Method for producing a component for an electrochemical system and component for an electrochemical system

Abstract

The present invention relates to a method for producing a component for an electrochemical system. The method comprises steps in which at least one metallic layer with at least one sealing bead formed therein is provided, at least two first surface regions of the at least one sealing bead are subjected to at least one laser treatment, and at least one second surface region of the at least one sealing bead, which is arranged between the at least two first surface regions and directly borders the at least two first surface regions, is provided with at least one elastomeric sealing element. Furthermore, the present invention also relates to a component for an electrochemical system and to an electrochemical system comprising the component.

Description

[0001] The present invention relates to a method for producing a component for an electrochemical system. The method comprises steps in which at least one metallic layer with at least one sealing bead formed therein is provided, at least two first surface regions of the at least one sealing bead are subjected to at least one laser treatment, and at least one second surface region of the at least one sealing bead, which is arranged between the at least two first surface regions and directly borders the at least two first surface regions, is provided with at least one elastomeric sealing element. Furthermore, the present invention also relates to a component for an electrochemical system and to an electrochemical system comprising the component.

[0002] Known electrochemical systems include, for example, fuel cell systems, flow batteries, or electrochemical compression systems, in particular electrolyzers. Known electrolyzers are designed, for example, in such a way that hydrogen and oxygen are generated from water by applying a potential, with at least the hydrogen being present in compressed form. In addition, electrochemical compression systems such as electrochemical hydrogen compressors are also known, to which gaseous molecular hydrogen is fed and in which this is electrochemically compressed by applying a potential. Furthermore, known electrochemical systems include electrochemical separator systems in which, for example, hydrogen is extracted from one reaction system and enriched in another part of the electrochemical system.

[0003] Furthermore, electrochemical systems are known which comprise a stack of electrochemical cells, each of which is separated from one another by bipolar plates. Such bipolar plates can be used, for example, to indirectly electrically contact the electrodes of the individual electrochemical cells (e.g. fuel cells) and / or to indirectly electrically connect adjacent cells (series connection of the cells). The bipolar plates can also have a channel structure or form a channel structure which is designed to supply the cells with one or more media and / or to transport away reaction products. The media can be fuels (e.g. hydrogen or methanol), reaction gases (e.g. air or oxygen) or coolants. Such a channel structure is usually arranged in an electrochemically active region (flow field) as well as in the distribution and discharge lines leading to and from this region.Collection areas. Furthermore, the bipolar plates can be designed to conduct the waste heat generated during the conversion of electrical or chemical energy in the electrochemical cell, as well as to seal the various media channels, including the cooling channels, from one another and / or from the outside. For example, the bipolar plates can have openings through which the media to be supplied and / or the reaction products can be conducted to or away from the electrochemical cells arranged between adjacent bipolar plates of the stack.

[0004] The electrochemical cells can, for example, each comprise one or more membrane electrode assemblies (MEAs). The MEAs can have one or more electrically conductive gas diffusion layers, which are typically oriented toward the bipolar plates and are formed, for example, as an electrically conductive fleece, in particular as a metal or carbon fleece. The membrane electrode assemblies typically have a frame-shaped seal on their outer edge, which is formed in particular from polymer-based material, preferably from polymer-based films.

[0005] The seal between the bipolar plates and the MEA is usually created outside the electrochemically active area and usually comprises at least one port seal and an outer seal. The bipolar plates are usually made up of two separator plates, one of which is adjacent to a membrane electrode unit. The separator plates can have seals to seal against the membrane electrode unit, in particular against the frame-shaped seal of the membrane electrode unit. If the separator plates are made of metal plates, these seals can be molded directly into the separator plates as sealing beads, for example by means of embossing, deep drawing or hydroforming. Alternatively, it is also possible for the sealing beads not to be molded into the separator plates or the bipolar plate, but rather into a sealing frame that surrounds the separator plate or the bipolar plate.bipolar plate or is arranged on it in a frame-like manner.

[0006] To improve micro-sealing, such sealing beads typically have polymer-based sealing coatings, particularly elastomeric sealing elements, on at least one side. Examples of this are mentioned in DE 10 2018 101 316 A1. To apply these elastomeric sealing elements, an elastomer-forming component (or an elastomer precursor) can be applied to the sealing bead(s) as part of or in an apolar liquid coating material. However, the process window for correctly setting the optimal parameters for the optimal viscosity of the coating material and the coating parameters for the achievable wet film thickness is very limited. The process is therefore technically very demanding. If coating material runs from the bead roof onto the bead flanks, this leads to losses in the final height of the elastomeric sealing element. This can result in higher leakage rates.In other cases, the affected bipolar plate may be classified as rejected.

[0007] Based on this, it was therefore the object of the present invention to provide a method for producing a component suitable for an electrochemical system, comprising at least one metallic layer with at least one sealing bead formed therein, in which a coating of the at least one sealing bead can be carried out with increased precision, and to provide a component suitable for an electrochemical system, comprising at least one metallic layer with at least one sealing bead formed therein, which component can be produced in such a way that a coating of the at least one sealing bead can be carried out with increased precision.

[0008] This object is achieved by a method according to patent claim 1, by a component for an electrochemical system according to patent claim 12, and by an electrochemical system according to patent claim 21. The respective dependent patent claims represent advantageous developments.

[0009] According to the invention, a method for producing a component for an electrochemical system is thus provided, in which a) at least one metallic layer with at least one sealing bead formed therein is provided, b) at least two first surface regions of the at least one sealing bead are each subjected to at least one laser treatment, in which the at least two first surface regions are irradiated by means of a pulsed laser with laser pulses having a pulse duration of less than 1 ns, wherein the at least one laser treatment produces surface structurings (or one surface structuring in each case) on the at least two first surface regions, which have periodic structures comprising alternately arranged, substantially strip-shaped elevations and depressions, as well as nanostructures in the form of substantially punctiform elevations arranged (at least) on the substantially strip-shaped elevations, and c) at least one second surface region of the at least one sealing bead, which is arranged between the at least two first surface regions and directly adjoins the at least two first surface regions, is provided with at least one elastomeric sealing element, wherein at least one (apolar) liquid coating material comprising at least one component forming at least one elastomer (or at least one elastomer precursor) is applied to the at least one second surface region.

[0010] The method according to the invention makes it possible to precisely provide a desired region of the at least one sealing bead of the metallic layer with an elastomeric sealing element. For this purpose, hydrophilic, preferably superhydrophilic, surface structures (or one hydrophobic, preferably superhydrophobic, surface structure in each case) are ultimately created on at least two surface regions (i.e., the at least two first surface regions of the at least one sealing bead) that directly border the region to be coated (i.e., the at least one second surface region of the at least one sealing bead), wherein the provision of the at least one elastomeric sealing element is finally carried out by applying at least one apolar liquid coating material comprising at least one elastomer.Since the hydrophilic surface structures have a repellent effect towards the apolar liquid coating material, the carrier liquid applied to the area to be coated stops at the edge of the area to be coated (immediately adjacent to the at least two first surface areas) and does not flow over the at least two surface areas with the surface structures. The two first surface areas, i.e. the areas with surface structures, therefore remain free of the apolar liquid coating material and thus also free of the coating. The surface structures thus act as a type of flow stopper for the at least one apolar liquid coating material comprising the at least one elastomer, so that the resulting elastomeric sealing element is ultimately arranged only on the area to be coated, i.e. the at least one second surface area.The surface structures can thus be created in areas that at least partially delimit the area to be coated, so that when the coating material is subsequently applied to the area to be coated, the coating material remains in the area to be coated and does not flow through the areas with the surface structures into areas not to be coated. This ultimately enables very precise application of the coating material and thus also coating of at least one sealing bead with increased accuracy, since it can be ensured that the coating material actually only reaches the area of ​​the respective sealing bead to be coated, and thus only this area is coated.

[0011] In particular, with appropriate arrangement of the areas with surface structures on at least one sealing bead, flow of the liquid coating material from the bead roof to the bead flanks can be prevented, even if, for example, the liquid coating material has a relatively low viscosity and thus a relatively high flow tendency. Accordingly, losses in the final height of the elastomeric sealing element and the resulting higher leakage rates, as well as rejection of the components that are therefore not sufficiently sealed, can be prevented.

[0012] In addition, the method according to the invention simplifies the coating process when applying the liquid coating material, since, for example, the viscosity and the wet layer thickness of the applied liquid coating material no longer have to be adjusted so precisely in order to reduce the risk of the liquid coating material flowing into an area not to be coated.

[0013] The position of the at least two first surface areas (and thus the position of the surface structuring) is variable and can preferably also be applied in a radius at the transition from the bead roof to one of the two bead flanks. This allows the maximum available width of the bead roof surface to be utilized, thus ensuring the maximum possible sealing width of the elastomeric sealing element.

[0014] Furthermore, the process according to the invention can also be used to produce particularly thick elastomeric sealing elements, for example, with a maximum thickness of at least 20 µm, and preferably at least 50 µm for foamed material, even with low-viscosity coating materials, since the surface structures allow a larger amount of liquid coating material to be applied to the area to be coated without any of the coating material flowing over the areas with the surface structures. Consequently, a higher wet film thickness and thus also a higher dry film thickness can be achieved than in the prior art.

[0015] The special surface structures also enable the topographical design of the elastomeric sealing element, and thus of the sealing element and sealing bead system, without changing the height of the (metallic) sealing bead. This opens up new approaches to system design. Furthermore, the use of surface structures allows for a modified edge geometry of the elastomeric sealing element to the bead roof or the bead flanks. This can result in a significantly steeper transition from the bead roof to the upper edge of the coating material, thus evening the coating thickness of the sealing element and improving contact with the adjacent component, e.g., the edge reinforcement of the MEA.

[0016] The hydrophilic surface structures on the at least two first surface regions are created by laser treatment. Within the scope of the present invention, it was surprisingly discovered that laser treatment on the at least two first surface regions of the beads of the metallic plate can produce special surface structures that have hydrophilic, preferably superhydrophilic, properties. The special surface structures obtained by the laser treatment have periodic structures and nanostructures arranged on the periodic structures, wherein the periodic structures comprise alternatingly arranged substantially strip-shaped elevations and depressions, and wherein the nanostructures are in the form of substantially point-shaped elevations and are arranged (at least) on the substantially strip-shaped elevations.The surface structures created by the laser treatment have hydrophilic, preferably superhydrophilic, properties and thus act as a type of flow stopper for the at least one apolar liquid coating material comprising the at least one elastomer, so that the coating material applied to the at least one second surface region stops at the edge of the at least one second surface region (immediately adjacent to the at least two first surface regions) and does not flow onto or over the at least two first surface regions. This ultimately results in increased coating accuracy, since the surface structures can prevent coating material from reaching areas not to be coated.

[0017] In step a) of the method according to the invention, at least one metallic layer is first provided. The at least one metallic layer has at least one sealing bead formed into the at least one metallic layer.

[0018] The at least one metallic layer can be, for example, at least one metallic plate or at least one metallic frame. Preferably, the at least one metallic plate comprises two metallic plates. The two metallic plates can be separator plates, e.g., separator plates of a bipolar plate. The two metallic plates can be connected to one another, e.g., welded to one another, or they can be unconnected.

[0019] In step b) of the method according to the invention, at least two first surface regions of the at least one sealing bead are each subjected to at least one laser treatment. During the laser treatment, the at least two first surface regions are irradiated with laser pulses using a pulsed laser, wherein the laser pulses have a pulse duration of less than 1 ns. The laser pulses can also be referred to as ultrashort laser pulses. Accordingly, an ultrashort pulse laser (USP laser) can be used as the laser.

[0020] The at least one laser treatment creates surface structures on the at least two first surface regions (or a surface structure is created on each of the at least two first surface regions). After the at least one laser treatment, the at least two first surface regions are thus surface-structured surface regions. The surface structures have periodic structures and nanostructures. The periodic structures extend over the entire surface-structured surface regions, i.e., over the entire at least two first surface regions.

