Fuel cell stack end plate and end plate manufacturing method

Abstract

The invention relates to an end plate (100) for a compressed fuel cell stack (200). The end plate (100) comprises a core (110) for providing stiffness to the end plate (100), the core being made of a core material and having a core stiffness. The end plate (100) further comprises an enclosure (120) having an enclosure surface (121) in contact with the fuel cell stack (200). The housing (120) is made of a housing material. The housing stiffness of the housing (120) is less than or equal to the core stiffness. The housing (120) is at least partially overmolded on the core (110). The invention also relates to a fuel cell stack (200) which is covered on at least one side by the end plate (100). The invention also relates to a method (500) for manufacturing said end plate (100).

Description

Technical Field

[0001] The present invention relates to an end plate for a compressed fuel cell stack, and a fuel cell stack comprising at least one such end plate. The present invention also relates to a method for manufacturing the end plate. Background Art

[0002] Applications that utilize fuel cell technology typically utilize fuel cell stacks. These stacks are typically assembled from multiple individual fuel cells electrically connected in series. Depending on the application, fuel cells can function as either fuel cells or electrolyzers, and may be based on proton exchange membrane (PEM) technology, solid oxide cell (SOC) technology, or other similar technologies.

[0003] In addition to the fuel cells, such stack assemblies may also include other components for mechanical support, cooling, or insulation. For example, a fuel cell stack includes end plates positioned on either side of the stack. These end plates typically provide structural support for the stack by applying pressure from both sides, thereby ensuring a hermetic seal between the components to prevent gas leakage or escape within the stack. The end plates are typically configured to receive bolts, screws, and other mechanical components used to compress the fuel cell stack.

[0004] A key aspect is that the end plates must compress the fuel cell stack to apply the required uniform contact pressure. For example, if the end plates apply uneven or insufficient compression, localized contact resistance can occur within the stack, potentially leading to hot spots within the stack. Furthermore, this can inhibit gas diffusion within the fuel cell or cause leaks.

[0005] In addition, in electrolyzer applications, the pressure is significantly higher, so the end plate needs to have higher stiffness than in fuel cell applications. For example, the hydrogen pressure of a PEM electrolyzer may reach more than 30 bar, while a PEM fuel cell stack generally operates at less than 4 bar.

[0006] The end plates also provide other functions for the fuel cell. For example, end plates are often used to supply reactant gases to the fuel cell. For this purpose, the end plates can be equipped with manifolds. Therefore, sealing is usually achieved on the surface of the end plates that contacts other components in the stack. For a reliable seal, the corresponding surface of the end plates must meet strict engineering requirements. For example, precise docking with the components is crucial. Other related applications include providing grooves in the end plates for accommodating bus plates, which are used to collect the current from the fuel cells. Therefore, the end plates generally also provide electrical insulation. In addition, the end plates and the bus plates can be designed with active or passive heating functions to ensure optimal performance, for example in cold climates.

[0007] Therefore, the end plate is not only crucial to the structural integrity of the fuel cell stack, but also has a significant impact on the electrical performance, safety and service life of the fuel cell. The above fully illustrates the overall importance of end plate design.

[0008] In the prior art, fuel cell end plates are generally provided as single injection-molded plastic parts. In order to meet mechanical, electrical and chemical requirements, these single injection-molded plastic parts are usually set to be large and complex, so a large material thickness is required. However, this makes it more difficult to strictly control the manufacturing tolerances of the end plates in terms of size and surface quality. This is because injection-molded parts with large material thickness are more susceptible to the adverse effects of warping and shrinkage than small parts, which may make it difficult to meet engineering requirements. The single-piece design makes surface finishing (especially secondary machining) difficult, and even impossible in some cases. In addition, due to the large size of the parts, the mold design also becomes complicated, so the mold cost is high. This leads to an increased risk of part defects, rising costs, and an increase in the weight of the fuel cell stack. Summary of the Invention

[0009] Therefore, an object of the present invention is to provide an end plate having a reduced material thickness while still providing structural support and electrical insulation, meeting engineering requirements, and being able to be manufactured in a mass production process such as injection molding.

[0010] The above problems are at least partially solved by the end plate of claim 1 , the fuel cell stack of claim 11 and the manufacturing method of claim 12 .

[0011] Further advantages and features of the present invention can be gathered from the dependent claims, the description, and the accompanying drawings. Features and details relating to the end plate according to the present invention naturally also apply to the fuel cell stack according to the present invention and the method according to the present invention, and vice versa, so that the disclosure of various aspects of the present invention is always and / or can be cross-referenced.

