrochemical cell assemblies .

[0007] According to the invention, there is provided an electrochemical cell assembly with the features of claim 1 . The electrochemical cell assembly comprises a stack of cell units , said stack of cell units comprising a plurality of cell units that are stacked upon one another along a stacking direction . The stack of cell units is arranged upon a base plate of the electrochemical cell assembly . The electrochemical cell assembly further comprises a housing surrounding the stack of cell units . The housing may extend along an outer perimeter of the cell units . The housing and the base plate together define or enclose a fluid volume , with the stack of cell units being arranged in said fluid volume . The housing is movable relative to at least the base plate along the stacking direction . In other words , the housing and the base plate are not fixedly attached to each other by welding or the like . The electrochemical cell assembly further comprises a sealing device that acts between the housing and the base plate . Said sealing device may seal the fluid volume defined or enclosed by the base plate and the housing against the exterior . The sealing device comprises a circumferential sealing member . Said sealing member is sealingly engaged against a first surface of the housing and against an opposed second surface of the base plate or against an opposed second surface of an element that is attached to the base plate . The housing is connected to the base plate by at least one fastening device , i . e . only one fastening device or several fastening devices . Said at least one fastening device restricts movement of the housing relative to the base plate along the stacking direction in a first direction away from the base plate .

[0008] The inventors have found that the proposed fastening device facilitates the manufacture of electrochemical cell assemblies , in particular with regard to mass production . Speci fically, by using the at least one fastening device for connecting the housing to the base plate , a welded connection between the housing and the base plate can be omitted, which can be time consuming and complex to manufacture . In addition, the proposed fastening device reduces local stresses on the housing, and thus unwanted distortion of the housing . The sealing device having the circumferential sealing member securely seals the fluid volume against the exterior even in the absence of a welded connection .

[0009] It is to be understood that the number of cell units forming the stack of cell units may vary . The height of the housing, i . e . the extent of the housing along the stacking direction, may vary accordingly . Speci fically, the height of the housing increases with the number of cell units .

[0010] In some embodiments , the cell units are solid oxide fuel cell units ( SOFCs ) . In some embodiments , the cell units are solid oxide electrolysis cell units ( SOECs ) . Preferably, the cell units are metal-supported solid oxide cell units ( e . g . , solid oxide fuel cell units or electrolysis cell units ) .

[0011] The cell units may be configured flat or planar . Thus , the length extent and the width extend of the cell units may be signi ficantly larger than their height extent . Preferably, the cell units are arranged such that the length extent and the width extent are perpendicular to the stacking direction .

[0012] Preferably, the at least one fastening device restricts the movement of the housing relative to the base plate along the stacking direction only in the first direction . In other words , the fastening device may allow a movement of the housing relative to the base plate along the stacking direction in a second direction towards the base plate .

[0013] The housing may be a single-piece housing . Preferably, the housing is a multi-piece housing . Thus , the housing may comprise several housing units that are fixedly attached to one another, for example by welding . This further aids easy manufacturing of the cell assembly .

[0014] In some embodiments , the first surface and the second surface are vertical surfaces . As used herein, a vertical surface is a surface that is aligned with the stacking direction . Where the first and second surfaces are vertical surfaces , the housing may be moved relative to the base plate in the second direction without af fecting the sealing ef fect provided by the sealing device .

[0015] In some embodiments , the first surface and the second surface are hori zontal surfaces . As used herein, a hori zontal surface is a surface that is perpendicular to the stacking direction .

[0016] In some embodiments , the sealing device is held in compression ( or in a form- fit manner ) between the first surface and the second surface , thereby enhancing the sealing ability of the sealing device . In some preferred embodiments , the electrochemical cell assembly further comprises an end plate that is arranged upon the stack of cell units . In other words , the stack of cell units is arranged between the end plate and the base plate . Where the electrochemical cell assembly comprises an end plate , the fluid volume may be defined or enclosed by the base plate , the housing and the end plate .

[0017] In some preferred embodiments , the housing is fixedly attached to the end plate . This facilitates sealing the fluid volume against the exterior because no relative movement is possible between the housing and the end plate . Preferably, the housing is fixedly and sealingly attached to the end plate .

