A unit fuel cell, a fuel cell stack and a bipolar plate assembly

Abstract

The present invention discloses a fuel cell stack (1), the fuel cell stack (1) comprising a plurality of bipolar plates (100), wherein each bipolar plate (100) has at least an anode plate (20) and a cathode plate, and a plurality of membrane electrode assemblies (10) clamped by the bipolar plates (100), wherein each membrane electrode assembly (10) has at least an anode (11) and a cathode (12) separated by a membrane (13), wherein the bipolar plates (100) clamp the membrane electrode assembly (10) so that the anode (11) of the membrane electrode assembly (10) faces the anode plate (20) of the first bipolar plate (100). , and the cathode (12) of the same membrane electrode assembly (10) faces the cathode plate (30) of the second bipolar plate (100); wherein the cell spacing of the fuel cell stack (1) is determined by the distance between two adjacent membrane electrode assemblies (10), wherein, at the boundary of the bipolar plates (100) of the fuel cell stack (1), the total distance (d) between the anode plate (20) of the first bipolar plate (100) and the cathode plate (30) of the second bipolar plate is equal to the cell spacing of the fuel cell stack (1), and the total distance (d) is measured on the sandwiched membrane electrode assembly (10).

Description

Technical Field

[0001] The invention relates to a unit fuel cell, a fuel cell stack and a bipolar plate assembly. Background Art

[0002] Typically, a fuel cell stack 1 comprises a plurality of unit fuel cells, or more generally, a plurality of membrane electrode assemblies (MEAs), which are separated by so-called bipolar plate assemblies. The bipolar plate assembly itself typically comprises at least two metal plates, so-called flow field plates, which are stacked on top of each other, with a flow field for reactants on one side and a flow field for a coolant on the other side. In the bipolar plate assembly, the coolant flow fields face each other, wherein the reactant fluid flow field is arranged on the outer surface of the bipolar plate assembly, which faces the MEA. During operation of the fuel cell stack, the current generated by the MEA causes a voltage potential difference to be generated between the bipolar plate assemblies. Therefore, in any case, the individual bipolar plate assemblies or unit fuel cells must be kept electrically isolated to avoid short circuits.

[0003] To achieve electrical isolation, an insulating layer, a so-called subgasket, is provided, which is arranged at or around the periphery of the membrane electrode assembly, thereby forming a membrane-electrode-subgasket assembly. The subgasket usually extends beyond the boundaries of the bipolar plate assembly to fully achieve short-circuit protection. Unfortunately, this leads to a design of the fuel cell stack with uneven side walls, which interferes with the arrangement of detectors in the fuel cell stack, for example in the housing.

[0004] However, when assembling the fuel cell stack, the bipolar plate assembly and the MEA must be precisely aligned with each other to ensure the operation of the fuel cell stack. To facilitate alignment, it is known that at each bipolar plate assembly and membrane-electrode-subgasket assembly there are at least one, preferably two, specific areas, where the geometry of the bipolar plate / membrane-electrode-subgasket assembly allows the deployment of alignment tools. Such alignment tools can be so-called guide rods or guide walls, which define the outer dimensions of the final fuel cell stack.

[0005] In order to achieve accurate alignment of the fuel cell stack elements, it is necessary that the subgasket does not extend over the boundaries of the bipolar plate assembly at least in these areas, and preferably everywhere. Unfortunately, this also means that inadequate electrical isolation occurs in these areas, making these areas at risk of short circuits, primarily due to bipolar plate bending and / or inadequate assembly. Summary of the invention

[0006] It is therefore an object of the present invention to provide a fuel cell stack having an adjustable geometry so as to eliminate electrical hazards.

[0007] This object is achieved by the fuel cell stack, unit fuel cell and bipolar plate assembly described in the embodiments provided in this application.

[0008] Hereinafter, the present invention provides a fuel cell stack, which includes a plurality of bipolar plates, each of which has at least an anode plate and a cathode plate, and a plurality of membrane electrode assemblies clamped by the bipolar plates, each of which has at least an anode and a cathode separated by a membrane, wherein the bipolar plates clamp the membrane electrode assemblies so that the anode of the membrane electrode assembly faces the anode plate of the first bipolar plate, and the cathode of the same membrane electrode assembly faces the cathode plate of the second bipolar plate. In addition, the cell pitch of the fuel cell stack is determined by the distance between two adjacent membrane electrode assemblies.

