Peripheral seal, polar separator comprising such a seal, electrochemical cell comprising such a separator, fuel cell comprising such an electrochemical cell, and vehicle comprising such a fuel cell

Abstract

The peripheral seal (40) further comprises an electrically insulating pad (43, 45, 47, 49) at specific points which is integral with the sealing portion (41), the pad (43, 45, 47, 49) projecting from the sealing portion (41) towards an exterior of the sealing portion (41), in a direction of extent parallel to the seal plane (P40), the pad (43, 45, 47, 49) being configured to be in contact with the first polar plate when the peripheral seal (40) is integrated in the electrochemical cell.

Description

[0001] TITLE: Peripheral seal, polar separator comprising such a seal, electrochemical cell comprising such a separator, fuel cell comprising such a cell and vehicle comprising such a cell

[0002] The present invention relates to a peripheral seal, a polar separator comprising such a peripheral seal, an electrochemical cell comprising such a polar separator, a fuel cell comprising a stack of such electrochemical cells and a vehicle comprising such a fuel cell.

[0003] Short circuits in electrochemical cells lead to a decrease in cell efficiency and can also damage these cells. As such, it is known to use short-circuit protection elements in an electrochemical cell. DE102021202538A1 describes an electrochemical cell comprising a bipolar plate consisting of two polar plates, the bipolar plate comprising an electrical socket for an electrical connector. An electrical insulation element is fixed near the electrical socket. The electrical insulation element may be attached to a seal arranged on the bipolar plate. The insulation element is intended to prevent a short circuit, caused by the electrical connector, which would be incorrectly positioned in the electrochemical cell, in particular which would not be positioned in the socket but between two successive bipolar plates, and which would touch these two bipolar plates.

[0004] However, short circuits in an electrochemical cell can be generated by other means than a poorly positioned electrical connector. In particular, the polar plates of an electrochemical cell can be accidentally brought into direct contact with each other, for example following an unintentional deformation of one of the polar plates. In particular, during the manufacture of the fuel cell, a step of stacking the polar plates on top of each other can lead to an accidental deformation of the plates, in particular locally at the level of notches in the polar plate receiving an alignment guide, guiding the plate for the stacking step. In other cases, corners of the polar plates are also likely to be deformed, for example following improper handling.These local deformations are likely to generate a short circuit directly between the polar plates of the electrochemical cell, since the deformed area of ​​the plate can come into contact with the subsequent plate in the stack. This results, under the effect of the currents generated by the cell, in very intense heating which is likely to instantly degrade several cells of the cell, or even the entire cell. The aim of the invention is then to propose a peripheral seal and / or a polar separator (i.e. a polar plate equipped with said seal) resolving these drawbacks, by making it possible to avoid a short circuit between two consecutive polar plates.

[0005] For this purpose, according to a first aspect, the invention relates to a peripheral seal for an electrochemical cell, the peripheral seal extending along a joint plane and comprising a sealing portion forming a closed loop parallel to the joint plane and configured to be in contact with a first polar plate of the electrochemical cell when the peripheral seal is integrated into the electrochemical cell. According to the invention, the peripheral seal further comprises at least one electrically insulating, punctual pad, integral with the sealing portion, the pad projecting from the sealing portion towards an outside of the sealing portion, in an extension direction parallel to the joint plane, the pad being configured to be in contact with the first polar plate when the peripheral seal is integrated into the electrochemical cell.

[0006] Thanks to the invention, when the peripheral seal is integrated into the electrochemical cell, the pad prevents the first polar plate and a second polar plate, arranged parallel to the first polar plate, from coming into contact with each other perpendicular to the joint plane. The first polar plate is thus electrically insulated from the second polar plate, while being kept at a distance from the second polar plate. Indeed, the pad, which is electrically insulating, prevents direct contact between the first and second polar plates, even in the event of involuntary deformation of one of the two plates. According to the invention, even following a deformation, for example caused accidentally by a force applied locally to the plate, or following an involuntary impact on the irregular region, no short circuit is generated in the electrochemical cell, since the pad prevents the polar plates from coming into contact with each other.In addition, the presence of the pad makes it possible to limit the use of electrically insulating material, by positioning the pad in contact with only one area of ​​the first polar plate, in this case a relatively fragile or deformable area.

[0007] According to other advantageous aspects of the invention, the peripheral seal comprises one or more of the following characteristics, taken individually or in all technically possible combinations:

[0008] - The sealing portion forms a frame comprising an elbow, the pad projecting from the sealing portion from the elbow. Thanks to this aspect of the invention, the pad makes it possible to avoid accidental contact at at least one corner of the plates. - The direction of extension is perpendicular to the sealing portion, at the pad. Thanks to this aspect of the invention, the perpendicular direction of extension makes it possible to maximize the extension length of the pad and therefore the point surface of support with the plate.

[0009] - The extension direction forms an angle between 1 and 89° with the sealing portion at the pad. Thanks to this aspect of the invention, the extension direction with such an angle makes it possible to guarantee a good compromise between the size of the pad and the length of the point support surface with the plate.

[0010] - The pad includes a through hole, perpendicular to the joint plane. The hole in the pad prevents any risk of short circuit near a particularly fragile or deformable area of ​​the plate, such as an orifice for example.

[0011] - A thickness of the sealing portion measured perpendicular to the joint plane is greater than a maximum thickness of the pad, measured perpendicular to the joint plane. The fact that the sealing portion is thicker than the pad prevents the latter from coming to bear against the plates without the sealing portion being so. This thus ensures that the sealing portion is in good contact with the plates and can therefore fully play its sealing role.

[0012] - The pad comprises a main portion and a joining portion, the joining portion connecting the main portion to the sealing portion, and a thickness of the joining portion, measured perpendicular to the joint plane, is less than a thickness of the main portion measured perpendicular to the joint plane. The variation in thickness of the pad allows the areas in contact with one of the plates to be chosen by design, while minimizing the amount of material used for the manufacture of the pad.

[0013] - The peripheral seal comprises several pads, the pads projecting from the sealing portion towards the outside of the sealing portion and being located at a distance from each other. This allows the presence of the pads to be well distributed around the perimeter of the peripheral seal and thus to avoid any accidental contact between the plates, regardless of the location of the accidental local deformation.

[0014] According to a second aspect, the invention relates to a polar separator comprising a first polar plate extending along a plate plane perpendicular to a stacking direction and comprising: a circulation field, for guiding a circulation of a functional fluid and which is parallel to the plate plane; a first peripheral zone, parallel to the plate plane, surrounding the circulation field; and the peripheral seal according to any one of the preceding claims, the sealing portion being in contact with the first peripheral zone, so that the closed loop formed by the sealing portion surrounds the circulation field, the pad extending over the peripheral zone.

