Fuel cell stack, fuel cell, and related vehicle

Abstract

The invention relates to a fuel cell stack comprising a plurality of identical bipolar plates (12) stacked in a stacking direction (A11), each bipolar plate (12) being formed by two monopolar plates placed one on top of the other and together forming at least one pocket (20) at one end of the bipolar plate (12), each pocket (20) having an end opening (28) configured to receive a pin (22) of a measurement module (18) of the fuel cell, any two consecutive bipolar plates (12) being stacked head-to-tail.

Description

[Technical field]

[0001] The present invention relates to a fuel cell stack, a fuel cell comprising such a stack, and a vehicle comprising such a fuel cell. [Background technology]

[0002] Fuel cells are used as energy sources in various applications, particularly in electric vehicles. In a polymer electrolyte membrane fuel cell (PEMFC), hydrogen is supplied to the anode of the fuel cell and oxygen is supplied as the oxidant to the cathode. A polymer electrolyte membrane fuel cell (PEMFC) comprises a membrane electrode assembly (MEA) that comprises a non-conductive, proton exchange, solid polymer electrolyte membrane with an anode catalyst on one side and a cathode catalyst on the other side. The membrane electrode assembly (MEA) is sandwiched between a pair of conductive elements called bipolar plates, generally with intervening gas diffusion layers made from carbon fiber or the like. The bipolar plates are generally rigid and thermally conductive. The bipolar plates function primarily as separators for the chemical species that form the gas reactants of the fuel cell and possibly as separators for a cooling fluid, and the bipolar plates also function as current collectors for the anode and cathode. The bipolar plates have passages with suitable openings for distributing gas reactants from the fuel cell across the surfaces of the respective anode and cathode catalysts, and for draining reaction products or residues, particularly water produced at the cathode.

[0003] A membrane electrode assembly sandwiched between two bipolar plates forms a unit cell of the fuel cell, and multiple unit cells are stacked to form a fuel cell stack. During fuel cell operation, it is advantageous to monitor the unit cells, in particular by measuring the electrical properties of the cells.

[0004] For example, US Patent No. 9997792(A1) discloses a fuel cell comprising a stack of cells connected to a computer by means of a ribbon of cables connected to each of the cells by a connecting tongue, the cables being held by a harness to press the cables against the connecting tongue. However, measurements made with this type of configuration are unreliable, the cells take up a lot of space, and furthermore the cables are prone to being damaged by mechanical stresses such as vibrations or expansion generated during the operation of the cells, thus shortening their useful life.

[0005] DE 102021202538 A1 describes a fuel cell comprising a cell stack. Each of the bipolar plates comprises electrical contacts, each configured to receive a mating connector. The electrical contacts are aligned along the axis of the stack of cells, while insulating elements are positioned at the periphery of the membrane electrode assembly, between each bipolar plate, in order to prevent short circuits between two adjacent bipolar plates, in particular during connection of the electrical contacts to the mating connector. However, the insulating elements, and thus the stack of bipolar plates, are relatively bulky. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] U.S. Patent No. 9997792(A1) [Patent Document 2] DE 102021202538 A1 Summary of the Invention [Problem to be solved by the invention]

[0007] It is these problems that the present invention seeks to remedy more specifically by proposing an improved fuel cell stack that is compact and more reliable. [Means for solving the problem]

[0008] To that end, the invention relates to a fuel cell stack, according to the invention, comprising a plurality of bipolar plates identical to one another, each extending along a median plane and stacked along a stacking direction perpendicular to the median plane, whereby two consecutive bipolar plates form between them a cell of the stack, each bipolar plate being formed by two monopolar plates superimposed and forming together at least one pocket at one end of the bipolar plate, each pocket having an end opening adapted to receive a pin of a measurement module of the fuel cell, while any two consecutive bipolar plates are stacked head-to-tail.

[0009] With the present invention, the head-to-tail mounting of the bipolar plates makes it possible to provide pockets whose openings each have a width, measured along the direction of the stack, that is therefore greater than the spacing between two successive bipolar plates, thereby facilitating the insertion of the pins in each pocket and, in addition, the pins are thicker and therefore stronger, which contributes to the reliability of the stack.

[0010] According to advantageous but non-essential aspects of the invention, such a stack may incorporate one or more of the following features, taken individually or according to any technically acceptable combination: - each pocket opens through an end opening in a direction of connection that is parallel to the longitudinal direction of the stack, the longitudinal direction being perpendicular to the direction of the stack; On the other hand, for any two consecutive bipolar plates, the direction of connection of each pocket of one of the two bipolar plates is oriented opposite to the direction of connection of each pocket of the other bipolar plate. each bipolar plate comprises a connection zone in which at least one pocket of the bipolar plate is provided and a mating zone located opposite the connection zone with respect to the center of the bipolar plate; whereas, for any two consecutive bipolar plates, the connection zone of one of the two bipolar plates is arranged facing the mating zone of the other bipolar plate in the stacking direction; The stack further comprises interrupt means interposed between each connection zone and a mating opposing zone so as to limit deformation of each pocket of the connection zone when a pin associated with the pocket is inserted into said pocket. the mating zones are provided with ridges protruding from the polar plate and extending towards the opposite connecting zone so as to limit deformation of each pocket of the connecting zone when the pin associated with the pocket is inserted into the pocket, thereby forming interruption means. the interrupting means comprise a spacer interposed between each connecting zone and the opposing mating zone; Meanwhile, each spacer is fastened to a mating zone. - each bipolar plate has an anode outer surface and a cathode outer surface; Meanwhile, for a given bipolar plate, the mating zone of the bipolar plate comprises a spacer fastened to the anode face of the bipolar plate and a spacer fastened to the cathode face of the bipolar plate. - each bipolar plate has an anode outer surface and a cathode outer surface; Meanwhile, for a given bipolar plate, the interruption means comprises three spacers, two of which are arranged on either side of the mating zone of the bipolar plate, on the anode face of the bipolar plate and on the cathode face of the bipolar plate, while the third spacer is arranged between the two monopolar plates forming the bipolar plate. the interrupting means comprise a spacer interposed between each connecting zone and the opposing mating zone; whereas for each bipolar plate, the interrupt means associated with the plate comprises a bridge of material connecting the spacers together; The interrupting means are mounted to the edges of the associated bipolar plates such that the spacers (32) are positioned on either side of the mating zone. the interrupting means comprise a spacer interposed between each connecting zone and the opposing mating zone; Meanwhile, the stack also comprises membrane electrode assemblies each received between two successive bipolar plates and extending between a connection zone associated with the two bipolar plates and an opposing mating zone, Some of the spacers are fastened to the membrane electrode assemblies. - The spacer is made from an elastomeric material. each bipolar plate comprises a connection zone in which at least one pocket of the bipolar plate is provided and a mating zone located opposite the connection zone with respect to the center of the bipolar plate; Whereas, for any two consecutive bipolar plates, the connection zone of one of the two bipolar plates is located opposite the mating zone of the other bipolar plate along the stacking direction; The connection bands are distributed in two rows, the two rows extending along the stacking direction, For each row, the end openings of the pockets of that row are geometrically supported by an opening plane that is parallel to the stacking axis, and the mating zones associated with the connection zones of said row are formed set back from the opening plane at a distance from the opening plane that is comprised between 1 mm and 5 mm, preferably 2 mm or more. Advantageously, for at least one cell of the stack, the cell comprises: a first polar plate, peripheral bands, and A reactive fluid flow region surrounded by a surrounding region A first polar plate comprising: - a membrane electrode assembly that is superimposed on a first polar plate according to a stacking direction, a peripheral portion opposite the peripheral band along the stacking direction; a central portion comprising a proton exchange polymer membrane and surrounded by a peripheral portion; and At least one gas diffusion layer interposed along the stacking direction between the proton exchange polymer membrane and the flow field of the first polar plate. A membrane electrode assembly comprising: a first peripheral seal, a main part interposed along the stacking direction between the peripheral zone and the peripheral part of the membrane electrode assembly, which surrounds the flow field and said gas diffusion layers associated with the flow field and provides a seal against the reactive fluids between, on the one hand, in the interior of the cell, a compartment of the cell defined between the peripheral part of the membrane electrode assembly and the peripheral zone, and, on the other hand, a zone outside the cell beyond the main part facing the compartment; Fins extending from the main section into the compartment A first peripheral seal comprising: Equipped with Where: - the main part comprises two longitudinal portions each extending parallel to a longitudinal direction perpendicular to the stacking direction, extending along the flow area and arranged on either side of the flow area, the compartments comprising two bypass zones each defined between the respective longitudinal portion on the one hand and the flow area and a gas diffusion layer associated with the flow area on the other hand, - for each longitudinal portion, at least one fin extends from that longitudinal portion into a corresponding bypass region; - Each fin is - joints through which the fins are attached to the corresponding longitudinal sections; an edge interposed between the gas diffusion layer and the peripheral zone along the stacking direction; intermediate sections connecting the joints to the ends, which are inclined in projection onto the median plane with respect to the direction of stacking and to the transverse direction perpendicular to the longitudinal direction; Equipped with for each longitudinal section, the fins attached to the longitudinal section are inclined along the same direction relative to the transverse direction; When the stack is in an operational configuration, the fins attached to the lower positioned longitudinal portion are inclined in the same direction as the flow of reactive fluid associated with the first polar plate. Advantageously, for each peripheral seal, the fins attached to opposite longitudinal portions are inclined in opposite directions relative to the transverse direction.

