Distribution plate for an electrochemical cell, and electrochemical cell

Abstract

The present invention relates to a distribution plate (7) for an electrochemical cell (1), the distribution plate (7) having a structure including a web (12) having a surface (13) and main passages (11) having a bottom surface (33), the surface (13) of the web (12) having distribution passages (60), at least one distribution passage (60) having a minor passage (15) connecting the at least one distribution passage (60) to the bottom surface (33) of the main passage (11) and / or the side surface (31) of the web (12), the minor passage (15) having a smaller diameter than the at least one distribution passage (60). Further, the present invention relates to an electrochemical cell (1).

Description

[Technical field]

[0001] The present invention relates to a distribution plate for an electrochemical cell, the distribution plate having a structure including a web having a surface and a main passage having a bottom surface, the surface of the web having distribution passages. Further, the present invention relates to an electrochemical cell. [Background technology]

[0002] Electrochemical cells are electrochemical energy converters, known in the form of fuel cells and electrolysers.

[0003] Fuel cells convert the energy produced by the chemical reaction of a continuous supply of fuel and oxidant into electrical energy. In known fuel cells, hydrogen (H2) and oxygen (O2) are converted into water (H2O), electrical energy and heat.

[0004] In particular, proton exchange membrane (PEM) fuel cells are known, which have a centrally located membrane that is permeable to protons, i.e. hydrogen ions, by means of which the oxidant, in particular air oxygen, is spatially separated from the fuel, in particular hydrogen.

[0005] A fuel cell has an anode and a cathode. Fuel is supplied to the fuel cell at the anode and catalytically oxidized to protons, releasing electrons, which reach the cathode. The released electrons are then conducted out of the fuel cell and flow through an external electrical circuit to the cathode.

[0006] An oxidant, specifically atmospheric oxygen, is supplied to the fuel cell at the cathode and reacts to form water by accepting electrons and protons from an external electric circuit. The resulting water is then drawn off from the fuel cell. The overall reaction is: O2+4H + +4e ‐ → 2H2O

[0007] A voltage is then generated between the anode and cathode of the fuel cell. To increase this voltage, multiple fuel cells are mechanically arranged one above the other and electrically connected in series to form a fuel cell stack, also called a stack or fuel cell stack.

[0008] A stack of electrochemical cells typically has end plates that press the individual cells together to provide stability to the stack, and can also serve as the positive and negative poles of the stack for conducting electrical current.

[0009] The electrodes, ie, the anode and cathode, and the membrane may be designed together to form a membrane electrode assembly (MEA), also called a Membrane Electorode Assembly.

[0010] The stack of electrochemical cells further comprises bipolar plates, also called gas distribution plates or distribution plates, which serve to distribute the fuel evenly to the anode and the oxidant evenly to the cathode. Furthermore, the bipolar plates usually have a surface structure, in particular a channel-like structure, for distributing the fuel and the oxidant to each electrode. In particular in fuel cells, the channel-like structure also serves to conduct the water generated during the reaction. In addition to this, the bipolar plates can have structures for conducting a cooling medium through the electrochemical cells to dissipate heat.

[0011] The bipolar plate ensures media guidance for oxygen, hydrogen and water as well as surface electrical contact with the membrane.

[0012] For example, a fuel cell stack typically contains up to several hundred individual fuel cells, which are stacked one on top of the other in layers as a so-called sandwich. Each fuel cell has an MEA and a bipolar plate half on the anode and cathode side, respectively. A fuel cell contains, in particular, an anode monopolar plate and a cathode monopolar plate, usually in the form of stamped sheets, which together form a bipolar plate and therefore channels for guiding gases and liquids and between which a cooling medium flows.

[0013] Furthermore, electrochemical cells usually contain gas diffusion layers responsible for gas distribution, which are located between the bipolar plates and the MEA and are typically made of a carbon fiber nonwoven fabric, also called "gas diffusion backing" (GDB), on the passage side, i.e. towards the adjacent bipolar plate, and a microporous layer, also called "micro porous layer" (MPL), on the catalyst side, i.e. towards the membrane.

[0014] In contrast to a fuel cell, an electrolyser is an energy converter that preferably splits water into hydrogen and oxygen under the application of a voltage, and also comprises, among other things, an MEA, bipolar plates and gas diffusion layers.