[0015] According to other advantageous aspects of the invention, the polar separator comprises one or more of the following characteristics, taken individually or in all technically possible combinations:

[0016] - The first peripheral zone comprises an irregular region, the irregular region comprising a main portion and a free edge, the free edge being non-rectilinear and delimiting the main portion; and the pad extends over the main portion near the free edge, being in contact with the main portion.

[0017] - The pad extends close to the free edge at a minimum distance from the free edge of less than 1 mm, preferably less than 0.8 mm, more preferably less than or equal to 0.5 mm, the minimum distance being measured parallel to the plate plane.

[0018] - The pad is a first pad, the cell further comprising a second peripheral seal, the second peripheral seal comprising a second pad, arranged on the main part, the first pad and the second pad being arranged on either side of the first peripheral zone, so that the first peripheral zone is interposed between the first pad and the second pad in the stacking direction and the first pad and the second pad are aligned in the stacking direction.

[0019] According to a third aspect, the invention relates to an electrochemical cell comprising: a polar separator as described above, a second polar plate, parallel to the first polar plate, the second polar plate comprising a second peripheral zone; and a membrane electrode assembly, interposed between the first polar plate and the second polar plate in the stacking direction, the membrane electrode assembly comprising: o a central portion, comprising a proton exchange polymer membrane, o a peripheral portion surrounding the central portion, the peripheral portion being interposed between the first peripheral zone and the second peripheral zone in the stacking direction, the peripheral seal being interposed between the first peripheral zone and the peripheral portion in the stacking direction;and o a gas diffusion layer, interposed between the proton exchange polymer membrane and the circulation field according to the stacking direction.;

[0020] According to a fourth aspect, the invention relates to a fuel cell comprising a stack of cells, each cell being as described previously, in which the cells are successively superimposed in the stacking direction, the second polar plate of each cell bearing against the first polar plate of the next cell in the stack, in the stacking direction.

[0021] Advantageously, the polar separator is as described above, the irregular region of each cell is aligned with the irregular region of the next cell in the stack, following the stacking direction, the respective free edge of the irregular regions thus aligned being configured to cooperate mechanically with an alignment rail, to align the cells relative to each other, the alignment rail being arranged parallel to the stacking direction and passing through or along the aligned irregular regions.

[0022] According to a fifth aspect, the invention relates to a vehicle comprising a fuel cell as described above.

[0023] The electrochemical cell described above is preferably obtained using a manufacturing method, comprising: providing the first polar plate; providing the second polar plate; providing the membrane-electrode assembly; forming the peripheral seal by overmolding the peripheral seal onto the first peripheral zone; and forming the pad by overmolding the pad directly onto the first peripheral zone.

[0024] The manufacturing method advantageously comprises the following characteristic: the formation of the peripheral seal and the formation of the pad are carried out simultaneously using the same overmolding operation, comprising positioning a mold on the first peripheral zone, and injecting a seal material into the mold to form both the peripheral seal and the pad.

[0025] 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: [Fig. 1] Figure 1 is a view of a fuel cell according to the invention;

[0026] [Fig. 2] Figure 2 is a view of a polar separator, in this case a cathode polar plate, and of a membrane-electrode assembly of an electrochemical cell according to the invention;

[0027] [Fig. 3] Figure 3 is a view of a detail of the cathode polar plate of Figure 2;

[0028] [Fig. 4] Figure 4 is a view of an anode polar plate of an electrochemical cell according to the invention;

[0029] [Fig. 5] Figure 5 is a section of a portion of a stack of electrochemical cells in normal configuration according to the invention;

[0030] [Fig. 6] Figure 6 is a section similar to Figure 3, one of the electrochemical cells being in a deformed configuration according to a first example;

[0031] [Fig. 7] Figure 7 is a section similar to Figure 3, one of the electrochemical cells being in a deformed configuration according to a second example; [Fig. 8] Figure 8 is a flowchart of a method of manufacturing an electrochemical cell according to the invention; and

[0032] [Fig. 9] Figure 9 is a partial view of a polar plate belonging to an electrochemical cell according to a second embodiment of the invention.

[0033] 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.

[0034] The fuel cell 1 comprises a stack 5, comprising separator plates, here bipolar plates 12. Each bipolar plate 12 comprises two associated polar plates, or more precisely two polar separators. One of the polar plates is a first polar plate 13, which is here a cathode polar plate 13 and the other polar plate is a second polar plate 113, which is here an anodic polar plate 113.

[0035] Each cathode polar plate 13, visible in Figure 2, extends along a plate plane P, and each anodic polar plate 113, visible in Figure 3, extends along a plate plane P', parallel to the plate plane P.

[0036] 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 clamped against each other by a compressive force applied, in a stacking direction X, on the stack 5, or alternatively, are welded or glued to each other. The stacking direction X is perpendicular to the planes P of the cathode polar plates 13 and P' of the anodic polar plates 113.

[0037] The battery 1 comprises a plurality of electrochemical cells 14, also called 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 polar plates, cathode 13 and anodic 113, associated with this cell 14. The membrane-electrode assembly 80 is also designated by MEA 80 (abbreviation of the expression “membrane-electrode 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.

[0038] Each bipolar plate 12 is thus common to two neighboring cells 14.

[0039] The bipolar plates 12 and the MEAs 80 are stacked according to the stacking direction X.

[0040] We also define a longitudinal direction Y and a transverse direction Z, perpendicular to the stacking direction X.

[0041] 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.

[0042] Alignment guides 18, visible in Figure 4, parallel to the stacking direction X, are used to keep the cells 14 aligned with each other in the stacking direction X. In the example of Figure 4, the alignment guides belong to the fuel cell 1. In a variant not shown, the alignment guides are used when stacking the cells and are then removed once the stacking is complete, and therefore do not belong to the fuel cell.

[0043] Each cathode polar plate 13 comprises a first peripheral zone 21, a circulation field 23, and optionally, two homogenization zones 25. Each cathode polar plate 13 also comprises at least one plate orifice 28, here six plate orifices 28a, 28b and 28c. The first peripheral zone 21 is parallel to the plate plane P, extends around the entire circumference of the cathode polar plate 13, and borders the circulation field 23, the homogenization zones 25 and the plate orifices 28.

[0044] The first peripheral zone 21 comprises an outer edge 29, and at least one irregular region, in the example of FIG. 2, several irregular regions 30a, 30b and 30c. The outer edge 29 is continuous and forms a closed contour of the first peripheral zone 21.