[0012] A first aspect of the present invention relates to an end plate for a fuel cell stack. The end plate is suitable for compressing a fuel cell stack. The end plate includes a core for providing rigidity to the end plate. The core has a core rigidity. The end plate also includes a cover, the cover including a cover surface that contacts the fuel cell stack. The cover has a cover rigidity that is less than or equal to the core rigidity. The cover is at least partially overmolded onto the core.

[0013] According to the invention, the fuel cell stack and its individual elements may also preferably be a PEM electrolysis stack or an AEM stack.The invention therefore also relates to an end plate for an electrolysis stack and a method for producing an end plate for a compressed electrolysis stack.

[0014] In other words, an end plate for a fuel cell stack is provided. The end plate is designed to provide sufficient structural support, for example, in a compressed fuel cell stack. The fuel cell stack may be, for example, a proton exchange membrane fuel cell (PEMFC) stack, a PEM electrolysis stack, or an AEM stack. The fuel cells of the fuel cell stack may operate as fuel cells and / or electrolysis cells. "End plate" may preferably refer to a plate covering one end of the fuel cell stack in the stacking direction. The end plate may be substantially flat. The end plate may have at least one substantially flat or planar side surface. Alternatively, the end plate may have two opposing substantially flat or planar surfaces, and they may be parallel to each other. Preferably, the extended height of the end plate may be less than its extended length and extended width. Preferably, the length and width of the end plate may extend within an extended plane.

[0015] The end plate stiffness is provided by the core of the end plate. Here, "stiffness" can preferably be a measure of an object's ability to resist deformation under mechanical load. The stiffness of a structure may depend on its cross-sectional profile, material, and / or load characteristics. Stiffness may be inherent to the structure. For example, stiffness may include bending stiffness, tensile stiffness, torsional stiffness, and / or tangential stiffness.

[0016] The end plate includes a housing having a housing surface for contacting the stack. "Contact" can refer to direct physical contact between different component surfaces. "Housing surface" can include all surfaces of the housing, such as edges, sealing surfaces, openings, holes, and / or busbar slots.

[0017] The shell is at least partially overmolded onto the core. Here, the term "overmolded onto" may refer to applying a first material (e.g., the shell material) to a second material (e.g., the core material) during a molding step. For example, the first material may not only at least partially cover the second material but also bond to the second material. Injection molding is preferably employed for this purpose. More specifically, overmolding or insert molding may be employed. During the molding step, a chemical and / or mechanical bond can be formed between the shell and the core.

[0018] Thus, by providing the end plate in the form of a hybrid with two different stiffnesses, the stiffness of the end plate can be increased without increasing the material thickness or the size. This stems in particular from the idea that, depending on the required function, specific sections of the end plate can be given a certain stiffness. This makes it possible to optimize the respective function of the individual sections of the end plate. According to the invention, the core can be regarded as the main reinforcement and has a higher stiffness than the shell. The shell can therefore only meet the minimum stiffness requirements. By overmolding one of the two onto the other, a synergistic effect of the advantages of the individual elements of the end plate is achieved, thereby reducing, in particular, the amount of material used, the manufacturing costs and the number of scrap pieces, and making it possible to increase the manufacturing tolerances and the strength of the component. Unlike a simple coating of the core, the shell produced in a molded manner provides additional mechanical support, electrical protection and chemical barrier and, together with the core, reinforces the overall function of the end plate.

[0019] This is because, for example, according to the above-described design, the core can be manufactured completely separately from the shell and designed according to its structural complexity. Since the shell is overmolded onto the core, the core is not required to be electrically insulating, so a wider range of material choices can be used for the optimization of the core. In addition, any defects in the core can be repaired by the shell during the overmolding process. Therefore, there is no need to adhere to strict core tolerances. Similarly, the requirement for stiffening the end plates can be ignored when selecting the shell material, because the core already acts as the main reinforcement. In addition, the design allows the shell surface to be used as a machinable surface, so that engineering requirements (such as strict manufacturing tolerances) can be met. In addition, the shell can have a reduced material size, so that the risk of warping or shrinkage of critical surfaces (such as sealing surfaces) can be reduced.

[0020] As a result, the size, footprint, weight, tolerances, cost and dimensions of the end plates are optimized.

[0021] According to a preferred embodiment, the core stiffness can be the stiffness of the core material, and the shell stiffness can be the stiffness of the shell material. These material stiffnesses can be the bending stiffness of the core material and the bending stiffness of the shell material. For example, the core stiffness can be at least three times, at least ten times, or even higher than the shell stiffness. However, this is merely an example and is not intended to be exhaustive.

[0022] The core thus acts as a primary reinforcement (eg, a load distribution plate) to maximize structural support while minimizing bending deformation.