[0015] It is particularly important for the efficiency of electrochemical cells, especially those having a polymer electrolyte membrane, that the electrode layers arranged on the membrane are uniformly supplied with reactant gases.

[0016] Known distributor plates have in particular passages and, respectively, adjacent or adjoining webs, which form a structure. These passages are also called main passages or channels, and the webs are also called lands. The surfaces of the webs, which are at least partially parallel to the elongation plane of the distributor plate, comprise the contact surface of the distributor plate with the adjacent gas diffusion layer of the electrochemical cell. The gases hydrogen and oxygen pass through the gas diffusion layer from the passages of the distributor plate to the reaction zone of the membrane. The areas of the gas diffusion layer resting on the webs of the distributor plate, and therefore the corresponding areas of the MEA located below, are relatively inaccessible to the supply of reactant gases, especially under the flow conditions of the electrochemical cell, which can lead to unintended and non-uniform flow density distributions.

[0017] On the side of the membrane where air or oxygen is supplied, water is generated during the operation of the fuel cell and is transported through the gas diffusion layer to the passages of the distribution plate, where it must be removed from the cell. Since typical operating temperatures for electrochemical cells with membranes are below 120° C., water typically condenses in the gas diffusion layer and exists in liquid form. In the gas diffusion layer, the direction of water transport is opposite to that of gas transport, and accumulated water can significantly impede the additional supply of reactant gases, especially oxygen.

[0018] That is, the higher the power density of the electrochemical cell, the more water is produced, which can result in insufficient liquid water transport at the contact area between the gas diffusion layer and the air passage side of the distribution plate.

[0019] US Pat. No. 5,399,633 describes an improved drainage system for bipolar plates in which additional grooves are provided in the slopes of the webs parallel to the direction of the main channels.

[0020] US Pat. No. 5,399,433 describes a bipolar plate with improved water drainage, the webs of which have an additional passage system arranged transversely to the direction of the main passages. Every two passages of the additional passage system have a common outlet. Furthermore, a crossing structure of the main passages of the distributor plate is disclosed, which leads to high pressure losses.

[0021] US Pat. No. 5,399,633 also relates to a bipolar plate with an improved drainage system, in which the webs have notches transverse to the direction of the main channels and additional grooves are present along the slope of the webs parallel to the direction of the main channels.

[0022] The passages described in these documents serve for water evacuation based on their sizing and are not designed for gas transport which would improve oxygen supply under the web. [Prior art documents] [Patent documents]

[0023] [Patent Document 1] JP 2020-47441 A [Patent Document 2] JP 2020-47443 A [Patent Document 3] JP 2020-47440 A Summary of the Invention

[0024] A distribution plate for an electrochemical cell is proposed, the distribution plate having a structure including a web having a surface and main channels having a bottom surface, the surface of the web having distribution channels, in particular at least one of said distribution channels having a secondary channel, in particular fluidly connecting the at least one distribution channel with a bottom surface of an adjacent main channel and / or a side surface of the web, the secondary channel having a smaller diameter, preferably a smaller width and / or depth, in particular a smaller cross-section than the at least one distribution channel.Furthermore, an electrochemical cell comprising the distribution plate is proposed.

[0025] The electrochemical cell, preferably a fuel cell or electrolyser, preferably comprises at least one distribution plate, at least one gas diffusion layer and at least one membrane or membrane electrode assembly, in particular one gas diffusion layer respectively arranged between the distribution plate and the membrane.

[0026] The gas diffusion layer preferably has a porous structure and more preferably abuts against the distribution plate under high pressure of about 10 to 15 bar. The membrane is preferably a polymer electrolyte membrane, for example comprising perfluorosulfonic acid (PFSA), in particular comprising or consisting of Nafion. Furthermore, alkaline membranes can also be used.

[0027] The gas diffusion layer preferably comprises a nonwoven fabric, in particular a carbon fiber nonwoven fabric, and optionally a microporous layer, the nonwoven fabric being arranged on the side of the gas diffusion layer facing the distribution plate. More preferably, the gas diffusion layer consists of a carbon fiber nonwoven fabric and optionally a microporous layer. In the nonwoven fabric, the gas permeability in the thickness direction, i.e. towards the membrane, may be comparable to the gas permeability in the plane, i.e. parallel to the membrane.

