DE102018114006A1 - Bipolar plate and fuel cell having a bipolar plate - Google Patents

Abstract

The present invention relates to a bipolar plate (10, 10 ') for mounting in a fuel cell (12), comprising a gas distributor element (14) having a plurality of channels (16) for distributing a reaction gas for operating the fuel cell (12) the gas distributor element (14) has a plurality of flow elements (20) juxtaposed in a main flow direction of the reaction gas, each flow element (20) along the main flow direction of the reaction gas forming a wavy metal strip with wave troughs (22) and wave crests (24) in that the wave troughs (22) and wave crests (24) of two adjacent flow elements (20) are offset relative to each other in the main flow direction, the wave troughs (22) of all flow elements (20) lying in a first plane (E1) and furthermore the wave crests (24) all flow elements (20) in a second plane (E2) lie, and wherein the troughs (22) and the wave crests (24) each form a planar abutment surface (16, 28) for contact with a counter-element.

Description

The present invention relates to a bipolar plate for a fuel cell. The present invention further relates to a fuel cell comprising such a bipolar plate.

Fuel cells are widely known as alternative energy converters. They usually comprise a bipolar plate which, for example, connects individual cells to a fuel cell stack in series as an essential part of a polymer electrolyte membrane fuel cell. In this case, a cell usually comprises a bipolar plate, a gas diffusion layer and a catalyst layer each on the cathode and anode side, which are electrically separated by a membrane. The bipolar plate has both on the anode side, as well as on the cathode side, a gas distributor field, which can be shaped differently. These distribution fields have the task of distributing the gases evenly, so that a homogeneous distribution in the catalyst layer is achieved. In the catalyst layer, the reaction proceeds with the participation of the reaction gases. In the catalyst layer of the cathode while water is formed, which occurs due to a temperature of less than 100 ° C and liquid. The membrane is permeable to water, so that liquid water can occur on both the cathode and on the anode side. The distribution field plate thus has in addition to the gas supply and the task of discharging the resulting water from the cell.

State of the art is that the shape of a bipolar plate is formed so that in each case channels are formed, through which the reaction gases flow and webs, which contact the gas diffusion layer and thus the catalyst layer electrically and thermally. Typically, under the webs colder and poorly traversed areas, which lead to water accumulation in these areas under humid operating conditions. This usually leads to a poorer performance of the fuel cell.

DE10 2007 009 905 A1 describes, for example, a fuel cell in which a fuel gas flow field is formed on a surface of a rectangular first metal separator. The fuel gas flow field includes flow grooves extending in the direction of gravity. An exhaust buffer is provided at the lower end of the fuel gas flow field. The outlet buffer includes a sloped surface that slopes toward the fuel gas discharge passage. The fuel gas discharge passage is located below the discharge buffer. Outlet channel grooves are formed by fins provided between the fuel gas discharge passage and the discharge buffer. Bottoms of the ribs are arranged in a zigzag pattern.

US 9,306,228 B2 describes a fuel cell having a gas passage for conducting oxygen gas. This gas channel has wave-shaped regions, which are arranged one above the other in the direction of flow of the gas.

DE 11 2009 001 377 T5 describes a gas flow path forming member for use in a fuel cell, wherein the gas flow path forming member is made of a metal grid structure formed of a thin metal plate, wherein a plurality of through holes in the metal grid structure are formed like a grid, the gas flow path forming member having a plurality of annular portions forming the through-holes, the annular portions each having a flat surface portion in a contact portion between the annular portion and the gas diffusion layer.

DE 11 2009 004 658 B4 describes a gas passage forming member for use in a fuel cell, wherein the gas passage forming member is made of an expanded metal, which is formed of a thin metal plate, wherein a plurality of ring portions, each having a through hole formed in the gas channel forming member and lattice-shaped Gas channel forming member is arranged, the ring portions are interconnected by connecting web portions, wherein each of the connecting web portions is inclined with respect to a flow direction of the gas, each connecting web portion has a first inclined plate portion, which is held against a rear side of the separator and a second inclined Plate portion which is held against a surface of the gas diffusion layer adjacent. In this case, only a linear contact between a gas channel forming element and a separator on the one hand or a gas diffusion layer on the other hand is formed. In the direction of a gas flow direction Pg, the gas channel formation element has a wave-shaped profile in the sectional view along such a linear contact.