[0011] The present invention relates to - A stack as described above, - two end plates on either side of the stack; a plurality of modules each having a pin connected to a respective pocket for measuring electrical characteristics of the cell; The present invention further relates to a fuel cell comprising the same.

[0012] Finally, the invention relates to a vehicle equipped with at least one fuel cell as previously described.

[0013] The invention will be better understood on reading the following description, given purely by way of example, with reference to the drawings in which: [Brief description of the drawings]

[0014] [Figure 1] 1A and 1B are schematic front and side perspective views of a fuel cell according to a first embodiment of the present invention; [Diagram 2] FIG. 2 is a schematic diagram of a stack of bipolar plates of the fuel cell shown in FIG. 1. [Diagram 3] FIG. 2 is a schematic perspective view of the connections between modules and cells of the bipolar plate stack of the fuel cell shown in FIG. 1. [Figure 4] Schematic representation of the stack of FIG. 1 in two illustrations a) and b), depicted in partially exploded perspective and oblique view. [Diagram 5] FIG. 2 is a schematic cross-sectional view of the stack shown in FIG. 1. [Figure 6] 4 is a schematic cross-sectional view of a fuel cell stack according to another embodiment. [Figure 7] 4 is a schematic cross-sectional view of a fuel cell stack according to another embodiment. [Figure 8] 4 is a schematic cross-sectional view of a fuel cell stack according to another embodiment. [Figure 9] 4 is a schematic cross-sectional view of a fuel cell stack according to another embodiment. [Figure 10] 4 is a schematic cross-sectional view of a fuel cell stack according to another embodiment. [Figure 11] 5 shows in two illustrations a) and b) a bipolar plate belonging respectively to the stack and to the fuel cell shown in FIG. 4 according to another embodiment of the invention. [Figure 12] FIG. 2 shows a schematic diagram in two illustrations a) and b) of a detail of a bipolar plate and a cross-section of a stack belonging to the same fuel cell according to another embodiment of the invention. [Figure 13] FIG. 2 is a schematic perspective view of the stack shown in FIG. 1. [Figure 14] 14 shows a detailed top view of the stack of FIG. 13 and a cross-sectional view of a portion of the stack of FIG. 13 in the two illustrations a) and b), respectively. [Figure 15] FIG. 14 shows in two illustrations a) and b) respectively the two opposite faces of the bipolar plate of the stack shown in FIG. 13. [Figure 16] FIG. 2 shows a detailed view of two bipolar plates belonging to a fuel cell according to an alternative embodiment of the invention in two illustrations a) and b). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] 1 and 2 show a fuel cell 10 according to a first embodiment of the invention. The fuel cell 10 comprises a stack 11 of bipolar plates 12.

[0016] In known manner, each bipolar plate 12 has two opposite outer faces, an anode face and a cathode face.

[0017] Each bipolar plate 12 is formed here by two superimposed monopolar plates 13, which include a first polar plate 13A, here a cathode plate, and a second polar plate 13B, here an anode plate, the first polar plate 13A and the second polar plate 13B being visible in FIG. 5. The expression "two consecutive monopolar plates 13" refers to the two monopolar cathode plates 13A and anode plates 13B associated with the same bipolar plate 12. The monopolar plates 13 are also simply called polar plates 13. In such a bipolar plate 12 formed by two superimposed monopolar plates 13, the anode monopolar plate 13B forms the anode surface of the bipolar plate 12, and the cathode monopolar plate 13A forms the cathode surface of the bipolar plate 12.

[0018] The cooling circuit is advantageously arranged between two monopolar plates which are assembled together in a sealed manner. Each bipolar plate 12 has a substantially flat shape extending along a median plane P12.

[0019] In such an embodiment, the two monopolar plates 13 associated with the same bipolar plate 12 are made from metal and are welded or joined together.

[0020] 4, the fuel cell 10 comprises a plurality of cells 14 made in the form of a stack 11 of bipolar plates 12, the cells 14 being formed between two successive bipolar plates 12. The stack 11 thereby consists of a plurality of individual cells 14 connected in series. For each individual cell 14, the fuel cell 10 further comprises a membrane electrode assembly 200, which is interposed between the two bipolar plates 12 associated with the cell 14. The membrane electrode assembly 200 is also simply referred to as an MEA 200.

[0021] Thereby, each bipolar plate 12 is common to two adjacent cells 14. Each membrane electrode assembly 200 extends along a mid-plane P200 that is parallel to two median planes P12 associated with the bipolar plates 12 between which the membrane electrode assembly 200 is interposed. The mid-plane P200 is perpendicular to the stack axis A11.

[0022] Fuel cell 10 is intended for use, for example, in a motor vehicle, and more particularly in an electrically powered vehicle, in which the electrical energy supplying the prime mover is provided essentially, if not entirely, by fuel cell 10.

[0023] The bipolar plates 12 are stacked along a stacking direction A11. The stacking direction A11 is perpendicular to a median plane P12 of the stacked bipolar plates 12. In other words, the median plane P12 is a plane transverse to the stacking direction A11. A longitudinal direction L and a transverse direction T are also defined which together with the stacking direction A11 form a Cartesian coordinate system.

[0024] The fuel cell 10 also includes two end plates 16 arranged on either side of the stack 11. The stack 11 is sandwiched between the two end plates 16 and compressed in a stacking direction A11 between the end plates 16. The end plates 16 are made, for example, from aluminum.

[0025] An external fluid circuit (not shown) is connected to the cell 10 at the level of the end plates 16, and the reactive gases are distributed to the membrane electrode assemblies 200 at the surface of the bipolar plates 12 via channels, which will be considered in more detail later, arranged in the bipolar plates 12 and organized in a network of channels 17 comprising flow areas 103 and generally two homogenization areas 104. For each bipolar plate 12, a center C12 of the bipolar plate is defined, which here corresponds to the center of symmetry of the network of channels 17.

[0026] A module 18 for measuring at least one electrical characteristic of the cells 14 is connected to the stack 11 of bipolar plates 12 in order to measure an electrical characteristic of the cells 14, such as, for example, the voltage at the terminals of one or more cells 14. Each module 18 serves to monitor the condition of the stack 11 in order to adapt the control of the fuel cell system 10.

[0027] Thus, two consecutive monopolar plates 13 belonging to the same bipolar plate 12 are advantageously arranged back-to-back to form at least one pocket 20 between them at one edge of the bipolar plate 12, for example at an edge arranged at one end 21 of the bipolar plate 12 along the longitudinal direction L. The edge 21 is thus in this example an edge of the bipolar plate 12 extending parallel to the transverse direction T.

[0028] Each pocket 20 is configured to receive a pin 22 of a module 18 for measuring an electrical characteristic of a cell 14 .

[0029] The bipolar plates 12 are identical to each other. Two consecutive bipolar plates 12 are stacked head-to-tail such that at least one pocket 20 of every other bipolar plate 12 is at the same height in the vicinity of the module 18, as seen in FIG.

[0030] According to the illustrated example, each bipolar plate 12 forms exactly two pockets 20 for respectively receiving the pins 22. For each bipolar plate 12, the pockets 20 for receiving the bipolar plate 12 are arranged adjacent to each other and form a connection zone 24A of the bipolar plate 12.

[0031] Each bipolar plate 12 also comprises a mating zone 24B. The mating zone 24B of a bipolar plate 12 is a portion of the bipolar plate 12 through which the constituent material of the plate extends, preferably a smooth portion. For each bipolar plate 12, the mating zone 24B is symmetrically positioned opposite the connection zone 24A with respect to the center C12 of the bipolar plate 12. Thereby, for any two consecutive bipolar plates 12 of the stack 11, the connection zone 24A of one of the two plates 12 is located opposite the mating zone 24B of the other bipolar plate 12 along the stacking direction A11. For any three consecutive bipolar plates 12 in the stack 11, the connection zone 24A of one of the three plates 12 that is positioned between two other surrounding bipolar plates 12 in the stacking direction A11 is disposed along the stacking direction A11 opposite the mating zone 24B of each of the other two surrounding bipolar plates 12 in the stacking direction A11.

[0032] As shown in Fig. 2, the stack 11 comprises two rows 23 of connection bands 24A, each of the rows 23 extending along the stacking direction A11. The two rows 23 are positioned symmetrically with respect to each other with respect to an axis parallel to the stacking direction A11 and passing through the center C12 of each of the bipolar plates. In the example, the two rows 23 are positioned on either side of a transverse plane of the stack, the transverse plane being perpendicular to the longitudinal direction L. In the example shown, the module 18 is connected to only one of the rows 23 positioned on the upper side of Fig. 2, the other row being left unused. In a variant (not shown), another module, such as the module 18, is connected to the other row of the connection band 24A.

