Single cell of a fuel cell and associated fuel cell

Abstract

The invention relates to a single cell (100) of a fuel cell stack, which comprises a plurality of walls (102), that are each continuous and sealed, which define compartments (V100) of the single cell and which are held by a sealing structure (200). The sealing structure is formed from a stack of wall frames (220), which each surround an associated wall (102), compartment frames (230), which are each arranged at the periphery of a corresponding compartment (V100), and adhesive layers (240), which are inserted between each of the frames of the sealing structure so as to sealingly secure the frames to each other. Each wall forms, with its associated wall frame, a peripheral gap, which is sealingly closed, on at least one of the faces of this wall, by a compartment frame arranged opposite this peripheral gap.

Description

[0001] TITLE: Fuel cell unit cell and associated fuel cell

[0002] The present invention relates to a fuel cell unit cell and to a fuel cell comprising such a unit cell.

[0003] A fuel cell is a device for generating electricity by electrochemical reaction between a fuel, for example di-hydrogen - also simply called hydrogen -, and an oxidant, for example di-oxygen - also simply called oxygen - contained in the air. We are interested here in fuel cells of the solid electrolyte proton exchange membrane type - also called PEMFC in English -, which usually comprise a stack - called "stack" in English - of unit cells each constituting an electrochemical generator.

[0004] Schematically, each unit cell comprises two separators, also called polar plates, between which is inserted a solid electrolyte in the form of a proton exchange membrane. The membrane is made, for example, of a sulfonated perfluorinated polymer material. Within each cell, each separator delimits a reactive compartment with the corresponding membrane. One of the two reactive compartments houses a cathode element, while the other reactive compartment houses an anodic element.

[0005] Within the stack, the cells are stacked so that cathode and anode elements alternate. In many types of fuel cells, for two neighboring cells, a separator from one of the two cells is 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, in which a cooling fluid such as glycol water circulates, is generally arranged between the two separators of the bipolar separator. In other types of fuel cells, particularly in a cell without liquid cooling, the same separator is shared by two neighboring cells and the cell therefore does not have a cooling compartment.

[0006] Hydrogen, air and any coolant are so-called "operating" fluids, which are supplied to the fuel cell during its operation. Depending on the operating phases of the fuel cell, the supply of one or more of the operating fluids is done continuously or intermittently.

[0007] The fuel cell thus provides openings to supply fluids to each of the reactive compartments and the fluids between two neighboring cells. Thus, each bipolar separator ensures on one side the fuel supply to the cell adjacent to this side and on the other side the oxidant supply to the cell adjacent to this other side, the supplies provided by the bipolar separators being done in parallel.

[0008] When the fuel cell is in operation, the electrochemical reaction creates an electrical potential difference between the two separators of each unit cell. The fuel cell thus comprises an electrical insulation device, designed to prevent current leaks between two neighboring cells and between each cell and the external environment, as well as a sealing device to prevent leaks of operating fluids, in particular to prevent the fluid circulating in a reactive compartment from contaminating a neighboring reactive compartment.

[0009] EP-3 618 157-A1 describes, for example, a redox cell, the fuel and oxidizer of which are electrolytes, i.e. liquids. The redox cell comprises frames, which are made of polypropylene and which are arranged around the bipolar plates and the electrodes, so as to reduce current leakage. The frames are pierced to provide channels for the circulation of the electrolytes. Sealing is ensured by O-rings, which are arranged in grooves machined in the thickness of the frames and which are held in compression by a clamping flange. Such a structure is however not suitable for the passage of gaseous fluids, in particular air or hydrogen, used with a fuel cell. The installation and inspection of each seal are also tedious operations.

[0010] JP-5 330 135-B2 describes a fuel cell unit cell comprising a sealing structure composed of frames and separators in the shape of an angle, the frames and separators being stacked and assembled by adhesive elements. Passages between the manifolds and the internal compartments of the unit cell are formed in hollows in the separators in the shape of an angle, which requires a specific machining step and complicates the assembly of the sealing structure.

[0011] The invention aims to address these problems in particular by proposing a fuel cell stack that is easy to assemble and has both good electrical insulation and good sealing.

[0012] To this end, the invention relates to a unit cell of a fuel cell stack, in which:

[0013] - the unit cell comprises several walls, each of which is continuous and watertight and which is stacked on top of each other along a stacking axis, these walls delimiting compartments of the unit cell and including:

[0014] • a first separator,

[0015] • a second separator, and • a proton exchange membrane, which is interposed between the first separator and the second separator,

[0016] - the first separator delimits with the membrane a first reactive compartment, the first reactive compartment being configured to receive a first operating fluid of the fuel cell,

[0017] - the second separator delimits with the membrane a second reactive compartment, the second reactive compartment being configured to receive a second operating fluid of the fuel cell,

[0018] - the compartments of the unit cell include the first reactive compartment and the second reactive compartment, the cell also comprises a sealing structure, the sealing structure comprising frames, which are each made of a polymer material and which are stacked along the stacking axis, the frames being arranged at the periphery of the walls and the compartments.

[0019] According to the invention, for at least one of the compartments of the unit cell, and for at least one of the two walls delimiting this at least one compartment: the frames of the sealing structure include:

[0020] • a wall frame, which is coplanar with the corresponding wall and which surrounds this wall, an internal edge of each wall frame being arranged opposite an external edge of this wall, the internal edge of the wall frame and the external edge of the wall being opposite each other and being separated by a peripheral gap, each wall frame preferably having a thickness substantially equal to a thickness of the corresponding wall,

[0021] • a compartment frame, which is arranged on the periphery of the corresponding compartment, the compartment frame comprising an inner edge, which is oriented towards the corresponding compartment and which delimits this compartment radially to the stacking axis, and an outer edge, opposite the inner edge, the inner edge having an inner contour, while the outer edge has an outer contour,

[0022] • layers of adhesives, each of which is interposed between, on the one hand, a compartment frame, and, on the other hand, the wall and the wall frame adjacent to this compartment frame, so as to fix, in a sealed manner, the frames to each other, the internal contour of the compartment frame is included, in projection along the stacking axis, in an external contour of the wall, so that an annular portion of the wall faces, along the stacking axis, a complementary portion of the compartment frame and forms a first overlap of the compartment frame on the wall, an internal contour of the wall frame is included, in projection along the stacking axis, in the external contour of the compartment frame, so that an annular portion of the wall frame faces a complementary portion of the compartment frame and forms a second overlap of the compartment frame on the wall frame,the adhesive layers include a first layer portion, which extends opposite the first overlap between the compartment frame and the adjacent wall, so as to sealably attach the compartment frame to the wall, and the adhesive layers include a second layer portion, which extends opposite the second overlap between the compartment frame and the adjacent wall frame, so as to sealably attach the compartment frame to the wall frame.,

[0023] By means of the invention, the frames of the sealing structure are assembled to each other by means of the adhesive layers, making the assembly of the unit cell convenient and quick to carry out. Furthermore, since the first compartment frame has an internal contour included in the external contour of the membrane, the first portion of the adhesive layer, interposed between the internal face of the first compartment frame and the external face of the adjacent membrane, prevents leakage of the operating fluid circulating in the first reactive compartment to the second reactive compartment. Similarly, since the internal contour of the first compartment frame is included in the external contour of the first separator, the second portion of the adhesive layer, interposed between the internal face of the first compartment frame and the external face of the adjacent separator, prevents leakage to the cooling compartment.The first and second portions of adhesive layers provide a seal across the entire covering surfaces, preventing the passage of operating fluids, both liquid and gaseous, between the elements assembled by these adhesive layers. In addition, it is possible to use repositionable and / or pressure-sensitive adhesive layers, which makes it possible to provide a removable cell.

[0024] According to advantageous but not mandatory aspects of the invention, such a unit cell may incorporate one or more of the following features taken in isolation or in any technically admissible combination: - the first separator is configured to sealably separate the first reactive compartment from a first cooling compartment, which is configured to receive a third operating fluid of the fuel cell, while the compartments of the unit cell include, in addition to the first reactive compartment and the second reactive compartment, the first cooling compartment.

[0025] The first adhesive layer portion and the second adhesive layer portion are part of a single adhesive layer, which extends continuously over one face of the compartment frame, so as to seal the peripheral gap adjacent to the compartment frame.

