WO2024126602A1

WO2024126602A1 - Subassembly for a fuel cell stack, fuel cell comprising such a subassembly and method for manufacturing such a subassembly

Info

Publication number: WO2024126602A1
Application number: PCT/EP2023/085657
Authority: WO
Inventors: Vincent Fabrice ROSSIGNOL; Clément Guillaume SANTINI
Original assignee: Symbio France
Priority date: 2022-12-14
Filing date: 2023-12-13
Publication date: 2024-06-20
Also published as: FR3143884A1; WO2024126602A9

Abstract

The invention relates to a subassembly for a fuel cell stack comprising at least a first bipolar half-plate (42) and a membrane-electrode assembly including a membrane and a bipartite frame (30) formed by a first half-frame (32) and a second half-frame (34). At least the second half-frame (34) is coated, on a first surface (S34) opposite a first surface (S32) of the first half-frame, with a layer of securing glue. First apertures (320) through the first half-frame (32) are each arranged opposite a solid portion (42A) of the first bipolar half-plate and opposite a solid portion (34A) of the second half-frame in a direction perpendicular to a main plane of the membrane (TT22). The first bipolar half-plate (42) is rigidly attached to the frame (30) by a quantity (Q2) of glue which extends through the first apertures (320) and which comes from the glue coated on the first surface (S34) of the second half-frame (34).

Description

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

The present invention relates to a subassembly intended to be integrated into a stack of electrochemical cells, within a fuel cell. The 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. The invention finally relates to a method of manufacturing a subassembly as mentioned above.

In the field of fuel cells, it is known to insert a stack of electrochemical cells between two end plates, located on either side of this stack in a stacking direction, and possibly to arrange this stack in a casing. . Electrochemical cells are formed by membrane-electrode assemblies and bipolar plates. A membrane-electrode assembly is sometimes called MEA, from the English “Membrane-Electrode Assembly”, and generally comprises a base membrane, which can be coated on one or both of its faces, with a catalytic layer comprising a catalyst, as well as a frame which supports this membrane. The frame may include apertures which, in the stack, define fluid flow galleries within the stack of electrochemical cells for the distribution and recovery of these fluids into the corresponding fluidic compartments of each cell. This frame is most often associated with at least one seal, sometimes called a “gasket”, with which it also provides a sealing function to the flow of fluids within the stack.

The membrane, when coated with layers comprising a catalyst, is sometimes called CCM, from the English "Catalyst Coated Membrane" and in this case comprises three layers, namely, a membrane itself, a catalytic layer on the anode side and a catalytic layer on the cathode side.

In the stack, a membrane-electrode assembly is inserted between two bipolar plates and thus delimits an anode compartment and a cathode compartment. On each side, the membrane coated with catalyst is covered by a gas diffusion layer which is therefore received in the corresponding anodic or cathodic compartment and promotes contacting of the chemical species, present in the corresponding anodic or cathodic compartment. , with the membrane. Each gas diffusion layer also has a role in conducting electrons. These diffusion layers are sometimes called GDL, from English “Gas Diffusion Layer”.

It is known to manufacture a membrane-electrode assembly by attaching the membrane coated with catalyst to the frame, which in particular makes it possible to stiffen this membrane and facilitate its handling. This takes place by sealing the membrane to the frame.

It is known to produce, during the manufacture of a fuel cell, bipolar plates formed of two half-plates or sheet metal strips which belong to two adjacent electrochemical cells. This requires handling separately the membrane-electrode assemblies, on the one hand, and the bipolar plates, on the other hand when they are placed within the stack of a fuel cell. This solution requires joining together the two half-plates or strips of a bipolar plate. This joining can be carried out by laser welding or brazing, in particular point by point, by plastic deformation of the strips, in particular by means of an electric tool creating an impact, or by gluing. However, we also know the possibility of having bipolar plates formed of two half-plates or strips of sheet metal which belong to two adjacent electrochemical cells, the two half-plates only being kept in contact with each other, by compression of the stack, generally with the interposition of one or more seals, which may be free seals or seals integrated into one or other of the half-plates.

Once the membrane-electrode assemblies, on the one hand, and the bipolar plates, on the other hand, are formed, they should be arranged alternately along the stacking direction, which in practice turns out to be long and difficult to implement.

It is known from WO-A-2014/1 11745 and US-B-8399150 to stick an electrochemical cell frame on a bipolar plate, by means of a layer of adhesive interposed between these parts. This approach requires joining the strips of the bipolar plates together using one of the techniques mentioned above and providing a quantity of adhesive dedicated to creating the connection between the frame and the bipolar plate. This approach imposes the way of then constituting the stack of electrochemical cells of the fuel cell and increases its cost price, on the one hand in terms of investment for the means of depositing the adhesive and on the other hand in terms of cost of this added adhesive.

It is also known from.JP2008084707A to distribute glue points between the two half-frames of a frame surrounding an electrochemical cell membrane and to pierce through holes in these half-frames which are aligned in a direction perpendicular to the plane of the membrane. A bipolar half-plate is attached to each half-frame using other glue dots. This assembly technique with glue dots requires a relatively large quantity of glue. Each bipolar half-plate is only directly attached to the adjacent half-frame. In addition, the glue placed between the two half-frames risks overflowing onto one side of the subassembly thus produced.

It is these drawbacks that the invention more particularly intends to remedy by proposing a new subassembly for a fuel cell stack, the manufacture of which is simplified and whose cost price can be reduced compared to previous materials.

To this end, the invention relates to a subassembly for a fuel cell stack comprising a membrane-electrode assembly including a membrane and a bipartite frame formed by a first half-frame disposed on a first side of the membrane and a second half -frame placed on a second side of the membrane. The membrane-electrode assembly also includes at least a first bipolar half-plate. At least the second half-frame is coated, on a first surface facing a first surface of the first half-frame, with a layer of glue for securing the half-frames.

In accordance with the invention, first orifices arranged through the first half-frame are each arranged facing a solid portion of the first bipolar half-plate and facing a solid portion of the second half-frame, according to a direction perpendicular to a main plane of the membrane. In addition, the first bipolar half-plate is secured to the frame by a quantity of glue which extends through the first orifices and which comes from the glue coated on the first surface of the second half-frame.

Thanks to the invention, the structure of the subassembly makes it possible to use the layer of glue provided primarily to secure together the two frames of the membrane-electrode assembly to ensure an additional function of immobilizing the first half -bipolar plate. This makes it possible to manipulate this subassembly in a unitary manner during the manufacture of a fuel cell incorporating it, which facilitates the work of an operator or a robot and makes it possible to increase production rates, therefore to reduce the cost price of the fuel cell. In addition, the mode of connection between the first bipolar half-plate and the frame is precise since the quantity of glue which extends through the first orifices is well positioned in space, thanks to these first orifices. In particular, this quantity of glue is not likely to flow outside the subassembly of the invention. Furthermore, in the case where the subassembly comprises a second bipolar half-plate, it constitutes a cell unitary electrochemical which can be tested, or even pre-activated, before its incorporation into a stack of cells, which makes a process for manufacturing such a cell more reliable.

According to advantageous but not obligatory aspects of the invention, such a subassembly can incorporate one or more of the following characteristics, taken in any technically admissible combination:

- The subassembly comprises a second bipolar half-plate arranged, relative to the membrane, opposite the first bipolar plate. The first half-frame is coated, on its first surface, with a layer of glue to secure the half-frames together. Second orifices provided through the second half-frame are each arranged facing a solid portion of the second bipolar half-plate and facing a solid portion of the first half-frame, in the direction perpendicular to a main plane of the membrane. In addition, the second bipolar plate is secured to the frame by a quantity of glue which extends through the second orifices and which comes from the glue coated on the first surface of the first half-frame.

- The first and second orifices are offset relative to each other in at least one direction parallel to the main plane of the membrane, so that there is no superposition between these orifices in the direction perpendicular to the main plane of the membrane. membrane.

