Fuel cell assembly comprising a support structure arranged transversely to the stacking direction

Abstract

The invention relates to a fuel cell stack (12) comprising: an assembly (8) of a plurality of fuel cells that are stacked in a stacking direction (10); two end plates (4, 6) that delimit the assembly (8) and are arranged opposite one another in the stacking direction (10); and a support structure (14, 38, 50, 58) that extends on at least one side surface (7, 9) of the assembly (8) and at least between the end plates (4, 6), the support structure (14, 38, 50, 58) being designed to support the fuel cells transversely to the stacking direction (10) in order to prevent the fuel cells from slipping transversely to the stacking direction (10). The support structure (14, 38, 50, 58) has an element (30, 40) which is preformed such that the support structure (14, 38, 50, 58), when assembled, exerts a preloading force that acts on the assembly (8) of a plurality of fuel cells, and the preloading force acts on the assembly (8) of a plurality of fuel cells transversely to the stacking direction (10).

Description

[0001] Fuel cell arrangement with a support structure arranged transversely to the stacking direction

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to a support structure for fuel cell assemblies.

[0004] TECHNICAL BACKGROUND

[0005] In light of growing efforts to protect the environment, hydrogen is becoming increasingly important as an energy carrier. The energy stored in hydrogen can be converted into electrical energy, for example, in fuel cells. Fuel cells can be subject to various requirements, particularly in aviation applications, but also in other highly dynamic environments.

[0006] In a fuel cell stack, several fuel cells or fuel cell components, such as bipolar plates, are typically pressed together between two end plates under a defined compressive load. However, if vibrations occur, these vibrations, together with gravity or other forces such as centrifugal forces, can lead to relative movements of the individual cells of the fuel cell stack. Particularly if the fuel cell stack is positioned horizontally, this can result in a "deflection" of the entire fuel cell stack. However, corresponding displacements can also occur if the fuel cell stack is aligned vertically. In particular, the highly demanding shock and vibration conditions in aviation can lead to severe deflection of the fuel cell stack and thus to possible damage.

[0007] Lateral support structures are known in which a band runs around the fuel cell stack. However, due to the flexural flexibility of the band, such structures cannot reliably prevent relative displacement of the fuel cell stack components, especially under high loads.

[0008] DESCRIPTION

[0009] Accordingly, it is an object of the invention to provide a support structure for a fuel cell stack which effectively prevents lateral displacement of individual cells relative to one another or deflection of the entire stack.

[0010] This object is achieved by the subject matter of the independent patent claims. Further embodiments emerge from the dependent claims and the following description.

[0011] The present invention discloses a fuel cell stack with a support structure that prevents lateral slippage of the fuel cells, as well as a method for assembling such a support structure. Features described with respect to the fuel cell stack also apply to the method, and vice versa.

[0012] According to a first aspect, a fuel cell stack is disclosed. The fuel cell stack comprises an arrangement of a plurality of fuel cells stacked in a stacking direction, two end plates delimiting the arrangement and arranged opposite one another in the stacking direction, and a support structure extending on at least one side surface of the arrangement and at least between the end plates. The support structure is designed to support the fuel cells transversely to the stacking direction in order to counteract deformation of the arrangement of a plurality of fuel cells. The support structure has a preformed element such that the support structure, in an assembled state, exerts a prestress acting on the arrangement of a plurality of fuel cells. The prestress acts on the arrangement of a plurality of fuel cells transversely to the stacking direction.

[0013] Deformation of the array of multiple fuel cells can, for example, be a slippage of the fuel cells transverse to the stacking direction, but also any other deformation. The support structure, as described herein, effectively prevents such deformation.

[0014] Each of the fuel cells comprises corresponding components, e.g., bipolar plates, electrolyte layers, sealing layers, gas diffusion layers, membrane layers, and catalyst layers, as known to those skilled in the art. Several such fuel cells are stacked one on top of the other such that the individual fuel cells form a stacked arrangement of fuel cells, which is held together between two end plates. The individual fuel cells form a uniform column with uniform lateral surfaces, e.g., the column forms essentially flat lateral surfaces when the fuel cell stack is unloaded.

[0015] Although the end plates already provide a basic stress in the fuel cell stack running in the stacking direction, forces acting transverse to the stacking direction can cause both displacement of the individual fuel cells relative to each other and deformation of the entire stack as a whole. In the former case, numerous micromovements can occur, which can also lead to global deformation of the stack. It can be assumed that both phenomena occur simultaneously. Micromovements are more likely to occur when, in addition to the aforementioned static forces, dynamic mechanical influences such as vibrations occur.

[0016] To prevent such deflections, the present disclosure provides a lateral support structure. The support structure is a mechanical element for reducing or preventing deformation of the fuel cell stack and acts laterally on the array of fuel cells, such that a support load is applied to the fuel cell stack or its components. The support structure supports the fuel cell stack or the array of fuel cells at least in one direction transverse or perpendicular to the stacking direction by preventing movement of the fuel cells relative to one another along this support direction through an applied prestress acting against the array of fuel cells and / or on one or more lateral surfaces of the array of fuel cells.

[0017] The support structure uses at least one preformed element which presses against the arrangement of fuel cells in at least one direction transverse or perpendicular to the stacking direction or counteracts a displacement of the arrangement of several fuel cells in at least one direction transverse or perpendicular to the stacking direction.

[0018] For example, the preformed element can be a resilient element whose spring force presses against the array of fuel cells. In such a configuration, the support structure preferably extends at least on opposite sides of the fuel cell stack and presses onto the side surfaces of the corresponding sides via the preformed element, preventing the array of fuel cells or the individual fuel cells from slipping in the corresponding connecting direction between the two side surfaces. By using such a two-sided support structure with preformed elements as resilient elements (which induce tension transversely or perpendicularly to the array), the resilient elements themselves can prevent individual fuel cells from being pushed out of the array.

[0019] In addition, the support structure, together with components of the fuel cell arrangement, for example with the bipolar plates, but also other stack components, can be shaped in such a way that displacement in both directions perpendicular to the stack direction is also prevented. This is achieved, for example, by means of bevelled contact surfaces, as described further below. This makes it possible to simultaneously prevent / reduce the second axis and thus the movement / deformation of the stack in this second axis using a single support structure that is mounted along one axis and is intended to prevent or reduce deformation of the fuel cell stack in the direction of this axis. The support structure and the engaged stack components can for this purpose be shaped, for example, so that they are in bevelled contact with one another, as described in more detail below.In general, the support structure (or the preformed element of the support structure) runs at least between the end plates or an element of a bracing unit that secures the fuel cell stack. A bracing unit does not necessarily consist exclusively of an end plate, but can be constructed from a variety of components. The support structure can, for example, be attached to one of these bracing elements of the bracing unit itself, for example by welding, screwing, riveting, gluing, or any other suitable fastening method. However, the support structure can also be attached to a surrounding structure (for example, a base plate on which the fuel cell stack is mounted).