[0033] What is valid for one of the rows 23 of the connection band 24A can be transferred to the other row 23 of the connection band 24A. In what follows, the row 23 to which the modules 18 are connected will mainly be described.

[0034] The second pocket 20 makes it possible to measure four wires per group of twenty cells 14. The same is used to measure the impedance.

[0035] More specifically, each pocket 20 is shaped to cooperate with the pin 22 .

[0036] For each pocket 20 , two successive monopolar plates 13 , when in contact with each other, together define a peripheral wall 26 of the pocket 20 .

[0037] Preferably, each pocket 20 has an open end 28 whose peripheral wall 26 has a conical shape. More generally, the open end 28 has a flared shape. Such a shape has the advantage of guiding the pins 22 of the module 18 during their insertion into said pockets 20.

[0038] The open end 28 of the same row 23 is geometrically supported by an open plane P28, which is a plane parallel to the stacking direction A11 and, in one example, a transverse plane, in other words, a plane perpendicular to the longitudinal direction L.

[0039] It should be understood that each pin 22 is inserted into the corresponding pocket 20 according to an insertion movement, which is a substantially translational movement, directed towards the interior volume of the corresponding pocket 20. For each pocket 20, a direction of connection D20 is defined which substantially corresponds to the opposite direction of the insertion movement of the pin 22 and thus corresponds to a direction parallel to the insertion movement but directed along the opposite direction. For each pocket 20 of a given bipolar plate 12, each direction of connection D20 is parallel to the median plane P12 of the bipolar plate 12. Each pocket 20 thereby opens outwardly via the open end 28 of the pocket 20 along the direction of connection D20.

[0040] Preferably, the pockets 20 of the same connection zone 24A are oriented in the same direction, i.e. the directions D20 of connections associated with the pockets 20 are parallel to each other. Thereby, by extension, for each connection zone 24A, the direction D20 of connections of each pocket 20 associated with the connection zone 24A is also the direction of connections for the connection zone 24A. For each row 23 of connection zones 24A, the direction D20 of connections associated with the connection zone 24A is perpendicular to the opening plane P28 associated with the connection zone 24A.

[0041] Preferably, for any two consecutive bipolar plates 12, the direction D20 of connection of each pocket 20 of one of the two bipolar plates 12 is oriented opposite to the direction of connection of each pocket 20 of the other bipolar plate 12.

[0042] Advantageously, the peripheral wall 26 of each pocket 20 has a ridge 26B so as to form a small cross-sectional passage for the pin 22. The ridge 26B serves to stiffen the pocket 20 and makes it possible to ensure electrical contact inside the pocket 20 between the pin 22 and the pocket 20.

[0043] Each module 18 here comprises ten aligned pins 22 arranged to connect ten pockets 20 to said module 18, i.e. twenty cells 14, as seen in Fig. 3, and an additional pin 25 for connecting a second pocket 20 of one of the twenty cells 14. The ten aligned pins 22 serve to measure the voltage of two consecutive cells 14 between two consecutive pins 22. The pins 22, 25 of a module 18 are preferably identical.

[0044] In the illustrated embodiment, each connection band 24A includes two pockets 20, one of which is associated with one of the pins 22 of the module 18, while the other pocket 20 is configured to receive an additional pin 25.

[0045] Although the illustrated example includes two modules 18, the fuel cell 10 is not limited to two modules, but may include more modules, such as, for example, ten modules 18 for connecting 200 cells 14. Similarly, the number of pins 22 for each module 18 is not a limitation.

[0046] The additional pins 25 are arranged substantially parallel to the array of pins 20, preferably at the longitudinal ends of the module 18. For example, the additional pins 25 are configured to inject a current into the pocket 20 in which the current is received, thereby allowing the impedance at the twenty cells 14 to be measured.

[0047] 4, each bipolar plate 12, and thus the two monopolar plates 13 associated with it, comprises an opening 101, a peripheral zone 102, a flow area 103 and two homogenization areas 104. In other words, the elements 101-104 are on two opposite faces of each bipolar plate 12. The flow area 103 and the two homogenization areas 104 are included in a passage network 17.

[0048] The peripheral zone 102 extends around the entire periphery of the bipolar plate 12, where it defines the edges of the openings 101, the homogenization areas 104 and the flow areas 103. The openings 101, the homogenization areas 104 and the flow areas 103 are located inside the peripheral zone 102. The peripheral zone 102 extends in a plane perpendicular to the stacking direction A11, i.e. parallel to the median plane P12.

[0049] Each opening 101 is intended either for the injection of a reactive or cooling fluid for each cell 14 of the stack 11 or for the discharge of a reactive or cooling fluid. The reactive or cooling fluid is the working fluid of the fuel cell 10. The openings 101 here have a closed contour, so that they form ducts inside the stack 11, the ducts being called "internal manifolds". In a variant (not shown), the working fluid of the fuel cell 10 is supplied by ducts outside the stack 11, the ducts being called "external manifolds". In such a case, the openings 101 have an open contour. The principles of the invention are valid regardless of the type of duct.

[0050] In the example, a row of three openings 101 is positioned on one side of the polar plate 13, here the cathode plate 13A, with respect to the transverse direction T, the three openings 101 being aligned in the transverse direction T. Another row with three other openings 101 is positioned on the other side of the polar plate 13, the other three openings 101 also being aligned in the transverse direction T. Each of the two rows of openings 101 is arranged near a respective longitudinal end of the polar plate 13.

[0051] For each reactive or cooling fluid, and thus for each fluid flow region 103 of the cell 12, an opening 101 forms a fluid supply for the associated flow region and another opening positioned symmetrically opposite with respect to the centre C12 serves to drain the fluid for the associated flow region 103, the two openings 101 positioned symmetrically opposite with respect to the centre C12 preferably having symmetrical shapes in accordance with central symmetry with respect to the centre C12.

[0052] The flow field 103 extends across the face of the plate 13A oriented towards the membrane electrode assembly 200, between the two uniformization regions 104 in the longitudinal direction L. Each uniformization region 104 is disposed between the flow field 103 and the openings 101 along the longitudinal direction L. Each uniformization region 104 generally includes a passageway connecting one of the openings 101 to the flow field 103. In the illustrated example, the passageway of the uniformization region 104 is similar and formed in the same way as the passageway of the flow field 103, except for its orientation, which is now widened.

[0053] Alternatively (not shown), the passages of the uniformization region 104 have a different width and / or depth than the passages of the flow region 103. Similarly, the passages of the uniformization region 104 may be made in a different manner, in particular by a different technical method, than the passages of the flow region 103. For example, the passages of the uniformization region 104 may be made in the form of ridges applied by addition of a metallic, elastomeric or polymeric material to a portion of the polar plate 13 that may or may not be planar, while the passages of the flow region 103 may be made by deep drawing, or vice versa.

[0054] For the cathode plate 13A, the first homogenization region 104 distributes the reactive fluid coming from one of the openings 101 so that the fluid flows through the flow region 103 along the longitudinal direction L. The second homogenization region 104 serves to discharge the reactive fluid distributed throughout the flow region 103 to the other opening 101 located opposite the plate 13A, where the reactive fluid is discharged.

[0055] The two openings 101 and the two homogenization regions 104 bounded by a flow region 103 are positioned opposite each other with respect to the center C12, in other words, the two openings 101 are arranged symmetrically with respect to the center C12. For each flow region 103, two symmetric openings 101 opposite with respect to the center C12 are associated with the flow region 103, and the two openings 101 form a flow region.

[0056] For each reactive or cooling fluid, and therefore for each flow region of the cell, the two homogenization regions 104 are preferably symmetrical according to central symmetry about the center C12, both in the shape of the homogenization region 104 and in the arrangement of the passages of the homogenization region 104.

[0057] In a variant (not shown), the polar plate 13 does not comprise a homogenization region 104 and the flow region 103 is connected directly to the opening 101 .

[0058] Thereby, on the face of the plate 13A facing towards the conjugate 200, only one of the reactive fluids flows oppositely along the longitudinal direction L from one of the openings 101 to the other of the openings 101 through the flow field 103. For the cathodic polar plate 13A, the reactive fluid is a cathodic reactive fluid such as air or oxygen.

[0059] In the illustrated example, the membrane electrode assembly 200 or MEA 200 comprises a peripheral portion 202, an opening 201 and a central portion 203. The peripheral portion 202 extends through the periphery of the MEA 200 and defines edges of the opening 201 and the central portion 203 located inside the peripheral portion 202. The opening 201 has a closed contour. The peripheral portion 202 extends in a plane perpendicular to the stacking direction A11 and parallel to the median plane P12.

[0060] The openings 201 of the MEA 200 are made in the membrane electrode assembly 200 for the flow of reactive fluids through the MEA along the stacking direction A11. Each opening 201 extends one of the openings 101 of the cathode polar plate 13A along the stacking direction A11 to form a through duct (or manifold) for the working fluid of the fuel cell. In other words, the openings 101 and 201 face each other along the stacking direction A11. In the example, each opening 201 has the same shape as the opening 101 that it faces.