[0021] The periodic structures are structures that are arranged periodically to one another in at least one spatial direction. According to some embodiments, the periodic structures can be arranged parallel to one another, at least in sections. The alignment can be provided over larger or smaller areas. Different areas with parallel structures, in which, however, a different orientation compared to another area is provided, can also border one another. Thus, the shape of the periodic structures on the surface repeats itself in at least one spatial direction. Periodic structures can generally be characterized by a spatial period. A spatial period typically refers to the maximum distance between two adjacent, identically or similarly shaped structures, i.e.two of the essentially strip-shaped elevations or two of the essentially strip-shaped depressions. Due to manufacturing reasons, the structures are generally not completely identical to one another. Rather, the period along the surface can be subject to fluctuations. An average spatial period of the periodic structures can preferably be less than 10 µm, particularly preferably at most 2 µm. It can also happen that the spatial period of the periodic structures is in any case less than 10 µm, preferably at most 2 µm. For example, the periodic structures can have a period in a spatial direction x (running parallel to the main extension plane of the surface) of less than 10 µm, preferably of at least 0.3 µm and / or at most 2 µm.

[0022] The periodic structures comprise alternatingly arranged, essentially strip-shaped elevations and depressions, i.e. the periodic structures comprise essentially strip-shaped elevations and essentially strip-shaped depressions, wherein these elevations and depressions are arranged alternately or alternately, i.e. the depressions each run between the (or two of) the elevations and are delimited and / or formed by them. Essentially strip-shaped can be understood here (and fundamentally within the scope of the entire present invention) to mean that a (maximum) length of the respective elevation or depression is significantly greater, preferably at least 4 times greater, particularly preferably at least 5 times greater, than a (maximum) width of the respective elevation or depression.The essentially strip-shaped elevations and / or depressions can each have, at least in sections, a (essentially) linear profile and / or a non-linear profile, for example, a single- or multiply curved (e.g., wavy) profile. Furthermore, it is possible, for example, for the width of the essentially strip-shaped elevations and / or the width of the essentially strip-shaped depressions to vary along their profile. For example, the essentially strip-shaped elevations and / or depressions can also be partially branched.

[0023] Within the scope of the present invention as a whole, the (maximum) width and / or (maximum) length of the essentially strip-shaped elevations and / or the (maximum) width and / or (maximum) length of the essentially strip-shaped depressions can be determined, for example, by means of SEM (scanning electron microscopy). The width is typically measured at half height and perpendicular to the local longitudinal direction of the depressions or elevations. The maximum width can be regarded as the largest width of the respective depression or elevation that can be measured in this way. The length is typically measured along the longitudinal direction (or the course) of the depressions or elevations. The maximum length can be regarded as the largest length of the respective depression or elevation that can be measured in this way.

[0024] The nanostructures are formed in the form of essentially point-shaped elevations. Furthermore, the nanostructures or the essentially point-shaped elevations are arranged at least on the essentially strip-shaped elevations. Additionally, the nanostructures in the form of essentially point-shaped elevations can also be arranged on (or in) the essentially strip-shaped depressions. However, it is possible for the nanostructures in the form of essentially point-shaped elevations to be arranged exclusively on the essentially strip-shaped elevations.Essentially point-shaped can be understood here (and fundamentally within the scope of the entire present invention) to mean that the length of the respective elevation does not differ at all, or not significantly, from the width of the respective elevation, wherein the length of the respective elevation is preferably at most 3 times, particularly preferably at most 2 times, as large as the width of the respective elevation. A respective peripheral edge of the essentially point-shaped elevations can, for example, be essentially round (or circular), essentially elliptical, or essentially oval.

[0025] Within the scope of the present invention, the length and / or width of the essentially point-shaped elevations can be determined, for example, using SEM (scanning electron microscopy). The length is typically measured along the longest direction of extension (perpendicular to the surface) of the elevation. The width is typically measured along the direction perpendicular to this longest direction of extension of the elevation.

[0026] Preferably, the nanostructures in the form of essentially point-shaped elevations are arranged on the interfaces of the essentially strip-shaped elevations. The interface of the respective elevation represents the entire surface area of ​​the respective elevation that lies above half the height of the elevation, measured between the lowest point of an adjacent depression and the highest point of the elevation. The interfaces of the essentially strip-shaped elevations can be determined, for example, using SEM (scanning electron microscopy).

[0027] The at least two first surface regions can each have a linear profile and / or a non-linear, for example, undulating, profile in sections. For example, the at least two first surface regions can each have a (substantially) linear profile or a non-linear, for example, undulating, profile overall.

[0028] In step c) of the method according to the invention, at least one second surface region of the at least one sealing bead is provided (or coated) with at least one elastomeric sealing element. At least one apolar liquid coating material is applied to the at least one second surface region. The at least one apolar liquid coating material comprises or consists of at least one component forming at least one elastomer and optionally at least one crosslinker. The at least one component forming at least one elastomer can be understood to mean a component that can be crosslinked to form at least one elastomer, i.e. a component from which at least one elastomer is formed by crosslinking. The at least one component forming at least one elastomer can also be referred to as at least one elastomer precursor (that can be crosslinked to form at least one elastomer).The at least one second surface region is arranged between the at least two first surface regions and directly adjoins the at least two first surface regions.

[0029] The formation of the at least one elastomeric sealing element from the applied apolar liquid coating material can occur, for example, by at least partial crosslinking of the applied coating material. This at least partial crosslinking can be triggered, for example, by a sudden temperature change, e.g., by increasing the temperature to a second temperature, or by UV radiation.

[0030] Preferably, the at least one sealing bead comprises a plurality of sealing beads. In other words, it is preferred that in step a) at least one metallic layer is provided, each with a plurality of sealing beads formed therein.

[0031] A preferred embodiment of the method according to the invention is characterized in that - the pulse duration of the laser pulses is less than 100 ps, ​​preferably less than 50 ps, ​​and / or - the (or one) fluence introduced into the at least two first surface areas by irradiation with the laser pulses in a range of 15 J / cm 2 up to 120 J / cm 2 , preferably 20 J / cm 2 up to 100 J / cm 2 , particularly preferably 25 J / cm 2 up to 80 J / cm 2 , lies.

[0032] A further preferred embodiment of the process according to the invention is characterized in that step c) is carried out no later than 72 hours after step b), preferably no later than 24 hours after step b), particularly preferably no later than 6 hours after step b), very particularly preferably no later than 3 hours after step b), in particular no later than 1 hour after step b), for example directly after step b). In this way, it can be ensured that the hydrophilic properties of the surface structures are still present to a sufficient extent when step c) is carried out, since excessive aging of the surface structures can result in a reduction or loss of the hydrophilic properties of the surface structures.The aged surface structures also exhibit the periodic structures, which comprise the alternating, essentially strip-shaped elevations and depressions, as well as the nanostructures in the form of essentially point-shaped elevations arranged (at least) on the essentially strip-shaped elevations. However, as the surface structures age, the areal density of the nanostructures on the essentially strip-shaped elevations can increase. The areal density of the nanostructures is understood to be the proportion of the total area of ​​the essentially strip-shaped elevations that the nanostructures in the form of point-shaped elevations occupy or cover.

[0033] In preferred embodiments, the pulse duration is less than 100 ps, ​​less than 50 ps, ​​less than 20 ps, ​​less than 10 ps, ​​or even less than 1 ps. In some embodiments, pulse durations in the fs range are used, e.g., greater than 30 fs and / or less than 1000 fs, preferably greater than 50 fs and / or greater than 100 fs. In particular, picosecond or femtosecond lasers, collectively referred to as ultrashort pulse lasers, can be used for the method.

[0034] In particular, the surface structures can be created by the interaction of the incident laser radiation with the irradiated surface. This interaction leads to a spatially modulated energy coupling into the material, which subsequently leads to the surface structures. Typically, the fluence of the laser radiation is in the order of magnitude of the ablation threshold of the material used for the metallic plate. The fluence can, for example, be selected so that it deviates by no more than 20% from the ablation threshold of the material used for the at least one metallic plate. The fluence represents a measure of the energy density of the laser pulses and is usually measured in J / cm 2 The fluence should preferably be at least 15 J / cm 2 , preferably at least 20 J / cm 2 , particularly preferably at least 25 J / cm 2 , and / or a maximum of 120 J / cm 2 , preferably not more than 100 J / cm 2, particularly preferably 80 J / cm 2 , amount to.

[0035] A further preferred embodiment of the method according to the invention is characterized in that - the substantially strip-shaped elevations have a width in the range from 250 nm to 700 nm, preferably from 350 nm to 600 nm, and / or the substantially strip-shaped depressions have a width in the range from 100 nm to 550 nm, preferably from 200 nm to 450 nm, and / or - the nanostructures (each) have an average diameter in the range from 10 nm to 200 nm, preferably from 30 nm to 150 nm, particularly preferably from 50 nm to 120 nm, and / or - the nanostructures (each) have a maximum diameter in the range from 10 nm to 300 nm, preferably from 30 nm to 250 nm, particularly preferably from 50 nm to 200 nm, and / or - the nanostructures each have a surface area in the range of 80 nm 2 up to 40000 nm 2, preferably from 800 nm 2 up to 20,000 nm 2 , particularly preferably from 2000 nm 2 up to 10000 nm 2 , and / or - the areal density of the nanostructures on the essentially strip-shaped elevations is in the range of 1 to 10%, preferably 2 to 6%.

[0036] The width of the substantially strip-shaped elevations and / or the width of the substantially strip-shaped depressions can be determined, for example, as described above.

[0037] The essentially strip-shaped depressions can preferably have a depth in the range of 0.05 to 0.7 µm. The depth refers to the extent perpendicular to the plate plane below half the height. Correspondingly, the essentially strip-shaped elevations can have a height in the range of 0.05 to 0.7 µm. The height refers to the extent perpendicular to the plate plane above half the depth. The depth of the essentially strip-shaped depressions and the height of the essentially strip-shaped elevations can be determined, for example, by means of SEM (scanning electron microscopy), in particular by means of FIB SEM (focused ion beam scanning electron microscopy). For example, the depth of the essentially strip-shaped depressions can vary along the course of the individual depressions, just as the height of the essentially strip-shaped elevations can vary along the course of the individual elevations.

[0038] The (respective) mean diameter as well as the (respective) maximum diameter of the nanostructures can be determined, for example, using SEM (scanning electron microscopy). The diameter is typically measured as a (linear) spatial distance passing through the center of the respective nanostructure between a first point on the outer edge of the respective nanostructure and a second point on the outer edge of the nanostructure opposite the first point. The mean diameter can then be determined by averaging several measured diameter values ​​(each of a nanostructure). For example, the nanostructures can (each) have a minimum diameter in the range of 5 to 60 nm, preferably from 10 to 55 nm, particularly preferably from 15 to 50 nm. Preferably, the diameter of the individual nanostructures can vary from nanostructure to nanostructure over a certain range, i.e.the nanostructures can be of different sizes.

[0039] The respective surface area of ​​the nanostructures can be determined, for example, using SEM (scanning electron microscopy). The surface area of ​​a nanostructure can be understood as the size of the area that the nanostructure covers or occupies in a top view of the surface on which it is located. Preferably, the respective surface area of ​​the individual nanostructures can vary from nanostructure to nanostructure over a certain range, i.e., the nanostructures can be of different sizes.

[0040] According to a further preferred embodiment of the method according to the invention, the at least one metallic layer is formed from stainless steel and / or at least one titanium alloy, for example from a stainless steel core with at least one surface made of a titanium alloy.

[0041] A further preferred embodiment of the method according to the invention is characterized in that - the provision of the at least one second surface area with the at least one elastomeric sealing element is carried out by a method selected from the group consisting of screen printing methods, roller printing methods, stencil printing methods, dispenser methods (ie methods for application by means of dispensers), and combinations thereof, and / or - the at least one elastomer is selected from the group consisting of fluororubbers, silicone rubbers, nitrile-butadiene rubbers, polyurethanes, natural rubber, perfluororubbers, styrene-butadiene rubbers, butyl rubbers, fluorosilicone rubbers, chlorosulfonated polyethylene, silicone resins, epoxy resins, hydrogenated nitrile-butadiene rubbers, ethylene-propylene-diene rubbers, olefin-based resins, polyisobutylenes, ethyl-2-cyanoacrylate, and mixtures thereof.

