FR3143880A1 - Fuel cell and its manufacturing process - Google Patents

Abstract

Fuel cell and its manufacturing method Fuel cell (1), comprising: stacked plates (10, 30, 50, 70), each plate comprising a respective exchange edge to form an exchange face (5); an external collector, fluidly connected to the exchange face; and a collector seal (90), framing the exchange face (5) to ensure tightness of the fluid connection. So that the collector gasket has a better controlled shape and is easier to apply, each plate includes a respective centering notch, adjacent to the exchange edge, to form a centering groove (6) bordering the exchange face. The collector seal comprises a longitudinal seal portion (91) formed in the centering groove and ensuring the sealing of the fluid connection. Figure for abstract: Figure 2

Description

Fuel cell and its manufacturing process

The present invention relates to a fuel cell and a method for manufacturing such a fuel cell.

US2001055708A1 describes a fuel cell comprising a horizontal stack of electrochemical cell components, including in particular anodic and cathode fluid field plates, anodic and cathode supports, anodic and cathode catalysts, and proton exchange membranes. The stack is supplied with reactive gas, such as oxygen or hydrogen, by a collector, positioned on top of the stack. A sealing system is interposed between the collector and the stack. While the edges of the components are in irregular positions, that is to say protruding or recessed relative to each other, the sealing system comprises a first part forming bridges of crosslinked silicone at low temperature, which follows the shape of the protruding and recessed edges, to form a flat and regular surface. The sealing system comprises a second part, formed by a layer of foamed silicone, which is interposed between the flat and regular surface of the first part and the lower surface of the collector, extending over the entire perimeter of the collector.

However, in practice, the need to use low viscosity silicone so that the silicone can perfectly match the irregularities of the stack and form bridges may imply that the silicone spreads in width, so that the joint thus formed, although relatively flat on the surface, is generally relatively spread out in width and of imprecise shape. Spreading the joint widthwise is likely to accidentally block part of the exchange face between the stack and the collector, thus reducing the efficiency of the fuel cell.

The invention aims to resolve the drawbacks of the prior art, by proposing a new fuel cell whose collector seal has a better controlled shape in which the application of the collector seal is facilitated.

The subject of the invention is a fuel cell, comprising:

- a stack, comprising plates, the plates of the stack comprising flow field plates and membrane-electrode plates and being stacked in a stacking direction to constitute electrochemical cells, each plate being oriented perpendicular to the direction of stacking by being arranged flat against the adjacent plate, each plate comprising a respective exchange edge, the exchange edges being parallel to each other and together forming an exchange face belonging to the stack, the face of the exchange extending parallel to the stacking direction;

- an external collector, which is fluidly connected to the stack by being attached against the stack so as to cover the exchange face, for an exchange of an operational fluid between the external collector and the stack via of the exchange face; And

- a collector seal, which frames the exchange face and which is interposed between the stack and the external collector, to ensure tightness of the fluid connection between the external collector and the stack.

According to the invention:

- each plate comprises a respective centering notch, adjacent to the exchange edge, the centering notches together forming a centering groove belonging to the stack, the centering groove bordering the exchange face and extending parallel to the stacking direction; And

- the collector seal comprises a longitudinal seal portion, which is parallel to the stacking direction, which is formed in the centering groove, so that the longitudinal seal portion is interposed between the stack and the outer collector for ensure the tightness of the fluid connection between the external collector and the stack.

An idea underlying the invention is to provide for forming the collector seal in the centering groove, so that the collector seal, received inside the centering groove, has a low tendency to overflow laterally. during its formation, in particular, even if the material used to form the collector seal has a very low viscosity. The shape of the collector joint being well controlled, it is easier to form a joint which fits the centering notches of the plates, even if certain notches are recessed or project from each other. Sealing against the operating fluid is therefore easier to ensure.

Another advantage is that certain centering notches can be used to ensure centering of the plate during the manufacture of the stack. In other words, during the stacking of the plates to form the stack and while the collector joint is not yet formed, a centering rail can be temporarily installed which cooperates mechanically with certain centering notches and thus serves as a template to ensure that the corresponding plates are correctly positioned, transversely to the stacking direction. The centering rail is oriented parallel to the stacking direction. When stacked, at least certain plates, whose centering notch cooperates mechanically with the rail, are guided to slide in the stacking direction along the centering rail. For other plates, the rail can pass through the centering notch following the stacking direction. Once the stacking of the plates is complete, the centering rail is removed, so that the centering notches are left free for the formation of the collector seal within them. The centering notches therefore combine both the function of centering the plates and receiving the longitudinal joint portion.

Preferably, at least one of the flow field plates forms exchange orifices, formed at the exchange edge of the flow field plate, to open onto the surface of the exchange face and be covered by the external collector, the exchange of operational fluid between the external collector and the stack being carried out via the exchange orifices.

Preferably, the plates of the stack comprise a respective secondary edge, parallel to the exchange edge and being connected to the exchange edge by the centering notch.

Preferably, for at least one of the plates of the stack, the exchange edge projects towards the outside of the stack relative to the secondary edge.

Preferably, for at least one of the membrane-electrode plates, the secondary edge of the membrane-electrode plate projects towards the outside of the stack, relative to the secondary edge of the adjacent flow field plates.

Preferably, the flow field plates include primary flow field plates and secondary flow field plates. Preferably, at least one of the primary flow field plates is adjacent to one of the secondary flow field plates to form, with said secondary flow field plate, a bipolar plate. Preferably, for at least one of the bipolar plates, the exchange edge of the primary flow field plate and the exchange edge of the secondary flow field plate are flush with each other. Preferably, for at least one of the bipolar plates, the centering notch of the primary flow field plate is set back towards the inside of the stack relative to the centering notch of the plate. secondary flow field.

Preferably, the centering notch of at least one of the membrane-electrode plates is flush with or set back towards the inside of the stack, relative to the centering notch of the field plate. adjacent secondary flow, and projecting towards the outside of the stack, relative to the centering notch of the adjacent primary flow field plate.

Preferably, for at least one of the membrane-electrode plates, the exchange edge of the membrane-electrode plate projects towards the outside of the stack, relative to the exchange edge of the field plates d adjacent flow.

Preferably, the stack further comprises peripheral seals, each peripheral seal being interposed between one of the flow field plates and one of the membrane-electrode plates in the stacking direction. Preferably, each peripheral joint comprises: an exchange edge portion, which is interposed between the exchange edge of the flow field plate and the exchange edge of the membrane-electrode plate in the direction of stack, being flush with the exchange edge of said flow field plate or set back towards the inside of the stack relative to the exchange edge of said flow field plate; and a recessed portion, which is interposed between the centering notch of the flow field plate and the centering notch of the membrane-electrode plate in the stacking direction, the recessed portion being recessed towards inside the stack relative to the centering notch of the membrane-electrode plate and being flush with or set back towards the inside of the stack relative to the centering notch of the field plate d 'flow.

Preferably, for at least one of the plates of the stack, the centering notch has a profile in the shape of an arc of a circle, projected in a projection plane which is orthogonal to the stacking direction.

Preferably, the plates of the stack comprise an end plate, terminating the stack in the stacking direction.

Preferably, a transverse groove is provided in the exchange edge of the end plate, the transverse groove being connected to the centering groove by opening into the centering notch of the end plate. Preferably, the collector joint comprises a transverse joint portion, which is perpendicular to the stacking direction, which is formed in the transverse groove and which is joined to the longitudinal joint portion, so that the transverse joint portion is interposed between the end plate and the outer collector to ensure fluid tightness of the fluid connection between the outer collector and the stack.

The invention also relates to a method for manufacturing the fuel cell as defined above. The process includes:

- while the plates of the stack are not yet stacked and the collector joint is not yet formed, installation of a centering rail, which is parallel to the stacking direction and which is capable of being received in the respective centering notch of the plates;

- successive stacking of the plates to form the stack while the centering rail is installed, by guiding the plates by mechanical cooperation of at least one of the centering notches with the centering rail, so that the centering rail ensures centering of the plates transversely in relation to the stacking direction;

- removal of the centering rail, once the stacking is completed, by moving the centering rail away from the stacking, transversely to the stacking direction;

- installation of the collector seal, with the longitudinal seal portion formed in the centering groove, once the stacking has been completed and the centering rail has been removed; And

- fluid connection of the external collector to the stack, once the collector seal has been put in place, by bringing the external collector against the stack so as to cover the exchange face, with the interposition of the collector seal, including the longitudinal joint portion, between the stack and the outer collector, to ensure the sealing of the fluid connection between the outer collector and the stack.

Preferably, the installation of the centering rail comprises fixing the centering rail on a support plate belonging to the fuel cell. Preferably, the successive stacking of the plates comprises the stacking of one of the plates against the support plate parallel to the stacking direction. Preferably, removal of the centering rail includes separating the centering rail from the backing plate.

Preferably, installing the collector gasket includes:

- application of a first bead, made of elastomer in a non-crosslinked state, in the centering groove, to form the longitudinal joint portion; And

- in-situ crosslinking of the non-crosslinked elastomer of the first bead, while the first bead has been applied.

Preferably, the installation of the collector joint further comprises, once the first bead has been applied: application of a second bead, made of elastomer in a non-crosslinked state on the first bead, so that the second bead bead is projecting towards the outside of the stack, relative to the exchange face, the elastomer of the second bead having a higher viscosity, at the moment when the second bead is applied, than the viscosity of the elastomer of the first bead, when the first bead is applied.

The invention and other advantages thereof will appear in the light of the following description of embodiments conforming to its principle, made with reference to the appended figures in which:

There shows a perspective view of a fuel cell according to one embodiment of the invention.

