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 which follow one another in the stacking direction, the bipolar plate comprising the following:-at least one dielectric through-opening, the at least one media passage opening forms a component of a media channel extending through the electrochemical device in the stacking direction; -a sealing bead extending around the media through-opening; a plurality of medium inlets, which are arranged on the inner side of the sealing rib facing the medium passage opening and allow a medium to flow into the inner space of the sealing rib; and-a plurality of medium outlets, which are arranged on the outer side of the sealing bead facing away from the medium passage opening and enable a medium to flow out of the interior of the sealing bead, the pressure loss occurring when the medium flows through the medium inlet, the interior of the sealing bead and the medium outlet from the medium passage opening is as low as possible, and wherein the medium preferably flows out of the medium outlet in a manner that the medium is distributed as uniformly as possible over the medium inlet region of the medium distribution region. The cross-section through which the total medium inlet can flow is at least 10% larger than the cross-section through which the total medium outlet can flow.

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: at least one medium passage opening, which forms part of a medium channel extending through the electrochemical device in the stacking direction; - Sealed ribs, which extend around the medium-through opening; - a plurality of medium inlets, which are arranged on the inner side of the sealing rib facing the medium through-opening and enable the medium to flow into the inner space of the sealing rib; and A plurality of medium outlets are arranged on the outer side of the sealing rib facing away from the medium through-opening and enable the medium to flow out of the inner space of the sealing rib. Background Art

[0002] The media inlet and the media outlet are also referred to as gas ports, through which the interior of the sealing rib is in fluid connection with the media through-opening or with the exterior space surrounding the sealing rib.

[0003] These medium inlets and medium outlets or gas ports are arranged on the sides of the sealing ribs and enable the respective media to enter the medium distribution area from the respective media channels and from there into the medium flow field of the bipolar plate.

[0004] In the case of known bipolar plates of the type mentioned in the introduction, there are as many medium inlets as medium outlets. Summary of the invention

[0005] Based on this prior art, the object of the present invention is to provide a bipolar plate of the type mentioned at the beginning, in which the pressure loss occurring when the medium flows from the medium through-opening through the medium inlet, the internal space of the closed rib and the medium outlet is as low as possible, wherein, preferably, the medium flows out from the medium outlet in a manner that is distributed as evenly as possible on the medium inlet area of ​​the medium distribution area.

[0006] According to the invention, this object is achieved in a bipolar plate for an electrochemical cell of an electrochemical device having the features of the preamble of claim 1 in that the total medium inlet cross section through which the medium can flow is at least 10% larger than the total medium outlet cross section through which the medium can flow.

[0007] The cross sections through which the medium inlet and the medium outlet can flow are taken here along a plane which is oriented parallel to the stacking direction and perpendicular to the mean flow direction of the medium through the relevant medium inlet or medium outlet.

[0008] The solution according to the invention is based on the concept that the inner space of the sealed rib is filled with the relevant medium. Since the cross-section through which the inner space of the sealed rib can flow is significantly larger than the cross-section through which the medium inlet and the medium outlet can flow, the flow resistance within the sealed rib will hardly cause a pressure drop in the medium when the medium flows from the medium through-opening to the outside of the sealed rib. By increasing the cross-section through which the total medium inlet can flow, the maximum medium flow is achieved at the medium outlet outside the sealed rib.

[0009] The average flow velocity when passing through the medium inlet is made lower, which will reduce the pressure drop in the medium at the medium inlet and also reduce the total pressure drop when the medium passes through the medium through-opening to the outside of the closed pressure rib. Thus, the total pressure drop is basically determined by the flow resistance at the medium outlet.

[0010] It is particularly advantageous if the total cross-sectional area through which the medium can flow is at least 15%, preferably at least 20%, greater than the total cross-sectional area through which the medium can flow.

[0011] In principle, the cross-sectional area through which the media inlet can flow can be influenced by selecting the number of media inlet openings and by selecting the size of the cross-sectional area through which the media inlet can flow.

[0012] Likewise, the total cross-sectional area through which the media outlet can flow can be influenced by selecting the number of media outlets and by selecting the size of the cross-sectional area through which the media outlet can flow.

[0013] In a preferred design of the present invention, it is provided that, on the same sealed pressure rib, the number of medium inlets is greater than the number of medium outlets.

