Plate and peripheral seal for a fuel cell, polar separator comprising such plate and seal, electrochemical cell comprising such a separator, associated stack and fuel cell

Abstract

The invention relates to a peripheral zone which comprises at least one plate through-hole (28a, 28b, 28c), an inner rim (31; 131), extending between the plate hole (28a, 28b, 28c) and the circulation field (23; 123), and an outer rim (32; 132). The inner and outer rims together define the plate hole (28a, 28b). The peripheral zone (21; 121) comprises at least one fin (38) integral with, projecting from and secant with the outer rim (32). The outer rim (32) receives an outer portion (43) of a peripheral seal (40) and the fin (38, 138; 238a, 238b) receives an extension (46) of the peripheral seal (40) when the peripheral seal (40) and the plate (13) are integrated with the fuel cell.

Description

[0001] TITLE: Plate and peripheral seal for a fuel cell, polar separator comprising such a plate and seal, electrochemical cell comprising such a separator, associated stack and fuel cell

[0002] The present invention relates to a plate for a fuel cell, a peripheral seal for a fuel cell, a polar separator comprising a plate and a peripheral seal for a fuel cell. The present invention also relates to an electrochemical cell comprising such a separator, a stack for a fuel cell comprising such an electrochemical cell and a fuel cell comprising such a stack.

[0003] Conventionally, a fuel cell plate is made using a metal plate with holes allowing the passage of the various fluids necessary for the operation of the cell, such as oxygen, hydrogen and a cooling fluid. These holes are generally arranged at the edge of the plate, across its width in order to maximize the active surface area of ​​the plate.

[0004] Conventionally, a multitude of these plates are stacked on top of each other to form cells, a plurality of cells then constituting the fuel cell.

[0005] However, when stacking the plates, it is possible that the edges of these plates, in particular the thin walls located around the holes, may become deformed, given the little material present and the thinness of the plates.

[0006] This can then lead to various battery malfunctions, such as fluid leaks or even short circuits.

[0007] In addition, these plates are generally equipped with a peripheral seal intended to ensure the sealing of fluids between the plates during stacking and around the orifices. EP3123545B1 describes for example an electrochemical cell comprising a bipolar plate on which a seal is arranged. The width of the seal is smaller for a part of the seal which is in a lateral region of the plate, in the vicinity of orifices forming fluid transport conduits, in comparison with the width of the seal in a central region of the plate.

[0008] Because the joint width is smaller in the lateral region, this part of the joint and / or the lateral region of the plate may become deformed or displaced when the plates are stacked. This results in poor stack stability and the risk of leakage of fluids circulating in the fuel cell, particularly in the orifices forming the fluid transport conduits.

[0009] The aim of the invention is then to propose a polar plate and a seal resolving these drawbacks and allowing good mechanical resistance of the plate and good mechanical stability of the peripheral seal, without reducing the active surface of the plate.

[0010] For this purpose, according to a first aspect, the invention relates to a plate, for a fuel cell, the plate extending along a plate plane, the plate comprising: a circulation field, for guiding a circulation of a functional fluid; and a peripheral zone, which surrounds the circulation field and which comprises: o at least one plate orifice, passing through the plate perpendicular to the plate plane, o an internal rim, extending between the plate orifice and the circulation field, and o an external rim, the internal rim and the external rim together delimiting the plate orifice.

[0011] According to the invention, the peripheral zone comprises at least one fin integral with the external rim and projecting from the external rim while intersecting said external rim along the plate plane, the external rim being designed to receive an external portion of a peripheral seal and said fin being designed to receive an extension of the peripheral seal when the peripheral seal and the plate are integrated into the fuel cell.

[0012] Thanks to the invention, the mechanical stability of the plate is increased. The fin reduces the risk of deformation of the plate, by allowing a better distribution of forces, particularly on the external edge during stacking and compression of the plates. In addition, the extension also limits deformation of the peripheral joint. The extension notably limits the risk of twisting or transverse displacement of the external part, by forming a support point for the external part.

[0013] This results in a reduction or even elimination of any risk of leakage or short circuit and therefore greater reliability of the fuel cell, while avoiding a reduction in the active surface area of ​​the plate, in particular the circulation field. Thanks to the invention, it is possible to reduce the risk of leakage or short circuit, without excessively reducing the cross-section of the orifice. Thus, the impact of the presence of the extension and the fin on the overall efficiency of the fuel cell is limited. According to other advantageous aspects of the invention, the plate comprises one or more of the following characteristics, taken individually or in all technically possible combinations:

[0014] - The fin extends towards an interior of the plate hole.

[0015] - Only one fin is provided for the plate hole.

[0016] - The outer rim comprises two lateral parts and a central part, the two lateral parts each being connected to the inner rim, and being arranged on either side of the plate orifice, the central part connecting the lateral parts together, the fin being integral with the outer rim and projecting from the outer rim, being integral with, and extending from, the central part.

[0017] According to a second aspect, the invention also relates to a peripheral seal, for a fuel cell, the peripheral seal extending along a joint plane and being intended to be received on a plate as described previously, so that the joint plane and the plate plane are parallel, the peripheral seal comprising, along the joint plane:

[0018] - two longitudinal parts, configured to be received on the peripheral zone on either side of the circulation field; and

[0019] - a transverse portion connecting the two longitudinal portions, the transverse portion comprising an external portion configured to be received on the external rim; the peripheral seal forming a closed loop including the longitudinal portions and the transverse portion, said closed loop being configured to surround the circulation field by extending over the peripheral zone along a seal path parallel to the seal plane when the peripheral seal and the plate are integrated into the fuel cell.

[0020] According to the invention, the peripheral seal further comprises an extension, integral with the external part and projecting from the external part while intersecting the external part, the extension being configured to be received on the fin of the plate when the peripheral seal and the plate are integrated into the fuel cell.

[0021] According to other advantageous aspects of the invention, the seal comprises one or more of the following characteristics, taken individually or in all technically possible combinations:

[0022] - A width of the extension, measured along the joint path, is less than 30%, preferably less than 15%, advantageously less than 10%, of a length of the external part measured along the joint path. - The external part has a width, measured transversely to the joint path, which is constant, and the extension has a length, measured transversely to the joint path, which is greater than the width of the external part by a factor of 1.5, preferably by a factor of 2, more preferably by a factor of 5.

[0023] - The peripheral seal includes:

[0024] - an outer lip, which borders the external part continuously following the joint path;

[0025] - an inner lip, which comprises: o a main portion bordering the outer part continuously parallel to the outer lip and ending at the extension, and o an extension portion which extends the main portion by bordering the extension continuously, so that the inner lip locally deviates from the outer lip at the extension.

[0026] According to a third aspect, the invention also relates to a polar separator comprising: a plate as described above; a peripheral seal as described above, in contact with a first face of the plate, so that the closed loop formed by the peripheral seal surrounds the first circulation field, the external part being in contact with the external rim and the extension being in contact with the fin.

[0027] It is advantageous to form a polar separator with the invention, the seal being secured to the plate, for example overmolded onto the plate. The polar separator can then be handled independently and allow optimal assembly of the stack, thus avoiding leaks of functional fluids during operation of the fuel cell.

[0028] According to a fourth aspect, the invention also relates to an electrochemical cell comprising:

[0029] - at least one polar separator according to the preceding claim

[0030] - a membrane-electrode assembly, comprising: o a central portion comprising a membrane, a peripheral portion, surrounding the central portion, and o two gas diffusion layers, between which the membrane is interposed, the plate being stacked with the membrane-electrode assembly so that the circulation field bears against one of the two gas diffusion layers and so that the peripheral seal bears against the peripheral portion and surrounds the gas diffusion layer against which the circulation field bears.