[0018] In some preferred embodiments , the housing is welded to the end plate . A welded connection may provide a reliable sealing ef fect between the housing and the end plate .

[0019] In some other embodiments , the housing and the end plate are separate from each other, i . e . the housing and the end plate are separate units . In this case , the housing may be movable relative to the end plate along the stacking direction . A further sealing device may act between the housing and the end plate for sealing the fluid volume against the exterior .

[0020] In some preferred embodiments , the fastening device is under tension, wherein a tensioning force acting on the fastening device acts along the stacking direction ( the tensioning force acting to pull the base plate towards the stack of cell units ( and housing / end plate ) in the first direction and vice-versa in the second direction towards the base plate ) . Consequently, the fastening device applies a compression force to the stack of cell units . The compression force is applied to the stack of cell units , e . g . via the end plate , such that the stack of cell units is compressed along the stacking direction by the compression force . Compressing the stack of cell units has the advantage that a direct contact between adj acent cell units and, thus , an electrical connection between the adj acent cell units may be secured . Furthermore or alternatively, the compression force may improve a sealing ef fect of gaskets that may be interposed between adj acent cell units .

[0021] In some preferred embodiments , the fastening device comprises an adj ustment mechanism for adj usting the tensioning force . This has the advantage that a desired tensioning force can be adj usted for example to reali ze a compression force regardless of manufacturing tolerances of the components of the electrochemical cell assembly, e . g . the housing or the cell units .

[0022] In some preferred embodiments , the first surface is an inner surface of the housing, preferably an inner vertical surface of the housing . An inner surface of the housing is a surface of the housing that is facing towards the fluid volume . Accordingly, the sealing member is arranged within the fluid volume . This has the advantage that the sealing member is exposed to the temperature in the fluid volume . During operation of an electrochemical cell assembly, the temperature in the fluid volume is typically elevated ( solid oxide cell units may reach an operating temperature of 600 ° C, for example ) . This elevated temperature can be used to cure the sealing member . Moreover, arranging the sealing member in the fluid volume may result in a sel fsealing ef fect that makes use of a pressure di f ference between the fluid volume and the exterior . Typically, during operation of the electrochemical cell assembly the pressure in the fluid volume is higher than the pressure in the exterior . Speci fically, a narrowing gap may be provided downstream of the sealing member, i . e . between the sealing member and the exterior . The pressure di f ference may result in the sealing member being pushed into said narrowing gap during operation of the electrochemical cell assembly .

[0023] In some other embodiments , the first surface is an outer surface of the housing, preferably an outer vertical surface of the housing . An outer surface of the housing is a surface of the housing that is facing towards the exterior . Accordingly, the sealing member is arranged outside of the fluid volume in the exterior . This may have the advantage that the sealing member is accessible without removal of the housing, e . g . for repair or leak checking .

[0024] In some preferred embodiments , the base plate comprises a protrusion, wherein the second surface is a surface of said protrusion . A protrusion facilitates the arrangement of the sealing member . Preferably, the second surface is a vertical surface of the protrusion. In some embodiments, the protrusion is an integral part of the base plate, i.e. a machined feature of the base plate. In some other embodiments, the protrusion is fixedly attached to the base plate. When seen along a viewing direction that is parallel to the stacking direction, preferably the protrusion is annular .

[0025] In some other embodiments, the base plate comprises a recess, e.g. a groove, wherein the second surface is a surface of said recess, preferably a vertical surface of the recess. The second surface (e.g., groove) or the first surface may allow the sealing device to slide along that surface .

[0026] In some preferred embodiments, the protrusion is surrounded by the housing (e.g., where the first surface is an inner surface of the housing) . With this configuration, the advantages of the protrusion itself and the arrangement of the sealing member in the fluid volume may be achieved in combination. In some cases the housing is surrounded by the protrusion (e.g., where the first surface is an outer surface of the housing) .

[0027] In some preferred embodiments, the sealing member is arranged in a recess, e.g. a circumferential groove, of the first surface or of the second surface. This has the advantage that the sealing member may be held in the recess by side walls of the recess. Consequently, the housing and the base plate may be moved, e.g. slid, relative to each other along the stacking direction while the sealing member is securely retained in the recess. Preferably, the recess is provided in the protrusion of the base plate.

