Method for connecting a first bipolar plate layer and a second bipolar plate layer in a bonded manner, bipolar plate for an electrochemical unit of an electrochemical device, and electrochemical device
Patent Information
- Application Number
- EP2023748005
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-08-01
- Filing Date
- 2023-07-17
- Publication Date
- 2025-06-11
AI Technical Summary
The existing methods for connecting bipolar plate layers in electrochemical devices require significant space for clamping tools, which compromises the fluid mechanical properties and support functions of the bipolar plates, leading to suboptimal performance.
The method involves integrating support structures into the bipolar plates that also serve as clamping tool supports, allowing for precise alignment and connection with minimal gap, using structures like cup-shaped or web-shaped designs to optimize space usage and maintain fluidic properties.
This approach enables reliable and process-safe connection of bipolar plate layers with minimal gap, preserving the fluid mechanical properties and support functions, thus enhancing the overall performance of electrochemical devices.
Smart Images
Figure 1.1
Abstract
Description
[0001] Method for the materially bonding of a first bipolar plate layer and a second bipolar plate layer, bipolar plate for an electrochemical unit of an electrochemical device and electrochemical device
[0002] The present invention relates to a method for the materially bonding of a first bipolar plate layer and a second bipolar plate layer of a bipolar plate for an electrochemical unit of an electrochemical device comprising a plurality of electrochemical units which follow one another along a stacking direction, the method comprising the following:
[0003] Bringing the first bipolar plate layer and the second bipolar plate layer into contact at one or more contact areas of the bipolar plate layers;
[0004] Applying a clamping force to the first bipolar plate layer and the second bipolar plate layer by means of one or more clamping tools; and materially connecting the first bipolar plate layer and the second bipolar plate layer along a connecting seam.
[0005] The connecting seam is preferably created by welding, in particular by laser welding.
[0006] To create such a connecting seam, a specially adapted and high-precision welding tool is required, which includes clamping tools for applying a clamping force to the first bipolar plate layer and the second bipolar plate layer, so that the first bipolar plate layer and the second bipolar plate layer are spaced apart from each other in the contact areas where the bipolar plate layers are to be connected by only a virtually "technical zero gap" with a height (along the stacking direction of the electrochemical device) of less than 0.03 mm. For this purpose, clamping tools, designed as clamping bars, for example, must be placed on flat areas of the bipolar plate layers on both sides of the connecting seam to be created to achieve a sufficient clamping effect.
[0007] The connecting seams and the flat areas of the bipolar plate layers that must be kept free on both sides of the connecting seams require a considerable proportion of the total space available on the bipolar plate, which is a disadvantage in terms of development and design, since a lot of space is also required for the arrangement of elements that are introduced into the bipolar plate layers by forming, which direct the flow of media to be supplied to the electrochemical device (anode gas, cathode gas, coolant) and / or support components of electrochemical units that are adjacent to the bipolar plate, for example gas diffusion layers or components of sealing arrangements of the electrochemical units.
[0008] Excessively large flat areas of the bipolar plate layers to be joined, which must be kept free for the arrangement of clamping tools, negatively influence the fluid mechanical properties of the bipolar plate.
[0009] The present invention is based on the object of creating a method for the materially bonding of a first bipolar plate layer and a second bipolar plate layer of a bipolar plate for an electrochemical unit of an electrochemical device of the type mentioned at the outset, which method makes it possible to reliably bond the two bipolar plate layers to one another without impairing the fluidic properties of the bipolar plate or impairing the supporting function of the bipolar plate for components of the electrochemical units of the electrochemical device.This object is achieved according to the invention in a method for the materially bonding of a first bipolar plate layer and a second bipolar plate layer of a bipolar plate for an electrochemical unit of an electrochemical device having the features of the preamble of claim 1 in that at least one clamping tool is supported on a support surface of at least one support structure of at least one of the bipolar plate layers, wherein the support surface of the support structure is offset from the respective other bipolar plate layer in the contact region along the stacking direction relative to the surface of the bipolar plate layer on which the support structure is formed.
[0010] The solution according to the invention is based on the concept of using structures which are already required for directing the media flows and / or for supporting components of the electrochemical units and which are preferably formed in at least one of the bipolar plate layers, in addition to supporting at least one clamping tool during the creation of a connecting seam between the first bipolar plate layer and the second bipolar plate layer of the bipolar plate.
[0011] The at least one support structure is designed such that it has a support surface for supporting a clamping tool during the creation of the connecting seam, wherein this support surface can preferably also serve to support a component of an electrochemical unit adjacent to the support structure, for example a gas diffusion layer or a component of a sealing arrangement of an electrochemical unit.
[0012] The height of the support structure, i.e. the distance of the support surface from the surface of the bipolar plate layer on which the support structure is formed, in a contact area in which this bipolar plate layer rests against the other bipolar plate layer - preferably flatly - is matched to the adjacent component of an electrochemical unit to be supported, for example a membrane electrode assembly.
[0013] The shape, especially the outer contour, of the support structure is optimized for the production process of the connecting seam.
[0014] This saves space on the bipolar plate, which would otherwise have to be kept free for the arrangement of clamping tools during the creation of the connecting seams.
[0015] The at least one support structure can, for example, have the shape of a bowl or "dimple" with a circular, oval or free-form edge.
[0016] The edge of a support structure is a line at which the support structure transitions into a flat area aligned parallel to the stacking direction.
[0017] Such a support structure can be arranged on an anode-side bipolar plate layer or on a cathode-side bipolar plate layer.
[0018] Preferably, such a support structure is formed by a forming process on one of the bipolar plate layers, for example by a stamping process or a deep-drawing process.
[0019] The largest dimension of such a support structure along a direction perpendicular to the stacking direction is preferably approximately 3 mm to approximately 7 mm, for example approximately 5 mm. Such a support structure can be formed on one side of the anode-side bipolar plate layer or on the cathode-side bipolar plate layer, wherein the respective other bipolar plate layer has a flat free surface in the corresponding region, against which a clamping tool can rest during the creation of a connecting seam.
[0020] Alternatively, it can also be provided that a preferably cup-shaped support structure is also formed on the respective other bipolar plate layer, which—viewed along the stacking direction of the electrochemical device—is substantially congruent with the support structure on the first bipolar plate layer or is only slightly offset from the support structure on the first bipolar plate layer. Due to the deformation of the support structures arranged in the same position on the two bipolar plate layers to be joined together, a force equilibrium is achieved when these support structures are pressed together by means of the clamping tools, which are brought into contact with the support structures. According to this equilibrium, the forces exerted by the bipolar plate layers on each other and on the clamping tools are equal to one another ("action equals reaction").
[0021] Alternatively or additionally, it can also be provided that at least one web structure on at least one of the bipolar plate layers to be connected to one another is web-shaped and runs essentially parallel to the connecting seam.
