Cell for a fuel cell and fuel cell comprising such a cell

Abstract

The invention relates to a cell (2) for a fuel cell (1) comprising a first polar plate (100), the first polar plate comprising a peripheral region (102), a membrane electrode assembly (200) superimposed on the first polar plate and comprising a peripheral portion (202), and at least one gas diffusion layer (205) interposed between a polymer proton exchange membrane (204) and the first polar plate, and a first peripheral seal (300) providing a seal for the reactant fluid between, on the one hand, a bypass region (50) of the cell and, on the other hand, a region (3) outside the cell, the seal comprising a main portion (301) and at least one fin (302) extending into the bypass region, characterised in that the fin further comprises an end portion (306) interposed between the gas diffusion layer and the peripheral region, and an intermediate portion (305) which is oblique with respect to the main portion.

Description

[0001] DESCRIPTION

[0002] TITLE: Cell for fuel cell and fuel cell comprising such a cell

[0003] The present invention relates to a cell for a fuel cell and a fuel cell comprising such a cell.

[0004] US8003273B2 describes a fuel cell, and at least one sealing member for such a cell. The cell comprises a membrane-electrode assembly comprising a gas diffusion layer, two separator plates on either side of the membrane-electrode assembly, each plate comprising a circulation zone with gas circulation channels. Each sealing member extends from an inner surface of an annular seal and extends between a separator plate and an electrolytic membrane, is in contact with a surface of the membrane-electrode assembly, and is in particular in contact with the gas diffusion layer, thus limiting the circulation of gas in a bypass zone. The bypass zone is often referred to by the Anglicism "bypass zone". It may be desirable to limit the circulation of gas in the bypass zone because the gas then bypasses the circulation zone without reacting, which reduces the efficiency of the cell.

[0005] In this known cell, the gasket is interposed between a peripheral zone of the separator plate and the membrane electrode assembly. The peripheral zone is at the same height as the circulation zone, while the gas circulation channel is a groove formed in the separator plate. However, it may be more advantageous to provide a separator plate made of stamped sheet metal, which may imply that the bypass zone extends partly under the gas diffusion layer. In this case, the gasket of the known cell may not block the gas circulation in the bypass zone sufficiently effectively.

[0006] The aim of the present invention is to remedy the drawbacks explained above, by proposing a peripheral seal which more effectively blocks the circulation of gas.

[0007] For this purpose, the invention relates to a peripheral seal for a cell for a fuel cell, the peripheral seal comprising:

[0008] • a main part, being configured to be interposed, in a stacking direction of the fuel cell, between: ♦ a peripheral zone belonging to a polar plate of the cell, the polar plate extending parallel to a main plane of the cell, the main plane being perpendicular to the stacking direction, the polar plate comprising a circulation field of a reactive fluid, surrounded by the peripheral zone, and

[0009] ♦ a peripheral portion belonging to a membrane-electrode assembly, the membrane-electrode assembly further comprising at least one gas diffusion layer,

[0010] • at least one fin comprising a joining part, by means of which the fin is attached to the main part.

[0011] According to the invention, said at least one fin further comprises:

[0012] • an end portion terminating the fin, configured to be interposed, according to the stacking direction, between the gas diffusion layer and the peripheral zone, and

[0013] • an intermediate part, connecting the junction part to the end part, the intermediate part being configured to be oblique relative to the main part of the peripheral joint, in projection in the main plane.

[0014] An idea underlying the invention is to block the circulation of the reactive fluid between the gas diffusion layer and the peripheral zone of the polar plate by interposing the fin, here the end portion of the fin between the gas diffusion layer and the peripheral zone. Thus, the fin can block the circulation of reactive fluid even when it circulates partly under the gas diffusion layer, making it possible to increase the proportion of reactive fluid in the circulation field, and therefore to improve the efficiency of the cell. In addition, the intermediate portion of the fin being oblique relative to the main portion, this makes it possible to reduce the risk of transverse deformation of the main portion of the first peripheral seal under a traction effect by the fin, despite the fact that the end portion of the fin is interposed, possibly being compressed, between the gas diffusion layer and the peripheral zone of the polar plate.In particular, a primary tensile force generated by the compression of the end portion by the gas diffusion layer is converted at the intermediate portion into a torsional and / or bending force, which deforms the intermediate portion. The main portion is thus subjected to a resulting force much lower than the primary tensile force, the resulting force not being sufficient to deform the main portion or only slightly deforming the main portion. The sealing of the first peripheral seal with respect to the outside of the stack is then ensured, allowing the cell to operate correctly.

[0015] The peripheral seal may include the following features, taken individually or in any technically possible combination:

[0016] The peripheral seal comprises several fins, each fin being connected to the main part only via the joining part.

[0017] The joining portion is configured to extend perpendicular to the main portion, projecting into the main plane.

[0018] The end part is configured to extend perpendicular to the main part, in projection in the main plane.

[0019] - At least one part, among the end part, the intermediate part and the junction part, is configured to be rectilinear, in projection in the principal plane.

[0020] A portion of the fin is configured to be curved, projecting into the principal plane.

[0021] The joining part has an opening allowing fluid to flow through the fin.

[0022] The main part of the peripheral seal and the fin are formed from a single piece.

[0023] The peripheral seal further comprises a dam which is parallel to the main portion, which connects the end portions of several fins, the dam being formed integrally with the first peripheral seal, and which is configured to be interposed according to the stacking direction between the gas diffusion layer and the polar plate.

[0024] The present invention also relates to a cell, for a fuel cell, comprising a polar plate and a peripheral seal, the polar plate comprising:

[0025] • the peripheral zone, and

[0026] • the circulation field of the reactive fluid, surrounded by the peripheral zone.

[0027] The cell may include the following characteristics, taken individually or in any technically possible combination:

[0028] The cell further comprises: • the membrane-electrode assembly, extending parallel to the main plane of the cell, superimposed on the first polar plate in the stacking direction, and comprising:

[0029] ♦ the peripheral portion, opposite the peripheral zone following the stacking direction,

[0030] ♦ a central portion comprising a proton exchange polymer membrane, framed by the peripheral portion, and

[0031] ♦ said at least one gas diffusion layer interposed, in the stacking direction, between the proton exchange polymer membrane and the polar plate, the peripheral seal ensuring a seal against the reactive fluid between, on the one hand, a bypass zone of the cell delimited inside the cell, between the peripheral portion of the membrane-electrode assembly and the peripheral zone, and on the other hand, a zone external to the cell beyond the main part with respect to the bypass zone, and said at least one fin extending into the bypass zone.

[0032] A contact portion of the end part is compressed between the gas diffusion layer and the peripheral zone

[0033] The circulation field delimits a plurality of channels, for the circulation of the reactive fluid, the channels extending in a longitudinal direction perpendicular to the stacking direction, each channel being delimited by:

[0034] • a canal bottom, belonging to the circulation field, and extending parallel to the longitudinal direction, and

[0035] • two channel teeth, belonging to the circulation field, and extending parallel to the longitudinal direction, the channel teeth being arranged on either side of the channel bottom, projecting relative to the channel bottom, each channel tooth being in contact with the gas diffusion layer in the stacking direction.

[0036] The canal teeth are further protruded from the peripheral area in the stacking direction.

[0037] The present invention also relates to a fuel cell comprising cells, at least one of said cells being as described above, the cells being stacked in the stacking direction to constitute a stack.

[0038] The present invention also aims to remedy the drawbacks of the prior art mentioned above by proposing a new cell for a fuel cell, which, while having a bypass zone which extends under the gas diffusion layer, has an improved efficiency without prejudice to the sealing of the cell with respect to the exterior.

[0039] For this purpose, the present invention also relates to a cell, for a fuel cell, the cell comprising a first polar plate extending parallel to a main plane of the cell, the main plane being perpendicular to a stacking direction of the fuel cell, the first polar plate comprising a peripheral zone and a circulation field of a reactive fluid, surrounded by the peripheral zone.The cell further comprises a membrane-electrode assembly, extending parallel to the main plane of the cell, superimposed on the first polar plate in the stacking direction, and comprising a peripheral portion, opposite the peripheral zone in the stacking direction, a central portion comprising a proton exchange polymer membrane, framed by the peripheral portion and at least one gas diffusion layer interposed, in the stacking direction, between the proton exchange polymer membrane and the first polar plate.The cell also comprises a first peripheral seal, comprising a main part interposed, in the stacking direction, between the peripheral zone and the peripheral portion of the membrane-electrode assembly, the first peripheral seal ensuring a seal to the reactive fluid between on the one hand a bypass zone of the cell delimited inside the cell, between the peripheral portion of the membrane-electrode assembly and the peripheral zone, and on the other hand a zone external to the cell beyond the main part with respect to the bypass zone and at least one fin extending into the bypass zone, comprising a junction part, by means of which the fin is attached to the main part.The fin further comprises an end portion, interposed, in the stacking direction, between the gas diffusion layer and the peripheral zone, and an intermediate portion, connecting the junction portion to the end portion, the intermediate portion being oblique relative to the main portion of the first peripheral joint, in projection in the main plane.

