Bipolar plate for an electrochemical unit of an electrochemical device, and electrochemical device
Patent Information
- Application Number
- EP2023745449
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-08-01
- Filing Date
- 2023-07-17
- Publication Date
- 2025-06-11
AI Technical Summary
Existing bipolar plates for electrochemical devices suffer from uneven distribution of anode and cathode gases due to the design of gas sealing beads and outlets, leading to inefficient gas flow and reduced performance of the electrochemical device.
Incorporating bypass channels between distribution channels in the anode and cathode gas distribution areas, allowing for fluid communication between adjacent channels to even out gas flow, thereby ensuring uniform distribution across the electrochemically active regions.
This solution ensures a more even distribution of anode and cathode gases to the flow fields, enhancing the performance and efficiency of the electrochemical device by compensating for uneven filling in the distribution channels.
Smart Images
Figure 1.1
Abstract
Description
[0001] Bipolar plate for an electrochemical unit of an electrochemical device and electrochemical device
[0002] The present invention relates to a bipolar plate for an electrochemical unit of an electrochemical device comprising a plurality of electrochemical units arranged one after the other along a stacking direction, wherein the bipolar plate comprises: an anode gas passage opening forming a component of an anode gas channel extending through the electrochemical device along the stacking direction; a cathode gas passage opening forming a component of a cathode gas channel extending through the electrochemical device along the stacking direction; an electrochemically active region of the bipolar plate 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 distribution region via which the anode gas passage opening is in fluid communication with the anode gas flow field;and a cathode gas distribution region, via which the cathode gas passage opening is in fluid communication with the cathode gas flow field; wherein the anode gas distribution region and / or the cathode gas distribution region comprises distribution structures extending along a flow direction of the anode gas or the cathode gas, respectively, which delimit distribution channels formed between two distribution structures. In known bipolar plates of this type, the anode gas passage opening is surrounded by an anode gas sealing bead, and the cathode gas passage opening is surrounded by a cathode gas sealing bead.
[0003] In order to guide the anode gas through the anode gas sealing bead, anode gas inlets are provided on the inside of the anode gas sealing bead facing the anode gas passage opening and anode gas outlets are provided on the outside of the anode gas sealing bead facing away from the anode gas passage opening.
[0004] In order to allow the cathode gas to pass through the cathode gas sealing bead, cathode gas inlets are provided on the inside of the cathode gas sealing bead facing the cathode gas passage opening and cathode gas outlets are provided on the outside of the cathode gas sealing bead facing away from the cathode gas passage opening.
[0005] The anode gas outlets can only be arranged at specific points along the circumference of the anode gas sealing bead, and the cathode gas outlets can only be arranged at specific points along the circumference of the cathode gas sealing bead. This follows from the technical requirement that the anode gas sealing bead or the cathode gas sealing bead must not be weakened too much, and from the requirement of implementation in the forming tools by means of which the anode gas outlets or the cathode gas outlets are formed on the anode gas sealing bead or the cathode gas sealing bead by a forming process, in particular by a stamping process or a deep-drawing process.The distribution channels of the anode gas distribution area and the cathode gas distribution area are unevenly supplied with the anode gas or the cathode gas, respectively, since some distribution channels have an orifice opening facing the respective sealing bead, which is located in the extension of an anode gas outlet or a cathode gas outlet, respectively, so that a high proportion of the anode gas or the cathode gas flows out of the respective outlet in the direction of the orifice opening of such a distribution channel.
[0006] Other distribution channels have outlet openings facing the respective sealing bead, which are located between the direct outflow paths of two anode gas outlets or two cathode gas outlets, so that only a small proportion of the anode gas or cathode gas flowing out of the respective outlets reaches the outlet openings of these distribution channels.
[0007] Since in the known bipolar plates the anode gas is guided through the distribution channels of the anode gas distribution area to the anode gas flow field without leaving the distribution channel through which it originally flowed, and the cathode gas passes through the distribution channels of the cathode gas distribution area to the cathode gas flow field without leaving the distribution channel through which it originally flowed, the uneven distribution of the anode gas or the cathode gas to the outlet openings of the distribution channels of the respective distribution area also leads to an uneven distribution of the anode gas over the anode gas flow channels of the anode gas flow field or to an uneven distribution of the cathode gas over the cathode gas flow channels of the cathode gas flow field.Such an uneven distribution of the anode gas and / or the cathode gas across the respective flow fields of the electrochemically active region of the bipolar plate reduces the performance and efficiency of the electrochemical device in which such bipolar plates are used.
[0008] The present invention is based on the object of creating a bipolar plate for an electrochemical unit of an electrochemical device of the type mentioned at the outset, in which the anode gas flowing out of the anode gas passage opening is distributed as evenly as possible between the distribution channels formed between the distribution structures of the anode gas distribution region and / or the cathode gas flowing out of the cathode gas passage opening is distributed as evenly as possible between the distribution channels formed between the distribution structures of the cathode gas distribution region.
[0009] This object is achieved according to the invention in a bipolar plate having the features of the preamble of claim 1 in that the anode gas distribution region and / or the cathode gas distribution region each have at least one bypass channel through which two adjacent distribution channels are in fluid communication with one another.
[0010] Through the bypass channels in the anode gas distribution area, anode gas can flow from a distribution channel, into which an above-average amount of anode gas flows out of the anode gas outlets, into an adjacent distribution channel, which receives less anode gas from the anode gas outlets.