[0022] A support surface formed on such a web-shaped support structure preferably has an extension perpendicular to the stacking direction of less than 3 mm, particularly preferably less than 1.5 mm.
[0023] Such a web-shaped support structure can be arranged on one side only on an anode-side bipolar plate layer or only on a cathode-side bipolar plate layer, wherein the other bipolar plate layer in this area has a flat free surface to which a clamping tool can be applied during the creation of the connecting seam.
[0024] Alternatively, the respective other bipolar plate layer may also be provided with a second web-shaped support structure, which—with respect to the contact plane of the two bipolar plate layers—is symmetrical to the first web-shaped support structure or deviates only slightly from its shape. Preferably, the position of the second web-shaped support structure—as viewed along the stacking direction—is substantially congruent with the position of the first web-shaped support structure or is only slightly offset from the position of the first web-shaped support structure.
[0025] The edges of the support structures, where the support structures transition into a flat area of the respective bipolar plate layer, preferably meet again on both opposite sides of the web-shaped support structure so that the two bipolar plate layers rest against each other "together." This results in a force equilibrium when the web-shaped support structures are pressed together using the clamping tools during the creation of the connecting seam, in which the forces exerted by the bipolar plate layers on each other and on the clamping tools are equal ("action equals reaction").
[0026] In a further embodiment of the invention, it is provided that one of the bipolar plate layers to be connected to one another has a plurality of web-shaped support structures which run transversely to the connecting seam and end at a short distance from the connecting seam.
[0027] In this case, the respective other bipolar plate layer can have a flat free surface in the region of these tapered web-shaped support structures, against which a clamping tool can be applied during the production of the connecting seam. Alternatively, it can also be provided that the respective other bipolar plate layer has one or more web-shaped support structures running essentially parallel to the connecting seam in the region in which the first bipolar plate layer has web-shaped support structures running transversely to the connecting seam.
[0028] The edges of the support structures meet in the area between the web-shaped support structures of the first bipolar plate layer, which run transversely to the connecting seam, and on the side of the web-shaped support structures of the second bipolar plate layer facing away from the connecting seam, such that the two bipolar plate layers abut one another "together" at these points. This creates a force equilibrium during the compression of the support structures during the creation of the connecting seam, in which the forces exerted by the bipolar plate layers on each other and on the clamping tools are equal ("action equals reaction").
[0029] The edge of a support structure, at which the support structure merges into a flat region of the bipolar plate layer, preferably has a distance from the connecting seam which is less than 1 mm, in particular less than 0.5 mm, particularly preferably less than 0.1 mm.
[0030] On a side of the support structure facing away from the connecting seam, the edge of the support structure formed on one of the bipolar plate layers preferably meets the edge of another support structure formed on the other bipolar plate layer, in order to ensure that the bipolar plate layers abut one another "together" at this section of their edges, in order to achieve a sufficient supporting effect through the resulting equilibrium of forces ("action equals reaction"). These sections of the edges of the support structures facing away from the connecting seam are preferably spaced from the connecting seam at a distance of greater than 1 mm and / or less than 5 mm.
[0031] The at least one support structure of the bipolar plate produced according to the invention allows, on the one hand, a clamping tool to be arranged very close to the connecting seam during the creation of the connecting seam. On the other hand, the at least one support structure can serve to support an adjacent component of an electrochemical unit, for example, a gas diffusion layer or a component of a sealing arrangement of an electrochemical unit.
[0032] The at least one support structure is designed as a stable element to absorb the clamping force of the clamping tools during the creation of the connecting seam and is placed as close as possible to the connecting seam.
[0033] The at least one support structure, which is formed on one of the bipolar plate layers, is preferably supported both on its side facing the connecting seam and on its side facing away from the connecting seam on a support structure, which is formed on the other bipolar plate layer.
[0034] By exerting a clamping force by means of clamping tools on the support structures of the bipolar plate, it is achieved that the bipolar plate layers to be connected to one another are only spaced from one another by a small gap in the contact area in which they lie against one another - preferably flat - and are to be connected to one another by the connecting seam, which gap has a height (along the stacking direction) that is less than 0.03 mm.The supporting effect of the support structure ensures during operation of the electrochemical device that the component of an electrochemical unit supported on the support structure, for example a gas diffusion layer, a sub-gasket or another element of a sealing arrangement of an electrochemical unit, does not penetrate into the space between a medium distribution area and a medium passage opening of the bipolar plate and thereby closes media outlets of sealing beads or a medium distribution area.
[0035] In a preferred embodiment of the invention, it is provided that at least one of the clamping tools is supported on several support surfaces of several different support structures and on several contact areas of the bipolar plate layers which lie between the support structures.
[0036] Preferably, it is provided that at least one first clamping tool is supported on at least one first support structure which is formed on the first bipolar plate layer, and at least one second clamping tool is supported on at least one second support structure which is formed on the second bipolar plate layer.
[0037] The first support structure has a first edge at which the first support structure transitions into a planar region of the first bipolar plate layer, and the second support structure has a second edge at which the second support structure transitions into a planar region of the second bipolar plate layer.
[0038] In a projection onto a plane oriented perpendicular to the stacking direction, the first edge and the second edge are preferably substantially congruent with one another or preferably differ from one another by a distance of at most 0.5 mm. This distance is preferably measured perpendicular to the longitudinal direction of the first edge or perpendicular to the longitudinal direction of the second edge. In a particular embodiment of the invention, it is provided that at least one support structure is formed at a location on one of the bipolar plate layers opposite a flat region of the respective other bipolar plate layer that is not provided with a support structure.
[0039] The support surface of at least one support structure preferably has a smallest extension (a) perpendicular to the stacking direction, which is at least 0.1 mm, in particular at least 0.5 mm.
[0040] Furthermore, the support surface of at least one support structure preferably has a smallest extension (a) perpendicular to the stacking direction, which is at most 3 mm, in particular at most 1.5 mm.
[0041] Alternatively or additionally, it can be provided that the support surface of at least one support structure has a greatest extent perpendicular to the stacking direction which is greater than 3 mm, in particular greater than 5 mm.
[0042] In a preferred embodiment of the invention, it is provided that at least one support structure has an edge at which the support structure merges into a flat region of the bipolar plate layer on which the support structure is formed, wherein the smallest distance (d) of the edge of the support structure from the center line of the connecting seam is at most 0.8 mm, in particular at most 0.5 mm, particularly preferably at most 0.3 mm.
[0043] The smallest distance (d) of the edge of the support structure from the center line of the connecting seam is preferably taken perpendicular to the center line of the connecting seam. Furthermore, it is preferably provided that at least one support structure has an edge at which the support structure transitions into a planar region of the bipolar plate layer on which the support structure is formed, wherein the greatest distance (D) of the edge of the support structure from the center line of the connecting seam is at most 5 mm, in particular at most 3 mm, particularly preferably at most 2 mm.