DE 10 2015 207 397 A1 describes a porous channel structure for a fuel cell including a channel plate having a plurality of land portions contacting a gas diffusion layer (GDL) to form a wave-shaped cross-section in the flow direction of the gas, and a plurality of channel portions contacting a flat plate to provide watertightness; having a channel opening through which reaction gas flows. The channel opening is stamped to include a portion of at least one of a web portion of the plurality Includes web portions or a channel portion of the plurality of channel parts.

DE 10 2014 223 735 A1 describes a fuel cell comprising a catalyst layer at which hydrogen gas or air is introduced through its two surfaces; a first separator disposed on a first side of the catalyst layer and including a plurality of first channels so that a first reactant can flow under the hydrogen gas and the air; and a second separator disposed on the second side of the catalyst layer and including a plurality of second channels arranged in a direction perpendicular to the first channels. More specifically, each of the second channels includes a plurality of vents so that a second reactant can flow under the hydrogen gas and the air in a direction perpendicular to the second channels.

DE10 2014 224 025 A1 describes a fuel cell separator and a fuel cell with the fuel cell separator. The fuel cell separator includes inlets and outlets formed by first sides and second sides of the channels so that the reactant introduced into the channels flows perpendicular to the channels. In particular, the inlets are arranged higher than the outlets.

DE 10 2012 209 851 A1 describes a permeable separator for a fuel cell. The permeable separator includes a flow plate and a flat plate. The flow plate includes a first flow surface which is upwardly inclined and has a first plurality of flow openings, and a second flow surface which is downwardly inclined and has a second plurality of flow openings which are repeatedly arranged along a longitudinal direction of the flow plate. The flow plate is disposed between a gas diffusion layer of a fuel cell and a flat plate to seal the flow plate and to provide a flow path for hydrogen or air therein.

Such known from the prior art solutions can offer even further improvement potential, in particular with regard to the gas distribution, for example in combination with a cost-effective manufacturability.

It is the object of the present invention to at least partially overcome the disadvantages known from the prior art. In particular, it is the object of the present invention to provide a solution by means of which, in the case of a bipolar plate, an effective distribution of the inflowing gas is made possible and / or which can be produced cost-effectively.

The object is achieved according to the invention by a bipolar plate with the features of claim 1. The object is achieved according to the invention further by a fuel cell with the features of claim 9. Preferred embodiments of the invention are described in the subclaims, in the description or the figures, wherein further features described or shown in the subclaims or in the description or the figures, individually or in any combination, may constitute an object of the invention, if the context does not clearly indicate otherwise.

It is proposed a bipolar plate for arrangement in a fuel cell, comprising a gas distributor element, which has a plurality of channels for distributing a reaction gas for operating the fuel cell, wherein the gas distributor element has a plurality of juxtaposed in a main flow direction of the reaction gas flow elements, each flow element along the main flow direction of the reaction gas has a waveform forming metal strip with wave troughs and wave crests in such a way that the wave troughs and wave crests of two adjacent flow elements are arranged offset to each other in the main flow direction to each other, wherein the wave troughs of all flow elements in a first plane E1 lie and continue the wave crests of all the flow elements in a second plane E2 lie, and wherein the wave troughs and the wave crests each form a planar contact surface for contact with a counter element.

Such a bipolar plate provides a solution by which an effective and homogeneous distribution of the incoming reaction gas is made possible and / or which is inexpensive to produce.

It is thus proposed a bipolar plate for arrangement in a fuel cell. Such a bipolar plate can in particular serve in a fuel cell to supply the active layers of the fuel cell, such as existing catalyst layers, for example using gas diffusion layers arranged on the catalyst layers, with the corresponding reaction gases. The bipolar plate may be further configured to electrically connect a plurality of cells, such as in series. Further, a bipolar plate in the sense of the present invention can serve to serve as an end plate, so as to supply a gas arranged at the end of a stack to an electrode.

