Sealing arrangement, plate assembly, electrochemical system, and methods for manufacturing sealing arrangement.

Abstract

The present invention relates to a sealing arrangement (50) comprising: an elastomeric sealing element (52) comprising a foamed material containing microspheres (54); and a metal layer (60) having a surface structure (62) including a plurality of recesses (64), wherein the sealing element (52) is configured as a coating of the metal layer (60) and is arranged at least in some regions on the surface structure (62), wherein the concentration of microspheres (54) measured perpendicular to the surface (61) of the metal layer (60) is non-uniform. The invention also relates to a plate assembly (70), an electrochemical system (1), and a method of producing the sealing arrangement (50).

Description

Technical Field

[0001] This invention relates to a sealing arrangement comprising an elastomeric sealing element and a metal layer. The invention also relates to a plate assembly for an electrochemical system, and an electrochemical system incorporating such a sealing arrangement. Furthermore, the invention relates to a method for manufacturing the sealing arrangement. Background Technology

[0002] Known electrochemical systems include, for example, fuel cell cell systems or electrochemical compressor systems, particularly electrolyzers. Electrolyzers are known to be constructed in such a way that hydrogen and oxygen are produced from water by applying an electric potential, and these gases are simultaneously compressed under pressure. Electrochemical compressor systems are also known, such as electrochemical hydrogen compressors, to which gaseous molecular hydrogen is supplied, and the latter is electrochemically compressed therein by applying an electric potential. This electrochemical compression is particularly suitable for compressing small amounts of hydrogen, as mechanical compression of hydrogen is much more laborious.

[0003] Electrochemical systems are also known to include stacked electrochemical cells, each cell separated from each other by bipolar plates. Such bipolar plates can be used, for example, to indirectly electrically contact the electrodes of a single electrochemical cell (e.g., a fuel cell cell) and / or indirectly electrically connect adjacent cells (cells in series). The bipolar plates can also have or be configured to form channel structures for supplying one or more media and / or removing reaction products from the cell. The media can be fuels (e.g., hydrogen or methanol), reaction gases (e.g., air or oxygen), or coolants. Such channel structures are typically arranged in electrochemical active regions (flow fields) and in distribution and collection regions leading to and away from the latter. Furthermore, the bipolar plates can be configured to transfer waste heat generated when electrical and / or chemical energy is converted in the electrochemical cell, and also to seal various media channels, including cooling channels, relative to each other and / or relative to the outside. For example, the bipolar plates can have openings through which the media and / or reaction products to be supplied can be directed toward or away from the electrochemical cells arranged between adjacent bipolar plates in the stack.

[0004] Electrochemical cell units may, for example, each include one or more membrane electrode assemblies (MEAs). MEAs may have one or more conductive gas diffusion layers, which are typically oriented toward the bipolar plates and constructed, for example, as conductive fiber fibers, particularly metal fiber fibers or carbon fiber fibers. The membrane electrode assemblies typically have a frame-like seal at their outer edges, said seal being particularly formed of a polymer-based material, preferably a polymer-based thin film.

[0005] The sealing between the bipolar plate and the membrane electrode assembly typically occurs outside the electrochemically active region and usually includes both at least one port seal and an external seal. The bipolar plate typically consists of two septa, each adjacent to the membrane electrode assembly. The septa may have seals for sealing the membrane electrode assembly, particularly frame-like seals; if the septa are constructed as metal plates, such as those made of stainless steel, the seals may be integrally formed into a sealing bead, for example, within the septa by convex forming, deep drawing, or hydroforming. To improve micro-sealing, such a sealing bead typically has a polymer-based sealing coating on at least one side.

[0006] In some applications, the sealing arrangement must function equally reliably across a temperature range between a minimum (e.g., -40°C) and a maximum (e.g., +100°C). This temperature variation, particularly during winter when the fuel cell system is initially running at ambient temperature or during cold starts, can occur from below zero to the stack's maximum operating temperature. As already described, the frame-like sealing element of the membrane electrode assembly is typically made of a polymer-based material, and the separators of the bipolar plates are preferably made of a metallic material. These materials have different coefficients of thermal expansion. Especially during rapid cold starts, the separators and the membrane electrode assembly can expand differently, and the frame-like sealing element can shift relative to the sealing flange. This can lead to coating detachment from the sealing flange. Typically, the sealing coating on the frame-like sealing element does not slip off; rather, the polymer-based sealing coating adheres at least temporarily to the polymer-based frame-like sealing element. The effects of coating detachment and adhesion become particularly noticeable when the stack is disassembled, and the coating may be pulled off due to previous detachment from the bipolar plates.

[0007] To further improve micro-seals, metal seal flanges typically have an elastomeric coating containing microspheres, at least in the region surrounding the flange with the through opening. This coating has a generally regular distribution of microspheres in its coating quality, such that the bonding between the elastomer and the metal surface is not present on the entire surface of the coating facing the metal. Therefore, this microsphere-containing elastomeric coating may be particularly prone to separation over time, potentially leading to leaks in the corresponding system. It is desirable to improve the adhesion of these coatings. Summary of the Invention

[0008] The object of this invention is to provide a sealing arrangement, plate assembly, and electrochemical system that at least partially solves the aforementioned problems. Furthermore, it is advantageous to develop a method for generating the sealing arrangement.

[0009] This objective is achieved by the sealing arrangement, plate assembly, and electrochemical system described in the independent claims, as well as the method for manufacturing the sealing arrangement. Further developments form the subject matter of the dependent claims and the subject matter described below.

[0010] According to one aspect of the present invention, a sealing arrangement is provided. The sealing arrangement includes:

[0011] --An elastomeric sealing element comprising a foamed material containing microspheres, and

[0012] --A metal layer having a surface structure including multiple recesses.

[0013] The sealing element is configured as a coating of a metal layer and is arranged at least in some areas of the surface structure. The concentration of microspheres in the sealing element, measured perpendicular to the surface of the metal layer, is non-uniform. Due to the non-uniform concentration of microspheres, the adhesion of the sealing element to the metal layer can be improved.

[0014] This uneven concentration should be understood in particular as meaning that not only are the sizes of the microspheres different, but the volume content of the gas in the polymer matrix is ​​also different. In other words, the sum of the volumes of the microspheres is relative to the volume of the coating composed of the polymer matrix and the microspheres.

[0015] The sealing element can be configured to have a first junction adjacent to the metal layer, and the concentration of microspheres in the sealing element is lower within the first junction than outside the first junction. Specifically, given suitable temperature control for the coating, crosslinking, and / or expansion processes, the sealing element can have a second junction away from the metal layer, wherein the concentration of microspheres in the sealing element is lower within the first and second junctions than outside the first and second junctions. The first junction and optionally the second junction described herein can each have a thickness, either individually or together, that does not exceed 35%, preferably not more than 30%, and particularly preferably not more than 23%, relative to the total maximum layer thickness of the sealing element measured perpendicular to the surface of the metal layer. If only the first junction has a lower concentration of microspheres, its proportion of the maximum layer thickness of the sealing element will also be at most 18%.

[0016] Conversely, the concentration of the polymer-based coating material, i.e., the polymer matrix minus the microspheres, is preferably also non-uniform. In particular, the weight content of the polymer matrix can be greater in the first junction and optionally in the second junction than outside the first junction and optionally in the second junction. This can be checked, for example, by measurements using terahertz radiation or computed tomography.

