Irrigation spacer for a single fuel cell, single cell and associated fuel cell

Abstract

Irrigation spacer for a single fuel cell, unit cell, and associated fuel cell. This irrigation spacer (600) for a single fuel cell comprises two distribution plates (602A, 602B) stacked flat one on top of the other along a vertical axis (A600). Each distribution plate is cut to form perforations (610) arranged to form a network (612) of channels, each channel having an elongated shape with two opposing longitudinal edges (612), two adjacent channels being separated by a strip (614) of material. Each strip of the first plate (602A) is superimposed, along the vertical axis (A600), with a corresponding strip of the second plate.Each distribution plate includes crossbars (618) that extend through perforations (610) in the thickness of the distribution plate and keep the strips (614) apart, with the crossbars of the first plate offset from the crossbars of the second plate. See Figure 13 for abbreviations.

Description

Title of the invention: Irrigation spacer for a single fuel cell, single cell and associated fuel cell

[0001] The present invention relates to an irrigation spacer for a unit cell of a fuel cell, a unit cell comprising such an irrigation spacer and a fuel cell comprising such a unit cell.

[0002] A fuel cell is a device that generates electricity through an electrochemical reaction between a fuel, for example dihydrogen—also simply called hydrogen—and an oxidant, for example dioxygen—also simply called oxygen—contained in the air. This discussion focuses on proton exchange membrane fuel cells with a solid electrolyte—also known as PEMFCs—which typically comprise a stack of individual cells, each constituting an electrochemical generator.

[0003] Schematically, each unit cell comprises two separators, also called polar plates, between which a solid electrolyte in the form of a proton exchange membrane is interposed. The membrane is made, for example, of a perfluorinated sulfide polymer material. Within each cell, each separator, together with its corresponding membrane, delimits a reactive compartment. One of the two reactive compartments houses a cathode element, while the other reactive compartment houses an anodic element.

[0004] Within the stack, the cells are stacked in such a way as to alternate cathode and anodic elements. In many types of fuel cells, for two adjacent cells, a separator from one of the two cells is located back-to-back with a separator from the other cell. These two separators together form a bipolar separator, also called a bipolar plate. A cooling compartment, through which a cooling fluid such as glycol water circulates, is generally provided between the two separators of the bipolar separator. In other types of fuel cells, particularly in a fuel cell without liquid cooling, the same separator is shared by two adjacent cells, and the cell therefore does not have a cooling compartment.

[0005] Hydrogen, air, and any coolant are referred to as "operating fluids," which are supplied to the fuel cell during its operation. Each reactive compartment housing the cathode element is supplied with air, each reactive compartment housing the anodic element is supplied with hydrogen, and each cooling compartment is supplied with coolant. According to the During the fuel cell's operating phases, the supply of one or more of the operating fluids is done continuously or intermittently.

[0006] The fuel cell thus provides, for each of the reactive and cooling compartments, a respective inlet and outlet to supply each compartment with the corresponding fluid. For proper operation of the fuel cell, the flow field of the corresponding fluid within each compartment is controlled as much as possible, so that the fluids circulate over the entire surface of each compartment, avoiding dead zones where the fluids circulate poorly or not at all.

[0007] It is known to manufacture separators from sheet metal and to create a network of channels directly on the surface of the separators, for example by stamping, to guide the flow of the corresponding fluid within each compartment. For proper operation of the fuel cell, the polar separators have very thin profiles and very tight manufacturing tolerances. As an order of magnitude, a polar separator is typically made from sheet metal 0.1 mm thick, while the channels each have a depth of 0.2 mm to 0.3 mm, with a tolerance of less than 0.01 mm. Manufacturing such a separator is delicate and expensive.

[0008] Another approach consists of placing in each compartment an irrigation spacer forming a network of channels.

[0009] US-5,683,828 and US-10,103,390 each describe, for example, irrigation spacers with a network of channels etched onto the surface of a sheet of metal, respectively by chemical or mechanical etching. However, these manufacturing methods lack precision and remain relatively expensive and difficult to implement.

[0010] CN 111-276-711 describes an irrigation spacer formed of two cut and superimposed plates, so as to form circulation channels for a fuel cell operating fluid. The channels are in the shape of a double helix, which is a source of pressure losses and hinders fluid circulation, particularly when the fluid is a liquid such as a coolant, which is more viscous than a gas.

[0011] It is these problems that the invention intends to remedy in particular, by proposing an irrigation spacer that is simple to manufacture and suitable for the circulation of gaseous or liquid fluids.

[0012] To this end, the invention relates to an irrigation spacer for a unit cell of a fuel cell, the irrigation spacer being configured to be housed in a compartment of the unit cell, in which: - the irrigation spacer comprises two distribution plates, including a first plate and a second plate, the distribution plates each comprising two opposite faces and stacked flat one on top of the other along a height axis orthogonal to a mean plane of the irrigation spacer, - each distribution plate includes perforations, which are formed by cutting the distribution plate, which open onto the two opposite faces of this distribution plate and which are arranged so as to form a network of channels when the two plates are stacked, the network of channels being configured to form a flow field of an operating fluid circulating in the compartment where the irrigation spacer is housed.

[0013] According to the invention - each distribution plate comprises a first portion, in which the perforations have an elongated shape with two opposing longitudinal edges, two adjacent perforations extending along one another and being separated from each other by a band of material, - Each distribution plate includes crossbars, which extend through perforations in the thickness of that distribution plate, and which keep the strips separated from each other, - each strip of the first portion of the first plate is superimposed, along the height axis, with a respective strip of the first portion of the second plate (602B; 702B), so as to form a first portion of the channel network, - in the first portion of the channel network, the crossbeams of the first plate are offset, in the middle plane, relative to the crossbeams of the second plate, so as not to impede the circulation of fluids in the channels of the first portion of the channel network.

[0014] Thanks to the invention, the spacer channel network is formed by simply cutting and then stacking two plates, which is quick and economical. Manufacturing dimensional tolerances are reduced, particularly in the thickness direction, which improves sealing and facilitates assembly with the other elements of the fuel cell stack. Furthermore, since the strips are overlapped, they are in surface contact with each other, which reduces leakage between the two distribution plates and improves electrical conductivity between them. The channel tortuosity is also relatively reduced, thus minimizing pressure losses during the circulation of the fuel cell operating fluids. The channels thus formed are therefore suitable for the circulation of both gaseous and liquid fluids.

[0015] According to advantageous but not obligatory aspects of the invention, such in The irrigation system may incorporate one or more of the following features, taken individually or in any technically permissible combination: - in the first portion of the channel network, each cross connects the two longitudinal edges of each perforation to each other. - For each distribution plate, the material strips of the first portion are parallel to each other. - In the first section of the channel network: • the perforations each have the same width, which is between 0.2 mm and 1.1 mm, and • the bands separating two adjacent perforations each have a width between 0.2 and 0.7 mm. - In the first portion of the channel network, each crossbar has a height equal to the height of the bands adjacent to the perforation in which this crossbar is placed, the height of the crossbars and the height of the bands being measured parallel to the height axis. - Each distribution plate is manufactured by cutting from a sheet of metal and has a thickness between 30 sqm and 300 sqm, preferably between 50 sqm and 100 sqm, preferably also equal, to ±5%, to 75 sqm. - The irrigation spacer comprises a fluid inlet and a fluid outlet, the inlet and outlet being fluidly connected to each other by the channel network, and For each of the distribution plates, each band extends continuously from the input to the output, so that each channel in the channel network extends continuously from the input to the output. - In orthogonal projection onto the mean plane of the spacer, the channels of the first portion of the channel network are straight. - Each distribution plate comprises, in addition to the first portion, a second portion, distinct from the first portion. Within each second portion of the distribution plates, the perforations are parallel to each other, with two adjacent perforations separated by a respective strip. Each strip of the second portion of the first plate is superimposed, along its vertical axis, with a corresponding strip of the second portion of the second plate, thus forming channels of a second portion of the irrigation spacer's channel network. The channels of the second portion of the channel network are parallel to each other. For each distribution plate, each strip of the first portion

[0016]

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[0020]

[0021] continues, continuously, with a respective strip of the second portion, that for each distribution plate, the bands of the first portion of the distribution plates are straight and parallel to each other, the channels of the first portion of the channel network extending along a first flow axis, while the bands of the second portion of the distribution plates are straight and parallel to each other, the channels of the second portion of the channel network extending along a second flow axis, and that the first flow axis and the second flow axis form an angle between them between 1 and 179°, preferably between 30° and 150°, preferably still between 60° and 120°. The invention also relates to a unit cell of a fuel cell stack, comprising: - a proton exchange membrane, with a first face and a second face opposite the first face, - a first separator, adjacent to the first face of the membrane, which delimits with the membrane a first reactive compartment and which hermetically separates the first reactive compartment from a first cooling compartment, - a second separator, which is adjacent to the second face of the membrane and which, together with the membrane, delimits a second reactive compartment, - in which at least one compartment, chosen from: • the first reactive compartment, • the second reactive compartment, and • the first cooling compartment houses an irrigation spacer as defined previously. The invention also relates to a fuel cell, comprising a stack of several unit cells as defined above. The invention will be better understood, and other advantages thereof will become more apparent, in the light of the following description of several embodiments of an irrigation spacer, a unit cell, and a fuel cell, conforming to its principle, given solely by way of example and with reference to the accompanying drawings, in which: - [Fig.1] [Fig.1] is a perspective view of a fuel cell according to the invention; - [Fig. 2] [Fig. 2] represents, on two insets a) and b), two schematic views of the fuel cell of [Fig. 1], observed respectively in partial perspective exploded view and top view, with some parts hidden;