[0044] The greatest distance (D) of the edge of the support structure is preferably taken perpendicular to the center line of the connecting seam.
[0045] At least one of the support structures may be cup-shaped.
[0046] Furthermore, it can be provided that at least one support structure is circular or oval in a plan view along the stacking direction.
[0047] Alternatively or additionally, it can be provided that at least one support structure is web-shaped.
[0048] A web-shaped support structure can run essentially parallel to the connecting seam, at least in sections.
[0049] Alternatively or additionally, it can be provided that several web-shaped support structures run transversely to the connecting seam and end at a distance (d') from the center line of the connecting seam of less than 0.8 mm, in particular of less than 0.5 mm, particularly preferably of less than 0.3 mm.
[0050] The distance (d') from the center line of the connecting seam is preferably taken perpendicular to the center line of the connecting seam. The present invention further relates to a bipolar plate for an electrochemical unit of an electrochemical device comprising a plurality of electrochemical units arranged one after the other along a stacking direction, wherein the bipolar plate comprises a first bipolar plate layer and a second bipolar plate layer, which are integrally bonded to one another in a contact region of the bipolar plate layers along a connecting seam.
[0051] The present invention is based on the further object of creating a bipolar plate of the above-mentioned type in which the first bipolar plate layer and the second bipolar plate layer can be reliably connected to one another without the fluid mechanical properties of the bipolar plate being impaired and without the function of supporting components of electrochemical units adjacent to the bipolar plate being impaired.
[0052] This object is achieved by a bipolar plate according to claim 15, wherein at least one support structure is formed on the first bipolar plate layer and / or on the second bipolar plate layer, wherein a support surface of the at least one support structure is offset from the surface of the bipolar plate layer on which the support structure is formed in the contact region along the stacking direction from the respective other bipolar plate layer, and wherein the at least one support structure has an edge at which the support structure merges into a planar region of the bipolar plate layer on which the support structure is formed, wherein the smallest distance (d, d') of the edge of the support structure from the center line of the connecting seam is at most 0.8 mm, in particular at most 0.5 mm, particularly preferably at most 0.3 mm.The smallest distance (d, d') of the edge of the support structure from the center line of the connecting seam is preferably taken perpendicular to the center line of the connecting seam.
[0053] Special embodiments of the bipolar plate have already been explained above in connection with special embodiments of the method according to the invention for the materially bonding of a first bipolar plate layer and a second bipolar plate layer of a bipolar plate for an electrochemical unit of an electrochemical device.
[0054] The method according to the invention for the material-locking connection of a first bipolar plate layer and a second bipolar plate layer of a bipolar plate can be used in particular for the material-locking connection of the bipolar plate layers of the bipolar plate according to the invention.
[0055] The bipolar plate according to the invention can be produced in particular using the method according to the invention for the material-to-material connection of a first bipolar plate layer and a second bipolar plate layer of a bipolar plate.
[0056] The bipolar plate according to the invention is particularly suitable for use in an electrochemical device comprising a plurality of electrochemical units which follow one another along a stacking direction and each comprise a bipolar plate according to the invention.
[0057] Such an electrochemical device may, for example, be a fuel cell device or an electrolyzer.
[0058] For example, the electrochemical device can be designed as a polymer electrolyte membrane (PEM) fuel cell device. Further features and advantages of the invention are the subject of the following description and the drawings of exemplary embodiments.
[0059] The drawings show:
[0060] Fig. 1 is a plan view of a bipolar plate for an electrochemical unit of an electrochemical device, which comprises a plurality of electrochemical units which follow one another along a stacking direction, wherein the bipolar plate comprises a first bipolar plate layer and a second bipolar plate layer which are materially connected to one another in a contact region of the bipolar plate layers along a connecting seam, wherein at least one support structure is formed on the first bipolar plate layer and / or on the second bipolar plate layer, wherein a support surface of the at least one support structure is offset from the surface of the bipolar plate layer on which the support structure is formed in the contact region along the stacking direction from the respective other bipolar plate layer, and wherein the at least one support structure has an edge at which the support structure extends into a planar region of the bipolar plate layer,on which the support structure is formed, wherein the smallest distance of the edge of the support structure from the center line of the connecting seam taken perpendicular to the center line of the connecting seam is at most 0.8 mm, looking towards the anode side of the bipolar plate;,
[0061] Fig. 2 is a plan view of a left end region of the bipolar plate from Fig. 1; Fig. 3 is an enlarged view of region I from Fig. 2;
[0062] Fig. 4 is a fragmentary, partially sectioned view of the bipolar plate region of Fig. 3, cut along line 4-4 in Fig. 3;
[0063] Fig. 5 is a partial plan view of a connecting seam of the bipolar plate from Fig. 3 and support structures adjacent to the connecting seam;
[0064] Fig. 6 is a plan view of the end region of the bipolar plate from Fig. 2, looking towards the cathode side of the bipolar plate;
[0065] Fig. 7 is an enlarged view of area II from Fig. 6;
[0066] Fig. 8 is a partial longitudinal section through a web-shaped support structure of the bipolar plate, along the line 8 - 8 in Fig. 7;
[0067] Fig. 9 is an enlarged view of area III from Fig. 6;
[0068] Fig. 10 is a schematic sectional view showing how a clamping force is applied to the first bipolar plate layer and the second bipolar plate layer by means of a plurality of clamping tools, wherein the clamping tools are supported on both sides of a connecting seam to be produced on a support structure of the first bipolar plate layer and on a support structure of the second bipolar plate layer; Fig. 11 is a schematic longitudinal section through clamping tools, which are supported on cup-shaped support structures formed on the first bipolar plate layer and on the second bipolar plate layer, and on flat regions of the first bipolar plate layer and the second bipolar plate layer lying between the support structures, along the line 11-11 in Fig. 10;
[0069] Fig. 12 shows a schematic section corresponding to Fig. 10 through the bipolar plate layers and the clamping tools supported on support structures of the bipolar plate layers, wherein on the side shown in Fig.
[0070] 12 on the side to the left of the connecting seam, such support structures are only formed on the first bipolar plate layer;
[0071] Fig. 13 shows a schematic longitudinal section corresponding to Fig. 11 through the clamping tools and the support structures which are formed on the first bipolar plate layer, along the line
[0072] 13 - 13 in Fig. 12;
[0073] Fig. 14 is a partial plan view of a medium distribution area of a second embodiment of a bipolar plate, wherein web-shaped support structures of a medium flow field extend obliquely to sections of a connecting seam of the bipolar plate;
[0074] Fig. 15 is a plan view of the rear side of the bipolar plate region of Fig. 14, wherein web-shaped support structures of a medium flow field run parallel to the sections of the connecting seam of the bipolar plate; and Fig. 16 is a partial longitudinal section through the bipolar plate of Figs. 15 and 16, along line 16-16 in Fig. 14, wherein the course of the sectional plane in Fig. 15 is indicated by line 16'-16'.
