Fuel cell and method for manufacturing same

Abstract

The invention relates to a fuel cell (1), comprising: stacked plates (10, 30, 50, 70), each plate comprising a relevant exchange edge to form an exchange face (5); an outer manifold, fluidly connected to the exchange face; and a manifold seal (90), which frames the exchange face (5) to ensure the tightness of the fluid connection. In order for the manifold seal to have a better controlled shape and be easier to apply, each plate comprises a relevant centring notch, adjacent to the exchange edge, so as to form a centring groove (6) bordering the exchange face. The manifold seal comprises a longitudinal seal portion (91) formed in the centring groove and ensuring the tightness of the fluid connection.

Description

[0001] TITLE: Fuel cell and its manufacturing process

[0002] The present invention relates to a fuel cell and a method for manufacturing such a fuel cell.

[0003] US2001055708A1 describes a fuel cell comprising a horizontal stack of electrochemical cell components, including in particular anode and cathode fluidic field plates, anode and cathode supports, anode 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, i.e., projecting or recessed relative to each other, the sealing system comprises a first part forming bridges of low-temperature crosslinked silicone, which conforms to the shape of the projecting 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.

[0004] 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 in width and of imprecise shape. The spreading of the joint in width is likely to accidentally block part of the exchange face between the stack and the collector, thus reducing the efficiency of the fuel cell.

[0005] 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.

[0006] The invention relates to 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 stacking direction 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 exchange face extending parallel to the stacking direction; an outer collector, which is fluidically 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 outer collector and the stack via the exchange face;a collector seal, which frames the exchange face and which is interposed between the stack and the external collector, to ensure a seal of the fluid connection between the external collector and the stack; and preferably a fixing system, distinct from the collector seal, the external collector being fixed to the stack by means of the fixing system.;

[0007] 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.

[0008] The manifold seal comprises a longitudinal seal portion, which is parallel to the stacking direction, which is formed in the centering groove, such that the longitudinal seal portion is interposed between the stack and the outer manifold to seal the fluid connection between the outer manifold and the stack.

[0009] An idea underlying the invention is to provide for forming the collector gasket in the centering groove, so that the collector gasket, received inside the centering groove, has a low tendency to protrude laterally during its formation, in particular, even if the material used to form the collector gasket has a very low viscosity. Since the shape of the collector gasket is well controlled, it is easier to form a gasket that fits the centering notches of the plates, even if some notches are set back or protrude relative to each other. Sealing against the operating fluid is therefore easier to ensure.

[0010] 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 mechanically cooperates 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. During its stacking, at least some plates, whose centering notch mechanically cooperates with the rail, are guided in sliding in the stacking direction along the centering rail. For the other plates, the rail can pass through the centering notch in the stacking direction.Once the plates have been stacked, the centering rail is removed, leaving the centering notches free for the collector joint to be formed within them. The centering notches therefore combine the function of centering the plates and receiving the longitudinal joint portion.

[0011] 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 outer collector, the exchange of operational fluid between the outer collector and the stack being carried out via the exchange orifices.

[0012] 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.

[0013] 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.

[0014] Preferably, for at least one of the membrane electrode plates, the secondary edge of the membrane electrode plate projects outwardly from the stack, relative to the secondary edge of the adjacent flow field plates.

[0015] Preferably, the flow field plates comprise 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 mutually flush. Preferably, for at least one of the bipolar plates, the centering notch of the primary flow field plate is recessed toward the inside of the stack relative to the centering notch of the secondary flow field plate.

[0016] Preferably, the centering notch of at least one of the membrane-electrode plates is flush or recessed towards the inside of the stack, relative to the centering notch of the adjacent secondary flow field plate, and protrudes 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 protrudes towards the outside of the stack, relative to the exchange edge of the adjacent flow field plates.

[0017] 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 along the stacking direction.Preferably, each peripheral seal 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 along the stacking direction, 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 along the stacking direction, the recessed portion being set back towards the inside of 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 flow field plate.

[0018] 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, in projection in a projection plane which is orthogonal to the stacking direction.

[0019] Preferably, the plates of the stack comprise an end plate, terminating the stack along the stacking direction.

[0020] 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 seal comprises a transverse seal portion, which is perpendicular to the stacking direction, which is formed in the transverse groove and which is joined to the longitudinal seal portion, so that the transverse seal portion is interposed between the end plate and the outer collector to ensure the fluidic sealing of the fluidic connection between the outer collector and the stack.

[0021] The invention also relates to a method for manufacturing the fuel cell as defined above. The method comprises: while the plates of the stack are not yet stacked and the collector joint is not yet formed, installing a centering rail, which is parallel to the stacking direction and which is adapted to be received in the respective centering notch of the plates; successively stacking 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 to the stacking direction; removing the centering rail, once the stacking is complete, by moving the centering rail away from the stack, transversely to the stacking direction;fitting the collector seal, with the longitudinal seal portion formed in the centering groove, once the stack has been completed and the centering rail has been removed; fluid connection of the outer collector to the stack, once the collector seal has been fitted, by bringing the outer collector against the stack so as to cover the exchange face, with interposition of the collector seal, including the longitudinal seal portion, between the stack and the outer collector, to ensure the sealing of the fluid connection between the outer collector and the stack; and preferably, fixing the outer collector to the stack using the fixing system.;

[0022] Preferably, the installation of the centering rail comprises fixing the centering rail to a support plate belonging to the fuel cell. Preferably, the successive stacking of the plates comprises stacking one of the plates against the support plate parallel to the stacking direction. Preferably, the removal of the centering rail comprises separating the centering rail from the support plate.