[0042] The preferred elastomers mentioned are particularly suitable as sealing materials.

[0043] According to a further preferred embodiment of the method according to the invention, the at least one apolar liquid coating material is at least one foamable material which additionally comprises expandable microspheres, wherein after the application of the apolar liquid coating material to the at least one second surface area, the at least one elastomeric sealing element is formed with expansion of the microspheres, wherein preferably the microspheres - in the unexpanded state have an average diameter of at least 5 µm and / or at most 50 µm, and / or - have an average diameter of at least 20 µm and / or at most 150 µm in the expanded state.

[0044] Alternatively, the at least one apolar liquid coating material may also be a foamable material that does not comprise expandable microspheres but, for example, another blowing agent, or a non-foamable material.

[0045] A further preferred embodiment of the method according to the invention is characterized in that - the at least two first surface areas and / or the at least one second surface area run substantially parallel to (or along) a main direction of extension of the respective sealing bead and / or extend over the entire length or the entire extension of the respective sealing bead, and / or - the at least two first surface regions each have (over the entire length of the respective surface region) a width in the range from 90 µm to 460 µm, preferably from 95 µm to 300 µm, particularly preferably from 100 µm to 200 µm.

[0046] The respective width of the at least two first surface areas can be determined, for example, by means of SEM (scanning electron microscopy) as described above.

[0047] A further preferred embodiment of the method according to the invention is characterized in that the at least one sealing bead has a bead roof (running along the course of the respective sealing bead) as well as a first and a second bead flank each adjacent to the bead roof (running along the course of the sealing bead), wherein - at least one of the at least two first surface areas is arranged on an edge of the first bead flank directly adjacent to the bead roof and / or on the bead roof, preferably on an edge of the bead roof directly adjacent to the first bead flank, and at least one further of the at least two first surface areas is arranged on an edge of the second bead flank directly adjacent to the bead roof and / or on the bead roof, preferably on an edge of the bead roof directly adjacent to the second bead flank, and / or - the at least one second surface area is arranged on the bead roof, wherein preferably • the at least one second surface area is arranged exclusively on the corrugated roof, and / or • the at least one second surface area extends over the entire width of the corrugated roof or in sections over the width of the corrugated roof.

[0048] By arranging at least one of the at least two first surface areas on an edge of the first bead flank directly adjacent to the bead roof and by arranging at least one further of the at least two first surface areas on an edge of the second bead flank directly adjacent to the bead roof, it is possible to coat the entire bead roof (or the bead roof over its entire width) without any of the coating material getting onto the bead flanks. This prevents losses in the final height of the elastomeric sealing element and the resulting higher leakage rates as well as rejection of components that do not seal sufficiently. In addition, this enables the maximum available width of the bead roof surface to be utilized, thus ensuring the maximum possible sealing width of the elastomeric sealing element.The sealing bead has bead feet that border the bead flanks and are therefore no longer part of the sealing bead itself.

[0049] Preferably, the bead roof of the respective sealing bead has no curvature (or the bead roof of the respective sealing bead is flat) or the bead roof of the respective sealing bead has a curvature with a radius of at least 1 mm, preferably at least 2 mm. However, the radius is usually larger; it can be up to 15 mm, for example. Likewise, the bead roof can have multiple curvatures across its width, for example, alternating convex and concave curvatures. The individual curvatures can be identical or different.

[0050] Preferably, the bead flanks of the respective sealing bead each have a minimum angle to the bead feet in the range of 15° to 75°, preferably from 25° to 65°.

[0051] Preferably, the bead flanks of the respective sealing bead are tangentially connected to the bead roof of the respective sealing bead with a radius of at least 0.05 mm, preferably at least 0.2 mm. This radius can be considered (essentially) part of the bead flank.

[0052] Preferably, the bead flanks of the respective sealing bead are each connected tangentially to the bead feet with a radius of at least 0.05 mm, preferably at least 0.2 mm.

[0053] According to a further preferred embodiment of the method according to the invention, the at least one second surface area is provided with a further surface structuring before step c), preferably before step b), which has a plurality of further depressions, wherein preferably the further depressions - have a width and / or a diameter in the range from 10 µm to 150 µm, preferably from 20 µm to 100 µm, particularly preferably from 30 µm to 70 µm, and / or - have a depth of at least 2 µm and / or at most 40 µm and / or a depth of at most 20% of the thickness of the metallic layer, and / or - by laser radiation, preferably by irradiation using a pulsed laser, or by microstructuring embossing.

[0054] The further surface structuring differs from the surface structurings produced on the at least two first surface regions. Thus, the further surface structuring is not a surface structuring that comprises periodic structures comprising alternating, substantially strip-shaped elevations and depressions, as well as nanostructures in the form of substantially point-shaped elevations arranged (at least) on the substantially strip-shaped elevations. Preferably, the further depressions differ from the substantially strip-shaped depressions of the periodic structures.

[0055] The further surface structuring can improve the adhesion of the at least one elastomeric sealing element to the metallic layer, in particular when the at least one apolar liquid coating material is at least one foamable material which additionally comprises expandable microspheres.

[0056] The width and / or diameter of the additional depressions can be determined, for example, using SEM (scanning electron microscopy). The width and / or diameter can be measured, for example, halfway up the depressions and / or parallel to the untreated surface of the metallic layer. The depth of the additional depressions can be determined, for example, using SEM (scanning electron microscopy). The depth can be measured, for example, from the untreated surface of the metallic layer to the deepest point of the depression. The untreated surface is a surface directly adjacent to another depression or its surroundings, which may appear as an elevation. If the additional depression is located on a bead roof, this untreated surface is also part of the bead roof.

[0057] By ensuring that the depth of the additional depressions, which are deeper than the surface structuring with strip-like elevations and depressions, is no more than 20% of the thickness of the metallic layer, it can be ensured that the metallic layer does not exhibit any material weaknesses that could lead to leaks or fractures during operation. The thickness of the metallic layer is sometimes also referred to as the thickness of the metallic layer.

[0058] The additional recesses are preferably produced by laser radiation. Alternatively, the additional recesses can be produced mechanically, e.g., by embossing or scoring the metallic layer. Regarding further aspects of the process steps for producing the additional recesses, as well as the resulting geometries and properties of the additional recesses and the structures surrounding them, reference is made to DE 10 2021 204 497, which is hereby incorporated by reference into this document in its entirety.

[0059] A further preferred embodiment of the method according to the invention is characterized in that the component for an electrochemical cell is a bipolar plate for an electrochemical system, preferably for a fuel cell or for a fuel cell stack; a separator plate for an electrochemical system, preferably for an electrolyzer system; or a sealing frame for an electrochemical system, preferably for an electrolyzer system. The electrochemical system is preferably an electrochemical cell or a stack comprising a plurality of electrochemical cells.

[0060] Furthermore, the present invention also relates to a component for an electrochemical system, comprising at least one metallic layer with at least one sealing bead formed therein, wherein the at least one sealing bead has at least two first surface regions and at least one second surface region arranged between the at least two first surface regions and directly adjacent to the at least two first surface regions, wherein the at least two first surface regions have surface structures (ieeach having a surface structuring) which have periodic structures comprising alternately arranged substantially strip-shaped elevations and depressions, as well as nanostructures in the form of substantially point-shaped elevations which are arranged (at least) on the substantially strip-shaped elevations, and wherein the at least one second surface region is at least one surface region provided with at least one elastomeric sealing element (or at least one surface region having at least one elastomeric sealing element).

[0061] Because the at least two first surface regions have surface structuring (or each have a surface structuring), the at least two first surface regions are surface-structured surface regions. Preferably, the at least two first surface regions are at least two laser-treated surface regions.

[0062] It is preferred that the surface structures can be produced or are produced by at least one laser treatment. The at least one laser treatment can be carried out according to the respective previously stated embodiments regarding the method according to the invention.

[0063] Furthermore, it is preferred that the at least one elastomeric sealing element was produced using a process in which at least one apolar liquid coating material comprising at least one component forming at least one elastomer (or at least one elastomer precursor) was first applied to the at least one second surface region. The application can preferably be carried out using a method selected from the group consisting of screen printing methods, roller printing methods, stencil printing methods, dispenser methods (i.e., methods for application by means of dispensers), and combinations thereof.

[0064] The surface structures exhibit periodic structures and nanostructures. The periodic structures extend over the entire surface-structured surface areas, i.e., over the entire at least two first surface areas.

[0065] The periodic structures and the nanostructures are formed or can be formed as previously described in the context of the method according to the invention, the statements made there applying analogously here.

[0066] The at least one metallic layer can, for example, be at least one metallic plate or at least one metallic frame. Preferably, the at least one metallic plate comprises two metallic plates that are connected to one another, e.g., welded to one another. The two metallic plates can be separator plates, e.g., separator plates of a bipolar plate. If the two metallic plates are not connected to one another (during steps a) to c) of the method), the two metallic plates can be connected to one another, e.g., welded to one another, after step c), in order to form a bipolar plate. A frame can be applied to a separator plate of an electrochemical system or arranged to surround such a plate.

[0067] Preferably, the at least one sealing bead comprises a plurality of sealing beads. In other words, it is preferred that the at least one metallic layer is at least one metallic layer with a plurality of sealing beads formed therein.

[0068] A preferred embodiment of the component according to the invention is characterized in that - the substantially strip-shaped elevations have a width in the range from 250 nm to 700 nm, preferably from 350 nm to 600 nm, and / or the substantially strip-shaped depressions have a width in the range from 100 nm to 550 nm, preferably from 200 nm to 450 nm, and / or - the nanostructures (each) have an average diameter in the range from 10 nm to 200 nm, preferably from 30 nm to 150 nm, particularly preferably from 50 nm to 120 nm, and / or - the nanostructures (each) have a maximum diameter in the range from 10 nm to 300 nm, preferably from 30 nm to 250 nm, particularly preferably from 50 nm to 200 nm, and / or - the nanostructures each have a surface area in the range of 80 nm 2 up to 40000 nm 2 , preferably from 800 nm 2 up to 20,000 nm 2 , particularly preferably from 2000 nm 2 up to 10000 nm 2 , and / or - the areal density of the nanostructures on the essentially strip-shaped elevations is in the range of 1 to 10%, preferably 2 to 6%.

[0069] The width of the substantially strip-shaped elevations and / or the width of the substantially strip-shaped depressions can be determined, for example, as described in the context of the method according to the invention.

[0070] The (respective) mean diameter and the (respective) maximum diameter of the nanostructures can be determined, for example, as described in the context of the method according to the invention

[0071] The respective surface area of ​​the nanostructures can be determined, for example, as described in the context of the method according to the invention, whereby what has been said in the context of the method according to the invention regarding variations and bandwidths applies analogously.

[0072] The areal density of the nanostructures can be determined, for example, as described in the context of the method according to the invention, the statements there applying analogously here.

[0073] According to a further preferred embodiment of the component according to the invention, the at least one metallic layer is formed from stainless steel and / or at least one titanium alloy, for example from a stainless steel core with at least one surface made of a titanium alloy.

[0074] A further preferred embodiment of the component according to the invention is characterized in that the at least one elastomeric sealing element - contains at least one elastomer selected from the group consisting of fluororubbers, silicone rubbers, nitrile-butadiene rubbers, polyurethanes, natural rubber, perfluororubbers, styrene-butadiene rubber, butyl rubber, fluorosilicone rubbers, chlorosulfonated polyethylene, silicone resins, epoxy resins, hydrogenated nitrile-butadiene rubbers, ethylene-propylene-diene rubbers, olefin-based resins, polyisobutylenes, ethyl-2-cyanoacrylate, and mixtures thereof, and / or - contains or consists of a foamed material with microspheres, wherein preferably an average diameter of the microspheres is at least 20 µm and / or at most 80 µm.

[0075] The preferred elastomers mentioned are particularly suitable as sealing materials.

[0076] Preferably, the at least one elastomeric sealing element can contain or consist of a foamed material with microspheres. Alternatively, the at least one elastomeric sealing element can also contain or consist of a foamable material that does not comprise expandable microspheres, or can contain or consist of a non-foamable material.

