Bipolar plate and electrochemical cell
Patent Information
- Application Number
- EP2023720762
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-09-07
- Filing Date
- 2023-04-25
- Publication Date
- 2025-07-16
Smart Images
Figure 1.1
Abstract
Description
[0001] Bipolar plate and electrochemical cell
[0002] The invention relates to a bipolar plate comprising a first half-sheet and a second half-sheet, which are firmly connected to one another, wherein the bipolar plate has a plurality of fluid passage openings comprising fluid inlet openings and fluid outlet openings, wherein a first distribution field for distributing a fluid, an active field and a second distribution field for distributing the fluid are arranged on both sides of the bipolar plate, and with at least one seal on each side of the bipolar plate, wherein a transition region is formed between a fluid passage opening and an adjacent distribution field.
[0003] DE 10 2014 225 160 A1 describes a metal separator, i.e., a bipolar plate, for a fuel cell stack with an anode separator and a cathode separator. In particular, DE 10 2014 225 160 A1 describes a design of a transition region formed in the metal separator between a fluid passage opening and an active region (not shown in detail), in which electrochemical reactions take place. The metal separator has a seal on each side, with the seals arranged offset from one another. Furthermore, support elements embossed into the separators are arranged at the inlet and outlet of the metal separator, forming channels for the fluids for operating the fuel cell stack.
[0004] CN208722997 U discloses a bipolar plate for a fuel cell with an anode plate and a cathode plate, and its configuration in a transition region between a fluid passage opening and a reaction region in which electrochemical reactions take place. The seals arranged on both sides of the bipolar plate are offset from one another and each arranged in an elongated recess or bead.
[0005] DE 10 2020 202 075 A1 describes an electrochemical cell with a supply device or bipolar plate comprising a first and a second circuit board for supplying operating media from a fluid passage opening, here called a port connection, into a supply area. The circuit boards are formed with grooves for receiving seals, which are arranged offset from one another.
[0006] The object of the invention is to optimize a bipolar plate of the type mentioned above with regard to pressure loss and the sealing effect of the seals in the transition area. Furthermore, the object of the invention is to provide an electrochemical cell with such improved bipolar plates.
[0007] The object is achieved for the bipolar plate, comprising a first half-sheet and a second half-sheet, which are firmly connected to one another, in that the bipolar plate has a plurality of fluid passage openings comprising fluid inlet openings and fluid outlet openings, wherein a first distribution field for distributing a fluid, an active field and a second distribution field for distributing the fluid are arranged on both sides of the bipolar plate, and with at least one seal on each side of the bipolar plate, wherein in at least one transition region between a fluid passage opening and an adjacent distribution field
[0008] - the first half-sheet is provided with a first step and a second step in the direction of the second half-sheet, starting from a fluid inlet opening,
[0009] - the second half-sheet, starting from the fluid inlet opening in the region of the first stage, is provided with a third stage in the direction of the first half-sheet and is provided with a fourth stage in the region of the second stage, which is directed away from the first half-sheet,
[0010] - the first half-sheet has, in a region between the first stage and the second stage, elongated three-dimensional first embossed structures aligned parallel to one another, which are curved in the direction of the second half-sheet,
[0011] -the second half-sheet has, in a region between the third stage and the fourth stage, elongated three-dimensional second embossed structures aligned parallel to one another, which are curved in the direction of the first half-sheet, are aligned with the first embossed structures and are supported against the first embossed structures,
[0012] - the first half-sheet has a first sealing region, which is formed in the region of the first embossed structures on the side of the first half-sheet facing away from the second half-sheet and is arranged transversely to the first embossed structures and coincides with them, - the second half-sheet has a second sealing region, which is arranged in the region of the second embossed structures on the side of the second half-sheet facing away from the first half-sheet, transversely to the second embossed structures and coincides with them, wherein the first sealing region and the second sealing region are arranged congruently one above the other as seen perpendicular to a plane spanned by the bipolar plate, and
[0013] - the second half-sheet has an opening slot which is arranged between the fourth stage and the adjacent distributor field, wherein three-dimensional third embossed structures are present which are curved in the direction of the first half-sheet, are arranged in alignment with the second embossed structures in a fluid flow direction and are supported against the first half-sheet, wherein the opening slot is arranged such that the third embossed structures arranged in the second half-sheet are intersected by the latter.