[0028] The distribution plate preferably comprises carbon, such as graphite, metal, such as stainless steel or titanium, and / or a metal-containing alloy. More preferably, the distribution plate is made of carbon, metal, and / or an alloy. In particular, the base plate of the distribution plate is made of carbon, metal, and / or an alloy.

[0029] The distribution channels serve primarily to supply gas, in particular oxygen, to the gas diffusion layer below the web of the bipolar plate and thus to the electrode following it. They guide the gas in particular to the area where the gas diffusion layer rests on the web. At least one distribution channel preferably connects two, in particular two adjacent, main channels. Meanwhile, the secondary channels mainly drain the generated liquid reaction water from the web to the main channel, in particular to the adjacent main channel. It is preferred that more than one distribution channel has secondary channels. It is even more preferred that there is one secondary channel per distribution channel. The secondary channels can also be called drain channels, capillary channels, grooves or microscopically small groove-like structures.

[0030] The at least one distribution channel and the sub-channels are in particular arranged on the side of the distribution plate facing the gas diffusion layer arranged adjacently in the electrochemical cell.

[0031] The distribution plate, which may also be called a bipolar plate, preferably has a corrugated structure, in which the webs and main channels are arranged alternately and preferably respectively parallel to one another.

[0032] The surfaces of the webs preferably each comprise at least one contact area, which may also be called a contact surface, where adjacently arranged gas diffusion layers abut. The contact areas of the webs are preferably arranged substantially parallel to the bottom surface of the main passage. Substantially parallel is understood to mean that the plane in which the contact areas lie and the bottom surface form an angle of less than 30°, more preferably less than 20°, even more preferably less than 10°, in particular less than 5°.

[0033] The porous structure of the gas diffusion layer can impede the natural outflow of water, which is typically present in liquid form under high flow densities, and can therefore lead to water retention at the contact area, which can limit the power density of the electrochemical cell.

[0034] The webs preferably have side surfaces, in particular included in the surface of the web. More preferably, the surface of the webs comprises two side surfaces per web, each of which continues to the bottom surface of the adjacent main channel. The side surfaces, which may also be called oblique surfaces, are preferably arranged at an oblique angle to the bottom surface, the oblique angle being more preferably in the range of 90° to 135°, even more preferably in the range of 90° to 125°, particularly preferably in the range of 95° to 110°. Furthermore, the side surfaces are preferably arranged folded relative to the contact area. The bottom surface is preferably at least partially planar.

[0035] The main channels are preferably arranged in a straight line, more preferably parallel to one another, in the distribution plate.

[0036] The secondary passages preferably have a cross-section that is triangular, i.e. V-shaped, circular, square or polygonal. More preferably, the cross-section of the secondary passage is V-shaped. The cross-section of the secondary passage may be constant over the length of the secondary passage or may vary in size and / or geometry. The width and / or depth of the secondary passage, especially in the first portion, is preferably between 1 μm and 150 μm, more preferably between 1 μm and 100 μm, especially preferably between 1 μm and 50 μm, even more preferably between 1 μm and 10 μm, and particularly preferably between 1 μm and 6 μm.

[0037] The gas diffusion layer disposed adjacent to the distribution plate preferably comprises fibers, and more preferably the width of the by-passages is smaller than the fiber diameter of the gas diffusion layer, e.g., about 8 μm. The width of the by-passages may be larger than the fiber diameter of the gas diffusion layer. The width, and possibly also the depth, of the by-passages may be selected depending on the structure of the adjacent gas diffusion layer.

[0038] Furthermore, the diameter, in particular the depth and / or width, of the secondary passages is preferably selected such that the secondary passages form a capillary action, in particular with respect to water. Diameter is understood in particular to mean the largest diameter of the cross section.

[0039] The distribution passages preferably have a cross-section that is rectangular, triangular or U-shaped. The cross-section of the main passage is preferably larger than the cross-section of the at least one distribution passage by at least a factor of 50. The distribution passage width and / or the distribution passage depth, respectively, are preferably between 10 μm and 400 μm, and it is further preferred that the distribution passage width and / or the distribution passage depth, respectively, are greater than 50 μm, in particular up to 150 μm.

