Bipolar plate with at least one layer and at least one insert

Abstract

The invention relates to a bipolar plate for an electrochemical system, in particular an electrolyser, comprising at least one layer comprising at least one through-opening as an inlet or outlet for a fluid, a flow field with an electrochemically active region, and at least one insert arranged at the through-opening, the fluid guiding structure of the insert has a plurality of protrusions and is arranged between the flow field and the through-opening in the direction of the flow of the fluid, so that the fluid is guided from the through-opening through the fluid guiding structure between the protrusions to the flow field, or vice versa, the fluid guiding structure comprises a first region and a second region, the first region and the second region are arranged close to each other in the flowing direction of the fluid, and the protrusions in the first region and the second region are each provided with different distances from each other and / or are arranged at different densities and / or are in different shapes. Thus, the flow cross-section in the first region is smaller than the flow cross-section in the second region, and / or the flow resistance in the first region is greater than the flow resistance in the second region.

Description

Technical Field

[0001] The invention relates to a bipolar plate for an electrochemical system, comprising a layer and an insert. The invention also relates to an arrangement for an electrochemical system with a bipolar plate. The invention also relates to an electrochemical system comprising a plurality of stacked bipolar plates or a plurality of stacked arrangements. Background Art

[0002] The electrochemical system herein may be, for example, a fuel cell system, an electrochemical compressor, a redox flow battery, or an electrolyzer.

[0003] In general, an electrochemical system typically includes stacked individual electrochemical cells, each cell having multiple layers, including at least one bipolar plate and a membrane electrode assembly (MEA), each individual cell being defined by two adjacent bipolar plates. The stacked individual electrochemical cells may have two end plates, which press the individual electrochemical cells together and give the stack stability. In addition, the electrochemical individual cells may include a gas diffusion layer (GDL) or a porous transport layer (PTL), which are arranged between the bipolar plate and the membrane electrode assembly. The bipolar plate can perform several functions: indirect electrical contact of the electrodes of the membrane electrode assembly (MEA); separation of a medium, such as water, oxygen or hydrogen; and electrical connection of adjacent electrochemical individual cells.

[0004] The bipolar plate comprises at least one through opening (port) as an inlet or outlet for a fluid to pass through the bipolar plate; a flow field with an electrochemically active area; and a fluid guiding structure located therebetween for guiding the fluid between the through opening and the flow field. In particular, the fluid guiding structure may form a fluid connection between the through opening and the flow field. The fluid guiding structure is usually formed by protrusions of several bipolar plates, so that there are corresponding passages between adjacent protrusions, allowing the fluid to flow.

[0005] For example, bipolar plates can be single-layer or multi-layer. Bipolar plates in fuel cell cells are usually double-layered so that the cooling fluid can flow between two separate layers, while bipolar plates in electrolyzers are usually single-layered. The bipolar plate itself and each layer of the bipolar plate can be considered a separator plate because it causes separation of the media.

[0006] In addition to the aforementioned bipolar plates, MEA, GDL or PTL, other layers may also be provided. Cell frames and / or cell seals may be installed between adjacent bipolar plates to seal the cells. Stacked individual electrochemical cells must be sealed from the external space because the fluid or medium inside the individual electrochemical cells is usually under overpressure compared to the external pressure. Depending on the type of electrochemical system, the fluid may include, for example, hydrogen, air (oxygen), water, a cooling medium and / or a mixture of (one or more) of these. In an electrolyzer, the pressure difference between the environment and the inside of the electrochemical cell may even exceed 20 bar. For example, the pressure on the generation side, such as the H2 side, may be up to 40 bar, while the pressure on the reactant side, such as the H2O side, may be only up to 2 bar. Therefore, it is important to seal the flow field of the fluid from the environment and the electrochemical system. To this end, particularly in electrolyzer applications, the electrochemical system may have at least one cell frame that travels around the outer edge of the individual electrochemical cell for each of the individual electrochemical cells, thereby achieving a sealing effect. Additionally, the electrochemical system may include one or more sealing layers or cell seals for each of the individual electrochemical cells to enhance the sealing effect.

[0007] However, this conventional electrochemical system has the following problems. The layer placed on the bipolar plate (i.e., the battery cell frame or battery cell seal) passes through the passage of the fluid guiding structure, and there is no support from the bipolar plate in this area. When the electrochemical battery cell is pressed, the layer in this area cannot transmit enough pressure or compression. On the other hand, in the case of a single-layer bipolar plate, this area of ​​the fluid guiding structure must be passed through, because the bipolar plate, in particular the anode side and the cathode side of the electrolyzer are made of a single sheet, that is, during stacking or assembly, they are basically placed concentrically on top of each other, and the force required for sealing can only be transmitted via the strength and / or stiffness of the battery cell frame and / or the battery cell seal itself. Due to the need for electrical insulation, the battery cell frame and / or the battery cell seal are usually made of plastic, but the plastic is usually not strong and / or stiff enough, which may cause problems when squeezing the stack. This is because the direction of the passage may be deformed at such a point, where the battery cell frame and / or the battery cell seal travels over the fluid guiding structure. The deformation usually causes the seal to come against the membrane and the cell frame and / or the cell seal to lose pressure. If a medium is introduced into the port, the medium then exits at the seal. The loss of pressure results in a leak, which can cause a short circuit, or even a complete failure of the system.

[0008] In order to solve this problem, support elements are sometimes used in the prior art, which are arranged as sealing support bridges formed into the bipolar plates across the fluid-conducting structures, see, for example, publications DE 10 2014 202 775 A1 and DE 10 2020 215 014 A1.