[0040] An idea underlying this cell is to block the circulation of the reactive fluid between the gas diffusion layer and the peripheral zone of the polar plate by interposing the fin between the gas diffusion layer and the peripheral zone. Thus, the fin can block the circulation of reactive fluid even when the bypass zone extends partly under the gas diffusion layer, making it possible to increase the proportion of reactive fluid in the circulation field, and therefore to improve the efficiency of the cell. In addition, the intermediate part of the fin being oblique with respect to the main part, this makes it possible to reduce the risk of transverse deformation of the main part of the first peripheral seal under a traction effect by the fin, despite the fact that the extreme part of the fin is interposed, possibly being compressed, between the gas diffusion layer and the peripheral zone of the polar plate.In particular, a primary tensile force generated by the compression of the end portion by the gas diffusion layer is converted at the oblique portion into a torsional and / or bending force, which deforms the oblique portion. The main portion is thus subjected to a resulting force much lower than the primary tensile force, the resulting force not being sufficient to deform the main portion or only slightly deforming the main portion. The sealing of the first peripheral seal with respect to the outside of the stack is then ensured, allowing the cell to operate correctly.

[0041] The cell of the present disclosure may comprise the following features, taken individually or in any technically possible combination:

[0042] - The joining part extends perpendicular to the main part of the first peripheral joint, in projection in the main plane.

[0043] - The extreme part extends perpendicular to the main part of the first peripheral joint, in projection in the main plane.

[0044] - At least one part, among the extreme part, the intermediate part and the junction part, is rectilinear, in projection in the principal plane.

[0045] - Part of the fin is curved, projecting into the main plane.

[0046] - A contact portion of the end part is compressed between the gas diffusion layer and the peripheral zone.

[0047] - The junction part has an opening allowing fluid to circulate through the fin.

[0048] - The cell further comprises a dam which is parallel to the main part, which connects the end parts of several fins, and which is interposed, according to the stacking direction, between the gas diffusion layer and the first polar plate, the dam being formed in one piece with the first peripheral seal.

[0049] - The main part of the first peripheral seal and the fin are formed from a single piece.

[0050] - The circulation field delimits a plurality of channels, for the circulation of the reactive fluid, the channels extending in a longitudinal direction perpendicular to the stacking direction, each channel being delimited by a channel bottom, belonging to the circulation field, and extending parallel to the longitudinal direction, and by two channel teeth, belonging to the circulation field, and extending parallel to the longitudinal direction, the channel teeth being arranged on either side of the channel bottom, projecting relative to the channel bottom, each channel tooth being in contact with the gas diffusion layer in the stacking direction.

[0051] - The canal teeth are further protruded from the peripheral area in the stacking direction.

[0052] - The membrane-electrode assembly comprises a holding frame forming the peripheral portion and framing the central portion.

[0053] - The cell further comprises a second polar plate, beyond the membrane-electrode assembly opposite the first polar plate in the stacking direction, and a second peripheral seal, interposed between the second polar plate and the membrane-electrode assembly along the stacking direction.

[0054] The present disclosure also relates to a fuel cell comprising cells, at least one of said cells being as described above, the cells being stacked in the stacking direction to constitute a stack.

[0055] The invention will be better understood by reading the following description, given solely by way of example and with reference to the drawings in which:

[0056] [Fig 1] Figure 1 is an exploded view of a portion of a cell of a fuel cell, according to a first embodiment of the invention.

[0057] [Fig 2] Figure 2 is a sectional view of a portion of a fuel cell stack, including the cell of Figure 1.

[0058] - [Fig 3] Figure 3 is another sectional view of part of the cell of Figure 1.

[0059] [Fig 4] Figure 4 is a top view of a portion of the cell of the preceding figures, showing the section line H-H' of Figure 2 and the section line III- 111' of Figure 3.

[0060] - [Fig 5] Figure 5 is a sectional view similar to that of Figure 2 where the stack is shown in a disassembled state.

[0061] [Fig 6] Figure 6 is a sectional view of a portion of a stack comprising a cell according to a second embodiment of the invention.

[0062] [Fig 7] Figure 7 is a top view of part of the cell of Figure 6, showing section line IV-IV' of Figure 6.

[0063] [Fig 8] Figure 8 is a top view of a portion of a cell according to a third embodiment of the invention.

[0064] [Fig 9] Figure 9 is a sectional view of a portion of a stack comprising a cell according to a fourth embodiment of the invention. - [Fig 10] Figure 10 is a top view of a portion of the cell of Figure 9, showing the section line V-V' of Figure 9.

[0065] [Fig 1 1] Figure 11 is a top view of a fifth embodiment of the invention.

[0066] [Fig 12] Figure 12 is a sectional view of a portion of a stack comprising a cell according to a sixth embodiment of the invention.

[0067] [Fig 13] Figure 13 is a top view of part of the cell of Figure 12, showing section line VI-VI' of Figure 12.

[0068] [Fig 14] Figure 14 is a sectional view of a portion of a stack comprising a cell according to a seventh embodiment of the invention.

[0069] [Fig 15] Figure 15 is a sectional representation of a portion of a cell according to an eighth embodiment of the invention.

[0070] [Fig 16] Figure 16 is a sectional representation of a portion of a cell according to a ninth embodiment of the invention.

[0071] - [Fig 17] Figure 17 is a top view of the ninth embodiment of the invention, showing the section line VIII-VIH' of Figure 16.

[0072] Figures 1 to 5 represent a first embodiment in accordance with the invention.

[0073] In Figure 1 are shown a first polar plate, called cathode polar plate 100, and a membrane electrode assembly 200 forming part of a cell 2 of a fuel cell 1. The cell 2 also comprises a second polar plate, called anode polar plate 100', shown in Figure 2.

[0074] The cathode polar plate 100 is perpendicular to a stacking direction X of the fuel cell 1, directed upwards, as in FIG. 2. The cathode polar plate 100 extends parallel to a main plane P of the cell 2, perpendicular to the stacking direction X. A longitudinal direction Y, directed towards the front of FIG. 2 and a transverse direction Z, directed from left to right in FIG. 2, extending in the main plane P, perpendicular to each other and perpendicular to the stacking direction X are also defined.

[0075] The cathode polar plate 100 may be formed by an electrically conductive material, for example metal such as stainless steel or graphite. The cathode polar plate 100 has a peripheral zone 102, openings 101, two homogenizing fields 104, and a circulation field 103.

[0076] The peripheral zone 102 extends around the entire circumference of the cathode polar plate 100, and borders the openings 101, the homogenization fields 104 and the circulation field 103. The openings 101, the homogenization fields 104 and the circulation field 103 are arranged inside the peripheral zone 102. The peripheral zone 102 extends in a plane perpendicular to the stacking direction X, parallel to the main plane P.

[0077] The circulation field 103 extends between the two homogenization fields 104 in the longitudinal direction Y. On one face of the cathode polar plate 100 facing the membrane electrode assembly 200, i.e. in the stacking direction X, the circulation field 103 comprises channels 105, formed in hollows, and extending substantially parallel to the longitudinal direction Y. The channels 105 may be delimited by grooves hollowed out in the cathode polar plate 100, or by stamping the cathode polar plate 100.

[0078] Each channel 105 is delimited in depth along the stacking direction X by a channel bottom 1051 formed by the cathode polar plate 100, extending along the longitudinal direction Y. The channel bottom 1051 may be substantially flat, as illustrated in the figures in a simplified manner, but most often has a slightly rounded profile in section by a transverse plane containing the transverse direction Z. In certain embodiments, such as that illustrated for example in FIGS. 2 and 3, the channel bottoms 1051 are, at least at their point of greatest depth of the channel along the stacking direction X, coplanar with the peripheral zone 102. Alternatively, the channel bottoms 1051 are set back relative to the peripheral zone 102 along the stacking direction X.

[0079] Each channel 105 is also delimited by two channel teeth 1052, formed by the cathode polar plate 100, projecting relative to the channel bottom 1051 in the stacking direction X. Preferably, the channel teeth 1052 also project relative to the peripheral zone 102 along the stacking direction X. The channel teeth 1052 are substantially planar and parallel to the channel bottom 1051. Alternatively, the channel teeth 1052 have a slightly rounded profile in section by a transverse plane containing the transverse direction Z and the stacking direction X. The channel teeth 1052 border the channel bottom 1051 along the length of the channel bottom 1051 along the longitudinal direction Y.

[0080] The channel bottom 1051 is continuously connected to each channel tooth 1052 by an inclined portion 1053 formed by the cathode polar plate 100. The channel 105 is therefore also delimited by two inclined portions 1053.