- The first bipolar half-plate is provided with cutouts aligned with the second orifices and/or in that the second bipolar half-plate is provided with cutouts aligned with the first orifices, in the direction perpendicular to the main plane of the membrane.

- A cutout opens onto at least one longitudinal edge of the bipolar plate in which it is formed.

- Each orifice provided through a half-frame has a section whose area is greater than or equal to 5 mm ² , preferably 10 mm ² , with a preferably circular, rectangular or oblong shape.

- The glue is heat-activatable and based on thermoplastic polymer, in particular EVA copolymer.

- At least one of the first orifices provided through the first half-frame is arranged in a peripheral external zone of the sub-assembly which is located outwards relative to a peripheral seal of the sub-assembly.

- The electrode membrane assembly has four corners, while the sub-assembly comprises at least four first orifices arranged through the first half-frame and arranged in a peripheral external zone of the sub-assembly which is located outwards relative to a peripheral seal of the subassembly, each in a corner of the membrane electrode assembly.

- At least one of the first orifices arranged through the first half-frame and the facing solid portion belonging to the first bipolar half-plate are arranged in a gallery framing zone, arranged around an opening of the first bipolar half-plate, and fluidly isolated from at least one anodic or cathodic fluid compartment delimited in the subassembly, between the membrane electrode assembly and the first bipolar half-plate.

According to another aspect, the invention relates to a fuel cell comprising a stack of electrochemical cells, each with a membrane-electrode assembly and two bipolar half-plates, at least one of these cells comprising, or being constituted by, a subset as mentioned above.

This fuel cell has the same advantages as those mentioned above.

According to a third aspect, the invention relates to a method of manufacturing a subassembly, in particular a subassembly as mentioned above, comprising a membrane-electrode assembly including a membrane and a bipartite frame formed by a first half -frame placed on a first side of the membrane and a second half-frame placed on a second side of the membrane. The membrane-electrode assembly also includes at least a first bipolar half-plate. This method comprising at least one preliminary step of coating at least one first surface of the second half-frame with an adhesive and a step of joining the frame and the membrane by applying the first surface of the second half-frame, coated of glue, against the first surface of the first half-frame.

According to the invention this method comprises at least one step of applying the first bipolar half-plate against a second surface of the first half-frame opposite the first surface of this first half-frame and a step of securing the first bipolar half-plate and the frame by migration of the glue coated on the first surface of the second half-frame, towards a surface of the first bipolar half-plate, through first orifices arranged in the first half-frame, between its first and second surfaces.

This process makes it possible to form electrochemical cells or parts of electrochemical cells which can be easily integrated into a stack of fuel cell cells, according to a technique which can be well mastered, with high production rates. Advantageously, the subassembly comprises a second bipolar half-plate and the method comprises at least one preliminary step of coating at least one first surface of the first half-frame with an adhesive, a step of applying the second bipolar half-plate against a second surface of the second half-frame opposite the first surface of this second half-frame and a step of joining the second bipolar half-plate and the frame by migration of the glue coated on the first surface from the first half-frame, towards a surface of the second bipolar half-plate, through first orifices provided in the second half-frame, between its first and second surfaces.

It can also be provided that, during the joining step, the glue coated on the first surface of the second half-frame, and possibly on the first surface of the first half-frame, is heated at least in the vicinity of the first orifices , and possibly at the level of the second orifices.

The invention will be better understood and other advantages thereof will appear more clearly in the light of the following description of four embodiments of a subassembly, a fuel cell and a method. in accordance with its principle, given solely by way of example and made with reference to the appended drawings in which:

[Fig.1] Figure 1 is a partially exploded perspective view of a sub-assembly conforming to a first embodiment of the invention, this sub-assembly constituting an electrochemical cell belonging to a stack of a battery. combustible ;

[Fig.2] Figure 2 is an exploded perspective view of a membrane-electrode assembly belonging to the subassembly shown in Figure 1;

[Fig.3] Figure 3 is a front view of the subassembly shown in Figure 1;

[Fig.4] Figure 4 is a longitudinal section of the subassembly shown in Figures 1 and 3, along line IV-IV in Figure 3, during a step of manufacturing a fuel cell including this subassembly. -together ;

[Fig.5] Figure 5 is a partial view, similar to Figure 4, for a subassembly conforming to a second embodiment of the invention.

[Fig.6] Figure 6 is a simplified front view, similar to Figure 3, for a subassembly conforming to a third embodiment of the invention;

[Fig.7] Figure 7 represents, on two inserts A) and B) and on a larger scale, partial sections at the level of cutting lines A-A and B-B in Figure 6 in the case where the subassembly is integrated to a stack of electrochemical cells; And

[Fig.8] Figure 8 is a simplified front view, similar to Figure 6, for a subassembly conforming to a fourth embodiment of the invention. In order to clearly show the characteristics of the invention, the proportions are not necessarily respected between the objects represented in the figures.

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

The bipolar half-plates 42 and 44 can also be called polar plates.

We denote A2 as a longitudinal axis of the membrane-electrode assembly 2, which coincides with a longitudinal axis A6 of the subassembly 6.

The membrane-electrode assembly 2 can be called MEA and comprises a base membrane 22 which, in the example described below, is coated with catalyst. 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 visible in Figure 7 for the third embodiment. It is described with reference to this figure 7. The base membrane 22 is therefore, in the example, coated, on a first side facing upwards in figures 1, 2 and 7, with a first catalytic layer 23 forming a cathode and, on a second side opposite the first side and oriented downwards in Figures 1, 2 and 7, a second catalytic layer 24 forming an anode. The membrane 22 and the catalytic layers 23 and 24 together form a membrane coated with catalyst 25, otherwise called CCM. In the remainder of this description, this membrane coated with catalyst 25 is called CCM membrane.

Here, the base membrane 22 is made of polymer material, in particular of the NAFION type (registered trademark), and has a thickness of the order of 0.005 to 0.050 mm, preferably 0.008 to 0.015 mm. The catalytic layers 23 and 24 are made from a platinum base and each have a thickness of the order of 0.001 to 0.010 mm, preferably 0.002 to 0.005 mm. The thickness of the CCM membrane 25 is preferably between 0.008 and 0.050 mm, preferably of the order of 0.017 mm.

We note TT22 as a median plane of the base membrane 22, which is also a median plane of the CCM membrane 25. The longitudinal axis A2 is included in the median plane TT22.

The CCM membrane 25 is mounted on a frame 30 consisting of two half-frames

32 and 34 which are intended to come in plane support against each other which are, for example, made of polymer film, for example poly(ethylene terephthalate) or PET or poly(ethylene naphthalate) or PEN.

We note TT30 a support plane of the two half-frames 32 and 34 against each other. The TT30 plane is also a median plane of the frame 30 and it includes the longitudinal axis A2. The two half-frames 32 and 34 are configured to trap between them a peripheral edge 22a of the membrane 22 when they rest against each other along the plane TT30. In this configuration, the half-frames 32 and 34 form a zone, also called "overlap", between the membrane 22 and the two half-frames 32, 34. Along each longitudinal edge or each transverse edge of the frame, the overlap has a width for example included in the range from 1 to 5 mm, preferably in the range from 2 to 4 mm.

The half-frame 32 is arranged on a first side of the CCM membrane 25, in the example above the membrane in Figures 1, 2 and 7, while the half-frame 34 is arranged on a second side of the CCM membrane 25, in the example below the membrane in Figures 1, 2 and 7. This has the effect of immobilizing the membrane 22, that is to say in practice the CCM membrane 25, by pinching it between the half-frames 32 and 34, within the frame 30.

Advantageously, the thickness of each of the half-frames 32 and 34 is between 0.020 and 0.030 mm, preferably of the order of 0.025 mm.

The frame 30 makes it possible to stiffen the CCM membrane 25 and hold it in position within the stack.

In practice, the half-frames 32 and 34 are secured to each other at the level of the TT30 support plane, preferably by means of glue.

Preferably, as can be seen in Figure 4 for example, the glue is not deformed and remains parallel to the TT30 plane.