[0028] In some preferred embodiments, the base plate has an end face facing towards the housing, wherein an end of the housing adjacent to the base plate is spaced apart from said end face along the stacking direction. That is to say, there is provided a gap between the end of the housing and the base plate. A gap facilitates an adjustment of the position of the housing relative to the base plate along the stacking direction. Specifically, the housing can be brought closer to the base plate in order to increase the compression force acting on the stack of cell units, if applicable. Preferably, the gap between the end of the housing and the end face of the base plate is equal to or more than 0.5 mm and equal to or less than 3.0 mm, more preferably equal to or more than 0.5 mm and equal to or less than 2.0 mm.

[0029] In some other embodiments, the housing is in touch-contact with the end face of the base plate. The compression force acting on the stack of cell units may then be increased through elastic and / or plastic deformation of the housing.

[0030] In some preferred embodiments, the fastening device comprises at least one holding member, i.e. only one holding member or several holding members, for restricting the movement of the housing relative to the base plate in the first direction and at least one fixing member, i.e. only one fixing member or several fixing members , for attaching the holding member to the base plate .

[0031] In some preferred embodiments , the at least one holding member comprises a strap . Due to its inherent flexibility a strap has the advantage that the course of the strap may conform to the shape of the housing . This may facilitate the manufacture or assembly of the electrochemical cell assembly . The fixing member may pass through an opening that is formed in the strap .

[0032] In some preferred embodiments , the strap is formed from a metal material , preferably steel . A strap formed from a metal material can withstand high tensioning forces , thus allowing for high compression forces acting on the stack of cell units .

[0033] In some embodiments , the at least one fixing member may cause the strap to apply a compression force to the sealing device (via the housing) , reacted by the base plate or element that is attached to the base plate ( in other words , the compression force is between the first and second surfaces ) .

[0034] In some preferred embodiments , the strap overarches the housing, wherein both ends of the strap are attached to the base plate . This has the advantage that the housing does not require any attachment features of the strap to the housing . Furthermore , a configuration, in which the strap overarches the housing and is attached to the base plate at both ends allows to apply compression forces to the housing in an even manner, e . g . such that a first portion of the housing and a second portion of the housing that are arranged on opposite sides of the stack of cell units receive essentially the same compression force .

[0035] In some preferred embodiments , a first end of the strap is attached to the base plate and a second end of the strap is attached to the housing . In this embodiment , the fastening device preferably comprises at least one further strap that is attached to the base plate and to the housing, wherein the strap and the further strap are arranged on opposite sides of the housing .

[0036] In embodiments having an end plate , a first end of the strap is attached to the base plate and a second end of the strap may be attached to the end plate . In this embodiment , the fastening device preferably comprises at least one further strap that is attached to the base plate and to the end plate , wherein the strap and the further strap are arranged on opposite sides of the housing .

[0037] In some preferred embodiments , the at least one fixing member comprises at least one screw, wherein a tensioning force in the strap can be adj usted by rotating said screw . A screw may enable a precise adj ustment of the tensioning force in the strap . The screw may be screwed in a threaded hole formed in the base plate . In some preferred embodiments , the base plate comprises at least one fluid inlet port for supplying a fluid to the fluid volume and / or at least one fluid outlet port for removing a fluid from the fluid volume . The ports may be provided by a respective through-hole that extends through the base plate along the stacking direction . During operation, the ports may serve di f ferent purposes as outlined below .

[0038] In an operation mode , preferably, at least one fluid inlet port is used as an oxidant inlet port . This fluid inlet port may be in fluidic communication with a first portion of the fluid volume between the housing and the stack of cell units .

[0039] Preferably, at least one fluid outlet port is used during operation as an outlet port for oxidant ( e . g . , oxidant consumed or partly consumed in operation as a fuel cell ) . This fluid outlet port may be in fluidic communication with a second portion of the fluid volume between the housing and the stack of cell units , said first and second portions of the fluid volume being on opposite sides of the stack of cell units ( and in fluidic communication with one another via the stack of cell units ) .