[0075] Identical or functionally equivalent elements are designated by the same reference numerals in all figures.
[0076] A bipolar plate shown in Figs. 1 to 9 and designated as a whole by 100 forms a component of an electrochemical unit 102 (not shown as a whole), which may comprise, in addition to the bipolar plate 100, a membrane electrode arrangement, gas diffusion layers and a sealing arrangement.
[0077] A plurality of such electrochemical units 102 follow one another along a stacking direction 104 to form a stack of electrochemical units 102, which is a component of an electrochemical device 106, for example a fuel cell device.
[0078] The bipolar plate 100 has a substantially rectangular shape, with long sides 107 of the bipolar plate 100 extending along a longitudinal direction 108 and short sides 109 of the bipolar plate 100 extending along a transverse direction 110 of the bipolar plate 100.
[0079] The longitudinal direction 108 and the transverse direction 110 are preferably aligned perpendicular to each other and perpendicular to the stacking direction 104.
[0080] The longitudinal direction 108 is also referred to as the x-direction, the transverse direction 110 is referred to as the y-direction, and the stacking direction 104 is referred to as the z-direction. The x-direction, the y-direction, and the z-direction form a rectangular coordinate system.
[0081] The bipolar plate 100 has two end regions 112 and an electrochemically active region 114 located between the end regions 112.
[0082] The electrochemically active region 114 of the bipolar plate 100 comprises an anode gas flow field 116 through which an anode gas can flow, a cathode gas flow field 118 through which a cathode gas can flow, and a coolant flow field 120 through which a coolant can flow.
[0083] In the embodiment described here, the bipolar plate 100 is formed in two layers and comprises a first bipolar plate layer 121 and a second bipolar plate layer 123.
[0084] In the embodiment shown in the drawing, the first bipolar plate layer 121 is an anode-side bipolar plate layer 122 on which the anode gas flow field 116 is formed, and the second bipolar plate layer 123 is a cathode-side bipolar plate layer 124 on which the cathode gas flow field 118 is formed.
[0085] In principle, however, the first bipolar plate layer 121 can also be a cathode-side bipolar plate layer 124 and the second bipolar plate layer 123 can be an anode-side bipolar plate layer 122.
[0086] The bipolar plate layers 121 and 123 consist of a material with good electrical conductivity, preferably a metallic material.
[0087] The bipolar plate layers 121 and 123 are integrally connected to one another along connecting seams 294, preferably welded, in particular by laser welding. The anode flow field 116 of the bipolar plate 100 is in fluid communication with an anode-side electrode of a membrane-electrode assembly, optionally via an anode-side gas diffusion layer.
[0088] The cathode flow field 118 of the bipolar plate 100 is in fluid communication with a cathode-side electrode of a membrane-electrode arrangement, optionally via a cathode-side gas diffusion layer.
[0089] Thus, anode gas and cathode gas can flow from the electrochemically active region 114 of the bipolar plate 100 to the electrochemically active regions of each membrane electrode assembly. Therefore, the region of the bipolar plate 100 provided with the anode gas flow field 116 and the cathode gas flow field 118 is referred to as its electrochemically active region 114, even though no electrochemical reactions take place at the bipolar plate 100 itself.
[0090] The anode gas flow field 116 comprises anode gas flow channels 126 whose main flow direction is aligned parallel to the longitudinal direction 108 (x-direction) of the bipolar plate 100.
[0091] The cathode gas flow field 118 comprises cathode gas flow channels 128 whose main flow direction extends parallel to the longitudinal direction 108 (x-direction) of the bipolar plate 100.
[0092] In its end regions 112, of which a first end region 112a is shown in Figs. 2 to 9, the bipolar plate 100 has a plurality of medium passage openings 130 through which a fluid medium to be supplied to the electrochemical device 106 (an anode gas (fuel gas, for example, hydrogen), a cathode gas (oxidizing agent, for example, oxygen or air), or a coolant (for example, water)) can pass through the bipolar plate 100. The medium passage openings 130 of the bipolar plates 100 arranged consecutively in the stack of electrochemical units 102 and the spaces located between the medium passage openings 130 in the stacking direction 104 together form a medium channel 132.
[0093] Each of the medium channels 132 in one of the end regions 112 of the bipolar plate 100, through which a fluid medium can be supplied to the electrochemical device 100, is assigned a different medium channel 132 in the respective opposite end region 112, through which the respective fluid medium can be discharged from the electrochemical device 106.
[0094] The fluid media pass through the anode gas flow field 116, the cathode gas flow field 118 or the coolant flow field 120 in the electrochemically active region 114 of the bipolar plate 100 from one end region 112 to the other end region 112.
[0095] In the first end region 112a of the bipolar plate 100 shown in Figs. 2 to 9, an anode gas passage opening 134, a cathode gas passage opening 136 and a coolant passage opening 138 are arranged.
[0096] In principle, each of these passage openings 134, 136 and 138 can serve either to supply the respective medium to the electrochemical device 106 or to remove the respective medium from the electrochemical device 106.
[0097] In principle, each of the three media—anode gas, cathode gas, and coolant—can flow through the electrochemically active region 114 parallel to the other media or in an opposite main flow direction relative to the main flow directions of one or two of the other media. In a preferred embodiment of the invention, all passage openings 134, 136, and 138 arranged in the first end region 112a of the bipolar plate 100 serve to supply the respective medium to the electrochemical device 106, and the passage openings 134, 136, and 138 arranged in the second end region 112b of the bipolar plate 100 serve to remove the respective medium from the electrochemical device 106.
[0098] In order to prevent undesired leakage of the fluid media from the respective associated passage openings 134, 136 and 138, each of these passage openings is provided with a sealing bead 140.
[0099] The anode gas passage opening 134 is surrounded by an anode gas sealing bead 142.
[0100] In order to be able to supply the anode gas from the anode gas passage opening 134 to the anode gas flow field 136, the anode gas sealing bead 142 is provided on its inner side facing the anode gas passage opening 134 with a plurality of anode gas inlets 144 through which anode gas can flow from the anode gas passage opening 134 into the interior of the anode gas sealing bead 142 (see Fig. 2).
[0101] The anode gas inlets 144 each open at an edge 146 of the anode gas passage opening 134.
[0102] In the illustrated embodiment, the edge 146 of the anode gas passage opening 134 is square; however, the polygonal edge 146 of the anode gas passage opening 134 can also have more or fewer than four corners.
