fuel cell stack

Abstract

A fuel cell stack (100) is provided, the fuel cell stack (100) comprising at least a fuel cell stack body (102) having a plurality of unit fuel cells, each unit fuel cell including a bipolar plate and a membrane electrode assembly stacked alternately in a stacking direction (104); a first and second terminal plates (110) sandwiching the fuel cell stack body (102), the first and second terminal plates (110) configured to collect electrical energy generated by the fuel cell stack body (102); and first and second end plates (1, 3) sandwiching a second terminal plate (110); and a housing (18) including at least a bottom plate, a stack enclosure (20) configured to cover the side of the fuel cell stack (100), and a top plate (22), wherein the first end plate (1) is configured as the bottom plate of the housing (18) and has at least one protruding connecting element (14) protruding laterally from the first end plate (1) and configured to connect the stack enclosure (20) to the first end plate (1).

Description

[Technical Field]

[0001] The present invention relates to a fuel cell stack. [Background technology]

[0002] A fuel cell stack typically consists of a stack body containing multiple membrane electrode assemblies (MEAs) separated by so-called bipolar plates (BPPs), a pair of terminal plates that collect the current generated by the stack body, and a pair of end plates that sandwich the terminal plates. Generally, an insulating plate is provided between each terminal plate and the adjacent end plate to insulate the terminal plate from the adjacent end plate.

[0003] The bipolar plate itself typically consists of at least two electrically conductive metal plates, so-called flow field plates, arranged one on top of the other, with a reactant flow field on one side and a cooling fluid flow field on the other. The cooling fluid flow fields thus face each other, while the reactant flow field faces the MEA. Each bipolar plate and / or membrane electrode assembly has inlet manifolds for fuel, oxidant, and coolant, and outlet manifolds for fuel, oxidant, and coolant. In an assembled stack, each manifold extends through the fuel cell stack body, forming tubular channels that carry the respective flow to and from the fuel cell stack. The flow fields of each plate form the active area where electrical energy is generated, and the active area is located between the inlet and outlet manifolds of each individual fuel cell.

[0004] Furthermore, to provide contact protection and / or protection from environmental influences such as water and / or dirt, the fuel cell stack is enclosed in a housing comprising a bottom plate, a top plate and side walls, with sealing elements provided between different elements of the housing to achieve an airtight sealed environment for the fuel cell stack within the housing and ensure safe and stable operation of the fuel cell stack.

[0005] However, the number of different components can make a typical fuel cell stack quite heavy, and manufacturing a fuel cell stack can be costly and effort intensive, as the components must be manufactured and assembled to close tolerances, some to ensure proper functioning of the fuel cell stack. Summary of the Invention [Problem to be solved by the invention]

[0006] It is therefore an object of the present invention to provide a fuel cell stack that is lightweight and can be manufactured in a simple and cost-effective manner. [Means for solving the problem]

[0007] This object is solved by a fuel cell stack according to claim 1.

[0008] Hereinafter, a fuel cell stack is provided that includes a fuel cell stack body with a plurality of unit fuel cells. Each unit fuel cell includes bipolar plates and membrane electrode assemblies stacked alternately in a stacking direction. Each bipolar plate and / or membrane electrode assembly may include an inlet manifold for at least a fuel, an oxidant, and a coolant, and an outlet manifold for at least a fuel, an oxidant, and a coolant. In particular, the manifolds may extend through the fuel cell stack body to form respective tubular channels for supplying respective flows to / from the fuel cell stack, and each of the unit fuel cells has an active area where electrical energy is generated, the active area being disposed between the inlet and outlet manifolds of each unit fuel cell.

[0009] The fuel cell stack further includes first and second terminal plates sandwiching the fuel cell stack body, the first and second terminal plates configured to collect electrical energy generated by the fuel cell stack body. The fuel cell stack also includes first and second end plates sandwiching the fuel cell stack body. At least one end plate may include at least one inlet opening and at least one outlet opening, the at least one inlet opening aligned with one or more inlet channels, and the at least one outlet opening aligned with one or more outlet channels. For example, the at least one end plate may include inlet openings for at least fuel, oxidant, and coolant, and outlet openings for at least fuel, oxidant, and coolant. Furthermore, an insulating plate may be provided between one terminal plate and an adjacent end plate.