[0014] In this case, the average cross-sectional area through which the medium inlet can flow can be substantially the same size as the average cross-sectional area through which the medium outlet can flow.

[0015] It is particularly advantageous if the number of the medium inlets is two or more greater than the number of the medium outlets.

[0016] The medium inlet is preferably arranged offset relative to the medium outlet along the circumferential direction of the sealing rib.

[0017] In a preferred design scheme of the present invention, it is provided that the bipolar plate includes an electrochemically active area, the electrochemically active area includes an anode gas flow field through which the anode gas can flow, a cathode gas flow field through which the cathode gas can flow, and a coolant flow field through which the coolant can flow, wherein the bipolar plate includes a medium distribution area, and the medium through-opening is in fluid connection with the electrochemically active area of ​​the bipolar plate via the medium distribution area.

[0018] The anode gas enters the anode of the membrane electrode assembly from the anode gas flow field of the electrochemically active region (if necessary, passing through the gas diffusion layer on the anode side). The cathode gas enters the cathode of the membrane electrode assembly from the cathode gas flow field of the electrochemically active region (if necessary, passing through the gas diffusion layer on the cathode side). Therefore, the region of the bipolar plate including the anode gas flow field and the cathode gas flow field is called the electrochemically active region, even though no electrochemical reaction occurs in the bipolar plate itself.

[0019] Preferably, at least one media outlet is arranged on the sealing rib and oriented in such a way that the medium flows out of the media outlet in a manner directed toward the media inlet region of the media distribution region.

[0020] For example, it can be provided that a plurality of media outlets are arranged on a distribution area section of the sealing rib, which distribution area section is located opposite a media inlet area of ​​the media distribution area.

[0021] It is particularly advantageous if all media outlets of the sealing rib are arranged on a distribution region section of the sealing rib which is opposite the media inlet region of the media distribution region.

[0022] Furthermore, at least one medium inlet is preferably arranged on the sealing rib outside a distribution area section of the sealing rib.

[0023] It is particularly advantageous if at least two media inlets, in particular at least three media inlets, particularly preferably at least four media inlets are arranged on the sealing rib outside a distribution area section of the sealing rib.

[0024] In a preferred design of the present invention, all media outlets are arranged on a media outlet section of the sealed rib, which starts at a first media outlet on the outside and ends at a second media outlet on the outside. Then, all other media outlets are located between the first media outlet on the outside and the second media outlet on the outside in a manner distributed along the circumference of the sealed rib.

[0025] In this case, it is advantageous if at least one media inlet is arranged on the sealing rib outside of a media outlet section of the sealing rib.

[0026] Preferably, at least two media inlets, in particular at least three media inlets, particularly preferably at least four media inlets are arranged on the sealing rib outside the media outlet section.

[0027] The longitudinal direction of the bipolar plate extends parallel to the main flow direction of the medium through the medium flow field associated with the bipolar plate. Preferably, at least one medium inlet is arranged and oriented on the sealing rib so that the medium flows into the inner space of the sealing rib substantially perpendicularly to the longitudinal direction of the bipolar plate through the medium inlet.

[0028] The longitudinal direction of the bipolar plate is preferably oriented parallel to the long sides of the essentially rectangular bipolar plate (seen in a plan view in the stacking direction).

[0029] In order not to negatively influence the mechanical stability and the spring properties of the sealing rib in its curved section, it is advantageous if no medium inlet is arranged on the curved section of the edge of the medium passage opening.

[0030] This achieves uniform squeezing of the closed compression ribs.

[0031] The cross section of the sealing rib through which flow can be passed is preferably greater than the average cross section through which flow can be passed of the medium flow channels of the medium flow field of the bipolar plate associated with the medium.

[0032] The medium through-opening (for which the associated sealing rib applies, the total through-flow cross-section of the medium inlet is at least 10% larger than the total through-flow cross-section of the medium outlet) can be an anode gas through-opening, a cathode gas through-opening or a coolant through-opening of the bipolar plate.

[0033] It is particularly advantageous that for all sealing ribs at the anode gas through-opening, the cathode gas through-opening and the coolant through-opening, the total flow-through cross-section of the medium inlet on the respectively assigned sealing rib is at least 10% larger than the total flow-through cross-section of the medium outlet.

