Bipolar plate for electrochemical cells, enabling a reduction of short-circuit flows at the edge of the reaction zone.
The bipolar plate design with alternating transverse ribs and recesses in lateral bypass zones addresses short-circuit flows and mechanical deformation, improving the performance of electrochemical cells by minimizing fluid bypass and enhancing fluid resistance.
Patent Information
- Application Number
- FR2024001455
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2024-02-14
- Publication Date
- 2025-12-26
- Estimated Expiration
- 2044-02-14
AI Technical Summary
Existing bipolar plates in electrochemical cells suffer from short-circuit flows of reactive fluids and heat transfer fluids in lateral bypass zones, which degrade performance and increase mechanical deformation risks.
A bipolar plate design with alternating anti-short-circuit parts featuring transverse ribs and recesses in the lateral bypass zones, reducing the cross-sectional area for fluid flow and increasing fluid resistance to minimize short-circuit flows while limiting mechanical deformation.
The design effectively reduces short-circuit flows of reactive fluids and heat transfer fluids, enhancing the performance and mechanical stability of electrochemical cells.
Smart Images
Figure 00000025_0000 
Figure 00000025_0001 
Figure 00000026_0000
Abstract
Description
Title of the invention: Bipolar plate for an electrochemical cell enabling a reduction of short-circuit flows at the edge of the reaction zone technical field
[0001] The field of the invention is that of electrochemical reactors comprising a stack of electrochemical cells, such as fuel cells and electrolyzers, and relates more particularly to bipolar plates with conductive sheets. PREVIOUS STATE OF THE ART
[0002] An electrochemical reactor, such as a fuel cell or an electrolyzer, usually comprises a stack of electrochemical cells, each of which includes an anode and a cathode electrically separated from each other by an electrolyte. The cells are the site of an electrochemical reaction between two reactant fluids introduced continuously.
[0003] Generally, in the case of a fuel cell, the fuel fluid (for example, hydrogen) is supplied to the anode, while the oxidizing fluid (for example, air) is supplied to the cathode. The electrochemical reaction is subdivided into two half-reactions, an oxidation reaction and a reduction reaction, which take place respectively at the anode / electrolyte interface and the cathode / electrolyte interface. For the electrochemical reaction to occur, the presence of an ionic conductor between the two electrodes, namely the electrolyte, for example, contained in a polymer membrane, and an electronic conductor formed by the external electrical circuit. The stack of cells is thus the site of the electrochemical reaction: the reactive fluids must be supplied to it, the products and non-reactive species must be removed, as well as the heat produced during the reaction.
[0004] Electrochemical cells are usually separated from each other by bipolar plates that provide electrical interconnection between them and allow the flow of reactive fluids. The bipolar plates have an anodic face on which a fuel fluid distribution circuit is formed, and an opposite cathodic face on which an oxidizing fluid distribution circuit is formed. Each distribution circuit takes the form of a network of channels arranged to deliver the reactive fluid to the corresponding electrode. The bipolar plates may also include a cooling circuit formed by a network of internal conduits that ensure the flow of a heat transfer fluid. allowing the heat produced locally during the electrochemical reaction by the cell to be dissipated.
[0005] Figure [1A] is a schematic and partial view of an example of a bipolar plate 1, of the conductive lamination type, in top view and from the cathode side. Figure [1B] is a cross-sectional view of the bipolar plate 1 of Figure [1A] along section line AA.
[0006] The bipolar plate 1 comprises two plates, upper 10 and lower 20, made of an electrically conductive material, and superimposed one on top of the other. Each plate 10 and 20 has a distribution circuit 7 adapted to convey a reactive fluid to the corresponding electrode. The anodic and cathodic distribution circuits 7 are superimposed on each other and define, in the XY plane, the reaction zone of the electrochemical cell. An air collector 2 and a hydrogen collector 3 are located opposite each other on the same side of the distribution circuit 7 and are separated from each other by a heat transfer fluid collector 4. The air collector 2 is adapted to supply the distribution circuit 7 with air, via an injection zone 8 and then a homogenization zone 9.
[0007] The plates 10, 20 have an external sealing line, formed of superimposed upper longitudinal ribs 12e and lower longitudinal ribs 22e, each associated with an external sealing gasket 5 (upper and lower). The external sealing line extends continuously around the periphery of the bipolar plate 1 and surrounds, in the XY plane, the collectors 2 and 3 (and here also the collector 4) and the reaction zone. It prevents reactive fluids from flowing outside the bipolar plate. Furthermore, the plates 10, 20 have upper internal longitudinal ribs 12i and lower internal longitudinal ribs 22i, which extend longitudinally along the edges of the distribution circuits and help to define a distribution channel.The external longitudinal ribs 12e, 22e (also called joint ribs) and the internal longitudinal ribs 12i, 22i (also called channel ribs) longitudinally delimit a lateral bypass zone Zcc located at the edge of the distribution circuit.
[0008] Thus, during operation, air is supplied by the inlet manifold 2, flows through the injection zone 8 and then the homogenization zone 9, and comes into contact with the cathode 32 by means of the distribution circuit 7. Unconsumed air then flows through a homogenization zone, then an injection zone, to finally reach the air outlet manifold 2 (see solid arrows in [Fig. 1A]). The same applies to hydrogen on the anodic side.
[0009] However, it appears that air can bypass the reaction zone by flowing into lateral bypass zones Zcc located between the reaction zone and the external sealing line. Indeed, as shown by the dashed arrows In [Fig. 1A], air can escape from the injection zone 8 to reach the lateral bypass zones Zcc (on the left of the figure) and flow along the longitudinal edges of the reaction zone. These flows are short-circuit flows insofar as they do not participate in the electrochemical reaction, which degrades the fuel cell's performance. This is the case for air on the cathodic side, but also for hydrogen on the anodic side.
[0010] There is therefore a need to have bipolar plates whose structural configuration of the conductive sheets makes it possible to reduce these flows in these lateral bypass zones, both for reactive fluids and for the heat transfer fluid.