[0017] One possible explanation for the improved adhesion is that the surface of the metal layer with surface structures is generally rougher than the untreated surface. Compared to an elastomeric substrate, microspheres may have a lower affinity for rough surfaces, thus allowing the elastomeric substrate to adhere better to the metal layer in the surface-structured regions compared to a smooth, unstructured metal layer. In general, the surface structure can lead to an increase in the elastomeric content and / or polymer matrix content at the interface with the metal layer. Due to the lower concentration of microspheres at the interface, the adhesion of the seal to the metal layer can be improved in this region. This significantly improved adhesion of the sealing element to the metal layer has been demonstrated in various tests comparing the sealing arrangement proposed in this application with a similar sealing arrangement without surface structures. For this purpose, the sealing arrangements to be compared were sprayed with an organic solvent and then mechanically pressurized. In these tests, it was found that the sealing arrangement according to the invention exhibits adhesion up to 10 times higher.

[0018] The sealing arrangement may have an elastically deformable protrusion integrally formed in the metal layer, sometimes also referred to as a sealing protrusion. The surface structure may be formed on only one or both surfaces of the protrusion. The sealing element is preferably arranged in at least some regions of the protrusion. The protrusion may have, for example, a protrusion top and at least one protrusion flank adjacent to the protrusion top, or only a curved protrusion top without a prominent protrusion flank. The surface structure may extend in at least some regions on the protrusion top and / or at least one protrusion flank. However, the surface structure may also extend laterally beyond the region of the protrusion flank. The surface structure may be configured to cover the surface of the protrusion at least on at least one side of the metal layer, in at least some regions, or completely. The protrusion is preferably configured to have a surface structure in at least some regions or completely on at least the side of the metal layer facing the component to be sealed, i.e., particularly the sealing edge region of the membrane electrode assembly. Therefore, the surface structure and the sealing element are preferably formed on the convex, outwardly curved surface of the protrusion. The convex edge typically has a transverse direction, extending from one convex edge flank to the top of the convex edge and / or to an optional second convex edge flank, or along the curvature of the top of the curved convex edge. The longitudinal direction of the convex edge typically corresponds to its direction of extension, that is, for example, around a port in a partition.

[0019] In this sealing arrangement, the average diameter of the microspheres can be at least 20 μm, particularly at least 30 μm, and / or at most 80 μm, particularly at most 60 μm. The microspheres are typically filled with a gaseous medium, particularly an expanding agent, preferably a gaseous hydrocarbon, particularly a saturated hydrocarbon, such as n-pentane, isopentane, or isobutane. The gaseous medium is typically enclosed within the microspheres. The compressible gaseous medium within the microspheres can increase the elasticity of the sealing element and thus improve its sealing performance.

[0020] In some embodiments, the average diameter of the microspheres is greater than the width of the depression. In some embodiments, the average diameter of the microspheres is smaller than the width of the depression. In this case, further mechanisms for better adhesion can be proposed. Because the average diameter of the microspheres is greater than the lateral extent of the depression, the microspheres cannot accumulate or can only accumulate partially in the junction region. Therefore, in general, the concentration of microspheres is lower in the junction than outside the junction.

[0021] The total layer thickness of the sealing element in this sealing arrangement can be, for example, up to 500 μm, preferably up to 300 μm, more preferably up to 200 μm, and particularly up to 150 μm. In some embodiments, the metal layer is configured to have a sealing element constructed as a coating on its entire surface or in part. Various elastomers are considered for elastomeric sealing elements. For example, the sealing element comprises: FPM (fluororubber), silicone rubber or NBR rubber (nitrile rubber), PUR (polyurethane), NR (natural rubber), FFKM (perfluororubber), SBR (styrene-butadiene rubber), BR (butyl rubber), FVSQ (fluorosilicone rubber), CSM (chlorosulfonated polyethylene), silicone resin, epoxy resin, or mixtures of the above substances, or pressure-sensitive adhesives and / or physical adhesives. The sealing element may also comprise layers, each layer comprising one or more of the aforementioned materials.

[0022] The width and / or diameter of the recess, particularly when measured at the midpoint of the recess and / or parallel to the untreated and / or unstructured metal surface, is at most 150 μm, preferably at most 100 μm, and particularly at most 70 μm. The recess can be measured from the untreated surface to the lowest point of the recess, with a depth of at least 2 μm and / or at most 40 μm. The depth of the recess may not exceed 20% of the metal layer thickness. This ensures that the metal layer does not experience material weakening during operation that could lead to leakage or breakage in the material.

[0023] To achieve a sufficient surface treatment effect, the maximum spacing between adjacent recesses should be at most five times the diameter of the recess. On the other hand, the recesses should not be arranged too close to each other, as this may lead to material damage. Adjacent recesses preferably have a minimum spacing corresponding to half the diameter of the recess. The spacing between adjacent recesses may differ in the longitudinal and transverse directions of the seal. In the transverse direction, this minimum spacing should correspond to at least half the diameter. Furthermore, in the transverse direction, this minimum spacing may correspond to at most three times the diameter. In the longitudinal direction, this minimum spacing may correspond to at least the diameter of the recess. In the longitudinal direction, the maximum spacing should be five times the diameter. If such a sealing element is combined with a sealing flange, the longitudinal and transverse directions of the sealing element correspond to the longitudinal and transverse directions of the sealing flange, respectively.

[0024] The circumferential edge of the recess can be, for example, substantially circular, elliptical, or oval. The shape of the circumferential edge can depend on the corresponding location of the recess in the metal layer. For example, the circumferential edge of a recess disposed on the top of a convex edge can be different from the circumferential edge of a recess disposed on at least one flank of a convex edge (see below).

[0025] The recess is preferably created by means of laser radiation. In other embodiments, the recess is created mechanically, for example by engraving or scribing the metal layer. The recess may be at least partially surrounded by a protrusion. The protrusion may be formed at the corresponding circumferential edge of the recess. The corresponding protrusion may protrude above the untreated surface of the metal layer. The protrusion may, for example, be configured as a crater edge. This crater edge is typically formed when the recess is formed, for example, by laser radiation, through the solidification of molten material. Therefore, the crater edge or protrusion may be formed from material migrating from the recess.

[0026] The metal layer may have further convex structures, which are produced, for example, by deep drawing, convex forming, and / or hydroforming. In addition to the sealing convex edges already described above, these further convex structures may include structures for guiding the medium along the metal layer, such as flow field and / or channel structures. The sealing element may, for example, surround the convex structure in an essentially closed manner. The sealing arrangement may have, for example, an outer peripheral convex edge extending around the flow field and sealing the latter relative to the surrounding area of ​​the metal layer, i.e., a sealing convex edge, and at least partially have the aforementioned surface structures and be covered by an elastomeric sealing element.

[0027] In some embodiments, the sealing arrangement may surround at least one through-opening for gas or liquid formed in the metal layer in a substantially closed manner. In some embodiments, the flange surrounds the through-opening in a substantially closed manner. For example, the sealing arrangement may have a port flange for sealing the through-opening of the medium, i.e., a sealing flange.

[0028] Metal layers are typically constructed as part of a separator or bipolar plate in electrochemical systems.

[0029] According to another aspect of the invention, a plate assembly for an electrochemical system is provided. This includes a sealing arrangement having an elastomeric sealing element comprising a foamed material containing microspheres. The system also includes two separators configured as metal layers, similar to the metal layers described above, having surface structures in at least certain regions. As in the sealing arrangement described above, the surface structures include a plurality of recesses. The plate assembly also includes a membrane electrode assembly disposed between the separators. The sealing element is configured as a coating on at least one side of each separator, particularly precisely on one side, and disposed in at least certain regions of the surface structure. The sealing arrangement is preferably disposed on the surface of the separator facing the membrane electrode assembly. As in the sealing arrangement described above, the concentration of microspheres in the sealing element, measured perpendicular to the surface of the metal layer, is non-uniform.