[0023] Preferably, the installation of the manifold seal comprises: applying a first bead, of elastomer in an uncrosslinked state, in the centering groove, to form the longitudinal seal portion; and in-situ crosslinking the uncrosslinked elastomer of the first bead, while the first bead has been applied.

[0024] Preferably, the installation of the collector seal further comprises, once the first bead has been applied: applying a second bead, made of elastomer in a non-crosslinked state on the first bead, so that the second bead projects 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 in accordance with its principle, made with reference to the appended figures in which:

[0025] [FIG 1] Figure 1 shows a perspective view of a fuel cell according to one embodiment of the invention.

[0026] [FIG 2] Figure 2 is a view similar to Figure 1, where an outer collector has been removed.

[0027] [FIG 3] Figure 3 is a view similar to Figure 1, where the outer manifold and a manifold gasket have been removed.

[0028] [FIG 4] Figure 4 is a perspective view, from another angle, in this case from a low angle, showing a detail of Figure 3.

[0029] [FIG 5] Figure 5 is a top view of a portion of a stack belonging to the fuel cell of Figures 1 to 4.

[0030] [FIG 6] Figure 6 is a view similar to that of Figure 5, in which the manifold gasket is further shown.

[0031] [FIG 7] Figure 7 is a perspective view similar to Figure 1, showing a step in the fabrication of the fuel cell.

[0032] [FIG 8] Figure 8 is a perspective view similar to Figure 1, showing another step in manufacturing the fuel cell.

[0033] [FIG 9] Figure 9 is a perspective view similar to Figure 1, showing another step in manufacturing the fuel cell.

[0034] 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 electrode plates 50 and, preferably, end plates 70 and peripheral seals 80. The cell 1 also comprises an outer collector 100, visible in Figure 1, and a collector seal 90, visible in Figures 2 and 6. The cell 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.

[0035] 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 FIGS. 7 to 9 is used, including centering rails 131, which is at least partially removed once the 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 form the stack 2. The direction Z2 is perpendicular to the plates 10, 30, 50 and 70 and fixed relative to the stack 2.

[0036] As shown in Figures 1 to 3, the support plates 111 and 112 are arranged on either side of the stack 2 along the direction Z2. The springs 114 are interposed, along the direction Z2, between the stack 2 and the support plate 112. The support plate 111 bears against the stack along the direction Z2. The stack 2 bears 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, bear against the plate 112 along the 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 keep them in position relative to each other in the direction Z2 and thus to keep the stack 2 in compression in the direction Z2 under the action of the springs 114.The springs 1 14 advantageously allow dimensional variations of the stack 2 along the direction Z2, which may occur during use of the cell, in particular under the effect of thermal stresses. In the present example, six tie rods 1 13 and eight springs 1 14 are provided, however a different number of these elements may be provided. Alternatively, another type of compression system may be provided. For example, the compression system could, as an alternative, 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 a 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 in document EP1597786.

[0037] Each plate 10, 30, 50 and 70 is of planar shape, along a respective plane, perpendicular to the direction Z2. The plates 10, 30, 50 and 70 are parallel to each other and to the plates 1 11 and 112. As best seen in Figures 3 and 4, each plate 10, 30, 50 or 70 is arranged flat against the adjacent plate, that is to say 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, along a plane perpendicular to the stacking direction Z2.In the illustrated example, the adjacent flow field plates 10 and 30 are superimposed without the interposition of a peripheral seal 80 between them.

[0038] The different plates of the stack 2 are arranged in a precise order along 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 along 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 dioxygen possibly contained in air, as well as, if necessary, a cooling fluid.Within each electrochemical cell, the cathode reactive fluid reacts with the anodic reactive fluid to produce electricity. The cooling fluid is used to cool the 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 through the stack 2.

[0039] In this example, for the sake of simplification, only nine electrochemical cells have been shown. However, in practice, the fuel cell 1 may have a higher number of cells, for example between fifty and five hundred.

[0040] Each plate 10, 30, 50 and 70 has an outer perimeter 3, which extends along a plane orthogonal to the direction Z2. Each plate 10, 30, 50 and 70 extends exclusively inside its outer perimeter 3. Here, each outer perimeter 3 is of generally rectangular shape. Advantageously, the outer perimeter 3 of each plate of the same type of the stack 2 is of the same shape, or of a close shape, and is superimposed along the stacking direction Z2 with the outer perimeter 3 of all the other plates of the same type, that is to say with alignment along the 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 external perimeter 3 that is identical and superimposed along the stacking direction Z2 with the external perimeter 3 of the other primary flow field plates 10, the perimeter 3 of the plates 10 possibly being different from that of the plates 50, and so on. In particular, provision is made for the external perimeter 3 of plates of a first type to be, in whole or in part, set back towards the inside of the stack 2 or protruding towards the outside of the stack 2, relative to the external perimeter of the plates of another type. For example, provision is made for the external perimeter 3 of the membrane-electrode plates 50 to protrude towards the outside of the stack 2 relative to the external perimeter 3 of the flow field plates 10.

[0041] The joining of the outer 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 outer perimeters 3 of the plates of the stack 2 have a generally rectangular shape. Certain parts of the outer perimeter 3 of the plates 10, 30, 50 and 70 being set back or overhanging, the sides 4 are irregular, the set back perimeters 3 forming transverse furrows, perpendicular to the stacking direction Z2, the overhanging perimeters 3 forming ridges, perpendicular to the stacking direction Z2 and parallel to the furrows.