We denote S32 the surface of the half-frame 32 facing the half-frame 34. We denote S34 the surface of the half-frame 34 facing the half-frame 32. In the mounted configuration of the frame 30 around the membrane 22, the surfaces S32 and S34 are in surface contact with each other, aligned on the TT30 plane and secured to each other by means of glue.

In this configuration, the median plane TT22 of the membrane 22 is also aligned with the plane TT30.

The glue used to assemble the half-frames 32 and 34 is, preferably, a heat-activatable glue based on a thermoplastic polymer, for example an glue based on an EVA copolymer, such as the glue marketed under the reference AP12 by the company Micel. Advantageously, the thickness of the layer of glue coated, that is to say deposited, on the surface S32 or S34 of each of the half-frames is between 0.01 to 0.02 mm, preferably, of the of the order of 0.013 mm, before application of surfaces S32 and S34 against each other.

Advantageously, the frame 30 defines openings 36 intended to form circulation and fluid distribution/collection galleries within the stack, when several subassembly 6 are juxtaposed within the stack, in a direction perpendicular to their TT30 midplanes.

The openings 36 are formed by aligning, in directions parallel to the axis A30, individual openings 36s and 364 formed respectively in the half-frames 32 and 34.

As a variant, particularly in the case of a so-called fuel cell with “external manifolds”, the frame 30 does not have openings of the type of openings 36.

We note A30 an axis perpendicular to the plane TT30 and passing 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, therefore to their median plane TT22.

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

Each bipolar half-plate 42 or 44 is equipped with openings 46 of the same geometry as the openings 36 and which also participate in the definition of these galleries.

We denote respectively 32A and 32B the longitudinal ends of the half-frame 32. We denote respectively 34A and 34B the longitudinal ends of the half-frame 34.

We respectively note A32 and A34 a longitudinal axis of the half-frame 32 and a longitudinal axis of the half-frame 34. In the mounted configuration of the membrane-electrode assembly 2, the axes A2, A32 and A34 are perpendicular to the axis A30 , parallel to each other and, preferably almost merged, to the thickness of the half-frames. We note respectively B32 and B34 a transverse axis of the half-frame 32 and a transverse axis of the half-frame 34, respectively perpendicular to the axes A32 and A34. In the mounted configuration of the membrane-electrode assembly 2, the axes B32 and B34 are perpendicular to the axis A30, parallel to each other and, preferably almost identical, to the thickness of the half-frames.

The half-frames 32 and 34 each define a central opening 32C, respectively 34C, which passes right through them and opposite which the CCM membrane 25 is arranged in the mounted configuration of this membrane on the frame 30. central openings 32C and 34C of the half-frames 32 and 34 are therefore delimited by internal edges of these half-frames. The meeting of the central openings 32C and 34C defines a central opening 30C of the frame 30, which is closed by the CCM membrane in the mounted configuration of the membrane-electrode assembly 2. The half-frames 32 and 34, and therefore the frame 30 which They constitute, present a closed contour around the corresponding central opening.

We note 32D the transverse edges of the central opening 32C of the half-frame 32, each transverse edge being parallel to the axis B32. We note 34D the transverse edges of the central opening 34C of the half-frame 34, each transverse edge being parallel to the axis B32.

Advantageously, the membrane-electrode assembly 2 also comprises a first gas diffusion layer 28 and a second gas diffusion layer 29 which can be called GDL and which have the function of promoting exchanges between the CCM membrane 25 and the fluids. circulating between the two bipolar half-plates 42 and 44 of a subassembly 6 to which this membrane-electrode assembly belongs.

Advantageously, the thickness of the diffusion layers 28 and 29 is between 0.050 and 0.320 mm, preferably of the order of 0.250 mm.

In the mounted configuration of the membrane-electrode assembly 2, the diffusion layers 28 and 29 cover the CCM membrane 25 and part of the frame 30, in the vicinity of the central opening 30C, each on one side of the CCM25 membrane.

To allow the immobilization of the bipolar half-plates 42 and 44 on the frame 30 equipped with the CCM membrane 25, each of the half-frames 32 and 34 is equipped with first orifices 320, respectively second orifices 340, which are arranged on either side and on the other side of its central opening 32C or 34C, along its longitudinal axis A32 or A34, and on either side of its individual openings 36s or 364 along its transverse axis B32 or B34. The first orifices 320 are intended to be covered by the bipolar half-plate 42, while the second orifices 340 are intended to be covered by the bipolar half-plate 44, in the mounted configuration of the subassembly 6. Thus, in the mounted configuration of the subassembly 6, the orifices 320 and 340 are arranged opposite the bipolar half-plates 42 and 44, in a direction parallel to the axis A30, that is to say in a direction perpendicular to the planes TT22 and TT30 .

In the example, the orifices 320 of the half-frame 32 are 4 in number, as are the orifices 340 of the half-frame 34.

As a variant not shown, a different number of orifices 320 and 340 can be provided, or even orifices in different numbers on the two half-frames. The half-frame 32 comprises two rows of two orifices 320 which extend respectively near the ends 32A and 32B of the half-frame 32, on either side of the individual openings 362, and which connect the surface S32 of the half-frame 32. frame 32 to a surface S'32 of the half-frame 32 which is opposite the surface S32 and on which the first bipolar half-plate 42 and the diffusion layer 28 bear. The orifices 320 therefore pass through the thickness of the half -frame 32.

In the same way, the half-frame 34 comprises two rows of two orifices 340 which extend respectively near the ends 34A and 34B of the half-frame 34, on either side of the individual openings 364, and which connect the surface S34 of the half-frame 34 to a surface S'34 of the half-frame 34 which is opposite the surface S34 and on which the second bipolar half-plate 42 and the diffusion layer 28 bear. The orifices 340 therefore pass through the thickness of the half-frame 34.

Advantageously, the orifices 320 are distributed on the first half-frame 32 symmetrically with respect to the axes A32 and B32. In the same way, the orifices 340 are distributed on the first half-frame 34 symmetrically with respect to the axes A34 and B34.

Advantageously, the orifices 320 are further away from the transverse edges 32D than the orifices 340 are further away from the transverse edges 34D. Thus, the orifices 320 and 340 are offset relative to each other, in a direction parallel to the longitudinal axes A32 and A34, so that there is no superposition between these orifices in the direction of the axis A30.

We note d32 a distance measured parallel to axis A32 between axis B32 and a straight line passing through the geometric centers of the orifices 320. We note d34 a distance measured parallel to axis A34 between axis B34 and a straight line passing by the geometric centers of the orifices 340. The distances d32 and d34 are different. In the example, the distance d32 is greater, by a non-zero deviation A24, compared to the distance d34 and this deviation A24 induces an offset between the orifices 320 and 340, parallel to the longitudinal axes A32 and A34, such that there is no overlap between them.

According to a not shown variant of the invention, in addition to or instead of the offset in a direction parallel to the longitudinal axes A32 and A34, the orifices 320 and 340 are offset relative to each other, in a direction parallel to the transverse axes B32 and B34, which also avoids superposition between these orifices in a direction parallel to axis A30.

We denote S42 the surface of the first bipolar half-plate 42 facing the frame 30 in the assembled configuration of the subassembly 6. We denote S44 the surface of the second bipolar plate 44 facing the frame 30 in the assembled configuration of the subassembly 6. In the assembled configuration of the subassembly 6, each orifice 320 extends, through the half-frame 32, between the surfaces S34 and S42, while each orifice 340 extends, through the half-frame 34, between the surfaces S32 and S44.

In the vicinity of two of its opposite corners, the first bipolar half-plate 42 is provided with two cutouts 48 which open onto two opposite longitudinal edges of this half-plate and which give access, from above in Figure 1, to two zones Z2 of the first half-frame 32 which are opposite with respect to the axes A32 and B32 and which cover from above the orifices 340 of the second half-frame 34, when the subassembly 6 is mounted. Likewise, the second bipolar half-plate 44 is provided, at two of its opposite corners, with two cutouts 49 which open onto two longitudinal edges and two opposite transverse edges of this half-plate and which give access, from below in Figure 1, two zones Z4 of the second half-frame 34 which are opposite with respect to the axes A34 and B34 and which cover from below the orifices 320 of the first half-frame 32, when the subassembly 6 is mounted.

