Electrochemical cell assembly

Abstract

The invention relates to an electrochemical cell assembly comprising an end plate assembly having an end plate (14), and a stack of cell repeat units, said end plate (14) comprising at least one through-hole (26) formed therein to form a fluid port (28) for supplying fluid from the outside of the electrochemical cell assembly to the stack of cell repeat units, said through-hole being associated with a sealing device (42), said sealing device comprising a sleeve (44), and a first gasket (56), said first gasket (56) being provided on a first face (50) of the sleeve (44), wherein the sleeve (44) is positioned at least partially in a recess (62) formed in a surface (64) of the end plate, said surface facing the stack of cell units.

Description

[0001] Title: Electrochemical cell assembly

[0002] Specification

[0003] The invention relates to the field of electrochemical cell stacks, in particular, fuel cell stacks and electrolyser cell stacks. More specifically, the invention relates to an electrochemical cell assembly.

[0004] Fuel cells and electrolyser cells are examples of electrochemical cells. Fuel cells are energy conversion devices that allow for conversion of electrochemical fuel to electricity. Electrolyser cells are fuels cells running in reverse mode, i.e. using electricity to 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) .

[0005] 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) .

[0006] Typically, multiple of such cell units are stacked upon one another to form a "stack" of cell units, also referred to as 'cell repeat units' . Said stack is commonly arranged between two end plates provided on opposite sides of the stack, thus forming an electrochemical cell assembly. The end plates may serve as access points for supplying the cell stack with fluid, e.g., fuel and / or oxidant. For this, at least one of the end plates may comprise at least one through-hole formed therein to form a fluid port for supplying fluid from the outside of the electrochemical cell assembly to the stack of cell units.

[0007] In such electrochemical cell assemblies, sealing gaskets may be interposed between the end plates and between the individual cell units to achieve a fluid-tight, in particular gas-tight, seal of the cell stack.

[0008] During use of the cell assembly, the end plates may deform due to thermal stresses, posing a risk of fuel and / or oxidant leakage at the end plates.

[0009] It is an object of the present invention to improve sealing in an electrochemical cell assembly, in particular with respect to possible end plate distortion. According to a first aspect of the invention there is provided an electrochemical cell assembly according to claim 1 . The electrochemical cell assembly comprises an end plate assembly having an end plate , and a stack of cell units . Preferably, the electrochemical cell assembly comprises a first end plate assembly having a first end plate , and a second end plate assembly having a second end plate , and a stack of cell units . The stack of cell units comprises a plurality of cell units stacked upon one another along a stacking direction . The stack of cell units is preferably arranged on the end plate . Preferably, the stack of cell units is arranged, preferably held in compression, between the first end plate and the second end plate . The first and second end plates are preferably provided on opposite sides of the stack of cell units such that , when seen in the stacking direction, one of the end plates is located in front of the stack of cell units and the other one of the end plates is located behind the stack of cell units .

[0010] The first end plate comprises at least one through-hole formed therein to form a fluid port for transporting fluid between the outside of the electrochemical cell assembly and the stack of cell units . In other words , at least one through-hole is provided in the end plate , said at least one through-hole forming a fluid port for transporting fluid between the outside of the electrochemical cell assembly and the stack of cell units . Preferably, the first end plate comprises at least one through-hole formed therein to form a fluid port for transporting fluid between the outside of the electrochemical cell assembly and the stack of cell units and / or the second end plate comprises at least one through-hole formed therein to form a fluid port for transporting fluid between the outside of the electrochemical cell assembly and the stack of cell units . In other words , at least one through-hole is provided in the first end plate and / or at least one through-hole is provided in the second end plate , said at least one through-hole forming a fluid port for transporting fluid between the outside of the electrochemical cell assembly and the stack of cell units . Transporting fluid between the outside of the electrochemical cell assembly and the stack of cell units may mean supplying fluid from the outside of the electrochemical cell assembly to the stack of cell units or may mean removing fluid from the stack of cell units to the outside of the electrochemical cell assembly . Preferably, the through-hole extends through the end plate concerned in the stacking direction .

[0011] Said at least one through-hole ( that is each of said one or more through-holes ) is associated with a sealing device . This , however, does not exclude that the end plate ( e . g . the first end plate and / or the second end plate ) comprises additional through-holes ful filling di f ferent functions ( e . g . for mounting or for electrical connection to the stack) . Said sealing device defines , preferably delimits , a fluid channel , preferably along the stacking direction, for guiding fluid, particularly fuel or oxidant (preferably fuel ) , between the associated through-hole in the end plate and the stack of cell units . Thus , the sealing device provides a fluid guiding function . Preferably, the sealing device is also configured to prevent loss of fluid between the end plate and the stack of cell units . Thus , the sealing device preferably provides a sealing function . The sealing device is located between the end plate and the stack of cell units , preferably at a position locally corresponding to the position of the through-hole in the end plate .

[0012] The sealing device comprises a sleeve and a first gasket . Said first gasket is located on a first face , preferably first end face , of the sleeve , said first face preferably facing the end plate . Thus , the first gasket preferably is interposed between the end plate and the sleeve .

[0013] The sleeve of the sealing device is positioned at least partially in a recess formed in a surface of the end plate , said surface facing the stack of cell units . That is to say, the end plate ( first end plate and / or the second end plate ) may have a groove or recess formed in a surface facing the stack of cell units , wherein the sleeve of the sealing device is positioned at least partially in said groove or recess . Thus , the groove or recess is designed to at least partially accommodate the sealing device .