[0061] In the stack 11, the openings 101 in the bipolar plates 12 and the openings 201 in the membrane electrode assemblies 200 together form ducts, also called "internal manifolds", inside the stack 11. In a variant (not shown), the working fluid of the fuel cell 10 is supplied by ducts external to the stack 11, which ducts are called "external manifolds". In such a case, the openings 101 in the bipolar plates 12 each have an open profile. The principles of the invention are valid regardless of the type of manifold.

[0062] The central portion 203 of the MEA 200 faces the flow area 103 and completely covers the flow area 103 along the stacking direction A11. The peripheral periphery of the central portion 203 of the MEA 200 overlaps, where appropriate, the inner periphery of the peripheral portion 202 of the MEA 200.

[0063] 5, the central part 203 of the MEA 200 comprises a membrane 204, which is a proton exchange polymer membrane. The membrane 204 extends parallel to a median plane P12 facing the flow field 103 in the stacking direction A11 and is substantially flat. The membrane 204 is preferably flush with the peripheral part 202 of the MEA 200. The membrane 204 may be covered with a layer of catalyst on its two faces parallel to the median plane P12. In the illustrated example, the membrane 204 extends beyond the flow field 103, in particular when the central part 203 overlaps a portion of the peripheral part 202.

[0064] The membrane 204 of each MEA 200 is embedded between two gas diffusion layers (GDLs) 205. Each diffusion layer 205 extends parallel to the median plane P12 and is interposed along the stacking direction A11 between a central portion 203 of the MEA 200 and an opposing polar plate 13. The central portion 203 embedded between the GDLs 205 is considered to extend along the midplane P200.

[0065] The MEA 200 advantageously comprises a holding frame 206 for supporting the central portion 203, and more particularly for supporting the membrane 204. The holding frame 206 thus forms the peripheral portion 202. In the example shown in Fig. 5, the holding frame 206 clamps a peripheral portion of the outer periphery of the membrane 204 along the stacking direction A11 to hold the membrane 204. The holding frame 206 thus clamps the entire portion of the membrane 204 that overlaps the peripheral portion 202 along the stacking direction A11.

[0066] In a variant (not shown), it is also possible that, instead of the retaining frame 206, the same membrane, such as the membrane 204, is arranged to form both the central part 203 and the peripheral part 202. However, the arrangement shown is preferred, since the retaining frame 206 is stronger, more flexible and more brittle compared to the membrane 204. The retaining frame 206 consists of two half-frames of substantially identical shape, intended to be pressed flat against one another, for example made from a polymeric film, such as polyethylene terephthalate, known by the abbreviation PET, or polyethylene naphthalate, known as PEN. When made from a polymeric film, the two half-frames are assembled to one another, for example by gluing.

[0067] In the illustrated example, each diffusion layer 205 entirely covers the opposing central portion 203, more particularly the membrane 204, and advantageously projects over the peripheral portion 202, i.e. over the inner periphery of the holding frame 206 which sandwiches the membrane 204. In particular, the gas diffusion layer 205, at least in the zone corresponding to the flow chamber 103, presses against the network of channels 17 along the stacking direction A11 and against the membrane 204 along the opposite direction. The gas diffusion layer 205 is advantageously made of a porous material and allows the diffusion of reactive fluids from the channels 17 to the membrane 204 during operation of the cell 14 and, where appropriate, the diffusion of reaction products coming from the membrane 204 to the channels 105 for evacuation.

[0068] The pins 22, 25 of each of the modules 18 are designed to promote effective and durable electrical contact over time between the module 18 and its corresponding bipolar plate 12. To that end, the pins 22, 25 of each of the modules 18 are shaped, for example, such that when the pins 22, 25 are inserted into the corresponding pocket 20, the pins 22, 25 exert two opposing forces on the peripheral wall 26 of the pocket 20. With reference to Figure 5, it can be seen that when the pins 22, 25 are inserted into the corresponding pocket 20, the two polar plates 13A and 13B that form the corresponding bipolar plate 12 tend to move away from each other.

[0069] The stack 11 further comprises interrupting means 30 arranged between each connection zone 24A and the opposite mating zone 24B so as to limit the deformation of each pocket 20 of the connection zone 24A when the pin 22 associated with the pocket 22 is inserted into the pocket 20, more specifically so as to limit the ability of the polar plates 13A and 13B to move apart during the insertion of the pins 22, 25. Preferably, the interrupting means 30 are aligned with each of the pockets 20 along the stacking direction A11. Preferably, the interrupting means 30 are arranged on both sides of the chamber 20 along the stacking direction A11.

[0070] In the example of Fig. 5, for each bipolar plate 12, the interrupting means 30 comprises two spacers 32, for example of parallelepiped shape, with two opposite faces parallel to the median plane P12. Preferably, each spacer 32 is fastened to the mating zone 24B, thereby being interposed between the mating zone 24B and the oppositely positioned connecting zone 24A. Thereby, for a given bipolar plate 12, the mating zone 24B comprises a spacer 32 on the anode face of the bipolar plate 12 and a spacer 32 on the cathode face of the bipolar plate 12. In this example, the spacers are made of an electrically insulating material. Furthermore, it may be advantageous for the spacers to be made of an elastic material, more particularly of an elastomer, and thus in particular of an electrically insulating elastomer. The spacers 32 are made here from polysiloxane, also called silicone, and are fastened to the monopolar plate 13 associated with the bipolar plate before forming the stack 11. For example, a silicone paste is applied to the monopolar plate 13, the silicone forming the spacers 32 after hardening. In particular, the spacers 32 are advantageously made by overmolding onto the monopolar plate 13. Thereby, each spacer 32 is advantageously fastened directly by overmolding to the corresponding mating zone 24B. Alternatively, the spacers are pre-manufactured, for example by molding and / or machining, so that the spacers are bonded or nested to the monopolar plate 13, thereby forming the interrupt means 30.

[0071] When the cells 14 are stacked in the operating state of the battery 10, the interrupting means 30 bear against the two opposing bipolar plates 12 or bear at a very short distance from each of the two opposing bipolar plates 12, so that each interrupting means 30 is interposed between the connection zone 24A of one of the two bipolar plates 12 and the mating zone 24B located oppositely and belonging to the other two bipolar plates 12. In the case of spacers 32 made of elastic material, in particular when inserting a pin 22 or 25 into the pocket 20, the interrupting means 30 arranged on both sides of the connection zone 24A associated with the pocket 20 can be made to deform elastically to accommodate the passage of the pin into the pocket 20, while resisting by elastic return the movement away of the polar plate 13 associated with the pocket 20 by bearing against the adjacent bipolar plate 12, more particularly by bearing against the mating facing zone 24B.

[0072] The spacing L12 is defined as the distance between two adjacent bipolar plates 12, measured between the median planes P12 of two successive bipolar plates 12 parallel to the stacking axis A11. The spacing L12 corresponds to the pitch of the fuel cell 10, or in other words the average thickness of the cells 14. The spacing L12 is, for example, comprised between 0.8 mm and 1.5 mm.

[0073] According to an example, the interruption means 30 has a thickness that is less than the spacing L12 separating two opposing bipolar plates 12 in the operating state of the ordered stack, measured parallel to the stacking direction A11, in order to accommodate the passage of the pins into the pockets 20 while limiting the separation, in particular to take into account the geometric tolerances of the manufacture and assembly of the cell, despite some separation of the polar plates 13 associated with the pockets 20.

[0074] In particular, the interrupting means 30 keeps two adjacent bipolar plates 12 at a distance, in particular keeping each connection zone 24A at a distance from the oppositely located mating zone 24B. The interrupting means 30 prevents direct contact between two adjacent bipolar plates 12, more particularly preventing direct contact between each connection zone 24A and the oppositely located mating zone 24B.

[0075] Advantageously, in the operating state of the stack 11, the interrupt means 30 are dimensioned in terms of thickness along the stacking direction A11, so as to leave an overall dimensional clearance along the stacking direction A11 between the interrupt means 30 and two adjacent bipolar plates 12. The dimensional clearance is preferably less than 100 microns, more preferentially less than 50 microns. The dimensional clearance between the interrupt means and the adjacent bipolar plates 12 is not shown in the figures. Due to the dimensional clearance it is possible to tolerate variations in the dimensions of the interrupt means 30 and of the bipolar plates 12, without the risk of the interrupt means being too thick for the space available between the connection zone 24A and the mating zone 24B, resulting in local deformation of the bipolar plates 12.

[0076] With reference to FIG. 5, the stack 11 is shown in section for each pocket 20 of a given connection zone 24A, the peripheral wall 26 advantageously comprising a diverging periphery 27A that defines the open end 28 of the pocket 20. The diverging periphery 27A corresponds to the edge of the monopolar plate 13A / 13B and here extends parallel to the transverse axis T. The periphery 27A diverges with respect to the median plane P12 when moving away from the bottom 29 of the pocket 20. Each diverging periphery 27A is part of the outer edge of the bipolar plate 12 to which the connection zone 24A belongs. The diverging periphery 27A facilitates the insertion of the pin 22 / 25 that corresponds to the pocket 20 in question.