[0081] Each opening 101 is intended either for the injection of reactive or cooling fluid, or for the evacuation of reactive or cooling fluid, for each cell 2 of the fuel cell 1. The openings 101 here have a closed contour. Three openings 101 are located on one side of the cathode polar plate 100 in the longitudinal direction Y, aligned in the transverse direction Z. Three other openings 101 are located on the other side of the cathode polar plate 100 in the longitudinal direction Y, also aligned in the transverse direction Z. For each reactive or cooling fluid, and therefore for each fluid circulation field of the cell, an opening 101 forms a fluid supply for the circulation field concerned, and another opening 101, located on the other side of the cathode polar plate 100 in the longitudinal direction Y, serves for the evacuation of fluid for the circulation field concerned.

[0082] Each homogenization field 104 is arranged between the circulation field 103 and the openings 101 in the longitudinal direction Y. On the face of the cathode polar plate 100 facing the membrane electrode assembly 200, i.e. in the stacking direction X, each homogenization field 104 may comprise channels, which are for example arranged in a fan-shaped orientation. These channels connect one of the openings 101 to the circulation field 103. The channels of the homogenization fields 104 may, as in the illustrated examples, be similar and formed in the same way as those of the circulation field 103, except for their orientation. However, the channels of the homogenization fields 104 may have for example a width and / or a depth different from those of the circulation field 103.Likewise, the channels of the homogenization fields 104 can be produced differently from those of the circulation field 103, in particular with different technological processes. The channels of the homogenization fields 104 can for example be produced in the form of ribs applied by adding material, metallic, elastomer, or polymer, on a portion of cathode polar plate 100 which can be flat or not, while the channels 105 of the circulation field 103 can be produced by stamping, or vice versa.

[0083] For the cathode polar plate 100, the first homogenization field 104 makes it possible to distribute the reactive fluid coming from one of the openings 101 b so that it circulates throughout the entire circulation field 103, in the longitudinal direction Y. The second homogenization field 104 makes it possible to evacuate the reactive fluid distributed over the entire circulation field 103 to another opening 101 b, located opposite the cathode polar plate 100, where the reactive fluid is evacuated. Thus, on the face of the cathode polar plate 100 which is turned towards the membrane electrode assembly 200, only one of the reactive fluids circulates from one of the openings 101 to another of the openings 101 opposite in the longitudinal direction Y, via the circulation field 103. For the cathode polar plate 100, the reactive fluid is cathode reactive fluid, for example air or oxygen.It is provided that only the openings 101 b deliver and evacuate fluid on this face of the cathode polar plate 100, while the contour of the openings 101 a and 101 c is tightly closed, so that the fluids passing through the openings 101 a and 101 c are not brought into contact with the cathode reactive fluid on this face of the cathode polar plate 100.

[0084] The membrane electrode assembly (MEA) 200 faces the cathode pole plate 100 in the stacking direction X, and is parallel to the principal plane P. The MEA 200 comprises a peripheral portion 202, openings 201, and a central portion 203.

[0085] The peripheral portion 202 extends around the entire circumference of the MEA 200, and borders the openings 201 and the central portion 203, which are located inside the peripheral portion 202. The openings 201 have a closed contour. The peripheral portion 202 extends in a plane perpendicular to the stacking direction X, parallel to the main plane P.

[0086] The openings 201 are made in the membrane electrode assembly (MEA) 200 to allow the circulation of the reactive fluids through the MEA in the stacking direction X. Each opening 201 extends one of the openings 101 of the cathode polar plate 100 in the stacking direction X. In other words, the openings 101 and 201 are opposite in the stacking direction X. In the example, each opening 201 has the same shape as the opening 101 with which it is opposite.

[0087] The central portion 203 of the MEA 200 faces the circulation field 103 and completely covers the circulation field 103 in the stacking direction X. A peripheral periphery of the central portion 203 may possibly overlap an inner periphery of the peripheral portion 202.

[0088] The central portion 203 of the MEA 200 comprises a membrane 204, which is a proton exchange polymer membrane. The membrane 204 extends parallel to the main plane P, opposite the circulation field 103 in the stacking direction X, and is substantially planar. The membrane 204 is preferably coplanar with the peripheral portion 202. The membrane 204 may be covered with a layer of catalyst on one of its faces or on its two faces parallel to the main plane P. As shown in FIG. 2, the membrane 204 may optionally extend beyond the circulation field 103, in particular in the case where the central portion 203 overlaps a part of the peripheral portion 202. The MEA 200 advantageously comprises a holding frame 206 for supporting the membrane 204. The holding frame 206 then forms the peripheral portion 202.The holding frame 206 is preferably made up of two half-frames of identical shape which are intended to bear flat against each other and which are, for example, made of polymer film, for example polyethylene terephthalate, known by the abbreviation PET, or polyethylene naphthalate, known by the abbreviation PEN. In the latter case, the two half-frames are for example assembled to each other by gluing. As shown in Figures 2, 3 and 5, to hold the membrane 204, the holding frame 206 can pinch in particular an external peripheral periphery of the membrane 204, in the stacking direction X. The holding frame 206 then encloses the entire part of the membrane 204 which overlaps the peripheral portion 202 in the stacking direction X.The holding frame 206 therefore comprises a central opening whose contour delimits, where appropriate, the central portion 203 of the MEA 200, central opening through which the membrane 204 is accessible to the reactive fluid circulating in the circulation field.

[0089] Alternatively, instead of the holding frame 206, it could be provided that the same membrane, such as the membrane 204, forms both the central portion 203 and the peripheral portion 202.

[0090] The gas diffusion layer 205 extends parallel to the main plane P. It is interposed between the central portion 203 and the cathode polar plate 100, along the stacking direction X. In particular, the gas diffusion layer 205 completely covers the central portion 203, namely the membrane 204, and advantageously extends over the peripheral portion 202, namely over the inner periphery of the holding frame 206 pinching the membrane 204. In particular, the gas diffusion layer 205 bears on the channel teeth 052 of the channels 105 along the stacking direction X, and bears against the membrane 204 in the opposite direction.The gas diffusion layer 205 is advantageously formed from a porous material, and allows the cathodic reactive fluid to diffuse from the channels 105 to the membrane 204 when the cell 2 is in operation, and possibly reaction products from the membrane 204 to diffuse to the channels 105 to be evacuated.

[0091] The cell 2 comprises a first peripheral seal 300, which is interposed between the cathode polar plate 100 and the MEA 200, following the stacking direction X. The peripheral seal 300 comprises a main part 301 and fins 302.

[0092] The first peripheral seal 300 may be formed on the cathode pole plate 100, for example by being overmolded onto the cathode pole plate 100, as shown in FIG. 1, but it may alternatively be formed on the MEA 200, or be formed separately from the cathode pole plate 100 and the MEA 200, and then assembled to either of these by any means well known to those skilled in the art. The first peripheral seal 300 is ideally made of an elastomeric material, for example silicone or ethylene-propylene-diene monomer (EPDM), and impermeable to the cathode fluid used in the fuel cell 1.

[0093] The first peripheral seal 300 comprises a main part 301, and at least one, preferably several, fins 302. Preferably, each of said several fins 302 is punctual, that is to say that it is connected only to the main part 301, without being connected to another fin 302 for example. In particular, the fins 302 are at a distance from each other.

[0094] The main part 301 forms a closed loop which, in the present example, extends along the peripheral zone 102, around the entire circumference of the cathode polar plate 100. Correspondingly, the main part 301 extends in a closed loop along the peripheral portion 202 of the MEA 200, here along the holding frame 206, around the entire circumference of the peripheral portion 202. The main part 301 is interposed between the peripheral zone 102 and the peripheral portion 202 in the stacking direction X, so as to seal the space defined in the stacking direction X between the zone 102 and the portion 202, around the entire circumference. In particular, the main part 301 surrounds the circulation field 103, the homogenization fields 104 if they are provided, the openings 101b serving this face of the cathode polar plate 100, or even possibly all the openings 101 of the cathode polar plate 100.The main part 301 also surrounds the gas diffusion layer 205, and the face of the membrane 204 turned, in the opposite direction to the stacking direction X, towards the cathode polar plate 100. The main part 301 comprises two opposite internal longitudinal surfaces 303, each arranged transversely on either side of the circulation field 103, each internal longitudinal surface 303 extending over a portion of the main part 301 parallel to the longitudinal direction Y, being turned towards the circulation field 103. Each internal longitudinal surface 303 connects the peripheral zone 102 to the peripheral portion 202 along the stacking direction X.

[0095] The main part 301 of the first peripheral seal 300, the cathode polar plate 100 and the MEA 200 thus delimit a cathode compartment 40 between them. The main part 301 ensures sealing of the cathode compartment 40 with respect to the exterior of the cell 2, in particular an external zone 3 located beyond the main part 301 of the first peripheral seal 300 with respect to the cathode compartment 40.

[0096] Two cathode bypass zones 50, belonging to the cathode compartment 40, are defined. Each bypass zone 50 is delimited, along the stacking direction X, between the cathode pole plate 100 and the MEA 200, and is delimited, along the transverse direction Z, between, on the one hand, the circulation field 103 and the gas diffusion layer 205 and, on the other hand, the main part 301 of the first peripheral seal 300, for a portion of this main part 301 which extends along the longitudinal direction Y. Each bypass zone 50 extends, along the longitudinal direction Y, along the field 103, or even from one homogenization field 104 to the other. The circulation field 103 is arranged, along the transverse direction Z, between the two bypass zones 50.