[0014] The proposed configuration allows for improved sealing of the fluid pathways in the electrochemical cell assembly, while not ( signi ficantly) increasing the height of the assembly . Speci fically, the recess formed in the end plate securely holds the sealing device in place during use of the cell assembly, thus signi ficantly reducing leaking rates because shi fting of the sealing device due to possible end plate distortion may be avoided . In addition, because the sealing device is at least partially located in the recess in the end plate , a height of the assembly in stacking direction is reduced . Furthermore , the proposed configuration eases manufacturing of the cell assembly as the recess may act as locating features for the sealing device and, thus , may hold the sealing device in place during assembly . Furthermore , the design of the sealing device comprising a sleeve and a gasket allows to enhance load applied via the sealing device relative to load trans ferred to other regions of the stack, thus ensuring fluid-tight sealing, while avoiding damage to other parts of the cell unit ( e . g . to electrochemically active layers of the cell units ) .

[0015] Preferably, each of the through-holes formed in a respective end plate ( first end plate and / or second end plate ) is associated with a recess to ( at least partially) accommodate the respective sealing device .

[0016] Preferably, the recess is configured to hold the sealing device in alignment with the associated through-hole laterally, i . e . in a plane perpendicular to the stacking direction, preferably by a form- fit connection ( in other words , an interference fit ) . This further improves sealing performance and reliability . Preferably, the recess (and thus a sealing device positioned in said recess) surrounds an associated through- hole, more preferably is arranged coaxially to the through- hole.

[0017] In some embodiments, the sealing device is form-f ittingly held in said recess. Thus, the sealing device may be positioned in the recess forming a form-fit connection acting between the end plate and the sealing device in a plane perpendicular to the stacking direction.

[0018] The form-fit connection may be formed by a face of the sealing device (primarily a face of the sleeve) , said face being directed radially outwards, and by a face of the end plate, said face being directed radially inwards and opposed to said face of the sealing device.

[0019] In some embodiments, the recess has a negative shape of the outer contour of the sealing device.

[0020] In some embodiments, the sleeve is, preferably fluid- tightly, bonded to the end plate. This may obviate the need for a seal between the end plate and the sleeve, thus further reducing potential leaking paths. In such embodiments, the face of the sleeve that is facing the end plate may be devoid of a gasket, which eases manufacturing due to reduced part count. Thus, the sealing device may comprise a gasket only on the face of the sleeve that is facing the stack of cell units. In such embodiments, the first face of the sleeve mentioned above (i.e. the face being provided with a gasket or stack of gaskets) denotes the face facing the stack of cell units. The sleeve may be materially bonded to the end plate. In preferred embodiments, the sleeve is bonded to the end plate by brazing. Brazing is particularly advantageous for metalceramic bonding.

[0021] In some embodiments, a depth of the recess along the stacking direction is at least 5%, preferably at least 10%, preferably at least 15%, and maximum 35%, preferably maximum 30%, preferably maximum 25%, preferably maximum 20% of a thickness of the sealing device along the stacking direction. This has proven advantageous with regards to a secure fixture of the sealing device in said recess.

[0022] In some embodiments, the sealing device further comprises at least one, preferably two, further gaskets stacked upon said first gasket along the stacking direction, thus forming a first stack of gaskets. Or, to put it differently, the sealing device may comprise a sleeve, preferably spacer sleeve, and a first stack of gaskets. Said first stack of gaskets comprises a plurality of gaskets, that is two or more, preferably three, gaskets, stacked upon one another along the stacking direction. That is, the first stack of gaskets is a multilayer of gaskets. Said first stack of gaskets is located on a first face, preferably first end face, of the sleeve, said first face facing the (neighbouring) end plate. Thus, the first stack of gaskets is interposed between the end plate and the sleeve. This configuration further improves sealing of the fluid pathways as the multiple gasket concept - in addition to the retaining function of the recess - increases the compliance to end plate distortion, thus signi ficantly reducing leak rates .

[0023] In addition, it may be advantageous i f the first gasket or first stack of gaskets is , preferably fully, accommodated in the recess formed in the end plate . In this way, the gasket or gaskets may securely be held in place during assembly and use of the cell assembly .

[0024] According to a second aspect of the invention there is provided an electrochemical cell assembly according to claim 10 . The electrochemical cell assembly comprises an end plate assembly having an end plate , and a stack of cell units . Preferably, the electrochemical cell assembly comprises a first end plate assembly having a first end plate , a second end plate assembly having a second end plate , and a stack of cell units . The stack of cell units comprises a plurality of cell units stacked upon one another along a stacking direction . The stack of cell units is preferably arranged on the end plate . Preferably, the stack of cell units is arranged, preferably held in compression, between the first end plate and the second end plate .

[0025] The end plate comprises at least one through-hole formed therein to form a fluid port for transporting fluid between the outside of the electrochemical cell assembly and the stack of cell units . Preferably, the first end plate comprises at least one through-hole formed therein to form a fluid port for transporting fluid between the outside of the electrochemical cell assembly and the stack of cell units and / or the second end plate comprises at least one through-hole formed therein to form a fluid port for transporting fluid between the outside of the electrochemical cell assembly and the stack of cell units.

[0026] Said at least one through-hole (that is each of said one or more through-holes) is associated with a sealing device. This, however, does not exclude that the end plate (e.g. first end plate and / or the second end plate) comprise additional through-holes fulfilling different functions (e.g. for mounting or electrical connection to the stack of cell units) . Said sealing device defines, preferably delimits, a fluid channel, preferably along the stacking direction, for guiding fluid, particularly fuel or oxidant, between the associated through-hole in the end plate and the stack of cell units. Preferably, the sealing device is also configured to prevent loss of fluid between the end plate and the stack of cell units. The sealing device is located between the end plate and the stack of cell units, preferably at a position locally corresponding to the position of the through-hole in the end plate.

[0027] In this case, the sealing device comprises a sleeve, preferably spacer sleeve, and a first stack of gaskets. Said first stack of gaskets comprises a plurality of gaskets, that is two or more, preferably three, gaskets, stacked upon one another along the stacking direction. That is , the first stack of gaskets is a multilayer of gaskets . Said first stack of gaskets is located on a first face , preferably first end face , of the sleeve , said first face facing the (neighbouring) end plate . Thus , the first stack of gaskets is interposed between the end plate and the sleeve .