[0026] The first overlap has a trailing length, which is equal to a minimum distance, measured parallel to the mean plane, between any two points belonging respectively to the inner edge of the corresponding compartment frame and to the outer edge of the corresponding adjacent wall, while the second overlap has a trailing length, which is equal to a minimum distance, measured parallel to the mean plane, between any two points belonging respectively to the outer edge of the corresponding compartment frame and to the inner edge of the corresponding adjacent wall frame, and each trailing length is greater than or equal to 1 mm, preferably greater than or equal to 2 mm, more preferably greater than or equal to 3 mm. For at least one of the compartment frames:

[0027] • this compartment frame comprises a transfer frame which provides two fluid passages, the two passages being provided for the circulation of the associated operating fluid between the corresponding compartment and the exterior of the unit cell,

[0028] • each passage opens into the associated compartment through an internal opening, which is provided on the internal edge of the transfer frame, and

[0029] • each passage opens outside the compartment through an external opening.

[0030] Each passage comprises an internal portion, which opens through the internal mouth into the compartment, the internal portion of the passage being provided in the thickness of the transfer frame.

[0031] The external mouthpiece is provided on the external edge of the transfer frame. For at least one transfer frame:

[0032] • at least one of the two passages houses guide fins for the associated operating fluid,

[0033] • the fins are formed by cutting this transfer frame and are distributed at a distance from each other within the corresponding passage, so as to direct the flow of the associated operating fluid,

[0034] • the fins are held in place by means of layers of adhesive between which the corresponding transfer frame is inserted.

[0035] For at least one of the first and second reactive compartments, the compartment frame comprises:

[0036] • the transfer framework,

[0037] • a first sealing frame, which is inserted between, on the one hand, the transfer frame and, on the other hand, a first of the two walls adjacent to the compartment frame and the wall frame opposite this first wall,

[0038] • a first adhesive film, which is interposed between the first sealing frame and the transfer frame, while the first sealing frame is, on the one hand, fixed to the first wall and to the facing wall frame by the adhesive layer associated with the first wall and, on the other hand, fixed to the transfer frame by the first adhesive film.

[0039] The compartment frame includes, in addition to the first sealing frame:

[0040] • a second sealing frame, the first and second sealing frames being arranged on either side of the transfer frame, the second sealing frame being interposed between, on the one hand, the transfer frame and, on the other hand, a second of the two walls adjacent to the compartment frame and the wall frame associated with this second wall, the second wall being different from the first wall,

[0041] • a second adhesive film, which is interposed between the second sealing frame and the transfer frame, while the second sealing frame is, on the one hand, fixed to the second wall and to the facing wall frame by the corresponding adhesive layer and, on the other hand, fixed to the transfer frame by the second adhesive film.

[0042] For at least one sealing frame, the adhesive film associated with this sealing frame is coated, continuously, on one face of this sealing frame.

[0043] For at least one sealing frame: • this sealing frame is made of a polymer material, for example PET, and has a thickness, measured parallel to the stacking axis, of between 10 μm and 20 μm, preferably equal to 12 μm,

[0044] • the adhesive film inserted between this sealing frame and the corresponding transfer frame has a thickness, measured parallel to the stacking axis, of between 6 pm and 30 pm, preferably of between 8 pm and 20 pm, preferably of between 10 pm and 15 pm.

[0045] For each compartment of the unit cell and for each of the walls delimiting this compartment, the peripheral gap associated with this wall is closed, on at least one of the faces of this wall, by a sealing frame.

[0046] For at least one transfer frame:

[0047] • this transfer frame is made of a polymer material, for example PET, and has a thickness, measured parallel to the stacking axis, of between 50 pm and 200 pm, preferably of between 80 pm and 150 pm, more preferably equal to 100 pm,

[0048] • each of the first adhesive layer portions and each of the second adhesive layer portions has a thickness, measured parallel to the stacking axis, of between 15 μm and 30 μm, preferably of between 18 μm and 25 μm, preferably equal to 20 μm.

[0049] The invention also relates to a fuel cell, comprising a stack formed of several unit cells stacked along the stacking axis, each unit cell being in accordance with any one of the preceding claims, and a jacket, which provides an internal volume in which the stack is housed, in which: the frames of the sealing structure of each of the unit cells each have a specific external edge, with an associated external contour, the external contours of all the frames of each sealing structure are superimposed on each other along the stacking axis, the external edges of all the frames of all the sealing structures together forming an external surface of the stack, which has a cylinder shape centered on the stacking axis, the external surface of the stack provides holding members, which are configured to cooperate with complementary members provided in the internal volume of the jacket,so as to maintain the stack within the internal volume and to provide a peripheral volume between the stack and the jacket, and - the maintaining members and the complementary members are designed to divide the peripheral volume into several conduits for circulating the operating fluids of the fuel cell.,

[0050] Advantageously:

[0051] - for each compartment of each unit cell, the associated compartment frame comprises a transfer frame which provides two fluid passages, the two passages being provided for the circulation of the associated operating fluid between the corresponding compartment and the exterior of the unit cell, while each passage opens into the associated compartment through an internal opening, which is provided on the internal edge of the transfer frame, and each passage opens outside the compartment through an external opening.

[0052] The external mouthpiece is provided on the external edge of the transfer frame, whereas:

[0053] • the fuel cell provides two first pairs of circulation conduits, which are respectively associated with the first and second operating fluids of the fuel cell, the unit cells being as defined previously,

[0054] • for each unit cell: each of the two compartments chosen from the first reactive compartment and the second reactive compartment is associated with a respective pair of first conduits, the compartment frames associated with each of the two reactive compartments of this unit cell each comprise a transfer frame with two passages each, the external mouth of each passage being arranged on an external edge of the corresponding transfer frame, the two passages of the same transfer frame each open into a separate conduit among the two circulation conduits of the associated pair of conduits.

[0055] For each unit cell, the first separator is configured to tightly separate the first reactive compartment from a first cooling compartment, which is configured to receive a third operating fluid of the fuel cell, the fuel cell having, in addition to the first two pairs of circulation ducts, a third pair of circulation ducts, the circulation ducts of the third pair being associated with the third operating fluid, while for each unit cell:

[0056] • each of the three compartments chosen from the first reactive compartment, the second reactive compartment and the first cooling compartment, is associated with a respective pair from among the three pairs of conduits,

[0057] • the compartment frames associated with each of the three compartments of this unit cell each comprise a transfer frame with two passages each, the external mouth of each passage being provided on an external edge of the corresponding transfer frame,

[0058] • the two passages of the same transfer frame each open into a separate conduit among the two circulation conduits of the associated pair of conduits.

[0059] The invention will be better understood, and other advantages thereof will appear more clearly in the light of the following description of an embodiment of a unit cell and a fuel cell, in accordance with its principle, given solely by way of example and with reference to the appended drawings, in which:

[0060] - [Fig 1] Figure 1 is a perspective view of a fuel cell according to the invention;

[0061] - [Fig 2] figure 2 represents, on two inserts a) and b), two schematic views of the fuel cell of figure 1, observed respectively in partially exploded perspective and in top view, certain parts being hidden;

[0062] - [Fig 3] Figure 3 represents respectively, on two inserts a) and b), a jacket and a unit cell of the fuel cell of Figure 1, the unit cell being in accordance with one embodiment;

[0063] - [Fig 4] Figure 4 is an exploded perspective view of the unit cell of Figure 3, with some parts hidden;

[0064] - [Fig 5] Figure 5 represents, on two inserts a) and b), a partial and exploded perspective of a first compartment of the unit cell of Figure 3, observed at two different scales and in section on insert b);

[0065] - [Fig 6] Figure 6 represents, on two inserts a) and b), a partial and exploded perspective of a unit cell conforming to another embodiment, observed at two different scales and in section on insert b), - [Fig 7] Figure 7 represents an exploded and partial perspective of a unit cell conforming to another embodiment;

[0066] - [Fig 8] Figure 8 represents a partial and exploded perspective of a second compartment of the unit cell of Figure 3;

[0067] - [Fig 9] Figure 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;

[0068] - [Fig 10] Figure 10 shows, schematically, a partial cross-section of an embodiment of the unit cell of Figure 3;

[0069] - [Fig 1 1] Figure 1 1 schematically represents a partial cross-section of a unit cell according to another embodiment;

[0070] - [Fig 12] Figure 12 is a perspective view of a first irrigation spacer of the unit cell of Figure 3;

[0071] - [Fig 13] Figure 13 represents respectively, on three inserts a), b) and c), a detail XI I la of the irrigation spacer of Figure 12, this same detail observed in exploded perspective and a diagram illustrating an operating principle of the irrigation spacer of Figure 12;

[0072] - [Fig 14] Figure 14 is a perspective view of a second irrigation spacer of the unit cell of Figure 3; and

[0073] - [Fig 15] Figure 15 is an enlarged, exploded perspective view of detail XV in Figure 14.