[0077] A further preferred embodiment of the component according to the invention is characterized in that - the at least two first surface areas and / or the at least one second surface area run substantially parallel to a main direction of the respective sealing bead and / or extend over the entire length or the entire course of the respective sealing bead, and / or - the at least two first surface regions each have a width in the range from 90 µm to 460 µm, preferably from 95 µm to 300 µm, particularly preferably from 100 µm to 200 µm.

[0078] The respective width of the at least two first surface regions can be determined, for example, as described in the context of the method according to the invention. For example, it is possible for the respective width of the at least two first surface regions to vary along their course.

[0079] According to a further preferred embodiment of the component according to the invention, the at least one sealing bead has a bead roof (running along the course of the respective sealing bead) as well as a first and a second bead flank each adjoining the bead roof (running along the course of the respective sealing bead), wherein - at least one of the at least two first surface areas is arranged on an edge of the first bead flank directly adjacent to the bead roof and / or on the bead roof, preferably on an edge of the bead roof directly adjacent to the first bead flank, and at least one further of the at least two first surface areas is arranged on an edge of the second bead flank directly adjacent to the bead roof and / or on the bead roof, preferably on an edge of the bead roof directly adjacent to the second bead flank, and / or - the at least one second surface area is arranged on the bead roof, wherein preferably • the at least one second surface area is arranged exclusively on the corrugated roof, and / or • the at least one second surface area extends over the entire width of the corrugated roof or in sections over the width of the corrugated roof.

[0080] It is particularly preferred that the at least one second surface area extends across the entire width of the bead roof. This enables the maximum available width of the surface of the bead roof to be utilized and thus ensures the maximum possible sealing width of the elastomeric sealing element. Furthermore, it is particularly preferred that the at least one second surface area is arranged exclusively on the bead roof, as this allows a very good sealing effect to be achieved with low material consumption. Overall, it is therefore particularly preferred if the at least one second surface area is arranged exclusively on the bead roof and extends across the entire width of the bead roof, as this allows a particularly good sealing effect to be achieved.

[0081] The sealing bead has bead feet that border the bead flanks and are therefore no longer part of the sealing bead itself.

[0082] The bead roof or the bead roofs and / or the bead flanks can be designed as previously described in the context of the method according to the invention, the statements made there applying analogously here.

[0083] A further preferred embodiment of the component according to the invention is characterized in that the at least one second surface area under the at least one elastomeric sealing element has a further surface structuring with a plurality of further depressions, wherein preferably the further depressions - have a width and / or a diameter in the range from 10 µm to 150 µm, preferably from 20 µm to 100 µm, particularly preferably from 30 µm to 70 µm, and / or - have a depth of at least 2 µm and / or at most 40 µm and / or a depth of at most 20% of the thickness of the metallic layer, and / or - were produced by laser radiation, preferably by irradiation using a pulsed laser, or by microstructuring embossing.

[0084] The further surface structuring differs from the surface structurings exhibited by the at least two first surface regions. Thus, the further surface structuring is not a surface structuring that comprises periodic structures comprising alternatingly arranged, substantially strip-shaped elevations and depressions, as well as nanostructures in the form of substantially point-shaped elevations arranged (at least) on the substantially strip-shaped elevations. Preferably, the further depressions differ from the substantially strip-shaped depressions of the periodic structures.

[0085] The further surface structuring can improve the adhesion of the at least one elastomeric sealing element to the metallic layer, in particular when the at least one elastomeric sealing element contains a foamed material with microspheres.

[0086] The width and / or diameter of the additional depressions can be determined, for example, using SEM (scanning electron microscopy) or using SEM images. The width and / or diameter can be measured, for example, halfway up the depressions and / or parallel to the untreated surface of the metallic layer. The depth of the additional depressions can be determined, for example, using SEM (scanning electron microscopy). The depth can be measured, for example, from the untreated surface of the metallic layer to the deepest point of the depression. The untreated surface is a surface directly adjacent to another depression or its surroundings, which may appear as an elevation. If the additional depression is located on a bead roof, this untreated surface is also part of the bead roof.

[0087] By ensuring that the depth of the additional depressions, which are deeper than the surface structuring with strip-like elevations and depressions, is no more than 20% of the thickness of the metallic layer, it can be ensured that the metallic layer does not exhibit any material weaknesses that could lead to leaks or fractures during operation. The thickness of the metallic layer is sometimes also referred to as the thickness of the metallic layer.

[0088] With regard to the further, in particular geometric properties of the further depressions and the structures surrounding them, reference is made to DE 10 2021 204 497, which is hereby incorporated in its entirety into this document by way of reference.

[0089] The additional recesses can preferably be created using laser radiation. Alternatively, the additional recesses can also be created mechanically, e.g., by embossing or scoring the metallic layer.

[0090] A further preferred embodiment of the component according to the invention is characterized in that the component is a bipolar plate for an electrochemical system, preferably for a fuel cell or for a fuel cell stack, or a sealing frame for an electrochemical system, preferably for an electrolysis cell. The electrochemical system is preferably an electrochemical cell or a stack comprising several electrochemical cells.

[0091] According to a further preferred embodiment of the component according to the invention, the component can be produced or is produced by the method according to the invention.

[0092] The present invention also relates to an electrochemical system comprising at least one component according to the invention. The electrochemical system is preferably an electrochemical cell, e.g., a fuel cell or an electrolysis cell, or a stack comprising a plurality of electrochemical cells, e.g., a fuel cell stack.

[0093] The present invention will be explained in more detail with reference to the following figures and examples, without limiting it to the specific embodiments and parameters shown here. Fig. 1 shows a schematic perspective view of an electrochemical system with a plurality of bipolar plates arranged in a stack; Fig. Figure 2a shows schematically in a perspective view two bipolar plates of the system according to Fig. 1 with a membrane electrode assembly (MEA) arranged between the bipolar plates; Fig. Figure 2b shows schematically the structure of an electrolysis cell with two separator plates and a sealing frame; Fig. Figure 3a shows schematically a section through a portion of an electrochemical system 1 according to the prior art of the type of system 1 from Fig. 1 and Fig. 2; Fig. 3b shows an enlarged view of section III from Fig. 3a; Fig. Figure 4a shows schematically a section through a portion of an electrochemical system 1 of the type of system 1 from Fig. 1 and Fig. 2; Fig. 4b shows an enlarged view of section IV from Fig. 4a; Fig. 5a shows an SEM image of the surface structuring of one of the first surface areas; Fig. 5b an enlarged view of a section of the SEM image from Fig. 5a; Fig. Figure 6a shows an SEM image of the surface structuring of one of the first surface areas after aging; Fig. 6b an enlarged view of a section of the SEM image from Fig. 6a; Fig. 7 shows an SEM image of the surface structuring of one of the first surface areas; Fig. 8a schematically shows a section of a portion of a metallic layer in the form of a metallic plate 2c during the implementation of an exemplary embodiment of the method according to the invention for producing a component for electrochemical system 1; Fig. 8b schematically shows a section of a portion of a metallic layer in the form of a metallic plate 2c during the implementation of an exemplary embodiment of the method according to the invention for producing a component for electrochemical system 1; Fig. 9 schematically shows a section of a portion of a metallic layer in the form of a metallic plate 2c during the implementation of an exemplary embodiment of the method according to the invention for producing a component for electrochemical system 1; Fig. 10 shows an SEM image of the further surface structuring of the second surface area; Fig. 11 schematically shows a section of a portion of a metallic layer in the form of a metallic plate 2c during the implementation of an exemplary embodiment of the method according to the invention for producing a component for electrochemical system 1; Fig. Figure 12a shows schematically a plan view of a section of a metallic layer in the form of a metallic plate 2c, as shown in Fig. 11 is shown; Fig. Figure 12b shows schematically a plan view of a section of a metallic layer in the form of a metallic plate 2c, as shown in Fig. 11 is shown; and Fig. 13 shows a flow chart of the method according to the invention.

[0094] Here and in the following, features that recur in various figures are designated by the same or similar reference symbols.

[0095] Fig. Figure 1 shows an electrochemical system 1 with a plurality of identical metallic bipolar plates 2, which are arranged in a stack 6 and stacked along a z-direction 7. The bipolar plates 2 of the stack 6 are clamped between two end plates 3, 4. The z-direction 7 is also called the stacking direction. In the present example, the system 1 is a fuel cell stack. Two adjacent bipolar plates 2 or the mutually facing separator plates 2a, 2b, each of these bipolar plates 2 of the stack, thus delimit an electrochemical cell, which serves, for example, to convert chemical energy into electrical energy. To form the electrochemical cells of the system 1, a membrane electrode assembly (MEA) is arranged between each adjacent bipolar plate 2 of the stack (see, for example, Fig. 2a). The MEA typically includes at least one membrane, e.g., an electrolyte membrane. Furthermore, a gas diffusion layer (GDL) may be disposed on one or both surfaces of the MEA.

[0096] In alternative embodiments, system 1 can also be configured as an electrolyzer, an electrochemical compressor, or a redox flow battery. Bipolar plates can also be used in these electrochemical systems. The structure of these bipolar plates can then correspond to the structure of the bipolar plates 2 explained in more detail here, even if the media flowing onto or through the bipolar plates in an electrolyzer, an electrochemical compressor, or a redox flow battery may differ from the media used in a fuel cell system.

[0097] The z-axis 7, together with an x-axis 8 and a y-axis 9, spans a right-handed Cartesian coordinate system. The bipolar plates 2 each define a plate plane, wherein the plate planes of the separator plates 2a, 2b of the bipolar plates 2 are each aligned parallel to the xy-plane and thus perpendicular to the stacking direction or to the z-axis 7. The end plate 4 has a plurality of media connections 5 via which media can be supplied to the system 1 and via which media can be removed from the system 1. These media that can be supplied to the system 1 and removed from the system 1 can include, for example, fuels such as molecular hydrogen or methanol, reaction gases such as air or oxygen, reaction products such as water vapor or depleted fuels, or coolants such as water and / or glycol.

[0098] Fig. Figure 2a shows in perspective two adjacent bipolar plates 2 of an electrochemical system of the type of system 1 from Fig. 1 and a membrane electrode assembly (MEA) 10 known from the prior art arranged between these adjacent bipolar plates 2, wherein the MEA 10 in Fig. 2 is largely covered by the bipolar plate 2 facing the viewer. The bipolar plate 2 is formed from two materially joined separator plates 2a, 2b, of which Fig. 2, only the first separator plate 2a facing the viewer is visible, concealing the second separator plate 2b. The separator plates 2a, 2b can each be made of a metal sheet, e.g., a stainless steel sheet. The separator plates 2a, 2b can be welded to one another, e.g., by laser welding.

[0099] The separator plates 2a, 2b have through-openings aligned with one another, which form the through-openings 11a-c of the bipolar plate 2. When stacking a plurality of bipolar plates of the type bipolar plate 2, the through-openings 11a-c form lines that extend in the stacking direction (or z-direction 7) through the stack 6 (see Fig. 1). Typically, each of the lines formed by the through-openings 11a-c is in fluid communication with one of the media connections 5 in the end plate 4 of the system 1. For example, coolant can be introduced into the stack or discharged from the stack via the lines formed by the through-openings 11a. The lines formed by the through-openings 11b, 11c, on the other hand, can be designed to supply the electrochemical cells of the fuel cell stack 6 of the system 1 with fuel and reaction gas, as well as to discharge the reaction products from the stack. The media-carrying through-openings 11a-c are designed essentially parallel to the plate plane.

[0100] To seal the through-openings 11a-c from the interior of the stack 6 and from the environment, the first separator plates 2a usually each have sealing arrangements in the form of sealing beads 12a-c, which are each arranged around the through-openings 11a-c and which completely enclose the through-openings 11a-c. The second separator plates 2b have, on the side visible from the viewer of the Fig. 2 opposite rear side of the bipolar plates 2 corresponding sealing beads for sealing the through openings 11a-c (not shown).