[0009] There is a continuing need to further improve the sealing of the system in order to prevent or at least reduce pressure loss or fluid loss and / or to improve the safety of the system. Summary of the invention

[0010] It is therefore an object of the present invention to provide a bipolar plate, an arrangement comprising a bipolar plate, and an electrochemical system comprising a plurality of stacked bipolar plates or a plurality of stacked arrangements, which at least partially solve the above-mentioned problems.

[0011] This problem is solved by the subject matter of the independent claims.

[0012] According to a first aspect, a bipolar plate for an electrochemical system, in particular for an electrolyzer, is provided. The bipolar plate comprises at least one layer and at least one insert. The layer comprises at least one through-opening as an inlet or outlet for a fluid, and a flow field with an electrochemically active area.

[0013] The insert is arranged at the through opening and includes a fluid guiding structure for guiding the fluid. The fluid guiding structure of the insert has a plurality of protrusions and is arranged between the flow field and the through opening in the flow direction of the fluid, thereby guiding the fluid or enabling the fluid to flow from the through opening to the flow field through the fluid guiding structure between the protrusions, or vice versa.

[0014] Here, the fluid guiding structure has a first area and a second area, which are arranged close to each other in the flow direction of the fluid, and the protrusions in the first area and the second area each have different distances from each other, and / or are arranged with different densities, and / or are designed to have different shapes, so that the flow cross-section in the first area is smaller than the flow cross-section in the second area, and / or the flow resistance in the first area is greater than the flow resistance in the second area.

[0015] Due to the different flow cross sections or flow resistances in two regions of the fluid-conducting structure of the insert, the fluid volume and the fluid velocity can be controlled locally, which can have a positive influence on the tightness of the system.

[0016] In addition, the flow can be optimized, which leads to a more uniform distribution of the fluid along the bipolar plate, which in turn has a positive effect on the sealing of the system. It has been found that the fluid flow is generally not constant with the same flow cross section or flow resistance along the fluid guiding structure. This is usually due to the upstream or downstream elements of the fluid guiding structure. For example, if the through opening is rectangular, the flow rate at the corner area of ​​the through opening is generally lower than at the elongated edge of the through opening due to the increased flow resistance in these areas. Therefore, the flow of the fluid can be uniformed by locally increasing the flow resistance of the fluid guiding structure at the elongated edge of the through opening. By making the fluid distribution uniform, the sealing elements of the system can then be simplified and standardized. To compare the two areas, the area of ​​the fluid guiding structure should be selected so that they have the same lateral width transverse to the flow direction.

[0017] The fluid guiding structure of the insert usually has several passages, each of which extends between adjacent protrusions and is designed to guide the fluid along the layer. It can be provided that at least two of the passages have different flow cross sections and / or different flow resistances and / or different widths and / or different lengths. Differently designed passages can be provided in a first area and a second area of ​​the fluid guiding structure of the insert. For example, the flow cross sections of the passages can differ in their shape and / or size.

[0018] The passage can have a first plurality of passages and a second plurality of passages, wherein the first plurality of passages and the second plurality of passages differ in their flow cross-sections, widths and / or lengths. Therefore, different groups of passages can be provided, each with different flow characteristics. Rather than being grouped individually, the flow characteristics can also be continuously changed, for example along an edge of the through opening. For example, the flow cross-section and / or width of the passage can be changed in a direction perpendicular to the flow direction of the fluid, and / or remain unchanged in the flow direction of the fluid and preferably decrease towards the center of the fluid guiding structure.

[0019] The protrusions may form depressions on a first side of the insert facing away from the layer, wherein the depressions in the first and second regions each have the same diameter and / or different diameters and / or the same width and / or different widths and / or the same cross-sectional content and / or different cross-sectional content and / or the same cross-sectional shape and / or different cross-sectional shapes and / or the same length and / or different lengths. It is therefore clear that several parameters may be varied in order to achieve desired different flow characteristics in the first and second regions.

[0020] In particular, at least one, several or all of the depressions may be channel-shaped. In this case, the protrusions are web-shaped. Channel-shaped or web-shaped does not necessarily mean that the structure is straight; curved passages or webs are also possible. At least two or all of the protrusions or depressions typically extend substantially parallel to each other. In one embodiment, the fluid guiding structure extends in a wave shape.

[0021] In some embodiments, at least one, several or all of the protrusions are block-shaped. It is possible that the density of block-shaped protrusions in the first area is greater than in the second area. The density of protrusions or the density of block-shaped protrusions should be understood to mean the relative proportion of the area covered by the protrusions, not necessarily just the number. The protrusions also differ in size. Combinations of differently designed protrusions, such as block-shaped protrusions and strip-shaped protrusions, are also possible.

[0022] The insert is usually firmly connected to the layer, preferably by means of a material connection. For example, welding or bonding joints can be considered. Mechanical connections are also possible, which are preferably provided outside the section of the insert with the protrusion.

[0023] Sometimes, the insert in the area outside the fluid guiding structure is designed essentially as a flat surface. The protrusion of the insert usually faces the layer and in particular rests on the layer. The layer can have an essentially flat surface in the area of ​​the fluid guiding structure of the insert. In particular, the protrusion of the insert can rest on the flat surface of the layer. In addition, the insert can be arranged around the through opening and in particular at least partially enclose the through opening. In addition, the flow field can be at a distance from the fluid guiding structure or directly adjacent to the fluid guiding structure.