[0031] Forming a cell including the above-mentioned polar separator is advantageous because this cell can be manipulated independently to form a stack of electrochemical cells. Thus, the fins and / or extensions can be easily aligned when compressing the cells.

[0032] According to a fifth aspect, the invention also relates to a stack for a fuel cell comprising at least one electrochemical cell according to the preceding claim and in which:

[0033] - the circulation field is a first circulation field formed on the first face of the plate;

[0034] - the peripheral seal is a first peripheral seal and the seal path is a first seal path; and

[0035] - the stack further comprises a second peripheral seal in contact with a second face of the plate, the second peripheral seal extending over the peripheral zone by forming a closed loop around a second circulation field formed on the second face, the second circulation field being surrounded by the peripheral zone, the second peripheral seal comprising: o an external part, in contact with the external rim and which extends over the external rim along a second seal path parallel to the plate plane, and o an extension, integral with the external part, in contact with and extending over the fin.

[0036] Forming a cell-based stack including fins and / or extensions makes it possible to increase the compression surface of the external part and, thus, to increase the rigidity of this external part, in order to limit its possible deformation, which could cause leaks of functional fluids.

[0037] According to a sixth aspect, the invention also relates to a fuel cell comprising a stack described above.

[0038] The invention will appear more clearly on reading the description which follows, given solely by way of non-limiting example, and made with reference to the drawings in which:

[0039] [Fig. 1] Figure 1 is a schematic perspective view of a fuel cell comprising plates according to the invention; [Fig. 2] Figure 2 is a top view of a polar separator, with in particular a cathode polar plate according to a first embodiment of the invention and a membrane-electrode assembly;

[0040] [Fig. 3] Figure 3 is a top view of a polar separator, with in particular an anode polar plate according to a first embodiment of the invention; [Fig. 4] Figure 4 is a detail of the cathode polar plate of Figure 2;

[0041] [Fig. 5] Figure 5 is a bottom view of a detail of the cathode pole plate of Figure 2;

[0042] [Fig. 6] Figure 6 shows on two inserts a) and b) two sections of the polar separator of Figures 1 and 2 respectively along lines IV-IV and VV; and

[0043] [Fig. 7] Figure 7 is a top view of a polar separator according to a second embodiment of the invention

[0044] In the present description, the term "polar separator" designates a polar plate (anode or cathode) equipped with a seal, so as to be able to integrate a bipolar plate, which can itself form a portion of a cell. By "bipolar plate" is meant a set of two polar separators assembled together, in this case an anodic polar plate, a cathodic polar plate, separated by at least one seal in accordance with the invention. The term cell, understood as electrochemical cell, designates an element capable of generating current following an electrochemical reaction. A cell comprises two polar separators separated from each other by a membrane electrode assembly. A membrane-electrode assembly comprises, in a known manner, a membrane coated with catalytic layer(s), a gas diffusion layer and a holding frame. Several cells form a stack of cells.This stack is generally held together by a compression system to form a fuel cell.

[0045] In Figure 1 a fuel cell 1 is shown. The fuel cell 1 is for example intended to be used in a motor vehicle, in particular an electric motor. The fuel cell 1 provides at least part and preferably all of the electrical energy supplying the electric motor of the motor vehicle.

[0046] The fuel cell 1 comprises a stack 5, comprising separator plates, here bipolar plates 12. Each bipolar plate 12 is formed by two associated polar plates. One of the polar plates is a plate 13, also called a cathode polar plate 13 and the other polar plate is a polar plate 113, also called an anodic polar plate 113. Each cathode polar plate 13, visible in FIG. 2, extends along a plate plane P, and each anodic polar plate 113, visible in FIG. 3, extends along a plate plane P', parallel to the plate plane P.

[0047] The two polar plates, cathode 13 and anodic 113, are assembled to each other in a sealed manner. The two associated polar plates 13 and 113, which form a single bipolar plate 12, are made of metal or graphite and are pressed against each other by a compressive force applied, in a stacking direction X, on the stack 5. They can also, as a variant, be welded or glued to each other. It is also possible to weld the two polar plates together in a localized manner, then for the applied compressive force to create the seal. The stacking direction X is orthogonal to the planes P of the cathode polar plates 13 and P' of the anodic polar plates 113.

[0048] The stack 1 comprises a plurality of cells 14 produced in the form of a stack of bipolar plates 12 stacked in the stacking direction X, a cell 14 comprising a cathode polar plate 13 belonging to a bipolar plate 12, and an anodic polar plate 113 of the following bipolar plate 12 in the stack 5. The stack 5, comprising several stacked bipolar plates 12, is thus made up of several individual cells 14 electrically connected in series. For each individual cell 14, the fuel cell 1 also comprises a membrane-electrode assembly 80, belonging to the stack 5, which is interposed between the two cathode 13 and anodic 113 polar plates associated with this cell 14. The membrane-electrode assembly 80 is also designated by MEA 80 (abbreviation of the expression "membraneelectrode assembly").Thus, the stack 5 comprises several stacked bipolar plates 12 and several stacked MEAs 80, one MEA 80 being stacked between two successive bipolar plates 12.

[0049] Each bipolar plate 12 is thus common to two neighboring cells 14.

[0050] The bipolar plates 12 and the MEAs 80 are stacked according to the stacking direction X.

[0051] We also define a longitudinal direction Y and a transverse direction Z, perpendicular to the stacking direction X.

[0052] The fuel cell 1 also comprises two end plates 16, which are arranged on either side of the stack 5. The stack 5 is sandwiched between the two end plates 16 and is compressed in the stacking direction X between the end plates 16. The end plates 16 are for example made of aluminum.

[0053] Advantageously, the fuel cell 1 also comprises two current collectors and insulating plates, not shown, the current collectors being arranged on either side of the stack in the stacking direction X, the insulating plates being arranged on either side of the stack 5 in the stacking direction X, interposed between the terminal plates 16 and the stack 5.

[0054] Alternatively, the end plates 16 are made of insulating material.

[0055] Each cathode polar plate 13 comprises a peripheral zone 21, a first and a second circulation field 23 also called active zone, and optionally, two first and two second homogenization zones 25.

[0056] The peripheral zone 21 extends around the entire circumference of the cathode polar plate 13, and borders the two circulation fields 23 and the four homogenization zones 25.

[0057] The peripheral zone 21 comprises at least one plate orifice 28, here six plate orifices 28a, 28b and 28c, internal rims 44 and external rims 32.

[0058] The plate orifices 28 are intended for the injection of functional fluid or for the evacuation of functional fluid. The plate orifices 28 have in the example of the figures a closed contour and pass through the cathode polar plate 13. Three plate orifices 28a, 28b and 28c are located on one side of the polar plate 13, aligned in the transverse direction Z, and three plate orifices 28a, 28b and 28c are located on the other side of the polar plate 13 in the longitudinal direction Y, also aligned in the transverse direction Z.In other words, in the case where the polar plate 13 is rectangular in shape, as illustrated, the plate orifices 28a, 28b and 28c, forming for example the fluid injection orifices, are aligned along the width of the plate, while the plate orifices 28a, 28b and 28c, forming for example the fluid discharge orifices, are also aligned along the width of the plate, on either side of the circulation fields 23. For each functional fluid, a plate orifice 28a, b or c forms a supply for this functional fluid, and a plate orifice 28a, b or c on the other side of the polar plate 13 forms an outlet for this functional fluid. The functional fluids are advantageously three in number and are for example air or oxygen, hydrogen and a cooling fluid.In the example of the figures, air flows through the orifices 28a, cooling fluid through the orifices 28b and hydrogen through the orifices 28c. Thus, one of the orifices 28a is an air supply orifice, and the other orifice 28a is an air discharge orifice. The same is true with the orifices 28b for the cooling fluid and 28c for the hydrogen.