[0042] As best seen 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 inlet and an outlet 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 centering grooves 6 and two or three secondary faces 7.

[0043] In addition to said at least one exchange face 5, the stack may comprise, in a 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.

[0044] For each exchange face 5, we define a normal direction Y2, perpendicular to face 5 and to direction Z2 and directed towards the outside of stack 2, and a tangential direction X2, parallel to exchange face 5 and perpendicular to direction Z2.

[0045] 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 formed in a hollow 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

[0046] 6 along 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

[0047] 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.

[0048] 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 in a hollow in the stack 2, so as to be open 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, the grooves 6 and 8 frame the exchange face 5 according to a closed contour.

[0049] As visible in Figure 2, the collector seal 90 is preferably integral with the stack 2, while the collector 100 is attached to the stack 2, bearing against the seal 90, as shown in Figure 1.

[0050] Advantageously, the manifold seal 90 is provided to be separate from the manifold 100. Preferably, the manifold seal 90 is not attached to the manifold 100, in particular in that the seal 90 does not stick to the manifold 100 or is not anchored to the manifold 100. Preferably, the manifold 100 only bears against the seal 90.

[0051] Preferably, the seal 90 adheres and / or is anchored to the stack 2, to be integral with the stack 2.

[0052] 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 in FIG. 6, 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 seal portion 92 connects the two longitudinal seal portions 91 together, extending, for example, parallel to the tangential direction X2. The portions 92 are joined to the portions 91 at each end of the portions 92. Then, the portions 92 are arranged on either side of the face 5 in the direction Z2.Overall, the manifold gasket 90 has a quadrilateral shape, or at least has a closed contour around the face 5.

[0053] Preferably, each longitudinal seal portion 91 completely fills the section of the groove 6 that it occupies, over a portion of the groove 6 that runs along the face 5, the portion 91 matching the shape of the bottom of the groove 6. Similarly, preferably, each transverse seal portion 92 completely fills the section of the groove 8 that it occupies, over a portion of the groove 8 that runs along the face 5, the portion 92 matching the shape of the bottom of the groove 8. As visible in FIG. 6, along the direction Y2, the seal 90 projects slightly to ensure sealed contact with the collector 100. In particular, the longitudinal seal portions 91 project slightly along the direction Y2 outside the grooves 6. In particular, the transverse seal portions 92 project slightly along the direction Y2, outside the grooves 8.

[0054] 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 fluidically connected to the stack 2, the collector 100 is attached against the stack 2 so as to cover the exchange face 5, as shown in FIG. 1. To ensure the sealing of this fluid connection, the seal 90 is interposed between the collector 100 and the stack 2, in the direction Y2.

[0055] By "exchange" is meant 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 face 5, the exchange of operational fluid is carried out parallel to the normal direction Y2.

[0056] In practice, as shown in Figure 1, the collector 100 comprises a connector 101, which has for example a funnel shape. A first opening of the connector 101, preferably flared, covers the face 5 to be fluidically connected thereto. Preferably, a second opening of the connector 101, preferably narrower than the first opening, is connected to an operational fluid inlet or outlet pipe. The first opening connected to the exchange face 5 is advantageously 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 a shape complementary to that of the grooves 6 and 8.To ensure the sealing 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 91 and transverse 92 seal portions 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 closed contour edge which delimits the first opening of the connector 101 therefore has a bearing face which comes into sealed support, over the entirety of the closed contour, on the seal 90 which therefore extends over an identical contour. The bearing face of the closed contour edge which delimits the first opening of the connector 101 may 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 closed contour.This bearing surface may have one or more raised ribs relative to the plane X2, Z2 perpendicular to the normal direction Y2, preferably one or more raised ribs following said contour, parallel to each other along the contour if there are several of them. Such ribs extending over the contour may 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.

[0057] The collector 100 may also preferably comprise a fastening system 102, which is integral with the connector 101 and by means of which the collector 100 can be fastened to the stack 1 and / or to the stack 2.

[0058] The fastening system 102 is separate from the manifold seal 90. This allows the manifold seal 90 to perform exclusively a sealing function. In other words, the manifold seal 90 does not perform any fastening function. This makes it possible to clearly distinguish each of the functions, in that the sealing and the fastening are provided by different parts, and thus to propose a particularly simple and reliable design, but also very easy and quick to implement.

[0059] Here, the fastening system 102 is designed to be fastened to the stack 1 by being fastened to the plates 111 and 112. In other words, in this case, the collector 100 is fastened to the stack 2 in that the fastening system 102 is fastened to the plates 111 and 112. Alternatively, it may be provided that the collector 100 is fastened to the stack 2 in that the fastening system 102 is fastened to only one of the plates 111 and 112, or to another element of the stack 1, in particular an element of the compression system or to a casing of the stack 1, or even to the stack 2 itself. Preferably, it is provided that the fastening system 102 fastens the collector 100 to the stack without being fastened to the grooves 6, which are reserved for the collector seal 90.

[0060] Preferably, the fixing system 102 comprises a base 103, by means of which the fixing system is fixed to a 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 exchange face 5, in the direction Z2.

[0061] Preferably, the fixing system 102 comprises a base 104, by means of which the fixing system is fixed to a fixing edge 116, belonging to the plate 112. Preferably, the base 104 is attached against the 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 to the direction Y2 against the face 5 by the bases 103 and 104. Preferably, at least one of the bases 103 or 104 is allowed to move in the direction Z2 relative to the other base and / or relative to the connector 101, to allow a dimensional variation of the stack 2 in the direction Z2 during use.

