Subassembly for a fuel cell stack, fuel cell comprising such a subassembly, and method for manufacturing such a subassembly

Abstract

This subassembly for a fuel cell stack comprises at least one first bipolar half plate (42); a membrane; and a membrane-electrode assembly comprising a two-part frame (30) formed by a first half frame (32) and a second half frame (34). At least the second half frame (34) is coated with a fixing adhesive layer on a first surface (S34) facing the first surface (S32) of the first half frame. First openings (320) disposed through the first half frame (32) are respectively disposed facing the solid portion (42A) of the first bipolar half plate and the solid portion (34A) of the second half frame in a direction perpendicular to the main plane (π22) of the membrane. The first bipolar half plate (42) extends through the first opening (320) and is secured to the frame (30) by a quantity of adhesive (Q2) derived from adhesive coated on the first surface (S34) of the second half frame (34).

Description

[Technical Field]

[0001] The present invention relates to a subassembly intended to be incorporated into a stack of electrochemical cells in a fuel cell. The present invention also relates to a fuel cell comprising a stack of electrochemical cells, at least one of which comprises or is constituted by such a subassembly. Finally, the present invention relates to a method for manufacturing such a subassembly. [Background technology]

[0002] In the field of fuel cells, it is known to insert a stack of electrochemical cells between two terminal plates located on either side of the stack in the stacking direction, and to place the stack in a casing if necessary. The electrochemical cell is formed by a membrane-electrode assembly and a bipolar plate. The membrane-electrode assembly, sometimes called MEA from the English "Membrane-Electrode Assembly," generally comprises a base membrane, which may be coated on one or both sides with a catalyst-containing catalyst layer, and a frame supporting the membrane. The frame may include openings that define fluid flow galleries within the stack of electrochemical cells for the distribution and recovery of these fluids in the corresponding fluid compartments of each cell within the stack. The frame is usually associated with at least one seal, sometimes called a "gasket," that also ensures a sealing function for the flow of fluids within the stack.

[0003] When the membrane is coated with a layer containing a catalyst, it is sometimes called a CCM, which stands for "Catalyst Coated Membrane." In this case, the membrane contains three layers: the membrane body, an anode-side catalyst layer, and a cathode-side catalyst layer.

[0004] In a stack, a membrane-electrode assembly is sandwiched between two bipolar plates, thereby defining an anode compartment and a cathode compartment. On each side, the catalyst-coated membrane is covered by a gas diffusion layer, which is received in the corresponding anode or cathode compartment and promotes contact between the membrane and the chemical species present in the corresponding anode or cathode compartment. Each gas diffusion layer also serves to conduct electrons. These diffusion layers are sometimes referred to as GDLs, from the English "gas diffusion layer."

[0005] It is known to manufacture membrane-electrode assemblies by mounting a catalyst-coated membrane on a frame, which makes it possible in particular to reinforce the membrane and facilitate its handling. This is done by leak-tight bonding of the membrane to the frame.

[0006] During the manufacture of fuel cells, it is known to produce bipolar plates formed from two half plates or metal foils belonging to two adjacent electrochemical cells. This requires separate handling of the membrane-electrode assembly, on the one hand, and the bipolar plate, on the other, during placement in the fuel cell stack. This solution requires joining the two half plates or foils of the bipolar plate together. This joining can be carried out by laser welding or brazing, especially point-by-point, by plastic deformation of the foil, especially using a power tool that produces impacts, or by bonding. However, it is also known to have bipolar plates formed from two half plates or metal foils belonging to two adjacent electrochemical cells, the two half plates only being held in contact with each other by the compression of the stack, generally with one or more intervening seals, which can be free seals or seals integrated into one or the other of the half plates.

[0007] When membrane-electrode assemblies are constructed on one side and bipolar plates on the other, they have to be arranged alternately along the stacking direction, which proves lengthy and delicate to implement in practice.

[0008] From WO 2014 / 111745 and US 8,399,150 it is known to bond an electrochemical cell frame to a bipolar plate by means of an adhesive layer interposed between these components. This approach requires bonding the foils of the bipolar plate according to one of the above-mentioned techniques and providing a quantity of adhesive dedicated to creating the bond between the frame and the bipolar plate. This approach imposes a subsequent method of constructing the stack of electrochemical cells of the fuel cell, increasing its costs both in terms of investment in the means for applying the adhesive and the cost of this added adhesive.

[0009] JP 2008084707 A further technique is known, which distributes adhesive points between two half frames of a frame surrounding an electrochemical cell membrane and drills holes in these half frames aligned perpendicular to the membrane plane. Half bipolar plates are attached to each half frame by other adhesive points. This assembly technique using adhesive points requires a relatively large amount of glue. Each half bipolar plate is directly bonded only to the adjacent half frame. In addition, the glue placed between the two half frames can overflow on one side of the resulting subassembly. Summary of the Invention [Problem to be solved by the invention]

[0010] It is these drawbacks that the present invention aims in particular to improve by proposing a new subassembly for a fuel cell stack, the manufacture of which is simplified and the cost of which can be reduced compared to previous equipment. [Means for solving the problem]

[0011] To this end, the present invention relates to a subassembly for a fuel cell stack, comprising a membrane-electrode assembly comprising a membrane and a two-part frame formed by a first half-frame arranged on a first side of the membrane and a second half-frame arranged on a second side of the membrane, the membrane-electrode assembly further comprising at least one first half bipolar plate, the at least second half-frame being coated on a first surface facing the first surface of the first half-frame with a layer of glue for bonding the half-frames together.

[0012] According to the invention, the first openings disposed through the first half frame are each disposed facing the solid portion of the first half bipolar plate and facing the solid portion of the second half frame in a direction perpendicular to the main plane of the membrane, and the first half bipolar plate is coupled to the frame by a quantity of glue extending through the first openings and resulting from glue coated on the first surface of the second half frame.

[0013] The structure of the subassembly according to the present invention allows the use of a glue layer, primarily intended to bond the two frames of the membrane-electrode assembly, and also ensures the additional function of immobilizing the first half bipolar plate. This allows the subassembly to be handled as a unit during the manufacture of fuel cells incorporating the glue layer, which facilitates operator or robot work and increases production speed, thereby reducing fuel cell costs. Additionally, the bonding between the first half bipolar plate and the frame is precise because the amount of glue extending through the first openings is well positioned in space due to these first openings. In particular, there is no risk of this amount of glue flowing outside the subassembly of the present invention. Additionally, when the subassembly includes a second half bipolar plate, the subassembly constitutes an integrated electrochemical cell that can be tested or pre-activated before being incorporated into a stack of cells, making the manufacturing process of such cells more reliable.

[0014] According to advantageous but non-essential aspects of the invention, such a subassembly may incorporate one or more of the following features taken in any technically permissible combination:

[0015] The subassembly includes a second half bipolar plate disposed opposite the first bipolar plate relative to the membrane. The first half frame is coated on a first surface with a layer of glue for bonding the half frames. Second openings are disposed through the second half frame, facing the solid portions of the second half bipolar plate and the first half frame, respectively, in a direction perpendicular to the main plane of the membrane. Additionally, the second bipolar plate extends through the second openings and is bonded to the frame by a quantity of glue derived from the glue coated on the first surface of the first half frame.

[0016] The first and second openings are offset from one another in at least one direction parallel to the major plane of the membrane, such that there is no overlap between the openings in a direction perpendicular to the major plane of the membrane.

[0017] In a direction perpendicular to the main plane of the membrane, the first half bipolar plate is provided with a notch aligned with the second opening and / or the second half bipolar plate is provided with a notch aligned with the first opening.

[0018] The notches open onto at least one longitudinal edge of the bipolar plate in which said notches are formed.

[0019] Each opening disposed through the half frame preferably has a circular, rectangular, or oblong shape, 5 mm 2 More than 10mm, preferably 2 It has a cross section with an area of ​​at least 100 mm.

[0020] The glue is heat activated and is based on a thermoplastic polymer, in particular an EVA copolymer.