[0077] For each pocket 20, an overall dimension L20 is defined as the maximum distance measured parallel to the stacking axis A11 between the two flared perimeter edges 27A of the pocket 20. The overall dimension L20 and the spacing L12 are shown in Figure 5. Head-to-tail mounting of the bipolar plate 12 makes it possible to provide pockets 20 with an overall dimension L20 greater than the spacing L12, which facilitates the insertion of thicker and therefore stiffer pins 22.

[0078] Each mating zone 24B extends towards the adjacent diverging periphery 27A and preferably comprises a mating edge 27B that extends parallel to the adjacent diverging periphery 27A belonging to the connecting zone 24A facing the mating zone 24B. Each mating edge 27B is part of the outer edge of the bipolar plate 12 to which the mating zone 24B belongs. Each mating edge 27B here extends parallel to the transverse direction T.

[0079] 5-8, the flared peripheral edge 27A and the mating edge 27B are aligned with each other along the stacking direction A11. In other words, the flared peripheral edge 27A and the mating edge 27B are geometrically supported by the opening plane P28.

[0080] It should be appreciated that the interruption means 30 serves to maintain each flared peripheral edge 27A at a distance from the adjacent mating edge 27B, which reduces the risk of shorting between two adjacent bipolar plates 12.

[0081] As shown in Figure 5, for each cell 14, the membrane electrode assembly 200 is advantageously sandwiched between the two bipolar plates 12 associated with the cell 14 by means of interrupt means 30. In the example shown in Figure 5, a holding frame 206 is sandwiched between the two bipolar plates 12 by means of interrupt means 30.

[0082] Generally, including for the embodiments described hereafter, one or more of the spacers 32 may be formed by a part of the seals of the cells 14. Similarly, one or more of the spacers 32 may be made from the same material as at least one of the seals of the cells, although it may be different from the seals. Thus, in the two cases, the spacers 32 are preferably made during the same operation as the formation of the seals, for example during the same casting, molding or overmolding operation as the seals in question, regardless of whether the seals are fixedly attached to one of the monopolar plates 13 or to the MEA 200, or whether the seals in question are free seals.

[0083] A stack 211 according to an alternative embodiment of the present invention is shown in FIG.

[0084] In alternative embodiments of the present invention, elements similar to elements of other embodiments have the same reference numerals and function in the same manner, and the differences between each embodiment and the previous embodiment are explained hereinafter.

[0085] In comparison with the stack 11 of the previous embodiment, in which the bipolar plates 12 are formed by two monopolar plates 13 welded or joined together in a sealed manner, the case of the stack 211 shown in Fig. 6 is an example in which each bipolar plate 12 is formed from two monopolar plates 13 assembled by simple compression against each other for assembly with the interposition of a mounted seal 230 placed between the two monopolar plates 13. The directly mounted seal 230 is shown diagrammatically and in a non-limiting manner by a dotted rectangle.

[0086] 6, for each bipolar plate 12, the interrupting means 30 comprise three spacers 32, for example made from an elastomeric material, in particular from silicone, two of which are arranged on either side of the mating zone 24B of the bipolar plate 12, on the anode face of the bipolar plate 12 and on the cathode face of the bipolar plate 12, respectively, while the third spacer 32 is arranged between the two cathode and anode plates 13A and 13B forming the bipolar plate 12, and preferably also in the mating zone of the bipolar plate 12. Preferably, the three spacers 32 are aligned along the stack axis A11 so as to counter compressive forces parallel to the stack axis A11.

[0087] A stack 311 according to a second embodiment of the invention is shown in Fig. 7. In contrast to the previous embodiment, in the case of the stack 311 shown in Fig. 7, the monopolar plates 13A and 13B of each bipolar plate 12 are provided with a ridge 332 that extends at a distance from the median plane P12 associated with the bipolar plate 12, the ridge 332 being provided in the mating zone 24B and bearing against a pocket 20 of the opposite connecting zone 24A. The ridge 332 forms a relief on the corresponding face of the bipolar plate 12. The ridge 332 thereby forms the interruption means 30. For each bipolar plate 12, the associated monopolar plates 13A and 13B are here welded together. As previously described, the dimension of the ridge 332 along the stacking direction A11 preferentially provides a dimensional clearance that allows for the manufacturing and assembly tolerances of the cells 14 to be accommodated.

[0088] The ridges 332 are advantageously formed together with the formation of the passages 17, more particularly by stamping. The ridges 332 are provided in one piece with each of the monopolar plates 13A / 13B. In turn, the interrupt means 30 are here formed in one piece with the bipolar plate 12, which is economical and quick to manufacture.

[0089] A stack 411 according to a second embodiment of the invention is shown in Fig. 8. With respect to the previous embodiment, and more particularly with respect to the stack 11 shown in Fig. 5, in the case of the stack 411 shown in Fig. 8, the spacers 32 of the interruption means 30 associated with each bipolar plate 12, which are respectively arranged on the anode face of the bipolar plate 12 and on the cathode face of the bipolar plate 12, are connected to each other by a bridge of material 434. The interruption means 30 are mounted on the edge of the bipolar plate 12 under consideration, more precisely on the mating edge 27B of the bipolar plate 12 under consideration, so that the spacers 32 are positioned on both sides of the mating zone 24B, i.e. on each face of the bipolar plate 12.

[0090] In the illustrated example, the bridge of material 434 is a flexible wall that connects the spacers 32 together. Preferably, the bridge of material 434 is formed by a continuous wall and covers the entire mating edge 27B facing the connection zone 24A so as to electrically insulate the mating edge 27B from the opposite flared periphery or from the flared periphery 27A.

[0091] Preferably, the bridge of material 434 is pre-formed to slightly pinch the mating edge 27B of the bipolar plate 12 and to hold the interrupt means 30 in place at the mating zone 24B during assembly of the stack 411. Advantageously, the interrupt means 30 is bonded to the bipolar plate 12.

[0092] In a variant (not shown), the mating zone 24B has an opening, such as a drilled hole, while the interrupt member 30 has a protrusion shaped to match the opening, such as a stud that matches the drilled hole, the opening and the matching protrusion cooperating with each other by their matching shapes to facilitate positioning of the interrupt member 30 when the interrupt member 30 is mounted in the corresponding mating zone 24B.

[0093] A stack 511 according to a second embodiment of the invention is shown in figure 9. With respect to the previous embodiment, and more particularly with respect to the stack 11 shown in figure 5, in the case of the stack 511 shown in figure 9 the spacers 32 are fastened to the membrane electrode assemblies 200 instead of to the monopolar plates 13A / 13B. In the example shown, the spacers 32 are fastened to the holding frame 206 of the MEA 200. Once the stack 511 is formed, the spacers 32 are positioned between the respective connection zones 24A and the mating zones 24B facing each other, forming the interrupt means 30.

[0094] In the illustrated example, each spacer 32 is positioned on one side of the membrane electrode assembly 200, preferably the side oriented towards the mating zone 24B, and serves to reduce the deviation of the peripheral portion 202 of the MEA 200 relative to the mid-plane P200 along the stacking direction A11, reducing the risk of tearing the membrane electrode assembly 200. Preferably, each spacer 32 bears against a flat portion of the mating zone 24B. As previously described, the dimension of the spacers 32 along the stacking direction A11 advantageously provides a dimensional clearance to accommodate accepted cell manufacturing and assembly tolerances.

[0095] A stack 611 according to a second embodiment of the present invention is shown in Fig. 10. With respect to the previous embodiment, specifically with respect to the stack 511 shown in Fig. 9 in particular, in the case of the stack 611 shown in Fig. 10, each spacer 32 comprises two half spacers 33, which are correspondingly fastened to each other along the stacking direction A11 on both sides of the membrane electrode assembly 200, which provides a better distribution of forces in the membrane electrode assembly 200 and reduces the risk of tearing the membrane electrode assembly 200.

[0096] 11a), for each bipolar plate 12, the mating zone 24B is symmetrically positioned opposite the connecting zone 24A with respect to the center C12 of the bipolar plate 12. The connecting zone 24A and the mating zone 24B each have a contour in projection onto the median plane P12.

[0097] The contour of the connection band 24A thus includes a flared periphery 27A, seen here from above, which forms an outer portion 33A of the contour of the connection band 24A. In the illustrated example, the connection band 24A extends near one of the openings 101 of the bipolar plate 12, here one of the openings 101 located at one end of two rows of three openings 101, and the connection band 24A forms an inner portion 34A of the contour of the connection band 24A.

[0098] Similarly, the contour of mating zone 24B includes mating edge 27B, seen here from above, forming an outer portion 33B of the contour of mating zone 24B. Mating zone 24B extends near one of the openings 101 of the other row of three openings 101, forming an inner portion 34B of the contour of mating zone 24B.