[0101] In an electrochemically active area 18, the first separator plates 2a have, at their side facing the observer, Fig. 2a facing front side, a flow field 17 with structures for guiding a reaction medium along the front side of the separator plate 2a. These structures are shown in Fig. 2a is given by a multitude of bridges and channels running between the bridges and delimited by the bridges. At the point where the viewer sees the Fig. 2, the first separator plates 2a each have a distribution or collection region 20. The distribution or collection region 20 comprises structures that are configured to distribute a medium introduced from a first of the two through-openings 11b into the distribution or collection region 20 over the active region 18 and / or to collect or bundle a medium flowing from the active region 18 to the second of the through-openings 11b. The distribution structures of the distribution or collection region 20 are in Fig. 2a also by webs and channels running between the webs and delimited by the webs.

[0102] The sealing beads 12a-12c generally have passages 13a-13c, of which the passages 13a are formed both on the underside of the upper separator plate 2a and on the upper side of the lower separator plate 2b, while the passages 13b are formed in the upper separator plate 2a and the passages 13c are formed in the lower separator plate 2b. For example, the passages 13a, which here are at least partially designed as local elevations of the bead, enable the passage of coolant between the through-opening 12a and the distribution area and further to the cavity 19 between the separator plates 2a and 2b in the active area 18. This allows the coolant to enter the distribution area between the separator plates or to enter the cavity 19 in the active area 18, or to be led out of it.Furthermore, the feedthroughs 13b allow hydrogen to pass between the through-opening 12b and the distribution area on the upper side of the upper separator plate 2a; these feedthroughs 13b are characterized by perforations facing the distribution area and running transversely to the plate plane. Thus, for example, hydrogen flows through the feedthroughs 13b from the through-opening 12b to the distribution area on the upper side of the upper separator plate 2a or in the opposite direction. The feedthroughs 13c allow air to pass between the through-opening 12c and the distribution area, so that air enters or is led out of the distribution area on the underside of the lower separator plate 2b. The corresponding perforations are not visible here. The bead feedthroughs usually extend only in the area of ​​the bead flanks and not into the area of ​​the bead roof.

[0103] The first separator plates 2a typically each further comprise a further sealing bead 12d in the form of a perimeter bead, which surrounds the flow field 17 of the active region 18, the distribution or collection region 20, and the through-openings 11b, 11c and seals them from the through-opening 11a, i.e., from the coolant circuit, and from the environment of the system 1. The second separator plates 2b each comprise corresponding perimeter beads. The structures of the active region 18, the distribution structures of the distribution or collection region 20, and the sealing beads 12a-d are each formed integrally with the separator plates 2a and molded into the separator plates 2a, e.g., in a stamping process, deep-drawing process, and / or by hydroforming. The same applies to the corresponding distribution structures and sealing beads of the second separator plates 2b.

[0104] Fig. Figure 2b shows an exploded view of an electrochemical single cell 49, wherein the single cell 49 is a component of an electrolyzer. Electrolyzers typically comprise a plurality of stacked single cells 49. The single cell 49 comprises two separator plates 2d and 2e, two cell frames 42 and 44, a sealing frame 40, and a membrane-electrode assembly 45 with media diffusion structures 41 and 43. The media diffusion structure 43 comprises, for example, layers of carbon fleece, while the media diffusion structure 41 comprises metal, e.g., titanium. The separator plate 2d is arranged here, for example, on the anode side of the single cell 49. The separator plate 2e is arranged on the cathode side of the single cell 49 in the illustrated embodiment. The individual layers are pressed together to form a single cell. The individual layers each have through openings 46, 47, 48 arranged one above the other in alignment for entry and exit.Leading out water, oxygen, and hydrogen, as well as positioning holes 50. By projecting the cell frame 44 onto the separator plate 2e, a flow field of the separator plate 2e is defined. By projecting the cell frame 42 onto the separator plate 2d, a flow field 51 of the separator plate 2d is defined. The cell frame 42 has distribution channels (not shown) for distributing the introduced water. The through-openings 46, 47 are in fluid communication with the flow field 51 so that a medium can be guided from the through-opening 46 to the flow field 51 or from the flow field 51 to the through-opening 47. The through-openings 46, 47, together with the flow field 51, are surrounded by a sealing bead 12e, which seals this flow area to the outside. The through-openings 48 are surrounded by their own sealing beads 12e'. Further sealing beads 12f, 12g are formed in the separator plate 2d and the sealing frame 40, respectively.The separator plates 2d, 2e and the sealing frame 40 thus form further components within the meaning of this document.

[0105] Fig. 3a and Fig. 4a each show schematically a section through a portion of an electrochemical system 1 of the type of system 1 from Fig. 1 and Fig. 2, where the cutting plane is aligned in the z-direction and thus perpendicular to the plate planes of the bipolar plates 2. In Fig. 3a and Fig. 4a (as well as in the detailed representations of the Fig. 3b and Fig. 4b) shows sections through two separator plates of a bipolar plate, but the same applies to components with only one layer, such as a single-layer separator plate 2d, 2e or a single-layer sealing frame 40. Unlike in Fig. 1-3 now also show the coatings of the sealing beads.

[0106] The electrochemical system from Fig. 3a differs from the electrochemical system Fig. 4a with regard to the components, for example bipolar plates. The bipolar plates of the electrochemical system are made of Fig. 3a are bipolar plates according to the prior art or bipolar plates manufactured according to the prior art, whereas the bipolar plates of the electrochemical system are Fig. 4a are exemplary bipolar plates according to the invention or bipolar plates produced according to an exemplary embodiment of the method according to the invention. The bipolar plates from the electrochemical system of Fig. 3a are identical in construction. Likewise, the bipolar plates of the electrochemical system are made of Fig. 4a are identical to each other.

[0107] The bipolar plates 2 of the system in Fig. 3a and the bipolar plates 2 of the system in Fig. 4a each comprise the previously described first metallic separator plate 2a and the previously described second metallic separator plate 2b. Each metallic separator plate 2a, 2b can have a material thickness of approximately 75 µm. Sealing arrangements in the form of sealing beads 12b can be seen, which are arranged around a through-opening 11b. Some of the sealing beads 12b have through-openings 13b. The two separator plates 2a, 2b rest on one another in a contact area 23 and are connected to one another there, in the present example by means of laser welds. The metallic separator plates 2a, 2b can be formed, for example, from stainless steel and / or at least one titanium alloy, or from a stainless steel core with at least one surface made of a titanium alloy.

[0108] In the Fig. 3a and Fig. 4a, four bipolar plates 2 are shown, with a membrane electrode assembly (MEA) 10 being arranged between each bipolar plate 2, the edge region 15 of which can be seen in the section shown. The MEA 10 typically comprises a membrane (not shown in Fig. 3a and Fig. 4a), e.g. an electrolyte membrane, and a sealing edge region 15 connected to the membrane.

[0109] The membrane of the MEA 10 extends at least over and thus defines the active region 18 of the adjacent bipolar plates 2, enabling proton transfer over or through the membrane. The membrane does not extend into the distribution or collection region 20. The sealing edge region 15 of the MEA 10 serves to position, secure, and seal the membrane between the adjacent bipolar plates 2. When the bipolar plates 2 of the system 1 are clamped in the stacking direction between the end plates 3, 4 (see Fig. 1), the sealing edge region 15 of the MEA 10 can, for example, be pressed between the sealing beads 12a-d of the respective adjacent bipolar plates 2 in order to fix and seal the MEA 10 between the adjacent bipolar plates 2.

[0110] The sealing edge region 15 covers the distribution or collection region 20 of the adjacent bipolar plates 2. The edge region 15 can also extend outwards beyond the sealing bead 12d and also beyond the outer edge region of the separator plates 2a, 2b (cf. Fig. 2a).

[0111] In Fig. 3b is now an enlarged view of section III from Fig. 3a, which shows a sealing bead 12b. Accordingly, Fig. 4b an enlarged view of section IV from Fig. 4a, which shows a sealing bead 12b. The sealing beads 12b each have a bead roof 24 running along the main direction of the respective sealing bead, as well as a first and a second bead flank 25a and 25b adjacent to the bead roof 24 and running along the main direction of the respective sealing bead. A bead base 22a and 22b adjoins the sealing bead 12 laterally.

[0112] The Fig. 3a / b and Fig. The corrugated roofs 24 shown in Figures 4a / b have no curvature (or are flat), but can alternatively have a curvature with a radius of at least 1 mm, preferably at least 2 mm. Likewise, the corrugated roof can have multiple curvatures in its cross-section; for example, convex and concave curvatures can alternate. The individual curvatures can be identical or different.

[0113] Preferably, the bead flanks 25a and 25b of the respective sealing bead 12b each have a minimum angle to the plane of the bead base in the range from 15° to 75°, preferably from 25° to 65°.

[0114] Preferably, the bead flanks 25a and 25b of the respective sealing bead 12b are tangentially connected to the bead roof 24 of the respective sealing bead 12b with a radius of at least 0.05 mm, preferably at least 0.2 mm. This radius can be considered part of the bead flank 25a, 25b. Corresponding radii are shown in Fig. 3a / b and Fig. 4a / b are not shown, but they are Fig. 8a, Fig. 8b and Fig. 9 clearly.

[0115] Preferably, the bead flanks 25a and 25b of the respective sealing bead 12b are each connected tangentially to the bead bases with a radius of at least 0.05 mm, preferably at least 0.2 mm. Here, too, the corresponding radii are Fig. 3a / b and Fig. 4a / b are not shown, but they are Fig. 8a, Fig. 8b and Fig. 9 clearly.

[0116] As already mentioned, the bipolar plates 2 of the electrochemical system are made of Fig. 3a / b are bipolar plates 2 according to the prior art or bipolar plates manufactured according to the prior art. In this case, the bipolar plate 2 has Fig. 3a / b an elastomeric sealing element 26, which was produced by applying at least one apolar liquid coating material to the bead roofs 24 of the sealing beads 12b, 12d. During and / or after the application of the liquid coating material, this has flowed from the bead roofs 24 of the sealing beads 12b, 12d onto the bead flanks 25a and 25b. As a result, the coating now covers not only the bead roofs 24 but also (partially) the bead flanks 25a and 25b. Due to this, the bipolar plates 2 of the electrochemical system comprise Fig. 3a / b, however, losses occur in the final height of the elastomeric sealing element 26, resulting in higher leakage rates. The detailed illustration shows an example of an elastomeric sealing element 26 on the bead 12b of the separator plate 2b, which has a significantly too low height, so that a leak occurs even at minimal pressure differences.

[0117] In contrast to the bipolar plates 2 of the electrochemical system made of Fig. 3a / b are the bipolar plates 2 of the electrochemical system made of Fig. 4a / b now show exemplary bipolar plates 2 according to the invention or bipolar plates 2 produced using an exemplary embodiment of the method according to the invention. The sealing beads 12b, 12d of these bipolar plates 2 each have two first surface regions 27 and a second surface region 28 arranged between the two first surface regions 27 and directly adjacent to the two first surface regions 27. The second surface region 28 is provided or coated with an elastomeric sealing element 26, wherein the second surface region 28 is arranged exclusively on the bead roof 24 and extends over the entire width of the bead roof 24.One of the two first surface regions 27 is arranged on an edge of the first bead flank 25a directly adjacent to the bead roof 24, and the other of the two first surface regions 27 is arranged on an edge of the second web flank 25b directly adjacent to the bead roof 24, wherein each of the two first surface regions 27 directly adjoins the second surface region 28 provided with an elastomeric sealing element. In addition, the two first surface regions 27 and the second surface region 28 run essentially parallel to a main direction of extension of the respective sealing bead 12b, 12d and preferably extend over the entire length or the entire extension of the respective sealing bead 12b, 12d. The two first surface regions 27 can each have a width in the range from 90 µm to 460 µm, preferably from 95 µm to 300 µm, particularly preferably from 100 µm to 200 µm.