[0011] In this respect, document EP3171439 A1 describes a structural configuration of the conductive sheets in the lateral bypass zones, where the conductive sheets have superimposed upper and lower transverse longitudinal ribs, each directly connecting the inner longitudinal rib to the outer longitudinal rib. The intermediate transverse ribs are deformable, so that when deformed, they extend vertically towards the sealing film (see film 34 in [Fig. 1B]), between the AME and the outer joint, and conform as closely as possible to the shape of the AME. Thus, the cross-sectional flow area of the reactive fluids in this lateral bypass zone Zcc is reduced, which limits the short-circuit flow of the reactive fluids.However, the cross-sectional area of the heat transfer fluid flow is increased, which reduces cooling efficiency and degrades the performance of the electrochemical cell. Description of the invention
[0012] The invention aims to remedy at least in part the disadvantages of the prior art, and more particularly to propose a bipolar electrochemical cell plate whose structural configuration of the conductive sheets, in at least one of the lateral bypass zones, makes it possible to reduce both the short-circuit flow of the reactive fluids and that of the heat transfer fluid, while also limiting the risks of mechanical deformation of the conductive sheets and / or the membrane / electrode assemblies in the intermediate longitudinal zone.
[0013] For this purpose, the object of the invention is a bipolar electrochemical cell plate, comprising upper and lower sheets, superimposed one on the other, comprising: • lower and upper distribution circuits, superimposed one on the other, adapted to bring reactive fluids respectively to lower and upper electrodes; • upper and lower internal longitudinal ribs, superimposed on each other, forming respectively a longitudinal border of the lower and upper distribution circuits; • upper and lower external longitudinal ribs, superimposed on each other, extending along the internal longitudinal ribs, laterally delimiting, with the internal longitudinal ribs, a lateral zone called bypass extending longitudinally along the distribution circuits.
[0014] In the lateral bypass zone there is a longitudinal alternation: • of at least one first anti-short-circuit part, where: the upper sheet metal has an upper intermediate longitudinal rib, extending throughout the first anti-short-circuit part; and where the lower sheet metal has a lower intermediate recess, superimposed on and in contact with the upper intermediate longitudinal rib; • of at least one second anti-short-circuit part, where: the lower sheet metal has a lower intermediate longitudinal rib, extending throughout the second anti-short-circuit part; and where the upper sheet metal has an upper intermediate recess, superimposed on and in contact with the lower intermediate longitudinal rib.
[0015] According to the invention, in the first anti-short-circuit part, the lower sheet comprises a longitudinal succession of lower transverse ribs, including: internal, respectively external, lower transverse ribs extending from the internal, respectively external, lower longitudinal rib, and having a closed opposite end not connected to the external, respectively internal, lower longitudinal rib.
[0016] Furthermore, in the second anti-short-circuit part, the upper sheet metal comprises a longitudinal succession of upper transverse ribs, including: internal, respectively external, upper transverse ribs extending from the internal, respectively external, upper longitudinal rib, and having a closed opposite end not connected to the external, respectively internal, upper longitudinal rib.
[0017] Some preferred but not limiting aspects of this bipolar plate are the following.
[0018] The bipolar plate may comprise several first anti-short-circuit parts arranged alternately longitudinally with several second anti-short-circuit parts.
[0019] In the first anti-short-circuit section, the lower internal and external transverse ribs of the lower sheet metal can be interlocked, so that each The lower internal transverse rib extends along an outer lower transverse rib.
[0020] In the second anti-short-circuit part, the internal and external upper transverse ribs of the upper sheet can be interdigitated, so that each internal upper transverse rib extends along an external upper transverse rib.
[0021] The upper and lower transverse ribs may have, in a plane parallel to the bipolar plate, a straight, T, L or spiral shape.
[0022] The upper and lower external transverse ribs may have a height, with respect to a reference plane passing between the upper and lower external longitudinal ribs, that is less than that of the upper and lower external longitudinal rib.
[0023] The lower intermediate recess can separate, along an axis orthogonal to a longitudinal axis of the lateral bypass zone, the outer lower transverse rib from the inner lower longitudinal rib, and the inner lower transverse rib from the outer lower longitudinal rib.
[0024] The upper intermediate recess can separate, along an axis orthogonal to a longitudinal axis of the lateral bypass zone, the outer upper transverse rib from the inner upper longitudinal rib, and the inner upper transverse rib from the outer upper longitudinal rib.
[0025] The upper and lower external longitudinal ribs can each be in contact with a sealing gasket.
[0026] The invention also relates to an electrochemical cell, comprising at least one bipolar plate according to any one of the preceding characteristics, and a membrane / electrode assembly in contact with the bipolar plate.
[0027] The invention also relates to an electrochemical reactor, comprising at least one electrochemical cell according to the preceding characteristic. Brief description of the drawings
[0028] Other aspects, objects, advantages and features of the invention will become more apparent upon reading the following detailed description of preferred embodiments thereof, given by way of non-limiting example, and made with reference to the accompanying drawings in which:
[0029] [Fig.1A], already described, is a schematic and partial top view of a bipolar plate according to an example from the prior art;
[0030] [Fig.1B], already described, is a schematic and partial view, in cross-section, of the bipolar plate of [Fig.1A], along the section line AA;
[0031] [Fig.2] is a schematic and partial top view of a bipolar plate according to one embodiment, illustrating the first and second short-circuit protection parts located in the lateral bypass areas;
[0032] [Fig.3A] is a schematic and partial view of a part of an upper sheet of a bipolar plate according to one embodiment, in a lateral bypass zone;
[0033] [Fig.3B] is a schematic and partial view of part of a lower sheet of the bipolar plate of [Fig.3A], in the same lateral bypass area;
[0034] [Fig.3C] is a schematic and partial view of the same part of the upper sheet of the bipolar plate of [Fig.3A], in the same lateral bypass area, illustrating the lower transverse ribs (in dotted lines);
[0035] Figures 4A to 4H are schematic and partial cross-sectional views of a bipolar plate according to one embodiment, in a lateral bypass zone, along different cutting lines in the first and second anti-short-circuit parts;
[0036] Figures 5A to 5C are schematic and partial top views of part of an upper sheet of a bipolar plate, according to different embodiments of the upper transverse ribs;
[0037] Figures 6A and 6B are schematic and partial views, in perspective ([Fig.ôA]) and in longitudinal section ([Fig.ôB]), of a bipolar plate according to one embodiment;
[0038] Figures 7A to 7F are schematic and partial cross-sectional views of a bipolar plate according to one embodiment, in a lateral bypass zone, along different cutting lines in the first and second anti-short-circuit parts.