[0030] Each plate assembly preferably comprises exactly two separators, each separator being separated from the other by a membrane electrode assembly. Each separator may be part of a bipolar plate, which typically comprises two abutting separators. Thus, a bipolar plate preferably belongs to two different plate assemblies.

[0031] According to another aspect of the invention, an electrochemical system is provided. This electrochemical system includes, for example, a plurality of plate assemblies of the type described above. Alternatively or additionally, the electrochemical system includes a plurality of sealing arrangements of the type described above.

[0032] Stacks of electrochemical systems, including bipolar plates and electrochemical cells, are typically terminated by end plates at each end of the stack. At least one end plate typically has one or more ports. Lines for supplying a medium and / or removing reaction products can be connected to said ports. Furthermore, at least one end plate typically has an electrical connection, through which the stack of cell cells can be electrically connected to a power-consuming device or voltage source. Correspondingly, the electrochemical system may have end plates.

[0033] The present invention also provides a method for producing a sealing arrangement, particularly a sealing arrangement of the type described above. The method includes at least the following steps:

[0034] - Provide a metal layer,

[0035] - Provide a metal layer with a surface structure, the surface structure including multiple recesses.

[0036] - Apply a foamable material containing expandable microspheres to the surface structure.

[0037] - An elastic sealing element is formed on a metal layer by expanding microspheres, wherein the distribution of the expanded microspheres in the sealing element 52, measured perpendicular to the surface of the metal layer, is non-uniform.

[0038] To reiterate, this non-uniform concentration should be understood in particular as meaning that not only are the sizes of the microspheres different, but the volume content of the gas in the polymer matrix is ​​also different; that is, the sum of the volumes of the microspheres is relative to the volume of the coating composed of the polymer matrix and the microspheres. Conversely, the concentration of the polymer-based coating material, i.e., the polymer matrix minus the microspheres, is preferably also non-uniform.

[0039] The microspheres in their unexpanded state may have an average diameter of at least 5 μm and / or at most 50 μm. Furthermore, the microspheres in their expanded state may have an average diameter of at least 20 μm and / or at most 80 μm. This value can depend on, for example, the crosslinking rate and / or degree of crosslinking of the elastomer. The faster the elastomer crosslinks, the lower the degree of expansion of the microspheres.

[0040] By expanding the microspheres, the maximum thickness of the sealing element, which is applied as a layer, is typically expanded to several times. For example, the maximum layer thickness of the finished sealing element is at least two times, preferably at least three times, and particularly at least four times, the layer thickness of the foamable material.

[0041] In a preferred variation, the surface depressions are created by laser radiation. Specifically, pulsed lasers can be used for this purpose. The depressions are subsequently formed by the melting of the material in the metal layer. Due to the heat generated by the laser irradiation, very fine particles of metal or metal compounds detach from the surface and evaporate. In the depressed region, it appears that the physical changes in the surface structure occur at least partially in the material of the metal layer (e.g., electronic and / or geometrical changes). In some cases, chemical changes also occur in the material of the metal layer (e.g., changes in chemical composition). For example, if the metal layer is made of stainless steel, the chromium / iron ratio or oxygen content may differ in the depressed region (i.e., in the depressed surface) and / or in the region immediately adjacent to the depressed surface (i.e., particularly in the region near the edge of the crater) compared to the untreated, unstructured surface. Surface treatment by means of laser radiation is advantageously carried out in such a way that the mechanical properties of the metal layer material are not damaged and the metal layer is not undesirably weakened.

[0042] In an alternative variation of this method, the depression is mechanically created, for example, by engraving to produce a microstructure. In this case, the depression can also be formed by scribing the metal layer.

[0043] In another alternative method step, the sealing flange is integrally formed in at least one metal layer, particularly by embossing, deep drawing, and / or hydraulic methods. This can occur before, simultaneously with, or after the surface construction. In particular, if the surface construction is formed by engraving, the embossing of the sealing flange can be performed simultaneously. If the surface construction produces a microstructure by engraving or by laser irradiation, the sealing flange is preferably pre-formed integrally.

[0044] Foamable materials can be applied by spraying, electroplating, screen printing, roller printing, stencil printing or metering processes.

[0045] The surface texture and the application of the foamable material preferably occur on the convex surface that only seals the raised edge.

[0046] This method is particularly suitable for the production of the aforementioned sealing arrangements, plate assemblies, and / or electrochemical systems. Therefore, the features described in connection with the sealing arrangements, plate assemblies, and / or electrochemical systems can be combined with or claimed in connection with this method, and vice versa. Attached Figure Description

[0047] The accompanying drawings illustrate exemplary embodiments of the sealing arrangement, plate assembly, electrochemical system, and production method, which will be explained in more detail based on the description below. In the drawings:

[0048] Figure 1 An electrochemical system is schematically illustrated in a three-dimensional view, comprising a plurality of separators or bipolar plates arranged in a stacked manner;

[0049] Figure 2 A three-dimensional diagram schematically illustrates the following based on Figure 1 The system has two bipolar plates, with a membrane electrode assembly (MEA) arranged between the bipolar plates;

[0050] Figure 3 The illustration shows crossing with Figure 1 Cross-section of a stack of plates of the same type as the system shown;

[0051] Figure 4 The illustration shows crossing with Figure 1 Another cross-section of a stack of plates of the same type as the system shown;

[0052] Figure 5 A cross-section through a sealing arrangement according to the prior art is shown;

[0053] Figure 6 A cross-section through a sealing arrangement according to one embodiment is shown;

[0054] Figure 7 A cross-section through a sealing arrangement according to one embodiment is shown;

[0055] Figure 8 A cross-section through a sealing arrangement according to one embodiment is shown;

[0056] Figure 9 A cross-section through a sealing arrangement according to one embodiment is shown;

[0057] Figure 10A cross-section through a convex edge according to the prior art is shown;

[0058] Figure 11 A cross-section through a convex edge according to one embodiment is shown;

[0059] Figure 12 A cross-section through a convex edge according to one embodiment is shown;

[0060] Figure 13 A cross-section through a convex edge according to one embodiment is shown;

[0061] Figure 14 A cross-section through a convex edge according to one embodiment is shown;

[0062] Figure 15 A cross-section through a convex edge according to one embodiment is shown;

[0063] Figure 16 A cross-section through a convex edge according to one embodiment is shown;

[0064] Figure 17 A cross-section through a convex edge according to one embodiment is shown;

[0065] Figure 18 A cross-section through a convex edge according to one embodiment is shown;

[0066] Figure 19 A flowchart of a method for generating a sealing arrangement according to the present invention is shown; and

[0067] Figure 20 A microscope image of a metal layer with a surface structure is shown for use in sealing arrangements.

[0068] Features that appear repeatedly in different figures are indicated by the same or similar reference numerals in each case, both herein and hereinafter. Detailed Implementation

[0069] This invention relates to a sealing arrangement. Specifically, this sealing arrangement can be used in an electrochemical system 1 (see...). Figures 1-4 ).

[0070] Figure 1An electrochemical system 1 is shown comprising multiple structurally identical metal bipolar plates 2 arranged in a stack 6 and stacked along a z-direction 7. The bipolar plates 2 of the stack 6 are sandwiched between two end plates 3, 4. The z-direction 7 is also referred to as the stacking direction. In this example, system 1 is a fuel cell stack. Therefore, each pair of adjacent bipolar plates 2, or the mutually facing separators X of each of these bipolar plates 2, forms an electrochemical cell, which, for example, is used to convert chemical energy into electrical energy. To form the electrochemical cell unit of system 1, a membrane electrode assembly (MEA) is arranged between each of the adjacent bipolar plates 2 in each case (see, for example, [reference needed]). Figure 2 These MEAs typically contain at least one membrane, such as an electrolyte membrane. Additionally, a gas diffusion layer (GDL) may be disposed on one or both surfaces of the MEA.