The bipolar plate is formed from or comprises a gas distributor element, which has a plurality of channels for distributing a reaction gas for operating the fuel cell. Thus, the bipolar plate, or its gas distributor element, serves to distribute an operating gas or reaction gas (the terms are used synonymously below) to the fuel cell as homogeneously as possible and as effectively as possible. This may be particularly advantageous since the bipolar plate is arranged in a fuel cell usually adjacent to corresponding electrodes and they should be supplied as effectively as possible with the respective operating gas. An electrode may, for example, comprise a gas diffusion layer which is arranged to contact the bipolar plate and serves to supply a reaction gas to a catalyst layer arranged adjacent to the gas diffusion layer. In the catalyst layer, the actual reaction can take place. The electrode or the catalyst layer is separated by a membrane from an oppositely poled electrode, such as also a catalyst layer.

In order to enable the most effective possible distribution of the operating gases, it is provided in the above-defined bipolar plate that the gas distributor element has a plurality of along the main flow direction of the gas juxtaposed flow elements. The main flow direction is in particular the direction in which the respective operating gas flows through the bipolar plate as an overall direction, for example, flows into the gas distribution element. This may be approximately defined as the sum of all the direction vectors of the reaction gas flowing in the gas distributor element.

Furthermore, the flow elements according to the invention are designed such that they are configured in strip form or as metal strips and thus have a greater length compared to their width. In other words, the flow elements are designed such that the width of this flow element row is limited and adjacent to adjacent flow elements.

It is further provided that the flow elements following the main flow direction of the reaction gas form a waveform or follow a waveform with each troughs and wave crests such that the troughs and peaks of two adjacent flow elements are offset from one another. In other words, an adjacent flow element is arranged offset in particular by a waveform or a portion of the waveform in the direction of the gas flow or in the main flow direction of the gas. For example, a flow element or several or all flow elements in the main flow direction has a repeating waveform, wherein the waveform repeats in the same way or regularly in particular. Such flow elements can accordingly represent flow elements which effectively distribute the operating gases.

In detail, the gas flow through the flow elements may be directed so that the reaction gas is directed on a falling waveform toward an electrode, such as a gas diffusion layer of the electrode, underneath the landed waveform and thus toward the catalyst layer of the electrode, when the bipolar plate is disposed adjacent to an electrode, for example, containing a catalyst layer having arranged thereon gas diffusion layer. By the lateral interruption of the flow elements or the row of flow elements along the rising waveform, a portion of the gas stream is passed to the first element and passed to the next flow element. Thus, a uniform gas distribution in the web and channel region and thus to the gas diffusion layer and thus in the catalyst layer of a fuel cell electrode is achieved. In this case, the channel region can be the region extending at right angles to the main flow direction, which is located above the wave troughs or underneath the wave peaks, wherein the channel region can furthermore be the region which leads from a wave crest to a wave trough and can thus overlap, for example, adjacent flow elements.

In addition, liquid water arising in the electrode can be transported under the webs, that is to say in particular the connecting regions of the wave crests and wave troughs, into the channel with the gas stream directed there, and discharged therefrom.

By these measures, both a better mixing of the gas diffusion layer and the catalyst layer with reaction gas is effected, as well as an improved water discharge of the liquid water from the gas diffusion layer and the catalyst layer in the direction of the gas distributor field, ie the gas distribution element of the bipolar plate achieved. As a result, a more uniform current density distribution and an overall better performance of the fuel cell can be achieved.

In the embodiment of the gas distribution element designed as a distribution field plate, a basic element can be given a wave-shaped form by forming, which in particular is repeated regularly. The basic element and thus the flow element are formed of a metal such as a metal sheet. Preferably, the flow element is formed from sheet steel. This allows a good electrical and thermal conduction at low production costs. Alternatively, however, a metal sheet made of titanium, aluminum, as well as other metallic materials or alloys may be considered.

For example, the flow elements are thus formed from one or more metal sheets, which may be provided, for example with a corrosion-protective layer. Due to the production and reshaping, in particular round or rounded basic shapes having a corresponding radius can be formed preferably or particularly simply. In this case, the waveform is limited in particular by minimal radii, which should in particular mean that there are always curves, but no sharp edges.

Furthermore, a flow element may laterally be adjoined by a plurality of, in particular, identical or different flow elements, wherein the wave shapes may be offset and / or different such that the third, fourth, fifth, sixth, or even further flow element with respect to the troughs and wave crests again corresponds to the original flow element. In other words, the flow elements may be arranged laterally at a frequency of two, three, four, five, six or more flow elements approximately in the waveform or its position repeating. Thus, it may be provided in principle that the waveform of the individual flow elements may be the same or may differ from each other and may optionally repeat regularly.