[0022] - [Fig.3] [Fig.3] represents respectively, on two inserts a) and b), a shirt and a unit cell of the fuel cell of [Fig.1], the unit cell conforming to an embodiment;

[0023] - [Fig.4] [Fig.4] is an exploded perspective view of the unit cell of the [Fig.3], some parts being hidden;

[0024] - [Fig.5] [Fig.5] represents, on two insets a) and b), a partial perspective and exploded view of a first compartment of the unit cell of the [Fig.3], observed at two different scales and in section on the insert b);

[0025] - [Fig.6] [Fig.6] represents, on two insets a) and b), a partial perspective and exploded view of a unit cell conforming to another embodiment, observed at two different scales and in cross-section on insert b),

[0026] - [Fig.7] [Fig.7] represents an exploded and partial perspective of a cell unitary conforming to another embodiment;

[0027] - [Fig.8] [Fig.8] represents a partial and exploded perspective of a second com unit cell compartment of the [Fig.3];

[0028] - [Fig.9] [Fig.9] represents respectively, on two inserts a) and b), a partial and exploded perspective of a unit cell conforming to two other embodiments of the invention;

[0029] - [Fig. 10] [Fig. 10] schematically represents a cross-section partial of an embodiment of the unit cell of the [Fig.3];

[0030] - [Fig. 11] [Fig. 11] schematically represents a cross-section partial of a unit cell conforming to another embodiment;

[0031] - [Fig. 12] [Fig. 12] is a perspective view of a first spacer irrigation of the unit cell of the [Fig.3];

[0032] - [Fig. 13] [Fig. 13] represents respectively, on three inserts a), b) and c), a detail XlIIa of the irrigation spacer of [Fig.12], the same detail observed in exploded perspective and a diagram illustrating a principle of operation of the irrigation spacer of [Fig. 12];

[0033] - [Fig. 14] [Fig. 14] is a perspective view of a second spacer irrigation of the unit cell of the [Fig.3]; and

[0034] - [Fig. 15] [Fig. 15] is a larger scale and exploded perspective view of a detail XV in [Fig. 14],

[0035] A fuel cell 20 is shown in [Fig. 1]. The fuel cell 20, also referred to simply as "fuel cell 20" hereafter, comprises a casing 22, which includes a sleeve 24. The sleeve 24 has the shape of a hollow cylinder, extending along a fuel cell axis A20 and having a substantially rectangular cross-section. The sleeve 24 provides an internal volume V24 with two opposing openings, the openings being closed by two covers 26A and 26B. The sleeve 24 and the covers 26A and S6B are preferably made of electrically insulating material, such as a polymer material or a fiber-reinforced polymer material, or are covered, at least on one inner face, with an electrically insulating material.

[0036] Fluid passages are provided through the housing 22 to allow the passage of operating fluids for the fuel cell 20. The operating fluids comprise three fluids: two gaseous fluids, in this case air and dihydrogen, and a dielectric heat transfer fluid, for example a liquid, in this case glycol water. The fluid passages are formed by fluid connections, which are provided here on the cover 26A, located at the top of Figures 1 and 2. Alternatively, all or part of the fluid connections are provided on the cover 26B. Alternatively, all or part of the fluid connections are located on the sleeve 24.

[0037] The stack 20 thus comprises three pairs of fluid connections, each pair being intended for the circulation of a specific operating fluid. The three pairs of fluid connections include a first pair of fittings 28A, a second pair of fittings 28B, and a third pair of fittings 28C. For each pair of fittings, one of the fittings, called the "inlet fitting," is intended for the intake of the corresponding operating fluid, while the other fitting, called the "outlet fitting," is intended for the extraction of the corresponding operating fluid. In the figures, the direction of flow of the operating fluids is schematically represented by arbitrarily oriented arrows, bearing in mind that this may be different in reality.

[0038] In [Fig.2], the stack 20 is schematically represented in exploded perspective, with the cover 26A positioned away from the sleeve 24. The fittings 28A, 28B and 28C are schematically represented by openings through the cover 26A. The sleeve 24 is shown in isolation in [Fig.3] a).

[0039] The internal volume V24 of the sleeve 24 houses a stack 50. The stack 50 comprises an external surface S50, which has a cylindrical shape centered on a stacking axis A50 and an overall rectangular cross-section. When the stack 50 is received into the internal volume V24, the stacking axis A50 coincides with the stack axis A20.

[0040] The stack 50 is formed of several unit cells 100, which are stacked along the stacking axis A50. A unit cell 100 is shown in isolation in [Fig. 3] b), and in exploded perspective in [Fig. 4]. Each unit cell 100 has a flattened shape, which extends along a mean plane P50 orthogonal to the stacking axis A50. In other words, the mean plane P50 is a plane transverse to the stacking axis A50. Each unit cell 100 – also referred to simply as "cell 100" hereafter – has, in projection onto the mean plane P50, an external contour C100. It is understood that the section of the external surface S50 of the stacking 50 corresponds to the external contour Cl00 of each unit cell 100.

[0041] The external surface S50 of the stack 50 provides retaining elements 52, which are configured to cooperate with complementary elements 30 provided in the internal volume V24 of the sleeve 24, so as to maintain the stack 50 within the internal volume V24 and to provide a peripheral volume V50 between the stack 50 and the sleeve 24. The peripheral volume V50 is therefore a portion of the internal volume V24, which is distributed around the stack 50.

[0042] The retaining members 52 and the complementary members 30 are provided, respectively, along the external surface S50 parallel to the stack axis A50, and along the jacket 24 parallel to the stack axis A20 and include sealing elements, so as to divide the peripheral volume V50 into several circulation channels for the operating fluids of the fuel cell 20. Advantageously, the retaining members 52 and the complementary members 30 provide electrical insulation between the stack 50 and the jacket 24.

[0043] Each circulation conduit is fluidically connected to a respective fitting 28A, 28B or 28C, so as to ensure the circulation of the operating fluids around the stack 50, and therefore around each unit cell 100.

[0044] The fuel cell 20 here provides six circulation channels, which are respectively associated in pairs with the three operating fluids of the fuel cell. These six circulation channels thus include a first pair of channels 38A, which are fluidly connected to the first pair of fittings 28A, a second pair of channels 38B, which are fluidly connected to the second pair of fittings 28B, and a third pair of channels 38C, which are fluidly connected to the third pair of fittings 28C.

[0045] Each circulation conduit 38A, 38B or 38C is thus separated, in a sealed manner, from the neighboring conduits. In this description, "sealed" means sealed against any of the operating fluids, liquid or gaseous, of the fuel cell 20, in particular sealed against hydrogen, which has the greatest tendency to leak due to its small molecular size and low viscosity compared to the other operating fluids.

[0046] In the example illustrated more particularly by Figures 1 and 3, the sleeve 24 is therefore an external wall of the stack 20, the sleeve 24 delimiting the circulation channels 38A, 38B or 38C in which a fluid flows under a pressure greater than atmospheric pressure. Even if this pressure is generally less than 5 bar absolute, or even less than 3 bar absolute, it is necessary to take into account the pressure difference with atmospheric pressure outside the sleeve 24, ensuring in particular that the sleeve 24 does not deform (particularly bulging) to the point of compromising the seal between the circulation ducts 38A, 38B, or 38C. In the illustrated example, to limit bulging deformation, especially of the larger faces of the sleeve 24, external reinforcements have been provided. In the example, the external reinforcements are independent of the sleeve 24; they are therefore attached to the sleeve and fixed to the outside of the sleeve 24, each bearing against one face (here, a flat outer face) of the sleeve 24. Each external reinforcement extends along the pier axis A20 between two ends. In the example, each end is fixed, for example, by screwing, to the corresponding cover 26A or 26B. Alternatively, the external reinforcement(s) may be fixed exclusively to the sleeve 24, or even fixed on one side to the sleeve 24 and on the other side to only one of the two covers. Each external reinforcement has a central body resting on the corresponding external face of the sleeve 24.In the illustrated example, only two external reinforcements are provided, one on each of the two opposite faces of the liner 24, which have the largest surface area and therefore present the greatest risk of deformation due to pressure in the circulation ducts 38A, 38B, or 38C. However, external reinforcements could also be provided for each external face, in particular for each flat external face of the liner 24. In the illustrated example, the central body of an external reinforcement has a transverse width, along a direction orthoradial to the pier axis A20 and parallel to the corresponding external face of the liner 24, which is preferably greater than or equal to 50% of the transverse width of said corresponding external face on which it rests, so that only one external reinforcement is necessary for the corresponding external face.However, for a given external face of the liner 24, several distinct individual reinforcements could be provided, offset from one another along the transverse direction, and therefore each with a small transverse width. In the illustrated example, the external reinforcement has stiffeners, here integral with the central body, forming an additional thickness on the central body along a radial direction perpendicular to the pier axis A20 and perpendicular to the corresponding external face of the liner 24. Advantageously, the stiffener(s) have a radial thickness, along the radial direction, which varies along the direction of the pier axis A20, with a smaller radial thickness at both ends, and conversely, a greater radial thickness at the center along this direction.This allows for optimization of the stiffener's rigidity by adapting it to the stresses experienced by the sleeve 24 at various points along its length, due to the pressure inside the ducts. The added external reinforcement(s) are preferably made of metal, for example, aluminum or an aluminum alloy, for example, in the form of a molded aluminum alloy part. Alternatively, the added external reinforcement(s) are made of a polymer material, preferably a composite material combining a polymer resin and reinforcements. for example in the form of glass, carbon and / or aramid fibers. According to yet another variant, similar reinforcements are integrated into the liner 24, in other words made in one piece with the liner, thus giving the liner a geometry optimized to resist the stresses due to fluid pressures in the circulation conduits 3 8A, 38B or 38C.