[0071] 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. Thus, the structure of these bipolar plates can correspond to the structure of bipolar plate 2 described in detail herein, but in each case of an electrolyzer, electrochemical compressor, or redox flow battery, the medium conducted to and / or through the bipolar plates can differ from the medium used in a fuel cell cell system.

[0072] The z-axis 7, x-axis 8, and y-axis 9 form a right-handed Cartesian coordinate system. Each bipolar plate 2 defines a plate plane, and each plate plane of the septa 2a, 2b of the bipolar plate 2 is positioned parallel to the xy plane and therefore perpendicular to the stacking direction or z-axis 7. The end plate 4 has multiple medium ports 5 through which medium can be supplied to and discharged from the system 1. The medium that can be supplied to and discharged from the system 1 may 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 fuel, or coolants such as water and / or ethylene glycol.

[0073] Figure 2 Shown in 3D Figure 1 A perspective view of two adjacent bipolar plates 2 of an electrochemical system of type 1, and a prior art known membrane electrode assembly (MEA) 10 arranged between the adjacent bipolar plates 2. Figure 2 MEA10 is largely obscured by bipolar plate 2 facing the observer. Bipolar plate 2 is formed by materials bonded together (e.g., see...). Figure 3 The two partitions 2a and 2b are formed in ) Figure 2Only the first partition 2a facing the observer is visible, and the first partition obscures the second partition 2b. Partitions 2a and 2b can each be made of sheet metal, such as stainless steel. For example, partitions 2a and 2b can be welded together, for example, by laser welding.

[0074] Partitions 2a and 2b have through openings that are aligned with each other and form through openings 11a-11c of bipolar plate 2. When multiple bipolar plates of the same type as bipolar plate 2 are stacked, the through openings 11a-11c form conduits extending along the stacking direction 7 through the stack 6 (see...). Figure 1 Typically, each line formed by the through openings 11a-11c is fluidly connected to one of the ports 5 in the end plate 4 of system 1. For example, coolant can be introduced into or discharged from the stack via the line formed by through opening 11a. Conversely, the lines formed by through openings 11b, 11c can be configured to supply fuel and reaction gases to the electrochemical cells of the fuel cell stack 6 of system 1 and to discharge reaction products from the stack. The medium-guided through openings 11a-11c are substantially parallel to the plate plane.

[0075] To seal the through openings 11a-11c relative to the interior of the stack 6 and relative to the surrounding environment, the first partition 2a typically has a sealing arrangement in the form of sealing flanges 12a-12c, which are respectively arranged around the through openings 11a-11c and, in each case, completely surround the through openings 11a-11c. On the back side of the bipolar plate 2... Figure 2 On the rear side of the observer, the second partition 2b has corresponding sealing convex edges for sealing the through openings 11a-11c (not shown).

[0076] In the electrochemically active region 18, the first separator 2a faces its orientation. Figure 2 A flow field 17 is present on the front side of the observer, the flow field 17 having a structure for guiding the reaction medium along the front side of the partition 2a. Figure 2 In this structure, these structures are defined by multiple webs and channels extending between and defined by these webs. In the bipolar plate 2 facing... Figure 2 On the observer's front side, the first partition 2a further has a dispensing or collecting region 20. This dispensing or collecting region 20 includes structures configured to dispense and / or collect or aggregate media on the active region 18, the dispensed media being media already introduced into the dispensing or collecting region 20 from the first of two through openings 11b, and the collected or aggregated media being media flowing from the active region 18 to the second through opening 11b. Figure 2In this context, the distribution structure of the distribution or collection area 20 is also defined by the web and the channels extending between the webs and defined by the web. Therefore, in general, elements 17, 18, and 20 can be understood as convex structures guiding the medium.

[0077] The sealing flanges 12a-12c typically have passages 13a-13c, which are at least partially manifested as local protrusions of the flanges. Passage 13a is formed on both the lower side of the upper partition 2a and the upper side of the lower partition 2b, while passage 13b is formed in the upper partition 2a and passage 13c is formed in the lower partition 2b. For example, passage 13a allows coolant to pass between the through opening 12a and the distribution area, allowing the coolant to reach the distribution area between the partitions and be guided out therefrom. Furthermore, passage 13b allows hydrogen to pass between the through opening 12b and the distribution area on the upper side of the upper partition 2a; these passages 13b are characterized by perforations facing the distribution area and extending at an angle to the plate plane. Thus, hydrogen can flow, for example, from the through opening 12c through the passage 13b to the distribution area on the upper side of the upper partition 2a, or flow in the opposite direction. The passage 13c allows air to pass between, for example, the through opening 12c and the distribution area, so that the air reaches the distribution area on the underside of the lower partition 2b and is guided out therefrom. The associated perforations are not visible here.

[0078] The first baffle 2a typically also has an additional sealing arrangement in the form of a peripheral protrusion 12d, which extends around the flow field 17 of the active region 18, the distribution or collection region 20, and the through openings 11b, 11c, and seals these with respect to the through openings 11a, i.e., with respect to the coolant circuit and with respect to the surrounding environment of the system 1. The second baffle 2b each includes a corresponding peripheral protrusion. The structure of the active region 18, the distribution structure of the distribution or collection region 20, and the protrusions 12a-12d are each formed integrally with the baffle 2a, and are integrally formed in the baffle 2a, for example, by a embossing process or deep drawing process and / or by means of hydroforming. The same applies to the corresponding distribution structure and sealing protrusion of the second baffle 2b. Outside the area surrounded by the peripheral protrusion 12d, a predominantly unstructured outer edge region 22 is formed in each baffle 2a, 2b.

[0079] The two through openings 11b or the conduits formed by the through openings 11b passing through the plate stack of system 1 each pass through the passage 13b in the sealing flange 12b, through the distribution structure of the distribution or collection area 20, and through the direction towards Figure 2The flow field 17 in the active region 18 of the first partition 2a is fluidly connected to each other. Similarly, the two through openings 11c or the pipelines formed by the through openings 11c through the plate stack of the system 1 are respectively connected via corresponding convex edge passages, via corresponding distribution structures, and via the back-to-back Figure 2 The observers are fluidly connected to each other by the corresponding flow fields on the exterior of the second partition 2b. Conversely, the through-opening 11a or the tubing formed by the through-opening 11a that passes through the plate stack of system 1 is fluidly connected to each other via cavities 19 enclosed or surrounded by partitions 2a, 2b. In each case, the cavity 19 is used to guide coolant through the bipolar plates 2, and in particular to cool the electrochemically active regions 18 of the bipolar plates 2.

[0080] Figure 3 Schematic illustration of crossing Figure 1 A portion of the cross-section of the plate stack 6 of system 1 has a cross-sectional plane oriented along the z-direction and therefore perpendicular to the plate plane of bipolar plate 2; it can, for example, be along... Figure 2 The kinked section AA extends in the middle.

[0081] The stacked bipolar plates 2, each with the same structure, each include the first metal separator 2a and the second metal separator 2b described above. The thickness of each metal separator 2a, 2b is approximately 75 μm. The structure guiding the medium along the outer surface of the bipolar plate 2 can be seen, particularly in the form of a web and channels separated by the web. Specifically shown are channels 29 facing away from each other on the surfaces of adjacent separators 2a, 2b, and cooling channels 19 between adjacent separators 2a, 2b. Between the cooling channels 19, the two separators 2a, 2b abut against each other in a contact area 24 and are connected at this point; in this example, they are connected by means of a laser weld.