[0062] At least one of the bases of the fixing system as described above could be fixed to a fixing edge belonging to one or other of the end plates 70 as described below.

[0063] Preferably, the stack 2 comprises exactly two end plates 70, which are provided at the ends of the stack 2, on either side, along the stacking direction Z2. In other words, each end plate 70 terminates the stack along the 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 provided to receive the forces applied to the stack 2 by the compression system. In the present example, the stack 2 bears 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 bears 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, in consideration of the electric currents in play within the stack 2. It may advantageously be provided that the plate 111 as well as the end plate 70 bearing against the support plate 111, are traversed, 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 made using the exchange face(s) 5 and the external collector(s) 100.

[0064] 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 involved within the stack 2. The membrane-electrode plate 50 also comprises 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 along the direction Z2, by a layer of cathodic 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 direction Z2, by a layer of anodic catalyst, itself covered by an anodic gas diffusion layer.The membrane of each plate 50 is the seat of the electrochemical reactions involving the anodic reactive fluid, brought to the face carrying the anodic catalyst, and the cathodic fluid, brought to the face carrying the cathodic catalyst, producing a difference in electrical potential on either side of the membrane, and, ultimately, the electricity of the fuel cell. Alternatively, the outer perimeter 3 of the plate 50 is formed by the membrane itself, and the plate 50 is frameless.

[0065] Preferably, for the manufacture of the cell 1, each membrane-electrode plate 50 is pre-assembled 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 when the plate 50 is added to the stack 2.

[0066] Preferably, each flow field plate 10 and 30 is electrically conductive, in consideration of the electric 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 passing through 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.

[0067] 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 of the Z2 direction. For example, the channels of the primary flow field plate 10 are directed, generally, parallel to the Y2 direction.By electrochemical reaction within the adjacent plate 50, each electrically conductive primary flow field plate 10 is brought to a cathodic electrical potential for the electrochemical cell in question. 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 outer 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 inwards relative to the perimeters 3.

[0068] All the secondary flow field plates 30 are dedicated to guiding the circulation of a second operational fluid, for example the anode 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 anode 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 the plate 30 and are directed, generally, either parallel to the direction Y2, or parallel to the direction X2.By electrochemical reaction within the adjacent plate 50, each electrically conductive plate 30 is brought to an anodic electrical potential for the electrochemical cell in question. 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 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.

[0069] 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 on 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 electrical potential.It may 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.

[0070] In the present example, it is provided that the bipolar plates of the stack are constituted by two separate plates 10 and 30 attached to one another. For example, each plate 10 and 30 is constituted by a metal sheet, which forms the flow 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 pre-assembled, 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 pre-assembled by being welded or brazed to one another.

[0071] Preferably, for the manufacture of the stack 1, each joint 80 is pre-assembled with one of the plates 10, 30 or 50. Preferably, before addition to the 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 may be provided that each membrane-electrode plate 50 carries two seals 80, one formed to project in the direction Z2 to be interposed between the plate 50 and the adjacent flow field plate 10, the other formed to project in the opposite direction to be interposed between the membrane-electrode plate 50 and the adjacent flow field plate 30 on the other side of the membrane-electrode plate 50. Preferably, each seal 80 is overmolded, cast or printed directly onto the plate 10, 30 or 50 which carries it, which then facilitates assembly. However, the use of a free seal is possible.

[0072] Furthermore, it is possible to provide for bonding of the plate 50 to one or other of the flow field plates 10 and 30, or to both flow field plates 10 and 30, for example by simple adhesive or double-sided bonding.

[0073] 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 the perimeter 3 of the plate concerned and constitute a part thereof. The exchange edge is intended to be covered by the extent of the collector 100, thus being inside the closed contour of the seal 90.The centering notch is intended to successively provide a first function, namely to provide guidance and centering of the plate 10, 30, 50 or 70 which carries it by cooperation with one of the rails 131, or at least to be crossed by the rail 131, when adding said plate to the stack 2, and a second function, namely to house the longitudinal seal portion 91 of the seal 90 once the stack 2 is completed, for sealing with the collector 100.

[0074] As shown in more detail in Figure 4, 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 in Figure 2, each end plate 70 comprises an exchange edge 71, two centering notches 72 and two secondary edges 73.

[0075] 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 is at the end of the exchange edge and at the end of the secondary edge, to connect together said exchange edge and said secondary edge. 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 the stack 2 comprises only two centering notches, only one exchange edge and only two secondary edges. 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 in a hollow relative to the exchange edge, in the opposite direction to the Y2 direction, or opening along the Y2 direction.

[0076] During manufacture, each rail 131 extends parallel to the Z2 direction. Each centering notch 12, 32, 52 and 72 is in correspondence with the rail 131 in the X2 direction, and engages astride the rail 131 or around the rail 131 in the Y2 direction, such that the 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. In order to be able to cooperate in sliding along 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 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 along the directions X2 and / or Y2 relative 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 manufacture, and which do not need to be complementary with the rail 131, but only to be sufficiently recessed and / or sufficiently wide 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.

[0077] 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 shape of an arc of a circle, in projection in 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" is meant the edge of the notch. In other words, it is preferred that the centering notches be rounded, which allows the notches to serve both for centering the plates during the manufacture of the stack 1 and for receiving the longitudinal joint portion 91 of the joint 90. However, other profiles could be provided, for example in a “U”, in a “V”,....In the case where the rail 131 has a shape other than that provided here, another, corresponding shape can be provided for the 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 allow contact along a segment of this notch edge profile having a certain length. However, it could be provided that the profile of the edge of the centering notch with contact and the sectional profile of the rail 131 are 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 with respect to the rail along the two transverse directions X2 and Y2.