A system of peripheral seals 50 is arranged between the frame 30 and the bipolar half-plates 42 and 44, on each side of the frame. In practice, two peripheral seals 50 are provided, one on surface S’32, the other on surface S’34. These seals 50 surround both the central opening 30C and the openings 36 of the frame, so that they ensure sealing, with respect to the exterior of the subassembly 6, for each of the operational fluids of the battery, to have hydrogen, oxygen, air and possible cooling fluid. These peripheral seals 50 therefore fluidly isolate the cathode compartment from the outside and the anode compartment from the outside.

Each of the openings 36, 46 is also surrounded by a system of opening seals 51 which do not allow, for a given fluid compartment, namely one among the anode compartment, the cathode compartment and a possibly compartment of cooling between two adjacent cells, the fluid communication of this compartment given only with the openings 36, 46 which allow the entry and exit of the fluid in this compartment. In practice, two series of opening seals 51 are provided, one on the surface S’32, the other on the surface S’34.

In Figure 3, the joints 50 and 51 are shown in dotted lines, seen through the bipolar half-plate 42. The joints 50 surround an internal zone Z _int of the subassembly 6 in which the CCM membrane 25, the layers are located gas diffusion 28 and 29 and the gallery portions formed by the openings 36 and 46. A peripheral external zone Z _ext of the subassembly 6 is defined around the joints 50, between these joints and the edges external parts of the subassembly. The joints 50 surround the different joints 51 which connect to the joints 50. In other words, the joints 51 are located in the internal zone Z _int .

We define an external peripheral zone Z _ext3 o of the frame 30 as the zone of this frame which belongs to the external peripheral zone Z _ext of the subset 6 in the mounted configuration of this cell. The external peripheral zone Z _ext3 o therefore surrounds the joints 50, on each of the half-frames 32 and 34.

In order not to break the seal provided by the seals 50, and as visible in Figures 1 to 3, the first and second orifices 320 and 340 are preferably provided in the peripheral external zone Z _ext3 o of the frame 30, therefore in the peripheral external zone Z _ext of subassembly 6.

A method of manufacturing a subassembly 6 as mentioned above is described below.

During a first preliminary step, surfaces S32 and S34 are coated with glue. This preliminary step can be carried out on the manufacturing site of the membrane-electrode assembly 2, just before the following steps or in advance. Alternatively, this preliminary step can be carried out at a remote site, from where the half-frames coated with glue are transported to the manufacturing site of the membrane-electrode assembly. The operation of coating surfaces S32 and S34 with glue can therefore be carried out by a manufacturer different from the one manufacturing the membrane-electrode assembly. In such a case, a protective film can be provided on the glue layer to convey it, this protective film then being removed before the second step described below.

During a second step, the two half-frames 32 and 34 are supported by their surfaces S32 and S34 along the plane TT30, while the membrane 22 is placed between them, which has the effect of pinching the edge 22a of the membrane 22 and to secure the frame 30 and the membrane 22, that is to say the frame 30 and the CCM membrane 25. The frame 30 is constituted by the adhesion of the surfaces S32 and S34 thanks to the glue which is coated there.

Advantageously, during the second step, the assembly of the two half-frames 32 and 34, by trapping the edges of the membrane 25, is carried out by activating the glue by application of ultrasound. Typically, the assembly of the two half-frames 32 and 34 imprisoning the membrane 25 is clamped between a sonotrode and an anvil, and the ultrasound transmitted by the sonotrode to the two half-frames 32 and 34 ensures activation of the glue, therefore bonding the two half-frames 32 and 34 together and, in the overlapping zone, bonding the two half-frames 32 and 34 with the membrane. Conventionally, the application of ultrasound can be implemented in particular by means of a ridged sonotrode, such as those known for example from US-B-10981245 or from US- A-2013/213552. Typically, as illustrated in US-A-2013/213552, the groove can for example be formed of two or three networks of grooves formed on the surface of the sonotrode, each network comprising grooves parallel to each other in a direction specific to each network . The grooves of the networks thus delimit between them projecting pins which are the preferred contact zones with the frame during the application of ultrasound. Note that the use of a ridged sonotrode can form, on the surface at least of the half-frame with which the sonotrode is in contact, a texturing of the surface of the half-frame which is substantially the inverted image of the ridged of the sonotrode. This texturing may have a depth less than the depth of the ridge of the sonotrode. The sonotrode can be grooved over its entire surface in contact with the two half-frames 32 and 34, or over only part of its surface. Preferably, the entire surface of the two half-frames 32 and 34 is assembled by ultrasound. In other words, the bonding zone of the two half-frames, which corresponds to the zone where the ultrasound is applied, then corresponds to the entire surface area of the frame 30. In certain embodiments, the entire bonding zone of the two half-frames, which corresponds to the zone where the ultrasound is applied, presents a texturing of the surface of the half-frame which is substantially the inverted image of the streaking of the sonotrode. In other embodiments, only one or more portions of the bonding zone of the two half-frames, which corresponds to the zone where the ultrasound is applied, presents such texturing, other portions of the bonding zone resulting the activation of the glue using a smooth sonotrode or a smooth portion of a sonotrode. In the overlapping zone of the frame 30 with the membrane 25, the ultrasound causes the assembly by gluing of each of the two half-frames 32 and 34 on the corresponding face of the membrane. Preferably, it is avoided that the sonotrode comes into contact with the membrane 25 inside the window delimited inside each half-frame, to avoid heating and compressing the membrane 25 in its actually active part which will be exposed to the reagents. The sonotrode used can be in the form of a frame, possibly allowing the complete assembly of the frame 30 on the membrane 25 in a single operation. Alternatively, we can plan to use a sonotrode covering only part of the desired bonding zone, the complete assembly of the frame 30 on the membrane 25 can then be carried out in several successive operations. Alternatively, one can plan to use several sonotrodes, each covering only part of the bonding zone, the complete assembly of the frame 30 on the membrane 25 can then be carried out in a single operation for all the sonotrodes simultaneously. , or in several successive operations with one or more sonotrodes used in each operation. During a third step, the diffusion layers 28 and 29 are deposited on the frame 30 then assembled thereon by any appropriate technique, for example by gluing.

During a fourth step, the two bipolar half-plates 42 and 44 are applied on either side of the frame 30 equipped with the CCM membrane 25 and the GDL layers 28 and 29, more precisely on the external surfaces S'32 and S'34 of the half-frames 32 and 34. The locations and dimensions of the cutouts 48 and 49 are chosen such that, at the end of the fourth step, the bipolar half-plate 42 covers the orifices 320 and the cutouts 48 are aligned, parallel to the axis A30, with the orifices 340, while the bipolar half-plate 44 covers the orifices 340 and the cutouts 49 are aligned, parallel to the axis A30, with the orifices 320. Thus, according to a direction parallel to axis A30, each orifice 320 is arranged between a solid portion 42A of the bipolar half-plate 42 and a solid portion 34A or 34B of the half-frame 34, facing a cutout 49, and each orifice 340 is arranged between a solid portion 44A of the bipolar half-plate 44 and a full portion 32A or 32B of the half-frame 32, facing a cutout 48. The solid portions 32A and 34A of the half-frames 32 and 34 are constituted , in this embodiment, at their longitudinal ends 32A and 34A. The solid portions 32A and 34A of the half-frames 32 and 34 are constituted by zones respectively devoid of openings 36 and orifices 320 or 340. At the level of these solid portions 32A and 34A, the surfaces S32 and S34 are not interrupted. The solid portions 42A and 44A of the bipolar half-plates 42 and 44 are constituted by zones respectively devoid of openings 46 or other orifice or cutout. At the level of these solid portions 42A and 44A, the surfaces S42 and S44 are not interrupted.