It is further provided that the wave troughs and wave crests each form a contact surface for contact with a, in particular gas-tight or gas-impermeable, counter element. This should mean in particular that a counter element, such as an electrode, such as a gas diffusion layer of the electrode, or an approximately gas-tight plate member, may abut the wave crests or troughs.

According to the invention, the wave troughs and wave crests each form a planar contact surface, that is to say that the contact surfaces of the wave crests and the contact surfaces of the wave troughs, ie all wave troughs and all wave crests, each lie in one plane. The contact surfaces of the troughs are in a first level E1 and the contact surfaces of the wave crests in a second plane E2 , Wherein the two aforementioned levels are formed in particular parallel. This embodiment may be particularly advantageous for positioning in the fuel cell. Because in this embodiment, the waveform or the gas distributor element can both have a flat contact surface in the direction of two electrodes, such as two gas diffusion layers or for an electrode, such as for a gas diffusion layer and in the direction of a flat plate member, as described below. The two contact surfaces are then connected to each other via an inclined transition region or web region, so that the contact surfaces and the transition regions in each case form the waveform. In this embodiment, the contacting of one or more electrodes, and / or a plate is thus facilitated and designed in a particularly defined manner, which can serve for an effective mode of operation of a fuel cell.

In this regard, it may be preferred that in at least one flow element, preferably in all flow elements, the sum of a length of all contact surfaces or contact areas of the wave crests and troughs in the main flow direction is greater than the sum of the lengths of the areas between the contact surfaces in the main flow direction. In other words, the expansion of the contact surfaces outweighs the transition surfaces of a flow element arranged between the contact surfaces. This embodiment enables a particularly effective and efficient operation of the fuel cell, since an effective contacting of electrodes with simultaneous effective distribution of the reaction gases can be made possible.

Furthermore, it may be preferred that at least two adjacent flow elements are mechanically interconnected. For example, the adjacent flow elements can be connected to one another by an electrically and / or thermally conductive material, for example by a metallic material. For example, the bipolar plate or the gas distributor element can be designed with its flow elements such that the wave troughs and the wave crests of adjacent flow elements are each connected to one another via an example inclined transition region. As a result, in particular the mechanical stability, the electrical and thermal transverse conduction, ie the working behavior of the fuel cell, as well as the manufacturability can be improved. In particular, the contact surfaces of the individual rows of waves can have overlapping areas in which the contact surfaces are connected to one another.

In particular, adjacent flow elements are integrally formed and connected to each other where wave troughs adjacent flow elements adjacent to each other. This allows a particularly cost-effective production.

Furthermore, it may be preferred that at the wave crests or the troughs, a gas distribution element at least partially final plate member is provided as a counter element. In this embodiment, the bipolar plate can thus comprise or consist of the gas distributor element and in particular the flat plate element, or a plate element separated from the bipolar plate can be provided. In this case, the plate element is arranged on the planar contact surface described above. In this embodiment, the flow path corresponding to the flow elements results alternately between the plate element and an electrode arranged approximately opposite to the plate element, in particular its gas diffusion layer. In this embodiment, the bipolar plate can serve approximately as an end element, that is to say for an electrode arranged at the end. Thus, this bipolar plate does not need to connect cells, but can only ensure the supply of operating gas or reaction gas to the electrode.

In particular, each metal strip of a flow element in the main flow direction is formed uninterrupted in a continuous same width. Uninterruptible means that the metal strip has almost the same thickness throughout, so no openings, cuts or interruptions. Slight differences in thickness may only result from forming processes in areas of a metal strip adjacent to the planar contact surfaces.

In particular, a metal strip on a periodically recurring wave profile, resulting in manufacturing technology to simplify and cost savings in terms of tools.

The wave crests and the wave troughs of at least two adjacent flow elements are preferably arranged exactly opposite one another. In other words, when there is a wave trough in a flow element, a wave crest can be located in an adjacent flow element at the same height. In this case, the centers of the contact surfaces of the wave crest and the wave trough (seen perpendicular to the contact surface) lie on an imaginary line which runs perpendicular to a longitudinal direction of the adjacent flow elements. In this embodiment, the resulting channels can be particularly large dimensions, whereby the pressure loss and thus the parasitic power, e.g. an air compressor and thus the fuel cell system efficiency is improved.