There is a view similar to the , where an external collector was removed.

There is a view similar to the , where the outer manifold and a manifold gasket were removed.

There is a perspective view, from another angle, in this case from a low angle, showing a detail of the .

There is a top view of part of a stack belonging to the fuel cell of Figures 1 to 4.

There is a view similar to that of the , where the manifold gasket is additionally shown.

There is a perspective view similar to the , showing a fuel cell manufacturing step.

There is a perspective view similar to the , showing another stage of fuel cell manufacturing.

There is a perspective view similar to the , showing another stage of fuel cell manufacturing.

Figures 1 to 3 show a fuel cell 1 according to one embodiment of the invention. The fuel cell 1 comprises a stack 2, shown in more detail in Figures 4 to 6. The stack 2 comprises primary flow field plates 10, secondary flow field plates 30, membrane plates- electrode 50 and, preferably, end plates 70 and peripheral joints 80. The battery 1 also includes an external collector 100, visible on the , and a collector seal 90, visible in Figures 2 and 6. The stack 1 also advantageously comprises a compression system visible in Figures 1 to 3, comprising for example support plates 111 and 112, tie rods 113 and springs 114.

For the manufacture of the stack 1, and in particular the centering of the different plates 10, 30, 50 and 70, a peripheral centering template 130 shown in Figures 7 to 9, including centering rails 131, is used, which is at least in part removed once stack 2 is completed.

A stacking direction Z2 is defined, according to which the plates 10, 30, 50 and 70 as well as the joints 80 are stacked to constitute the stack 2. The direction Z2 is perpendicular to the plates 10, 30, 50 and 70 and fixed compared to stack 2.

As shown in Figures 1 to 3, the support plates 111 and 112 are arranged on either side of the stack 2 in the direction Z2. The springs 114 are interposed, in the direction Z2, between the stack 2 and the support plate 112. The support plate 111 comes to bear against the stack in the direction Z2. The stack 2 comes to bear against the springs 114, which are distributed over the surface of the support plate 112. The springs 114, interposed between the support plate 112 and the stack 2, come to bear against the plate 112 following direction Z2. The tie rods 113, which are each parallel to the direction Z2, are distributed around the stack 2, connecting the support plates 111 and 112 together, so as to maintain them in position relative to each other. other in the direction Z2 and thus maintain the stack 2 in compression in the direction Z2 under the action of the springs 114. The springs 114 advantageously allow dimensional variations of the stack 2 in the direction Z2, which can occur during the use of the battery, particularly under the effect of thermal stress. In the present example, six tie rods 113 and eight springs 114 are provided, however a different number of these elements can be provided. Alternatively, another type of compression system can be provided. For example, the compression system could, alternatively, comprise support plates, on either side of the stack, the entire stack and the support plates being received in a casing, and springs being interposed between one face of the casing and at least one of the support plates to compress the stack. The principle of such an alternative compression system is for example described in document WO2007/080472. Other compression systems are described in document US20090162728 or, without springs, in document US20100261088, or even in document EP1597786.

Each plate 10, 30, 50 and 70 is of planar shape, following a respective plane, perpendicular to the direction Z2. The plates 10, 30, 50 and 70 are parallel to each other and to the plates 111 and 112. As better visible in Figures 3 and 4, each plate 10, 30, 50 or 70 is arranged flat against the adjacent plate, it i.e. against the immediately following plate. Being thus arranged flat, the plate 10, 30, 50 or 70 is superimposed, edge to edge, with the adjacent plate, possibly with the interposition of one of the joints 80 between the two adjacent plates. More precisely, each peripheral seal 80 is interposed between one of the membrane-electrode plates 50, and one of the flow field plates 10 or 30. Each peripheral seal 80 extends flat between the plates concerned, according to a plane perpendicular to the stacking direction Z2. In the example illustrated, the adjacent flow field plates 10 and 30 are superimposed without the interposition of a peripheral seal 80 between them.

The different plates of stack 2 are arranged in a precise order following the stacking direction Z2, to form groups of adjacent plates, each group of adjacent plates forming a respective electrochemical cell. Each electrochemical cell of the stack 2 comprises, in this order following the direction Z2, a secondary flow field plate 30, a possible peripheral seal 80, a membrane-electrode plate 50, another possible peripheral seal 80, and a primary flow field plate 10. For the operation of the electrochemical cells, the stack 2 is designed to be supplied with operational fluids, including a cathodic reactive fluid, comprising for example dihydrogen, an anodic reactive fluid, comprising for example oxygen possibly contained in air, as well as, if necessary, a cooling fluid. Within each electrochemical cell, the cathodic reactive fluid reacts with the anodic reactive fluid to produce electricity. The cooling fluid is used to cool stack 2. It is also planned to evacuate these operational fluids and/or the products resulting from the reaction of these operational fluids after their passage into stack 2.

In the present example, for the sake of simplification, only nine electrochemical cells have been represented. However, in practice, the fuel cell 1 may have a higher number of cells, for example between fifty and five hundred.

Each plate 10, 30, 50 and 70 has an external perimeter 3, which extends along a plane orthogonal to the direction Z2. Each plate 10, 30, 50 and 70 extends exclusively within its outer perimeter 3. Here each outer perimeter 3 is of generally rectangular shape. It is advantageously provided that the outer perimeter 3 of each plate of the same type of the stack 2 is of the same shape, or of similar shape, and is superimposed in the stacking direction Z2 with the outer perimeter 3 of all the other plates of the stack. same type, that is to say with alignment following direction Z2. For example, all the membrane-electrode plates 50 have an identical outer perimeter 3 and superimposed along the stacking direction Z2 with the outer perimeter 3 of the other membrane-electrode plates 50. For example, all the primary flow field plates 10 have an identical outer perimeter 3 and superimposed along the stacking direction Z2 with the outer perimeter 3 of the other primary flow field plates 10, the perimeter 3 of the plates 10 being able to be different from that of the plates 50, and so following. It is envisaged in particular that the outer perimeter 3 of plates of a first type is, for all or part, set back towards the inside of the stack 2 or projects towards the outside of the stack 2, relative to the perimeter exterior of plates of another type. For example, it is expected that the outer perimeter 3 of the membrane-electrode plates 50 projects outwards from the stack 2 in relation to the outer perimeter 3 of the flow field plates 10.

The union of the exterior perimeters 3 of all the plates 10, 30, 50 and 70 of the stack forms different sides 4 of the stack 2, parallel to the direction Z2, here four sides 4, since the exterior perimeters 3 of the plates the stack 2 has a generally rectangular shape. Certain parts of the outer perimeter 3 of the plates 10, 30, 50 and 70 being recessed or overhanging, the sides 4 are irregular, the recessed perimeters 3 forming transverse furrows, perpendicular to the stacking direction Z2, the perimeters 3 overhanging forming ridges, perpendicular to the stacking direction Z2 and parallel to the furrows.

As better visible in Figures 2 and 3, at least one of the sides 4 of the stack 2 forms at least one exchange face 5, at least one centering groove 6 and at least one secondary face 7. For example , at least one of the sides 4 of the stack 2 forms a single exchange face 5, two centering grooves 6 and two secondary faces 7. The present description and the drawings show only one of the sides 4 of the stack 2 provided with such elements. However, it is preferentially provided that one or more other sides 4 comprise such elements, or at least comprise centering grooves 6. Typically, two opposite sides 4 of the stack 2 will be provided with such elements, to form an entrance and an output for the same given operational fluid. It is also possible to provide, in one side 4, two exchange faces 5 arranged side by side in the tangential direction of said face which is perpendicular to the stacking direction Z2, with in this case, for example, three or four grooves centering 6 and two or three secondary faces 7.

In addition to said at least one exchange face 5, the stack may comprise, in known manner, one or more internal galleries, or internal collectors, each internal gallery being formed of superimposed orifices arranged in the stack of plates, for the circulation and distribution of one or more other operational fluids.

For each exchange face 5, a normal direction Y2 is defined, perpendicular to the face 5 and to the direction Z2 and directed towards the outside of the stack 2, and a tangential direction X2, parallel to the exchange face 5 and perpendicular to the direction Z2.

Preferably, the exchange face 5, the grooves 6 and the secondary faces 7 extend from one end to the other of the stack 2 in the direction Z2, and are parallel to the direction Z2.

Each centering groove 6 extends parallel to the direction Z2, is hollowed out in the stack 2, so as to be open in the normal direction Y2. The exchange face 5 is arranged between the two grooves 6, being delimited by the grooves 6 in the tangential direction X2. Each groove 6 is arranged between the exchange face 5 and one of the secondary faces 7. Along the tangential direction X2, the secondary face 7 is preferably delimited by the groove 6 and extends for example to one end of the side 4. Preferably, the exchange face 5 and the secondary face(s) 7 are parallel to each other and parallel to the tangential direction X2.

On the same side 4 as that carrying the exchange face 5, the stack also preferably comprises one or more transverse grooves 8, here two transverse grooves 8. Each transverse groove 8 is formed hollow in the stack 2, so as to to be opened in the normal direction Y2. Each transverse groove 8 connects the two centering grooves 6 together. For this, each transverse groove 8 preferably extends perpendicular to the direction Z2, in particular parallel to the direction X2. The exchange face 5 is arranged between the two grooves 8, being delimited by the grooves 8 in the stacking direction Z2. Together, grooves 6 and 8 frame the exchange face 5 according to a closed contour.

As visible on the , the collector seal 90 is preferably integral with the stack 2, while the collector 100 is attached to the stack 2, coming to rest against the seal 90, as shown in the .

