Bipolar plate and electrochemical cell

Abstract

The invention relates to: a bipolar plate (1); and an electrochemical cell (12) comprising a plurality of such bipolar plates (1, 1 '). The bipolar plate (1) comprises a first half plate (1a) and a second half plate (1b) which are fixedly connected with each other, the bipolar plate (1) is provided with a plurality of fluid channel openings (2), and the fluid channel openings comprise fluid inlet openings (2a, 2c and 2e) and fluid outlet openings (2b, 2d and 2f); on both sides of the bipolar plate (1) there are a first distributor field (3) for distributing the fluid, an active field (4) and a second distributor field (5) for distributing the fluid. At least one seal (6, 6 ') is also present on each side of the bipolar plate (1), the seals (6, 6') being positioned one above the other in at least one transition region (7) between the fluid channel opening (2) and the adjacent distributor field (3, 5) as seen perpendicularly to the plane of expansion of the bipolar plate (1) and being reinforced by embossing structures (9a, 9b).

Description

Technical Field

[0001] The present invention relates to a bipolar plate, which includes a first half plate and a second half plate fixedly connected to each other, wherein the bipolar plate has a plurality of fluid channel openings, the plurality of fluid channel openings including a fluid inlet opening and a fluid outlet opening, and a first distributor field for distributing fluid, an effective field and a second distributor field for distributing fluid are arranged on both sides of the bipolar plate, and at least one seal is provided on each side of the bipolar plate, and a transition area is formed between the fluid channel opening and the adjacent distributor field. Background Art

[0002] DE 10 2014 225 160 A1 describes a metal separator, i.e. a bipolar plate, for a fuel cell stack having an anode separator and a cathode separator. Specifically, DE 10 2014 225 160 A1 describes an embodiment of a transition region, which is formed in the metal separator between the fluid channel opening and the active region (not shown in detail) in which the electrochemical reaction occurs. The metal separator has seals on both sides, wherein the seals are arranged offset from each other. Support elements embossed into the separator are also arranged at the inlet and outlet of the metal separator and form passages for the fluid used to operate the fuel cell stack.

[0003] CN208722997 U discloses a bipolar plate for a fuel cell having an anode plate and a cathode plate and a design thereof in a transition area between a fluid channel opening and a reaction area where an electrochemical reaction occurs. The seals arranged on the two sides of the bipolar plate are offset from each other and are each arranged in an elongated recess or flange.

[0004] DE 10 2020 202 075 A1 describes an electrochemical cell with a supply device or bipolar plate, which comprises a first circuit board and a second circuit board for supplying a working medium from a fluid channel opening, referred to here as a port connection, into a supply region. The circuit boards are designed with flanges for accommodating seals arranged offset from one another. Summary of the invention

[0005] The object of the invention is to optimize a bipolar plate of the aforementioned type with respect to the pressure losses that occur and the sealing effect of the seal in the transition region. Another object of the invention is to provide an electrochemical cell having a bipolar plate that is improved in this way.

[0006] The object is achieved by a bipolar plate comprising a first half plate and a second half plate fixedly connected to each other, wherein the bipolar plate has a plurality of fluid channel openings, the plurality of fluid channel openings comprising a fluid inlet opening and a fluid outlet opening, wherein a first distributor field for distributing a fluid, an effective field and a second distributor field for distributing a fluid are arranged on both sides of the bipolar plate, and at least one seal is provided on each side of the bipolar plate, and in at least one transition area between a fluid channel opening and an adjacent distributor field,

[0007] the first plate half is provided with a first step and a second step starting from the fluid inlet opening in the direction of the second plate half,

[0008] the second plate half is provided with a third step in the region of the first step in the direction of the first plate half, starting from the fluid inlet opening, and with a fourth step directed away from the first plate half in the region of the second step,

[0009] the first plate half has, in the region between the first step and the second step, first elongated three-dimensional embossed structures which are oriented parallel to one another and are bent in the direction of the second plate half,

[0010] the second plate half has, in the region between the third step and the fourth step, an elongated three-dimensional second embossed structure, which is oriented parallel to one another and is bent in the direction of the first plate half, and is arranged in alignment with the first embossed structure and bears against it,

[0011] the first plate half has a first sealing area which is formed on the side of the first plate half facing away from the second plate half in the region of the first embossed structure and is arranged to extend transversely to the first embossed structure and to fill the first embossed structure,