[0045] Each irregular region 30a, 30b and 30c respectively comprises a main portion 31a, 31b and 31c and a free edge 32a, 32b and 32c. The free edges 32a, 32b and 32c are non-rectilinear and belong to the outer edge 29. The irregular region 30a comprises a plate corner 35 of the cathode pole plate 13. The plate corner 35 belongs to the first peripheral zone 21 and the free edge 30a delimits the plate corner 35. The irregular region 30b comprises a straight notch 37 belonging to the first peripheral zone 21. The straight notch 37 is delimited by the free edge 32b, and the main part 31b frames the straight notch 37. The irregular region 30c is a through-orifice 39 belonging to the first peripheral zone 21. The main part 31c surrounds the through-orifice 39 and the free edge 32c forms a closed contour which internally delimits the through-orifice 39.The through hole 39 serves, for example, as a guide hole during the manufacture of the plates and / or the seal and / or the stacking of the plates of the fuel cell.

[0046] The irregular regions 30a, 30b and 30c are advantageously used to align the cathode polar plates 13 of the stack 5 along the stacking direction X. The irregular regions 30a, 30b and 30c of an electrochemical cell 14 are aligned with the irregular regions 30a, 30b and 30c of the next electrochemical cell 14 in the stack 5. In the example shown in FIG. 1, the alignment guides 18 thus run along the irregular regions 30b and mechanically cooperate with the free edges 32b. In other words, the alignment guides 18 are inserted into the straight notches 37.

[0047] The 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 circulation field 23 is configured to guide a circulation of a functional fluid in the longitudinal direction Y. In the example of FIG. 1, the circulation field 23 is configured to guide air. The circulation field 23 comprises channels 24, extending substantially parallel to the longitudinal direction Y, and arranged next to each other in the transverse direction Z. The channels 24 are for example delimited by grooves hollowed out in the cathode polar plate 13, or by a stamping of the cathode polar plate 13. The plate orifices 28 are intended for the injection of functional fluid or 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 pole plate 13, aligned along the transverse direction Z, and three plate orifices 28a, 28b and 28c are located on the other side of the pole plate 13 along the stack longitudinal direction Y, also aligned along the transverse direction Z. 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 pole plate 13 forms an outlet for this functional fluid. The functional fluids are advantageously three in number and are for example air, hydrogen and a cooling fluid. In the example of the figures, air circulates in the orifices 28a, cooling fluid in the orifices 28b and hydrogen in the orifices 28c. Thus, one of the ports 28a is an air supply port, and the other port 28a is an air exhaust port.The same applies to ports 28b for the coolant and 28c for the hydrogen.

[0048] The homogenization zones 25 are arranged on either side of the circulation field 23 in the longitudinal direction Y. One of the homogenization zones 25 makes it possible to distribute air from one of the orifices 28a towards the circulation field 23, and the other homogenization zone 25 makes it possible to evacuate the functional fluid distributed over the entire circulation field 23 towards the other orifice 28a, located opposite the cathode polar plate 13 in the longitudinal direction Y.

[0049] 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.

[0050] Each cell, and more precisely each polar separator 14, further comprises a first peripheral seal 40, which extends along a joint plane P40. The first peripheral seal 40 is made of a material impermeable to functional fluids, and is for example made of silicone.

[0051] 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 bipolar plates, or two portions of polar plate, 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.

[0052] The first peripheral seal 40 comprises a sealing portion 41, which forms a closed loop parallel to the joint plane P40.

[0053] Advantageously, and as visible in Figure 2, the first peripheral seal 40 forms a frame comprising four elbows 42, close to the plate corners 35, to follow the geometry of the cathode plate 13.

[0054] When the first peripheral seal 40 is integrated into the electrochemical cell 14, the joint plane P40 and the plate plane P are parallel and the sealing portion 41 extends over the first face 13a of the cathode polar plate 13, and more particularly over the first peripheral zone 21, forming a closed loop around the circulation field 23, the homogenization zones 25 and the orifices 28. The sealing portion 41 separates the irregular regions 30 from the circulation field 23 and prevents the functional fluids from leaving the circulation field 23. By "integrated", it is meant that the peripheral seal 40 is in place on the polar plate 13.

[0055] In the example of the figures, the first peripheral seal 40 is a lip seal, that is to say that the sealing portion 41 comprises an inner lip 41a and an outer lip 41b which delimit it. The inner lip 41a is on the side of the first peripheral seal 40 facing the circulation field 23 and the outer lip 41b is on the side of the first peripheral seal 40 facing the irregular regions 30. When the cells 14 are stacked to form the stack 1, the first peripheral seal 40 is compressed and the sealing portion has a thickness E40, measured perpendicular to the joint plane P40 at one of the lips 41a or 41b. Advantageously, the thickness E40', which is the thickness of material located between the two lips 41a and 41b, measured perpendicular to the joint plane P40, is between 0.05 mm and 0.40 mm, and is preferably equal to 0.150 mm.

[0056] In a variant not shown, the first peripheral seal 40 is a so-called flat seal, that is to say that it does not include lips.

[0057] The first peripheral seal 40 further comprises a first pad, here several first pads 43, 45, 47 and 49. The first pads 43, 45, 47 and 49 are electrically insulating, and are integral with the sealing portion 41. In other words, the first pads 43, 45, 47 and 49 are in a single piece, monolithic with the sealing portion 41. Each first pad 43, 45, 47, 49 projects from the sealing portion 41 in a direction of extension D while being at a distance from the other first pads 43, 45, 47. In particular, the first pads 43, 45, 47 and 49 do not extend all along the sealing portion 41. In other words, the first pads 43, 45, 47, and 49 are point pads, which form an ear at precise locations of the sealing portion 41. The direction of extension D is, for each first pad, the average direction of extension of the first pad 43, 45, 47 and 49.

[0058] Each first pad 43, 45, 47 and 49 projects from the sealing portion 41 towards an outside of the sealing portion 41, that is to say outside a surface defined by the closed loop formed by the sealing portion 41. The extension directions D of each first pad 43 and 45 form an angle of between 1 and 89° with the sealing portion 41 at the first pad 43 or 45 considered, measured in the joint plane P40. The extension directions D of each first pad 47 and 49 are perpendicular to the sealing portion 41 at the first pad 47 or 49 considered, in the joint plane P40.

[0059] When the first peripheral seal 40 is integrated into the electrochemical cell 14, the first pads 43, 45, 47 and 49 are configured to be in contact with the cathode polar plate 13, in particular the first face 13a.

[0060] Each first pad 43 extends from one of the bends 42 of the sealing portion 41 onto and in contact with one of the main parts 31a, each first pad 45 and 47 extends onto and in contact with one of the main parts 31b and each first pad 49 extends onto one of the main parts 31c. The first pad 49 comprises a through orifice 49a, perpendicular to the joint plane P40, which when the first pad 49 is in contact with the first face 13a, surrounds the orifice 39 leaving it free. Such a pad 49 then makes it possible to remarkably avoid any risk of short circuit between the plates at the orifice 39 which has a weak zone of the plate due to the material recess.

