Separator for electrolyser and method of manufacturing separator

Abstract

The invention relates to a separator (1) for an electrolyser, comprising:-a metal layer (10) having a sectioned surface structure (12), the surface structure (12) comprising a plurality of channel-like depressions (14) produced by a laser surface treatment,-an elastomeric coating (20), the elastomeric coating (20) being designed as a sealing element, the elastomeric coating (20) being applied to the metal layer (10), and an elastomer coating (20) for sealing at least one region of the separator (1), the elastomer coating (20) being arranged at least in some regions on the surface structure (12). The invention further relates to a method for producing the separator (1).

Description

Technical Field

[0001] The present invention relates to a separator for an electrolyzer and a method for manufacturing the separator for an electrolyzer. Background Art

[0002] For example, an electrolyzer produces hydrogen and oxygen from water by applying an electrical potential, and at the same time may compress at least one of the produced gases.

[0003] Conventional electrolyzers usually consist of stacked individual cells, each of which has a series of layers with a separator, two dielectric diffusion structures and a membrane electrode assembly (MEA), the two dielectric diffusion structures being in particular (one or more) porous transport layers (PTL) and / or gas diffusion layers (GDL). Since the medium is introduced into the cell at an overpressure relative to the external pressure, the electrochemical cell stack must be sealed relative to the outside. To this end, for each individual electrochemical cell stacked on each other to form the electrolyzer, the electrolyzer usually has a cell frame extending around the outer edge of the electrochemical cell. The individual cells in the stack are pressed between two end plates, for example by means of screws. Between the individual cell frames and between the cell frames and the separator or membrane electrode assembly arranged between the cell frames, the stack of electrochemical cells has a sealing element, which extends circumferentially along the periphery, but is usually located at a certain distance inward of the periphery.

[0004] The individual cells combined to form a stack are each separated by separators, which serve on the one hand to separate the medium and on the other hand to transfer the current or voltage from the individual cells to the individual cells, in particular due to the mesh structure between the fluid-conducting channels in contact with the MEA (possibly indirectly). The separators usually have a flow field on their surface with a channel structure arranged to supply and discharge the fluid. The task of the flow field or the channel structure of the flow field is to ensure the distribution of the medium on the surface. Such separators are also called bipolar plates, because they simultaneously form the anode of the first cell and the cathode of the cell adjacent to the first cell.

[0005] The medium, ie in many cases water, oxygen and hydrogen, is usually supplied or discharged via through-openings formed in the separators. The through-openings of the stacked separators are arranged in an overlapping manner so that they form a fluid line.

[0006] In an electrolyzer, the pressure difference between the surroundings and the interior of an electrochemical cell may exceed 20 bar. For example, the pressure on the product side, such as the H2 side, may be as high as 40 bar, while the pressure on the reactant side, such as the H2O side, is only at most 2 bar. It is therefore important to seal the flow field with respect to the surroundings and within the electrochemical system. For this purpose, sealing elements arranged around the flow field and / or sealing elements arranged around the through-opening are usually provided.

[0007] The flow field and / or through-opening are usually sealed using a bead molded into the partition, an elastic seal molded onto the metal layer of the partition, or a combination thereof. To avoid leakage, it is important that the elastomeric seal is firmly bonded to the metal layer. In order to ensure that the elastomeric seal is attached to the metal layer of the partition as much as possible, one surface of the metal layer is usually treated with a single layer of attachment promoter or a double layer combination of primer and attachment promoter before applying the elastomeric seal. Primers and attachment promoters are usually composed of active polymers in a solvent mixture. Typically, the entire surface of the metal layer is coated with an attachment promoter and / or primer, for example in a solvent-containing bath, although only individual areas of the layer are provided with an elastomer, and the layer only needs to be coated with an attachment promoter in these areas. In addition, the bonding agent or primer in the activation area of ​​the partition will affect the necessary conductivity, and therefore usually must be removed again in the activation area, i.e. in the flow field.

[0008] Therefore, there is a need to seal the liquid-carrying area of ​​the separator as much as possible, either from the environment or within the electrolyser. The present invention has been designed to at least partially address the above problems. Summary of the invention

[0009] The invention is defined by a separator and a method according to the independent claims. Further developments are described in the dependent claims and in the following description.

[0010] According to a first aspect of the present disclosure, a separator for an electrolyzer is provided. The separator comprises a metal layer having a segmented surface structure, wherein the surface structure comprises a large number of channel-shaped depressions produced by laser surface treatment. In addition, the separator has an elastomeric coating designed as a sealing element, the elastomeric coating being applied to the metal layer to seal at least one area of ​​the separator. The elastomeric coating is arranged at least in some areas on the surface structure.