[0020] The preformed element may also be a rigid element that extends laterally at least between the end plates of the fuel cell stack. For example, the support structure may be a structural component, such as a rod or beam, that extends laterally along at least one of the side surfaces of the fuel cell stack substantially in the stacking direction and is shaped accordingly to provide laterally supported assembly.

[0021] In general, the support structure can also comprise an intermediate electrically insulating component or layer and thus be insulated from the arrangement of multiple fuel cells, so that direct contact of electrically conductive or mechanically rigid components of the support structure, such as the preformed element, with the components of the individual fuel cells is avoided, thereby reducing the risk of short circuits caused by bridging multiple fuel cells and of mechanical damage. Such a layer can also be designed as a sliding element, or an additional sliding element can be provided, which can slide relative to the support structure or relative to the preformed element along the stacking direction. Such a sliding element is thus fixed to the support structure or to the side surface along the stacking direction and can slide off on the other side.This prevents damage to the multiple fuel cells due to an undesired force acting along the stacking direction on the fuel cells or their components.

[0022] In addition, the support structure can be used in conjunction with the bracing elements already required for stack bracing, such as straps, tie rods, etc., which can be provided between the preformed element of the support structure and the array of multiple fuel cells. This makes it possible, with the aid of the existing mechanical components of the bracing system, to press the support structure against the fuel cell components, thus achieving improved contact pressure on the stack. Furthermore, with a suitable design, these contact partners can be used as sliding elements to compensate for potential relative movements in the stacking direction.

[0023] Optionally, as described below, a compressible component and / or a protective layer and / or a sacrificial material (a material that may be damaged to a certain extent by the fuel cells, i.e., cut by the cell components, thereby providing a common contact surface between the cell components and the support structure) may additionally be provided between the side surface of the array of multiple fuel cells and the remaining components of the support structure. Such a component can adapt to the contour of the corresponding side surface and thus also prevent protection against damage due to force application along the stacking direction. An uneven surface caused by the offset of individual cell components relative to one another can lead to an uneven application of force, which can result in damage to the cell components.For this reason, a design solution described here to reduce force peaks or to equalize the surface pressure is optionally considered.

[0024] The support structure can also be provided and arranged on each of the side surfaces of the fuel cell stack as a single, connected component or as a multi-part component, wherein the individual components of the support structure run essentially parallel to one another along the stacking direction. Furthermore, the support structure can act on each side surface on which it is present either completely and extensively along the entire stacking direction on the arrangement of several fuel cells, or only selectively along the stacking direction on the arrangement. When using a resilient element, this can, for example, be designed on each side surface as a type of clamp which, when installed, acts in a central region of the corresponding side surface with respect to the stacking direction. It is also conceivable for the prestress to vary along the stacking direction.For example, at locations in the arrangement of several fuel cells that are close to the end plates, a lower prestress may be necessary than at central locations in the middle between the end plates.

[0025] The prestressing of the support structure on each side surface of the fuel cell stack to which such a support structure is attached can act on the respective side surface perpendicularly or parallel or both perpendicularly and parallel (for example in the mentioned embodiment with bevelled contact surfaces) to the corresponding side surface on the arrangement of several fuel cells and thus provide a supporting effect only in one side direction of the arrangement or in both side directions of the arrangement.

[0026] According to one embodiment, the support structure runs along at least one pair of two opposite side surfaces of the fuel cell stack.

[0027] The arrangement on both sides on opposite sides prevents a lateral displacement (partial or complete) of the arrangement of several fuel cells by the support structure itself, which could occur, for example, if a force acts perpendicular to the side surface only on one side surface, which is not compensated by a counterforce on the opposite side.

[0028] According to a further embodiment, the support structure is designed to support the fuel cells in two spatial directions running transversely to the stacking direction.

[0029] For example, the support structure can run along all four side surfaces of the array of multiple fuel cells and thus introduce a prestress on each of the side surfaces. However, the support structure can also have a second contact section that is shaped to match a first contact section on the components of the fuel cells (such as their bipolar plates), so that the support structure on one of the side surfaces of the array of multiple fuel cells additionally introduces a prestress parallel to the corresponding side surface and perpendicular to the stacking direction. As a result, even a support structure that is present only on one side surface of the array can enable a supporting effect in both directions perpendicular to the stacking direction.

[0030] According to a further embodiment, the support structure is arranged on the end plates or can be fastened to a base supporting the fuel cell stack.

[0031] According to a further embodiment, the support structure has at least one resilient element which presses transversely to the stacking direction onto at least one side surface of the arrangement of a plurality of fuel cells.

[0032] Furthermore, alternatively or additionally, one (or more) plates that are functionally passive with respect to the actual function of the fuel cell stack (also referred to herein as a middle plate) can be provided at any position along the stacking direction. Such a middle plate separates the arrangement into several partial stacks, which have a lower partial stack height in the stacking direction than the entire arrangement of several fuel cells. The middle plate then serves as the sole or additional contact partner with the support structure. Since the partial stack height of the partial stacks is lower than the stack height of the overall stack, deformation of the stack is prevented or at least reduced.

[0033] Such a resilient element can, for example, be an elastic, clamp-like element that has a bent starting position. The resilient element can, for example, be made of a metallic material or a plastic material that possesses a certain degree of flexibility, so that the resilient element pushes back to its starting position when bent from its starting position. In particular, a resilient element made of plastic can contribute to the electrical insulation of the individual fuel cells, as described further below. When the resilient element is straightened from its bent starting position, it pushes back to its bent starting position, thus providing a clamping force.If the straightened resilient element is then secured at the ends, for example, to the end plates of the fuel cell stack or a surrounding structure, and then released, the resilient element (since its ends are fixed to the end plates) pushes back into its original position, thereby pressing against the side surface of the multiple fuel cell array, as described above. In particular, the resilient element can be the preformed element described above.

[0034] According to a further embodiment, the support structure comprises at least one arrangement consisting of a rigid support and a compressible component. The compressible component is arranged between the respective side surface of the arrangement of multiple fuel cells and the rigid support.