[0082] A membrane electrode assembly (MEA) 10, as known from the prior art, is arranged between stacked adjacent bipolar plates 2 in each case. The MEA 10 typically includes a membrane 14 (e.g., an electrolyte membrane) and a sealed edge region 15 connected to the membrane. For example, the sealed edge region may be substantially connected to the membrane, for example, by adhesive bonding or by lamination.

[0083] In each case, the membrane of MEA 10 extends at least over the active region 18 of the adjacent bipolar plate 2, and at this location, proton transfer is possible via or through the membrane. The membrane does not extend into the dispensing or collection region 20. The sealing edge region 15 of MEA 10 is used in each case to position, secure, and seal the membrane between the adjacent bipolar plates 2. If the bipolar plates 2 of system 1 are clamped between end plates 3 and 4 along the stacking direction (see...) Figure 1In this way, the sealing edge region 15 of MEA 10 can be compressed between the port protrusions 12a-12c of the respective adjacent bipolar plates 2 and / or between the outer peripheral protrusions 12d of the adjacent bipolar plates 2, so as to fix and seal MEA 10 between adjacent bipolar plates 2.

[0084] In each case, the sealing edge region 15 covers the dispensing or collecting region 20 of the adjacent bipolar plate 2. This edge portion 15 may also extend outward beyond the outer peripheral flange 12d and may adjoin the outer edge region 22 of the partitions 2a, 2b (see...). Figure 2 ).

[0085] A gas diffusion layer 16 may be additionally disposed in the active region 18. The gas diffusion layer 16 enables fluid flow to cross the membrane 14 over the maximum possible area of ​​the membrane 14 surface, and thus improves proton transfer via the membrane 14. The gas diffusion layer 16 may, for example, be disposed on both sides of the membrane 14 in the active region 18 between adjacent partitions 2. The gas diffusion layer 16 may be formed of, for example, a conductive nonwoven fabric or may include a conductive nonwoven fabric. Specifically, the conductive nonwoven fabric is metal fiber flocking or carbon fiber flocking.

[0086] Figure 4 Schematic illustration of crossing Figure 1 Another cross-section of a portion of the plate stack 6 of system 1. Here, the selected cross-section extends through two adjacent bipolar plates 2. Due to space constraints, this cross-section is shown as being broken towards the two outer sides of the protrusion 12b, which extends around the through opening 11b. In the region of the outer peripheral protrusion 12b, sealing arrangements 50', 50”, 50”', 50”” according to the invention are arranged between each bipolar plate 2 and the sealing edge region 15 of the membrane electrode assembly 10, each of these sealing arrangements comprising sealing elements 52', 52”, 52”', 52””, which will be described in more detail below.

[0087] The first sealing arrangement 50' includes a partition 2b configured as a metal layer 60, which has a surface structure 62' of the type described above above above its convex edge top 68 (i.e., its convex side). An elastomeric sealing element 52' containing microspheres 54 is disposed on the surface structure 62'. The second sealing arrangement 50" includes a partition 2a configured as a metal layer 60, which similarly has a surface structure 62" above its convex edge top. Another elastomeric sealing element 52" containing microspheres 54 is disposed on the surface structure 62". The sealing elements 52' and 52" may be made of the same elastomeric material or different elastomeric materials. The first sealing arrangement 50' faces the second sealing arrangement 50". On its recessed side, the sealing arrangements 50' and 50" are each formed without a surface structure and without an elastic coating. The first sealing arrangement 50' and the second sealing arrangement 50" abut against both sides of the sealing edge region 15 of the membrane electrode assembly; they seal around the port convex edge 12b. On one hand, the metal layers 60 of the partitions 2a and 2b and the sealing edge region 15 formed of polymer-based material have different coefficients of thermal expansion. Especially in the case of rapid cold start, the partitions 2a and 2b and the sealing edge region 15 can expand differently, and the frame-like sealing element can shift relative to the sealing convex edge. Due to the high microsphere content in the individual elastomeric sealing elements 52' and 52'", the latter can at least partially follow the shift. Furthermore, the surface structures 62 and 62' of the metal layer 60 in the first junction 57 of the elastomeric sealing elements 52' and 52' have a lower concentration of microspheres (see...). Figures 6-9 This ensures better adhesion between the elastomeric sealing elements 52', 52” and the corresponding partitions 2a, 2b.

[0088] Figure 3 and Figure 4 Both examples show that in each case only one septum 2b and one septum 2a belong to the plate assembly 70 according to the invention. In both examples, the septum 2b arranged on the upper side of the membrane electrode assembly 10 and the septum 2a arranged on the lower side of the membrane electrode assembly 10 belong to the plate assembly 70 explicitly marked with reference numerals. The septum 2a of the bipolar plate 2 arranged on the upper side of the membrane electrode assembly 10 already belongs to the next plate assembly.

[0089] As described above, the electrochemical system 1 includes a sealing arrangement 50, which will be described in more detail below.

[0090] Figure 5 A cross-section of a sealing arrangement 50 according to the prior art is shown, which includes an elastomeric sealing element 52 and a metal layer 60. The elastomeric sealing element 52 is configured as a coating of the metal layer 60 and includes a foaming material containing microspheres 54. Here, the concentration of microspheres 54 in the sealing element 52 is substantially uniform, and this concentration is measured perpendicular to the surface 61 of the metal layer 60. Although Figures 5-9The microspheres 54 are shown in an ideal form because they are spherical in every case and specifically have elements of equal size, but this does not mean that they are all the same size. Therefore, a uniform distribution (allocation) of the concentration of the microspheres 54 should be understood as meaning that the gas volume content remains substantially unchanged along a sufficiently long portion of the sealing arrangement 50 (e.g., along a portion corresponding to at least ten times the width of the sealing arrangement 50) in a direction perpendicular to the surface 61 of the metal layer 60. The volume or weight content of the polymer matrix similarly remains constant in the same direction within this portion of the sealing arrangement 50.

[0091] It has been discovered that Figure 5 The sealing arrangement 50 shown cannot always withstand the desired level of mechanical and / or thermal stress that occurs during operation of the electrochemical system 1. The adhesion of the sealing element 52 to the metal layer 60 may sometimes be insufficient because the elastomeric sealing element 52 may detach from the metal layer 60.

[0092] After conducting various tests, the inventors of this invention discovered that if the metal layer 60 has a surface structure 62, the adhesion between the elastomeric sealing element 52 and the metal layer 60 can be significantly improved.

[0093] Figures 6-9 A cross-section of a sealing arrangement 50 according to the invention is shown, wherein its metal layer 60 has the surface structure 62. For example... Figure 5 The sealing arrangement is the same as in case 50. Figures 6-9 The sealing arrangements 50 shown each include an elastomeric sealing element 52 and a metal layer 60. The elastomeric sealing element 52 is configured as a coating of the surface structure 61 of the metal layer 60 and includes a foaming material comprising microspheres 54.