[0023] According to another preferred embodiment, the end plate may comprise a single, one-piece, continuous structure. Alternatively or additionally, the cover may be overmolded onto the core such that at least one end of the core is covered by the cover surface. Alternatively or additionally, the cover may be overmolded onto the core such that the core is at least partially or completely covered along its periphery by the cover surface.

[0024] Thereby, the bonding strength between the shell and the core can be improved, and the shell surface can provide electrical protection and material barrier for the core.

[0025] According to a preferred embodiment, the housing surface can be configured to provide a sealing surface between the end plate and the components of the fuel cell stack when the end plate is mounted on the fuel cell stack. The housing material can be a compressible material and / or an electrically insulating material. Preferably, the housing material can include plastic, injection-molded thermoplastics, thermoformed plastics such as polyphenylene sulfide, composite materials comprising polystyrene and polyphenylene oxide, composite materials comprising polystyrene and polyphenylene ether, polyetheretherketone, or epoxy laminates. However, these are provided as examples only and are not to be considered exhaustive.

[0026] This allows contact surfaces for stack components to be provided in a configuration that meets tight sealing tolerances. Additionally, the end plates can provide electrical and structural safety. For example, when the end plates directly contact the busbar, electrical conductivity is generally undesirable. These materials are particularly well-suited for hydrogen fuel cell environments and are optimized for size, weight, thermal / electrical conductivity, and secondary surface finishes (e.g., machining).

[0027] According to another preferred embodiment, the core may comprise a non-plastic material as core material, such as metals such as aluminum and steel. Alternatively or additionally, the core material may be a composite material comprising glass and / or carbon fiber fabric. However, these are examples only and are not to be considered exhaustive. Alternatively or additionally, the core material may not comprise the shell material, or may comprise at least some of the shell material. For example, the core material may comprise plastic, injection molded thermoplastics, thermoformed plastics such as polyphenylene sulfide, a composite material comprising polystyrene and polyphenylene oxide, a composite material comprising polystyrene and polyphenylene ether, polyetheretherketone or an epoxy laminate. However, these are examples only and are not to be considered exhaustive. The core may preferably be made of the same resin as the shell. The core may preferably comprise a non-electrically insulating material. The core may preferably have a cross-sectional profile different from that of the shell. More preferably, the cross-sectional profile of the end plate may be closed. Most preferably, the cross-sectional profile of the shell may be complemented by the cross-sectional profile of the core, thereby forming a closed, preferably continuous, more preferably rectangular end plate profile.

[0028] The core can thus be made of a material with high material stiffness. Said material can also be selected to optimize weight, size and cost. A particular advantage of making the two parts from similar or identical materials is that a chemical bond is formed during overmolding, thereby reducing the risk of delamination.

[0029] According to a preferred embodiment, to create a form-fitting, locked connection, at least one of the core and the shell may include at least one joining segment, while the other may include a corresponding, complementary mating segment. The joining segment or mating segment may preferably narrow or widen as it extends from the corresponding end plate segment (i.e., the core or shell). Alternatively or additionally, the joining segment and / or mating segment may extend in at least two different directions. For example, the joining segment or mating segment may have a dovetail or slot configuration.

[0030] This provides a mechanical fixation between the core and the shell, thereby reducing the risk of separation or delamination between the shell and the core.

[0031] According to another preferred embodiment, the end plate may include a top surface, a bottom surface and a circumferential front surface extending therebetween. The shell surface may include at least the top surface. The core may include the bottom surface.

[0032] According to a preferred embodiment, the shell can at least partially comprise a cross-sectional profile that is open on one side. For example, the shell can comprise a U-shaped cross-sectional profile. Alternatively or additionally, the core can at least partially comprise a closed cross-sectional profile. For example, the core can comprise a rectangular cross-sectional profile. Preferably, the inner edge profile of the shell cross-sectional profile can correspond to the outer edge profile of the core cross-sectional profile.

[0033] This can improve the mechanical strength of the end plate, in particular the bending stiffness.

[0034] According to another preferred embodiment, the end plate may include one or more plate features for providing end plate functionality in the fuel cell stack. The plate features may be provided on the housing and / or the core. For example, the plate features may include one or more ports for supplying reactant gases, grooves for accommodating a bus plate, slots for aligning the end plate with the fuel cell stack, and drilled holes, threaded holes, and / or slots for accommodating compression hardware (e.g., clamps) for clamping the stack.

[0035] The end plate may preferably include one or more supply ports extending through the shell surface and the core in a longitudinal extension direction to provide a through passage between the top and bottom surfaces. The supply port may preferably extend at least partially along the periphery of the end plate on the shell surface.

