Bipolar plate for electrochemical cell of electrochemical device and electrochemical device

Abstract

In order to provide a bipolar plate for an electrochemical cell of an electrochemical device, the electrochemical device comprises a plurality of electrochemical cells following one another in a stacking direction, the bipolar plate comprising the following:-an anode gas through-opening; -a cathode gas through-opening; -an electrochemically active region of the bipolar plate, the electrochemically active region comprising an anode gas flow field and a cathode gas flow field; -an anode gas distribution region via which the anode gas through-opening is in fluid connection with the anode gas flow field; and-a cathode gas distribution region via which the cathode gas through-opening is in fluid connection with the cathode gas flow field; wherein the anode gas distribution region and / or the cathode gas distribution region comprise distribution structures, which delimit a distribution channel formed between each two distribution structures, in a bipolar plate in which the anode gas distribution region and / or the cathode gas distribution region are arranged, the anode gas is distributed as equally as possible to the distribution channels in the anode gas distribution region and / or the cathode gas is distributed as equally as possible to the distribution channels in the cathode gas distribution region, the invention proposes that the anode gas distribution region and / or the cathode gas distribution region each have at least one bypass channel, two adjacent distribution channels are fluidically connected to each other by means of a bypass channel.

Description

Technical Field

[0001] The invention relates to a bipolar plate for an electrochemical cell of an electrochemical device, the electrochemical device comprising a plurality of electrochemical cells following one another in a stacking direction, wherein the bipolar plate comprises the following items: - an anode gas through-opening, the anode gas through-opening forming an integral part of an anode gas channel extending through the electrochemical device in the stacking direction; - a cathode gas through-opening, which forms an integral part of a cathode gas channel extending through the electrochemical device in the stacking direction; - an electrochemically active region of the bipolar plate, the electrochemically active region including an anode gas flow field through which the anode gas can flow and a cathode gas flow field through which the cathode gas can flow; - an anode gas distribution region, via which the anode gas through-opening is in fluid connection with the anode gas flow field; and - a cathode gas distribution region, via which the cathode gas through-opening is in fluid connection with the cathode gas flow field; Therein, the anode gas distribution region and / or the cathode gas distribution region comprises distribution structures extending in the flow direction of the anode gas or the cathode gas, respectively, and these distribution structures delimit distribution channels formed between each two distribution structures. Background Art

[0002] In known bipolar plates of this type, the anode gas through-opening is surrounded by an anode gas sealing rib and the cathode gas through-opening is surrounded by a cathode gas sealing rib.

[0003] In order to guide the anode gas through the anode gas sealing rib, an anode gas inlet is provided on the inner side of the anode gas sealing rib facing the anode gas through-opening, and an anode gas outlet is provided on the outer side of the anode gas sealing rib facing away from the anode gas through-opening.

[0004] In order to guide the cathode gas through the cathode gas sealing rib, a cathode gas inlet is provided on the inner side of the cathode gas sealing rib facing the cathode gas through-opening, and a cathode gas outlet is provided on the outer side of the cathode gas sealing rib facing away from the cathode gas through-opening.

[0005] The anode gas outlet can only be arranged at a specific point along the circumference of the anode gas sealing rib, and the cathode gas outlet can only be arranged at a specific point along the circumference of the cathode gas sealing rib. This is due to the technical condition that the anode gas sealing rib or the cathode gas sealing rib cannot be excessively weakened, and due to the availability of a deformation tool, by means of which the anode gas outlet or the cathode gas outlet is formed on the anode gas sealing rib or the cathode gas sealing rib through a deformation process, especially through a stamping process or a deep drawing process.

[0006] The flow of anode gas or cathode gas into the distribution channels of the anode gas distribution area and the cathode gas distribution area is not equal. This is because some distribution channels have access openings toward their respective closed ribs that are located on the extension line of the anode gas outlet or the cathode gas outlet, so that a large proportion of the anode gas or cathode gas flows out from the relevant outlet in the direction of the access opening of such distribution channel.

[0007] The access openings of the other distribution channels facing the respective sealing ribs are located between the direct outflow paths of two anode gas outlets or two cathode gas outlets, so that only a smaller portion of the anode gas or cathode gas flowing out of the relevant outlets reaches the access openings of these distribution channels.

[0008] Since in the known bipolar plates, the anode gas is guided to the anode gas flow field through the distribution channels of the anode gas distribution area without leaving the distribution channels into which it initially flows, and the cathode gas is guided to the cathode gas flow field through the distribution channels of the cathode gas distribution area without leaving the distribution channels into which it initially flows, the unequal distribution of the anode gas or the cathode gas to the access openings of the distribution channels of the respective distribution areas will also result in unequal distribution of the anode gas on the anode gas flow channel of the anode gas flow field, or result in unequal distribution of the cathode gas on the cathode gas flow channel of the cathode gas flow field.

[0009] Due to the unequal distribution of the anode gas and / or cathode gas over the respective flow fields of the electrochemically active areas of the bipolar plates, the power and efficiency of the electrochemical device in which the bipolar plates are used is reduced. Summary of the invention

[0010] The object of the present invention is to provide a bipolar plate for an electrochemical cell of an electrochemical device of the type described at the outset, in which the anode gas flowing out of the anode gas through-opening is distributed as evenly as possible to the distribution channels formed between the distribution structures of the anode gas distribution area, and / or the cathode gas flowing out of the cathode gas through-opening is distributed as evenly as possible to the distribution channels formed between the distribution structures of the cathode gas distribution area.

[0011] According to the invention, this object is achieved in a bipolar plate having the features of the preamble of claim 1 in that the anode gas distribution area and / or the cathode gas distribution area each have at least one bypass channel, through which two adjacent distribution channels are in fluid connection with each other.