[0011] Likewise, the bypass channels in the cathode gas distribution area allow cathode gas to flow from one distribution channel, which receives an above-average amount of cathode gas from the cathode gas outlets, into an adjacent distribution channel, which receives less cathode gas from the cathode gas outlets. This evens out the supply of anode gas and cathode gas to the distribution channels.
[0012] As a result, the anode gas flow channels of the anode gas flow field supplied with anode gas by the anode gas distribution area and the cathode gas flow channels of the cathode gas flow field supplied with cathode gas by the cathode gas distribution area are supplied more evenly with anode gas and cathode gas, respectively.
[0013] The distribution structures between which the distribution channels are formed can, for example, be designed as distribution webs which extend substantially linearly along a longitudinal direction of the respective distribution structure.
[0014] In a preferred embodiment of the invention, it is provided that the at least one bypass channel is formed by a local lowering of one of the distributor structures.
[0015] The local lowering preferably corresponds to at least 5%, in particular at least 10%, particularly preferably at least 20%, of the height of the locally lowered distribution structure in a non-lowered section of the distribution structure.
[0016] The height of the distributor structure is preferably measured starting from a longitudinal center plane of the bipolar plate oriented perpendicular to the stacking direction, along which an anode-side bipolar plate layer and a cathode-side bipolar plate layer of the bipolar plate abut one another. Furthermore, it is advantageous if the local depression of the distributor structure, through which a bypass channel 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 locally lowered distributor structure in a non-lowered section of the distributor structure.
[0017] The local reduction is preferably at least 20 pm, in particular at least 40 pm, particularly preferably at least 80 pm.
[0018] Furthermore, the local reduction is preferably at most 380 pm, in particular at most 360 pm, particularly preferably at most 320 pm, for example at most 200 pm.
[0019] The extent of the local depression of the distributor structure in the longitudinal direction of the locally lowered distributor structure is preferably no more than 1.5 mm. This prevents a component of an electrochemical unit supported by the respective distributor structure, for example, a gas diffusion layer or a component of a sealing arrangement of an electrochemical unit, from being insufficiently supported by the respective distributor structure and thus bulging into the respective bypass channel, which would undesirably reduce the flow-through cross-section of the respective bypass channel.
[0020] In a preferred embodiment of the invention, the anode gas passage opening is surrounded by an anode gas sealing bead, on the outer side of which, facing away from the anode gas passage opening, an anode gas outlet is arranged, and the cathode gas passage opening is surrounded by a cathode gas sealing bead, on the outer side of which, facing away from the cathode gas passage opening, a cathode gas outlet is arranged. During operation of the electrochemical device, the largest portion of the anode gas flowing out of the anode gas outlet flows into a distribution channel, which is referred to below as a first-order distribution channel of the anode gas distribution region.
[0021] Furthermore, the largest portion of the cathode gas flowing out of the cathode gas outlet flows into a distribution channel, which is hereinafter referred to as the first-order distribution channel of the cathode gas distribution region.
[0022] Two second-order distribution channels are adjacent to the respective first-order distribution channel, and a third-order distribution channel or another second-order distribution channel is adjacent to the respective second-order distribution channels (apart from the respective associated first-order distribution channel).
[0023] During operation of the electrochemical device, more anode gas or cathode gas flows into a first-order distribution channel than into a second-order distribution channel, and more anode gas or cathode gas flows into a second-order distribution channel than into a first-order distribution channel.
[0024] In order to compensate for this uneven filling of the first to third order distribution channels, it is preferably provided that the respective first order distribution channel is in fluid connection with the two adjacent second order distribution channels via a first order bypass channel.
[0025] Furthermore, it is preferably provided that the second-order distribution channels are each fluidly connected to the adjacent third-order distribution channel or, if appropriate, to the adjacent further second-order distribution channel via a second-order bypass channel. For a uniform distribution of the anode gas or cathode gas between the first-order to third-order distribution channels, it is particularly advantageous if the first-order bypass channels each have a larger flow-through cross-section than the second-order bypass channels.
[0026] The flow-through cross-section of a bypass channel is taken perpendicular to the longitudinal extent of the bypass channel in question and thus essentially parallel to the longitudinal directions of the distribution channels connected by the bypass channel as well as parallel to the stacking direction.
[0027] Furthermore, for a uniform distribution of the anode gas or cathode gas between the first- to third-order distribution channels, it is advantageous if the second-order bypass channels overlap at least partially with the adjacent first-order bypass channels—as viewed in a direction perpendicular to the longitudinal direction of the first-order distribution channel and perpendicular to the stacking direction. This allows anode gas or cathode gas flowing out of a first-order bypass channel to flow into the adjacent second-order bypass channel without changing its flow direction.
[0028] Regardless of the size of the flow-through cross-sections of adjacent bypass channels, it is advantageous for the most uniform distribution possible of the anode gas or cathode gas to the distribution channels of the anode gas distribution region or cathode gas distribution region if at least one bypass channel overlaps at least partially with at least one bypass channel formed in an adjacent distribution structure—as viewed in a direction perpendicular to the longitudinal direction of the distribution structure on which the respective bypass channel is formed and perpendicular to the stacking direction. In a preferred embodiment of the invention, it is provided that more than half of the directed distribution structures of the anode gas distribution region and / or more than half of the directed distribution structures of the cathode gas distribution region are each provided with at least one bypass channel.