[0039] DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS
[0040] In the figures and throughout the description, the same reference numerals represent identical or similar elements. Furthermore, the various elements are not drawn to scale in order to enhance the clarity of the figures. Moreover, the different embodiments and variants are not mutually exclusive and may be combined. Unless otherwise indicated, the terms "approximately," "about," and "in the order of" mean within 10%, and preferably within 5%. Furthermore, the terms "between ... and ..." and equivalents mean that the limits are inclusive, unless otherwise stated.
[0041] The invention relates to a bipolar plate for an electrochemical cell, for electrochemical reactors such as fuel cells and electrolyzers. The bipolar plate is of the conductive sheet type, which has ribs and indentations. The invention relates more specifically to a configuration particular structural design of the bipolar plate in at least one of the lateral bypass zones which extend longitudinally between the external sealing line and the reaction zone, making it possible to reduce the short-circuit flow of reactive fluids as well as that of the heat transfer fluid, while also limiting the risks of deformation of the AME or the conductive sheets in the intermediate longitudinal zone.
[0042] Various embodiments and variants will be described with reference to a fuel cell, and in particular to a PEM (Proton Exchange Membrane) type fuel cell in which the cathode is supplied with oxygen and the anode with hydrogen. However, the invention applies to any type of fuel cell, particularly those operating at low temperatures, i.e., below 200°C, as well as to electrochemical electrolyzers.
[0043] [Fig. 2] is a schematic and partial top view of a portion of the bipolar plate 1 according to one embodiment. Certain elements are described with reference to [Fig. 1B].
[0044] Here and for the rest of the description we define a direct orthogonal frame XYZ, where the Z axis is oriented along the thickness of the bipolar plate 1 (from the lower sheet 20 to the upper sheet 10), and where the X and Y axes define a principal plane along which the bipolar plate extends.
[0045] The electrochemical cells here belong to a stack of cells in a fuel cell. Each electrochemical cell comprises a membrane / electrode assembly 30 (MEA, see [Fig. 1B]) consisting of a cathode 32 and an anode 33 separated from each other by an electrolyte 31, which here includes a polymer membrane. The MEAs 30 of the electrochemical cells are arranged between bipolar plates 1 adapted to deliver reactive species to the electrodes and to dissipate the heat produced during the electrochemical reaction. The MEA extends partially into the lateral bypass zone Zcc along the transverse axis X. A sealing film 34 (distinct from the membrane 31 or corresponding to the membrane) may extend from the MEA 30 to the edge of the bipolar plates 1 and be in contact with the external sealing gaskets 5.
[0046] Each bipolar plate 1 is formed of two superimposed and joined upper and lower sheets 10 and 20. They are made of an electrically conductive material. These conductive sheets 10, 20 are locally deformed to form channels for the flow of reactive fluids, and in particular an injection zone 8, a homogenization zone 9, and a distribution circuit 7, as well as a cooling circuit located between the conductive sheets 10, 20. Thus, the lower sheet 20, for example the anodic sheet, is intended to be in contact with the anode of the membrane / electrode assembly 30 of an adjacent electrochemical cell, while that the upper plate 10, here cathodic, is intended to be in contact with the cathode 32 of the AME of the electrochemical cell.
[0047] Each conductive plate 10, 20 has an external face and an opposite internal face, the conductive plates 10, 20 facing each other at their internal faces. An external face is called anodic when it is intended to be in contact with the anode 33, or is called cathodic when it is intended to be in contact with the cathode 32. The anodic face of one conductive plate has the distribution circuit for a combustible reactive fluid, for example hydrogen here, and the cathodic face of the other conductive plate has the distribution circuit for the oxidizing reactive fluid, for example air here.
[0048] The conductive sheets 10, 20 are in the form of thin sheets or elementary plates made of an electrically conductive material, for example a metal or even a composite material, for example, one loaded with graphite. The thickness can be on the order of a few tens of microns to a few hundred microns, for example, from approximately 50 µm to 200 µm in the case of metal sheets.
[0049] Each conductive sheet 10, 20 has ribs and indentations, obtained for example by deep drawing, stamping, or any other forming technique, the shape of which on one face is the complement of the shape on the opposite face. The ribs notably allow for defining the distribution circuit of a reactive fluid on the outer face, as well as the cooling circuit of the heat transfer fluid on the inner face.
[0050] Manifolds 2, 3, 4 are openings that pass through each of the bipolar plates 1. The reactive fluid manifolds 2, 3 are located on either side of the reaction zone, along a principal axis of reactive fluid flow, here along the Y axis. In this example, a heat transfer fluid manifold 4 is located between the reactive fluid manifolds 2, 3. Alternatively, they can be located along an X axis orthogonal to the longitudinal Y axis.
[0051] The reactant fluid manifolds 2, 3 are adjacent to each other (separated or not by the heat transfer fluid manifold 4), and are arranged opposite the same opening (inlet or outlet) of the reaction zone. In this example, an air inlet manifold 2 and a hydrogen manifold 3 (inlet or outlet) are located opposite the inlet of the cathodic distribution circuit 7.
[0052] The conductive sheets 10, 20 have injection zones 8 to allow fluid circulation to and from the manifolds. Thus, an air injection zone 8 provides the fluid connection between the air manifold 2 and the homogenization zone 9. It is formed of conduits that cross the sealing line of the air manifold and open onto the outer face of the upper sheet 10, allowing air to flow towards the homogenization zone 9. The same applies to the sheet lower 20, whose injection zone communicates with the hydrogen collector 3 and the homogenization zone. The coolant injection zone is formed by conduits that open between the two cathodic 10 and anodic 20 conductive plates. Similar injection zones are described in particular in document EP3136492A1.
[0053] Each conductive sheet 10, 20 here includes a homogenization zone 9 which communicates with the injection zone 8 on one side, and with the distribution circuit 7 on the other. Such a homogenization zone 9 makes it possible to homogenize the airflow at the inlet of the distribution circuit 7. It can be formed by homogenization channels made in the conductive sheet 10. Document EP3136492A1 also describes an example of such a homogenization zone.
[0054] Each conductive plate 10, 20 comprises a distribution circuit 7, formed of channels extending between an inlet and an outlet aligned along a principal direction (here the Y-axis). These channels are separated in pairs by a separating rib that is in contact with the corresponding AME. The cathodic and anodic distribution circuits define the reaction zone of the electrochemical cell in the XY plane.
[0055] Furthermore, a reference plane Pref of the bipolar plate 1 is defined as the contact plane of the conductive sheets 10, 20 at their outer edges 11 and 21e (see [Fig. 1B]). This is the reference plane Pref with respect to which the ribs and recesses are defined, when considered from the outer face of each conductive sheet 10, 20.