The collector seal 90 frames the exchange face 5. For this, the collector seal 90 comprises two longitudinal seal portions 91 and two transverse seal portions 92. Each longitudinal seal portion 91, also visible in section on the , extends parallel to the stacking direction Z2. The portions 91 are arranged on either side of the face 5 in the direction X2, each being formed in one of the grooves 6, over the entire height of the face 5 in the direction Z2. Each transverse joint portion 92 connects the two longitudinal joint portions 91 together, extending, for example, parallel to the tangential direction X2. Portions 92 are joined to portions 91 at each end of portions 92. Then, portions 92 are arranged on either side of face 5 in direction Z2. Overall, the collector seal 90 has a quadrilateral shape, or, at least, has a closed contour around face 5.

Preferably, each longitudinal joint portion 91 completely fills the section of the groove 6 which it occupies, on a portion of the groove 6 which runs along the face 5, the portion 91 matching the shape of the bottom of the groove 6. Likewise , preferably, each transverse joint portion 92 completely fills the section of the groove 8 which it occupies, on a portion of the groove 8 which runs along the face 5, the portion 92 conforming to the shape of the bottom of the groove 8. As visible on the , in the direction Y2, the seal 90 projects slightly to ensure tight contact with the collector 100. In particular, the longitudinal seal portions 91 project slightly in the direction Y2 outside the grooves 6. In particular, the portions transverse seals 92 project slightly in direction Y2, outside the grooves 8.

The exchange face 5 is configured to allow an exchange of at least one operational fluid, preferably a single operational fluid, with the external collector 100. To this end, the external collector 100 is fluidically connected to the stack 2, being in particular connected with the exchange face 5, preferably exclusively with the face 5. To be fluidly connected to the stack 2, the collector 100 is attached against the stack 2 so as to cover the face d 'exchange 5, as shown on the . To ensure the tightness of this fluid connection, the seal 90 is interposed between the collector 100 and the stack 2, in direction Y2.

By “exchange”, we mean either an admission of operational fluid within the stack 2 via the exchange face 5, the operational fluid then being supplied by the external collector 100, or an evacuation of operational fluid from the interior of the stack 2 via the exchange face 5, the operational fluid then being collected by the external collector 100. At the level of face 5, the exchange of operational fluid is carried out parallel to the normal direction Y2.

In practice, as shown in the , the collector 100 comprises a connector 101, which has for example a funnel shape, a first flared opening of which covers face 5 to be fluidly connected thereto, and a second, narrower opening of which is connected to a pipe arrival or evacuation of operational fluid. The first opening connected to the exchange face 5 is delimited by a closed contour edge belonging to the connector 101, which extends in the plane X2, Z2 perpendicular to the normal direction Y2, and which is advantageously of complementary shape to that grooves 6 and 8. To ensure the tightness of the connection, this closed contour belonging to the collector comes into contact with the seal 90 all around the face 5, in particular in contact with the longitudinal seal portions 91 and transverse 92 of the seal 90. The collector seal 90 is preferably made of elastomer, for example silicone, which is slightly elastic in order to be able to fit the collector 100 and thus ensure sealing. The edge with a closed contour which delimits the first opening of the connector 101 therefore has a bearing face which comes into tight support, over the entire closed contour, on the seal 90 which therefore extends over an identical contour. The bearing face of the edge with a closed contour which delimits the first opening of the connector 101 can be a flat surface extending in the plane X2, Z2 perpendicular to the normal direction Y2, therefore having the shape of a strip following the contour farm. This support surface may have one or more ribs in relief relative to the plane X2, Z2 perpendicular to the normal direction Y2, preferably one or more ribs in relief following said contour, parallel to each other along the contour if there are several . Such ribs extending over the contour can thus be indented into the material of the seal 90, over the entire closed contour, to increase the reliability of the sealing of the contact between the connector 101 and the seal 90.

The collector 100 can also, preferably, comprise a fixing system 102, which is integral with the connector 101 and via which the collector 100 can be fixed to the battery 1 and/or to the stack 2. Here, the fixing system 102 is designed to be fixed to the pile 1 by being fixed to the plates 111 and 112. Preferably, the fixing system 102 comprises a base 103, via which the fixing system is fixed to an edge fixing edge 115, belonging to the plate 111. Preferably, the base 103 is attached against the fixing edge 115 parallel to the normal direction Y2, the fixing edge 115 being parallel and/or in the extension of the face of exchange 5, following direction Z2.

Preferably, the fixing system 102 comprises a base 104, via which the fixing system is fixed to a fixing edge 116, belonging to the plate 112. Preferably, the base 104 is attached against the edge fixing edge 116 parallel to the normal direction Y2, the fixing edge 116 being parallel and/or in the extension of the exchange face 5, in the direction Z2. The connector 101 is held pressed in the opposite direction of the direction Y2 against the face 5 by the bases 103 and 104. Preferably, at least one of the bases 103 or 104 is authorized to move in the direction Z2 relative to the another base and/or in relation to the connector 101, to allow a dimensional variation of the stack 2 in the direction Z2 during use.

At least one of the bases of the fixing system as described above could be fixed to a fixing edge belonging to one or the other of the end plates 70 as described below.

Preferably, the stack 2 comprises exactly two end plates 70, which are provided at the ends of the stack 2, on either side, in the stacking direction Z2. In other words, each end plate 70 completes the stack in direction Z2. This does not exclude other plates bordering the stack 2 on either side by bordering the plates 70. The end plates 70 are designed to receive the forces applied to the stack 2 by the compression system. In the present example, the stack 2 is supported against the support plate 111 via one of these two end plates 70, in the opposite direction to the direction Z2 and the stack 2 is supported against the springs 114 via the other of these two end plates 70. Preferably, the end plates 70 are electrically insulating, comprise an electrically insulating coating, or comprise at least one portion, in contact with the stack, which is electrically insulating, taking into consideration the electrical currents in play within the stack 2. It can advantageously be provided that the plate 111 as well as the terminal plate 70 bearing against the support plate 111, are crossed, in the direction Z2 , by passages for operational fluid, to supply the stack 2 and/or to evacuate operational fluid from the stack 2. Thus, if additional connections for operational fluid can be made via the end plate 70, in addition to those carried out using the exchange face(s) 5 and the external collector(s) 100.

Preferably, each membrane-electrode plate 50 is constituted by a membrane-electrode assembly, and comprises, in certain embodiments, an outer frame, forming the outer perimeter 3 of the plate 50. The outer frame is preferably electrically insulating, in consideration of the electric currents in play within the stack 2. The electrode membrane plate 50 also includes a membrane, surrounded by the frame, allowing an exchange of protons from one face to the other of the plate 50. The membrane is covered, on one face, here the face directed in the direction Z2, by a layer of cathode catalyst, itself covered by a cathodic gas diffusion layer. The membrane is covered, on another face, here the face directed in the opposite direction to the Z2 direction, by a layer of anodic catalyst, itself covered by an anodic gas diffusion layer. The membrane of each plate 50 is the seat of electrochemical reactions involving the anodic reactive fluid, brought to the face carrying the anodic catalyst, and the cathode fluid, brought to the face carrying the cathode catalyst, producing a difference in electric potential on both sides. on the other hand from the membrane, and, ultimately, the electricity from the fuel cell. Alternatively, the outer perimeter 3 of the plate 50 is formed by the membrane itself, and the plate 50 has no frame.

Preferably, for the manufacture of the battery 1, each membrane-electrode plate 50 is preassembled before being added to the stack 2, that is to say that the aforementioned components of the plate 50 are already fixed to each other. to the others when adding plate 50 to stack 2.

Preferably, each flow field plate 10 and 30 is electrically conductive, taking into consideration the electrical currents in play within the stack 2. On one of its faces, each plate 10 and 30 forms a flow field, that is to say a plurality of channels crossing the stack 2, transversely with respect to the stacking direction Z2, to guide, within each channel, a circulation of operational fluid. The channels of the plates 10 and 30 are formed along the gas diffusion layer of the plate 50 adjacent to this plate 10 or 30, so that the operational fluid circulating in the channels is brought into contact with the gas diffusion layer and ensures the electrochemical reaction near the adjacent plate 50.

All the primary flow field plates 10 are dedicated to guiding the circulation of a first operational fluid, for example the cathodic reactive fluid, and have their channels facing the corresponding gas diffusion layer of the plate 50 which is adjacent to this plate 10. Here, it is the cathodic diffusion layer of said plate 50. In this sense, the primary flow field plates 10 can be described as polar plates, here cathodic. In the example, the channels of the primary flow field plates 10 face the plate 50, which is adjacent to the plate 10, in the opposite direction from the Z2 direction. For example, the channels of the primary flow field plate 10 are directed, generally, parallel to the direction Y2. By electrochemical reaction within the adjacent plate 50, each primary flow field plate 10, electrically conductive, is brought to a cathodic electric potential for the electrochemical cell considered. The peripheral seal 80, interposed between the plate 10 and the adjacent plate 50, ensures sealing between these two plates 10 and 50 to prevent the first operational fluid from escaping from the stack at the level of the external perimeters 3 of said plates 10 and 50. For this, the seal 80 advantageously forms a closed contour which extends along the perimeters 3, flush with or possibly slightly set back towards the inside relative to the perimeters 3.