[0040] Preferably, at least one fluid inlet port is used during operation as a fuel inlet port . This fluid inlet port may be in fluidic communication with a cell volume of the cell units , i . e . an internal volume of the cell units , and not in fluidic communication with the first and second portions of the fluid volume .

[0041] Preferably, at least one fluid outlet port is used during operation as an outlet port for consumed or partly consumed fuel . This fluid outlet port may be in fluidic communication with the cell volume of the cell units , and not in fluidic communication with the first and second portions of the fluid volume .

[0042] According to the invention, there is also provided a method of preparing an electrochemical cell assembly with the features of claim 20 .

[0043] The method comprises providing an electrochemical cell assembly having

[0044] - a base plate ,

[0045] - a stack of cell units , comprising a plurality of cell units that are stacked upon one another along a stacking direction, said stack of cell units being arranged upon the base plate ,

[0046] - a housing surrounding the stack of cell units , wherein the housing and the base plate together define or enclose a fluid volume , wherein the housing is movable relative to at least the base plate along the stacking direction, and

[0047] - a sealing device that acts between the housing and the base plate , said sealing device comprising a circumferential sealing member engaged against a first surface of the housing and against an opposed second surface of the base plate or against a second surface of an element that is attached to the base plate .

[0048] Additional preferred features of the electrochemical cell assembly, e . g . regarding the housing, the base plate , an end plate or the stack of cell units , may be realised as described above .

[0049] The method further comprises restricting movement of the housing relative to the base plate along the stacking direction in a first direction away from the base plate by connecting the housing to the base plate by at least one fastening device .

[0050] Preferably, movement in a second direction that is opposite the first direction is not restricted by the at least one fastening device . That is to say, the at least one fastening devices allows movement in said second direction . Additional preferred features of the fastening device may be realised as described above .

[0051] According to the invention, there is provided a further electrochemical cell assembly with the features of claim 21 . The electrochemical cell assembly having : a sealing device that acts between a housing and a base plate , said sealing device forming a fluidic seal between the housing and the base plate ; and at least one fastening device , said fastening device connected to the base plate and configured to apply a compressive force to a stack of cell units stacked upon the base plate , wherein an end of the housing is spaced apart from the base plate .

[0052] The electrochemical cell assembly may additionally have any of the features as described above .

[0053] Further embodiments are derivable from the following description and the drawings :

[0054] Figure 1 shows a cross-sectional view of an embodiment of an electrochemical cell assembly;

[0055] Figure 2 shows a side view of the electrochemical cell assembly shown in Figure 1 .

[0056] Referring to Figures 1 and 2 , there is shown an exemplary configuration of an electrochemical cell assembly 10 .

[0057] The electrochemical cell assembly 10 comprises a stack 12 , the stack 12 comprising a plurality of electrochemical cell units 14 that are stacked upon one another along a stacking direction 16 .

[0058] The cell units 14 are configured flat or planar and extend in a respective cell plane that is perpendicular to the stacking direction 16 . Adj acent cell units 16 are in touchcontact with each other, said touch-contact providing an electrical connection between the cell units 14 . The stack 12 further comprises a plurality of gaskets 18 . The gaskets 18 are interposed between adj acent cell units 14 . In this example , the gaskets 18 are configured as annular sealing rings having a central opening 20 . The gaskets 18 may be formed from a vermiculite material , for example .

[0059] The electrochemical cell assembly 10 further comprises a base plate assembly 22 having a base plate 24 . The stack 12 of cell units 14 is arranged upon the base plate 24 .

[0060] In this example , the base plate assembly 22 further comprises a first insulating plate 26 that is interposed between the base plate 24 and the stack 12 of cell units 14 . The first insulating plate 26 electrically insulates the stack 12 of cell units 14 from the base plate 24 that is preferably formed from a metal material . The first insulating plate 26 may be formed from a mica material , for example .

[0061] The exemplary electrochemical cell assembly 10 further comprises an end plate assembly 28 having an end plate 30 that is arranged upon the stack 12 of cell units 14 .