[0012] Bypass channels in the anode gas distribution region allow anode gas to flow from a distribution channel into which an above-average amount of anode gas flows from the anode gas outlet to an adjacent distribution channel containing less anode gas from the anode gas outlet.

[0013] By means of bypass channels in the cathode gas distribution area, cathode gas can also flow from a distribution channel containing an above-average amount of cathode gas from the cathode gas outlet to an adjacent distribution channel containing less cathode gas from the cathode gas outlet.

[0014] In this way, the anode gas delivered to the distribution channels or the cathode gas delivered is made equal.

[0015] This results in that the anode gas flow channels of the anode gas flow field supplied with anode gas from the anode gas distribution region or the cathode gas flow channels of the cathode gas flow field supplied with cathode gas from the cathode gas distribution region also transport the anode gas or cathode gas more evenly.

[0016] The distributing structures which form the distributing channels between them can be designed, for example, as distributing ribs which extend substantially linearly in the longitudinal direction of the respective distributing structure.

[0017] In a preferred embodiment of the present invention, it is provided that at least one bypass channel is formed by a local depression of one of the distribution structures.

[0018] The local depression preferably corresponds to at least 5%, in particular at least 10%, particularly preferably at least 20% of the height of the distributor structure having the local depression in the non-depressed section of the distributor structure.

[0019] The height of the distributor structure is preferably measured here starting from a longitudinal center plane of the bipolar plate oriented perpendicularly to the stacking direction and along which the anode-side bipolar plate layers and the cathode-side bipolar plate layers of the bipolar plate abut one another.

[0020] It is also advantageous if the local depression of the distributor structure forming the bypass channel corresponds to at most 95%, in particular at most 90%, particularly preferably at most 80%, for example at most 50%, of the height of the distributor structure with the local depression in the non-depressed section of the distributor structure.

[0021] The local depression is preferably at least 20 μm, in particular at least 40 μm, particularly preferably at least 80 μm.

[0022] Furthermore, the local depression is preferably at most 380 μm, in particular at most 360 μm, particularly preferably at most 320 μm, for example at most 200 μm.

[0023] The extension of the local depression of the distribution structure in the longitudinal direction of the distribution structure with the local depression is preferably at most 1.5 mm. This prevents components of the electrochemical cell supported by the respective distribution structure, such as a gas diffusion layer or a component of a sealing component of the electrochemical cell, from being insufficiently supported by the respective distribution structure and thus protruding into the respective bypass channel, thereby undesirably reducing the cross section of the bypass channel through which flow can flow.

[0024] In a preferred design of the present invention, the anode gas through-opening is surrounded by an anode gas sealing rib, and an anode gas outlet is arranged on the outer side of the anode gas sealing rib facing away from the anode gas through-opening, and the cathode gas through-opening is surrounded by a cathode gas sealing rib, and a cathode gas outlet is arranged on the outer side of the cathode gas sealing rib facing away from the cathode gas through-opening.

[0025] During operation of the electrochemical device, the greatest proportion of the anode gas flowing out of the anode gas outlet flows into distribution channels of the first-order distribution channels, which are referred to below as anode gas distribution regions.

[0026] Furthermore, the largest share of the cathode gas flowing out of the cathode gas outlet flows into distribution channels which are referred to below as first-order distribution channels of the cathode gas distribution region.

[0027] Two second-order distributing channels are adjacent to the respective first-order distributing channel, and (in addition to the respectively assigned first-order distributing channel) one third-order distributing channel or a further second-order distributing channel is adjacent to the respective second-order distributing channel.

[0028] During operation of the electrochemical device, more anode gas or cathode gas flows into the first-order distribution channel than into the second-order distribution channel, and more anode gas or cathode gas flows into the second-order distribution channel than into the first-order distribution channel.

[0029] In order to compensate for the unequal filling of the first-order to third-order distribution channels, it is preferably provided that a respective first-order distribution channel is in fluid connection with two adjacent second-order distribution channels, preferably via a first-order bypass channel.

[0030] Furthermore, it is preferably provided that the second-order distributor channels are in fluid connection with the respectively adjacent third-order distributor channels or, if appropriate, with the respectively adjacent further second-order distributor channels via the second-order bypass channels.

[0031] In this case, it is particularly advantageous for an equal distribution of the anode gas or cathode gas to the first- to third-order distribution channels if the first-order bypass channels have a larger flow-through cross section than the second-order bypass channels.

[0032] The flow-through cross section of the bypass channels extends perpendicularly to the longitudinal direction of the respective bypass channels and is therefore substantially parallel to the longitudinal direction of the distribution channels connected to one another via the bypass channels and parallel to the stacking direction.

[0033] Furthermore, it is advantageous for evenly distributing the anode gas or cathode gas to the first-order to third-order distribution channels that the second-order bypass channels (seen in a direction perpendicular to the longitudinal direction of the first-order distribution channels and oriented perpendicular to the stacking direction) at least partially overlap with the first-order bypass channels respectively adjacent to each other. In this way, it is possible to allow the anode gas or cathode gas flowing out of the first-order bypass channels to flow into the adjacent second-order bypass channels without changing their flow direction.

[0034] Regardless of the size of the flow-through cross-sections of adjacent bypass channels, it is advantageous for distributing the anode gas or cathode gas as equally as possible to the distribution channels of the anode gas distribution area or the cathode gas distribution area if at least one bypass channel (seen in a direction perpendicular to the longitudinal direction of the distribution structure on which the relevant bypass channel is constructed and oriented perpendicular to the stacking direction) at least partially overlaps with at least one bypass channel constructed in an adjacent distribution structure.

