Assembly device and system comprising an assembly device and at least one cell unit

Abstract

The invention relates to an assembly device (10) for assisting stacking of electrochemical cell units (102) to form a stack (100) of cell units, the assembly device comprising a support (14) having a support surface (18), an alignment device (24) for aligning the cell units relative to each other parallel to the support surface, the alignment device defines a receiving space for receiving cell units therein, the alignment device comprises at least one positioning pillar (26) that extends in a stacking direction perpendicular to the support surface, the at least one positioning pillar is configured to block a translational and / or a rotational movement of cell units positioned within the receiving space in a plane parallel to the support surface. The invention also relates to a system comprising such an assembly device and at least one cell unit as well as to a method of manufacturing an electrochemical cell stack.

Description

[0001] Title : Assembly device and system comprising an assembly device and at least one cell unit

[0002] Specification

[0003] The invention relates to the field of electrochemical cell stacks , in particular, fuel cell stacks and electrolyser cell stacks . More speci fically, the invention relates to an assembly device for assisting stacking of electrochemical cell units , to a system comprising an assembly device and at least one electrochemical cell unit , and to a method of manufacturing an electrochemical cell stack using an assembly device .

[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 H20 into hydrogen and oxygen . Reversible cells are capable of operating in both modes . Such electrochemical cells typically comprise electrochemically active layers that may be configured to allow for conversion of electrochemical fuel to electricity ( fuel cells ) or for decomposing a compound into its constituent parts using electricity ( electrolyser cells ) . The present invention specifically relates to solid oxide cells (SOCs) . Such solid oxide cells (SOCs) typically comprise an electrolyte layer formed from a solid oxide, e.g. from Yttria-stabilized zirconia (YSZ) , Gadolinia-doped Ceria, or Cerium Gadolinium Oxide (CGO) . SOCs can be run as solid oxide fuel cell (SOFC) or as solid oxide electrolyser cell (SOEC) .

[0005] 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. The end plates may serve as access points for supplying fluid from the outside of the electrochemical cell assembly to the stack of cell units. For example, at least one of the end plates may comprise a fluid port in the form of a through-hole for delivering fluid to the stack of cell units. Such electrochemical cell assemblies are known, for example, from WO 2020 / 126486 or WO 2022 / 175679.

[0006] It is an object of the present invention to facilitate and improve stacking of the cell units.

[0007] According to the invention, there is provided an assembly device with the features of claim 1. The assembly device is configured for assisting, i.e. for use in, stacking of electrochemical cell units along a stacking direction to form a stack of cell units. Preferably, the assembly device is configured for assisting, i . e . for use in, the assembly of an electrochemical cell assembly, comprising a plurality of cell units stacked upon one another along a stacking direction . The electrochemical cell assembly may additionally comprise a base plate on which the cell units are stacked .

[0008] The assembly device comprises a support , preferably support plate , for supporting the cell units ( and the optional base plate ) during stacking, and an alignment device for aligning the cell units relative to each other . The support , preferably support plate , has a support surface for, directly or indirectly, supporting the cell units during stacking . The support surface preferably extends in a first direction and in a second direction perpendicular to the first direction . Preferably, the support surface extends perpendicular to an intended stacking direction of the cell units . The alignment device is configured for aligning the cell units relative to each other with respect to at least one direction parallel to the support surface , i . e . in at least one direction perpendicular to the stacking direction . Preferably, the alignment device is configured for aligning the cell units relative to each other in a plane parallel to the support surface . The alignment device has a receiving space for receiving cell units therein . The receiving space may be delimited at one side by the support , preferably by the support surface of the support . The alignment device comprises at least one positioning pillar . The at least one positioning pillar extends in a stacking direction perpendicular to the support surface , in particular in the stacking direction along which the cell units are intended to be stacked . The at least one positioning pillar has a positioning surface for contacting an external perimeter of a cell unit positioned within the receiving space . The at least one positioning pillar is configured to block a translational and / or a rotational movement of cell units positioned within the receiving space in a plane parallel to the support surface . Thus , the at least one positioning pillar is configured such that cell units positioned within the receiving space and in particular contacting the positioning surface of the at least one positioning pillar cannot translate in a direction parallel to the support surface and / or rotate about an axis orthogonal to the support surface .

[0009] The proposed assembly device aids stacking of cell units to form a stack of cell units . Speci fically, the at least one positioning pillar allows for precise positioning of the cell units relative to each other, while keeping the footprint of the alignment device small .

[0010] The support surface may directly support the cell units during stacking . Thus , the first cell unit , i . e . the outermost cell unit of the stack, may abut the support surface . Alternatively, the support surface may indirectly support the cell units during stacking . Thus , an additional component may be located between the support surface and the cell units . That is , an additional component may be placed onto the support surface , with the cell units being stacked on top of the additional component . The additional component may be a base plate of the stack of cell units ( see below) .

[0011] The support surface may be shaped or corrugated . Preferably, the support surface is flat or planar .

[0012] In some embodiments , the alignment device or at least a subset of the components of the alignment device is mounted on the support . Thus , the support may be a carrier for the alignment device . In some embodiments , the support and the alignment device may co-operate only indirectly via the cell units .

[0013] The at least one positioning pillar may be formed integral with the support . Preferably, the at least one positioning pillar is a component provided separately from the support .

[0014] The assembly device may comprise a single positioning pillar to minimi ze part count and complexity while blocking a translational and / or a rotational movement of cell units . Alternatively, the assembly device may comprise more than one positioning pillar . In preferred embodiments , the assembly device comprises at least two positioning pillars , preferably exactly two positioning pillars . In such embodiments , preferably, the at least two positioning pillars define the receiving space therebetween . This allows for a precise positioning of the cell units relative to each other while maintaining good access to the receiving space . Preferably, the two pillars are arranged such that a line between the pillars is parallel to the first direction .

[0015] In preferred embodiments , the two pillars are arranged on opposed sides of the receiving space . Thus , the two pillars are preferably arranged such that they are located on opposed sides of a cell unit positioned in the receiving space .

[0016] In some embodiments , the assembly device further comprises a holding device for the or each pillar . In embodiments having more than one pillar, preferably each pillar is associated with its own holding device . Preferably, the holding device and the associated pillar co-operate to prevent movement of the pillar in a direction parallel to the support surface , i . e . perpendicular to the stacking direction . Preferably, the holding device and the associated pillar co-operate to prevent movement of the pillar along the first direction and / or along the second direction .