All the secondary flow field plates 30 are dedicated to guiding the circulation of a second operational fluid, for example the anodic reactive fluid and have their channels facing the corresponding gas diffusion layer of another plate 50, which is adjacent to this plate 30. Here, it is the anodic diffusion layer of said plate 50. The plates 10 and 30, adjacent to each other, therefore separate two plates 50, to which they are respectively adjacent. The secondary flow field plates 30 can be described as polar plates, here anodic. In the example, the channels of the secondary flow field plates 30 face the plate 50, which is adjacent to the plate 30, in the direction Z2. In the example, the channels of plate 30 and are directed, generally, either parallel to direction Y2, or parallel to direction X2. By electrochemical reaction within the adjacent plate 50, each plate 30, electrically conductive, is brought to an anodic electric potential for the electrochemical cell considered. The peripheral seal 80, interposed between the plate 30 and the adjacent plate 50, ensures sealing between these two plates 30 and 50 to prevent the second operational fluid from escaping from the stack at the level of the outer perimeters 3 of said plates 30 and 50. For this, the seal 80 advantageously forms a closed contour which extends along the perimeters 3.

In other words, the channels of the flow field plates 10 and 30 of the same electrochemical cell are separated by one of the membrane-electrode plates 50, the channels of the flow field plates 10 and 30 facing this membrane-electrode plate 50 being surrounded by the peripheral seals 80. From one electrochemical cell to the adjacent electrochemical cell, the channels of the plate 10 of the first electrochemical cell turn their backs to the channels of the plate 30 of the second electrochemical cell . The adjacent flow field plates 10 and 30, belonging to two neighboring cells, together constitute a bipolar plate. By electrical conduction between these two adjacent plates 10 and 30, the two polar plates are at the same electric potential.

It can advantageously be provided that, between the adjacent flow field plates 10 and 30, that is to say, within the bipolar plate, another circulation field is formed by the plates 10 and 30. This other circulation field comprises channels, delimited by the plates 10 and 30, to conduct the circulation of a third operational fluid between the flow field plates 10 and 30, namely cooling fluid, and thus cool the stack 2 during its use.

In the present example, it is envisaged that the bipolar plates of the stack are constituted by two distinct plates 10 and 30 and placed one on top of the other. For example, each plate 10 and 30 is made up of a metal sheet, which forms the circulation fields preferably by stamping the sheet. Alternatively, all or part of the plates 10 or 30 can be formed by a machined plate, made of metal, graphite or other electrically conductive material. Preferably, for each bipolar plate, the two flow field plates 10 and 30 are preassembled, that is to say already fixed to one another before their addition to the stack 2. For example, the flow field plates 10 and 30 of the same bipolar plate are preassembled by being welded or brazed with each other.

Preferably, for the manufacture of stack 1, each joint 80 is preassembled with one of the plates 10, 30 or 50. Preferably, before addition to stack 2, each bipolar plate carries two joints 80, one formed on the plate 30 projecting in the direction Z2, the other formed on the plate 10 projecting in the opposite direction. Alternatively, it can be provided that each membrane-electrode plate 50 carries two seals 80, one formed projecting in the direction Z2 to be interposed between the plate 50 and the adjacent flow field plate 10, the other formed in projecting in the opposite direction to be interposed between the membrane-electrode plate 50 and the flow field plate 30 adjacent to the other side of the membrane-electrode plate 50. Preferably, each joint 80 is overmolded, cast or printed directly on the plate 10, 30 or 50 which carries it, which then facilitates assembly. However, the use of a free joint is possible.

Furthermore, it is possible to provide bonding of the plate 50 to one or the other of the flow field plates 10 and 30, or to the two flow field plates 10 and 30, for example by simple adhesive or double-sided bonding.

At their respective outer perimeter 3, each plate 10, 30, 50 and 70 has several edges, including at least one exchange edge and at least one secondary edge, and several centering notches, formed at the outer perimeter 3 of said plate . In other words, the exchange edge, the secondary edge and the centering notch belong to perimeter 3 of the plate concerned and constitute a part of it. The exchange edge is intended to be covered by the extent of the collector 100, therefore being inside the closed contour of the seal 90. The centering notch is intended to successively ensure a first function, namely ensuring the guiding and centering the plate 10, 30, 50 or 70 which carries it by cooperation with one of the rails 131, or at least being crossed by the rail 131, when adding said plate to the stack 2 , and a second function, namely housing the longitudinal seal portion 91 of the seal 90 once the stack 2 is completed, for sealing with the collector 100.

As shown in more detail on the , each primary flow field plate 10 comprises an exchange edge 11, two centering notches 12 and two secondary edges 13, each secondary flow field plate 30 comprises an exchange edge 31, two centering notches 32 and two secondary edges 33, each membrane-electrode plate 50 comprises an exchange edge 51, two centering notches 52 and two secondary edges 53 and, as shown on the , each end plate 70 comprises an exchange edge 71, two centering notches 72 and two secondary edges 73.

It is preferably provided that, for each plate, the centering notch is adjacent to the exchange edge and to the secondary edge, that is to say it is at the end of the exchange edge and at the end of the edge secondary, to connect said exchange edge and said secondary edge together. In other words, it is advantageously provided that each centering notch is located between one of the exchange edges and one of the secondary edges of the plate considered. Here, each plate of stack 2 includes only two centering notches, only one exchange edge and only two secondaries. It is advantageously provided that the exchange edge is parallel to the tangential direction X2. It is advantageously provided that the secondary edges adjacent to this exchange edge are parallel to the tangential direction X2. It is expected that the centering notches adjacent to this exchange edge are formed hollow relative to the exchange edge, in the opposite direction to direction Y2, or opening in direction Y2.

During manufacturing, each rail 131 extends parallel to the direction Z2. Each centering notch 12, 32, 52 and 72 is in correspondence with the rail 131 in direction X2, and engages astride rail 131 or around rail 131 in direction Y2, such that rail 131 is at least partially received in each of the notches 12, 32, 52 and 72, as shown in Figures 5 and 7-9. To be able to cooperate in sliding in the direction Z2 with the rail 131 during manufacturing, at least some of the centering notches 12, 32, 52 and 72, namely here the centering notches 32, 52 and 71, are “centering notches.” centering with contact" which have a shape complementary to that of the rail 131, to match the shape of the rail 131, or at least to be in contact with the rail 131 to center the plate concerned in the directions X2 and/or Y2 relative to to the rail 131. Preferably, other centering notches, namely here the notches 12, are “contactless centering notches” which allow the passage of the rail 131, which are only crossed by the rail 131 during manufacturing , and which do not need to be complementary with the rail 131, but only to be sufficiently recessed and/or wide enough to be crossed by the rail 131, while remaining at a distance from the rail 131. The centering notches 12, 32, 52 and 72 are also shaped to allow removal of the rail 131, by moving the rail away from the stack 2 in the direction Y2, once the stack 2 is completed.

In the present example, as visible in Figures 5 and 7-9, the rail 131 has a cylindrical shape with a circular base, centered on an axis parallel to the direction Z2. Preferably, as clearly visible in Figures 5 and 6, for each plate, the centering notch 12, 32, 52 or 72 has a profile in the form of an arc of a circle, projected into a projection plane P2 which is orthogonal to the stacking direction Z2. The plane P2 is parallel to the plane in which Figures 5 and 6 are drawn. By “profile”, we mean the edge of the notch. In other words, it is preferred that the centering notches are rounded, which allows the notches to be used both for centering the plates during the manufacture of the stack 1 and both for receiving the longitudinal joint portion 91 of the joint. 90. However, other profiles could be provided, for example "U", "V", etc. In the case where the rail 131 has a shape other than that provided here, another corresponding shape can be intended for centering notches. In the example, the profile of the edge of the centering notch with contact is of the same nature as the sectional profile of the rail 131, so as to authorize contact along a segment of this notch edge profile having a certain length. However, it could be envisaged that the profile of the edge of the centering notch with contact and the sectional profile of the rail 131 be provided to ensure only point contacts, preferably enough point contact points so that the contact between the edge of the centering notch with contact and the rail 131 precisely determines the relative position of the notch relative to the rail in the two transverse directions X2 and Y2.

As visible on the , each peripheral joint 80 preferably comprises an exchange edge portion 81, which is interposed between the exchange edge 11 or 31 of the adjacent plate 10 or 30, and the exchange edge 51 of the adjacent plate 50, according to direction Z2. The exchange edge portion 81 extends parallel to and along these exchange edges 11, 31, 51 of the adjacent plates. Each peripheral joint 80 preferably comprises a secondary edge portion 83, which is interposed, on the one hand, between the secondary edge 13 or 33 of the adjacent flow field plate 10 or 30, and, on the other hand, the secondary edge 53 of the adjacent plate 50, in direction Z2. The secondary edge portion 83 extends parallel to and along these secondary edges. Each peripheral joint 80 preferably comprises a recessed portion 82, which is interposed between the notch 12 or 32 of the adjacent plate 10 or 30, and the notch 52 of the adjacent plate 50, in the direction Z2. The recessed portion 82 extends along these centering notches and preferably has a profile similar to that of these centering notches, in particular to be able to be crossed by the rail 131 during manufacturing. It is preferably provided that, for each joint 80, the recessed portion 82 is adjacent to the exchange edge 81 and to the secondary edge 83, that is to say it is at the end of the portion 81 and at the end of portion 83, to connect portions 81 and 83 together. In other words, it is advantageously provided that each recessed portion 82 is between portions 81 and 83, respectively of exchange edge 81 and secondary edge 83. Here, each seal 80 comprises only two recessed portions 82, only one exchange edge portion 81 and only two secondary edge portions 83, in correspondence with the number of exchange edges, secondary edges and centering notches of each plate. It is advantageously provided that the exchange edge portion 81 is parallel to the tangential direction X2. It is advantageously provided that the secondary edge portions 83 adjacent to this exchange edge portion 81 are parallel to the tangential direction X2. It is anticipated that the recessed portions 82 adjacent to this exchange edge portion 81 are formed recessed relative to this exchange edge portion 81, in the opposite direction to the direction Y2, or opening in the direction Y2 .