In particular, in this embodiment but in no way limited thereto, it may further be preferred that the waveforms of at least two flow elements are formed accordingly. In other words, it can be provided that the flow elements have the same wave structure, that is about the same radii and the same contact surfaces, wherein the waveforms are shifted relative to each other only in the main flow direction. In this embodiment, a particularly cost-manufacturability can be made possible, since it can be used with a variety of correspondingly shaped flow elements. In addition, a particularly homogeneous gas distribution can be made possible, which can provide advantages in terms of working the fuel cell.

It may further be preferred that at least two adjacent flow elements are formed with mutually different waveforms. In this embodiment, it is possible to influence the gas distribution in a targeted manner, which may also have advantages in terms of application. For example, a first waveform may be different from the second, or even third, fourth, or fifth, etc., waveform with respect to the execution of the waveform. There may be a difference with regard to at least one of the following features: length of a contact surface of the wave troughs in the main flow direction, length of a contact surface of the wave peaks in the main flow direction, width of a flow element, height of a flow element, angle between the first plane E1 and metal strip in the area between the contact surfaces of a wave trough and a subsequent wave crest (= land area), angle between the second level E2 and metal strip in the area between the contact surfaces of a wave trough and a subsequent wave crest (= web area). In this case, only one of the aforementioned features may be different and the other features may be the same, or any number of the features described above may be different.

Furthermore, it may in principle be provided that the waveform of a flow element is different in itself. For example, a flow element or a plurality of flow elements can be designed such that the respective second shaft is twice as long as the first shaft.

With regard to further advantages and technical features of the above-described Bipolar plate is referred to the description of the fuel cell, the figures and the description of the figures.

The subject of the present invention is furthermore a fuel cell, comprising a bipolar plate according to the invention, which electrically contacts at least one electrode, and wherein the fuel cell is designed to conduct a reaction gas in the main flow direction of the reaction gas through the bipolar plate.

The above-described fuel cell may be, for example, a polymer electrolyte membrane fuel cell. It has one or preferably a plurality of bipolar plates, which are designed as described above. For example, the bipolar plates contact an electrode and on the opposite side a plate element or contact two electrodes electrically and preferably thermally.

It can thus be provided that the bipolar plate only consists of the gas distributor element and, for example, is in contact with an electrode on both sides, for example at corresponding contact surfaces. In this case, the gas distribution element may have approximately areas to ensure a gas supply or other areas, but these additional areas are designed in one piece with the area described as a gas distribution element. For example, it can be provided that the bipolar plate electrically contacts one electrode at the contact surfaces of the wave troughs and at the contact surfaces of the wave crests, or that the bipolar plate contacts or has a plate element at least partially terminating the gas distributor element at the contact surfaces of the wave crests and at the abutment surfaces Wellentäler an electrode contacted electrically.

In this case, at least one gas inlet is provided which conducts the corresponding reaction gases in the main flow direction through the respective bipolar plate or through the respective gas distributor element.

In particular, such a fuel cell has the advantages as described in detail above. In particular, a cost-effective manufacturability and / or an effective and homogeneous gas distribution can be made possible.

With regard to further advantages and technical features of the fuel cell described above, reference is made to the description of the bipolar plate, the figures and the description of the figures.

• 1 eine schematische Ansicht von schräg oben von einer Ausgestaltung eines Gasverteilerelements einer Bipolarplatte;
• 2 eine schematische Schnittansicht durch die Ausgestaltung aus 1 von der Seite;
• 3 eine schematische Draufsicht auf die Ausgestaltung aus 1;
• 4 eine Schnittansicht durch einen Teil einer Brennstoffzelle.
• 5 eine Draufsicht auf eine Bipolarplatte; und
• 6 einen Querschnitt B-B durch die Bipolarplatte gemäß 5 mit Vergrößerung der Strömungselemente im gestrichelt gekennzeichneten Bereich B; und
• 7 schematisch den Aufbau einer Brennstoffzelle im Querschnitt.

In the following, a particularly preferred embodiment of the invention will be explained with reference to the accompanying drawings, wherein it is explicitly pointed out that the object according to the invention is not limited to the exemplary embodiment described. Show it:

• 1 a schematic view obliquely from above of an embodiment of a gas distribution element of a bipolar plate;
• 2 a schematic sectional view through the embodiment of 1 of the page;
• 3 a schematic plan view of the embodiment 1 ;
• 4 a sectional view through a portion of a fuel cell.
• 5 a plan view of a bipolar plate; and
• 6 a cross section BB through the bipolar plate according to 5 with enlargement of the flow elements in the dashed area B; and
• 7 schematically the structure of a fuel cell in cross section.