[0012] the second plate half has a second sealing area which is arranged on the side of the second plate half facing away from the first plate half in the region of the second embossed structure so as to extend transversely to the second embossed structure and fill the second embossed structure, the first sealing area and the second sealing area being arranged one above the other in a superimposed manner when viewed perpendicularly to the plane in which the bipolar plate is developed, and

[0013] -The second half plate has an open groove, which is arranged between the fourth step portion and the adjacent distributor field. There is a three-dimensional third embossed structure, which is bent toward the first half plate and arranged to be aligned with the second embossed structure in the direction of fluid flow and supported against the first half plate, and the open groove is arranged so that the third embossed structure arranged in the second half plate intersects with the open groove.

[0014] Since the seals on the two half plates extend in a superimposed manner one above the other in the transition area between the distributor field and the fluid channel opening, and in addition, the first embossed structure and the second embossed structure are filled and reinforced with sealing material, the sealing effect of the components adjacent to the bipolar plate in the area of ​​the fluid channel opening is significantly improved. The term "superimposed" means that when viewed perpendicularly to the plane in which the bipolar plate is unfolded, the center lines of the first sealing area and the second sealing area are positioned one above the other. However, the widths of the first sealing area and the second sealing area may be slightly different. Therefore, a battery stack of an electrochemical cell can be constructed by limited compression of the seal. Due to the introduction of the first and second embossed structures and the improved support of the half plates, the sealing material can also be applied more accurately to the half plates in the transition area. The distance between the first half plate and the second half plate is so large due to the first embossed structure and the second embossed structure that the flow can be guided with little pressure loss.

[0015] It has proven useful if, in at least one transition region between a fluid channel opening and an adjacent distributor field,

[0016] the first plate half is provided with a third step and a fourth step starting from the fluid outlet opening in the direction of the second plate half,

[0017] the second plate half is provided with a first step in the direction of the first plate half in the region of the third step in the first plate half, starting from the fluid outlet opening, and a second step directed away from the first plate half in the region of the fourth step in the first plate half,

[0018] the first plate half has, in the region between its third step and its fourth step, further elongated three-dimensional first embossed structures which are oriented parallel to one another and are bent in the direction of the second plate half,

[0019] the second plate half has, in the region between its first step and its second step, elongated three-dimensional further second embossed structures, which are oriented parallel to one another and are bent in the direction of the first plate half and are arranged in alignment with and bear against the further first embossed structures,

[0020] the first plate half has a third sealing area which is formed on the side of the first plate half facing away from the second plate half in the region of the further first embossed structure and is arranged to extend transversely to the further first embossed structure and to fill the further first embossed structure,

[0021] the second plate half has a fourth sealing area which is arranged on the side of the second plate half facing away from the first plate half in the region of the further second embossed structure so as to extend transversely to and fill the further second embossed structure, and the third sealing area and the fourth sealing area are arranged one above the other in a superimposed manner when viewed perpendicularly to the plane in which the bipolar plate is developed, and

[0022] -The second half plate has another open groove arranged between its second step portion and the adjacent distributor field, and there is a three-dimensional additional third embossed structure, which is bent toward the first half plate and arranged to be aligned with the additional second embossed structure in the direction of fluid flow and supported against the first half plate, and the other open groove is arranged so that the additional third embossed structure arranged in the second half plate intersects with the other open groove.

[0023] The advantages of this arrangement in the region of the fluid outlet opening are similar to those of the fluid inlet opening described above. In this case, "overlapping" also means that the center lines of the third and fourth sealing regions are positioned one above the other when viewed perpendicularly to the plane in which the bipolar plates are unfolded. However, the widths of the third and fourth sealing regions may differ slightly.

[0024] In the transition region between the distributor field and the fluid channel opening, there is an open slot on each side of the bipolar plate, through which the fluid is guided from the fluid inlet opening via the open slot toward the distributor field and the effective field. In addition, in the transition region between the distributor field and the fluid channel opening located on the same side of the bipolar plate, there is another open slot, through which the fluid from the effective field is guided via another distributor field toward the fluid outlet opening. The oxidant is supplied to the effective field on the first side of the bipolar plate, and the fuel is supplied to the other effective field on the opposite second side of the bipolar plate.

[0025] It has proven to be particularly effective if the first and third sealing areas are each designed as flat seals. On the other hand, the second and fourth sealing areas preferably each have two parallel sealing protrusions. This improves the tightness of the seal and optimizes the compression of the seals of the stacked bipolar plates when building the battery stack.