[0021] At least one of the first openings disposed through the first half-frame is located within a perimeter region of the subassembly that is outwardly positioned relative to a peripheral sealing gasket of the subassembly.

[0022] The membrane-electrode assembly includes four corners, while the subassembly includes at least four first openings disposed through a first half frame, each at a corner of the membrane-electrode assembly, and disposed within an outer peripheral region of the subassembly located outwardly relative to a peripheral sealing gasket of the subassembly.

[0023] At least one of the first openings arranged through the first half frame and the solid portion of the first half bipolar plate facing said half frame is located in the gallery framing area, is arranged around the opening of said first half bipolar plate and is fluidly isolated from at least one anode or cathode fluid compartment defined in the subassembly between the membrane-electrode assembly and said first half bipolar plate.

[0024] According to another aspect, the present invention relates to a fuel cell comprising a stack of electrochemical cells each having a membrane-electrode assembly and two half bipolar plates, at least one of these cells comprising or consisting of a subassembly as described above.

[0025] This fuel cell exhibits the same advantages as those mentioned above.

[0026] According to a third aspect, the present invention relates to a method for manufacturing a subassembly, in particular a subassembly as described above, comprising a membrane-electrode assembly, the subassembly comprising a membrane and a two-part frame formed by a first half frame arranged on a first side of the membrane and a second half frame arranged on a second side of the membrane, the membrane-electrode assembly also comprising at least a first half bipolar plate, the method comprising at least a preliminary step of coating at least a first surface of the second half frame with glue, and a step of bonding the frame and the membrane by applying the first surface of the second half frame coated with glue against the first surface of the first half frame.

[0027] According to the invention, the method comprises at least the steps of applying a first half bipolar plate to a second surface of the first half frame opposite to the first surface of the first half frame, and joining the first half bipolar plate and frame by moving glue coated on the first surface of the second half frame between its first and second surfaces towards the surface of the first half bipolar plate through a first opening arranged in the first half frame.

[0028] This method allows for the formation of electrochemical cells or portions of electrochemical cells that can be easily incorporated into stacks of fuel cells at high production rates using well-learned techniques.

[0029] Advantageously, the subassembly comprises a second half bipolar plate, and the method comprises at least the preliminary step of coating at least a first surface of a first half frame with glue, a step of applying a second half bipolar plate to a second surface of said second half frame opposite to the first surface of said second half frame, and a step of joining said second half bipolar plate and frame by moving the glue coated on the first surface of the first half frame towards the surface of said second half bipolar plate, through a first opening arranged in said second half frame, between its first and second surfaces.

[0030] During the bonding step, the glue coated on the first surface of the second half frame, and optionally on the first surface of the first half frame, can be heated at least in the vicinity of the first opening, and optionally at the level of the second opening.

[0031] The present invention will be better understood and other advantages will become more apparent in the light of the following description of four embodiments of a subassembly, a fuel cell, and a method in accordance with its principles, given by way of example only, and with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0032] [Figure 1] FIG. 1 is a partially exploded perspective view of a subassembly according to a first embodiment of the invention, the subassembly constituting an electrochemical cell belonging to a stack of fuel cells. [Figure 2] FIG. 2 is an exploded perspective view of a membrane-electrode assembly belonging to the subassembly shown in FIG. [Figure 3] FIG. 3 is a front view of the subassembly shown in FIG. [Figure 4] FIG. 4 is a longitudinal cross-sectional view of the subassembly shown in FIGS. 1 and 3, taken along line IV-IV in FIG. 3, during a process for manufacturing a fuel cell comprising this subassembly. [Figure 5] FIG. 5 is a partial view similar to FIG. 4 of a subassembly according to a second embodiment of the invention. [Figure 6] FIG. 6 is a simplified front view similar to FIG. 3 of a subassembly according to a third embodiment of the present invention. [Figure 7] FIG. 7 shows, on a larger scale in the two insets a) and b), a partial cross section at section lines AA and BB in FIG. 6 when the subassembly is incorporated into a stack of electrochemical cells. [Figure 8] FIG. 8 is a simplified front view similar to FIG. 6 of a subassembly according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0033] To clearly illustrate the features of the present invention, proportions are not necessarily considered between objects shown in the figures.

[0034] A membrane-electrode assembly 2 is shown in a partially exploded view in Figure 1. This assembly 2 is associated with a first half bipolar plate 42 and a second half bipolar plate 44 to form a subassembly 6 intended to constitute an electrochemical cell designed to be part of a stack, this stack constituting part of a fuel cell. Such a stack is shown in Figure 7, with the reference numeral 60, within a partially visible fuel cell 8, for a third embodiment of the invention.

[0035] The half bipolar plates 42 and 44 may also be referred to as polar plates.

[0036] A2 denotes the longitudinal axis of the membrane-electrode assembly 2, which coincides with the longitudinal axis A6 of the subassembly 6.

[0037] The membrane-electrode assembly 2, which may be referred to as an MEA, comprises a base membrane 22 that is coated with a catalyst in the example described below. More precisely, the base membrane 22 is a proton exchange polymer membrane. The structure of the membrane-electrode assembly 2 is the same as that shown in FIG. 7 for the third embodiment. The membrane-electrode assembly will be described with reference to this FIG. 7. Accordingly, in this example, the base membrane 22 is coated on a first side, oriented upward in FIGS. 1, 2, and 7, with a first catalyst layer 23 that forms the cathode, and on a second side opposite the first side, oriented downward in FIGS. 1, 2, and 7, with a second catalyst layer 24 that forms the anode. The membrane 22 and the catalyst layers 23 and 24 together form a catalyst-coated membrane 25, otherwise referred to as a CCM. In the remainder of this specification, this catalyst-coated membrane 25 will be referred to as a membrane CCM.

[0038] Here, the base membrane 22 is made of a polymer material, particularly of the Nafion type (registered trademark), and has a thickness of about 0.005 mm to 0.050 mm, preferably 0.008 mm to 0.015 mm. The catalyst layers 23 and 24 are made of platinum and each have a thickness of about 0.001 mm to 0.010 mm, preferably 0.002 mm to 0.005 mm. The thickness of the CCM membrane 25 is preferably 0.008 mm to 0.050 mm, preferably about 0.017 mm.

[0039] π22 denotes the mid-plane of the base membrane 22, which is also the mid-plane of the CCM membrane 25. The longitudinal axis A2 is contained in the mid-plane π22.

[0040] The CCM membrane 25 is mounted in a frame 30 consisting of two half frames 32 and 34 intended to be in planar contact with each other and made, for example, of a polymer film, for example, poly(ethylene terephthalate) i.e. PET or poly(ethylene naphthalate) i.e. PEN.

[0041] π30 denotes the contact plane of the two half frames 32, 34 relative to one another. Plane π30 is also the mid-plane of frame 30, which contains longitudinal axis A2. The two half frames 32, 34 are configured to capture the peripheral edge 22a of membrane 22 between them when they are in contact with one another along plane π30. In this configuration, half frames 32, 34 form an area, also called an "overlap," between membrane 22 and the two half frames 32, 34. Along each longitudinal edge or each lateral edge of the frames, this overlap has a width, for example, comprised within the range of 1 mm to 5 mm, preferably within the range of 2 mm to 4 mm.

[0042] Half frame 32 is disposed on a first side of CCM membrane 25 in the example above the membrane in Figures 1, 2 and 7, and half frame 34 is disposed on a second side of CCM membrane 25 in the example below the membrane in Figures 1, 2 and 7. This has the effect of immobilizing membrane 22, and indeed CCM membrane 25, by sandwiching said membrane between half frames 32 and 34 within frame 30.

[0043] Advantageously, the thickness of each of the half frames 32 and 34 is between 0.020 mm and 0.030 mm, preferably about 0.025 mm.

[0044] The frame 30 allows the CCM membrane 25 to be reinforced and held in place within the stack.

[0045] In practice, the half frames 32 and 34 are joined to each other at the contact surface π 30, preferably by glue.

[0046] Preferably, as can be seen in FIG. 4, for example, the glue does not deform and remains parallel to the plane π30.