[0017] The or each positioning pillar may be fixed to the associated holding device , e . g . by a screw connection . The or each positioning pillar may be displaceable relative to the associated holding device along the stacking direction . The or each holding device may take the form of a bracket .

[0018] The at least one holding device may be separate from the support . Preferably, the at least one holding device is attached to the support , preferably such that the holding device can non-destructively be detached from the support . In an example , the or each holding member may be fixed to the support by a screw connection .

[0019] In some embodiments , the at least one positioning pillar is fixed relative to the support . Thus , movement of the at least one positioning pillar relative to the support may be blocked .

[0020] In preferred embodiments , the at least one pillar is movable along the stacking direction, i . e . perpendicular to the support surface . This allows to adj ust how far the at least one pillar protrudes above the support surface of the support , which eases stacking of the cell units ( further details see below with regards to the proposed method of assembly) .

[0021] In preferred embodiments , the or each pillar extends through the support in stacking direction, i . e . between the side having the support surface and an opposite (bottom) surface . Preferably, the or each pillar extends through a corresponding through-hole formed in the support . Preferably, the or each pillar is movable along the stacking direction through the support , speci fically through an associated through-hole formed in the support . The through-hole in the support may serve as a linear guide for the associated pillar .

[0022] In preferred embodiments , the assembly device further comprises a linear guide device for guiding movement of the at least one pillar along the stacking direction. This aids precise positioning of the pillar.

[0023] Preferably, the linear guide device is configured to prevent movement of the at least one pillar in a direction perpendicular to the stacking direction. Preferably, the liner guide device is configured to allow movement of the at least one pillar only in one direction, i.e. along the stacking direction.

[0024] In preferred embodiments, the linear guide device comprises a carrier for the at least one pillar, said carrier being movable along the stacking direction. Thus, movement of the at least one pillar along the stacking direction may be accomplished by moving the carrier along the stacking direction. The at least one pillar, preferably each pillar, may be attached to the carrier.

[0025] Preferably, the carrier is located on a side of the support opposite the support surface, i.e. preferably below the support. In this way, free space for positioning the cell units on the recording surface is preserved.

[0026] In some embodiments, there is provided a separate carrier for each pillar. Thus, each pillar may be carried by its own carrier. This allows the height of the different pillars to be adjusted independently.

[0027] In some embodiments, there is provided a common carrier for all pillars. Thus, all pillars may be carried by the same carrier . This allows for synchronous movement of the pillars .

[0028] Preferably, the carrier is guided by one or more linear guides extending along the stacking direction .

[0029] In some embodiments , the or each holding device comprises a linear guide section that co-operates with a correspondingly shaped linear guide section of the associated pillar to guide the pillar along the stacking direction . Preferably, the linear guide section of the holding device and the linear guide section of the associated pillar co-operate to prevent movement of the pillar in a plane parallel to the support surface , i . e . perpendicular to the stacking direction .

[0030] The linear guide section of the pillar may be formed in the pillar . For example , the linear guide section of the pillar may take the form of a notch or groove formed in an outer surface of the pillar .

[0031] Preferably, the linear guide section of the holding device and the linear guide section of the associated pillar cooperate with each other in the manner of tongue and groove .

[0032] The or each holding device may be separate from the support . In preferred embodiments , the or each holding device is attached to the support , preferably on the side of the support surface . As set out above, the stack of cell units may comprise a base plate in addition to the cell units. In such embodiments, the cell units may be stacked upon the base plate. Thus, preferably the base plate is configured for (directly or indirectly) stacking the cell units thereon.

[0033] In embodiments having a base plate, the base plate may be placed onto the support surface prior to stacking the cell units on top of it. Thus, the cell units may be indirectly supported by the support surface, i.e. via the base plate.

[0034] In embodiments comprising a linear guide device having one or more holding devices, the holding device or at least one of the holding devices may be configured such that a gap is formed between part of the holding device and the support surface for receiving a base plate of the stack (on which the cell units are stacked) . Thus, said gap formed between the holding device and the support surface forms a receptacle for a base plate of the stack. The holding device (s) may be configured to block or limit movement of a base plate positioned in the gap in stacking direction. The holding device (s) may be configured such that the base plate can be inserted in said gap in a direction parallel to the support surface, i.e. perpendicular to the stacking direction. This facilitates positioning of the base plate. It will be understood that the gap may be a subset of the receiving space, the receiving space being for receiving all components of the stack. In some embodiments, the support comprises one or more base plate positioning members, preferably on the side of the support surface, for positioning the base plate in a plane parallel to the support surface, i.e. perpendicular to the stacking direction. The positioning members may be stop members. The positioning members may take the form of pins that protrude from the support in stacking direction.

[0035] As used herein, the term "pillar" refers to an elongate component, i.e. a component having a length which is greater than both its width and thickness, for example twice as great.

[0036] The at least one pillar may have different shapes.

[0037] The or each pillar may take the form of a beam. The or each pillar may take the form of a bar. The or each pillar may take the form of a rod.

[0038] The or each pillar may have consistent cross-section along its length. The or each pillar may have a circular crosssection. The or each pillar may have an angular or polygonal cross-section, e.g. a triangular cross-section. The or each pillar may take the form of a prism. The or each pillar may take the form of a cylinder.

[0039] In preferred embodiments, the or each pillar is a circular beam. Thus, the or each pillar may be cylindrical. The at least one pillar may be formed from various materials . Preferred material include metals , preferably steel , and ceramics , preferably alumina .

[0040] The positioning surface of a respective pillar may extend the full length of the pillar . Alternatively, the positioning surface may extend only partially along the length of the pillar .

[0041] Preferably, the positioning surface of the or each positioning pillar has a shaped surface that is configured to engage against , preferably contact , a correspondingly shaped contact portion of the external perimeter of a cell unit positioned in the receiving space .

[0042] In some embodiments , the shaped surface of the positioning pillar is one of concave and convex, preferably convex, and the correspondingly shaped contact portion of the external perimeter is the other one of concave and convex, preferably concave .

[0043] The positioning pillar may have a circular or oval crosssection . However, concave / convex as used herein is not limited to a round-shaped cross-section . For example , the or each pillar may have a rectangular or triangular cross section and still be considered convex-shaped .