In the 1 is a view of a gas distribution element 14 a bipolar plate 10 (see 5 ) according to the invention. The bipolar plate 10 serves in particular for the arrangement in a fuel cell 12 (see 7 of which a part in the 4 or 6 is shown). The gas distribution element 14 has a plurality of channels 16 for distributing a reaction gas for operating the fuel cell 12 on.

The gas distribution element 14 has a plurality of along the main flow direction of the reaction gas, which is indicated by the arrow 18 is shown, juxtaposed flow elements 20 on. The flow elements 20 Form in the main flow direction of the reaction gas from a waveform, the waveform wave troughs 22 and wave mountains 24 having. It is envisaged that the troughs 22 and wave mountains 24 each a planar contact surface 26 . 28 form.

It is further shown that the troughs 22 and wave mountains 24 two adjacent flow elements 20 are offset from each other along the main flow direction. In detail, the figures show that the troughs 22 and the wave mountains 24 at least two adjacent flow elements 20 are arranged oppositely, wherein the waveforms of the flow elements 20 basically identical or designed accordingly.

With respect to the waveform, this first comprises the contact surfaces 26 . 28 and further rising or falling land areas 30 , which can each be straight and with the contact surfaces 26 . 28 by rounded connecting areas 34 can be connected. Such a configuration may be advantageous for the distribution of the reaction gases, but the flow elements are 20 or their waveforms are not limited to this embodiment.

In the 4 is also a part of a fuel cell 12 (see 7 ) with a bipolar plate 10 (see 5 ). It is shown that on the wave mountains 24 a the gas distributor element 14 at least partially final plate element 38 is provided and that the troughs 22 an electrode 40 contact, wherein the electrode is a gas diffusion layer 42 and a catalyst layer 44 as is basically known.
With regard to the distribution of the reaction gas through the bipolar plate 10 or the gas distribution element 14 this can be described as follows. As in particular in the 2 to 4 Shown is a part of the gas flow passing through the arrows 18 is shown in the flow element 20 with a repetitive waveform, first by the downward wave-form approximately toward the gas diffusion layer 42 and thus towards the catalyst layer 44 directed. Due to the pressure conditions, the other part of the flow becomes right or left on the flow element 20 deflected and the downwardly facing waveform of this next flow element 20 guided. From then on, the flow path is repeated. This results in a main flow direction parallel to the orientation of the flow elements 20 extends and may correspond, for example, the direction in which the reaction gas in the gas distribution element 14 is guided, as in the 2 to 4 can be seen. In other words, the gas does not become parallel to the channels 16 in the gas distribution element 14 but, contrary to the prior art solutions substantially at right angles thereto.

5 shows a plan view of a bipolar plate 10 with a gas distribution element 14 containing a variety of flow elements 20 having. In the edge area of the bipolar plate 10 are gas inlets 11a exists, through which a reaction gas flows and in the direction of the arrow 18 indicating the main flow direction of the reaction gas via the gas distributor field 14 along the flow elements 20 in the form of integrally interconnected metal strip is guided with wave profile. The gas inlets 11a opposite are gas outlets 11b arranged by the possible residues of the reaction gas and reaction products, represented by the arrow 18 ' to be dissipated.

6 shows a schematic cross section BB through a bipolar plate 10 according to 5 with enlargement of the flow elements 20 in the dashed area B according to 5 , In addition, an in 5 not shown plate element 38 present, that at the contact surfaces 26 the wave troughs 22 all flow elements 20 is applied. Furthermore, a gas diffusion layer 42 present at the contact surfaces 28 the wave mountains 24 all flow elements 20 is present, a catalyst layer 44 , which adhere to the gas diffusion layer 42 connects, as well as a polymer electrolyte membrane 46 , which adhere to the catalyst layer 44 followed.