[0011] In a preferred embodiment, the surface structure is designed to improve the adhesion of the elastomer coating to the metal layer. Due to the improved adhesion, a pretreatment with an adhesion promoter and / or a primer can be omitted, thereby avoiding the use of environmentally harmful chemicals. In addition, the surface structure formed as laser surface structure can be introduced precisely into the material of the metal layer by laser and, in particular, can be provided in the metal layer only where it is required. For example, the surface structure can be carried out only in the area where the elastomer coating is present. Conversely, the elastomer coating can be located only in the area of ​​the surface structure, wherein the lateral protrusion of the elastomer coating should have a maximum of 3 mm.

[0012] The separator may also have a PVD coating applied to the metal layer, with the elastomer coating being arranged on the PVD coating at least in some areas. PVD is an abbreviation for "physical vapor deposition". In general, PVD utilizes a physical process to convert a starting material into a gas phase. The gaseous material is then directed to the substrate to be coated - in this case the metal layer - where it condenses and forms the target layer. PVD will not be described in detail here, as the process has been carried out for some time using commercial machines.

[0013] The PVD coating and the surface structure may be arranged to overlap one another in an overlapping region and the elastomeric coating may be arranged at least or only in the overlapping region of the PVD coating and the surface structure. The PVD coating 30 may also lead to a further improvement in the attachment of the elastomeric coating 20 .

[0014] According to one example, the PVD coating is arranged on the surface structure. In this case, the surface structure can be generated first and then the PVD coating is applied to the surface structure. In another example, the channel-shaped depressions of the surface structure form at least partial interruptions in the PVD coating. In this case, the metal layer can be coated with the PVD coating and then the channel-shaped depressions are generated with a laser.

[0015] The channel-shaped recessed portion can be, for example, linear, preferably straight. In particular, the channel-shaped recessed portion can run parallel to each other, intersect and / or form a diamond grid structure at least in sections. Alternatively, the recessed portion can be annular or spiral.

[0016] In this case, the length of the channel-shaped depression is advantageously greater than the width, at least by a factor of 5, advantageously by a factor of 10.

[0017] The channel-shaped depressions usually form a macrostructure of the metal layer, wherein the metal layer has a microstructure within the channel-shaped depressions. The macrostructure and / or microstructure can increase the surface area of ​​the metal layer, allowing the elastomeric coating to better attach to the metal layer. An undercut, such as a mushroom-shaped undercut, can also be formed within the channel-shaped depressions, into which the elastomeric coating can penetrate. The attachment can be further improved by the local form of the elastomeric coating and the undercut. The undercut can be part of the microstructure.

[0018] In one embodiment, the channel-shaped recess is at least partially surrounded by protrusions, in particular laterally surrounded, which are formed on the corresponding circumferential edges of the channel-shaped recess. The corresponding protrusions can then protrude above the untreated surface of the metal layer and are formed in particular by the material removed from the channel-shaped recess. In some embodiments, the protrusions can preferably also have a microstructure. For example, the height of the protrusions is at most 30 μm or at most 20 μm relative to the untreated surface of the metal layer. The depth of the channel-shaped recess relative to the untreated surface of the metal layer can be set to be at least 7 μm and / or at most 50 μm, and / or wherein the width of the channel-shaped recess is at least 35 μm and / or at most 150 μm, and / or wherein the layer thickness of the PVD coating is at least 100 nm and / or at most 1 μm, and / or wherein the layer thickness of the elastomer coating is at least 10 μm and / or at most 3 mm. The width of the parallel recesses can be at least 1.5 times the width of the recesses, and / or at most 3 mm apart. If two or more channel-shaped recesses intersect, the depth of the intersection of the recesses may be greater, for example at least 1.5 times, for example 2 times, the depth of a single channel-shaped recess.

[0019] The metal layer is usually made of titanium or stainless steel, for example stainless steel 1.4404 or 1.4541. The metal layer can be made at least mainly or completely of these materials. However, the invention is not limited to these materials.

[0020] The PVD coating may comprise at least one layer, for example two layers. If more than one layer is provided, the layers are generally different in their materials. The PVD coating may comprise or consist of at least one of the following materials: titanium, nickel, niobium, tantalum, carbon, platinum, zirconium, carbide, titanium nitride, titanium aluminum nitride and / or titanium carbonitride. However, the present invention is not limited to these materials.

[0021] The elastomer coating may also include or consist of the following materials: FKM (fluororubber), silicone rubber or NBR rubber (nitrile rubber), PUR (polyurethane), NR (natural rubber), FFKM (perfluororubber), SBR (styrene butadiene rubber), BR (butadiene rubber), FVMQ (fluorosilicone rubber), CSM (chlorosulfonated polyethylene), HNBR (hydrogenated nitrile butadiene rubber), ACM (acrylate rubber), AEM (acrylate-ethylene rubber), EPDM (ethylene-propylene-diene rubber), IIR (butyl rubber) or a mixture of the foregoing. However, the present invention is not limited to these materials.