[0044] In preferred embodiments , the shaped surface of the positioning pillar is the convex, and the correspondingly shaped portion of the external perimeter is the concave . In some embodiments , the receiving space is further for receiving a top plate of the stack of cell units . In such cases , the or each positioning pillar may comprise a top plate positioning member for positioning the top plate in a plane perpendicular to the stacking direction . The top pate positioning member may comprise a protrusion from an end face of the or each positioning pillar, configured to engage in a corresponding depression or hole in the top plate . Alternatively, the top plate may comprise a protrusion configured to engage a corresponding depression or hole in the or each positioning pillar . In each case the protrusion and depression or hole cooperate to position ( i . e . , align and prevent movement of ) the top plate in a plane perpendicular to the stacking direction . The protrusion may be a pin and the depression or hole may be a blind hole . Alternatively, and particularly where the or each positioning pillar is provided with the protrusion, said protrusion may be a threaded protrusion configured to screw in to a corresponding threaded hole in the top plate or to pass through a hole in the top plate .

[0045] In some embodiments , the assembly device may further comprise a pressing device for applying a compressive force to cell units positioned within the receiving space , said compressive force acting along the stacking direction . This allows the cell units to be compressed after stacking, e . g . prior to positioning a housing around the cell units ( see below) . The pressing device may, for example , be motor- driven or hydraulically or pneumatically operated . In preferred embodiments , the top plate positioning member is configured to engage the top plate along the stacking direction, and the pressing device is configured to act on the or each positioning pillar to move the or each positioning pillar along the stacking direction to apply the compressive force to the cell units via the top plate . In such cases , the or each positioning pillar may be provided with a protrusion, said protrusion may be a threaded protrusion configured to screw in to a corresponding threaded hole in the top plate or to pass through a hole in the top plate to allow a nut to be screwed to the protrusion . This may allow the or each positioning pillar to engage the top plate along the stacking direction, to enable the positioning pillar to apply the compressive force to the stack via the top plate . In such examples , the pressing device may act between the carrier and the rack .

[0046] According to the invention, there is also provided a system comprising an assembly device as described above and at least one electrochemical cell unit . The at least one electrochemical cell unit is dimensioned to be positioned, preferably is positioned, in the receiving space defined by the alignment device of the assembly device such that the at least one positioning pillar engages against , preferably contacts , the external perimeter of the at least one cell unit . Preferably, the at least one positioning pillar, with its positioning surface , preferably with the shaped surface of its positioning surface , contacts a corresponding contact portion of the external perimeter of the at least one cell units .

[0047] Preferably, the at least one pillar and the at least one cell unit co-operate to prevent translational and / or rotational movement of the at least one cell unit parallel to the support surface , i . e . perpendicular to the stacking direction . Preferably, the at least one pillar and the at least one cell unit co-operate to prevent movement of the at least one cell unit along the first direction and along the second direction . Preferably, the at least one pillar and the at least one cell unit co-operate to prevent rotation of the at least one cell unit around the stacking direction .

[0048] Preferably, the at least one pillar and the at least one cell unit co-operate in a form- fitting manner .

[0049] In some embodiments , the positioning surface of the or each pillar has a shaped surface , said shaped surface having a negative shape of a corresponding contact portion of the external perimeter of the at least one cell unit . This allows the cell units to be held securely in place .

[0050] In preferred embodiments , the positioning surface of the or each pillar has a shaped surface , wherein said shaped surface is one of concave and convex, preferably convex, and wherein a corresponding contact portion of the external perimeter of the at least one cell unit is the other one of concave and convex, preferably concave . In preferred embodiments , the assembly device comprises at least two positioning pillars . In such embodiments , preferably the pillars engage against opposite sides of the cell unit .

[0051] The cell units may have di f ferent geometries . In some embodiments , each cell unit is generally rectangular . In embodiments comprising two positioning pillars , preferably the two pillars engage against opposite sides of the rectangular cell unit .

[0052] In some embodiments , the cell units are generally rectangular having two opposed long sides , preferably straight sides , and two opposed short sides , preferably shaped sides . In such embodiments , the or each pillar may engage against one of the short (preferably shaped) sides of the cell units . Preferably, the receiving space is configured and the at least one cell unit is positioned in the receiving space such that the long sides extend in the first direction and the short sides extend in the second direction .

[0053] As set out above , preferably, the stack of cell units further comprises a base plate on which the cell units are stacked . Thus , preferably, the system further comprises a base plate for supporting the at least one cell unit . Preferably, the base plate is positioned directly on the support surface of the support and the at least one electrochemical cell unit is positioned on the base plate . As set out above , in some embodiments , the assembly device comprises at least one base plate positioning member . In such embodiments , preferably, the base plate is positioned on the support surface such that the base plate engages against , preferably contacts , said at least one base plate positioning member .

[0054] In some embodiments of the system, the or each pillar extends through the support and the base plate in the stacking direction ( see also above with respect to the assembly device ) .

[0055] In preferred embodiments , the or each pillar extends through a respective through-hole formed in the base plate , said through-hole forming a fluid port for delivering fluid to the stack of cell units positioned thereon . Thus , the base plate may have at least one fluid port in the form of a through-hole for delivering fluid to the stack of cell units positioned thereon . In such embodiments , the pillar ( s ) may thus be guided through the base plate via through-hole ( s ) that are anyway present in the base plate for cell stack operation . As such, no additional guiding hole must be provided in the base plate . In addition, this allows to precisely position the cell units relative to the fluid port ( s ) in the base plate .

[0056] Preferably, the contact portion of the external perimeter of a respective cell unit at least partially surrounds an adj acent fluid port formed in the base plate . In preferred embodiments , the base plate has a first fluid port in the form a first through-hole and a second fluid port in the form of a second through-hole , wherein a first pillar extends through the first through-hole and a second pillar extends through the second through-hole . Preferably, the through-holes ( fluid ports ) are spatially separated along the first direction . Preferably, the cell units extend between said through-holes when positioned in the receiving space .

[0057] Preferably, each through-hole in the base plate is associated with a corresponding through-hole formed in the support ( e . g . , support plate ) , wherein the or each positioning pillar extends through both of said associated through-holes ( i . e . , a given positioning pillar extends through an associated pair of through-holes formed in the support and the base plate ) . Thus , the support (plate ) may have through-hole ( s ) at position ( s ) locally corresponding to the through-hole ( s ) in the base plate . Preferably, the base plate is positioned on the support surface such that the through-holes in the support and the through-holes in the base plate are aligned, preferably coaxially to each other .

[0058] In embodiments having at least one base plate positioning member, preferably said at least one positioning member is arranged such that the base plate , when engaging against , preferably contacting, the at least one positioning member, is positioned such that the through-hole ( s ) in the base plate are aligned with the corresponding through-hole ( s ) in the support , preferably are coaxially to each other ( likewise , where present , the top plate positioning member ) .