[0118] The first two surface areas 27 each have a special surface structure. Fig. Figure 5a shows an SEM image of such a surface structuring. Fig. 5b an enlarged view of the SEM image from Fig. 5a. The surface structurings of the first two surface regions 27 have periodic structures and nanostructures 31, wherein the periodic structures comprise alternately arranged, essentially strip-shaped elevations 29 and depressions 30, and wherein the nanostructures 31 are designed in the form of essentially point-shaped elevations and are arranged (at least) on the essentially strip-shaped elevations 29. These special surface structurings now enable simplified application of the apolar liquid coating material during the production of the bipolar plates 2. Thus, the special surface structurings have hydrophilic, preferably superhydrophilic, properties during the production of the bipolar plate 2 and thus act as a type of flow stopper for an apolar liquid coating material which comprises at least one component or component forming at least one elastomer.comprises at least one elastomer precursor (and optionally at least one crosslinker) (or consists of at least one component forming at least one elastomer or at least one elastomer precursor and optionally at least one crosslinker), so that such a coating material applied to the second surface region 28 stops at the edge of the second surface region 28 directly adjacent to the two first surface regions 27 and does not flow onto or over the two first surface regions 27. The surface structures thus act as a type of flow stopper for the apolar liquid coating material comprising the at least one component forming the at least one elastomer, so that the elastomeric sealing element 26 is ultimately arranged only on the second surface region 28.This ultimately enables very precise application of the liquid coating material and thus also coating of the sealing beads with increased accuracy, since it can be ensured that the coating material actually only reaches the area of ​​the respective sealing bead 12b, 12d to be coated, i.e. in the present example the second surface area 28, and thus only this area is coated. In particular, in the present example the surface structuring on the sealing beads 12b, 12d can prevent the suspension from flowing onto the bead flanks 25a and 25b, even if, for example, the suspension has a relatively low viscosity and thus a relatively high flow tendency. Accordingly, in the bipolar plates of the electrochemical system made of . Fig. 4a / b, the elastomeric sealing element 26 is arranged only on the bead roofs 24 and not on the bead flanks 25a and 25b. As a result, a very good sealing effect can be achieved with low material consumption. In particular, the various beads of the Fig. 4a have a substantially identical profile of the elastomeric sealing element 26 on their bead roofs 24, which leads to a uniform sealing effect.

[0119] In addition, the special surface structures simplify the application of the liquid coating material, since, for example, the viscosity and the wet layer thickness of the applied coating material no longer need to be adjusted so precisely in order to reduce the risk of the liquid coating material flowing into an area that is not to be coated.

[0120] Due to the special surface structuring, the elastomeric sealing element 26 on the respective sealing beads 12b, 12d can also preferably have a particularly high thickness, e.g., a maximum thickness of at least 20 µm, preferably at least 80 µm in the case of foamed material, since the surface structuring allows a larger amount of coating material to be applied to the area to be coated without any of the coating material flowing off. Consequently, a higher wet layer thickness and thus also a higher dry layer thickness can be achieved than in the prior art.

[0121] The special surface structures can be produced by laser treatment, see process step L in the flow chart of the Fig. 13. During the laser treatment, the two first surface regions 27 are irradiated by means of a pulsed laser with laser pulses having a pulse duration of less than 1 ns, preferably less than 100 ps, ​​particularly preferably less than 50 ps. In particular, picosecond or femtosecond lasers, which are collectively referred to as ultrashort pulse lasers, can be used for the laser treatment. Preferably, the fluence introduced into the two first surface regions by irradiation with the laser pulses is in the range of 15 J / cm 2 up to 120 J / cm 2 , preferably 20 J / cm 2 up to 100 J / cm 2 , particularly preferably 25 J / cm 2 up to 80 J / cm 2 .

[0122] The elastomeric sealing element 26 on the second surface area 28 was produced by first applying at least one apolar liquid coating material comprising at least one component forming at least one elastomer to the at least one second surface area, cf. process step C in the flow diagram of the Fig. 13. This application can preferably be carried out using a method selected from the group consisting of screen printing, roller printing, stencil printing, dispensing (i.e., dispenser application), and combinations thereof. The formation of the at least one elastomeric sealing element from the applied apolar liquid coating material takes place, for example, by at least partial crosslinking of the applied coating material. This at least partial crosslinking can be triggered, for example, by a sudden temperature change, e.g., by an increase to a second temperature, or by UV radiation.

[0123] Preferably, the second surface region 28 is provided with the elastomeric sealing element 26, in particular the application of the at least one apolar liquid coating material, at the latest 72 hours after, preferably at the latest 24 hours after, particularly preferably at the latest 6 hours after, very particularly preferably at the latest 3 hours after, in particular at the latest 1 hour after, for example directly after, the laser treatment for producing the surface structuring on the two first surface regions 27.

[0124] Through REM images, as shown in Fig. 5a / b, the surface structures can be characterized more precisely. As already mentioned, Fig. 5b an enlarged view of a section of the SEM image from Fig. 5a. Furthermore, Fig. 7 shows another SEM image showing a larger section of the surface structuring. Fig. 5a / 5b and 7 show different sections of the same sample shortly after laser treatment, ie without significant aging. In addition, Fig. 6a shows an SEM image of the surface structuring after aging, where in Fig. 6b an enlarged view of a section of the SEM image from Fig. 6a. Again, this is a section of the same sample, but not the same section.

[0125] The periodic structures are structures that are arranged periodically to one another in at least one spatial direction. Thus, the shape of the periodic structures on the surface is repeated in at least one spatial direction. The average spatial period of the periodic structures is less than 10 µm, preferably at most 2 µm. The spatial period typically refers to the maximum distance between two adjacent structures of the same or similar shape, e.g., two of the essentially strip-shaped elevations 29 or two of the essentially strip-shaped depressions 30. Due to manufacturing reasons, the structures are not completely identical to one another. Thus, the period along the surface is subject to certain fluctuations. For example, the periodic structures can have a period in a spatial direction running perpendicular to the surface (e.g.,the spatial direction x) running parallel to the x-axis 8 is less than 10 µm, preferably at least 0.3 µm and / or at most 2 µm.

[0126] The periodic structures comprise alternatingly arranged, essentially strip-shaped elevations 29 and depressions 30, ie, the periodic structures comprise essentially strip-shaped elevations 29 and essentially strip-shaped depressions 30, wherein these elevations 29 and depressions 30 are arranged alternately or alternately, ie, the depressions 30 each extend between the (or two of) the elevations 29 and are delimited and / or formed by them. In addition, the essentially strip-shaped elevations 29 and / or depressions 30 can also be partially branched, as can be seen from Fig. 7 can be seen.

[0127] The essentially strip-shaped elevations 29 have a width in the range from 250 nm to 700 nm, preferably from 350 nm to 600 nm, and the essentially strip-shaped depressions 30 have a width in the range from 100 nm to 550 nm, preferably from 200 nm to 450 nm. The width is typically measured at half height and perpendicular to the local longitudinal direction of the depressions 30 or the elevations 39. The length is typically measured along the longitudinal direction (or the course) of the depressions 30 or the elevations 29.

[0128] Furthermore, the essentially strip-shaped depressions 30 have a depth in the range of 0.05 to 0.7 µm. The depth of the essentially strip-shaped depressions 30 can be determined, for example, by means of SEM (scanning electron microscopy) or using SEM images. The depth is typically measured perpendicular to the surface formed by the essentially strip-shaped elevations. For example, the depth of the essentially strip-shaped depressions 30 can vary along the course of the individual depressions 30.

[0129] The nanostructures 31 are formed in the form of essentially point-shaped elevations. Furthermore, the nanostructures 31 or the essentially point-shaped elevations are arranged at least on the essentially strip-shaped elevations 29. In addition, the nanostructures 31 in the form of essentially point-shaped elevations can also be arranged on (or in) the essentially strip-shaped depressions 30. However, it is possible for the nanostructures 31 in the form of essentially point-shaped elevations to be arranged exclusively on the essentially strip-shaped elevations 29. A respective peripheral edge of the essentially point-shaped depressions can be essentially round (or circular), essentially elliptical, or essentially oval.

[0130] Preferably, the nanostructures 31 are arranged in the form of essentially point-shaped elevations on the interfaces of the essentially strip-shaped elevations 29. The interface of the respective elevation 29 represents the entire surface area of ​​the respective elevation 29 that lies above half the height of the elevation 29, measured between the lowest point of an adjacent depression 30 and the highest point of the elevation 29.

[0131] The nanostructures 31 (each) have an average diameter in the range from 10 nm to 200 nm, preferably from 30 nm to 150 nm, particularly preferably from 50 nm to 120 nm, and (each) a maximum diameter in the range from 10 nm to 300 nm, preferably from 30 nm to 250 nm, particularly preferably from 50 nm to 200 nm. For example, the nanostructures 31 (each) can have a minimum diameter in the range from 5 to 60 nm, preferably from 10 to 55 nm, particularly preferably from 15 to 50 nm. Typically, the average diameter of the individual nanostructures 31 varies from nanostructure 31 to nanostructure 31 over a certain range, ie the nanostructures 31 are of different sizes.

[0132] Furthermore, the surface area of ​​the nanostructures 31 is in the range of 80 nm 2 up to 40000 nm 2 , preferably from 800 nm 2 up to 20,000 nm 2 , particularly preferably from 2000 nm 2 up to 10000 nm 2The surface area of ​​a nanostructure 31 can be understood as the size of the area that the nanostructure 31 covers or occupies in a plan view of the surface on which it is located. Typically, the surface area of ​​the individual nanostructures 31 varies from nanostructure 31 to nanostructure 31 over a certain range, i.e., the nanostructures 31 are of different sizes.

[0133] The surface structures of the first surface areas 27 can age over time. In Fig. Figure 6a shows an SEM image of such an aged surface structuring, where Fig. 6b an enlarged view of a section of the SEM image from Fig. 6a. The aged surface structurings also have the periodic structures, which comprise the alternating, essentially strip-shaped elevations 29 and depressions 30, as well as the nanostructures 31 in the form of essentially point-shaped elevations, which are arranged (at least) on the essentially strip-shaped elevations 29. However, as the surface structurings age, the areal density of the nanostructures 31 increases, at least on the essentially strip-shaped elevations 29. The areal density of the nanostructures is understood here to be the proportion of the area of ​​the total area of ​​the essentially strip-shaped elevations 29 that the nanostructures 31 in the form of point-shaped elevations occupy or cover.The age-related increase in the areal density of the nanostructures leads to changed properties of the relevant surface area; the hydrophilic properties change into hydrophobic properties with an increase in this areal density and the surface structures can no longer serve as a flow stopper for an apolar coating mass or coating suspension after ageing.

[0134] In Fig. 8a, Fig. 8b and Fig. 9 schematically shows a section of a portion of a metallic layer in the form of a metallic plate 2c during the implementation of an exemplary embodiment of the method according to the invention for producing a component for an electrochemical system, which component can be used, for example, in an electrochemical system 1 of the type of system 1 from Fig. 1 and Fig. 2a or Fig. 2b can be used. The metallic plate 2c can thus, for example, represent a separator plate that can be connected to another separator plate to obtain a bipolar plate or a separator plate 2d, 2e of an electrolyzer cell that can be used individually. The metallic plate 2c can also already be connected to another separator plate at the time the method step is carried out. However, the metallic plate 2c can also represent a sealing frame 40 that can be arranged on or around a separator plate. Fig. 8a and Fig. 8b relate to two different exemplary embodiments of the method according to the invention, which lead to two different exemplary embodiments of the component according to the invention for an electrochemical system, which differ from one another in the different position of the first and second surface regions 27 and 28. In Fig. Finally, Figure 9 shows an embodiment which differs from that shown in Fig. 8b only in that a different coating material was used, specifically a foamed coating material with inflated microspheres 33, and that before or after the surface structuring on the two first surface areas, the second surface area was provided with a further surface structuring, which has a plurality of further depressions 32. In principle, however, the foamed coating material could also be used independently of the further depressions 32. The position of the first and second surface areas 27 and 28 is in the embodiments of Fig. 8b and Fig. 9, however, is the same.

[0135] In all three versions of the Fig. 8a, Fig. 8b and Fig. 9, the metallic plate 2c comprises several sealing beads 12. In the Fig. 8a-b and Fig. In the sections shown in Figure 9, only one of the sealing beads 12 is shown as an example. The sealing beads 12 each have a bead roof 24 running along the main direction of the respective sealing bead, as well as a first and a second bead flank 25a and 25b adjacent to the bead roof 24 and running along the main direction of the respective sealing bead. A bead base 22a and 22b adjoins the sealing bead 12 laterally.