[0047] The individual cells 100 of the stack 50 are preferably identical to each other. We now describe in detail the individual cell 100.

[0048] As illustrated in [Fig. 4], the cell 100 comprises several walls 102, which are continuous and sealed and are stacked one on top of the other along the stacking axis A50. The walls 102 include a first separator 110, a second separator 120, and a proton exchange membrane 130. The wall 102 formed by the membrane 130 is interposed between the first separator 110 and the second separator 120. The walls 102 delimit compartments V100 of the unit cell 100.

[0049] Still on [Fig. 4], the second separator 120 is shown schematically in dashed lines. The first separator 110 and the second separator 120 are preferably identical to each other and are here made by cutting a metal sheet, for example a stainless steel sheet.

[0050] The membrane 130, also called PEM for "Proton Exchange Membrane", is here made in the form of a polymer layer 130A. Generally, on either side of the membrane 130, in each of the compartments V100 delimited by the membrane 130, a gas diffusion layer 130B is placed, such that the membrane 130 is sandwiched between the two gas diffusion layers 130B. The polymer layer 130A is here made of a fluorinated polymer material, for example known by the trade name Nafion.

[0051] In the illustrated example, the polymer layer 130A is coated on both sides with a catalyst layer, the membrane 130 being referred to as CCM for "Catalyst Coated Membrane". The catalyst layers are not shown. The membrane 130, the gas diffusion layers 130A and 130B, and the associated catalyst layers together form what is generally called an MEA, an acronym for "Membrane Electrode Assembly".

[0052] As an alternative not illustrated, at least one of the catalyst layers is deposited on one or the other of two gas diffusion layers 130B, between the gas diffusion layer 130B and the polymer layer 130A which are adjacent.

[0053] The polymer layer 130A is impermeable to reactive gases, hydrogen or oxygen, but allows the diffusion of H+ protons through it. The gas diffusion layers 130B, also called GDLs (for "gas diffusion layer"), are porous to reactive gases and are, for example, made primarily of carbon fibers. overlapped and compressed. The gas diffusion layers 130B may optionally be coated on their face in contact with the membrane 130A with an ionomer that may be of the same nature as the material of the polymer layer 130A. The structure of the membrane 130 is not detailed further.

[0054] The membrane 130 comprises a first face 132 and a second face 134 opposite the first face 132. The first face 132 and the second face 134 extend parallel to the mid-plane P50. The first face 132 is oriented towards the first separator 110. The first separator 110, together with the membrane 130, delimits a first reactive compartment VI32, which is configured to receive a first operating fluid of the fuel cell 20. The first reactive compartment VI32 is, for example, an anodic compartment of the unit cell 100, meaning that the first operating fluid is hydrogen. Thus, the first operating fluid is a gaseous fluid. The first reactive compartment VI32 is one of the compartments VI100 of the cell 100.

[0055] The second face 134 is oriented towards the second separator 120. The second separator 120, together with the membrane 130, delimits a second reactive compartment VI34, which is configured to receive a second operating fluid for the fuel cell. The second reactive compartment VI34 is, for example, a cathode compartment of the unit cell 100; that is, the operating fluid circulating in this compartment is air, which contains oxygen. Thus, the second operating fluid is a gaseous fluid. The second reactive compartment VI34 is another of the compartments VI00 of the cell 100.

[0056] It is understood that when three unit cells 100 are stacked one on top of the other, with a bottom cell 100, a middle cell 100 and a top cell 100, the first separator 110 of the middle cell is adjacent to the second separator 120 of the top cell 100.

[0057] In the illustrated example, the first separator 110 of the middle cell 100 and the second separator 120 of the top cell delimit between themselves a first cooling compartment V136 of the middle cell 100.

[0058] The first cooling compartment VI36 is therefore common to two adjacent cells 100. The second separator 120 of the middle cell 100 and the first separator 110 of the bottom cell 100 delimit between themselves a second cooling compartment V138 of the middle cell. For two stacked unit cells 100, the first cooling compartment VI36 of the bottom cell is therefore, for the top cell, a second compartment VI38.

[0059] More generally, for the cell 100 described, each cooling compartment V136 and V138 is configured to receive a third operating fluid for the fuel cell 20. The third operating fluid is here a cooling fluid such as glycol-water. Thus, the third operating fluid is a liquid fluid at the operating temperatures of the pile 20. More generally, the first separator 110 is configured to hermetically seal the first reactive compartment VI32 from the first cooling compartment V136.

[0060] In the illustrated example, each unit cell 100 therefore comprises three compartments V100, namely the first reactive compartment V132, the second reactive compartment VI34, and the first cooling compartment VI36. Each of these compartments VI00 is respectively associated with a fuel cell operating fluid 20.

[0061] The fuel cell 20 houses, in each of the compartments V100 of the unit cell 100, an irrigation spacer. More specifically, the second reactive compartment VI34 houses an irrigation spacer 600 of a first type, according to a first embodiment, while the first reactive compartment VI32 houses an irrigation spacer 700 of a second type, according to another embodiment. The first cooling compartment VI36 also houses another example of the second type of spacer 700.

[0062] The irrigation spacers 600 or 700 are configured to define the circulation, within each compartment VI00, of the corresponding operating fluid. The irrigation spacers 600 and 700 are described later in this description. When the stack 20 is assembled, the first separator 110, the second separator 120, the membrane 130, and the spacers 600 and 700 are supported by one another. Preferably, the gas diffusion layers 130B are stacked along the stacking axis 150, with axial clamping between an irrigation spacer 600 or 700 and the corresponding face of the membrane 130, so as to ensure good electrical conduction between these stacked elements.

[0063] According to another aspect, the unit cell 100 also comprises a sealing structure 200 ([Fig. 5]). The sealing structure comprises frames 210, each made of a polymer material and stacked along the stacking axis A50. The frames 210 are arranged around the periphery of the walls 102 and the compartments VI00 of the unit cell 100.

[0064] The principles of the sealing structure 200 are described with reference to [Fig. 5], where two walls 102 of the unit cell 100, delimiting a single compartment V100, are shown. The wall 102 at the top of [Fig. 5] a) is here the membrane 130, while the wall 102 at the bottom of [Fig. 5] a) is the second separator 120. The compartment shown is therefore the second reactive compartment VI34, knowing that the principles described can be transposed to the other compartments V100 of the unit cell 100 and to the corresponding walls 102.

[0065] The remainder of the unit cell 100, in particular the irrigation spacer 600 or the diffusion layer 130B, is not shown so as not to overload the figures which are intended to represent this sealing structure more specifically. For the parts of the description which concern the elements of the sealing structure 200, when two of these elements comprise surfaces which face each other and are oriented orthogonally to the stacking axis A50, these surfaces (and by extension these elements) are said to be "adjacent" to each other, whereas when these two surfaces are parallel to the stacking axis A50, these surfaces are said to be "opposite" to each other.

[0066] In the illustrated example, the frames 210 of the sealing structure 200 include wall frames 220, each wall frame 220 being coplanar with and surrounding a respective wall 102. In [Fig. 5] a), the wall frames 220 and the associated walls are shown offset to facilitate distinction between the parts, while in [Fig. 5] b), the wall frames 220 are shown coplanar with the respective walls 102, as in reality. Each wall frame 220 and the corresponding wall 102 are thus opposite each other. Each wall frame 220 has a thickness substantially equal, for example, to ±10%, to a thickness of the corresponding wall 102, the thicknesses being measured parallel to the stacking axis A50.

[0067] The frames 210 of the sealing structure 200 also include compartment frames 230. Each compartment frame 230 is arranged around the periphery of the corresponding compartment VI00, here the second reactive compartment VI34. Only one compartment frame 230 is shown in [Fig. 5]. In this embodiment of the sealing structure 200, each compartment frame 230 is formed from a single piece.

[0068] Each frame 210 of the sealing structure 200 is generally ring-shaped, in this example a rectangular ring, and is formed in a plate of a sealing material, for example by cutting. The wall frames 220 are made of an electrically insulating material, preferably a polymer material, for example polyethylene terephthalate, also known as PET.

[0069] Each frame 210 comprises two faces 213, which are opposite each other and extend parallel to the mean plane P50, an internal edge 214, which connects the two faces 213 to each other and is oriented towards an internal side of the unit cell 100, and an external edge 215, which is opposite the internal edge 214 and which connects the two faces 213 to each other. For each frame 210, the internal edge 214 defines, in projection onto the mean plane P50, an internal contour of this frame 210, while the external edge 215 defines, in projection onto the mean plane P50, an external contour of this frame 210.

[0070] In the case of the wall frames 220, the inner edge 214 extends opposite the corresponding wall 102. In the case of the compartment frames 230, the inner edge 214 is oriented towards the corresponding compartment V100 and delimits this compartment V100 radially to the stacking axis A50.

[0071] Similarly, each wall 102 comprises two faces 103 which are opposite each other and which extend parallel to the average plane P50 and an external edge 105 which connects the two faces 103 to each other. For each wall 102, the corresponding external edge 105 is oriented towards the outside of the cell 100. The external edge 105 of each wall 102 defines, in projection onto the average plane P50, an external contour of this wall 102.