[0059] Preferably, the system further comprises a top plate supported by the at least one cell unit . The top plate may be positioned in the receiving space , located on top of ( in the stacking direction, disposed to an opposite end of the stack to the base plate ) the stack of cell units . The or each positioning pillar may comprise a top plate positioning member, wherein the top plate positioning member engages against the top plate . This positions the top plate in a plane perpendicular to the stacking direction .

[0060] The system may further comprise a pressing device for applying a compressive force to cell units positioned within the receiving space , said compressive force acting along the stacking direction .

[0061] Preferably, the top plate positioning member is configured to engage the top plate along the stacking direction, and the pressing device is configured to act on the or each positioning pillar to move the or each positioning pillar along the stacking direction to apply the compressive force to the cell units via the top plate .

[0062] According to the invention, there is further provided a method of manufacturing an electrochemical cell stack using an assembly device as described above . The electrochemical cell stack comprises a base plate and a plurality of cell units that are stacked upon each other in a stacking direction on top of the base plate . The method comprises , preferably in the order as stated :

[0063] - providing an assembly device as described above ;

[0064] - providing a base plate ;

[0065] - providing a plurality of cell units ;

[0066] - placing the base plate onto the support surface of the support of the assembly device , preferably such that the base plate engages against the base plate positioning members , preferably by sliding the base plate in a direction parallel to the support surface ;

[0067] - stacking the plurality of cell units on top of the base plate by sequentially, i . e . one after another, placing the cell units on top of each other in the receiving space defined by the assembly device such that the external perimeters of the cell units , preferably the contact portions of the external perimeters , engage against , preferably abut , the positioning surface , preferably the shaped surface of the at least one positioning pillar .

[0068] Optionally, one or more gaskets are positioned between cell units in the stack of cell units .

[0069] In embodiments , in which the at least one pillar is movable along the stacking direction ( e . g . by the above-described linear guide device ) , the at least one pillar, after placing a respective cell unit in the cell unit receiving space , may be moved in stacking direction by a stacking distance , preferably wherein after moving the at least one pillar by the stacking distance a further cell unit is placed in the receiving space . Thus , the at least one pillar " grows" with a height of the stack ( e . g . , the exposure of the at least one pillar above the support grows or increases as successive cell units are positioned in the stack) . This facilitates placement of the cell units in the receiving space while still ensuring precise alignment of the cell units . Preferably, the stacking distance corresponds to a height of the respective cell unit in stacking direction .

[0070] In some embodiments , the method may further comprise compressing the stack of cell units along the stacking direction . Thus , the method may comprise applying a compressive force to the stacked cell units along the stacking direction .

[0071] This may accomplished by an external pressing device . In some embodiments , the assembly device itsel f comprises a pressing device ( see above ) . In such embodiments , the method may comprise compressing the stacked cell units along the stacking direction using said pressing device .

[0072] In preferred embodiments , the method comprises providing a top plate and placing said top plate onto the stack of cell units . In such embodiments , the stack of cell units may be compressed by applying a compressive force to said top plate using the pressing device . In some embodiments , the at least one positioning pillar comprises a top plate positioning member and the method further comprises : providing a top plate of the stack, stacking the top plate on top of the ( stacked) plurality of cell units ( in other words , the top plate is stacked at an opposite end of the stack to the base plate ) , and positioning the top plate in a plane perpendicular to the stacking direction using the top plate positioning member .

[0073] In some embodiments , the top plate positioning member engages the top plate along the stacking direction, and compressing the stack comprises the pressing device acting on the at least one positioning pillar and the at least one positioning pillar applying the compressive force to the cell units via the top plate .

[0074] In some embodiments , the method further comprises providing a housing around the stack of cell units and attaching said housing to the base plate and, preferably, to the optional top plate . The housing may, for example , be attacked by welding or brazing .

[0075] Preferably, the step of providing a housing around the stack of cell units is performed after compressing the stack of cell units . The housing may be provided to maintain the compression in the stack of cell units . Thus , in preferred embodiments , the method comprises compressing the stack of cell units , preferably using a pressing device of the assembly device , and, after that , providing a housing around the compressed stack of cell units and attaching said housing to the base plate and, preferably, to the optional top plate .

[0076] After having stacked all cell units of the stack, preferably the at least one pillar and the cell units are disengaged ( from one another ) . This may be accomplished by moving the pillars along the stacking direction, preferably in an opposite direction to the stacking direction ( i . e . , anti-parallel to the direction and orientation along which the cell units are stacked by sequentially placing the cell units on top of each other ) . Alternatively or in addition, this may be accomplished by moving the pillars in a direction parallel to the support surface , i . e . perpendicular to the stacking direction . In an implementation comprising a holding device or holding bracket , after having stacked all cell units , the holding device or holding bracket may be dismantled . In embodiments comprising a compression step ( see above ) , preferably the at least one pillar and the cell units are disengaged subsequent to said compression step .

[0077] Preferably, the step of disengaging is performed subsequent to the step of attaching the housing to the base plate ( and top plate , where present ) . As a result , the alignment device may maintain alignment of the stack during said steps of compressing and / or attaching the housing .

[0078] The alignment device described above is applicable to various types of cell units . In some preferred embodiments , the cell units are fuel cell units or electrolyser cell units . Preferably, the cell units are solid oxide cell units , more preferably solid oxide fuel cell units ( SOFC ) or solid oxide electrolyser cell units ( SOEC ) .

[0079] Further embodiments are derivable from the following description and the drawings .

[0080] In the drawings :

[0081] Fig . 1 shows a perspective view of an example implementation of a system comprising an assembly device according to a first embodiment and a stack of cell units ;

[0082] Fig . 2 shows a top view of the system according to Figure 1 ;

[0083] Fig . 3A shows a perspective view of an example implementation of an assembly device according to a second embodiment with positioning pillars in a retracted configuration; and Fig . 3B shows the assembly device of Fig . 3A with positioning pillars in an extended configuration;

[0084] Fig . 4 shows a top view of a detail of the assembly device of Fig . 3A;

[0085] Fig . 5 shows the assembly device of Fig . 4 with a base plate positioned onto the support surface ; Fig . 6 shows the assembly device of Fig . 5 with a cell unit positioned onto the base plate ;

[0086] Fig . 7 shows a perspective view of a system comprising an assembly device according to Figure 3A and a stack of cell units ; and

[0087] Fig . 8 shows a perspective view of an example implementation of an assembly device according to a third embodiment .

[0088] Repeat use of reference symbols in the present speci fication and drawings is intended to represent the same or analogous features or elements .