[0097] The fins 302 have the function of reducing or preventing a circulation of cathodic reactive fluid in the longitudinal direction Y in the bypass zones 50, in particular in order to concentrate the fluid in the circulation field 103. To do this, each fin 302 closes a cross section of the bypass zone 50 that it occupies, the cross section being taken perpendicular to the longitudinal direction Y. The fins 302 are distributed along the main part 301 of the first peripheral seal.

[0098] 300, in either or both of the cathode bypass zones 50. Each fin 302 is attached to one of the internal longitudinal surfaces 303 of the main portion

[0099] 301. Each fin 302 extends from the internal longitudinal surface 303, generally in the transverse direction Z, towards an interior of the main part 301, in the direction of the circulation field 103. The fins 302 may be formed in one piece with the main part 301.

[0100] Each fin 302 comprises, successively, from the main part 301, a junction part 304, an intermediate part 305 and an end part 306.

[0101] Each fin 302 is, in the examples illustrated, advantageously in the form of a wall which has an elongation in the main plane P, this elongation having a broken line profile, a curve, or a profile constituted by a combination of one or more rectilinear lines and / or one or more broken lines, and / or one or more curves.

[0102] Optionally, each fin 302 in the form of a wall preferably has at any point considered along its elongation, in cross-section through a plane perpendicular to the elongation of the wall at this point considered, a thickness along the longitudinal direction Y, also called width, and a thickness along the stacking direction X such that the thickness along the longitudinal direction Y is smaller than the thickness along the stacking direction X, in particular to extend from the cathode polar plate 100 to the MEA 200 over at least a portion of the length of the fin 302 along the transverse direction Z, or even over its entire length. According to another option, the thickness along the longitudinal direction Y is greater than the thickness along the stacking direction X, or varies depending on the point of the elongation considered.

[0103] Preferably, each of the joining parts 304, intermediate part 305 and end part 306 has the same width, that is to say the same thickness measured in the Y direction. In other words, each of the fins 302 has a thickness in the Y direction that is substantially constant. This makes it possible to minimize the material used to form the fins 302 and to guarantee the correct formation of the fins 302, in particular the continuity of material during the manufacturing process of the peripheral seal 300.

[0104] The fin 302 is connected to the main part 301 via the joining part 304, which extends from the internal longitudinal surface 303. In particular, the fin 302 is attached to the main part 301 only via the joining part 304.

[0105] In the present example, the junction part 304 is rectilinear and its projection onto the main plane P is perpendicular to the longitudinal direction Y, i.e. parallel to the transverse direction Z. The junction part 304 is interposed along the stacking direction X between the peripheral zone 102 of the cathode polar plate 100 and the peripheral portion 202 of the MEA 200.

[0106] The intermediate part 305 of the fin 302 is attached to the junction part 304, extending it in the direction of the field 103. In the present example, the intermediate part 305 is rectilinear and its projection onto the main plane P is oblique relative to the main part 301, or even oblique relative to the longitudinal direction Y. The intermediate part 305 is interposed in the stacking direction X between the peripheral zone 102 of the cathode polar plate 100 and the peripheral portion 202 of the MEA 200.

[0107] A length of the junction part 304, in projection in the plane P, is preferably less than the length of the intermediate part of the fin 302, for example representing less than 50%, preferably less than 30%, advantageously less than 10% of the length of the intermediate part 305.

[0108] The end portion 306 of the fin 302 is attached to the intermediate portion 305, extending it in the direction of the field 103. The end portion 306 terminates the fin 302. In the present example, the end portion 306 is rectilinear and its projection onto the main plane P is perpendicular to the longitudinal direction Y, that is to say is parallel to the transverse direction Z.

[0109] The intermediate 305 and end 306 portions are not attached to the main portion 301 other than by the joining portion 304. At least one portion of the fin 302, called the contact portion 307 of the fin 302, belonging to the end portion 306 and including the end of the fin 302, is interposed between the gas diffusion layer 205 and the peripheral zone 102 in the stacking direction X. Optionally, another portion of the end portion 306, by which the end portion 306 is attached to the intermediate portion 305, is interposed between the peripheral zone 102 and the peripheral portion 202.

[0110] The end portion 306 and the intermediate portion 305 form between them an angle advantageously between 110 and 150 degrees, ideally 120 degrees. The intermediate portion 305 and the junction portion 304 form an angle advantageously between 110 and 150 degrees, ideally 120 degrees.

[0111] Thus, according to the embodiment of figures 1 to 5, each fin 302 has an extension trajectory forming a zigzag in projection in the plane P from the main part 301 in the direction of the field 103.

[0112] As shown in Figures 2, 3 and 4, the contact portion 307 of the fin 302 is elastically deformed, in compression along the stacking direction X, between the gas diffusion layer 205 and the peripheral zone 102. The contact portion 307 being thus compressed, it has a thickness, measured along the stacking direction X, which is less than that of the rest of the fin 302, in particular that of the junction portion 304 and the intermediate portion 305. In the undeformed state of the fin 302, as shown in Figure 5, it can be provided that the portion 307 initially has the same thickness along the stacking direction X as the rest of the fin 302. This compressive deformation of the contact portion 307 can also deform the intermediate portion 305. As shown in section in Figure 3, the intermediate portion 305 can resume this deformation of the extreme part 306 by twisting slightly.The fact that the intermediate part 305 is oblique relative to the longitudinal direction Y advantageously avoids transmitting the deformation to the junction part 304 and to the main part 301. The particular orientation of the intermediate part 305 therefore prevents mechanical stresses, linked to the flattening of the contact zone 307 between the layer 205 and the peripheral zone 102, from being applied to the main part 301.

[0113] The anode pole plate 100' is similar to the cathode plate 100, except for some differences, the main ones of which are discussed below. The anode pole plate 100' extends parallel to a principal plane P of the cell 2, perpendicular to the stacking direction X, and is disposed beyond the MEA 200 with respect to the cathode pole plate 100.

[0114] The anodic polar plate 100' is advantageously formed by the same material as the cathodic polar plate 100 and comprises, like the cathodic polar plate 100, a peripheral zone 102', similar to the peripheral zone 102, openings, similar to the openings 101, two homogenization fields, similar to the fields 104, and a circulation field 103', similar to the field 103.

[0115] The peripheral zone 102' extends around the entire circumference of the anode polar plate 100', and borders the openings, the homogenization fields and the circulation field 103'. As for the cathode polar plate 100, the openings, the homogenization fields and the circulation field 103' of the anode polar plate 100' are arranged inside the peripheral zone 102'. The peripheral zone 102' extends in a plane perpendicular to the stacking direction X, parallel to the main plane P.

[0116] Like the openings 101, each opening of the anode polar plate 100' is used for the injection or evacuation of reactive fluid or cooling fluid, in correspondence with the openings 101. Along the stacking direction X, the openings of the anode plate 100' are each connected to one of the openings 101 via one of the openings 201 of the MEA 200.

[0117] The circulation field 103' extends between the two homogenization fields of the plate 100' in the longitudinal direction Y. On one face of the anode polar plate 100' facing the membrane electrode assembly 200, i.e. in the opposite direction to the stacking direction X, the circulation field 103' comprises channels 105', formed in hollows, and extending substantially parallel to the longitudinal direction Y. The channels 105' may be delimited by grooves hollowed out in the anode polar plate 100', or by stamping the anode polar plate 100'.

[0118] Each channel 105' is delimited in depth along the stacking direction X by a channel bottom 105T formed by the anode polar plate 100', extending along the longitudinal direction Y. The channel bottom 1051' may be substantially flat as illustrated in the figures in a simplified manner, but most often has a slightly rounded profile in section by a transverse plane containing the transverse direction Z. In certain embodiments, such as that illustrated in FIG. 2, the channel bottoms 1051' are, at least at their point of greatest depth of the channel 105' along the stacking direction, coplanar with the peripheral zone 102'. In a variant not shown, the channel bottoms 105T protrude relative to the peripheral zone 102' along the stacking direction X.

[0119] Each channel 105' is also delimited by two channel teeth 1052', formed by the anode pole plate 100', set back from the channel bottom 1051' in the stacking direction X. Preferably, the channel teeth 1052' are also set back from the peripheral zone 102' along the stacking direction X. The channel teeth 1052' are substantially planar and parallel to the channel bottom 1051'. Alternatively, the channel teeth 1052' have a slightly rounded profile in section by a transverse plane containing the transverse direction Z and the stacking direction X. The channel teeth 1052' border the channel bottom 1051' along the length of the channel bottom 1051' along the longitudinal direction Y.