[0029] It is particularly favorable for a uniform distribution of the anode gas or the cathode gas if all directed distribution structures of the anode gas distribution area and / or all directed distribution structures of the cathode gas distribution area are each provided with at least one bypass channel.
[0030] A further homogenization of the supply of anode gas to the anode gas flow field or cathode gas to the cathode gas flow field can be achieved if at least one distributor structure of the anode gas distribution area and / or at least one distributor structure of the cathode gas distribution area is provided with two or more bypass channels spaced apart from one another in the longitudinal direction of the respective distributor structure.
[0031] A bypass channel formed on a distributor structure is preferably located closer to an end of the distributor structure in question facing the anode gas passage opening or the cathode gas passage opening than to an end of the distributor structure in question facing the electrochemically active region of the bipolar plate.
[0032] Furthermore, it is advantageous if at least one distribution structure of the anode gas distribution region and / or at least one distribution structure of the cathode gas distribution region is provided with a bypass channel whose distance from an end of the respective distribution structure facing away from the electrochemically active region of the bipolar plate along the longitudinal direction of the distribution structure is greater than the extent of the bypass channel along the longitudinal direction of the distribution structure. The bipolar plate according to the invention is particularly suitable for use in an electrochemical device comprising a plurality of electrochemical units that follow one another along a stacking direction and each comprise a bipolar plate according to the invention.
[0033] Such an electrochemical device can be designed, for example, as a fuel cell device or as an electrolyzer.
[0034] For example, such an electrochemical device can be embodied as a polymer electrolyte membrane (PEM) fuel cell device. Further features and advantages of the invention are the subject of the following description and the drawing of an exemplary embodiment.
[0035] The drawings show:
[0036] Fig. 1 is a plan view of a bipolar plate for an electrochemical unit of an electrochemical device comprising a plurality of electrochemical units arranged one after the other along a stacking direction, wherein the bipolar plate comprises an anode gas passage opening forming a component of an anode gas channel extending through the electrochemical device along the stacking direction, a cathode gas passage opening forming a component of a cathode gas channel extending through the electrochemical device along the stacking direction, an electrochemically active region of the bipolar plate 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 distribution region via which the anode gas passage opening is in fluid communication with the anode gas flow field, and a cathode gas distribution region,via which the cathode gas passage opening is in fluid communication with the cathode gas flow field, wherein the anode gas distribution region and the cathode gas distribution region comprise directed distribution structures extending along a flow direction of the anode gas and the cathode gas, respectively, which delimit distribution channels formed between two distribution structures, and wherein the anode gas distribution region and the cathode gas distribution region each have a plurality of bypass channels through which two adjacent distribution channels are in fluid communication with each other, with the view towards the anode side of the bipolar plate;,
[0037] Fig. 2 is an enlarged view of the left end region of the bipolar plate from Fig. 1;
[0038] Fig. 3 is an enlarged view of area I from Fig. 2;
[0039] Fig. 4 is a perspective view of the area of the bipolar plate shown in Fig. 3, looking towards the anode side of the bipolar plate;
[0040] Fig. 5 is a partial longitudinal section through the bipolar plate of Figs. 1 to 4 parallel to a distribution structure of the anode gas distribution region, along the line 5-5 in Fig. 3;
[0041] Fig. 6 is a partial longitudinal section through the bipolar plate of Figs. 1 to 4, transverse to distribution structures of the anode gas distribution region, along the line 6 - 6 in Fig. 3;
[0042] Fig. 7 shows a partial longitudinal section through the bipolar plate of Figs. 1 to 4, transverse to the distribution structures of the anode gas distribution region, in the region of bypass channels of the anode gas distribution region, along line 7-7 in Fig. 3; Fig. 8 shows a plan view of the bipolar plate of Fig. 1 along the stacking direction, looking toward the cathode side of the bipolar plate;
[0043] Fig. 9 is an enlarged view of the left end region of the bipolar plate from Fig. 8;
[0044] Fig. 10 is an enlarged view of area II from Fig. 9;
[0045] Fig. 11 is a perspective view of the area of the bipolar plate shown in Fig. 10, looking towards the cathode side of the bipolar plate;
[0046] Fig. 12 is a partial longitudinal section through the bipolar plate of Figs. 1 to 11, parallel to a distribution structure of the cathode gas distribution region, along the line 12-12 in Fig. 10;
[0047] Fig. 13 is a partial longitudinal section through the bipolar plate of Figs. 1 to 11, transverse to the distribution structures of the cathode gas distribution area, along the line 13 - 13 in Fig. 10; and
[0048] Fig. 14 is a partial longitudinal section through the bipolar plate of Figs. 1 to 11, transverse to distributor structures of the cathode gas distribution region, in the region of bypass channels of the cathode gas distribution region, along the line 14-14 in Fig. 10.
[0049] Identical or functionally equivalent elements are designated by the same reference numerals throughout the figures. A bipolar plate, shown in Figs. 1 to 14 and designated as a whole by 100, forms a component of an electrochemical unit 102 (not shown as a whole), which, in addition to the bipolar plate 100, may include a membrane-electrode assembly, gas diffusion layers, and a sealing assembly.