[0099] Preferably, the internal contour of the connection zone 24A is symmetrical to the internal contour of the mating zone 24B about the center C12, such that when the two bipolar plates are stacked head-to-tail, the internal contour of the connection zone 24A of the first of the two bipolar plates 12 is superimposed on the internal contour of the mating zone 24B of the other bipolar plate 12.

[0100] Preferably, the outer contour of the connection zone 24A is symmetrical to the outer contour of the mating zone 24B about the center C12, so that the monopolar plates 13A and 13B are easy to manufacture.

[0101] In the example shown in FIG. 11b), the connection band 24A and the mating band 24B are arranged differently with respect to the bipolar plate 12 of FIG. 11a), with the connection band 24A and the mating band 24B extending near the opening 101 in the middle of a corresponding row of three openings 101.

[0102] An advantageous variant of the bipolar plate 12 is shown in FIG. 12. According to said variant, the outer edge of each mating zone 24B is set back from the opening plane P28. In the illustrated example, the mating zone 24B has a notch 34 such that the outer contour 33B of the mating zone 24B is set back from the outer contour 33A of the connecting zone 24A. The shape of the notch 34 is not limiting. In the illustrated example, each mating edge 27B is parallel to the opening plane P28 and at a distance from the opening plane P28. For each mating edge 27B, a distance D28 is defined as the minimum distance between the mating edge 27B and the opposite opening plane P28, parallel to the median plane P12. By extension, distance D28 is also the distance between each mating zone 24B and aperture plane P28, or stated another way, the distance between each mating zone 24B and flared periphery 27A.

[0103] 12, the outer contour 33B is straight, so the distance D28 is simply the distance between the mating edge 27B and the opening plane P28. In the previous embodiment, the distance D28 is zero or substantially zero.

[0104] The setback can be used to increase the flaring of the flared periphery 27A along the stacking direction A11, which facilitates insertion of the pins 22 / 25 while maintaining a minimum distance between each flared periphery 27A and its associated mating edge 27B, particularly during connection of the module 18, reducing the risk of short circuits.

[0105] Thereby, each mating edge 27B is set back from the opening plane 28, a distance D28 being 1 mm or more, other preferably 2 mm or more, while preferably less than 5 mm.

[0106] Another aspect of the invention will now be described with reference to Figures 13 to 15. More specifically, attention is paid to the seals inside each cell 14 between the monopolar plate 13 and the membrane electrode assembly 200. The stack 11 is partially shown in Figure 13, where the monopolar plate 13, here the cathode plate 13A, and the membrane electrode assembly 200 are visible.

[0107] The cathode plate 13A and the membrane electrode assembly 200 form part of the cell 14, which also comprises a peripheral seal 300, also called the first seal, which is interposed between the cathode polar plate 13A and the MEA 200 along the stacking direction A11. The peripheral seal 300 comprises a main part 301 and a fin 302. The peripheral seal 300 is preferentially made of an elastomeric material and is impermeable to the cathode fluid used in the fuel cell 10. More generally, the peripheral seal 300 is impermeable to each of the working fluids of the fuel cell 10.

[0108] 14b), for each anode plate 13B, the stack 11 comprises a peripheral seal 300' interposed between the anode plate 13B and the membrane electrode assembly 200 located opposite the anode plate 13B. The principles of the invention described with respect to the peripheral seal 300 associated with the cathode plate 13A can be transferred to the peripheral seal 300' associated with the anode plate 13B. The peripheral seal 300 associated with the cathode plate 13A is described hereinafter.

[0109] In the illustrated example, the first peripheral seal 300 is formed on the cathode polar plate 13A, for example by overmolding it thereon. Alternatively, the peripheral seal 300 is formed on the MEA 200 or is further formed separately from the cathode polar plate 13A of the MEA 200.

[0110] The main part 301 is a continuously extending bead of material, in this example forming a closed contour, or in other words a closed loop, extending along the peripheral zone 102 over the entire periphery of the plate 13A. The main part 301 surrounds the flow area 103, in which case the homogenization area 104 is provided and the openings 101 form the flow area 103. In the illustrated example, the main part 301 has a trapezoidal cross section, although such a shape is not limiting. The main part 301 extends along the flow area 103 and here comprises two longitudinal portions 301A and 301B extending parallel to the longitudinal direction L.

[0111] In the example shown, the main portion 301 of the peripheral seal 300 advantageously surrounds all openings 101 in the plate 13A. In a variant (not shown), other seals are provided around openings 101 that do not provide a flow area of ​​interest.

[0112] However, main portion 301 does not surround either connection zone 24A or mating zone 24B.

[0113] When the cathode plate 13A and the membrane electrode assembly 200 are assembled in the stack 11, the main part 301 extends in a closed loop along the peripheral part 202, here along the holding frame 206, through the periphery of the peripheral part 202. The main part 301 is interposed between the peripheral zone 102 and the peripheral part 202 along the stacking direction A11 so as to seal, over the entire periphery, a space defined along the stacking direction A11 between the peripheral zone 102 of the cathode plate 13A and the peripheral part 202 of the MEA 200. The main part 301 also surrounds the gas diffusion layer 205 and the face of the membrane 204 oriented towards the cathode plate 13A.

[0114] When the cathode plate 13A and the membrane electrode assembly 200 are assembled in the stack 11, the main part 301, the cathode polar plate 13A and the MEA 200 define a compartment 40 therebetween, here the cathode compartment. The main part 301 provides sealing of the cathode compartment 40 against the outside of the cell 14, specifically against an external zone 3 that is positioned beyond the main part 301 with respect to the cathode compartment 40. The connection zone 24A and the mating zone 24B are positioned outside the cathode compartment 40, while the pocket 20 remains accessible for connection to its module 18. Each cell 14 thus comprises two compartments 40 associated with each of the cathode plate 13A and the anode plate 13B, defining the cell 14.

[0115] The main part 301 of the first peripheral seal 300 comprises two opposed internal longitudinal surfaces 303 each disposed across either side of the flow field 103, each internal longitudinal surface 303 extending across a longitudinal portion 301A or 301B of the main part 301 and oriented towards the flow field 103. Each internal longitudinal surface 303 connects a peripheral zone 102 of the cathode polar plate 13A to a peripheral portion 202 of the MEA 200 in the stacking direction A11.

[0116] Each cathode compartment 40 includes two portions, referred to as "diversion zones 50", that extend between the peripheral seal 300 and the flow field 103 and join the openings 101 that define the flow field 103. More specifically, each diversion zone 50 extends between a respective longitudinal portion 301A or 301B and the flow field 103. Generally, each diversion zone 50 corresponds to a detour path around the flow field 103 that the reactive fluid follows between the two openings 101 that define the flow field 103.

[0117] Each bypass zone 50 is defined along the stacking direction A11 between the cathode polar plate 13A and the MEA 200, and along the transverse direction T between the flow field 103 and the gas diffusion layer 205 on the one hand and the main part 301 of the peripheral seal 300 on the other hand, for a portion of the main part 301 extending along the longitudinal direction L. Each bypass zone 50 extends along the longitudinal direction L, along the flow field 103, or even from one homogenization zone 104 to the other homogenization zone 104. The flow field 103 extends between the two bypass zones 50 along the transverse direction T.

[0118] The function of the fins 302 is to reduce or even prevent reactive fluid from being diverted along the longitudinal direction L in the diversion zone 50. To that end, each fin 302 at least partially blocks a cross-section of the diversion zone 50 that it occupies, the cross-section being taken perpendicular to the longitudinal direction L. The fins 302 are distributed along the main part 301 of the seal 300 in one, the other or both cathode diversion zones 50. Each fin 302 is attached to one of the inner surfaces 303 of the main part 301. In the illustrated example, a fin 302 projects from each of the longitudinal parts 301A and 301B of the main part 301. Each fin 302 extends from the inner surface 303 generally along the transverse direction T towards the flow field 103. Preferably, the fin 302 is formed in one piece with the main part 301.

[0119] Each fin 302 successively includes, starting from a main portion 301 , a joint portion 304 , a middle portion 305 and an end portion 306 .

[0120] Each fin 302, in the example shown, is advantageously in the form of a wall having an extension in a plane between its junction 304 and its end 306 in the median plane P12, which extension has a contour of a straight, intermittent or curved line, or a contour consisting of a combination of one or more straight lines, one or more dashed lines and / or one or more curved lines.

[0121] The fins 302 are joined to the main part 301 by means of joints 304 extending from the inner surface 303. In this example, the joints 304 are straight and their projection onto the median plane P12 is perpendicular to the longitudinal direction L, i.e. parallel to the transverse direction T. The joints 304 are interposed between the peripheral zone 102 of the polar plate 13 and the peripheral part 202 of the MEA 200 along the stacking direction A11.