[0026] The first embossed structure and the second embossed structure are preferably oriented between the fluid channel opening and the adjacent distributor field with their longitudinal axes in the direction of the fluid flow direction. The first embossed structure and the second embossed structure are preferably extended in a straight line and have a constant width and length so that the first embossed structure and the second embossed structure optimally support each other.

[0027] Preferably, a first fluid inlet opening for supplying oxidizing gas and a first fluid outlet opening for discharging oxidizing gas are configured on the first side of the bipolar plate. Preferably, a second fluid inlet opening for supplying fuel gas and a second fluid outlet opening for discharging fuel gas are configured on the second side of the bipolar plate.

[0028] In particular, each half of the bipolar plate is three-dimensionally structured in the region of the first distributor field, the active field and the second distributor field to form a fluid guide path. This structuring is particularly achieved by embossing the half-plate. The structuring can be achieved by forming passages, locally defined protrusions or recesses, etc.

[0029] Preferably, a fluid guide path for a coolant is formed between the first half plate and the second half plate of the bipolar plate. The coolant is fed via the fluid inlet opening. The fluid outlet opening is used to discharge the coolant.

[0030] The object is also achieved by an electrochemical cell comprising a plurality of bipolar plates according to the invention and a membrane electrode unit arranged in each case between two bipolar plates, the membrane electrode unit being covered in each case on both sides by a fluid-transporting layer.

[0031] The electrochemical cell is preferably an electrolysis cell for electrolyzing water or a polymer electrolyte fuel cell for decomposing water into hydrogen as fuel and oxygen as oxidizing gas.

[0032] In electrolysis cells, fluid transport layers are also called porous transport layers or PTLs for short. In fuel cells, fluid transport layers are often called gas diffusion layers or GDLs for short.

[0033] It is also possible to form a stacked arrangement comprising a plurality of fuel cells or electrolysis cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figures 1 to 9 The invention is intended to be explained by way of example. In the accompanying drawings:

[0035] Figure 1 The bipolar plate is shown in plan view from one side;

[0036] Figure 2 The flow through the fluid inlet opening is shown in the region of the fluid inlet opening. Figure 1 Cross section II-II' of the bipolar plate;

[0037] Figure 3 Shown according to Figure 2 A plan view of a cross section of a bipolar plate;

[0038] Figure 4The diagram shows the flow of fluid from the side of the inlet opening. Figure 2 a side view of a cross section of a bipolar plate;

[0039] Figure 5 shows the distribution field as viewed from the side according to Figure 2 a side view of a cross section of a bipolar plate;

[0040] Figure 6 Shown according to Figure 2 A three-dimensional view of a cross section of a bipolar plate, wherein the seal 6' is not shown;

[0041] Figure 7 The seal 6' is shown according to Figure 2 A three-dimensional view of a cross section of a bipolar plate;

[0042] Figure 8 The flow through the fluid outlet opening is shown in the region of the fluid outlet opening. Figure 1 Cross section III-III' of the bipolar plate;

[0043] Fig. 9 A three-dimensional schematic diagram showing a stacked arrangement of electrochemical cells. DETAILED DESCRIPTION

[0044] Figure 1 The rectangular bipolar plate 1 is shown in a plan view from one side B. The bipolar plate 1 comprises a first half plate 1a and a second half plate 1b (see Figure 2 ), the first half plate and the second half plate are fixedly connected to each other, for example, by welding, adhesive bonding, etc. The bipolar plate 1 also includes a plurality of fluid channel openings 2, which are arranged at two ends of the rectangular bipolar plate 1. The fluid channel openings 2 include fluid inlet openings 2a, 2c, 2e and fluid outlet openings 2b, 2d, 2f. There are a first distributor field 3 for distributing the fluid, an effective field 4, and a second distributor field 5 for distributing the fluid between the fluid channel openings 2. This arrangement of the fluid channel openings 2, the distributor fields 3, 5, and the effective field 4 is also aligned 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 ), for greater clarity the outline of the at least one seal is indicated here as a dashed line. The seal 6, 6' extends around the periphery of each half-plate 1a, 1b and also around each of the fluid passage openings 2.

[0045] The section II-II' is arranged in the transition region 7 between the fluid inlet opening 2c for the fuel and the adjacent distributor field 5 and is Figure 2 Shown in.