[0036] A plurality of ports can thus be provided in the end plate for supplying reactant gases to the fuel cell stack or for conducting exhaust gases away from the fuel cell stack.

[0037] The housing preferably includes one or more partitions defining the inner surface of the supply ports. Each supply port may preferably be surrounded by a different partition. The core may include corresponding through-holes for accommodating the partitions. It is also conceivable that one through-hole may accommodate more than one such partition. Thus, for example, multiple supply ports may be formed by multiple partitions accommodated within the same through-hole. The housing surface preferably includes the inner surface.

[0038] This allows the housing material to define the inner side of the supply port. This helps ensure that the supply port is within the required manufacturing tolerances and exhibits the desired chemical and / or electrical inertness. At the same time, the core can remain simple and made of a rigid material, thereby providing high bending stiffness. Furthermore, the core does not need to be chemically or electrically inert. Furthermore, the core can be manufactured to relatively loose tolerances.

[0039] The cover surface may preferably include a concave section, which may extend at least partially inwardly in the direction from the top surface to the bottom surface.

[0040] A recess for the bus plate can thereby be provided in the electrically insulating material.

[0041] Another aspect of the present invention relates to a fuel cell stack. For example, the fuel cell stack may be a solid polymer electrolyte fuel cell stack. The fuel cell stack includes stacked fuel cells arranged in series. The stack is covered on at least one side by an end plate having any of the configurations described above.

[0042] With the fuel cell stack, the same advantages and technical benefits as described above for the end plate of the invention can be achieved. In particular, the risk of gas escape from the fuel cell stack can be reduced, and its mechanical stability and weight can be improved.

[0043] Another aspect of the present invention relates to a method for manufacturing an end plate for a compressed fuel cell stack. For example, the end plate described above can be made using the method described above. In the method, a core for providing rigidity to the end plate is provided by (e.g., manufactured from) a core material. The provided core has a core rigidity. Additionally, a housing is formed by at least partially overmolding the core with a housing material, the housing having a housing surface that contacts the fuel cell stack. The housing rigidity of the formed housing is less than or equal to the core rigidity.

[0044] By means of the method, the same advantages and technical benefits as described above for the end plates of the present invention can be obtained. In particular, the end plates can be manufactured in a manufacturing process suitable for large-scale production. In addition, the moulds used in the process can be kept small and simple, thereby improving the mould flow characteristics, reducing the risk of material defects and reducing the effects of warping and shrinkage on the finished end plate. In addition, the method allows the core to be manufactured using an injection moulding process, which, for example, facilitates the formation of complex shapes. Machining is also a viable option for manufacturing the core. Any reworking of core defects can be repaired by the shell as part of the overmoulding process. Manufacturing costs can thereby be kept low and the end plate can be provided as a single solid piece, with one section (i.e. the shell or the core) formed on the other section.

[0045] According to a preferred embodiment, in the method, the core can be provided by machining a monolithic material. For example, the core can be machined or water jet cut. Alternatively, the core can be formed by an injection molding process. Preferably, the core can be surface-machined, for example, before being overmolded with the shell material. Preferably, in the method, the core can be provided separately from the shell. In the method, the end plates can be manufactured using a mixed material combination comprising core material and shell material.

[0046] This can increase the manufacturing speed and design freedom of the core.

[0047] According to another preferred embodiment, in the method, the shell can be formed preferably by an injection molding process, such as overmolding or insert molding. Alternatively or additionally, in the method, the shell can be formed by providing a mold having a cavity. Preferably, the mold may include one or more port protrusions for forming one or more supply ports in the end plate. The port protrusion may extend axially into the cavity along the protrusion axis from the periphery of the cavity. Alternatively or additionally, the mold may include one or more front sections for forming a concave section on the shell surface. The front section may protrude from the periphery of the mold. Alternatively or additionally, the mold may include one or more sealing sections for forming a sealing structure, such as a sealing groove, on the shell surface. The sealing section may extend from the front section and / or the port protrusion. Here, the sealing section may preferably protrude or be concave axially and / or laterally from the front section and / or the port protrusion.

[0048] This makes it possible to provide different sheet metal features on the housing.

[0049] Preferably, in the method, the core may be inserted into the mould cavity such that the port protrusion is aligned with the through hole provided in the core. The mould may be filled with the shell material. The shell material may be cured.

[0050] This reduces the complexity of the mold and the amount of material required for the housing.

[0051] Preferably, the housing, housing surface, and / or supply port can be surface-machined after the overmolding step onto the core. For example, they can be machined after this step. Preferably, mechanical fixing structures (such as joint sections or mating sections) can be added by roughening, machining grooves, and / or machining dovetail structures.

[0052] The overmolded end plate can preferably be removed from the mold before or after the surface finishing step.