[0122] The intermediate portion 305 of the fin 302 is attached to the joint 304 and extends the joint 304 along the direction of the region 103. In the present example, the intermediate portion 305 is straight and its projection onto the median plane P12 is oblique to the longitudinal direction L. The intermediate portion 305 is interposed between the peripheral zone 102 and the peripheral portion 202 along the stacking direction A11. In a variant, it may be provided that the intermediate portion 305 is parallel to the longitudinal direction L, i.e. parallel to the main portion 301. More generally, the intermediate portion 305 is inclined with respect to the transverse direction T, i.e. with respect to a direction perpendicular to the longitudinal portion 301A or 301B to which the corresponding fin 302 is attached.

[0123] The end 306 of the fin 302 is attached to the intermediate portion 305 and extends the intermediate portion 305 towards the region 103. The end 306 terminates the fin 302. In this example, the end 306 is straight and its projection onto the median plane P12 is perpendicular to the longitudinal direction L, i.e. parallel to the transverse direction T.

[0124] At least one portion of the end 306 of the fin 302, called contact portion 307, comprises the free end of the fin 302 and is interposed along the stacking direction A11 between the gas diffusion layer 205 and the peripheral zone 102. If appropriate, another portion of the end 306, through which the end 306 is attached to the intermediate portion 305, is interposed between the peripheral zone 102 and the peripheral portion 202.

[0125] In the illustrated example, the end portion 306 and the intermediate portion 305 form between them an angle that is advantageously comprised between 110° and 150°, here an angle of 120°. The intermediate portion 305 and the joint portion 304 form between them an angle that is advantageously comprised between 110° and 150°, here an angle of 120°.

[0126] As shown in FIG. 14b), the contact portion 307 of the fin 302 is elastically deformed between the gas diffusion layer 205 and the peripheral zone 102 in compression along the stacking direction A11. Due to the compression of the contact portion 307, the contact portion 307 has a thickness, measured along the stacking direction A11, which is less than the thickness of the remaining portions of the fin 302, in particular the thickness of the joint portion 304 and the middle portion 305. It can be provided that in the undeformed state of the fin 302, the portion 307 initially has the same thickness along the stacking direction A11 as the remaining portions of the fin 302. Such deformation under compression of the contact portion 307 can also deform the middle portion 305. As shown, the middle portion 305 accommodates the deformation of the end portion 306 by twisting slightly. The fact that the intermediate portion 305 is inclined with respect to the transverse direction T prevents mechanical stresses related to the flattening of the contact zone 307 between the layer 205 and the peripheral zone 102 from being applied to the main portion 301, which would otherwise adversely affect the sealing and / or the life span of the peripheral seal 300.

[0127] Under certain conditions of use of the fuel cell 10, in particular during cold start of the fuel cell 10, it may occur that water vapor condenses into liquid water in the compartment 40. When the fuel cell 10 is in use, for example in a vehicle, the stack 11 is laid out so as to be generally horizontal, i.e. when the vehicle is on a horizontal surface, the stacking direction A11 is substantially horizontal, while the transverse direction T of the stack is substantially vertical. Thus, the two longitudinal portions 301A and 301B are horizontal, and one of the longitudinal portions 301A / 301B of the peripheral seal 300 is positioned above the other longitudinal portion 301B / 301A of the peripheral seal 300. In the example shown in Fig. 13 and Fig. 15a, the longitudinal portion 301A of the peripheral seal 300 at the bottom of Fig. 13 is positioned below the other longitudinal portion 301B of the same peripheral seal 300. Therefore, the condensed water tends to accumulate on the same longitudinal portion 301A or 301B of the lower peripheral seal 300.

[0128] In the example shown in Fig. 13 and Fig. 15a), it is assumed that the cathode plate 13A is visible and the cathode fluid flows from one of the openings 101 located on the left of Fig. 13 to one of the openings 101 located on the right of Fig. 13. For example, the reactive fluid flows from the opening 101 located on the top left of the cathode plate 13A to the opening 101 located on the bottom right. Thereby, the reactive fluid flows along the bypass zone 50 generally along the same direction, here to the right along the longitudinal direction L. The circulation of the reactive fluid along the bypass zone 50 is depicted diagrammatically by two arrows 51A and 51B in Fig. 15a).

[0129] The fins 302 of the lower longitudinal portion 301A are advantageously oriented along the direction of flow of the reactive fluid flowing along the diversion zone 50 associated with the lower longitudinal portion 301A so as to facilitate the evacuation of condensate entrained by the reactive fluid. In other words, the fins 302 of the lower longitudinal portion 301A are inclined along the same direction relative to the transverse direction T as the direction of reactive fluid flow.

[0130] On the other hand, as mentioned above, two successive bipolar plates 12 of a stack 11 are stacked head-to-tail. With reference to Figures 13 and 15a, taking a first bipolar plate 12 along the same orientation as shown in said figures corresponds to then taking a second bipolar plate 12 rotated by 180° about the direction of stacking A11, i.e., the second bipolar plate 12 would obtain symmetry with respect to the centre C12. In other words, the longitudinal portion 301B shown at the top in Figures 13 and 15a) would be at the bottom, although such a configuration is not shown.

[0131] Advantageously, for each peripheral seal 300, the fins 302 attached to the opposite longitudinal portions 301A, 301B are inclined along opposite directions relative to the transverse direction T such that the fins 302 of the lower longitudinal portion 301A or 301B are inclined along the direction of reactive fluid flow even when the bipolar plate 12 is arranged head-to-tail, whereby the fins 302 attached to the upper longitudinal portion 301B are inclined relative to the transverse axis T along the opposite direction relative to the reactive fluid flow.

[0132] Two opposite faces of the same bipolar plate 12 are shown in illustrations a) and b) of Fig. 15, respectively, with the cathode plate 13A shown in illustration a) and the anode plate 13B shown in illustration b). In other words, between illustrations a) and b), the same bipolar plate 12 is inverted by a rotation of 180° about the transverse axis T, which is vertical in Fig. 15.

[0133] The principles of the invention defined with reference to the cathode plate 13A of Fig. 15a) are naturally also valid for the anode plate 13B of Fig. 15b), i.e. the fins 302 of the lower longitudinal section, here longitudinal section 301B, are inclined with respect to the transverse axis T along the same direction as the direction of flow of the reactive fluid associated with the anode plate 13B, whereby the fins 302 belonging to the same longitudinal section 301A or 301B are inclined along the same direction with respect to the transverse direction T.

[0134] It should be understood that the direction of inclination of the fins 302 belonging to the lower longitudinal portion 301A is selected according to the direction of the flow of reactive fluid along the corresponding diversion zone 50. In the illustrated example, the flow of reactive fluid is crossed on both sides of each bipolar plate 12, which means that when the polar plates 13A and 13B are seen from the front, the flow is presented in the same direction, as shown in Figures 15a) and 15b).

[0135] Advantageously, for the peripheral seal 300 of the anode plate 13B, the fins 302 belonging to opposite longitudinal portions 301A / 301B are inclined along opposite directions with respect to the transverse direction T.

[0136] A perimeter joint 300 with two alternative types of fins 302′ and 302″ is shown in FIGS. 16a and 16b), respectively. As before, it is assumed that the reactive fluids flow from left to right.

[0137] In Fig. 16a) for the previously described fins 302, the end portions 306 are aligned with the intermediate portions 305, i.e. the assembly formed by the joining of the intermediate portions 305 and the end portions 306 is inclined with respect to the transverse direction T. The fins 302' of the longitudinal portion 301A at the bottom are inclined along the direction of the flow of the reactive fluids, whereas the fins 302' attached to the longitudinal portion 301B at the top are inclined along the opposite direction of the flow of the reactive fluids.

[0138] In Fig. 16b) for the previously described fin 302, the joint portion 304 is aligned with the middle portion 305, i.e. the assembly formed by joining the middle portion 305 and the joint portion 304 is inclined with respect to the transverse direction T. The fin 302" of the longitudinal portion 301A at the bottom is inclined along the direction of the flow of the reactive fluid, while the fin 302" attached to the longitudinal portion 301B at the top is inclined along the opposite direction to the flow of the reactive fluid.