[0009] In order to provide a fuel cell stack that can reduce the risk of electrical short circuit, it is recommended that at the boundary of the bipolar plates of the fuel cell stack, the total distance between the anode plate of the first bipolar plate and the cathode plate of the second bipolar plate is equal to the cell spacing of the fuel cell stack, which total distance is measured on the membrane electrode assembly sandwiched in between.

[0010] According to a preferred embodiment, at the boundary of the bipolar plates of the fuel cell stack, the anode plate of the first bipolar plate has a first distance from the membrane electrode assembly, and the cathode plate of the second bipolar plate has a second distance from the membrane electrode assembly, wherein the first distance is different from the second distance. Therefore, any risk of short circuit can be further prevented.

[0011] According to another aspect of the present invention, this feature can also be implemented in a unit fuel cell. A unit fuel cell is generally composed of an anode and a cathode plate, which sandwich a membrane electrode assembly. Even such a unit fuel cell can be used as an independent fuel cell, and the voltage provided by such a unit fuel cell is quite small. Therefore, these unit fuel cells are stacked together to form a fuel cell stack, in which the sum of the voltages generated by each unit fuel cell is a sufficiently large voltage for most applications. Therefore, the backs of the anode and cathode plates of two unit fuel cells are in contact with each other, thereby forming a bipolar plate assembly.

[0012] The unit fuel cell or at least one unit fuel cell of the fuel cell stack has an anode and a cathode plate, wherein the anode plate and the cathode plate sandwich a membrane electrode assembly (MEA), wherein the MEA has at least an anode and a cathode, the anode and the cathode being separated by a membrane. Thus, the anode faces the anode plate and the cathode faces the cathode plate. As mentioned above, in order to avoid any short circuit, it is recommended that the anode plate has a first distance from the membrane MEA and the cathode plate has a second distance from the MEA, wherein the first and second distances are different. Therefore, it should be noted that the first and second distances are determined or measured at the same position.

[0013] Usually, the cathode and anode plates are designed identically, with the borders separated from each other for stability reasons, so that the distance between the plates and the MEA is very small. This also leads to a symmetrical layout at the MEA and identical distances to the MEA. As mentioned above, by increasing the distance to this cell spacing, the risk of short circuits can be avoided. However, this may lead to a loss of stability. Due to the different recommended distances, the risk of short circuits can be avoided even if one of the plates is bent or the assembly precision is insufficient.

[0014] The different distances have the greater advantage that at the greater distances sufficient space can be provided for the weld. This allows the anode and cathode plates of two different unit fuel cells to be conveniently joined to form a bipolar plate assembly, as will be explained in further detail below.

[0015] According to a preferred embodiment, the membrane electrode assembly of the unit fuel cell also has a subgasket, which is at least partially arranged around the anode and the cathode in an enclosing manner, and the first and second distances are determined between the anode plate and the subgasket, and between the cathode and the subgasket, respectively. Therefore, it is particularly preferred that the subgasket surrounds the anode and the cathode in a frame-like manner. This design allows good electrical isolation of the anode and the cathode of the membrane electrode assembly.

[0016] According to another preferred embodiment, the positions for determining the first and second distances and / or measurements are arranged at the borders of the unit fuel cells. The borders of the plates are very sensitive to bending, because the plates themselves are usually very thin, approximately in the range of 0.05 to 0.1 mm, and the borders are used to align the unit fuel cells, which in turn increases the risk of damaging the plates in the border area. Due to the distance of one cell spacing, the plates are more or less in contact with each other, which increases stability. In the preferred case of different distances, stability is further improved and the risk of short circuits is still avoided.