[0034] Therefore, in a preferred design of the present invention, the anode gas through-opening, the cathode gas through-opening and the coolant through-opening of the bipolar plate are respectively surrounded by closed ribs on which the medium inlet and the medium outlet are arranged, wherein the total medium inlet cross-section that can flow through on each of these closed ribs is at least 10% larger, in particular at least 15% larger, and particularly preferably at least 20% larger than the total medium outlet cross-section that can flow through on the respective closed ribs.

[0035] The bipolar plate according to the invention is particularly suitable as a component of an electrochemical device which comprises a plurality of electrochemical cells which follow one another in the stacking direction and which each comprise a bipolar plate according to the invention.

[0036] Such an electrochemical device may be, for example, a fuel cell device or an electrolysis apparatus.

[0037] In a preferred embodiment of the invention, it is provided that the electrochemical device is designed as a polymer electrolyte membrane (PEM) fuel cell device. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Further features and advantages of the invention are the subject of the following description of embodiments and the accompanying drawings, in which:

[0039] Figure 1 A top view of an end region of a bipolar plate of an electrochemical cell for an electrochemical device is shown in a viewing direction directed toward the cathode side of the bipolar plate, the electrochemical device comprising a plurality of electrochemical cells following one another in a stacking direction, wherein the bipolar plate comprises a plurality of medium through-openings, each of which forms a component of a medium channel extending through the electrochemical device in the stacking direction, the medium through-openings each comprising a sealing rib, the sealing rib extending around the medium through-opening; each comprising a plurality of medium inlets, which are arranged on the inner side of the sealing rib facing the medium through-opening and enable the medium to flow into the inner space of the sealing rib; and each comprising a plurality of medium outlets, which are arranged on the outer side of the sealing rib facing away from the medium through-opening and enable the medium to flow out of the inner space of the sealing rib, wherein the total flowable cross-section of the medium inlets is at least 10% larger than the total flowable cross-section of the medium outlets;

[0040] Figure 2 The viewing direction is shown pointing to the anode side of the bipolar plate. Figure 1 A top view of an end region of a bipolar plate;

[0041] Figure 3 Shows Figure 1 and Figure 2 A top view of the inner side of an end region of a bipolar plate layer on the anode side of a bipolar plate; and

[0042] Figure 4 Shows Figure 1 and Figure 2 A top view of the inner side of an end region of a bipolar plate layer on the cathode side of a bipolar plate.

[0043] In all figures, identical or functionally equivalent elements are marked with the same reference numerals. DETAILED DESCRIPTION

[0044] Figures 1 to 4 The bipolar plate shown in the middle section and designated as a whole 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.

[0045] 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.

[0046] 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 .

[0047] The longitudinal direction 108 and the transverse direction 110 are preferably oriented perpendicularly to one another and perpendicularly to the stacking direction 104 .

[0048] 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.

[0049] The x-direction, y-direction and z-direction develop a rectangular coordinate system.

[0050] The bipolar plate 100 has two end regions 112 and an electrochemically active region 114 located between the end regions 112 .

[0051] 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.

[0052] 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.

[0053] The bipolar plate layers 122 and 124 are made of a material that is good at conducting electricity, preferably a metal material.

[0054] 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.

[0055] 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).

[0056] 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).

[0057] Therefore, the anode gas and the cathode gas can enter the electrochemically active region of each membrane electrode assembly 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.

[0058] The anode gas flow field 116 includes anode gas flow channels 126 , the main flow direction of which is oriented parallel to the longitudinal direction 108 (x-direction) of the bipolar plate 100 .

[0059] The cathode gas flow field 118 includes cathode gas flow channels 128 , the main flow direction of which is oriented parallel to the longitudinal direction 108 (x-direction) of the bipolar plate 100 .

[0060] The bipolar plate 100 has an end region 112 ( Figures 1 to 4 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.

[0061] 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 .

[0062] 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 .

[0063] exist Figures 1 to 4 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.

[0064] 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 .

[0065] 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.

[0066] 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.

[0067] 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 .

[0068] The anode gas through-opening 134 is surrounded by an anode gas sealing rib 142 .

[0069] 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 ).

[0070] The anode gas inlet 144 opens in each case at an edge 146 of the anode gas passage opening 134 .

[0071] It is preferably provided that the anode gas inlet 144 opens into each of the rectilinear edge sections 148 , 150 and 152 of the anode gas through-opening 134 .