[0035] In a preferred embodiment of the present invention, it is provided that more than half of the directional distribution structures of the anode gas distribution region and / or more than half of the directional distribution structures of the cathode gas distribution region are each provided with at least one bypass channel.

[0036] For an equal distribution of the anode gas or the cathode gas, it is particularly advantageous if all oriented distribution structures of the anode gas distribution region and / or all oriented distribution structures of the cathode gas distribution region are each provided with at least one bypass channel.

[0037] If at least one distribution structure of the anode gas distribution area and / or at least one distribution structure of the cathode gas distribution area is provided with two or more bypass channels spaced apart from each other in the longitudinal direction of the respective distribution structures, further equalization of the transport of anode gas to the anode gas flow field or the transport of cathode gas to the cathode gas flow field can be achieved.

[0038] The bypass channels formed on the distribution structures are preferably closer to the end of the relevant distribution structure facing the anode gas or cathode gas through-opening than to the end of the relevant distribution structure facing the electrochemically active area of ​​the bipolar plate.

[0039] It is also advantageous if at least one distribution structure of the anode gas distribution area and / or at least one distribution structure of the cathode gas distribution area is provided with a bypass channel whose spacing along the longitudinal direction of the distribution structure from the end of the respective distribution structure facing away from the electrochemically active area of ​​the bipolar plate is greater than the extension of the bypass channel along the longitudinal direction of the distribution structure.

[0040] The bipolar plate according to the invention is particularly suitable for use in an electrochemical device comprising a plurality of electrochemical cells which follow one another in the stacking direction and each comprise a bipolar plate according to the invention.

[0041] Such an electrochemical device may be, for example, a fuel cell device or an electrolysis apparatus.

[0042] For example, the electrochemical device may be configured as a polymer electrolyte membrane (PEM) fuel cell device. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Further features and advantages of the invention are the subject of the following description of embodiments and the accompanying drawings, in which:

[0044] Figure 1 A top view of a bipolar plate for an electrochemical unit of an electrochemical device is shown with a viewing direction pointing to the anode side of the bipolar plate, the electrochemical device comprising a plurality of electrochemical units following one another in a stacking direction, wherein the bipolar plate comprises: an anode gas through-opening, the anode gas through-opening forming a component of an anode gas channel extending through the electrochemical device in the stacking direction; a cathode gas through-opening, the cathode gas through-opening forming a component of a cathode gas channel extending through the electrochemical device in the stacking direction; an electrochemically active region of the bipolar plate, the electrochemically active region comprising an anode gas flow field through which the anode gas can flow and a cathode gas flow field through which the cathode gas can flow; an anode gas a distribution region, via which an anode gas through-opening is in fluid connection with an anode gas flow field; and a cathode gas distribution region, via which a cathode gas through-opening is in fluid connection with a cathode gas flow field, wherein the anode gas distribution region and the cathode gas distribution region comprise oriented distribution structures extending in the flow direction of the anode gas or the cathode gas, the oriented distribution structures delimiting distribution channels formed between each two distribution structures, and wherein the anode gas distribution region and the cathode gas distribution region each have a plurality of bypass channels, via which each two mutually adjacent distribution channels are in fluid connection with each other;

[0045] Figure 2 Shows Figure 1 An enlarged view of the left end region of the bipolar plate;

[0046] Figure 3 Shows Figure 2 An enlarged view of region I;

[0047] Figure 4 The viewing direction is shown pointing to the anode side of the bipolar plate. Figure 3 A perspective view of a region of a bipolar plate shown in;

[0048] Figure 5 along Figure 3 Line 5-5 in FIG. 5 shows a distribution structure parallel to the anode gas distribution area passing through Figures 1 to 4 A longitudinal cross-sectional view of a section of a bipolar plate;

[0049] Figure 6 along Figure 3 Line 6-6 in FIG. 6 shows the distribution structure passing through the anode gas distribution area transversely to the anode gas distribution area. Figures 1 to 4 A longitudinal cross-sectional view of a section of a bipolar plate;

[0050] Figure 7 along Figure 3 The line 7-7 in FIG. 1 shows the passage of the distribution structure transversely to the anode gas distribution region in the bypass channel region of the anode gas distribution region. Figures 1 to 4 A longitudinal cross-sectional view of a bipolar plate;

[0051] Figure 8 The viewing direction is shown pointing to the cathode side of the bipolar plate. Figure 1 A top view of the bipolar plates along the stacking direction;

[0052] Fig. 9 Shows Figure 8 An enlarged view of the left end area of ​​the bipolar plate;

[0053] Fig.10 Shows Fig. 9 An enlarged view of region II;

[0054] Fig.11 The viewing direction is shown pointing to the cathode side of the bipolar plate. Fig.10 A perspective view of the bipolar plate region shown in ;

[0055] Fig.12 along Fig.10 Line 12-12 in FIG. 1 shows a distribution structure parallel to the cathode gas distribution region passing through Figures 1 to 11 A longitudinal cross-sectional view of a section of a bipolar plate;

[0056] Fig.13 along Fig.10 Line 13-13 in FIG. 1 shows the distribution structure passing through the cathode gas distribution area transversely to the cathode gas distribution area. Figures 1 to 11 A longitudinal cross-sectional view of a section of a bipolar plate; and

[0057] Fig.14 along Fig.10 The line 14-14 in FIG. 1 shows the passage of the distribution structure transversely to the cathode gas distribution region in the bypass channel region of the cathode gas distribution region. Figures 1 to 11 Longitudinal cross-sectional view of a section of a bipolar plate.

[0058] In all figures, identical or functionally equivalent elements are marked with the same reference symbols. DETAILED DESCRIPTION

[0059] Figures 1 to 14 The bipolar plate shown in the figure, which is generally designated by 100, forms a component of an electrochemical cell 102 (not shown as a whole). In addition to the bipolar plate 100, the electrochemical cell may also include a membrane electrode assembly, a gas diffusion layer and a sealing assembly.