[0017] It is further preferred that the anode plate and / or cathode plate has a first region and a second region, the first region having a first structure and the second region having a second structure, wherein in the first region, the first structures of the anode plate and the cathode plate are identical channel-like structures including grooves and protrusions, and in the second region, the second structure of the anode plate is different from the second structure of the cathode plate, even if the second structure can also be provided with a channel-like structure. At least the channel-like structure of the first region forms a fluid flow field for reactants, which will be distributed in the anode and / or cathode of the membrane electrode assembly. The different designs of the first and second structures allow the optimization of fluid distribution in the first region by the first structure and on the other hand the optimization of stability in the second region by the second structure.

[0018] Therefore, it is particularly preferred that the first region is formed in the active region of the unit fuel cell and the second region is formed in the boundary region of the unit fuel cell, wherein on the anode side, the active region is defined by the extension of the anode, on the cathode side, the active region is defined by the extension of the cathode, and the boundary region is defined by the extension of the subgasket surrounding the anode and / or cathode. This maximizes the active region and increases the stability of the unit fuel cell.

[0019] Another aspect of the present invention relates to a fuel cell group, which includes at least the first and second unit fuel cells as described above, wherein the first unit fuel cell and the second unit fuel cell are stacked on each other so that the cathode plate of the first unit fuel cell faces and / or contacts the anode plate of the second unit fuel cell, thereby the cathode plate and the anode plate form the bipolar plate assembly.

[0020] The above-described new design of the anode and cathode plates provides a bipolar plate assembly in a fuel cell stack that is more stable and can be electrically isolated from any other adjacent bipolar plate assemblies in the fuel cell stack - even if the subgasket does not provide sufficient isolation, for example, due to manufacturing inaccuracies or tolerances. The new design of the bipolar plate assembly also allows for better short circuit protection between adjacent bipolar plate assemblies in the fuel cell stack because the distance between adjacent bipolar plate assemblies is increased in the second region.

[0021] Therefore, according to another aspect of the present invention, a bipolar plate assembly is preferred, which generally has a first and a second flow field plate, i.e., an anode plate and a cathode plate, each of which has a front and a back surface, wherein the back surfaces face each other. In addition, the two plates have a first region and a second region, the first region having a first structure (e.g., on the back surface), and the second region having a second structure (e.g., on the back surface). Therefore, in the first region, the first structure is a channel-like structure including grooves and protrusions, wherein the protrusions of the anode plate and the cathode plate are arranged to face and contact each other, and the grooves of the anode plate and the cathode plate are arranged to face each other, thereby forming a coolant flow field channel of the bipolar plate. In contrast, in the second region, the second structure of one of the plates (anode plate or cathode plate) is provided with a first group of protrusions and a second group of protrusions, and the second structure of the corresponding other plate is provided with grooves and protrusions, wherein the protrusions of the first group of protrusions are arranged to face and contact the protrusions of the corresponding other plate, and the protrusions of the second group of protrusions are arranged to face the grooves of the other plate. Thus, in the second region, the second set of protrusions of the anode plate are received in the recesses of the cathode plate, or vice versa, the second set of protrusions of the cathode plate are received in the recesses of the anode plate.

[0022] Thus, in the second region, the bipolar plate assembly is more stable, since the two plates support each other and are therefore stronger than just a single plate. They can therefore better withstand any bending forces. On the other hand, due to this arrangement, the total distance of two adjacent bipolar plate assemblies is increased, thereby reducing or avoiding the risk of short circuits due to contacting bipolar plates. In addition, the design allows a variety of possibilities for connecting the anode and cathode plates in the second region. In particular, the plates can be welded together, for example by ultrasonic welding. In the enlarged distance to the MEA provided by the new design, the weld seam can be accommodated so that when the bipolar plate assembly is combined with the membrane electrode assembly, the membrane electrode assembly will remain flat and will not bend or bulge on the weld seam.

[0023] According to another preferred embodiment of the fuel cell stack or the bipolar plate assembly, as described above, the second region is arranged in the outer region or border region of the anode plate and the cathode plate. As described above, in a fuel cell or a fuel cell stack, the outer regions of adjacent bipolar plate assemblies are usually separated from each other by a subgasket surrounding the membrane electrode assembly. Preferably, the subgasket should have the same extension as the bipolar plate assembly, but due to manufacturing errors or tolerances, the subgasket does not always have the same extension as the bipolar plate. Therefore, there may be areas where the bipolar plate assemblies are not sufficiently electrically isolated from each other, thereby increasing the risk of short circuits. Because this usually occurs in the outer or border region of the bipolar plate assembly, it is preferably arranged in the second region in the border region.