[0056] Thus, a rib is obtained by local deformation of the conductive sheet 10, 20, from its inner face to its outer face. It is therefore a relief or boss on the conductive sheet 10, 20, viewed from the outer face, which deviates from the reference plane Pref along the Z-axis (and therefore deviates from the other conductive sheet). In other words, a rib is a surface that protrudes from the reference plane Pref. Thus, an upper rib is a rib on the upper sheet 10 that deviates from the reference plane Pref along the +Z direction. And a lower rib is a rib on the lower sheet 20 that deviates from the reference plane Pref along the -Z direction. Furthermore, a rib has an elongated shape in the XY plane: a dimension (length) along a longitudinal axis is greater than its dimension (width) along a transverse axis.
[0057] Furthermore, an intermediate longitudinal rib is defined as a rib located in the lateral bypass zone Zcc (i.e., situated between the internal and external longitudinal ribs) and extending longitudinally along the same longitudinal axis Y as that of the Zcc zone. In addition, an intermediate transverse rib is defined as... a rib located in the lateral bypass zone Zcc and which extends longitudinally along an inclined axis (in the XY plane), or even orthogonal, to the longitudinal axis Y of the Zcc zone.
[0058] Conversely, a recess is obtained by local deformation of the conductive sheet 10, 20, from its outer face to its inner face. It is therefore a depression or hollow in the conductive sheet 10, 20, viewed from its outer face, which extends below the reference plane Pref along the Z-axis (and thus moves closer to the other conductive sheet). Thus, an upper recess is a recess in the upper sheet 10 that extends beyond the reference plane Pref along the -Z direction. And a lower recess is a recess in the lower sheet 20 that extends beyond the reference plane Pref along the +Z direction.
[0059] As illustrated in [Fig. 1B], the bipolar plate 1 has superimposed external longitudinal ribs, upper 12e and lower 22e, which completely surround the collectors 2 and 3 and the reaction zone in the XY plane. They extend longitudinally along the edge of the bipolar plate 1. External sealing gaskets 5 are arranged in contact with the upper rib 12e and lower rib 22e, respectively. They are also in contact with the sealing film 34. This configuration, which forms an external sealing line, prevents fluids, particularly reactive gases, from flowing outside the bipolar plate 1.
[0060] Furthermore, the bipolar plate 1 has internal longitudinal ribs, upper 12i and lower 22i, superimposed one on the other, which extend longitudinally along the edge of the reaction zone. They form the edge ribs of the distribution circuits 7. They are in contact with the diffusion layer of the PAME electrode 30. Thus, the lateral bypass zone Zcc corresponds to the area delimited laterally (along the X-axis) by the external sealing line and by the reaction zone, and more precisely by the external longitudinal ribs 12e, 22e on the one hand, and by the internal longitudinal ribs 12i, 22i on the other. Its longitudinal axis is here the Y-axis (this longitudinal axis may be straight or not).
[0061] It should also be noted that the conductive sheets 10, 20 comprise upper and lower flat portions, superimposed on one another and in contact with each other at the level of the reference plane Pref. Thus, external longitudinal portions 11e, 21e extend in the XY plane between the external longitudinal ribs 12e, 22e and the edge of the bipolar plate 1, over its entire periphery. In addition, upper internal longitudinal portions 11i and lower internal longitudinal portions 21i extend between the internal longitudinal ribs 12i, 22i and the distribution ribs.
[0062] According to the invention, in at least one of the lateral bypass zones Zcc, the bipolar plate 1 is formed by a longitudinal succession of at least one first short-circuit protection portion Plcsup and a second short-circuit protection portion P2inf. By longitudinal succession, it is understood that these first and second short-circuit protection portions Plsup, P2inf follow one another along the longitudinal axis of the lateral bypass zone Zcc. This longitudinal succession may be an alternation of several first short-circuit protection portions Plsup with several second short-circuit protection portions P2inf, either periodically or not.
[0063] In the first anti-short-circuit part Plsup, the contact plane between the two conductive sheets 10, 20 is a superior contact plane Pcsup, in the sense that it is located above the reference plane Pref along the direction +Z (cf in particular [Fig.4B] to 4D, described later).
[0064] The upper plate 10 y has an intermediate upper longitudinal rib 16, which extends along the longitudinal axis of the lateral bypass zone Zcc. Preferably, it extends continuously in a planar manner. It may or may not be coplanar with the external upper longitudinal rib 12e and / or with the internal upper longitudinal rib 12i. This intermediate upper longitudinal rib 16 extends over the entire length (along the Y-axis) of the first short-circuit protection section Plsup, and over its entire width (along the Y-axis). It thus directly connects the external upper longitudinal rib 12e with the internal upper longitudinal rib 12i, without any intermediate recess. The intermediate upper longitudinal rib 16 may be in contact with the AME over at least part of its width.
[0065] Furthermore, the lower plate 20 has a lower intermediate recess 24, superimposed on and in contact with the upper intermediate longitudinal rib 16, which extends along the longitudinal axis of the lateral bypass zone Z cc. The contact plane between the upper intermediate longitudinal rib 16 and the lower intermediate recess 24 corresponds to the upper contact plane Pcsup. It is located above the reference plane Pref (see [Fig. 4B]).
[0066] Finally, the lower plate 20 also includes a longitudinal succession, and preferably a longitudinal alternation, of lower transverse ribs 25i, 25e, of two different types: external lower transverse ribs 25e and internal lower transverse ribs 25i. These lower transverse ribs 25i, 25e extend vertically from the lower intermediate recess 24 along the direction -Z.
[0067] An external lower transverse rib 25e is a rib that extends along an axis transverse to the longitudinal axis Y, from the lower longitudinal rib external rib 22e and towards the internal lower longitudinal rib 22i. By "from the external lower longitudinal rib," we mean that it is directly connected to the latter (without an intervening recess that would come into contact with the superior rib 16). Thus, the cross-section delimited by the external lower longitudinal rib 22e communicates with the cross-section delimited by the external lower transverse rib 25e. Furthermore, the opposite end of the external lower transverse rib 25e is closed (blocked), in the sense that it is not connected to the internal lower longitudinal rib 22i.Thus, the cross-section delimited by the lower internal longitudinal rib 22i does not communicate with the cross-section delimited by the lower external transverse rib 25e: the lower recess 24 ensures the separation along the X axis between the lower external transverse rib 25e and the lower internal longitudinal rib 22i.