[0078] As visible in Figure 4, each peripheral seal 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, in the direction Z2. The exchange edge portion 81 extends parallel and along these exchange edges 11, 31, 51 of the adjacent plates. Each peripheral seal 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 the direction Z2. The secondary edge portion 83 extends parallel and along these secondary edges.Each peripheral seal 80 preferably comprises a hollow 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 hollow portion 82 extends along these centering notches and preferably has a profile similar to that of these centering notches, in particular so that it can be crossed by the rail 131 during manufacture. It is preferably provided that, for each joint 80, the hollow portion 82 is adjacent to the exchange edge 81 and to the secondary edge 83, that is to say is at the end of the portion 81 and at the end of the portion 83, to connect the portions 81 and 83 together. In other words, it is advantageously provided that each hollow portion 82 is between the portions 81 and 83, respectively of the exchange edge 81 and of the secondary edge 83.Here, each joint 80 comprises only two hollow portions 82, only one exchange edge portion 81 and only two secondary edge portions 83, corresponding to the number of exchange edges, secondary edges and centering notches of each plate. Advantageously, the exchange edge portion 81 is parallel to the tangential direction X2. Advantageously, the secondary edge portions 83 adjacent to this exchange edge portion 81 are parallel to the tangential direction X2. It is provided that the hollow portions 82 adjacent to this exchange edge portion 81 are formed hollow relative to this exchange edge portion 81, in the opposite direction to the direction Y2, or opening in the direction Y2.

[0079] In the example, the hollow portion 82 has a profile in the shape of an arc of a circle, in projection in the projection plane P2, or, more generally, a profile of the same shape or corresponding to that of the adjacent centering notches 12, 52 or 72 belonging respectively to the plates 10, 50 or 70, as described above.

[0080] The successive exchange edges 11, 31, 51 and 71 of the plates 10, 30, 50 or 70 are superimposed along 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 set back and others protrude along the direction Y2, as 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 some others described below, the term "superimposed" is used with its usual meaning.

[0081] The exchange edges together form the exchange face 5, or one of the exchange faces. The exchange face 5 is therefore a face which is not necessarily flat, and may therefore in particular have 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 along the direction Z2, are arranged in the same plane parallel to the direction Z2 and are arranged in the same position along the tangential direction X2, or even of the same length along the direction X2. Preferably, the exchange edges 51 of the membrane-electrode plates 50, which are superimposed along the direction Z2, are arranged in the same plane parallel to the direction Z2 and are arranged in the same position along the tangential direction X2, or even are of the same length along the direction X2. Preferably, the exchange edges 71 of the end plates 70, which are superimposed along the direction Z2, are arranged in the same plane parallel to the direction Z2 and are arranged in the same position along the tangential direction X2, or even are of the same length along the direction X2.

[0082] The successive secondary edges 13, 33, 53 and 73 of the plates are superimposed along 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 set back and others protrude along 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 superimposed along the direction Z2 are parallel to each other.Preferably, the secondary edges 13 of the primary flow plates 10, which are superimposed along the direction Z2, are arranged in the same plane parallel to the direction Z2 and are arranged in the same position along the tangential direction X2, or even are of the same length along the direction X2. Preferably, the secondary edges 33 of the secondary flow plates 30, superimposed along the direction Z2, are arranged in the same plane parallel to the direction Z2 and are arranged in the same position along the tangential direction X2, or even are of the same length along the direction X2. Preferably, the secondary edges 53 of the membrane-electrode plates 50, superimposed along the direction Z2, are arranged in the same plane parallel to the direction Z2 and are arranged in the same position along the tangential direction X2, or even are of the same length along the direction X2.Preferably, the secondary edges 73 of the end plates 70, superimposed along the direction Z2, are arranged in the same plane parallel to the direction Z2 and are arranged in the same position along the tangential direction X2, or even are of the same length along the direction X2.

[0083] The successive centering notches 12, 32, 52 and 72 of the plates are superimposed along the direction Z2. Here again, "superimposed" has a particular meaning, in that this term does not exclude that, possibly, certain centering notches may be recessed and others protrude along the direction Y2, as described below as a preference. "Superimposed" nevertheless indicates that, overall, the centering notches are aligned along the same axis parallel to the axis Z2. The centering notches together form one of the centering grooves 6. If the seals 80 are provided, the hollow portion 82 also belongs to this centering groove. Preferably, the notches 12 of the primary flow plates, superimposed along the direction Z2, are identical and are arranged in the same position along the directions X2 and Y2.Preferably, the notches 32 of the secondary flow plates 30, superimposed along the direction Z2, are identical and are arranged in the same position along the directions X2 and Y2. Preferably, the notches 52 of the membrane-electrode plates 50, superimposed along the direction Z2, are identical and are arranged in the same position along the directions X2 and Y2. Preferably, the notches 72 of the terminal plates 70, superimposed along the direction Z2, are identical and are arranged in the same position along the directions X2 and Y2.

[0084] 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 along the normal direction Y2, 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 inside 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 the edges 11, 31 has a grid of orifices 19 which extends in the directions X2 and Z2 over all or most of the exchange face 5.