[0024] As also mentioned above, it is further preferred if the second region can frame the first region so that an increased distance between two adjacent bipolar plate assemblies can be provided over the entire outer region of the bipolar plate assembly.

[0025] In another preferred embodiment, the anode plate and the cathode plate have a reactant flow field on the front side, wherein each reactant flow field also has a groove and a protrusion. Therefore, the groove of the reactant flow field is formed by the protrusion of the coolant flow field, and the protrusion of the reactant flow field is formed by the groove of the coolant flow field.

[0026] Therefore, the anode / cathode plate can be manufactured by a single stamping or punching process, and the total thickness of the anode / cathode plate can be further reduced, and a single plate can be provided for the reactant flow field and the coolant flow field. This reduces the overall thickness of the bipolar plate assembly and facilitates stacking.

[0027] According to another preferred embodiment, in the first region, an active area of ​​the reactant flow field is formed on each front face of the first and second flow field plates, and in the second region, a boundary area of ​​the reactant flow field is formed. With this design, the active area of ​​the flow field plates can be adapted to the electrodes of the membrane electrode assembly, and the boundary area can be adapted to the subgasket surrounding the membrane electrode assembly. This design allows the active area to be enlarged and short circuit protection to be improved.

[0028] According to another preferred embodiment of the fuel cell stack, in the second region, the anode plate of the first bipolar plate assembly has a first distance to its respective adjacent subgasket, and the cathode plate of the second bipolar plate assembly has a second distance to its respective adjacent subgasket, wherein the first distance and the second distance are different from each other. Therefore, the sum of the first distance and the second distance corresponds to the total distance between two adjacent bipolar plate assemblies, or two anode plates to two cathode plates in the fuel cell stack. This maximizes the distance between the bipolar plate assemblies in the boundary region, thereby reducing the risk of short circuits, even if the bipolar plates are bent or the subgaskets are not fully formed or damaged. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Further preferred embodiments are defined in the description and the drawings. Therefore, elements described or shown in combination with other elements may exist alone or in combination with other elements without departing from the scope of protection.

[0030] In the following, preferred embodiments of the present invention are described with reference to the accompanying drawings, wherein the drawings are merely exemplary and are not intended to limit the scope of protection. The scope of protection is limited only by the appended claims.

[0031] The accompanying drawings show:

[0032] Figure 1 : A schematic cross-sectional view of a fuel cell stack according to the prior art;

[0033] Figure 2 : A schematic cross-sectional view of a fuel cell stack according to a preferred embodiment of the present invention; and

[0034] Figure 3 : A schematic cross-sectional view of a fuel cell stack according to another preferred embodiment of the present invention. DETAILED DESCRIPTION

[0035] In the following, identical or similar functional elements are denoted by the same reference numerals.

[0036] Figure 1 and Figure 2 A partial schematic cross section of a fuel cell stack 1 is shown respectively. The fuel cell stack 1 has a membrane electrode assembly 10 sandwiched between two bipolar plate assemblies 100-1 and 100-2. The membrane electrode assembly 10 generally includes a cathode 11 and an anode 12 separated by a membrane 13, and the cathode 11 and the anode 12 form an active area of ​​the membrane electrode assembly 10. A subgasket 14 surrounds the active area.

[0037] like Figure 1 and Figure 2As shown in , the membrane electrode assembly 10 is sandwiched between two adjacent bipolar plate assemblies 100-1 and 100-2. Each bipolar plate assembly has a first flow field plate 20 (e.g., an anode plate) and a second flow field plate 30 (e.g., a cathode plate), which are in contact with the corresponding electrodes of the membrane electrode assembly 10. Therefore, the first flow field plate 20 of the first bipolar plate assembly 100-1, the MEA 10 and the second flow field plate 30 of the second bipolar plate assembly 30 form a unit fuel cell 50. In the following, the first flow field plate 20 is regarded as the anode plate 20, and the second flow field plate 30 is regarded as the cathode plate. However, it should be noted that this can be reversed without departing from the scope of the present invention.