[0022] The separator generally has at least one through opening for the reaction medium or product medium to pass through, and / or at least one flow field for guiding the reaction medium or product medium along the separator. Typically, the elastomeric coating is arranged around the through opening and / or the flow field to seal the through opening or the flow field. The desired electrolysis reaction generally occurs in the region of the flow field, for example, decomposing water into hydrogen and oxygen. The flow field optionally has a channel structure. The channel structure of the flow field is generally formed integrally in the separator, for example by convex pressing, hydroforming or deep drawing.

[0023] The separator can in particular be designed as a bipolar plate. In other words, the separator in a stack of electrochemical cells connected in series can form the anode of a first electrochemical cell on one side and the cathode of a second electrochemical cell adjacent to the first electrochemical cell on the other side.

[0024] According to another aspect, an electrolyzer is provided, wherein the electrolyzer comprises a plurality of stacked separators of the above type. A membrane electrode assembly (MEA) and / or a porous transport layer (PTL) or a gas diffusion layer (GDL) arranged between the MEA and the separator may also be provided for each separator.

[0025] According to another aspect, a method for manufacturing a separator for an electrolyzer is provided. The method comprises at least the following steps:

[0026] - generating a surface structure in the metal layer by irradiating the metal layer with a laser, wherein the surface structure comprises a plurality of channel-shaped depressions,

[0027] - Applying an elastomeric coating to the metal layer at least in the region of the surface structure.

[0028] The elastomer coating is designed as a sealing element for sealing at least one region of the partition wall.

[0029] The method may also have the further step of applying a PVD coating to the metal layer, wherein an elastomeric coating is applied to the metal layer in the region of the PVD coating.

[0030] The surface structure and the PVD coating may overlap each other in the overlapping region. The elastomeric coating is usually applied at least to the overlapping region. In one embodiment, the metal layer is first provided with a PVD coating and then laser surface treated at least in this region to generate the surface structure. Alternatively, the metal layer is first laser surface treated to form the surface structure. Then, at least in this region, a PVD coating is provided on the metal layer.

[0031] The method described here is particularly suitable for producing the above-mentioned separators, or is designed for this purpose. Features described only in connection with the separator can be combined with the method, and vice versa. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Embodiments of separators, arrangements and electrochemical systems are shown in the attached drawings and explained in detail in the following description. In the drawings:

[0033] Figure 1 shows an exploded view of a single cell of an electrolyser comprising a separator according to the invention;

[0034] Figure 2 shows a top view of a metal layer of a separator according to one embodiment;

[0035] Figure 3 Shown through Figure 2 A cross-section of a partial area of ​​the separator is shown;

[0036] Figure 4 shows a section through a section of another bulkhead;

[0037] Figure 5 shows a section through a section of another bulkhead;

[0038] Figure 6 Laser surface treatment test specimens are shown;

[0039] Figures 7 to 11 Various surface structures are shown;

[0040] Fig.12 SEM images showing the surface structure; and

[0041] Fig.13 Another SEM image showing the surface structure;

[0042] Fig.14 shows a section through a portion of a baffle in another embodiment;

[0043] Fig.15 Shows Fig.14 Detailed view of section A in FIG. DETAILED DESCRIPTION

[0044] Here and hereinafter, features which occur repeatedly in different figures are each provided with the same or similar reference symbols.

[0045] Figure 1 A cross-sectional view of a single electrochemical cell 100 is shown, wherein the cell 100 is part of an electrolyzer. An electrolyzer is typically composed of a large number of stacked single cells 100. A single cell 100 includes two separators 1 and 2, two cell frames 42 and 44, a sealing layer 45, and a membrane electrode assembly 40 with dielectric diffusion structures 41 and 43. For example, the dielectric diffusion structure 43 includes layered carbon fibers, and the dielectric diffusion structure 41 includes a metal, such as titanium. Here, the separator 1 is, for example, arranged on the anode side of the single cell 100. In the exemplary embodiment shown, the separator 2 is arranged on the cathode side of the single cell 100. Each of the individual layers is pressed together to form a single cell. Each of the individual layers has a fluid passage 46, 47, 50, which are arranged one above the other in alignment for the entry and exit of water, oxygen and hydrogen, and each individual layer also has a positioning hole 48.