[0062] In this example , the end plate assembly 28 further comprises a second insulating plate 32 that is interposed between the end plate 30 and the stack 12 of cell units 14 . The second insulating plate 32 electrically insulates the stack 12 of cell units 14 from the end plate 30 that is preferably formed from a metal material . The second insulating plate 32 may be formed from a mica material, for example .

[0063] The electrochemical cell assembly 10 further comprises a housing 34 that surrounds the stack 12 of cell units 14. The housing 34 extends along the outer perimeters 35 of the cell units 14.

[0064] The base plate 24, the end plate 30 and the housing 34 together define or enclose a fluid volume 36. The stack 12 of cell units 14 is arranged within said fluid volume 36.

[0065] In this example, the base plate 24 comprises at least one first fluid inlet port 38 for first fluid, e.g., fuel. The fluid inlet port 38 is provided by a through-hole 40 formed in the base plate 24. The fluid inlet port 38 is fluidically connected with cell volumes of the cell units 14 via an inlet manifold 42 that extends through the stack 12 of cell units 14 along the stacking direction 16. The inlet manifold 42 is defined by the gasket openings 20 and through-holes that are formed in the cell units 14 and aligned with the openings 20. During operation of the electrochemical cell assembly 10, the fluid inlet port 38 may be used to provide a first fluid, e.g. fuel such as hydrogen or steam, to the cell units 14, i.e. to their cell volume .

[0066] In this example, the base plate 24 comprises at least one first fluid outlet port 44 for first fluid, e.g. unspent fuel and / or product of the electrochemical reaction. The fluid outlet port 44 is provided by a through-hole 46 formed in the base plate 24 . The fluid outlet port 44 is fluidically connected with the cell volumes of the cell units 14 via an outlet mani fold 48 that extends through the stack 12 of cell units 14 along the stacking direction 16 . The outlet mani fold 48 is provided by the gasket openings 20 and through-holes that are formed in the cell units 14 and aligned with the openings 20 . During operation of the electrochemical cell assembly 10 , the fluid outlet port 44 may be used to remove fluid, e . g . a consumed or partly consumed fuel and / or product of the electrochemical reaction, from the cell units 14 to the exterior .

[0067] The base plate 24 may further comprise at least one second fluid inlet port for second fluid, e . g . oxidant / air (not visible in the Figures ) . The second fluid inlet port may be fluidically connected with a first portion of the ( second) fluid volume 36 between the housing 34 and the stack 12 of cell units 14 . During operation of the electrochemical cell assembly 10 , the second fluid inlet port may be used to supply second fluid, e . g . oxidant such as air or oxygen, to the first portion of the ( second) fluid volume 36 .

[0068] The base plate 24 may further comprise at least one second fluid outlet port for second fluid, e . g . , oxidant / air and / or product of the electrochemical reaction (not visible in the Figures ) . The second fluid outlet port may be fluidically connected with a second portion of the ( second) fluid volume 36 between the housing 34 and the stack 12 of cell units 14 . The first and second portions of the ( second) fluid volume 36 may be on opposite sides of the stack 12 of cell units 14 and fluidically connected by the stack 12 of cell units 14 . During operation of the electrochemical cell assembly 10 , the second fluid outlet port may be used to remove fluid, e . g . a consumed or partly consumed oxidant or a product of the electrochemical reaction, from the ( second) fluid volume 36 .

[0069] The housing 34 is movable relative to the base plate 24 along the stacking direction 30 .

[0070] In this example , the housing 34 is fixedly attached to the end plate 30 , preferably by welding . That is to say, the housing 34 and the end plate 30 can only be moved together along the stacking direction 16 . In other examples , the housing 34 may be movable relative to the end plate 30 along the stacking direction 16 . In some examples , the function of the housing and end plate may be provided by a single housing component .

[0071] The housing 34 is connected to the base plate 24 by at least one fastening device 50 . In the speci fic example of Figure 2 , three fastening devices 50 are provided, but it will be understood that any suitable number of fastening devices may be used and that in some cases , the fastening devices (particularly the straps thereof ) may overlap . Each of the fastening devices 50 of Fig . 2 are of the type depicted in Fig . 1 that overarch the housing and are fastened to the base plate at both of their ends . The fastening devices 50 restrict a movement of the housing 34 relative to the base plate 24 along the stacking direction 16 in a first direction 52 away from the base plate 24. Since the end plate 30, in this example, is fixedly attached to the housing 34, the fastening devices 50 also restrict a movement of the end plate 30 relative to the base plate 24 in the first direction 52.