[0014] Because the seals on the two half-sheets run congruently one above the other in the transition area between a distribution panel and a fluid passage opening, and the first and second embossed structures are filled and stiffened by the sealing material, the sealing effect on components adjacent to a bipolar plate in the area of the fluid passage openings is significantly increased. "Congruent" means that the center lines of the first and second sealing areas lie one above the other, viewed perpendicular to the plane spanned by the bipolar plate. However, the width of the first sealing area and the second sealing area can differ slightly. A cell stack of electrochemical cells can thus be constructed with defined compression of the seals.The application of the sealing material to the half-sheets is also possible more precisely in the transition area due to the first and second embossed structures, which provide improved support for each half-sheet. The distance between the first and second half-sheets is large enough to allow flow control with minimal pressure loss. It has proven effective to use a sealing layer in at least one transition area between a fluid passage opening and an adjacent distribution panel.
[0015] - the first half-sheet is provided with a third step and a fourth step in the direction of the second half-sheet, starting from a fluid outlet opening,
[0016] - the second half-sheet, starting from the fluid outlet opening in the region of the third step in the first half-sheet, is provided with a first step in the direction of the first half-sheet and, in the region of the fourth step in the first half-sheet, is provided with a second step which is directed away from the first half-sheet,
[0017] - the first half-sheet has, in a region between its third stage and its fourth stage, further elongated three-dimensional first embossed structures aligned parallel to one another and curved in the direction of the second half-sheet, - the second half-sheet has, in a region between its first stage and its second stage, further elongated three-dimensional second embossed structures aligned parallel to one another, curved in the direction of the first half-sheet, aligned in alignment with the further first embossed structures and supported against the further first embossed structures,
[0018] - the first half-sheet has a third sealing region, which is formed in the region of the further first embossed structures on the side of the first half-sheet facing away from the second half-sheet and is arranged transversely to the further first embossed structures and falling away from them,
[0019] - the second half-sheet has a fourth sealing region which is arranged in the region of the further second embossed structures on the side of the second half-sheet facing away from the first half-sheet, extending transversely to the further second embossed structures and slanting therefrom, wherein the third sealing region and the fourth sealing region are arranged congruently one above the other when viewed perpendicular to the plane spanned by the bipolar plate, and
[0020] - the second half-sheet has a further opening slot which is arranged between its second step and the adjacent distribution field, wherein three-dimensional further third embossed structures are present which are curved in the direction of the first half-sheet, are arranged in alignment with the further second embossed structures in a fluid flow direction and are supported against the first half-sheet, wherein the further opening slot is arranged such that the further third embossed structures arranged in the second half-sheet are intersected by it. The advantages of this arrangement in the region of a fluid outlet opening are analogous to those described above for the fluid inlet opening. Here, “congruent” is also understood to mean that the center lines of the third and fourth sealing regions lie one above the other when viewed perpendicular to the plane spanned by the bipolar plate.However, the width of the third sealing area and the fourth sealing area may differ slightly.
[0021] In the transition area between a distribution field and a fluid passage opening, there is an opening slot on each side of the bipolar plate, from which a fluid is guided from a fluid inlet opening via the opening slot towards the distribution field and the active field. Furthermore, in the transition area between a distribution field and a fluid passage opening, there is another opening slot on the same side of the bipolar plate, through which the fluid is guided from the active field via another distribution field towards a fluid outlet opening. An oxidizing agent is supplied to an active field on a first side of the bipolar plate, and a fuel is supplied to another active field on an opposite second side of the bipolar plate.
[0022] It has proven particularly effective if the first sealing area and the third sealing area are each designed as flat seals. The second sealing area and the fourth sealing area, on the other hand, preferably each have two parallel sealing beads. When constructing a cell stack, this improves the tightness and optimizes the compression of the seals of the stacked bipolar plates.
[0023] The first embossed structures and the second embossed structures are preferably aligned with their longitudinal axes in the direction of a fluid flow direction between the fluid passage opening and the adjacent distribution field. The first and second embossed structures are preferably elongated in a straight line and are designed with a constant width and length, so that they optimally support one another. A first fluid inlet opening for supplying oxidizing gas and a first fluid outlet opening for discharging it are preferably arranged on a first side of the bipolar plate. A second fluid inlet opening for supplying fuel gas and a second fluid outlet opening for discharging it are preferably arranged on a second side of the bipolar plate.