[0046] The flow field of the separator 2 is defined by the battery cell frame 44 protruding onto the separator 2. The flow field 3 of the separator 1 is defined by the battery cell frame 42 protruding onto the separator 1. The battery cell frame 42 has a distribution channel (not shown) for distributing the water fed in. The through openings 46, 47 are fluidly connected to the flow field 3 so that the medium can be led from the through opening 46 to the flow field 3, or from the flow field 3 to the through opening 47. When an electric potential is applied, hydrogen (or oxygen) can be produced from the supplied water. This can be discharged through the distribution channel 49 in the battery cell frame 44. It can then leave the battery cell through the through opening 50. Although Figure 1 The partition 1 shown has a circular outer contour, but other shapes are also possible. For example, the partitions 1, 2 can have a rectangular outer contour (see also Figure 2 and 6 ).

[0047] Figure 1 The separators 1 and 2 in FIG. 1 are exemplary separators according to the prior art.

[0048] As already pointed out above, the pressure difference between the environment and the interior of the electrochemical cell 100 may exceed 20 bar. For example, the pressure on the product side, such as the hydrogen side, is typically up to 40 bar, while the pressure on the reactant side, such as the water side, is only at most 2 bar. Therefore, sealing structures are provided to seal the various areas from each other.

[0049] For example, an elastomeric seal is used which is arranged around the area to be sealed. In order to enable the elastomeric material to be bonded to the metal layer of the diaphragm 1, the metal layer is first coated with an adhesion promoter as a single-layer system or with a primer and an adhesion promoter as a two-layer system. This one or several coatings are usually on the entire surface, while the elastomeric coating is usually not on the entire surface, but only in the area of ​​the diaphragm to be sealed. In addition, the primer / adhesion promoter in the activation area of ​​the diaphragm affects the necessary conductivity and must therefore be removed again in the activation area, i.e. in the flow field.

[0050] The present invention was conceived to at least partially address these problems.

[0051] In particular, it has been recognized that laser surface structures and / or PVD coatings can serve as suitable substrates for applying elastomeric coatings. In particular, this significantly improves the adhesion of elastomeric coatings applied to the laser surface structures. Figure 2-9 Further explanation.

[0052] Figure 2 A separator 1 for an electrolyser is shown. Figure 3 Shown through Figure 2 A cross-section of a local area of ​​a separator 1. The separator 1 comprises a metal layer 10, which consists, for example, at least mainly or completely of titanium or stainless steel. The thickness of the metal layer 10 is at least 0.1 mm and / or at most 1 mm. The separator 1 has a flow field 3, which is designed to distribute the water supplied from the through-opening 4 to a larger area as much as possible. For this purpose, an optional channel structure 6 is provided in the flow field 3. The through-opening 5 is designed to discharge hydrogen, wherein, on one side of the separator shown, the fluid through-opening 5 is surrounded by a surface structure 12 according to the invention and can be sealed from the environment by means of a seal after being coated with an elastomer (see below).

[0053] The section of the metal layer 10 has a surface structure 12. The surface structure 12 in turn has a large number of channel-shaped depressions 14 produced by laser surface treatment. The depressions 14 are generated by irradiating the metal layer 10 with a laser. The depth of the channel-shaped depressions 14 relative to the untreated surface 19 of the metal layer 10 is, for example, at least 7 μm and / or at most 50 μm. Figure 3 , the untreated surface 19 of the metal layer 10 is indicated by a dashed line in the region of the recess 14. For the purposes of this document, channel-shaped means that the length of the recess greatly exceeds the width of the recess, for example, exceeds the width of the recess by a factor of at least 5, at least 10 or at least 20. The length of the recess is advantageously defined as the maximum extent of the recess, for example in the processing direction or feed direction of the laser.

[0054] The width of the channel-shaped depression 14 is at least 35 μm and / or at most 150 μm. The width is usually measured at half the height of the depression 14. The width of the depression 14 usually depends on the diameter of the laser spot used to generate the depression 14. On the other hand, the length of the depression does not depend on the beam diameter of the laser used, but can be varied by moving the laser beam or moving components along the partition 1, see Figure 6-11 The ratio of the width to the depth of the channel-shaped depression may be about 1.5 to 7. This means that the channel-shaped depression is wider rather than deeper.

[0055] It is possible to provide that the channel-shaped recessed portion 14 is surrounded by protrusions 16, and the protrusions 16 are formed on the corresponding circumferential edges of the channel-shaped recessed portion 14, see Figure 3 The corresponding protrusions 16 may protrude above the untreated surface 19 of the metal layer 10 and be formed, for example, by material removed from the channel-shaped recess 14. If protrusions are provided and / or the untreated surface 19 of the metal layer 10 has irregularities and it is difficult to determine the depth of the recess 14 relative to the untreated surface 19 of the metal layer, the height of the protrusions 16 may be taken into account in the indication of the depth of the recess 14, i.e., if there should be protrusions 16 around the recess 14, the depth of the recess 14 is indicated from the apex of the protrusion 16 to the deepest point of the recess 14.