[0046] As can be seen from the figure, the first half plate 1a is provided with a first step 8a and a second step 8b in the direction of the second half plate 1b starting from the fluid inlet opening 2c. The second half plate 1b is provided with a third step 8c in the direction of the first half plate 1a starting from the fluid inlet opening 2c, and a fourth step 8c oriented away from the first half plate 1a is provided in the region of the first step 8a, and in the region of the second step 8b. In the region between the first step 8a and the second step 8b, the first half plate 1a has an elongated three-dimensional first embossed structure 9a, which is oriented parallel to each other and is bent in the direction of the second half plate 1b. In the region between the third step 8c and the fourth step 8d, the second half plate 1b has an elongated three-dimensional second embossed structure 9b, which is oriented parallel to each other, is bent in the direction of the first half plate 1a, and is arranged to align with and bear against the first embossed structure 9a. The first half plate 1a has a first sealing area 6a in the form of a flat seal, which is formed on the side of the first half plate 1a facing away from the second half plate 1b in the region of the first embossed structure 9a and is arranged to extend transversely to the first embossed structure 9a and fill it. The first embossed structure 9a is accordingly filled with a sealing compound and reinforced.

[0047] The second half plate 1b has a second sealing area 6b, which has two parallel sealing protrusions 10a, 10b and is arranged on the side of the second half plate 1b facing away from the first half plate 1a in the area of ​​the second embossed structure 9b so as to extend transversely to the second embossed structure 9b and fill it. The second embossed structure 9b is also filled with a sealing compound and reinforced accordingly.

[0048] When viewed perpendicularly to the plane in which the bipolar plate 1 is laid out, the first sealing area 6 a and the second sealing area 6 b are positioned one above the other and thus extend in parallel on the side A and the side B of the bipolar plate 1 .

[0049] The second half plate 1b has an open slot 11 arranged between the fourth step 8d and the adjacent distributor field 5, and there is a three-dimensional third embossed structure 9c bent in the direction of the first half plate 1a. The third embossed structure 9c is arranged to be aligned with the second embossed structure 9b in the fluid flow direction S and bear against the first half plate 1a. The open slot 11 is arranged so that the third embossed structure 9c arranged in the second half plate 1b intersects with the open slot. Therefore, during the formation of the open slot 11, a part of the second half plate 1b is separated, and the part includes a part of the previously formed third embossed structure 9c.

[0050] Figure 3 Shown according to Figure 2 A plan view of a cross section of a bipolar plate 1. Figure 2 The same reference numerals throughout the drawings indicate the same elements.

[0051] Figure 4 The diagram shows the fluid inlet opening 2c as viewed from the side. Figure 2 A side view of a cross section of a bipolar plate 1. Figure 2 Reference numerals with the same reference numerals in the figures indicate the same elements. Now it is clear to see the first embossed structure 9a and the second embossed structure 9b, which support each other and form a flow path for the fluid between the two half-plates 1a, 1b. The flow path extends towards the open slot 11.

[0052] Figure 5 The diagram shows the distribution field 5 as viewed from the side. Figure 2 A side view of a cross section of a bipolar plate 1. Figure 2 Reference numerals which are identical to those in the Figures 1 and 2 indicate identical elements. The third embossed structure 9c and the open slots 11 which allow a fluid to flow between the two half-plates 1a, 1b can now be clearly seen.

[0053] Figure 6 Shown according to Figure 2 3D view of a cross section of a bipolar plate 1 without the seal 6' or the second sealing area 6b. In the second half of the plate 1b, the elongated second embossed structure 9b and the third embossed structure 9c can be seen, which are arranged one after the other in alignment in the fluid flow direction S. The first embossed structure 9a in the first half of the plate 1a is not visible here. Figure 2 The same reference numerals throughout the drawings indicate the same elements.

[0054] Figure 7 Shown according to Figure 2 3D view of a cross section of a bipolar plate 1 with a seal 6' or second seal portion 6b. Here the first embossed structure 9a in the first half of the plate 1a and the third embossed structure 9c in the second half of the plate 1b can be seen. The second embossed structure 9b in the second half of the plate 1b is not visible here and is covered by the seal 6'. Figure 2 The same reference numerals throughout the drawings indicate the same elements.