[0047] S32 denotes the surface of half frame 32 facing half frame 34. S34 denotes the surface of half frame 34 facing half frame 32. In the mounting configuration of frame 30 around membrane 22, surfaces S32 and S34 are in surface contact with each other, aligned on plane π30 and bonded to each other by glue.

[0048] In this configuration, the central plane π22 of the membrane 22 is also aligned on the plane π30.

[0049] The glue used to assemble the half frames 32 and 34 is preferably a heat-activatable glue based on a thermoplastic polymer, for example a glue based on an EVA copolymer, such as the glue sold under the reference AP12 by the company Micel.

[0050] Advantageously, the thickness of the glue layer coated, i.e. deposited, on each surface S32 or S34 of the half-frames is between 0.01 mm and 0.02 mm, preferably about 0.013 mm, before applying the surfaces S32 and S34 to each other.

[0051] Advantageously, the frame 30 defines openings 36 intended to form fluid circulation and distribution / collection galleries within the stack when several subassemblies 6 are juxtaposed in the stack in a direction perpendicular to their central plane π30.

[0052] The opening 36 is formed by aligning individual openings 362 and 364 formed in the half-frames 32 and 34, respectively, in a direction parallel to the axis A30.

[0053] Alternatively, particularly in the case of so-called "external manifold" fuel cells, frame 30 does not have openings of the type of opening 36.

[0054] A30 denotes an axis that is perpendicular to the plane π30 and passes through the geometric center of the frame 30. The axis A30 is perpendicular to the base membrane 22 as well as to the CCM membrane 25, and thereby perpendicular to its mid-plane π22.

[0055] Within the stack, the axes A30 of the different frames 30 coincide and the frames 30 are oriented around this axis so that the openings 36 together constitute circulation and distribution / collection galleries for fluids, in particular hydrogen, air or heat transfer fluids, within the stack.

[0056] Each half bipolar plate 42 or 44 is provided with openings 46 of the same geometric shape as openings 36, which also participate in the definition of these galleries.

[0057] Reference numerals 32A and 32B respectively indicate longitudinal ends of the half frame 32. Reference numerals 34A and 34B respectively indicate longitudinal ends of the half frame 34.

[0058] A32 and A34 indicate the longitudinal axes of the half frames 32 and 34, respectively. In the mounted configuration of the membrane-electrode assembly 2, axes A2, A32, and A34 are perpendicular to axis A30, parallel to each other, and preferably approximately coincident with the thickness of the half frames. B32 and B34 indicate the transverse axes of the half frames 32 and 34, respectively, which are perpendicular to axes A32 and A34, respectively. In the mounted configuration of the membrane-electrode assembly 2, axes B32 and B34 are perpendicular to axis A30, parallel to each other, and preferably approximately coincident with the thickness of the half frames.

[0059] Half frames 32 and 34 each define a central opening 32C and 34C, respectively, that passes through the half frames from end to end before CCM membrane 25 is disposed in its mounting configuration on frame 30. Central openings 32C and 34C of half frames 32 and 34 are thereby defined by the inner edges of these half frames. Central openings 32C and 34C in combination define central opening 30C in frame 30 that is closed by the CCM membrane in its mounting configuration with membrane-electrode assembly 2. Half frames 32 and 34, and therefore frame 30 that they constitute, have closed contours around the corresponding central openings.

[0060] Reference numeral 32D denotes the lateral edges of the central opening 32C of the half frame 32, each of which is parallel to the axis B32. Reference numeral 34D denotes the lateral edges of the central opening 34C of the half frame 34, each of which is parallel to the axis B32.

[0061] Advantageously, the membrane-electrode assembly 2, which may also be called GDL, comprises a first gas diffusion layer 28 and a second gas diffusion layer 29 whose function is to facilitate the exchange between the CCM membrane 25 and the fluid circulating between the two half bipolar plates 42 and 44 of the subassembly 6 to which this membrane-electrode assembly belongs.

[0062] Advantageously, the thickness of the diffusion layers 28 and 29 is between 0.050 mm and 0.320 mm, preferably about 0.250 mm.

[0063] In the mounted configuration of the membrane-electrode assembly 2, the diffusion layers 28 and 29 each cover a portion of the CCM membrane 25 and frame 30 on one side of the CCM membrane 25, near the central opening 30C.

[0064] To allow immobilization of the half bipolar plates 42 and 44 on the frame 30 with the CCM membrane 25, each half frame 32 and 34 has a first opening 320 and a second opening 340, respectively, arranged on either side of its central opening 32C or 34C along its longitudinal axis A32 or A34, and on either side of its respective opening 362 or 364 along its transverse axis B32 or B34. In the mounted configuration of the subassembly 6, the first opening 320 is intended to be covered by the half bipolar plate 42, while the second opening 340 is intended to be covered by the half bipolar plate 44. Thus, in the mounted configuration of the subassembly 6, the openings 320 and 340 are arranged facing the half bipolar plates 42 and 44 in a direction parallel to the axis A30, i.e., perpendicular to the planes π22 and π30.

[0065] In this example, the number of openings 320 in half frame 32 is four, as is the number of openings 340 in half frame 34 .

[0066] In variations not represented, a different number of openings 320 and 340 may be provided, or different numbers of openings may be provided on the two half frames.

[0067] The half frame 32 has two rows of two openings 320 extending near the ends 32A and 32B of the half frame 32 on either side of each opening 362, respectively, and connecting the surface S32 of the half frame 32 to the surface S'32 of the half frame 32 opposite the surface S32 and on which the first half bipolar plate 42 and the diffusion layer 28 rest. Thus, the openings 320 penetrate the thickness of the half frame 32.

[0068] Similarly, the half frame 34 has two rows of two openings 340 extending near the ends 34A and 34B of the half frame 34 on either side of each opening 364, respectively, and connecting the surface S34 of the half frame 34 to the surface S'34 of the half frame 34 opposite the surface S34 and on which the second half bipolar plate 42 and the diffusion layer 28 rest, so that the openings 340 penetrate the thickness of the half frame 34.

[0069] Advantageously, the openings 320 are distributed on the first half frame 32 symmetrically with respect to the axes A 32 and B 32. Similarly, the openings 340 are distributed on the first half frame 34 symmetrically with respect to the axes A 34 and B 34.

[0070] Advantageously, opening 320 is farther from lateral edge 32D than opening 340 is from lateral edge 34D, such that openings 320 and 340 are offset from one another in a direction parallel to longitudinal axes A32 and A34, such that there is no overlap between these openings in the direction of axis A30.

[0071] d32 denotes the distance measured parallel to axis A32 between axis B32 and a line passing through the geometric center of opening 320. d34 denotes the distance measured parallel to axis A34 between axis B34 and a line passing through the geometric center of opening 340. Distances d32 and d34 are different. In this example, distance d32 is greater than distance d34 by a non-zero difference Δ24, which induces an offset between openings 320 and 340 parallel to longitudinal axes A32 and A34, so that there is no overlap between them.

[0072] According to an unrepresented variant of the invention, in addition to or instead of being offset in a direction parallel to the longitudinal axes A32 and A34, the openings 320 and 340 are offset from each other in a direction parallel to the transverse axes B32 and B34, which also avoids overlap between these openings in a direction parallel to the axis A30.

[0073] S42 denotes the surface of the first half bipolar plate 42 that faces the frame 30 in the assembled configuration of the subassembly 6. S44 denotes the surface of the second half bipolar plate 44 that faces the frame 30 in the assembled configuration of the subassembly 6.

[0074] In the assembled configuration of the subassembly 6, each opening 320 extends through the half frame 32 between surfaces S34 and S42, while each opening 340 extends through the half frame 34 between surfaces S32 and S44.

[0075] Near two of its opposite corners, the first half bipolar plate 42 has two notches 48 that open on two opposite longitudinal edges of the half plate, face each other relative to the axes A32 and B32, and allow access from above, in FIG. 1, to two areas Z2 of the first half frame 32 that, when the subassembly 6 is installed, cover the opening 340 in the second half frame 34 from above. Similarly, the second half bipolar plate 44 has two notches 49 that open on two longitudinal edges and two opposite lateral edges of the half plate, face each other relative to the axes A34 and B34, and allow access from below, in FIG. 1, to two areas Z4 of the second half frame 34 that, when the subassembly 6 is installed, cover the opening 320 in the first half frame 32 from below.