[0060] A plurality of such electrochemical cells 102 follow one another in a stacking direction 104 in order to form a stack of electrochemical cells 102 , which is a component of an electrochemical device 106 , for example a fuel cell device.

[0061] The bipolar plate 100 has a substantially rectangular shape, wherein long sides 107 of the bipolar plate 100 extend along a longitudinal direction 108 and short sides 109 of the bipolar plate 100 extend along a transverse direction 110 of the bipolar plate 100 .

[0062] The longitudinal direction 108 and the transverse direction 110 are preferably oriented perpendicularly to one another and perpendicularly to the stacking direction 104 .

[0063] The longitudinal direction 108 is also referred to as the x-direction, the transverse direction 110 is referred to as the y-direction, and the stacking direction 104 is referred to as the z-direction.

[0064] The x-direction, y-direction and z-direction develop a rectangular coordinate system.

[0065] The bipolar plate 100 has two end regions 112 and an electrochemically active region 114 located between the end regions 112 .

[0066] The electrochemically active region 114 of the bipolar plate 100 includes an anode gas flow field 116 through which an anode gas can flow, a cathode gas flow field 118 through which a cathode gas can flow, and a coolant flow field 120 through which a coolant can flow.

[0067] In the embodiment described herein, the bipolar plate 100 is constructed in two layers and includes an anode-side bipolar plate layer 122 on which the anode gas flow field 116 is constructed and a cathode-side bipolar plate layer 124 on which the cathode gas flow field 118 is constructed.

[0068] The bipolar plate layers 122 and 124 are made of a material that is good at conducting electricity, preferably a metal material.

[0069] The bipolar plate layers 122 and 124 are connected to one another in a materially bonded manner along a joining line (not shown in the figures), preferably welded, in particular by laser welding.

[0070] The anode flow field 116 of the bipolar plate 100 is in fluid connection with the anode-side electrode of the membrane electrode assembly (optionally via an anode-side gas diffusion layer).

[0071] The cathode flow field 118 of the bipolar plate 100 is in fluid connection with the cathode-side electrode of the membrane electrode assembly (optionally via a cathode-side gas diffusion layer).

[0072] Therefore, the anode gas and the cathode gas can reach the electrochemically active regions of the respective membrane electrode assemblies from the electrochemically active region 114 of the bipolar plate 100. Therefore, the region of the bipolar plate 100 where the anode gas flow field 116 and the cathode gas flow field 118 are provided is referred to as the electrochemically active region 114 of the bipolar plate, even though the bipolar plate 100 itself does not undergo an electrochemical reaction.

[0073] The anode gas flow field 116 includes anode gas flow channels 126 , the main flow directions of which are oriented parallel to the longitudinal direction 108 (x-direction) of the bipolar plate 100 .

[0074] The cathode gas flow field 118 includes cathode gas flow channels 128 , the main flow directions of which are oriented parallel to the longitudinal direction 108 (x-direction) of the bipolar plate 100 .

[0075] The bipolar plate 100 has an end region 112 ( Figures 2 to 7 and Figures 9 to 14 1 , the first end region 112 a of the bipolar plate 100 is shown to have a plurality of medium passage openings 130, through which a fluid medium (anode gas (fuel gas, such as hydrogen), cathode gas (oxidant, such as oxygen or air) or coolant (such as water)) to be supplied to the electrochemical device 106 can be passed through the bipolar plate 100. The medium passage openings 130 of the bipolar plates 100 that follow one another in a stack of electrochemical cells 102 and the intermediate spaces between the medium passage openings 130 in the stacking direction 104 jointly form medium channels 132, respectively.

[0076] Each of the media channels 132 in one of the end regions 112 of the bipolar plate 100 , through which a fluid medium can be supplied to the electrochemical device 100 , is assigned a further media channel 132 in the respective opposite end region 112 , through which the relevant fluid medium can be discharged from the electrochemical device 106 .

[0077] In this case, the fluid medium passes from one end region 112 to the other end region 112 via an anode gas flow field 116 , a cathode gas flow field 118 or a coolant flow field 120 in the electrochemically active region 114 of the bipolar plate 100 .

[0078] exist Figures 2 to 7 and Figures 9 to 14 An anode gas through-opening 134 , a cathode gas through-opening 136 and a coolant through-opening 138 are arranged in the first end region 112 a of the bipolar plate 100 shown in FIG.

[0079] In this case, each of these through-openings 134 , 136 and 138 can in principle be used selectively to supply the relevant medium to the electrochemical device 106 or to discharge the relevant medium from the electrochemical device 106 .

[0080] In principle, each of the three media, anode gas, cathode gas and coolant, can flow through the electrochemically active region 114 parallel to the respective other media or in a main flow direction opposite to the main flow direction of one or both of the other media.

[0081] In a preferred design scheme of the present invention, it is provided that all through-openings 134, 136 and 138 arranged in the first end region 112a of the bipolar plate 100 are used to supply respective media to the electrochemical device 106, while the through-openings 134, 136 and 138 arranged in the second end region 112b of the bipolar plate 100 are used to discharge respective media from the electrochemical device 106.

[0082] In order to prevent the fluid medium from unintentionally escaping from the respectively associated through-openings 134 , 136 and 138 , each of these through-openings is provided with a respective sealing rib 140 .

[0083] The anode gas through-opening 134 is surrounded by an anode gas sealing rib 142 .

[0084] In order to transport the anode gas from the anode gas through-opening 134 to the anode gas flow field 136, the anode gas sealing rib 142 is provided with a plurality of anode gas inlets 144 on its inner side facing the anode gas through-opening 134, through which the anode gas can flow from the anode gas through-opening 134 into the inner space of the anode gas sealing rib 142 (see Figure 2 ).