[0038] Each bipolar plate assembly 100-1, 100-2, or more preferably, each flow field plate 20, 30 has a coolant flow field structure on its back side 21, 31, and the coolant flow field structure is in the form of grooves 22, 32 and protrusions 23, 33. Since the two back sides 21, 31 are arranged to face each other, the coolant flow field structure forms a coolant flow field channel 40, through which the coolant can be guided to cool the bipolar plate assemblies 100-1, 100-2, thereby cooling the fuel cell stack 1.

[0039] On the front side 24, 34, i.e. on the side facing the electrode, a reactant flow field is provided, which also has grooves 25, 35 and protrusions 26, 36. In the described embodiment, the grooves 22, 32 and protrusions 23, 33 of the coolant flow field form the protrusions 26, 36 and grooves 25, 35 of the reactant flow field, respectively. This allows to simplify the manufacture of the flow field plates 20, 30, since the flow field plates 20, 30 can be manufactured by a single stamping or punching process.

[0040] Furthermore, in Figure 1 and Figure 2 It is seen that the individual reactant flow fields are separated by the membrane electrode assembly 10 and the subgasket area 14. Furthermore, they are sealed from the outside by means of sealing elements 42 arranged between the flow field plates 20, 30 and the subgasket 14.

[0041] In such Figure 1In the fuel cell stack according to the prior art shown, the anode plate 20 and the cathode plate 30 are built identically. Therefore, when the flow field plates 20, 30 are arranged so that their back faces 21, 31 face each other, all the grooves 22, 32 of the coolant flow fields of the anode plate 20 and the cathode plate 30 face each other. The disadvantage of this design is that the first distance d1 between the cathode plate 30 of the bipolar plate assembly 100-1 and the corresponding adjacent subgasket 14, and the second distance d2 between the anode plate 20 of the bipolar plate assembly 100-2 and the corresponding adjacent subgasket 14 are very small. Therefore, when the bipolar plate assemblies 100-1, 100-2 may contact each other, the risk of short circuit is high in the event that one of the bipolar plates is bent, or the subgasket 14 is damaged or missing in this area.

[0042] Reference now Figure 2 In contrast, the first and second flow field plates 20, 30 of the illustrated embodiment of the present invention are identical only in the first region I. In the second region II, the anode plate 20 has a first set of protrusions 27 and a second set of protrusions 28, while the cathode plate 30 still has protrusions 37 and grooves 38. Therefore, the second set of protrusions 28 are accommodated in the grooves 38. This in turn allows the distance d1 between the anode plate 20 of the first bipolar plate assembly 100-1 to the adjacent subgasket 14 to be increased, wherein the distance d2 between the cathode plate 30 of the second bipolar plate assembly 100-2 to the same subgasket 14 is relatively small, for example, within the same range known in the prior art. In addition, the total distance is one cell spacing, which ensures improved short circuit avoidance.

[0043] The advantage of this new design is that the border area (second area) of the bipolar plate assembly is more stable because the two plates provide more rigidity than a single plate. Typically, the width of the anode / cathode plates is about 0.075 mm, so they are very sensitive to bending or other damage.

[0044] This increased strength has the further advantage that the bipolar plate assembly can be welded very close to the outer / border areas. Due to the increased strength, opposing sides of the bipolar plate assembly can apply reaction forces without damaging the assembly (eg, bending the plates).

[0045] Preferably, the distance d1 is approximately the same as the distance to the bead seal so that the MEA remains flat when the bipolar plate assembly and the MEA are combined (stacked). If the distance d1 is not large enough, it is necessary to weld at the bottom of the flow field (ie, in the groove), thereby creating a bend in the membrane electrode assembly.

[0046] The total distance between two adjacent plates is one cell pitch, which is the maximum possible distance between two plates, thus ensuring that short circuits can be avoided.

[0047] Figure 3Another preferred embodiment of a fuel cell stack is shown, in which the distance between adjacent bipolar plate assemblies 100-1 to 100-2 is also a cell spacing. Figure 2 In contrast to the embodiment shown, the distance between the plate and the gasket does not differ, but both are equally spaced at one cell pitch, so that short circuits can also be avoided in this embodiment.

