Fuel cell and method for manufacturing same

Abstract

The invention relates to a fuel cell (1) comprising: a stack of plates (10, 30, 50, 70), each plate comprising a respective exchange edge to form an exchange face (5); an external collector in fluid connection with the exchange surface; and a collector seal (90) surrounding the exchange surface (5) in order to ensure the sealing of the fluid connection. In order to ensure that the collector seal has a better controlled shape and is easier to use, each plate comprises a respective centering recess adjacent to the exchange edge to form a centering groove (6) connected to said exchange face. The collector seal comprises a longitudinal seal portion (91) formed in the centering groove and ensuring fluid connection tightness.

Description

Field of the Invention

[0001] The present invention includes fuel cells and methods of making such fuel cells. Background Art

[0002] US2001055708A1 describes a fuel cell comprising a horizontal stack of electrochemical cell components, the components comprising flow field plates, anode and cathode supports, anode and anode catalysts, and a proton exchange membrane. Reactant gases such as oxygen or hydrogen are supplied to the stack via a collector located at the top of the stack. A sealing system is placed between the collector and the stack. Although the edges of the electrochemical cell components are in irregular positions, i.e., protruding or retracted relative to other components, the sealing system includes a first portion forming a low-temperature cross-linked silicone bridge, the first portion matching the shape of the protruding and recessed edges to form a flat and regular surface. The sealing system includes a second portion formed by a foamed silicone layer, the second portion being placed between the flat and regular surface of the first portion and the lower surface of the collector and extending over the entire periphery of the collector.

[0003] However, in practice, the need to use low-viscosity silicones to allow them to perfectly conform to irregularities in the stack and form bridges can mean that the silicone expands in width, resulting in a seal that, while relatively flat on the surface, is often relatively wide and imprecise in shape. This lateral expansion of the seal can unintentionally obstruct part of the exchange surface between the stack and the collector, reducing fuel cell efficiency. Summary of the Invention

[0004] The present invention aims to solve the disadvantages of the prior art by proposing a new fuel cell whose collector seal has a better controlled shape, thereby facilitating the application of the collector seal.

[0005] The present invention includes a fuel cell comprising:

[0006] a stack comprising plates, the plates of the stack comprising flow field plates and membrane electrode plates, the plates of the stack being stacked along a stacking direction to form an electrochemical cell, each of the plates being oriented perpendicular to the stacking direction and lying flat on an adjacent plate, each of the plates comprising a respective exchange edge, the exchange edges being parallel to one another and jointly forming an exchange face belonging to the stack, the exchange face extending parallel to the stacking direction;

[0007] an external collector in fluid connection with the stack, said external collector covering the exchange surface by being attached against the stack, for exchanging the working fluid between the external collector and the stack through the exchange surface;

[0008] - a collector seal surrounding the exchange surface and interposed between the stack and the external collector to ensure a fluid-tight connection between the external collector and the stack; and - preferably, a fixing system, different from the collector seal, by which the external collector is fixed to the stack.

[0009] Each of said plates comprises a respective centering notch adjacent to said exchange edge, said centering notches together forming a centering groove belonging to said stack, said centering groove adjoining said exchange face and extending parallel to the stacking direction;

[0010] The collector seal comprises a longitudinal seal parallel to the stacking direction, which is formed in the centering groove such that the longitudinal seal is arranged between the stack and the external collector to ensure a fluid-tight connection between the external collector and the stack.

[0011] The basic concept of the present invention is to form the collector seal in the centering groove so that the collector seal contained within the centering groove has a low tendency to lateral expansion during its formation, particularly even when the material used to form the collector seal has a very low viscosity. The shape of the collector seal is well controlled, making it easier to form a seal that matches the centering grooves of the plate, even if some centering grooves are recessed or protruding relative to one another. This makes it easier to ensure a tight seal with the working fluid.

[0012] Another advantage is that during the manufacture of the stack, certain centering recesses can be used to ensure the centering of the plates. In other words, during the stacking of the plates to form the stack, when the collector seal has not yet been formed, a temporary centering rail can be installed, which mechanically cooperates with some of the centering recesses and acts as a template to ensure that the corresponding plates are correctly positioned laterally with respect to the stacking direction. The centering rail is parallel to the stacking direction. During the stacking of the plates, the centering recesses of the plates mechanically cooperate with the centering rail, and at least some of the plates are guided to slide along the centering rail in the stacking direction. For the other plates, the centering rail can pass through the centering recess in the stacking direction. Once the stacking of the plates is completed, the centering rail is removed so that the centering recesses are free to form the collector seal in the centering recesses. Therefore, the centering recess has both the function of centering the plates and the function of accommodating the longitudinal sealing portion.

[0013] Preferably, at least one of the flow field plates forms an exchange opening, which is formed at the exchange edge of the flow field plate to open on the surface of the exchange surface and be covered by the external collector, and the exchange of working fluid between the external collector and the stack body is carried out through the exchange opening.

[0014] Preferably, the plates of the stack comprise respective secondary edges parallel to the exchange edge and connected to the exchange edge by means of the centering recesses.

[0015] Preferably, for at least one plate of the stack, the exchange edge projects towards the outside of the stack relative to the secondary edge.