[0103] The corners of the anode gas passage opening 134 are preferably rounded to prevent tearing of the bipolar plate layers 122 and 124 in the region of these corners. To allow the anode gas to escape from the interior of the anode gas sealing bead 142, the anode gas sealing bead 142 is provided with a plurality of anode gas outlets 154 on its outer side facing away from the anode gas passage opening 134.
[0104] The anode gas outlets 154 are preferably arranged on a portion 156 of the anode gas sealing bead 142 which faces the electrochemically active region 114 of the bipolar plate 100.
[0105] The anode gas inlets 144, which are arranged on the same portion 156 of the anode gas sealing bead 142, are preferably offset from the anode gas outlets 154 along the circumferential direction of the anode gas sealing bead 142.
[0106] The anode gas flows through the anode gas outlets 154 at the section 156 of the anode gas sealing bead 142 into an anode gas distribution region 170, which serves to distribute the anode gas as evenly as possible to the anode gas flow channels 126 of the anode gas flow field 116.
[0107] The anode gas distribution region 170 comprises a plurality of directed distribution structures 172 and a plurality of non-directed distribution structures 174, which serve to deflect the anode gas from its original flow direction.
[0108] The directed distribution structures 172 are designed, for example, as essentially linearly extending distribution webs 176.
[0109] The non-directional distribution structures 174 are formed, for example, as substantially cup-shaped distribution knobs 178. The distribution structures 172 and 174, like all other structures of the bipolar plate 100 described above and below, are preferably formed integrally with the material of the bipolar plate layers 121 or 123 and are introduced into the respective bipolar plate layer 121 or 123 by a forming process, for example, by a stamping process or a deep-drawing process.
[0110] The cathode gas passage opening 136 is surrounded by a cathode gas sealing bead 162.
[0111] The coolant passage opening 138 is surrounded by a coolant sealing bead 164.
[0112] Near the outer edge 180 of the bipolar plate 100 there is a ring-shaped closed edge bead 182.
[0113] The edge bead 182 encloses the electrochemically active region 114 of the bipolar plate 100, the anode gas passage openings 134 and the anode gas sealing beads 142 in both end regions 112, the cathode gas passage openings 136 and the cathode gas sealing beads 162 in both end regions 112, and the coolant passage openings 138 and the coolant sealing beads 164 in both end regions 112 of the bipolar plate 100.
[0114] The edge bead 182 serves to prevent the media to be supplied to the electrochemical device 106, in particular the anode gas, the cathode gas, and the coolant, from escaping from the electrochemical units 102 into the exterior space 184 of the electrochemical device 106. To allow the cathode gas to flow out of the cathode gas passage opening 136 through the cathode gas sealing bead 162, the cathode gas sealing bead 162 is provided with a plurality of cathode gas inlets 194 on its inner side facing the cathode gas passage opening 136 (see in particular Fig. 6).
[0115] Through the cathode gas inlets 194, cathode gas passes from the cathode gas passage opening 136 into the interior of the cathode gas sealing bead 162.
[0116] The cathode gas inlets 194 preferably open at the edge 198 of the cathode gas passage opening 136.
[0117] In the embodiment illustrated in the drawing, the edge 198 of the cathode gas passage opening 136 is rectangular. However, the number of corners of the polygonal edge 198 can also be fewer or larger than four.
[0118] Cathode gas outlets 214, which are arranged on the outer side of the cathode gas sealing bead 162 facing away from the cathode gas passage opening 136 and through which the cathode gas flows out of the interior of the cathode gas sealing bead 162, are preferably all arranged on a section 200 of the cathode gas sealing bead 162 which faces the electrochemically active region 114 of the bipolar plate 100.
[0119] Preferably, the cathode gas inlets 194, which are arranged on the same section 200 of the cathode gas sealing bead 162, are arranged offset from the cathode gas outlets 214 along the circumferential direction of the cathode gas sealing bead 162.
[0120] Preferably, a total of two or more, in particular four or more, particularly preferably six or more, in the illustrated embodiment eight, cathode gas outlets 214 are provided on the cathode gas sealing bead 162. The cathode gas flows through the cathode gas outlets 214 into a cathode gas distribution region 216 of the bipolar plate 100, which serves to distribute the cathode gas as evenly as possible among the cathode gas flow channels 128 of the cathode gas flow field 118.
[0121] For this purpose, the cathode gas distribution region comprises distribution structures 218, which are designed as directional distribution structures 220 or as non-directional distribution structures 221.
[0122] The directional distribution structures 220 are preferably formed as linearly extending distribution webs 222.
[0123] The non-directional distribution structures 221 are formed, for example, as essentially cup-shaped distribution knobs 223.
[0124] In order to allow the coolant to flow out of the coolant passage opening 138 into the coolant flow field 120 of the bipolar plate 100, the coolant sealing bead 164 is provided with a plurality of coolant inlets 224 on its inner side facing the coolant passage opening 138 (see in particular Figs. 2 and 6).
[0125] Through the coolant inlets 224, the coolant passes from the coolant passage opening 138 into the interior of the coolant sealing bead 164.
[0126] The edge 228 of the coolant passage opening 138 is rectangular in the embodiment illustrated in the drawing. However, the number of corners of the polygonal edge 228 of the coolant passage opening 138 can also be greater or less than four. Coolant outlets 225, which are arranged on the outer side of the coolant sealing bead 164 facing away from the coolant passage opening 138 and through which the coolant flows out of the interior of the coolant sealing bead 164, are preferably all arranged on a section 230 of the coolant sealing bead 164 facing the electrochemically active region 114 of the bipolar plate 114.
[0127] Preferably, the coolant inlets 224, which are arranged on the same section 230 of the coolant sealing bead 164, are arranged offset from the coolant outlets 225 along the circumferential direction of the coolant sealing bead 164.
[0128] The coolant flows through the coolant outlets 225 into a coolant distribution area 242 of the bipolar plate 100, which serves to distribute the coolant as evenly as possible to the coolant flow channels of the coolant flow field.
[0129] In this coolant distribution region 242, the anode-side bipolar plate layer 122 and the cathode-side bipolar plate layer 124 are offset in opposite directions along the stacking direction 104 with respect to a longitudinal center plane of the bipolar plate 100 oriented perpendicular to the stacking direction 104, such that a large flow-through cross-section is available for the flow of the coolant through the coolant distribution region 242.
[0130] The bipolar plate 100 is preferably rotationally symmetrical with respect to a rotation of 180° around an axis of rotation extending through the center of the electrochemically active region 114 of the bipolar plate 100 and parallel to the stacking direction 104 (z-direction). The medium passage openings 130 arranged in the second end region 112b, in particular the anode gas passage opening 134 arranged there, the cathode gas passage opening 136 arranged there, and the coolant passage opening 138 arranged there, are therefore preferably constructed and arranged essentially in the same way as the anode gas passage opening 134, the cathode gas passage opening 136 and the coolant passage opening 138 in the first end region 112a, which were described above.