[0028] The proposed configuration allows for improved sealing of the fluid pathways in the electrochemical cell assembly . Speci fically, the multiple gasket concept increases the compliance of the sealing device to the above-described end plate distortion, thus signi ficantly reducing leak rates . Additional advantages and optional features of the sealing device described above in connection with the first aspect are also applicable to the second aspect .

[0029] In some embodiments of the second aspect , the sealing device may be held in alignment with the associated through-hole laterally, i . e . in a plane perpendicular to the stacking direction, by a form- fit connection acting between the end plate and the sealing device in a plane perpendicular to the stacking direction . This allows the sealing device to be held securely in place during manufacture of the cell and during use , thus signi ficantly improving sealing performance and reliability . This is particularly advantageous as end plate may undergo thermal stresses . In some embodiments , the form- fit connection acts between the end plate and the sleeve . In some embodiments , the form- fit connection acts between the end plate and at least one gasket of the sealing device . In some embodiments , the form- fit connection acts between the end plate and both the sleeve and at least one gasket of the sealing device .

[0030] Preferably, the form- fit connection is configured to centre the sealing device (preferably sleeve ) around the associated through-hole . Preferably, the form- fit connection is configured such that the through-hole in the end plate and the fluid channel defined by the sealing device are arranged in fluid communication with each other, preferably coaxially to each other .

[0031] The form- fit connection may be formed by a face of the sealing device (primarily a face of the sleeve ) , said face being directed radially outwards and by a face of the end plate , said face being directed radially inwards and opposed to said face of the sealing device .

[0032] In a preferred embodiment , the sealing device , preferably the sleeve , is positioned partially in a groove or recess ( e . g . a recess described above in connection with the first aspect ) formed in a surface of the respective end plate facing the stack of cell units to form said form- fit connection . Such a configuration is easy to manufacture and provides improved stability against possible end plate distortion . Preferably, said recess has a negative shape of the outer contour of the sealing device .

[0033] The following optional features and advantages are applicable to both aspects : In some embodiments of either aspect , a spacer is provided between two adj acent , i . e . neighbouring, gaskets of the first stack of gaskets . Preferably, a spacer is provided between each pair of neighbouring gaskets . Such a spacer further improves distortion compliance as it allows to ef ficiently trans fer forces between the gaskets and, additionally, strengthens stack cohesion .

[0034] In some embodiments , a spacer may be provided between the sleeve and the first gasket or between the sleeve and the first stack of gaskets - alternatively or in addition to spacers provided between the gaskets . In such embodiments , the spacer may be , preferably f luid-tightly, bonded to the sleeve . The spacer may be materially bonded to the substrate . In preferred embodiments , the spacer may be bonded to the sleeve by brazing .

[0035] The spacer ( that is each of the one or more spacers ) may be a spacer sheet or spacer plate . Preferably, the spacer is a, particularly flat , annular ring ( spacer-ring) .

[0036] Preferably, the spacer comprises a central through-hole and the gaskets each comprise a central through-hole , wherein the spacer and the gaskets are arranged such that the through-hole of the spacer or spacers and the through-hole of the gaskets are aligned, preferably coaxially to each other ( and coaxially to the sleeve ) . It will be understood that the gasket or gaskets , respective spacer or spacers (where present ) , and respective sleeve need not be perfectly coaxially aligned; for example the gaskets may be si zed such that a coaxial misalignment does not result in the gaskets overhanging the through-hole . Preferably, the spacer is formed from a metallic material . More preferably, the spacer is formed from steel , more preferably stainless steel , more preferably coated stainless steel , more preferably alumina coated stainless steel . Exemplarily, the spacer may be formed from stainless steel type 441 (EN 1 . 4509 ) . Stainless steel has the advantage of high corrosion resistance and high strength, thus improving long-time performance of the sealing device under operating conditions of the cell units . In preferred embodiments , the spacer or spacers may be formed from a stainless steel having a thermally grown oxide coating .

[0037] In a preferred embodiment of the second aspect , the gaskets are formed from an exfoliated vermiculite material ( further details see below) and the spacer or spacers are formed from stainless steel . In this preferred embodiment , the sleeve is preferably formed from a ceramic material ( e . g . , alumina or other non-porous ceramic material ) .

[0038] In some embodiments of either aspect , the sealing device further comprises a second gasket or second stack of gaskets , said second gasket or second stack of gaskets being provided on a second face , preferably second end face , of the sleeve , said second face facing the stack of cell units . The second stack of gaskets preferably comprises two or more , preferably three , gaskets stacked upon one another along the stacking direction . Such a configuration further improves the sealing function of the sealing device . In embodiments having a second stack of gaskets , the second stack of gaskets may optionally comprise spacers provided between two adj acent gaskets of said second stack of gaskets . That is , a spacer may be provided between two adj acent gaskets of the second stack of gaskets .

[0039] The optional features and advantages explained above in connection with the first stack of gaskets and the spacer are also applicable to the second stack of gaskets .

[0040] Preferably, the first face and / or the second face of the sleeve extend perpendicular to the stacking direction . Preferably, the first face and / or the second face are end faces of the sleeve .

[0041] In preferred embodiments , the sleeve has a sleeve opening and the or each gasket has a gasket opening, wherein said sleeve opening and said gasket opening or gasket openings together form at least a section of the fluid channel for guiding fluid between the through-hole and the stack of cell units . Advantageously, the gasket opening or gasket openings are aligned with the sleeve opening of the sleeve . Preferably, the sleeve opening and the gasket opening or gasket openings are arranged coaxially to each other . This has proven advantageous with regards to homogeneous load distribution and reliable sealing of the fluid channel . In preferred embodiments , the sleeve is a hollow cylinder, preferably disk, having a central ( axial ) sleeve opening or through-hole .

[0042] In preferred embodiments , the or each gasket is an annular ring ( sealing ring) , i . e . ring-shaped, having a central gasket opening . The annular ring may be flat on opposing sides thereof ( those sides facing the end plate and sleeve or neighboring gasket or neighboring spacer, as appropriate ) .