[0035] The compressible component is arranged between the preformed element and the corresponding side surface of the arrangement of several fuel cells. The compressible component is pressed against the respective side surface by the preformed element or by corresponding intermediate layers located between the preformed element and the side surface (such as electrically insulating components and sliding elements, if present) and preferably has deformable surfaces. The compressible component can thus adapt to the shape / contour of both the side surface of the arrangement and the shape / contour of the elements of the support structure located further out. This prevents damage to the fuel cells due to a not completely uniform surface (i.e.Minor positioning errors of the individual fuel cells relative to each other are compensated for), and the preload is evenly distributed throughout the array of multiple fuel cells. The compressible component can be made of any suitable material and exhibits high friction with respect to the side surfaces. The compressible component is, for example, an elastic element or a foam. In general, the compressible component also protects softer elements of the support structure from damage caused by sharp edges of the fuel cell elements.

[0036] According to a further embodiment, the compressible component comprises a fluid-filled cushion or a foam.

[0037] According to a further embodiment, the support structure consists of an electrically insulating material or is coated with an electrically insulating material, or at least one electrically insulating component is positioned between the support structure and the arrangement of a plurality of fuel cells.

[0038] The support structure, or parts thereof, can be made of electrically insulating materials. In particular, elements of the support structure that come into direct contact with the array of multiple fuel cells are made of electrically insulating materials or coated with such materials. Electrically insulating materials can be, for example, various plastics, resins, foam materials, or similar materials.

[0039] According to a further embodiment, the electrically insulating component is designed as a sliding element to allow sliding between the arrangement of several fuel cells and the support structure.

[0040] Such a sliding plane, the arrangement of which has already been described above, enables elements of the support structure located between the prefabricated element and the array of multiple fuel cells to slide against each other or generally shift relative to each other in the stacking direction. This prevents longitudinal loads acting on the individual fuel cells along the stacking direction, as the prefabricated element and the remaining elements of the support structure can align relative to each other along the stacking direction in such a way that no such forces are exerted.

[0041] According to a further embodiment, the support structure is in surface contact with the arrangement of several fuel cells.

[0042] In particular, the preformed element of the support structure itself can press against the arrangement, for example if the preformed element is a resilient element, as described above. However, the preformed element can also hold other elements of the support structure, such as the electrically insulating component described above, the compression device, or the compressible component, between the preformed element and the corresponding side surface of the arrangement of several fuel cells in such a way that these enclosed elements press against the side surface and accordingly introduce the prestress. The latter alternative is conceivable, for example, if the preformed element is a rigid element. However, the support structure can also be in surface contact with the arrangement of several fuel cells through a combination of these alternatives.For this purpose, the preformed element can be in direct surface contact with the array of multiple fuel cells at some points and in other areas, via additional intervening elements, in surface contact with the array. It is also conceivable that the support structure is in surface contact with the array of multiple fuel cells only at some points (particularly at particularly stressed areas).

[0043] According to a further embodiment, the arrangement of a plurality of fuel cells comprises a plurality of cell components. The cell components each have a peripheral edge that has at least one first contact section, which is shaped to correspond to a second contact section of the support structure, so that the first contact section and the second contact section can be brought into flush surface contact.

[0044] The cell components can be, for example, bipolar plates, seals, or other cell components. In embodiments with a center plate, such a center plate can also be configured accordingly. However, it should be noted that the center plate is not a cell component, but a separate mechanical element in the cell stack that is stacked next to the cell components. The fact that the first contact section and the second contact section are shaped correspondingly means in particular that, viewed in a cross-section, the first contact section has a negative shape of the second contact section, so that the first contact section and the second contact section fit together in such a way that the support structure prevents lateral displacement of the bipolar plates.Furthermore, as described above, electrically insulating components, sliding elements, compression devices, and other intermediate layers can also be provided here in order to achieve the effects described above with regard to these elements.

[0045] Furthermore, the second contact section can be designed as a single or two-part structure. In a two-part design, the support structure is thus at least partially bipartite. A one-part design, on the other hand, allows for smaller support structure thicknesses and greater flexural rigidity.

[0046] According to a further embodiment, the first contact portion and the second contact portion are bevelled.

[0047] A bevel here means in particular that the surfaces of the contact sections do not run parallel to the general lateral extent of the bipolar plates (i.e. to the direction of extension of the bipolar plates which together define the lateral surface of the arrangement of a plurality of fuel cells), but have at least an angle other than 0° to this direction. For example, the first contact section can form a wedge with respect to the direction of the lateral extent. The second contact section can define a corresponding recess in the support structure into which the first contact section fits. The wedging effect thus achieved effectively prevents lateral displacement both perpendicular to the lateral surface along which the support structure runs and parallel thereto.

[0048] According to a further embodiment, the support structure comprises a compression device for the fuel cell stack and exerts a pressing force on the arrangement of multiple fuel cells in the stacking direction. The compression device can, for example, be a band or another suitable device. Such a band can, for example, be tensioned substantially along the stacking direction. In particular, if such a band is made of a pliable material, sufficient prestressing can be achieved, for example, by an intermediate compressible component, as described above, which is pressed against the side surface by the band.

[0049] According to a further embodiment, an elastic intermediate layer is arranged between the support structure and the arrangement of a plurality of fuel cells in order to improve the surface fit and thus to equalize (evenly distribute) a compressive force exerted by the support structure on the arrangement of a plurality of fuel cells.

[0050] Such an elastic intermediate layer can adapt to deviations in the corresponding side surface from the perfectly flat shape and thus, among other things, compensate for inaccuracies in the stacking of the individual fuel cells. This allows the variation in the compressive force / contact force caused by such inaccuracies to be compensated.

[0051] According to a further embodiment, the fuel cell stack further comprises a sliding intermediate layer which can be bonded to the elastic intermediate layer and is designed to slide on the support structure.

[0052] Since the sliding intermediate layer can be bonded to the elastic intermediate layer, the latter cannot shift relative to the elastic intermediate layer along the stacking direction. However, due to the sliding ability with respect to the support structure (or with respect to the preformed element of the support structure), a sliding plane is formed parallel to the corresponding side surface of the preformed element. This makes it possible to compensate for linear expansions or fluctuations along the stacking direction, which may occur, for example, due to temperature and / or pressure differences inside the stack, as well as for relative movements in the stacking direction when the stack vibrates. The elastic intermediate layer also enables lateral compensation of composition inaccuracies, as described above.According to a second aspect, a method is provided for mounting a lateral support structure to a fuel cell stack comprising an array of multiple fuel cells stacked in a stacking direction and two end plates defining the array and arranged opposite one another in the stacking direction. The support structure comprises at least one elastic preformed element. The method comprises the following steps: attaching a mounting frame to each of the preformed elements. Clamping each of the preformed elements from a rest position to a tensioned position. Fastening the at least one preformed element on opposite sides of the fuel cell stack. The method further comprises releasing the mounting frame so that the at least one preformed element is forced back to its rest position, thereby exerting a lateral clamping force on the array of multiple fuel cells.The lateral clamping force supports the arrangement of several fuel cells laterally.