[0072] The inner edge 214 of each wall frame 220 is arranged opposite the outer edge 105 of the associated wall 102, the inner edge 214 of the wall frame 220 and the outer edge 105 of the opposite wall 102 being separated, radially to the stacking axis A50, by a peripheral gap 1220. Each wall 102 is therefore associated with a peripheral gap 1220 specific to that wall 102 and to the corresponding opposite wall frame 220. Consequently, each wall frame 220 is therefore associated with a peripheral gap 1220 specific to that wall frame 220 and to the corresponding opposite wall 102.

[0073] The peripheral gap 1220 is as small as possible. The peripheral gap 1220 is typically between 0 mm (millimeter) and 0.2 mm. In reality, the peripheral gap 1220 is not zero, particularly due to manufacturing tolerances and assembly clearances. In the illustrated example, 1220 is equal to 0.1 mm.

[0074] The sealing structure 200 also includes layers of adhesives 240, which are interleaved between each of the frames 210 of the sealing structure so as to fix the frames 210 to each other in a watertight manner. Each layer of adhesive 240 is thus sandwiched between two frames 210 and is therefore adjacent to each of these two frames 210. In the example of [Fig. 5], two layers of adhesive 240 are shown, each layer of adhesive 240 being sandwiched between, on the one hand, the compartment frame 230 and, on the other hand, one of the walls 102 and the wall frame 220 associated with this wall 102. In other words, each layer of adhesive 240 is sandwiched between, on the one hand, the corresponding compartment frame 230 and, on the other hand, the wall 102 and the wall frame 220 adjacent to this compartment frame 230.

[0075] Each layer of adhesive 240 is made of a sealing material, preferably a contact adhesive, also known as PSA for Pressure Sensitive Adhesive. Non-limiting examples of adhesives include acrylic adhesives. Each layer of adhesive 240 is made of an electrically insulating material. Thus, the sealing structure 200, formed by assembling the frames 210 joined to each other by layers of adhesive, ensures not only a seal between two neighboring V100 compartments, but also the sealing and electrical insulation of each VI00 compartment from the outside of the unit cell.

[0076] Advantageously, each layer of adhesive 240 extends continuously over the surfaces of the frames 210 and / or walls 102 that this layer of adhesive 240 bonds together. For example, for assembling two faces, the layer of adhesive 240 is applied by coating to one of the faces to be joined, and then the second face is pressed onto the layer of adhesive 240. In [Fig. 5] a), the two layers of adhesive 240 have a shape identical to the compartment frame 230, which is sandwiched between these two layers of adhesive 240.

[0077] Preferably, the compartment frame 230 undergoes an adhesive coating on each of its two opposite faces before being cut and assembled to the rest of the sealing structure 240.

[0078] In the illustrated example, the compartment frame 230 is intercalated, along the stacking axis A50, between two walls 102, and between the two wall frames 220 which are coplanar with the two walls 102. The compartment frame 230 is thus adjacent to these two wall frames 220.

[0079] For each of these walls 102 adjacent to the compartment frame 230, the internal contour of the compartment frame 230 is included, in projection along the stacking axis A50, in an external contour of the adjacent wall 102, so that an annular portion of the wall 102 faces, along the stacking axis 102, a complementary portion of the compartment frame 230 and forms a first overlap S231 of the compartment frame 230 on this wall 102. Schematically, the first overlap S231 is a portion of a face 103 of the wall 102, which corresponds to the projection, parallel to the stacking axis A50, of the compartment frame 230 on the adjacent wall 102.

[0080] For each of the wall frames 220 associated with the walls 102 adjacent to the compartment frame 230, an internal contour of the wall frame 220 is included, in projection along the stacking axis A50, within the external contour of the compartment frame 230, such that an annular portion of the wall frame 220 faces a complementary portion of the compartment frame 230 and forms a second overlap S232 of the compartment frame 230 onto this wall frame 220. The second overlap S232 corresponds to the projection, parallel to the stacking axis A50, of the compartment frame 230 onto the adjacent wall frame 220. Thus, the second overlap 232 here corresponds to that face 223 of the wall frame 220 which is oriented towards the compartment frame in question.

[0081] Preferably, the external contours of all the frames 210 of the sealing structure 200 are superimposed one on the other along the stacking axis A50, the external edges of all the frames of all the sealing structures together an external surface S100 of the unit cell 100. The external surface S50 of the stack 50 corresponds to the union of the external surfaces S100 of the unit cells 100 that make up this stack 50. Optionally, during the assembly of the stack 50, the external surface S50 is rectified after the assembly of the unit cells 100, so that the external surface S50 is smooth.

[0082] For the adhesive layer 240 interposed between the compartment frame 230 and the adjacent wall 102, this adhesive layer 240 includes a first portion, called the first portion of layer 241, which extends opposite the first overlap S231 between the compartment frame 230 and the adjacent wall 102, so as to fix, in a watertight manner, this compartment frame 230 to the adjacent wall 102.

[0083] Similarly, this adhesive layer 240 includes a second portion, referred to as the second layer portion 242, which extends opposite the second overlap S232 between the compartment frame 230 and the adjacent wall frame 220, so as to fix, in a watertight manner, this compartment frame 230 to this wall frame 220.

[0084] The first portion of layer 241 and the second portion of layer 242 are arranged in the same plane transverse to the stacking axis A50. The first portion of layer 241 is, in this transverse plane, surrounded by the second portion of layer 242.

[0085] Advantageously, the adhesive layer 240 includes a third portion, called the third portion of layer 243, which is radially intercalated, in the same plane transverse to the stacking axis A50, between the first portion of layer 241 and the second portion of layer 242 and which therefore unites the first portion of layer 241 and the second portion of layer 242 to each other. The third portion of layer 243 of the adhesive layer is located opposite, along the stacking axis A50, the peripheral gap 1220. The third portion of layer 243 of the adhesive layer 240 continuously connects the first layer 242 to the second portion of layer 242. In other words, the first portion of layer 241 of adhesive and the second portion of layer 242 of adhesive are part of the same continuous layer, here the adhesive layer 240, which extends over one face of the compartment frame 230, so as to cover the peripheral gap 1220 opposite the compartment frame 230.

[0086] The first cover S231 has a leakage length L231, which is equal to a minimum distance, measured parallel to the mean plane P50, between any two points belonging respectively to the inner edge 214 of the corresponding compartment frame 230 and the outer edge 105 of the corresponding adjacent wall 102. In the example of [Fig. 5], the leakage length L231 is the length of the shortest path between the compartment V100 and the peripheral gap 1220, passing between the compartment frame 230 and the adjacent wall 102 considered.

[0087] Similarly, the second cover S232 has a leakage length L232, which is equal to a minimum distance, measured parallel to the mean plane P50, between any two points belonging respectively to the outer edge 215 of the corresponding compartment frame 230 and the inner edge 214 of the corresponding adjacent wall frame 220. In the example of [Fig. 5], the leakage length L232 of the second overlap S232 is the length of the shortest path between the peripheral gap 1220 and the outside of the unit cell 100, passing between the compartment frame 230 and the adjacent wall frame 220 under consideration.

[0088] Each leakage length L231 or L232 is greater than or equal to 1 mm, preferably greater than or equal to 2 mm, and even more preferably greater than or equal to 3 mm. This ensures a seal greater than a minimum value, firstly, between each of the compartments V100 and the outside of the cell 100 and, secondly, between two adjacent compartments V100.

[0089] Preferably, the compartment frame 230 and the two associated layers of adhesives 240 are manufactured by coating both sides of the compartment frame 230 with an adhesive material, the compartment frame 230 thus coated then being cut to the desired shape, before being assembled to the other elements of the unit cell 100.

[0090] The assembly formed by the compartment frame 230 coated with the two associated adhesive layers 240 thus forms a frame known as a "double-sided adhesive frame." The compartment frame 230 thus forms a continuous and watertight core of this double-sided adhesive frame. Advantageously, during the manufacture of the unit cell 100, a double-sided adhesive plate is provided. This double-sided adhesive plate comprises a continuous, watertight core, here made of PET, coated on both sides with an adhesive material. The adhesive material is, for example, deposited by a coating process on both sides of the core. This double-sided adhesive plate is then cut to the desired geometry, so as to form, in a single step, the compartment frame 230 and the two associated adhesive layers 240.

[0091] Such a sealing structure 200 does not include any fluid inlet or outlet passages in the associated compartment VI00. If such an inlet and / or type of fluid is to be provided in the compartment, it is necessary, with this sealing structure 200, to provide it elsewhere, for example in one of the walls 102 that delimit the compartment.

[0092] A sealing structure 300, according to another embodiment, is shown in [Fig. 6]. The sealing structure 300 differs from the sealing structure 200 described previously in that the sealing structure 300 comprises a compartment frame which is made in the form of a transfer frame 330 through which two fluid passages 332 are provided, so as to allow the operating fluid corresponding to compartment V100 to circulate. A single passage of Fluid 332 is shown in [Fig.6]. The transfer frames 330 are therefore part of the frames 210. In this embodiment of the sealing structure 300, each compartment frame 330 comprises only the transfer frame.

[0093] One of the two fluid passages 332 is an inlet for the working fluid, while the other passage 332 is an outlet for the working fluid, the terms "inlet" and "outlet" depending on the direction of flow of the working fluid. The fluid passages 332 thus connect compartment VI00 and the exterior of cell 100.