[0072] The straight edge section 148 extends obliquely to the longitudinal direction 108 (x-direction) of the bipolar plate 100 and obliquely to the transverse direction 110 (y-direction) and preferably faces the electrochemically active region 114 of the bipolar plate 100 .

[0073] Arranged at the edge section 148 are a plurality of, preferably at least three, in the exemplary embodiment shown, four anode gas inlets, through which the anode gas flows, preferably perpendicularly to the longitudinal direction 108 (x direction) of the bipolar plate 100 , into the interior of the anode gas containment rib 142 .

[0074] The rectilinear edge section 150 preferably extends substantially parallel to the longitudinal direction 108 (x direction) of the bipolar plate 100 and preferably faces the coolant passage 138 .

[0075] One or more anode gas inlets 144 , in the exemplary embodiment shown, two anode gas inlets 144 , open into the edge section 150 .

[0076] The straight edge section 152 preferably extends substantially parallel to the longitudinal direction 108 (x direction) of the bipolar plate 100 and preferably faces away from the coolant passage 138 .

[0077] One or more anode gas inlets 144 , in the exemplary embodiment shown, two anode gas inlets 144 , are preferably introduced into the edge section 152 , through which the anode gas preferably flows perpendicularly to the longitudinal direction 108 (x direction) of the bipolar plate 100 into the interior of the anode gas sealing rib 142 .

[0078] Furthermore, the edge 146 of the anode gas through-opening 134 also comprises a straight edge section 153 , which is preferably oriented obliquely to the longitudinal direction 108 (x-direction) of the bipolar plate 100 and obliquely to the transverse direction 110 (y-direction) of the bipolar plate 100 and preferably faces away from the electrochemically active region 114 of the bipolar plate 100 .

[0079] Preferably, no anode gas inlet 144 opens into the edge section 153 .

[0080] The edge sections 148 , 150 , 152 and 153 together form the polygonal edge 146 of the anode gas through-opening 134 .

[0081] 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.

[0082] 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.

[0083] 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 .

[0084] 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 .

[0085] The section 156 of the anode gas sealing rib 142 preferably extends substantially parallel to the straight edge section 148 of the edge 146 of the anode gas through-opening 134 and substantially parallel to the rounded corner regions 157a and 157b of the edge 146 which connect the straight edge section 148 to the edge section 150 or to the edge section 152 .

[0086] In this case, a plurality of anode gas outlets 154 , preferably at least four, in the exemplary embodiment shown, six, are preferably arranged on the section 156 .

[0087] 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 .

[0088] In addition, the anode gas sealing rib 142 also includes further sections 158a, 158b and 160, which are respectively oriented substantially parallel to straight edge sections 150 and 152 extending parallel to the longitudinal direction 108 of the bipolar plate 100 or substantially parallel to a straight edge section 153 of the edge 146 of the anode gas through-opening 134 facing away from the electrochemically active region 114.

[0089] 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 region 170 , which is used to distribute the anode gas as evenly as possible into the anode gas flow channels 126 of the anode gas flow field 116 .

[0090] 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.

[0091] In this case, the directional distributing structure 172 is designed, for example, as a distributing rib 176 extending essentially linearly.

[0092] The non-directional distributing structure 174 is designed, for example, as a substantially bowl-shaped distributing projection 178 .

[0093] 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.

[0094] The cathode gas through-opening 136 is surrounded by a cathode gas sealing rib 162 .

[0095] The coolant passage opening 138 is surrounded by a coolant-tightening rib 164 .

[0096] An annularly closed edge rib 182 surrounds the outer edge 180 of the bipolar plate 100 .

[0097] 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 .

[0098] 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 .

[0099] 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 Figure 1 ).

[0100] 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 .

[0101] The cathode gas inlet 194 preferably opens at rectilinear edge sections 196 , 202 and 204 of the edge 198 of the cathode gas through-opening 136 .

[0102] The straight edge section 196 preferably extends obliquely to the longitudinal direction 108 (x direction) of the bipolar plate 100 and to the transverse direction 110 (y direction) of the bipolar plate 100 and preferably faces the electrochemically active region 114 of the bipolar plate 100. A plurality of cathode gas inlets 194 preferably open into the edge section 196, in particular at least four, in the exemplary embodiment shown, six.