[0053] Preferably, the preformed element is a resilient element, such as a clamp-like element, which has a rest position or bent initial position (i.e., in a state without external force, the element is in a bent shape). When the preformed element is brought out of this rest position by bending, it exerts a restoring force which forces the preformed element back into the rest position. Before assembly, the preformed element is placed into a tensioned position by appropriate deformation or bending. This tensioning can take place, for example, in a pressing device or, as described below, with a pulling tool or in another way after connection to the assembly frame.

[0054] The mounting frame is fastened to the preformed element (in particular on the side which, in the installed state, faces away from the fuel cell stack, i.e. on a concave region of the preformed element). The mounting frame holds the preformed element at the ends in the stacking direction. In addition, the mounting frame holds the preformed element firmly in at least one region between the ends (inner region). Each of these regions can be held, for example, by an arm of the mounting frame. In addition, a pulling tool of the mounting frame can optionally be located on the inner region or on the corresponding holding arm (as described above). The pulling tool can, for example, be a spindle or another linear actuator which enables the inner region to be pulled outwards towards the mounting frame.Since the preformed element is held at its ends in the mounting frame, the pulling tool pulls the inner area straight, creating a restoring force from the preformed element. However, it should be noted that such a pulling tool merely represents one way to clamp the preformed element. In particular, the preformed element can also be clamped before connecting it to the assembly tool, for example, in a suitable press, and only then connected to the mounting frame.

[0055] Subsequently, as described above with respect to the fuel cell stack, the remaining components of the support structure can optionally be attached to the preformed element. For example, various electrically insulating components, sliding elements, compression devices, compressible components, etc., as described herein, can be attached to the support structure. Such elements can be provided either continuously along the stacking direction or only in certain places, particularly in areas that are subject to particular stress during operation, i.e., particularly prone to deflection of the fuel cell stack.

[0056] Once the support structure has been fully pre-assembled, it is guided to the fuel cell stack using the mounting frame, and the ends of the support structure or of the pre-formed elements are fastened, i.e. the at least one pre-formed element is guided and fastened to opposite side surfaces of the arrangement of multiple fuel cells. If only one pre-formed element is used, it will of course only be fastened to one side surface of the arrangement. If, for example, two pre-formed elements are used, they are fastened to two opposite side surfaces, etc. The ends can be fastened, for example, to the end plates of the fuel cell stack or to a surrounding structure connected to the fuel cell stack (for example a base plate), using any suitable type of fastening (such as welding, riveting, screwing, or gluing).

[0057] After the preformed elements have been guided and secured to the opposite sides of the fuel cell stack, the corresponding mounting frames are released synchronously or step by step. For this purpose, for example, the corresponding pulling tools are released / opened either simultaneously or step by step, or the mounting frames themselves are removed step by step. Such synchronous release of the pulling tools prevents displacement of the assembly of multiple fuel cells, as the restoring forces caused by the opposing elastic preformed elements returning to their rest position at least approximately balance each other out at all times, thus resulting in a zero lateral force on the assembly.When the preformed elements move back to the rest position, they press on the corresponding side surfaces due to the attachment at the ends to the fuel cell stack (or a surrounding structure) and support the fuel cell stack.

[0058] Now the mounting frames are completely removed from the prefabricated elements.

[0059] In summary, the invention provides a fuel cell stack having a lateral support structure. The support structure prevents lateral slippage of individual fuel cells within the fuel cell stack or bending / deformation of the stack, which can occur particularly in highly dynamic environments, such as aircraft, due to the various forces and vibrations. However, it should be recognized that the fuel cell stack can also be advantageously used in other environments, such as motor vehicles, trains, etc. The support structure reliably prevents undue deformation or damage to the fuel cell stack in such high-load environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The following examples are described in more detail with reference to the accompanying drawings. The illustrations are schematic and not to scale. Like reference numerals refer to like or similar elements. They show:

[0061] Fig. 1 A schematic representation of a fuel cell stack according to the state of the art.

[0062] Fig- 2 A schematic representation of a possible deflection in a fuel cell assembly without a support structure.

[0063] Fig- 3 A highly schematic representation of a fuel cell stack with a support structure and the effect of the support structure when deflection occurs.

[0064] Fig- 4 A schematic representation of a cross section through a fuel cell stack with an exemplary support structure.

[0065] Fig. 5 A schematic representation of a sub-element of a fuel cell and its contact with a support structure.

[0066] Fig. 6 A schematic side view of a fuel cell stack with an exemplary support structure and a cross-sectional view through the fuel cell stack in a plan view, illustrating the contact of the support structure with a sub-element of the fuel cell stack.

[0067] Fig. 7 A schematic side view of a fuel cell stack with a further exemplary support structure and a cross-sectional view through the fuel cell stack in a plan view, which illustrates the contact of the support structure with a sub-element of the fuel cell stack.

[0068] Fig- 8 Two schematic side views from mutually perpendicular perspectives of a fuel cell stack with a support structure with a resilient element.

[0069] Fig- 9 Schematic representations of the resilient element from Fig. 8 in three states.

[0070] Fig. 10 A schematic flow diagram of a method for mounting a support structure with a resilient element to a fuel cell stack by means of a mounting frame.

[0071] Fig- 11 A schematic side view of a fuel cell stack with a support structure with a compressible component which is slidably connected in the vertical direction to a rigid support or a resilient element.

[0072] Fig. 12 A schematic view of the layer structure of the support structure from Fig. 11.

[0073] Fig. 13 A schematic side view of a fuel cell stack with a support structure with a protective layer or with a sacrificial material, which is slidably connected in the vertical direction to a rigid holder or a resilient element.

[0074] Fig. 14 A schematic view of the layer structure of the support structure from Fig. 11. DETAILED DESCRIPTION OF EMBODIMENTS

[0075] Fig. 1 shows a fuel cell stack 2 from the prior art, without a support structure. The fuel cell stack 2 comprises a first end plate 4 and a second end plate 6. Between the first end plate 4 and the second end plate 6, an arrangement 8 of a plurality of fuel cells is stacked on top of one another in a stacking direction 10 and is held together by the first end plate 4 and the second end plate 6, for example by a compression force exerted by the end plates 4, 6, which acts in the stacking direction 10. The fuel cell stack 2 is arranged vertically in Fig. 1, i.e. the fuel cells of the arrangement 8 are stacked in a vertical direction (from bottom to top).