[0085] The exchange orifices 19 are provided to put the outer collector 100 into fluid communication with the circulation fields of reactive operational fluid of the plates 10, or with the circulation fields of reactive operational fluid of the plates 30, or with the circulation fields of cooling operational fluid formed between the adjacent plates 10 and 30. For this purpose, 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, no exchange orifice 19 is advantageously provided. The exchange of operational fluid between the outer collector 100 and the stack 2 is therefore carried out via 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 exchange face 5.

[0086] 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 the centering notches 72 of the end plate 70 in question to each other, so as to open into each of these centering notches 72 of the end plate 70 in question, to thus connect the centering grooves 6.

[0087] 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 projects slightly towards the outside of the stack 2, that is to say in the direction Y2, relative to the adjacent secondary edges 13, 33, 53 or 73. Thus, in Figure 5, it has been illustrated that the exchange edge 11, 31 of each flow field plate 10, 30 projects outwardly from the stack 2, i.e. in the direction Y2, relative to the adjacent secondary edge 13, 33 of the same flow field plate 10, 30, by an amount, called the exchange edge offset "d1-3", which is preferably between 0.05 millimeters and 3 millimeters, preferably between 0.2 millimeters and 1 millimeter.As a result, when the longitudinal seal portions 91 are formed and / or when they are compressed by the collector 100, there is less chance that they will overflow on the side of the exchange face 5, and that they will accidentally block the exchange orifices 19. As a variant, it is however possible to provide that the exchange edge is aligned with the secondary edge, that is to say, extends along the same axis in the direction X1.

[0088] 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 protrude towards the outside of the stack 2, i.e. in the direction Y2, relative 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 protrude towards the outside of the stack 2, i.e. in the direction Y2, relative 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, in Figure 5, 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, relative to the exchange edges 11 and 31 of the adjacent flow field plates 10 and 30, by an amount, 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 protrude towards the outside of the stack 2, that is to say in the direction Y2, relative to the secondary edges 13 and 33 of the adjacent flow field plates 10 and 30 by the same membrane-electrode plate offset value “d50” preferably between 0.1 millimeter and 2 millimeters, preferably between 0.2 millimeter and 1 millimeter.

[0089] Preferably, for at least one of the bipolar plates, and preferably for all of them, 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, i.e. are at the same level along the 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 along the direction Y2.

[0090] Preferably, for at least one of the bipolar plates, and preferably for all of them, 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 to 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 may also, in addition, be smaller in 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 bears transversely on the centering rail 131 to ensure the transverse positioning of the bipolar plate, which can therefore be described as a 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 is made up of the plates 10 and 30 preassembled and added to the stack together, or when the stack is produced by stacking preassembled electrochemical cells.Thus, in Figure 5, 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 to 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 whether, for example, the primary flow field plate 10 is a cathode or an anodic plate, the secondary flow field plate 30 then being respectively an anodic or cathodic plate.

[0091] Preferably, the centering notch 52 of at least one of the membrane electrode plates 50, or of all the membrane electrode plates 50, is flush with the centering notch 32 of the adjacent secondary flow field plate 30. The centering notch 52 of at least one of the membrane electrode plates 50, or of all the membrane electrode plates 50, may also, in addition, be of the same size, in 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 described as a centering notch with contact.

[0092] Alternatively, it may 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 may therefore in this case be described as a non-contact centering notch. Preferably, the centering notch 52 then projects towards the outside of the stack 2 relative to the centering notch 12 of the adjacent primary flow field plate 10. In this case, it may 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 stacking, provision is made, for example, for the membrane-electrode plate 50 to be pre-assembled 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 may 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.

[0093] Preferably, as shown in Figure 4, 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 stacking direction 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 flow field channels, in the direction of the stacking direction Z2. Furthermore, it is advantageous to provide that the thickness E10 is greater than the thickness E30. For example, the thickness E10 is at least 1.5 times greater than the thickness E30, or even twice as great. 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-circuiting 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 withdrawal of the notch 12 and the thickness of the plate 10, in addition to the presence of the insulating and projecting notch 52.

[0094] Preferably, for at least one of the peripheral seals 80, if not for all the peripheral seals 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 to the direction Y2, or slightly projecting in the 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 seals 80, if not for all the seals 80, the exchange edge portion 81 is set back, in the opposite direction to the direction Y2, with respect to the exchange edge 51 of the plate 50 against which the seal 80 is formed. In other words, the edge 51 advantageously projects in the direction Y2 relative to the portion 81.

[0095] Preferably, for at least one of the peripheral seals 80, if not for all the peripheral seals 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 seal 80 is formed. Alternatively, it could be provided that the secondary edge portion 83 is slightly set back in the opposite direction to the direction Y2, or slightly projecting in the direction Y2, relative to the secondary edge 13 or 33 of the plate 10 or 30 against which the seal 80 is formed. Preferably, for at least one of the seals 80, if not for all the seals 80, the secondary edge portion 83 is set back, in the opposite direction to the direction Y2, relative 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.

[0096] Preferably, for at least one of the peripheral seals 80 interposed between a plate 10 and a plate 50, otherwise for all these seals 80 interposed between a plate 10 and a plate 50, the hollow portion 82 is flush in the direction Y2, with the notch 12 of this plate 10 against which the seal 80 is formed. Preferably, this same hollow portion 82 is set back in the direction Y2, with respect to the notch 52 of the plate 50 against which the seal 80 is formed. This may imply that the size of the hollow portion 82 is larger than the size of the notch 52. During manufacture, the hollow portion 82 can thus be crossed by the rail 131 without touching it.