[0120] The channel bottom 1051' is continuously connected to each channel tooth 1052' by an inclined portion 1053' formed by the anode pole plate 100'. The channel 105' is therefore also delimited by two inclined portions 1053'.

[0121] As for the cathode polar plate 100, each homogenization field of the anode polar plate 100' is arranged between the circulation field 103' and the openings of the anode polar plate 100' in the longitudinal direction Y and may comprise channels, for example fan-shaped. The first homogenization field makes it possible to distribute the reactive fluid coming from one of the openings of the anode polar plate 100' so that it circulates in the circulation field 103' and the second homogenization field makes it possible to evacuate the reactive fluid distributed over the entire circulation field 103' to another opening. While the field 103 of the cathode polar plate 100 was supplied with cathode reactive fluid, namely air or oxygen, by the openings 101 b, the field 103' is supplied with anodic reactive fluid, for example hydrogen, by the openings of the anodic polar plate 100' corresponding to the openings 101 a.The contours of the other openings of the anode polar plate 100', corresponding to the openings 101b and 101c, are tightly closed so that only the anode reactive fluid can circulate in the circulation field 103'.

[0122] The MEA 200 comprises another gas diffusion layer 205', which extends parallel to the main plane P. It is interposed between the central portion 203 of the MEA 200 and the anode polar plate 100', along the stacking direction X. The central portion 203 of the MEA 200 is therefore interposed, along the stacking direction X, between the two gas diffusion layers 205 and 205'. In particular, the layer 205' completely covers the central portion 203 of the MEA 200, namely the membrane 204, and advantageously extends over the peripheral portion 202, namely over the inner periphery of the holding frame 206 pinching the membrane 204. In particular, the gas diffusion layer 205' bears on the channel teeth 1052' of the channels 105' in the direction opposite to the stacking direction X.The gas diffusion layer 205' is advantageously formed of a porous material, and allows the anodic reactive fluid to diffuse from the channels 105' to the membrane 204 when the cell 2 is in operation, and possibly reaction products from the membrane 204 to diffuse to the channels 105' to be evacuated.

[0123] By supplying the anodic and cathodic reactive fluids via the fields 103 and 103', through the gas diffusion layers 205 and 205', a chemical reaction between said reactive fluids takes place at the membrane 204 of the cell 2. By exchange of protons between the anodic reactive fluid and the cathodic reactive fluid through the membrane, an electrical potential difference is generated between the cathodic polar plate 100 and the anodic polar plate 100'.

[0124] The cell 2 comprises a second peripheral seal 300', preferably similar to the seal 300, and which is interposed between the anode polar plate 100' and the MEA 200, following the stacking direction X. The peripheral seal 300' comprises a main part 301' and fins 302', similar to the main part 301 and the fins 302.

[0125] The second peripheral seal 300' may be formed on the anode pole plate 100', for example by being overmolded onto the anode pole plate 100', but it may alternatively be formed on the MEA 200, or be formed separately from the anode pole plate 100' and the MEA 200. The seal 300' is ideally made of an elastomeric material, and impermeable to the anode fluid used in the fuel cell 1.

[0126] In particular, the main part 30T of the second peripheral seal 300' forms a closed loop which, in the present example, extends along the peripheral zone 102', around the entire circumference of the anode polar plate 100'. Correspondingly, the main part 30T extends in a closed loop along the peripheral portion 202 of the MEA 200, here along the holding frame 206, around the entire circumference of the peripheral portion 202. The main part 30T is interposed between the peripheral zone 102' and the peripheral portion 202 in the stacking direction X, so as to seal the space defined in the stacking direction X between the zone 102' and the portion 202, around the entire circumference.In particular, the main part 30T surrounds the circulation field 103', the homogenization fields of the anode polar plate 100' if they are provided, the openings serving this face of the anode polar plate 100' in anode fluid, otherwise all the openings of the anode polar plate 100'. The main part 301' also surrounds the gas diffusion layer 205', and the face of the membrane 204' facing in the direction of the stacking direction X. The main part 301' comprises two opposite internal longitudinal surfaces 303', each arranged transversely on either side of the circulation field 103', each internal longitudinal surface 303' extending over a portion of the main part 30T parallel to the longitudinal direction Y, facing in the direction of the circulation field 103'. Each internal longitudinal surface 303' connects the peripheral zone 102' to the peripheral portion 202 along the stacking direction X.

[0127] The main part 301' of the second peripheral seal 300', the anode polar plate 100' and the MEA 200 thus delimit an anode compartment 40' between them. The main part 301' of the second peripheral seal 300' ensures sealing of the anode compartment 40' with respect to the exterior of the cell 2, in particular the external zone 3.

[0128] Two anode bypass zones 50', belonging to the anode compartment 40', are defined. Each bypass zone 50' is delimited, along the stacking direction X, between the anode polar plate 100' and the MEA 200, and is delimited, along the transverse direction Z, between, on the one hand, the circulation field 103' and the gas diffusion layer 205' and, on the other hand, the main part 30T of the second peripheral seal 300', for a portion of this main part 30T which extends along the longitudinal direction Y. Each bypass zone 50' extends, along the longitudinal direction Y, along the field 103'. The circulation field 103' extends between the two bypass zones 50' along the transverse direction Z.

[0129] The fins 302' have the function of reducing, or preventing, a circulation of anodic reactive fluid in the longitudinal direction Y in the bypass zones 50'. To do this, each fin 302' closes a cross-section of the bypass zone 50' that it occupies, the cross-section being taken perpendicular to the longitudinal direction Y. The fins 302' are distributed along the main part 301' of the second peripheral seal 300', in one or the other, or both, anodic bypass zones 50'. Each fin 302' is attached to one of the internal longitudinal surfaces 303' of the main part 301' of the second peripheral seal 300'. Each fin 302' extends from the inner longitudinal surface 303', generally in the transverse direction Z, and towards the circulation field 103'. The fins 302' may be formed integrally with the main portion 30T.

[0130] Each fin 302' comprises, successively from the main part 301', a junction part 304', an intermediate part 305' and an end part 306. Each fin 302' is, in the examples illustrated, advantageously in the form of a low wall which has an elongation in the main plane P, this elongation having a broken line profile, a curve, or a profile consisting of a combination of one or more rectilinear lines and / or one or more broken lines, and / or one or more curves.

[0131] Optionally, each wall-shaped fin preferably has at any point considered along its elongation, in cross-section through a plane perpendicular to the elongation of the wall at this point considered, a thickness along the longitudinal direction Y, also called width, and a thickness along the stacking direction X such that the thickness along the longitudinal direction Y is smaller than the thickness along the stacking direction X, in particular to extend from the anode polar plate 100' to the MEA 200' over at least part of the length of the fin 302' along the transverse direction Z, or even over its entire length.

[0132] Alternatively, the thickness along the longitudinal direction Y is greater than the thickness along the stacking direction X, or varies depending on the point of the elongation considered.

[0133] Preferably, each of the joining parts 304', intermediate part 305' and end part 306' has the same width, i.e. the same thickness measured along the Y direction. In other words, each of the fins 302' has a thickness along the Y direction that is substantially constant. This makes it possible to minimize the material used to form the fins 302' and to guarantee the correct formation of the fins 302', in particular the continuity of material during the manufacturing process of the peripheral seal 300'.

[0134] The fin 302' is connected to the main part 301' via the joining part 304', which extends from the internal longitudinal surface 303'. In the present example, the joining part 304' is rectilinear and its projection onto the main plane P is perpendicular to the longitudinal direction Y, i.e. parallel to the transverse direction Z. The joining part 304' is interposed along the stacking direction X between the peripheral zone 102' of the anode pole plate 100' and the peripheral portion 202 of the MEA 200.

[0135] The intermediate portion 305' of the fin 302' is attached to the joining portion 304', extending it in the direction of the field 103'. In the present example, the intermediate portion 305' is rectilinear and its projection onto the main plane P is oblique relative to the longitudinal direction Y. The intermediate portion 305' is interposed along the stacking direction X between the peripheral zone 102' of the anode polar plate 100' and the peripheral portion 202 of the MEA 200. A length of the joining portion 304', in projection into the plane P, is preferably less than the length of the intermediate portion of the fin 302, for example representing less than 50%, preferably less than 30%, advantageously less than 10% of the length of the intermediate portion 305.

[0136] The end portion 306' of the fin 302' is attached to the intermediate portion 305', extending it in the direction of the field 103'. The end portion 306' terminates the fin 302'. In the present example, the end portion 306' is rectilinear and its projection onto the main plane P is perpendicular to the longitudinal direction Y, that is to say is parallel to the transverse direction Z.

[0137] At least a portion of the fin 302', called the contact portion 307', belonging to the end portion 306' of the fin 302' and including the end of the fin 302', is interposed between the gas diffusion layer 205' and the peripheral zone 102' in the stacking direction X. Optionally, another portion of the end portion 306', by which the end portion 306' is attached to the intermediate portion 305', is interposed between the peripheral zone 102' and the peripheral portion 202.