[0094] Preferably, the fluid passages 332 are provided when cutting the transfer frame 330, the transfer frame 330 being sandwiched between the two layers of adhesive 240, so as to secure, in a watertight manner, with respect to the outside, the transfer frame 330 to the adjacent wall frames 220 and to the associated walls 102.

[0095] As an alternative not shown, a fluid passage is formed by a partial recess, in the direction of the stacking axis A50, of the transfer frame, such a recess having a depth along the stacking direction less than the thickness of the transfer frame and a circumferential extent.

[0096] Each passage 332 opens into the associated compartment V100 through an internal mouth 334, which is provided on the internal edge 214 of the transfer frame 330. Each passage 332 opens outside the compartment V100 through an external mouth 335.

[0097] Each passage 332 thus comprises an internal portion 334B, which opens via the internal inlet 334 into the corresponding compartment VI00. The internal portion 334B of each passage 332 is formed within the thickness of the transfer frame 330. This arrangement makes it possible to economically incorporate the passages 332 within each of the transfer frames 330, so as to supply each compartment VI00 with the corresponding operating fluid.

[0098] In the illustrated example, the external opening 335 of each passage 332 of the transfer frame 330 is advantageously provided on the external edge 215 of the transfer frame 335, so as to communicate fluidly with one of the circulation conduits 38A, 38B or 38C. One of the passages 332 of a transfer frame 330 thus communicates with one of the circulation conduits 38A, 38B or 38C while the other of the passages 332 of this same transfer frame 330 communicates with the other of the circulation conduits 38A, 38B or 38C which belongs to the same pair of conduits.

[0099] In other words, for each of the two passages 332 of the same transfer frame 330, the external opening 335 associated with this passage 332 opens onto the external edge 215 of this transfer frame 330 in a distinct conduit among the circulation conduits of the associated pair.

[0100] In an alternative not illustrated, the external mouth 335 is arranged differently, for example axially oriented and is arranged on one of the faces 213 of the transfer frame 330, the external mouths then preferably being aligned along the stacking axis A50 so as to form chimneys, which extend through the frames 210, these chimneys being provided for the circulation of the operating fluids, taking up an arrangement known in the field of so-called "internal manifold" polar plates.

[0101] Advantageously, each passage 332 houses fins 336 for guiding the associated working fluid. Alternatively, only one of the two passages 332 includes the fins 336. Within each fluid passage 332, the fins 336 form pillars, which keep the two layers of adhesive 240 associated with the transfer frame 330 at a distance. Two adjacent fins 336 define a channel between them. Each fluid passage 332 is therefore formed by the union of the channels defined between the fins 336. The shape of each fin 336 is chosen so as to impede the flow of the working fluids passing through the passages 332 as little as possible, while ensuring the transfer of the mechanical clamping forces of the stack 50, these clamping forces being parallel to the stack axis A50.

[0102] The fins 336 are preferably formed, during the manufacture of the transfer frame 330, by cutting out a portion of this transfer frame 330. The fins 336 thus have the same thickness as the rest of the transfer frame 330. When the cell 100 is assembled, the fins 336 are held in place by means of the adhesive layers arranged on either side of the transfer frame 330, here the adhesive layers 240, between which the transfer frame 330 is sandwiched. The fins 336 are advantageously spaced apart within the corresponding passage 332, so as to direct the flow of the associated operating fluid. Preferably, the fins 336 are evenly distributed within the corresponding passage 332.

[0103] A sealing structure 400, according to another embodiment, is shown in [Fig.7]. The sealing structure 400 differs from the sealing structure 300 described previously in that the sealing structure 400 comprises a compartment frame 430 which includes, in addition to the transfer frame 330 sandwiched between the two corresponding adhesive layers 240, an additional frame, called the first sealing frame 432, which is sandwiched between the transfer frame 330 and one of the adhesive layers 240 associated with this transfer frame 330. The first sealing frame 432 is thus adjacent to a wall 102, to which this first sealing frame 432 is fixed by one of the adhesive layers 240. In other words, the first sealing frame 432 is sandwiched between, on the one hand, the transfer frame 330 and, on the other hand, one of the two walls 102 adjacent to this transfer frame 330. In the example of [Fig. 7], the first Sealing frame 432 is associated with wall 102 and wall frame 220 located at the bottom of the figure.

[0104] The compartment frame 430 also includes an adhesive film 440, which is interposed between the first sealing frame 432 and the transfer frame 330, so as to fix the transfer frame 330 to the adjacent first sealing frame 432.

[0105] Preferably, the adhesive film 440 is made of a sufficiently hard material, chosen to prevent adhesive from bridging, particularly between the fins 336, under pressure, and thus to avoid obstruction of the fluid passages 332. The adhesive film 440 includes tabs 441, which correspond to the fins 336 of the transfer frame 330. The tabs 441 form a discontinuous portion of the adhesive film 440. In an alternative not shown, the adhesive film 440 does not include tabs and is continuous in the circumferential direction around the stacking axis A50, in the same manner as the adhesive layers 240.

[0106] The transfer frame 330, and in particular the fins 336, are thus fixed to the first sealing frame 432 by the first adhesive film 440, while this first sealing frame 432 is fixed in a hermetic manner to the adjacent wall 102, and to the wall frame 220 opposite this wall 102, by the corresponding layer of adhesive 240.

[0107] The sealing frame 432, which extends continuously in the radial and circumferential directions around the stacking axis A50, faces the peripheral gap 1220 formed between this wall 102 and the opposite wall frame 210, thus providing the adhesive layer 240 with continuous support, which improves the sealing of the corresponding compartment V100 compared to the situation without a sealing frame 432. The presence of a sealing frame 432 is particularly advantageous in the case where the working fluid circulating in the compartment V100 is a gas, in other words in the case where the transfer frame 330 is formed around the first reactive compartment VI32 or around the second reactive compartment VI34, where hydrogen and air respectively circulate.

[0108] Preferably, the sealing frame 432 has the same shape, in the sense of the same internal and external contour, as the transfer frame of which it is a part. Similarly, preferably, the adhesive film 440 has the same shape, in the sense of the same internal and external contour, as the first sealing frame 432 and the corresponding transfer frame.

[0109] Thus, the sealing frames 432 are preferably adjacent to the membrane 130, and to the wall frame opposite the membrane 130, on the side where the operating fluid is hydrogen, to avoid the risk of hydrogen contamination on the other side of the membrane 130. Preferably still, sealing frames 432 are arranged in each of the reactive compartments V132 and V134, on either side of the membrane 130, so as to prevent gas transfers between the two compartments. reactive compartments V132 and V134.

[0110] Preferably, the sealing frame 432 and the associated adhesive layer 240 are manufactured by coating one of the two faces of the sealing frame 432 with an adhesive material, the sealing frame 432 thus coated then being cut to the desired shape, before being assembled to the other elements of the unit cell 100.

[0111] The assembly formed by the sealing frame 432 coated with an associated adhesive layer 240 thus forms a frame known as a "single-sided adhesive frame." The sealing frame 432 thus forms a continuous and watertight core of this single-sided adhesive frame, this continuity being radial and circumferential. Advantageously, during the manufacture of the unit cell 100, a single-sided adhesive plate is provided, this single-sided adhesive plate comprising a continuous watertight core, here made of PET, coated on one of its two faces with an adhesive material. The adhesive material is, for example, deposited by coating on one of the faces of the core. This single-sided adhesive plate is then cut to the desired geometry, so as to form, in a single step, the sealing frame 432 and the associated adhesive layer 240, the two being continuous both radially and circumferentially over the entire extent of the sealing frame 432.

[0112] A sealing structure 500, according to another embodiment, is shown in [Fig. 8]. The sealing structure 500 differs from the sealing structure 400 described previously, in that the sealing structure 500 comprises, for each transfer frame 330, two sealing frames 432, which are arranged on either side of the transfer frame 330. The sealing structure 500 also comprises a second adhesive film 440, which is interposed between the second sealing frame 432 and the compartment frame 330.

[0113] Compared to the sealing structures 300 and 400 described previously with reference to Figures 6 and 7, in the case of the sealing structure 500 shown in [Fig. 8], the surfaces of the adhesive films 440 facing the fluid passages 332 are smaller, which reduces the risk of contamination of compartment V100 and of the operating fluid circulating in this compartment V100. The risk of obstruction of the fluid passages 332 by the thinning of the adhesive films 442 is also reduced.

[0114] The first sealing frame 432 and the second sealing frame 432 are each interposed between, on the one hand, the transfer frame 330 and, on the other hand, one of the two respective adhesive layers 240. The second sealing frame 432 is, on the one hand, fixed to the wall 102 and the corresponding wall frame 210 by the corresponding adhesive layer 240 and, on the other hand, fixed to the transfer frame 330 by means of the second adhesive film 440. In other words, in this embodiment of the sealing structure 500, the transfer frame 330, the two sealing frames 432, and the two adhesive films 440 together form a compartment frame 530 of this structure sealing.

[0115] Advantageously, for each of the two sealing frames 432, the associated adhesive layer 240 is coated onto the sealing frame 432, so as to form a single-sided adhesive frame. During manufacturing, each frame 432 and the associated adhesive layer 240 are formed in the same steps, by cutting a single-sided adhesive sheet.

[0116] It is understood that for each wall 102 of the unit cell 100, when the compartments located on each side of this wall 102 include transfer frames 330 taken between two adhesive films 440, it is particularly advantageous to seal the gap 1220, using a sealing frame 432 and an associated layer of adhesive 240, at least on one of the faces 103 of this wall 102, because the adhesive films 440 might not be sufficient to guarantee a sufficient seal. When the wall 102 is the membrane 130, the membrane 130 is preferably sealed on each of its two faces by a sealing frame 432 with the associated adhesive layer 240, so as to hold the membrane 130, which is here made of fluorinated polymer and is more fragile and more difficult to glue than the separators 110 and 120, which are here made of stainless steel.