[0048] In summary, due to the new design, electrical insulation between adjacent bipolar plate assemblies 100-1, 100-2 can be ensured even in areas where the subgasket portion 14 is not large enough compared to the extension of the bipolar plate assemblies 100-1, 100-2, or in areas where the subgasket portion 14 is damaged or not fully aligned. In addition, the overall strength of the bipolar plate assembly and the fuel cell is improved.

[0049] Reference numerals

[0050] 1. Fuel cell stack;

[0051] 10 membrane electrode assembly;

[0052] 100 bipolar plate assemblies;

[0053] I first area;

[0054] II Second Area;

[0055] 11 anode;

[0056] 12 cathode;

[0057] 13 membrane;

[0058] 14 washers;

[0059] 20 first (anode) flow field plate;

[0060] 30 second (cathode) flow field plate;

[0061] 21, 31 back side of flow field plate;

[0062] 22, 32 dorsal convexity (first area);

[0063] 23, 33 back groove (first area);

[0064] 24, 34 front;

[0065] 25, 35 frontal convexity (first area);

[0066] 26, 36 front groove (first area);

[0067] 27 The first set of protrusions on the front (second area);

[0068] 28 The second set of protrusions on the front (second area);

[0069] 37 convex (second area);

[0070] 38 groove (second area);

[0071] 40 coolant flow channel;

[0072] 50 fuel cells.

Claims

1. A fuel cell stack (1) comprising: A plurality of bipolar plates (100), wherein each bipolar plate (100) has at least an anode plate (20) and a cathode plate (30), and A plurality of membrane electrode assemblies (10) sandwiched between the bipolar plates (100), wherein each membrane electrode assembly (10) has at least an anode (11) and a cathode (12) separated by a membrane (13) and a subgasket (14), wherein the subgasket (14) surrounds the anode (11) and the cathode (12) in a frame-like manner, The bipolar plates (100) clamp the membrane electrode assembly (10) so that the anode (11) of the membrane electrode assembly (10) faces the anode plate (20) of the first bipolar plate (100), and the cathode (12) of the same membrane electrode assembly (10) faces the cathode plate (30) of the second bipolar plate (100); and The cell spacing of the fuel cell stack (1) is determined by the distance between two adjacent membrane electrode assemblies (10). Features: At the boundary of the bipolar plates (100) of the fuel cell stack (1), the total distance (d) between the anode plate (20) of the first bipolar plate (100) and the cathode plate (30) of the second bipolar plate is equal to the cell spacing of the fuel cell stack (1), and the total distance (d) is measured on the membrane electrode assembly (10) sandwiched therebetween, wherein at the boundary of the bipolar plates (100) of the fuel cell stack (1), the anode plate (20) of the first bipolar plate (100) has a distance to the membrane electrode assembly (10). The invention relates to a membrane electrode assembly (10) having a first distance (d1) from a subgasket (14) of the first bipolar plate (100), and a second distance (d2) from a cathode plate (30) of the second bipolar plate (100) to the same subgasket (14) of the same membrane electrode assembly (10), so that at the boundary, the subgasket (14) of the membrane electrode assembly (10) does not contact the anode plate (20) of the first bipolar plate (100) and the cathode plate (30) of the second bipolar plate (100), and wherein the first distance (d1) is different from the second distance (d2).

2. A fuel cell stack (1) according to claim 1, wherein the anode plate (20) and / or the cathode plate (30) of at least one bipolar plate (100) has a first region (I) and a second region (II), the first region having a first structure, and the second region having a second structure, wherein in the first region (I), the first structures of the anode plate (20) and the cathode plate (30) are identical, including channel-like structures of grooves (23, 26; 33, 36) and protrusions (22, 25; 32, 36), and in the second region (II), the second structures of the anode plate (20) and the cathode plate (30) are also channel-like structures, wherein the second structure of the anode plate (20) is different from the second structure of the cathode plate (30).