[0061] Advantageously, several first pads extend over the same main part. This is the case in particular for the main part 31b, shown in detail in Figure 3, where two first pads 45 extend over the main part 31b while being located on either side of the right notch 37 in the longitudinal direction Y, and the first pad 47 extends between the first pads 45 in the longitudinal direction Y. The first pads 43, 45, 47 and 49 extend near the free edges 32a, 32b and 32c respectively such that a minimum distance dmin, measured parallel to the plate plane P between the first pads 43, 45, 47 and 49 and the free edges 32a, 32b and 32c is less than 1 mm, preferably less than 0.8 mm, more preferably less than or equal to 0.5 mm.The minimum distance dmin is greater than 0.1 mm, for example to be able to position an overmold on the cathode polar plate 13 to form the first pads 43, 45, 47 and 49.

[0062] As can be seen in Figures 2 to 5, the first pads 43 and 45 advantageously comprise a main part, respectively a main part 43a and 45a and a joining part, respectively a joining part 43b and 45b. The joining part 43b connects the main part 43a to the sealing portion 41. Similarly, the joining part 45b connects the main part 45a to the sealing portion 41. The main part 45a has a thickness E45a, and the joining part 45b has a thickness E45b, the thicknesses E45a and E45b being measured perpendicular to the joint plane P40. The main part 45a has a thickness E45a which is greater than the thickness E45b, thus the thickness E45a is said to be the maximum thickness of the first pad 45. The thickness E45a is less than or equal to the thickness E40.For example, the thickness E45b is defined as the smallest possible taking into account the manufacturing process chosen, and may be between 0.05 mm and 0.25 mm, advantageously between 0.05 mm and 0.15 mm, and preferably equal to 0.10 mm. The thickness E45a, for its part, may for example be between 0.15 mm and 0.50 mm, advantageously between 0.15 mm and 0.25 mm, preferably equal to 0.20 mm. Preferably, the thickness E45b is less than the thickness E40', preferably less than 0.10 mm, for example being 0.05 mm less than the thickness E40'. These thicknesses are chosen so as to, on the one hand, optimize the mechanical resistance of the first peripheral seal 40, the optimization of the anti-short-circuit function, without however increasing the thickness of the electrochemical cell 14 too significantly.

[0063] Similarly, a thickness of the main part 43a is greater than a thickness of the joining part 43b, and the thickness of the main part 43a is less than the thickness E40 of the first peripheral seal 40, the thicknesses being measured perpendicular to the joint plane P40. The maximum thickness of the first pad 43 is therefore the thickness of the main part 43a.

[0064] The smaller thickness of the joining portions 43b and 45b facilitates creep, and / or deformation, and / or local folding of the first peripheral seal 40, which is compressed when the cathode polar plates 13 are stacked to form the stack 1 and thus limits the risk of deformation of the first peripheral seal 40. More precisely, during a deformation of the first peripheral seal 40, the following phenomena will be able to take place easily thanks to the invention: the joining portion 45b will be able to easily deform, bend, stretch, etc. due to its small thickness. This will allow the main part 45a to easily orient itself in a direction making it possible to avoid any contact between the two polar plates 13. The lips 41a, 41b, given their greater thickness than the joining portion 45b, will not or will only slightly deform, thus preserving the good sealing function of the first peripheral seal 40

[0065] The first pads 47 and 49 advantageously have a thickness equal to the thickness E45a, but as a variant, they have a different thickness, which is less than or equal to the thickness E40 of the first peripheral seal 40.

[0066] In a variant not shown, all the first pads comprise a main part and a joining part.

[0067] Alternatively not shown, some irregular regions do not have a first pad extending over them.

[0068] Each electrochemical cell 14 advantageously comprises a second peripheral seal 60, which extends along a seal plane P60.

[0069] In the example of Figures 5 and 6, the second peripheral seal 60 is a lip seal, comprising a sealing portion 61 similar to the sealing portion 41. In particular, the sealing portion 61 forms a closed loop parallel to the joint plane P60. When the second peripheral seal 60 is integrated into the electrochemical cell 14, the sealing portion 61 is in contact with the cathode polar plate 13, more precisely in contact with a face 13b of the cathode polar plate 13, opposite the face 13a in the stacking direction X. In particular, the sealing portion 61 is arranged on the first peripheral zone 21.

[0070] The sealing portion 61 comprises an inner lip 61a and an outer lip 61b which delimit it, and which are similar to the outer 41a and inner 41b lips. When the cells 14 are stacked to form the stack 1, the second peripheral seal 60 is compressed and has a thickness E60, measured along the stacking direction X at one of the lips 61a or 61b. Advantageously, a thickness E60', which is the thickness of material located between the two lips, measured along the stacking direction X, is between 0.05 mm and 0.40 mm, and is preferably equal to 0.150 mm.

[0071] The second peripheral seal 60 advantageously comprises at least one second pad, here the second pad 65. The second pad 65 is made of a single piece with the sealing portion 61, in other words, the second pad 65 is made of a single piece, monolithic with the sealing portion 61. The second pad 65 is made of electrically insulating material. The second pad 65 advantageously projects from the sealing portion 61 in a direction of extension D. The second pad 65 is a point pad, which forms an ear at a precise location of the sealing portion 61. The direction of extension D is, as for the first pads 43, 45, 47 and 49, the average direction of extension of the second pad 65.When the second peripheral seal 60 is integrated into the electrochemical cell 14, the joint plane P60 and the plate plane P are parallel and the second pad 65 is in contact with the cathode polar plate 13, and arranged on the first peripheral zone 21, such that the peripheral zone 21 is interposed between one of the first pads 43, 45, 47 or 49 and the second pad 65 in the stacking direction X, here the first pad 45 in the stacking direction X. In other words, the second pad 65 is advantageously aligned in the stacking direction X with one of the first pads 43, 45, 47 or 49, and in the case of FIGS. 5 and 6, the second pad 65 is aligned with the first pad 45 and of identical shape to the first pad 45.

[0072] The alignment of the second pad 65 with one of the first pads 43, 45, 47 or 49 according to the stacking direction X makes it possible to avoid a short circuit between two consecutive polar plates regardless of the direction of deformation of the polar plate 13.

[0073] In a variant not shown, the second peripheral seal comprises several second pads, each second pad being aligned in the stacking direction with one of the first pads of the first peripheral seal.

[0074] In a variant not shown, the second pad is not aligned with one of the first pads in the stacking direction.

[0075] The second pad 65 extends close to the free edge 32b, and advantageously, is separated by at least the minimum distance dmin from the free edge 132b, the minimum distance dmin being measured parallel to the plate plane P.

[0076] In the example of Figure 4, the second pad 65 comprises a main part 65a and a joining part 65b, which connects the main part 65a to the second peripheral joint 60.