[0131] Since the bipolar plate 100 described above and shown in Figs. 1 to 9 is designed in multiple layers, the first bipolar plate layer 121 and the second bipolar plate layer 123 must be connected to one another in a fluid-tight manner along the connecting seams 294 in order to prevent one of the media to be supplied to the electrochemical device 106 (anode gas, cathode gas, coolant) from passing through gaps between the first bipolar plate layer 121 and the second bipolar plate layer 123 to a medium passage opening 130 of another medium or into a medium distribution region or into a medium flow field of another medium.
[0132] Such connecting seams 294, at which the first bipolar plate layer 121 and the second bipolar plate layer 123 are integrally connected to one another, preferably by welding, in particular by laser welding, are arranged, for example, in the region between the outer side of the anode gas sealing bead 142 on the one hand and the anode gas distribution region 170 on the other hand (see in particular Figs. 3 to 5), as well as between the cathode gas sealing bead 162 on the one hand and the cathode gas distribution region 216 on the other hand (see in particular Fig. 9), and between the anode gas sealing bead 142 on the one hand and the coolant distribution region 242 on the other hand (see in particular Fig. 7). As shown, for example, in Figs.As can be seen from Figures 3 to 5, support structures 296 are preferably formed on both sides of the connecting seam 294. These support structures serve, during the production of the connecting seam 294, to support clamping tools that are in contact with support surfaces 298 of the support structures 296 and optionally also in contact with planar contact regions 300 of the bipolar plate layers 121, 123 located between the support structures 296, in order to press the first bipolar plate layer 121 and the second bipolar plate layer 123 against each other with a sufficient clamping force during the joining process, in particular a welding process. This ensures that, before the joining process, at most, a "technical zero gap" of less than 0.03 mm in height (along the stacking direction 104) remains between the two bipolar plate layers 121, 123.
[0133] As can be seen from Figs. 3 to 5, the support structures 296 on the side of the connecting seam 294 facing the sealing bead 140 (anode gas sealing bead 142) are formed by the aforementioned non-directional distributor structures 174 in the form of distributor knobs 178.
[0134] These cup-shaped support structures 302 each have a support surface 298 which is oriented perpendicular to the stacking direction 104 (z-direction) of the bipolar plate 100 and is offset from the second bipolar plate layer 123 along the stacking direction 104 (z-direction) of the bipolar plate 100 relative to the surface 299 of the first bipolar plate layer 121, on which these cup-shaped support structures 302 are formed by forming, in the planar contact region 300, in which the two bipolar plate layers 121 and 123 lie flat against one another.
[0135] The support surface 298 of the cup-shaped support structures 302 preferably has a smallest dimension a perpendicular to the stacking direction 104 (z-direction) of the bipolar plate 100, which is at least 0.1 mm, in particular at least 0.5 mm. Furthermore, the smallest dimension a of the support surfaces 298 of these cup-shaped support structures 302 perpendicular to the stacking direction 104 (z-direction) of the bipolar plate 100 is preferably at most 3 mm, in particular at most 1.5 mm.
[0136] As can further best be seen from Fig. 5, each of the cup-shaped support structures 302 has an edge 304 at which the respective support structure 302 merges into a flat region of the first bipolar plate layer 121 on which the support structures 302 are formed, wherein the smallest distance d of the edge 304 of the respective support structure 296 from the center line 306 of the connecting seam 294 - taken perpendicular to the center line 306 of the connecting seam 294 - is at most 0.8 mm, in particular at most 0.5 mm, particularly preferably at most 0.3 mm.
[0137] The greatest distance D of the edge 304 of the respective support structure 296 from the center line 306 of the connecting seam 294, taken perpendicular to the center line 306 of the connecting seam 294, is preferably at most 5 mm, in particular at most 3 mm, particularly preferably at most 2 mm.
[0138] As can further be seen from Figs. 3 to 5, the support structures 296 on the side of the connecting seam 294 facing away from the sealing bead 140 (anode gas sealing bead 142) are formed by the directional distributor structures 172 of the anode distribution region 170 in the form of the distributor webs 176.
[0139] These web-shaped support structures 308 also each comprise a support surface 298, the smallest dimension a' of which perpendicular to the stacking direction 104 (z-direction) of the bipolar plate 100 is preferably at least 0.1 mm, in particular at least 0.5 mm. The web-shaped support structures 308 have their greatest dimension perpendicular to the stacking direction 104 (z-direction) of the bipolar plate 100 along their longitudinal direction 310, and this greatest dimension is preferably greater than 3 mm, in particular greater than 5 mm.
[0140] The web-shaped support structures 308 run transversely to the connecting seam 294, and their ends 292 facing the sealing bead 140 (anode gas sealing bead 142) are preferably located at a distance d' from the center line 306 of the connecting seam 294, taken perpendicular to the center line 306 of the connecting seam 294, which is less than 0.8 mm, in particular less than 0.5 mm, particularly preferably less than 0.3 mm.
[0141] The ends 292 of the web-shaped support structures 308 lie on an edge 312 of the respective support structure 296, at which edge 312 the support structure 296 merges into a planar region of the first bipolar plate layer 121 on which the support structure 296 is formed, wherein the smallest distance d' of the edge 312 of the support structure 296 from the center line 306 of the connecting seam 294, taken perpendicular to the center line 306 of the connecting seam 294, is preferably at most 0.8 mm, in particular at most 0.5 mm, particularly preferably at most 0.3 mm.
[0142] In the operating state of the electrochemical device 106, adjacent components of electrochemical units 102, for example gas diffusion layers or sub-gaskets of membrane electrode units of electrochemical units 102, are supported on the support surfaces 298 of the support structures 296.
[0143] The distances between these support surfaces 298 should therefore not be too large to prevent these adjacent components of electrochemical units 102 from sagging in the areas between the support surfaces 298 and reducing the flow-through cross sections present there. A method for the integral connection of the first bipolar plate layer 121 and the second bipolar plate layer 123 is explained below with reference to Figs. 10 and 11.
[0144] 10 and 11 refer to a case in which cup-shaped support structures 302 are formed on the first bipolar plate layer 121 on both sides of the connecting seam 294 to be produced, and cup-shaped support structures 302' are also arranged on the second bipolar plate layer 123 at positions which are essentially congruent with the positions of the cup-shaped support structures 302 on the first bipolar plate layer 121 or are only slightly offset from these positions.
[0145] The first support structures 296, which are formed on the first bipolar plate layer 121, each have a first edge 304, at which these first support structures 296 transition into a planar region of the first bipolar plate layer 121, and the second support structures 296', which are formed on the second bipolar plate layer 123, each have a second edge 304', at which the second support structures 296' transition into a planar region of the second bipolar plate layer 123, wherein the first edges 304 and the second edges 304' are substantially congruent with one another in a projection onto a plane 314 oriented perpendicular to the stacking direction 104 (z-direction) of the bipolar plate 100, or deviate from one another by a distance of at most 0.5 mm - taken perpendicular to the longitudinal direction of the respective first edge 304 or the respective second edge 304'.