In the example, the recessed portion 82 has a profile in the shape of an arc of a circle, projected into the projection plane P2, or, more generally, a profile of the same shape or corresponding to that of the centering notches 12 , 52 or 72 adjacent respectively belonging to the plates 10, 50 or 70, as described above.

The successive exchange edges 11, 31, 51 and 71 of the plates 10, 30, 50 or 70 are superimposed in the direction Z2. For this particular case, the term “superimposed” has a special meaning, in that this term does not exclude, possibly, that certain exchange edges may be recessed and others protrude in the direction Y2, such that described preferentially below. However, “superimposed” indicates that overall, the exchange edges extend along the same plane perpendicular to the direction Y2. Except for this particular case and a few others described below, the term “superimposed” is used with its usual meaning.

The exchange edges together form exchange face 5, or one of the exchange faces. The exchange face 5 is therefore a face which is not necessarily flat, and can therefore in particular present grooves corresponding to the recessed exchange edges. If the joints 80 are provided, the exchange edge portion 81 also belongs to this exchange face 5. Preferably, the exchange edges 11, 31, 51 and 71 superimposed in the direction Z2 are parallel to each other. Preferably, the exchange edges 11 of the primary flow plates 10, which are superimposed in the direction Z2, are arranged in the same plane parallel to the direction Z2 and are arranged in the same position in the tangential direction X2, or even , are of the same length in the direction X2. Preferably, the exchange edges 31 of the secondary flow plates 30, which are superimposed in the direction Z2, are arranged in the same plane parallel to the direction Z2 and are arranged in the same position in the tangential direction X2, or even , of the same length following direction X2. Preferably, the exchange edges 51 of the membrane-electrode plates 50, which are superimposed in the direction Z2, are arranged in the same plane parallel to the direction Z2 and are arranged in the same position in the tangential direction X2, or even, are of the same length in the direction X2. Preferably, the exchange edges 71 of end plates 70, which are superimposed in the direction Z2, are arranged in the same plane parallel to the direction Z2 and are arranged in the same position in the tangential direction X2, or even, are of same length following direction X2.

The successive secondary edges 13, 33, 53 and 73 of the plates are superimposed in the direction Z2. For this case also “superimposed” has a particular meaning, in that this term does not exclude that, possibly, certain secondary edges are recessed and others project in the direction Y2, as described below. However, “superimposed” means that, overall, the secondary edges extend along the same plane perpendicular to the direction Y2. The secondary edges together form one of the secondary faces 7. If the joints 80 are provided, the secondary edge portion 83 also belongs to this secondary face. Preferably, the secondary edges 13, 33, 53 and 73 superposed in the direction Z2 are parallel to each other. Preferably, the secondary edges 13 of the primary flow plates 10, which are superimposed in the direction Z2, are arranged in the same plane parallel to the direction Z2 and are arranged in the same position in the tangential direction X2, or even, are of the same length following direction X2. Preferably, the secondary edges 33 of the secondary flow plates 30, superimposed in the direction Z2, are arranged in the same plane parallel to the direction Z2 and are arranged in the same position in the tangential direction length following direction X2. Preferably, the secondary edges 53 of the membrane-electrode plates 50, superimposed in the direction Z2, are arranged in the same plane parallel to the direction Z2 and are arranged in the same position in the tangential direction X2, or even, are of the same length following direction X2. Preferably, the secondary edges 73 of the end plates 70, superimposed in the direction Z2, are arranged in the same plane parallel to the direction Z2 and are arranged in the same position in the tangential direction direction X2.

The successive centering notches 12, 32, 52 and 72 of the plates are superimposed in the direction Z2. Here again, “superimposed” has a particular meaning, in that this term does not exclude the possibility that, possibly, certain centering notches may be recessed and others protrude in the direction Y2, as described below at preferential title. “Superimposed” nevertheless indicates that, overall, the centering notches are aligned along the same axis parallel to the Z2 axis. The centering notches together form one of the centering grooves 6. If the joints 80 are provided, the recessed portion 82 also belongs to this centering groove. Preferably, the notches 12 of the primary flow plates, superimposed in the direction Z2, are identical and are arranged in the same position in the directions X2 and Y2. Preferably, the notches 32 of the secondary flow plates 30, superimposed in the direction Z2, are identical and are arranged in the same position in the directions X2 and Y2. Preferably, the notches 52 of the membrane-electrode plates 50, superimposed in the direction Z2, are identical and are arranged in the same position in the directions X2 and Y2. Preferably, the notches 72 of the end plates 70, superimposed in the direction Z2, are identical and are arranged in the same position in the directions X2 and Y2.

Advantageously, at least some of the flow plates 10 and 30 form exchange orifices 19. Each orifice 19 opens onto one of the exchange edges 11 and/or 31 in the normal direction Y2, i.e. that is to say that the orifices 19 open onto the surface of the exchange face 5 formed by these exchange edges 11 and 31. The orifices 19 thus open into the interior of the collector 100, in particular inside the connector 101, and are covered by the collector 100, in particular by the connector 101, and framed by the seal 90. Preferably, each edge 11 and/or 31 comprises a row of orifices 19, said row being parallel to the direction X2, so that the assembly formed by the stacking of edges 11, 31 has a grid of orifices 19 which extends along directions

The exchange orifices 19 are provided to put the external collector 100 in fluid communication with the reactive operational fluid circulation fields of the plates 10, or with the reactive operational fluid circulation fields of the plates 30, or with the circulation fields of operational cooling fluid formed between the adjacent plates 10 and 30. To this end, each exchange orifice 19 leads to one or more of the channels of the circulation field concerned. On the stack outside the exchange face(s) 5, an exchange orifice 19 is advantageously not provided. The exchange of operational fluid between the external collector 100 and the stack 2 is therefore carried out by the intermediate of the exchange orifices 19 carried by the face 5 to which the collector 100 is connected. In the present example, the exchange orifices 19 are formed exclusively by the plates 10, on the respective exchange edge 11 thereof. For a given exchange face 5, corresponding to a given external collector 100, all the orifices 19 opening into this exchange face communicate exclusively with the circulation fields of the same operational fluid for all the electrochemical cells covered by this face exchange 5.

Preferably, as visible in Figures 2 and 3, the transverse grooves 8 are each formed on the respective exchange edge 71 of one of the end plates 70. Therefore for each of these end plates 70, the transverse groove 8 connects together the centering notches 72 of the end plate 70 considered, so as to open into each of these centering notches 72 of the end plate 70 considered, to thus connect the centering grooves 6.

Preferably, for at least one of the plates of the stack 2, and preferably, for all the plates of the stack 2, the exchange edge 11, 31, 51 or 71 of the plate concerned is slightly in projecting outwards from the stack 2, that is to say in the direction Y2, with respect to the adjacent secondary edges 13, 33, 53 or 73. Thus, on the , it has been illustrated that the exchange edge 11, 31 of each flow field plate 10, 30 projects towards the outside of the stack 2, that is to say in the direction Y2, by relative to the adjacent secondary edge 13, 33 of the same flow field plate 10, 30, of a quantity, called exchange edge offset "d1-3", which is preferably between 0.05 millimeter and 3 millimeters , preferably between 0.2 millimeter and 1 millimeter. As a result, when the longitudinal joint portions 91 are formed and/or when they are compressed by the collector 100, there is less chance that they overflow from the side of the exchange face 5, and that they accidentally close the exchange orifices 19. As a variant, however, it can be provided that the exchange edge is aligned with the secondary edge, that is to say, extends along the same axis in direction X1.

Preferably, for at least one of the membrane electrode plates 50, and preferably, for all the membrane-electrode plates 50 of the stack 2, the exchange edges 51 of the membrane-electrode plate 50 project towards the outside of the stack 2, that is to say along the direction Y2, with respect to the exchange edges 11 and 31 of the adjacent flow field plates 10 and 30. Preferably, for at least one of the membrane electrode plates 50, and preferably, for all the membrane electrode plates 50 of the stack 2, the secondary edges 53 of the membrane electrode plate 50 project towards the exterior of the stack 2, that is to say in the direction Y2, with respect to the secondary edges 13 and 33 of the adjacent flow field plates 10 and 30. These arrangements advantageously make it possible to reduce the risk of short circuit between the edges 11 and 31 and between the edges 13 and 33 of these plates 10 and 30, by improving their separation by the electrically insulating edges 51 and 53. Thus, on the , it has been illustrated that the exchange edge 51 of each membrane-electrode plate 50 projects towards the outside of the stack 2, that is to say in the direction Y2, with respect to the exchange edges 11 and 31 of adjacent flow field plates 10 and 30, of a quantity, called membrane-electrode plate offset "d50", which is preferably between 0.1 millimeter and 2 millimeters, preferably between 0.2 millimeter and 1 millimeter. Likewise, for all the membrane-electrode plates 50 of the stack 2, the secondary edges 53 of the membrane-electrode plate 50 project towards the outside of the stack 2, that is to say along the direction Y2, relative to the secondary edges 13 and 33 of the adjacent flow field plates 10 and 30 of the same membrane-electrode plate offset value “d50” preferably between 0.1 millimeter and 2 millimeters, preferably between between 0.2 millimeter and 1 millimeter.

Preferably, for at least one of the bipolar plates, and preferably for all, the exchange edge 11 of the primary flow field plate 10 and the exchange edge 31 of the flow field plate secondary 30 are in mutual flush, that is to say they are at the same level in direction Y2. Preferably, likewise, the secondary edges 13 of the primary flow field plate 10 and the secondary edges 33 of the secondary flow field plate 30 are flush with each other, i.e. are at the same level following direction Y2.