[0138] The end portion 306' and the intermediate portion 305' form an angle advantageously between 110 degrees and, ideally, 120 degrees. The intermediate portion 305' and the junction portion 304' form an angle advantageously between 110 and 150 degrees, ideally 120 degrees.

[0139] Thus, according to the embodiment of figures 1 to 4, each fin 302' has an extension trajectory forming a zigzag in projection in the plane P from the main part 301' in the direction of the circulation field 103'.

[0140] As shown in Figures 2, 3 and 4, the contact portion 307' of the fin 302' is elastically deformed, in compression along the stacking direction X, between the gas diffusion layer 205' and the peripheral zone 102'. This compressive deformation of the contact portion 307' can also deform the intermediate portion 305'. As shown in section in Figure 3, the intermediate portion 305' can take up this deformation of the end portion 306' by twisting slightly. The fact that the intermediate portion 305' is oblique relative to the longitudinal direction Y advantageously avoids transmitting the deformation to the junction portion 304' and to the main portion 301'. The particular orientation of the intermediate part 305' therefore prevents mechanical stresses, linked to the flattening of the contact zone 307' between the layer 205' and the peripheral zone 102', from being applied to the main part 301'.

[0141] To illustrate the elastic deformation of the fins 302 when the cell 2 is assembled, the same cell 2 is also shown in an unassembled state in FIG. 5. Before the assembly of the cell as shown in FIG. 5, the end portions 306 and 306' of the seals 300 and 300' are not compressed along the stacking direction X between the gas diffusion layer 205 and the peripheral zone 102 and between the gas diffusion layer 205' and the peripheral zone 102' respectively. The thickness of the contact portions 307 and 307' is identical to the rest of the fins 302 and 302'. FIG. 5 also illustrates the case where the seals 300 and 300' are secured to the plates 100 and 100' respectively, rather than to the MEA 200.

[0142] In practice, in the fuel cell 1, several cells 2 such as that described above are stacked in the stacking direction X, each cell comprising the cathode polar plate 100, the first peripheral seal 300, the MEA 200, the second peripheral seal 300', and the anodic polar plate 100'.

[0143] As shown in Figure 2, several cells 2 are superimposed on each other in the stacking direction X, so that the anode polar plate 100' of a cell 2 bears against the cathode polar plate 100 of the next cell 2 along the stacking direction X, said plates 100' and 100 of two adjacent cells, thus being superimposed along the stacking direction X. The anode polar plate 100' and the cathode polar plate 100 of two adjacent cells 2, thus superimposed, form a bipolar plate 10. In the present example, the plates 100 and 100' of the bipolar plate 10 are fixed together, for example by being welded or glued together. For example, the peripheral zones 102 and 102' bear against each other in the stacking direction X. If necessary, the welding or bonding can be carried out along said peripheral zones 102 and 102', around the entire periphery of the bipolar plate 10.

[0144] The chemical reaction between the reactive fluids at the membrane 204 being exothermic, it may be desirable to cool the cell. For this, preferably, on the back of the circulation fields 103 and 103', the plates 100 and 100' of the bipolar plate 10 delimit between them, in the stacking direction X, a circulation field 13, inside the bipolar plate 10, for circulation of cooling fluid. Where appropriate, the welding or bonding between the peripheral zones 102 and 102' ensures a seal between the circulation field 13 and the outside of the bipolar plate 10, by forming a closed loop surrounding the circulation field 13. Preferably, the circulation field 13 is supplied with cooling fluid through one of the openings 101 of the plates 100 and 100', here one of the openings 101c. The coolant is discharged through the other opening 101c.The other openings 101a and 101b are sealed against the circulation field 13, so that no reactive fluid can be admitted into the circulation field 13. For example, the cooling fluid circulates from one opening 101c to the other in the longitudinal direction Y, via the circulation field 13.

[0145] Figures 6 and 7 illustrate a second embodiment, identical to the first embodiment illustrated in Figures 1 to 5, except for the differences indicated below. For Figures 1 to 5 and Figures 6 and 7, identical reference signs are used to designate identical features between the two embodiments. For the embodiment of Figures 6 and 7, reference signs increased by 200 are used to designate features corresponding to those described for Figures 1 and 5, but which have differences. The following description focuses on the differences of the embodiment of Figures 6 and 7 compared to that of Figures 1 to 5, and does not describe again in detail the features which are identical, or based on the same principles.

[0146] For this embodiment of figures 6 and 7, the peripheral portion 202 of the MEA 200 is advantageously replaced by a peripheral portion 402. The peripheral portion 402 is preferably not formed by a holding frame, but by a peripheral continuation 406 which extends the membrane 204 parallel to the plane P. In this embodiment, the peripheral continuation 406 and the membrane 204 preferably form a single membrane, in one piece, said membrane forming both the central portion 203 and the peripheral portion 202 of the MEA 200.

[0147] Furthermore, and independently of the presence of a peripheral continuation 406 or, instead, of the presence of a peripheral portion 402, for this embodiment of FIGS. 6 and 7, a first peripheral seal 500 replaces the first peripheral seal 300. The first peripheral seal 500 comprises the same main part 301 as that of the seal 300. On the other hand, the fins 302 of the seal 300 are replaced by fins 502 for the seal 500. Each fin 502 comprises the same joining part 304 as the fin 302, the same intermediate part 305 as the fin 302, and comprises an end part 506 which replaces the end part 306 of the fin 302.

[0148] Like the end portion 306, the end portion 506 is interposed between the gas diffusion layer 205 and the peripheral continuation 406 on the one hand, and the peripheral zone 102 on the other hand, according to the stacking direction X. The end portion 506 is attached to the intermediate portion 305. The end portion 506 is rectilinear. Unlike the end portion 306, the projection of the end portion 506 onto the main plane P is diagonal to the longitudinal direction Y so that the end portion 506 extends the intermediate portion 305 while being aligned with the intermediate portion 305. Thus, the assembly composed of the intermediate portion 305 and the end portion 506 is rectilinear and its projection onto the main plane P is diagonal to the longitudinal direction Y. The end portion 506 comprises a contact portion 507.The contact portion 507 corresponds to the portion of the end part 506 interposed between the gas diffusion layer 205 and the peripheral zone 102 in the stacking direction X.

[0149] Thus, according to the embodiment of figures 6 to 7, each fin 502 has an extension trajectory substantially forming a comma from the main part 301 in the direction of the field 103.

[0150] For this embodiment of Figures 6 and 7, a second peripheral seal 500' preferably replaces the second peripheral seal 300'. The peripheral seal 500' comprises the same main part 301' as that of the seal 300'. On the other hand, the fins 302' of the seal 300' are replaced by fins 502' for the seal 500'. A fin 502' comprises the same joining part 304' as the fin 302', the same intermediate part 305' as the fin 302', and comprises an end part 506' which replaces the end part 306' of the fin 302'. The same characteristics as those described above for the parts 304, 305, 506 and 507 of the fin 502 apply mutatis mutandis to the parts 304', 305', 506' and 507' of the fin 502'.

[0151] For this embodiment of figures 6 and 7, the anode 100' and cathode 100' polar plates are identical to those provided in figures 1 to 5, or of similar construction, except that, instead of being fixed to each other by welding or gluing, they bear against each other in the stacking direction X without being fixed to each other.

[0152] More precisely, independently of the shape of the fins and independently of the presence of a peripheral continuation 406 or, instead, of the presence of a peripheral portion 402, the plates 100 and 100' of figures 6 and 7, belonging respectively to two adjacent cells 2, are in abutment against each other by means of a plate joint 211, which is interposed, in the stacking direction X, between the plates 100' and 100 belonging respectively to two adjacent cells. The plate seal 211 comprises a main part 212, which is interposed between the peripheral areas 102 and 102' along the stacking direction X and which forms a closed loop surrounding the circulation field 13, to prevent leakage of coolant between the circulation field 13 and the outside of a bipolar plate 210 formed by the plate 100, the plate 100' and the plate seal 211.Similar to the seals 300, 300', 500 and 500', the seal 211 also includes fins 213, which extend from the main portion 212 towards the field 13, in the transverse direction Z, the fins 213 being arranged between the plates 100 and 100' in the stacking direction X. The fins 213 are intended to ensure that the coolant circulates, for the most part, between the circulation fields 103 and 103', rather than between the peripheral zones 102 and 102', thus improving the cooling efficiency.

[0153] Figure 8 illustrates a third embodiment, identical to the first embodiment illustrated in Figures 1 to 5, except for the differences indicated below. For Figures 1 to 5 and Figure 8, identical reference signs are used to designate features identical to those previously described. For the embodiment of Figure 8, reference signs increased by 400 are used to designate features corresponding to those described for Figures 1 and 5, but which have differences. The following description focuses on the differences of the embodiment of Figure 8 compared to that of Figures 1 to 5, and does not describe again in detail the features which are identical, or based on the same principles.

[0154] For the embodiment of Figure 8, the first peripheral seal 300 is replaced by a first peripheral seal 700, which comprises a main part 301 identical to that of the seal 300 and fins 702 replacing the fins 302.