[0085] The anode gas inlet 144 opens in each case at an edge 146 of the anode gas passage opening 134 .

[0086] In the illustrated embodiment, the edge 146 of the anode gas through-opening 134 is configured as a quadrilateral; however, the polygonal edge 146 of the anode gas through-opening 134 may also have more or less than four corners.

[0087] The corners of the anode gas through-openings 134 are preferably rounded in order to avoid tearing of the bipolar plate layers 122 and 124 in the region of these corners.

[0088] In order to enable the anode gas to escape from the inner space of the anode gas sealing rib 142 , the anode gas sealing rib 142 is provided with a plurality of anode gas outlets 154 on its outer side facing away from the anode gas through-opening 134 .

[0089] The anode gas outlet 154 is preferably arranged on a section 156 of the anode gas containment rib 142 that faces the electrochemically active region 114 of the bipolar plate 100 .

[0090] The anode gas inlets 144 arranged on the same section 156 of the anode gas sealing rib 142 are preferably offset relative to the anode gas outlets 154 along the circumferential direction of the anode gas sealing rib 142 .

[0091] The anode gas flows out through the anode gas outlet 154 on the section 156 of the anode gas sealing rib 142 into the anode gas distribution area 170 , which is used to distribute the anode gas to the anode gas flow channels 126 of the anode gas flow field 116 as evenly as possible.

[0092] The anode gas distribution region 170 includes a plurality of directional distribution structures 172 and a plurality of non-directional distribution structures 174, which are used to redirect the anode gas away from its original flow direction.

[0093] In this case, the directional distributing structure 172 is designed, for example, as a distributing rib 176 extending essentially linearly.

[0094] The non-directional distributing structure 174 is designed, for example, as a substantially bowl-shaped distributing projection 178 .

[0095] The distributor structures 172 and 174 and all other structures of the bipolar plate 100 described above and below are preferably formed integrally with the material of the bipolar plate layer 122 or 124 and introduced into the respective bipolar plate layer 122 or 124 by a forming process, for example by an embossing process or a deep drawing process.

[0096] The cathode gas through-opening 136 is surrounded by a cathode gas sealing rib 162 .

[0097] The coolant passage opening 138 is surrounded by a coolant-tightening rib 164 .

[0098] An annularly closed edge rib 182 surrounds the outer edge 180 of the bipolar plate 100 .

[0099] The edge ribs 182 surround the electrochemically active area 114 of the bipolar plate 100 , the anode gas through-openings 134 and the anode gas sealing ribs 142 in the two end areas 112 of the bipolar plate 100 , the cathode gas through-openings 136 and the cathode gas sealing ribs 162 in the two end areas 112 , and the coolant through-openings 138 and the coolant sealing ribs 164 in the two end areas 112 .

[0100] The edge beads 182 are used to prevent the medium to be supplied to the electrochemical device 106 , in particular anode gas, cathode gas and coolant, from escaping from the electrochemical cell 102 into an exterior space 184 of the electrochemical device 106 .

[0101] In order to allow the cathode gas to flow out from the cathode gas through-opening 136 through the cathode gas sealing rib 162, the cathode gas sealing rib 162 is provided with a plurality of cathode gas inlets 194 on its inner side facing the cathode gas through-opening 136 (see in particular Fig. 9 ).

[0102] The cathode gas enters the inner space of the cathode gas sealing rib 162 from the cathode gas through-opening 136 through the cathode gas inlet 194 .

[0103] The cathode gas inlet 194 preferably opens out at an edge 198 of the cathode gas through-opening 136 .

[0104] In the illustrated embodiment, the edge 198 of the cathode gas through opening 136 is configured as a quadrilateral. However, the number of corners of the polygonal edge 198 may be less than or more than four.

[0105] The cathode gas outlets 214 arranged on the outer side of the cathode gas sealing rib 162 facing away from the cathode gas through-opening 136 and enabling the cathode gas to flow out from the inner space of the cathode gas sealing rib 162 are preferably all arranged on the section 200 of the cathode gas sealing rib 162 facing the electrochemically active area 114 of the bipolar plate 100.

[0106] Preferably, the cathode gas inlets 194 arranged on the same section 200 of the cathode gas sealing rib 162 are arranged offset relative to the cathode gas outlets 214 in the circumferential direction of the cathode gas sealing rib 162 .

[0107] Preferably, a total of two or more, in particular four or more, in particular six or more, and in the present embodiment, eight cathode gas outlets 214 are provided on the cathode gas sealing rib 162 .

[0108] The cathode gas flows out through the cathode gas outlet 214 into the cathode gas distribution area 216 of the bipolar plate 100 . The cathode gas distribution area is used to distribute the cathode gas to the cathode gas flow channels 128 of the cathode gas flow field 118 as evenly as possible.

[0109] For this purpose, the cathode gas distribution region comprises distribution structures 218 which are designed as directional distribution structures 220 or as non-directional distribution structures 221 .

[0110] The directional distributing structure 220 is preferably designed as a linearly extending distributing rib 222 .

[0111] The non-directional distributing structure 221 is designed, for example, as a substantially bowl-shaped distributing projection 223 .

[0112] In order to allow the coolant to flow out of the coolant through-opening 138 and into the coolant flow field 120 of the bipolar plate 100, the coolant sealing rib 164 is provided with a plurality of coolant inlets 224 on its inner side facing the coolant through-opening 138 (see in particular Figure 2 ).

[0113] The coolant enters the inner space of the coolant sealing rib 164 from the coolant through-opening 138 through the coolant inlet 224 .