[0050] A plurality of such electrochemical units 102 follow one another along a stacking direction 104 to form a stack of electrochemical units 102, which is a component of an electrochemical device 106, for example a fuel cell device.
[0051] The bipolar plate 100 has a substantially rectangular shape, with long sides 107 of the bipolar plate 100 extending along a longitudinal direction 108 and short sides 109 of the bipolar plate 100 extending along a transverse direction 110 of the bipolar plate 100.
[0052] The longitudinal direction 108 and the transverse direction 110 are preferably aligned perpendicular to each other and perpendicular to the stacking direction 104.
[0053] 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.
[0054] The x-direction, the y-direction and the z-direction form a rectangular coordinate system.
[0055] The bipolar plate 100 has two end regions 112 and an electrochemically active region 114 located between the end regions 112.
[0056] The electrochemically active region 114 of the bipolar plate 100 comprises 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. In the exemplary embodiment described here, the bipolar plate 100 is formed in two layers and comprises an anode-side bipolar plate layer 122 on which the anode gas flow field 116 is formed, and a cathode-side bipolar plate layer 124 on which the cathode gas flow field 118 is formed.
[0057] The bipolar plate layers 122 and 124 consist of an electrically highly conductive material, preferably a metallic material.
[0058] The bipolar plate layers 122 and 124 are materially connected to one another along joining lines (not shown in the drawing), preferably welded, in particular by laser welding.
[0059] The anode flow field 116 of the bipolar plate 100 is in fluid communication with an anode-side electrode of a membrane electrode arrangement, optionally via an anode-side gas diffusion layer.
[0060] The cathode flow field 118 of the bipolar plate 100 is in fluid communication with a cathode-side electrode of a membrane-electrode arrangement, optionally via a cathode-side gas diffusion layer.
[0061] Thus, anode gas and cathode gas can flow from the electrochemically active region 114 of the bipolar plate 100 to the electrochemically active regions of each membrane-electrode assembly. Therefore, the region of the bipolar plate 100 provided with the anode gas flow field 116 and the cathode gas flow field 118 is referred to as its electrochemically active region 114, even though no electrochemical reactions take place at the bipolar plate 100 itself. The anode gas flow field 116 comprises anode gas flow channels 126, the main flow direction of which is aligned parallel to the longitudinal direction 108 (x-direction) of the bipolar plate 100.
[0062] The cathode gas flow field 118 comprises cathode gas flow channels 128 whose main flow direction extends parallel to the longitudinal direction 108 (x-direction) of the bipolar plate 100.
[0063] In its end regions 112, of which a first end region 112a is shown in Figs. 2 to 7 and 9 to 14, the bipolar plate 100 has a plurality of medium passage openings 130 through which a fluid medium to be supplied to the electrochemical device 106 (an anode gas (fuel gas, for example, hydrogen), a cathode gas (oxidizing agent, for example, oxygen or air), or a coolant (for example, water)) can pass through the bipolar plate 100. The medium passage openings 130 of the bipolar plates 100 arranged consecutively in the stack of electrochemical units 102 and the spaces located between the medium passage openings 130 in the stacking direction 104 together form a medium channel 132.
[0064] Each of the medium 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 different medium channel 132 in the respective opposite end region 112, through which the respective fluid medium can be discharged from the electrochemical device 106.
[0065] The fluid media pass through the anode gas flow field 116, the cathode gas flow field 118 or the coolant flow field 120 in the electrochemically active region 114 of the bipolar plate 100 from one end region 112 to the other end region 112. In the first end region 112a of the bipolar plate 100 shown in Figs. 2 to 7 and 9 to 14, an anode gas passage opening 134, a cathode gas passage opening 136 and a coolant passage opening 138 are arranged.
[0066] In principle, each of these passage openings 134, 136 and 138 can serve either to supply the respective medium to the electrochemical device 106 or to remove the respective medium from the electrochemical device 106.
[0067] In principle, each of the three media, anode gas, cathode gas and coolant, can flow through the electrochemically active region 114 parallel to the other media or with an opposite main flow direction with respect to the main flow directions of one or two of the other media.
[0068] In a preferred embodiment of the invention, it is provided that all passage openings 134, 136 and 138 arranged in the first end region 112a of the bipolar plate 100 serve to supply the respective medium to the electrochemical device 106 and the passage openings 134, 136 and 138 arranged in the second end region 112b of the bipolar plate 100 serve to remove the respective medium from the electrochemical device 106.
[0069] In order to prevent undesired leakage of the fluid media from the respective associated passage openings 134, 136 and 138, each of these passage openings is provided with a sealing bead 140.
[0070] The anode gas passage opening 134 is surrounded by an anode gas sealing bead 142. In order to be able to supply the anode gas from the anode gas passage opening 134 to the anode gas flow field 136, the anode gas sealing bead 142 is provided with a plurality of anode gas inlets 144 on its inner side facing the anode gas passage opening 134, through which anode gas can flow from the anode gas passage opening 134 into the interior of the anode gas sealing bead 142 (see Fig. 2).
[0071] The anode gas inlets 144 each open at an edge 146 of the anode gas passage opening 134.
[0072] In the illustrated embodiment, the edge 146 of the anode gas passage opening 134 is square; however, the polygonal edge 146 of the anode gas passage opening 134 can also have more or fewer than four corners.