[0155] Each fin 702 has a joining portion 704, replacing the joining portion 304, an intermediate portion 305, identical to that of the fin 302, and an end portion 306, identical to that of the fin 302. The joining portion 704 extends from the main portion 301 from the internal longitudinal surface 303. Like the joining portion 304, the joining portion 704 is rectilinear. However, unlike the joining portion 304, the projection of the joining portion 704 onto the main plane P is diagonal to the longitudinal direction Y. The intermediate portion 305 is attached to the joining portion 704 and is aligned with the joining portion 704. Thus, the assembly composed of the joining portion 704 and the intermediate portion 305 is rectilinear and its projection onto the main plane P is diagonal to the longitudinal direction Y.

[0156] Figures 9 and 10 illustrate a fourth embodiment, identical to the first embodiment illustrated in Figures 1 to 5, except for the differences indicated below. For Figures 1 to 5 and Figures 9 and 10, identical reference signs are used to designate features identical to those described previously. The following description focuses on the differences of the embodiment of Figures 9 and 10 compared to that of Figures 1 to 5, and does not describe again in detail the features which are identical, or based on the same principles.

[0157] For the embodiment of Figures 9 and 10, the peripheral portion 202 of the MEA 200 is replaced by the peripheral portion 402, with the peripheral continuation 406, as described for the embodiment of Figures 6 and 7. For the embodiment of Figures 9 and 10, the anode 100' and cathode 100 polar plates are identical to those provided in Figures 1 to 5, or of similar construction, except that, two anode 100' and cathode 100 polar plates belonging respectively to two adjacent cells, instead of being fixed to each other by welding, they bear against each other in the stacking direction X without being fixed to each other, with the interposition of the plate joint 211 described above for the embodiment of Figure 6.

[0158] Figure 11 illustrates a fifth embodiment, identical to the first embodiment illustrated in Figures 1 to 5, except for the differences indicated below. For Figures 1 to 5 and Figure 11, identical reference signs are used to designate features identical to those previously described. For the embodiment of Figure 11, reference signs increased by 600 are used to designate features corresponding to those described for Figures 1 and 5, but which have differences. The following description focuses on the differences of the embodiment of Figure 11 compared to that of Figures 1 to 5, and does not describe again in detail the features which are identical, or based on the same principles.

[0159] For the embodiment of Figure 11, the seal 300 is replaced by the seal 900, which comprises a main part 301 identical to that of the seal 300. On the other hand, the wings 302 are replaced by fins 902. The fin 902 comprises a joining part 904, replacing the joining part 304, an intermediate part 905, replacing the intermediate part 305, and an end part 906, replacing the end part 306. These parts 904, 905 and 906 follow one another from the main part 301, in the direction of the circulation field 103.

[0160] Overall, the fin 902 snakes along an axis parallel to the transverse Z direction.

[0161] The fin 902 is attached to the internal longitudinal surface 303 of the main part 301 via the joining part 904. Instead of being rectilinear like the joining part 304, the joining part 904 is curved and its projection onto the main plane P is curved relative to the longitudinal direction Y. At least a portion of the joining part 904 is therefore oblique relative to the main part 301, in projection into the plane P.

[0162] The intermediate part 905 is attached to the joining part 904. Instead of being rectilinear like the intermediate part 305, the intermediate part 905 is curved and its projection onto the main plane P is curved. The intermediate part 905 is oblique relative to the main part 301, in projection into the plane P, being preferentially directed along an inverted oblique relative to the joining part 904.

[0163] The end portion 906 is attached to the intermediate portion 905 and terminates the fin 302. The end portion 906 is interposed between the gas diffusion layer 205 and the holding frame 206 on the one hand, and the peripheral zone 102 on the other hand according to the stacking direction X. Unlike the end portion 306 which is rectilinear, the end portion 906 is curved and its projection onto the main plane P is curved relative to the longitudinal direction Y. The end portion 906 is oblique relative to the main portion 301, in projection into the plane P, being preferentially directed along an inverted oblique relative to the intermediate portion 905.

[0164] The end portion 906 comprises a contact portion 907, which can be compared to the contact portion 307 described above. The contact portion 907 corresponds to the portion of the end portion 906 interposed between the gas diffusion layer 205 and the peripheral zone 102 in the stacking direction X.

[0165] Figures 12 and 13 illustrate a sixth embodiment, identical to the fourth embodiment illustrated in Figures 9 and 10 except for the differences indicated below. For Figures 12 and 13, identical reference signs are used to designate features identical to those previously described. For the embodiment of Figures 12 and 13, reference signs increased by 800 are used to designate features corresponding to those described for Figures 1 and 5, but which have differences. The following description focuses on the differences of the embodiment of Figures 12 and 13 compared to that of Figures 9 and 10, and does not describe again in detail the features which are identical, or based on the same principles.

[0166] For this embodiment of Figures 12 and 13, the first peripheral seal 300 is replaced by a first peripheral seal 1100. The first peripheral seal 1100 comprises a main part 301 identical to that described previously. The seal 1100 comprises fins 1102, replacing the fins 302. The fin 1102 has a joining part 1104, replacing the joining part 304, an intermediate part 305 identical to that of the fin 302 and an end part 306 identical to that of the fin 302.

[0167] The joining portion 1104 differs from the joining portion 304 only in that it comprises an opening 1105, in the form of a notch in the fin 1102, which separates the joining portion 304 from the peripheral portion 402. To form this opening 1105, the thickness of the joining portion 1104 measured in the stacking direction X is less than the thickness measured in the stacking direction X of the intermediate portion 305. This opening 1105 in the longitudinal direction Y allows the circulation of fluids through the fin 1102, for example in order to evacuate reaction products or condensation which could form between the successive fins 1102.

[0168] For this embodiment of Figures 12 and 13, the second peripheral seal 300' is replaced by a peripheral seal 1100'. The peripheral seal 1100' comprises a main part 30T identical to that described previously. The peripheral seal 1100' comprises fins 1102', replacing the fins 302'. The fin 1102' has a joining part 1104', replacing the joining part 304', an intermediate part 305' identical to that of the fin 302' and an end part 306' identical to that of the fin 302'. The joining part 1104' forms an opening 1105', according to the same principle as the opening 1105 the joining part 1104.

[0169] Figure 14 illustrates a seventh embodiment, identical to the embodiment of Figures 12 and 13 except for the differences described below. For Figure

[0170] 14, identical reference signs are used to designate features identical to those described previously. For the embodiment of Figure 14, reference signs increased by 200 are used to designate features corresponding to those described in Figures 12 and 13, but which have differences. The following description focuses on the differences of the embodiment of Figure 14 compared to the previous ones, and does not describe again in detail the features which are identical, or based on the same principles.

[0171] For the embodiment of Figure 14, the peripheral seal 1100' is replaced by the peripheral seal 700 of Figure 8, and the plate seal 21 1 is replaced by a plate seal 41 1.

[0172] The plate seal 41 1 comprises a main part 212, identical to that of the seal 21 1. Similar to the seal 21 1, the seal 411 also comprises fins 413, replacing the fins 213. The fins 413 differ from the fins 213 in that they comprise a notch 414, to allow circulation of cooling fluid through the fin 413, according to the same principle as the opening 1105.

[0173] Figure 15 illustrates an eighth embodiment, identical to the first embodiment of Figures 1 to 5, except for the differences described below. For Figure

[0174] 15, identical reference signs are used to designate features identical to those described previously. The following description focuses on the differences of the embodiment of Figure 15 from that of Figures 1 to 5, and does not describe again in detail features that are identical, or based on the same principles.

[0175] In addition to all the elements already described for the embodiment of Figures 1 to 5, the embodiment of Figure 15 provides a dam 310, which extends parallel to the main part 301 of the seal 300, that is to say parallel to the longitudinal direction Y. The dam 310 is interposed, in the stacking direction X, between the peripheral zone 102 and the diffusion layer 205. The dam 310 is arranged, in the transverse direction Z, between the circulation field 103 and the seal 300. The dam 310 advantageously connects all or part of the fins 302 together, the respective end part 306 of each fin 302 or at least of several fins 302, being attached to the dam 310. Preferably, the dam 310 is made of the same material as the seal 300, so as to be able to be formed at the same time, with the same material and / or to be made of the same material as the seal 300.