[0076] A system of peripheral sealing gaskets 50 is arranged on each side of the frame, between the frame 30 and the half bipolar plates 42 and 44. In fact, two peripheral sealing gaskets 50 are provided, one on the surface S'32 and the other on the surface S'34. These sealing gaskets 50 surround both the central opening 30C and the opening 36 of the frame, thereby ensuring a seal for each of the working fluids of the cell, i.e., hydrogen, oxygen, air, and any cooling fluid, against the outside of the subassembly 6. These peripheral sealing gaskets 50 thus fluidically isolate the cathode compartment from the outside and the anode compartment from the outside.

[0077] Each of the openings 36, 46 is also surrounded by an opening-sealing gasket system 51 that allows fluid communication of a given fluid compartment, i.e., only with one of the anode compartment, the cathode compartment, and possibly the cooling compartment between two adjacent cells, with the openings 36, 46 allowing fluid in and out of this compartment only. In practice, two opening-sealing gaskets 51 are provided, one on the surface S'32 and the other on the surface S'34.

[0078] 3, the gaskets 50 and 51 are shown in dotted lines as seen through the half bipolar plate 42. The gasket 50 is positioned within the interior region Z of the subassembly 6. int , where the CCM membrane 25, the gas diffusion layers 28 and 29, and the gallery portion formed by the openings 36 and 46 are located. ext is defined around the gaskets 50 between these gaskets and the outer edge of the subassembly. The gaskets 50 surround the different gaskets 51 that connect to them. In other words, the gaskets 51 define an inner area Z int Located inside.

[0079] Outer peripheral area Z of frame 30 ext30 is the outer peripheral region Z of the subassembly 6 in this cell mounting configuration. ext This defines the outer region Z ext30 surrounds the gasket 50 in each of the half frames 32 and 34 .

[0080] In order not to break the seal ensured by the gasket 50, the first opening 320 and the second opening 340 are preferably located within the outer peripheral region Z of the frame 30, as seen in FIGS. ext30 , thereby forming a periphery region Z of the subassembly 6. ext will be placed in.

[0081] A method for manufacturing the subassembly 6 as described above will now be described.

[0082] During the first preliminary step, surfaces S32 and S34 are coated with glue. This preliminary step can be carried out at the production site of the membrane-electrode assembly 2, immediately before or before the following steps. Alternatively, this preliminary step can be carried out at a remote location, from which the glue-coated half frames are transported to the production site of the membrane-electrode assembly. This allows the operation of coating surfaces S32 and S34 with glue to be carried out by a manufacturer different from the manufacturer that produces the membrane-electrode assembly. In such a case, a protective film can be provided on the glue layer for transportation, which is then removed before the second step described below.

[0083] During the second step, the two half frames 32 and 34 are placed in contact with their surfaces S32 and S34 along the plane π30, while the membrane 22 is disposed between them, which has the effect of sandwiching the edge 22a of the membrane 22 and bonding the frame 30 and the membrane 22, i.e., the frame 30 and the CCM membrane 25. The frame 30 is constituted by the adhesion of the surfaces S32 and S34 by means of a glue coated thereon.

[0084] Advantageously, during the second step, the assembly of the two half frames 32 and 34 by capturing the edges of the membrane 25 is carried out by applying ultrasound to activate the glue. Typically, the assembly of the two half frames 32 and 34 capturing the membrane 25 is performed by clamping them between a sonotrode and anvil, and ultrasound transmitted by this sonotrode to the two half frames 32 and 34 ensures the activation of the glue, thereby joining the two half frames 32 and 34 to each other and to the membrane in the overlap region. Conventionally, the application of ultrasound can be carried out in particular by means of a grooved sonotrode, such as those known, for example, from US Pat. No. 10,981,245 or US Patent Application Publication No. 2013 / 213552. Typically, as shown in U.S. Patent Application Publication No. 2013 / 213552, the grooves can be formed from two or three networks of grooves formed in the surface of the sonotrode, each network containing parallel grooves in a direction specific to each network. The grooves of the network thus together define protruding studs that are the preferred contact areas with the frame during ultrasonic application. Note that the use of a grooved sonotrode can create a texturing on at least the surface of the half frame with which the sonotrode is in contact, a texture that is essentially the inverse image of the sonotrode's grooves. This texturing can have a depth shallower than the depth of the sonotrode's grooves. The sonotrode can be grooved across the entire surface of the sonotrode that is in contact with the two half frames 32 and 34, or across only a portion of the sonotrode's surface. Preferably, the entire surface of the two half frames 32 and 34 is assembled ultrasonically. In other words, the joining region of the two half frames, which corresponds to the area where the ultrasonic waves are applied, corresponds to the entire area of ​​the frame 30. In some embodiments, the entire joining region of the two half frames, which corresponds to the area where the ultrasonic waves are applied, has a texturing of the surface of the half frames that is substantially the inverse image of the sonotrode grooves.In other embodiments, only one or more portions of the joining area of ​​the two half frames corresponding to the area where ultrasound is applied have such texturing, while the remaining portions of the joining area result from glue activation by a smooth sonotrode or smooth portions of the sonotrode. In the overlap area of ​​the frame 30 with the membrane 25, ultrasound causes each of the two half frames 32 and 34 to join on the corresponding surfaces of the membrane. Preferably, the sonotrode is prevented from contacting the membrane 25 inside the windows defined on the inside of each half frame to avoid heating and compressing the membrane 25 in its active area, which would be exposed to the reactants. The sonotrode used may be in the form of a frame, potentially allowing complete assembly of the frame 30 on the membrane 25 in a single motion. Alternatively, a sonotrode can be prepared to cover only a portion of the desired joining area, and then complete assembly of the frame 30 on the membrane 25 can be performed in several successive motions. Alternatively, several sonotrodes can be prepared for use, each covering only a portion of the joining area, and the complete assembly of the frame 30 on the membrane 25 can then be carried out simultaneously for all sonotrodes in a single operation, or in several successive operations with one or more sonotrodes used in each operation.

[0085] During a third step, the diffusion layers 28 and 29 are deposited on the frame 30 and then assembled onto the frame 30 by any suitable technique, for example by bonding.

[0086] During a fourth step, the two half bipolar plates 42 and 44 are attached to either side of the frame 30 comprising the CCM membrane 25 and the GDL layers 28 and 29, more precisely to the outer surfaces S'32 and S'34 of the half frames 32 and 34. The position and dimensions of the notches 48 and 49 are selected so that at the end of the fourth step, the half bipolar plate 42 covers the opening 320 and the notch 48 is aligned with the opening 340 parallel to the axis A30, while the half bipolar plate 44 covers the opening 340 and the notch 49 is aligned with the opening 320 parallel to the axis A30. Thus, in the direction parallel to the axis A30, each opening 320 is disposed facing the notch 49 between the solid portion 42A of the half bipolar plate 42 and the solid portion 34A or 34B of the half frame 34, and each opening 340 is disposed facing the notch 48 between the solid portion 44A of the half bipolar plate 44 and the solid portion 32A or 32B of the half frame 32. The solid portions 32A and 34A of the half frames 32 and 34 are defined at their longitudinal ends 32A and 34A in this embodiment. The solid portion 32A of the half frame 32 is defined by an area free of openings 36 and openings 320, and the solid portion 34A of the half frame 34 is defined by an area free of openings 36 and openings 340, respectively. In these solid portions 32A and 34A, the surfaces S32 and S34 are uninterrupted. The solid portions 42A of the half bipolar plate 42 and the solid portions 44A of the half bipolar plate 44 are each defined by areas that are free of openings 46 or other openings or cutouts. In these solid portions 42A and 44A, the surfaces S42 and S44 are uninterrupted.