[0010] Furthermore, the fuel cell stack includes a housing having at least a bottom plate, a stack enclosure configured to cover a side of the fuel cell stack, and a top plate. In particular, the top plate may be connected to the stack enclosure or may be formed integrally with the stack enclosure. The stack enclosure may be formed as a hollow box or may be formed by a plurality of separate side walls connected to each other to form the hollow box.

[0011] To reduce the number of parts of the fuel cell stack and the complexity of the assembly process, the first end plate is configured as a bottom plate of a housing and includes at least one protruding connection element protruding laterally from the first end plate and configured to connect the stack enclosure to the first end plate. This allows the bottom plate of the housing to be omitted, thereby reducing the overall fuel cell stack weight and part count, simplifying the assembly process and reducing the weight and cost of the completed fuel cell stack. Advantageously, the second end plate may further be configured as a top plate of a housing. This reduces the number of parts, thereby further reducing the weight of the fuel cell stack.

[0012] Furthermore, the first end plate may include a plurality of protruding connection elements, which may be discretely arranged around the outer periphery of the first end plate, which has the advantage that the stack enclosure can be reliably fixed to the first end plate.

[0013] Alternatively, the at least one protruding connection element may be configured as a flange extending along the entire periphery of the first end plate, which has the advantage that the stack enclosure can be fixed evenly around the periphery of the first end plate, and furthermore, as will be explained in more detail below, this simplifies sealing of the housing against external contaminants.

[0014] Furthermore, the at least one protruding connection element may include at least one fastening interface for securing the stack enclosure to the at least one protruding connection element and thereby to the first end plate. This allows the stack enclosure to be further fastened to the first end plate. Preferably, the fastening interface may be configured to removably fasten the stack enclosure to the protruding element. This has the advantage that the housing can be easily removed to access the fuel cell stack, for example for maintenance purposes, and then reattached. The fastening interface may be configured to provide a pressure and / or form fit for the stack enclosure to the protruding connection element. For example, the fastening interface may be a groove, a clamping element, a latch, a snap tag, a lug, and / or a hole (e.g., a threaded or blind hole, or a through hole through which a fastening element can pass) in the protruding connection element.

[0015] According to a further embodiment, at least one sealing element is provided, configured to provide a seal between the at least one protruding connection element and the stack enclosure. This allows for a sealed environment for the fuel cell stack within the housing, thereby ensuring safe and stable operation of the fuel cell stack. More specifically, the stack enclosure may abut against an upper portion of the at least one protruding connection element or a side portion of the at least one protruding connection element. When the stack enclosure abuts against the upper portion of the at least one protruding connection element, the at least one sealing element may be disposed between the stack enclosure and the protruding connection element such that the at least one sealing element is compressed by gravity, thereby improving the seal between the stack enclosure and the end plate, more specifically, the protruding connection element. However, the at least one sealing element can also be compressed by other means. For example, a fastening element that secures the stack enclosure to the protruding connection element may be further configured to compress the at least one sealing element. In this way, even when the stack enclosure abuts against the side of the protruding connection element, the seal between the stack enclosure and the protruding connection element can be improved by compressing the at least one sealing element using the fastening element.

[0016] Furthermore, the at least one sealing element is arranged on the at least one protruding connection element and / or the stack enclosure. Preferably, the at least one sealing element is fixed to the protruding connection element or the stack enclosure. For example, the at least one sealing element may be permanently or removably fixed to the protruding connection element or the stack enclosure. This has the advantage that the at least one sealing element is fixed in place.

[0017] Furthermore, the at least one sealing element may be a continuous sealing element, which, in particular in combination with the flange, allows for improved gas-tight sealing of the fuel cell stack in the housing. If gas-tight sealing of the housing is not required, for example if only contact protection is required, it is also possible to provide a plurality of discrete sealing elements, which can preferably interact with discrete protruding connection elements.

[0018] Preferably, the at least one sealing element is arranged in a groove. Furthermore, the at least one sealing element may be frictionally fixed, press-fitted, adhesively attached, and / or molded to the protruding connecting element, in particular a flange, or to the stack enclosure. For example, the at least one sealing element may have a U-shape that can be attached to the edge of the stack enclosure. Furthermore, the at least one sealing element may be molded, clamped, and / or glued.

[0019] Furthermore, the at least one protruding connection element may include a groove. The groove may be configured to accommodate a portion of the stack enclosure, such as an edge of the stack enclosure, and / or the at least one sealing element. This has the advantage that the position of the stack enclosure and / or the position of the at least one sealing element on the first end plate can be adjusted and / or fixed. Preferably, the groove may be deep enough to also include the at least one sealing element. This can improve the airtight seal of the fuel cell stack within the housing. Alternatively, the groove may only accommodate the at least one sealing element.