[0117] In the example of [Fig.8], the compartment V100 under consideration is delimited by two sealing frames 432 and by the associated adhesive layers 240, further improving the sealing of this frame V100. In particular, the compartment V100 where the operating fluid is hydrogen is preferably delimited by such a sealing structure comprising two sealing frames 432 on either side of the compartment frame 330.

[0118] Preferably, all compartments V100 through which gases circulate, i.e. the first reactive compartment VI32 and the second reactive compartment VI34, are each delimited by two sealing frames 432 on either side of a compartment frame 330 associated with this reactive compartment.

[0119] [Fig.9] illustrates, for a compartment V100 considered, respectively, on inserts a) and b), two alternative sealing structures 500' and 500" of the sealing structure 500 represented on [Fig.8].

[0120] Compared to the sealing structure 500 shown in [Fig. 8], in the case of the sealing structure 500' shown in Figure 9 a), one of the sealing frames 432 and the adhesive layer 240 associated with this sealing frame 432 are arranged on the other side of one of the walls 102 delimiting compartment VI00, here on the other side of the wall 102 located on the bottom of [Fig. 9] a). This sealing frame 432 therefore belongs, in a stacking arrangement, to the compartment frame of the compartment adjacent to the compartment V100 under consideration, located on the other side of the wall 102 located on the bottom of [Fig. 9] a). The adhesive layer 240 associated with this wall 102 is thus interposed, the other side of the wall 102 with respect to the compartment VI00 under consideration, between the sealing frame 432 and the wall 102, so as to close the gap 1220. The gap 1220 is not shown on [Fig.9].

[0121] Compared to the sealing structure 500 shown in [Fig. 8], in the case of the sealing structure 500 shown in [Fig. 9] b), the two sealing frames 432 and the adhesive layers 240 associated with each of these sealing frames 432 are arranged on the other side of the two walls 102 delimiting compartment VI00. In other words, the transfer frame 330 associated with compartment VI00 of [Fig. 9] b) is interposed between the two wall frames 220 that immediately frame it in the stacking direction A50, without any sealing frame being interposed between this transfer frame 330 and these two wall frames 220. In contrast, such sealing frames 432 are provided immediately in contact with each of these two wall frames 220, with, for each wall frame only, the interposition of a layer 240 adhesive between the 432 sealing frame and the wall frame.In a stack, these two sealing frames 432 therefore each belong respectively to one of the two compartment frames of the two neighboring compartments of the compartment V100 considered, located respectively on the other side of the wall 102 located on the bottom of [Fig.9] b) and on the other side of the wall 102 located towards the top of [Fig.9] b).

[0122] In all cases where the compartment frame includes a sealing frame 432, and in particular in all cases where this sealing frame 432 is interposed between a transfer frame 330, belonging to the same compartment frame, and a wall frame 220, the adhesive layer 240, which is therefore interposed between, on the one hand, the sealing frame, and, on the other hand, the wall 102 and the wall frame 220 associated with this wall, necessarily includes a first portion of the layer, which extends opposite the first overlap between the compartment frame (here the sealing frame being part of this compartment frame) and the wall, so as to fix the compartment frame to the wall in a watertight manner. This first portion of the layer 241 is therefore in these cases opposite and in contact with the sealing frame 432 and the wall.This same adhesive layer 240 includes the second portion of layer 242, which extends opposite the second overlap between the compartment frame (here again the sealing frame being part of this compartment frame) and the wall frame, so as to fix the compartment frame to the wall frame in a watertight manner. This second portion of layer 242 is therefore, in these cases, opposite and in contact with the sealing frame 432 and the wall frame 220. Of course, the first portion of adhesive layer 241 and the second portion of adhesive layer 242 preferably form part of the same adhesive layer 240, as in the illustrations, which extends continuously over one face of the compartment frame, in this case one face of the sealing frame 432, the first and second portions of the adhesive layer. 241 and 242 are therefore continuous both radially and circumferentially over the entire extent of the sealing frame 432, so as to close the peripheral gap 1220 opposite the compartment frame 220.

[0123] The sealing structures 500, 500' and 500" shown in figures 8 and 9 can thus be chosen, as required, for each of the compartments V100 of a unit cell 100, and by extension for the stack 50.

[0124] Generally, the thicknesses of each element of the sealing structures 200, 300, 400 or 500, namely the thicknesses of the wall frames 220, the compartment frames 220, the transfer frames 330, the sealing frames 432, as well as the thicknesses of the adhesive layers 240 or the adhesive films 440, are adjusted according to the structure of each unit cell 100, in particular according to the nature of each wall 102 and the various elements received in each of the compartments VI00 of the unit cell 100.

[0125] Thus, each sealing frame 432 is made of a polymer material, for example PET, and has a thickness, measured parallel to the stacking axis A50, of between 10 qm and 20 qm, preferably equal to 12 qm.

[0126] The adhesive film 440 interposed between each sealing frame 432 and the corresponding transfer frame 330 has a thickness, measured parallel to the stacking axis A50, of between 6 qm and 30 qm, preferably between 8 qm and 20 qm, preferably between 10 qm and 15 qm.

[0127] Each transfer frame 330 is made of a polymer material, for example PET, and has a thickness, measured parallel to the stacking axis A50, of between 50 qm and 600 qm, preferably between 80 qm and 150 qm, preferably also equal to 100 qm.

[0128] For each layer of adhesive 240, the first and second layers each have a thickness, measured parallel to the stacking axis, of between 15 µm and 30 µm, preferably between 18 µm and 25 µm, preferably equal to 20 µm. Preferably, the thickness is identical for the first and second layers.

[0129] The unit cell 100 is shown schematically in cross-section in [Fig. 10]. As indicated by the dotted line, this unit cell is repeated in the stack.

[0130] The first reactive compartment V132 houses here one example of the second type spacer 700. On the periphery of the first reactive compartment VI32, the frames 210 which form the compartment frame corresponding to this compartment include a transfer frame 330, which provides the two passages 332 associated with the first reactive compartment VI32, and two sealing frames 432, one on each side of the transfer frame 330, which are each fixed to the transfer frame 330 by a respective adhesive film 440.

[0131] The second reactive compartment V134 houses here an example of the spacer 600 of the first type. On the periphery of the second reactive compartment V134, the frames 210 which form the compartment frame corresponding to this reactive compartment VI34 comprise a transfer frame 330, which provides the two passages 332 associated with the second reactive compartment VI32, and two sealing frames 432, one on each side of the transfer frame 330, which are each fixed to the transfer frame 330 by a respective adhesive film 440.

[0132] The cooling compartment VI36 here houses a second example of the second-type spacer 700. Around the periphery of the cooling compartment V136, the frames 210 that form the compartment frame corresponding to this compartment comprise only a transfer frame 330, which provides the two passages 332 associated with the reactive cooling compartment V132.

[0133] It is noted, however, that a given sealing structure can be implemented regardless of the type of spacer contained in a given compartment.

[0134] In [Fig. 10], the passages 332 are schematically represented by dashed arrows. In particular, the passages 332 for each of the compartments V132, V134, and V136 are shown as if aligned along the stacking axis A50, this illustration being schematic. As seen in [Fig. 4], the location and circumferential extent of the passages 332 are adjusted according to the type and orientation of the irrigation spacers 600 or 700. Preferably, as illustrated in [Fig. 4], the passages 332 for each of the compartments V132, V134, and V136 of the same unit cell 100 are offset from one another around the perimeter of the cell, preferably by being substantially diametrically opposite each other. On the other hand, the passages 332 of each of the first reactive compartments V132 of the set of unit cells 100 of the stack are preferably aligned along the stacking axis A50.Similarly, the passages 332 of each of the second reactive compartments V134 of the stack of unit cells 100 are preferably aligned along the stacking axis A50, and the passages 332 of each of the cooling compartments V136 of the stack of unit cells 100 are preferably aligned along the stacking axis A50.

[0135] In the example of [Fig. 10], the first reactive compartment V132 and the second reactive compartment V134 are each delimited by a compartment frame comprising two respective sealing frames 432, arranged on either side of a transfer frame 300, each sealing frame 432 being adjacent to a respective wall 102. Thus, the peripheral gap 1220 associated with the wall 102 separating the two reactive compartments V132 and V134, in other words, the gap 1220 associated with the membrane 130, is sealed, on both faces of the membrane 130, by a frame respective sealing 432. For each compartment frame of the first reactive compartment VI32 and the second reactive compartment VI34, each sealing frame 432 is fixed to the transfer frame by an adhesive film 440. The compartment frame thus formed is associated with two layers of adhesive 240 arranged on either side of the compartment frame along the stacking axis A50. Each of these two layers of adhesive 240 is therefore interposed between, on the one hand, a sealing frame 432, and, on the other hand, the wall 102 and the wall frame 220 associated with this wall.