[0053] This ensures that the surfaces meet tight machining tolerances. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Other features, advantages and purposes of the present invention will become more apparent to those skilled in the art by reading the following detailed description of the embodiments of the present invention in conjunction with the accompanying drawings, which schematically illustrate:

[0055] Figure 1 An embodiment of the end plate and fuel cell stack of the present invention is shown.

[0056] Figure 2 Show Figure 1 Exploded rear view of the end plate,

[0057] Figure 3 Show Figure 1 Exploded front view of the end plate,

[0058] Figure 4A Show Figure 1 Cutaway perspective view of the middle board,

[0059] Figure 4B Show Figure 4A A partial enlarged view of the center section view,

[0060] Figure 5A Show Figure 1 A cutaway perspective view of the housing of the mid-end plate,

[0061] Figure 5B Show Figure 5A Cutaway front view of the middle shell,

[0062] Figure 6 An embodiment of a method for manufacturing an end plate according to the present invention will be described. DETAILED DESCRIPTION

[0063] Figures 1 to 6 Various views and aspects of embodiments of the invention are shown.

[0064] Figure 1 A fuel cell stack 200 is shown as an example, which includes a plurality of fuel cells 240 stacked along a stacking direction SD. Figure 1 The stacking direction SD is exemplarily shown by a double arrow in FIG. Figure 1 In the diagram, the stacked fuel cells 240 are schematically shown as a single item. The fuel cell stack 200 can be used to generate electricity, in which case the fuel cells 240 operate as fuel cells. Alternatively or additionally, the fuel cell stack 200 can be used to generate fuel, in which case the fuel cells 240 operate as an electrolyzer. The fuel cell stack 200 is provided with end plates 100 on either or both sides of the fuel cell stack 200, which are opposite to each other along the stacking direction SD.

[0065] Figures 1 to 4B An end plate 100 is shown as an example. The end plate 100 may include a substantially flat top surface 101, a substantially flat bottom surface 102, and a circumferential front surface 103 extending therebetween. The top surface 101 and the bottom surface 102 may be parallel to each other. The end plate 100 may have any cross-sectional profile, such as a rectangular or circular shape. The plate height of the end plate 100 (e.g., the plate extension in the stacking direction SD) may be smaller than the plate width and plate length.

[0066] The end plate 100 includes at least two different sections that are different from each other in terms of stiffness. That is, the end plate 100 includes a core 110 for providing stiffness to the end plate 100. In addition, the end plate 100 includes a cover 120 having a cover surface 121 configured to be in contact with the fuel cell stack 200. Figure 1 The core 110 and a portion of the shell 120 are highlighted, but it is also conceivable to incorporate other sections with different stiffness into the end plate 100 .

[0067] The housing surface 121 may include all surfaces of the housing 120 and Figures 2 to 5B 100 . In these figures, the cover surface 121 is shown as at least the top surface 101 of the end plate 100, thereby forming the surface that contacts the fuel cell stack 200. For example, the cover surface 121 may contact one of the fuel cells 240 of the fuel cell stack 200 and / or contact other components located at the respective ends of these stacked fuel cells 240. The core 110 forms the bottom surface 102 of the end plate 100, as shown in the figures.

[0068] The core stiffness of the core 110 is equal to or greater than the shell stiffness of the shell 120. In particular, the bending stiffness of the core 110 can be greater than that of the shell 120. This difference in stiffness may be due to the use of different materials to manufacture the core 110 and the shell 120. Alternatively or additionally, the core 110 and the shell 120 may have different cross-sectional profiles.

[0069] Despite the above differences, the shell 120 and the core 110 can still be provided as a single, preferably continuous structure, because the shell 120 is at least partially overmolded onto the core 110. This can be Figures 1 to 4B As can be seen in FIG, here, the shell 120 completely covers one side of the core 110, as shown in the figure. In addition, the outer periphery of the core 110 is covered in the side direction by the circumferential shell edge 122 of the shell 120, which extends from the shell surface 121. Figure 4B As shown in the exemplary embodiment, the inner edge 129 of the cross-sectional profile of the shell 120 can be matched with the outer edge 119 of the cross-sectional profile of the core 110 .