[0043] In some embodiments of either aspect of the invention, the sleeve has a first recess formed in its first face , wherein the first gasket or the first stack of gaskets is positioned at least partially in said recess .

[0044] Advantageously, this may further improve performance of the electrochemical cell assembly because a height of the assembly in stacking direction can be further reduced while improving compliance to the sealing device .

[0045] As set out above , in connection with the first aspect , the first face of the sleeve may be a face facing the stack of cell units . Thus , the recess may be formed on a face of the sleeve that is facing the stack of cell units . Alternatively, in connection with the first aspect , the first face of the sleeve may be a face facing the end plate . Thus , the recess may be formed in a face of the sleeve that is facing the end plate . In connection with the second aspect , the first face denotes a face of the sleeve that is facing the end plate . Thus , in connection with the second aspect , the optional first recess is formed in a face of the sleeve facing the end plate .

[0046] Alternatively or in addition to said first recess , the sleeve may have a second ( opposite ) recess formed in its second face . This is particularly favourable for embodiments having a second gasket or a second stack of gaskets . In such embodiments , preferably said second gasket or said second stack of gaskets is at least partially accommodated in said second recess .

[0047] The or each recess in the sleeve may be formed between an outer circumferential wall of the sleeve and an inner circumferential wall of the sleeve . Preferably, said outer circumferential wall defines an outer surface of the sleeve and said inner circumferential wall defines the sleeve opening . In embodiments wherein the or each gaskets has gasket opening ( e . g . an annular ring having a central gasket opening) , preferably the inner circumferential wall reaches through said gasket opening .

[0048] In some embodiments , the or each recess formed in the sleeve may be an annular recess . This may be particularly advantageous , when the or each gasket takes the form of an annular ring .

[0049] Preferably, the or each recess formed in the sleeve surrounds a sleeve opening of the sleeve , i . e . the central sleeve opening of a cylindrical , preferably disk-shaped, sleeve . Preferably, the sleeve is formed from a ceramic material . More preferably, the sleeve is formed from aluminium oxide ( alumina ) . Ceramic materials have the advantage of high mechanical sti f fness and superior creep stability, thus improving long-time sealing function .

[0050] Preferably, the gasket or gaskets are formed from an exfoliated vermiculite material . The exfoliated vermiculite material may comprise exfoliated vermiculite or consist of exfoliated vermiculite . Vermiculite is a layered silicate with the chemical sum formula (K, Mg, Fe ) ( Si , Al )40io (OH)2• The exfoliated vermiculite material may be thermally or chemically exfoliated . The exfoliated vermiculate material may comprise a diluent filler, an elastomer and / or steatite . Examples for an exfoliated vermiculite material comprising a diluent filler and an elastomer are the materials Thermiculite 815 , Thermiculite 835 and Thermiculite 715 ( registered trademarks of the Flexitallic group ) . An example for an exfoliated vermiculite material comprising steatite is the material Thermiculite 866 ( registered trademark of the Flexitallic group ) .

[0051] The first end plate and the second end plate may each comprise at least one , preferably more than one , preferably two , alternatively four, through-holes . Preferably, each through-hole in the first end plate is associated with a corresponding through-hole in the second end plate . Preferably, said associated through-holes are aligned with each other along the stacking direction . In an alternative embodiment , the first end plate or the second end plate is devoid of a through-hole . That is , only the second end plate or the first end plate comprises at least one through-hole formed therein . Alternatively, the first end plate and the second end plate comprise di f fering numbers of through-holes .

[0052] Preferably, in case several sealing devices are provided, said sealing devices are configured identically .

[0053] Preferably, the stack of cell units is held in compression between said first end plate and said second end plate . For this , the electrochemical cell assembly may comprise additional compression means for tensioning said first end plate and said second end plate towards each other along the stacking direction . Such compression means are known in the art , and may e . g . include tension rods , compression springs or bolts , clamps or other means for compression .

[0054] In some embodiments of either aspect of the invention, the end plate assembly, preferably, the first end plate assembly and / or the second end plate assembly, may each further comprise an insulation plate located between the end plate and the stack of cell units . The insulation plate is configured to electrically insulate end plate and stack of cell units . The insulation plate may be formed from an electrically insulating material . The insulation plate may be formed from mica . The insulation plate may be formed from a ceramic material ( e . g . , alumina ) . The insulation plate - for each of said one or more through-holes formed in the end plate - may have a respective through-hole formed therein at a position locally corresponding to the position of the through-hole formed in the end plate . Preferably, the sealing device associated with a respective through-hole of the end plate is received in the corresponding through-hole of the insulation plate . This further improves sealing of the electrochemical cell assembly without causing undue compression on the cell stack that may damage the cell units . More speci fically, as the sealing devices are received in the through-holes of the insulation plate , compression forces introduced into the sealing devices by the end plates are trans ferred directly to the stack of cell units , preferably without trans ferring load to the insulation plate . Thus , a load path via the sealing devices may be decoupled from a load path via the insulation plate , which allows for applying location-dependent compression forces .

[0055] Preferably, a thickness , i . e . extension, of the sealing device along the stacking direction is larger than a thickness of the insulation plate . This ensures the fluid channel ( for fuel or oxidant ) compression is predominantly through the gasket stack and not the insulation plate . This further improves sealing between the base plate and the first cell unit .

[0056] In some embodiments of either aspect , the end plate assembly, preferably the first end plate assembly and / or the second end plate assembly, may further comprise a current collector plate located between the insulation plate and the stack of cell units .

[0057] The sealing devices described above are applicable to various types of cell units . In some preferred embodiments , the cell units are fuel cell units or electrolyser cell units , preferably solid oxide cell units , preferably solid oxide fuel cell units ( SOFC ) or solid oxide electrolyser cell units ( SOEC ) . In the case of fuel cell operation, the fuel may be , for example , a hydrocarbon or hydrogen and oxidant may be air or oxygen . In the case of electrolyser cell operation, the fuel may be , for example , steam, and a sweep gas ( for example air ) may be provided in the oxidant channels .