[0103] The straight edge section 202 preferably extends substantially parallel to the longitudinal direction 108 (x direction) of the bipolar plate 100 and preferably faces the coolant passage 138. One or more cathode gas inlets 194, in the illustrated embodiment two cathode gas inlets 194, preferably lead into the edge section 202, through which the cathode gas preferably flows perpendicularly to the longitudinal direction 108 (x direction) of the bipolar plate 100 into the interior of the cathode gas sealing rib 162.

[0104] The straight edge section 204 preferably extends substantially parallel to the longitudinal direction 108 (x direction) of the bipolar plate 100 and preferably faces the edge ridge 182 .

[0105] One or more cathode gas inlets 194 , in the exemplary embodiment shown, two cathode gas inlets 194 , open into the edge section 204 , through which cathode gas flows, preferably perpendicularly to the longitudinal direction 108 (x direction) of the bipolar plate 100 , into the interior of the cathode gas sealing rib 162 .

[0106] Furthermore, the edge 198 of the cathode gas channel 136 may also include a rectilinear edge section 206 extending substantially parallel to the transverse direction 110 (y-direction) of the bipolar plate 100 , preferably facing away from the electrochemically active region 114 of the bipolar plate 100 .

[0107] The edge segments 196 , 202 , 204 and 206 together form a polygonal edge 198 of the cathode gas through-opening 136 .

[0108] 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 greater than four.

[0109] A plurality of cathode gas outlets 214, for example four or more, preferably six or more, and in the illustrated embodiment eight, are arranged on the outer side of the section 200 of the cathode gas sealing rib 162, which extends substantially parallel to the straight edge section 196 of the edge 198 of the cathode gas through-opening 136 and substantially parallel to the rounded corner areas 201a and 201b of the edge 198 connecting the straight edge section 196 with the edge section 202 or with the edge section 204.

[0110] In addition, the cathode gas sealing rib 162 also includes further sections 208, 210 and 212, which respectively extend substantially parallel to the straight edge sections 202 and 204 extending parallel to the longitudinal direction 108 of the bipolar plate 100, or substantially parallel to the straight edge section 206 of the edge 198 of the cathode gas through-opening 136 facing away from the electrochemically active area 114.

[0111] The cathode gas outlets 214 are preferably all arranged on the section 200 of the cathode gas containment rib 162 that faces the electrochemically active region 114 of the bipolar plate 100 .

[0112] 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 .

[0113] Preferably, a total of two or more, in particular four or more, in particular six or more, in the illustrated embodiment, eight cathode gas outlets 214 are provided on the cathode gas sealing rib 162 .

[0114] The cathode gas flows out through the cathode gas outlet 214 into the cathode gas distribution region 216 of the bipolar plate 100 . The cathode gas distribution region is used to distribute the cathode gas into the cathode gas flow channels 128 of the cathode gas flow field 118 as evenly as possible.

[0115] 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 .

[0116] The directional distributing structure 220 is preferably designed as a linearly extending distributing rib 222 .

[0117] The non-directional distributing structure 221 is designed, for example, as a substantially bowl-shaped distributing projection 223 .

[0118] 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 1 ).

[0119] The coolant enters the inner space of the coolant sealing rib 164 from the coolant through-opening 138 through the coolant inlet 224 .

[0120] The coolant inlet 224 preferably opens at the rectilinear edge sections 226 , 232 a and 232 b of the edge 228 of the coolant through-opening 138 .

[0121] The straight edge section 226 preferably extends substantially parallel to the transverse direction 110 (y direction) of the bipolar plate 100 and preferably faces the electrochemically active region 114 of the bipolar plate 100. A plurality of coolant inlets 224 preferably open into the edge section 226, in particular at least three, in the illustrated exemplary embodiment four.

[0122] The straight edge section 232a preferably extends substantially parallel to the longitudinal direction 108 (x direction) of the bipolar plate 100 and preferably faces the anode gas passage opening 134. One or more, in the illustrated embodiment, two coolant inlets 224 preferably open into the edge section 232a, through which the coolant preferably flows perpendicularly to the longitudinal direction 108 (x direction) of the bipolar plate 100 into the interior of the coolant sealing rib 164.

[0123] The straight edge section 232b preferably extends substantially parallel to the longitudinal direction 108 (x direction) of the bipolar plate 100 and preferably faces the cathode gas passage opening 136. One or more, in the illustrated embodiment, two coolant inlets 224 preferably open into the edge section 232b, through which the coolant preferably flows perpendicularly to the longitudinal direction 108 (x direction) of the bipolar plate 100 into the interior of the coolant sealing rib 164.