[0077] The main part 65a has a thickness E65a and the joining part 65b has a thickness E65b, the thicknesses E65a and E65b being measured along the stacking direction X. The thickness E65a is greater than the thickness E65b, thus the thickness E65a is said to be the maximum thickness of the second pad 65. The maximum thickness, here the thickness E65a, is less than the thickness E60 of the second peripheral seal 60. In a similar manner to what has been described for the first peripheral seal 40, the thickness E65b may be between 0.05 mm and 0.25 mm, advantageously between 0.05 mm and 0.15 mm, and preferably be equal to 0.10 mm, and the thickness E65a may for example be between 0.15 mm and 0.50 mm, advantageously between 0.15 mm and 0.25 mm. mm, preferably equal to 0.20 mm. Preferably, the thickness E65b is less than the thickness E60', preferably less than 0.10 mm, for example being 0.05 mm less than the thickness E60'.These thicknesses are chosen so as to, on the one hand, optimize the mechanical resistance of the second peripheral seal 60, the optimization of the anti-short-circuit function, without however increasing too significantly the thickness of the electrochemical cell 14, as has been described for the first peripheral seal 40.

[0078] The anode polar plate 113 comprises a second peripheral zone 121, and advantageously a circulation field 123, homogenization zones 125 and plate orifices 128a, 128b and 128c.

[0079] Advantageously, the second peripheral zone 121 extends around the entire periphery of the anode polar plate 113, and borders the circulation field 123, the homogenization zones 125 and the plate orifices 128.

[0080] The second peripheral zone 121 advantageously comprises an outer edge 129 and at least one irregular region, in the example of FIG. 4, several irregular regions 130a, 130b and 130c, similar to the regions 30a, 30b, 30c. The outer edge 129 is continuous and forms a closed contour of the second peripheral zone 121.

[0081] Each irregular region 130a, 130b and 130c advantageously comprises, in a similar manner to what has been described for the regions 30a, 30b and 30c, respectively a main portion 131a, 131b and 131c and a free edge 132a, 132b and 132c. The main portions 131a, 131b and 131c are similar respectively to the main portions 31a, 31b and 31c and the free edges 132a, 132b and 132c are similar respectively to the free edges 32a, 32b and 32c.

[0082] The irregular region 130a advantageously comprises a plate corner 135 of the anode pole plate 113. The plate corner 135 belongs to the first peripheral zone 121 and the free edge 132a delimits the plate corner 135. The irregular region 130b comprises a straight notch 137 belonging to the second peripheral zone 121. The straight notch 137 is delimited by the free edge 132b, and the main part 131b frames the straight notch 137. The irregular region 130c is a through-orifice 139 belonging to the second peripheral zone 121. The main part 131c surrounds the through-orifice 139 and the free edge 132c forms a closed contour which internally delimits the through-orifice 139.

[0083] The irregular regions 130a, 130b and 130c of the different anode polar plates 113 of the stack 5 are advantageously aligned along the stacking direction X. Thus, the irregular regions 130a, 130b and 130c are advantageously used to align the anode polar plates 113 along the stacking direction X.

[0084] The circulation field 123 extends over a first face 113a of the anode polar plate 113, the first face 113a facing the membrane electrode assembly 80. The circulation field 123, similarly to the circulation field 23, is configured to guide a circulation of a functional fluid along the longitudinal direction Y which is hydrogen in the example of the figures. The circulation field 123 comprises channels 124, similar to the channels 24.

[0085] The 125 homogenization zones are similar to the 25 homogenization zones.

[0086] The plate ports 128 are similar to the plate ports 28a, 28b and 28c and extend the ports 28a, 28b and 28c of the cathode pole plate 13. In the example of the figures, air flows through the ports 128a, coolant through the ports 128b and hydrogen through the ports 128c. Thus, one of the ports 128c is a hydrogen supply port, and the other port 128c is a hydrogen discharge port. The same is true with the ports 128b for the coolant and 128a for the air.

[0087] It is provided that only the openings 128c deliver and discharge functional fluid, here hydrogen on 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.

[0088] Advantageously, and as can be seen in FIG. 4, each electrochemical cell 14 comprises a third peripheral seal 140 which extends along a seal plane P140. The third peripheral seal 140 is made of a material impermeable to functional fluids, and is for example made of silicone, in a similar manner to the first peripheral seal 40.

[0089] The third peripheral seal 140 comprises a sealing portion 141, which forms a closed loop parallel to the joint plane P140.

[0090] Advantageously, and as visible in Figure 4, the third peripheral seal 140 comprises four elbows 142, close to the plate corners 135, to follow the geometry of the anode plate 113.

[0091] When the third peripheral seal 140 is integrated into the electrochemical cell 14, the sealing portion 141 extends over the first face 113a of the anode polar plate 113, and more particularly over the second peripheral zone 121, forming a closed loop around the circulation field 123, the homogenization zones 125 and the orifices 128. The sealing portion 141 separates the irregular regions 130 from the circulation field 123 and thus prevents the functional fluids from leaving the circulation field 123.

[0092] As seen in Figures 5 and 6, the third peripheral seal 140 is a flat seal, that is to say that the sealing portion 141 is flat. When the cells 14 are stacked to form the stack 1, the third peripheral seal 140 is compressed and the sealing portion has a thickness E140, measured perpendicular to the joint plane P140. In a variant not shown, the third peripheral seal is a lip seal.

[0093] The third peripheral seal 140 comprises a third pad, here advantageously, several third pads 143, 145, 147 and 149, similar to the first pads 43, 45, 47 and 49. The third pads 143, 145, 147 and 149 are made of the same material as the sealing portion 141, in other words are made of a single piece, monolithic with the sealing portion 141.

[0094] Each third pad 143, 145, 147 projects from the sealing portion 141 towards the outside of the sealing portion 141 in an extension direction D, and are located at a distance from each other. In particular, the third pads 143, 145, 147 and 149 do not extend all along the sealing portion 141. In other words, the third pads 143, 145, 147, and 149 are point pads, which form an ear at specific locations of the sealing portion 141.

[0095] The direction of extension D is, for each third pad, the average direction of extension of the third pad 143, 145, 147 and 149.

[0096] Each third pad 143, 145, 147 and 149 projects from the sealing portion 141 towards the outside of the sealing portion 141, i.e. outside a surface defined by the closed loop formed by the sealing portion 141.

[0097] The extension directions D of each third pad 143 and 145 form an angle of between 1 and 89° with the sealing portion 141 at the level of the third pad 143 or 145 considered, measured in the joint plane P140. The extension directions D of each third pad 147 and 149 are perpendicular to the sealing portion 141 at the level of the third pad 147 or 149 considered, in the joint plane P140.

[0098] When the third peripheral seal 140 is integrated into the electrochemical cell 14, the seal plane P140 and the plate plane P' are parallel and the third pads 143, 145, 147 and 149 are configured to be in contact with the cathode polar plate 113, in particular the first face 113a.