[0114] In the illustrated embodiment, the edge 228 of the coolant through-opening 138 is configured as a quadrilateral. However, the number of corners of the polygonal edge 228 of the coolant through-opening 138 may also be more or less than four.

[0115] Coolant outlets 225 arranged on the outer side of the coolant sealing rib 164 facing away from the coolant passage opening 138 and through which coolant can flow out of the interior space of the coolant sealing rib 164 are preferably all arranged on a section 230 of the coolant sealing rib 164 facing the electrochemically active region 114 of the bipolar plate 114 .

[0116] Preferably, the coolant inlet 224 arranged on the same section 230 of the coolant-tightening rib 164 is arranged offset relative to the coolant outlet 225 in the circumferential direction of the coolant-tightening rib 164 .

[0117] The coolant flows out through the coolant outlet 225 into the coolant distribution area 242 of the bipolar plate 100 , which is used to distribute the coolant as evenly as possible into the coolant channels of the coolant flow field.

[0118] In the coolant distribution area 242, the bipolar plate layer 122 on the anode side and the bipolar plate layer 124 on the cathode side are offset in opposite directions along the stacking direction 104 relative to the longitudinal center plane of the bipolar plate 100 oriented perpendicular to the stacking direction 104, so that a larger cross-section for flow through the coolant distribution area 242 is available.

[0119] The bipolar plate 100 is preferably designed rotationally symmetrically with respect to a rotation through 180° about an axis of rotation extending through the center point of the electrochemically active region 114 of the bipolar plate 100 and parallel to the stacking direction 104 (z direction).

[0120] Therefore, the medium through-opening 130 arranged in the second end region 112b, in particular the anode gas through-opening 134 arranged there, the cathode gas through-opening 136 arranged there and the coolant through-opening 138 arranged there, are preferably constructed and arranged substantially identically to the anode gas through-opening 134, the cathode gas through-opening 136 or the coolant through-opening 138 in the above-mentioned first end region 112a.

[0121] use Figures 1 to 14 The bipolar plate 100 shown and described above strives to distribute the anode gas flowing out of the anode gas outlet 154 on the anode gas sealing rib 142 as evenly as possible to the distribution channel 173 formed between the oriented distribution structures 172 of the anode gas distribution area 170, and to distribute the cathode gas flowing out of the cathode gas outlet 214 on the cathode gas sealing rib 162 as evenly as possible to the distribution channel 219 formed between the oriented distribution structures 220 of the cathode gas distribution area 216.

[0122] For this purpose, bypass channels 288 are respectively formed on the distribution structure 132 of the anode gas distribution region 170, through which two adjacent distribution channels 173 of the anode gas distribution region 170 are in fluid connection with each other (see in particular Figure 3 , Figure 4 and Figure 7 ).

[0123] Likewise, bypass channels 288 are formed in each case on the distribution structure 220 of the cathode gas distribution region 216 , via which two adjacent distribution channels 219 of the cathode gas distribution region 216 are in fluid connection with one another.

[0124] Bypass channels 288 in the anode gas distribution region 170 allow anode gas to flow from a distribution channel 173 having an above average amount of anode gas flowing out of the anode gas outlet 154 to an adjacent distribution channel 173 containing less anode gas flowing out of the anode gas outlet 154 .

[0125] Likewise, bypass channels 288 in cathode gas distribution region 216 may allow cathode gas to flow from distribution channels 219 containing above-average cathode gas from cathode gas outlets 214 to adjacent distribution channels 219 containing less cathode gas from cathode gas outlets 214 .

[0126] In this way, the anode gas delivered to the distribution channels 173 , 219 or the cathode gas delivered is made equal.

[0127] This results in that the anode gas flow channels 126 of the anode gas flow field 116 supplied with anode gas from the anode gas distribution region 170 or the cathode gas flow channels 128 of the cathode gas flow field 118 supplied with cathode gas from the cathode gas distribution region 216 also transport the anode gas or cathode gas more evenly.

[0128] from Figure 4 and Fig.11 As can be seen more clearly in the perspective view of , the bypass channel 288 is formed by a local depression of the distribution structure 172 or 220 , on which the relevant bypass channel 288 is constructed.

[0129] Here, the local depression of the distribution structure 172, 220 preferably corresponds to at least 5%, in particular at least 10%, and particularly preferably at least 20% of the height of the distribution structure 172, 220 with the local depression in the non-depressed section 290 of the relevant distribution structure 172, 220 adjacent to the respective bypass channel 288.

[0130] In addition, it is preferably provided that the local depression of the distribution structure 172, 220 on which the bypass channel 288 is formed corresponds to at most 95%, in particular at most 90%, particularly preferably at most 80%, for example at most 50%, of the height of the distribution structure 172, 220 with the local depression in the non-depressed section 290 of the relevant distribution structure 172, 220.

[0131] It is preferably provided that the local depression is preferably at least 20 μm, in particular at least 40 μm, particularly preferably at least 80 μm.

[0132] It is furthermore preferably provided that the local depression is preferably at most 380 μm, in particular at most 360 μm, particularly preferably at most 320 μm, for example at most 200 μm.

[0133] The extension of the local depressions and thus of the bypass channels 288 in the longitudinal direction of the respective distributor structure 172 , 220 having the local depression is preferably at most 1.5 mm. This prevents components of the electrochemical cell 102 supported by the respective distributor structure 172 , 220 , such as components of the gas diffusion layer or the sealing assembly of the electrochemical cell 102 , from being insufficiently supported by the respective distributor structure 172 , 220 and thus protruding into the respective bypass channel 288 , thereby undesirably reducing the cross section of the bypass channel 288 through which flow can flow.