[0056] The channel-shaped depression 14 generally forms a macrostructure of the metal layer 10, wherein the metal layer 10 has a microstructure 18 in the channel-shaped depression 14. The macrostructure can be understood as the contour of the channel-shaped depression 14, while the microstructure extends in the depression 14. Compared with the untreated surface 19 of the metal layer 10, the surface roughness of the microstructure 18 is greater, which is conducive to the attachment of the elastomer seal 20 to the metal layer 10. The protrusion 16 can also have a microstructure 18. Typically, the height of the protrusion is at most 30 μm relative to the untreated surface 19 of the metal layer 10. Cuttings, such as mushroom-shaped cuttings, can also be formed in the channel-shaped depression 14, into which the stationary liquid elastomer compound can penetrate. After the elastomer compound has solidified to form the elastomer coating 20, and by the local form of the elastomer coating 20 and the cutting, the attachment can be further improved. The cutting can be part of the microstructure (microscopic cutting).

[0057] Figure 6-11 1 shows different types of surface structures 12 of the metal layer 10. Here, various macroscopic structures of the channel-shaped depressions 14 can be seen. Accordingly, the channel-shaped depressions 14 can be linear, for example straight or curved, see Figure 6-11 .

[0058] The area in which the surface structure 12 is arranged can extend in a strip along the separator 1 or the area to be sealed of the separator 1. The width of this area can be at least 0.5 mm and / or at most 10 mm. In addition, this area can be self-contained or even full-surface and can advantageously not protrude beyond the elastomer coating.

[0059] exist Figure 7 and 8 In the embodiment, there are a plurality of depressions 14 which run parallel to one another at least in sections. There are also depressions 14 which are arranged at an angle to one another. Figure 7 and 8 In the embodiment, the angle is about 90°, but other smaller or larger angles are also possible. The recessed portions arranged at a certain angle may intersect (see Figure 7 and 8 ) and form a diamond grid structure (see Figure 7 ) or honeycomb grid structure (see Fig.11 upper left corner). Fig. 9 The recesses 14 in the middle are spaced apart.

[0060] exist Fig.10 and 11 In the figure (upper right corner), the depression extends in a spiral or annular shape. Other variants of the channel-shaped depression are conceivable, and the invention is not limited to the shape of the depression 14 shown.

[0061] Fig.12 and 13 The images of the depressions 14 made using a scanning electron microscope (SEM) are shown. From these figures, the microstructure 18 in the depressions 14 can be clearly seen. In addition, the protrusions 16 arranged on both sides of the depressions 14, which divide each depression 14, can also be seen. Fig.12 Also shown are intersection points 17 of the intersecting channel-shaped recesses 14. At the intersection points 17, the depth of the recesses 14 may be greater than the depth outside the intersection points 17. This is because in the region of the intersection points 17, the metal layer 10 is irradiated with the laser beam twice.

[0062] It should also be noted that the parallel depressions 14 may be at least 1.5 times the width of the depression and / or at most 3 mm apart. About 20% to 90%, preferably 25% to 75%, of the surface of the metal layer 10 provided with the surface structure may be provided with channel-shaped depressions.

[0063] Figure 4 and 5 It shows that Figure 3 A similar section through partition 1 is shown. Figure 4 and 5The metal layer 10 has the surface structure 12 on both sides. However, the surface structure 12 can also be arranged on only one side of the metal layer 10.

[0064] from Figure 4 and 5 It can also be seen that the diaphragm 1 also has an elastomeric coating 20, which is designed as a sealing element and is applied to the metal layer 10 for sealing at least one area of ​​the diaphragm 1. The elastomeric coating 20 is arranged at least on the surface structure 12. The laser-treated surface in the area of ​​the surface structure is generally rougher than the untreated surface 19. Therefore, the increase in the surface and the increase in the roughness contribute to a significantly improved attachment of the elastomeric seal 20 arranged in the area of ​​the surface structure 12 compared to the attachment of the elastomeric seal 20 on the untreated surface 19.

[0065] For example, the layer thickness of the elastomer coating 20 can be at least 10 μm and / or at most 3 mm. The layer thickness of the elastomer coating 20 can preferably be greater than the depth of the recessed portion 14, for example at least 2 times, or at least 10 times. The elastomer coating 20 should ideally be thick enough to fully cover the raised areas of the surface structure 12, such as any protrusions 16. The elastomer coating 20 can include or be composed of the following materials, such as FKM (fluororubber), silicone rubber or NBR rubber (nitrile rubber), PUR (polyurethane), NR (natural rubber), FFKM (perfluororubber), SBR (styrene butadiene rubber), BR (butadiene rubber), FVMQ (fluorosilicone rubber), CSM (chlorosulfonated polyethylene), HNBR (hydrogenated nitrile butadiene rubber), ACM (acrylate rubber), AEM (acrylate-ethylene rubber), EPDM (ethylene-propylene-diene rubber), IIR (butyl rubber) or a mixture of the foregoing substances.