[0074] A fuel cell 20 is shown in Figure 1. The fuel cell 20, also referred to simply as “cell 20” hereinafter, comprises a housing 22, which comprises a jacket 24. The jacket 24 has the shape of a hollow cylinder, which extends along a cell axis A20 and which here has a substantially rectangular section. The jacket 24 provides an internal volume V24 with two opposite openings, the openings being closed by two covers 26A and 26B. The jacket 24 and the covers 26A and 26B are preferably made of an electrically insulating material, such as a polymer material or a fiber-reinforced polymer material, or are covered, at least on one internal face, with an electrically insulating material.

[0075] Fluid conduits are provided through the housing 22 to allow the passage of operating fluids of the cell 20. The operating fluids here comprise three fluids, therefore two gaseous fluids, here air and dihydrogen, and a dielectric heat transfer fluid, for example liquid, here glycolated water. The fluid conduits are materialized by fluid connections, which are provided here on the cover 26A, located at the top of FIGS. 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 jacket 24.

[0076] 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 connections 28A, a second pair of connections 28B and a third pair of connections 28C. For each pair of connections, one of the connections called the “inlet connection” is intended for the admission of the corresponding operating fluid, while the other connection called the “outlet connection” is intended for the extraction of the corresponding operating fluid. In the figures, the direction of circulation of the operating fluids is represented schematically by arbitrarily oriented arrows, knowing that it may be otherwise in reality.

[0077] In Figure 2, the battery 20 is shown schematically in exploded perspective, the cover 26A being distant from the jacket 24. The connections 28A, 28B and 28C are shown schematically by openings passing through the cover 26A. The jacket 24 is shown in isolation in Figure 3 a).

[0078] The internal volume V24 of the jacket 24 houses a stack 50. The stack 50 comprises an external surface S50, which has a cylinder shape centered on a stack axis A50 and with a generally rectangular section. When the stack 50 is received in the internal volume V24, the stack axis A50 coincides with the stack axis A20.

[0079] The stack 50 is formed from several unit cells 100, which are stacked along the stacking axis A50. A unit cell 100 is shown in isolation in Figure 3 b), and in exploded perspective in Figure 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 simply called "cell 100" in the following - 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 stack 50 corresponds to the external contour C100 of each unit cell 100.

[0080] The external surface S50 of the stack 50 provides holding members 52, which are configured to cooperate with complementary members 30 provided in the internal volume V24 of the jacket 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 jacket 24. The peripheral volume V50 is therefore a portion of the internal volume V24, which is distributed around the stack 50. The holding 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 cell axis A20 and include sealing elements, so as to divide the peripheral volume V50 into several circulation conduits for the operating fluids of the fuel cell 20.Advantageously, the holding members 52 and the complementary members 30 provide electrical insulation between the stack 50 and the jacket 24.

[0081] Each circulation conduit is fluidically connected to a respective connector 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.

[0082] The fuel cell 20 here provides six circulation ducts, which are respectively associated in pairs with the three operating fluids of the fuel cell. These six circulation ducts thus include a first pair of ducts 38A, which are fluidically connected to the first pair of connectors 28A, a second pair of ducts 38B, which are fluidically connected to the second pair of connectors 28B, and a third pair of ducts 38C, which are fluidically connected to the third pair of connectors 28C.

[0083] Each circulation conduit 38A, 38B or 38C is thus separated, in a sealed manner, from the neighboring conduits. In the present description, by "sealed" is meant 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 given its small molecular size and its low viscosity compared to the other operating fluids.

[0084] In the example illustrated more particularly by Figures 1 and 3, the jacket 24 is therefore an external wall of the cell 20, the jacket 24 delimiting the circulation conduits 38A, 38B or 38C in which a fluid circulates under a pressure higher than atmospheric pressure. Even if this pressure is generally less than 5 bars absolute, or even less than 3 bars absolute, it is necessary to take into account the pressure difference with the atmospheric pressure which prevails outside the jacket 24, ensuring in particular that the jacket 24 does not deform (in particular by bulging) to the point of compromising the seal between the circulation conduits 38A, 38B or 38C. In the example illustrated, to limit deformation by bulging, in particular of the larger faces of the jacket 24, external reinforcements have been provided.In the example, the external reinforcements are independent of the jacket 24, are therefore attached to the jacket and are fixed to the outside of the jacket 24, each bearing on a face (here a flat external face) of the jacket 24. Each external reinforcement extends along the stack axis A20 between two ends. In the example, each end is fixed, for example by screwing, to the corresponding cover 26A, 26B. Alternatively, the external reinforcement(s) are fixed exclusively to the jacket 24, or are even fixed on one side to the jacket 24 and on the other side to only one of the two covers. Each external reinforcement comprises a central body bearing on the corresponding external face of the jacket 24.In the illustrated example, only two external reinforcements have been provided, one on each of the two opposite faces of the jacket 24 which have the largest surface area, and therefore present the greatest risk of deformation due to the 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 jacket 24. In the illustrated example, the central body of an external reinforcement has a transverse width, in a direction orthoradial to the stack axis A20 and parallel to the corresponding external face of the jacket 24, which is preferably greater than or equal to 50% of the transverse width of said corresponding external face on which it is supported, so that only one external reinforcement is necessary for the corresponding external face.However, it would be possible to provide, for a given external face of the jacket 24, several separate individual reinforcements, offset from each other in the transverse direction, and therefore each of small transverse width. In the example illustrated, the external reinforcement has stiffeners, here in a single piece with the central body, forming an excess thickness on the central body in a radial direction perpendicular to the stack axis A20 and perpendicular to the corresponding external face of the jacket 24. Advantageously, the stiffener(s) have a radial thickness, in the radial direction, which changes along the direction of the stack axis A20, with a lesser radial thickness at the two ends, and on the contrary a greater radial thickness in the center in this direction.This makes it possible to optimize the stiffness of the stiffener by adapting it to the stresses undergone by the jacket 24, at different points thereof, due to the pressure inside the conduits. The added external reinforcement(s) are preferably made of metal, for example aluminum or aluminum alloy, for example in the form of a molded part made of aluminum alloy. Alternatively, the added external reinforcement(s) are made of polymer material, preferably then of 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 jacket 24, in other words made in a single piece with the jacket, thus giving the jacket an optimized geometry to withstand the forces due to the pressures of the fluids in the circulation conduits 38A, 38B or 38C.The unit cells 100 of the stack 50 are preferably identical to each other. The unit cell 100 is now detailed.

[0085] As illustrated in FIG. 4, the cell 100 comprises several walls 102, which are continuous and sealed and which are stacked on top of each 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 between them compartments V100 of the unit cell 100.

[0086] Still in Figure 4, the second separator 120 is shown schematically in dotted lines. The first separator 110 and the second separator 120 are preferably identical to each other and are here produced by cutting a metal sheet, for example a stainless steel sheet.

[0087] The membrane 130, also called PEM for “Proton Exchange Membrane” in English, is here produced in the form of a polymer layer 130A. Generally, there is, on either side of the membrane 130, in each of the compartments V100 delimited by the membrane 130 on either side thereof, a gas diffusion layer 130B, such that the membrane 130 is sandwiched between the two gas diffusion layers 130B. The polymer layer 130A is here produced from a fluoropolymer material, for example known under the trade name Nation.

[0088] In the illustrated example, the polymer layer 130A is covered on both sides with a catalyst layer, the membrane 130 being called CCM for “Catalyst Coated Membrane” in English. The catalyst layers are not shown. The membrane 130, the gas diffusion layers 130A and 130B and the associated catalyst layers together generally form a MEA, an acronym for “Membrane Electrode Assembly”.

[0089] Alternatively not shown, 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.

[0090] The polymer layer 130A is impermeable to reactive gases, hydrogen or oxygen, but allows the diffusion, through it, of H+ protons. The gas diffusion layers 130B, also called GDL for "gas diffusion layer" in English, are porous for reactive gases and are for example made essentially of entangled and compressed carbon fibers. The gas diffusion layers 130B may optionally be coated on their face in contact with the membrane 130A with an ionomer which may be of the same nature as the material of the polymer layer 130A. The structure of the membrane 130 is not detailed further. 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 mean plane P50. The first face 132 is oriented towards the side of the first separator 110.The first separator 110 delimits with the membrane 130 a first reactive compartment V132, which is configured to receive a first operating fluid of the fuel cell 20. The first reactive compartment V132 is here for example an anode compartment of the unit cell 100, that is to say that the first operating fluid is hydrogen. Thus the first operating fluid is a gaseous fluid. The first reactive compartment V132 is one of the compartments V100 of the cell 100.