[0087] The geometry of the GDLs 28 is such that said geometry does not intervene between a first opening 320 and a solid portion 42A of the half bipolar plate 42 facing said opening 320, but allows direct contact, via a given first opening 320, between the solid portion 34A of the half frame 34 corresponding to this given first opening 320 and the solid portion 42A of the half bipolar plate 44 corresponding to this given first opening 320. Similarly, the geometry of the GDLs 29 is such that said geometry does not intervene between a second opening 340 and a solid portion 44A of the half bipolar plate 44 facing said opening 340, but allows direct contact, via a given second opening 340, between the solid portion 32A of the half frame 32 corresponding to this given second opening 340 and the solid portion 44A of the half bipolar plate 42 corresponding to this given second opening 340. In both cases, such relative positioning can be achieved by the geometry of the external contours of the GDLs 28, 29, as in the example shown, or by the presence of openings in the GDLs 28, 29. A solid part of a half frame or half bipolar plate corresponds to the first or second opening when said solid part is aligned with this opening in a direction parallel to the axis A30, in other words facing this opening.

[0088] This results in the formation of a nine-layer structure: three layers 22, 23, and 24 of CCM membrane 25, two half frames 32 and 34, two GDLs 28 and 29, and two half bipolar plates 42 and 44. This multi-layer structure is intended to form subassembly 6 at the end of the method of the present invention.

[0089] The fifth step of joining the first and second half bipolar plates 42, 44 to the frame 30 is performed by activating the glue present on the surfaces S32 and S34, at least over the area of ​​the solid portion 34A of the half frame 34 facing the first opening 320 and over the area of ​​the solid portion 32A of the half frame 32 facing the second opening 340, for example by heating. This activation can optionally be completed by a pressing operation to ensure contact of the thereby activated glue with the corresponding solid portions 44A, 42A of the half bipolar plates 44, 42 through the first and second openings 320, 340. The optional pressing can be performed at least partially simultaneously with the activation. Pressing can follow activation or can begin before or during activation and continue beyond activation. Thereby, through a given first opening 320, the solid portion 34A of the half frame 34 facing this given first opening 320 is bonded to the corresponding solid portion 42A of the half bipolar plate 42 also facing this given first opening 320, in particular by glue initially carried by the solid portion 34A of the half frame 34. It can be considered that at least a part of the glue initially carried by the half frame 34 moves through the given first opening 320 and reaches the surface S42 of the half polar plate 42. Similarly, through a given second opening 340, the solid portion 32A of the half frame 32 facing this given second opening 340 is bonded to the corresponding solid portion 44A of the half bipolar plate 44 facing this given second opening 340, in particular by glue initially carried by the solid portion 32A of the half frame 32. It can be considered that at least a portion of the glue initially carried by the half-frames 32 thereby migrates through the given second openings 340 and reaches the surface S44 of the half-polar plate 44.

[0090] Furthermore, activation of the glue, particularly in the case of a thermoplastic glue activated by heat, may have the effect of fluidizing the glue and allowing some of the glue, particularly some of the glue located near and around a given first opening 320 and / or second opening 340, to then migrate to the openings 320 and 340 in the direction of surfaces S44 and S42, respectively.

[0091] In particular, heating of the glue present on surface S34 may also have the effect of causing part of the glue present between half frames 32 and 34 to flow into opening 320. Likewise, heating of the glue present on surface S32 may also have the effect of causing part of the glue present between half frames 32 and 34 to flow into opening 340. This allows the glue previously coated on surfaces S32 and S34 during the fifth step to flow between these surfaces and move into the nearest hollow volume defined by openings 320 and 340. From there, the glue flows within these openings towards the edges of these openings adjacent to surfaces S42 and S44 of half bipolar plates 42 and 44, where said glue reaches at the end of the fifth step.

[0092] The above envisages such movement of glue "near and around" the first and / or second openings, meaning that the glue covers these openings and is activated, in particular by heat, over an area strictly larger than that of these openings.

[0093] During the fifth step, the first half bipolar plate 42 is bonded to the frame 30 by glue present in the openings 320, while the second half bipolar plate 44 is bonded to the frame 30 by glue present in the openings 340.

[0094] The fifth step is advantageously carried out by applying a local heat source 82 on the half frames 34 aligned with each opening 320 in a direction parallel to the axis A30, and by applying a local heat source 84 on the half frames 32 aligned with each opening 340 in a direction parallel to the axis A30, as shown in Figure 4. The application of the heat source 82 or 84 makes it possible to increase the local temperature of the glue, ensuring its activation and possibly promoting glue flow into the openings 320 and 340.

[0095] The heat source is advantageously a heating rod that can be manually operated by an operator or by a robot and includes a heating resistor. The heating rod may in particular be of the type of manual soldering iron stylus. The heating rod may also be an impulse-operated system.

[0096] If desired, a mechanical force, i.e., pressure of a heat source in the direction of the frame, can be applied together with the supply of heat to ensure activation of the glue and assembly of the frame 30 with the half bipolar plate 42.

[0097] Here, the heating rod 82 is inserted into the notch 49 in a direction parallel to the axis A30, and / or the heating rod 84 is inserted into the notch 48 in a direction parallel to the axis A30, bringing the heat as close as possible to the glue coated on the surface S34 or S32 by applying it directly to the area Z4 or Z2 of the half frame 34 or 32 accessible through the notch in question.

[0098] Alternatively, only one of the half bipolar plates 42 or 44 has a notch.

[0099] The fact that the notches 48 and 49 open onto at least one longitudinal edge of the half bipolar plates 42 and 44 respectively facilitates contact between the heating rods 82 or 84 and the half frames 32 or 34 .

[0100] Alternatively, during the fifth step, the heating of the glue is carried out by radiation, by convection, in particular by blown hot air, by applying ultrasound or ultraviolet light. The choice of heating mode, and thereby the heat source used, depends on the type of glue used and the geometry of the half bipolar plates and the frame.

[0101] In addition, as already mentioned above, it is advantageous to carry out a step of pressing the multilayer structure in a direction parallel to the axis A30 and of vibrating the glue present in the multilayer structure. This pressing and this vibration can facilitate the migration of the glue in the openings 320 and 340 from the surfaces S34 and S32 towards the surfaces S42 and S44, respectively, and / or the contact of this glue with the surfaces S42 and S44 through the openings 320 and 340. The pressing can be localized, for example concentrated in the area of ​​the first and second openings, or it can extend over a larger area of ​​the multilayer structure, possibly over the entire surface of the multilayer structure or over all the parts of the surface of the multilayer structure that lie outside the periphery of the GDLs 28 and 29.

[0102] Following the fifth step, an amount Q2 of glue initially located on surface S34 is present in each opening 320, whereby the glue connects surface S42 to the portion of surface S34 facing this opening 320 and possibly to the edge of this opening adjacent to surface S34, i.e., to the solid portion 34A of the half-frame 32 facing the opening 320. In addition, an amount Q4 of glue initially located on surface S32 is present in each opening 340, whereby the glue connects surface S44 to the portion of surface S32 facing this opening 340 and possibly to the edge of this opening adjacent to surface S32, i.e., to the solid portion 32A of the half-frame 32 facing the opening 340. In other words, glue amount Q2 generally comes mainly from the glue initially coated on surface S34, while glue amount Q4 generally comes mainly from the glue initially coated on surface S32. In this regard, the fact that there is no overlap between openings 320 and 340 ensures that the solid portion of the glue-coated half frame is exposed facing the solid portion of the opposing half bipolar plate through each opening 320 or 340. The amounts Q2 and Q4 of glue extending into openings 320 and 340, respectively, thereby ensure that either the first half bipolar plate 42 or the second bipolar plate 44 will bond onto the frame 30 without a direct connection between these two half bipolar plates 42, 44 via the frame 30.

[0103] The glue constituting quantity Q2 can be formed only by the amount of glue present in the portion of surface S34 facing opening 320, while the glue constituting quantity Q4 can be formed only by the amount of glue present in the portion of surface S32 facing opening 340.