[0059] The peripheral zone 21 here comprises six internal rims 31. Each internal rim 31 is associated with one of the plate orifices 28 and extends between the plate orifice 28 with which it is associated and the circulation field 23. Each internal rim 31 delimits a portion of the plate orifice 28 with which it is associated. The peripheral zone 21 comprises, in the example of the figures, six external rims 32. Each external rim 32 is associated with a plate orifice 28 and partially delimits it. Thus, each plate orifice 28 is delimited by the internal rim 31 and the external rim 32 which are associated with it. Each external rim 32 extends along an external rim trajectory R32, a length of the external rim 32 being measured along this trajectory.

[0060] Advantageously, and as shown in Figure 2, each external rim 32 comprises two lateral parts 34a and 34b and a central part 36. For each external rim 32, the two lateral parts 34a and 34b are arranged on either side of the plate orifice 28 with which the external rim 32 is associated in the transverse direction Z. For each external rim 32, the two lateral parts 34a and 34b are connected to the internal rim 31 and extend in the longitudinal direction Y. In the example of Figures 2 and 4, one or both lateral parts 34a and 34b associated with an orifice 28 can be confused with one of the lateral parts 34a or 34b associated with another orifice 28. This is the case, for example, of the lateral parts 34 which delimit the orifices 28b.For each orifice 28b, the lateral part 34a delimiting the orifice 28b is merged with the lateral part 34b delimiting the orifice 28a and the lateral part 34b delimiting the orifice 28b is merged with the lateral part 34a delimiting the orifice 28c.

[0061] According to the invention, the peripheral zone 21 further comprises at least one fin 38 and preferably a plurality of fins 38. By fin is meant a local (i.e. point-like) outgrowth of material, projecting from the external edge 32 in a direction D38, visible in FIG. 4, parallel to the plate plane P and intersecting the external edge 32 from which it projects. In other words, the continuity of the edge of the external rim 32 is interrupted punctually by the local and punctual protrusion formed by the fin 38. As shown in FIG. 2, the peripheral zone 21 comprises six fins 38, each fin 38 being associated with an orifice 28. In the example of FIGS. 2 and 4, a single fin 38 is associated with each orifice 28. Preferably, each of the fins 38 is solid, as can be seen in the figures.

[0062] The presence of a single fin 38 per orifice 28 makes it possible to limit the pressure loss induced by this fin inside a fluid flow gallery formed by all the orifices 28 of the successive bipolar plates 12. This makes it possible to limit the fluid disturbances suffered by the functional fluid circulating in said fluid flow gallery.

[0063] Each fin 38 is integral with the outer rim 32. In other words, each fin 38 is monolithic with the outer rim 32. In the example of Figures 2 to 4, each fin 38 is integral with the central portion 36 and extends approximately from a middle of the central portion 36.

[0064] Placing at least one fin 38 on a central part 36 is advantageous because the central part 36 is the furthest from the center of the plate 13; the mechanical strength of the central part 36 is more compromised by the thinness of this central part than the mechanical strength of the lateral parts 34a, 34b which are attached to the center of the plate 13.

[0065] The presence of at least one of these fins 38 makes it possible, thanks to the punctual addition of material to the peripheral zone 21, on the one hand to locally reinforce the latter without too much impact on its size on the other hand. Indeed, the addition of material locally and at a precise location selected by design, makes it possible to avoid any untimely deformation of the plate during stacking and compression of the plates. This results in a reduction or even elimination of the risk of leakage or short circuit and therefore greater reliability of the fuel cell.

[0066] Advantageously, the fins 38 extend from the outer rim 32 towards an interior of the plate orifice 28 with which each fin 38 is associated. This makes it possible in particular not to increase a total surface area occupied by the polar plate 13 and thus to minimize the overall size of the cathode polar plate 13 and therefore of the battery 1.

[0067] Advantageously, each fin 38 has a width £38, measured transversely to the outer rim 32 from which the fin 38 extends, less than or equal to 15% of the length of the outer rim 32 from which the fin 38 extends. In particular, each fin 38 has a width £38, measured transversely to the outer rim 32, less than or equal to 10% of the length of the outer rim 32 from which the fin 38 extends. Such dimensions are judiciously chosen to ensure the best possible compromise between mechanical strength of the cathode polar plate 13 in the area of ​​the orifices 28 and the size of the fin 38. In the case where the fin 38 extends towards the outside of the cathode polar plate 13, this makes it possible to minimize the size of the cathode polar plate 13. In the case where the fin 38 extends towards the inside of the orifice 28, this makes it possible to minimize the impact on the flow of the fluid inside the orifice 28.

[0068] The first circulation field 23 extends over a first face 13a of the cathode polar plate 13, the first face 13a being turned towards the membrane electrode assembly 80. The first circulation field 23 is configured to guide a circulation of a functional fluid in the longitudinal direction Y. In the example of FIG. 2, the first circulation field 23 is configured to guide air. The first circulation field 23 comprises channels 23a, extending substantially parallel to the longitudinal direction Y, and arranged next to each other in the transverse direction Z. The channels 23a are for example delimited by grooves hollowed out in the cathode polar plate 13, or by a stamping of the cathode polar plate 13.

[0069] The first homogenization zones 25 are arranged on either side of the first circulation field 23 in the longitudinal direction Y. One of the first homogenization zones 25 makes it possible to distribute functional fluid from one of the orifices 28 to the first circulation field 23, and the other first homogenization zone 25 makes it possible to evacuate the functional fluid distributed over the entire first circulation field 23 to another orifice 28, located opposite the cathode polar plate 13 in the longitudinal direction Y. More precisely, air circulates from one of the openings 28a in one of the first homogenization zones 25, in the first circulation field 23 in the longitudinal direction Y, in the other first homogenization zone 25 and is evacuated through the opening 28a on the other side of the cathode polar plate 13 along the longitudinal direction Y.

[0070] It is provided that only the openings 28a deliver and evacuate functional fluid, here air on the first face 13a of the cathode polar plate 13, while the contour of the openings 28b and 28c is sealed, so that the fluids passing through the openings 28b and 28c are not brought into contact with the air on the first face 13a of the cathode polar plate 13.

[0071] The second circulation field 23 and the second homogenization zones 25, visible in FIG. 5, extend over a second face 13b of the cathode polar plate 13, opposite the first face 13a in the stacking direction X. The second homogenization zones 25 are arranged on either side of the second circulation field in the longitudinal direction Y. The peripheral zone 21 surrounds the second homogenization zones 25 and the second circulation field 23. Cooling fluid circulates from one of the orifices 28b, through one of the second homogenization zones 25, then in the second circulation field 23, through the other second homogenization zone 25 and is discharged through the other orifice 28b.