[0024] In particular, each half-sheet of the bipolar plate is three-dimensionally structured in the region of the first distribution field, the active field, and the second distribution field to form fluid conduction paths. Such structuring is achieved, in particular, by embossing the half-sheets. The structuring can be achieved by forming channels, locally limited elevations or depressions, and the like.
[0025] A fluid conduction path for a coolant is preferably formed between the first half-sheet and the second half-sheet of the bipolar plate. This path is fed via a fluid inlet opening. A fluid outlet opening serves to discharge the coolant.
[0026] The object is further achieved for an electrochemical cell comprising a plurality of bipolar plates according to the invention and a membrane electrode unit arranged between two bipolar plates, each of which is covered on both sides with a fluid transport layer.
[0027] The electrochemical cell is preferably an electrolysis cell for the electrolysis of water or a polymer electrolyte fuel cell for the decomposition of water into hydrogen as fuel and oxygen as oxidizing gas.
[0028] In an electrolysis cell, a fluid transport layer is also called a porous transport layer (PTL). In a fuel cell, a fluid transport layer is often referred to as a gas diffusion layer (GDL).
[0029] A stacked arrangement comprising several fuel cells or electrolysis cells can also be formed. Figures 1 to 9 are intended to illustrate the invention by way of example. Thus, Figure 1 shows a bipolar plate in plan view from one side. Figure 2 shows a cross-section 11-11 ' through the bipolar plate of Figure 1 in the region of a fluid inlet opening.
[0030] Figure 3 is a plan view of the section of the bipolar plate according to Figure 2,
[0031] Figure 4 is a side view of the section of the bipolar plate according to Figure 2 seen from the side of the fluid inlet opening,
[0032] Figure 5 is a side view of the section of the bipolar plate according to Figure 2 seen from the side of the distribution panel,
[0033] Figure 6 is a three-dimensional view of the section of the bipolar plate according to Figure 2 without showing the seal 6',
[0034] Figure 7 is a three-dimensional view of the section of the bipolar plate according to Figure 2 with seal 6',
[0035] Figure 8 shows a cross section III-III' through the bipolar plate of Figure 1 in the region of a fluid outlet opening, and
[0036] Figure 9 is a schematic three-dimensional representation of a stacked arrangement of electrochemical cells.
[0037] Figure 1 shows a rectangular bipolar plate 1 in a plan view from one side B. The bipolar plate 1 comprises a first half-sheet 1a and a second half-sheet 1b (see Figure 2), which are firmly connected to one another, for example by welding, gluing or the like. The bipolar plate 1 further has a plurality of fluid passage openings 2, which are arranged at both ends of the rectangular bipolar plate 1. The fluid passage openings 2 comprise fluid inlet openings 2a, 2c, 2e and fluid outlet openings 2b, 2d, 2f. Between the fluid passage openings 2 there is a first distribution field 3 for distributing a fluid, an active field 4 and a second distribution field 5 for distributing the fluid. This arrangement of fluid passage openings 2, distribution fields 3, 5 and active field 4 is also located in alignment on the second side A of the bipolar plate 1.The bipolar plate 1 has at least one seal 6, 6' on each side A, B (see Figure 2), the extent of which is indicated here as a dashed line for clarity. The seal 6, 6' runs around the circumference of each half-plate 1a, 1b and further around each of the fluid passage openings 2. A section 11-11', shown in Figure 2, was arranged in a transition region 7 between the fluid inlet opening 2c for fuel and the adjacent distribution field 5.