[0066] The elastomeric coating 20 designed as a sealing element can form a sealing profile or a sealing line. Figure 2 As indicated, the partition wall 1 may have at least one through opening 47, Figure 2 In the example of the present invention, the through opening 5 is a hydrogen port for the reaction medium or product medium to pass through, and / or has at least one flow field 3 for guiding the reaction medium or product medium along the partition 1. The elastomer coating 20 is arranged around the through opening 47, 5 and / or the flow field 3 to seal the through opening or the flow field 3.

[0067] Optionally, the separator 1 may have a PVD coating 30 applied to the metal layer 10, see Figure 4 and 5 The elastomeric coating 20 is typically disposed at least in some areas on the PVD coating 30, see Figure 4 and 5The PVD coating 30 and the surface structure 12 generally overlap each other in an overlap region 24 , wherein the elastomeric coating 20 is disposed at least in the overlap region 24 of the PVD coating 30 and the surface structure 12 . The PVD coating 30 may also improve the adhesion of the elastomeric coating 20 .

[0068] The layer thickness of the PVD coating 30 is usually significantly smaller than the layer thickness of the elastomeric coating and may be at least 100 nm and / or at most 1 μm. Figure 4 and 5 The dimension ratios in the figure do not necessarily correspond to reality; on the contrary, the PVD coating 30 is shown exaggerated for the sake of clarity. The arrangement of the surface structure 12 and the PVD coating relative to each other depends on which surface treatment is performed first, i.e., laser surface treatment or application of the PVD coating. For example, if laser surface treatment is performed first and then PVD coating, the PVD coating 30 can be arranged on the surface structure 12 (see Figure 4 ). Alternatively, if the order of the surface treatment is reversed, the channel-shaped depressions 14 of the surface structure 12 can at least partially form interruptions 34 in the PVD coating 30 (see Figure 5 ).

[0069] The PVD coating 30 may include at least one layer of at least one material, or may include two layers of different materials. The PVD coating may include or consist of at least one of the following materials: titanium, nickel, niobium, tantalum, carbon, platinum, zirconium, carbide, titanium nitride, titanium aluminum nitride and / or titanium carbonitride.

[0070] Figure 4 and 5 The metal layer 10 of FIG. 1 has an elastomer coating 20 and a PVD coating 30 on both sides. However, the elastomer coating 20 and the optional additional PVD coating 30 can also be provided on only one side of the metal layer 10 .

[0071] For direct comparison, Figure 4 and 5 However, Fig.14 and 15 The metal layer 10 of the separator 1 does not have a PVD coating 30, but rather only has an elastomer coating 20 on each side of the metal layer 10 of the separator 1. When viewed parallel to the layer plane of the metal layer 10, the elastomer coating 20 is arranged alternately in groove-like embossed depressions 11, which have been molded into the sealing area of ​​the separator 1. The groove-like depressions 11 can be located at the same point on the separator 1, at which point Figure 2 The surface structure 12 is shown. Figure 2 In this surface structure area, it is flat. Now, in Fig.14In this case, this area is embossed several times along the course of the surface structure 12. In these groove-like embossed recesses 11, each of which accommodates an elastomer coating 20, it is now also possible to apply a surface structure in the form of channel-like depressions 14 to the surface using a laser. Fig.15 In the cross section, these are indicated by interruptions in the surface at the bottom of the groove-shaped depression 11. Fig.15 There are also channel-shaped recesses 14 on the flanks of the central groove-shaped recess 11, which may be distorted in a perspective view due to their arrangement on an inclined surface, shown in this cross-section as a step shape. It is also conceivable to provide groove-shaped recesses 14 exclusively on the inner side of the flanks 13 of the groove-shaped recess 11. It is also conceivable to spray the elastomer coating 20 onto the inner edges of the fluid through-openings 4 and 5. In these cases, additional surface structures 12 can be applied to the inner edges of these through-openings.

[0072] It is also possible to provide a sealing element consisting of an elastomer coating 20 around the outer edge of the metal layer. In this case, a surface structure 12 can be used on the outer edge of the separator 1.