[0089] Figures 1 and 2 schematically show an example implementation of a system 200 comprising an assembly device 10 according to a first embodiment and a stack of cell units 100 positioned in a receiving space 12 of the assembly device 10 . As will be described in detail below, the assembly device 10 is configured for assisting stacking of electrochemical cell units 102 to form the stack of cell units 100 ( also referred to as electrochemical cell stack, hereinafter referred to as " stack" ) .

[0090] In the example shown in Figure 1 , the stack 100 comprises a base plate 104 , an optional insulation plate 106 and a plurality of cell units 102 ( only schematically shown) stacked upon each other along a stacking direction 108 . Preferably, the stack 100 further comprises a top plate 110 such that the cell units 102 are sandwiched between the base plate 104 and the top plate 110 (see e.g. Figure 7) .

[0091] As set out above, the stack 100 may comprise additional components such as gaskets (e.g., positioned between cell units) , current collector plates, further insulation plates, or a top plate (not shown) .

[0092] The cell units 102 may, for example, be fuel cell units or electrolysis cell units, preferably solid oxide fuel cell units or solid oxide electrolysis cell units.

[0093] In the example, the cell units 102 are generally rectangular having two opposed long sides 112-1, 112-2 and two opposed short sides 114-1, 114-2. In other examples, the geometry of the cell units 102 may vary. For example, the cell units 102 may have a circular or a square footprint .

[0094] The assembly device 10 comprises a support 14 for the stack 100. In the example of Figure 1, the support 14 comprises a support plate 16 having a, preferably flat, support surface 18 for supporting the stack 100 during assembly thereof.

[0095] The support surface 18 extends in a first direction 20 and in a second direction 22 perpendicular to the first direction 20. Preferably, the support surface 18 extends in a plane perpendicular to the stacking direction 108. The assembly device 10 further comprises an alignment device 24 for aligning the cell units 102 relative to each other in a plane parallel to the support surface 18 ( each cell unit , stacked upon another, aligned by the at least one positioning pillar on a respective plane parallel to the support surface ) .

[0096] In the example , the alignment device 24 comprises two positioning pillars 26 (hereinafter referred to as "pillars" ) that extend along the stacking direction 108 . The pillars 26 define the receiving space 12 for the cell units 102 between them .

[0097] As set out above , the pillars 26 are arranged such that cell units 102 positioned in the receiving space 12 between them cannot translate or rotate in a plane parallel to the support surface 18 .

[0098] Speci fically, the pillars 26 are configured such that cell units 102 positioned in the receiving space 12 abut an outer surface 28 of the pillars 26 with a corresponding contact portion 116 of their external perimeter 118 such that the cell units 102 are form- f ittingly held between the two pillars 26 ( see Figure 2 ) . The outer surface 28 of a pillar 26 thus forms a positioning surface 30 of said pillar 26 for contacting a corresponding contact portion 116 of the external perimeter 118 of the cell units 102 .

[0099] In the example , the pillars 26 each take the form of a cylindrical beam . Thus , the pillars 26 have a convex shaped (outer) surface 32. In other implementations, the pillars 26 may have a different shape, e.g. a rectangular or triangular cross section.

[0100] Correspondingly, the cell units 102 have a concave shaped contact portion 116 (see Figure 2) . As will be described in detail below with respect to Figure 6, preferably the concave portions 116 align with a respective fluid port 70 provided in the base plate 104 of the stack 100 such that the aligned column of the concave portions 116 of the cell units 102 forms a fluid passage for fluid to flow along the stacking direction 108.

[0101] In the example, the concave contact portions 116 are provided at the short sides 114-1, 114-2 of the cell units 102. Thus, the pillars 26 are located at opposed short sides 114-1, 114-2 of the cell units 102. In other implementations, the contact portions 116 may be provided at different positions around the perimeter 118 of the cell units 102, e.g. at the long sides 112-1, 112-2 or at the corners. In such implementations, the pillars 26 may then be arranged to contact the long sides 112-1, 112-2 of the cell units 102 or the corners of the cell units 102.

[0102] In the example, each pillar 26 is held by a respective holding device 34 (also referred to as bracket) . The holding device 34 is mounted on the support plate 16, for example by a screw connection 36. Each holding device 34 is configured to block movement of the associated pillar 26 in a direction perpendicular to the stacking direction 108 , preferably in the first direction 20 and in the second direction 22 .

[0103] As can be seen from Figure 1 , each holding device 34 comprises a connecting section 38 that co-operates with a corresponding connecting section 40 of the associated pillar 26 , in speci fic example in the manner of tongue and groove . Speci fically, each pillar 26 has a groove 42 formed in its outer surface 28 , in which a corresponding proj ection 44 of the holding device 34 engages .

[0104] The connecting sections 38 , 40 may form linear guide sections 46 , 48 for guiding movement of the pillars along the stacking direction 108 ( further details below with respect to the second embodiment ) .

[0105] The connecting sections 38 , 40 may also be configured such that movement of the associated pillar 26 along the stacking direction 108 is blocked or at least can be blocked i f desired . For example , the proj ections 44 may be part of a screw that can be tightened or loosened so as to block or allow movement of the associated pillar 26 along the stacking direction 108 .

[0106] Referring to Figure 1 , it can be seen that each holding device 34 is configured such that a gap 50 is formed between an overhang section 52 of the holding device 34 and the support surface 18 for receiving the base plate 104 of the stack 100 ( on which the cell units 102 are stacked) .

[0107] The holding devices 34 may be fixed to the support plate 118 after placing the base plate 104 onto the support surface 18 . Alternatively, the base plate 104 may be inserted in said gap 50 by moving the base plate 104 parallel to the support surface 18 in the second direction 22 .

[0108] In order to define a position of the base plate 104 relative to the support plate 16 , the support plate 16 may further comprise optional base plate positioning members 54 ( see Figure 2 ) . In the example , the positioning members 54 take the form of pins 56 that protrude from the support plate 16 in stacking direction 108 . As can be seen from Figure 2 , the base plate 104 preferably abuts the positioning members 54 in an assembled state .

[0109] Figures 3A and 3B show an example implementation of an assembly device 10 according to a second embodiment . To avoid repetition, aspects of Figures 3A and 3B that are generally the same as shown in Figures 1 and 2 will not be described again, except where relevant to explain the particular features of Figures 3A and 3B . Like reference numerals are used to describe like features

[0110] In the example of Figure 3A, the support plate 16 is held by a rack 58 , speci fically by a cross beam 60 of said rack 58 . However, it will be understood that the speci fic configuration of the rack 58 shown is only exemplary and may take on various implementations .