[0020] According to a further embodiment, the end plate includes a base portion and a stepped portion, the at least one protruding connection element is disposed on the base portion, and the stepped portion includes input and output ports and / or terminals for operation of the fuel cell stack. For example, the input and output ports and terminals may include inlet openings for reactants and / or coolants, outlet openings for reactants and / or coolants, at least one output terminal for generated electrical energy, and / or at least one terminal for monitoring the fuel cell stack. Preferably, the stepped portion is recessed by a predetermined amount relative to the base portion, thereby ensuring sufficient space between the stack enclosure and fuel cell stack components disposed in the stepped portion, such as a compression element to be provided for compressing the fuel cell stack.

[0021] Preferably, at least the first end plate includes at least one reinforcing element for reinforcing the first end plate, particularly against deformation forces. In particular, the at least one reinforcing element may be embedded in the first end plate. For example, the at least one reinforcing element may be overmolded or inserted into the material of the first end plate. Preferably, the at least one reinforcing element is made of metal, such as a metal bar or metal tube. This improves the resistance of the first end plate to deformation forces. For example, the at least one reinforcing element may be a hollow or solid element. The at least one reinforcing element may also be a profiled element and / or may include an opening through which the material forming the end plate can enter.

[0022] Additionally or alternatively, the at least one reinforcing element may be a frame having at least one bar with a circular, triangular, rectangular, oval, or polygonal cross section. Preferably, the at least one reinforcing element is disposed at the stepped portion of the first end plate. Furthermore, the reinforcing element may be configured to function as an anchor point for fixing the compression element configured to compress the fuel cell stack in the stacking direction. This has the advantage that the compression element can be attached directly to the stable structure of the end plate.

[0023] According to a further embodiment, at least the first end plate is made of an electrically insulating material. By making the first end plate from an electrically insulating material, the first end plate can be advantageously placed in at least partial direct contact with the terminal plate, eliminating the need for an additional insulating plate. This further reduces the number of parts, resulting in a simplified assembly process, since fewer parts must be assembled. Because the end plate itself is at least partially made from an electrically insulating material, there is no risk of a short circuit even if the terminal plate comes into direct contact with the end plate.

[0024] Additionally or alternatively, the at least one end plate may be at least partially coated with an electrically insulating material in the area in direct contact with the adjacent terminal plate. For example, the end plate may be made at least partially of metal coated with an electrically insulating material. This has the advantage that the metal provides the necessary strength and / or stability required for the end plate, while the electrically insulating material forms a coating that provides electrical insulation.

[0025] Furthermore, the plastic material may be a fiber-reinforced plastic material, which has the advantage of providing greater strength and / or stability than plastic materials while also having electrical insulating properties. For example, the fiber-reinforced plastic material may be a glass fiber reinforced molding compound, a glass fiber reinforced epoxy, a glass fiber reinforced polyester, and / or a glass fiber reinforced phenolic molding compound.

[0026] Preferably, the electrically insulating material is a moldable material, and preferably the at least one end plate is molded. Advantageously, the end plate may be formed by a molding process, such as injection molding, which allows for a cost-effective manufacturing process. For example, the electrically insulating material may be a composite plastic, a thermosetting composite material, and / or a phenolic plastic. Thermosetting plastic materials have the advantage that they do not change shape when exposed to heat.

[0027] Preferably, the at least one end plate includes a recess formed in a surface of the end plate facing an adjacent terminal plate, the recess being dimensioned to accommodate the terminal plate. This reduces the overall height of the fuel cell stack. Furthermore, the depth of the recess may be designed so that the entire height of the terminal plate can be accommodated within the recess. Alternatively, the depth of the recess may be designed so that only a portion of the height of the terminal plate is incorporated into the recess.

[0028] Furthermore, the dimensions and / or depth of the recesses may be dimensioned such that the recesses are further configured to incorporate a heating element configured to heat the fuel cell stack body. The heating element may be configured to provide thermal energy to the fuel cell stack or a portion of the fuel stack to compensate for heat losses occurring during operation of the fuel cell stack or to heat the fuel cell stack during start-up. By also locating the heating element in the recesses of the end plates, the height of the fuel cell stack is further reduced.