[0091] The second face 134 is oriented towards the second separator 120. The second separator 120 delimits with the membrane 130 a second reactive compartment V134, which is configured to receive a second operating fluid of the fuel cell. The second reactive compartment V134 is for example here a cathode compartment of the unit cell 100, that is to say that the operating fluid circulating in this compartment is here air, which contains oxygen. Thus the second operating fluid is a gaseous fluid. The second reactive compartment V134 is another of the compartments V100 of the cell 100.

[0092] It is understood that when three unit cells 100 are stacked on top of each other, with a bottom cell 100, a middle cell 100 and a top cell 100, the first separator 110 of the middle cell is found adjacent to the second separator 120 of the top cell 100.

[0093] In the illustrated example, the first separator 110 of the middle cell 100 and the second separator 120 of the upper cell delimit between them a first cooling compartment V136 of the middle cell 100.

[0094] The first cooling compartment V136 is therefore common to two neighboring cells 100. The second separator 120 of the middle cell 100 and the first separator 110 of the bottom cell 100 delimit between them a second cooling compartment V138 of the middle cell. For two stacked unit cells 100, the first cooling compartment V136 of the bottom cell is therefore, for the top cell, a second compartment V138.

[0095] More generally, for the cell 100 described, each cooling compartment V136 and V138 is configured to receive a third operating fluid from the fuel cell 20. The third operating fluid is here a cooling fluid such as glycolated liquid water. Thus the third operating fluid is here a liquid fluid at the operating temperatures of the cell 20. More generally, the first separator 110 is configured to separate in a sealed manner the first reactive compartment V132 from the first cooling compartment V136.

[0096] In the illustrated example, each unit cell 100 therefore comprises three compartments V100, namely the first reactive compartment V132, the second reactive compartment V134, and the first cooling compartment V136. Each of these compartments V100 is respectively associated with an operating fluid of the fuel cell 20.

[0097] The fuel cell 20 here houses, in each of the compartments V100 of the unit cell 100, an irrigation spacer. More precisely, the second reactive compartment V134 houses an irrigation spacer 600 of a first type, according to a first embodiment, while the first reactive compartment V132 houses an irrigation spacer 700 of a second type, according to another embodiment. The first cooling housing V136 also houses another example of the spacer 700 of the second type.

[0098] The irrigation spacers 600 or 700 are configured to define the circulation, within each compartment V100, 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, as well as the spacers 600 and 700, are supported on each other. 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.

[0099] According to another aspect, the unit cell 100 also comprises a sealing structure 200 (FIG. 5). The sealing structure comprises frames 210, which are each made of a polymer material and which are stacked along the stacking axis A50. The frames 210 are arranged at the periphery of the walls 102 and the compartments V100 of the unit cell 100.

[0100] The principles of the sealing structure 200 are described with the aid of FIG. 5, where two walls 102 of the unit cell 100, delimiting a single compartment V100, are represented. The wall 102 on the top of FIG. 5 a) is here the membrane 130, while the wall 102 on the bottom of FIG. 5 a) is the second separator 120. The compartment represented is therefore the second reactive compartment V134, knowing that the principles described can be transposed to the other compartments V100 of the unit cell 100 and to the corresponding walls 102. The rest of the unit cell 100, in particular the irrigation spacer 600 or the diffusion layer 130B, is not represented so as not to overload the figures which aim to represent this sealing structure more particularly.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 which 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 “facing” each other.

[0101] In the illustrated example, the frames 210 of the sealing structure 200 include wall frames 220, each wall frame 220 being coplanar with a respective wall 102 and surrounding this wall 102. In Figure 5 a), the wall frames 220 and the associated walls are shown offset to facilitate distinction between the parts, while in Figure 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. Preferably, each wall frame 220 has a thickness substantially equal, for example equal to ±10%, to a thickness of the corresponding wall 102, the thicknesses being measured parallel to the stacking axis A50.

[0102] The frames 210 of the sealing structure 200 also include compartment frames 230. Each compartment frame 230 is arranged on the periphery of the corresponding compartment V100, here the second reactive compartment V134. A single 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.

[0103] Each frame 210 of the sealing structure 200 generally has a ring shape, in the example a rectangular ring shape, and is formed in a plate of a waterproof 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 called PET.

[0104] Each frame 210 comprises two faces 213, which are opposite each other and which extend parallel to the mean plane P50, an inner edge 214, which connects the two faces 213 to each other and which is oriented towards an inner side of the unit cell 100, and an outer edge 215, which is opposite the inner edge 214 and which connects the two faces 213 to each other. For each frame 210, the inner edge 214 defines, in projection onto the mean plane P50, an inner contour of this frame 210, while the outer edge 215 defines, in projection onto the mean plane P50, an outer contour of this frame 210. In the case of the wall frames 220, the inner edge 214 extends opposite the corresponding wall 102. In the case of 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.

[0105] Similarly, each wall 102 comprises two faces 103 which are opposite each other and which extend parallel to the mean 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 mean plane P50, an external contour of this wall 102.

[0106] 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 facing wall 102 being separated, radially to the stacking axis A50, by a peripheral gap I220. Each wall 102 is therefore associated with a peripheral gap I220 specific to this wall 102 and to the corresponding facing wall frame 220. Consequently, each wall frame 220 is therefore associated with a peripheral gap I220 specific to this wall frame 220 and to the corresponding facing wall 102.

[0107] The peripheral gap I220 is the smallest possible. The peripheral gap I220 is typically between 0 mm (millimeter) and 0.2 mm. In reality, the peripheral gap I220 is not zero, in particular because of manufacturing tolerances and assembly clearances. In the example illustrated, I220 is equal to 0.1 mm.

[0108] The sealing structure 200 also includes layers of adhesives 240, which are interposed between each of the frames 210 of the sealing structure so as to fix, in a sealed manner, the frames 210 to each other. Each layer of adhesive 240 is thus taken 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 interposed 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 interposed 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.

[0109] Each layer of adhesive 240 is made of a waterproof material, preferably a “contact” type adhesive, also called PSA for “Pressure Sensitive Adhesive” in English. Advantageously, each layer of adhesive 240 is repositionable, so that the sealing structure 200 is removable, the unit cell 100 being by extension also removable. Non-limiting examples of adhesives include acrylic glues. Each layer of adhesive 240 is made of an electrically insulating material. Thus the sealing structure 200, formed by the assembly of the frames 210 assembled to each other by layers of adhesive, ensures not only the sealing between two neighboring compartments V100, but also the sealing and electrical insulation of each compartment V100 with respect to the exterior of the unit cell.

[0110] 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 secures. For example, for the assembly of two faces, the layer of adhesive 240 is applied by coating on one of the faces to be assembled, 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 interposed between these two layers of adhesive 240.

[0111] 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.

[0112] In the illustrated example, the compartment frame 230 is interposed, 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.

[0113] 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.

[0114] 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, in the external contour of the compartment frame 230, so 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 on this wall frame 220. The second overlap S232 corresponds to the projection, parallel to the stacking axis A50, of the compartment frame 230 on the adjacent wall frame 220. Thus the second overlap 232 corresponds here to that of the faces 223 of the wall frame 220 which is oriented towards the compartment frame considered.

[0115] Preferably, the external contours of all the frames 210 of the sealing structure 200 are superimposed on each other along the stacking axis A50, the external edges of all the frames of all the sealing structures together forming an external surface S100 of the unit cell 100. The external surface S50 of the stack 50 corresponds to the meeting of the external surfaces S100 of the unit cells 100 which compose this stack 50. Optionally, during the assembly of the stack 50, the external surface S50 is ground after the assembly of the unit cells 100, so that the external surface S50 is smooth.

[0116] For the adhesive layer 240 interposed between the compartment frame 230 and the adjacent wall 102, this adhesive layer 240 comprises a first portion, called first layer portion 241, which extends opposite the first overlap S231 between the compartment frame 230 and the adjacent wall 102, so as to fix, in a sealed manner, this compartment frame 230 to the adjacent wall 102.

[0117] Similarly, this adhesive layer 240 comprises a second portion, called 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 sealed manner, this compartment frame 230 to this wall frame 220.

[0118] The first layer portion 241 and the second layer portion 242 are arranged in the same plane transverse to the stacking axis A50. The first layer portion 241 is, in this transverse plane, surrounded by the second layer portion 242.