Preferably, for at least one of the bipolar plates, and preferably for all, the centering notch 12 of the primary flow field plate 10 is set back towards the inside of the stack 2, this is that is to say, in the opposite direction of the direction Y2, relative to the centering notch 32 of the secondary flow field plate 30. The centering notch 32 of the secondary flow field plate 30 can also, in addition, be of smaller size, along the directions X2 and Y2, than the centering notch 12 of the primary flow field plate 10. Thus, during the manufacture of the cell 1, for each bipolar plate, it is the centering notch 32 of the secondary flow field plate 30 which comes into transverse support on the centering rail 131 to ensure the transverse positioning of the bipolar plate, which can therefore be described as a notch centering notch with contact, while the centering notch 12 remains distant from the centering rail 131 by being crossed by the rail 131 in the direction Z2, which can therefore be described as a centering notch with contact. This is particularly possible when the bipolar plate consists of plates 10 and 30 preassembled and added to the stack together, or when the stack is produced by stacking preassembled electrochemical cells. Thus, on the , it has been illustrated that, for at least one of the bipolar plates, and preferably for all, the centering notch 12 of the primary flow field plate 10 is set back towards the inside of the stack 2 , that is to say, in the opposite direction of the direction Y2, relative to the centering notch 32 of the secondary flow field plate 30 by an amount, called notch offset "d12-32 », which is preferably between 0.1 millimeter and 1 millimeter, preferably between 0.2 millimeter and 0.6 millimeter. Of course, this notch offset between the centering notch 12 of the primary flow field plate 10 and the centering notch 32 of the secondary flow field plate 30 is independent of the fact that, for example , the primary flow field plate 10 is a cathode or anodic plate, the secondary flow field plate 30 then being respectively an anodic or cathode plate.

Preferably, the centering notch 52 of at least one of the membrane-electrode plates 50, or all of the membrane-electrode plates 50, is flush with the centering notch 32 of the field plate secondary flow 30 adjacent. The centering notch 52 of at least one of the membrane-electrode plates 50, or of all the membrane-electrode plates 50, can also, in addition, be of the same size, along the directions X2 and Y2, as the centering notch 32 of the adjacent secondary flow field plate 30. Thus, during the manufacture of the stack 2, the centering notch 52 comes to bear on the centering rail 131 to ensure the transverse positioning of the plate 50, when the plate 50 is added to the stack 2, and can therefore also be qualified as a centering notch with contact.

Alternatively, it can be provided that the centering notch 52 of at least one of the membrane-electrode plates 50, or of all the membrane-electrode plates 50, is slightly set back towards the inside of the stack 2 relative to the centering notch 32 of the adjacent secondary flow field plate 30, and can therefore in this case be described as a non-contact centering notch. Preferably, the centering notch 52 then projects outwards from the stack 2 relative to the centering notch 12 of the adjacent primary flow field plate 10. In this case, it can also be provided that the centering notch 52 has an intermediate size, in the directions X2 and Y2 between those of the notches 12 and 32. In this case, to ensure the centering of the plate 50 during the stacking, it is envisaged for example that the membrane-electrode plate 50 is preassembled with another plate which has a centering notch with contact, here for example the adjacent secondary flow field plate 30. For the alignment of the membrane-electrode plate 50 with this other plate for the purposes of its pre-assembly, or for the stacking of the membrane-electrode plate 50 without pre-assembly, provision can be made to ensure the centering of the membrane-electrode plate 50 for example by optical alignment or by geometric pre-alignment shapes between the two adjacent plates.

Preferably, as shown on the , each flow field plate 10 occupies a thickness E10 within the stack 2, the thickness E10 being measured parallel to the stacking direction Z2. E10 is the thickness occupied at the perimeter 3 of the flow field plate 10. Preferably, each flow field plate 30 occupies a thickness E30 within the stack 2, the thickness E30 being measured parallel to the stacking direction Z2. E30 is the thickness occupied at the perimeter 3 of the flow field plate 30. Preferably, each membrane-electrode plate 50 occupies a thickness E50 within the stack 2, the thickness E50 being measured parallel to the direction stacking Z2. E50 is the thickness occupied at the perimeter 3 of the membrane-electrode plate 50. Preferably, the thicknesses E10 and E30 are greater than the thickness E50, so that the plates E10 and E30 can provide sufficient internal volume for the channels of the flow fields, in the direction of the stacking direction Z2. Furthermore, it is advantageously anticipated that the thickness E10 is greater than the thickness E30. For example, thickness E10 is at least 1.5 times larger than thickness E30, or even twice as large. This difference between the thicknesses E10 and E30, combined with the positioning and/or the relative size of the notches 12 and 32 described above, makes it possible to reduce the risk of short circuit between flow field plates 10 and 30 adjacent to the same membrane-electrode plate 50. Indeed, within the groove 6, the distance to be covered for the formation of an electric arc connecting the notch 12 to the notch 32 located beyond the membrane-electrode plate 50 , is particularly high, thanks to the removal of the notch 12 and the thickness of the plate 10, in addition to the presence of the insulating and projecting notch 52.

Preferably, for at least one of the peripheral joints 80, if not for all the peripheral joints 80, the exchange edge portion 81 is flush in the direction Y2, with the exchange edge 11 or 31 of the plate 10 or 30 against which the seal 80 is formed. Alternatively, it could be provided that the exchange edge portion 81 is slightly set back in the opposite direction from direction Y2, or slightly projects in direction Y2, relative to the exchange edge 11 or 31 of the plate 10 or 30. against which the seal 80 is formed. Preferably, for at least one of the joints 80, if not for all the joints 80, the exchange edge portion 81 is set back, in the opposite direction from the direction Y2, with respect to the edge of exchange 51 of the plate 50 against which the joint 80 is formed. In other words, the edge 51 advantageously projects in the direction Y2 relative to the portion 81.

Preferably, for at least one of the peripheral joints 80, if not for all the peripheral joints 80, the secondary edge portion 83 is flush in the direction Y2, with the secondary edge 13 or 33 of the plate 10 or 30 against which the joint 80 is formed. It could alternatively be provided that the secondary edge portion 83 is slightly set back in the opposite direction from the direction Y2, or slightly projects in the direction Y2, relative to the secondary edge 13 or 33 of the plate 10 or 30 against which the joint 80 is formed. Preferably, for at least one of the joints 80, if not for all the joints 80, the secondary edge portion 83 is set back, in the opposite direction from the direction Y2, with respect to the secondary edge 53 of the plate 50 against which the seal 80 is formed. In other words, the edge 53 advantageously projects in the direction Y2 relative to the portion 83.

Preferably, for at least one of the peripheral joints 80 interposed between a plate 10 and a plate 50, otherwise for all these joints 80 interposed between a plate 10 and a plate 50, the recessed portion 82 is flush in the direction Y2, with the notch 12 of this plate 10 against which the joint 80 is formed. Preferably, this same recessed portion 82 is recessed in the direction Y2, opposite the notch 52 of the plate 50 against which the seal 80 is formed. This may imply that the size of the recessed portion 82 is larger than the size of the notch 52. During manufacturing, the recessed portion 82 can thus be crossed by the rail 131 without touching it.

Preferably, for at least one of the peripheral joints 80 interposed between a plate 30 and a plate 50, otherwise for all these peripheral joints 80 interposed between a plate 30 and a plate 50, the recessed portion 82 is recessed along the direction Y2, opposite the notches 32 and 52 of the plates 30 and 50 between which the peripheral seal 80 is interposed. This may imply that the size of the recessed portion 82 is larger than the size of the notches 32 and 52. During manufacturing, the recessed portion 82 of the peripheral joint 80 can thus be crossed by the rail 131 without touching it.

Preferably, for at least one of the end plates 70, and preferably for the two plates 70, the exchange edge 71, the secondary edge 73 and the notch 72 are arranged in the same way as the edge of exchange 31, the secondary edge 33 and the notch 32 of the plate 30. In other words, except at the level of the groove 8, the exchange edge 71, the secondary edge 73 and the notch 72 have the same shape and the same arrangement as those of the plate 30. Preferably, a thickness of the plate 70, measured at its perimeter 3 parallel to the thicknesses E10 and E30, is greater than the thicknesses E10 and E30.

As shown in Figures 2 and 6, the longitudinal portion 91 of the joint 90, in the opposite direction to the direction Y2, matches and fills the shape of the different notches 12, 32, 52 and 72 and the recessed portions 82. In particular, the notches 32 and 52, which project relative to the others, are advantageously encapsulated by the portion 91 of the joint 90. In other words, the joint 90 is interposed in the direction Z2 between the respective perimeter 3 of the successive plates 30 and 50, at the level of the notches 32 and 52, being received in the notches 12 and the recessed portions 82. Thanks to these arrangements, not only optimal sealing of the fluid connection between the collector 100 and the face 5 is ensured, but also the risk of electric arc within groove 6 is reduced.

In addition, the seal 90 projects, in the direction Y2, beyond the exchange edges 11, 31, 51 and 71. Preferably, the seal 90 thus projects over its entire perimeter, that is to say i.e. for joint portions 91 and 92.

To manufacture the fuel cell 1, it is possible to implement a process as defined below, and as illustrated in Figures 7 to 9.