[0072] In this example, the fastening devices 50 allow movement of the housing 34 relative to the base plate 24 along the stacking direction 16 in an opposed second direction 54 towards the base plate 24.

[0073] As shown in the inset of Figure 1, in this example, an end 56 of the housing 34 adjacent to the end plate 24 is spaced apart from an end face 58 of the base plate 24 that is facing towards the housing 34, i.e. in the first direction 52. Consequently, a gap 60 is present between the end 56 of the housing 34 and the end face 58 of the base plate 24. It should be noted that the dimension of the gap 60 is only schematic in the Figures. Preferably, the gap 60, i.e. the distance between the end 56 and the end face 58, is equal to or more than 0.5 mm and equal to or less than 3.0 mm, preferably equal to or less than 2.0 mm.

[0074] As explained above, the fastening devices 50 allow movement of the housing 34 in the second direction 54 towards the base plate 24. This movement of the housing 34, however, is restricted because the end plate 30 (which, in this example, is fixedly attached to the housing 34) is resting on the second insulating plate 32. Therefore, the insulating plates 28 , 32 and the stack 12 of cell units 14 restrict movement of the end plate 30 ( and thus movement of the housing 24 ) in the second direction 54 towards the base plate 24 and, thus , keep the gap 60 open .

[0075] In other examples , the end 56 is in touch-contact with the end face 58 .

[0076] The fastening device 50 comprises at least one holding member 62 for restricting the movement of the housing 34 relative to the base plate 24 and at least one fixing member 64 for attaching the holding member 62 to the base plate 24 .

[0077] In this example , the holding member 62 comprises a strap 66 that overarches the housing 34 . Both ends 68 and 70 of the strap 66 are attached to the base plate 24 . Preferably, the strap 66 is formed from a metal material .

[0078] In other examples , one end of the strap 66 is attached to the base plate 24 and the other end of the strap 66 is attached to the housing 34 . In other examples , one end of the strap 66 is attached to the base plate 24 and the other end of the strap 66 is attached to the end plate 30 . In these examples , the fastening device may comprise at least one further strap that is attached to the base plate and to the end plate , wherein the strap and the further strap are arranged on opposite sides of the housing 34 . In this example , the at least one fixing member 64 comprises two screws 72a and 72b . The screws 72a and 72b reach through a respective opening formed in the ends 68 and 70 of the strap 66 . The screws 72a and 72a are received in a respective threaded hole formed in the base plate 24 . A tensioning force in the strap 66 can be adj usted by rotating the screws 72a and 72b .

[0079] In this example , the screws 72a and 72b are rotated such that the fastening device 50 is under tension .

[0080] Consequently, the fastening device 50 applies a compression force to the stack 12 of cell units 14 via the end plate 30 and the second insulating plate 32 . That is to say, the stack 12 of cell units 14 is held in compression between the end plate 30 and the base plate 24 as a result of the tension in the fastening device . The compression force acting on the stack 12 of cell units 14 can be adj usted by rotating the screws 72a and 72b .

[0081] The electrochemical cell assembly 10 further comprises a sealing device 74 that acts between the housing 34 and the base plate 24 . The sealing device 74 is configured to seal the ( second) fluid volume 36 against the exterior ( i . e . , the ( second) fluid volume 36 is enclosed by the base plate , end plate , housing and sealing device ) .

[0082] The sealing device 74 comprises a circumferential sealing member 76 that sealingly engages against a first surface 78 of the housing 34 and against a second surface 80 of the base plate 24 or of an element that is fixedly attached to the base plate 24. The sealing member 76 extends along the entire circumference of the housing 34. In this example, the surfaces 78 and 80 are vertical surfaces, i.e. the surfaces are aligned with the stacking direction 16.

[0083] In this example, the first surface 78 is an inner vertical surface of the housing 34. Consequently, the sealing member 76 is arranged inside the housing 34.