[0119] Advantageously, the adhesive layer 240 comprises a third portion, called third layer portion 243, which is interposed radially, in the same plane transverse to the stacking axis A50, between the first layer portion 241 and second layer portion 242 and which therefore joins the first layer portion 241 and second layer portion 242 to each other. The third layer portion 243 of the adhesive layer is located opposite, along the stacking axis A50, the peripheral gap I220. The third layer portion 243 of the adhesive layer 240 continuously connects the first layer 242 to the second layer portion 242. In other words, the first adhesive layer portion 241 and the second adhesive layer portion 242 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.The first overlap 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 internal edge 214 of the corresponding compartment frame 230 and to the external 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 I220, passing between the compartment frame 230 and the adjacent wall 102 considered.

[0120] Similarly, the second overlap 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 to 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 I220 and the outside of the unit cell 100, passing between the compartment frame 230 and the adjacent wall frame 220 considered.

[0121] Each leakage length L231 or L232 is greater than or equal to 1 mm, preferably greater than or equal to 2 mm, more preferably greater than or equal to 3 mm. This ensures a seal greater than a minimum value, on the one hand, between each of the compartments V100 and the outside of the cell 100 and, on the other hand, between two neighboring compartments V100.

[0122] Preferably, the compartment frame 230 and the two associated adhesive layers 240 are manufactured by coating an adhesive material on both sides of the compartment frame 230, 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.

[0123] The assembly formed by the compartment frame 230 coated with the two associated adhesive layers 240 thus forms a frame called a “double-sided adhesive frame”. The compartment frame 230 thus forms a continuous and sealed 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 comprising a continuous sealed 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.

[0124] Such a sealing structure 200 does not include a fluid inlet or outlet passage in the associated compartment V100. If such an inlet and / or type of fluid must 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 which delimit the compartment.

[0125] A sealing structure 300, according to another embodiment, is shown in Figure 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 the compartment V100 to circulate. A single fluid passage 332 is shown in Figure 6. The transfer frames 330 are therefore part of the frames 210. In this embodiment of the sealing structure 300, each compartment frame 330 only comprises the transfer frame.

[0126] One of the two fluid passages 332 is an inlet for the operating fluid, while the other passage 332 is an outlet for the operating fluid, the notions of “inlet” and “outlet” depending on the direction of circulation of the operating fluid. The fluid passages 332 thus connect the compartment V100 and the exterior of the cell 100.

[0127] 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 sealed manner, with respect to the exterior, the transfer frame 330 to the adjacent wall frames 220 and to the associated walls 102.

[0128] 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 in the stacking direction less than the thickness of the transfer frame and a circumferential extent.

[0129] 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.

[0130] Each passage 332 thus comprises an internal portion 334B, which opens via the internal mouth 334 into the corresponding compartment V100. The internal portion 334B of each passage 332 is formed in the thickness of the transfer frame 330. Such an arrangement thus makes it possible to economically form the passages 332 in each of the transfer frames 330, so as to supply each compartment V100 with the corresponding operating fluid. In the example illustrated, the external mouth 335 of each passage 332 of the transfer frame 330 is advantageously formed on the external edge 215 of the transfer frame 335, so as to communicate fluidically 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 ducts 38A, 38B or 38C while the other of the passages 332 of this same transfer frame 330 communicates with the other of the circulation ducts 38A, 38B or 38C which belongs to the same pair of ducts.

[0131] In other words, for each of the two passages 332 of the same transfer frame 330, the external mouth 335 associated with this passage 332 opens onto the external edge 215 of this transfer frame 330 in a separate conduit among the circulation conduits of the associated pair.

[0132] In a variant not illustrated, the external mouth 335 is arranged differently, for example oriented axially 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, using an arrangement known in the field of polar plates known as “internal manifold”.

[0133] Advantageously, each passage 332 houses fins 336 for guiding the associated operating fluid. Alternatively, only one of the two passages 332 comprises the fins 336. Within each fluid passage 332, the fins 336 form pillars, which keep the two layers of adhesives 240 associated with the transfer frame 330 in question at a distance. Two neighboring fins 336 delimit a channel between them. Each fluid passage 332 is therefore formed from the meeting of the channels delimited between the fins 336. The shape of each fin 336 is chosen so as to hinder as little as possible the flow of the operating fluids passing through the passages 332, while ensuring the transfer of the forces of the mechanical clamping forces of the stack 50, these clamping forces being parallel to the stack axis A50.

[0134] The fins 336 are preferably formed, during the manufacture of the transfer frame 330, by cutting 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 by means of the adhesive layers arranged on either side of the transfer frame 330 in question, here the adhesive layers 240, between which the transfer frame 330 is interposed. The fins 336 are advantageously distributed at a distance from each other within the corresponding passage 332, so as to direct the flow of the associated operating fluid. Preferably, the fins 336 are regularly distributed in the corresponding passage 332.

[0135] 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 interposed between the two corresponding adhesive layers 240, an additional frame, called the first sealing frame 432, which is interposed 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 interposed 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 Figure 7, the first sealing frame 432 is associated with the wall 102 and the wall frame 220 located at the bottom of the figure.

[0136] 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 secure the transfer frame 330 to the adjacent first sealing frame 432.

[0137] Preferably, the adhesive film 440 is here made of a sufficiently hard material, chosen so as to avoid adhesive creep, in particular between the fins 336, under the effect of pressure, and thus to avoid obstruction of the fluid passages 332. The adhesive film 440 here comprises tabs 441, which correspond to the fins 336 of the transfer frame 330. The tabs 441 here form a discontinuous portion of the adhesive film 440. In a variant not shown, the adhesive film 440 does not comprise a tab and is continuous in the circumferential direction around the stacking axis A50, in the manner of the adhesive layers 240.

[0138] 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 sealed manner to the adjacent wall 102, and to the wall frame 220 opposite this wall 102, by the corresponding adhesive layer 240.

[0139] The sealing frame 432, which extends continuously, in the radial direction and in the circumferential direction around the stacking axis A50, faces the peripheral gap I220 formed between this wall 102 and the wall frame 210 opposite it, thus providing the adhesive layer 240 with a continuous support, which improves the sealing of the corresponding compartment V100 compared to the situation without the sealing frame 432. The presence of a sealing frame 432 is particularly advantageous in the case where the operating 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 V132 or around the second reactive compartment V134, where hydrogen and air circulate respectively.

[0140] 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, preferably, the adhesive film 440 has the same shape, in the sense of the same internal and external contour, as the corresponding first sealing frame 432 and the transfer frame.

[0141] 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 risks of hydrogen pollution on the other side of the membrane 130. More preferably, sealing frames 432 are arranged in each of the reactive compartments V132 and V134, on either side of the membrane 130, so as to avoid gas transfers between the two reactive compartments V132 and V134.

[0142] Preferably, the sealing frame 432 and the associated adhesive layer 240 are manufactured by coating an adhesive material on one of the two faces of the sealing frame 432, 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.

[0143] The assembly formed by the sealing frame 432 coated with an associated adhesive layer 240 thus forms a frame called a “single-sided adhesive frame”. The sealing frame 432 thus forms a continuous and sealed 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 sealed 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.

[0144] 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.

[0145] Compared to the sealing structures 300 and 400 described previously with reference to FIGS. 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 risks of pollution of the compartment V100 and of the operating fluid circulating in this compartment V100. The risk of obstruction of the fluid passages 332 by the creep of the adhesive films 442 is also reduced.

[0146] 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 corresponding wall 102 and 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 sealing structure.

[0147] Advantageously, for each of the two sealing frames 432, the associated adhesive layer 240 is coated on the sealing frame 432, so as to form a single-sided adhesive frame. During manufacture, each frame 432 and the associated adhesive layer 240 are formed during the same steps, by cutting out a single-sided adhesive plate.

[0148] It is understood that for each wall 102 of the unit cell 100, when the compartments located on each side of this wall 102 comprise transfer frames 330 taken between two adhesive films 440, it is particularly advantageous to seal the gap I220, using a sealing frame 432 and an associated adhesive layer 240, at least on one of the faces 103 of this wall 102, because the adhesive films 440 might not be sufficient to guarantee sufficient sealing. 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 fluoropolymer and which is more fragile and more difficult to stick than the separators 110 and 120, which are here made of stainless steel.

[0149] In the example of Figure 8, the compartment V100 considered 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.