[0111] In the assembly device 10 according to the second embodiment , the pillars 26 are movable along the stacking direction 108 . This allows a position of the pillars 26 along the stacking direction 108 to be adj usted . Figure 3A show the pillars 26 in a retracted configuration and Figure 3B show the pillars 26 in an extended configuration .

[0112] Referring to Figure 3B, it can be seen that the pillars 26 ( at least in an extended configuration) extend through respective through-holes 62 formed in the support plate 16 ( see also Figure 4 ) . As will be described in detail below, the pillars 26 and the through-holes 62 formed in the support plate 16 are arranged at a distance corresponding to a distance of corresponding through-holes 64 in the base plate 104 ( see Figure 5 )

[0113] The assembly device 10 further comprises a linear guide device 65 for guiding movement of the pillars 26 along the stacking direction . Speci fically, the pillars 26 are supported by ( and slidably attached to ) a carrier 66 . The carrier 66 is located to a side of the support plate 16 that is opposite the support surface 18 . The carrier 66 is movable along the stacking direction 108 . In the example , the carrier 66 is guided along two linear guides 68 , e . g . in the form of rods , that are connected to the support plate 16 . The carrier 66 may be manually movable along the stacking direction 108 . Alternatively, the linear guide device 65 may comprise a drive unit for driving a movement of the carrier 66 ( and thus the pillars 26 ) along the stacking direction 108 .

[0114] In the example , the assembly device 10 does not comprise a holding device 34 as described in connection with Figures 1 and 2 . However, in other implementations not shown, the assembly device 10 may comprise such a holding device 34 for each pillar 26 . The holding devices 34 may then each comprise a linear guide section 46 that co-operates with a corresponding linear guide section 48 of the associated pillar 26 ( see above ) .

[0115] A method of manufacturing an electrochemical cell stack 100 using an assembly device 10 according to Figures 3A and 3B will be described below with reference to Figures 4 to 6 .

[0116] In a first step, an assembly device 10 according to Figure 3A is provided . In an initial configuration, the pillars 26 may be in the fully retracted configuration as shown in Figure 3A. Alternatively, the pillars 26 may already be in an extended configuration, in which they protrude slightly over the support surface 18 in stacking direction 108 .

[0117] In a further step, the base plate 104 is provided . As set out above , the base plate 104 comprises two through-holes 64 forming fluid ports 70 for supplying fluid to the cell units 102 in the subsequently-manufactured stack 100 . For example , the through-holes 64 may serve as access point to supply fluid from an exterior of the stack 100 to a fluid volume defined by a housing (not shown) surrounding the stack 100 . The through-holes 64 are provided at the same distance as the pillars 26 .

[0118] As shown in Figure 5 , the base plate 104 is placed onto the support surface 18 such that the through-holes 64 in the base plate 104 are aligned with the pillars 26 and, i f the pillars are already in a slightly extended configuration, the pillars 26 extend through the through-holes 64 in stacking direction 108 .

[0119] After positioning the base plate 104 on the support surface 18 , the pillars 26 may be moved in stacking direction 108 such that they slightly protrude over a top surface of the base plate 104 . Alternatively, the pillars 26 may already have been in such an extended configuration in their initial configuration .

[0120] In a further step, the cell units 102 are stacked upon one another along the stacking direction 108 . One or more gaskets may be positioned between cell units during stacking of said cell units . The pillars may be sequentially extended after stacking of each, or a number of , cell unit ( s ) .

[0121] Figure 6 shows an example configuration, in which a cell unit 102 ( only schematically shown) is placed in the receiving space 12 between the two pillars 26 and directly onto the base plate 104 . However, it will be understood that prior to stacking the cell units 102 onto the base plate 104 , further components of the stack 100 ( e . g . one or more gaskets , an insulation plate and / or a current collector plate ) may be placed onto the base plate 104 such that the cell units 102 are in fact placed onto said components and the base plate 104 only indirectly supports the cell units 102 .

[0122] As can be seen from Figure 6 , when positioned in the receiving space 12 , the concave contact portions 116 of the external perimeter 118 of the cell unit 102 abut the correspondingly shaped positioning surfaces 30 ( convex shaped surfaces 32 ) of the pillars 26 such that the cell unit 102 is form- f ittingly held between the two pillars 26 . In this configuration, translational and rotational movement of the cell unit 102 parallel to the support surface 18 is blocked .

[0123] As set out above , in this configuration, the cell units 102 partially surround the fluid ports 70 ( through-holes 64 ) formed in the base plate 104 with their contact portions 116 . In the assembled stack 100 , the aligned column of cell units 102 , speci fically the contact portions 116 , forms a fluid passage for fluid, for example fuel or oxidant , to flow along the stacking direction 108 .

[0124] After placing a respective cell unit 102 or a certain number of cell units 102 , the pillars 26 may be moved in stacking direction 108 by a stacking distance such that the pillars 26 "grow" with growing cell stack 100. The stacking distance may correspond to a cell height of the cell units 102 along the stacking direction 108.

[0125] Figure 7 schematically shows a configuration after completion of the stacking process. As mentioned above, in the example, the stack 100 comprises a top plate 110 placed onto the stacked cell units 102.

[0126] In a further step, the stack 100 may be removed from the assembly device 10. For this, the pillars 26 may be moved to the retracted configuration (i.e. in a direction opposite to the stacking direction 108, in other words the pillars may be moved anti-parallel to the stacking direction) . In such a way, the pillars are disengaged from the cell units (i.e., the pillars and the cell units are disengaged from one another) .

[0127] In some embodiments, prior to removing the stack 100 from the assembly device 10, the stack 100 may be compressed along the stacking direction 108 (i.e., to ensure electrical contact between the cell units 102, more specifically compressed along an axis parallel to the stacking direction) . The pillars 26 may be retracted prior to compressing the stack 100. Alternatively, the pillars may be retracted during the compression step.

[0128] In some embodiments, a housing (not shown) is provided around said compressed stack 100 and attached to either or both of the base plate 104 and the top plate 110. The housing may, for example , be welded to the base plate 104 and the top plate 110 .

[0129] Figure 8 shows an example implementation of an assembly device 10 according to a third embodiment . The assembly device 10 of this embodiment is identical to the assembly device 10 according to Figures 3A and 3B except that it additionally comprises a pressing device 72 for compressing the cell stack 100 along the stacking direction 108 (more speci fically compressing the stack along an axis parallel to the stacking direction) .