[0136] In the example of [Fig. 10], the cooling compartment V136 is delimited by a compartment frame comprising only a transfer frame 330, without a sealing frame 432. Thus, the peripheral gap 1220 associated with the first separator 110 is sealed by a sealing frame 432 on only one side of the first separator 110, and this sealing frame 432 is similar to the compartment frame of the adjacent compartment, namely here the first reactive compartment VI32. Similarly, due to the pattern effect resulting from the stacking of identical cells, the peripheral gap 1220 associated with the second separator 120 is sealed by a sealing frame 432 on only one side of the first separator 110, this sealing frame 432 being similar to the compartment frame of the first reactive compartment VI32.Of course, to ensure the seal, it would have been possible to provide, for the VI36 cooling compartment, a compartment frame comprising a sealing frame on one side of the 330 transfer frame, or comprising two sealing frames, on each side, of the 330 transfer frame.

[0137] A unit cell 200 according to an alternative embodiment is shown in [Fig. 11]. The unit cell 200 comprises the first reactive compartment V132 and the second reactive compartment VI34, but does not include a cooling compartment. Cooling of the unit cell 200 is provided here by the passage of air, which circulates in the second reactive compartment VI34.

[0138] Unlike the unit cell 100 of the previous embodiment, the second reactive compartment VI34 is here delimited by a compartment frame comprising a single sealing frame 432. In the example of [Fig.11], the peripheral gap 1220 associated with the membrane 130 is closed on one side by a sealing frame 432. To compensate for the absence of the sealing frame without reducing the height of the compartment, the transfer frame 330 received in the second reactive compartment has a greater thickness than the transfer frame 330 of the previous embodiment, so that the passage of fluid 332 allows a higher flow rate of the associated operating fluid - here air - which serves both for the electrochemical reaction of the fuel cell and for cooling the cell.

[0139] Regardless of the number of compartments V100 in the unit cell 100, with or without cooling compartment VI36, for each compartment VI00, and for For each of the walls 102 delimiting this compartment VI00, the peripheral gap 1220 associated with this wall 102 is sealed, on at least one face of this wall 102, by a sealing frame 432, which is fixed to this wall by the associated adhesive layer 240. In other words, the peripheral gap 1220 associated with this wall 102 is sealed, on at least one face of this wall, by a frame continuous around the entire circumference of this gap 1220.

[0140] Preferably, the reactive compartment through which hydrogen circulates, here the first compartment VI32, is delimited by a compartment frame comprising two sealing frames 432 arranged on either side of a transfer frame 330 along the stacking axis A50, each of these sealing frames 432 closing a peripheral gap 1220 associated with the two walls 201 delimiting this reactive compartment. Each sealing frame is fixed to the transfer frame by an adhesive film 440. The compartment frame thus formed is associated with two layers of adhesive 240 arranged on either side of the compartment frame along the stacking axis A50. Each of these two layers of adhesive 240 is therefore interposed between, on the one hand, a sealing frame 432, and, on the other hand, the wall 102 and the wall frame 220 associated with this wall.

[0141] Preferably, each sealing frame 432 and the associated adhesive layer 240 are made by cutting from a single-sided adhesive plate.

[0142] Preferably, each transfer frame 330 and the two associated adhesive films 440 are made by cutting from a double-sided adhesive sheet.

[0143] The irrigation spacer 600 of the first type is now described using Figures 12 and 13.

[0144] The irrigation spacer 600, also simply called the "spacer 600", has a generally rectangular shape, with two opposite long sides and two opposite short sides, and is flat, extending orthogonally to a height axis A600. When the spacer 600 is received in the corresponding compartment V100, the height axis A600 is parallel to the stacking axis A50. The long sides extend parallel to a longitudinal axis X600 of the spacer 600, while the short sides extend parallel to a transverse axis Y600 of the spacer 600. The longitudinal axis X600, the transverse axis Y600 and the height axis A600 together form an orthogonal coordinate system.

[0145] The spacer 600 comprises two distribution plates 602, including a first plate 602A and a second plate 602B. Each of the distribution plates 602 comprises two opposite faces, including a first face 604 and a second face 605.

[0146] The two plates 602 are stacked flat one on top of the other along the height axis A600, which is orthogonal to a mean plane P600 of the irrigation spacer 600. When the spacer 600 is received in the compartment V100, the mean plane P600 of The irrigation spacer 600 is therefore orthogonal to the stacking axis A50, or parallel to the average plane P50 of the corresponding unit cell 100.

[0147] Each distribution plate 602 is manufactured by cutting from a metal sheet and has a thickness of between 30 µm and 300 µm, preferably between 50 µm and 100 µm, preferably also equal, to ±5%, to 75 µm. Preferably, the distribution plates 602 have the same thickness.

[0148] Each distribution plate 602 includes perforations 610, which are formed by cutting this distribution plate 602. The perforations 610 are through, that is to say, the perforations 610 open onto the two opposite faces 604 and 605 of this distribution plate 602.

[0149] The perforations 602 are arranged to form a network 612 of channels when the two plates 602 are stacked, the network 612 of channels being configured to form a flow field of an operating fluid circulating in the compartment VI00 where the irrigation spacer 600 is housed.

[0150] The irrigation spacer 600 comprises a fluid inlet 613A and a fluid outlet 613B, the inlet 613A and outlet 613B being fluidly connected to each other by the channel network 612. The terms "inlet" and "outlet" are relative and depend on the direction of flow of the fluid. In the illustrated example, the inlet 613A and outlet 613B are respectively provided on the short sides of the spacer 600.

[0151] The perforations 610 of each distribution plate 602 have an elongated shape, with two adjacent perforations 610 extending along one another and separated from each other by a strip 614 of material. Each perforation 610 is delimited by two opposing longitudinal edges 616, each of the two longitudinal edges 616 corresponding to one of the edges of the two strips 614 of material that delimit each perforation 610.

[0152] Each distribution plate 602 also includes crossbars 618, which extend through perforations 610 in the thickness of the distribution plate 602, and which keep the strips 614 apart. Each crossbar 618 thus connects the two longitudinal edges 616 of the perforation 610 through which it extends.

[0153] Each strip 614 of the first plate 602A is superimposed, along the height axis A600, with a respective strip 614 of the second plate 602B, delimiting a first portion 620 of the channel network 612. In other words, in the first portion 620 of the channel network 612, each perforation 610 of the first plate 602A is aligned, along the height axis A600, with a respective perforation 610 of the second plate 602B, so as to form each channel of the network 612. The irrigation spacer 600 here comprises only one portion 620, that is to say, the first Portion 620 represents the entirety of the 612 channel network. The first portion 620 of the 612 network is represented by a dotted outline.

[0154] The first portion 620 of the network 612 of channels corresponds, on each of the distribution plates 602, to a first portion 621 of these distribution plates 602. For each distribution plate 602 of the irrigation spacer 600 of the first type, the first portion 621 of this plate 602 therefore represents the entirety of this plate.

[0155] The crossbeams 618 of the first plate 602A are offset, in the mean plane P600 of the spacer 600, relative to the crossbeams 618 of the second plate 602B, so as not to impede the circulation of operating fluids in the channels of the first portion 620 of the network 612 of channels of the irrigation spacer 600.

[0156] In inset c) of [Fig. 13], a detail of the spacer 600 is shown sandwiched between two elements of the cell 100, namely between the membrane 130 and the second separator 120. The circulation of the working fluid is represented by an arrow F612. It is understood that the fluid circulating in each channel of the network 612 flows along each channel while bypassing the cross members 618, which are offset from each other according to the direction of the channel, two cross members 618 of the spacer 600, which extend through a given channel and which do not belong to the same distribution plate 602, are therefore offset from each other according to the direction of the channel.

[0157] In the first portion 620 of the channel network, the bands 614 of each distribution plate 602 are preferably parallel to each other. As a result, the perforations 610, and therefore the channels of the network 612, are also parallel to each other, so as to reduce the pressure losses of the operating fluid circulating in the spacer 600.

[0158] Advantageously, for each of the distribution plates 602 for the irrigation spacer 600 of a given compartment, each strip 614 of material extends continuously from the fluid inlet 613A to the fluid outlet 613B of the spacer 600, so that each channel of the network 612 extends continuously from the inlet 613A to the outlet 613B. In other words, there is no bifurcation or junction of the perforations 610, so as to reduce the pressure losses of the operating fluid circulating in the spacer 600.

[0159] Preferably, in the first portion 620 of the canal network 612, the bands 614 of the irrigation spacer 600 are straight in orthogonal projection onto the mean plane P600 of the spacer 600. Thus the canals of the first portion of the canal network are straight.

[0160] Preferably, in the first portion 620 of the 612 channel network, the per- The perforations 610 each have the same width 1610, which is between 0.2 mm and 1.1 mm, while the strips 614 of material separating two adjacent perforations 610 each have a width 1614 between 0.2 mm and 0.7 mm. This ensures both good flow of the operating fluid and good transfer of the compressive forces, parallel to the height axis A600, which are exerted on the spacer 600 when the spacer 600 is received in a fuel cell 20.

[0161] Preferably, in the first portion 620 of the channel network 612, each cross member 618 has a height equal to the height of the strips 614 of material adjacent to the perforation 610 in which this cross member 618 is placed, the height of the cross members and the height of the strips being measured parallel to the height axis. The manufacturing process is thus simplified, each distribution plate 602 being produced by simple cutting.

[0162] The irrigation spacer 700 of the second type is now described using Figures 14 and 15. The elements identical to those of the irrigation spacer 600 of the first type bear the same references.

[0163] Whereas for the spacer 600 of the first type, each channel of the network 612 of channels is straight from one end to the other, i.e. from the input 613A to the output 613B, the spacer 700 of the second type comprises a network of channels 712, in which each channel is formed of several straight portions, two consecutive portions not being aligned with each other.