[0073] The corners of the anode gas passage opening 134 are preferably rounded in order to prevent tearing of the bipolar plate layers 122 and 124 in the region of these corners.
[0074] In order to allow the anode gas to escape from the interior of the anode gas sealing bead 142, the anode gas sealing bead 142 is provided with a plurality of anode gas outlets 154 on its outer side facing away from the anode gas passage opening 134.
[0075] The anode gas outlets 154 are preferably arranged on a portion 156 of the anode gas sealing bead 142 which faces the electrochemically active region 114 of the bipolar plate 100.
[0076] The anode gas inlets 144, which are arranged on the same section 156 of the anode gas sealing bead 142, are preferably offset from the anode gas outlets 154 along the circumferential direction of the anode gas sealing bead 142. The anode gas flows through the anode gas outlets 154 on the section 156 of the anode gas sealing bead 142 into an anode gas distribution region 170, which serves to distribute the anode gas as evenly as possible among the anode gas flow channels 126 of the anode gas flow field 116.
[0077] The anode gas distribution region 170 comprises a plurality of directed distribution structures 172 and a plurality of non-directed distribution structures 174, which serve to deflect the anode gas from its original flow direction.
[0078] The directed distribution structures 172 are designed, for example, as essentially linearly extending distribution webs 176.
[0079] The non-directional distribution structures 174 are formed, for example, as essentially cup-shaped distribution knobs 178.
[0080] The distributor structures 172 and 174, like all other structures of the bipolar plate 100 described above and below, are preferably formed integrally with the material of the bipolar plate layers 122 or 124 and are introduced into the respective bipolar plate layer 122 or 124 by a forming process, for example by a stamping process or a deep-drawing process.
[0081] The cathode gas passage opening 136 is surrounded by a cathode gas sealing bead 162.
[0082] The coolant passage opening 138 is surrounded by a coolant sealing bead 164.
[0083] Near the outer edge 180 of the bipolar plate 100, a closed, annular edge bead 182 extends. The edge bead 182 encloses the electrochemically active region 114 of the bipolar plate 100, the anode gas passage openings 134 and the anode gas sealing beads 142 in both end regions 112, the cathode gas passage openings 136 and the cathode gas sealing beads 162 in both end regions 112, and the coolant passage openings 138 and the coolant sealing beads 164 in both end regions 112 of the bipolar plate 100.
[0084] The edge bead 182 serves to prevent the media to be supplied to the electrochemical device 106, in particular the anode gas, the cathode gas and the coolant, from escaping from the electrochemical units 102 into the outer space 184 of the electrochemical device 106.
[0085] In order to allow the cathode gas to flow out of the cathode gas passage opening 136 through the cathode gas sealing bead 162, the cathode gas sealing bead 162 is provided with a plurality of cathode gas inlets 194 on its inner side facing the cathode gas passage opening 136 (see in particular Fig. 9).
[0086] Through the cathode gas inlets 194, cathode gas passes from the cathode gas passage opening 136 into the interior of the cathode gas sealing bead 162.
[0087] The cathode gas inlets 194 preferably open at the edge 198 of the cathode gas passage opening 136.
[0088] In the embodiment illustrated in the drawing, the edge 198 of the cathode gas passage opening 136 is rectangular. However, the number of corners of the polygonal edge 198 can also be fewer or larger than four. Cathode gas outlets 214, which are arranged on the outer side of the cathode gas sealing bead 162 facing away from the cathode gas passage opening 136 and through which the cathode gas flows out of the interior of the cathode gas sealing bead 162, are preferably all arranged on a section 200 of the cathode gas sealing bead 162 facing the electrochemically active region 114 of the bipolar plate 100.
[0089] Preferably, the cathode gas inlets 194, which are arranged on the same section 200 of the cathode gas sealing bead 162, are arranged offset from the cathode gas outlets 214 along the circumferential direction of the cathode gas sealing bead 162.
[0090] Preferably, a total of two or more, in particular four or more, particularly preferably six or more, in the illustrated embodiment eight, cathode gas outlets 214 are provided on the cathode gas sealing bead 162.
[0091] The cathode gas flows through the cathode gas outlets 214 into a cathode gas distribution region 216 of the bipolar plate 100, which serves to distribute the cathode gas as evenly as possible to the cathode gas flow channels 128 of the cathode gas flow field 118.
[0092] 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.
[0093] The directional distribution structures 220 are preferably formed as linearly extending distribution webs 222.
[0094] The non-directional distribution structures 221 are formed, for example, as essentially cup-shaped distribution knobs 223. To allow the coolant to flow from the coolant passage opening 138 into the coolant flow field 120 of the bipolar plate 100, the coolant sealing bead 164 is provided with a plurality of coolant inlets 224 on its inner side facing the coolant passage opening 138 (see in particular Fig. 2).
[0095] Through the coolant inlets 224, the coolant passes from the coolant passage opening 138 into the interior of the coolant sealing bead 164.
[0096] In the embodiment illustrated in the drawing, the edge 228 of the coolant passage opening 138 is rectangular. However, the number of corners of the polygonal edge 228 of the coolant passage opening 138 can also be greater or less than four.