[0055] Figure 8 The passage through the fluid in the region of the fluid outlet opening 2d for unused fuel is shown. Figure 1Cross-section III-III' of the bipolar plate 1. In the transition region 7 between the fluid outlet opening 2d and the adjacent distributor field 3, the first half plate 1a has a third step 8c' and a fourth step 8d' in the direction of the second half plate 1b starting from the fluid outlet opening 2d. The second half plate 1b is provided with a first step 8a' in the direction of the first half plate 1a in the region of the third step 8c' in the first half plate 1a starting from the fluid outlet opening 2d, and a second step 8b' oriented away from the first half plate 1a is provided in the region of the fourth step 8d' in the first half plate 1a. The first half plate 1a has an elongated three-dimensional additional first embossed structure 9a' in the region between its third step 8c' and its fourth step 8d', which are oriented parallel to each other and bent in the direction of the second half plate 1b. The second half plate 1b has, in the region between its first step 8a' and its second step 8b', elongated three-dimensional further second embossed structures 9b', which are oriented parallel to one another and are bent in the direction of the first half plate 1a, arranged to be aligned with and bear against the further first embossed structures 9a'. The first half plate 1a has a third sealing region 6c, which is formed on the side of the first half plate 1a facing away from the second half plate 1b in the region of the further first embossed structures 9a' and is arranged to extend transversely to and fill the further first embossed structures 9a'. The further first embossed structures 9a' are accordingly filled with a sealing compound and reinforced.

[0056] The second plate half 1b has a fourth sealing area 6d, which is arranged on the side of the second plate half 1b facing away from the first plate half 1a in the region of the further second embossed structure 9b' so as to extend transversely to the further second embossed structure 9b' and fill the further second embossed structure. The further second embossed structure 9b' is accordingly filled with a sealing compound and reinforced.

[0057] When viewed perpendicularly to the plane in which the bipolar plate 1 is unfolded, the third sealing area 6c in the form of a flat seal and the fourth sealing area 6d comprising two sealing protrusions 10a, 10b extending parallel to each other extend in a manner overlapping one another and thereby extend in parallel on side A and side B of the bipolar plate 1.

[0058] The second half plate 1b has another open slot 11' arranged between its second step 8b' and the adjacent distributor field 3, and there is a three-dimensional further third embossed structure 9c', which is bent in the direction of the first half plate 1a. The further second embossed structure 9b' and the further third embossed structure 9c' are arranged to align and bear against the first half plate 1a in the fluid flow direction S. The further open slot 11' is arranged so that the further third embossed structure 9c' arranged in the second half plate 1b intersects with the further open slot.

[0059] Thus, during the formation of the further opening slot 11 ′, a portion of the second half-plate 1 b is separated, said portion comprising a portion of the previously formed further third embossed structure 9 c ′.

[0060] As mentioned above and as Figure 2 and Figure 8 As shown in FIG, on the side B of the bipolar plate 1 there are inlets and outlets for the fuel gas, in particular in the form of hydrogen.

[0061] Also according to Figure 1 On the side A of the bipolar plate 1 of the bipolar plate 1, there is an arrangement of inlets and outlets for a fluid in the form of an oxidant, such as, in particular, in the form of air or oxygen. The oxidant flows to the side A of the bipolar plate 1 via the fluid inlet opening 2a and thereby flows through an arrangement similar to the arrangement in the transition region 7 on the side B of the bipolar plate 1 via the open slots in the first half plate 1a into the distributor field, into the effective field, into another distributor field, and into another open slot in the first half plate 1a in the direction of the fluid outlet opening 2b. For the arrangement in the transition region on the side A of the bipolar plate 1, it is only necessary to use the names of the half plates in reverse. The basic design of the oxidant inlet and oxidant outlet corresponds to the basic design of the fuel inlet and fuel outlet on the side B of the bipolar plate 1.

[0062] Fluid inlet opening 2e (see Figure 1 ) is designed for supplying coolant to a fluid guide 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 flows into the fluid outlet opening 2f, the geometry of the fluid guide path being predetermined by the two structured half plates 1a, 1b. At the transition, the area between the fluid outlet opening 2f and the fluid guide path between the half plates 1a, 1b is not subject to any design specifications and can be designed as required.

[0063] The geometrical design of the fluid channel openings 2, the distributor fields 3, 5 and the active field 4 can vary within wide limits and does not necessarily have to be exactly the same. Figures 1 to 8 Design as shown in .