[0124] Furthermore, the edge 228 of the coolant passage opening 138 may also include a rectilinear edge section 234 extending substantially parallel to the transverse direction 110 (y-direction) of the bipolar plate 100 and preferably facing away from the electrochemically active region 114 of the bipolar plate 100. Preferably, no coolant inlet 224 opens into the edge section 234.

[0125] Edge sections 226, 232a, 232b and 234 together form a polygonal edge 228 of coolant through-opening 138, which is configured as a quadrilateral in the illustrated embodiment. However, the number of corners of polygonal edge 228 of coolant through-opening 138 may be more or less than four.

[0126] A plurality of, for example, three or more, preferably five or more, in the illustrated embodiment, seven coolant outlets 225 are arranged on a section 230 of the coolant-tightening rib 164, which extends substantially parallel to a straight edge section 226 of an edge 228 of the coolant through-opening 138 and substantially parallel to rounded corner regions 231a and 231b of the edge 228 that connect the straight edge section 226 to an edge section 232a or to an edge section 232b. The section 200 of the coolant-tightening rib 164 preferably faces the electrochemically active region 114 of the bipolar plate 100.

[0127] Preferably, the coolant inlets 224 arranged on the same section 230 of the coolant-tightening rib 164 are arranged offset relative to the coolant outlets 225 in the circumferential direction of the coolant-tightening rib 164 .

[0128] In addition to the section 230 provided with the coolant outlet 225 , the coolant-tightening rib 164 preferably also includes further sections 238 a , 238 b and 240 , which are each oriented substantially parallel to the edge section 232 a , 232 b or 234 of the edge 228 of the coolant passage 138 .

[0129] These further sections 238 a , 238 b and 240 of the coolant-tightening ribs 164 are preferably not provided with a coolant outlet 225 .

[0130] The coolant flows out through the coolant outlet 225 into the coolant distribution area 242 of the bipolar plate 100 . The coolant distribution area is used to distribute the coolant to the coolant channels of the coolant flow field as evenly as possible.

[0131] 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 that can be flowed through is available for the coolant flow through the coolant distribution area 242.

[0132] The bipolar plate 100 is preferably designed rotationally symmetrically about 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).

[0133] Therefore, the medium through-opening 130 arranged in the second end region 112, 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.

[0134] The anode gas inlet 144 is formed as a medium inlet 272 on the anode gas sealing rib 142 . The anode gas outlet 154 is formed as a medium outlet 274 on the anode gas sealing rib 142 .

[0135] The cathode gas inlet 194 is formed as a medium inlet 272 on the cathode gas sealing rib 162 . The cathode gas outlet 214 is formed as a medium outlet 274 on the cathode gas sealing rib 162 .

[0136] The coolant inlet 224 is formed at the medium inlet 272 on the coolant sealing rib 164 . The coolant outlet 225 is formed at the medium outlet 274 on the coolant sealing rib 164 .

[0137] use Figures 1 to 4 The bipolar plate 100 shown in and described above aims to reduce the pressure drop in the medium to be supplied to the electrochemical device 106 when passing through the respectively assigned sealing ribs 140. It is advantageous for this to be that the total flowable cross-section of the respective medium inlet 272 on the relevant sealing rib 140 is at least 10% larger, in particular at least 15% larger, particularly preferably at least 20% larger than the total flowable cross-section of the medium outlet 274 on the same sealing rib 140.

[0138] This can be achieved in particular by making the cross-section through which the medium inlet 272 on the sealing rib 140 can flow substantially the same as the cross-section through which the medium outlet 274 on the same sealing rib 140 can flow, but the number of the medium inlet 272 on the sealing rib 140 is greater than the number of the medium outlet 274. Preferably, the number of the medium inlet 272 is greater than the number of the medium outlet 274 by two or more.

[0139] Therefore, in the illustrated embodiment, eight anode gas inlets 144 are arranged on the inner side of the anode gas sealing rib 142 facing the anode gas through-opening 134, and six anode gas outlets 154 are arranged on the outer side of the anode gas sealing rib 142 facing away from the anode gas through-opening 134.