7 shows schematically the structure of a fuel cell 12 in cross section, comprising two bipolar plates 10 . 10 ' , a polymer electrolyte membrane 46 , two electrodes 40 . 40 ' each comprising a gas diffusion layer 42 . 42 ' and one catalyst layer each 44 . 44 ' , The sealing of the cathode side of the polymer electrolyte membrane 46 from the anode side via a sealing element 51 , which is the cathode side in the main flow direction supplied reaction gas 52 from the anode side in the main flow direction supplied reaction gas 54 separates. The bipolar plates 10 . 10 ' are here with the wave mountains 24 respectively in the direction of the gas diffusion layer 42 . 42 ' arranged.

LIST OF REFERENCE NUMBERS

10, 10 '

bipolar

11a

gas inlet

11b

gas outlet

12

fuel cell

14

Gas distributor element

16

channel

18

arrow

20

flow element

22

trough

24

Wellenberg

26

contact surface

28

contact surface

30

web region

34

connecting area

38

panel member

40, 40 '

electrode

42, 42 '

Gas diffusion layer

44, 44 '

catalyst layer

46

Polymer electrolyte membrane

51

sealing element

52

cathode-side reaction gas

54

anode-side reaction gas

E1

first floor

E2

second level

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007009905 A1 [0004]
• US 9306228 B2 [0005]
• DE 112009001377 T5 [0006]
• DE 112009004658 B4 [0007]
• DE 102015207397 A1 [0008]
• DE 102014223735 A1 [0009]
• DE 102014224025 A1 [0010]
• DE 102012209851 A1 [0011]

Claims (10)

Bipolar plate (10, 10 ') for arrangement in a fuel cell (12), comprising a gas distributor element (14), which has a plurality of channels (16) for distributing a reaction gas for operating the fuel cell (12), wherein the gas distributor element (14) a plurality of flow elements (20) juxtaposed in a main flow direction of the reaction gas, each flow element (20) along the main flow direction of the reaction gas has a wave forming metal strip with wave troughs (22) and wave crests (24) such that the wave troughs ( 22) and wave crests (24) of two adjacent flow elements (20) are offset from each other in the main flow direction, wherein the wave troughs (22) of all flow elements (20) lie in a first plane (E1) and further the wave crests (24) of all flow elements (20) lie in a second plane (E2), and wherein the troughs (2 2) and the wave crests (24) each form a planar abutment surface (26, 28) for contact with a counter element. Bipolar plate (10, 10 ') after Claim 1 , wherein in at least one flow element (20) the sum of a length of all contact surfaces (26, 28) of the wave crests (24) and wave troughs (22) in the main flow direction is greater than the sum of the lengths of the regions between the abutment surfaces (26, 28 ) in the main flow direction. Bipolar plate (10, 10 ') according to one of Claims 1 or 2 wherein at least two adjacent flow elements (20) are mechanically interconnected. Bipolar plate (10, 10 ') according to one of Claims 1 to 3 wherein adjacent flow elements (20) are integrally formed and joined together where troughs (22) of adjacent flow elements (20) abut each other. Bipolar plate (10, 10 ') according to one of Claims 1 to 4 , wherein on the wave crests (24) or the troughs (22), a gas distribution element (14) at least partially final plate member (38, 38 ') is provided. Bipolar plate (10, 10 ') according to one of Claims 1 to 5 wherein each metal strip is formed in the main flow direction in a continuous same width without interruption. Bipolar plate (10, 10 ') according to one of Claims 1 to 6 , wherein the waveforms of at least two flow elements (20) are formed accordingly. Bipolar plate (10, 10 ') according to one of Claims 1 to 7 wherein at least two adjacent flow elements (20) are formed with mutually different waveforms. Fuel cell (12), comprising a bipolar plate (10, 10 ') according to one of Claims 1 to 8th at least one electrode (40, 40 ') electrically contacting, wherein the fuel cell (12) is configured to conduct a reaction gas in the main flow direction of the gas through the bipolar plate (10, 10'). Fuel cell (12) after Claim 9 , characterized in that the bipolar plate (10, 10 ') at the abutment surfaces (26) of the troughs (22) and at the contact surfaces (28) of the wave crests (24) each electrically contact one electrode (40), or that the bipolar plate ( 10, 10 ') on the abutment surfaces (28) of the wave crests (24) a gas distribution element (14) at least partially final plate member (38, 38') contacted or has and on the contact surfaces (26) of the troughs (22) an electrode ( 40, 40 ') are electrically contacted.

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