[0136] In all three versions of the Fig. 8a, Fig. 8b and Fig. 9, the sealing beads 12 have two first surface areas 27 and a second surface area 28 arranged between the two first surface areas 27 and directly adjacent to the two first surface areas 27. In addition, in all three embodiments of the Fig. 8a, Fig. 8b and Fig. 9 the two first surface regions 27 and the second surface region 28 are substantially parallel to a main direction of extension of the respective sealing bead 12 and preferably extend over the entire length or the entire extension of the respective sealing bead 12. In all three cases, the two first surface regions 27 can each have a width in the range from 90 µm to 460 µm, preferably from 95 µm to 300 µm, particularly preferably from 100 µm to 200 µm.

[0137] In both versions of the Fig. 8a, Fig. 8b shows a moment of the process in which the at least one apolar liquid coating material comprising at least one component forming at least one elastomer has just been applied to the second surface region 28, so that a wet layer 26a of the liquid coating material is arranged on the second surface region 28. From this, for example, an elastomeric sealing element can be formed by at least partial crosslinking. Fig. 9, however, the elastomer sealing element is already partially cross-linked and foamed.

[0138] Accordingly, in all three embodiments of the Fig. 8a, Fig. 8b and Fig. 9, the two first surface regions 27 each have a special surface structuring produced by laser treatment. The surface structuring of the first two surface regions 27 has periodic structures and nanostructures 31, wherein the periodic structures comprise alternatingly arranged substantially strip-shaped elevations 29 and depressions 30, and wherein the nanostructures 31 are formed in the form of substantially punctiform elevations and are arranged (at least) on the substantially strip-shaped elevations 29.

[0139] In Fig. 8a, one of the two first surface regions 27 is arranged on an edge of the bead roof 24 directly adjacent to the first bead flank 25a, and the other of the two first surface regions 27 is arranged on an edge of the bead roof 24 directly adjacent to the second bead flank 25b. The second surface region 28 extends almost (but not completely) over the entire width of the bead roof 24, so that the bead roof 24 is coated with the wet layer 26a almost (but not completely) over its entire width. Due to the surface structuring on the two first surface regions 27, the liquid coating material does not flow onto the bead flanks 25a and 25b, but stops at the two first surface regions 27. Accordingly, the ultimately obtained elastomeric sealing element is arranged only on the bead roof 24 and not on the bead flanks 25a and 25b.As a result, a very good sealing effect can be achieved with low material consumption.

[0140] In Fig. 8b, one of the two first surface regions 27 is arranged on an edge of the first bead flank 25a directly adjacent to the bead roof 24, and the other of the two first surface regions 27 is arranged on an edge of the second bead flank 25b directly adjacent to the bead roof 24. The second surface region 28 extends over the entire width of the bead roof 24, so that the bead roof 24 is coated with the wet layer 26a over its entire width. Due to the surface structures on the two first surface regions 27, the liquid coating material does not flow onto the bead flanks 25a and 25b, but stops at the two first surface regions 27. Accordingly, the ultimately obtained elastomeric sealing element is arranged only on the bead roof 24 and not on the bead flanks 25a and 25b. As a result, a very good sealing effect can be achieved with low material consumption. In particular, the Fig. The embodiment shown in Figure 8b utilizes the maximum available width of the corrugated roof surface, thus ensuring the maximum possible sealing width of the elastomeric sealing element. Overall, a particularly good sealing effect can be achieved.

[0141] In addition to the features described here, the metallic plate 2c may be made of Fig. 8a or Fig. 8b, for example, like the separator plates 2a, 2b of the bipolar plate of the electrochemical system from Fig. 4a / b (or in accordance with the relevant specifications). This particularly applies to all information contained therein regarding surface structuring.

[0142] The Fig. The embodiment shown in Figure 9 differs from that shown in Fig. 8b only in that a different coating material was used and that before or after the surface structuring on the two first surface areas was created, the second surface area was provided with a further surface structuring which has a plurality of further depressions 32.

[0143] So, first of all, in the embodiment according to Fig. 9 in contrast to the embodiment in Fig. 8b, the at least one apolar liquid coating material comprises at least one foamable material that additionally comprises expandable microspheres 33. The elastomeric sealing element can be formed here by expanding the microspheres 33. As a result, an elastomeric sealing element is formed that contains or consists of a foamed material with microspheres 33.

[0144] In the expanded state shown, the microspheres 33 can have an average diameter of at least 20 µm and / or at most 150 µm. After the foamable material was applied, a solvent contained in the foamable material was evaporated.

[0145] The further surface structuring located on the second surface region 28 differs from the surface structurings exhibited by the at least two first surface regions 27. Thus, the further surface structuring is not a surface structuring comprising periodic structures comprising alternatingly arranged, substantially strip-shaped elevations and depressions, nor nanostructures in the form of substantially punctiform elevations arranged (at least) on the substantially strip-shaped elevations 29. Furthermore, the further depressions 32 differ from the substantially strip-shaped depressions 30 of the periodic structures.

[0146] In Fig. Figure 10 shows a light microscopic image of the further surface structuring, which allows the further surface structuring to be characterized in more detail.

[0147] Thus, the further depressions 32 of the further surface structuring have a diameter in the range from 50 µm to 80 µm, preferably from 60 µm to 70 µm, particularly preferably approximately 65 µm. In addition, the further depressions 32 have a depth of at least 2 µm and / or at most 40 µm and a depth of at most 20% of the thickness of the metallic layer. The diameter can be measured halfway up the depressions 32 and / or parallel to the untreated surface of the metallic layer. The depth can be measured, for example, from the untreated surface of the metallic layer to the deepest point of the depression 32.

[0148] According to the recording in Fig. 10, a peripheral edge of the further recesses 32 is substantially round (or circular).

[0149] The size of each further depression is in a range of 0.0001 to 0.05 mm 2, especially 0.0008 to 0.02 mm 2 and preferably 0.001 to 0.01 mm 2 In addition, there are about 500 to 100,000, preferably about 4,000 to 20,000, depressions per square centimeter.

[0150] By combining the further surface structuring on the second surface area 28 with the use of a foamable material with microspheres 33 as a coating material, the adhesion of the elastomeric sealing element to the metallic layer can be significantly improved.

[0151] In addition to the features described here, the metallic plate 2c may be made of Fig. 9 for example, like the separator plates 2a, 2b of the bipolar plate of the electrochemical system from Fig. 4a / b (or in accordance with the relevant specifications). This particularly applies to all information contained therein regarding surface structuring.

[0152] In Fig. 11 is a schematic cross-sectional view of a section of a metallic layer in the form of a metallic plate 2c during the implementation of an exemplary embodiment of the method according to the invention for producing a component for an electrochemical system, which component can be used, for example, in an electrochemical system 1 of the type of system 1 from Fig. 1 and Fig. 2 can be used. The metallic plate 2c can thus, for example, represent a separator plate that can be connected to another separator plate to obtain a bipolar plate.

[0153] In the Fig. In the section shown in Figure 11, only one of the sealing beads 12 is shown as an example. The sealing bead 12 has a bead roof 24 running along the main direction of the respective sealing bead, as well as a first and a second bead flank 25a and 25b, each adjacent to the bead roof 24 and running along the main direction of the sealing bead.

[0154] The sealing bead 12 has two first surface regions 27 and a second surface region 28 arranged between the two first surface regions 27 and directly adjacent to the two first surface regions 27. In addition, the two first surface regions 27 and the second surface region 28 run essentially parallel to a main direction of extension of the sealing bead 12 and preferably extend over the entire length or the entire extension of the sealing bead 12. The two first surface regions 27 can each have a width in the range from 90 µm to 460 µm, preferably from 95 µm to 300 µm, particularly preferably from 100 µm to 200 µm.

[0155] In Fig. 11 shows a moment of the process after the laser treatment of the two first surface areas 27 of the sealing bead 12 but before providing the second surface area 28 of the sealing beads 12 with at least one elastomeric sealing element.

[0156] Accordingly, in the Fig. In the embodiment shown in Figure 11, the two first surface regions 27 of the sealing beads 12 each have a special surface structuring produced by laser treatment. The surface structuring of the two first surface regions 27 has periodic structures and nanostructures 31, wherein the periodic structures comprise alternatingly arranged substantially strip-shaped elevations 29 and depressions 30, and wherein the nanostructures 31 are designed in the form of substantially punctiform elevations and are arranged (at least) on the substantially strip-shaped elevations 29 (cf. Fig. 5 to 7).

[0157] If, in the next process step, the second surface region 28 of the sealing bead is provided with at least one elastomeric sealing element or at least one apolar liquid coating material comprising at least one component forming at least one elastomer is applied to the second surface region, the liquid coating material does not flow onto the bead flanks 25a and 25b due to the surface structuring on the two first surface regions 27, but stops at the boundary of the two first surface regions 27. Accordingly, the ultimately obtained elastomeric sealing element is arranged only on the bead roof 24 and not on the bead flanks 25a and 25b. As a result, a very good sealing effect can be achieved with low material consumption.

[0158] In addition to the features described here, the metallic plate 2c may be made of Fig. 11 for example, like the separator plates 2a, 2b of the bipolar plate of the electrochemical system from Fig. 4a / b (or in accordance with the relevant specifications). This particularly applies to all information contained therein regarding surface structuring.

[0159] In Fig. 12a and Fig. 12b is a plan view of a section of a metallic layer in the form of a metallic plate 2c, as shown in Fig. 11. The explanations therein therefore also apply here. In the exemplary embodiment in Fig. 12a, the two first surface areas 27 each have a linear profile. In the exemplary embodiment in Fig. 12b, the two first surface areas 27 have a wavy shape.

[0160] The flow chart of the Fig.Figure 13 summarizes the method according to the invention for producing a component for an electrochemical system. In the first step B, at least one metallic layer with at least one sealing bead formed therein is provided. This can be done, for example, by forming webs and channels into a plate, for example, a stainless steel plate of alloy 1.4404 with a sheet thickness of 0.075 mm. Subsequently, in method step L, at least two first surface regions of the at least one sealing bead are each subjected to at least one laser treatment. The at least two first surface regions are irradiated with laser pulses using a pulsed laser. The first surface regions of the webs can, for example, be subjected to a laser treatment with a laser having a wavelength of 1064 nm and a pulse duration of <15 ps at a frequency of 50 kHz and a total fluence of 80 J / cm 2or a fluence per pulse of 0.577 J / cm 2This creates surface structuring on the at least two first surface regions, which have periodic structures comprising, on the one hand, alternating, essentially strip-shaped elevations and depressions, and, on the other hand, nanostructures in the form of essentially point-shaped elevations arranged at least on the essentially strip-shaped elevations. Subsequently, preferably without delay, in particular after less than 12 hours, at least one second surface region of the at least one sealing bead, which is arranged between the at least two first surface regions and directly borders the at least two first surface regions, is provided with at least one elastomeric sealing element in method step C.In this case, at least one apolar liquid coating material containing at least one component forming at least one elastomer is applied to the at least one second surface area as known from the prior art. List of reference symbols 1 electrochemical system 2 bipolar plates 2a Separator plate 2b Separator plate 2c metallic plate 2d, 2e separator plates 3 End plate 4 End plate 5 Media connection 7 z-direction 8 x-direction 9 γ-direction 10 membrane electrode assembly (MEA) 11a Passage opening 11b Through opening 11c Passage opening 12 sealing bead 12a sealing bead 12b sealing bead 12c sealing bead 12d sealing bead 12e sealing bead 12e' Sealing bead of the through opening 48 12f sealing bead 12g sealing bead 13a Implementation 13b Implementation 13c Implementation 15 Marginal area 17 Flow field 18 active area 19 Cavity 20 Distribution or collection area 22a first bead foot 22b second beading foot 23 Contact area 24 ribbed roof 25a first bead flank 25b second bead flank 26 elastomeric sealing element 26a Wet layer 27 first surface area 28 second surface area 29 essentially strip-shaped elevation 30 essentially strip-shaped depression 31 Nanostructure 32 further deepening 33 Microsphere 40 sealing frames 41 Media diffusion structure 42 cell frames 43 Media diffusion structure 44 cell frames 45 Membrane electrode assembly 46 passage opening 47 passage opening 48 passage opening 49 Single cell of an electrolyzer 50 positioning holes 51 Flow field QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2018 101 316 A1