[0064] Fig. 9 A three-dimensional schematic diagram of a stacked arrangement 20 of a plurality of electrochemical cells 12 is shown. The electrochemical cells 12 comprise a plurality of bipolar plates 1, 1' and a membrane electrode unit 13, which is arranged in each case between two bipolar plates 1, 1' and is covered on both sides with a fluid transport layer (not shown separately here). For the sake of a better overview, the distributor field between the fluid channel openings 2 and the active field 4 is also omitted. Figure 1 In contrast, the cross section of the fluid channel opening 2 is designed to be circular.

[0065] Reference numerals list

[0066] 1. 1' bipolar plate

[0067] 1a, 1b half board

[0068] 2 Fluid channel openings

[0069] 2a, 2c, 2e fluid inlet openings

[0070] 2b, 2d, 2f fluid outlet openings

[0071] 3 First distributor field

[0072] 4 Effective field

[0073] 5 Second distributor field

[0074] 6. 6' seal

[0075] 6a First sealing area

[0076] 6b Second sealing area

[0077] 6c Third sealing area

[0078] 6d Fourth sealing area

[0079] 7 Transition zone

[0080] 8a, 8a' first step

[0081] 8b, 8b' Second step

[0082] 8c, 8c' third step

[0083] 8d, 8d' Fourth step

[0084] 9a, 9a' first embossed structure

[0085] 9b, 9b' Second embossed structure

[0086] 9c, 9c' Third embossing structure

[0087] 10a, 10b sealing protrusion

[0088] 11, 11' open slot

[0089] 12 Electrochemical Cells

[0090] 13 Membrane Electrode Unit

[0091] 20 Stacking Arrangement

[0092] A. First side of the bipolar plate

[0093] B Second side of the bipolar plate

[0094] S Fluid flow direction.

Claims

1. A bipolar plate (1), comprising a first half plate (1a) and a second half plate (1b) fixedly connected to each other, wherein: The bipolar plate (1) has a plurality of fluid channel openings (2), the plurality of fluid channel openings comprising fluid inlet openings (2a, 2c, 2e) and fluid outlet openings (2b, 2d, 2f), wherein a first distributor field (3), an effective field (4) and a second distributor field (5) for distributing fluid are arranged on two sides of the bipolar plate (1), and at least one seal (6, 6') is provided on each side of the bipolar plate (1), and in at least one transition area (7) between a fluid channel opening (2) and an adjacent distributor field (3, 5), - the first half plate (1a) is provided with a first step (8a) and a second step (8b) starting from the fluid inlet opening (2a, 2c, 2e) in the direction of the second half plate (1b), - the second plate half (1b) is provided with a third step (8c) in the region of the first step (8a) in the direction of the first plate half (1a) starting from the fluid inlet opening (2a, 2c, 2e), and in the region of the second step (8b) is provided with a fourth step (8c) directed away from the first plate half (1a), - the first plate half (1a) has, in the region between the first step (8a) and the second step (8b), first elongated three-dimensional embossed structures (9a), which are oriented parallel to one another and are bent in the direction of the second plate half (1b), - the second plate half (1b) has, in the region between the third step (8c) and the fourth step (8d), an elongated three-dimensional second embossed structure (9b), which is oriented parallel to one another and is bent in the direction of the first plate half (1a), and is arranged in alignment with and bears against the first embossed structure (9a), - the first plate half (1a) has a first sealing area (6a), which is formed on the side of the first plate half (1a) facing away from the second plate half (1b) in the region of the first embossed structure (9a) and is arranged to extend transversely to the first embossed structure (9a) and to fill the first embossed structure, - the second half plate (1b) has a second sealing area (6b), which is arranged in the area of ​​the second embossed structure (9b) on the side of the second half plate (1b) facing away from the first half plate (1a) so as to extend transversely to the second embossed structure (9b) and fill the second embossed structure, and when viewed perpendicularly to the plane in which the bipolar plate (1) is unfolded, the first sealing area (6a) and the second sealing area (6b) are arranged one above the other, and -The second half plate (1b) has an open groove (11), which is arranged between the fourth step portion (8d) and the adjacent distributor field (5), and there is a three-dimensional third embossed structure (9c), which is bent toward the first half plate (1a) and arranged to be aligned with the second embossed structure (9b) in the fluid flow direction (S) and supported against the first half plate (1a), and the open groove (11) is arranged so that the third embossed structure (9c) arranged in the second half plate (1b) intersects with the open groove.