[0024] It can be provided that the through opening has an edge, wherein the longitudinal direction of the first passage or protrusion is aligned substantially perpendicular to the closest area of ​​the edge and / or the longitudinal direction of the second passage or protrusion is aligned at an angle between 0° and 90° to the closest area of ​​the edge.

[0025] The layer usually has at least two through openings arranged close to each other, and the two through openings are separated from each other by an area of ​​the layer. In certain embodiments, the insert is arranged at least two through openings and has a fluid guiding structure for the two through openings. It can be set that the two through openings are designed as fluid inlets, or the two through openings are designed as fluid outlets, in particular for the same fluid. The insert can extend further between the at least two through openings. Optionally, the insert can extend along the edge of the two through openings in a frame-shaped, 8-shaped or glasses-shaped shape.

[0026] In some embodiments, the layer has a convex arrangement molded into the layer, the convex arrangement partially surrounding at least one through opening. This may refer to a region of the through opening that is located adjacent to the fluid guiding structure. The insert may be arranged on the convex arrangement, in particular in a region outside the fluid guiding structure. It is possible that the convex arrangement runs between the through openings. The convex arrangement may be designed as a semi-convex or a full convex, and the height of the convex arrangement and the height of the protrusion may match each other, for example have the same height. In some embodiments, the insert may be arranged on the top of the convex of the convex arrangement.

[0027] The flow field generally has a channel structure for guiding the reaction medium or the production medium along the separation plate. The lip top of the lip arrangement and the channel structure of the flow field can be aligned in the same direction, preferably perpendicular to the plate plane of the layer, and formed into the separation plate, for example by embossing, such as roller embossing of the separation plate, impact embossing, hydroforming and / or deep drawing.

[0028] The bipolar plate may have an elastomeric seal for sealing the through-opening, which is arranged on a first side of the insert facing away from the layer. The elastomeric seal may be molded onto the insert and / or the layer. For example, the elastomeric seal is designed as an elastomeric bead or coating and is arranged on the layer and / or the insert. In particular, the elastomeric seal may be applied continuously to the insert and the layer. It may also be used to connect the insert and the layer as an alternative to or in addition to another connection between the two elements.

[0029] As already described above, the protrusion on the first side of the insert may form a depression, such as a channel or a recess. In this case, the elastomeric seal may be arranged at least in the depression. On the rear side of the bipolar plate, i.e. the side of the bipolar plate facing away from the insert, the convex edge arrangement may form a receptacle for a further sealing element, for example an elastomeric sealing element. The depression of the insert may also be at least partially or completely filled with an elastomer, thus forming a contact surface or a stop for the next seal on the side facing away from the bipolar plate.

[0030] The thickness of the insert is typically no more than 70%, preferably no more than 30%, of the thickness of the layer.Due to the reduced thickness of the insert, the protrusions and vias can be more finely designed than if they were formed in the layer.

[0031] It can be provided that the insert is made of metal, for example titanium or stainless steel, and / or that the layer is made of metal, for example titanium or stainless steel, in sections, at least mainly or completely. Other materials, such as alloys, are also possible, and the invention is not limited to a specific material of the layer. If the insert is made of metal, it can be produced by stamping, deep drawing or hydroforming. As an option, the insert and the layer can be made of the same or different materials. Additionally or alternatively, the insert can be formed separately from the layer and made from a different material blank than the layer. The independent manufacturing option increases the design freedom of the two components.

[0032] According to another aspect, a bipolar plate for an electrochemical system, in particular an electrolyzer, is proposed. The bipolar plate comprises at least one layer and at least one insert. The layer comprises at least one through opening as an inlet or outlet for a fluid, and a flow field with an electrochemically active area. Here, the insert is arranged at the through opening and comprises a fluid guiding structure for guiding the fluid. The fluid guiding structure of the insert is arranged between the flow field and the through opening in the flow direction of the fluid, thereby guiding the fluid or causing the fluid to be guided to or flow to the flow field from the through opening through the fluid guiding structure, or vice versa. The fluid guiding structure of the insert has a plurality of protrusions and passages, and each passage extends between adjacent protrusions and is designed to guide the fluid along the layer. At least two of the passages have different flow cross sections and / or different flow resistances and / or different widths and / or different lengths.

[0033] The features described in connection with the bipolar plate according to the first aspect may be used alone or in combination with the bipolar plate of the second aspect without exceeding the scope of this document.

[0034] According to a third aspect, an arrangement for an electrochemical system is provided. The arrangement comprises a bipolar plate according to any of the two above-mentioned aspects, wherein the arrangement comprises a first cell frame and / or a membrane electrode unit and / or a second cell frame, and wherein an insert is arranged between the first cell frame and the layer and / or between the membrane electrode unit and the layer and / or between the second cell frame and the layer.

[0035] In one embodiment, the insert can be designed to support the first cell frame and / or the membrane electrode unit and / or the second cell frame, in particular in the region of the flow-conducting structure. The cell frame can be made of plastic and designed to seal regions of the bipolar plate, such as flow fields and / or through-openings.

[0036] According to a fourth aspect of the present invention, an electrochemical system is provided, comprising a plurality of stacked bipolar plates of the above type and / or a plurality of stacked arrangements of the above type.