[0134] Each anode gas outlet 154 on the anode gas sealing rib 142 is respectively assigned a first-order distribution channel 173a of the anode gas distribution area 170, which is arranged and oriented relative to the anode gas outlet 154 so that a maximum portion of the anode gas flowing out of the anode gas outlet 154 flows into the first-order distribution channel 173a.

[0135] Two second-order distribution channels 173b are adjacent to each first-order distribution channel 173a of the anode gas distribution area 170, and one third-order distribution channel 173c is adjacent to each second-order distribution channel 173b, wherein each second-order distribution channel 173b obtains less anode gas coming out of the anode gas outlet 154 compared with the first-order distribution channel 173a, and wherein each third-order distribution channel 173c obtains less anode gas coming out of the anode gas outlet 154 compared with the second-order distribution channel 173b.

[0136] Each first-order distribution channel 173 a is in fluid connection with one of the adjacent second-order distribution channels 173 b via a first-order bypass channel 288 a .

[0137] Each of the second-order distribution channels 173b is in fluid connection with an adjacent third-order distribution channel 173c via a second-order bypass channel 288b.

[0138] The third-order distribution channel 173c can be in fluid connection with another adjacent third-order distribution channel 173c via a third-order bypass channel 288c, respectively.

[0139] In order to distribute the anode gas to the distribution channels 173a, 173b and 173c of different stages as evenly as possible, the anode gas flowing through the first-stage bypass channel 288a must be greater than the anode gas flowing through the second-stage bypass channel 288b.

[0140] Therefore, compared with the second-order bypass channel 288b, the first-order bypass channel 288a has a larger cross-section through which flow can pass.

[0141] Compared to the third-order bypass channel 288c, the second-order bypass channel 288b preferably has a larger flow-through cross section.

[0142] from Figure 3 As can be better seen in FIG. 1 , the second-order bypass channels 288 b (seen in a direction perpendicular to the longitudinal direction of the first-order distribution channels 173 a and oriented perpendicular to the stacking direction 104 ) at least partially overlap with the respectively adjacent first-order bypass channels 288 a.

[0143] This ensures that the anode gas flowing through the first-order bypass channel 288 a can also flow through the second-order bypass channel 288 b without changing the flow direction or with only a slight change in the flow direction.

[0144] For the same reason, a bypass channel 288 (seen in a direction perpendicular to the longitudinal direction of the distribution structure 172 in which the bypass channel 288 is respectively formed and oriented perpendicular to the stacking direction 104 ) at least partially overlaps with at least one bypass channel 288 formed in an adjacent distribution structure 172 .

[0145] The distance between the bypass channel 288 and an end 292 of the respective distribution structure 172 on which the associated bypass channel 288 is formed, facing away from the electrochemically active region 114 of the bipolar plate 100 , along the longitudinal direction of the distribution structure 172 is greater than the extension of the associated bypass channel 288 along the longitudinal direction of the distribution structure 172 .

[0146] Each cathode gas outlet 214 on the cathode gas sealing rib 162 is respectively assigned a first-order distribution channel 219a of the cathode gas distribution area 216, which is arranged and oriented relative to the cathode gas outlet 214 so that the largest portion of the cathode gas flowing out of the cathode gas outlet 214 flows into the first-order distribution channel 219a.

[0147] Two second-order distribution channels 219b are adjacent to each first-order distribution channel 219a of the cathode gas distribution area 216, and there may be one additional second-order distribution channel 219b adjacent to each of the second-order distribution channels 219b, wherein each of the second-order distribution channels 219b obtains less cathode gas coming out of the cathode gas outlet 214 compared to the first-order distribution channel 219a.

[0148] Each first-order distribution channel 219a is in fluid connection with an adjacent second-order distribution channel 219b via a first-order bypass channel 288a.

[0149] The second-order distribution channels 219b can be in fluid connection with other adjacent second-order distribution channels 219b via the second-order bypass channels 288b, respectively.

[0150] In order to distribute the cathode gas to the distribution channels 219a and 219b of different stages as evenly as possible, the cathode gas flowing through the first-stage bypass channel 288a must be greater than the cathode gas flowing through the second-stage bypass channel 288b.

[0151] Therefore, compared with the second-order bypass channel 288b, the first-order bypass channel 288a has a larger cross-section through which flow can pass.

[0152] from Fig.10 As can be better seen in FIG. 1 , the second-order bypass channels 288 b (seen in a direction perpendicular to the longitudinal direction of the first-order distribution channels 219 a and oriented perpendicular to the stacking direction 104 ) at least partially overlap with the respectively adjacent first-order bypass channels 288 a .

[0153] This ensures that the cathode gas flowing through the first-order bypass channel 288a can also flow through the second-order bypass channel 288b without changing the flow direction or only slightly changing the flow direction.

[0154] For the same reason, a bypass channel 288 (seen in a direction perpendicular to the longitudinal direction of the distribution structure 220 in which the bypass channel 288 is respectively formed and oriented perpendicular to the stacking direction 104 ) at least partially overlaps with at least one bypass channel 288 formed in an adjacent distribution structure 220 .

[0155] The distance between the bypass channel 288 and an end 292 of the respective distributor structure 220 (on which the respective bypass channel 288 is formed) facing away from the electrochemically active region 114 of the bipolar plate 100 in the longitudinal direction of the distributor structure 220 is greater than the extension of the respective bypass channel 288 in the longitudinal direction of the distributor structure 220 .