The geometry of the GDL 28 is such that it does not interpose between the first orifices 320 and the solid portions 42A of the bipolar half-plate 42 which are facing the orifices 320, so as to allow direct contact, at through a first given orifice 320, of the solid portion 34A, corresponding to this first given orifice 320, of the half-frame 34, with the solid portion 42A corresponding to this first given orifice 320, of the bipolar half-plate 44. Likewise, the geometry of the GDL 29 is such that it does not interpose between the second orifices 340 and the solid portions 44A of the bipolar half-plate 44 which are facing the orifices 340, so as to allow contact direct, through a second given orifice 340, of the solid portion 32A, corresponding to this second given orifice 340, of the half-frame 32, with the solid portion 44A corresponding to this first given orifice 340, of the half-plate bipolar 42. In both cases, such relative positioning can be achieved by the geometry of the external contour of the GDL 28, 29, as in the example illustrated, or perhaps achieved by the presence of an orifice in the GDL 28, 29. A solid portion of a half-frame or half-bipolar plate corresponds to a first or second orifice when it is aligned with, in other words facing, this orifice, in a parallel direction to the A30 axis.

We thus constitute a nine-layer structure, namely the three layers 22, 23 and 24 of the CCM membrane 25, the two half-frames 32 and 34, the two GDL 28 and 29 and the two bipolar half-plates 42 and 44 This multilayer structure is intended to form subassembly 6, at the end of the process of the invention.

A fifth step of securing the first and second bipolar half-plates 42 and 44 with the frame 30 is implemented by activating, for example by heating, the glue present on the surfaces S32 and S34, at least over the extent of the portions solid portions 34A of the half-frame 34 which are facing the first orifices 320, and over the extent of the solid portions 32A of the half-frame 32 which are facing the second orifices 340. This activation can optionally be completed by a pressing operation to guarantee contact, through first and second orifices 320 and 340, of the glue thus activated with the corresponding solid portion 44A, 42A of the bipolar half-plate 44, 42. The optional pressing can be concomitant, at least in part, upon activation. Pressing may follow activation, or may begin before or during activation and continue beyond activation. Thus, through a first given orifice 320, the solid portion 34A of the half-frame 34, which is opposite this first given orifice 320, is secured to the corresponding solid portion 42A, of the bipolar half-plate 42 , which is also opposite this first orifice 320 given, this in particular by the glue initially carried by full portion 34A of the half-frame 34. We can therefore consider that at least part of the glue initially carried by the half-frame 34 migrates, through the first given orifice 320, to reach the surface S42 of the polar half-plate 42. Likewise, through a second given orifice 340, the solid portion 32A of the half-frame 32, which is in facing this second given orifice 340, is secured to the corresponding full portion 44A of the bipolar half-plate 44, which is facing this second given orifice 340, this in particular by the glue initially carried by full portion 32A of the half- frame 32. We can therefore consider that at least part of the glue initially carried by the half-frame 32 migrates through the second given orifice 340 to reach the surface S44 of the half-polar plate 44.

Furthermore, the activation of the glue can, particularly in the case of thermoplastic glues activated by heating, have the effect of fluidifying this glue and allowing a part of this glue, in particular that located in the vicinity around a first and /or second orifice 320 and 340 given, to then migrate into this orifice 320 and 340, respectively towards the surfaces S44 and S42. In particular, heating the glue present on the surface S34 can also have the effect of causing part of the glue present between the half-frames 32 and 34 to flow into the orifices 320. Likewise, heating the glue present on the surface S32 can also have the effect of causing part of the glue present between the half-frames 32 and 34 to flow into the orifices 340. Thus, during the fifth step, the glue previously coated on the surfaces S32 and S34 can flow between these surfaces and migrate to the nearest hollow volumes which are constituted by the orifices 320 and 340. From there, the glue flows, in these orifices, towards the edges of these orifices which adjoin the surfaces S42 and S44 of the bipolar half-plates 42 and 44 which it reaches at the end of the fifth step.

The above assumes such migration of the glue “in the vicinity and around” the first and/or second orifices. This implies that the glue is activated, in particular by heating, on an area which covers these orifices and whose area is strictly greater than that of these orifices.

During the fifth step, the first bipolar half-plate 42 is secured to the frame 30 thanks to the glue present in the orifices 320, while the second bipolar half-plate 44 is secured to the frame 30 thanks to the glue present in the orifices 320. 340 holes.

The fifth step is advantageously carried out by application of a localized heat source 82 on the half-frame 34, located in the alignment of each orifice 320 in a direction parallel to the axis A30, and by application of a heat source. localized heat 84 on the half-frame 32, located in the alignment of each orifice 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 locally raise the temperature of the glue, in order to ensure its activation and, possibly, to facilitate its flow into the orifices 320 and 340.

The heat source is advantageously a heating bar which can be manipulated by hand by an operator or by a robot and which includes a heating resistance. The heating bar may in particular be of the type of a manual welding station stylus. The heating bar can also be a system operating by impulse.

Possibly a mechanical force, that is to say a pressure of the heat source towards the frame is exerted jointly with the heat input, which makes it possible to secure the activation of the glue and the assembly of the frame 30 with the bipolar half-plate 42.

Here the heating bar 82 is inserted, in a direction parallel to the axis A30, in a cutout 49 and/or the heating bar 84 is inserted, in a direction parallel to the axis A30, in a cutout 48, to bring heat as close as possible to the glue coated on the surface S34 or S32, by direct application to the zone Z4 or Z2 of the half-frame 34 or 32 accessible through the cutout in question.

Alternatively, only one of the bipolar half-plates 42 or 44 is equipped with cutouts.

The fact that the cutouts 48 and 49 each open onto at least one longitudinal edge of the bipolar half-plates 42 and 44 facilitates contact between the heating bar 82 or 84 and the half-frame 32 or 34.

Alternatively, during the fifth step, the heating of the glue is carried out by radiation, by convection, in particular with blown hot air, by application of ultrasound or ultraviolet rays. The choice of heating mode, and therefore the heat source used, depends on the type of glue used and the geometry of the bipolar half-plates and the frame.

In addition and advantageously, as has already been mentioned above, a step of pressing the multilayer structure, in a direction parallel to the axis A30, can be implemented, as well as an application step of vibrations to the glue present in the multilayer structure. This pressing and this vibration facilitate the migration of the glue, from the surfaces S34 and S32 respectively towards the surfaces S42 and S44, within the orifices 320 and 340 and/or can facilitate the bringing into contact of this glue with the surface S42 and S44 through the orifices 320 and 340. The pressing can be localized, for example concentrated on the extent of the first and second orifices, or can be extended to a larger area of the multilayer structure, possibly to the entirety of the surface of the multilayer structure or the entire surface portion of the multilayer structure which is located outside the perimeter of the GDLs 28 and 29.

Following the fifth step, a quantity Q2 of glue initially located on the surface S34 is present in each orifice 320, so that it connects the surface S42 to the portion of the surface S34 located opposite this orifice 320 and possibly at the edge of this orifice which adjoins the surface S34, that is to say at the level of the solid portion 34A of the half-frame 34 which is opposite the orifice 320. In addition, a quantity Q4 of glue initially located on the surface S32 is present in each orifice 340, so that it connects the surface S44 to the portion of the surface S32 located opposite this orifice 340 and possibly to the edge of this orifice which adjoins the surface S32, it is that is to say at the level of the solid portion 32A of the half-frame 32 which is opposite the orifice 340. In other words, the quantity of glue Q2 generally comes mainly from the glue initially coated on the surface S34, while the quantity of glue Q4 generally comes mainly from the glue initially coated on the surface S32. In this regard, the fact that there is no superposition between the orifices 320 and 340 guarantees that a full portion of a half-frame, coated with glue, is exposed, through each orifice 320 or 340, facing a full portion of the opposite half-plate. Thus, the quantities of glue Q2 and Q4 which extend respectively into the orifices 320 and 340 ensure the bonding, either of the first bipolar half-plate 42, or of the second bipolar plate 44, on the frame 30, without direct connection between these two half-plates 42, 44 through the frame 30.