[0037] In one embodiment where the electrochemical system is an electrolyzer, water may be the reaction medium and hydrogen and oxygen are the production medium. In a fuel cell monomer system, hydrogen and oxygen or air are typically the reaction medium and water is the production medium. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Examples of embodiments of bipolar plates, arrangements and electrochemical systems are shown in the accompanying drawings and explained in more detail in the description below. In the drawings:

[0039] Figure 1 is a top view of a bipolar plate according to one embodiment;

[0040] Figure 2 is based on Figure 1 A three-dimensional view of a section D of a bipolar plate;

[0041] Figure 3 is based on Figure 1 A three-dimensional image of a region of a bipolar plate;

[0042] Figure 4 It passes through Figure 3 A cross section of a partial area A of a bipolar plate;

[0043] Figure 5 It passes through Figure 3 A cross section of another partial region B of the bipolar plate;

[0044] Figure 6 It passes through Figure 3 A cross section of another partial region C of the bipolar plate;

[0045] Figure 7 is based on Figure 1 A three-dimensional image of a region of a bipolar plate;

[0046] Figure 8 is along Figure 7 A perspective view of a section taken along line AA in FIG.

[0047] Fig. 9 is a perspective view of a region of a bipolar plate according to another embodiment;

[0048] Fig.10 is a top view of a region of an insert according to a further embodiment;

[0049] Fig.11 is a perspective view of a region of a bipolar plate according to another embodiment;

[0050] Fig.12 is a top view of another insert and a cross-sectional view along line BB;

[0051] Fig.13 yes Fig.12A perspective view of an insert and a perspective view of a section along line CC;

[0052] Fig.14 is a cross section through an arrangement having a bipolar plate, an insert and a seal; and

[0053] Fig.15 is an exploded view of a single battery cell of an electrolyzer with conventional bipolar plates according to the prior art.

[0054] Here and hereinafter, features which occur repeatedly in different figures are in each case denoted by the same or similar reference symbols. DETAILED DESCRIPTION

[0055] Fig.15 An exploded view of an electrochemical single cell 100 according to the prior art is shown, and in the example shown, the single cell 100 is part of an electrolyzer. An electrolyzer typically includes a large number of individual cells 100 stacked. The single cell 100 shown includes two bipolar plates 1 and 1', two cell frames 42 and 44, a sealing layer 45, and a membrane electrode assembly 40 with dielectric diffusion structures 41 and 43. An elastomeric seal can also be used instead of the sealing layer 45, for example, an elastomeric seal is used on the surface of the bipolar plate 1' facing the cell frame 44; the cell frame 44 will then be directly adjacent to the bipolar plate 1'. For example, the dielectric diffusion structure 43 includes layered carbon fibers, and the dielectric diffusion structure 41 includes a metal, such as titanium. The bipolar plate 1 is arranged here, for example, on the anode side of the single cell 100. In the embodiment shown, the bipolar plate 1' is arranged on the cathode side of the single cell 100. The individual layers are pressed together to form a single cell 100. The individual layers each have fluid passages 46 , 47 , 50 arranged in register stacked relation to one another, inward and outward passages for water, oxygen and hydrogen, and positioning holes 48 .

[0056] By projecting the cell frame 44 onto the separator plate 1', the flow field of the bipolar plate 1' is defined in the area enclosed by the cell frame 44. By projecting the cell frame 42 onto the bipolar plate 1, the flow field 8 of the bipolar plate 1 is defined in the area enclosed by the cell frame 42. The cell frame 42 has distribution channels (not shown) for distributing the water fed in. The through openings 46 and 47 are in fluid communication with the flow field 8, so that the medium can be conducted from the through opening 46 to the flow field 8 or from the flow field 8 to the through opening 47. When an electric potential is applied, hydrogen (or oxygen) in the electrolyzer can be generated from the supplied water. This hydrogen can be discharged through the distribution channel 49 in the cell frame 44. It can then leave the cell through the through opening 50. Although Fig.15The bipolar plates 1, 1' shown in FIG. 1 have a rounded outer contour, but other shapes are also possible. For example, the bipolar plates 1, 1' may have a rectangular outer contour, possibly with rounded corners (see also FIG. 1 ). Figure 1 ).

[0057] As already indicated above, the pressure difference between the environment and the inside of the electrochemical cell 100 can exceed 20 bar. The pressure on the production side, e.g. the H2 side, is typically at most 40 bar, while the pressure on the reactant side, e.g. the H2O side, can be only at most 2 bar. Therefore, it is important to seal individual areas of the bipolar plates 1, 1' from other areas of the bipolar plates and / or the environment.

[0058] Figure 1 A highly schematic bipolar plate 1 according to the invention is shown in a top view. The bipolar plate has at least one layer 2 and at least one insert 10 .

[0059] The layer 2 is usually designed as a sheet metal layer and has a plurality of through openings 3, 4, 5, 6, and each of the through openings 4 and 6 is designed as an inlet for a fluid, and each of the through openings 3 and 5 is designed as an outlet for a fluid, and water, hydrogen or oxygen can be considered as fluids, for example. The layer 2 also has a flow field 8 with an electrochemically active area. The flow field 8 has a channel structure for guiding a fluid, such as a reaction medium or a production medium, along the bipolar plate 1. The channel structure of the flow field 8 is usually, but not necessarily, designed as parallel protrusions.

[0060] The insert 10 is arranged between the flow field 8 and the through-openings 3, 4. The insert 10 is arranged at the through-openings 3, 4 and has a fluid guiding structure 12 for guiding a fluid.