[0084] In this example, the second surface 80 is provided by a protrusion (or upstand) 82. Said protrusion 82 is attached to the base plate 24 and extends from the base plate 24 in the first direction 52. Seen along a viewing direction that is parallel to the stacking direction 16, the protrusion is annular in shape. In other examples, the protrusion may be a machined feature of the base plate 24 (i.e., the protrusion and base plate are unitary) .

[0085] The sealing member may be formed from vermiculite or rubber. Preferably, the sealing member is circumferential.

[0086] In this example, the sealing member 76 is arranged in a recess 84 formed in the second surface 80. The sealing member 76 is held in the recess 84 by side walls of the recess 84. In other examples, the sealing member 76 is arranged in a recess formed in the first surface 78.

[0087] In some examples (not shown) the housing 34 is surrounded by the protrusion 82 with the sealing device disposed therebetween. In such examples, the first surface is an outer vertical surface of the housing 34 and the second surface is provided by the protrusion (or upstand) .

[0088] In the above examples, the housing 34 is not in tension or compression. In further examples, the sealing member may be arranged between the end 56 of the housing 34 and the end face 58 of the baseplate 24. In this example, the housing may apply compression force to the sealing member to aid its sealing effect.

[0089] In each case, the sealing device allows the housing to move along the stacking direction without compromising the sealing ability of the sealing device 74.

[0090] The sealing device 74 may comprise an envelope gasket, whereby a pressure difference between the pressure in the (second) fluid volume 36 and the pressure external to the electrochemical cell assembly (e.g., an ambient pressure) acts to drive the sealing device closed (sealed) . In such cases, an initial seal may be due to form fit (i.e., interference fit) of the sealing device 74 between the housing 34 and the protrusion 82, and the seal (closure thereof) maintained in use by the pressure difference. Alternatively, the sealing device 74 may comprise a gasket held in compression (therefore sealingly held, compression in a lateral direction) between the housing 34 and protrusion 82. In such cases, the sealing device 74 may comprise a vermiculite or rubber seal (i.e., gasket) . The compression force may be provided by the stiffness of the housing 34 and protrusion 82. In some cases a further component (or further protrusion from the base plate 24) may apply compression to the sealing device 74 via the housing 34, reacted by the protrusion 82. In some cases, the sealing device 74 and a portion of the housing 34 may sit in a groove in the baseplate 24 to provide the abovementioned sealing effects.

[0091] In Fig. 1 the strap 50 (specifically substantially vertical portion thereof) is depicted as being angled relative to the housing 34. This need not be the case. In some examples the at least one fixing member 34 is positioned such that the strap applies a compression force (e.g., the abovementioned compression force) to the sealing device 74, to improve (or provide) a fluidic seal between the first surface of the housing and the second surface of the protrusion. In such cases the strap and housing may be parallel to one another.

Claims

Claims1. An electrochemical cell assembly (10) , preferably fuel cell assembly or electrolysis cell assembly, comprising :- a base plate (24) ,- a stack (12) of cell units (14) , comprising a plurality of cell units (14) stacked upon one another along a stacking direction (16) , said stack (12) of cell units (14) being arranged upon the base plate (24 ) ,- a housing (34) surrounding the stack (12) of cell units (14) , wherein the housing (34) and the base plate (24) together define or enclose a fluid volume (36) , wherein the housing (34) is movable relative to at least the base plate (24) along the stacking direction (16) , and- a sealing device (74) that acts between the housing (34) and the base plate (24) , said sealing device (74) comprising a circumferential sealing member (76) engaged against a first surface (78) of the housing (34) and against an opposed second surface (80) of the base plate (24) or of an element (82) that is attached to the base plate (24) , wherein the housing (74) is connected to the base plate (24) by at least one fastening device (50) , said fastening device (50) configured to restrict movement of the housing (34) relative to the base plate (24)along the stacking direction (16) in a first direction (52) away from the base plate (24) .

2. The electrochemical cell assembly (10) according to claim 1, wherein an end plate (30) is arranged upon the stack (12) of cell units (14) .

3. The electrochemical cell assembly (10) according to the preceding claim, wherein the housing (34) is fixedly attached to the end plate (30) .