[0072] Each individual cell 14 comprises a first peripheral seal 40 which extends along a joint plane P40. The first peripheral seal 40 is configured to be integrated into the cell 14, and thus, to be integrated into the fuel cell 1. When the first peripheral seal 40 and the cathode pole plate 13 are integrated into the fuel cell 1, the first peripheral seal 40 is received on the first face 13a, so as to be in contact with the first face 13a. The joint planes P40 and plate P are then parallel.

[0073] The first peripheral seal 40 comprises two longitudinal parts 41 which, when the first peripheral seal 40 is integrated into the fuel cell 1, are received on the peripheral zone 21 and extend in the longitudinal direction Y on either side of the circulation field 23 in a continuous manner.

[0074] The first peripheral joint 40 also comprises at least one, here two transverse parts 42, connected to each other by the longitudinal parts 41.

[0075] The first peripheral seal 40 forms a closed loop including the longitudinal parts 41 and the transverse parts 42 which, when the first peripheral seal 40 and the cathode pole plate 13 are integrated into the fuel cell 1, surrounds the circulation field 23 by extending over the peripheral zone 21 following a first seal trajectory T40, parallel to the seal plane P40.

[0076] The first peripheral seal 40 is sealed against functional fluids and is preferably made of elastomeric material. Thus, the first peripheral seal 40 ensures sealing of the functional fluids circulating through the orifices 28, to prevent them from mixing with each other, and ensures sealing between the cathode polar plate 13 and the exterior.

[0077] Each transverse portion 42 comprises several external portions 43 and several internal portions 44. As seen in Figures 2 and 4, each transverse portion comprises three external portions 43 and two internal portions 44.

[0078] The external parts 43 extend over the external rims 32, at a rate of one external part 43 per external rim 32. In the example of Figures 2 and 4, the first peripheral seal 40 comprises six external parts 43. Each external part 43 is thus associated with an orifice 28. Two external parts 43 associated with two different plate orifices 28 may be partially merged. This is for example the case for portions of the external parts 43 extending over lateral parts 34a and 34b, which are associated with the orifices 28b and merged respectively with the lateral parts 34b associated with the orifices 28a and 34a associated with the orifices 28c.

[0079] The inner portions 44 extend over the inner flanges 31 associated with the ports 28b and 28c and are attached to the outer portions 43 associated with the ports 28b and 28c respectively, in order to ensure that the ports 28b and 28c are sealed.

[0080] The first peripheral seal 40 further comprises at least one extension 46 and preferably a plurality of extensions 46. By extension, we mean a local protrusion of material, projecting from the first peripheral seal 40 in a direction D46 intersecting the first peripheral seal 40, parallel to the joint plane P40.

[0081] Each extension 46 extends parallel to the joint plane P40 and is integral with the first peripheral joint 40. In other words, each extension 46 is monolithic with the first peripheral joint 40. In the example of the figures, each extension 46 is integral with the external part 43. The presence of at least one of these extensions 46 makes it possible, thanks to the punctual addition of material to the first peripheral joint 40, on the one hand to locally reinforce the latter, without too much impact on its size on the other hand. Indeed, the addition of material locally and at a precise location selected by design, makes it possible to avoid any untimely deformation or any untimely movement of the first peripheral joint 40 during the stacking and compression of the electrochemical cells 14. This results in a reduction or even elimination of any risk of leakage or short circuit and therefore greater reliability of the fuel cell 1.

[0082] In the example of figures 2 and 4, the first peripheral seal 40 comprises six extensions 46. Each extension 46 is integral with one of the external parts 43, at a rate of one extension 46 per external part 43. Thus, each extension 46 is associated with the same orifice 28 as that with which the external part 43 with which the extension 46 is integral is associated.

[0083] Each extension 46 extends over the peripheral zone 21, in the direction D46, which is here perpendicular to the first joint trajectory T40, at the height of the extension 46 and parallel to the joint plane P40. In particular, in the example of FIGS. 2 and 4, each extension 46 extends over the fin 38 associated with the same plate orifice 28 as it. Each extension 46 therefore extends from the external part 43 towards the inside of the orifice 28 with which it is associated.

[0084] When the first peripheral seal 40 and the cathode polar plate 13 are integrated into the fuel cell 1, the directions D38 and D46 are advantageously aligned along the stacking direction X, or in other words, are coplanar in a plane perpendicular to the planes P and P40.

[0085] Advantageously, for each extension 46, a width £46 of the extension 46, measured along the first joint trajectory T40, is less than 30%, preferably less than 15%, advantageously less than 10% of a length of the external part 43 with which it is made of material, the length L43 of the external part 43 being measured along the first joint trajectory T40. Advantageously, the width £46 of the extension 46 is between 3% and 8% of the length L43 of the external part 43 with which it is made of material.

[0086] This makes it possible to limit a surface area occupied by the external part 43 on the peripheral zone 21 while ensuring a length of the extension 46 sufficient to limit an untimely movement or deformation of the first peripheral seal 40 during the stacking and compression of the electrochemical cells 14. More generally, this makes it possible to mechanically stabilize the first peripheral seal 40. In the example of FIGS. 2 and 4, this also makes it possible to limit a reduction in the section of the plate orifices 28, measured along the plate plane P.

[0087] Advantageously, each outer portion 43 has a width £43, measured transversely to the first joint path T40, which is constant. In addition, for each extension 46, a length L46 of the extension 46 measured transversely to the first joint path T40 is greater than the width £43 of the outer portion 43 by a factor of 1.5, preferably by a factor of 2, more preferably by a factor of 5.

[0088] This also makes it possible to limit a surface area occupied by the external part 43 on the peripheral zone 21 while ensuring a surface area of ​​the extension 46 sufficient to limit an untimely movement or deformation of the first peripheral seal 40 during the stacking and compression of the electrochemical cells 14. More generally, this makes it possible to mechanically stabilize the first peripheral seal 40. In the example of FIGS. 2 and 4, this also makes it possible to limit a reduction in the section of the plate orifices 28, measured along the plate plane P.

[0089] Combining these two characteristics of length L46 and width £46 makes it possible to define an ideal surface for the extension 46, thus making it possible to optimally stabilize the joint 40 at the time of compression of the stack 5. It is thus possible to adjust the additional compression surface for the plate 13.

[0090] More precisely, it is mainly the length L46 which makes it possible to optimally stabilize the seal 40 at the time of compression of the stack 5. The width £46 is advantageously chosen accordingly in order to give a rounded trajectory to the extension portion 56 as well as a rounded shape to the fin 38, this shape minimizing the impact of the fin 38 on the flow of the fluid in the plate orifice 28.

[0091] In the example of figures 2 and 4, the first peripheral seal 40 is a so-called lip seal, that is to say that the first peripheral seal 40 comprises lips which delimit it, transversely to the first seal trajectory T40, the first peripheral seal 40 being of greater thickness than the rest of the first peripheral seal 40, said thickness being measured at the lips in the stacking direction X. As such, the first peripheral seal 40 comprises an outer lip 51 and inner lips 53.

[0092] The outer lip 51, clearly visible in Figure 4, is continuous and continuously borders at least one outer portion 43 along the first seal path T40. In the example of Figures 2 and 4, the outer lip 51 continuously borders each outer portion 43 and each longitudinal portion 41. In the example of Figures 2 and 4, the first peripheral seal 40 comprises six inner lips 53, each associated with a plate orifice 28.