[0097] Preferably, for at least one of the peripheral seals 80 interposed between a plate 30 and a plate 50, otherwise for all these peripheral seals 80 interposed between a plate 30 and a plate 50, the recessed portion 82 is set back in the direction Y2, with respect to 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 manufacture, the recessed portion 82 of the peripheral seal 80 can thus be crossed by the rail 131 without touching it.

[0098] Preferably, for at least one of the end plates 70, and preferably for both plates 70, the exchange edge 71, the secondary edge 73 and the notch 72 are arranged in the same way as the exchange edge 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.

[0099] As shown in Figures 2 and 6, the longitudinal portion 91 of the seal 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 hollow portions 82. In particular, the notches 32 and 52, which project relative to the others, are advantageously encapsulated by the portion 91 of the seal 90. In other words, the seal 90 is interposed along the direction Z2 between the respective perimeter 3 of the successive plates 30 and 50, at the notches 32 and 52, being received in the notches 12 and the hollow portions 82. Thanks to these arrangements, not only is optimal sealing of the fluid connection between the collector 100 and the face 5 ensured, but also the risk of electric arcing within the groove 6 is reduced.

[0100] 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 for the seal portions 91 and 92.

[0101] To manufacture the fuel cell 1, a method as defined below and as illustrated in Figures 7 to 9 can be implemented.

[0102] As shown in Figure 7, the support plate 111 is preferably arranged, 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 jig 130, comprising the rails 131, is temporarily installed. Here, only two rails 131 are provided for the jig 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 jig 130 also comprises a fixing base 132, to which the rails 131 are fixedly attached.

[0103] 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 attached 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 along the direction Y2.

[0104] 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.

[0105] 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.

[0106] At this stage, additional peripheral centering templates may be provided, arranged opposite other sides 4 of the stack 2, if these other sides 4 have corresponding centering grooves. Finally, centering means internal to the stack 2 may be provided, such as rods parallel to the direction Z2 and passing through the stack 2 from the inside, from the plate 1 11.

[0107] Once the template(s) 130 are installed, the plates 10, 30, 50 and 70 and the joints 80 are stacked to form the 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, some plates are stacked individually, for example the plates 50 and 70, while other plates, namely for example the plates 10 and 30, are pre-assembled in pairs before being stacked. Preferably, each gasket 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 stack 2, a complete bipolar plate is added to stack 2, including two adjacent pre-assembled plates 10 and 30 and two joints 80 formed respectively on plates 10 and 30.

[0108] 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 along the directions X2 and Y2, while the other centering notches, set back from the rail 131 along the direction Y2, are only crossed by the rail 131 along the 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, whereas the notches 12 and the recessed portions 82, respectively of the primary flow field plates 10 and of the peripheral seals 80, more set back, are at a distance from the rail 131 by being crossed only by the rail 131 in the direction Z2, and are therefore centering notches without contact. The cooperation of the rails 131 with the centering notches ensures that, once the stack 2 is completed, each plate of the stack 2 is correctly positioned against the adjacent plate, in particular in the directions X2 and Y2.

[0109] To carry out the stacking, as shown in Figure 7, it is advantageous to 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. A current collector and a planar sealing gasket, not shown, are then advantageously stacked.

[0110] 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 to the direction Z2.

[0111] One of the plates 50 is then stacked, 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 assembled. A pre-assembled bipolar assembly is then stacked comprising a plate 10, carrying a seal 80 facing in the direction of the already stacked plate 50, a plate 30 fixed to the plate 10 in the direction Z2, and a second seal 80 formed on the plate 30 in the direction Z2. This pre-assembled 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, alternately following a pre-assembled bipolar assembly and a plate 50. Once the last plate 50 is stacked, a last flow field plate 10 is added, on which another current collector and possible sealing gasket are stacked.The second end plate 70 is then stacked.

[0112] Stack 2 is then completed, and is kept centered using rails 131, still in place.

[0113] Once the stack 2 is completed and while the joint 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 slipping the support plate 112 onto the tie rods 113.

[0114] 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 similar manner 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 threaded onto the rails 131, in order to be guided in sliding by the rails in the direction Z2. To install the support plate 112, the plate is advantageously threaded 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 the stack 2.

[0115] Once the stack 2 is arranged 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 put into 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 tightening the nuts of the tie rods to the torque.

[0116] 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, 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 with respect to the stack 2. The removal of the rails 131 is therefore particularly easy. We then arrive at the configuration of figure 3.

[0117] 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, by casting, injecting or overmolding the seal 90 in the liquid or pasty state into the grooves 6 and 8, then curing the seal 90. To form the seal 90 while it is in the liquid or pasty state, it is preferred that the stack 1 be 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 by conforming to the interior contours of the grooves 6 and 8.

[0118] To form the seal 90, preferably, as shown in Figure 6, a first bead 95 of a first material in the liquid or pasty state is first applied in the grooves 6 and 8, over the entire perimeter of the future seal 90. The first material is advantageously based on silicone, or another suitable elastomer, which is not crosslinked during its application to be in the liquid or pasty state and thus to fit the bottom of the grooves 6 and 8, in particular, by encapsulating the notches 32 and 52 which are projecting. A low viscosity material is advantageously chosen, to give it a self-leveling and / or filling character. This ensures that the material fits 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 are projecting and others are recessed.Despite its low viscosity, the material can be applied very precisely, because it is prevented from spreading in the X2 direction by groove 6 and in the Z2 direction by groove 8.

[0119] Once the first bead 95 is applied, it is cured in situ. In the case of a silicone, curing 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 fits the grooves 6 and 8 around the entire perimeter of the joint 90.