[0099] Each third pad 143 extends over and in contact with one of the main parts 131a from one of the bends 142 of the sealing portion 141, each third pad 145 and 147 extends over and in contact with one of the main parts 131b and each third pad 149 extends over and in contact with one of the main parts 131c. The third pad 149 comprises an orifice 149a passing perpendicularly to the joint plane P140, which surrounds the orifice 139 leaving it free.

[0100] The third pads 143, 145, 147 and 149 extend near the free edges 132a, 132b and 132c respectively, and advantageously, are separated from the free edges 132a, 132b and 132c by a minimum distance dmin. In the example of FIG. 4, the third pads 143 and 145 comprise a main part, respectively the main parts 143a and 145a, and a joining part, respectively the joining parts 143b and 145b. The joining part 143b connects the main part 143a to the sealing portion 141 of the third peripheral seal 140. Similarly, the joining part 145b connects the main part 145a to the sealing portion 141.

[0101] The main portion 145a has a thickness E145a, and the joining portion 145b has a thickness E145b, the thicknesses E145a and E145b being measured perpendicular to the joint plane P140. The main portion 145a has a thickness E145a which is greater than the thickness E145b, thus the thickness E145a is said to be the maximum thickness of the third pad 145. The maximum thickness of the third pad 145 is less than or equal to the thickness E140.

[0102] Similarly, a thickness of the main portion 143a is greater than a thickness of the joining portion 143b, and the thickness of the main portion 143a is less than or equal to the thickness E140 of the third peripheral seal 140, the thicknesses being measured perpendicular to the joint plane P140. The maximum thickness of the third pad 143 is therefore the thickness of the main portion 143a.

[0103] The smaller thickness of the joining portions 143b and 145b facilitates the creep of the third peripheral seal 140, which is compressed when the anode pole plates 113 are stacked to form the stack 1 and thus limits the risk of deformation of the third peripheral seal 140.

[0104] The third pads 147 and 149 advantageously have a thickness equal to the thickness E145a, but as a variant, they have a different thickness, which is less than or equal to the thickness E140 of the third peripheral seal 140.

[0105] In a variant not shown, all third pads comprise a main part and a joining part.

[0106] Alternatively not shown, some irregular regions of the anode pole plate do not have a third pad extending thereover.

[0107] For each bipolar plate 12, the cathode polar plate 13 bears against the anode polar plate 113 belonging to the same bipolar plate 12. In particular, as shown in FIGS. 5 and 6, the cathode polar plate 13 bears against the anode polar plate 113 belonging to the same bipolar plate 12 by means of the inner 61 and outer 62 lips of the second peripheral seal 60 in the stacking direction X.

[0108] Advantageously, for each electrochemical cell 14, the irregular regions 130a, 130b and 130c respectively overlap with the irregular regions 30a, 30b and 30c of the same cell 14, and extend them in the stacking direction X. In addition, in a particularly advantageous manner, the irregular regions 30a, 130a, 30b, 130b and 30c, 130c of the same cell 14 are aligned in the stacking direction X and respectively overlap with the irregular regions 30a, 30b, 30c, 130a, 130b and 130c of the next cell 14 in the stack 5. This makes it possible to align the cells 14 in the stacking direction X using the irregular regions 30 and 130. Thus, in the example of Figure 1, the alignment guides 18 run along the irregular regions 30b and 130b and mechanically cooperate with the free edges 32b and 132b. In other words, the alignment guides 18 are inserted both in the straight notches 37 and in the straight notches 137.In a variant not shown, the alignment guides are rods passing through the through holes, or complementary devices at the corners, which mechanically cooperate with the free edges delimiting the through holes or the corners.

[0109] Alternatively, the irregular regions 30 and 130 make it possible to pass a tie rod connecting the end plates 16 together in the stacking direction X, or to position the cathode 13 and anode 113 polar plates during their manufacture. This is particularly the case for the orifices 39 and 139 which advantageously serve to position the cathode 13 or anode 113 polar plate relative to an overmold used to mold the first or third peripheral seal 40 or 140.

[0110] Cooling fluid circulates between the cathode polar plate 13 and the anodic polar plate 113 of the same bipolar plate, from the openings 28b and 128b. Thus, the second peripheral seal 60 ensures a seal between the bipolar plate 12 and the outside and prevents the cooling fluid from escaping.

[0111] In a variant not shown, the cathode and anodic polar plates of the same bipolar plate are glued or welded together, a second peripheral joint then not being necessary.

[0112] In a variant 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 a variant.

[0113] The membrane-electrode assembly 80, or MEA 80, comprises a central portion 81 and a peripheral portion 82, surrounding the central portion 81.

[0114] The central portion 81 comprises a membrane 83, visible in dotted lines in Figure 2. The membrane 83 is advantageously a proton exchange polymer membrane. The membrane 83 extends parallel to the plate planes P and P', and is opposite the circulation fields 23 and 123 in the stacking direction X. 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 faces one of the plate orifices 28a and one of the plate orifices 128a along the stacking direction X and extends these plate orifices 28a and 128a along the stacking direction X.The same applies to 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 discharging the fluids circulating in each electrochemical cell 14. The holding frame 84 comprises notches and orifices, which extend the notches 37 and the orifices 39 in the stacking direction X.

[0115] 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.

[0116] The MEA 80 also comprises 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.

[0117] 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.

[0118] 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 and can diffuse through the latter to the membrane 83, to react with each other.

[0119] As seen in Figures 5 and 6, the first peripheral seal 40 and the third peripheral seal 140 bear against the holding frame 84 in the stacking direction X, ensuring the sealing of the electrochemical cell 14 with the exterior.

[0120] In Figure 5, the electrochemical cell 14 is in a normal configuration. The following description is made with reference to the irregular region 30b, but is also valid for the regions 30a and 30c.

[0121] In the normal configuration, the irregular region 30b extends parallel to the plate plane P. The peripheral portion 82, which in the example of the figures is the holding frame 84, is arranged between the first pad 45 and the second peripheral zone 121 along the stacking direction X. In the example of FIG. 5, the electrochemical cell 14 comprises the third pad 145, thus the holding frame 84 and arranged between the first pad 45 and the third pad 145 along the stacking direction X. In the example of FIG. 5, the thickness E40 is greater than the thickness E45a, and the thickness E140 is greater than the thickness E145a, the pads 45 and 145 are therefore at a distance from the holding frame 84.Alternatively, the thickness E45a is equal to the thickness E40, in which case, the main part 45a of the first pad 45 is in contact with the holding frame 84 and / or the thickness E145a is equal to the thickness E140 in which case the main part 145a is in contact with the holding frame 84.

[0122] The irregular region 30b is particularly susceptible to deformation, for example due to involuntary shocks during handling of the cathode polar plate 13.