[0029] According to a further embodiment, at least the first end plate is in at least partial direct contact with the terminal plate, and the at least one end plate includes at least one surface structure element configured to prevent current leakage between the terminal plate and the conductive portion of the end plate. Although the end plate is electrically insulated, current leakage may occur. Ground faults, or leakage currents, are uncontrollable and unwanted currents that flow along the surface of an insulating material between two conductors. The shortest path these currents take along the surface of the insulating material is called the creepage distance. These fault currents on the surface of the insulating material can cause changes in the insulating material over time.

[0030] For example, the at least one surface structure element may be disposed adjacent to a conductive element. Preferably, the at least one surface structure includes at least one rib and / or groove, and / or a plurality of ribs and / or grooves. Additionally or alternatively, the at least one structural element may be disposed around the periphery of the at least one end plate and / or in a recess formed in the at least one end plate. The conductive element may be the terminal plate, a reinforcing element, and / or other metal part. Also, the at least one end plate may be provided with one or more surface structure elements.

[0031] Further preferred embodiments are defined in the description and drawings as well as in the dependent claims, in which respect an element described or shown in combination with other elements may also be present alone or in combination with other elements without departing from the scope of protection.

[0032] Preferred embodiments of the invention will now be described with reference to the drawings, which are for illustrative purposes only and are not intended to limit the scope of protection, which is defined solely by the appended claims. [Brief explanation of the drawings]

[0033] [Figure 1] 1 is a schematic perspective exploded view of a fuel cell stack according to one embodiment. [Figure 2] FIG. 2 is a schematic perspective view of an end plate of the fuel cell stack of FIG. 1. [Figure 3] FIG. 2 is a side view of a fuel cell stack. DETAILED DESCRIPTION OF THE INVENTION

[0034] In the following, identical or similarly functioning elements are designated with the same reference numerals.

[0035] 1-3 illustrate a fuel cell stack 100 according to one embodiment. The fuel cell stack includes a fuel cell stack body 102 with a plurality of unit fuel cells. Each unit fuel cell includes bipolar plates and membrane electrode assemblies stacked alternately in a stacking direction 104. Each bipolar plate and / or membrane electrode assembly may include inlet manifolds for at least fuel, oxidant, and coolant, and outlet manifolds for at least fuel, oxidant, and coolant. The manifolds may extend through the fuel cell stack body 102 to form respective tubular channels 106 for supplying respective flows to and from the fuel cell stack 100. Each unit fuel cell has an active area 108 where electrical energy is generated, and the active area 108 is disposed between the inlet and outlet manifolds of each unit fuel cell.

[0036] The fuel cell stack 100 further includes first and second terminal plates 110 that sandwich the fuel cell stack body 102. The first and second terminal plates 110 are configured to collect electrical energy generated by the fuel cell stack body 102 within the active area 108. The fuel cell stack also includes a first end plate 1 and a second end plate 3 that sandwich the fuel cell stack body 102.

[0037] Furthermore, the fuel cell stack 100 includes a housing 18 (FIG. 3) that can function as contact and / or environmental protection. The housing 18 includes a stack enclosure 20 configured to cover the side of the fuel cell stack 100 and a top plate 22. The bottom plate of the housing 18 is formed by a first end plate 1, as can be seen in FIG. 3. The top plate 22 is connected to the stack enclosure 20 at a fastening interface 24, and the stack enclosure 20 is formed by a plurality of independent side walls 20-1, 20-2 that are interconnected to form a hollow box. Alternatively, the stack enclosure 20 may be formed as a hollow box, and / or the top plate 22 may be integrally formed with the stack enclosure 20, or the second end plate 3 may be configured as the top plate 20.

[0038] In order to also function as a bottom plate for the housing 18, the end plate 1 comprises a protruding connecting element 14 that protrudes laterally from the first end plate 1 and is configured to connect the housing 18 to the first end plate 1. In the embodiment described above, the protruding connecting element is a flange 14 that surrounds the outer periphery of the end plate 1. Alternatively, particularly if only touch protection is required, the first end plate 1 may comprise a plurality of separate protruding connecting elements, which are arranged around the outer periphery of the first end plate 1.

[0039] In the above-described embodiment, the housing 18 abuts against the top of the flange 14, as can be seen in FIG. 3 . To attach the housing 18 to the end plate 1, the flange 14 has a plurality of fastening interfaces 16 for securing the housing 18 to the end plate 1. In the illustrated embodiment, the fastening interfaces 16 are blind threaded holes provided in the flange 14 in the stacking direction 104. However, the fastening interfaces 16 may also be through-holes or through-holes through which a fastening element can be inserted. Alternatively, the stack enclosure 20 may abut against a side surface of the flange 14. In this case, the blind threaded holes serving as fastening interfaces may be provided on the side surface of the flange 14 perpendicular to the stacking direction 104.