[0073] A method for manufacturing the above-mentioned separator 1 is also provided. The method comprises the following steps:

[0074] - generating a surface structure 12 in the metal layer 10 by irradiating the metal layer 10 with a laser, wherein the surface structure 12 comprises a plurality of channel-shaped depressions 14,

[0075] An elastomeric coating 20 is applied to the metal layer 10 at least in the region of the surface structure 12 , the elastomeric coating 20 being designed as a sealing element for sealing at least one region of the separator 1 .

[0076] The choice of the laser that can be used is not particularly limited. Any laser with sufficient power to generate a channel-shaped depression 14 with a suitable size and depth on the material of the metal layer 10 can be used. Preferably, a pulsed laser is used as the laser beam source in the present invention. Solid-state lasers have proven to be particularly suitable here.

[0077] For example, the laser can be a pulsed femtosecond, picosecond or nanosecond laser. Alternatively, a cw laser is also feasible. The recessed portion is then formed by melting the material of the metal layer 10. Due to the heat generated by the laser irradiation, very fine particles of metal or metal compound detach from the surface and vaporize. Then, by scanning the metal layer with a laser spot, a channel-shaped recessed portion 14 can be generated. The surface treatment by means of laser radiation advantageously does not destroy the mechanical properties of the metal layer material, nor does it cause an undesirable weakening of the strength of the metal layer.

[0078] For example, the laser system used here has a power of 20 to 200 watts, a wavelength of 1030 nm or 1062 nm, a focal length of 254 mm, and an ablation rate of 25 cm 2 / s. The following table lists the detailed parameters and example parameters of the laser:

[0079]

[0080] Of course, other lasers or laser parameters are also suitable for generating the surface structure 12 or the depressions 14 .

[0081] For example, compression molding, transfer molding or injection molding can be used to apply or spray the elastomeric coating.Such coating techniques are known in the art.

[0082] The method may include the following additional steps:

[0083] A PVD coating 30 is applied to the metal layer 10 , and an elastomeric coating 20 is applied to the metal layer 10 in the region of the PVD coating 30 .

[0084] Optionally, the metal layer 10 is first provided with a PVD coating 30. The metal layer is then subjected to a laser surface treatment at least in this region to generate the surface structure 12. Alternatively, the metal layer 10 is first subjected to a laser surface treatment to generate the surface structure 12 and then a PVD coating 30 is provided at least in this region.

[0085] The PVD coating may be applied to the metal layer 10 using conventional techniques. Therefore, a detailed description is not provided.

[0086] The above and Figure 1-10 The individual features of the partition 1 and the components shown may be claimed individually or in combination, but the combined features shall not contradict each other.

[0087] List of reference numerals:

[0088] 1 Partition

[0089] 2 Partitions

[0090] 3 Flow field

[0091] 4 Through opening for fluid

[0092] 5 Through opening for fluid

[0093] 6-channel architecture

[0094] 10 Metal Layer

[0095] 11 Groove-shaped convex and concave parts

[0096] 12 Surface structure

[0097] 13 The side wings of the groove-shaped convex and concave parts

[0098] 14 Channel-shaped depression

[0099] 16 Protrusion

[0100] 17 Intersection

[0101] 18 Microstructure

[0102] 19 Untreated surface

[0103] 20 Elastomer coating

[0104] 24 Overlapping Area

[0105] 30 PVD coating

[0106] 34 Discontinuity of PVD coating

[0107] 40 membrane electrode assembly

[0108] 41 Dielectric Diffusion Structure

[0109] 42 Battery Cell Frame

[0110] 43 Dielectric Diffusion Structure

[0111] 44 Battery Cell Frame

[0112] 45 Sealing layer

[0113] 46 Through opening for fluid

[0114] 47 Through opening for fluid

[0115] 48 Positioning holes

[0116] 49 Hydrogen distribution channel

[0117] 50 Hydrogen through opening

Claims

1. A separator (1) for an electrolyzer, comprising: a metal layer (10) having a segmented surface structure (12), wherein the surface structure (12) comprises a plurality of channel-shaped depressions (14) produced by laser surface treatment, an elastomeric coating (20) which is designed as a sealing element and which is applied to the metal layer (10) for sealing at least one region of the partition (1), Therein, the elastomer coating (20) is arranged at least in some areas on the surface structure (12).

2. The separator (1) according to claim 1, characterized in that Also included is a PVD coating (30) applied to the metal layer (10), wherein the elastomeric coating (20) is arranged at least in a region on the PVD coating (30).

3. The separator (1) according to claim 2, characterized in that The PVD coating (30) and the surface structure (12) overlap each other in an overlapping region (24), and the elastomeric coating (20) is arranged at least in the overlapping region (24) of the PVD coating (30) and the surface structure (12).