[0040] The distribution channels may be arranged, for example, in a corrugated, parallel, cross-shaped, trapezoidal or honeycomb shape. The distribution channels preferably form a distribution angle with the main channels of 20° to 70°, more preferably 30° to 60°, in particular 30° to 45°.

[0041] The distribution plate preferably at least partially comprises a coating, which may be more hydrophilic or more hydrophobic than the material of the base plate of the distribution plate.

[0042] The coating may be hydrophobic, in particular may have a lotus effect. Hydrophobicity is preferably understood as being less wettable by water than steel with a smooth surface, more preferably as a contact angle for a water drop of more than 70°, in particular more than 80°. The coating may be present in particular in the contact area, for example in order to reduce the contact resistance there. Furthermore, the coating may be present on the bottom surface. Furthermore, the coating may be present only inside or only outside the secondary passages.

[0043] The coating preferably comprises carbon, such as soot or graphite, in particular carbon particles, and a binder, in particular organic, for example synthetic resins and / or polyvinylidene fluoride (PVDF). The binder may be thermoplastic or thermosetting. The coating preferably has a layer thickness in the range of 1 nm to 200 μm, more preferably 5 nm to 100 μm, especially preferably 5 nm to 50 μm. In the contact area of ​​the web, a layer thickness of more than 5 μm is preferably present. On the side and bottom surfaces, the layer thickness is preferably less than 1 μm.

[0044] Furthermore, the distribution plate optionally has at least partially a coating with an internal structuring. The secondary passages may be formed by the internal structuring of the coating. The internal structuring is preferably configured to be hydrophilic, so that water is drawn into the internal structuring, like into a wick. Hydrophilicity is preferably understood as being better wettable by water than the wettability of steel with a smooth surface, and more preferably as a contact angle for a water drop of less than 40°, in particular less than 10°. The coating may contain hydrophilic components, such as oxidized carbon particles with hydroxy, carbonyl and / or carboxyl groups, together with a polymeric binder, which is particularly applicable to carbon distribution plates. Furthermore, hydrophilic surface properties may be produced, for example, by surface treatment, for example with oxygen or acid. The coating preferably has a surface roughness Ra in the range of 0.1 to 10 μm, more preferably a bulk peak-to-valley maximum distance of 0.1 to 20 μm, more preferably 1 to 10 μm.

[0045] The coating can be applied, for example, by laser sintering, or by a method that also serves to apply a metal, ceramic, polymer, or mixture thereof in a pattern to the distribution plate. Yet another example of a coating method is spray coating.

[0046] Alternatively, a coating material, such as a powder, can first be applied to the distribution plate, which is then removed again in the contact areas and then a selective (laser) sintering process can be carried out, so that for example only the main channels can be provided with a coating that includes an internal structuring. The coating can be applied selectively, for example by mask and / or screen printing.

[0047] The coating can also be applied area-wise and then partially removed, for example by laser or mechanical methods, so as to expose the by-passages, in particular the side walls of the by-passages being formed by the coating.

[0048] The distribution channels and / or by-channels may be drilled into the base plate of the distribution plate, which is in particular a thin plate, and / or into the coating of the distribution plate. In the latter case, the layer thickness is preferably more than 5 μm. The distribution channels and / or by-channels may be coated or uncoated.

[0049] In a first preferred embodiment, the secondary passage ends at a flat part of the bottom of the main passage or at a side of the web, or at an edge between the bottom of the main passage and the side of the web. More preferably, the secondary passage ends abruptly at the end point, i.e. in a section having a constant width and depth. Alternatively, the width and / or depth of the secondary passage may decrease in the direction of the end point. The notion abruptly is understood in particular to mean that there is no connection to another secondary passage or a branching into several passages at the end point.

[0050] In a second preferred embodiment, the sub-passage communicates with the other sub-passage at the bottom surface of the main passage. The other sub-passage is preferably arranged only at the bottom surface. The other sub-passage may be arranged along the edge between the side surface and the bottom surface, and the other sub-passage is delimited by the side surface, especially on the first side. The edge where the side surface and the bottom surface meet can also be called a cutting edge or cutting line. Furthermore, the other sub-passage may be arranged along the axis of symmetry of the main passage, and the other sub-passage can each have the same spacing to both adjacent side surfaces. This can also be expressed as the other sub-passage extending in the center of the main passage. The other sub-passage is preferably arranged at an arrangement angle of less than 45° to the main passage. There may be one other sub-passage per main passage, or there may be several other sub-passages, each of which has at least one sub-passage communicating from the web.