[0093] Each inner lip 53 comprises a main portion 55 and an extension portion 56. The main portion 55 continuously borders the outer portion 43 associated with the same plate orifice 28 as it, parallel to the outer lip 51 and also borders the inner portion 44 associated with the same plate orifice 28 as it. The main portion 55 ends at the extension 46 associated with the same plate orifice 28. The extension portion 56 extends the main portion 55 and borders the extension 46 continuously. Thus, the inner lip 53 locally deviates from the outer lip 51 at the extension 46, to border the extension 46. In other words, the distance between the inner 53 and outer 51 lips is substantially constant over the entire first peripheral seal 40, except at the extension 46 where it is higher.

[0094] Spacing the inner 53 and outer 51 lips at the extension 46 makes it possible to compress the entire extension 46 and thus avoid possible twisting of the fin 38 receiving the extension 46.

[0095] The first peripheral seal 40 also comprises secondary lips 58. The secondary lips 58 continuously border the longitudinal portions 41 and the internal portions 44 and each lip 58 is integral with one of the main portions 55 associated with the plate orifices 28a.

[0096] In a variant not shown, the first peripheral seal does not include lips and is said to be flat.

[0097] As seen in Figures 5 and 6, the cathode polar plate 13 comprises a second peripheral seal 60 which extends along a seal plane P60.

[0098] The second peripheral seal 60 is configured to be integrated into the cell 14, and thus, to be integrated into the fuel cell 1. When the second peripheral seal 60 and the cathode polar plate 13 are integrated into the fuel cell 1, the second peripheral seal 60 is received on the second face 13b, so as to be in contact with the second face 13b. The joint planes P60 and plate P are then parallel.

[0099] In a similar manner to what has been described for the first peripheral seal 40, the second peripheral seal 60 comprises two longitudinal parts 61 which, when the second peripheral seal 60 is integrated into the fuel cell 1, are received on the peripheral zone 21 and extend in the longitudinal direction Y on either side of the circulation field 23 in a continuous manner.

[0100] The second peripheral seal 60 comprises at least one, here two transverse parts 62, connected to each other by the longitudinal parts 61. The second peripheral seal 60 forms a closed loop including the longitudinal parts 61 and the transverse parts 62 which, when the second peripheral seal 60 and the cathode pole plate 13 are integrated into the fuel cell 1, surrounds the circulation field 23 by extending over the peripheral zone 21 following a second seal trajectory T60, parallel to the seal plane P60.

[0101] The second peripheral seal 60 is sealed against functional fluids and is preferably made of elastomeric material.

[0102] Similar to the first peripheral seal 40, each transverse portion 62 comprises several external portions 63 and several internal portions 64. As seen in Figure 5, each transverse portion comprises three external portions 63 and two internal portions 64.

[0103] The external parts 63 extend over the external rims 32, at a rate of one external part 63 per external rim 32, each external part 63 is thus associated with an orifice 28. In a manner similar to what has been described for the first peripheral seal 40, two external parts 63 associated with two different plate orifices 28 can be partially merged.

[0104] The inner portions 64 extend over the inner flanges 31 associated with the ports 28b and 28c and are attached to the outer portions 63 associated with the ports 28b and 28c respectively, in order to ensure that the ports 28b and 28c are sealed.

[0105] In a similar manner to what has been described for the first peripheral seal 40, the second peripheral seal 60 further comprises six extensions 66, visible in FIGS. 5 and 6. Each extension 66 is integral with one of the external parts 63, at a rate of one extension 66 per external part 63. Thus, each extension 66 is associated with the same orifice 28 as that with which the external part 63 with which the extension 66 is integral is associated.

[0106] Each extension 66 extends locally over the peripheral zone 21, projecting from the second peripheral seal 60 in a direction D66 which is intersecting with the second peripheral seal 60, parallel to the joint plane P60. In the example of the figures, each extension 66 projects perpendicularly to the second joint trajectory T60 at the height of the extension 66 and parallel to the joint plane P60. In particular, in the example of FIG. 5, each extension 66 extends over the fin 38 associated with the same plate orifice 28 as it. Each extension 66 therefore extends from the external part 63 associated with the same plate orifice 28 as it, towards the inside of the orifice 28 with which it is associated.When the second peripheral seal 60 and the cathode polar plate 13 are integrated into the fuel cell 1, the directions D38 and D66 are advantageously aligned along the stacking direction X, or in other words, are coplanar in a plane perpendicular to the planes P and P60.

[0107] The presence of at least one of these extensions 66 makes it possible, thanks to the occasional addition of material to the second peripheral seal 60, to locally reinforce the latter without having too much of an impact on its size.

[0108] In a variant not shown, the peripheral zone does not include a fin and the extension then extends over the peripheral zone, advantageously over the external rim.

[0109] Advantageously, for each extension 66, a width £66 of the extension 66, measured along the second joint trajectory T60, is less than 30%, preferably less than 30%, advantageously less than 10% of a length of the external part 63 with which it is made of material, the length of the external part 63 being measured along the second joint trajectory T60. Advantageously, the width £66 of each extension 66 is between 3% and 8% of the length L63 of the external part 63 with which it is made of material.

[0110] Similar to what has been described for the external portions 43 of the first peripheral seal 40, advantageously, each external portion 63 has a width £63, measured transversely to the second seal path T60, which is constant. In addition, for each extension 66, a length L66 of the extension 66 measured transversely to the second seal path T60 is greater than the width £63 of the external portion 63 by a factor of 1.5, preferably by a factor of 2, more preferably by a factor of 5.

[0111] Preferably, and as shown in Figure 6, the extensions 46 and 66 are superimposed relative to each other along the stacking axis X, thus forming a pillar parallel to the stacking direction X. This makes it possible in particular to improve the mechanical stability of the external edges 32 of the cathode polar plates 13, when they are stacked in the stack 5. This alignment of the extensions 46 and 66 makes it possible to create an additional zone where the compression of the stack 5 is identical to the rest of the compression undergone by the polar plate 13, in a manner advantageous compared to the prior art.

[0112] As shown in Figure 6, the second peripheral seal 60 is a so-called lip seal, that is to say that the second peripheral seal 60 comprises lips which delimit it, transversely to the longitudinal direction of the seal, the second peripheral seal 60 being of greater thickness than the rest of the second peripheral seal 60, said thickness being measured at the lips in the stacking direction X. As such, the second peripheral seal 60 comprises an outer lip 71 and six inner lips 73, one of the inner lips 73 being visible in Figure 6. Each inner lip 73 is associated with a plate orifice 28.

[0113] The outer lip 71 is continuous and continuously borders at least one outer portion 63 along the second seal path T60. Advantageously, the outer lip 71 continuously borders each outer portion 63 and each longitudinal portion 61.

[0114] Each inner lip 73 comprises a main portion 75, visible in insert a) of Figure 6 and an extension portion 76, visible in insert b) of Figure 6. The main portion 75 continuously borders the external part 63 associated with the same plate orifice 28 as it, parallel to the outer lip 71 and also borders the internal part 64 associated with the same plate orifice 28 as it. The main portion 75 ends at the extension 66 associated with the same plate orifice 28, and the extension portion 76 extends the main portion 75 and borders the extension 66 continuously. Thus, the inner lip 73 locally deviates from the outer lip 71 at the extension 66, to border the extension 66.

[0115] The second peripheral seal 60 also comprises secondary lips 78 which continuously border the longitudinal parts 41 and the internal parts 44. Each secondary lip 78 is integral with one of the main portions 75 associated with the plate orifices 28b.

[0116] In a variant not shown, the second peripheral seal does not include lips and is said to be flat.