[0104] Alternatively, as explained above, the glue constituting quantity Q2 can be formed from glue that was on surface S34 both at and around opening 320 before the fifth step, while the glue constituting quantity Q4 is formed from glue that was on surface S32 both at and around opening 340 before the fourth step.

[0105] Preferably, glue volume Q2 extends parallel to plane π30 within first opening 320. In other words, glue volume Q2 is not deformed during the assembly process, so glue volume Q2 is not deformed on the final product and is instead parallel to plane π30.

[0106] In other words, the method of manufacturing the subassembly 6 of the present invention takes advantage of the fact that glue is applied to surfaces S32 and S34 and uses said glue to bond the half frames 32 and 34 to each other around the CCM membrane 25 on the one hand, and to bond the half bipolar plates 42 and 44 onto the frame 30 on the other hand, without using additional glue, welding, or other assembly means.

[0107] The cross section of the openings 320 and 340 is 50 mm 2 Less than 20mm, preferably 2 This avoids weakening the frame 30 while still allowing effective bonding of the half bipolar plates 42 and 44 onto the frame. In addition, the cross section of the openings 320 and 340 can be selected to be 5 mm 2 More than 10mm, preferably 2 This ensures that the adhesive surface in contact with surface S42 or S44 is sufficient to ensure effective immobilization of half bipolar plate 42 or 44.

[0108] For example, openings 320 and 340 can be circular, as shown, with a diameter of 3 mm to 8 mm, preferably about 5 mm. Alternatively, the openings can be any other shape, such as a polygon (triangle, rectangle, pentagon, hexagon, etc.) or oblong oval, with a length in the range of 5 mm to 10 mm, e.g., 7 mm, and a width in the range of 2 mm to 5 mm. Of course, larger opening sizes are possible, particularly to increase adhesive strength, but may affect overall size or positioning relative to the plate.

[0109] At the end of the fifth step of the method of the invention, subassembly 6 constitutes an electrochemical cell and can be handled by a human operator or a robot without the risk of its different layers separating from one another, since the different layers are effectively held to one another by the glue that was coated on surfaces S32 and S3 during the first preliminary step and part of which is located within openings 320 and 340.

[0110] Thus, once several electrochemical cells have been produced in the form of subassemblies 6, it is possible to continue the production of a fuel cell 8 by repeating steps 1 to 5 described above, by juxtaposing different cells to form a stack during subsequent steps, as shown in Figure 7 for the third embodiment. This subsequent step can be carried out easily and quickly by treating each electrochemical cell as a unit.

[0111] The first five steps described above allow for the construction of a cell with all major components, including the CCM membrane 25 and the two half bipolar plates 42 and 44, which can be tested or even pre-activated without the risk of separation or accidental shifting in the context of normal handling. Indeed, creating individual electrochemical cells in this manner provides the opportunity to subsequently test the electrochemical cells with appropriate tooling, tooling that ensures different seals and allows for the supply of reactants and, optionally, cooling fluids. Such test tooling is advantageously capable of, and designed to, measure the efficiency of the cells. Advantageously, the same tooling or a separate tooling allows for at least partial electrochemical break-in, which is typically performed after cell stacking when the cells are assembled. Such activation allows, at least in part, for the electrochemical performance to be brought to or close to the expected initial performance level. Such testing and / or pre-activation operations allow for verification of the operation and performance of pre-assembled cells before incorporating them into a stack.

[0112] In the first embodiment, the sealing of the anode compartment between the membrane-electrode assembly 2 and the anode half bipolar plate and the cathode compartment between the membrane-electrode assembly 2 and the cathode half bipolar plate is ensured not by pre-assembling the membrane-electrode assembly 2 with one and / or the other of the half bipolar plates, as explained above, but by the perimeter sealing gasket 50 and the opening gasket 51. In fact, this pre-assembly due to the glue quantities Q2, Q4 extending through the first opening 320 and / or the second opening 340 and originating from the glue coated on the first surface S34 of the second half frame 34 or the glue coated on the second surface S32 of the first half frame 32 forms a pre-assembly only in a point area. This pre-assembly therefore cannot ensure a fluid-tight seal against the exterior of the relevant compartment.

[0113] In the second to fourth embodiments shown in Figure 5 onwards, elements similar to those in the first embodiment have the same reference numerals. The following will mainly describe what distinguishes these embodiments from the first embodiment. When a reference numeral is mentioned in the remainder of the description without appearing in one of Figures 6 to 8, or when a reference numeral is shown in one of Figures 6 to 8 without being mentioned in the remainder of the description, said reference numeral refers to the same object as the one having the same reference numeral in the first embodiment.

[0114] In the second embodiment, the half bipolar plates 42 and 44 are free of cutouts corresponding to the cutouts 48 and 49 of the first embodiment for at least one opening 320 and / or 340. More specifically, in some variations of this second embodiment, the half bipolar plates 42 and 44 are completely free of cutouts corresponding to the cutouts 48 and 49 of the first embodiment, so that each second opening 340 is disposed between the solid portion 44A of the second half bipolar plate 44 and the solid portion 32A of the half frame 32, which is itself disposed facing the solid portion 42A of the first half bipolar plate 42. In other words, at the second opening, the frame 30 is covered on its two opposite sides by the half bipolar plates 42 and 44. This makes the half bipolar plates easier to manufacture and more interchangeable than in the first embodiment.

[0115] In this second embodiment, heating of the glue is obtained by applying a heat source 84 not directly on the frame 30 as in the first embodiment, but on the portion 44A of the second half-plate 44 that preferably bonds said second half-plate to the frame 30, i.e. in the area facing the opening 340. The amount Q2 of glue transferred from the glue layer previously coated on the surface S32 of the half-frame 32 thus ensures the connection between the frame 30 and the half bipolar plate 44 through the opening 320.

[0116] In a variant not represented, the heat source can be applied to portion 42 A of first half-plate 42 .

[0117] At each opening 320, the situation is symmetrical about the plane π30 relative to that shown in FIG.

[0118] This embodiment is easier to implement than the previous one, at the expense of potentially less effective thermal heating.

[0119] In Figures 6 and 8, areas where it is preferable to place the first opening 320 and the second opening 340 are identified with single-line hatching, and excluded areas where these openings are preferably not placed are identified with cross-hatching.

[0120] 6 and 7, the subassembly 6 includes a system of perimeter sealing gaskets 50 formed using perimeter sealing gaskets that ensure the same functionality as the system of perimeter sealing gaskets 50 of the first embodiment. The system of opening sealing gaskets 51 also has the same functionality as the system of opening sealing gaskets 51 of the first embodiment.

[0121] In the third embodiment of FIGS. 6 and 7, the peripheral gasket 50 together with the opening sealing gasket 51 connected to the peripheral gasket 50 partially ensures the sealing function of the opening.

[0122] Compared to the first embodiment, an additional peripheral gasket 50 is arranged on the surface of the half bipolar plate 42 facing the frame 30, as can be seen in the upper part of the insets a) and b) of Figure 7. According to a variant of the invention not represented, this is also the case at the level of the opening sealing gasket 51.

[0123] As can be seen in Figure 7, a stack 60 of electrochemical cells 6 made into a fuel cell 8 according to the invention comprises several electrochemical cells formed by subassemblies 6 also according to the invention, separated by bipolar plates 4 each consisting of a first half bipolar plate 42 belonging to a cell 6 and a second half bipolar plate 44 belonging to an adjacent cell 6, the frames 30 of these subassemblies being held in a sealed manner against the bipolar plates 4 by peripheral sealing gaskets 50 arranged in particular along the longitudinal edges of the electrochemical cells and by opening gaskets 51 surrounding each of the openings 36, 46 forming fluid flow galleries in the stack of electrochemical cells.