[0076] Fig. 2 illustrates the problem with a fuel cell stack 2 according to Fig. 1 (or a similar fuel cell stack from the prior art), from which the present invention is based. The fuel cell stack 2 is arranged horizontally here, so that the surface planes of the individual fuel cells of the arrangement 8 run vertically and the gravitational vector 61 acts in or along the respective surface planes. The fuel cells in the arrangement 8 are pressed together by the end plates 4, 6 by a clamping force 60 acting along the stacking direction 10 (Fig. 1).

[0077] The upper part of Figure 2 shows the fuel cell stack in a first state (a), which corresponds to the state before operation began. Here, the fuel cells of the assembly are still arranged neatly next to each other, as intended, without any relative lateral displacement.

[0078] State b illustrates the fuel cell stack 2 immediately after the start of operation. Operation, for example in an aircraft, causes vibrations 62 within the arrangement 8 of fuel cells. At the same time, the gravitational vector 61 acts perpendicular to the stacking direction 10 of the arrangement 8. Instead of or in addition to the gravitational force, however, other forces, such as centrifugal forces during the flight of an aircraft, can also act. Due to the vibrations 62 and the force 61, the arrangement 8 of fuel cells bends over time in the direction of the force 61, as the individual fuel cells of the arrangement 8 shift relative to one another perpendicular to the stacking direction 10. This is shown in state c, which indicates the state some time after the start of operation. Such bending can, as is easily apparent, lead to damage to the fuel cell stack 2.

[0079] Fig. 3 shows a highly schematic view of a fuel cell stack 12 which, compared to the fuel cell stack 2 in Fig. 1, is extended by a support structure 14. The support structure itself is not shown in Fig. 3, but can be attached to the end plates 4, 6 of the fuel cell stack 12 and run along the stacking direction 10 (see Fig. 1) of the arrangement 8 of fuel cells. The support structure 14 runs along two side surfaces 7, 9 of the fuel cell stack 12. Although the support structure can be attached to the end plates 4, 6 and run between them, it should be recognized that the support structure can also be attached in other ways. For example, the support structure can also be attached to a structure carrying the fuel cell stack 12. Fig. 3 also schematically illustrates the effect of such a support structure 14 (Figs. 4 to 14), which can be constructed according to any of the embodiments described further below with reference to Fig.4 to 14 described embodiments.

[0080] The left side of Fig. 3 illustrates the fuel cell stack 12 with the tie rods 22, which are common in the prior art, before the fuel cells begin to slip within the assembly 8. Here, the individual fuel cells are still neatly stacked on top of each other without any relative lateral displacement.

[0081] The middle part of Fig. 3 shows the fuel cell stack 12 after a similar lateral slippage transverse to the stacking direction 10 has begun. The fuel cells of the arrangement 8, or the side surface 7 of the arrangement 8, which have shifted laterally (here to the left), move in the direction of the tie rods 22, which can unduly reduce the distance to the tie rods 22. The right side of Fig. 3 shows the force effect of the (not shown) support structure 14 and the arrangement 8 of several fuel cells, whereby the support structure 14 is not shown for better visibility of the force effect. When the individual fuel cells press against the support structure with a certain displacement force 63, the support structure generates a counterforce 64, which counteracts the displacement of the fuel cells in the direction of the tie rods 22.As soon as the forces 63 and 64 are in equilibrium, no further displacement of the fuel cells can occur transversely to the stacking direction 10.

[0082] Fig. 4 shows a cross-section through an exemplary fuel cell stack 12 with a support structure 14, which is divided into six substructures (three on each side). The cross-section shows a sectional plane perpendicular to the stacking direction 10 in Fig. 1. The view represents a plan view of, for example, one of the bipolar plates 16 of the fuel cell stack 12, which is located in the fuel cell stack 12. Three substructures of the support structure 14 are provided on each of the side surfaces 7 and 9, thereby preventing individual fuel cells or elements of individual fuel cells from slipping out of the stack in the direction of both side surfaces 7, 9.Between each part of the support structure 14 and the fuel cell stack 12, there is also a compression device 22 (these are typically tension rods, which can be designed as a screw, band, or similar), which here is implemented in the form of a band 22 running along the stacking direction 10, and an electrically insulating component 24, which can optionally be designed as a sliding element 24. The support structure 14 itself is made of a mechanically strong and essentially rigid material, such as a metal. The support structure can comprise both rigid elements and the prestressed resilient elements described herein. Such a resilient element is of course not rigid, since it applies the prestress for the fuel cell stack precisely through the introduced bending stress. In the embodiments of Fig.11 and 13, however, elements 30 and 40 may be rigid elements.

[0083] In order to prevent short circuits in the fuel cell stack 12, which could occur, for example, if two or more cells were electrically connected to one another by the compression device 22, the electrically insulating component 24 is provided between the compression device 22 and the arrangement 8 of several fuel cells. This component, which is required anyway, can be designed in such a way that, in addition to the main requirement, namely the insulation of the compression device, it also functions as a sliding element, so that the requirements for the application of a support structure can also be met. This prevents direct contact between the support structure 14, or the electrically conductive components of the support structure 14, and the components of the fuel cells (for example, the bipolar plates). The compression device can, for example, be a circumferential belt that encloses the fuel cell stack.The support structure 14 presses the compression device 22 on the side surfaces 7, 9 against the arrangement 8 of multiple fuel cells. The support structure 14 can, for example, comprise generally preformed elements 30, 40, which can be designed, for example (as shown in Figs. 6 to 10), as resilient elements 30, or also as rigid elements, as in Figs. 11 to 14. However, it should be noted that the elements 30, 40 in Figs. 11 to 14 can also be resilient elements. These preformed and / or resilient elements 30 laterally clamp the fuel cell stack 12, as described above, thereby achieving a lateral supporting effect.

[0084] Figs. 5 and 6 show a fuel cell stack 12 with a support structure 14, wherein the support structure 14 is in surface contact with the arrangement 8 of several fuel cells. Figs. 5 and 6 are described together below. Fig. 5 and the upper portion of Fig. 6 show a cell component 16 (or one side of a bipolar plate 16) in the fuel cell stack 12 in a plan view. This means that Fig. 5 and the upper portion of Fig. 6 show a section through the fuel cell stack 12 shown in the lower portion of Fig. 6 into the plane of the drawing.