[0117] In a variant not shown, the cathode polar plate comprises only one plate orifice, one internal rim and one external rim. In this case, the peripheral seal comprises only one external part.

[0118] In a variant not shown, the cathode polar plate does not include homogenization zones and the functional fluid circulates from the orifices directly into the circulation field.

[0119] In a variant not shown, several fins and / or several extensions are provided for the same plate orifice. In this case, it is possible that some or all of the fins and / or extensions extend towards the inside of the plate orifice.

[0120] In a variant not shown, at least one of the plate holes is not associated with any fin and / or at least one of the plate holes is not associated with any extension.

[0121] In a variant not shown, at least one of the fins extends away from the plate orifices, thereby increasing a total surface area of ​​the cathode pole plate, measured parallel to the plate plane. The anodic pole plate 113 is similar to the cathode pole plate 13. Each anodic pole plate 113 includes a peripheral zone 121, similar to the peripheral zone 21. The anodic pole plate 113 also includes a first circulation field 123, and optionally, two first homogenization zones 125.

[0122] The peripheral zone 121 comprises at least one plate orifice 128, here six plate orifices 128a, 128b and 128c, internal rims 131 and external rims 132, similar to the plate orifices 28, to the internal rims 31 and external rims 32. The plate orifices 128 pass through the anode polar plate 113 and are opposite in the stacking direction X the plate orifices 28 of the cathode polar plate 13 belonging to the same bipolar plate 12 as the anode plate 113. Each external rim 132 extends along an external rim trajectory R132, a length of the external rim 132 being measured along this trajectory.

[0123] Each outer rim 132 comprises two side portions 134a and 134b and a central portion 136, similar to the side portions 34a, 34b and the central portion 36.

[0124] Advantageously, the peripheral zone 121 further comprises at least one fin 138 and preferably a plurality of fins 138, similar to the fins 38, locally projecting from the external rim 132 in a direction D138 parallel to the plate plane P, said direction being secant to the external rim 32 from which the fins 138 project. In the example of FIG. 3, the peripheral zone 121 comprises six fins 138, each fin being associated with an orifice 128. As shown in FIG. 3, a single fin 138 is associated with an orifice 128.

[0125] Each fin 138 is integral with the outer rim 132. In other words, each fin 138 is monolithic with the outer rim 132.

[0126] The presence of at least one of these fins 138 makes it possible, thanks to the specific material added to the peripheral zone 121, to locally reinforce the latter without having too much impact on its size.

[0127] Advantageously, and similarly to what has been described for the fins 38, each fin 138 has a width, measured transversely to the outer rim, less than 15% of the length of the outer rim 132 from which the fin 138 extends. In particular, each fin 138 has a width, measured transversely to the outer rim, less than or equal to 10% of the length of the outer rim 132 from which the fin 138 extends. Such dimensions are judiciously chosen to ensure the best possible compromise between mechanical strength of the anode polar plate 113 in the area of ​​the orifices 128 and size of the fin 138. The first circulation field 123 extends over a first face 113a of the anode polar plate 113 facing towards the membrane electrode assembly 80 and visible in FIG. 3. The first circulation field 123 is configured to guide a circulation of a functional fluid in the longitudinal direction Y.In the example of Figure 3, the first circulation field 123 is configured to guide hydrogen. The first circulation field 123 comprises channels 123a, extending substantially parallel to the longitudinal direction Y, and arranged next to each other in the transverse direction Z. The channels 123a are for example delimited by grooves hollowed out in the anode polar plate 113, or by a stamping of the anode polar plate 113.

[0128] The first homogenization zones 125 are arranged on either side of the first circulation field 123 in the longitudinal direction Y. One of the first homogenization zones 125 makes it possible to distribute functional fluid from one of the orifices 128 to the first circulation field 123, and a second homogenization zone 125 makes it possible to evacuate the functional fluid distributed over the entire first circulation field 123 to another orifice 128, located opposite the anode polar plate 113 in the longitudinal direction Y. More precisely, hydrogen circulates from one of the openings 128c in one of the first homogenization zones 125, in the circulation field 123 in the longitudinal direction Y, in the other first homogenization zone 125 and is evacuated through the other opening 128c of the other side of the anode polar plate 113 in the longitudinal direction Y.

[0129] It is provided that only the openings 128c deliver and discharge functional fluid, here hydrogen, onto the first face 113a of the anode polar plate 113, while the contour of the openings 128a and 128b is tightly closed, so that the fluids passing through the openings 128a and 128b are not brought into contact with the hydrogen on the first face 113a of the anode polar plate 113.

[0130] The anode polar plate 113 also comprises a second circulation field and second homogenization zones, not shown in the figures, which extend over a second face 113b of the anode polar plate 113, opposite the first face 113a in the stacking direction X. The second homogenization zones are arranged on either side of the second circulation field in the longitudinal direction Y. The peripheral zone 121 surrounds the second homogenization zones and the second circulation field. Cooling fluid circulates from one of the orifices 128b, through one of the second homogenization zones, then into the second circulation field, through the other second homogenization zone and is discharged through the other orifice 128b.Thus, between two polar plates 13 and 113 belonging to the same bipolar plate 12, cooling fluid circulates from one of the openings 28b and 128b opposite each other in the stacking direction X, between the second circulation fields of the polar plates 13 and 113, and is discharged through the openings 28b and 128b opposite each other in the stacking direction X, on the other side of the polar plates 13 in the longitudinal direction Y. The other openings 28a, 128a, 28c and 128c are tightly closed with respect to the circulation field, so that no reactive fluid can be admitted into the second circulation fields of the polar plates 13 and 113.

[0131] Each individual cell 14 comprises a peripheral seal 140 which extends along a joint plane P140.

[0132] When the peripheral seal 140 and the anode polar plate 113 are integrated into the fuel cell 1, the peripheral seal 140 is received on the first face 113a, so as to be in contact with the first face 113a. The joint planes P140 and plate P' are then parallel.

[0133] The peripheral seal 140 comprises two longitudinal parts 141 functionally similar to the longitudinal parts 41. When the peripheral seal 140 is integrated into the fuel cell 1, the longitudinal parts 141 are received on the peripheral zone 121 and extend in the longitudinal direction Y on either side of the circulation field 123 in a continuous manner.

[0134] The peripheral joint 140 comprises at least one, here two transverse parts 142, similar at least functionally to the transverse parts 42 connected to each other by the longitudinal parts 141.

[0135] The peripheral seal 140 forms a closed loop including the longitudinal parts 141 and the transverse parts 142 which, when the peripheral seal 140 and the anode pole plate 113 are integrated into the fuel cell 1, surrounds the circulation field 123 by extending over the peripheral zone 121 following a seal trajectory T140, parallel to the seal plane P140.

[0136] Each transverse portion 142 comprises several external portions 143 and several internal portions 144, similar respectively to the external portions 43 and the internal portions 44.

[0137] The peripheral seal 140 further comprises at least one extension 146 and preferably a plurality of extensions 146. As shown in FIG. 3, the peripheral seal 140 comprises six extensions 146. The extensions 146 are similar to the extensions 46. In particular, each extension 146 projects from the peripheral seal 140 in a direction D146 intersecting the peripheral seal 140, parallel to the joint plane P140, and is integral with one of the external parts 143, at a rate of one extension 146 per external part 143. In the example of FIG. 3, each extension 146 extends over the peripheral zone 121, perpendicular to the joint path T140 at the height of the extension 146. Thus, each extension 146 is associated with the same orifice 128 as that with which the external part 143 with which it is integral is associated.