[0124] The peripheral sealing gasket 50 seals the peripheral region Z of the subassembly 6 against the anode compartment, the cathode compartment, and the cooling fluid compartment. ext This defines the inner boundary of the outer peripheral region Z of the subassembly 6. ext is located externally relative to at least one peripheral sealing gasket 50 of the subassembly 6. It is in this peripheral region Z that the first openings 320 disposed through the solid portions 42A of the first half frame 32 and the first half bipolar plate 42 are preferably selected to be located. ext In particular, it is external to the peripheral gasket 50 provided between the frame 30 and the first half bipolar plate 42. It is also within this peripheral region Z that the second openings 340 disposed through the solid portions 44A of the second half frame 34 and the second half bipolar plate 44 are preferably selected to be disposed. ext 3 and 4. The peripheral gasket 50 is external to the peripheral gasket 50 provided between the frame 30 and the second half bipolar plate 42 within the electrochemical cell 6. For each electrochemical cell 6, the peripheral sealing gasket 50 is generally disposed radially inward from the outer edge of the half bipolar plate and the outer edge of the frame of the membrane-electrode assembly, thereby defining this peripheral region Z ext It is indeed possible to use a perimeter sealing gasket 50 to arrange the first openings 320 arranged through the solid parts 42A of the first half frame 32 and the first half bipolar plate 42 and / or the second openings 340 arranged through the solid parts 44A of the second half frame 34 and the second half bipolar plate 44. The contour of the perimeter sealing gasket 50 may be locally turned inwards to reduce the available peripheral surface Z around the first openings 320 and / or the second openings 340. ext Note that it is possible to provide for this so that it can be adapted to increase

[0125] Additionally, on each side of the frame 30, an opening sealing gasket 51, in combination with a corresponding perimeter sealing gasket 50, defines a gallery framing area Z around the openings 36, 46. egAs a result, six gallery framing areas Z are defined in FIG. eg Gallery framing area Z eg Each of the gallery framing regions Z is fluidly isolated from the anode compartment, the cathode compartment, and the cooling fluid compartment. eg Each of the gallery framing areas Z may also accommodate at least some of the first openings 320 disposed through the first half frame 32 facing the solid portion 42A of the first half bipolar plate 42 and / or at least some of the second openings 340 disposed through the second half frame 34 facing the solid portion 44A of the second half bipolar plate 44. However, each gallery framing area Z eg Note that the area is likely to be fluidly connected to the gallery it surrounds.

[0126] Such regions may also be defined in the first and second embodiments, even though said regions are not formally identified in FIGS.

[0127] 6 and 7 show the presence of bonding regions Z2, Z4 corresponding to the locations of the first and second openings 320, 340, respectively, along the longitudinal edges of the subassembly 6 at the height of the active area corresponding to the presence of the CCM film 25. However, these bonding regions Z2, Z4 can be located near the longitudinal ends of the subassembly 6, e.g., longitudinally at the height of the openings 36, 46 in the subassembly 6, as in the example of FIG. 3, or even starting from the center of the subassembly 6 and extending longitudinally beyond the openings 36, 46 in the subassembly 6. Alternatively, as envisioned above, these bonding regions Z2, Z4 can be located near the gallery framing region Z eg It can be located on one side or the other side.

[0128] More precisely, as shown in FIG. 3, it is particularly advantageous to provide at least four first openings 320 and, if applicable, at least four second openings 340, each located at one of the four corners of the membrane-electrode assembly, the corners being located within the circumferential region Zext is defined as a part of the membrane-electrode assembly included in

[0129] longitudinally at the height of the openings 36 of the frame 36 that form the reaction fluid gallery or cooling fluid gallery of the subassembly 6, or starting from the center of the subassembly 6 longitudinally beyond these openings 36, 46,

[0130] - and / or defined laterally at the height of one of the openings 36 of the frame 36 forming the reaction fluid gallery or cooling fluid gallery of the subassembly 6 that is laterally closest to the longitudinal edge under consideration, or starting from the center of the subassembly 6 and laterally beyond this opening 36.

[0131] 7, but also in FIG. 4, it is shown that it is advantageous for the solid portion 42A of the first half bipolar plate 42 facing the first opening 320 of the first half frame 32 and / or the solid portion 44A of the second half bipolar plate 44 facing the second opening 340 of the second half frame 34 to be folded along the axis A30 in a position equal to or close to the position of the midplane π30 of the frame 30 along the axis A30, in order to minimize deformation of the frame along the axis A30 at the location of the connection between the frame 30 and the corresponding half bipolar plate 42. This position may be exactly at the position of the midplane π30 of the frame 30 along the axis A30, or it may be offset from the position of the midplane π30 of the frame 30 by a value less than or equal to the thickness of the frame 30 along the axis A30, and ideally it may be offset from the position of the midplane π30 of the frame 30 by a value equal to the thickness along the axis A30 of the half frames 32, 34 in which the openings 320, 340 are formed.

[0132] 6 and 7, the half bipolar plates 42, 44 have relief passages along the axis A30 corresponding to the bottoms of the reaction fluid circulation channels, the separating teeth between the two channels, and the abutment surfaces for the sealing gaskets 50, 51. These relief passages may be spaced apart from the mid-plane π30 of the frame 30 along the axis A30. However, as in the example of FIG. 4, it can be seen that the first half bipolar plate 42 is formed such that its solid portion 42A facing the first opening 320 is offset along the axis A30 from the mid-plane π30 of the frame 30 by an amount equal to the thickness, along the axis A30, of the half frame 32 in which the first opening 320 is formed.

[0133] Thus, in the case of half bipolar plates formed using stamped metal sheet, the solid portion 42A of the first half bipolar plate 42 facing the first opening 320 of the first half frame 32 can correspond to the stamped shape of the sheet forming the first half bipolar plate 42, and / or the solid portion 44A of the second half bipolar plate 44 facing the second opening 340 of the second half frame 34 can correspond to the stamped shape of the sheet forming the second half bipolar plate 44.

[0134] In the embodiment of Figure 8, the aperture sealing gasket 51 is separate from the peripheral gasket 50, thereby having a closed contour, and as such ensures, for each anode compartment, cathode compartment, or cooling fluid compartment, a sealing function between the associated compartment and at least those of the apertures 36 and 46 that do not communicate with this given compartment. eg , and a portion of the interior area is defined by two gallery framing areas Z, as represented by the cross-hatched area disposed between two opening sealing gaskets 51 in FIG. eg Located in between.

[0135] In this embodiment, the first opening 320 and the second opening 340 are preferably located within the outer peripheral region Z of the subassembly 6. ext will be placed in.

[0136] According to a non-represented variant of the fourth embodiment, some or all of the joining areas Z2, Z4 may be joined to one or more gallery framing areas Z eg It can be set up in.

[0137] According to another unrepresented variant of the invention applicable to all embodiments, only one of the first openings 320 or only some of said openings may be located in the circumferential region Z ext or one or more gallery framing areas Z eg Similarly, only one of the second openings 340, or only some of the openings, is located in the circumferential region Z ext or one or more gallery framing areas Z eg The image forming apparatus can be arranged to be placed in a position indicated by a solid line.

[0138] Whatever the embodiment, in a stack such as stack 60 shown in Figure 7, at least one of the electrochemical cells 6 is according to the invention. Preferably, for homogeneity, all of the electrochemical cells 6 are according to the invention.

[0139] According to a non-represented variant of the invention applicable to all embodiments, the subassembly 6 comprises, on only one side, a first polar half-plate 42, which is joined to a second polar half-plate 44, for example using a joining technique using the first opening 320, before joining the polar half-plate 42 to the frame 30, to form a pre-assembled polar plate 4. In this case, the subassembly 6 is a multi-layer structure that is not symmetrical with respect to the plane π30, since the two joined polar half-plates are located on the sides of the half-frame 32. This subassembly 6 can be handled as a unit by an operator or a robot, so that it can be assembled in one operation into a stack 60 of the type shown in FIG. 7. Each subassembly 6 then forms part of an electrochemical cell, since it must be associated with a second half bipolar plate 44, which is itself part of another pre-assembled bipolar plate 4 of an adjacent subassembly, to form a complete cell. In this case, only the first opening 320 is placed through the first half frame 32 without the need to place a second opening through the second half frame 34, and only the fifth step components shown at the top of Figure 4 or the symmetrical components of the components shown in Figure 6 are implemented, and glue can be coated only on the first surface S34 of the second half frame 34. This embodiment does not allow for testing or pre-activation of the cells before the stack is constructed.