The glue constituting a quantity Q2 can be formed by the sole quantity of glue present on the portion of the surface S34 facing an orifice 320, while the glue constituting a quantity Q4 can be formed by the sole quantity of glue present on the portion of surface S32 facing an orifice 340.

Alternatively and as explained above, the glue constituting a quantity Q2 can be formed from the glue which was, before the fifth step, on the surface S34, both at and around an orifice 320, while the glue constituting the quantity Q4 is formed by glue which was, before the fourth step, on the surface S32, both at and around an orifice 340.

Preferably, the quantity Q2 of glue extends, within the first orifices 320, parallel to the plane TT30. In other words, the quantity Q2 of glue is not deformed during the assembly process, so that the quantity Q2 of glue is, on the finished product, not deformed, but on the contrary parallel to the plane TT30 .

In other words, the method of manufacturing the subassembly 6 of the invention takes advantage of the fact that a glue is applied to the surfaces S32 and S34 to use it, on the one hand, to join the half -frames 32 and 34 between them and around the CCM membrane 25 and, on the other hand, to secure the bipolar half-plates 42 and 44 on the frame 30, without the use of additional glue, welding or a other means of assembly.

The section of the orifices 320 and 340 can be chosen with a relatively small area, less than or equal to 50 mm ² , preferably 20 mm ² . This avoids weakening the frame 30, while allowing effective joining of the bipolar half-plates 42 and 44 to the frame. In addition, the section of the orifices 320 and 340 can be chosen with an area greater than or equal to 5 mm ² , preferably 10 mm ² . This allows the glue surface in contact with a surface S42 or S44 to be sufficient to ensure effective immobilization of the bipolar half-plate 42 or 44.

For example, the orifices 320 and 340 can be circular in shape, with a diameter of between 3 and 8 mm, preferably of the order of 5 mm, as shown in the figures. Alternatively, they can be of any other shape, for example in the shape of a polygon (triangle, rectangle, pentagon, hexagon, etc.) or in an oblong shape, with a length in the range from 5 to 10 mm, for example 7 mm and a width included in the range from 2 to 5 mm. Of course, a larger size of the orifices is also possible, making it possible in particular to increase the adhesion force, but with potentially repercussions on the total size, or on the positioning with respect to the plate.

At the end of the fifth step of the process of the invention, the subassembly 6 constitutes an electrochemical cell and can be manipulated, by a human operator or a robot, without the risk of its different layers separating from each other, because these are effectively maintained in relation to each other thanks to the glue coated on the surfaces S32 and S3 during the first preliminary step and part of which is in the orifices 320 and 340.

When several electrochemical cells have thus been created, in the form of subassemblies 6, by repeating the first to fifth steps mentioned above, it is possible to continue the manufacture of the fuel cell 8 by forming, during a subsequent step, a stacking, by juxtaposition of the different cells, as shown in Figure 7 for the third embodiment. This subsequent step is easy and quick to implement, by manipulating the electrochemical cells each individually.

The first five steps mentioned above make it possible to constitute cells which have all their main components, including the CCM membrane 25 and the two bipolar half-plates 42 and 44, and which, under normal handling, do not risk prevent them from accidentally separating or shifting, which allows them to be tested or even pre-activated. Indeed, creating an individual electrochemical cell in this way offers the opportunity to then test it with appropriate tools, tools ensuring the various seals and allowing the reagents and possibly the cooling fluid to be supplied. Such test tools are advantageously capable of, and designed to, measure the efficiency of the cell. Advantageously, the same tooling, or separate tooling makes it possible to carry out, at least partially, the electrochemical running-in which is usually practiced after the stacking of the cells, when the cell is assembled. Such activation, at least partial, makes it possible to bring the electrochemical performance to or close to the expected level of initial performance. Such testing and/or pre-activation operations make it possible to validate the operation and performance of the cell thus preassembled, before integrating them into the stack.

In the first embodiment, the sealing of the anode compartment, between the membrane-electrode assembly 2 and the anodic bipolar half-plate, and of the cathode compartment, between the membrane-electrode assembly 2 and the cathode bipolar half-plate , is ensured by the peripheral seals 50 and the seals opening 51, and not by the pre-assembly of the membrane-electrode assembly 2 with one and/or the other of the bipolar half-plates, as described above. Indeed, this pre-assembly by the quantities Q2, Q4 of glue which extend through the first and/or second orifices 320, 340 and which come from the glue coated on the first surface S34 of the second half-frame 34 or glue coated on the second surface S32 of the first half-frame 32, only form a pre-assembly at point areas. This pre-assembly is therefore incapable of ensuring fluid sealing of the compartment concerned with respect to the outside.

In the second to fourth embodiments shown in Figures 5 and following, the elements similar to those of the first embodiment bear the same references. In what follows, we mainly describe what distinguishes these embodiments from the first. If a reference is mentioned in the rest of the description without being mentioned in one of Figures 6 to 8 or if a reference is given in one of Figures 6 to 8 without being mentioned in the rest of the description, it designates the same object as that bearing the same reference in the first embodiment.

In the second embodiment, the bipolar half-plates 42 and 44 do not have, for at least one orifice 320 and/or 340, a cutout comparable to the cutouts 48 and 49 of the first embodiment. More particularly, in certain variants of this second embodiment, the bipolar half-plates 42 and 44 are entirely devoid of cutouts comparable to the cutouts 48 and 49 of the first embodiment, so that each second orifice 340 is arranged between a portion full 44A of the second bipolar half-plate 44 and a full portion 32A of the half-frame 32 which is itself arranged opposite a full portion 42A of the first bipolar half-plate 42. In other words, at level of the second orifices, the frame 30 is covered, on its two opposite sides, by the bipolar half-plates 42 and 44. Thus, the bipolar half-plates are simpler to manufacture than in the first embodiment and are interchangeable.

In this second embodiment, the heating of the glue is obtained by applying a heat source 84 not directly to the frame 30, as in the first embodiment, but to the portion 44A of the second half-plate 44, in the area where it is desired to secure it to the frame 30, that is to say opposite an orifice 340. A quantity Q2 of glue, which has migrated from the layer of glue previously coated on the surface S32 of the half-frame 32, then ensures the connection between the frame 30 and the bipolar half-plate 44 through the orifice 320.

As a variant not shown, the heat source can be applied to the portion 42A of the first half-plate 42. At each orifice 320, the situation is symmetrical with respect to the plane TT30, with respect to that shown in Figure 5.

This embodiment is simpler to implement than the previous one, at the cost of potentially less efficient heating of the glue.

In Figures 6 and 8, the zones where it is preferable to provide the first and second orifices 320 and 340 are identified with single-line hatching and the exclusion zones, where these orifices are preferably not provided, are identified with cross hatching.

In the third embodiment of Figures 6 and 7, the subassembly 6 comprises a system of peripheral seals 50, which is formed of peripheral seals ensuring the same function as the system of peripheral seals 50 of the first embodiment. An opening seal system 51 is also provided, with the same function as the opening seal system 51 of the first embodiment.

In the third embodiment of Figures 6 and 7, the peripheral seals 50 partly provide the function of sealing the openings, with the opening seals 51 which connect with the peripheral seal 50.

Compared to the first embodiment, an additional peripheral seal 50 is arranged on the surface of the bipolar half-plate 42 opposite the frame 30, as visible in the upper part of the inserts A) and B) of Figure 7. According to a variant not shown of the invention, it is the same at the level of the opening seals 51.

As visible in Figure 7, the stack 60 of electrochemical cells 6, produced within a fuel cell 8 conforming to the invention, comprises several electrochemical cells, formed by subassemblies 6 also conforming to the invention , which are separated by bipolar plates 4 each constituted by a first half-bipolar plate 42 belonging to a cell 6 and by a second half-bipolar plate 44 belonging to an adjacent cell 6, the frames 30 of these subassemblies being maintained tightened in a tight manner relative to the bipolar plates 4, with peripheral seals 50, arranged in particular along the longitudinal edges of the electrochemical cells and opening seals 51 which each surround one of the openings 36, 46 forming the galleries d flow of fluids within the stack of electrochemical cells.