Claims

1. A bipolar plate for an electrochemical cell (102) of an electrochemical device (106), the electrochemical device comprising a plurality of electrochemical cells (102) following one another in a stacking direction (104), wherein: The bipolar plate (100) comprises the following items: - an anode gas through-opening (134), which forms part of an anode gas channel extending through the electrochemical device (106) in the stacking direction (104); - a cathode gas through-opening (136), which forms part of a cathode gas channel extending through the electrochemical device (106) in the stacking direction (104); - an electrochemically active region (114) of the bipolar plate (100), the electrochemically active region comprising an anode gas flow field (116) through which an anode gas can flow, and a cathode gas flow field (118) through which a cathode gas can flow; - an anode gas distribution region (170), via which the anode gas through-opening (134) is in fluid connection with the anode gas flow field (116); as well as - a cathode gas distribution region (216), via which the cathode gas through-opening (136) is in fluid connection with the cathode gas flow field (118); The anode gas distribution region (170) and / or the cathode gas distribution region (216) comprises a distribution structure (172, 220) extending along the flow direction of the anode gas or the cathode gas, wherein the distribution structure delimits a distribution channel (173, 219) formed between each two distribution structures (172, 220). It is characterized in that The anode gas distribution region (170) and / or the cathode gas distribution region (216) each have at least one bypass channel (288), via which two mutually adjacent distribution channels (173, 219) are fluidically connected to one another.

2. The bipolar plate according to claim 1, characterized in that: The at least one bypass channel (288) is formed by a local depression in one of the distribution structures (172, 220).

3. The bipolar plate according to claim 2, characterized in that: The local depression corresponds to at least 5% of the height of the distributing structure (172, 220) with the local depression in the non-depressed section (290) of the distributing structure (172, 220).

4. The bipolar plate according to any one of claims 2 or 3, characterized in that: The local depression corresponds to at most 95% of the height of the distributing structure (172, 220) with the local depression in the non-depressed section (290) of the distributing structure (172, 220).

5. The bipolar plate according to any one of claims 2 to 4, characterized in that: The local depression is at least 20 μm.

6. The bipolar plate according to any one of claims 2 to 5, characterized in that: The local depression is at most 380 μm.

7. The bipolar plate according to any one of claims 2 to 6, characterized in that: The extension of the local depression in the longitudinal direction of the dispensing structure (172, 220) with the local depression is at most 1.5 mm.

8. The bipolar plate according to any one of claims 2 to 7, characterized in that: The anode gas through-opening (134) is surrounded by an anode gas sealing rib (142), and an anode gas outlet (154) is arranged on the outer side of the anode gas sealing rib facing away from the anode gas through-opening (134); and the cathode gas through-opening (136) is surrounded by a cathode gas sealing rib (162), and a cathode gas outlet (214) is arranged on the outer side of the cathode gas sealing rib facing away from the cathode gas through-opening (136). wherein a maximum share of the anode gas flowing out of the anode gas outlet (154) flows into the first-order distribution channel (173a) of the anode gas distribution region (170), and / or a maximum share of the cathode gas flowing out of the cathode gas outlet (214) flows into the first-order distribution channel (219a) of the cathode gas distribution region (216), wherein two second-order distribution channels (173b, 219b) are adjacent to respective first-order distribution channels (173a, 219a), and each third-order distribution channel (173c) or another second-order distribution channel (219b) is adjacent to respective second-order distribution channels (173b, 219b), wherein the respective first-order distribution channels (173a, 219a) are in fluid connection with the second-order distribution channels (173b, 219b) via the first-order bypass channels (288a), and the second-order distribution channels (173b, 219b) are in fluid connection with one of the third-order distribution channels (173c) or with the other second-order distribution channels (219b) via the second-order bypass channels (288b), and Compared with the second-order bypass channel (288b), the first-order bypass channel (288a) has a larger cross-section capable of flow through.

9. The bipolar plate according to claim 8, characterized in that: The second-order bypass channel (288b) at least partially overlaps with the first-order bypass channel (288a) adjacent to each other when viewed from a direction perpendicular to the longitudinal direction of the first-order distribution channel (173a, 219a) and oriented perpendicular to the stacking direction (104).

10. The bipolar plate according to any one of claims 1 to 9, characterized in that: At least one bypass channel (288) at least partially overlaps with at least one bypass channel (288) constructed in an adjacent distribution structure (172, 220), viewed from a direction perpendicular to the longitudinal direction of the distribution structure (172, 220) on which the associated bypass channel (288) is constructed and oriented perpendicular to the stacking direction (104).

11. The bipolar plate according to any one of claims 1 to 10, characterized in that: More than half of the oriented distribution structures (172) of the anode gas distribution region (170) and / or more than half of the oriented distribution structures (220) of the cathode gas distribution region (216) are each provided with at least one bypass channel (288).

12. The bipolar plate according to any one of claims 1 to 11, characterized in that: All oriented distribution structures (172) of the anode gas distribution region (170) and / or all oriented distribution structures (220) of the cathode gas distribution region (216) are each provided with at least one bypass channel (288).

13. The bipolar plate according to any one of claims 1 to 12, characterized in that: At least one distribution structure (172) of the anode gas distribution region (170) and / or at least one distribution structure (220) of the cathode gas distribution region (216) is provided with two or more bypass channels (288) spaced apart from each other in the longitudinal direction of the respective distribution structures (172, 220).

14. The bipolar plate according to any one of claims 1 to 13, characterized in that: At least one distribution structure (172) of the anode gas distribution area (170) and / or at least one distribution structure (220) of the cathode gas distribution area (216) is provided with a bypass channel (288) as follows: the distance between the bypass channel and an end (292) of the respective distribution structure (172, 220) facing away from the electrochemically active area (114) of the bipolar plate (100) along the longitudinal direction of the distribution structure (172, 220) is greater than the extension of the bypass channel (288) along the longitudinal direction of the distribution structure (172, 220).

15. An electrochemical device comprising electrochemical cells (102) which follow one another in a stacking direction (104) and each comprise a bipolar plate (100) according to any one of the preceding claims 1 to 14.

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