[0123] Finally, the irregular region 30b is advantageously used to align the cathode polar plates 13. For example, and as shown in FIG. 1, by using the alignment guides 18, which are inserted into the straight notches 37 and 137. Thus, the alignment guides 18 exert stresses on the straight notches 37, in particular stresses along the longitudinal Y and transverse Z directions, which can cause their deformation, in addition to the stresses due to the stacking of the cathode 13 and anodic 113 polar plates forming the electrochemical cells 14.

[0124] Thus, the electrochemical cell 14 is capable of passing into a deformed configuration, in which the irregular region 30b is bent, so that the irregular region 30b is inclined relative to the plate plane P. An example of a deformed configuration is visible in FIG. 6. In the example shown in FIG. 6, the first pad 45 is in contact with the holding frame 84, itself in contact with the third pad 145. The first peripheral zone 21, more particularly the irregular region 30b, is kept at a distance from the second peripheral zone 121 by at least the third pad 145, and in the example of FIG. 6, also by the first pad 45 and the holding frame 84.

[0125] In variants not shown, the holding frame is perforated or torn, for example by the first peripheral zone, or does not extend over the entire width of the first peripheral zone. In this case, in the deformed configuration, the first pad is in contact with the third pad, or the second peripheral zone is directly in contact with the third pad. In the latter case, only the third pad keeps the first and second peripheral zones at a distance from each other.

[0126] The first pad 145 being electrically insulating, the cathode 13 and anodic 113 polar plates of the same electrochemical cell 14 are kept electrically isolated from each other. The first pad 145 therefore prevents a short circuit within the same electrochemical cell 14, caused by a deformation of an irregular region 30a, 30b or 30c of the cathode polar plate 13.

[0127] In a variant visible in Figure 7, when the electrochemical cell 14 is in a deformed configuration, it is one of the irregular regions of the anode polar plate 113, in other words, of the second plate, which is inclined relative to the plate plane P'. In Figure 7, it is the irregular region 130b which is deformed. The first pad 45 extending over the main part 31b of the irregular region 30b aligned in the stacking direction X with the irregular region 130b is then in contact with the inclined irregular region 130b, either directly or via the holding frame 84, and / or the third pad 145 extending over the inclined irregular region 30b. The first pad 45 thus keeps the peripheral zones 21 and 121 at a distance from each other.

[0128] The electrochemical cells 14 described above are preferably obtained using a manufacturing method, shown in FIG. 8 and comprising a step 501 of providing the cathode polar plate 13, then a step 502 of providing the anodic polar plate 113, and a step 503 of providing the MEA 80.

[0129] The manufacturing method then comprises a step 504 of forming the first peripheral seal 40. The forming step 504 is carried out by overmolding the first peripheral seal 40 onto the first peripheral zone 21. In particular, a mold is applied to the first peripheral zone 21 and a seal material is injected into the mold, in order to form the first peripheral seal 40.

[0130] The manufacturing method comprises a step 505 of forming the first pads 43, 45, 47 and 49, by overmolding the first pads 43, 45, 47 and 49 directly onto the first peripheral zone 21.

[0131] Advantageously, steps 504 and 505 take place simultaneously, steps 504 and 505 being carried out during the same overmolding operation. During this overmolding operation, the mold is positioned on the first peripheral zone 21, and the seal material injected into the mold forms both the first peripheral seal and the first pads 43, 45, 47 and 49.

[0132] Advantageously the same process is repeated to form the second peripheral seal.

[0133] Figure 9 shows a part of an electrochemical cell 214, as an alternative embodiment to the electrochemical cell 14. The elements of the electrochemical cell 214 identical to those of the electrochemical cell 14 are designated by the same reference numerals and are not described again in detail. The electrochemical cell 214 differs from the electrochemical cell 14 by its cathode plate 213 and its first peripheral seal 240, which replaces the first peripheral seal 40. The cathode pole plate 213 differs from the cathode pole plate 13 in that it does not include the irregular regions 30a and 30c and includes an irregular region 230. The irregular region 230 includes a main part 231 and a free edge 232. The irregular region 230 includes a rounded notch 239, the rounded notch 239 belonging to the first peripheral area 21.The rounded notch 239 is delimited by the free edge 232, and the main part 231 frames the rounded notch 239.

[0134] The irregular region 230 is advantageously used to align the cathode polar plates 213 of the stack 5 according to the stacking direction X. The irregular region 230 of an electrochemical cell 14 is aligned with the irregular region 230 of the next electrochemical cell 14 in the stack 5.

[0135] The first peripheral seal 240 is similar to the first peripheral seal 40 and elements identical to those of the first peripheral seal 40 are indicated with the same reference signs as those of the first peripheral seal 40 and are not described again in detail. The first peripheral seal 240 does not include elbows 42, does not include pads 43 and 49, and includes first pads 249, electrically insulating, which are integral with the sealing portion 41. The first pads 249 project from the sealing portion 41 towards the outside of the sealing portion 41 in an extension direction D, which is the average extension direction of the first pad 249. Each first pad 249 projects from the sealing portion 41 towards the outside of the sealing portion 41.When the first peripheral seal 240 is integrated into the electrochemical cell 214, the joint plane P40 and the plate plane P are parallel and the first pads 249 are in contact with the cathode plate 213 and extend over the main part 231, on either side of the rounded notch 239. In a similar manner to what has been described for the first pads 43, 45, 47 and 49, the first pads 249 are advantageously separated from the free edge 232 at least by the minimum distance dmin.

[0136] The pads 249 each comprise a main portion 249a and a joining portion 249b.

[0137] The joining portion 249b connects the main portion 249a to the first peripheral seal 40. The main portion 249a advantageously has a thickness greater than a thickness of the joining portion 249b. The thicknesses of the joining portion and the main portion are preferably less than the thickness of the first peripheral seal 240.

[0138] 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. Peripheral seal (40; 60; 140; 240), for an electrochemical cell (14; 214), the peripheral seal (40; 60; 140; 240) extending along a joint plane (P40; P60; P140) and comprising: a sealing portion (41; 61; 141) forming a closed loop parallel to the joint plane (P40; P60; P140) and configured to be in contact with a first polar plate (13; 213) of the electrochemical cell (14; 214) when the peripheral seal (40; 60; 140; 240) is integrated into the electrochemical cell (14; 214), characterized in that the peripheral seal (40; 60; 140; 240) further comprises at least one pad (43, 45, 47, 49; 65; 143, 145, 147, 149; 249), punctual, electrically insulating, made of the same material as the sealing portion (41; 61; 141), the pad (43, 45, 47, 49; 65; 143, 145, 147, 149; 249) projecting from the sealing portion (41; 61; 141) towards an outside of the sealing portion (41; 61;141), in an extension direction (D) parallel to the joint plane (P40; P60; P140), the pad (43, 45, 47, 49; 65; 143, 145, 147, 149; 249) being configured to be in contact with the first polar plate (13; 213) when the peripheral seal (40; 60; 140; 240) is integrated into the electrochemical cell (14; 214).; 2. Peripheral seal (40; 140) according to claim 1, in which the sealing portion (41; 141) forms a frame comprising an elbow (42; 142), the pad (43; 143) projecting from the sealing portion (41; 141) from the elbow (42; 142).