The peripheral seals 50 delimit the interior limit of a peripheral external zone Z _ext of the subassembly 6 which is delimited in a sealed manner with respect to the anodic, cathode and cooling fluid compartments. The area external peripheral zone Z _ext of the subassembly 6 is therefore located outwards relative to at least one peripheral seal 50 of the subassembly 6. It is in this external peripheral zone Z _ext , exterior, in particular with respect to the peripheral joint 50 provided between the frame 30 and the first bipolar half-plate 42, which is preferably chosen to place the first orifices 320 arranged through the first half-frame 32 and the solid portions 42A of the first half-plate bipolar 42. It is also in this external peripheral zone Z _ext , exterior, in particular with respect to the peripheral joint 50 provided between the frame 30 and the second bipolar half-plate 42, that we preferably choose to place the second orifices 340 arranged through the second half-frame 34 and the solid portions 44A of the second bipolar half-plate 44. For each electrochemical cell 6, the peripheral seals 50 are generally arranged set back radially inwards relative to the external edges of the bipolar half-plates and the external edges of the frame the membrane-electrode assembly, so that it is actually possible to use this peripheral external zone Z _ex t to place the first orifices 320 arranged through the first half-frame 32 and the solid portions 42A of the first bipolar half-plate 42, and/or the second orifices 340 arranged through the second half-frame 34 and the solid portions 44A of the second bipolar half-plate 44. Note that it is possible to provide that the contour of the peripheral seals 50 can be adapted, to locally present a detour towards the interior, in order to increase the peripheral external surface Z _ext available around the first orifices 320 and/or second orifices 340.

Furthermore, on each side of the frame 30, the opening seals 51 delimit, in combination with the corresponding peripheral seal 50 and around the openings 36, 46, gallery framing zones Z _eg . Six gallery framing zones Z _eg are therefore visible in Figure 6. Each of the gallery framing zones Z _eg is fluidically isolated from the anodic, cathodic and cooling fluid compartments. Each of the gallery framing zones Z _eg can also accommodate at least some of the first orifices 320, arranged through the first half-frame 32 facing a solid portion 42A of the first bipolar half-plate 42, and/or at least some of the second orifices 340, arranged through the second half-frame 34 facing a solid portion 44A of the second bipolar half-plate 44. Note, however, that each gallery framing zone Z _eg is capable of be fluidly connected with the gallery it surrounds.

Such zones can also be defined in the first and second embodiments, even if they are not formally identified in Figures 1 to 6. In Figures 6 and 7, the presence of the bonding zones Z2, Z4 is illustrated, which correspond respectively to the position of the first orifices 320 and the second orifices 340, along the longitudinal edges of the subassembly 6, at the height of the active zone corresponding to the presence of the CCM membrane 25. However, these bonding zones Z2, Z4 could be, as in the example of Figure 3, located near the longitudinal ends of the subassembly 6, for example longitudinally at the height of the openings 36, 46 of the subassembly 6, or even beyond the openings 36, 46 of the subassembly 6 in the longitudinal direction starting from the center of the subassembly 6. Alternatively, and as envisaged above, these zones Z2, Z4 collage can be located in one or other of the gallery framing zones Z _eg .

More precisely, it is particularly advantageous, as illustrated in Figure 3, to provide at least four first orifices 320 and, where appropriate, at least four second orifices 340, each located at one of the four corners of the membrane assembly. electrode, a corner being defined as being a portion of the electrode membrane assembly which is included in the peripheral external zone Z _ext and which is:

- longitudinally at the height of the openings 36 of the frame 36 forming reactive or cooling fluid galleries of the subassembly 6, or beyond these openings 36, 46 in the longitudinal direction starting from the center of the subassembly 6;

- and/or transversely at the height of that of the openings 36 of the frame 36, forming a reactive or cooling fluid gallery of the subassembly 6, which is the closest transversely to the longitudinal edge considered, or beyond this opening 36 according to the transverse direction starting from the center of the subassembly 6.

In Figure 7, but also in Figure 4, it is illustrated that it is advantageous to provide that the solid portion 42A of the first half-bipolar plate 42, which faces a first orifice 320 of the first half-plate frame 32, and/or the solid portion 44A of the second bipolar half-plate 44, which faces a second orifice 340 of the second half-frame 34, is folded down to be arranged, along the axis A30, at a position equal to the position of the median plane TT30 of the frame 30 along the axis A30, or close to it, this in order to minimize the deformation of the frame along the axis A30 at the location of the junction of the frame 30 with the corresponding half-bipolar plate 42. This position can be exactly that of the median plane TT30 of the frame 30 along the axis A30, or be offset from that of the median plane TT30 of the frame 30 by a value less than or equal to the thickness of the frame 30 along the axis A30 , ideally offset from that of the median plane TT30 of the frame 30 by a value equal to the thickness, along the axis A30, of the half-frame 32, 34 in which the orifice 320, 340 is formed. In the example of Figures 6 and 7, the bipolar half-plates 42, 44 have reliefs along the axis A30, these reliefs corresponding to the bottoms of reactive fluid circulation channels, to separation teeth between two channels, to bearing surfaces for seals 50, 51. These reliefs can be separated from the median plane TT30 of the frame 30 along the axis A30. We see, however, that, just as in the example of Figure 4, the first bipolar half-plate 42 is formed in such a way that the solid portion 42A facing a first orifice 320 is arranged in a position which, according to the axis A30, is offset from that of the median plane TT30 of the frame 30 by a value equal to the thickness, along the axis A30, of the half-frame 32 in which the first orifice 320 is formed.

Thus, in the case of a bipolar half-plate formed from a stamped metal sheet, the solid portion 42A of the first bipolar half-plate 42, which faces a first orifice 320 of the first half-frame 32, may correspond to a stamped shape of the sheet forming the first bipolar half-plate 42 and/or the solid portion 44A of the second bipolar half-plate 44, which faces a second orifice 340 of the second half-frame 34, may correspond to a stamped shape of the sheet forming the second bipolar half-plate 44.

In the embodiment of Figure 8, the opening seals 51 are separated from the peripheral seals 50 and therefore have a closed contour ensuring in themselves the sealing function, for each anodic, cathodic or fluid compartment. cooling, between the compartment concerned and at least those of the openings 36 and 46 which do not communicate with this given compartment. In the embodiment of Figure 8, the opening seals 51 each alone delimit a gallery framing zone Z _eg and portions of the internal zone are located between two gallery framing zones Z _eg , as represented by the cross-hatched areas arranged between two opening seals 51 in Figure 8.

Also in this embodiment, the first and second orifices 320 and 340 are preferably provided in the peripheral external zone Z _ext of the subassembly 6.

According to a variant not shown of the fourth embodiment, some or all of the bonding zones Z2, Z4 can be provided in one or more gallery framing zone(s) Z _eg ..

According to another variant not shown of the invention, applicable to all embodiments, only one of the first orifices 320 or only some of them is/are provided in the peripheral external zone Z _ext or in one or more of them. gallery framing zone(s) Z _eg . Likewise, it can be provided that only one of the second orifices 340 or only some of them is/are provided in the peripheral external zone Z _e xt or in one or more gallery framing zone(s) Z _eg .

Whatever the embodiment, in the stack, such as the stack 60 shown in Figure 7, at least one electrochemical cell 6 conforms to the invention. Preferably, for the sake of homogeneity, all the electrochemical cells 6 conform to the invention.