As shown on the , the support plate 111 is preferably placed, preferably in a horizontal plane, so that the direction Z2 will be vertical and oriented upwards. While the plates 10, 30, 50 and 70 and the joints 80 are not yet stacked and the joint 90 is not yet formed, the peripheral centering template 130, comprising the rails 131, is temporarily installed. Here, only two rails 131 are provided for the template 130, but a different number can be provided, by providing a corresponding number of centering grooves 6 on the plates 10, 30, 50, 70. The template 130 also includes a fixing base 132 , to which the rails 131 are fixedly attached.

The centering template 130 is attached to the periphery of the stack 2, that is to say on the outside of the stack 2, against the side 4 of the stack 2 carrying the grooves 6. To be fixed to the plate 111, the template 130 is reported by being moved until it comes into contact with the plate 111 parallel to the direction Y2, or at least with a movement having a component in the direction Y2.

To be fixed to the plate 111, it is advantageously provided that the base 132 is attached against the fixing edge 115 of the plate 111, that is to say advantageously the same fixing edge 115 as that which will later be used to fix the collector 100. Preferably, the base 132 is fixed to the fixing edge 115 by screwing. Tapped holes provided in the edge 115 can be used for screwing the template 130 and, later, for screwing the collector 100.

When the template 130 is installed, the rails 131 protrude in the direction Z2 from the base 132, being distributed in a plane perpendicular to the direction X2.

At this stage, additional peripheral centering templates can be provided, arranged facing other sides 4 of the stack 2, if these other sides 4 have corresponding centering grooves. Finally, we can provide centering means internal to the stack 2, such as rods parallel to the direction Z2 and crossing the stack 2 from the inside, from the plate 111.

Once the template(s) 130 are installed, the plates 10, 30, 50 and 70 and the joints 80 are stacked to form stack 2, while the joint 90 is still not formed. To carry out the stacking, each plate is slid parallel to the direction Z2, along the rails 131, the corresponding centering notch of each plate receiving the rail 131. In other words, the rail 131 has the function of guiding the plate via the corresponding centering notch. As indicated above, preferably, certain plates are stacked individually, for example plates 50 and 70, while other plates, namely for example plates 10 and 30, are preassembled in pairs before stacking. Preferably, each joint 80 is pre-assembled with one of the plates, preferably one of the plates 10 and 30, before being added to the stack 2. In practice, except possibly at the ends of the stack 2, a complete bipolar plate is added to stack 2, including two pre-assembled adjacent plates 10 and 30 and two joints 80 formed respectively on plates 10 and 30.

For each plate, or each pre-assembled assembly comprising several plates, at least one of the centering notches cooperates mechanically with the rail 131 to guide the sliding along Z2 and center this pre-assembled assembly or plate in the directions X2 and Y2, while the other centering notches, set back from rail 131 in direction Y2, are only crossed by rail 131 in direction Z2. In the present example, only the notches 32, 52 and 72, respectively of the secondary flow plates 30, of the membrane-electrode plates 50 and of the end plates, are centering notches with contact which cooperate mechanically with the rail 131, then that the notches 12 and the recessed portions 82, respectively of the primary flow field plates 10 and the peripheral joints 80, further back, are at distances from the rail 131 being only crossed by the rail 131 in the direction Z2, and are therefore non-contact centering notches. The cooperation of the rails 131 with the centering notches ensures that, once stack 2 is completed, each plate of stack 2 is correctly positioned against the adjacent plate, in particular along directions X2 and Y2.

To perform stacking, as shown in the we advantageously start by stacking the end plate 70 against the support plate 111, by sliding the end plate 70 along the rails 131 via the notches 72. We then advantageously stack a current collector and a planar seal, not shown.

A flow field plate 30 is then stacked, guiding the plate 30 in the direction Z2 by cooperation of the rails 131 with the notches 32, until the plate 50 comes to bear against the elements already assembled in the opposite direction. from direction Z2.

We then stack one of the plates 50, guiding the plate 50 in the direction Z2 by cooperation of the rails 131 with the notches 52, until the plate 50 comes to bear against the flow field plate 30 already assembly. A pre-assembled bipolar assembly is then stacked comprising a plate 10, carrying a joint 80 facing towards the plate 50 already stacked, a plate 30 fixed to the plate 10 in the direction Z2, and a second joint 80 formed on the plate 30 following direction Z2. This preassembled assembly is guided by the rails 131 by cooperation of said rails with the notches 32. Another plate 50 is then stacked, and so on, alternating between a preassembled bipolar assembly and a plate 50. Once the last plate 50 stacked, a final flow field plate 10 is added, on which another current collector and possible seal are stacked. The second end plate 70 is then stacked.

Stack 2 is then completed, and is kept centered using rails 131, still in place.

Once the stack 2 is completed and while the seal 90 is still not in place, the tie rods 113 are installed on the support plate 111. Then, the springs 114 and the support plate 112 are installed. , so that the springs 114 are interposed in the direction Z2 between the support plate 112 and the plate 70 at the top of the stack 2. The installation of the support plate 112 preferably includes threading the plate support 112 on the tie rods 113.

Preferably, the support plate 112 carries a fixing base 134, which is fixed on the fixing edge 116 of the support plate 112, preferably by screwing, in a manner similar to the fixing base 132, fixed on the fixing edge 115 of the support plate 111. The base 134, which belongs to the template 130 and being initially separated from the template 130, is configured to be slipped onto the rails 131, in order to be guided in sliding by the rails following direction Z2. To install the support plate 112, the plate is advantageously slipped onto the tie rods 113, preferably with the base 134 threaded onto the rails 131, in the direction Z2, with the springs 114 interposed between the plate 112 and the plate. 70 at the top of stack 2

Once the stack 2 is placed between the two support plates 111 and 112, and while the template 130, in particular the rails 131, are still in place, the stack 2 is placed in compression using the tie rods. 113, for example by tightening nuts at the ends of the tie rods 113 to bring the support plates 111 and 112 closer to each other in the direction Z2. Assembly with a press is also possible followed by torque tightening of the tie rod nuts.

Once the stack 2 is in compression between the plates 111 and 112 and before forming the joint 90, the rails 131 are removed, for example by removing the template 130 as a whole. For this, the bases 132 and 134 are advantageously separated from the plates 111 and 112 to separate the rails 131 from the plates 111 and 112. Then, the template 130 is moved away from the stack 2 transversely with respect to the direction Z2, this is that is to say, according to a movement which includes a component along Y2 with respect to the stack 2. In particular, the rail 131 is extracted from the centering groove 6 by being moved transversely with respect to the direction Z2, in particular along the direction Y2 relative to stack 2. Removal of rails 131 is therefore particularly easy. We then arrive at the configuration of the .

Once the rails 131 have been removed, the collector seal 90 is put in place, in particular with the portions 91 in the grooves 6 and the portions 92 in the grooves 8. Preferably, the seal 90 is formed in situ, in flowing, by injecting or overmolding the seal 90 in the liquid or pasty state in the grooves 6 and 8, then by hardening the seal 90. To form the seal 90 while it is in the liquid or pasty state, we prefers that the stack 1 is oriented so that the direction Y2 is directed upwards, so that gravity contributes to the liquid or pasty material being received in the grooves 6 and 8 without overflowing and matching the interior contours of the grooves 6 and 8.

To form the joint 90, preferably, as shown in the , we first apply a first bead 95 of a first material in the liquid or pasty state, in the grooves 6 and 8, over the entire perimeter of the future seal 90. The first material is advantageously based on silicone, or of another suitable elastomer, which is not crosslinked during its application to be in the liquid or pasty state and thus match the bottom of the grooves 6 and 8, in particular, by encapsulating the notches 32 and 52 which are projecting. We advantageously choose a material with low viscosity, to give it a self-leveling and/or filling character. This ensures that the material matches the bottom of the grooves 6 and 8, in particular that of the grooves 6 which is irregular due to the fact that certain centering notches protrude and others are recessed. Despite its low viscosity, the material can be applied very precisely, because it is prevented from spreading in the direction X2 by the groove 6 and in the direction Z2 by the groove 8.

Once the first bead 95 is applied, it is hardened in situ. In the case of a silicone, hardening can be obtained for example by crosslinking the silicone at room temperature. The first bead 95 then forms a base belonging to the future joint 90, which fills and matches the grooves 6 and 8 over the entire perimeter of the joint 90.

Once the first bead 95 has been applied, a second bead 96 of a second material in the liquid or pasty state is applied over the first bead 95. It is possible to plan to apply the second bead 96 while the first cord 95 is only partially hardened, in order to ensure good cohesion between the cords 95 and 96. The second cord 96 covers the first cord over the entire periphery of the joint 90, constituted by the cords 95 and 96. The second cord 96 is formed so as to project from the grooves 6 and 8, over the entire perimeter of the joint 90.

The second cord 96 is advantageously made of a second material, different from the first at least in its viscosity, the viscosity being compared when the materials are in the uncured state. It is advantageously chosen that the second material to form the second bead 96, in the liquid or pasty state, is more viscous than the first material to form the first bead 95 when the first material is itself in the liquid or pasty state . This advantageously allows the second bead 96, applied in the liquid or pasty state, to maintain a raised shape over the first bead 95, even when the second material is not yet hardened. This advantageously allows the second bead 96, and even the seal 90 in general, to be formed without a mold. Preferably, the second material is also based on silicone, or another suitable elastomer. Once the second bead 96 is applied, it is hardened in situ, for example by crosslinking the silicone at room temperature. We then arrive at the configuration of the .

Even if the method of forming the joint 90 described above is preferred, it is possible, as a variant, to form the joint 90 in a single casting of material, or to form the joint 90 according to other appropriate processes.