[0146] The configuration of the support structures 296 shown in Figs. 10 and 11 thus differs from the specific configuration of the support structures 296 shown in Figs. 3 to 5 for the area between the anode gas sealing bead 142 and the anode gas distribution area 170; however, apart from the specific design of the clamping tools 316 used to carry out the joining process, no fundamental differences arise.
[0147] First, the first bipolar plate layer 121 and the second bipolar plate layer 123 are arranged such that they are in contact with each other at one or more contact areas 300, preferably over a large area.
[0148] By means of several clamping tools 316, 316', a clamping force is applied to the first bipolar plate layer 121 and the second bipolar plate layer 123, by means of which the first bipolar plate layer 121 and the second bipolar plate layer 123 are pressed against each other in the contact regions 300, so that at most a "technical zero gap" with a height (extension along the stacking direction 104) of less than 0.03 mm remains in the contact regions 300.
[0149] The clamping tools 316 rest on support surfaces 298 of the support structures 296, which are offset from the respective other bipolar plate layer 123 by a height H along the stacking direction 104 in the contact regions 300 relative to the surface 299 of the bipolar plate layer 121 on which the support structures 296 are formed.
[0150] The smallest distances d, d' of the edges 304, 304' of the support structures 296, 296' from the center line 306 of the connecting seam 294 to be produced are so small, preferably at most 0.8 mm, in particular at most 0.5 mm, particularly preferably at most 0.3 mm, that the clamping forces introduced along the edges 304, 304' into the contact regions 300 of the bipolar plate layers 121, 123 are sufficiently high to produce a stable clamping effect between the bipolar plate layers 121 and 123 in the flat contact regions 300. As can best be seen from the longitudinal section in Fig.11, the clamping tools 316, 316', which in the exemplary embodiment shown are designed as clamping webs 318 extending in a longitudinal direction, rest both on the support surfaces 298 of the support structures 296 and, in the regions between two support structures 296 following one another along the longitudinal direction of a clamping tool 316, 316', on a respective flat contact region 300 of the first bipolar plate layer 121 and the second bipolar plate layer 123, respectively, in order to transmit clamping forces to the bipolar plate layers 121, 123 at these surfaces.
[0151] While the clamping forces are applied to the bipolar plate layers 121, 123 by means of the clamping tools 316, the first bipolar plate layer 121 and the second bipolar plate layer 123 are integrally connected to one another along the connecting seam 294, preferably by welding, for example by laser welding.
[0152] In this case, a laser for producing a connecting seam 294 by means of laser welding can be arranged on the side of the first bipolar plate layer 121 facing away from the second bipolar plate layer 123 or on the side of the second bipolar plate layer 123 facing away from the first bipolar plate layer 121.
[0153] After the creation of the connecting seam 294, the clamping tools 316, 316' are released from the bipolar plate layers 121, 123.
[0154] A second embodiment of a method for the materially bonding of the first bipolar plate layer 121 and the second bipolar plate layer 123, shown in Figs. 12 and 13, differs from the first embodiment shown in Figs. 10 and 11 in that no support structures 296' for a clamping tool 316' are provided on the second bipolar plate layer 123 to the left of the connecting seam 294 to be created, but instead the clamping tool 316' rests against a flat area of the second bipolar plate layer 123 in this area. As can be seen from the longitudinal section in Fig. 13, this clamping tool 316' therefore has the same cross-section throughout its longitudinal direction and thus has an overall substantially cuboid shape.
[0155] Otherwise, the second embodiment of a method for materially connecting the first bipolar plate layer 121 and the second bipolar plate layer 123 shown in Figs. 12 and 13 corresponds to the first embodiment shown in Figs. 10 and 11, to the above description of which reference is made in this respect.
[0156] As can be seen from Figs. 6 and 9, the cathode gas sealing bead 162 is also surrounded by a closed connecting seam 294.
[0157] As can best be seen from Fig. 9, as in the case of the connecting seam 294 surrounding the anode gas sealing bead 142 described above, support structures 296 are provided on both sides of the connecting seam 294 for supporting clamping tools 316 during the creation of the connecting seam 294.
[0158] The support structures 296, which are arranged on the side of the connecting seam 294 facing the sealing bead 140 (cathode gas sealing bead 162), are designed as cup-shaped support structures 302 molded into the second bipolar plate layer 123, while the support structures 296 arranged on the side of the connecting seam 294 facing away from the sealing bead 140 (cathode gas sealing bead 162) are designed as web-shaped support structures 308 molded into the second bipolar plate layer 123, the longitudinal direction 310 of which runs transversely to the center line 306 of the connecting seam 294.
[0159] Preferably, the longitudinal direction 310 forms an angle a of more than 75°, in particular more than 80°, with the center line 306 of the connecting seam 294. Furthermore, the support structures 296 on both sides of the connecting seam 294 surrounding the cathode gas sealing bead 162 are identical in structure, function, and method of manufacture to the support structures 296 on both sides of the connecting seam 294 surrounding the anode gas sealing bead 142, to whose above description reference is made in this regard.
[0160] The method for the integral connection of the first bipolar plate layer 121 and the second bipolar plate layer 123 along the connecting seam 294, which surrounds the cathode gas sealing bead 162, corresponds - except for the interchange of the first bipolar plate layer 121 and the second bipolar plate layer 123 with one another - to the method described above with reference to Figs. 10 to 13, to the above description of which reference is made in this respect.
[0161] As can be seen from Figs. 6 and 7, on the cathode side of the bipolar plate 100 along the connecting seam 294 surrounding the anode gas sealing bead 142, on the side facing away from the sealing bead (anode gas sealing bead 142), a support structure 296 is provided which extends parallel to the connecting seam 294.
[0162] This web-shaped support structure 308 can also serve to support a clamping tool 316 during the creation of the connecting seam 294.
[0163] 14 to 16 show a second embodiment of a bipolar plate 100, in which a connecting seam 294, along which a first bipolar plate layer 121 and a second bipolar plate layer 123 are integrally connected to one another, runs at least in sections parallel to a bead 320, on the flank 322 of which facing the connecting seam 294, a plurality of medium outlet openings 324 are arranged. On the side of the connecting seam 294 facing away from the bead 320, a medium flow field 326 is arranged, which has webs 328 that run at an angle of approximately 45° with respect to the longitudinal direction of the connecting seam 294.
[0164] Between each two webs 328, a medium flow channel 330 is formed, into which medium flowing out of the medium outlet openings 324 of the bead 320 flows.
[0165] The medium flow field 326 shown in Fig. 14 can, for example, be the anode gas flow field 116 of the bipolar plate 100.