[0130] In the example , the pressing device 72 is mounted on a cross beam 74 of the rack 58 in a position above ( facing) the support plate 16 .

[0131] The pressing device 72 is configured to apply a compressive force along the stacking direction 108 (more speci fically the compressive force is applied along an axis parallel to the stacking direction) . In the speci fic example , the pressing device 72 comprises a pressure distribution plate 76 that is moveable along the stacking direction, e . g . via a spindle drive 78 .

[0132] In such embodiment , the optional step of compressing the stack 100 described above may be accomplished by applying a compressive force to the top plate 110 ( i f present ) using said pressing device 72 . In embodiments comprising a compression step ( see above ) , the pillars 26 and the cell units 102 may be disengaged subsequent to said compression step . Preferably, the step of disengaging is also performed subsequent to the step of attaching the housing to the base plate ( and top plate , where present ) . As a result , the alignment device 24 may maintain alignment of the stack 100 during said steps of compressing and / or attaching the housing .

[0133] In a further example , the receiving space 12 receives a top plate 110 of the stack 100 of cell units . In such cases , the positioning pillars 26 may include a top plate positioning member (not shown) which positions the top plate 110 in a plane perpendicular to the stacking direction 108 . The top plate positioning member may comprise a protrusion from an end face of the or each positioning pillar 26 , configured to engage in a corresponding depression or hole in the top plate 110 . Alternatively, the top plate 110 may comprise a protrusion configured to engage a corresponding depression or hole in the or each positioning pillar 26 . In each case the protrusion and depression or hole cooperate to position ( i . e . , align and prevent movement of ) the top plate 110 in a plane perpendicular to the stacking direction 108 . The protrusion may be a pin and the depression or hole may be a blind hole . Alternatively, and particularly where the or each positioning pillar 26 is provided with the protrusion, said protrusion may be a threaded protrusion configured to screw in to a corresponding threaded hole in the top plate 110 or to pass through a hole in the top plate 110 . Further, the top plate positioning member may be configured to engage the top plate 110 along the stacking direction 108 , and in such cases the pressing device 72 is configured to act on the or each positioning pillar 26 to move the or each positioning pillar 26 along the stacking direction 108 to apply the compressive force to the cell units 102 via the top plate 110 . In such cases , the or each positioning pillar 26 may be provided with a protrusion, said protrusion may be a threaded protrusion configured to screw in to a corresponding threaded hole in the top plate 110 or to pass through a hole in the top plate 110 to allow a nut to be screwed to the protrusion . This may allow the or each positioning pillar 26 to engage the top plate 110 along the stacking direction 108 , to enable the positioning pillar 26 to apply the compressive force to the stack 100 via the top plate 110 . In such examples , the pressing device 72 may act between the carrier 66 and the rack 58 to apply a pull force to the pillars 26 , transmitted to the top plate 110 , which applies a corresponding compression force through the stack 100 .

Claims

Claims1. Assembly device (10) for assisting stacking of electrochemical cell units (102) to form a stack (100) of cell units (102) , the assembly device (10) comprising:- a support (14) , preferably support plate (16) , having a support surface (18) for supporting the cell units (102) during stacking,- an alignment device (24) for aligning the cell units (102) relative to each other parallel to the support surface (18) , wherein : the alignment device (24) defines a receiving space (12) for receiving cell units (102) therein, the alignment device (24) comprises at least one positioning pillar (26) that extends in a stacking direction (108) perpendicular to the support surface (18) , the at least one positioning pillar (26) has a positioning surface (30) for contacting an external perimeter (118) of cell units (102) positioned within the receiving space (12) , the at least one positioning pillar (26) is configured to block a translational and / or a rotational movement of cell units (102) positioned within the receiving space (12) in a plane parallel to the support surface (18) .

2. The assembly device (10) according to claim 1, comprising at least two positioning pillars (26) , said at least two positioning pillars (26) defining the receiving space (12) between them.

3. The assembly device (10) according to the preceding claim, wherein the two positioning pillars (26) are arranged on opposed sides of the receiving space (12) .

4. The assembly device (10) according to any one of the preceding claims, wherein the or each positioning pillar (26) is movable along the stacking direction (108) .

5. The assembly device (10) according to any one of the preceding claims, wherein the or each positioning pillar (26) extends through the support (14) along the stacking direction (108) , preferably through a respective through-hole (62) formed in the support (14) .

6. The assembly device (10) according to claim 4 or 5, further comprising a linear guide device (65) for guiding movement of the at least one positioning pillar (26) along the stacking direction (108) .

7. The assembly device (10) according to the preceding claim, wherein the linear guide device (65) is configured to prevent movement of the at least one positioning pillar (26) in a direction perpendicular to the stacking direction (108) .

8. The assembly device (10) according to any one of claims 6 or 7, wherein the linear guide device (65) comprises a carrier (66) , said carrier (66) carrying the at least one positioning pillar (26) , preferably all positioning pillars (26) , said carrier (66) being located on a side of the support (14) opposite the support surface (18) , said carrier (66) being movable along the stacking direction (108) .

9. The assembly device (10) according to the preceding claim, said carrier (66) being by guided by one or more linear guides (68) extending along the stacking direction ( 108 ) .

10. The assembly device (10) according to any one of the preceding claims, further comprising a holding device (34) for the or each positioning pillar (26) , wherein the holding device (34) and the associated positioning pillar (26) co-operate to prevent movement of the positioning pillar (26) in a direction parallel to the support surface (18) .

11. The assembly device (10) according to the preceding claim, wherein each holding device (34) has a linear guide section (48) , said linear guide section (48) cooperating with a linear guide section (46) of the associated positioning pillar (26) , preferably in the manner of tongue and groove.

12. The assembly device (10) according to the preceding claim, wherein the holding device (34) is attached tothe support (14) , preferably on the side of the support surface (18) .

13. The assembly device (10) according to any one of claims 10 to 12, wherein the holding device (34) is configured such that a gap (50) is formed between a part of the holding device and the support surface (18) , said gap (52) forming a receptacle for a base plate (104) of the stack (100) .

14. The assembly device (10) according to the preceding claim, wherein the support (14) comprises one or more base plate positioning members (54) for positioning the base plate (104) in a plane perpendicular to the stacking direction (108) .

15. The assembly device (10) according to any one of the preceding claims, wherein the or each positioning pillar (26) is a circular beam.

16. The assembly device (10) according to any one of the preceding claims, wherein the or each positioning pillar (26) is formed from metal or ceramic.