[0040] To ensure an airtight seal for the fuel cell stack, a continuous sealing element 25 is provided for sealing between the flange 14 and the housing 18 or stack enclosure 20, respectively. In the illustrated embodiment, the sealing element 26 is disposed in a groove 28 provided in the flange 14. Alternatively, the sealing element 26 may be fixed to the protruding connection element 14 or the stack enclosure 20. For example, the sealing element 26 may be frictionally fixed, press-fit, adhesively attached, molded, clamped, and / or glued. As can be seen in FIG. 3 , the stack enclosure 20 abuts the top of the flange 14, causing the weight of the stack enclosure 20 due to gravity to compress the sealing element 26 even before the stack enclosure 20 is fastened to the first end plate 1.

[0041] As can be seen, the end plate 1 has a T-shape with a base portion formed by a flange 14 and a stepped portion, the stepped portion including input and output ports and / or terminals, e.g., input and output openings 2a, 2b, 2c, 4a, 4b, 4c, for operation of the fuel cell stack 100. More specifically, the first end plate 1 has fuel, oxidant and coolant inlet openings 2a, 2b, 2c and fuel, oxidant and coolant outlet openings 4a, 4b, 4c.

[0042] 1, the inlet openings 2a, 2b, 2c and outlet openings 4a, 4b, 4c are aligned with inlet and outlet channels 106 extending through the fuel cell stack body 102 to provide respective flow to and from the fuel cell stack 100. In this case, the second end plate 3 is configured to terminate the inlet and outlet channels 106. Alternatively, the inlet openings 2a, 2b, 2c and outlet openings 4a, 4b, 4c may be split between the first and second end plates 1, 3.

[0043] 1, the first end plate 1 and the second end plate 3 are at least partially in direct contact with the terminal plate 110. To avoid short circuits between the terminal plate 110 and the first and second end plates 1 and 3, the end plates 1 and 3 are made of a plastic material to electrically insulate the end plates 1 and 3. Alternatively, insulating plates made of an electrically insulating material may be provided between the end plates 1 and 3 and the terminal plate 110.

[0044] The plastic material from which the first end plate 1 is formed may be a moldable plastic material, allowing the end plate 1 to be formed by a molding process such as injection molding.

[0045] Additionally, in the illustrated embodiment, the end plate 1 includes three reinforcing elements 6 embedded in the plastic material. However, any other number of reinforcing elements 6 may be selected depending on the dimensions of the end plate 1 and / or the expected loads that the end plate 1 will be subjected to. As can be seen in FIG. 3 , the reinforcing elements 6 are cylindrical rods that extend through the end plate 1. For example, the reinforcing elements 6 may be overmolded with an electrically insulating material. Alternatively, the reinforcing elements 6 may be inserted into the end plate 1.

[0046] Alternatively, the reinforcing elements 6 may form a frame with metal bars with a circular, triangular, rectangular, oval or polygonal cross section. Depending on the dimensions of the end plate 1 and / or the expected loads on the end plate 1, the reinforcing elements 6 may be hollow or solid. The reinforcing elements 6 may also be profiled and / or include openings through which the material forming the end plate 1 can penetrate. Of course, different types of reinforcing elements 6 may be used in one end plate 1.

[0047] The end plate 1 shown in this embodiment is made from a plastic material, thereby eliminating the need for an additional insulating plate between the end plate 1 and the adjacent terminal plate 110. As can be further seen in the illustrated embodiment, the end plate 1 includes a recess 8 formed in a surface 10 of the end plate 1 that faces the adjacent terminal plate 110. The dimensions of the recess 8 are dimensioned to accommodate the terminal plate 110. For example, the depth of the recess 8 may be designed such that the entire height of the terminal plate 110 can be accommodated in the recess 8. Alternatively, the depth of the recess 8 is such that only a portion of the height of the terminal plate 110 is incorporated into the recess 8.

[0048] Furthermore, the end plate 1 includes a surface structure element 12 configured to prevent current leakage between conductive elements, such as the terminal plate 110 and the conductive portion of the end plate 1. For example, the surface structure element 12 is disposed adjacent to the reinforcing element 6, which is a conductive element. The surface structure element 12 is formed as a rib 13 and a groove 15. Additionally or alternatively, at least one structure element 12 may be disposed in the recess 8.