[0068] An internal lower transverse rib 25i is a rib that extends along an axis transverse to the longitudinal axis Y, from the internal lower longitudinal rib 22i towards the external lower longitudinal rib 22e. "From the internal lower longitudinal rib" means that it is directly connected to the latter (without an intervening recess that would come into contact with the upper rib 16). Thus, the cross-section delimited by the internal lower longitudinal rib 22i communicates with the cross-section delimited by the internal lower transverse rib 25i. Furthermore, the opposite end of the internal lower transverse rib 25i is closed (blocked), in the sense that it is not connected to the external lower longitudinal rib 22e.Thus, the cross-section delimited by the lower external longitudinal rib 22e does not communicate with the cross-section delimited by the lower internal transverse rib 25i: the lower recess 24 ensures the separation along the X axis between the lower internal transverse rib 25i and the lower external longitudinal rib 22e.
[0069] Furthermore, in the second anti-short-circuit part P2inf, the contact plane between the two conductive sheets 10, 20 is a lower contact plane Pcinf, in the sense that it is located below the reference plane Pref along the +Z direction (see in particular [Fig.4E] to 4F, described later).
[0070] The lower plate 20 y has a lower intermediate longitudinal rib 26, which extends along the longitudinal axis of the lateral bypass zone Zcc. Preferably, it extends continuously in a planar manner. It may or may not be coplanar with the outer lower longitudinal rib 22e and / or with the inner lower longitudinal rib 22i. This lower intermediate longitudinal rib 26 extends over the entire length (along the Y axis) of the anti-short- circuit P2inf, and across its entire width (along the Y-axis). It thus directly connects the outer lower longitudinal rib 22e with the inner lower longitudinal rib 22i, without any intermediate recess. The lower intermediate longitudinal rib 26 can be in contact with FAME over at least part of its width.
[0071] Furthermore, the upper plate 10 has an upper intermediate recess 14, superimposed on and in contact with the lower intermediate longitudinal rib 26, which extends along the longitudinal axis of the lateral bypass zone Z cc. The contact plane between the lower intermediate longitudinal rib 26 and the upper intermediate recess 14 corresponds to the lower contact plane Pcinf. It is located below the reference plane Pref (see [Fig. 4E]).
[0072] Finally, the upper plate 10 also includes a longitudinal succession, and preferably a longitudinal alternation, of upper transverse ribs 15e, 15i of two different types: external upper transverse ribs 15e and internal upper transverse ribs 15i. These upper transverse ribs 15i, 15e extend vertically from the upper intermediate recess 14 in the direction +Z.
[0073] An external upper transverse rib 15e is a rib that extends along an axis transverse to the longitudinal axis Y, from the external upper longitudinal rib 12e towards the internal upper longitudinal rib 12i. By "from the external upper longitudinal rib," it is understood that it is directly connected to the latter (without an intervening recess). Furthermore, the opposite end of the external upper transverse rib 15e is closed (blocked), in the sense that it is not connected to the internal upper longitudinal rib 12i: the lower recess 14 ensures the separation along the X axis between the external upper transverse rib 15e and the internal upper longitudinal rib 12i.
[0074] An internal upper transverse rib 15i is a rib that extends along an axis transverse to the longitudinal axis Y, from the internal upper longitudinal rib 12i towards the external upper longitudinal rib 12e. By "from the internal upper longitudinal rib," it is understood that it is directly connected to the latter (without an intervening recess). Furthermore, the opposite end of the internal upper transverse rib 15i is closed (blocked), in the sense that it is not connected to the external upper longitudinal rib 12e: the lower recess 14 ensures the separation along the X axis between the internal upper transverse rib 15i and the external upper longitudinal rib 12e.
[0075] Thus, as explained in detail below, in the anti-short-circuit section Plsup with upper contact plane Pcsup, the cross-sectional area of airflow at the upper (cathodic) plate 10 is significantly reduced (increased linear pressure drop), which limits the short-circuit air flow. Furthermore, the short-circuit hydrogen flow at the lower (anodic) plate 20 is limited by the presence of the lower transverse ribs 25e, 25i. These ribs induce an increase in fluid resistance (increased singular pressure drops), which further limits the short-circuit flow at the lower plate 20. Finally, the short-circuit flow of the heat transfer fluid is limited because the internal lower transverse ribs 25i are not connected to the external longitudinal rib 22e.Thus, the heat transfer fluid cannot flow into it and therefore cannot reach the reaction zone.
[0076] Similarly, in the anti-short-circuit section P2inf with lower contact plane Pcinf, the cross-sectional area for hydrogen flow at the lower plate 20 is significantly reduced (increased linear pressure drop), which limits the short-circuit flow of hydrogen. Furthermore, the short-circuit flow of air at the upper plate 10 is limited by the presence of the upper transverse ribs 15e, 15i (increased fluid resistance due to singular pressure drops), which further restricts the short-circuit flow at the upper plate 10. Finally, the short-circuit flow of the heat transfer fluid is limited because the internal upper transverse ribs 15i are not connected to the external longitudinal rib 12e. Therefore, the heat transfer fluid cannot flow through it, thus partially bypassing the reaction zone.
[0077] In the example of [Fig. 2], each lateral bypass zone Zcc comprises a longitudinal alternation of several short-circuit protection sections Plsup with an upper contact plane Pcsup and several short-circuit protection sections P2inf with a lower contact plane Pcinf, where each short-circuit protection section Plsup is directly followed by a short-circuit protection section P2inf. Obviously, other arrangements of the short-circuit protection sections are possible. In any case, the short-circuit flow of reactive fluids in these lateral bypass zones Zcc is limited, so that the reactive fluids flow more into the reaction zone, thereby improving the performance of the electrochemical cell. Similarly, the short-circuit flow of the heat transfer fluid is limited, which also improves the performance of the electrochemical cell.
[0078] Figures 3A to 3C are schematic and partial top views of a portion of the bipolar plate 1 of [Fig. 2], at a lateral bypass zone. [Fig. 3A] is a top view of the upper plate 10, [Fig. 3B] is a top view of the lower plate 20, and [Fig.3C] is a top view of the bipolar plate 1, where lower transverse ribs 25e, 25i are visible in dotted lines.