[0051] In a third preferred embodiment, the secondary passage communicates with an end structure, where the secondary passage branches into at least two sub-passages, each of the at least two sub-passages having a smaller diameter than the secondary passage. In particular, the size of each of the cross-sections of the at least two sub-passages is smaller than the size of the cross-section of the secondary passage. The end structure may also be referred to as a microstructure or an extension, which effectively increases the surface area of ​​the liquid water, thereby improving the evacuation of the liquid water and / or the vaporization of the water into the gas phase guided in the main passage. It is further preferred that the end structure has at least three sub-passages, whereby at least one sub-passage can branch into at least two other sub-passages. The secondary passage and at least one of the sub-passages preferably partially form an angle in the range of 20° to 70°, more preferably 30° to 60°, for example 45°. Furthermore, it is preferred that the at least two sub-passages end in substantially parallel alignment with the secondary passage. The sub-passages preferably have a linear course between the respective branches.

[0052] Preferably, the secondary passage has a first portion disposed at a first angle relative to the primary passage in the range of 30° to 150°, and a second portion disposed at a second angle relative to the primary passage in the range of less than 45°.

[0053] It is further preferred that a first portion of the secondary passage, in particular directly on and / or within the at least one distribution passage, is arranged substantially perpendicular to the primary passage, where "substantially perpendicular" is understood to mean that the first angle is between 60° and 120°, more preferably between 80° and 100°, especially preferably between 85° and 95°.

[0054] It is further preferred that the second part of the secondary passage is arranged substantially parallel to the primary passage, where "substantially parallel" is understood to mean that the second angle is smaller than 30°, preferably smaller than 20°, more preferably smaller than 10°, particularly preferably smaller than 5°.

[0055] A second portion of the secondary passage is disposed at a second angle to align the secondary passage with a primary flow direction of the gas phase within the primary passage.

[0056] Preferably, the secondary passage has a curved path, which may also be called a circular path, in particular connecting a first portion of the secondary passage with a second portion of the secondary passage. Alternatively or additionally, the secondary passage may have a straight path with at least one, preferably more than one, turn, which may also be called a bend. The first portion and / or the second portion may also each have a curved path.

[0057] There may be more than two portions of the secondary passageway, thereby allowing more than two angles to be adjusted relative to the primary passageway.

[0058] The at least one distribution passage having a secondary passage is understood in particular to mean that the secondary passage forms at least one extension of the distribution passage. The secondary passage can begin, in particular directly, on the surface or inside the at least one distribution passage. The secondary passage preferably extends partially within or inside the at least one distribution passage. This can also be expressed as the secondary passage and the at least one distribution passage overlapping. The secondary passage can also be present over the entire length of the at least one distribution passage. The at least one distribution passage preferably has a bottom in which the secondary passage is partially arranged. The diameter of the secondary passage can be constant in the at least one distribution passage or can increase in the direction of the main passage.

[0059] The side of the web can have at least one retention edge, and the secondary passage is preferably arranged at least partially along the at least one retention edge. The retention edges can be embossed in the distribution plate, for example forming offset ridges. The at least one retention edge leads to an enhanced flow of the gas phase from the main passage to the distribution passage. In particular, the at least one retention edge is arranged flush with the inlet to the at least one distribution passage.

[0060] The components of the above-described embodiments can be freely combined with each other. Effect of the Invention

[0061] The distribution plate of the present invention not only improves the gas supply to the gas diffusion layer in the contact area, i.e., improves the penetration, especially of oxygen, into the area below the web, but also improves the water transport from the contact area to the main passages of the distribution plate.

[0062] The distribution channels improve the gas inflow into the contact area, while the secondary channels serve to facilitate good outflow of the liquid water from the distribution channels. The special geometry of the distribution channels allows for a further improvement in gas supply. The small diameter of the secondary channels results in a capillary action which further facilitates the transport of water.

[0063] The outflow within the main passage is also further optimized by the separate secondary passage in the main passage.