2. The bipolar plate (1) according to claim 1, wherein: In at least one transition region (7) between a fluid channel opening (2) and an adjacent distributor field (3, 5) - the first half plate (1a) is provided with a third step (8c') and a fourth step (8d') starting from the fluid outlet opening (2b, 2d, 2f) in the direction of the second half plate (1b), - the second plate half (1b) is provided with a first step (8a') in the direction of the first plate half (1a) starting from the fluid outlet opening (2b, 2d, 2f) in the region of the third step (8c') in the first plate half (1a), and a second step (8b') is provided in the region of the fourth step (8d') in the first plate half (1a) directed away from the first plate half (1a), - the first plate half (1a) has, in the region between the third step (8c') of the first plate half and the fourth step (8d') of the first plate half, an elongated three-dimensional further first embossed structure (9a'), which is oriented parallel to one another and is bent in the direction of the second plate half (1b), - the second plate half (1b) has, in the region between the first step (8a') of the second plate half and the second step (8b') of the second plate half, an elongated three-dimensional further second embossed structure (9b'), the further second embossed structures being oriented parallel to one another and bent in the direction of the first plate half (1a), arranged in alignment with the further first embossed structure (9a') and bearing against the further first embossed structure (9a'), - the first plate half (1a) has a third sealing area (6c), which is formed on the side of the first plate half (1a) facing away from the second plate half (1b) in the region of the further first embossed structure (9a') and is arranged to extend transversely to the further first embossed structure (9a') and to fill the further first embossed structure, - the second half plate (1b) has a fourth sealing area (6d), which is arranged on the side of the second half plate (1b) facing away from the first half plate (1a) in the region of the further second embossed structure (9b') so as to extend transversely to the further second embossed structure (9b') and fill the further second embossed structure, and when viewed perpendicularly to the plane in which the bipolar plate (1) is unfolded, the third sealing area (6c) and the fourth sealing area (6d) are arranged one above the other in a superimposed manner, and -The second half plate (1b) has another open groove (11') arranged between the second step portion (8b') of the second half plate and the adjacent distributor field (3), and there is a three-dimensional additional third embossed structure (9c'), which is bent toward the first half plate (1a) and arranged to be aligned with the additional second embossed structure (9b') in the fluid flow direction (S) and supported against the first half plate (1a), and the other open groove (11') is arranged so that the additional third embossed structure (9c') arranged in the second half plate (1b) intersects with the other open groove.

3. The bipolar plate (1) according to claim 1 or 2, wherein: The first sealing area (6a) and the third sealing area (6c) are each designed as a flat seal.

4. The bipolar plate (1) according to any one of claims 1 to 3, wherein: The second sealing area (6b) and the fourth sealing area (6d) each have two parallel sealing protrusions (10a, 10b).

5. The bipolar plate (1) according to any one of claims 1 to 4, wherein: The first embossed structure (9a, 9a') and the second embossed structure (9b, 9b') are oriented between the fluid channel opening (2) and the adjacent distributor field (3, 5) such that the longitudinal axes of the first embossed structure and the second embossed structure are in the direction of the fluid flow direction (S).

6. The bipolar plate (1) according to any one of claims 1 to 5, wherein: A first fluid inlet opening (2a) for supplying oxidizing gas and a first fluid outlet opening (2b) for discharging oxidizing gas are configured on the first side portion (A) of the bipolar plate (1).

7. The bipolar plate (1) according to any one of claims 1 to 6, wherein: A second fluid inlet opening (2c) for supplying fuel gas and a second fluid outlet opening (2d) for discharging fuel gas are configured on the second side (B) of the bipolar plate (1).

8. The bipolar plate (1) according to any one of claims 1 to 7, wherein: Each half-plate (1a, 1b) is three-dimensionally structured in the region of the first distributor field (3), the effective field (4) and the second distributor field (5) to form a fluid guiding path.

9. The bipolar plate (1) according to any one of claims 1 to 8, wherein: A fluid guide path for a coolant is formed between the first half plate (1a) and the second half plate (1b).

10. An electrochemical cell (12) comprising a plurality of bipolar plates (1, 1') according to any one of claims 1 to 9 and a membrane electrode unit (13), the membrane electrode unit being arranged in each case between two bipolar plates (1, 1') and the membrane electrode unit being covered on both sides with a fluid transport layer in each case.

Images