[0094] However, with Figure 5Conversely, the metal layer 60 has a surface 61 with a surface structure 62. The surface structure 62 of the metal layer 60 includes a plurality of recesses 64. A sealing element 52 is disposed in at least some regions of the surface structure 62. It has been found that the concentration of microspheres 54, i.e., the volume content of the gas, measured perpendicularly to the surface 61 of the metal layer 60, is non-uniform in the sealing element 52. The sealing element 52 may particularly have a first junction 57 adjacent to the metal layer 60, wherein the concentration of microspheres 54, i.e., the volume content of the gas, in the sealing element 52 is lower within the first junction 57 than outside the first junction 57. Conversely, the weight content of the polymer matrix is ​​higher within the first junction 57 than outside the first junction 57. The first junction 57 has a thickness relative to the total maximum layer thickness of the sealing element 52 measured perpendicularly to the surface 61 of the metal layer 60, for example, may be up to 35%, preferably up to 30%, preferably up to 23%, particularly preferably up to 18%. Furthermore, the sealing element 52 may also have a second junction 59 located away from the metal layer 60, wherein the concentration of microspheres 54 in the sealing element 52, i.e., the volume content of the gas, is lower in the second junction 59 than outside the first and second junctions 57, 59. Conversely, the weight content of the polymer matrix is ​​higher in the first and second junctions 57, 59 than outside the first and second junctions 57, 59. In summary, that is, along a line perpendicular to the surface of the metal layer, the first and second junctions 57, 59 have a certain thickness relative to the total maximum layer thickness of the sealing element 52 measured perpendicular to the surface 61 of the metal layer 60, for example, it may be up to 35%, preferably up to 30%, particularly preferably up to 23%, and particularly preferably up to 18%. The formation of such a second junction 59 of the sealing element 52 requires appropriate process control, particularly appropriate temperature control of the coating process, crosslinking process, and / or expansion process. Advantageously, crosslinking occurs prior to expansion in the first junction and optionally the second junction.

[0095] One possible first mechanism (or explanation) for the non-uniform concentration of microspheres 54 in the elastomeric sealing element 52 is that the coating material of the sealing element 52 without microspheres has a higher affinity for the surface structure 62 than the coating material containing microspheres 54. The reason for this modified (higher) affinity could be that the chemical surface composition of the metal layer 60 differs in the region of the surface structure 62 from that in the untreated, unstructured region, and / or that the roughness of the metal layer 60 differs in the region of the surface structure 62 from that in the untreated, unstructured region. This is particularly true in the case of laser treatment of the metal layer 60 (see the manufacturing method below). A second possible mechanism is that the size of the surface-treated recess 64 is smaller than the size of the microspheres 54. The microspheres 54 are geometrically misfitted to the recess 64, and therefore the concentration of microspheres 54 is lower in the junction 59 than above the junction 59. It should be noted that these two proposed mechanisms are not mutually exclusive and may occur simultaneously.

[0096] Figure 6 and Figure 7 The sealing element 52 of the sealing arrangement 50 shown is disposed only on the surface area of ​​the metal layer 60 having the surface structure 62. In other words, the sealing arrangement 50 is not positioned at an untreated location on the metal layer 60.

[0097] Figure 8 The sealing element 52 shown is arranged partially on the surface structure 62. The sealing element 52 is also arranged partially on the untreated smooth area 63 of the metal layer 60. Therefore, the surface structure 62 exists only in some portions of the surface 61 of the metal layer 60 coated with the sealing element 52. Figure 9 The sealing element 52 shown extends slightly beyond the surface structure 62 into the untreated area 63 on both sides; here, the surface structure 62 is therefore only present in some portions of the surface 61 of the metal layer 60 coated by the sealing element 52.

[0098] The total layer thickness of the sealing element 52 may, for example, not exceed 500 μm, preferably not exceed 300 μm, more preferably not exceed 200 μm, and particularly not exceed 150 μm. Here, the layer thickness is preferably determined to be perpendicular to the surface 61 of the metal layer 60. The elastomeric sealing element 52 may in particular comprise the following materials: FPM (fluororubber), silicone rubber or NBR (nitrile butadiene rubber), PUR (polyurethane), NR (natural rubber), FFKM (perfluororubber), SBR (styrene-butadiene rubber), BR (butyl rubber), FVSQ (fluorosilicone rubber), CSM (chlorosulfonated polyethylene), silicone resin, epoxy resin, or mixtures of the above, or pressure-sensitive adhesives and / or physical adhesives. Fillers or other additives may also be provided in the elastomeric material of the sealing element 52.

[0099] In the expanded state, the microspheres are typically filled with a gaseous medium 58, wherein the gas 58 can be, for example, a saturated hydrocarbon, such as n-pentane, isopentane, or isobutane. The gas 58 is typically enclosed within the microspheres 54 and preferably cannot escape from the sealing element 52.

[0100] The average diameter of the microspheres 54 in the expanded state can be at least 20 μm and / or at most 80 μm. According to one example, the average diameter of the microspheres 54 is in the range of 35 μm to 55 μm. The width or diameter of the recesses 64, particularly when measured at the midpoint of the recess 64 and / or parallel to the untreated metal surface 61, is at most 150 μm, preferably at most 100 μm, and especially at most 70 μm. Because the size of the recesses 64 is on the micrometer scale, the surface structure can also be referred to as a surface microstructure. Adjacent recesses 64 are preferably spaced apart from each other and therefore do not merge together.

[0101] exist Figure 6 In one embodiment, the recess 64 has a diameter larger than the average diameter of the microspheres 54. Figure 7 In one embodiment, the recess 64 has a certain diameter, which is smaller than the average diameter of the microspheres 54. Figures 5 to 9 The simplification is that all microspheres are shown as having the same diameter, but in reality they always have a range of diameters.

[0102] In this regard, we should also refer to Figure 20 The image shows a microscope image of a metal layer 60 having a surface structure 62 in the form of a recess 64. Figure 20 This will be discussed again below.

[0103] Typically, the depth of the recess 64 is at least 2 μm and / or at most 40 μm. The depth of the recess 64 may particularly not exceed 20% of the thickness of the metal layer 60. The depth of the recess 64 is preferably measured from the untreated surface 61 to the lowest point of the recess 64.

[0104] The size of a single indentation 64 is, for example, 0.0001 mm. 2 up to 0.05mm 2 Within this range, especially 0.001mm 2 Up to 0.02mm 2 And preferably 0.0008mm 2 up to 0.01mm 2 According to one variation, there are approximately 500 to 100,000 recesses per square centimeter, preferably 4,000 to 20,000 recesses. It can be configured such that 10% to 90%, preferably 20% to 50%, and particularly 25% to 50%, of the surface 61 of the metal layer 60 having the surface structure 62 is occupied by recesses 64.

[0105] The recess 64 is preferably created by means of laser radiation. In other embodiments, the recess 64 is created mechanically, for example by engraving or scribing the metal layer 60.

[0106] Figures 10-18 An example cross section is shown of the protruding edge 65 passing through the metal layer 60.

[0107] Figure 10 A metal layer 60 according to the prior art is shown, which has a protruding edge 65. The metal layer 60 and the protruding edge 65 have relatively smooth unstructured surfaces 63, and therefore specifically do not have surface structures 62.

[0108] on the contrary, Figures 11-18 The metal layer 60 and its protruding edge 65 shown have a surface structure 62 in at least certain areas. The surface structure 62 is formed on the surface of the protruding edge 65, that is, on the surface of the convex side of the protruding edge 65 of the layer 60. For clarity, the sealing element 52 is not shown here. It will be apparent to those skilled in the art that the sealing element 52 in the sealing arrangement 50 is positioned on the protruding edge 65; the width (lateral range) of the sealing element is represented by the bracket 52 in each case.

[0109] like Figures 11-18 As shown, each protruding edge 65 according to one embodiment of the present invention is integrally formed in the metal layer 60, for example by punching, deep drawing, and / or hydroforming. Figures 11-14 and Figures 16-18 In some embodiments shown, each protruding edge 65 has at least one protruding edge flank 66, 66' and a protruding edge top 68, the protruding edge top 68 being adjacent to the protruding edge flanks 66, 66' on both sides. The protruding edge top 68 is formed, for example, in the outer edge region 22 of the metal layer 60, as a protrusion relative to the plane of the plate defined by the metal layer 60. In the regions of the protruding edge flanks 66, 66', the material of the layer 60 is raised at an angle to the plane of the plate. The protruding edge top 68 can be as follows: Figures 11-14 and Figure 18 The image shows the region of the convex edge 65 that extends substantially parallel to the plane of the plate, or it can be represented as follows: Figure 16-17 The diagram shows a curved section. On the other hand, in... Figure 15 In one embodiment, the convex edge 65 has only a strongly curved convex edge top 68', so the side wings are integrated into the curved portion, that is, there are no obvious convex edge side wings.