[0058] The cell units may comprise each at least one , preferably two or more , through-holes , said through-holes being in fluid communication with the active layers of the cell units allowing for fluid entering and exiting the cell units ( e . g . via respective fluid channels ) . Thus , the through-holes in the cell units may form fluid ports of the cell units . The stack of cell units may further comprise gaskets , preferably sealing rings , configured to seal said fluid ports of the cell units . In the stack, the column of fluid ports of the stacked cell units and the optional gaskets of the stack of cell units together form a fluid pathway ( or chimney) extending along the stacking direction, said fluid pathway serving as an internal mani fold for distributing fluid inside the stack of cell units. The stack of cell units, in addition to the cell units, may comprise further components, such as electrical connectors, electrical contact (or current collection) plates (e.g. monopole or endpole plates) or additional sealing gaskets.

[0059] Further embodiments are derivable from the following description and the drawings.

[0060] In the drawings :

[0061] Fig. 1 shows a perspective view of an embodiment of an electrochemical cell assembly;

[0062] Fig. 2 shows a perspective section of the electrochemical cell assembly according to Fig. 1;

[0063] Fig. 3 shows a cross-sectional view of the electrochemical cell assembly according to Fig. 1;

[0064] Fig. 4 shows a detail of a sealing device of the electrochemical cell assembly according to Fig. 1;

[0065] Fig. 5 shows a detail of a sealing device according to a further embodiment;

[0066] Fig. 6 shows a detail of a sealing device according to a further embodiment; Fig . 7 shows a detail of a sealing device according to a further embodiment ;

[0067] Fig . 8 shows a detail of a sealing device according to a further embodiment ;

[0068] Fig . 9 shows a detail of a sealing device according to a further embodiment in partial sectional view;

[0069] Fig . 10 shows a detail of a sealing device according to a further embodiment in partial sectional view;

[0070] Fig . 11 shows a detail of a sealing device according to a further embodiment in partial sectional view;

[0071] Fig . 12 shows a detail of a sealing device according to a further embodiment in partial sectional view; and

[0072] Fig . 13 shows a detail of a sealing device according to a further embodiment in partial sectional view .

[0073] Repeat use of reference symbols in the present speci fication and drawings is intended to represent the same or analogous features or elements .

[0074] Figure 1 schematically shows an exemplary embodiment of an electrochemical cell assembly 10 . The electrochemical cell assembly 10 comprises a first end plate assembly 12 having a first end plate 14 , a second end plate assembly 16 having a second end plate 18 , and a stack 20 of cell repeat units 22 . Figures 1 to 3 are intended to primarily provide an overview of the electrochemical cell assembly 10 and its components in general by way of example .

[0075] As shown in Figure 1 , the stack 20 is arranged between the first end plate assembly 12 and the second end plate assembly 16 . In the assembled state , the stack 20 is preferably held in a compressed state between the first end plate assembly 12 and the second end plate assembly 16 . For this , the electrochemical cell assembly 10 may comprise additional compression means known in the art (not shown) , such as tension rods , compression springs or bolts .

[0076] Referring to Fig . 2 , the stack 20 comprises a plurality of cell units 22 , also referred to herein as cell repeat units 22 , said cell repeat units 22 being stacked upon each other along a stacking direction 24 . As set out above , the cell repeat units 22 may be fuel cell units , electrolyser cell units or reversible cell units comprising electrochemically active layers (not shown) .

[0077] In the embodiment shown, exemplarily, the first end plate assembly 12 and the second end plate assembly 16 are configured identically . In the following, the structure of the end plate assemblies 12 , 16 is described by way of example using the first end plate assembly 12 .

[0078] Referring to Fig . 3 , the first end plate assembly 12 comprises the first end plate 14 . The first end plate 14 comprises at least one through-hole 26 formed therein, in this example there are two through-holes 26 (see also Fig. 1 for the second end plate 18) but any appropriate number of through-holes may be provided, for example three, four, six, and so forth. The through-holes 26 extend along the stacking direction 24 and form respective fluid ports 28 for transporting fluid between the outside of the electrochemical cell assembly 10 and the stack 20 of cell repeat units 22.

[0079] In the example shown, each through-hole 26 in the first end plate 14 is associated with a corresponding through-hole 26 in the second end plate 18. In an alternative embodiment, the second end plate 18 is devoid of such through-holes 26.

[0080] In the embodiment shown, the first end plate assembly 12 further comprises an optional insulation plate 30. The first end plate 14 and the insulation plate 30 are stacked upon each other along the stacking direction 24. In the electrochemical cell assembly 10, the insulation plate 30 is located between the first end plate 14 and the stack 20 of cell repeat units 22 (see e.g. Fig. 2) . Accordingly, an insulation plate 30 of the second end plate assembly 16 is located between the second end plate 18 and the stack 20 of cell repeat units 22.

[0081] Preferably, the insulation plate 30 is formed from an electrically insulating material, e.g. from mica or ceramic (e.g., alumina) . Exemplarily, the insulation plate 30 comprises at least one through-hole 32 extending along the stacking direction 24 ( see Fig . 2 ) , in this example two through-holes 32 (but a greater number of through-holes may be provided as appropriate ) . The through-holes 32 are arranged at positions locally corresponding to the positions of the through-holes 26 in the first end plate 14 ( see Fig . 2a and 2b ) . Preferably, the through-holes 32 in the insulation plate 30 are arranged coaxially to the through-holes 26 in the first end plate 14 . Preferably, the diameter of the through-holes 26 in the first end plate 14 is smaller than the diameter of the through-holes 32 in the insulation plate 30 .