[0140] As a result, the pressure drop in the anode gas that occurs when the anode gas flows from the anode gas through-opening 134 through the anode gas sealing rib 142 into the anode gas distribution region 170 is significantly reduced.

[0141] In addition, in the illustrated embodiment of the bipolar plate 100, ten cathode gas inlets 194 are arranged on the inner side of the cathode gas sealing rib 162 facing the cathode gas through-opening 136, and eight cathode gas outlets 214 are arranged on the outer side of the cathode gas sealing rib 162 facing away from the cathode gas through-opening 136.

[0142] As a result, the pressure drop in the cathode gas that occurs when the cathode gas flows from the cathode gas through-opening 136 through the cathode gas sealing rib 162 into the cathode gas distribution region 216 is significantly reduced.

[0143] Furthermore, in the illustrated embodiment, eight coolant inlets 224 are arranged on the inner side of the coolant sealing rib 164 facing the coolant through-opening 138 , and seven coolant outlets 225 are arranged on the outer side of the coolant sealing rib 164 facing away from the coolant through-opening 138 .

[0144] As a result, the pressure drop in the coolant that occurs when the coolant flows from the coolant passage 138 through the coolant sealing rib 164 into the coolant distribution region 242 is significantly reduced.

[0145] The anode gas distribution region 170 forms a medium distribution region 276 for the anode gas.

[0146] The cathode gas distribution region 216 forms a medium distribution region 276 for the cathode gas.

[0147] The coolant distribution area 242 forms a medium distribution area 276 for the coolant.

[0148] Each of the media distribution areas 276 includes a media inlet area 278 , through which the respective media enters the respective media distribution area 276 .

[0149] That section of the sealing rib 140 which faces the electrochemically active region 114 of the bipolar plate 100 forms the distribution region section 280 of the respective sealing rib 140 .

[0150] The anode gas flow field 116 forms a medium flow field 282 for the anode gas.

[0151] The cathode gas flow field 118 forms a medium flow field 282 for the cathode gas.

[0152] The coolant flow field 120 forms a medium flow field 282 for the coolant.

[0153] Each of the medium flow fields 282 of the bipolar plate 100 includes medium flow channels 284 , which extend along a main flow direction of the medium through the associated medium flow field 282 .

[0154] What applies to all media inlets 272 is that they are preferably arranged offset relative to the respective media outlet 274 in the circumferential direction of the respective sealing rib 140 .

[0155] Each media outlet 274 is preferably arranged on a respective sealing rib 140 and oriented such that the medium flowing through the media outlet 274 flows out of the media outlet 274 in a directed manner toward the media inlet region 278 of the respectively associated media distribution region 276 .

[0156] Preferably, all media outlets 274 are arranged on a distribution area section 280 of the respective sealing rib 140 , which is opposite the media inlet area 278 of the respectively associated media distribution area 276 .

[0157] In each of the medium passage openings 130 , preferably at least one medium inlet 272 is arranged on the associated sealing rib 140 outside the distribution area section 280 of the respective sealing rib 140 .

[0158] Preferably, at least two, in particular at least three, particularly preferably at least four media inlets 272 are arranged in each medium passage opening 130 on the associated sealing rib 140 outside the distribution area section 280 of the respective sealing rib 140 .

[0159] At each of the sealing ribs 140 , a media outlet section 286 of the respective sealing rib 140 is defined in such a way that the media outlet section begins at an outer first media outlet 274 a and ends at an outer second media outlet 274 b .

[0160] Preferably, it is provided in each sealing rib 140 that at least one medium inlet 272 is arranged on the relevant sealing rib 140 outside the medium outlet section 286 of the respective sealing rib 140 .

[0161] A longitudinal direction 108 (x direction) of the bipolar plate 100 extends parallel to a main flow direction of a medium through a medium flow field 282 respectively associated with the medium.

[0162] Preferably, on each sealed rib 140, at least one medium inlet 272 is arranged and oriented on the respective sealed rib 140 so that the medium flows into the internal space of the respective sealed rib 140 through the relevant medium inlet 272 substantially perpendicular to the longitudinal direction 108 of the bipolar plate 100, that is, substantially parallel to the transverse direction 110.

[0163] In order not to negatively influence the mechanical stability and the spring properties of the sealing ribs in their curved sections, it is provided that no medium inlet 272 is arranged on the curved section of the edge of the respective medium passage opening 130 .