[0064] In addition to this, the optional end structures provide further structure that effectively increases the surface area of ​​the liquid water, thereby improving its drainage and evaporation into the gas phase within the main passage.

[0065] The stagnation edge, which serves for gas redirection from the main passage to the distribution passage, also contributes to the drainage of the contact area along the stagnation edge with the secondary passage.

[0066] Furthermore, liquid water can be absorbed into the internal structuring of the coating, if present, and transported to the main channels.

[0067] The embodiments of the present invention will be described in detail with reference to the drawings and the following description. [Brief description of the drawings]

[0068] [Figure 1] FIG. 1 is a schematic diagram showing an electrochemical cell according to the prior art. [Diagram 2] A fuel cell stack having a distribution plate. [Diagram 3] The contact area between the gas diffusion layer and the distribution plate. [Figure 4] FIG. 2 is a partial view showing a distribution plate having distribution passages. [Diagram 5] FIG. 4 is a partial view showing a distribution plate having a distribution passage and a sub-passage. [Figure 6] FIG. 2 is a cross-sectional view taken along a first cutting plane. [Figure 7]FIG. 4 is a partial view showing a distribution plate having a sub-passage inside a distribution passage. [Figure 8] FIG. 2 is a cross-sectional view taken along a second cutting plane. [Figure 9] FIG. 4 is a cross-sectional view taken along a third cutting plane. [Figure 10] FIG. 13 is a partial view showing a distribution plate having secondary passages and end structures. [Figure 11] 11 is another embodiment of an end structure. [Figure 12] 11 is yet another embodiment of an end structure. [Figure 13] FIG. 4 is a partial view showing a distribution plate having a secondary passage and another secondary passage. [Figure 14] FIG. 1 is a partial view of a distribution plate having a retaining edge. [Figure 15] FIG. 13 is a partial view of a distribution plate having retention edges and secondary passages. [Figure 16] FIG. 2 is another cross-sectional view taken along a second cutting plane. [Figure 17] FIG. 2 is another cross-sectional view taken along the first cutting plane. [Figure 18] FIG. 13 is a partial view of a distribution plate having a retention edge, a secondary passage, and another secondary passage. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0069] In the following description of the embodiments of the present invention, identical or similar elements are provided with the same reference numerals, and these elements will not be described repeatedly in individual cases. The drawings only represent the subject matter of the present invention diagrammatically.

[0070] 1 shows diagrammatically an electrochemical cell 1 in the form of a fuel cell according to the prior art. The electrochemical cell 1 has a membrane 2 as electrolyte. The membrane 2 separates a cathode space 39 from an anode space 41.

[0071] In the cathode space 39 and the anode space 41, an electrode layer 3, a gas diffusion layer 5, and a distribution plate 7 are respectively arranged on the membrane 2. The composite of the membrane 2 and the electrode layer 3 can also be called a membrane electrode assembly 4.

[0072] The distribution plate 7 has main channels 11 for gas supply to the gas diffusion layer 5, for example oxygen 43 in the cathode space 39 and hydrogen 45 in the anode space 41. On the distribution plate 7 main channels 11 and webs 12 alternate.

[0073] The surfaces 13 of the webs 12 define contact areas 47 between the distribution plate 7 and the adjacently arranged gas diffusion layer 5, respectively. The webs 12 further have side surfaces 31 and the main channels 11 have bottom surfaces 33.

[0074] 2 shows a fuel cell stack including a number of distribution plates 7 and membrane electrode assemblies 4 including membranes 2. The distribution plates 7 guide oxygen 43 or air enriched with oxygen 43 and hydrogen 45 to the membrane electrode assemblies 4. In the main channels 11 of the distribution plates 7, which are supplied with oxygen 43 or air enriched with oxygen 43, water 51 is discharged. Furthermore, the distribution plates 7 serve to guide the coolant 49.

[0075] 3 shows the contact area 47 between the gas diffusion layer 5 and the distribution plate 7. Here, the webs 12 of the distribution plate 7 are in contact with the gas diffusion layer 5. A coating 37 having a further internal structuring 74 is arranged on the webs 12 of the distribution plate 7. Hydrogen 45 passes from the main channels 11 through the gas diffusion layer 5 to the electrode layer 3 arranged on the membrane 2.