[0166] Fig. 15 shows the back side of the bipolar plate 100 in the area shown in Fig. 14 and thus a medium flow field 326' which is associated with another medium to be supplied to the electrochemical device 106.
[0167] If Fig. 14 shows the anode gas flow field 116, Fig. 15 shows the cathode gas flow field 118 of the bipolar plate 100.
[0168] However, the anode side and the cathode side of the bipolar plate 100 can also be interchanged.
[0169] As can be seen from Fig. 15, the webs 328 of the medium flow field 326' run at least partially parallel to the connecting seam 294.
[0170] The medium channels 330' of the medium flow field 326' and the medium channels 330 of the medium flow field 326 therefore intersect, forming a sequence of local support centers 332 parallel to the connecting seam 294, at which the first bipolar plate layer 121 and the second bipolar plate layer 123 support each other, so that a force equilibrium can be established at these local support centers 332 when the bipolar plate layers 121 and 123 are pressed together, and elevations in the first bipolar plate layer 121 or second bipolar plate layer 123 adjacent to these local support centers 332 can serve as support structures 296 for supporting clamping tools 316 (see Fig. 16).
[0171] Thus, even in this embodiment of the bipolar plate 100, the method described above with reference to Figs. 10 to 13 for the materially bonding of the first bipolar plate layer 121 and the second bipolar plate layer 123 can be carried out by means of clamping tools 316, which are supported on support structures 296 that are formed into the first bipolar plate layer 121 or into the second bipolar plate layer 123.
Claims
A method for the integral joining of a first bipolar plate layer (121) and a second bipolar plate layer (123) of a bipolar plate (100) for an electrochemical unit (102) of an electrochemical device (106) comprising a plurality of electrochemical units (102) which follow one another along a stacking direction (104), the method comprising the following: Bringing the first bipolar plate layer (121) and the second bipolar plate layer (123) into contact at one or more contact areas (300) of the bipolar plate layers (121, 123); Applying a clamping force to the first bipolar plate layer (121) and the second bipolar plate layer (123) by means of one or more clamping tools (316); and materially connecting the first bipolar plate layer (121) and the second bipolar plate layer (123) along a connecting seam (294); characterized in that at least one clamping tool (316) is supported on a support surface (298) of at least one support structure (296) of at least one of the bipolar plate layers (121, 123), wherein the support surface (298) of the support structure (296) is offset from the respective other bipolar plate layer (123, 121) in the contact region (300) along the stacking direction (104) with respect to the surface (299) of the bipolar plate layer (121, 123) on which the support structure (296) is formed. Method according to claim 1, characterized in that at least one of the clamping tools (316) is supported on a plurality of support surfaces (298) of a plurality of different support structures (296) and on a plurality of contact regions (300) of the bipolar plate layers (121, 123) located between the support structures (296). Method according to one of claims 1 or 2, characterized in that at least one first clamping tool (316) is supported on at least one first support structure (296) formed on the first bipolar plate layer (121), and at least one second clamping tool (316') is supported on at least one second support structure (296') formed on the second bipolar plate layer (123).Method according to claim 3, characterized in that the first support structure (296) has a first edge (304) at which the first support structure (296) transitions into a planar region of the first bipolar plate layer (121), and the second support structure (296') has a second edge (304') at which the second support structure (296') transitions into a planar region of the second bipolar plate layer (123), wherein the first edge (304) and the second edge (304') are substantially congruent with one another in a projection onto a plane (314) oriented perpendicular to the stacking direction (104) or deviate from one another by a distance of at most 0.5 mm.Method according to one of claims 1 to 4, characterized in that at least one support structure (296) is formed at a location of one of the bipolar plate layers (121, 123) opposite which a flat region of the respective other bipolar plate layer (123, 121) which is not provided with a support structure (296) lies. Method according to one of claims 1 to 5, characterized in that the support surface (298) of at least one support structure (296) has a smallest extent (a) perpendicular to the stacking direction (104) which is at least 0.1 mm. Method according to one of claims 1 to 6, characterized in that the support surface (298) of at least one support structure (296) has a smallest extent (a) perpendicular to the stacking direction (104) which is at most 3 mm. Method according to one of claims 1 to 7, characterized in that the support surface (298) of at least one support structure (296) has a greatest extent perpendicular to the stacking direction (104) which is greater than 3 mm.Method according to one of claims 1 to 8, characterized in that at least one support structure (296) has an edge (304, 312) at which the support structure (296) merges into a flat region of the bipolar plate layer (121, 123) on which the support structure (296) is formed, wherein the smallest distance (d) of the edge (304, 312) of the support structure (296) from the center line (306) of the connecting seam (294) is at most 0.8 mm. Method according to one of claims 1 to 9, characterized in that at least one support structure (296) has an edge (304) at which the support structure (296) merges into a flat region of the bipolar plate layer (121, 123) on which the support structure (296) is formed, wherein the greatest distance (D) of the edge (304) of the support structure (296) from the center line (306) of the connecting seam (294) is at most 5 mm. Method according to one of claims 1 to 10, characterized in that at least one support structure (296) is circular or oval in a plan view along the stacking direction (104). Method according to one of claims 1 to 11, characterized in that at least one support structure (296) is web-shaped. Method according to claim 12, characterized in that the at least one web-shaped support structure (308) runs, at least in sections, substantially parallel to the connecting seam (294). Method according to one of claims 12 or 13, characterized in that a plurality of web-shaped support structures (308) run transversely to the connecting seam (294) and end at a distance (d') from the center line (306) of the connecting seam (294) of less than 0.8 mm.Bipolar plate for an electrochemical unit (102) of an electrochemical device (106), which comprises a plurality of electrochemical units (102) which follow one another along a stacking direction, wherein the bipolar plate (100) comprises the following: a first bipolar plate layer (121) and a second bipolar plate layer (123), which are materially connected to one another in a contact region (300) of the bipolar plate layers (121, 123) along a connecting seam (294); wherein at least one support structure (296) is formed on each of the first bipolar plate layer (121) and / or the second bipolar plate layer (123), wherein a support surface (298) of the at least one support structure (296) is opposite the surface (299) of the bipolar plate layer (121, 123). on which the support structure (296) is formed, is offset in the contact region (300) along the stacking direction (104) from the respective other bipolar plate layer (123, 121), and wherein the at least one support structure (296) has an edge (304, 312) at which the support structure (296) merges into a planar region of the bipolar plate layer (121, 123) on which the support structure (296) is formed, wherein the smallest distance (d, d') of the edge (304, 312) of the support structure (296) from the center line (306) of the connecting seam (294) is at most 0.8 mm. An electrochemical device comprising a plurality of electrochemical units (102) which follow one another along a stacking direction (104) and each comprise a bipolar plate (100) according to claim 15.