According to a not shown variant of the invention, applicable to all embodiments, the subassembly 6 comprises a first half-polar plate 42 on one side only and this is joined to a second half-polar plate 44 to form a preassembled polar plate 4, before joining the frame 30 and the half-polar plate 42, with the bonding technique using, for example, the first orifices 320. In this case, the subassembly 6 is a multilayer structure which is not symmetrical with respect to the plane TT30, since the two joined polar half-plates are located on the side of the half-frame 32. This subassembly 6 can be integrated into a stack of the type of stack 60 shown in Figure 7, in one operation because it can be handled individually by an operator or a robot. Each sub-assembly 6 then constitutes a part of an electrochemical cell, since it must be associated with the second bipolar half-plate 44 itself forming part of another pre-assembled bipolar plate 4 of an adjacent sub-assembly to constitute a cell complete. In this case, only the first orifices 320 are provided through the first half-frame 32, without the need to provide second orifices through the second half-frame 34, only the component of the fifth step represented in the upper part of the Figure 4, or a component symmetrical to that shown in Figure 6, is implemented and the glue can only be coated on the first surface S34 of the second half-frame 34. This embodiment does not make it possible to test or to pre-activate a cell before the stack is formed.

The invention is shown in the figures in the case where the membrane 25 is of the CCM type, the catalytic layers 23, 24 being carried by the base membrane 22. It is also applicable to the case where the catalytic layers 23, 24 are carried by the diffusion layers 28 and 29, according to CCB technology, from the English “Catalyst Coated Baking” or even in the case of a mixed assembly, with one among the catalytic layers 23, 24 which is carried by the base membrane 22, and the other among the catalytic layers 23, 24 which carried by the corresponding diffusion layer 28 or 29.

Alternatively, the subassembly 6 does not include the diffusion layers 28 and 29, which can also be omitted, and/or replaced by structures integrated into the bipolar plates 4. Whatever the embodiment or variant considered, the quantity of glue Q2 or Q4 present in an orifice 320 or 340 does not necessarily fill the entire volume of this orifice.

In the embodiments mentioned above, the orifices 320 and 340 have the same geometry, as shown in the figures. In a variant not shown, one or more of the orifices of a half-frame has a geometry different from that of the other orifices of this half-frame and/or one or more of the orifices of a half-frame has a geometry different from that one or more holes in the other half-frame.

The embodiments and variants considered above can be combined to generate new embodiments of the invention.

Claims

1. Subassembly (6) for fuel cell stack (8) comprising

- a membrane-electrode assembly (2) including o a membrane (22, 25) o a bipartite frame (30) formed by

■ a first half-frame (32) arranged on a first side of the membrane;

■ a second half-frame (34) arranged on a second side of the membrane;

- and at least a first bipolar half-plate (42), in which at least the second half-frame (34) is coated, on a first surface (S34) facing a first surface (S32) of the first half- frame (32), a layer of glue for securing the half-frames, characterized in that

- first orifices (320) arranged through the first half-frame (32) are each arranged facing a solid portion (42A) of the first bipolar half-plate (42) and facing a solid portion ( 34A) of the second half-frame (34), in a direction (A30) perpendicular to a main plane of the membrane (TT22); And

- the first bipolar half-plate (42) is secured to the frame (30) by a quantity (Q2) of glue which extends through the first orifices (320) and which comes from the glue coated on the first surface (S34 ) of the second half-frame (34).

2. Subassembly for fuel cell stack according to claim 1, characterized in that

- it comprises a second bipolar half-plate (44) arranged, relative to the membrane (22, 25), opposite the first bipolar plate (4A); the first half-frame (32) is coated, on its first surface (S32), with a layer of glue for joining the half-frames (32, 34);

- second orifices (340) arranged through the second half-frame (34) are each arranged facing a solid portion (44A) of the second bipolar half-plate (44) and facing a solid portion (32A) ) of the first half-frame (32), in the direction (A30) perpendicular to a main plane of the membrane (TT22); And - the second bipolar plate (44) is secured to the frame (30) by a quantity (Q4) of glue which extends through the second orifices (340) and which comes from the glue coated on the first surface (S32) of the first half-frame (34).

3. Subassembly for fuel cell stack according to claim 2, characterized in that the first and second orifices (320, 340) are offset (A24) relative to each other in at least one direction parallel to the main plane (TT22) of the membrane (22, 25), so that there is no superposition between these orifices in the direction (A30) perpendicular to the main plane of the membrane.

4. Subassembly for fuel cell stack according to one of claims 2 and 3, characterized in that the first bipolar half-plate (42) is provided with cutouts (48) aligned with the second orifices (340) and /or in that the second bipolar half-plate (44) is provided with cutouts (49) aligned with the first orifices (320), in the direction (A30) perpendicular to the main plane of the membrane.

5. Subassembly for fuel cell stack according to claim 4, characterized in that a cutout (48, 49) opens onto at least one longitudinal edge of the bipolar plate in which it is formed.

6. Sub-assembly for fuel cell stack according to one of the preceding claims, characterized in that each orifice (320, 340) arranged through a half-frame (32, 34) has a section whose area is greater than or equal to 5 mm ² , preferably 10 mm ² , with a preferably circular, rectangular or oblong shape.

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

8. Subassembly for fuel cell stack according to one of the preceding claims, characterized in that at least one of the first orifices (320) arranged through the first half-frame (32) is arranged in a zone external peripheral seal (Z _ext ) of the sub-assembly (6) which is located outwards relative to a peripheral seal (50) of the sub-assembly (6).

9. Sub-assembly for fuel cell stack according to one of the preceding claims, characterized in that the membrane electrode assembly (2) has four corners, and in that the sub-assembly (6) has at least four first orifices (320) arranged through the first half-frame (32) and arranged in a peripheral external zone (Z _ext ) of the subassembly (6) which is located towards the outside relative to a peripheral seal (50) of the subassembly (6), each in a corner of the membrane electrode assembly.

10. Subassembly for fuel cell stack according to one of the preceding claims, characterized in that at least one of the first orifices (320) provided through the first half-frame (32) and the solid portion ( 42A) facing the first bipolar half-plate (42) are arranged in a gallery framing zone (Z _eg ), arranged around an opening 46 of the first bipolar half-plate (42), and isolated fluidically of at least one anodic or cathodic fluid compartment delimited in the subassembly, between the electrode membrane assembly (2) and the first bipolar half-plate (42).

11. Fuel cell (8) comprising a stack (60) of electrochemical cells, each with 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 one of the preceding claims.

12. Method for manufacturing a subassembly (6) comprising

■ a first half-frame (32) arranged on a first side of the membrane

■ a second half-frame (34) arranged on a second side of the membrane

- and at least one first bipolar half-plate (42), this process comprising at least one preliminary step of coating at least one first surface (S34) of the second half-frame (34) with an adhesive; And

- a step of joining the frame (30) and the membrane (22, 25) by applying the first surface (S34) of the second half-frame, coated with glue, against the first surface (S32) of the first half-frame (32); this method being characterized in that it comprises at least one step of applying the first bipolar half-plate (42) against a second surface (S'32) of the first half-frame (32) opposite the first surface ( S32) of this first half-frame;

- a step of joining the first bipolar half-plate (42) and the frame (30) by migration of the glue coated on the first surface (S34) of the second half-frame (34), towards a surface (S42) of the first bipolar half-plate, to through first orifices (320) arranged in the first half-frame (32), between its first and second surfaces (S32, S'32).

13. Method according to claim 12, characterized in that the subassembly comprises a second bipolar half-plate (44) and in that the method comprises at least one preliminary step of coating at least one first surface (S32 ) of the first half-frame (32) with glue; a step of applying the second bipolar half-plate (44) against a second surface (S’34) of the second half-frame (34) opposite the first surface (S34) of this second half-frame;

- a step of joining the second bipolar half-plate (44) and the frame (30) by migration of the glue coated on the first surface (S32) of the first half-frame (32), towards a surface (S44) of the second bipolar half-plate, through first orifices (340) provided in the second half-frame, between its first and second surfaces (S34, S'34).

14. Method according to one of claims 12 or 13, characterized in that, during the joining step, the glue coated on the first surface (S34) of the second half-frame (34), and possibly on the first surface (S32) of the first half-frame (32), is heated at least in the vicinity of the first orifices (320), and possibly at the level of the second orifices (340).