[0097] Coolant outlets 225, which are arranged on the outer side of the coolant sealing bead 164 facing away from the coolant passage opening 138 and through which the coolant flows out of the interior of the coolant sealing bead 164, are preferably all arranged on a section 230 of the coolant sealing bead 164 which faces the electrochemically active region 114 of the bipolar plate 114.
[0098] Preferably, the coolant inlets 224, which are arranged on the same section 230 of the coolant sealing bead 164, are arranged offset from the coolant outlets 225 along the circumferential direction of the coolant sealing bead 164.
[0099] The coolant flows through the coolant outlets 225 into a coolant distribution region 242 of the bipolar plate 100, which serves to distribute the coolant as evenly as possible among the coolant flow channels of the coolant flow field. In this coolant distribution region 242, the anode-side bipolar plate layer 122 and the cathode-side bipolar plate layer 124 are offset in opposite directions along the stacking direction 104 relative to a longitudinal center plane of the bipolar plate 100 oriented perpendicular to the stacking direction 104, such that a large cross-section is available for the flow of the coolant through the coolant distribution region 242.
[0100] The bipolar plate 100 is preferably rotationally symmetrical with respect to a rotation of 180° about an axis of rotation extending through the center of the electrochemically active region 114 of the bipolar plate 100 and parallel to the stacking direction 104 (z-direction).
[0101] The medium passage openings 130 arranged in the second end region 112b, in particular the anode gas passage opening 134 arranged there, the cathode gas passage opening 136 arranged there and the coolant passage opening 138 arranged there, are therefore preferably constructed and arranged essentially in the same way as the anode gas passage opening 134, the cathode gas passage opening 136 and the coolant passage opening 138 in the first end region 112a, which have been described above.
[0102] With the bipolar plate 100 shown in Figs. 1 to 14 and described above, the aim is to distribute the anode gas flowing out of the anode gas outlets 154 on the anode gas sealing bead 142 as evenly as possible to the distribution channels 173 of the anode gas distribution region 170 formed between the directed distribution structures 172 and to distribute the cathode gas flowing out of the cathode gas outlets 214 on the cathode gas sealing bead 162 as evenly as possible to the distribution channels 219 of the cathode gas distribution region 216 formed between the directed distribution structures 220. For this purpose, bypass channels 288 are formed on the distributor structures 132 of the anode gas distribution region 170, through which two adjacent distributor channels 173 of the anode gas distribution region 170 are in fluid communication with each other (see in particular Figs. 3, 4 and 7).
[0103] Likewise, a bypass channel 288 is formed on each of the distributor structures 220 of the cathode gas distribution region 216, through which two adjacent distributor channels 219 of the cathode gas distribution region 216 are in fluid communication with each other.
[0104] Through the bypass channels 288 in the anode gas distribution area 170, anode gas can flow from a distribution channel 173, into which an above-average amount of anode gas flows out from the anode gas outlets 154, into an adjacent distribution channel 173, which receives less anode gas from the anode gas outlets 154.
[0105] Likewise, through the bypass channels 288 in the cathode gas distribution area 216, cathode gas can flow from a distribution channel 219, which receives an above-average amount of cathode gas from the cathode gas outlets 214, into an adjacent distribution channel 219, which receives less cathode gas from the cathode gas outlets 214.
[0106] In this way, the supply of the distribution channels 173, 219 with anode gas or cathode gas is made uniform.
[0107] As a result, the anode gas flow channels 126 of the anode gas flow field 116, which are supplied with anode gas by the anode gas distribution region 170, and the cathode gas flow channels 128 of the cathode gas flow field 118, which are supplied with cathode gas by the cathode gas distribution region 216, are more evenly supplied with anode gas and cathode gas, respectively. As best seen from the perspective views of Figs. 4 and 11, the bypass channels 288 are formed by a local depression of the distributor structure 172 or 220, on which the respective bypass channel 288 is formed.
[0108] The local lowering of the distributor structure 172, 220 preferably corresponds to at least 5%, in particular at least 10%, particularly preferably at least 20%, of the height of the locally lowered distributor structure 172, 220 in a non-lowered section 290 of the respective distributor structure 172, 220, which is adjacent to the respective bypass channel 288.
[0109] Furthermore, it is preferably provided that the local lowering of the distributor structure 172, 220, on which the respective 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 locally lowered distributor structure 172, 220 in a non-lowered section 290 of the respective distributor structure 172, 220.
[0110] It is preferably provided that the local reduction is at least 20 pm, in particular at least 40 pm, particularly preferably at least 80 pm.
[0111] Furthermore, it is preferably provided that the local reduction is at most 380 pm, in particular at most 360 pm, particularly preferably at most 320 pm, for example at most 200 pm.
[0112] The extension of the local depression and thus of the bypass channel 288 in the longitudinal direction of the respective locally lowered distributor structure 172, 220 is preferably at most 1.5 mm. This prevents a component of an electrochemical unit 102 supported by the respective distributor structure 172, 220, for example a gas diffusion layer or a component of a sealing arrangement of an electrochemical unit 102, from being insufficiently supported by the respective distributor structure 172, 220 and thus bulging into the respective bypass channel 288, which would undesirably reduce the flow-through cross-section of the respective bypass channel 288.
[0113] Each anode gas outlet 154 on the anode gas sealing bead 142 is assigned a first-order distribution channel 173a of the anode gas distribution region 170, which is arranged and aligned relative to the anode gas outlet 154 such that the largest portion of the anode gas flowing out of the anode gas outlet 154 flows into this first-order distribution channel 173a.