[0110] If possible Figures 11-18 As can be seen, the surface structure 62 extends at least in some areas on the top of the convex edge 68, 68' and / or optionally at least one convex edge wing 66, 66'.

[0111] Therefore, in Figure 11 , Figure 13 and Figures 15-18 The variant indicates that the entire top of the convex edge 68 is configured to completely cover the surface structure 62, while Figure 12 and Figure 14 The top of the convex edge 68 has a surface structure 62 in some areas, but has at least one unstructured area 63 in the middle or at least spaced apart from the convex edge wings 66, 66'.

[0112] exist Figure 11 , Figure 12 and Figure 14 In the variant, approximately one-third of each convex side wing 66, 66' is provided with a surface structure 62. In this case, the surface structure 62 of the convex side wing 66, 66' is adjacent to the surface structure 62 of the convex top 68.

[0113] exist Figure 13 In the variant, only the convex wing 66' includes surface structure 62, while the convex wing 66 is unstructured or smooth. In other variants, structure 62 can change along the path of the convex wing 65 from the convex wing 66' to the convex wing 66 and back, and this change may occur multiple times. For example, in Figure 18 In a variant, the figure shows a cross-section through the convex edge 65, which merges into passage 13 on the left, and the next passage 13' can be seen in the background on the right, offset relative to passage 13 shown in the figure. Passages 13 and 13' have no surface structure or coating. If this surface structure 62 changes between the convex edge flanks 66 and 66', the overall width of the surface structure 62 may vary along the path or remain constant.

[0114] However, as Figure 14 As shown in the variant, the surface structure 62 can also extend laterally beyond the area of ​​the corresponding convex side wings 66, 66', and can cover a portion of the convex foot 67, 67'.

[0115] Figures 11-18 The convex edge 65 shown may be, for example, one of the convex edges 12a-12d described above. Thus, the convex edge 65 may surround one of the through openings 11a-11c for the fluid or flow field 17 in an essentially closed manner, and may be configured as a sealing convex edge 12a-12d.

[0116] Metal layer 60 can be configured, for example, as the aforementioned layers or plates 2, 2a, 2b, particularly partitions 2a, 2b (see...). Figures 1-4 )one of the.

[0117] Figure 19 A flowchart of a method for producing a sealing arrangement 50, particularly the sealing arrangement described above, according to the present invention is shown.

[0118] The method includes at least the following steps:

[0119] -S1: Provides a 60mm metal layer.

[0120] -S2: Provide a metal layer 60 having a surface structure 62, the surface structure 62 including a plurality of recesses 64.

[0121] -S3: Apply a foamable material containing expandable microspheres 54 to the surface structure 62.

[0122] -S4: An elastomeric sealing element 52 is formed on the metal layer 60 by expanding the microspheres 54, wherein the distribution of the expanded microspheres 54 in the sealing element 52, measured perpendicular to the surface 61 of the metal layer 60, is non-uniform.

[0123] In a preferred variant, the depression 64 in step S2 is generated by laser radiation. For example, a pulsed laser can be used here.

[0124] In optional step P, the sealing flanges 12a-12d, 65 are integrally formed in the metal layer 60, for example, by embossing, deep drawing, and / or hydroforming. This can occur before, simultaneously with, or after the formation of the surface structure 62 in the metal layer 60.

[0125] Figure 20 A microscopic image of a metal layer 60 with a surface structure 62 formed by means of a laser is shown. The laser system used here has a power of 100 watts, a wavelength of 1064 nm, a focal length of 254 mm, and an ablation rate of approximately 25 cm⁻¹. 2 / s. Of course, other laser systems or lasers are also suitable for creating surface structures 62 or depressions 64.

[0126] Regarding the characteristics of the recess 64 in surface structure 62, refer to the above description. From Figure 20It can also be seen that the recesses 64 can be arranged, for example, as rows or paths 69 extending parallel to each other; this is especially true when a surface structure is formed on the straight portion of an outer peripheral convex edge. The row arrangement 69 of the recesses 64 can be the result of producing the recesses 64 by means of a laser. It is also possible to arrange the recesses on concentric circles, as can be used, for example, in the case of a port convex edge. In this case, the concentric circles form paths 69. Many other forms are conceivable; preferably, the recesses are arranged close to each other on paths 69 such that these paths follow the route of the surface to be constructed, that is, especially when the convex edge extends in a wavy manner (at least in a nearly wavy manner). Each recess 64 can be at least partially surrounded by a protrusion 75 formed at the corresponding circumferential edge of the recess. The corresponding protrusion 75 can protrude above the untreated surface 63 of the metal layer 60. The protrusion 75 is typically formed when the recesses 64 are formed, for example, by laser radiation, and the protrusion 75 forms crater-like edges by the solidification of the molten material. Therefore, the edge of the crater or protrusion 75 can be formed by material migrating from the depression 64.

[0127] exist Figure 20 It can also be seen that the circumferential edge of the recess 64 is basically circular. The diameter of the basically circular recess 64 is approximately 65 μm. The shape of the circumferential edge of the recess can depend on the lateral range of the laser beam used and the angle at which the laser beam is incident on the metal layer 60. Therefore, the shape of the circumferential edge can also depend on the corresponding position of the recess 64 on the metal layer 60. For example, the circumferential edge of the recess 64 arranged on the top of the convex edge 68 can be circular, while the circumferential edge of the recess 64 arranged on the flanks of the convex edge 66, 66' can be elliptical or oval. The reason for this dependence may be due to the dependence on the laser incident angle described above, since the top of the convex edge 68 and the flanks of the convex edge 66, 66' usually have different surface normals.

[0128] To achieve the full effect of surface structure 62, the maximum spacing between adjacent recesses 64 should be at most five times the diameter of the recess 64. On the other hand, the recesses 64 should not be arranged too close to each other, as this may lead to material damage. Adjacent recesses 64 preferably have a minimum spacing corresponding to half the diameter of the recess 64. The spacing between adjacent recesses 64 may differ in the longitudinal direction (i.e., in the longitudinal direction of the row or path 69) and the transverse direction of the sealing element 52. In the transverse direction, the minimum spacing should correspond to at least half the diameter. Furthermore, in the transverse direction, the minimum spacing may correspond to at most three times the diameter. In the longitudinal direction, the minimum spacing may correspond to at least the diameter of the recess. In the longitudinal direction, the maximum spacing should be five times the diameter. Here, it is considered that the spacing is only within the continuous surface structure area, that is, in Figure 12In the example, on the one hand, it is in the region of the convex side wing 66 and the left region of the convex top 68, while on the other hand, it is in the region of the convex side wing 66' and the right region of the convex top 68.

[0129] In alternative variations of this method, the recess 64 is used to produce microstructures, for example, by carving or scribing. In this case, the recess 64 can be constructed as circular, elliptical, or oval recesses; in particular, these shapes can be combined with each other.

[0130] In step S3, the foamable material can be applied to the metal layer 60 or its surface structure 62 by spraying, brush plating, screen printing, roller printing, stencil printing, or metering processes. Once the foamable material has been applied to the surface structure 62, the solvent contained in the foamable material can evaporate. Evaporation of the solvent can be stimulated by applying negative pressure or a vacuum, or by increasing the temperature to a first temperature. In another step, the elastomer material can be crosslinked or partially crosslinked. This (partial) crosslinking can be stimulated, for example, by a temperature jump or by UV radiation, such as by raising the temperature to a second temperature, preferably higher than the first temperature.