[0070] During overmolding, chemical bonding may occur between the core 110 and the shell 120. The core 110 and shell 120 may preferably include additional mechanical fixing features to lock the two sections 110, 120 together. Figures 1 to 4B For example, the core 110 and the housing 120 can be connected to each other in a form-locking manner. This can prevent relative movement in any direction, such as Figure 4A and 4B For example, the x-direction, y-direction and z-direction are shown. To this end, the shell 120 may include one or more engaging members 124 that engage with corresponding counterparts 114 of the core 110. Figure 2 As shown, the shell 120 can include an engagement piece 124 that extends inwardly relative to the outer periphery from the circumferential shell edge 122 . The counterpart 114 can be provided as a lateral recess in the core 110 that corresponds to the shape of the engagement piece 124 . Figure 4B Other examples of mechanical fixing features are shown. Figure 4B In the embodiment, the core 110 is exemplarily provided with a groove as a counterpart 114. The housing 120 is shown as having a corresponding engagement member 124 protruding from the inner edge 129 toward the core 110. It is conceivable that the engagement member 124 and the counterpart 114 can be provided in other different ways, for example Figure 6 However, all of the above configurations are merely examples and should not be considered exhaustive.

[0071] like Figure 1 As further shown, the end plate 100 may include plate features 130, such as supply ports 131, for supplying reactant gases and coolant to the stacked fuel cells 240 and for exhausting corresponding exhaust gases. The plate features 130 may be provided in the core 110 and / or the housing 120, and other examples of the plate features 130 will be explained in the following paragraphs.

[0072] Figure 1Further shown is a clamping structure 250, which compresses the end plate 100 and the stacked fuel cells 240 together. The clamping structure 250 may include a clamping member 251, such as a clamping strap. The clamping member 251 may be secured to the end plate 100 via a fixing member 252 to apply an appropriate contact pressure between the stacked fuel cells 240 and the end plate 100. This allows the stack to be maintained in a compressed state, wherein the initial compressive force is applied externally and subsequently removed.

[0073] Figure 2 and 3 Other details of the core 110 are shown by way of example. In general, the core 110 can have any cross-sectional profile, including rectangular or square. In addition, the core 110 can be solid, or solid but with structural voids. The through-channel that passes through the core 110 along the stacking direction SD can be provided as a through-hole 113. As shown by way of example, the through-hole 113 can be provided at any position on the circumference of the core 110. In the exemplary illustration, the through-hole 113 can be provided at opposite ends of the core 110 along the length direction. The core 110 may not include a through-hole, or include one or more through-holes 113. The through-hole 113 can also serve as a mating piece 114. The core 110 may include a threaded hole 115 for receiving a fixing member 252.

[0074] Figure 2 、 3 5A and 5B illustrate exemplary shells 120. Shells 120 may be of any geometric shape, but generally may match the shape of core 110. Alternatively, shells 120 may have an open cross-sectional profile. Figures 2 to 5B As shown, the cover 120 may have a U-shaped cross-sectional profile. The U-shape may be formed by the cover surface 121, or more specifically, by the circumferential cover edges 122 on either side of the top surface 101 (which may be formed by the cover surface 121).

[0075] like Figure 3 、 4A As clearly shown in FIG4B , the housing 120 includes a housing surface 121 designed to contact components of the fuel cell stack 200. To this end, the housing 120 can be made of an electrically insulating material. Furthermore, the housing surface 121 can include a concave section 126 that extends inward to create a step in the housing surface 121. This creates a recessed portion for accommodating, for example, a busbar.

[0076] Figures 1 to 5B It is further shown that the circumferential shell edge 122 can include one or more clamping sections 125 for accommodating the clamping element 251. The clamping sections 125 can each be provided by a material reduction in the circumferential shell edge 122.

[0077] Figures 1 to 5B It is further shown that the passage through the shell 120 can be defined by a plurality of partition walls 123, which can form supply ports 131 in the end plate 100. One or more of the partition walls 123 can extend from the shell surface 121. The partition walls 123 can extend transversely to the top surface 101 up to the supply port length. The supply port length can be selected according to the requirements of the fuel cell stack 200. For example, the supply port length can be set to be greater than or less than the length of the circumferential shell edge 122. The partition walls 123 can protrude inwardly and / or outwardly relative to the core 110 from the shell surface 121. Thereby, the partition walls 123 can form a connection with the piping system in the fuel cell stack 200. Each supply port 131 can be provided with a sealing section 127, such as a groove. A sealing ring can be placed in the sealing section 127. Alternatively, the sealing section 127 can provide a sealing edge.

[0078] Figure 6 Further illustrated are exemplary steps of a method for manufacturing 500 the end plate 100. Of course, other configurations of the method 500 are possible, and thus this illustration should only be understood as an example of one possible configuration.

[0079] like Figure 6 As shown, in one step of method 500, a core 110 is provided. The core 110 can be provided by machining or cutting a whole piece of material. Alternatively, the core 110 can be formed in a first injection molding process. Alternatively, it is also conceivable that the core 110 can be formed by pressing a pre-impregnated composite material or by a compression molding process, combining resin and reinforcement materials and / or fibers. These reinforcement materials can be solid and / or hollow and can be oriented according to engineering requirements to meet the requirements of bending stiffness and strength. As a general supplement or alternative to the above-mentioned configuration, the core 110 can include an internal grid structure. Weight and stiffness can thereby be optimized. The core 110 can then be selectively surface-processed.