[0038] It can be seen there that the first half-sheet 1a, starting from the fluid inlet opening 2c, is provided with a first step 8a and a second step 8b in the direction of the second half-sheet 1b. Starting from the fluid inlet opening 2c, the second half-sheet 1b is provided in the region of the first step 8a with a third step 8c in the direction of the first half-sheet 1a and in the region of the second step 8b with a fourth step 8c, which is directed away from the first half-sheet 1a. In a region between the first step 8a and the second step 8b, the first half-sheet 1a has elongated, three-dimensional first embossed structures 9a which are aligned parallel to one another and are curved in the direction of the second half-sheet 1b.The second half-sheet 1b has, in a region between the third step 8c and the fourth step 8d, elongated, three-dimensional second embossed structures 9b aligned parallel to one another, which are curved in the direction of the first half-sheet 1a, are arranged in alignment with the first embossed structures 9a, and are supported against the first embossed structures 9a. The first half-sheet 1a has a first sealing region 6a in the form of a flat gasket, which is formed in the region of the first embossed structures 9a on the side of the first half-sheet 1a facing away from the second half-sheet 1b and is arranged to run transversely to the first embossed structures 9a and to coincide with them. The first embossed structures 9a are accordingly filled with sealing compound and stiffened.
[0039] The second half-sheet 1b has a second sealing region 6b with two parallel sealing beads 10a, 10b, which are arranged in the region of the second embossed structures 9b on the side of the second half-sheet 1b facing away from the first half-sheet 1a, extending transversely to the second embossed structures 9b and overlapping them. The second embossed structures 9b are therefore also filled with sealing compound and stiffened.
[0040] The first sealing region 6a and the second sealing region 6b lie congruently one above the other when viewed perpendicular to a plane spanned by the bipolar plate 1 and thus run parallel on side A and side B of the bipolar plate 1. The second half-sheet 1b has an opening slot 11 which is arranged between the fourth step 8d and the adjacent distributor field 5, wherein three-dimensional third embossed structures 9c are present which are curved in the direction of the first half-sheet 1a. The third embossed structures 9c are arranged in alignment with the second embossed structures 9b in a fluid flow direction S and are supported against the first half-sheet 1a. The opening slot 11 is arranged such that the third embossed structures 9c arranged in the second half-sheet 1b are intersected by the latter.Accordingly, during the formation of the opening slot 11, a part of the second half-sheet 1 b was cut out, which contained a part of the previously formed third embossed structures 9 c.
[0041] Figure 3 shows a plan view of the section of the bipolar plate 1 according to Figure 2. The same reference numerals as in Figure 2 identify the same elements.
[0042] Figure 4 shows a side view of the section of the bipolar plate 1 according to Figure 2, viewed from the side of the fluid inlet opening 2c. The same reference numerals as in Figure 2 indicate the same elements. The first embossed structures 9a and the second embossed structures 9b are clearly visible. These support one another and form a flow channel for a fluid between the two half-sheets 1a, 1b. The flow channel runs toward the opening slot 11.
[0043] Figure 5 shows a side view of the section of the bipolar plate 1 according to Figure 2, seen from the side of the distribution panel 5. The same reference numerals as in Figure 2 indicate the same elements. The third embossed structures 9c and the opening slot 11, which allows a fluid to flow between the two half-sheets 1a, 1b, are clearly visible.
[0044] Figure 6 shows a three-dimensional view of the section of the bipolar plate 1 according to Figure 2, without depicting the seal 6' or the second sealing region 6b. In the second half-plate 1b, the elongated second embossed structures 9b and the third embossed structures 9c can be seen, which are arranged one behind the other in alignment in the fluid flow direction S. The first embossed structures 9a in the first half-sheet 1a are not visible here. The same reference numerals as in Figure 2 identify the same elements.
[0045] Figure 7 shows a three-dimensional view of the section of the bipolar plate 1 according to Figure 2 with the seal 6' or the second sealing section 6b. The first embossed structures 9a in the first half-sheet 1a and the third embossed structures 9c in the second half-sheet 1b can be seen here. The second embossed structures 9b in the second half-sheet 1b are not visible here and are covered by the seal 6'. The same reference numerals as in Figure 2 identify the same elements.