[0061] The insert 10 and the layer 2 may be made of the same or different materials. For example, metals such as titanium or stainless steel are possible. Other materials such as alloys are also possible. Additionally or alternatively, the insert 10 may be formed separately from the layer 2 and made from a different material blank than the layer 2. The thickness of the insert 10 may be at most 70%, preferably at most 30%, of the thickness of the layer 2. Furthermore, the insert 10 may be firmly connected to the layer 2, preferably by a material joint connection. In this way, the insert 10 may be connected to the layer 2 by a welded joint or an adhesive joint. Figure 1-9 As shown in , the protrusions 14 and 24 of the insert 10 face the layer 2 and rest on the layer 2. The layer 2 may have a substantially flat surface in the region of the fluid guiding structure 12 of the insert 10, and the protrusions 14, 24 of the insert 10 rest on the flat surface of the layer 2.

[0062] exist Figure 2-9In the embodiment of the present invention, the insert 10 is arranged at the through-openings 3, 4 and further arranged to surround the through-openings 3, 4. The insert 10 typically encloses the through-openings 3, 4 at least partially, preferably completely.

[0063] In order to explain the structure of the insert 10, the following also describes Figure 2-10 , these figures show various parts and aspects of the insert 10.

[0064] The fluid guiding structure 12 of the insert 10 has several protrusions 14, 24, 34 and is arranged in the flow direction of the fluid between the flow field 8 and the through-openings 3, 4. This allows the fluid to flow from the through-opening 4 as an inlet through the protrusions 14, 24, 34 of the fluid guiding structure 12 to the flow field 8. Furthermore, the fluid can flow from the flow field 8 through the fluid guiding structure 12 and between the protrusions 14, 24, 34 of the insert 10 to the through-opening 3 as an outlet.

[0065] The fluid guiding structure 12 comprises a first region 18 and a second region 19, which are arranged close to each other in the flow direction of the fluid. Optionally, a third region 21 may also be provided, which is arranged close to the first region 18 or the second region 19 in the flow direction of the fluid. The regions 18, 19, 21 extend from one end of the fluid guiding structure 12 facing the through openings 3, 4 to one end of the fluid guiding structure 12 facing the flow field 8 in the flow direction of the fluid. The above-mentioned regions 18, 19, 21 are different from each other in terms of their flow cross sections and / or flow resistances.

[0066] The protrusions 14 and 24 have different distances from each other and / or are arranged at different densities, so that the flow cross section in the first region 18 is smaller than the flow cross section in the second region 19, and / or the flow resistance in the first region 18 is greater than the flow resistance in the second region 19. In addition, the protrusions 24 and 34 can each have different distances from each other and / or be arranged at different densities, so that the flow cross section in the second region 19 is smaller than the flow cross section in the third region 21, and / or the flow resistance in the second region 19 is greater than the flow resistance in the third region 21. In the illustrated embodiment example, the protrusions 14, 24, 34 are designed to have the same shape in the regions 18, 19, 21. Alternatively, they can also be designed to have different shapes in each of the regions 18, 19, 21.

[0067] Furthermore, the fluid guiding structure 12 of the insert 10 has a plurality of passages 20, 30, 40, each extending between adjacent protrusions 14, 24, 34 and configured to guide a fluid along the layer 2. The passages 20 in the first region 18, the passages 30 in the second region 19 and the passages 40 in the third region 21 have different flow cross sections and / or different flow resistances. In particular, the flow cross section of the passage 40 is greater than the flow cross section of the passage 30, and the flow cross section of the passage 30 is in turn greater than the flow cross section of the passage 20. Furthermore, the passages 20, 30, 40 in the respective regions 18, 19, 21 each have a different width and / or a different length.

[0068] The flow behavior of the fluid can be specifically influenced by using passages 20, 30, 40 or protrusions 14, 24, 34 of the fluid guiding structure 12, which vary in terms of flow resistance or flow cross section. Thus, the fluid flow resistance at the through-openings 3, 4 generally decreases from the corner area 39 toward the center of the through-opening, or increases from the center toward the corner area 39. If the flow resistance of the fluid guiding structure 12 in the area adjacent to the center of the through-openings 3, 4, i.e. in the first area 18, is greater than in the second area 19 and the third area 21, the flow distribution and the fluid flowing through the through-openings 3, 4 can be made more uniform.

[0069] The projections 14, 24, 34 form recesses 15, 25, 35 on the first side 11 of the insert 10 facing away from the layer 2, wherein the recesses 15 in the first region 18, the recesses 25 in the second region 19 and the recesses 35 in the third region 21 each have the same diameter, the same width, the same cross-sectional content and the same cross-sectional shape. Alternatively, the dimensions in the regions 18, 19, 21 can also deviate from one another. Thus, the passages 20, 30, 40 form webs 16, 26, 36 designed to be complementary in shape on the first side 11 of the insert 10 facing away from the layer 2, which webs have different widths and / or lengths in the regions 18, 19, 21.

[0070] In some embodiments, the flow cross-section and / or width of passages 20, 30, 40 varies continuously in a direction perpendicular to the flow direction of the fluid, and preferably decreases toward the center of the fluid guiding structure 12 or the through openings 3, 4, while remaining substantially constant in the flow direction of the fluid.

[0071] Figure 1-9 and Fig.11The projections 14, 24, 34 are all designed as elongated webs. Therefore, the depressions 15, 25, 35 associated with the projections 14, 24, 34 are designed as channel-shaped grooves. The fluid guiding structure 12 extends along the through-openings 3, 4 in an undulating manner via the web-shaped projections 14, 24, 34 and the channels 20, 30, 40 located between them. However, projections or depressions designed in different shapes are also conceivable.