Once the seal 90 is formed, the fluid connection of the external collector 100 is made with the exchange face 5. To do this, the collector 100, in particular the connector 101, is placed against the exchange face, approaching the connector 101 of the stack parallel to direction Y2. At the very least, the approach movement of connector 101 has a component following direction Y2. The connector 101 is matched to the seal 90, so that the connector 101 is in sealing contact over the entire perimeter of the seal 90. In particular, the collector 100 comes into sealing support on the seal 90 via the cord 96. The outer collector 100 is finally fixed using the fixing system 102, in particular by screwing the base 103 to the fixing edge 115 and by fixing the base 104 to the fixing edge 116. We then arrive at to the configuration of the .

Any characteristic described above for one of the embodiments or variants can be implemented for the other embodiments or variants described above, as far as technically possible.

Claims (15)

Fuel cell (1), comprising:

• a stack (2), comprising plates (10, 30, 50, 70), the plates (10, 30, 50, 70) of the stack (2) comprising flow field plates (10, 30) and membrane-electrode plates (50) and being stacked in a stacking direction (Z2) to form electrochemical cells, each plate (10, 30, 50, 70) being oriented perpendicular to the stacking direction (Z2) by being arranged flat against the adjacent plate (10, 30, 50, 70), each plate (10, 30, 50, 70) comprising a respective exchange edge (11, 31, 51, 71), the edges d exchange (11, 31, 51, 71) being parallel to each other and together forming an exchange face (5) belonging to the stack (2), the exchange face (5) extending parallel to the direction stacking (Z2);
• an external collector (100), which is fluidly connected to the stack (2) by being attached against the stack (2) so as to cover the exchange face (5), for an exchange of an operational fluid between the external collector (100) and the stack (2) via the exchange face (5); And
• a collector seal (90), which frames the exchange face (5) and which is interposed between the stack (2) and the external collector (100), to ensure sealing of the fluid connection between the external collector ( 100) and the stack (2);

characterized in that:

• each plate (10, 30, 50, 70) comprises a respective centering notch (12, 32, 52, 72), adjacent to the exchange edge (11, 31, 51, 71), the centering notches (12, 32, 52, 72) together forming a centering groove (6) belonging to the stack (2), the centering groove (6) bordering the exchange face (5) and extending parallel to the direction of stacking (Z2); And
• the collector seal (90) comprises a longitudinal seal portion (91), which is parallel to the stacking direction (Z2), which is formed in the centering groove (6), so that the longitudinal seal portion (91) is interposed between the stack (2) and the outer collector (100) to ensure the sealing of the fluid connection between the outer collector (100) and the stack (2).

Fuel cell (1) according to claim 1, in which at least one of the flow field plates (10, 30) forms exchange orifices (19), formed at the exchange edge (11, 31 ) of the flow field plate (10, 30), to emerge on the surface of the exchange face (5) and be covered by the external collector (100), the exchange of operational fluid between the external collector ( 100) and the stacking (2) being carried out via the exchange orifices (19). Fuel cell (1) according to any one of the preceding claims, in which the plates (10, 30, 50, 70) of the stack (2) comprise a respective secondary edge (13, 33, 53, 73), parallel to the exchange edge (11, 31, 51, 71) and being connected to the exchange edge (11, 31, 51, 71) by the centering notch (12, 32, 52, 72). Fuel cell (1) according to claim 3, in which, for at least one of the plates (10, 30, 50, 70) of the stack (2), the exchange edge (11, 31, 51 , 71) projects towards the outside of the stack (2) relative to the secondary edge (13, 33, 53, 73). Fuel cell (1) according to any one of claims 3 or 4, in which, for at least one of the membrane-electrode plates (50), the secondary edge (53) of the membrane-electrode plate (50) projects towards the outside of the stack (2), relative to the secondary edge (13, 33) of the adjacent flow field plates (10, 30). Fuel cell (1) according to any one of the preceding claims, in which:

• the flow field plates (10, 30) include primary flow field plates (10) and secondary flow field plates (30);
• at least one of the primary flow field plates (10) is adjacent to one of the secondary flow field plates (30) to form, with said secondary flow field plate (30), a bipolar plate; And
• for at least one of the bipolar plates:
  • the exchange edge (11) of the primary flow field plate (10) and the exchange edge (31) of the secondary flow field plate (30) are flush with each other, and
  • the centering notch (12) of the primary flow field plate (10) is set back towards the inside of the stack (2) relative to the centering notch (32) of the field plate secondary flow (30).

Fuel cell (1) according to claim 6, in which the centering notch (52) of at least one of the membrane-electrode plates (50) is flush with or recessed towards the inside of the stack (2), relative to the centering notch (32) of the adjacent secondary flow field plate (30), and projecting towards the outside of the stack (2), relative to the notch centering (12) of the adjacent primary flow field plate (10). Fuel cell (1) according to any one of the preceding claims, in which, for at least one of the membrane-electrode plates (50), the exchange edge (51) of the membrane-electrode plate (50) projects outwards from the stack (2), relative to the exchange edge (11, 31) of the adjacent flow field plates (10, 30). Fuel cell (1) according to any one of the preceding claims, in which the stack (2) further comprises peripheral joints (80), each peripheral joint (80) being interposed between one of the field plates of flow (10, 30) and one of the membrane-electrode plates (50) in the stacking direction (Z2), each peripheral seal (80) comprising:

• an exchange edge portion (81), which is interposed between the exchange edge (11, 31) of the flow field plate (10, 30) and the exchange edge (51) of the plate membrane-electrode (50) following the stacking direction (Z2), being flush with the exchange edge (11, 31) of said flow field plate (10, 30) or recessed towards the interior of the stack (2) relative to the exchange edge (11, 31) of said flow field plate (10, 30); And
• a recessed portion (82), which is interposed between the centering notch (12, 32) of the flow field plate (10, 30) and the centering notch (52) of the membrane-electrode plate (50) following the stacking direction (Z2), the recessed portion (82) being set back towards the inside of the stack (2) relative to the centering notch (52) of the membrane plate- electrode (50) and being flush with or set back towards the inside of the stack (2) relative to the centering notch (12, 32) of the flow field plate (10, 30).

Fuel cell (1) according to any one of the preceding claims, in which, for at least one of the plates (10, 30, 50, 70) of the stack (2), the centering notch (12 , 32, 52, 72) has a profile in the shape of an arc of a circle, projected in a projection plane (P2) which is orthogonal to the stacking direction (Z2). Fuel cell (1) according to any one of the preceding claims, in which:

• the plates (10, 30, 50, 70) of the stack (2) comprise an end plate (70), terminating the stack (2) in the stacking direction (Z2);
• a transverse groove (8) is provided in the exchange edge (71) of the end plate (70), the transverse groove (8) being connected to the centering groove (6) by opening into the centering notch ( 72) of the end plate (70); And
• the collector joint (90) comprises a transverse joint portion (92), which is perpendicular to the stacking direction (Z2), which is formed in the transverse groove (8) and which is joined to the longitudinal joint portion (91), so that the transverse seal portion (92) is interposed between the end plate (70) and the outer collector (100) to ensure fluid tightness of the fluid connection between the outer collector (100) and the stack (2).

Method for manufacturing the fuel cell (1) according to any one of the preceding claims, the method comprising:

• while the plates (10, 30, 50, 70) of the stack (2) are not yet stacked and the collector joint (90) is not yet formed, installation of a centering rail (131 ), which is parallel to the stacking direction (Z2) and which is capable of being received in the respective centering notch (12, 32, 52, 72) of the plates (10, 30, 50, 70);
• successive stacking of the plates (10, 30, 50, 70) to form the stack (2) while the centering rail (131) is installed, guiding the plates (10, 30, 50, 70) by mechanical cooperation d 'at least one of the centering notches (12, 32, 52, 72) with the centering rail (131), so that the centering rail (131) ensures centering of the plates (10, 30, 50, 70) transversely with respect to the stacking direction (Z2);
• removal of the centering rail (131), once the stack (2) is completed, by moving the centering rail (131) away from the stack (2), transversely to the direction of stacking (Z2);
• installation of the collector seal (90), with the longitudinal seal portion (91) formed in the centering groove (6), once the stack (2) has been completed and the centering rail (131 ) has been removed ; And
• fluid connection of the outer collector (100) to the stack (2), once the collector seal (90) has been put in place, by bringing the outer collector (100) against the stack (2) so as to cover the exchange face (5), with the interposition of the collector seal (90), including the longitudinal seal portion (91), between the stack (2) and the external collector (100), to ensure the sealing of the fluid connection between the external collector (100) and the stack (2).

Method according to claim 12, in which:

• the installation of the centering rail (131) comprises fixing the centering rail (131) on a support plate (111) belonging to the fuel cell (1);
• the successive stacking of the plates (10, 30, 50, 70) comprises the stacking of one of the plates (10, 30, 50, 70) against the support plate (111) parallel to the stacking direction (Z2); And
• removing the centering rail (131) includes separating the centering rail (131) from the backing plate (111).

Method according to any one of claims 12 or 13, in which the installation of the collector seal (90) comprises:

• application of a first bead (95), made of elastomer in a non-crosslinked state, in the centering groove (6), to form the longitudinal joint portion (91); And
• in-situ crosslinking of the non-crosslinked elastomer of the first bead (95), while the first bead (95) has been applied.

Method according to claim 14, wherein the installation of the collector seal (90) further comprises, once the first bead (95) has been applied: application of a second bead (96), made of elastomer in a non-crosslinked state on the first bead (95), so that the second bead (96) projects towards the outside of the stack (2), relative to the exchange face (5), the elastomer of the second bead (96) having a higher viscosity, when the second bead (96) is applied, than the viscosity of the elastomer of the first bead (95), when the first bead (95) is applied.