[0049] In summary, by providing end plates that also function as the housing bottom plates, the housing bottom plates can be omitted, resulting in a reduction in the number of parts in the fuel cell stack. This can reduce the overall weight of the fuel cell stack, and the reduced number of parts can also simplify the fuel cell stack assembly process. Using end plates made of an electrically insulating plastic material can also eliminate the insulating plates typically provided between the end plates and the terminal plates, thereby achieving further weight and / or part reductions. Because the end plates are electrically insulated, there is no risk of a short circuit even if the conductive elements of the terminal plates come into contact with the end plates. [Explanation of symbols]

[0050] 1 end plate 2 Opening 3 End Plate 4 Openings 6 Reinforcing elements 8 recess 10 surface 12 Surface structure elements 13 Ribs 14 Protruding connecting element 15 groove 16 Fastening Interface 18 Housing 20 stack enclosures 22 Upper Plate 24 Fastening Interface 26 sealing elements 28 Groove 100 fuel cell stack 102 fuel cell stack body 104 Lamination direction 106 channels 108 Active Area 110 Terminal plate

Claims

1. A fuel cell stack (100) comprising at least a fuel cell stack body (102) including a plurality of unit fuel cells, each unit fuel cell including a bipolar plate and a membrane electrode assembly stacked alternately in a stacking direction (104); first and second terminal plates (110) sandwiching the fuel cell stack body (102), the first and second terminal plates (110) being configured to collect electrical energy generated by the fuel cell stack body (102); first and second end plates (1, 3) sandwiching the first and second terminal plates (110); The fuel cell stack (100) includes a housing (18) including at least a bottom plate, a stack enclosure (20) configured to cover the sides of the fuel cell stack (100), and a top plate (22), 1. A fuel cell stack (100) comprising: a first end plate (1) configured as the bottom plate of the housing (18); and at least one protruding connecting element (14) protruding laterally from the first end plate (1) and configured to connect the stack enclosure (20) to the first end plate (1).

2. 2. The fuel cell stack (100) of claim 1, wherein the at least one protruding connection element (14) includes at least one fastening interface (16) for securing the stack enclosure (20) to the at least one protruding connection element (14), and thereby to the first end plate (1).

3. 3. The fuel cell stack (100) according to claim 1 or 2, wherein the stack enclosure (20) abuts against an upper portion of the at least one protruding connection element (14) or a side portion of the at least one protruding connection element (14).

4. The fuel cell stack (100) of any of claims 1 to 3, wherein the at least one protruding connection element (14) includes a groove (28).

5. 5. A fuel cell stack (100) according to any one of claims 1 to 4, wherein at least one sealing element (26) is provided, configured to provide a seal between the at least one protruding connection element (14) and the stack enclosure (20), and preferably the sealing element is arranged in a groove (28).

6. 6. The fuel cell stack (100) according to claim 5, wherein the at least one sealing element (26) is arranged on the at least one protruding connection element (14) and / or the stack enclosure (20), and preferably the at least one sealing element (26) is fixed to the protruding connection element (14) or the stack enclosure (20).

7. 7. The fuel cell stack (100) according to any one of claims 1 to 6, wherein the at least one protruding connection element (14) is configured as a flange extending along the entire periphery of the first end plate (1).

8. 8. A fuel cell stack (100) as described in any one of claims 1 to 7, wherein the first end plate (1) includes a base portion and a stepped portion, the at least one protruding connection element (14) is arranged on the base portion, and the stepped portion includes input and output ports and / or terminals for operation of the fuel cell stack (100).

9. 9. A fuel cell stack (100) according to any one of claims 1 to 8, wherein at least the first end plate (1, 3) comprises at least one reinforcing element (6) for reinforcing the first end plate (1, 3), in particular against deformation forces.

10. 10. The fuel cell stack (100) according to any of the preceding claims, wherein at least the first end plate (1, 3) is made of a plastic material, preferably a fiber-reinforced plastic material.

11. 11. The fuel cell stack (100) of claim 10, wherein at least the first end plate (1, 3) is in at least partial direct contact with the terminal plate (110), and the at least one end plate (1, 3) includes at least one surface structural element configured to avoid current leakage between the terminal plate (110) and the conductive element of the end plate (1, 3).

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