[0072] Fig.10 An alternative embodiment of the insert 10 is shown in which the protrusions 14 and 24 are designed as small blocks formed into the insert. Fig.10 A top view of the side of the insert facing the layer 2 and arranged on the layer 2 is shown. The density of the protrusions 14 in the first region 18 of the insert 10 is higher than the density of the protrusions 24 in the second region 19 of the insert. In particular, this is achieved by a large number of nuggets. Additionally or alternatively, the nuggets in the first region 18 can also be larger than the nuggets in the second region, with the result that the flow resistance in the first region 18 is greater than the flow resistance in the second region 19, or the flow cross section in the second region 19 is greater than the flow cross section in the first region 18.

[0073] The channel structure of the flow field 8 is usually, but not necessarily, designed as parallel protrusions, the length of which in the flow direction of the fluid is usually significantly longer than the length of the protrusions 14, 24, 34 of the fluid guiding structure 12, for example at least 5 times longer. The layer 2 usually has a convex edge arrangement 9 formed into the sheet material of the layer 2, which partially surrounds the through openings 3, 4, that is, in the area outside the fluid guiding structure 12. The convex edge arrangement 9 and the fluid guiding structure 12 together surround the through openings 3, 4. The convex edge arrangement 9 and the channel structure of the flow field 8 are generally formed into the layer 2 by embossing, deep drawing or hydraulic forming, and are aligned in the same direction, preferably perpendicular to the plane of the layer 2. The convex edge arrangement 9 and the channel structure of the flow field 8 are therefore an integral part of the layer 2. The plane of the layer 2 is an extended flat surface without embossing; for example, the plane of the layer 2 can extend adjacent to the insert 10.

[0074] exist Figure 1 , Figure 3 and Fig. 9 , the through-openings 3, 4 are rectangular with rounded corners. The through-openings 3, 4 have an edge 7 which delimits an edge region 17 of the layer 2 around the through-openings 3, 4, and the longitudinal direction of the passages 20, 30 is oriented substantially perpendicular to the edge 7 or to the closest region of the edge 7. In a corner region 39 of the through-openings 3, 4, the longitudinal direction of the passages 30, 40 is aligned at an angle of 0° to 90° to the closest region of the edge 7. The fluid guiding structure 12 adjoins the through-openings 3, 4, more precisely to the edge region 17 of the layer 2.

[0075] exist Figure 1 In the embodiment of FIG. 4 , a total of four inserts 10 are shown, each of which is arranged at a through-opening 3 , 4 of a layer. The number of inserts 10 may be less than the number of through-openings 3 , 4 . Figure 3 and Fig. 9 In the embodiment example, at least two through openings 3, 4 arranged close to or adjacent to each other share an insert 10. In this case, a single insert 10 is arranged at at least two through openings 3, 4, and the insert has a fluid guide structure 12 for the two through openings 3, 4. It can be provided that the insert 10 extends between the at least two through openings 3, 4. Figure 3 and Fig. 9 In the embodiment, the insert 10 extends along the edges 7 of the two through openings 3 in a frame-like, figure-of-eight-shaped or glasses-shaped manner.

[0076] The rim arrangement 9 can run between two adjacent through-openings 3, 4. The term "rim" or "rim arrangement" 9 is used here in particular to describe the shape of the rim; it can be associated with an element having only a minimal or a significant elastic component, the elastic component depending in particular on the selected material and its material strength. For example, the insert 10 can be arranged on top of the rim of the rim arrangement 9. The end face of the rim arrangement 9 faces the third area 21 of the fluid guiding structure 12, wherein a fluid channel 37 is formed between the end face of the rim arrangement 9 and the protrusion 34 of the third area 21, the fluid channel 37 extending at a certain angle to the protrusion 34, for example perpendicular to the protrusion 34. The fluid channel 37 connects the through-openings 3, 4 to the passage 40 fluid in the third area 21 of the fluid guiding structure 12. In Figure 7 In the figure, the direction of fluid flow is indicated by arrows. Figure 7 It can be seen that the fluid channels 37 and passages 40 in the third region 21 enable a fluid flow between the through-openings 3 , 4 in the region of the layer 2 , and thus also between the through-openings 3 , 4 and the flow field 8 . Figure 8 It is also shown that the protrusions 34 and passages 40 in the third region 21 are longer than the protrusions 24 and passages 30 in the second region 19 .

[0077] Typically, the bipolar plate 1 comprises an elastomeric seal 22 for sealing the through openings 3, 4, which is arranged on the first side 11 of the insert 10 facing away from the layer 2. The elastomeric seal 22 can preferably be arranged in the recesses 15, 25 of the insert 10, or can be molded onto the insert 10. The elastomeric seal 22 can be designed so that it forms a flat surface on the side facing away from the layer 2. Fig.11As shown in the figure, the elastomeric seal 22 can only extend over a section of the first, second and possibly third area, in particular with respect to the flow direction of the fluid. However, it can also cover the entire area with the protrusions 14, 24, 34, or extend beyond this area. The combination of the insert 10 with the elastomeric seal 22 allows the overlying components in this area of ​​the fluid guiding structure 12 to be supported, resulting in improved sealing to mating components, such as MEAs, battery cell frames, etc. For this purpose, an advantageous design of the insert 10 is Figure 12 to Figure 14 The embodiment of the insert 10 shown in FIG. 1 has recesses 15 and 25 completely filled with an elastomer 23. The elastomer 23 renders the insert 10 incompressible or increases the incompressibility of the insert 10, so that the insert 10 is suitable as a stop element for an overlying element.