[0138] In particular, as shown in Figure 3, each extension 146 extends over the fin 138 associated with the same plate orifice 128. Each extension 146 therefore extends from the respective outer portion 143 towards the inside of the orifice 128 with which it is associated.

[0139] When the peripheral seal 140 and the anode polar plate 113 are integrated into the fuel cell 1, the directions D138 and D146 are advantageously aligned along the stacking direction X, or in other words, are coplanar in a plane perpendicular to the planes P and P140.

[0140] Advantageously, for each extension 146, a width £146 of the extension 146, measured along the joint trajectory T140, is less than 10% of a length L143 of the external part 143 with which it is made of material, the length L143 of the external part 143 being measured along the joint trajectory T140. Advantageously, the width £146 of the extension 146 is between 3% and 8% of the length L143 of the external part 143 with which it is made of material.

[0141] Advantageously, each outer portion 143 has a width £143, measured transversely to the joint path T140, which is constant. In addition, for each extension 146, a length L146 of the extension 146 measured transversely to the joint path T140 is greater than the width £143 of the outer portion 43 by a factor of 1.25, preferably by a factor of 1.5, more preferably by a factor of 2.

[0142] In the same way as for the cathode polar plate 13, the width £146 and the length L146 of the extensions 146 makes it possible to limit a surface occupied by the external part 143 on the peripheral zone 121 while ensuring a length of the extensions 146 sufficient to limit an untimely movement or deformation of the peripheral seal 140 during the stacking and compression of the electrochemical cells 14. In the example of FIG. 3, this also makes it possible to limit a reduction in the section of the plate orifices 128, measured along the plate plane P'.

[0143] As shown in Figure 6, the peripheral seal 140 is a flat seal.

[0144] Alternatively, the peripheral seal 140 is a lip seal, and then comprises lips similar, at least functionally, to the outer 51, inner 53 and secondary 58 lips. In a particularly advantageous manner, and as shown in FIG. 6, in the stack 5, the cathode polar plate 13 comprises two peripheral seals 40 and 60 which are lip seals, and the anodic polar plate 113 comprises a flat peripheral seal 140.

[0145] Each anode polar plate 113 bears against the cathode plate 13 belonging to the same bipolar plate 12 in the stacking direction X. In particular, the anode polar plate 113 bears against the outer 71 and inner 73 lips of the second peripheral seal 60, ensuring a seal between the bipolar plate 12 and the exterior. In particular, the cooling fluid circulating between the polar plates 13 and 113 of the same bipolar plate cannot escape.

[0146] In variants not shown, the anode pole plate comprises two peripheral lip seals and the cathode pole plate comprises a single flat peripheral seal. Other combinations of lip seals and flat seals carried by either the anode or cathode pole plates are also possible as variants.

[0147] The membrane-electrode assembly 80, or MEA 80, comprises a central portion 81 and a peripheral portion 82, surrounding the central portion 81.

[0148] The central portion 81 comprises a membrane 83, visible in dotted lines in Figure 2. The membrane 83 is a proton exchange polymer membrane. The membrane 83 extends parallel to the plate planes P and P', and faces the circulation fields 23 and 123 in the stacking direction X.

[0149] The MEA 80 advantageously comprises a holding frame 84, which supports the membrane 83. In this case, the holding frame 84 comprises a central opening delimiting the central portion 81, and the remainder of the holding frame delimits the peripheral portion 82. The holding frame 84 also comprises orifices 85a, 85b and 85c corresponding to orifices for supplying and discharging functional fluids. Each orifice 85a is opposite one of the plate orifices 28a and one of the plate orifices 128a in the stacking direction X and extends these plate orifices 28a and 128a in the stacking direction X. The same is true for the orifices 85b and 85c. In the example of the figures, the orifices 85 have the same shape as the orifices 28 and 128. The orifices 28, 128 and 85 thus form six galleries in the stack 5, in which the functional fluids circulate, supplying and evacuating the fluids circulating in each cell 14.

[0150] Alternatively, the membrane 83 forms both the central portion 81 and the peripheral portion 82 and the MEA 80 does not include a holding frame. The MEA 80 also includes two gas diffusion layers 86, one of the gas diffusion layers 86 being visible in FIG. 2, which are arranged on either side of the membrane 83 in the stacking direction X.

[0151] As mentioned previously, the MEA 80 is interposed between a cathode polar plate 13 and an anodic polar plate 113 in the stacking direction X.

[0152] More specifically, one of the gas diffusion layers 86 is in contact with both the membrane 83 and the circulation field 23, and the other gas diffusion layer 86 is in contact with both the membrane 83 and the circulation field 123 along the stacking direction X. Thus, the functional fluids circulating in the circulation fields 23 and 123 are in contact with the gas diffusion layers 86 and can diffuse through the latter to the membrane 83, to react with each other.

[0153] As can be seen in Figure 6, the first peripheral seal 40 and the peripheral seal 140 bear against the holding frame 84 in the stacking direction X. In particular, the outer lip 71 and the extension portion 76 bear against the holding frame 84 in the stacking direction X and the extension 146 bears against the holding frame 84 in the stacking direction X, ensuring the sealing of the cell 14 with the outside.

[0154] In Figure 7, a cathode pole plate 213 is shown as an alternative embodiment to the cathode pole plate 13. The elements of the pole plate 213 which are identical to those of the cathode pole plate 13 are designated by the same reference numerals and are not described in detail again.

[0155] The cathode polar plate 213 differs from the cathode polar plate 13 by its fins 238.

[0156] The cathode polar plate 213 comprises fins 238a, identical to the fins 38, and fins 238b which differ from the fins 38. Each fin 238b is associated with an orifice, here the orifices 28b. Each fin 238b projects from the external rim 32 in a direction D38 parallel to the plate plane P and intersecting the external rim 32, here intersecting the lateral parts 34. Each fin 238b is integral with the external rim 32. In this embodiment, each fin 238b is integral with a lateral part 34, one with a lateral part 34a and the other with a lateral part 34b.

[0157] Advantageously, the fins 238b extend from the outer rim 32 towards an interior of the plate orifice 28 with which each fin 238b is associated. This makes it possible in particular not to increase a total surface area occupied by the polar plate 13. Advantageously, each fin 238b has a width, measured transversely to the outer rim, less than 15% of the length of the outer rim 32 from which the fin 238b extends. In particular, each fin 238b has a width, measured transversely to the outer rim, less than or equal to 10% of the length of the outer rim 32 from which the fin 238b extends.

[0158] The extensions 46 thus extend over the fins 238a and 238b, in a manner similar to that described previously.

[0159] The use of both peripheral lip seals and flat peripheral seals is particularly advantageous because it allows good mechanical stability of the stack 5 while limiting the compressive forces to be applied to the stack 5 to ensure its sealing. Indeed, peripheral lip seals require greater precision in the alignment of the bipolar plates 12, so that the lips are aligned with each other in the stacking direction X. However, they deform more easily, which limits the compressive forces to be applied to the stack 5 to ensure sealing of the stack 5. Flat seals require greater compressive force but less precision during alignment. Thus, the use of both types of seals allows a compromise between acceptable tolerances for aligning the polar plates 13 and 113, and the compressive forces to be applied to the stack.

[0160] Any feature described for one embodiment or variation in the foregoing may be implemented for the other embodiments and variations described above, as long as technically feasible.