[0006] DE 10 2021 204 497 [0058, 0088]

Claims

[1] Method for producing a component for an electrochemical system (1), in which a) at least one metallic layer (2c) with at least one sealing bead (12a-g) formed therein is provided, b) at least two first surface regions (27) of the at least one sealing bead (12a-g) are each subjected to at least one laser treatment, in which the at least two first surface regions (27) are irradiated by means of a pulsed laser with laser pulses having a pulse duration of less than 1 ns, wherein the at least one laser treatment produces surface structurings on the at least two first surface regions (27) which have periodic structures comprising alternatingly arranged substantially strip-shaped elevations (29) and depressions (30), as well as nanostructures (31) in the form of substantially punctiform elevations arranged at least on the substantially strip-shaped elevations (29), and c) at least one second surface region (28) of the at least one sealing bead (12a-g), which is arranged between the at least two first surface regions (27) and directly adjoins the at least two first surface regions (27), is provided with at least one elastomeric sealing element (26), wherein at least one apolar liquid coating material comprising at least one component forming at least one elastomer is applied to the at least one second surface region (28). [2] Method according to the preceding claim, characterized by , that - the pulse duration of the laser pulses is less than 100 ps, ​​preferably less than 50 ps, ​​and / or - the fluence introduced into the at least two first surface areas (27) by irradiation with the laser pulses in a range of 15 J / cm 2 up to 120 J / cm 2 , preferably 20 J / cm 2 up to 100 J / cm 2, particularly preferably 25 J / cm 2 up to 80 J / cm 2 , lies. [3] Method according to one of the preceding claims, characterized by that step c) is carried out at the latest 72 hours after step b), preferably at the latest 24 hours after step b), particularly preferably at the latest 6 hours after step b), very particularly preferably at the latest 3 hours after step b), in particular at the latest 1 hour after step b), for example directly after step b). [4] Method according to one of the preceding claims, characterized by , that - the substantially strip-shaped elevations (29) have a width in the range from 250 nm to 700 nm, preferably from 350 nm to 600 nm, and / or the substantially strip-shaped depressions (30) have a width in the range from 100 nm to 550 nm, preferably from 200 nm to 450 nm, and / or - the nanostructures (31) have an average diameter in the range from 10 nm to 200 nm, preferably from 30 nm to 150 nm, particularly preferably from 50 nm to 120 nm, and / or - the nanostructures (31) have a maximum diameter in the range from 10 nm to 300 nm, preferably from 30 nm to 250 nm, particularly preferably from 50 nm to 200 nm, and / or - the nanostructures (31) each have a surface area in the range of 80 nm 2 up to 40000 nm 2 , preferably from 800 nm 2 up to 20,000 nm 2 , particularly preferably from 2000 nm 2 up to 10000 nm 2 , and / or - the areal density of the nanostructures (31) on the essentially strip-shaped elevations (29) is in the range from 1 to 10%, preferably from 2 to 6%. [5] Method according to one of the preceding claims, characterized bythat the at least one metallic layer (2c) is formed from stainless steel and / or at least one titanium alloy, for example from a stainless steel core with at least one surface made of a titanium alloy. [6] Method according to one of the preceding claims, characterized by , that - providing the at least one second surface region (28) with the at least one elastomeric sealing element (26) is carried out by a method selected from the group consisting of screen printing methods, roller printing methods, stencil printing methods, dispenser methods, and combinations thereof, and / or - the at least one elastomer is selected from the group consisting of fluororubbers, silicone rubbers, nitrile-butadiene rubbers, polyurethanes, natural rubber, perfluororubbers, styrene-butadiene rubbers, butyl rubbers, fluorosilicone rubbers, chlorosulfonated polyethylene, silicone resins, epoxy resins, hydrogenated nitrile-butadiene rubbers, ethylene-propylene-diene rubbers, olefin-based resins, polyisobutylenes, ethyl-2-cyanoacrylate, and mixtures thereof. [7] Method according to one of the preceding claims, characterized bythat the at least one apolar liquid coating material is at least one foamable material which additionally comprises expandable microspheres (33), wherein after the application of the at least one apolar liquid coating material to the at least one second surface region (28), the at least one elastomeric sealing element (26) is formed with expansion of the microspheres (33), wherein preferably the microspheres (33) - in the unexpanded state have an average diameter of at least 5 µm and / or at most 50 µm, and / or - have an average diameter of at least 20 µm and / or at most 150 µm in the expanded state. [8] Method according to one of the preceding claims, characterized by , that - the at least two first surface regions (27) and / or the at least one second surface region (28) run substantially parallel to a main direction of extension of the respective sealing bead (12a-g) and / or extend over the entire length of the respective sealing bead (12a-g), and / or - the at least two first surface regions (27) each have a width in the range from 90 µm to 460 µm, preferably from 95 µm to 300 µm, particularly preferably from 100 µm to 200 µm. [9] Method according to one of the preceding claims, characterized by that the at least one sealing bead (12a-g) has a bead roof (24) and a first and a second bead flank (25a, 25b) adjacent to the bead roof (24), wherein - at least one of the at least two first surface regions (27) is arranged on an edge of the first bead flank (25a) directly adjacent to the bead roof (24) and / or on the bead roof (24), preferably on an edge of the bead roof (24) directly adjacent to the first bead flank (25a), and at least one further of the at least two first surface regions (27) is arranged on an edge of the second bead flank (25b) directly adjacent to the bead roof (24) and / or on the bead roof (24), preferably on an edge of the bead roof (24) directly adjacent to the second bead flank (25b), and / or - the at least one second surface area (28) is arranged on the bead roof (24), wherein preferably • the at least one second surface area (28) is arranged exclusively on the bead roof (24), and / or • the at least one second surface area (2) extends over the entire width of the corrugated roof (24) or in sections over the width of the corrugated roof (24). [10] Method according to one of the preceding claims, characterized by that the at least one second surface region (28) is provided with a further surface structuring before step c), preferably before step b), which has a plurality of further depressions (32), wherein preferably the further depressions (32) - have a width and / or a diameter in the range from 10 µm to 150 µm, preferably from 20 µm to 100 µm, particularly preferably from 30 µm to 70 µm, and / or - have a depth of at least 2 µm and / or at most 40 µm and / or have a depth of at most 20% of the thickness of the metallic layer, and / or - by laser radiation, preferably by irradiation using a pulsed laser, or by microstructuring embossing. [11] Method according to one of the preceding claims, characterized by that the component for an electrochemical system (1) is a bipolar plate (2) for an electrochemical system (1), a separator plate (2d, 2e) for an electrochemical system (1) or a sealing frame (40) for an electrochemical system (1), preferably for an electrolyzer system. [12] A component for an electrochemical system (1), comprising at least one metallic layer (2c) with at least one sealing bead (12a-g) formed therein, wherein the at least one sealing bead (12a-g) has at least two first surface regions (27) and at least one second surface region (28) arranged between the at least two first surface regions (27) and directly adjacent to the at least two first surface regions (27), wherein the at least two first surface regions (27) have surface structures comprising periodic structures comprising alternatingly arranged substantially strip-shaped elevations (29) and depressions (30), as well as nanostructures (31) in the form of substantially punctiform elevations arranged at least on the substantially strip-shaped elevations (29),and wherein the at least one second surface region (28) is at least one surface region provided with at least one elastomeric sealing element (26). [13] Component according to claim 12, characterized by , that - the substantially strip-shaped elevations (29) have a width in the range from 250 nm to 700 nm, preferably from 350 nm to 600 nm, and / or the substantially strip-shaped depressions (30) have a width in the range from 100 nm to 550 nm, preferably from 200 nm to 450 nm, and / or - the nanostructures (31) have an average diameter in the range from 10 nm to 200 nm, preferably from 30 nm to 150 nm, particularly preferably from 50 nm to 120 nm, and / or - the nanostructures (31) have a maximum diameter in the range from 10 nm to 300 nm, preferably from 30 nm to 250 nm, particularly preferably from 50 nm to 200 nm, and / or - the nanostructures (31) each have a surface area in the range of 80 nm 2 up to 40000 nm 2 , preferably from 800 nm 2 up to 20,000 nm 2 , particularly preferably from 2000 nm 2 up to 10000 nm 2 , and / or - the areal density of the nanostructures (31) on the essentially strip-shaped elevations (29) is in the range from 1 to 10%, preferably from 2 to 6%. [14] Component according to claim 12 or 13, characterized by that the at least one metallic layer (2c) is formed from stainless steel and / or at least one titanium alloy, for example from a stainless steel core with at least one surface made of a titanium alloy. [15] Component according to one of claims 12 to 14, characterized by that the at least one elastomeric sealing element (26) - contains at least one elastomer selected from the group consisting of fluororubbers, silicone rubbers, nitrile-butadiene rubbers, polyurethanes, natural rubbers, perfluororubbers, styrene-butadiene rubbers, butyl rubbers, fluorosilicone rubbers, chlorosulfonated polyethylene, silicone resins, epoxy resins, hydrogenated nitrile-butadiene rubbers, ethylene-propylene-diene rubbers, olefin-based resins, polyisobutylenes, ethyl-2-cyanoacrylate, and mixtures thereof, and / or - contains or consists of at least one foamed material with microspheres (33), wherein preferably an average diameter of the microspheres (33) is at least 20 µm and / or at most 150 µm. [16] Component according to one of claims 12 to 15, characterized by , that - the at least two first surface regions (27) and / or the at least one second surface region (28) run substantially parallel to a main direction of extension of the respective sealing bead (12a-g) and / or extend over the entire length of the respective sealing bead (12a-g), and / or - the at least two first surface regions (27) each have a width in the range from 90 µm to 460 µm, preferably from 95 µm to 300 µm, particularly preferably from 100 µm to 200 µm. [17] Component according to one of claims 12 to 16, characterized by that the at least one sealing bead (12a-g) has a bead roof (24) and a first and a second bead flank (25a, 25b) adjacent to the bead roof (24), wherein - at least one of the at least two first surface areas (27) is arranged on an edge of the first bead flank (25a) directly adjacent to the bead roof (24) and / or on the bead roof (24), preferably on an edge of the bead roof (24) directly adjacent to the first bead flank (25a), and at least one further of the at least two first surface regions (28) is arranged on an edge of the second bead flank (25b) directly adjacent to the bead roof (24) and / or on the bead roof (24), preferably on an edge of the bead roof (24) directly adjacent to the second bead flank (25b), and / or - the at least one second surface area (28) is arranged on the bead roof (24), wherein preferably • the at least one second surface area (28) is arranged exclusively on the bead roof (24), and / or • the at least one second surface area (28) extends over the entire width of the corrugated roof (24) or in sections over the width of the corrugated roof (24). [18] Component according to one of claims 12 to 17, characterized by that the at least one second surface region (28) under the at least one elastomeric sealing element (26) has a further surface structuring with a plurality of further depressions (32), wherein preferably the further depressions (32) - have a width and / or a diameter in the range from 10 µm to 150 µm, preferably from 20 µm to 100 µm, particularly preferably from 30 µm to 70 µm, and / or - have a depth of at least 2 µm and / or at most 40 µm and / or have a depth of at most 20% of the thickness of the metallic layer, and / or - were produced by laser radiation, preferably by irradiation using a pulsed laser, or by microstructuring embossing. [19] Component according to one of claims 12 to 18, characterized by that the component is a bipolar plate (2) for an electrochemical system (1), a separator plate (2d, 2e) for an electrochemical system (1) or a sealing frame (40) for an electrochemical system (1), preferably for an electrolyzer system [20] Component according to one of claims 12 to 19, characterized by that the component can be produced or is produced by a method according to one of claims 1 to 11. [21] Electrochemical system (1) comprising at least one component according to one of claims 12 to 20.

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