[0078] Fig.12 In the figure, the insert is shown from the second side 13, but from Fig.12 In the cross section of FIG. 1 , the elastomer 23 injected into the recesses 15, 25 from the first side 11 can be seen. In this case, the insert 10 is completely, usually practically completely, filled with the elastomer 23 in the recesses 15 and 25, which means that it can, for example, form a contact surface or a stop for a further elastomer seal 22 or 27. The insert 10 can have an edge section 31, which encloses the recesses 15, 25 at least in a section, so that the recesses 15, 25 extend in the area defined by the edge section 31, for example in the shape of a groove or a cavity. The elastomer 23 can be flush with the edge section 31 and arranged in the recesses 15, 25 and sometimes also on the webs 16, 26. The edge section 31 can therefore be slightly higher than the webs 16, 26, or the webs 16, 26 can be convexly pressed slightly below the edge section 31. Other types of seals around the through-openings are also possible, for example the bipolar plates 1 in the layer 2 can also be provided with a ridge seal around the through-openings. In order to act as a stop, it is advantageous if the elastomer 23 is flush with the edge or edge section 31 of the recess 15, 25. The elastomer 23 should neither protrude nor be too low. This ensures the main sealing function and prolongs the service life.

[0079] On the rear side of the bipolar plate 1 , ie the side of the bipolar plate 1 facing away from the insert 10 , the lip arrangement 9 can form a receptacle for a further sealing element, for example an elastomeric sealing element.

[0080] like Fig.15As shown in , the bipolar plate 1 can be part of an arrangement of an applied electrochemical system. In addition to the bipolar plate 1, the arrangement includes a first battery cell frame 42 and / or a membrane electrode unit 40 and / or a second battery cell frame 44. The insert 10 is then arranged between the first battery cell frame 42 and the layer 2 and / or between the membrane electrode unit 40 and the layer 2 and / or between the second battery cell frame 44 and the layer 2. The electrochemical system according to the present disclosure then includes a plurality of stacked bipolar plates 1 and / or a plurality of stacked arrangements.

[0081] List of reference numerals:

[0082] 1 Bipolar Plate

[0083] 1' Bipolar Plate

[0084] 2 layers

[0085] 3 Through opening

[0086] 4 Through opening

[0087] 5 Through opening

[0088] 6 Through opening

[0089] 7 Edge

[0090] 8 Flow field

[0091] 9. Convex edge arrangement

[0092] 10 Insert

[0093] 11 First side

[0094] 12 Fluid guiding structure

[0095] 13 Second side

[0096] 14 Protrusions in the first area

[0097] 15 Depression in the first area

[0098] 16 Web in first region

[0099] 17 Marginal Area

[0100] 18 First Area

[0101] 19 Second Area

[0102] 20 Passage in the first area

[0103] 21 Third Area

[0104] 22 Elastomer seals

[0105] 23 Elastomer filler

[0106] 24 Protrusions in the second area

[0107] 25 Depression in the second area

[0108] 26 Web in the second region

[0109] 27 Seals

[0110] 28 Elastomer sealing element

[0111] 30 Passage in the second area

[0112] 31 Edge

[0113] 34 Protrusions in the third area

[0114] 35 Depression in the third area

[0115] 36 Web in the third region

[0116] 37 Fluid Channel

[0117] 39 Corner area

[0118] 40 Passage in the third area

[0119] 41 Dielectric Diffusion Structure

[0120] 42 Battery Cell Frame

[0121] 43 Dielectric Diffusion Structure

[0122] 44 Battery Cell Frame

[0123] 45 Sealing layer

[0124] 46 Through opening for fluid

[0125] 47 Through opening for fluid

[0126] 48 Positioning holes

[0127] 49 Hydrogen distribution channel

[0128] 50 Hydrogen penetration opening

[0129] 60 membrane electrode assembly

[0130] 100 electrochemical cells

Claims

1. A bipolar plate (1) for an electrochemical system, in particular an electrolyser, comprising at least one layer (2) and at least one insert (10), the layer (2) comprising: - at least one through opening (3, 4) which serves as an inlet or outlet for a fluid, - a flow field (8) with an electrochemically active area, The insert (10) is arranged at the through opening (3, 4) and comprises a fluid guiding structure (12) for guiding a fluid. The fluid guiding structure (12) of the insert (10) has a plurality of protrusions (14, 24) and is arranged between the flow field (8) and the through openings (3, 4) in the direction of flow of the fluid, so that the fluid is guided from the through openings (3, 4) through the fluid guiding structure (12) between the protrusions (14, 24) to the flow field (8), or vice versa. The fluid guiding structure (12) comprises a first region (18) and a second region (19), wherein the first region (18) and the second region (19) are arranged close to each other in the flow direction of the fluid. The protrusions (14, 24) in the first region (18) and the second region (19) have different distances from each other, and / or are arranged at different densities, and / or have different shapes, so that the flow cross section in the first region (18) is smaller than the flow cross section in the second region (19), and / or the flow resistance in the first region (18) is greater than the flow resistance in the second region (19).

2. The bipolar plate according to claim 1, characterized in that: The fluid guiding structure (12) of the insert (10) has a plurality of passages (20, 30), each of which extends between adjacent protrusions (14, 24) and is designed to guide fluid along the layer (2), wherein at least two of the passages (20, 30) have different flow cross-sections and / or different flow resistances and / or different widths and / or different lengths.