3. Peripheral seal (40; 140; 240) according to claim 1 or 2, in which the direction of extension (D) is perpendicular to the sealing portion (41; 141), at the level of the pad (47, 49; 147, 149; 249).

4. Peripheral seal (40; 60; 140) according to claim 1 or 2, in which the direction of extension (D) forms an angle of between 1 and 89° with the sealing portion (41; 61; 141) at the level of the pad (43, 45; 65; 143, 145).

5. Peripheral seal (40; 140) according to any one of the preceding claims, in which the pad (49; 149) comprises an orifice (49a; 149a) passing through, perpendicular to the joint plane (P40; P140).

6. Peripheral seal (40; 60; 140) according to any one of the preceding claims, in which a thickness (E40; E60; E140) of the sealing portion (41; 61; 141) measured perpendicular to the joint plane (P40; P60; P140) is greater than a maximum thickness (E45a; E145a; E65a) of the pad, measured perpendicular to the joint plane (P40; P60; P140).

7. A peripheral seal (40; 60; 140; 240) according to any preceding claim, wherein the pad (43, 45; 65; 143, 145; 249) comprises a main portion (43a, 45a; 65a; 143a, 145a; 249a) and a joining portion (43b, 45b; 65b; 143b; 145b; 249b), the joining portion (43b, 45b; 65b; 143b, 145b; 249b) connecting the main portion (43a, 45a; 65a; 143a; 145a; 249a) to the sealing portion (41; 61; 141), and wherein a thickness (E45b; E65b; E143b, E145b; E249b) of the joining part (43b, 45b; 65b; 143b, 145b; 249b), measured perpendicular to the joint plane (P40; P60; P140), is less than a thickness (E45a; E65a; E143a, E145a; E249a) of the main part (43a, 45a; 65a; 143a; 145a; 249a) measured perpendicular to the joint plane (P40; P60; P140).

8. Peripheral seal (40; 60; 140) according to any one of the preceding claims, comprising several pads (43, 45, 47, 49; 65; 143, 145, 147, 149; 249), the pads (43, 45, 47, 49; 65; 143, 145, 147, 149; 249) projecting from the sealing portion (41; 61; 141) towards the outside of the sealing portion (41; 61; 141) while being located at a distance from each other.

9. A polar separator (14; 214) comprising a first polar plate (13; 213) extending along a plate plane (P) perpendicular to a stacking direction (X) and comprising: a circulation field (23), for guiding a circulation of a functional fluid and which is parallel to the plate plane (P); a first peripheral zone (21), parallel to the plate plane (P), surrounding the circulation field (23); and the peripheral seal (40; 240) according to any one of the preceding claims, the sealing portion (41) being in contact with the first peripheral zone (21), such that the closed loop formed by the sealing portion (41) surrounds the circulation field (23), the pad (43, 45, 47, 49; 249) extending over the peripheral zone (21).

10. A polar separator (14; 214) according to claim 9, wherein: the first peripheral zone (21) comprises an irregular region (30a, 30b, 30c; 230), the irregular region (30a, 30b, 30c; 230) comprising a main portion (31a, 31b, 31c; 231) and a free edge (32a, 32b, 32c; 232), the free edge (32a, 32b, 32c; 231) being non-rectilinear and delimiting the main portion (31a, 31b, 31c; 231); and the pad (43, 45, 47, 49; 249) extends over the main part (31a, 31b, 31c; 231) near the free edge (32a, 32b, 32c; 232), being in contact with the main part (31a, 31b, 31c; 231).

11. Polar separator (14; 214) according to claim 10, wherein the pad (43, 45, 47, 49; 249) extends close to the free edge (32a, 32b, 32c; 232) while being at a minimum distance (dmin) from the free edge (32a, 32b, 32c; 232) less than 1 mm, preferably less than 0.8 mm, more preferably less than or equal to 0.5 mm, the minimum distance (dmin) being measured parallel to the plate plane (P).

12. Polar separator (14; 214) according to any one of claims 10 and 11, wherein the pad (45) is a first pad (45), the cell (14; 214) further comprising a second peripheral seal (60), the second peripheral seal (60) comprising a second pad (65), arranged on the main part (31b), the first pad (45) and the second pad (65) being arranged on either side of the first peripheral zone (21), so that the first peripheral zone (21) is interposed between the first pad (45) and the second pad (65) in the stacking direction (X) and the first pad (45) and the second pad (65) are aligned in the stacking direction (X).

13. An electrochemical cell comprising: a polar separator according to any one of claims 9 to 12, a second polar plate (113), parallel to the first polar plate (13), the second polar plate (113) comprising a second peripheral zone (121); and a membrane electrode assembly (80), interposed between the first polar plate (13; 213) and the second polar plate (113) in the stacking direction (X), the membrane electrode assembly (80) comprising: o a central portion (81), comprising a proton exchange polymer membrane (83), o a peripheral portion (82) surrounding the central portion (81), the peripheral portion (82) being interposed between the first peripheral zone (21) and the second peripheral zone (121) in the stacking direction (X), the peripheral seal (40) being interposed between the first peripheral zone (21) and the peripheral portion (82) in the stacking direction (X);and o a gas diffusion layer (86), interposed between the proton exchange polymer membrane (83) and the circulation field (23) in the stacking direction (X).; 14. Fuel cell (1) comprising a stack (5) of cells (14; 214), each cell (14; 214) being according to claim 13, in which the cells (14; 214) are successively superimposed in the stacking direction (X), the second polar plate (113) of each cell (14; 214) being in abutment against the first polar plate (13; 213) of the next cell (14; 214) of the stack (5), following the stacking direction (X).

15. Fuel cell (1) according to claim 14, wherein the polar separator (14; 214) is according to any one of claims 10 to 12, the irregular region (30b) of each cell (14; 214) is aligned with the irregular region (30b) of the next cell (14; 214) in the stack (5), along the stacking direction (X), the respective free edge (32b) of the irregular regions (30b) thus aligned being configured to mechanically cooperate with an alignment rail (18), to align the cells (14; 214) relative to each other, the alignment rail (18) being arranged parallel to the stacking direction (X) and passing through or running along the aligned irregular regions (30b).

16. Vehicle, comprising a fuel cell (1) according to any one of claims 14 or 15.

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