[0079] With reference to [Fig. 3A], the upper plate 10 includes the external upper longitudinal rib 12e, which helps define the external sealing line and extends continuously along the longitudinal axis Y. It also includes the internal upper longitudinal rib 12i, which forms the edge of the upper distribution circuit 7. This rib also extends continuously along the longitudinal axis Y. It should be noted that the ribs 12e and 12i may not extend longitudinally in a parallel fashion.
[0080] In the anti-short-circuit parts Plsup with upper contact plane Pcsup, the upper sheet 10 has an upper intermediate longitudinal rib 16, which connects transversely along the X axis the outer upper longitudinal ribs 12e and inner upper longitudinal ribs 12i, and which extends longitudinally along the Y axis, continuously, between the two adjacent anti-short-circuit parts P2inf.
[0081] In the short-circuit protection sections P2inf with a lower contact plane Pcinf, the upper plate 10 has an intermediate upper recess 14, which extends transversely along the X axis between the outer upper longitudinal ribs 12e and inner upper longitudinal ribs 12i, and which extends longitudinally along the Y axis between the two adjacent short-circuit protection sections P2inf. It also has an alternating longitudinal pattern of outer upper transverse ribs 15e and inner upper transverse ribs 15i. In this example, the upper transverse ribs 15e, 15i are straight and extend along the transverse axis X.
[0082] With reference to [Fig.3B], the lower sheet 20 has the external lower longitudinal rib 22e and the internal lower longitudinal rib 22i.
[0083] In the short-circuit protection sections Plsup with upper contact plane Pcsup, the lower sheet metal 20 has a lower intermediate recess 24, which extends transversely along the X-axis between the lower outer longitudinal ribs 22e and the lower inner longitudinal ribs 22i. This lower intermediate recess 24 is superimposed on the upper longitudinal rib 16 and is in contact with it. This contact is made in the upper contact plane Pcsup. It also has an alternating longitudinal pattern of lower outer transverse ribs 25e and lower inner transverse ribs 25i.
[0084] In the anti-short-circuit parts P2inf with lower contact plane Pcinf, the lower sheet metal 20 has a lower intermediate longitudinal rib 26, which connects transversely along the X axis the lower longitudinal ribs external 22e and internal 22i, and which extends longitudinally along the Y axis, continuously, between the two adjacent anti-short-circuit parts Plsup.
[0085] With reference to [Fig.3C], the upper plate 10 is shown, with, in the portions Plsup, its upper longitudinal rib 16, and the alternation of the internal lower transverse ribs 25i of the lower plate 20 is shown in dashed lines. The upper intermediate recess 14 is also shown in the portions P2inf with the alternation of its upper transverse ribs 15e, 15i, superimposed on the lower longitudinal rib 26 (not shown) of the lower plate 20.
[0086] Thus, in the upper portions P2, the short-circuit flow of air is limited by the reduction of the cross-sectional flow (due to the upper longitudinal rib 16), and the short-circuit flow of hydrogen is limited by the presence of the lower transverse ribs 25e, 25i. And in the lower portions P2, the short-circuit flow of hydrogen is limited by the reduction of the cross-sectional flow (due to the lower longitudinal rib 26), and the short-circuit flow of air is limited by the presence of the upper transverse ribs 15e, 15i. The short-circuit flow of the heat transfer fluid is also limited insofar as the upper internal transverse ribs 15i and lower internal transverse ribs 25i are not connected, respectively, to the upper external longitudinal ribs 12e and lower external longitudinal ribs 22e.
[0087] Figures 4A to 4H are schematic and partial views of a bipolar plate 1 similar to that of [Fig.2], along different cutting lines in the lateral bypass zone Zcc, in an anti-short-circuit part Plsup ([Fig.4B] to 4D) and then in an anti-short-circuit part P2inf ([Fig.4E] to 4G).
[0088] Fig. 4A illustrates the bipolar plate 1 upstream of an anti-short-circuit part Plsup. Between the external longitudinal ribs 12e, 22e and the internal longitudinal ribs 12i, 22i, the bipolar plate 1 comprises the upper intermediate longitudinal portions 13 and the lower intermediate portions 23, superimposed on each other, and in contact with each other at the level of the reference plane Pref.
[0089] Figure 4B illustrates the bipolar plate 1 in a short-circuit protection portion Psup. The upper plate 10 has an upper intermediate longitudinal rib 16, which connects transversely (along the X-axis) the outer upper longitudinal ribs 12e and inner upper longitudinal ribs 12i. The lower plate 20 has the lower intermediate recess 24, which extends transversely between the outer lower longitudinal ribs 22e and inner lower longitudinal ribs 22i. The lower intermediate recess 24 is superimposed on the upper longitudinal rib 16 and is in contact with it at the upper contact plane Psup.
[0090] As illustrated in [Fig. 4C], the lower sheet metal 20 has, in this short-circuit protection section Plsup, lower transverse ribs, here an external lower transverse rib 25e. It is connected to the external lower longitudinal rib 22e so that the internal cross-section of the external sealing line is widened (here along the +X direction). It extends transversely (along the X axis) towards the internal lower longitudinal rib 22i, without being connected to it: its end is closed (plugged). In other words, a curved portion provides the connection between the external lower transverse rib 25e and the lower intermediate recess 24 (which is in contact with the upper longitudinal rib 16).
[0091] As illustrated in [Fig. 4D], the lower plate 20 here has an internal lower transverse rib 25i. This is connected to the internal lower longitudinal rib 22i such that the internal cross-section between the internal longitudinal ribs 12i, 22i is widened (here along the -X direction). It extends transversely (along the X axis) towards the external lower longitudinal rib 22e, without being connected to it: its end is closed. In other words, a curved portion provides the connection between the internal lower transverse rib 25i and the lower intermediate recess 24.
[0092] Figure 4E illustrates the bipolar plate 1 in a short-circuit protection section P2inf. The lower plate 20 has a lower intermediate longitudinal rib 26, which connects transversely (along the X-axis) the outer lower longitudinal ribs 22e and inner lower longitudinal ribs 22i. The upper plate 10 has the upper intermediate recess 14, which extends transversely between the outer upper longitudinal ribs 12e and inner upper longitudinal ribs 12i. The upper intermediate recess 14 is superimposed on the lower intermediate longitudinal rib 26 and is in contact with it at the lower contact plane Pcinf.