[0046] Figure 8 shows a cross-section III-IH' through the bipolar plate 1 from Figure 1 in the region of a fluid outlet opening 2d for unused fuel. In a transition region 7 between the fluid outlet opening 2d and the adjacent distributor field 3, the first half-sheet 1a has, starting from the fluid outlet opening 2d, a third step 8c' and a fourth step 8d' in the direction of the second half-sheet 1b. Starting from the fluid outlet opening 2d in the region of the third step 8c' in the first half-sheet 1a, the second half-sheet 1b is provided with a first step 8a' in the direction of the first half-sheet 1a and, in the region of the fourth step 8d' in the first half-sheet 1a, is provided with a second step 8b' which is directed away from the first half-sheet 1a.The first half-sheet 1a has, in a region between its third step 8c' and its fourth step 8d', elongated, three-dimensional further first embossed structures 9a', which are aligned parallel to one another and curved in the direction of the second half-sheet 1b. The second half-sheet 1b has, in a region between its first step 8a' and its second step 8b', elongated, three-dimensional further second embossed structures 9b', which are aligned parallel to one another and curved in the direction of the first half-sheet 1a, are aligned in alignment with the further first embossed structures 9a', and are supported against the further first embossed structures 9a'.The first half-sheet 1a has a third sealing region 6c, which is formed in the region of the further first embossed structures 9a' on the side of the first half-sheet 1a facing away from the second half-sheet 1b and is arranged to run transversely to the further first embossed structures 9a' and to coincide with them. The further first embossed structures 9a' are therefore filled with sealing compound and stiffened. The second half-sheet 1b has a fourth sealing region 6d, which is arranged in the region of the further second embossed structures 9b' on the side of the second half-sheet 1b facing away from the first half-sheet 1a, to run transversely to the further second embossed structures 9b' and to fill them. The further second embossed structures 9b' are therefore filled with sealing compound and stiffened.
[0047] The third sealing area 6c in the form of a flat seal and the fourth sealing area 6d comprising two sealing beads 10a, 10b running parallel to one another run congruently one above the other when viewed perpendicular to a plane spanned by the bipolar plate 1 and thus run parallel on side A and side B of the bipolar plate 1.
[0048] The second half-sheet 1b has a further opening slot 11', which is arranged between its second step 8b' and the adjacent distribution field 3, wherein three-dimensional further third embossed structures 9c' are present, which are curved in the direction of the first half-sheet 1a. The further second embossed structures 9b' and the further third embossed structures 9c' are arranged in alignment in a fluid flow direction S and are supported against the first half-sheet 1a. The further opening slot 11' is arranged such that the further third embossed structures 9c' arranged in the second half-sheet 1b are intersected by the latter.
[0049] Accordingly, during the formation of the further opening slot 11', a part of the second half-sheet 1b was cut out, which contained a part of the previously formed further third embossed structures 9c'.
[0050] On side B of the bipolar plate 1, as described above and shown in Figures 2 and 8, there are the inlet and outlet for the fuel gas, in particular in the form of hydrogen.
[0051] Also on side A of the bipolar plate 1 according to Figure 1 there is an arrangement for the inlet and outlet of a fluid in the form of an oxidizing agent, such as in particular in the form of air or oxygen. The oxidizing agent flows via the fluid inlet opening 2a onto side A of the bipolar plate 1 and thus via an arrangement analogous to that in the transition region 7 on side B of the bipolar plate 1 via an opening slot in the first half-plate 1a into a distribution field, onto the active field, into another distribution field and another opening slot in the first half-plate 1a in the direction of the fluid outlet opening 2b. For the arrangement in the transition region on side A of the bipolar plate 1, simply use the designation of the half-plates in reverse. The basic design for the inlet and outlet of the oxidizing agent corresponds to that for the inlet and outlet of the fuel on side B of the bipolar plate 1.
[0052] The fluid inlet opening 2e (see Figure 1) is configured for supplying coolant into a fluid conduction path or flow space (not shown in detail) between the two half-plates 1a, 1b of the bipolar plate 1. The coolant flows along the rectangular bipolar plate 1 and into the fluid outlet opening 2f, with the geometry of the fluid conduction path being defined by the two structured half-plates 1a, 1b. The area between the fluid outlet opening 2f at the transition into the fluid conduction path between the half-plates 1a, 1b is not subject to any design specifications and can be configured as desired.
[0053] The geometric design of the fluid passage openings 2, the distribution fields 3, 5 and the active field 4 can be varied within wide limits and do not have to be designed as shown in Figures 1 to 8.