17. The assembly device (10) according to any one of the preceding claims, wherein the positioning surface (30) of the or each positioning pillar (26) has a shaped surface (32) which is configured to contact a correspondingly shaped contact portion (116) of the external perimeter (118) of a cell unit (102) positioned in the receiving space (12) .

18. The assembly device (10) according to the preceding claim, wherein the shaped surface (32) of the or each positioning pillar (26) is one of concave and convex, and the correspondingly shaped contact portion (116) of the external perimeter (118) is the other one of concave and convex.

19. The assembly device (10) according to any one of the preceding claims, wherein the receiving space (12) is further for receiving a top plate (110) of the stack of cell units (102) , and wherein the or each positioning pillar (26) comprises a top plate positioning member for positioning the top plate (110) in a plane perpendicular to the stacking direction (108) .

20. The assembly device (10) according to any one of the preceding claims, further comprising a pressing device (72) for applying a compressive force to cell units (102) positioned within the receiving space (12) , said compressive force acting along the stacking direction (108) .

21. The assembly device (10) according to the preceding claim when dependent on claim 19, wherein the top plate positioning member is configured to engage the top plate (110) along the stacking direction (108) , and the pressing device is configured to act on the or each positioning pillar (26) to move the or each positioning pillar (26) along the stacking direction(108) to apply the compressive force to the cell units(102) via the top plate (110) .

22. System (200) comprising an assembly device (10) according to any one of the preceding claims and at least one electrochemical cell unit (102) , said at least one electrochemical cell unit (102) being dimensioned to be positioned, preferably being positioned, in the receiving space (12) defined by the assembly device (10) such that the at least one positioning pillar (26) , with its positioning surface (30) , engages against the external perimeter (118) of the at least one cell unit (102) .

23. System (200) according to the preceding claim, wherein the at least one positioning pillar (26) and the at least one cell unit (102) co-operate to prevent movement of the at least one cell unit (102) perpendicular to the stacking direction (108) .

24. System (200) according to claim 22 or 23, wherein the positioning surface (30) of the or each positioning pillar (26) has a shaped surface (32) , said shaped surface (32) having a negative shape of a corresponding contact portion (116) of the external perimeter (118) of the at least one cell unit (102) .

25. System (200) according to any of claims 22 to 24, whereinthe positioning surface (30) of the or each positioning pillar (26) has a shaped surface (32) , said shaped surface (32) being one of concave and convex, a corresponding contact portion (116) of the external perimeter (118) of the at least one cell unit (102) is the other one of concave and convex.

26. System (200) according to any of claims 22 to 25, wherein the assembly device (10) comprises two positioning pillars (26) .

27. System (200) according to the preceding claim, wherein each cell unit (102) is generally rectangular, and wherein the two pillars (26) engage against opposite sides (114-1, 114-2) of the cell unit (102) .

28. System (200) according to the preceding claim, wherein the rectangular cell unit (102) has two opposed long sides (112-1, 112-2) , preferably straight sides, and two opposed short sides (114-1, 114-2) , preferably shaped sides, wherein each positioning pillar (26) engages against one of the short sides (114-1, 114-2) of the cell unit (102) .

29. System (200) according to any of claims 22 to 28, further comprising a base plate (104) for supporting the at least one cell unit (102) , said base plate (104) being positioned on the support surface (18) of the support ( 14 ) .

30. System (200) according to the preceding claim, wherein the assembly device (10) comprises at least one base plate positioning member (54) , wherein the base plate (104) engages against said at least one base plate positioning member (54) .

31. System (200) according to claim 29 or 30, wherein the or each positioning pillar (26) extends through the support (14) and the base plate (104) in the stacking direction .

32. System (200) according to the preceding claim, wherein the or each positioning pillar (26) extends through a respective through-hole (64) formed in the base plate (104) , said through-hole (64) forming a fluid port (70) for delivering fluid to the cell units (102) .

33. System (200) according to the preceding claim, wherein each through-hole (64) in the base plate (104) is associated with a corresponding through-hole (62) formed in the support (14) , wherein the or each positioning pillar (26) extends through both of said associated through-holes (62, 64) .

34. System (200) according to any one of claims 22 to 33, further comprising a top plate (110) supported by the at least one cell unit (102) , and wherein the or each positioning pillar (26) comprises a top plate positioning member, wherein the top plate positioning member engages against the top plate (110) .

35. Method of manufacturing an electrochemical cell stack(100) , comprising a base plate (104) and a plurality of cell units (102) that are stacked upon each other in a stacking direction (108) on top of the base plate (104) , using an assembly device (10) according to any of claims 1 to 21, the method comprising- providing an assembly device (10) according to any of claims 1 to 21;- providing a base plate (104) ;- providing a plurality of cell units (102) ;- placing the base plate (104) onto the support surface (18) of the support (14) of the assembly device (10) ;- stacking the plurality of cell units (102) on top of the base plate (104) by sequentially placing the cell units (102) on top of each other in the receiving space (12) such that the external perimeters (118) of the cell units (102) abut the positioning surface (30) of the at least one positioning pillar (26) .

36. The method according to the preceding claim, wherein the at least one positioning pillar (26) is movable along the stacking direction (108) , wherein after placing a respective cell unit (102) in the receiving space (12) , the at least one positioning pillar (26) is moved in stacking direction by a stacking distance.

37. The method according to claim 35 or 36, wherein the at least one positioning pillar (26) comprises a topplate positioning member and wherein the method further comprises:- providing a top plate (110) of the stack (100) ,- stacking the top plate (110) on top of the plurality of cell units (102) , and- positioning the top plate (110) in a plane perpendicular to the stacking direction (108) using the top plate positioning member.

38. The method according to any one of claims 35 to 37, wherein the assembly device (10) comprises a pressing device (72) , the method comprising compressing the stack (100) of cell units (102) using said pressing device ( 72 ) .

39. The method according to the preceding claim when dependent on claim 37, wherein the top plate positioning member engages the top plate (110) along the stacking direction (108) , and compressing the stack (100) comprises the pressing device acting on the at least one positioning pillar (26) and the at least one positioning pillar (26) applying the compressive force to the cell units (102) via the top plate (110) .

40. The method according to any one of claims 38 and 39, further comprising providing a housing around the compressed stack (100) of cell units (102) and attaching said housing to the base plate (104) , for example by welding.

41. The method according to any one of claims 35 to 40, further comprising: disengaging the at least one positioning pillar (26) from the cell units (102) , preferably by moving the at least one positioning pillar (26) in an opposite direction to the stacking direction ( 108 ) .

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