[0093] As illustrated in [Fig. 4F], the upper plate 10 here has an external upper transverse rib 15e. It is connected to the external upper longitudinal rib 12e so that the internal cross-section of the external sealing line is widened (here along the +X direction). It extends transversely (along the X axis) towards the internal upper longitudinal rib 12i, without being connected to it: its end is closed. In other words, a curved portion provides the junction between the external upper transverse rib 15e and the upper intermediate recess 14 (which is in contact with the intermediate lower longitudinal rib 26).
[0094] As illustrated in [Fig. 4G], the upper plate 10 here has an internal upper transverse rib 15i. This is connected to the internal upper longitudinal rib 12i such that the internal cross-section between the ribs Internal longitudinal ribs 12i and 22i are widened (here along the -X direction). They extend transversely towards the external upper longitudinal rib 12e, without being connected to it: their end is closed. In other words, a curved portion provides the junction between the internal upper transverse rib 15i and the upper intermediate recess 14.
[0095] As illustrated in [Fig.4H], apart from the short-circuit protection parts Pcsup and Pcinf, the bipolar plate 1 can have a configuration identical to that of [Fig.4A].
[0096] Note that the transverse ribs (lower 25e, 25i and upper 15e, 15i) are not necessarily coplanar with the external longitudinal ribs 12e, 22e and / or internal ribs 12i, 22i. They are preferably in contact with a FAME diffusion layer over at least part of their width along the X-axis. Preferably, the external transverse ribs, for example upper 15e, are lower than the external longitudinal rib 12e, so as to maximize the mechanical crushing force of the external joint 5. By "lower," we mean here that the height of the external transverse ribs 15e (i.e., its distance from the reference plane Pref) is less than that of the external longitudinal rib 12e. This height difference can be on the order of 50 µm.
[0097] Furthermore, the internal longitudinal rib 12i may be lower than the distribution ribs that transversely delimit the distribution channels, so as not to over-compress the AME diffusion layer outside the reaction zone. The internal transverse ribs 15i may, however, have the same height as the distribution ribs. Moreover, the internal longitudinal rib 12i may have the same height as the external longitudinal rib 12e. What is stated here for the upper ribs applies equally to the lower ribs.
[0098] Figures 5A to 5C are schematic and partial views of a bipolar plate 1 according to different embodiment variants, where the external upper transverse ribs 15e and internal ribs 15i are illustrated.
[0099] Figure 5A illustrates an example where the transverse ribs (here the upper ribs 15e, 15i, but this is also the case for the lower ribs) extend in a straight line along the X-axis. Preferably, there is an interdigitation between the outer transverse ribs 15e and inner transverse ribs 15i, in the sense that each outer transverse rib 15e extends along the edge of an inner transverse rib 15i. In other words, the outer transverse ribs 15e and inner transverse ribs 15i have a length along the X-axis sufficient for an outer transverse rib to extend along an inner transverse rib. Thus, the flow of the reactive fluid is a meandering flow and not a straight flow along the Y-axis, preferably longer by a factor of at least 1.5 with respect to the rectilinear flow, which generates singular pressure losses at each change of flow direction, and thus greatly reducing short-circuit flow.
[0100] Figure 5B illustrates a variant where the transverse ribs 15e, 15i have a T-shape formed by a straight part extending along the X axis and an orthogonal straight part extending along the Y axis in both directions -Y and +Y. Here, the interdigitation of these transverse ribs 15e, 15i leads to a further increase in the meandering character of the short-circuit flow, and therefore the singular head losses, which further reduces this short-circuit flow.
[0101] Fig. 5C illustrates another variant where the transverse ribs 15e, 15i have an L-shape formed by a straight portion extending along the X-axis and an orthogonal straight portion extending along the Y-axis in one or the other of the two directions -Y and +Y. Here too, the interdigitation of these transverse ribs 15e, 15i leads to a further increase in the meandering character of the short-circuit flow, which further reduces this short-circuit flow.
[0102] Of course, other shapes of the transverse ribs in the XY plane can be considered, for example spiral shapes. It should also be noted that the internal and external transverse ribs improve the mechanical strength of the bipolar plate in the lateral zone, without degrading the quality of the external sealing line.
[0103] Figures 6A and 6B are schematic and partial views of a bipolar plate 1 according to one embodiment, [Fig.6B] being a longitudinal section in the lateral bypass zone Zcc.
[0104] As shown in [Fig. 6A], the lateral zone Zcc comprises a longitudinal alternation of short-circuit protection portions Plsup with an upper contact plane Pcsup and short-circuit protection portions P2inf with a lower contact plane Pcinf. The outer upper transverse ribs 15e and inner upper transverse ribs 15i are interdigitated L-shaped, as are the outer and inner lower transverse ribs (not visible).
[0105] As shown in [Fig.6B], in the anti-short-circuit parts Plsup with upper contact plane Pcsup, the upper sheet 10 has the upper longitudinal rib 16, and the lower sheet 20 has a lower recess 24 superimposed and in contact with the upper longitudinal rib 16, from which extend external and internal lower transverse ribs.
[0106] Furthermore, it should be noted here that the upper plate 10 has an upper curved portion 17 which provides the longitudinal connection (along the Y axis) between the upper intermediate rib 16 and the upper intermediate recess 14. Similarly, the lower plate 20 has a lower curved portion 27 which provides the longitudinal junction between the lower intermediate recess 24 and the lower intermediate rib 26. As shown in [Fig.6B], the upper curved portions 17 and lower 27 are offset along the Y axis so as not to be in contact with each other, this in order not to weaken the conductive sheets 10, 20 by a local transmission of mechanical stresses, while respecting the manufacturing and positioning tolerances.
[0107] Figures 7A to 7F are schematic and partial views of the bipolar plate 1 of [Fig.6A], in cross-section along different cutting lines.
[0108] Figure 7A illustrates the bipolar plate 1 in an anti-short-circuit portion Plsup with an upper contact plane Pcsup, where, in this section line, the lower sheet 20 has an external lower transverse rib 25e. It extends from the external lower longitudinal rib 22e towards the internal lower longitudinal rib 22i and bifurcates to form an L. Its opposite end is closed and has a curved portion that connects the external lower transverse rib 25e to the lower intermediate recess 24.
[0109] Fig. 7B illustrates the bipolar plate 1 in the same anti-short-circuit part Plsup with upper contact plane Pcsup, where, in this cutting line, the lower sheet 20 does not have a lower transverse rib, but the lower intermediate recess 24, superimposed and in contact with the upper longitudinal rib 16.