[0054] Figure 9 shows a schematic three-dimensional representation of a stacked arrangement 20 of several electrochemical cells 12. An electrochemical cell 12 comprises several bipolar plates 1, 1' and, arranged between two bipolar plates 1, 1', a membrane electrode unit 13, each of which is covered on both sides with a fluid transport layer (not shown separately here). For the sake of clarity, the distribution fields between the fluid passage openings 2 and the active field 4 have also been omitted. The cross-section of the fluid passage openings 2 is circular here, in contrast to Figure 1. List of reference symbols
[0055] I , r bipolar plate
[0056] 1a, 1b half sheet
[0057] 2 Fluid passage opening
[0058] 2a, 2c, 2e fluid inlet opening
[0059] 2b, 2d, 2f fluid outlet opening
[0060] 3 first distribution panel
[0061] 4 Active field
[0062] 5 second distribution panel
[0063] 6, 6' seal
[0064] 6a first sealing area
[0065] 6b second sealing area
[0066] 6c third sealing area
[0067] 6d fourth sealing area
[0068] 7 Transition area
[0069] 8a, 8a' first stage
[0070] 8b, 8b' second stage
[0071] 8c, 8c' third stage
[0072] 8d, 8d' fourth stage
[0073] 9a, 9a' first embossed structures
[0074] 9b, 9b' second embossed structures
[0075] 9c, 9c' third embossed structures
[0076] 10a, 10b sealing bead
[0077] II , 11 ' opening slot
[0078] 12 electrochemical cell
[0079] 13 Membrane electrode assembly
[0080] 20 Stacking arrangement
[0081] A first side of the bipolar plate
[0082] B second side of the bipolar plate
[0083] S Fluid flow direction
Claims
Patent claims 1. Bipolar plate (1), comprising a first half-sheet (1a) and a second half-sheet (1b), which are firmly connected to one another, wherein the bipolar plate (1) has a plurality of fluid passage openings (2) comprising fluid inlet openings (2a, 2c, 2e) and fluid outlet openings (2b, 2d, 2f), wherein a first distribution field (3) for distributing a fluid, an active field (4) and a second distribution field (5) for distributing the fluid are arranged on both sides of the bipolar plate (1), and with at least one seal (6, 6') on each side of the bipolar plate (1), wherein in at least one transition region (7) between a fluid passage opening (2) and an adjacent distribution field (3, 5) - the first half-sheet (1a) is provided with a first step (8a) and a second step (8b) in the direction of the second half-sheet (1b), starting from a fluid inlet opening (2a, 2c, 2e), - the second half-sheet (1b) is provided, starting from the fluid inlet opening (2a, 2c, 2e), in the region of the first step (8a) with a third step (8c) in the direction of the first half-sheet (1a) and is provided in the region of the second step (8b) with a fourth step (8c) which is directed away from the first half-sheet (1a), - the first half-sheet (1a) has, in a region between the first step (8a) and the second step (8b), elongated three-dimensional first embossed structures (9a) aligned parallel to one another, which are curved in the direction of the second half-sheet (1b), -the second half-sheet (1b) has, in a region between the third step (8c) and the fourth step (8d), elongated three-dimensional second embossed structures (9b) aligned parallel to one another, which are curved in the direction of the first half-sheet (1a), are arranged in alignment with the first embossed structures (9a) and are supported against the first embossed structures (9a), - the first half-sheet (1a) has a first sealing region (6a) which is formed in the region of the first embossed structures (9a) on the side of the first half-sheet (1a) facing away from the second half-sheet (1b) and is arranged transversely to the first embossed structures (9a) and extending therefrom, - the second half-sheet (1 b) has a second sealing region (6 b) which, in the region of the second embossed structures (9 b), is arranged on the side of the second half-sheet (1 b) facing away from the first half-sheet (1 a) transversely to the second embossed structures (9b) and arranged to extend downwards, wherein the first sealing region (6a) and the second sealing region (6b) are arranged congruently one above the other, viewed perpendicular to a plane spanned by the bipolar plate (1), and - the second half-sheet (1 b) has an opening slot (11 ) which is arranged between the fourth step (8d) and the adjacent distributor field (5), wherein three-dimensional third embossed structures (9c) are present which are curved in the direction of the first half-sheet (1a), are arranged in alignment with the second embossed structures (9b) in a fluid flow direction (S) and are supported against the first half-sheet (1a), wherein the opening slot (11 ) is arranged such that the third embossed structures (9c) arranged in the second half-sheet (1 b) are intersected by the latter.