[0082] Referring to Fig . 2 and 3 , it can be seen that each cell repeat unit 22 has at least one through-hole 34 , in this example two through-holes 34 (but a greater number of through-holes may be provided as appropriate ) , said through-holes 34 being in fluid communication with the active layers of the cell unit 22 , e . g . via respective fluid channels (not shown) . Thus , the through-holes 34 form fluid ports of the respective cell repeat units 22 . In the embodiment shown, the stack 20 of cell repeat units 22 further comprises sealing gaskets 38 located between the individual cell repeat units 22 and surrounding the through-holes 34 . Preferably, the through-holes 34 in the cell repeat units 22 are arranged coaxially to the through- holes 26 in the first end plate 14 and the through-holes 32 in the insulation plate 30 ( see e . g . Fig . 3 ) . Referring to Fig . 3 , it can be seen that each through-hole 26 formed in the first end plate 14 is associated with a respective sealing device 42 ( in Fig . 3 only schematically shown) . In the embodiment shown, exemplarily, the sealing devices 42 are configured identically . In this example , the sealing devices 42 are arranged in a respective through- hole 32 of the optional insulation plate 30 .

[0083] Each sealing device 42 defines a fluid channel 43 for guiding fluid from the associated through-hole 26 formed in the end plate 14 to the stack 20 of cell repeat units 22 ( further details below) and is configured to prevent loss of fluid between the end plate 14 , 18 with the associated through-hole 26 formed therein and the stack 20 of cell repeat units 22 .

[0084] Referring to Figures 4 and 5 , the structure of a sealing device 42 according to a first embodiment is described by way of example using one of the sealing devices 42 .

[0085] The sealing device 42 comprises a sleeve 44 and at least one gasket 56 .

[0086] As shown in Figure 4 , the sleeve 44 takes the form of a disk (hollow cylinder ) having a central sleeve opening ( through-hole ) 46 and a closed circumferential wall surrounding the sleeve opening 46 in a circumferential direction . The sleeve 44 comprises a first end face 50 and a second end face 52 opposite the first end face 50 . In the assembled electrochemical cell assembly 10 , the first end face 50 is facing the neighbouring end plate 14 with the associated through-hole 26 formed therein - i . e . not facing the other of the two end plates . The second end face 52 is facing the stack 20 of cell repeat units 22 .

[0087] Preferably, the sleeve 44 is formed from a ceramic material , preferably alumina .

[0088] As exemplarily shown in Figure 4 , the gaskets 56 are annular sealing rings each having a central gasket opening 57 . The gaskets 56 are preferably formed from an exfoliated vermiculite material . Said vermiculite material may be thermally or chemically exfoliated .

[0089] In the embodiment shown in Figure 5 , the first end face 50 is provided with a first stack 54 of gaskets 56 , said stack 54 comprising a plurality of , in the example three , gaskets 56 stacked upon one another along the stacking direction 24 . It will be noted that in Figure 5 only a portion of the end plate 14 is shown for clarity of the figure .

[0090] Further, Figure 5 ( and subsequent Figures ) exempli fy the sealing device with respect to the end plate 14 , but said sealing devices are equally applicable to end plate 14 as indicated in Figures 1 , 2 , and 3 (where such through-holes are present ) . In the example of Figure 5, the stack 54 of gaskets 56 further comprises optional spacers 58 located between two adjacent gaskets 56. In other words, between two adjacent gaskets 56, there is provided a spacer 58. The spacers 58 preferably are flat annular rings each having a central spacer opening 59. Preferably, the spacers 58 are formed from stainless steel, more preferably coated stainless steel. Alternatively (not shown) the gaskets in the stack of gaskets may not be separated by spacers.

[0091] As shown in Fig. 5, the gaskets 56, the spacers 58 and the sleeve 44 are aligned, preferably arranged coaxially to each other, such that the column of gaskets 56, spacers 58 and the sleeve 44 together delimit an inner fluid pathway, i.e. the above-described fluid channel 43. In other words, the central sleeve opening 46, the central gasket openings 57, and the central spacer openings 58 together form the fluid channel 43. It will be understood that the central sleeve opening 46, the central gasket openings 57, and the central spacer openings 58 need not be perfectly coaxially aligned .

[0092] Referring to Figures 3 and 5, it can be seen that an aligned column of through-holes 26, fluid channel 43 (central sleeve opening 46, central gasket openings 57, and central spacer openings 59) and through-holes 34 of the cell repeat units 22 forms a fluid pathway or chimney extending throughout the electrochemical cell assembly 10 along the stacking direction 24. In further embodiments not shown, the sleeve 44 may be bonded to the endplate , for example by brazing . In such cases , no gasket ( or stack thereof ) is provided between the sleeve 44 and the neighbouring end plate 14 , 18 .

[0093] Figure 6 shows a further embodiment of a sealing device 42 . The sealing device 42 of this embodiment is identical to the sealing device of Figure 4 , except that a second stack 60 of gaskets 56 is provided on the second end face 50 of the sleeve 44 . To avoid repetition, aspects of Figure 6 that are generally the same as shown in Figure 5 will not be described again, and like reference numerals are used to describe like features .

[0094] Figure 7 shows a further embodiment of an electrochemical cell assembly 10 , which is identical to the embodiment of Figure 5 , except that the sealing device 42 is partially positioned in a recess 62 formed in the surface 64 of the first end plate 14 facing the stack 20 .

[0095] More speci fically, each of the through-holes 26 in the end plate 14 is surrounded by such a recess 62 formed in the surface 64 of the end plate 14 . In the example , a depth 66 of said recess 62 along the stacking direction 24 is such that the first stack of gaskets 54 ( including the gaskets 56 and the spacers 58 , where present ) is fully accommodated in said recess 62 and also part of the sleeve 44 .

[0096] Alternatively, in some examples the depth 66 of said recess 62 may be such that the stack of gaskets ( including the gaskets 56 and the spacers 58 , where present ) is partially accommodated in said recess 66 .