[0110] Figure 7C illustrates the bipolar plate 1 in the same anti-short-circuit portion Plsup with upper contact plane Pcsup, where, in this section line, the lower sheet 20 has an internal lower transverse rib 25i. It extends from the internal lower longitudinal rib 22i towards the external lower longitudinal rib 22e and bifurcates to form an L. Its opposite end is closed and has a curved portion which connects the external lower transverse rib 25i to the lower intermediate recess 24.
[0111] Figure 7D illustrates the bipolar plate 1 in a short-circuit protection portion P2inf with a lower contact plane Pcinf, where, in this cross-section, the lower plate 20 has a lower intermediate longitudinal rib 26, and the upper plate 10 has an upper intermediate recess 14, superimposed on and in contact with the lower intermediate longitudinal rib 26. Here, the upper plate 10 has an internal upper transverse rib 15i. It extends from the internal upper longitudinal rib 12i towards the external upper longitudinal rib 12e, and bifurcates to form an L. Its opposite end is closed and has a curved portion that connects the internal upper transverse rib 12i to the upper intermediate recess 14.
[0112] Fig. 7E illustrates the bipolar plate 1 in the same anti-short-circuit part P2inf with lower contact plane Pcinf, where, in this cutting line, the upper sheet 10 does not have an upper transverse rib, but has the upper intermediate recess 14, superimposed on and in contact with the lower intermediate longitudinal rib 26.
[0113] Figure 7F illustrates the bipolar plate 1 in the same anti-short-circuit portion P2inf with lower contact plane Pcinf, where, in this section line, the upper plate 10 has an external upper transverse rib 15e. It extends from the external upper longitudinal rib 12e towards the internal upper longitudinal rib 12i, and bifurcates to form an L. Its opposite end is closed and has a curved portion which connects the external upper transverse rib 15e to the upper intermediate recess 14.
[0114] Specific embodiments have just been described. Various variants and modifications will be apparent to those skilled in the art.
Claims
1. Demands Bipolar plate (1) of an electrochemical cell, comprising: • upper (10) and lower (20) sheets, superimposed one on top of the other, comprising: • lower and upper distribution circuits (7), superimposed one on the other, adapted to bring reactive fluids respectively to lower and upper electrodes; • upper internal longitudinal ribs (12i) and lower internal longitudinal ribs (22i), superimposed on each other, forming respectively a longitudinal border of the lower and upper distribution circuits (7); • upper (12e) and lower (22e) external longitudinal ribs, superimposed on each other, extending along the internal longitudinal ribs (12i, 22i), laterally delimiting, with the internal longitudinal ribs (12i, 22i), a lateral zone called bypass (Zcc) extending longitudinally along the distribution circuits (7); • in the lateral bypass zone (Zcc) there is a longitudinal alternation: • of at least one first anti-short-circuit part (Plsup), where: the upper sheet (10) has an upper intermediate longitudinal rib (16), extending throughout the first anti-short-circuit part (Plsup); and where the lower sheet (20) has a lower intermediate recess (24), superimposed on and in contact with the upper intermediate longitudinal rib (16); • of at least one second short-circuit protection part (P2inf), where: the lower sheet metal (20) has a lower intermediate longitudinal rib (26) extending throughout the second short-circuit protection part; and where the upper sheet metal (10) having an upper intermediate recess (14), superimposed and in contact with the lower intermediate longitudinal rib (26); • characterized in that, in the first anti-short circuit part (Plsup), the lower sheet (20) comprises a longitudinal succession of lower transverse ribs, including: internal lower transverse ribs (25i), respectively external (25e), extending from the internal lower longitudinal rib (22i), respectively external (22e), and having a closed opposite end not connected to the external lower longitudinal rib (22e), respectively internal (22i);• and in that, in the second anti-short-circuit part (P2inf), the upper sheet (10) comprises a longitudinal succession of upper transverse ribs, including: internal upper transverse ribs (15i), respectively external (15e), extending from the internal upper longitudinal rib (12i), respectively external (12e), and having a closed opposite end not connected to the external upper longitudinal rib (12e), respectively internal (12i).;
2. Bipolar plate (1) according to claim 1, comprising several first anti-short-circuit parts (Plsup) arranged alternately longitudinally with several second anti-short-circuit parts (P2sup).
3. Bipolar plate (1) according to claim 1 or 2, wherein, in the first anti-short-circuit part (Plsup), the lower internal (25i) and external (25e) transverse ribs of the lower sheet (20) are interdigitated, so that each lower internal transverse rib (25i) extends along an external lower transverse rib (25e).
4. Bipolar plate (1) according to any one of claims 1 to 3, wherein, in the second short-circuit protection portion (P2inf), the upper internal (15i) and external (15e) transverse ribs of the upper sheet (10) are interdigitated, such that each rib upper internal transverse (15i) extends along an upper external transverse rib (15e).
5. Bipolar plate (1) according to any one of claims 1 to 4, wherein the upper (15e, 15i) and lower (25e, 25i) transverse ribs have, in a plane parallel to the bipolar plate (1), a straight, T, L or spiral shape.
6. Bipolar plate (1) according to any one of claims 1 to 5, wherein the upper external transverse ribs (15e), respectively lower (25e), have a height, with respect to a reference plane (Pref) passing between the upper external longitudinal ribs (12e) and lower (22i), less than that of the upper external longitudinal rib (12e), respectively lower (22e).
7. Bipolar plate (1) according to any one of claims 1 to 6, wherein the lower intermediate recess (24) separates, along an axis orthogonal to a longitudinal axis of the lateral bypass zone (Zcc), the outer lower transverse rib (25e) from the inner lower longitudinal rib (22i), and the inner lower transverse rib (25i) from the outer lower longitudinal rib (22e).
8. Bipolar plate (1) according to any one of claims 1 to 7, wherein the upper intermediate recess (14) separates, along an axis orthogonal to a longitudinal axis of the lateral bypass zone (Zcc), the outer upper transverse rib (15e) from the inner upper longitudinal rib (12i), and the inner upper transverse rib (15i) from the outer upper longitudinal rib (12e).
9. Bipolar plate (1) according to any one of claims 1 to 8, wherein the upper (12e) and lower (22i) external longitudinal ribs are each in contact with a sealing gasket (5).
10. Electrochemical cell, comprising at least one bipolar plate (1) according to any one of the preceding claims, and a membrane / electrode assembly (30) in contact with the bipolar plate (1).
11. Electrochemical reactor, comprising at least one electrochemical cell according to the preceding claim.