[0114] Each first-order distribution channel 173a of the anode gas distribution region 170 is adjacent to two second-order distribution channels 173b, and each of the second-order distribution channels 173b is adjacent to one third-order distribution channel 173c, wherein each second-order distribution channel 173b receives less anode gas from the anode gas outlets 154 than a first-order distribution channel 173a, and wherein each third-order distribution channel 173c receives less anode gas from the anode gas outlets 154 than a second-order distribution channel 173b.
[0115] Each first-order distribution channel 173a is in fluid communication with one of the adjacent second-order distribution channels 173b via a first-order bypass channel 288a.
[0116] Each of the second-order distribution channels 173b is in fluid communication with an adjacent third-order distribution channel 173c via a second-order bypass channel 288b.
[0117] Third-order distribution channels 173c can each be fluidly connected to an adjacent third-order distribution channel 173c via a third-order bypass channel 288c. To distribute the anode gas as evenly as possible among the different-order distribution channels 173a, 173b, and 173c, more anode gas must flow through the first-order bypass channels 288a than through the second-order bypass channels 288b.
[0118] The first-order bypass channels 288a therefore each have a larger flow-through cross-section than the second-order bypass channels 288b.
[0119] The second-order bypass channels 288b preferably have a larger flow-through cross-section than the third-order bypass channels 288c.
[0120] As best seen in Fig. 3, the second-order bypass channels 288b overlap at least partially with the adjacent first-order bypass channels 288a, as viewed in a direction perpendicular to the longitudinal direction of the first-order distribution channel 173a and perpendicular to the stacking direction 104.
[0121] This ensures that the anode gas which has flowed through a first-order bypass channel 288a can also flow through the second-order bypass channel 288b without changing the flow direction or with only a slight change in the flow direction.
[0122] For the same reason, it is advantageous for the bypass channels 288 to at least partially overlap with at least one bypass channel 288 formed in an adjacent distributor structure 172—in a direction oriented perpendicular to the longitudinal direction of the distributor structure 172, in which the bypass channels 288 are each formed, and perpendicular to the stacking direction 104. The distances of the bypass channels 288 from an end 292 of the respective distributor structure 172, facing away from the electrochemically active region 114 of the bipolar plate 100, on which the respective bypass channel 288 is formed, along the longitudinal direction of this distributor structure 172, are greater than the extent of the respective bypass channel 288 along the longitudinal direction of the distributor structure 172.
[0123] Each cathode gas outlet 214 on the cathode gas sealing bead 162 is assigned a first-order distribution channel 219a of the cathode gas distribution region 216, which is arranged and aligned relative to the cathode gas outlet 214 such that the largest portion of the cathode gas flowing out of the cathode gas outlet 214 flows into this first-order distribution channel 219a.
[0124] Each first-order distribution channel 219a of the cathode gas distribution region 216 is adjacent to two second-order distribution channels 219b, and each of the second-order distribution channels 219b can be adjacent to another second-order distribution channel 219b, wherein each second-order distribution channel 219b receives less cathode gas from the cathode gas outlets 214 than a first-order distribution channel 219a.
[0125] Each first-order distribution channel 219a is in fluid communication with one of the adjacent second-order distribution channels 219b via a first-order bypass channel 288a.
[0126] Second-order distribution channels 219b can each be in fluid communication with an adjacent further second-order distribution channel 219b via a second-order bypass channel 288b.
[0127] To distribute the cathode gas as evenly as possible between the distribution channels of different orders 219a and 219b, more cathode gas must flow through the first-order bypass channels 288a than through the second-order bypass channels 288b. The first-order bypass channels 288a therefore each have a larger flow-through cross-section than the second-order bypass channels 288b.
[0128] As best seen in Fig. 10, the second-order bypass channels 288b overlap at least partially with the adjacent first-order bypass channels 288a, as viewed in a direction perpendicular to the longitudinal direction of the first-order distribution channel 219a and perpendicular to the stacking direction 104.
[0129] This ensures that the cathode gas which has flowed through a first-order bypass channel 288a can also flow through the second-order bypass channel 288b without changing the flow direction or with only a slight change in the flow direction.
[0130] For the same reason, it is favorable that the bypass channels 288 overlap at least partially with at least one bypass channel 288 formed in an adjacent distributor structure 220 in a direction oriented perpendicular to the longitudinal direction of the distributor structure 220, in which the bypass channels 288 are each formed, and perpendicular to the stacking direction 104.
[0131] The distances of the bypass channels 288 from an end 292 of the respective distributor structure 220 facing away from the electrochemically active region 114 of the bipolar plate 100, on which the respective bypass channel 288 is formed, along the longitudinal direction of this distributor structure 220, are greater than the extent of the respective bypass channel 288 along the longitudinal direction of the distributor structure 220.