[0085] It should be noted that, although Figures 5 and 6 illustrate a beveled contact surface between the support structure and the cell components 16, engagement of the support structure may also occur without such a beveled contact surface or, in general, without a feature explicitly formed on the cell components 16. For example, the support structure may also be in straight surface contact with the cell components 16. However, it is conceivable that the engagement regions may have to be specially designed, so that the force absorption of individual, partially deformable or easily damaged, cell components 16 could require a special design solution. However, this is not absolutely necessary for the subject matter of the present disclosure and is not to be interpreted in a restrictive manner.

[0086] The cell component 16 in Figs. 5 and 6 has a first contact portion 26, which is shaped to correspond to a second contact portion 28 of the support structure 14. In other words, the cell component 16 has a projection or a wedge (first contact portion 26) shaped to fit into a corresponding recess of the second contact portion 28, so that the first contact portion 26 and the second contact portion 28 can be brought into flush surface contact.

[0087] In the illustrated configuration, both the first contact section 26 and the second contact section 28 are chamfered. However, it should be recognized that the first contact section 26 and the second contact section 28 can also be configured to correspond to one another in other ways, such as with appropriately designed grooves and projections, and not exclusively via a chamfer as shown. Due to the chamfer, the support structure 14 supports the fuel cell stack 12 in both directions perpendicular to the stacking direction 10. In Figs. 5 and 6, the second contact section 28 is split in two, with a first segment 28a and a second segment 28b of the second contact section. The use of a split second contact section 28 improves the compensation of CRA (Cell Row Assembly, CRA) tolerances.In particular, the use of a single, continuous element instead of two increases the bending stiffness and thus the area moment of inertia due to the connection of the two elements with additional material. However, this can also prove detrimental to the compensation of stack tolerances in the event of tilt or misalignment of the end plates or the stack. Tilts can possibly be compensated more easily with two individual elements than with one element. A corresponding design can therefore be selected depending on the requirements and these factors. Although shown and described here with reference to a cell component 16, it should be recognized that other elements of the fuel cell, such as sealing elements or other cell components, can also be equipped with corresponding first contact portions 26.

[0088] The second contact section 28 can, for example, be a preformed element 30 in the form of a resilient element 30, as described further below with reference to Figs. 8 to 10. In addition, further elements or layers can be arranged between the first contact section 26 and the second contact section, such as the sliding elements described herein, electrically insulating components, etc. For example, the layer structure at the contact surfaces between the first contact section 26 and the second contact section 28 can correspond to the structure shown in Figs. 11 and 12 or in Figs. 13 and 14. However, it is also conceivable for the second contact section 28 itself to be formed, for example, from an electrically insulating material with sufficient rigidity.

[0089] Fig. 7 shows a further configuration of a fuel cell stack 12, which differs from the configuration in Figs. 5 and 6 in that the second contact section 28 is designed as a single piece in a type of “suspender shape.” This design allows the thickness of the second contact section 28 to be reduced, since a single-piece construction increases the mechanical stability of the support structure 14 overall. However, both the single-piece and the two-piece construction of the second contact section 28 fulfill the intended supporting effect. The comparison of the mechanical stability of the single-piece construction to the two-piece construction is schematically visible on the right-hand sides of Figs. 6 and 7. It should be recognized that the continuous contact section can optionally also be present along the entire stacking direction 10, and not just in a central region, as shown.

[0090] Figures 8 and 9 show a preformed element 30 configured as a resilient element 30. The preformed element 30 is thus made of an elastic / resilient material, such as a metal. Figure 8 shows the preformed element 30 installed in the fuel cell stack 12. Figure 9 shows the preformed element 30 in three different bending states.

[0091] One or more such preformed elements 30 can be used, for example, as second contact sections 28 in the support structures shown in Figs. 5 to 7. Furthermore, such preformed elements 30 can also be used in the support structure 14 in Fig. 4 (triangles in Fig. 4). Fig. 8 shows two preformed / resilient elements 30 in a side view of the fuel cell stack 12 (left side) and in a front view of the fuel cell stack (right side) in an installed state. Here, too, it should be recognized that further functional intermediate layers, such as those described below with reference to Figs. 10 to 14, can be present between the preformed components 30 and the arrangement 8 of several fuel cells.

[0092] In the illustrated configuration, the preformed elements 30 are attached to the end plates 4, 6 and are arranged on opposite side surfaces 7, 9 of the fuel cell stack 12. The preformed elements 30 therefore exert a bilateral supporting effect (force arrows F) on the assembly 8, since the preformed elements 30, when installed, are bent into a position that differs from their respective rest position. On the right side of Fig. 8, it is visible that the preformed elements 30 can serve, for example, as second contact sections 28 of the support structure 14, as described with reference to Fig. 7.

[0093] To illustrate the effect of such preformed elements 30, Fig. 9 shows such a preformed element 30 in three different bending states. The middle image of Fig. 9 shows the preformed element 30 in its rest position (initial position, without the effect of an external force). On the left and right sides of Fig. 9, the preformed / resilient element 30 is deflected / straightened from the rest position to various degrees. In these bending states, the preformed element pushes back into the rest position shown in the middle. When the preformed element 30 is installed and connected to the fuel cell stack 12 in a deflected position, as shown in Fig. 8, the ends of the preformed element are fixed.The preformed element therefore introduces a lateral prestress into the fuel cell stack 12 when attempting to bend back to the rest position, which counteracts any deformation of the fuel cell stack 12 (such as lateral displacement of the individual fuel cells relative to one another or any other deformation of the stack as a whole), as described in detail above.

[0094] Figure 10 shows a sequence of steps of a method 100 for assembling a support structure 14 to a fuel cell stack. In step A, at least two preformed elements 30 are provided (steps A to E each show only one preformed element 30. A second or more additional elements can be prepared in parallel or subsequently in the same manner before step F is performed).

[0095] In step B, a respective mounting frame 32 is attached to the preformed element 30. The mounting frame 32 can, for example, be attached to the preformed element 30 with corresponding arms, as shown. In particular, the mounting frame 32 is releasably fixed to the preformed element 30 at the outer ends (top and bottom in Fig. 10). At least a third arm can be releasably attached to an inner region of the preformed element 30. In the illustrated embodiment of the method, the third arm also has a pulling tool 34, which serves to pull the central region toward the mounting frame 34 and thereby introduce a preload into the preformed element 30. The pulling tool 34 can be any suitable tool, such as a pull spindle or any other suitable linear actuator. Furthermore, the pulling tool 34 can also be omitted entirely.The deformation could then take place, for example, in a suitable press before the preformed element 30 is attached to the mounting frame, and the fixation would then be achieved by the mounting frame. In such embodiments, however, a spindle could still be used for unloading or preloading (fine adjustment in the preloaded state). The preloading mechanism could then be realized with less stroke and therefore be easier to implement. The mounting frame 34 is attached to the concave side of the preformed element 30 so that the pulling tool, when actuated, pulls the preformed element 30 straight, thereby inducing tension in the preformed element 30, which leads to a restoring force.