[0076] 4 shows a perspective plan view of a portion of a distribution plate 7 having alternating main passages 11 and webs 12. Along the main passages 11 there is a main flow direction 53. An alignment angle 72 is depicted in relation to the alignment of the main passages 11. Furthermore, the main passages 11 each have an axis of symmetry 55.

[0077] Each web 12 has a surface 13, the part of which is bent over and arranged against the bottom surface 33 of the main channel 11, referred to as the side surface 31. In the contact area 47 of the surface 13 of the web 12, the distribution channel 60 is arranged. The side surface 31 of the web 12 is followed by the bottom surface 33 of the main channel 11.

[0078] 5 shows a perspective plan view of a part of a distributor plate 7 with the distribution passages 60 and the secondary passages 15. The distributor plate 7 in FIG. 5 substantially corresponds to the distributor plate 7 shown in FIG. 4, with the difference that for each of the four distribution passages 60, a secondary passage 15 is arranged, which guides the water 51 to the adjacent main passage 11 or to the adjacent side surface 31, thus connecting each distribution passage 60 with the main passage 11 or with the side surface 31. The secondary passages 15 start at the distribution passages 60.

[0079] A first portion 17 of each secondary passage 15 is disposed at a first angle 19 relative to the adjacent primary passage 11, and a second portion 21 of each secondary passage 15 is disposed at a second angle 23 relative to the adjacent primary passage 11. The secondary passages 15 shown have curved paths such that their orientation changes along their paths relative to the adjacent primary passages 11. The secondary passages 15 are disposed substantially perpendicular to the primary passages 11 at the respective distribution passages 60, and substantially parallel to the primary passages 11 at or near the primary passages 11.

[0080] The first sub-passage 82 terminates at the flat portion 62 of the bottom surface 33 of the adjacent main passage 11. The second sub-passage 84 terminates at the edge 59 between the bottom surface 33 of the main passage 11 and the side surface 31 of the web 12. The third sub-passage 86 terminates at the side surface 31 of the web 12, thereby allowing the water 51 to flow out from the side surface 31 to the bottom surface 33 of the adjacent main passage 11. Additionally, a first cutting plane 76 is marked.

[0081] Figure 6 shows a cross-sectional view taken along the first cutting plane 76 shown in Figure 5. The sub-passage 15 is disposed on the side 31 of the web 12 and has a cross-section 35 that is V-shaped. The sub-passage 15 has a width 29 and a depth 27.

[0082] 7 shows a perspective plan view of a part of a distributor plate 7 with the bypass channels 15 inside the distributor channels 60. The distributor plate 7 in FIG. 7 substantially corresponds to the distributor plate 7 shown in FIG. 5, with the difference that the bypass channels 15 extend partially into the respective distributor channels 60 and are arranged at the bottom 88 of the distributor channels 60. The bypass channels 15 are accordingly arranged partially in the contact area 47 with the gas diffusion layer 5. In addition to this, a second cutting plane 78 and a third cutting plane 80 are marked.

[0083] Figure 8 shows a cross-section along the second cutting plane 78 shown in Figure 7. The distribution passages 60 are disposed on the surface 13 of the web 12, and at the bottom 88 of the distribution passages 60 are the sub-passages 15.

[0084] Figure 9 shows a cross-sectional view along the third cutting plane 80 shown in Figure 7. The second sub-passage 84 is located at the edge 59 between the side surface 31 and the bottom surface 33. The third sub-passage 86 is in the side surface 31 of the web 12.

[0085] 10 shows a perspective plan view of a portion of a distributor plate 7 having a secondary passage 15 communicating with an end structure 64 having more than two sub-passages 66. There are a plurality of sub-passages 66 each having the same length 90 but arranged offset from one another. The end structure 64 is located at the bottom surface 33 of the primary passage 11.

[0086] FIG. 11 illustrates another embodiment of an end structure 64 in which the subpassages 66 each have a different length 90 that decreases from the inside to the outside within the end structure 64 .

[0087] FIG. 12 illustrates yet another embodiment of an end structure 64 having subpassages 66 that are arranged in groups and offset from one another.