[0097] Preferably, the depth 66 of said recess 62 along the stacking direction 24 is at least 5% , preferably at least 10% , preferably at least 15% , and maximum 35% , preferably maximum 30% , preferably maximum 25% , preferably maximum 20% of a thickness 68 of the sealing device 42 along the stacking direction 24 .

[0098] Preferably, the sealing device is held in the recess 62 in a form- fitting manner in a plane perpendicular to the stacking direction 24 . As shown in Figure 7 , the recess preferably has a negative shape of the outer contour of the sealing device 42 .

[0099] The embodiment according to Figure 7 may additionally comprise a second stack 60 of gaskets 56 as shown in Figure 6.

[0100] Figure 8 shows a further embodiment of a sealing device 42 . The configuration of this embodiment is identical to the configuration of Figure 7 , except that only a single gasket 56 is provided on the first face 50 of the sleeve 44 . A single gasket 56 has been found to provide adequate sealing when a recess 62 is provided . The sealing device 42 is positioned at least partially in the recess 62 . In this case , the sleeve 44 is positioned at least partially in the recess . Optionally, a second gasket 56 or a second stack 60 of gaskets 56 (not shown) may be provided on the second end face 52 of the sleeve 44. To avoid repetition, aspects of

[0101] Figure 8 that are generally the same as shown in Figure 7 will not be described again, and like reference numerals are used to describe like features.

[0102] In further embodiments not shown, the sleeve 44 may be bonded to the endplate 14, 18, for example by brazing. In such cases, no gasket (or stack thereof) is provided between the sleeve 44 and the end plate 14, 18.

[0103] Figure 9 shows a further embodiment of a sealing device 42, wherein the gaskets 56 and the optional spacers 58 are at least partially accommodated in respective recesses 70, 72 formed in the sleeve 44. Specifically, the sleeve 44 has a first recess 70 formed in its first face 50 and an opposite second recess 72 formed in its second face 52. In other embodiments, the sleeve 44 may have only one of said recesses 70, 72 (see e.g. Figure 13 below) .

[0104] In the example, each recess 70, 72 takes the form of an annular recess that is delimited perpendicular to the stacking direction 24 by an outer circumferential wall 74 of the sleeve 44 and an inner circumferential wall 76 of the sleeve 44. As shown in Figure 9, the inner circumferential wall 76 delimits the sleeve opening 46 and reaches into the gasket openings 57 and the spacer openings 59. The outer circumferential wall 76 defines an outer surface 78 (see Fig. 4) of the sleeve 44. Preferably, each recess 70 , 72 is designed such that a respective gap is formed between the stack 54 of gaskets 56 and either or both the outer circumferential wall 74 and the inner circumferential wall 76 .

[0105] Referring to Figure 10 , it can be seen that the concept shown in Figure 9 for multiple gaskets 56 is also applicable to embodiments in which the sealing device 42 comprises only a single gasket 56 in recesses 70 , 72 on either or both of its faces 50 , 52 .

[0106] Figures 11 and 12 show further embodiments , which are identical to the embodiments of Figures 9 and 10 , except that the sealing device 42 is partially positioned in a recess 62 formed in the surface 64 of the first end plate 14 facing the stack 20 . To avoid repetition, aspects of Figures 11 and 12 that are generally the same as shown in Figures 9 and 19 will not be described again, and like reference numerals are used to describe like features .

[0107] As set out above , while the sleeves 44 shown in Figures 9 to 12 have two opposite recesses 70 , 72 formed therein, in further embodiments , the sleeve 44 may have only one of said recesses 70 , 72 .

[0108] Figure 13 shows such an embodiment , wherein the sleeve 44 has a recess 72 formed at its second face 52 , but is devoid of a recess 70 at its first face 50 . Exemplarily, there is provided a second stack 60 of gaskets 56 at least partially accommodated in said second recess 72 in the sleeve 44 and a first stack 54 of gaskets 56 provided on the first face 50 of the sleeve 44 , said stack of gaskets at least partially accommodated in the recess of the end plate . In the example shown, the first stack 54 of gaskets 56 is positioned in a recess 62 formed in the first end plate 14 similar to the example shown in Figure 7 . It will be understood that the sleeve 44 may equally have a recess 70 formed at its first face 50 ( facing the end plate 14 ) , but be devoid of a recess 72 at its second face 52 ( facing the stack) .

[0109] In further embodiments , a spacer may be provided between the sleeve and a first gasket or between the sleeve and a first stack of gaskets - alternatively or in addition to spacers provided between the gaskets . In such embodiments , the spacer may be , preferably f luid-tightly, bonded to the sleeve . The spacer may be materially bonded to the substrate , for example by brazing .

Claims

Claims1. An electrochemical cell assembly (10) comprising an end plate assembly (12) having an end plate ( 14 ) , and a stack (20) of cell units (22) , comprising a plurality of cell units (22) stacked upon one another along a stacking direction (24) , said end plate (14) comprising at least one through-hole (26) formed therein to form a fluid port (28) for transporting fluid between the outside of the electrochemical cell assembly (10) and the stack (20) of cell units (22) , said through-hole (26) being associated with a sealing device (42) , said sealing device (42) defining a fluid channel (43) for guiding fluid between the through-hole (26) and the stack (20) of cell units (22) , said sealing device (42) comprising a sleeve (44) and a first gasket (56) , said first gasket (56) being provided on a first face (50) of the sleeve (44) , wherein the sleeve (44) is positioned at least partially in a recess (62) formed in a surface (64) of the end plate (14) , said surface (64) facing the stack (20) of cell units (22) .

2. The electrochemical cell assembly (10) according to claim 1, wherein said recess (62) is configured to hold the sealing device (42) in alignment with theassociated through-hole (26) in a plane perpendicular to the stacking direction (24) .

3. The electrochemical cell assembly (10) according to claim 1 or 2, wherein said recess (62) surrounds an associated through-hole (26) in the end plate (14) , preferably which is arranged coaxially to the through- hole (26) .

4. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the sealing device is form-f ittingly held in said recess (62) .

5. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the sleeve (44) is bonded to the end plate (14) , preferably by brazing .

6. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein a depth (66) of said recess (62) along the stacking direction (24) is at least 5%, preferably at least 10%, preferably at least 15%, and maximum 35%, preferably maximum 30%, preferably maximum 25%, preferably maximum 20% of a thickness (68) of the sealing device (42) along the stacking direction (24) .

7. The electrochemical cell assembly (10) according to any one of the preceding claims, said first face (50) facing the end plate (14) .

8. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein said firstgasket (56) is, preferably fully, accommodated in said recess ( 62 ) .

9. The electrochemical cell assembly (10) according to the preceding claim, the sealing device (42) further comprising at least one, preferably two, further gaskets (56) stacked upon said first gasket (56) along the stacking direction (24) forming a first stack of gaskets ( 54 ) .

10. An electrochemical cell assembly (10) comprising an end plate assembly (12) having an end plate (14) , and a stack (20) of cell units (22) , comprising a plurality of cell units (22) stacked upon one another along a stacking direction (24) , said end plate (14) comprising at least one through-hole (26) formed therein to form a fluid port (28) for transporting fluid between the outside of the electrochemical cell assembly (10) and the stack (20) of cell units (22) , said through-hole (26) being associated with a sealing device (42) , said sealing device (42) defining a fluid channel (43) for guiding fluid between the through-hole (26) and the stack (20) of cell units (22) , said sealing device (42) comprising a sleeve (44) , and a first stack (54) of gaskets (56) comprising two or more, preferably three, gaskets (56) stackedupon one another along the stacking direction (24) , said first stack (54) of gaskets (56) being provided on a first face (50) of the sleeve (44) , said first face (50) facing the end plate (14) .

11. The electrochemical cell assembly (10) according to any of claims 9 or 10, wherein a spacer (58) is provided between two adjacent gaskets (56) of said first stack (54) of gaskets (56) .

12. The electrochemical cell assembly (10) according to the preceding claim, said spacer (58) being a flat annular ring.

13. The electrochemical cell assembly (10) according to any of claims 11 or 12, said spacer (58) being formed from steel, preferably stainless steel, more preferably coated stainless steel, more preferably alumina coated stainless steel.

14. The electrochemical cell assembly (10) according to any of claims 10 to 13, wherein the sealing device (42) is held aligned with the associated through-hole (26) by a form-fit connection acting between the end plate (14) and the sealing device (42) in a plane perpendicular to the stacking direction (24) .

15. The electrochemical cell assembly (10) according to the preceding claim, wherein the form-fit connection is configured to centre the sealing device (42) around the through-hole (26) .

16. The electrochemical cell assembly (10) according to claim 14 or 15, wherein the form-fit connection is formed by a face of the sealing device (42) being directed radially outwards and by a face of the end plate (14) being directed radially inwards and opposed to said face of the sealing device (42) .

17. The electrochemical cell assembly (10) according to any of claims 14 to 16, wherein the sealing device (42) is positioned partially in a recess (62) formed in the end plate (14) to form said form-fit connection .

18. The electrochemical cell assembly (10) according to any one of the preceding claims, the sealing device (42) further comprising a second gasket, preferably a second stack (60) of gaskets (56) , said second gasket or second stack (60) of gaskets (56) being provided on a second face (52) of the sleeve (44) , said second face (52) being opposite the first face (50) , preferably facing the stack (20) of cell units (22) .

19. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the sleeve (44) has a sleeve opening (46) and the or each gasket(56) has a gasket opening (57) , said sleeve opening (46) and said gasket opening (57) or gasket openings(57) together forming at least a section of the fluid channel (43) .

20. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the sleeve (44) is a disk (45) having a central sleeve opening (46) .

21. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the or each gasket (56) is an annular ring having a central gasket opening ( 57 ) .

22. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the sleeve (44) has a first recess (70) formed in its first face (50) , wherein the first gasket (56) or the first stack (54) of gaskets (56) is at least partially accommodated in said first recess (70) .

23. The electrochemical cell assembly (10) according to any one of the preceding claims when referring to claim 18, wherein the sleeve (44) has a second recess (72) formed in its second face (52) , wherein the second gasket (56) or the second stack (60) of gaskets (56) is at least partially accommodated in said second recess ( 72 ) .

24. The electrochemical cell assembly (10) according to claim 22 or 23, wherein the or each recess (70, 72) is formed between an outer circumferential wall (74) of the sleeve (44) and an inner circumferential wall (76) of the sleeve (44) , said outer circumferential wall (74) defining an outer surface (78) of the sleeve (44)and said inner circumferential wall (76) defining a sleeve opening (46) of the sleeve (44) .

25. The electrochemical cell assembly (10) according to any of claims 22 to 24, wherein the or each recess (70, 72) formed in the sleeve (44) is an annular recess surrounding a sleeve opening (46) of the sleeve (44) .

26. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the sleeve (44) is formed from a ceramic material.

27. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the sleeve (44) is formed from aluminium oxide.

28. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the or each gasket (56) is formed from an exfoliated vermiculite material .

29. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the end plate assembly (12) further comprises an insulation plate (30) located between the end plate (14) and the stack (20) of cell units (22) .

30. The electrochemical cell assembly (10) according to the preceding claim, said insulation plate (30) - for each of said one or more through-holes (26) formed in the end plate (14) - having a respective through-hole (32) formed therein at a position locallycorresponding to the position of the through-hole (26) formed in the end plate (14) , wherein the sealing device (42) associated with a respective through-hole (26) of the end plate (14) is received in said through-hole (32) of the insulation plate (30) .

31. The electrochemical cell assembly (10) according to any one of the preceding claims, wherein the cell units (22) are solid oxide cell units, preferably solid oxide fuel cell units (SOFC) or solid oxide electrolyser cell units (SOEC) .

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