2. Bipolar plate (1) according to claim 1, wherein in at least one transition region (7) between a fluid passage opening (2) and an adjacent distribution field (3, 5) - the first half-sheet (1a) is provided with a third step (8c') and a fourth step (8d') in the direction of the second half-sheet (1b), starting from a fluid outlet opening (2b, 2d, 2f), - the second half-sheet (1 b) is provided, starting from the fluid outlet opening (2b, 2d, 2f), in the region of the third step (8c') in the first half-sheet (1a), with a first step (8a') in the direction of the first half-sheet (1a), and is provided, in the region of the fourth step (8d') in the first half-sheet (1a), with a second step (8b') which is directed away from the first half-sheet (1a), - the first half-sheet (1a) has, in a region between its third stage (8c') and its fourth stage (8d'), elongated three-dimensional further first embossed structures (9a') aligned parallel to one another, which are curved in the direction of the second half-sheet (1b), -the second half-sheet (1b) has, in a region between its first step (8a') and its second step (8b'), elongated three-dimensional further second embossed structures (9b') aligned parallel to one another, which are curved in the direction of the first half-sheet (1a), are arranged in alignment with the further first embossed structures (9a') and are supported against the further first embossed structures (9a'), - the first half-sheet (1a) has a third sealing region (6c) which is formed in the region of the further first embossed structures (9a') on the side of the first half-sheet (1a) facing away from the second half-sheet (1b) and is arranged transversely to the further first embossed structures (9a') and extending therefrom, - the second half-sheet (1 b) has a fourth sealing region (6d) which is arranged in the region of the further second embossed structures (9b') on the side of the second half-sheet (1 b) facing away from the first half-sheet (1 a), extending transversely to the further second embossed structures (9b') and sloping therefrom, wherein the third sealing region (6c) and the fourth sealing region (6d) are arranged congruently one above the other when viewed perpendicular to a plane spanned by the bipolar plate (1 ), and - the second half-sheet (1 b) has a further opening slot (11 ') which is arranged between its second step (8 b') and the adjacent distributor field (3), wherein three-dimensional further third embossed structures (9 c') are present which are curved in the direction of the first half-sheet (1 a), are arranged in alignment with the further second embossed structures (9 b') in a fluid flow direction (S) and are supported against the first half-sheet (1 a), wherein the further opening slot (11 ') is arranged such that the further third embossed structures (9 c') arranged in the second half-sheet (1 b) are intersected by the latter.
3. Bipolar plate (1) according to claim 1 or claim 2, wherein the first sealing region (6a) and the third sealing region (6c) are each designed as flat seals.
4. Bipolar plate (1) according to one of claims 1 to 3, wherein the second sealing region (6b) and the fourth sealing region (6d) each have two parallel sealing beads (10a, 10b).
5. Bipolar plate (1) according to one of claims 1 to 4, wherein the first embossed structures (9a, 9a') and the second embossed structures (9b, 9b') are aligned with their longitudinal axes in the direction of a fluid flow direction (S) between the fluid passage opening (2) and the adjacent distributor field (3, 5).
6. Bipolar plate (1) according to one of claims 1 to 5, wherein a first fluid inlet opening (2a) for supplying and a first fluid outlet opening (2b) for discharging oxidizing gas is arranged on a first side (A) of the bipolar plate (1).
7. Bipolar plate (1) according to one of claims 1 to 6, wherein a second fluid inlet opening (2c) for supplying and a second fluid outlet opening (2d) for discharging fuel gas is arranged on a second side (B) of the bipolar plate (1).
8. Bipolar plate (1) according to one of claims 1 to 7, wherein each half-sheet (1 a, 1 b) is three-dimensionally structured in the region of the first distribution field (3), the active field (4) and the second distribution field (5) to form fluid conduction paths.
9. Bipolar plate (1) according to one of claims 1 to 8, wherein a fluid guide path for a coolant is formed between the first half-sheet (1 a) and the second half-sheet (1 b).
10. Electrochemical cell (12), comprising a plurality of bipolar plates (1, 1') according to one of claims 1 to 9 and a membrane electrode unit (13) arranged between each of the two bipolar plates (1, 1'), each membrane electrode unit being coated on both sides with a fluid transport layer.