[0120] 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 apply the second bead 96 while the first bead 95 is only partially hardened, in order to ensure good cohesion between the beads 95 and 96. The second bead 96 covers the first bead over the entire periphery of the joint 90, constituted by the beads 95 and 96. The second bead 96 is formed so as to project relative to the grooves 6 and 8, over the entire perimeter of the joint 90.

[0121] The second bead 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 for forming the second bead 96, in the liquid or pasty state, is more viscous than the first material for forming 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 retain a raised shape over the first bead 95, even when the second material is not yet cured. 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 cured in situ, for example by crosslinking the silicone at room temperature. This results in the configuration shown in Figure 2.

[0122] Although the method of forming the seal 90 set forth above is preferred, provision may alternatively be made to form the seal 90 in a single pour of material, or to form the seal 90 by other suitable methods.

[0123] Once the seal 90 is formed, the fluid connection of the outer collector 100 with the exchange face 5 is made. For this, the collector 100, in particular the connector 101, is brought against the exchange face 5, by approaching the connector 101 of the stack parallel to the direction Y2. At the very least, the approach movement of the connector 101 has a component along the direction Y2. The connector 101 is made to correspond 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 contact with the seal 90 by means of the bead 96. At the moment when the collector 100 is attached against the exchange face 5, it is advantageously provided that the seal 90 has already hardened or has already been crosslinked, or in any case is no longer sticky, so that the collector 100 does not adhere to the seal 90, but is simply in sealing contact with the seal 90.

[0124] Finally, the external collector 100 is 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. This results in the configuration of FIG. 1. 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

CLAIMS 1 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 constitute 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 exchange edges (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 stacking direction (Z2);an external collector (100), which is fluidically 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); 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 a seal of the fluidic connection between the external collector (100) and the stack (2); and a fixing system (102), separate from the collector seal (90), the external collector (100) being fixed to the stack (2) via the fixing system (102);wherein: 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 stacking direction (Z2); and the manifold 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 manifold (100) to ensure the sealing of the fluid connection between the outer manifold (100) and the stack (2).; 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 open onto 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 stack (2) being carried out via the exchange orifices (19). 3.- Fuel cell (1) according to any one of the preceding claims, wherein 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). 4.- 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). 5.- Fuel cell (1) according to any one of claims 3 or 4, wherein, 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). 6.- Fuel cell (1) according to any one of the preceding claims, wherein: the flow field plates (10, 30) comprise 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 secondary flow field plate (30). 7.- 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 or set back towards the inside of the stack (2), relative to the centering notch (32) of the adjacent secondary flow field plate (30), and projecting outwards from the stack (2), relative to the centering notch (12) of the adjacent primary flow field plate (10). Fuel cell (1) according to any one of the preceding claims, wherein, 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, wherein the stack (2) further comprises peripheral seals (80), each peripheral seal (80) being interposed between one of the flow field plates (10, 30) and one of the membrane-electrode plates (50) along 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 membrane-electrode plate (50) along the stacking direction (Z2), being flush with the exchange edge (11, 31) of said flow field plate (10, 30) or set back towards the inside 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) along the stacking direction (Z2),the hollow portion (82) being set back towards the inside of the stack (2) relative to the centering notch (52) of the membrane-electrode plate (50) and being flush 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, wherein, 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, in projection in a projection plane (P2) which is orthogonal to the stacking direction (Z2). Fuel cell (1) according to any one of the preceding claims, wherein: the plates (10, 30, 50, 70) of the stack (2) comprise an end plate (70), terminating the stack (2) along 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 manifold seal (90) comprises a transverse seal 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 seal portion (91), so that the transverse seal portion (92) is interposed between the end plate (70) and the outer manifold (100) to ensure fluid sealing of the fluid connection between the outer manifold (100) and the stack (2). A 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 seal (90) is not yet formed, installing a centering rail (131), which is parallel to the stacking direction (Z2) and which is adapted to be received in the respective centering notch (12, 32, 52, 72) of the plates (10, 30, 50, 70);successively stacking the plates (10, 30, 50, 70) to form the stack (2) while the centering rail (131) is installed, by guiding the plates (10, 30, 50, 70) by mechanical cooperation of 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 to the stacking direction (Z2); removing the centering rail (131), once the stack (2) is completed, by moving the centering rail (131) away from the stack (2), transversely to the stacking direction (Z2); placing the collector seal (90), with the longitudinal seal portion (91) formed in the centering groove (6), once the stacking (2) has been completed and the centering rail (131) has been removed;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 interposition of the collector seal (90), including the longitudinal seal portion (91), 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); and; fixing the outer collector (100) to the stack (2) using the fixing system (102). Method according to claim 12, wherein: installing the centering rail (131) comprises fixing the centering rail (131) on a support plate (111) belonging to the fuel cell (1); successively stacking the plates (10, 30, 50, 70) comprises stacking 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) comprises separating the centering rail (131) from the support plate (111).A method according to any one of claims 12 or 13, wherein placing the manifold seal (90) comprises: applying a first bead (95), of elastomer in an uncrosslinked state, in the centering groove (6), to form the longitudinal seal portion (91); and in-situ crosslinking the uncrosslinked elastomer of the first bead (95), while the first bead (95) has been applied. A method according to claim 14, wherein placing the manifold seal. (90) further comprises, once the first bead (95) has been applied: applying a second bead (96), made of elastomer in a non-crosslinked state on the first bead (95), such 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, at the moment 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.

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