[0164] The spacer 700 includes an input 713A and an output 713B, each of which is provided on one of the respective long sides of the rectangle. Advantageously, each channel of the network 712 extends continuously from the input 713A to the output 713B.

[0165] The channel network 712 comprises several distinct portions. Within each portion, the perforations 610 are parallel to each other, with two adjacent perforations 610 being separated from each other by a band 614 of respective material

[0166] In the illustrated example, the channel network 712 comprises three consecutive portions, including a first portion 714A, a second portion 714B, and a third portion 714C, the outlines of the three portions 714A, 714B, and 714C being shown as dashed lines in Figures 14 and 15. More generally, the number of portions is chosen according to the geometry of the spacer, the arrangement of the fluid inlet and outlet, etc. What is valid for the first and second portions 714A and 714B of the channel network 712 is applicable to any two consecutive portions of the channel network 712.

[0167] The spacer 700 comprises two distribution plates 702, including a first plate 702A and a second plate 702B. Portions 714A, 714B, and 714C of the channel network 712 are found, with the references 724A, 724B, and 724C, on each of the plates 702. In [Fig. 14], only the first and second portions 724A and 724B of each of the first and second distribution plates 702A and 702B are visible. The operating principle of the spacer 700 is described with reference to the first and second portions 714A and 714B of the channel network 712.

[0168] For each of the first and second distribution plates 702A and 702B, in each of the first and second portions 724A and 724B, the perforations 610 are parallel to each other, two adjacent perforations 610 being separated from each other by a strip 614 of respective material.

[0169] Each strip 614 of the second portion 724B of the first plate 702A is superimposed, along the height axis A600, with a respective strip 614 of the second portion 724B of the second plate 702B, so as to form channels of a second portion 714B of the irrigation spacer 712 channel network, the channels of the second portion 714B of the irrigation spacer 712 being parallel to each other.

[0170] For each distribution plate 702A or 702B, each band 614 of the first portion 724A of this distribution plate extends, continuously, with a band 614 of the second portion 724B of this same distribution plate.

[0171] For each distribution plate 702A or 702B, the bands 614 of the first portion 724A are straight and parallel to each other, the channels of the first portion 714A of the network 712 extending along a first flow axis 716A, while the bands 614 of the second portion 724B are straight and parallel to each other, the channels of the second portion 714B of the network 712 extending along a second flow axis 716B. The first flow axis 716A and the second flow axis 716B are each represented by a respective arrow in Figures 14 and 15. The first flow axis 716A is here parallel to the transverse axis Y600, while the second flow axis 716B is here parallel to the longitudinal axis X100.

[0172] The first flow axis 716A and the second flow axis 716B are distinct, that is to say that the working fluid circulating in each channel of the network 712 changes direction in the passage from the first portion 714A to the second portion 714B.

[0173] The first flow axis 716A and the second flow axis 716B form an angle between them of between 1 and 179°, preferably between 30° and 150°, and more preferably between 60° and 120°. In the illustrated example, the first flow axis 716A and the second flow axis 716B form an angle of 90°.

[0174] In the illustrated examples, each of the compartments among the first reactive compartment VI32, the second reactive compartment VI34 and the first compartment Cooling compartment V126 houses an irrigation spacer 600 or 700 according to the invention.

[0175] In an alternative not shown, only one of the V100 housings of the unit cell 100 receives an irrigation spacer of a different type, the other two V100 housings each receiving an irrigation spacer according to the invention. According to another alternative not shown, only one of the VI00 housings of the unit cell 100 receives an irrigation spacer according to the invention, the other two V100 housings each receiving an irrigation spacer of a different type.

[0176] The embodiments and variants mentioned above can be combined with each other to generate new embodiments of the invention.

Claims

Claims

1. An irrigation spacer (600; 700) for a unit cell (100) of a fuel cell (20), the irrigation spacer being configured to be housed in a compartment (V100) of the unit cell, wherein: • the irrigation spacer comprises two distribution plates (602; 702), including a first plate (602A; 702A) and a second plate (602B; 702B), the distribution plates each comprising two opposite faces (604, 605) and being stacked flat on top of each other along a height axis (A600) orthogonal to a mean plane (P600) of the irrigation spacer, • each distribution plate (602; 702) comprises perforations (610), which are formed by cutting the distribution plate, which open onto the two opposite faces of this distribution plate and which are arranged so as to form a network (612; 712) of channels when the two plates are stacked, the network of channels being configured to form a flow field of an operating fluid circulating in the compartment (V100) where the irrigation spacer is housed, characterized in that: • each distribution plate (602; 702) comprises a first portion (621; 724A), in which the perforations (610) have an elongated shape with two opposite longitudinal edges (612), two neighboring perforations extending along one another and being separated from one another by a strip (614) of material, • each distribution plate (602; 702) comprises crosspieces (618), which extend through the perforations (610) in the thickness of this distribution plate, and which keep the strips (614) at a distance from each other, • each strip (614) of the first portion (724A) of the first plate (602A; 702A) is superimposed, along the height axis (A600), with a respective strip (614) of the first portion (620; 734B) of the second plate 602B; 702B), so as to form a first portion (620; 714A) of the network (612; 712) of channels, • in the first portion of the network of channels, the crosspieces (618) of the first plate (602A; 702A) are offset, in the mean plane (P600), relative to the crosspieces of the second plate (602B; 702B), so as not to prevent the circulation of fluids in the channels of the first portion (620; 714A) of the network of channels.

2. Irrigation spacer (600; 700) according to claim 1, wherein, in the first portion (620; 714A) of the network (612; 712) of channels, each crosspiece (618) connects to each other the two longitudinal edges (612) of each perforation (610).

3. Irrigation spacer (600; 700) according to any one of claims 1 or 2, wherein, for each distribution plate (602; 702), the strips (614) of material of the first portion (621; 724A) are parallel to each other.

4. Irrigation spacer (600; 700) according to any one of claims 1 to 3, wherein, in the first portion (620; 714A) of the network (612; 712) of channels: • the perforations (610) each have the same width (1610), which is between 0.2 mm and 1.1 mm, and • the strips (614) separating two neighboring perforations each have a width (1614) between 0.2 and 0.7 mm.

5. Irrigation spacer (600; 700) according to any one of claims 1 to 4, wherein, in the first portion (620; 714A) of the network (612; 712) of channels, each crosspiece (618) has a height equal to a height of the strips (614) adjacent to the perforation in which this crosspiece is arranged, the height of the crosspieces (618) and the height of the strips (614) being measured parallel to the height axis (A600).

6. An irrigation spacer (600; 700) according to any one of claims 1 to 5, wherein each distribution plate (602; 702) is manufactured by cutting from a metal sheet and has a thickness between 30 μm and 300 μm, preferably between 50 μm and 100 μm, more preferably equal, within ±5%, to 75 μm.

7. An irrigation spacer (600; 700) according to any one of claims 1 to 6, wherein: • the irrigation spacer comprises a fluid inlet (613A; 713A) and a fluid outlet (613B; 713B), the inlet and outlet being fluidically connected to each other by the network (612; 712) of channels, and • for each of the distribution plates, each strip (614) extends continuously from the inlet to the outlet, such that each channel of the network (612; 712) of channels extends continuously from the inlet to the outlet.

8. Irrigation spacer (600; 700) according to any one of claims 1 to 7, in which, in orthogonal projection on the mean plane (P600) of the spacer, the channels of the first portion (620; 714A) of the network (612; 712) of channels are rectilinear.

9. Irrigation spacer (700) according to any one of claims 1 to 8, wherein: • each distribution plate (702) comprises, in addition to the first portion (724A), a second portion (724B), distinct from the first portion, • in each second portion (724B) of the distribution plates, the perforations (610) are parallel to each other, two adjacent perforations being separated from each other by a respective strip (614), • each strip (614) of the second portion (724B) of the first plate (702A) is superimposed, along the height axis, with a respective strip (614) of the second portion (724B) of the second plate (702B), so as to form channels of a second portion (714B) of the network (712) of channels of the irrigation spacer (700), the channels of the second portion of the network of channels being parallel to each other, • for each distribution plate (702A;702B), each strip (614) of the first portion (724A) extends, continuously, with a respective strip of the second; portion (724B), • for each distribution plate (702A; 702B), the strips (614) of the first portion (724A) of the distribution plates (702) are rectilinear and parallel to each other, the channels of the first portion (714A) of the network of channels (712) extending along a first flow axis (716A), while the strips (614) of the second portion (724B) of the distribution plates (702) are rectilinear and parallel to each other, the channels of the second portion of the network of channels (712) extending along a second flow axis (716B), • the first flow axis (716A) and the second axis flow (716B) form between them an angle of between 1 and 179°, preferably of between 30° and 150°, more preferably of between 60° and 120°.

10. Unit cell (100) of a fuel cell stack (50) (20), comprising: • a proton exchange membrane (130), with a first face (132) and a second face (134) opposite the first face, • a first separator (110), which is adjacent to the first face of the membrane, which delimits with the membrane a first reactive compartment (VI32) and which separates in a sealed manner the first reactive compartment from a first cooling compartment (V136), • a second separator (120), which is adjacent to the second face (134) of the membrane (130) and which delimits with the membrane a second reactive compartment (VI34), in which at least one compartment, chosen from: • the first reactive compartment (VI32), • the second reactive compartment (VI34), and • the first cooling compartment (VI36), houses an irrigation spacer (600; 700) conforming to any one of the preceding claims.

11. Fuel cell (20), comprising a stack (50) of several unit cells (100) according to the preceding claim.

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