3. The bipolar plate (1) according to the preceding claim, characterized in that The flow cross section and / or width of the passage (20, 30) changes in a direction perpendicular to the flow direction of the fluid and / or remains constant in the flow direction of the fluid and preferably decreases toward the center of the fluid guiding structure (12).

4. The bipolar plate (1) according to any one of the preceding claims, characterized in that The protrusions (14, 24) form recesses (15, 25), in particular channel-shaped grooves, on a first side (11) of the insert (10) facing away from the layer (2), wherein the recesses (15, 25) in the first area (18) and in the second area (19) each have the same diameter and / or different diameters and / or the same width and / or different widths and / or the same cross-sectional content and / or different cross-sectional contents and / or the same cross-sectional shape and / or different cross-sectional shapes and / or the same length and / or different lengths.

5. The bipolar plate (1) according to any one of the preceding claims, characterized in that The protrusions (14, 24) are block-shaped, wherein the density of the block-shaped protrusions (14, 24) in the first region (18) is greater than that in the second region (19).

6. The bipolar plate (1) according to any one of the preceding claims, characterized in that The insert (10) is firmly connected to the layer (2), preferably by a material joint connection.

7. The bipolar plate (1) according to any one of the preceding claims, characterized in that The protrusions (14, 24) of the insert (10) face the layer (2) and, in particular, rest on the layer (2).

8. The bipolar plate (1) according to any one of the preceding claims, characterized in that The insert (10) is arranged around the through-opening (3, 4) and at least partially encloses the through-opening (3, 4).

9. The bipolar plate (1) according to any one of the preceding claims, characterized in that The layer (2) has a substantially flat surface in the region of the fluid guiding structure (12) of the insert (10), and the protrusions (14, 24) of the insert (10) rest on the flat surface of the layer (2).

10. The bipolar plate (1) according to any one of the preceding claims, characterized in that The through opening (3, 4) has an edge (7), and the longitudinal direction of the first passage (20, 30) is aligned substantially perpendicular to the closest area of ​​the edge (7), and / or the longitudinal direction of the second passage (20, 30) is aligned at an angle of 0° to 90° to the closest area of ​​the edge (7).

11. The bipolar plate (1) according to any one of the preceding claims, characterized in that The layer (2) has a lip arrangement (9) which is formed into the layer (2) and which partially surrounds the through-openings (3, 4).

12. The bipolar plate (1) according to the preceding claim, characterized in that The layer (2) has at least two through-openings (3, 4) arranged close to each other, wherein the rim arrangement (9) extends between the through-openings (3, 4), wherein the insert (10) is arranged at two of the at least two through-openings (3, 4) and has a fluid guiding structure (12) for the two through-openings (3, 4).

13. The bipolar plate (1) according to the preceding claim, characterized in that The insert (10) extends between the at least two through-openings (3; 4) and is arranged on the convex edge arrangement (9), and preferably extends along the edges (7) of the two through-openings (3, 4) in a frame-shaped, figure-of-eight-shaped or glasses-shaped manner.

14. The bipolar plate (1) according to any one of the two preceding claims, characterized in that The two through-openings (3; 4) are designed as fluid inlets or fluid outlets.

15. The bipolar plate (1) according to any one of the preceding claims, characterized in that An elastomeric seal (22) for sealing the through-openings (3, 4) is included, the elastomeric seal being arranged on a first side (11) of the insert (10) facing away from the layer (2).

16. Bipolar plate (1) according to the preceding claim, characterized in that The protrusions (14, 24) on the first side (11) of the insert (10) form a recess (15, 25), in particular a channel-shaped groove, and the elastomeric seal (22) is arranged at least in the recess (15, 25).

17. The bipolar plate (1) according to any one of the preceding claims, characterized in that The thickness of the insert (10) is at most 70%, preferably at most 30%, of the thickness of the layer (2).

18. A bipolar plate (1) for an electrochemical system, in particular an electrolyser, comprising at least one layer (2) and at least one insert (10), the layer (2) comprising: - at least one through opening (3, 4) which serves as an inlet or outlet for a fluid, - a flow field (8) with an electrochemically active area, The insert (10) is arranged at the through opening (3, 4) and comprises a fluid guiding structure (12) for guiding a fluid. wherein the fluid guiding structure (12) of the insert (10) is arranged between the flow field (8) and the through openings (3, 4) in the flow direction of the fluid, so that the fluid is guided from the through openings (3, 4) through the fluid guiding structure (12) to the flow field (8), or vice versa, wherein the fluid guiding structure (12) of the insert (10) has a plurality of protrusions (14, 24) and passages (20, 30), wherein the passages (20, 30) each extend between adjacent protrusions (14, 24) and are designed to guide the flow of fluid along the layer (2), At least two of the passages (20, 30) have different flow cross sections and / or different flow resistances and / or different widths and / or different lengths.

19. An arrangement for an electrochemical system, characterized in that The arrangement comprises a bipolar plate (1) according to any of the preceding claims, wherein the arrangement comprises a first battery cell frame and / or a membrane electrode unit and / or a second battery cell frame, and wherein the insert (10) is arranged between the first battery cell frame and the layer (2) and / or between the membrane electrode unit and the layer (2) and / or between the second battery cell frame and the layer (2).

20. An electrochemical system, in particular an electrolyser, characterized in that Comprising a plurality of stacked bipolar plates (1) according to any one of claims 1 to 18 and / or a plurality of stacked arrangements according to the preceding claims.

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