[0164] For each sealing rib 140 , it is applicable that the flow-through cross section of the respective sealing rib 140 is preferably greater than the average flow-through cross section of the medium flow channels 284 of the medium flow field 282 of the bipolar plate 100 associated with the respective medium.

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: at least one medium passage opening (130), which forms part of a medium channel (132) extending through the electrochemical device (106) in a stacking direction (104); - a sealed pressure rib (140), the sealed pressure rib extending around the medium through-opening (130); - a plurality of medium inlets (272), which are arranged on the inner side of the sealing rib (140) facing the medium through-opening (130) and enable the medium to flow into the inner space of the sealing rib (140); as well as - a plurality of medium outlets (274), which are arranged on the outer side of the sealing rib (140) facing away from the medium through-opening (130) and are capable of allowing the medium to flow out from the inner space of the sealing rib (140); It is characterized in that The total cross-sectional area through which the medium inlet (272) can flow is at least 10% larger than the total cross-sectional area through which the medium outlet (274) can flow.

2. The bipolar plate according to claim 1, characterized in that: The number of the medium inlets (272) is greater than the number of the medium outlets (274).

3. The bipolar plate according to any one of claims 1 or 2, characterized in that: The medium inlet (272) is arranged in a staggered manner relative to the medium outlet (274) along the circumferential direction of the sealing pressure rib (140).

4. The bipolar plate according to any one of claims 1 to 3, characterized in that: The bipolar plate (100) includes an electrochemically active region (114), the electrochemically active region including 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, wherein the bipolar plate (100) includes a medium distribution region (276), and the medium through-opening (130) is in fluid connection with the electrochemically active region (114) of the bipolar plate (100) via the medium distribution region.

5. The bipolar plate according to claim 4, characterized in that: At least one medium outlet (274) is arranged at the sealing rib (140) and oriented such that medium flows out of the medium outlet (274) in a direction toward a medium inlet region (278) of the medium distribution region (276).

6. The bipolar plate according to any one of claims 4 or 5, characterized in that: A plurality of media outlets (274) are arranged on a distribution area section (280) of the sealing rib (140), the distribution area section being opposite to a media inlet area (278) of the media distribution area (276).

7. The bipolar plate according to claim 6, characterized in that: At least one medium inlet (272) is arranged on the sealing rib (140) outside a distribution area section (280) of the sealing rib (140).

8. The bipolar plate according to any one of claims 1 to 7, characterized in that: All media outlets (274) are arranged on a media outlet section (286) of the sealing rib (140), which begins at a first outer media outlet (274a) and ends at a second outer media outlet (274b).

9. The bipolar plate according to claim 8, characterized in that: At least one medium inlet (272) is arranged on the sealing rib (140) outside a medium outlet section (286) of the sealing rib (240).

10. The bipolar plate according to any one of claims 1 to 9, characterized in that: The longitudinal direction (108) of the bipolar plate (100) extends parallel to a main flow direction of a medium through a medium flow field (282) associated with the bipolar plate (100), wherein at least one medium inlet (272) is arranged and oriented on the sealing rib (140) so that the medium flows into the inner space of the sealing rib (140) through the medium inlet (272) substantially perpendicularly to the longitudinal direction (108) of the bipolar plate (100).

11. The bipolar plate according to any one of claims 1 to 10, characterized in that: No medium inlet (272) is arranged on the curved section of the edge (146, 198, 228) of the medium passage opening (130).

12. The bipolar plate according to any one of claims 1 to 11, characterized in that: The cross section through which the sealing rib (140) can flow is larger than the average cross section through which the medium flow channel (284) of the medium flow field (282) of the bipolar plate (100) associated with the medium can flow.

13. The bipolar plate according to any one of claims 1 to 12, characterized in that: The medium through-opening (130) is an anode gas through-opening (134), a cathode gas through-opening (136) or a coolant through-opening (138).

14. The bipolar plate according to any one of claims 1 to 13, characterized in that: The anode gas through-opening (134), the cathode gas through-opening (136) and the coolant through-opening (138) of the bipolar plate (100) are respectively surrounded by a sealed rib (140) on which a medium inlet (272) and a medium outlet (274) are arranged. The total medium inlet (272) on each of the sealing ribs (140) has a flow-through cross section that is at least 10% larger than the total medium outlet (274) on the respective sealing rib (140).

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

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