[0176] The dike 310 borders the circulation field 103, it aims to delimit a channel 295, which, preferably, is added to the channels 105 and which has the same function as these channels 105. The channel 295 is delimited, in the stacking direction X, by the peripheral zone 102, which ensures the same function as the channel bottom 1051 for the channel 105, and the layer 205. The channel 295 is therefore delimited, in the transverse direction Z, by a channel tooth 1052 of the cathode polar plate 100, and by the dike 310, which is adjacent and parallel to this channel tooth 1052, which can be called the last channel tooth. The additional channel 295 is therefore preferably provided to also conduct the circulation of reactive fluid opposite the active zone of the MEA 200, which is the central portion 203 of the MEA 200 over the extent of which the membrane 204 is accessible to the reactive fluid circulating in the circulation field.The presence of the dam 310 makes it possible to simplify the production of one or more fins 302 attached to the dam 310, therefore which extend transversely over the entire transverse dimension between the main part 301 of the peripheral seal 300 and this dam 310, therefore across the entire bypass zone 40 to form an additional channel, here the channel 295, to conduct the circulation of reactive fluid. Such an embodiment is particularly advantageous if the channel teeth 1052 of the circulation field 103 are produced by stamping the cathode pole plate 100, the latter being made of metal. Indeed, in this case, it can be complex to produce fins 302 from molded polymer material, in particular with the same material and the same production method as the peripheral seal 300, which come into contact with the last stamped metal tooth.In such a case, the presence of the dam 310 allows the last channel tooth of the active zone, instead of being stamped, to be formed by a tooth of the same material as the peripheral seal 300 and the fins 302 so that they form only one.

[0177] Thus, in the example of Figure 15, the dam 310 is located, along the stacking direction X, opposite the central portion 203 of the MEA 200, at its demarcation with the peripheral portion 202, so that the channel 295 is opposite the central portion 203. In other words, along the transverse direction Z, the dam 310 is offset towards the inside of the cell relative to the inner periphery of the frame 206, where the frame 206 pinches the membrane 204.

[0178] Figures 16 and 17 illustrate a ninth embodiment, identical to the eighth embodiment of Figure 15 except for the differences described below.

[0179] In this embodiment, the same reference signs as for Figure 15 are used. In this embodiment of Figures 16 and 17, the dam 310 is offset in the transverse direction Z towards the outside of the cell 2 relative to the dam 310 of Figure 15. In other words, the dam 310 of Figures 16 and 17 is opposite, in the stacking direction X, the demarcation between the peripheral portion 202 and the central portion 203, that is to say opposite the inner periphery of the frame 206 pinching the central portion 203. Thus, the channel 295 is opposite a part of the central portion 203 which runs directly along the frame 206. In such a case, it will be possible to seek to place the dam 310 as close as possible, in the transverse direction Z, to the last canal tooth.

[0180] The channel 295 delimited by the dike 310 is not necessarily the same size as a channel 103 and, in particular in the case of figures 16 and 17, we may seek to minimize its size, in particular in the transverse direction Z.

[0181] In a variant not shown, the fins of the first peripheral seal 300, 500, 700, 900, 1100 may not be opposite the fins of the second peripheral seal 300', 500', 1100', but offset from each other in the longitudinal direction Y. According to other variants not shown, the same first peripheral seal 300, 500, 700, 900, 1100 or second peripheral seal 300', 500', 1100' may comprise fins of different shapes, and a first peripheral seal 300, 500, 700, 900, 1100 may have fins different from a second peripheral seal 300', 500', 1100'.

[0182] Any feature described for one of the foregoing embodiments or variations may be implemented in the other embodiments and variations described above. In particular, any fin and any main portion of a peripheral seal or plate seal may be implemented in any other peripheral or plate seal described above. The dam 310 may be applied to any peripheral or plate seal described above. In particular, a fin may include both curved and straight portions.

Claims

CLAIMS 1. Peripheral seal (300; 500; 700; 900; 1100), for a cell (2) for a fuel cell (1), the peripheral seal (300; 500; 700; 900; 1100) comprising: • a main part (301), being configured to be interposed, in a stacking direction (X) of the fuel cell, between: ♦ a peripheral zone (102) belonging to a polar plate (100) of the cell (2), the polar plate (100) extending parallel to a main plane (P) of the cell (2), the main plane (P) being perpendicular to the stacking direction (X), the polar plate (100) comprising a circulation field (103) of a reactive fluid, surrounded by the peripheral zone (102), and ♦ a peripheral portion (202; 402) belonging to a membrane-electrode assembly (200), the membrane-electrode assembly further comprising at least one gas diffusion layer (205), • at least one fin (302; 502; 702; 902; 1102) comprising a joining part (304; 704; 904; 1104), by means of which the fin (302; 502; 702; 902; 1102) is attached to the main part (301); characterized in that said at least one fin (302; 502; 702; 902; 1102) further comprises: • an end portion (306; 506; 906) terminating the fin (302; 502; 702; 902; 1102), configured to be interposed, in the stacking direction (X), between the gas diffusion layer (205) and the peripheral zone (102), and • an intermediate part (305; 905; 1105), connecting the junction part (304; 704; 904; 1104) to the end part (306; 506; 906), the intermediate part (305; 905; 1105) being configured to be oblique relative to the main part (301) of the joint peripheral (300; 500; 700; 900; 1100), in projection in the main plane (P).

2. Peripheral seal (300; 500; 700; 900; 1100) according to claim 1, comprising several fins (302; 502; 702; 902; 1102), each fin (302; 502; 702; 902; 1102) being connected to the main part (301) only via the joining part (304; 704; 904; 1104).

3. Peripheral seal (300; 500; 700; 900; 1100), according to any one of the preceding claims, in which the joining part (304; 1104) is configured to extend perpendicular to the main part (301), in projection in the main plane (P).

4. Peripheral seal (300; 500; 700; 900; 1100) according to any one of the preceding claims, in which the end portion (306) is configured to extend perpendicular to the main portion (301), in projection in the main plane (P).

5. Peripheral joint (300; 500; 700; 1100) according to any one of the preceding claims, in which at least one part, among the end part (306; 506), the intermediate part (305; 1105) and the joining part (304; 704; 1104), is configured to be rectilinear, in projection in the main plane (P).

6. Peripheral seal (900), according to any one of the preceding claims, in which a portion of the fin (902) is configured to be curved, in projection in the main plane (P).

7. Peripheral seal (1100) according to any one of the preceding claims, in which the joining part (1104) comprises an opening (1105) allowing circulation of fluid through the fin (1102).

8. Peripheral seal (300; 500; 700; 900; 1100) according to any one of the preceding claims, in which the main part (301) of the peripheral seal (300; 500; 700; 900; 1100) and the fin (302; 502; 702; 902; 1102) are formed in one piece.

9. Peripheral seal (300) according to any one of the preceding claims, further comprising a dam (310) which is parallel to the main part (301), which connects the end parts (306) of several fins (302), the dam (310) being formed in one piece with the first peripheral seal (300), and which is configured to be interposed according to the stacking direction (X) between the gas diffusion layer (205) and the polar plate (100).

10. Cell (2), for a fuel cell, comprising the polar plate (100) and a peripheral seal (300; 500; 700; 900; 1100) according to any one of the preceding claims, the polar plate (100) comprising: • the peripheral zone (102), and • the circulation field (103) of the reactive fluid, surrounded by the peripheral zone (102).

11. Cell (2), according to claim 10, further comprising: • the membrane-electrode assembly (200), extending parallel to the main plane (P) of the cell (2), superimposed on the first polar plate (100) in the stacking direction (X), and comprising: ♦ the peripheral portion (202; 402), opposite the peripheral zone (102) in the stacking direction (X), ♦ a central portion (203) comprising a proton exchange polymer membrane (204), framed by the peripheral portion (202; 402), and ♦ said at least one gas diffusion layer (205) interposed, in the stacking direction (X), between the proton exchange polymer membrane (204) and the polar plate (100), the peripheral seal (300; 500; 700; 900; 1100) ensuring a seal against the reactive fluid between, on the one hand, a bypass zone (50) of the cell (2) delimited inside the cell (2), between the peripheral portion (202; 402) of the membrane-electrode assembly (200) and the peripheral zone (102), and, on the other hand, an external zone (3) to the cell (2) beyond the main part (301) with respect to the bypass zone (50), and said at least one fin extending into the bypass zone.

12. Cell (2) according to claim 11, in which a contact portion (307; 507; 907) of the end part (306; 506; 906) is compressed between the gas diffusion layer (205) and the peripheral zone (102).

13. Cell (2) according to any one of claims 10 to 12, in which the circulation field (103) delimits a plurality of channels (105), for the circulation of the reactive fluid, the channels (105) extending in a longitudinal direction (Y) perpendicular to the stacking direction (X), each channel (105) being delimited by: • a channel bottom (1051), belonging to the circulation field (103), and extending parallel to the longitudinal direction (Y), and • two channel teeth (1052), belonging to the circulation field (103), and extending parallel to the longitudinal direction (Y), the channel teeth (1052) being arranged on either side of the channel bottom (1051), projecting relative to the channel bottom (1051), each channel tooth (1052) being in contact with the gas diffusion layer (205) in the stacking direction (X).

14. Cell (2) according to claim 13 in which the channel teeth (1052) further project relative to the peripheral zone (102) in the stacking direction (X).

15. Fuel cell (1) comprising cells (2), at least one of said cells (2) being according to any one of claims 10 to 14, the cells (2) being stacked in the stacking direction (X), to constitute a stack.

Images