[0150] More preferably, all the compartments V100 in which gases circulate, i.e. here the first reactive compartment V132 and the second reactive compartment V134, are each delimited by two sealing frames 432 on either side of a compartment frame 330 associated with this reactive compartment.

[0151] Figure 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 shown in Figure 8.

[0152] Compared to the sealing structure 500 shown in Figure 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 the compartment V100, here on the other side of the wall 102 located on the bottom of Figure 9 a), this sealing frame 432 therefore belonging, in a stack, to the compartment frame of the compartment neighboring the compartment V100 considered, located on the other side of the wall 102 located on the bottom of Figure 9 a). The adhesive layer 240 associated with this wall 102 is therefore interposed, on the other side of the wall 102 relative to the compartment V100 considered, between the sealing frame 432 and the wall 102, so as to close the gap I220. The gap I220 is not shown in FIG. 9.

[0153] Compared to the sealing structure 500 shown in Figure 8, in the case of the sealing structure 500" shown in Figure 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 the compartment V100. In other words, the transfer frame 330 associated with the compartment V100 of Figure 9 b) is interposed between the two wall frames 220 which immediately surround it in the stacking direction A50, without interposition of any sealing frame between this transfer frame 330 and these two wall frames 220. On the other hand, such sealing frames 432 are provided immediately in contact with each of these two wall frames 220 with, for each wall frame only, interposition of a layer of adhesive 240 between the frame sealing 432 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 at the bottom of figure 9 b) and on the other side of the wall 102 located towards the top of figure 9 b).In all cases in which the compartment frame comprises a sealing frame 432, and in particular in all cases in which 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 layer portion, which extends facing the first overlap between the compartment frame (here the sealing frame forming part of this compartment frame) and the wall, so as to fix, in a sealed manner, the compartment frame to the wall. This first layer portion 241 is therefore in these cases facing and in contact with the sealing frame 432 and the wall.This same adhesive layer 240 includes the second layer portion 242, which extends facing the second overlap between the compartment frame (here again the sealing frame forming part of this compartment frame) and the wall frame, so as to fix, in a sealed manner, the compartment frame to the wall frame. This second layer portion 242 is therefore in these cases facing 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 are preferably part of the same adhesive layer 240, as in the illustrations, which extends continuously over one face of the compartment frame, in this case a face of the sealing frame 432, the two first and second portions of adhesive layer 241 and 242 therefore being 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.

[0154] 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.

[0155] 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 V100 of the unit cell 100.

[0156] 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 μm and 20 μm, preferably equal to 12 μm. 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 μm and 30 μm, preferably of between 8 μm and 20 μm, preferably of between 10 μm and 15 μm.

[0157] 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 pm and 600 pm, preferably of between 80 pm and 150 pm, more preferably equal to 100 pm.

[0158] For each adhesive layer 240, the first layer portion and the second layer portion each have a thickness, measured parallel to the stacking axis, of between 15 μm and 30 μm, preferably of between 18 μm and 25 μm, preferably equal to 20 μm. Preferably, the thickness is identical for the first layer portion and the second layer portion.

[0159] The unit cell 100 is shown schematically in section in Figure 10. As indicated by dotted lines, this unit cell is repeated in the stack.

[0160] The first reactive compartment V132 here houses an example of the spacer 700 of the second type. On the periphery of the first reactive compartment V132, the frames 210 which form the compartment frame corresponding to this compartment comprise a transfer frame 330, which provides the two passages 332 associated with the first reactive compartment V132, 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.

[0161] The second reactive compartment V134 here houses a copy 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 V134 comprise a transfer frame 330, which provides the two passages 332 associated with the second reactive compartment V132, 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.

[0162] The cooling compartment V136 here houses a second example of the spacer 700 of the second type. On the periphery of the cooling compartment V136, the frames 210 which 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.

[0163] It is noted, however, that a given sealing structure can be implemented regardless of the type of spacer contained in a given compartment. In FIG. 10, the passages 332 are schematically represented by dotted arrows. In particular, the passages 332 for each of the compartments V132, V134 and V136 are represented as if they were aligned along the stacking axis A50, this illustration being schematic. As seen in Figure 4, the location and extent in the circumferential direction of the passages 332 are adjusted according to the type and orientation of the irrigation spacers 600 or 700. Preferably, as illustrated in Figure 4, the passages 332 for each of the compartments V132, V134 and V136 of the same unit cell 100 are offset from each other on the perimeter of the cell, preferably being substantially diametrically opposed to 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 set of unit cells 100 of the stack are preferably aligned along the stacking axis A50, and the passages 332 of each of the cooling compartments V136 of the set of unit cells 100 of the stack are preferably aligned along the stacking axis A50.

[0164] In the example of Figure 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 I220 associated with the wall 102 separating the two reactive compartments V132 and V134, in other words the gap I220 associated with the membrane 130, is closed, on both faces of the membrane 130, by a respective sealing frame 432. For each compartment frame of the first reactive compartment V132 and of the second reactive compartment V134, 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.

[0165] In the example of Figure 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 I220 associated with the first separator 110 is only closed by a sealing frame 432 on one side of the first separator 110, and this sealing frame 432 is related to the compartment frame of the neighboring compartment, namely here to the first reactive compartment V132. Similarly, by the pattern effect due to the stacking of identical cells, the peripheral gap I220 associated with the second separator 120 is only closed by a sealing frame 432 on one side of the first separator 110, this sealing frame 432 is related to the compartment frame of the first reactive compartment V132.Of course, to ensure the seal, it would have been possible to provide, for the cooling compartment V136, a compartment frame comprising a sealing frame on one side of the transfer frame 330, or comprising two sealing frames, on each side, of the transfer frame 330.

[0166] 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 V134, but does not comprise a cooling compartment. The cooling of the unit cell 200 is here ensured by the passage of air, which here circulates in the second reactive compartment V134.

[0167] Unlike the unit cell 100 of the previous embodiment, the second reactive compartment V134 is here delimited by a compartment frame comprising a single sealing frame 432. In the example of FIG. 11, the peripheral gap I220 associated with the membrane 130 is closed on one side only 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 here has a thickness greater than the transfer frame 330 of the previous embodiment, so that the fluid passage 332 allows a higher flow rate of the associated operating fluid - here air -, which is used both for the electrochemical reaction of the fuel cell and for cooling the cell.

[0168] Regardless of the number of compartments V100 of the unit cell 100, with or without cooling compartment V136, for each compartment V100, and for each of the walls 102 delimiting this compartment V100, the peripheral gap I220 associated with this wall 102 is closed, on at least one of the faces 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 I220 associated with this wall 102 is closed, on at least one of the faces of this wall, by a continuous frame over the entire circumference of this gap I220.

[0169] Preferably, the reactive compartment where the hydrogen circulates, here the first compartment V132, 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 I220 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.

[0170] Preferably, each sealing frame 432 and the associated adhesive layer 240 are produced by cutting out a single-sided adhesive plate.

[0171] Preferably, each transfer frame 330 and the two associated adhesive films 440 are produced by cutting out a double-sided adhesive plate.

[0172] The irrigation spacer 600 of the first type is now described with the aid of Figures 12 and 13.

[0173] The irrigation spacer 600, also simply called “spacer 600”, has a generally rectangular shape, with two opposite long sides and two opposite short sides, and is planar, which extends 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 reference frame.

[0174] The spacer 600 comprises two distribution plates 602, including a first plate 602A and a second plate 602B. The distribution plates 602 each comprise two opposing faces, including a first face 604 and a second face 605.

[0175] The two plates 602 are stacked flat on top of each 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 else parallel to the mean plane P50 of the corresponding unit cell 100.

[0176] 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, more preferably equal, within ±5%, to 75 μm. Preferably, the distribution plates 602 have the same thickness.

[0177] Each distribution plate 602 comprises perforations 610, which are formed by cutting out this distribution plate 602. The perforations 610 are through-perforations, that is to say that the perforations 610 open onto the two opposite faces 604 and 605 of this distribution plate 602.

[0178] 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 V100 where the irrigation spacer 600 is housed.

[0179] The irrigation spacer 600 comprises a fluid inlet 613A and a fluid outlet 613B, the inlet 613A and the outlet 613B being fluidically connected to each other by the channel network 612. The notions of “inlet” and “outlet” are relative, and depend on the direction of circulation of the flow fluid. In the example illustrated, the inlet 613A and the outlet 613B are respectively provided on the short sides of the spacer 600.