Claims
Patent claims Bipolar plate for an electrochemical unit (102) of an electrochemical device (106) comprising a plurality of electrochemical units (102) arranged one after the other along a stacking direction (104), wherein the bipolar plate (100) comprises: an anode gas passage opening (134) forming part of an anode gas channel extending through the electrochemical device (106) along the stacking direction (104); a cathode gas passage opening (136) forming part of a cathode gas channel extending through the electrochemical device (106) along the stacking direction (104); an electrochemically active region (114) of the bipolar plate (100) which comprises an anode gas flow field (116) through which the anode gas can flow and a cathode gas flow field (118) through which the cathode gas can flow;an anode gas distribution region (170), via which the anode gas passage opening (134) is in fluid communication with the anode gas flow field (116); and a cathode gas distribution region (216), via which the cathode gas passage opening (136) is in fluid communication with the cathode gas flow field (118); wherein the anode gas distribution region (170) and / or the cathode gas distribution region (216) comprises distributor structures (172, 220) extending along a flow direction of the anode gas or the cathode gas, respectively, which delimit distributor channels (173, 219) formed between each two distributor structures (172, 220), 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) through which two adjacent distribution channels (173, 219) are in fluid communication with one another. Bipolar plate according to claim 1, characterized in that the at least one bypass channel (288) is formed by a local depression of one of the distribution structures (172, 220). Bipolar plate according to claim 2, characterized in that the local depression corresponds to at least 5% of the height of the locally lowered distribution structure (172, 220) in a non-lowered section (290) of the distribution structure (172, 220). Bipolar plate according to one of claims 2 or 3, characterized in that the local depression corresponds to at most 95% of the height of the locally lowered distributor structure (172, 220) in a non-lowered section (290) of the distributor structure (172, 220).Bipolar plate according to one of claims 2 to 4, characterized in that the local depression is at least 20 pm. Bipolar plate according to one of claims 2 to 5, characterized in that the local depression is at most 380 pm. Bipolar plate according to one of claims 2 to 6, characterized in that the extent of the local depression in the longitudinal direction of the locally depressed distributor structure (172, 220) is at most 1.5 mm. Bipolar plate according to one of claims 2 to 7, characterized in that the anode gas passage opening (134) is surrounded by an anode gas sealing bead (142), on the outer side of which anode gas outlet (154) is arranged, facing away from the anode gas passage opening (134), and the cathode gas passage opening (136) is surrounded by a cathode gas sealing bead (162), on the outer side of which a cathode gas outlet (214) is arranged, facing away from the cathode gas passage opening (136), wherein the largest portion of the anode gas flowing out of the anode gas outlet (154) flows into a first-order distribution channel (173a) of the anode gas distribution region (170) and / or the largest portion of the anode gas flowing out of the cathode gas outlet (214) outflowing cathode gas flows into a first-order distribution channel (219a) of the cathode gas distribution area (216), wherein the respective first-order distribution channel (173a, 219a) is assigned two second-order distribution channels (173b,219b) are adjacent and the respective second-order distribution channels (173b, 219b) are each adjacent to a third-order distribution channel (173c) or a further second-order distribution channel (219b), wherein the respective first-order distribution channel (173a, 219a) is in fluid communication with the second-order distribution channels (173b, 219b) via a first-order bypass channel (288a) and the second-order distribution channels (173b, 219b) are each in fluid communication with one of the third-order distribution channels (173c) or with a further second-order distribution channel (219b) via a second-order bypass channel (288b), and wherein the first-order bypass channels (288a) each have a larger flow-through cross-section than the second-order bypass channels (288b). Bipolar plate according to claim 8, characterized in that the second-order bypass channels (288b) - viewed in a direction oriented perpendicular to the longitudinal direction of the first-order distribution channel (173a, 219a) and perpendicular to the stacking direction (104) - at least partially overlap with the respectively adjacent first-order bypass channels (288a). Bipolar plate according to one of claims 1 to 9, characterized in that at least one bypass channel (288) - viewed in a direction oriented perpendicular to the longitudinal direction of the distribution structure (172, 220) on which the respective bypass channel (288) is formed, and perpendicular to the stacking direction (104) - at least partially overlaps with at least one bypass channel (288) formed in an adjacent distribution structure (172, 220).Bipolar plate according to one of claims 1 to 10, characterized in that more than half of the directed distributor structures (172) of the anode gas distribution region (170) and / or more than half of the directed distributor structures (220) of the cathode gas distribution region (216) are each provided with at least one bypass channel (288). Bipolar plate according to one of claims 1 to 11, characterized in that all directed distributor structures (172) of the anode gas distribution region (170) and / or all directed distributor structures (220) of the cathode gas distribution region (216) are each provided with at least one bypass channel (288). Bipolar plate according to one of claims 1 to 12, characterized in that at least one distributor structure (172) of the anode gas distribution region (170) and / or at least one distributor structure (220) of the. Cathode gas distribution area (216) is provided with two or more bypass channels (288) spaced apart from one another in the longitudinal direction of the respective distributor structure (172, 220). Bipolar plate according to one of claims 1 to 13, characterized in that at least one distributor structure (172) of the anode gas distribution region (170) and / or at least one distributor structure (220) of the cathode gas distribution region (216) is provided with a bypass channel (288), the distance of which from an end (292) of the respective distributor structure (172, 220) facing away from the electrochemically active region (114) of the bipolar plate (100) along the longitudinal direction of the distributor structure (172, 220) is greater than the extent of the bypass channel (288) along the longitudinal direction of the distributor structure (172, 220).Electrochemical device comprising a plurality of electrochemical units (102) which follow one another along a stacking direction (104) and each comprise a bipolar plate (100) according to one of claims 1 to 14.