[0139] The above-described embodiments and variations can be combined with each other to create new embodiments of the present invention. [Explanation of symbols]

[0140] 3 External Bands 10 fuel cell 11 Stack 12 Bipolar Plates 13 Monopolar Plate 13A First polar plate, cathode plate 13B Second polar plate, anode plate 14 Cells 16 End Plate 17 Passage network, passage 18 Module for measuring electrical properties 20 Pocket 21 One end 22 pin 23 columns 24A connection bandwidth 24B Mating Band 25 additional pins 26 Perimeter Wall 26B Ridge part 27A flared edge 27B Fitting edge 28 Open End 29 bottom 30 Interruption means, interruption member 32 Spacer 33 Half spacer 33A Outer part of the flared edge 27A 33B Outer portion of the contour of the mating zone 24B 34 Cutout 34A Inner part of the contour of the connection band 24A 34B Inner portion of the contour of the mating zone 24B 40 Compartment 50 Detour Bandwidth 51A, 51B (reactive fluid circulation) arrows 101 Aperture 102 Surrounding Band 103 Flow area, flow chamber 104 Equalization area Aisle 105 200 Membrane electrode assembly, MEA 201 Aperture 202 Periphery 203 Center part 204 Membrane 205 Gas diffusion layer, GDL 206 Holding Frame 211 Stack 230 Sealing part 300, 300′ First sealing portion, peripheral sealing portion, peripheral bonding portion 301 Main part 301A, 301B Longitudinal section 302, 302′, 302″ fins 303 Inner Longitudinal Surface 304 Joint 305 Middle Section 306 End 307 Contact area, contact zone 311 Stack 332 Prominence 411 Stack 434 Bridge Materials 511 Stack 611 Stack A11 Stacking axis, stacking direction C12 center D20 Connection Direction D28 distance L Longitudinal L12 interval L20 Overall dimensions P12 Median plane P28 Opening plane P200 intermediate plane T transverse direction, transverse axis

Claims

1. A stack (11; 211; ...; 611) of fuel cells (10), a plurality of bipolar plates (12) identical to one another, each extending along a median plane (P12) and stacked along a stacking direction (A11) perpendicular to said median plane, whereby two successive bipolar plates (12) form between them a cell (14) of the stack; Each bipolar plate (12) is formed by two monopolar plates (13A, 13B) superimposed and forming together at least one pocket (20) at one end (21) of said bipolar plate (12), each pocket (20) having an end opening (28) configured to receive a pin (22) of a module (18) for measuring said fuel cell; Any two consecutive bipolar plates (12) are stacked head-to-tail, forming a stack (11; 211; ...; 611).

2. Each pocket (20) opens through said end opening (28) along a direction of connection (D20) that is parallel to the longitudinal direction (L) of the stack (11) and perpendicular to said stacking direction (A11); 2. A stack (11; 211; ...; 611) according to claim 1, wherein for any two consecutive bipolar plates (12), the direction (D20) of connection of the pockets (20) of each of one of the two bipolar plates is oriented opposite to the direction of connection of the pockets of each of the other bipolar plates.

3. Each bipolar plate (12) comprises a connection region (24A) in which the at least one pocket (20) of the bipolar plate is formed, and a mating region (24B) located opposite the connection region (24A) with respect to a center (C12) of the bipolar plate (12); for any two consecutive bipolar plates (12), the connection zone (24A) of one of said two bipolar plates is arranged opposite the mating zone (24B) of the other bipolar plate along said stacking direction (A11); 3. A stack (11; 211; ...; 611) according to claim 1 or 2, further comprising interruption means (30) interposed between each connection zone (24A) and the opposite mating zone (24B) so as to limit deformation of each pocket (20) of the connection zone when the pin (22) associated with said pocket is inserted into said pocket.

4. 4. A stack (311) as described in claim 3, wherein the mating zone (24B) has a protuberance (332) protruding from the monopolar plate (13A, 13B) and extending toward the opposite connection zone (24A) so as to limit deformation of each pocket (20) of the connection zone when the pin (22) associated with the pocket is inserted into the pocket to form the interruption means (30).

5. The interrupting means (30) comprises a spacer (32) interposed between each connecting zone (24A) and the opposite mating zone (24B); Each spacer (32) is fastened to said mating zone (24B); Stack (11; 211; 411; 611) according to claim 3.

6. Each bipolar plate (12) has an outer anode surface and an outer cathode surface; 6. The stack (11; 211) of claim 5, wherein for a given bipolar plate (12), the mating zone (24B) of the bipolar plate comprises a spacer (32) fastened to the outer anode face of the bipolar plate (12) and a spacer (32) fastened to the outer cathode face of the bipolar plate (12).

7. Each bipolar plate (12) has an outer anode surface and an outer cathode surface; 7. A stack (211) according to claim 5 or 6, wherein for a given bipolar plate (12), the interruption means (30) comprises three spacers (32), two of which are arranged on either side of the mating zone (24B) of the bipolar plate (12), on the outer anode face of the bipolar plate (12) and on the outer cathode face of the bipolar plate (12), respectively, while a third spacer (32) is arranged between the two monopolar plates (13A, 13B) forming the bipolar plate (12).

8. The interrupting means (30) comprises a spacer (32) interposed between each connecting zone (24A) and the opposite mating zone (24B); for each bipolar plate (12), the interrupt means (30) associated with said plate comprises a bridge (434) of material connecting said spacers (32); 8. A stack (411) according to any one of claims 5 to 7, wherein the interrupting means are mounted on the edges (27B) of the associated bipolar plates (12) such that the spacers (32) are positioned on either side of the mating zone (24B).

9. The interrupting means (30) comprises a spacer (32) interposed between each connecting zone (24A) and the opposite mating zone (24B); The stack further comprises membrane electrode assemblies (200) each received between two successive bipolar plates (12) and extending between the connection zones (24A) associated with the two bipolar plates and the opposing mating zones (24B), 4. The stack (511; 611) of claim 3, wherein some of the spacers (32) are fastened to the membrane electrode assemblies (200).

10. Stack (11; 211) according to any one of claims 5 to 9, wherein the spacers (32) are made from an elastomeric material.

11. Each bipolar plate (12) comprises a connection region (24A) in which the at least one pocket (20) of the bipolar plate is formed, and a mating region (24B) located opposite the connection region (24A) with respect to a center (C12) of the bipolar plate (12); for any two consecutive bipolar plates (12), the connection zone (24A) of one of said two bipolar plates is located opposite the mating zone (24B) of the other bipolar plate along the stacking direction (A11); The connecting band (24A) is divided into two rows (23), the two rows extending along the stacking direction (A11), 11. A stack (11) according to any one of claims 1 to 10, wherein for each row, the end openings (28) of the pockets (20) of said row are geometrically supported by an opening plane (P28) that is parallel to the stacking axis (A11), while the mating zones (24B) associated with the connection zones (24A) of said row are set back from the opening plane (P28) at a distance (D28) from the opening plane (P28) that is comprised between 1 mm and 5 mm, preferably greater than or equal to 2 mm.

12. For at least one cell (14) of the stack, said cell comprises: A first polar plate (13A), A peripheral band (102), and A reactive fluid flow region (103) surrounded by a peripheral region (102). A first polar plate (13A) comprising: A membrane electrode assembly (200) that is stacked on the first polar plate (13A) according to a stacking direction (A11), a peripheral portion (202; 402) facing said peripheral zone (102) along said stacking direction (A11), a central portion (203) comprising a proton exchange polymer membrane (204) and surrounded by said peripheral portion (202; 402); At least one gas diffusion layer (205) interposed between the proton exchange polymer membrane (204) and the flow field (103) of the first polar plate (13A) along the stacking direction (A11). A membrane electrode assembly (200) comprising: A first peripheral seal (300), a main part (301) interposed along the stacking direction (A11) between the peripheral zone (102) and the peripheral part (202) of the membrane electrode assembly (200), which surrounds the flow field (103) and the gas diffusion layer (205) associated with said flow field and provides a seal against reactive fluids between, on the one hand, a compartment (40) of the cell (14) defined between the peripheral part (202; 402) of the membrane electrode assembly (200) and the peripheral zone (102), inside the cell (14), and, on the other hand, a zone outside the cell beyond the main part (301) facing the compartment (40); A fin (302) extending from the main portion into said compartment. A first peripheral seal (300) comprising: Equipped with said main part (301) comprises two longitudinal portions (301A, 301B) each extending parallel to a longitudinal direction (L) perpendicular to said stacking direction (A11) and extending along said flow field (103) and arranged on either side of said flow field, said compartment (40) comprising two bypass zones (50) each defined between a respective longitudinal portion on the one hand and said flow field (103) and said gas diffusion layer (205) associated with said flow field on the other hand, for each longitudinal portion, at least one fin (302; 302'; 302") extends from said longitudinal portion into a corresponding bypass region (50); Each fin is a joint (304) through which the fin is attached to the corresponding longitudinal portion (301A, 301B); an edge (306) interposed between the gas diffusion layer (205) and the peripheral zone (102) along the stacking direction (A11); an intermediate portion (305) connecting the joint portion (304) to the end portion (306), the intermediate portion (305) being inclined in projection onto the median plane (P12) with respect to a transverse direction (T) perpendicular to the stacking direction (A11) and the longitudinal direction (L); Equipped with for each longitudinal portion, the fins attached to the longitudinal portion are inclined along the same direction relative to the transverse direction; 12. A stack (11) according to any one of claims 1 to 11, wherein when the stack is in an operational configuration, the fins attached to the longitudinal portion located at the bottom are inclined in the same direction as the flow of reactive fluid associated with the first polar plate (13A).

13. Stack (11) according to claim 12, wherein for each peripheral seal, the fins (302; 320'; 302'') attached to opposite longitudinal portions (301A, 301B) are inclined along opposite directions with respect to the transverse direction (T).

14. A stack (11) according to any one of claims 1 to 13, two end plates (16) on either side of the stack (11); a plurality of measurement modules (18) each configured to measure an electrical characteristic of the cell (14), each module (18) having a pin (22) each connected to a respective pocket (20); A fuel cell (10).

15. A vehicle comprising at least one fuel cell (10) according to claim 14.

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