[0080] Preferably, the mechanical anchoring member can be added by roughening or machining. To this end, the core 110 can be provided with a counterpart 114. Figure 6 In the embodiment of the present invention, the counterpart 114 is shown as a slot, some of which may be shaped like a dovetail structure.

[0081] The core 110 can then be placed in the cavity 301 of the injection molding mold 300. The mold 300 can include a port protrusion 330 for forming the supply port 131 in the end plate 100. The port protrusion 330 can extend axially into the cavity 301 along the protrusion axis PA from the peripheral edge 303 of the cavity 301. The circumferential extension of the port protrusion 330 can be smaller than the through hole 113 of the core 100 to form the partition wall 123 during molding. In addition, the mold 300 can include a front section 326 for forming the concave section 126 in the shell surface 121. Alternatively or additionally, the front section 326 can be composed of a collector bus plate so that it is added during the injection molding process and can become a permanent part of the end plate 100. The mold 300 can also include a sealing section 327 for forming a sealing structure on the shell surface 120. The sealing section 327 can extend laterally from the port protrusion 330.

[0082] When the core 110 is inserted into the cavity 301, the port protrusion 330 can be aligned with the through hole 113 of the core 110. Figure 6 is shown in .

[0083] Next, mold 300 may be filled with the shell material, which may be cured. Thus, shell 120 having shell surface 121 is formed by at least partially overmolding the shell material onto core 110. It is contemplated that shell 120 may be formed in another injection molding process than core 110, provided that this is suitable for the manufacturing process of core 110.

[0084] The shell 120 and the core 110 thus formed have different rigidities from each other. Here, the shell 120 and the core 110 may have different properties, such as material rigidity, bending strength, electrical conductivity, water absorption, and hydrogen permeability.

[0085] In addition, at least one or more areas of the cover surface 121 may be finished during the machining process, such as secondary machining. For example, such finishing may be performed if a smoother surface finish than that achieved during the overmolding process is desired. The overmolded end plate 100 may be removed from the mold 300 before or after such finishing.

[0086] The present invention is not limited to the above-described embodiments, but only in accordance with the appended claims. All features of the above-described embodiments can be combined in any possible way and can be provided interchangeably.

[0087] Reference numerals

[0088] 100 End Plate

[0089] 101 Top

[0090] 102 Bottom

[0091] 103 circumferential surface

[0092] 110 core

[0093] 113 through holes

[0094] 114 matching parts

[0095] 115 threaded hole

[0096] 116 connecting section

[0097] 119 outer edge

[0098] 120 Shell

[0099] 121 Shell surface

[0100] 122 Circumferential shell edge

[0101] 123 partition wall

[0102] 124 joints

[0103] 125 Clamping section

[0104] 126 concave section

[0105] 127 Sealing section

[0106] 129 inner edge

[0107] 130 Plate Features

[0108] 131 Supply port

[0109] 200 fuel cell stack

[0110] 240 stacked fuel cells

[0111] 250 clamping structure

[0112] 251 Clamping parts

[0113] 252 fixings

[0114] SD stacking direction

[0115] 300 mold

[0116] 301 cavity

[0117] 303 mold periphery

[0118] 326 anterior section

[0119] 327 sealing section

[0120] 330 port protrusion

[0121] 500 Manufacturing Method

Claims

1. An end plate (100) for compressing a fuel cell stack (200), characterized in that: The end plate has: - a core (110) for providing rigidity to the end plate (100), the core having a core rigidity, - a housing (120) having a housing surface (121) for contacting the fuel cell stack (200), the housing stiffness of the housing (120) being less than or equal to the core stiffness, The shell (120) is at least partially overmolded on the core (110).

2. The end plate (100) according to claim 1, characterized in that: The core stiffness is the stiffness of the core material and the shell stiffness is the stiffness of the shell material, wherein these material stiffnesses are preferably the bending stiffness of the core material and the bending stiffness of the shell material.

3. The end plate (100) according to claim 1 or 2, characterized in that: The end plate (100) comprises a single, one-piece, continuous structure, and / or The shell (120) is overmolded onto the core (110) in such a way that the core (110) is covered by the shell surface (121) at least at one end and preferably completely along its periphery.