Claims

CLAIMS 1. Plate (12; 13; 113; 213), for a fuel cell (1), the plate (13; 113; 213) extending along a plate plane (P; P'), the plate (13; 113; 213) comprising: - a circulation field (23; 123), for guiding a circulation of a functional fluid; and - a peripheral zone (21; 121), which surrounds the traffic field (23; 123) and which comprises: o at least one plate orifice (28a, 28b, 28c; 128a, 128b, 128c), passing through the plate (13; 113; 213) perpendicular to the plate plane (P, P'), o an internal rim (31; 131), extending between the plate orifice (28a, 28b, 28c; 128a, 128b, 128c) and the circulation field (23; 123), and o an external rim (32; 132), the internal rim (31; 131) and the external rim (32; 132) together delimiting the plate orifice (28a, 28b, 28c; 128a, 128b, 128c); characterized in that the peripheral zone (21; 121) comprises at least one fin (38, 138; 238a, 238b) integral with the external rim (32; 132) and projecting from the external rim (32; 132) while intersecting said external rim (32) along the plate plane (P; P'), the external rim (32; 132) being designed to receive an external part (43; 63; 143) of a peripheral seal (40; 60; 140) and said fin (38, 138;238a, 238b) being adapted to receive an extension (46; 66; 146) of the peripheral seal (40; 60; 140) when the peripheral seal (40; 60; 140) and the plate (13; 113; 213) are integrated into the fuel cell (1).; 2. A plate (13, 113; 213) according to claim 1, wherein the fin (38, 138; 238a, 238b) extends towards an interior of the plate orifice (28a, 28b, 28c, 128a, 128b, 128c).

3. Plate (13, 113; 213) according to any one of claims 1 or 2, wherein a single fin (38, 138; 238a; 238b) is provided for the plate orifice (28a, 28b, 28c; 128a, 128b, 128c).

4. Plate (13; 113; 213) according to any one of the preceding claims, in which the external rim (32; 132) comprises two lateral parts (34a, 34b; 134a, 134b) and a central part (36; 136), the two lateral parts (34a, 34b; 134a, 134b) each being connected to the inner rim (31; 131), and being arranged on either side of the plate orifice (28a, 28b, 28c; 128a, 128b, 128c), the central portion (36; 136) connecting the lateral portions (34a, 34b; 134a, 134b) together, the fin (38, 138; 238a) being integral with the outer rim (32; 132) and projecting from the outer rim (32; 132), being integral with, and extending from, the central portion (36; 136).

5. Peripheral seal (40; 60; 140), for a fuel cell (1), the peripheral seal (40; 60; 140) extending along a joint plane (P40; P60; P140) and being intended to be received on a plate (13, 113; 213) according to any one of the preceding claims, so that the joint plane (P40; P60; P140) and the plate plane (P; P') are parallel, the peripheral seal (40; 60; 140) comprising, along the joint plane (P40; P60; P140): - two longitudinal parts (41; 61; 141), configured to be received on the peripheral zone (21; 121) on either side of the circulation field (23; 123); and - a transverse portion (42; 62; 142) connecting the two longitudinal portions (41; 61; 141), the transverse portion (42; 62; 142) comprising an external portion (43; 63; 143) configured to be received on the external rim (32; 132); the peripheral seal (40; 60; 140) forming a closed loop including the longitudinal parts (41; 61; 141) and the transverse part (42; 62; 142), said closed loop being configured to surround the circulation field (23; 123) by extending over the peripheral zone (21; 121) along a seal path (T40; T60; T140) parallel to the seal plane (P40; P60; P140) when the peripheral seal (40; 60; 140) and the plate (13; 113; 213) are integrated into the fuel cell (1), characterized in that the peripheral seal (40; 60; 140) further comprises an extension (46; 66; 146), integral with the external part (43; 63; 143) and projecting from the external part (43; 63;143) being secant to the external part (43; 63; 143), the extension (46; 66; 146) being configured to be received on the fin (38, 138; 238a; 238b) of the plate (13; 113; 213) when the peripheral seal (40; 60; 140) and the plate (13; 113; 213) are integrated into the fuel cell (1).; 6. Peripheral seal (40; 60; 140) according to claim 5, wherein a width (£46; £66; £46) of the extension (46; 66; 146), measured along the seal path (T40; T60; T140) is less than 30%, preferably less than 15%, advantageously less than 10%, of a length (L43; L63; L143) of the external part (43; 63; 143) measured along the joint trajectory (T40; T60; T140).

7. Peripheral seal (40; 60; 140) according to any one of claims 5 to 6, wherein the outer portion (43, 63, 143) has a width (£43, £63, £143), measured transversely to the seal path (T40, T60, T140), which is constant, and wherein the extension (46, 66, 146) has a length (L46, L66, L146), measured transversely to the seal path (T40, T60, T140), which is greater than the width (£43, £63, £143) of the outer portion (43, 63, 143) by a factor of 1.5, preferably by a factor of 2, more preferably by a factor of 5.

8. Peripheral seal (40; 60) according to any one of claims 5 to 7, comprising: - an outer lip (51; 71), which borders the external part (43; 63) continuously following the joint path (T40; T60; T 140); - an inner lip (53; 73), which comprises: o a main portion (55; 75) bordering the outer part (43; 63) continuously parallel to the outer lip (51; 71) and ending at the extension (46; 66), and o an extension portion (56; 76) which extends the main portion (55; 75) by bordering the extension (46; 66) continuously, so that the inner lip (53; 73) locally deviates from the outer lip (51; 71) at the extension (46; 66).

9. Polar separator comprising: - a plate (13; 113; 213) according to any one of claims 1 to 4; - a peripheral seal (40; 140) according to any one of the claims 5 to 8, in contact with a first face (13a; 113a) of the plate (13; 113; 213), so that the closed loop formed by the peripheral seal (40; 140) surrounds the first circulation field (23; 123), the external part (43; 143) being in contact with the external rim (32; 132) and the extension (46; 146) being in contact with the fin (38, 138; 238a; 238b).

10. Electrochemical cell comprising: - at least one polar separator according to the preceding claim - a membrane-electrode assembly (80), comprising: o a central portion (81) comprising a membrane (83), a peripheral portion (82), surrounding the central portion (81), and o two gas diffusion layers (86), between which the membrane (83) is interposed, the plate (13) being stacked with the membrane-electrode assembly (80) so that the circulation field (23; 123) bears against one of the two gas diffusion layers (86) and so that the peripheral seal (40; 140) bears against the peripheral portion (82) and surrounds the gas diffusion layer (86) against which the circulation field (23; 123) bears.

11. Stack (5) for a fuel cell (1) comprising at least one electrochemical cell according to the preceding claim and in which: - the circulation field (23) is a first circulation field (23) formed on the first face (13a) of the plate (13); - the peripheral seal (40) is a first peripheral seal (40) and the seal path (T40) is a first seal path (T40); and - the stack (5) further comprises a second peripheral seal (60) in contact with a second face (13b) of the plate (13), the second peripheral seal (60) extending over the peripheral zone (21) forming a closed loop around a second circulation field (23) formed on the second face (13b), the second circulation field (23) being surrounded by the peripheral zone (21), the second peripheral seal (60) comprising: o an external part (63), in contact with the external rim (32) and which extends over the external rim (32) along a second seal path (T60) parallel to the plate plane (P), and o an extension (66), integral with the external part (63), in contact with and extending over the fin (38; 238a; 238b).

12. Fuel cell (1) comprising a stack (5) according to the preceding claim.

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