[0096] In steps D and E, further components, such as sliding elements (not shown), electrically insulating components 24, , and other elements as described herein, can then be gradually attached to the preformed element 30. However, such elements do not necessarily have to be mounted in the tensioned state. It is also conceivable for such elements to be attached to the preformed element 30 in the untensioned state. For example, segments that ensure direct engagement with the stack surface can be applied to the prestressed and preformed element 30. For example, one of the layer structures of Figs. 11 and 12 or Figs. 13 and 14 can be implemented.

[0097] After the preparation in steps D and E, the prepared support structures 14 (comprising the prefabricated elements 30 and the additional elements 22, 24, etc.) are attached to the fuel cell stack by attaching the preformed elements 30. For example, the preformed elements can be connected at the ends to the end plates 4, 6.

[0098] Furthermore, in step G (not shown), the pulling tools 34 (or corresponding spindle or other tools if no pulling tool is used on the mounting frame) on the opposite sides of the support structure 14 are released synchronously or alternately and step by step, and the mounting frames 34 are released from each of the preformed elements 30. Since the support structure 14, or its preformed elements 30, were fixed with the end plates 4, 6 in a position deflected from the rest position, the restoring force presses against the arrangement 8 of several fuel cells after the mounting frames are released, thus laterally stabilizing the structure.

[0099] 11 and 12 show a first layered structure of a support structure 14, 38. In this structure, a rigid holder 40 runs parallel along the stacking direction 10. However, instead of a rigid holder 40, a preformed / resilient element 30, as described above, can also be used. In other words, the layered structure described here can also be implemented in the support structures 14 described above with reference to the prefabricated element 30. It should be noted that the described structure can be present symmetrically on opposite side surfaces of the arrangement 8 of several fuel cells. An electrically insulating component 42, which can be made, for example, from a plastic or another electrically non-conductive material, is arranged directly adjacent to the rigid holder 40 (or the prefabricated element 30).Another electrically insulating component 44 is arranged further inward, adjacent to the electrically insulating component 42. The electrically insulating component 42 has high friction / adhesion, for example, by bonding, to the rigid support 40 (or the preformed element 30) and low friction to the electrically insulating component 44, which allows these components to slide against each other along a sliding plane 70. The components 42, 44 are therefore also referred to as sliding elements 42, 44.

[0100] A compressible component 46, such as a fluid-filled cushion or a foam element, is arranged between the sliding element 44 and the arrangement 8 of multiple fuel cells. As shown in Fig. 12, the compressible component 46 can also be integrated into the sliding element 44. The compressible component 46 exhibits high friction with the arrangement 8 of multiple fuel cells, or with its side surface, and is fixed to the sliding element 44. The compressible component thus compensates for unevenness or inaccuracies or cell positioning tolerances, while the sliding mechanism implemented by the sliding elements 42, 44 enables sliding along the sliding plane 70 and thus, for example, also compensates for expansions / contractions of the fuel cell stack 14, 38 due to temperature and / or pressure differences.In this way, damage to the fuel cell stack caused by the support structure 14, 38 can be avoided, while simultaneously providing lateral support, which prevents damage to the fuel cell stack due to deflection. The compressible component 46 also protects soft elements of the support structure 14, 38, such as the sliding elements 42, 44, from damage caused by sharp edges of the fuel cell components.

[0101] It should be noted, however, that this arrangement or design of the individual components as elastic or rigid, as well as electrically insulating or non-insulating, is merely exemplary. For example, it is also conceivable to cast the side surface instead of element 46 with a filler material, such as a resin, which provides a common (flat) surface for the individual cell components. In order to introduce the necessary prestress, one of the elements 42, 44 can then, for example, be compressible / elastic. However, at least one of the elements 42, 44 must then be rigid so that a sliding plane is formed. The sliding plane can be formed between elements 40 and 42, between elements 42 and 44, or between elements 44 and 46. Generally, a sliding plane is always formed between two rigid elements. In addition, electrical insulation must always be achieved between the individual fuel cells.It must be avoided as an electrically conductive connection / bridge between the individual fuel cells. Any combination of elements 42, 44, and 46 that meets these requirements is conceivable. Furthermore, individual layers can be omitted entirely, as long as it is ensured that at least one slip plane is formed and the necessary prestress is applied.

[0102] 13 and 14 show another possible layered structure of a support structure 14, 50. This layered structure can also be used in the support structure 14 described above with the preformed element 30 or in a support structure 50 with a rigid holder 40. Here, a sliding plane 70 is defined between the rigid holder 40 (or the preformed element 30) and a sliding intermediate layer 56. The sliding intermediate layer can be made, for example, from a plastic or another electrically insulating material and enables sliding on the rigid holder 40 (or the preformed element 30) at the sliding plane 70. An elastic intermediate layer 52 enables lateral compensation of inaccuracies, similar to the compressible component 46 from FIGS. 11 and 12. In the structure of FIGS. 13 and 14, a protective layer 54 is also provided.The protective layer 54 can, for example, be a material that is very mechanically resistant, in particular resistant to cuts. This protects softer components of the layer structure from damage caused by sharp edges. Alternatively, the protective layer 54 can, for example, also be a sacrificial material 54 that can be damaged by the fuel cells (i.e. that can be cut into to a certain extent by the cell components, thereby providing a common contact surface between the cell components and the support structure) and thus prevents damage to the components further out. The protective layer 54 is also electrically insulating, thus preventing short circuits. The support structure 14, 50 of Figs. 13 and 14 is also arranged symmetrically on opposite side surfaces of the arrangement 8 of several fuel cells, thereby achieving a lateral supporting effect.The elements 52, 54 in Figs. 13 and 14 essentially perform the same function as the compressible component 46 of Figs. 11 and 12.

[0103] Additionally, it should be noted that "comprising" or "having" does not exclude other elements or steps, and "a" or "an" does not exclude a plurality. Furthermore, it should be noted that features or steps described with reference to one of the above embodiments may also be used in combination with other features or steps of other embodiments described above. Reference signs in the claims are not to be considered as limitations.