[0180] The perforations 610 of each distribution plate 602 have an elongated shape, two neighboring perforations 610 extending along one another and being separated from one another by a strip 614 of material. Each perforation 610 is delimited by two opposite longitudinal edges 616, each of the two longitudinal edges 616 corresponding to one edge of the two strips 614 of material which delimit each perforation 610.

[0181] Each distribution plate 602 also comprises crosspieces 618, which extend through the perforations 610, in the thickness of the distribution plate 602, and which keep the strips 614 at a distance from each other. Each crosspiece 618 thus connects to each other the two longitudinal edges 616 of the perforation 610 through which this crosspiece 618 extends.

[0182] 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 network 612 of channels. In other words, in the first portion 620 of the network 612 of channels, 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 a single portion 620, in other words the first portion 620 represents the entire network 612 of channels. The first portion 620 of the network 612 is represented by a dotted frame.

[0183] To the first portion 620 of the network 612 of channels corresponds, on each of the distribution plates 602, 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.

[0184] The crosspieces 618 of the first plate 602A are offset, in the mean plane P600 of the spacer 600, relative to the crosspieces 618 of the second plate 602B, so as not to prevent the circulation of the operating fluids in the channels of the first portion 620 of the network 612 of channels of the irrigation spacer 600. In the insert 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 operating 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 crosspieces 618, which are offset from each other in the direction of the channel, two crosspieces 618 of the spacer 600, which extend through a given channel and which do not belong to the same distribution plate 602, being therefore offset from each other in the direction of the channel.

[0185] In the first portion 620 of the channel network, the strips 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.

[0186] 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, such 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.

[0187] Preferably, in the first portion 620 of the network 612 of channels, the strips 614 of the irrigation spacer 600 are rectilinear in orthogonal projection on the mean plane P600 of the spacer 600. Thus the channels of the first portion of the network of channels are rectilinear.

[0188] Preferably, in the first portion 620 of the network 612 of channels, the perforations 610 each have the same width Σ610, which is between 0.2 mm and 1.1 mm, while the strips 614 of material separating two neighboring perforations 610 each have a width Σ614 between 0.2 mm and 0.7 mm. This ensures both good flow of the operating fluid and good transfer of the compression 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.

[0189] Preferably, in the first portion 620 of the network 612 of channels, each crosspiece 618 has a height equal to a height of the strips 614 of material adjacent to the perforation 610 in which this crosspiece 618 is arranged, the height of the crosspieces and the height of the strips being measured parallel to the height axis. The manufacturing method is thus simplified, each distribution plate 602 being produced by simple cutting.

[0190] The irrigation spacer 700 of the second type is now described with the aid of figures 14 and 15. The elements identical to those of the irrigation spacer 600 of the first type bear the same references.

[0191] Whereas for the spacer 600 of the first type, each channel of the network 612 of channels is rectilinear from one end to the other, that is to say from the inlet 613A to the outlet 613B, the spacer 700 of the second type comprises a network of channels 712, in which each channel is formed of several rectilinear portions, two consecutive portions not being aligned with each other.

[0192] The spacer 700 comprises an inlet 713A and an outlet 713B, each of which is provided on a respective long side of the rectangle. Advantageously, each channel of the network 712 extends continuously from the inlet 713A to the outlet 713B.

[0193] 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 respective strip 614 of material.

[0194] In the illustrated example, the network 712 of channels comprises three consecutive portions, including a first portion 714A, a second portion 714B, and a third portion 714C, the contours of the three portions 714A, 714B and 714C being shown in dotted lines in Figures 14 and 15. More generally, the number of portions is chosen as a function of the geometry of the spacer, the arrangement of the fluid inlet and the fluid outlet, etc. What is valid for the first and second portions 714A and 714B of the network 712 of channels is transposable to any two consecutive portions of the network 712 of the network of channels.

[0195] The spacer 700 comprises two distribution plates 702, including a first plate 702A and a second plate 702B. The portions 714A, 714B and 714C of the network 712 of channels 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 network 712 of channels.

[0196] 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 respective strip 614 of material. 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 network 712 of channels of the irrigation spacer 700, the channels of the second portion 714B of the network 712 of channels being parallel to each other.

[0197] For each distribution plate 702A or 702B, each strip 614 of the first portion 724A of this distribution plate extends, continuously, with a strip 614 of the second portion 724B of this same distribution plate.

[0198] For each distribution plate 702A or 702B, the strips 614 of the first portion 724A are rectilinear 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 strips 614 of the second portion 724B are rectilinear 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.

[0199] The first flow axis 716A and the second flow axis 716B are distinct, that is to say that the operating fluid circulating in each channel of the network 712 changes direction when passing from the first portion 714A to the second portion 714B.

[0200] 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°, more preferably between 60° and 120°. In the example illustrated, the first flow axis 716A and the second flow axis 716B form an angle between them of 90°.

[0201] In the illustrated examples, each of the compartments among the first reactive compartment V132, the second reactive compartment V134 and the first cooling compartment V126 houses an irrigation spacer 600 or 700 according to the invention.

[0202] In a variant not shown, only one of the housings V100 of the unit cell 100 receives an irrigation spacer of another type, the other two housings V100 each receiving an irrigation spacer in accordance with the invention. According to another variant not shown, only one of the housings V100 of the unit cell 100 receives an irrigation spacer in accordance with the invention, the other two housings V100 each receiving an irrigation spacer of another type. The embodiments and variants mentioned above can be combined with each other to generate new embodiments of the invention.

Claims

CLAIMS 1. Unit cell (100) of a stack (50) of fuel cells (20), in which: the unit cell comprises several walls (102), which are each continuous and sealed and which are stacked on top of each other along a stacking axis (A50), these walls (102) delimiting compartments (V100) of the unit cell and including: • a first separator (110), • a second separator (120), and • a proton exchange membrane (130), which is interposed between the first separator and the second separator, the first separator delimits with the membrane a first reactive compartment (V132), the first reactive compartment (V132) being configured to receive a first operating fluid of the fuel cell, the second separator delimits with the membrane (130) a second reactive compartment (V134), the second reactive compartment (V132) being configured to receive a second operating fluid of the fuel cell, the compartments (V100) of the unit cell include the first reactive compartment (V132) and the second reactive compartment (V134), the cell also comprises a sealing structure (200; 300; 400;500), the sealing structure comprising frames (210), which are each made of a polymer material and which are stacked along the stacking axis (A50), the frames being arranged at the periphery of the walls (102) and the compartments, characterized in that, for at least one of the compartments (V100) of the unit cell (100), and for at least one of the two walls (102) delimiting this at least one compartment: the frames (210) of the sealing structure include:; • a wall frame (220), which is coplanar with the corresponding wall and which surrounds this wall, an internal edge (214) of each wall frame (220) being arranged opposite an external edge (105) of this wall (102), the internal edge of the wall frame (220) and the external edge of the wall being opposite each other and being separated by a peripheral gap (1220), each wall frame (220) having a thickness substantially equal to a thickness of the corresponding wall (102), • a compartment frame (230; 330; 430; 530), which is arranged on the periphery of the corresponding compartment (V100), the compartment frame comprising an inner edge (214), which is oriented towards the corresponding compartment (V100) and which delimits this compartment radially to the stacking axis (A50), and an outer edge (215), opposite the inner edge, the inner edge having an inner contour, while the outer edge has an outer contour, • adhesive layers (240), which are each interposed between, on the one hand, a compartment frame, and, on the other hand, the wall and the wall frame adjacent to this compartment frame, so as to fix, in a sealed manner, the frames to each other, the internal contour of the compartment frame (230; 330; 430; 530) is included, in projection along the stacking axis (A50), in an external contour of the wall, so that an annular portion of the wall faces, along the stacking axis, a complementary portion of the compartment frame and forms a first overlap (S231) of the compartment frame on the wall, an internal contour of the wall frame (220) is included, in projection along the stacking axis, in the external contour of the compartment frame, so that an annular portion of the wall frame faces a complementary portion of the compartment frame and forms a second overlap (S232) of the frame compartment on the wall frame,the adhesive layers include a first layer portion (241), which extends facing the first overlap (S231) between the compartment frame and the adjacent wall, so as to fix, in a sealing manner, the compartment frame to the wall, and the adhesive layers include a second layer portion (242), which extends facing the second overlap between the compartment frame and the adjacent wall frame, so as to fix, in a sealing manner, the compartment frame to the wall frame., 2. Unit cell (100) according to claim 1, wherein: the first separator (110) is configured to tightly separate the first reactive compartment (V132) from a first compartment of cooling (V136), which is configured to receive a third operating fluid of the fuel cell (20), the compartments (V100) of the unit cell include, in addition to the first reactive compartment (V132) and the second reactive compartment (V134), the first cooling compartment (V136).