4. The separator (1) according to claim 3, characterized in that The PVD coating (30) is arranged on the surface structure (12), or The channel-shaped depressions (14) of the surface structure (12) at least partially form interruptions (34) in the PVD coating (30).

5. A separator (1) according to any one of the preceding claims, characterised in that The channel-shaped depressions (14) are linear, preferably straight, and in particular extend parallel to each other at least in sections, intersect and / or form a diamond-shaped grid structure, or wherein the depressions (14) are annular or spiral.

6. A separator (1) according to any one of the preceding claims, characterised in that The channel-shaped recessed portion (14) forms a macrostructure of the metal layer (10), wherein the metal layer (10) has a microstructure (18) within the channel-shaped recessed portion (14).

7. A separator (1) according to any one of the preceding claims, characterised in that The channel-shaped recess (14) is at least partially surrounded by a protrusion (16), which is formed on the corresponding circumferential edge of the channel-shaped recess (14), wherein the corresponding protrusion protrudes beyond the untreated surface (19) of the metal layer (10) and is in particular formed by material removed from the channel-shaped recess (14), and wherein the protrusion (16) preferably also has a macrostructure (18).

8. A separator (1) according to the preceding claim, characterised in that The height (h) of the protrusions (16) relative to the untreated surface (19) of the metal layer (30) is at most 30 μm.

9. A separator (1) according to any one of the preceding claims, It is characterized in that The depth of the channel-shaped depression (14) relative to the untreated surface of the metal layer (10) is at least 7 μm and / or at most 50 μm, and / or wherein the width of the channel-shaped depression (14) is at least 35 μm and / or at most 150 μm, and / or wherein the layer thickness of the PVD coating (30) is at least 100 nm and / or at most 1 μm, and / or Therein, the layer thickness of the elastomeric coating (20) is at least 10 μm and / or at most 3 mm.

10. A separator (1) according to any one of the preceding claims, characterised in that The distance between the parallel depressions (14) is at least 1.5 times the depression width and / or is at most 3 mm.

11. A separator (1) according to any one of the preceding claims, characterised in that The metal layer (10) is made of titanium or stainless steel.

12. A separator (1) according to any one of the preceding claims, when dependent on claim 2, characterised in that The PVD coating (30) comprises at least one layer, preferably two layers, and comprises or consists of at least one of the following materials: titanium, nickel, niobium, tantalum, carbon, platinum, zirconium, carbide, titanium nitride, titanium aluminum nitride and / or titanium carbonitride.

13. A separator (1) according to any one of the preceding claims, characterised in that The elastomer coating (20) comprises or consists of the following materials: FKM (fluororubber), silicone rubber or NBR rubber (nitrile rubber), PUR (polyurethane), NR (natural rubber), FFKM (perfluororubber), SBR (styrene-butadiene rubber), BR (butadiene rubber), FVMQ (fluorosilicone rubber), CSM (chlorosulfonated polyethylene), HNBR (hydrogenated nitrile rubber), ACM (acrylate rubber), AEM (acrylate-ethylene rubber), EPDM (ethylene-propylene-diene rubber), IIR (butyl rubber) or a mixture of the above substances.

14. A separator (1) according to any one of the preceding claims, characterised in that include: at least one through opening for the passage of reaction medium or product medium, and / or at least one flow field (3) for guiding the reaction medium or product medium along the partition (1), Therein, the elastomer coating (20) for sealing the through-opening or the flow field (3) is arranged around the through-opening and / or the flow field (3).

15. A method for manufacturing a separator (1) for an electrolyser, comprising the following steps: A surface structure (12) is produced in the metal layer (10) by irradiating the metal layer (10) with laser light, wherein the surface structure (12) comprises a plurality of channel-shaped depressions (14), An elastomeric coating (20) is applied to the metal layer (10), at least in the region of the surface structure (12), the elastomeric coating (20) being designed as a sealing element for sealing at least one region of the separator (1).

16. The method according to claim 15, characterized in that The method comprises the following additional steps: applying a PVD coating (30) to the metal layer (10), and applying the elastomeric coating (20) to the metal layer (10) in the region of the PVD coating (30).

17. The method (1) according to claim 16, characterized in that The surface structure (12) and the PVD coating (30) overlap one another in an overlap region (24), and the elastomeric coating (20) is applied at least to the overlap region (24).

18. The method according to claim 16 or 17, characterized in that The metal layer (10) is first provided with the PVD coating (30) and then subjected to a laser surface treatment at least in this region in order to produce the surface structure (12).

19. The method according to claim 16 or 17, characterized in that The metal layer (10) is first subjected to a laser surface treatment to produce the surface structure (12) and is then provided with the PVD coating (30) at least in the region.

20. A method according to any one of claims 15 to 19 for producing a separator (1) according to any one of claims 1 to 14.

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