3. A fuel cell stack (1) according to claim 2, wherein the first region (I) is formed in an active region and the second region is formed in a boundary region, wherein on the anode side, the active region is defined by the extent of the anode (11), and on the cathode side, the active region is defined by the extent of the cathode (12), and the boundary region is defined by the extent of a subgasket (14) extending on the anode (11) and / or the cathode (12).

4. The fuel cell stack (1) according to claim 3, wherein a sealing element (42) is provided at the boundary between the first region (I) and the second region (II), and the sealing element (42) seals the active region from the outside so that the active region and the boundary region are separated by the sealing element.

5. A fuel cell stack (1) according to any one of claims 2 to 4, wherein in at least one bipolar plate (100), the second structure of the anode plate (20) or the cathode plate (30) is provided with a first group of protrusions (27) and a second group of protrusions (28), and the second structure of the corresponding other plate, i.e., the cathode plate (30) or the anode plate (20), is provided with a groove (38) and a protrusion (37), wherein the protrusions (27) of the first group of protrusions of the anode plate (20) / cathode plate (30) are arranged to face and / or contact the protrusions (37) of the cathode (12) / anode plate (20), and the protrusions (28) of the second group of protrusions of the anode (11) / cathode plate (30) are arranged to face the grooves (38) of the cathode (12) / anode plate (20), so that the protrusions (28) of the second group of protrusions of the anode (11) / cathode plate (30) are accommodated in the grooves (38) of the cathode (12) / anode plate (20).

6. A fuel cell stack (1) according to any one of claims 2 to 4, wherein the anode (11) and cathode plate (30) of the bipolar plate (100) have a front side (24, 34) and a back side (21, 31), wherein the first structure and the second structure are arranged on the back side (21, 31), wherein: In the first region (I), the grooves (23, 33) on the back sides of the anode (11) and the cathode plate (30) are arranged opposite to each other, thereby forming a cooling liquid flow field channel of the bipolar plate (100).

7. A fuel cell stack (1) according to claim 6, wherein at least in the first region (I), the anode plate (20) and / or the cathode plate (30) has a reactant flow field on the front side (24, 34), wherein each reactant flow field has grooves (26, 36) and protrusions (25, 35), and the grooves (26, 36) and protrusions (25, 35) are formed by corresponding protrusions (25, 35) and grooves (26, 36) on the back side (21, 31).

8. The fuel cell stack (1) according to claim 4, wherein the sealing element (42) is a bead seal.

9. A unit fuel cell (50) for a fuel cell stack (1) according to any one of the preceding claims.

10. A bipolar plate (100) for a fuel cell stack (1) according to any one of claims 1 to 7, comprising at least an anode plate (20) having a front side (24) and a back side (21), and a cathode plate (30) having a front side (34) and a back side (31), wherein the back sides (21, 31) of the anode plate (20) and the cathode plate (30) face each other, wherein the anode plate (20) and the cathode plate (30) each have a first region (I) and a second region (II), the first region (I) having a first structure on the back side (21, 31), and the second region (II) having a second structure on the back side (21, 31), wherein in the first region (I), the first structure is a channel-shaped structure including grooves (23, 33) and protrusions (22, 32), wherein the protrusions (22, 32) of the anode plate (20) and the cathode plate (30) are arranged to face and contact each other, and the anode plate (20) and the cathode plate (30) The grooves (23, 33) are arranged relative to each other to form a cooling liquid flow field channel of the bipolar plate (100), wherein in the second region (II), the second structure of the anode plate (20) or the cathode plate (30) is provided with a first group of protrusions (27) and a second group of protrusions (28), and the second structure of the corresponding other plate (100) is provided with a groove (38) and a protrusion (37), wherein the first group of protrusions (27) is arranged to face and contact the protrusions (37) of the corresponding other plate (100), and the second group of protrusions (28) is arranged to face the grooves (38) of the corresponding other plate (100), so that the second group of protrusions (28) are accommodated in the grooves (38) of the corresponding other plate (100), wherein a sealing element (42) is provided at the boundary of the first region (I) and the second region (II), and the sealing element (42) seals the active region from the outside, so that the active region and the boundary region are separated by the sealing element.

11. The bipolar plate (100) according to claim 10, wherein: The sealing element (42) is a bead seal.

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