3. Unit cell (100) according to any one of claims 1 or 2, in which the first portion of layer (241) of adhesive and the second portion of layer (242) of adhesive are part of the same layer of adhesive (240), which extends continuously on one face of the compartment frame (230; 330; 430; 530), so as to close the peripheral gap (I220) adjacent to the compartment frame.

4. Unit cell (100) according to any one of claims 1 to 3, wherein: the first overlap (S231) has a trailing length (L231), which is equal to a minimum distance, measured parallel to the mean plane (P50), between any two points belonging respectively to the internal edge (214) of the corresponding compartment frame and at the outer edge (105) of the corresponding adjacent wall (102), the second overlap (S232) has a trailing 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 and at the inner edge (214) of the corresponding adjacent wall frame (220), each leakage length is greater than or equal to 1 mm, preferably greater than or equal to 2 mm, more preferably greater than or equal to 3 mm.

5. Unit cell (100) according to any one of claims 1 to 4, wherein, for at least one of the compartment frames: this compartment frame comprises a transfer frame (330) which provides two fluid passages (332), the two passages being provided for the circulation of the associated operating fluid between the corresponding compartment (V100) and the exterior of the unit cell (100), 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, and each passage (332) opens outside the compartment (V100) through an external opening (335).

6. Unit cell (100) according to claim 5, in which: each passage (332) comprises an internal portion (334B), which opens through the internal mouth (334) into the compartment (V100), the internal portion (334B) of the passage being formed in the thickness of the transfer frame (330).

7. Unit cell (100) according to any one of claims 5 or 6, wherein the external mouth (335) is provided on the external edge (215) of the transfer frame (330).

8. Unit cell (100) according to any one of claims 5 to 7, in which, for at least one transfer frame (330): at least one of the two passages (332) houses fins (336) for guiding the associated operating fluid, the fins are formed by cutting this transfer frame (330) and are distributed at a distance from each other within the corresponding passage, so as to direct the flow of the associated operating fluid, the fins (336) are held by means of the layers of adhesives (240) between which the corresponding transfer frame is interposed.

9. Unit cell (100) according to claim 5 to 8, wherein, for at least one of the first and second reactive compartments (V132, V134), the compartment frame (430; 530) comprises: • the transfer frame (330), • a first sealing frame (432), which is interposed between, on the one hand, the transfer frame and, on the other hand, a first of the two walls (102) adjacent to the compartment frame and the wall frame (220) opposite this first wall, • a first adhesive film (440), which is interposed between the first sealing frame (432) and the transfer frame (330), the first sealing frame (432) is, on the one hand, fixed to the first wall (102) and to the wall frame (220) opposite by the adhesive layer (240) associated with the first wall and, on the other hand, fixed to the transfer frame (330) by the first adhesive film (440).

10. Unit cell (100) according to claim 9, wherein: the compartment frame (530) comprises, in addition to the first sealing frame (432): • a second sealing frame (432), the first and second sealing frames being arranged on either side of the transfer frame (330), the second sealing frame being interposed between, on the one hand, the transfer frame and, on the other hand, a second of the two walls (102) adjacent to the compartment frame and the wall frame (220) associated with this second wall, the second wall being different from the first wall, • a second adhesive film (440), which is interposed between the second sealing frame (432) and the transfer frame (330), the second sealing frame (432) is, on the one hand, fixed to the second wall (102) and to the wall frame (220) opposite by the corresponding adhesive layer (240) and, on the other hand, fixed to the transfer frame (330) by the second adhesive film (440).

11. Unit cell (100) according to any one of claims 9 or 10, wherein, for at least one sealing frame (432), the adhesive film (240) associated with this sealing frame is coated, continuously, on one face of this sealing frame (432).

12. Unit cell (100) according to any one of claims 9 to 11, wherein, for at least one sealing frame (432): this sealing frame is made of a polymer material, for example PET, and has a thickness, measured parallel to the stacking axis (A50), of between 10 pm and 20 pm, preferably equal to 12 pm, the adhesive film (440) interposed between this sealing frame and the corresponding transfer frame (330) has a thickness, measured parallel to the stacking axis, of between 6 pm and 30 pm, preferably of between 8 pm and 20 pm, preferably of between 10 pm and 15 pm.

13. Unit cell (100) according to any one of claims 9 to 12, in which: for each compartment (V100) of the unit cell and for each of the walls (110, 120, 130) delimiting this compartment (V100), the interstice peripheral (1200) associated with this wall is closed, on at least one of the faces of this wall, by a sealing frame (432).

14. Unit cell (100) according to any one of claims 5 to 13, wherein, for at least one transfer frame (330): this transfer frame is made of a polymer material, for example PET, and has a thickness, measured parallel to the stacking axis (A50), of between 50 pm and 200 pm, preferably of between 80 pm and 150 pm, more preferably equal to 100 pm, each of the first adhesive layer portions (241) and each of the second adhesive layer portions (242) has a thickness, measured parallel to the stacking axis (A50), of between 15 pm and 30 pm, preferably of between 18 pm and 25 pm, preferably equal to 20 pm.

15. Fuel cell (20), comprising a stack (50) formed of several unit cells (100) stacked along the stacking axis (A50), each unit cell being in accordance with any one of the preceding claims, and a jacket (24), which provides an internal volume (V24) in which the stack is housed, in which: the frames (210) of the sealing structure (200; 300; 400; 500) of each of the unit cells each have a specific external edge (215), with an associated external contour, the external contours of all the frames of each sealing structure are superimposed on each other along the stacking axis (A50), the external edges of all the frames of all the sealing structures together forming an external surface (S50) of the stack, which has a cylinder shape centered on the stacking axis, the external surface (S50) of the stack cleaning of the maintenance organs (52),which are configured to cooperate with complementary members (30) arranged in the internal volume (V24) of the jacket, so as to maintain the stack (50) within the internal volume and to provide a peripheral volume (V50) between the stack (50) and the jacket (24), and the maintaining members and the complementary members are designed to divide the peripheral volume (V50) into several conduits (38A, 38B, 38C) for circulating the operating fluids of the fuel cell., Fuel cell according to claim 15, wherein: for each compartment (V100) of each unit cell (100), the associated compartment frame (330) comprises a transfer frame which provides two fluid passages (332), the two passages being provided for the circulation of the associated operating fluid between the corresponding compartment (V100) and the exterior of the unit cell (100), each passage (332) opens into the associated compartment (V100) through an internal opening (334), which is provided on the internal edge (214) of the transfer frame, and each passage (332) opens outside the compartment (V100) through an external opening (335).Fuel cell (20) according to claim 16, wherein: the external mouth (335) is provided on the external edge (215) of the transfer frame (330), the fuel cell provides two first pairs of circulation conduits (38A, 38B), which are respectively associated with the first and second operating fluids of the fuel cell, the unit cells (100) are in accordance with any one of claims 5 to 14 for each unit cell:. • each of the two compartments (V100) chosen from the first reactive compartment (V132) and the second reactive compartment (V134), is associated with a respective pair of first conduits (38A, 38B), • the compartment frames (330; 430; 530) associated with each of the two reactive compartments (V132, V134) of this unit cell each comprise a transfer frame (330) with two passages (332) each, the external mouth (335) of each passage being provided on an external edge (215) of the corresponding transfer frame, • the two passages (332) of the same transfer frame each open into a separate conduit among the two circulation conduits of the associated pair of conduits. Fuel cell (20) according to the preceding claim, in which: for each unit cell (100), the first separator (110) is configured to separate in a sealed manner the first reactive compartment (V132) from a first cooling compartment (V136), which is configured to receive a third operating fluid of the fuel cell, the fuel cell houses, in addition to the first two pairs of circulation conduits (38A, 38B), a third pair of circulation conduits (38C), the circulation conduits (38C) of the third pair being associated with the third operating fluid, for each unit cell: • each of the three compartments (V100) chosen from the first reactive compartment (V132), the second reactive compartment (V134) and the first cooling compartment (V136), is associated with a respective pair from among the three pairs of conduits (38A, 38B, 38C), • the compartment frames (330; 430; 530) associated with each of the three compartments (V132, V134, V136) of this unit cell each comprise a transfer frame (330) with two passages (332) each, the external mouth (335) of each passage being provided on an external edge (215) of the corresponding transfer frame, • the two passages (332) of the same transfer frame each open into a separate conduit among the two circulation conduits of the associated pair of conduits.

Images