[0088] 13 shows a perspective plan view of a part of the distributor plate 7 with the distribution passages 60, the secondary passages 15 and the further secondary passages 70. The secondary passages 15 are partially arranged inside the distribution passages 60 and all of them communicate with the further secondary passages 70 arranged along the axis of symmetry 55 of the main passages 11. The arrangement angle 72 of the further secondary passages 70 is 0° in the illustrated embodiment, accordingly the further passages 70 run parallel to the main passages 11. Furthermore, the width 29 and the depth 27 of the secondary passages 15 increase in the outflow direction within the distribution passages 60.

[0089] 14 shows a perspective plan view of a portion of distribution plate 7 having retention edge 68 configured on side 31 of web 12. The other side 31 of web 12 may also optionally have at least one retention edge 68.

[0090] FIG. 15 shows a perspective plan view of a portion of a distribution plate 7 having a retention edge 68 and secondary passages 15 disposed therealong.

[0091] FIG. 16 is a cross-sectional view of the second cutting plane shown in FIG. 78 1 shows a cross-sectional view along

[0092] FIG. 17 is a schematic diagram of the first embodiment of the present invention shown in FIG. 1 1 shows a cross-sectional view along cutting plane 76 of the web 12. The by-passages 15 along retention edge 68 on side 31 of web 12 are apparent.

[0093] 18 shows a perspective plan view of a portion of a distribution plate 7 having a distribution passage 60, a secondary passage 15, a retention edge 68 and a further secondary passage 70. The secondary passage 15 extends along one of the retention edges 68 and communicates with another secondary passage 70 that extends parallel to the axis of symmetry 55 of the main passage 11.

[0094] The present invention is not limited to the above-described embodiment and the embodiments highlighted therein, but rather many variations within the scope of the claims that are within the scope of the practice of the art. [Explanation of symbols]

[0095] 1. Electrochemical cell 7 Distribution Plate 11 Main passage 12. Web 13 Surface 15 Side passage 17 First Part 19 First Angle 21 Second Part 23 Second Angle 27 Depth 29 Width 31 Side 33 Bottom 35 Cross Section 37 Coating 59 Edge 60 Distribution aisle 62 Flat area 64 End structure 66 Lower Passage 68 Retention Edge 70 Sub-aisle 72 Placement angle 74 Internal structuring

Claims

1. A distribution plate (7) for an electrochemical cell (1), said distribution plate (7) having a structure including webs (12) having a surface (13) and main channels (11) having a bottom surface (33), said surface (13) of said webs (12) having distribution channels (60), at least one distribution channel (60) having a secondary channel (15) connecting at least one of said distribution channels (60) with the bottom surface (33) of the main channels (11) and / or with the side surface (31) of the webs (12), said secondary passage (15) having a smaller diameter than at least one of said distribution passages (60); The sub-passage (15) communicates with another sub-passage (15, 70) at the bottom surface (33) of the main passage (11).

2. 2. The distributor plate (7) according to claim 1, characterized in that the further secondary passages (15, 70) are arranged at an arrangement angle (72) of less than 45° to the main passage (11).

3. 3. The distributor plate (7) according to claim 1 or 2, characterized in that the secondary passages (15) are arranged with their first portions (17) at a first angle (19) in the range of 30° to 150° relative to the main passages (11) and with their second portions (21) at a second angle (23) in the range of less than 45° relative to the main passages (11).

4. 4. The distributor plate (7) according to claim 1, wherein the secondary passages (15) have a curved course.

5. 5. The distributor plate (7) according to claim 1, wherein the secondary passage (15) extends partially into at least one distributor passage (60).

6. 6. The distribution plate (7) according to claim 5, characterized in that the side surface (31) has at least one retention edge (68), and the secondary passages (15) are arranged at least partially along the at least one retention edge (68).

7. 7. The distributor plate (7) according to any one of the preceding claims, characterized in that the width (29) and / or the depth (27) of the secondary passages (15) are between 1 μm and 150 μm, respectively.

8. 8. The distributor plate (7) according to claim 1, wherein the cross section (35) of the secondary passages (15) is V-shaped.

9. 9. The distributor plate (7) according to claim 1, characterized in that the distributor plate (7) at least partially comprises a coating (37) which has an internal structuring (74).

10. 10. The distributor plate (7) according to claim 9, characterized in that the secondary passages (15) are drilled in the coating (37).

11. Electrochemical cell (1) comprising a distributor plate (7) according to any one of claims 1 to 10.

Images