[0131] As the temperature rises, the microspheres 54 expand due to the phase change of the medium they contain from a liquid phase to a gas phase. The expanded shape of the microspheres is maintained even upon cooling due to the cross-linking of the polymer and the bonding of the microsphere shell to the surrounding polymer.

[0132] In some embodiments of the method, the microspheres 54 in their unexpanded state have an average diameter of at least 5 μm and / or at most 50 μm. In their expanded state, the microspheres 54 may have an average diameter of at least 20 μm and / or at most 80 μm. By expanding the microspheres 54, the maximum thickness of the sealing element 52, which is applied as a layer, is typically expanded several times. For example, the maximum layer thickness of the finished sealing element 52 is four times the layer thickness of the foamable material.

[0133] This method is particularly suitable for the production of the aforementioned sealing arrangement 50, plate assembly 70, and / or electrochemical system 1. Therefore, the features described in connection with the sealing arrangement 50, plate assembly 70, and / or electrochemical system 1 can be combined with or claimed in this method, and vice versa.

[0134] List of reference numerals in the attached diagram:

[0135] 1. Electrochemical System

[0136] 2 Bipolar plates

[0137] 2a Partition (single panel)

[0138] 2b Partition (Single Panel)

[0139] 3 end plates

[0140] 4 end plates

[0141] 5. Media Port

[0142] 6 stacking

[0143] 7 Z direction

[0144] 8 X direction

[0145] 9 Y direction

[0146] 10 Membrane Electrode Assembly

[0147] 11a-c Through opening

[0148] 12a-d Sealing convex edge

[0149] 13 access

[0150] 13a-c pathway

[0151] 14 Membrane

[0152] 15 Sealed edge area

[0153] 16 Gas diffusion layer

[0154] 17 Flow Field

[0155] 18 Electrochemical active regions

[0156] 19 cavities

[0157] 20. Distribution and Collection Areas

[0158] 22 Outer edge region

[0159] 24 Contact Area

[0160] 29 channels

[0161] 50 Sealing arrangement

[0162] 52 Elastomer sealing element

[0163] 54 microspheres

[0164] 56 Elastomers

[0165] 57 First junction (metal plate - elastomer)

[0166] 58 Gases

[0167] 59 Second junction (elastomer - surrounding environment)

[0168] 60 metal layers

[0169] 61 Surface of the metal layer

[0170] 62 Surface Structure

[0171] 63 Unprocessed areas

[0172] 64. Depression

[0173] 65 convex edge

[0174] 66,66' Convex side wing

[0175] 67,67' Convex foot

[0176] 68. Convex top edge

[0177] 69. Concave lines

[0178] 70-board assembly

[0179] 75. Edge of the crater

Claims

1. A sealing arrangement, said sealing arrangement (50) comprising: - An elastomeric sealing element (52), the elastomeric sealing element comprising a foamed material containing microspheres (54), and - A metal layer (60) having a surface structure (62) including a plurality of recesses (64). The elastomeric sealing element (52) is configured as a coating of the metal layer (60) and is disposed at least in some areas of the surface structure (62). The concentration of microspheres (54) in the elastomeric sealing element (52), measured on the surface (61) perpendicular to the metal layer (60), is non-uniform; At least one protruding edge (65) is integrally formed in the metal layer (60), the surface structure (62) is formed on the surface of the protruding edge (65), and the elastomeric sealing element (52) is disposed on the protruding edge (65); The convex edge (65) has a convex edge top (68) and at least one convex edge side wing (66, 66') adjacent to the convex edge top (68), the surface structure (62) extends over at least some areas of the convex edge top (68) and the at least one convex edge side wing (66, 66'), and the elastomeric sealing element (52) is disposed over at least some areas of the convex edge top (68) and the at least one convex edge side wing (66, 66').

2. The sealing arrangement (50) according to claim 1, characterized in that, The elastomeric sealing element (52) has a first junction (57) adjacent to the metal layer (60), and the concentration of microspheres (54) in the elastomeric sealing element (52) is lower within the first junction (57) than outside the first junction (57).

3. The sealing arrangement (50) according to claim 2, characterized in that, The elastomeric sealing element (52) has a second junction (59) away from the metal layer (60), and the concentration of microspheres (54) in the elastomeric sealing element (52) is lower within the second junction (59) than outside the first junction (57) and the second junction (59).

4. The sealing arrangement (50) according to claim 3, characterized in that, The first junction (57) and the second junction (59) have a certain thickness, either individually or together, which is no more than 35% of the total maximum layer thickness of the elastomeric sealing element (52) as measured perpendicular to the surface (61) of the metal layer (60).

5. The sealing arrangement (50) according to claim 1, characterized in that, The average diameter of the microspheres (54) is at least 20 µm and / or at most 80 µm.

6. The sealing arrangement (50) according to claim 1, characterized in that, The width and / or diameter of the recess (64) is at most 150µm.

7. The sealing arrangement (50) according to claim 1, characterized in that, The recess (64) has a certain depth, the depth being at least 2µm and / or at most 40µm, and / or the depth of the recess (64) not exceeding 20% ​​of the thickness of the metal layer (60).

8. The sealing arrangement (50) according to claim 1, characterized in that, The elastomeric sealing element (52) comprises: FPM (fluororubber), silicone rubber or NBR rubber (nitrile rubber), PUR (polyurethane), NR (natural rubber), FFKM (perfluororubber), SBR (styrene-butadiene rubber), butyl rubber, FVSQ (fluorosilicone rubber), CSM (chlorosulfonated polyethylene), silicone resin, epoxy resin or a mixture of the above substances, or pressure-sensitive adhesive and / or physical adhesive.

9. The sealing arrangement (50) according to claim 1, characterized in that, The microspheres (54) are filled with a gaseous medium.

10. The sealing arrangement (50) according to claim 1, characterized in that, The elastomeric sealing element (52) surrounds at least one through opening (11a-11c) for gas or liquid formed in the metal layer (60) in an essentially closed manner.

11. The sealing arrangement (50) according to claim 1, characterized in that, The metal layer (60) is configured as part of a separator (2a, 2b) or bipolar plate (2) for use in an electrochemical system.

12. A plate assembly for an electrochemical system, said plate assembly (70) comprising: A sealing arrangement (50) having an elastomeric sealing element (52) comprising a foamed material containing microspheres (54); and two partitions (2a, 2b) configured as a metal layer (60) having a surface structure (62) in at least some regions, the surface structure (62) comprising a plurality of recesses (64); And a membrane electrode assembly (10) disposed between the partitions (2a, 2b), wherein the elastomeric sealing element (52) is configured as a coating on at least one side of each of the partitions (2a, 2b) and disposed in at least some areas on the surface structure (62), and wherein the concentration of microspheres (54) in the elastomeric sealing element (52) measured perpendicular to the surface (61) of the metal layer (60) is non-uniform; At least one protruding edge (65) is integrally formed in the metal layer (60), the surface structure (62) is formed on the surface of the protruding edge (65), and the elastomeric sealing element (52) is disposed on the protruding edge (65); The convex edge (65) has a convex edge top (68) and at least one convex edge side wing (66, 66') adjacent to the convex edge top (68), the surface structure (62) extends over at least some areas of the convex edge top (68) and the at least one convex edge side wing (66, 66'), and the elastomeric sealing element (52) is disposed over at least some areas of the convex edge top (68) and the at least one convex edge side wing (66, 66').

13. An electrochemical system comprising a plurality of sealing arrangements according to claim 11 and / or a plurality of plate assemblies for an electrochemical system according to claim 12.

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