4. The electrochemical cell assembly (10) according to the preceding claim, wherein the housing (34) is welded to the end plate (30) .

5. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the fastening device (50) is under tension, and wherein a tensioning force acting on the fastening device (50) acts along the stacking direction (16) .

6. The electrochemical cell assembly (10) according to the preceding claim, wherein the fastening device (50) comprises an adjustment mechanism for adjusting said tensioning force.

7. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the base plate (24) comprises a protrusion (76) , and wherein the second surface (80) is a surface of said protrusion (82) .

8. The electrochemical cell assembly (10) according to the preceding claim, wherein the protrusion (82) is surrounded by the housing (34) .

9. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the first surface (78) is an inner surface of the housing (34) .

10. The electrochemical cell assembly (10) according to any one of claims 1 to 7, wherein the first surface (78) is an outer surface of the housing (34) , and wherein the housing 34 is surrounded by the protrusion (82) .

11. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the sealing member (76) is arranged in a recess (84) of the first surface (78) or of the second surface (80) .

12. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the base plate (24) has an end face (58) facing towards the housing (34) , and wherein an end (56) of the housing (34) adjacent to the base plate (24) is spaced apart from said end face (58) along the stacking direction (16) .

13. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the fastening device (50) comprises at least one holding member (62) for restricting the movement of the housing (34) relative to the base plate (24) in the first direction(52) and at least one fixing member (64) for attaching the holding member (62) to the base plate (24) .

14. The electrochemical cell assembly (10) according to the preceding claim, wherein the at least one holding member (62) comprises a strap (66) .

15. The electrochemical cell assembly (10) according to the preceding claim, wherein the strap (66) is formed from a metal material, preferably steel.

16. The electrochemical cell assembly (10) according to any one of claims 14 and 15, wherein the strap (66) overarches the housing (34) , and wherein both ends (68, 70) of the strap (66) are attached to the base plate (24 ) .

17. The electrochemical cell assembly (10) according to any one of claims 14 and 15, wherein a first end of the strap (66) is attached to the base plate (24) and a second end of the strap (66) is attached to the housing ( 34 ) .

18. The electrochemical cell assembly (10) according to any one of claims 13 to 17, wherein the at least one fixing member (64) comprises at least one screw (72) , and wherein a tensioning force in the strap (66) can be adjusted by rotating said screw (72) .

19. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the base plate (24) comprises at least one fluid inlet port for supplying a fluid to the fluid volume (36) and / or atleast one fluid outlet port for removing a fluid from the fluid volume (36) .

20. A method of preparing an electrochemical cell assembly (10) , preferably fuel cell assembly or electrolysis cell assembly, said method comprising: a. providing an electrochemical cell assembly (10) having-a base plate (24) ,-a stack (12) of cell units (14) , comprising a plurality of cell units (14) that are stacked upon one another along a stacking direction (16) , said stack (12) of cell units (14) being arranged upon the base plate (24 ) ,-a housing (34) surrounding the stack (12) of cell units (14) , wherein the housing (34) and the base plate (24) together define or enclose a fluid volume (36) , wherein the housing (34) is movable relative to at least the base plate (24) along the stacking direction (16) , and-a sealing device (74) that acts between the housing (34) and the base plate (24) , said sealing device (74) comprising a circumferential sealing member (76) engaged against a first surface (78) of the housing (34) and against an opposed second surface (80) of the base plate (24) or of an element(82) that is attached to the base plate(24 ) , and b. restricting the movement of the housing (34) relative to the base plate (24) along the stacking direction (16) in a first direction (52) away from the base plate (24) by connecting the housing (34) to the base plate (24) by at least one fastening device (50) .

21. An electrochemical cell assembly (10) , preferably fuel cell assembly or electrolysis cell assembly, comprising : a sealing device (74) that acts between a housing (34) and a base plate (24) , said sealing device (74) forming a fluidic seal between the housing (34) and the base plate (24) ; and at least one fastening device (50) , said fastening device (50) connected to the base plate (24) and configured to apply a compressive force to a stack (12) of cell units (14) stacked upon the base plate (24) , wherein an end (56) of the housing (34) is spaced apart from the base plate (24) .

Images