[0140] The invention is shown in the figure when the membrane 25 is of the CCM type and the catalyst layers 23, 24 are supported by the base membrane 22. The invention is also applicable when the catalyst layers 23, 24 are supported by the diffusion layers 28 and 29 according to the CCB ("catalyst coating and calcination") technique, or in the case of mixed assemblies, where one of the catalyst layers 23, 24 is supported by the base membrane 22 and the other of the catalyst layers 23, 24 is supported by the corresponding diffusion layer 28 or 29.

[0141] Alternatively, the subassembly 6 does not include the diffusion layers 28 and 29, which may otherwise be omitted and / or replaced by structures incorporated into the bipolar plate 4.

[0142] Whatever the embodiment or variant considered, the amount Q2 or Q4 of glue present in the opening 320 or 340 does not necessarily fill the entire volume of this opening.

[0143] In the embodiment described above, the openings 320 and 340 have the same geometric shape as shown in the figures. In variations not represented, one or more of the openings in the half frames have different geometric shapes.

[0144] In the above-described embodiment, openings 320 and 340 have the same geometric shape as shown in the figures. In variations not represented, one or more openings in a half frame have a different geometric shape than the other openings in that half frame and / or one or more openings in a half frame have a different geometric shape than one or more openings in the other half frame.

[0145] The embodiments and variations as envisioned above can be combined to create new embodiments of the present invention.

Claims

1. A membrane-electrode assembly (2), a membrane (22, 25); A two-part frame (30), a first half frame (32) disposed on a first side of the membrane; a second half frame (34) disposed on a second side of the membrane; A two-part frame (30) formed by A membrane-electrode assembly (2) comprising: at least one first bipolar half plate (42); A subassembly (6) for a fuel cell stack (8), comprising: At least the second half frame (34) is coated on a first surface (S34) facing the first surface (S32) of the first half frame (32) with an adhesive layer for fixing the half frames; Each of the first openings (320) disposed through the first half-frame (32) is disposed facing the solid portion (42A) of the first bipolar half-plate (42) and facing the solid portion (34A) of the second half-frame (34) in a direction (A30) perpendicular to the main plane (π22) of the membrane; The first bipolar half plate (42) extends through the first opening (320) and is secured to the frame (30) by the amount (Q2) of adhesive that comes from the adhesive coated on the first surface (S34) of the second half frame (34). A subassembly (6) for a fuel cell stack (8), characterized in that:

2. The subassembly comprises a second bipolar half-plate (44) disposed opposite the first bipolar plate (4A) with respect to the membrane (22, 25), the first half frame (32) is coated on its first surface (S32) with an adhesive layer for fixing the half frames (32, 34); the second openings (340) disposed through the second half-frame (34) are each disposed facing the solid portion (44A) of the second bipolar half-plate (44) and facing the solid portion (32A) of the first half-frame (32) in the direction (A30) perpendicular to the main plane (π22) of the membrane; The second bipolar plate (44) extends through the second opening (340) and is secured to the frame (30) by the quantity (Q4) of adhesive that comes from the adhesive coated on the first surface (S32) of the first half frame (34).

2. A subassembly for a fuel cell stack according to claim 1.

3. 3. A subassembly for a fuel cell stack according to claim 2, characterized in that the first opening (320) and the second opening (340) are offset (Δ24) from each other in at least one direction parallel to the main plane (π22) of the membrane (22, 25), so that there is no overlap between these openings in the direction (A30) perpendicular to the main plane of the membrane.

4. 4. A subassembly for a fuel cell stack according to claim 2, characterized in that in the direction (A30) perpendicular to the main plane of the membrane, the first bipolar half-plate (42) is provided with a notch (48) aligned with the second opening (340) and / or the second bipolar half-plate (44) is provided with a notch (49) aligned with the first opening (320).

5. 5. A subassembly for a fuel cell stack according to claim 4, characterized in that the notches (48, 49) open onto at least one longitudinal edge of the bipolar plate in which they are formed.

6. Each opening (320, 340) disposed through the half-frames (32, 34) preferably has a circular, rectangular or oblong shape, and is 5 mm ２ More than 10 mm, preferably ２ 10. A subassembly for a fuel cell stack according to any one of the preceding claims, characterized in that it has a cross section with an area of ​​at least 100 .mu.m.sup.- ...

7. 10. Subassembly for a fuel cell stack according to any one of the preceding claims, characterized in that the adhesive is heat-activatable and based on a thermoplastic polymer, in particular an EVA copolymer.

8. At least one of the first openings (320) disposed through the first half frame (32) is located in the outer peripheral region (Z ｅｘｔ 10. A subassembly for a fuel cell stack according to claim 9, wherein the subassembly is arranged in a peripheral sealing gasket (50) of the subassembly (6), the region being located externally relative to the peripheral sealing gasket (50) of the subassembly (6).

9. The membrane-electrode assembly (2) includes four corners, and the subassemblies (6) are disposed through the first half frame (32), each at a corner of the membrane-electrode assembly, and the outer peripheral region (Z ｅｘｔ 10. A subassembly for a fuel cell stack according to claim 9, further comprising at least four first openings (320) arranged in a peripheral sealing gasket (50) of the subassembly (6), said areas being located externally with respect to a peripheral sealing gasket (50) of the subassembly (6).

10. At least one of the first openings (320) arranged through the first half frame (32) and the solid portion (42A) facing the opening belonging to the first bipolar half plate (42) is located in a gallery framing area (Z ｅｇ 10. The subassembly for a fuel cell stack according to claim 9, wherein a membrane-electrode assembly (2) is disposed around an opening (46) in the first bipolar half-plate (42) and is fluidly isolated from at least one anode or cathode fluid compartment defined within the subassembly between the membrane-electrode assembly (2) and the first bipolar half-plate (42).

11. A fuel cell (8) comprising a stack (60) of electrochemical cells each having a membrane-electrode assembly (2) and two bipolar half-plates (42, 44), characterized in that at least one of the cells comprises or is constituted by a subassembly (6) according to any one of the preceding claims.

12. A membrane-electrode assembly (2), a membrane (22, 25); A two-part frame (30), a first half frame (32) disposed on a first side of the membrane; a second half frame (34) disposed on a second side of the membrane; A two-part frame (30) formed by A membrane-electrode assembly (2) comprising: at least one first bipolar half plate (42); A method for manufacturing a subassembly (6), comprising: The method comprises at least a preliminary step of coating at least a first surface (S34) of said second half frame (34) with adhesive; fixing the frame (30) and the membrane (22, 25) by applying the first surface (S34) of the second half frame, which is coated with adhesive, to the first surface (S32) of the first half frame (32); Including, The method comprises at least applying the first bipolar half plate (42) to a second surface (S'32) of the first half frame (32) opposite the first surface (S32) of the first half frame; fixing the first bipolar half plate (42) and the frame (30) by movement of the adhesive coated on the first surface (S34) of the second half frame (34) towards the surface (S42) of the first bipolar half plate through a first opening (320) arranged in the first half frame (32) between its first surface (S32) and its second surface (S'32); A method comprising:

13. the subassembly comprising a second bipolar half-plate (44), and the method comprising at least a preliminary step of coating at least a first surface (S32) of said first half frame (32) with adhesive; applying the second bipolar half plate (44) to a second surface (S'34) of the second half frame (34) opposite the first surface (S34) of the second half frame; fixing the second bipolar half plate (44) and the frame (30) by movement of the adhesive coated on the first surface (S32) of the first half frame (32) towards the surface (S44) of the second bipolar half plate through a first opening (340) arranged in the second half frame between its first surface (S34) and its second surface (S'34); 13. The method of claim 12, comprising:

14. 14. The method according to claim 12 or 13, characterized in that during the fixing step, the adhesive coated on the first surface (S34) of the second half frame (34) and optionally on the first surface (S32) of the first half frame (32) is heated at least in the vicinity of the first opening (320) and optionally at the second opening (340).

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