[0104] LIST OF REFERENCE SYMBOLS

[0105] 2 fuel cell stacks (state of the art, without support structure)

[0106] 4 first end plate

[0107] 6 second end plate

[0108] 7 Side surface

[0109] 8 Arrangement of several fuel cells

[0110] 9 Side surface

[0111] 10 Stacking direction

[0112] 12 fuel cell stacks

[0113] 14 Support structure

[0114] 16 Bipolar plate, cell components

[0115] 18 Flow field

[0116] 20 Rand

[0117] 22 Compression device (band), tension rod

[0118] 24 electrically insulating component / sliding element

[0119] 26 first contact section

[0120] 28 second contact section

[0121] 28a, 28b Segments of the second contact section

[0122] 30 spring element / preformed element

[0123] 32 mounting frames

[0124] 34 pulling tool

[0125] 36 Connection

[0126] 38 Support structure

[0127] 40 rigid bracket

[0128] 42 electrically insulating component / sliding element

[0129] 44 electrically insulating component / sliding element

[0130] 46 compressible components

[0131] 48 membrane electrode assembly

[0132] 50 support structure

[0133] 52 elastic interlayer

[0134] 54 protective layer, sacrificial material 56 sliding intermediate layer

[0135] 58 Support structure

[0136] 60 clamping force

[0137] 61 Gravitational vector

[0138] 62 vibrations

[0139] 63 Displacement force

[0140] 64 Counterforce

[0141] 70 Slip plane a Condition before start of operation b Condition immediately after start of operation c Condition after some time of operation

[0142] 100 Methods for assembling a support structure

[0143] A Providing preformed elements

[0144] B Attaching mounting frames

[0145] C Clamping the mounting frames

[0146] D, E Attaching additional elements of the support structure

[0147] F Attaching prefabricated elements to fuel cell stacks

[0148] G synchronous release of the mounting frames

Claims

Patent claims 1. Fuel cell stack (12), comprising: - an arrangement (8) of several fuel cells stacked in a stacking direction (10), - two end plates (4, 6) limiting the arrangement (8) and arranged opposite each other in the stacking direction (10), and - a support structure (14, 38, 50, 58) extending along at least one side surface (7, 9) of the arrangement (8) and at least between the end plates (4, 6), wherein the support structure (14, 38, 50, 58) is configured to support the fuel cells transversely to the stacking direction (10) in order to counteract deformation of the arrangement (8) of several fuel cells; wherein the support structure (14, 38, 50, 58) has a preformed element (30, 40) such that the support structure (14, 38, 50, 58) exerts a prestress on the arrangement (8) of several fuel cells in an assembled state; wherein the prestress acts on the arrangement (8) of several fuel cells transversely to the stacking direction (10).

2. Fuel cell stack (12) according to claim 1, wherein the support structure (14, 38, 50, 58) extends along at least one pair of two opposing side surfaces (7, 9) of the fuel cell stack (12).

3. Fuel cell stack (12) according to claim 1 or 2, wherein the support structure (14, 38, 50, 58) is designed to support the fuel cells in two spatial directions extending transversely to the stack direction (10).

4. Fuel cell stack (12) according to one of the preceding claims, wherein the support structure (14, 38, 50, 58) is arranged on the end plates (4, 6) or can be attached to a base supporting the fuel cell stack (12).

5. Fuel cell stack (12) according to one of the preceding claims, wherein the support structure (14, 38, 50, 58) includes at least one resilient element (30) exhibits which pushes transversely to the stacking direction (10) onto at least one side surface (7, 9) of the arrangement (8) of several fuel cells.

6. Fuel cell stack (12) according to one of the preceding claims, wherein the support structure (14, 38, 50, 58) comprises at least an arrangement of a rigid support (40) and a compressible component (46), and wherein the compressible component (46) is arranged between the relevant side surface (7, 9) of the arrangement (8) of several fuel cells and the rigid support (40).

7. Fuel cell stack (12) according to claim 6, wherein the compressible component (46) comprises a fluid-filled cushion or a foam.

8. Fuel cell stack (12) according to one of the preceding claims, wherein the support structure (14, 38, 50, 58) consists of an electrically insulating material or is coated with an electrically insulating material, or wherein at least one electrically insulating component (24, 42, 44, 56) is positioned between the support structure (14, 38, 50, 58) and the arrangement (8) of several fuel cells.

9. Fuel cell stack (12) according to claim 8, wherein the electrically insulating component (24, 42, 44, 56) is designed as a sliding element to allow sliding between the arrangement (8) of several fuel cells and the support structure (14, 38, 50, 58).

10. Fuel cell stack (12) according to one of the preceding claims, wherein the support structure (14, 38, 50, 58) is connected with the arrangement (8) of several Fuel cells are in surface contact.

11. Fuel cell stack (12) according to claim 10, wherein the arrangement (8) of several fuel cells comprises several cell components (16) exhibits, and wherein the cell components (16) each have a circumferential edge (20) which has at least a first contact section (26) which is shaped correspondingly with a second contact section (28) of the support structure (14, 38, 50, 58) such that the first contact section (26) and the second contact section (28) can be brought into flush surface contact.

12. Fuel cell stack (12) according to claim 11, wherein the first contact section (26) and the second contact section (28) are chamfered.

13. Fuel cell stack (12) according to one of the preceding claims, wherein the support structure (14, 38, 50, 58) has a compression device (22) for the fuel cell stack (12) and exerts a pressing force extending in the stack direction (10) on the arrangement (8) of several fuel cells.

14. Fuel cell stack (12) according to one of the preceding claims, wherein an elastic intermediate layer (52) is arranged between the support structure (14, 38, 50, 58) and the arrangement (8) of several fuel cells to equalize a pressure force exerted by the support structure (14, 38, 50, 58) on the arrangement (8) of several fuel cells.

15. Fuel cell stack (12) according to claim 14, further comprising a sliding intermediate layer (56) which is bondable to the elastic intermediate layer (52) and is designed to slide on the support structure (14, 38, 50, 58).

16. Method (100) for mounting a lateral support structure (14, 38, 50, 58) to a fuel cell stack (12), wherein the fuel cell stack (12) comprises: an arrangement (8) of several fuel cells stacked in a stacking direction (10); and two supports limiting the arrangement (8) and mutually abutting each other in the stacking direction (10). oppositely arranged end plates (4, 6); wherein the support structure (14, 38, 50, 58) comprises at least one elastically preformed element (30); wherein the method (100) comprises the following steps: attaching (B) a mounting frame (32) to each of the at least one preformed element (30); Clamping (C) each of the preformed elements (30) from a rest position into a clamped position; Attaching (F) the at least one preformed element (30) to opposite sides of the end plates (4, 6); Releasing (G) the mounting frame (32) so that the at least one preformed element (30) is pushed back into its rest position and exerts a lateral clamping force on the arrangement (8) of several fuel cells, which laterally supports the arrangement (8) of several fuel cells.

Images