4. The end plate (100) according to claim 1 or 2, characterized in that: The housing surface (121) is configured to provide a sealing surface between the end plate (100) and components of the fuel cell stack (200) when the end plate (100) is mounted on the fuel cell stack (200), and / or The housing (120) is made of an electrically insulating material, and / or The housing materials include plastics, injection molded thermoplastics, thermoformed plastics such as polyphenylene sulfide, composite materials comprising polystyrene and polyphenylene oxide, composite materials comprising polystyrene and polyphenylene ether, polyetheretherketone or epoxy-based laminates.

5. The end plate (100) according to claim 1 or 2, characterized in that: The core (110) comprises: Non-plastic materials such as metals such as aluminum or steel, or composite materials containing glass and / or carbon fiber fabrics, as core materials, or At least some of the material used for the housing (120).

6. The end plate (100) according to claim 1 or 2, characterized in that: At least one of the core (110) and the shell (120) comprises at least one joining section (114, 124), and the respective other comprises a corresponding complementary-shaped mating section (114, 124) for forming a positive-locking connection.

7. The end plate (100) according to claim 1 or 2, characterized in that: The end plate (100) comprises a top surface (101), a bottom surface (102) and a peripheral front surface (103) extending therebetween, wherein the housing surface (121) comprises at least the top surface (101) and the core (110) comprises the bottom surface (103), and / or The housing (120) at least partially comprises a cross-sectional profile open on one side, preferably a U-shaped cross-sectional profile, and / or The core (110) at least partially comprises a closed, preferably rectangular cross-sectional profile, wherein the profile of the inner edge (129) of the cross-sectional profile of the shell (120) preferably corresponds to the profile of the outer edge (119) of the cross-sectional profile of the core (110).

8. The end plate (100) according to claim 7, characterized in that: The end plate (100) includes one or more supply ports (131), which extend through the shell surface (121) and the core (110) in a longitudinal extension direction to provide a through channel between the top surface (101) and the bottom surface (102), wherein the supply port (131) preferably extends at least partially along the periphery of the end plate (100) on the shell surface (121).

9. The end plate (100) according to claim 8, characterized in that: The shell (120) includes one or more partition walls (123) that define the inner surface of the supply port (131), wherein each supply port (131) is preferably surrounded by a different partition wall (123), and wherein the core (110) includes corresponding through holes (113) for accommodating the partition walls (123).

10. The end plate (100) according to claim 7, characterized in that: The housing surface (121) includes a concave section (126) extending at least partially inwardly in a direction from the top surface (101) to the bottom surface (102).

11. A fuel cell stack (200), preferably a solid polymer electrolyte fuel cell stack, characterized in that: A stack of fuel cells (240) is provided, which is arranged in series and is covered on at least one side by an end plate (100) according to one of claims 1 to 10.

12. A method of manufacturing (500) an end plate (100) for a compressed fuel cell stack (200), characterized in that: - providing a core (110) for providing stiffness to the end plate (100) by a core material, the core (110) having core stiffness, and - forming a shell (120) by at least partially overmolding a shell material onto the core (110), the shell having a shell surface (121) in contact with the fuel cell stack (200), and the shell stiffness of the shell (120) is less than or equal to the core stiffness.

13. The method (500) according to claim 12, characterized in that: - providing the core (110) by processing, preferably machining or water jet cutting, from a block of material or by forming the core (110) in an injection molding process; and / or - Surface processing, preferably machining, of the core (110) before overmolding with the shell material.

14. The method (500) according to claim 12 or 13, characterized in that: - The housing (120) is preferably formed by injection molding in the following manner, namely: o Providing a mold (300) having a mold cavity (301), wherein the mold (300) comprises: ■ one or more port protrusions (330) for forming one or more supply ports (131) in the end plate (100), wherein the port protrusions (330) extend axially into the cavity (301) along a protrusion axis (PA) from a peripheral edge (303) of the cavity (301); ■ one or more front sections (326) for forming a concave section (126) in the shell surface (121), which protrude from the mold periphery (303); and ■ one or more sealing sections (327) for forming a sealing structure on the housing surface (120), which respectively extend from the front section (326) and / or the port protrusion (330) in a preferably protruding or concave manner; o Inserting the core (110) into the mold cavity (301) such that the port protrusion (330) is aligned with the through hole (113) provided in the core (110); o filling the mold (300) with the shell material; o curing the shell material; and / or - after overmolding onto the core (110), the shell (120), preferably the shell surface (121) and / or the supply port (131) is surface-processed, preferably machined; and - Preferably before or after said surfacing step, said overmolded end plate (100) is removed from said mould (300).

15. The method (500) according to claim 12 or 13, characterized in that: The core (110) is provided separately from the shell (120), and / or a mixed material combination including the core material and the shell material is used to manufacture the end plate (100) in the method (500).

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