[0016] Preferably, for at least one of the membrane electrode plates, a secondary edge of the membrane electrode plate protrudes toward the outside of the stack relative to a secondary edge of an adjacent flow field plate.

[0017] Preferably, the flow field plates include a main flow field plate and a secondary flow field plate. Preferably, at least one of the main flow field plates is adjacent to one of the secondary flow field plates to form a bipolar plate together with the secondary flow field plate. Preferably, for at least one of the bipolar plates: the exchange edge of the main flow field plate and the exchange edge of the secondary flow field plate are flush with each other. Preferably, the centering notch of the main flow field plate is recessed toward the interior of the stack relative to the centering notch of the secondary flow field plate.

[0018] Preferably, the centering recess of at least one membrane electrode plate is flush with or recessed toward the interior of the stack relative to the centering recess of its adjacent secondary flow field plate, and protrudes toward the exterior of the stack relative to the centering recess of its adjacent primary flow field plate.

[0019] Preferably, for at least one of the membrane electrode plates, an exchange edge of the membrane electrode plate protrudes toward the outside of the stack relative to an exchange edge of an adjacent flow field plate.

[0020] Preferably, the stack further comprises circumferential seals, each of which is positioned between one of the flow field plates and one of the membrane electrode plates along the stacking direction. Preferably, each of the circumferential seals comprises: an exchange edge portion positioned between the exchange edge of the flow field plate and the exchange edge of the membrane electrode plate along the stacking direction, and flush with the exchange edge of the flow field plate or recessed toward the interior of the stack relative to the exchange edge of the flow field plate; and a recessed portion positioned between the centering recess of the flow field plate and the centering recess of the membrane electrode plate along the stacking direction, the recessed portion recessed toward the interior of the stack relative to the centering recess of the membrane electrode plate, and flush with the stack relative to the centering recess of the flow field plate or recessed toward the interior of the stack.

[0021] Preferably, for at least one of the plates of the stack, the centering recess has a contour in the shape of a circular arc in projection onto a projection plane perpendicular to the stacking direction.

[0022] Preferably, the plates of the stack comprise end plates which terminate the stack in the stacking direction.

[0023] Preferably, the exchange edge of the end plate is provided with a transverse groove, which is connected to the centering groove via a centering recess leading to the end plate; and the collector seal includes a transverse sealing portion perpendicular to the stacking direction, which is formed in the transverse groove and joined to the longitudinal sealing portion so that the transverse sealing portion is located between the end plate and the external collector, thereby ensuring a fluid-tight connection between the external collector and the stacking body.

[0024] The present invention also includes a method for manufacturing a fuel cell as described above. The method comprises:

[0025] - when the plates of the stack have not yet been stacked and the collector seal has not yet been formed, installing centering rails which are parallel to the stacking direction and can be accommodated in corresponding centering recesses of the plates;

[0026] - while installing the centering rail, successively stacking the panels to form a stack, guiding the panels by mechanical cooperation of at least one centering recess with the centering rail, so that the centering rail ensures transverse centering of the panels with respect to the stacking direction;

[0027] - once the stack has been prepared, removing the centering rail by moving it away from the stack transversely with respect to the stacking direction;

[0028] - once the stack has been prepared and the centering rails removed, the collector seal is installed, wherein the longitudinal seal is formed in the centering groove;

[0029] - once the collector seal is mounted, ensuring a fluid-tight connection between the external collector and the stack by placing the external collector against the stack so as to cover the exchange surface and positioning the collector seal comprising the longitudinal seal between the stack and the external collector; and

[0030] - Preferably, said external collector is fixed to said stack using said fixing system.

[0031] Preferably, the installation of the centering rail comprises fixing the centering rail to a support plate belonging to the fuel cell. Preferably, the continuous stacking of the plates comprises stacking one of the plates on the support plate parallel to the stacking direction. Preferably, the removal of the centering rail comprises detaching the centering rail from the support plate.

[0032] Preferably, the installation of the collector seal comprises:

[0033] - applying a first bead made of an elastomer in a non-crosslinked state into said centering groove to form a longitudinal seal; and

[0034] - Once said first bead is applied, the non-crosslinked elastomer of said first bead is crosslinked in situ.

[0035] Preferably, the installation of the collector seal further comprises: once the first bead is applied, applying a second bead made of an elastomer in a non-cross-linked state onto the first bead, so that the second bead protrudes toward the outside of the stack relative to the exchange surface, and when the second bead is applied, the elastomer of the second bead has a higher viscosity than the elastomer of the first bead when the first bead is applied. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The present invention and other advantages thereof will become apparent from the following description of embodiments consistent with the principles of the invention with reference to the accompanying drawings, in which:

[0037] [ Figure 1 ] Figure 1 A perspective view showing a fuel cell according to an embodiment of the present invention is shown.

[0038] [ Figure 2 ] Figure 2 is similar to Figure 1 A view of the , where the outer collector has been removed.

[0039] [ Figure 3 ] Figure 3 is similar to Figure 1 View of the outer collector and collector seal removed.

[0040] [ Figure 4 ] Figure 4 It is shown from another low angle Figure 3 Detailed stereogram.

[0041] [ Figure 5 ] Figure 5 Shown Figure 1-4 A top view of a partial structure of a fuel cell stack.

[0042] [ Figure 6 ] Figure 6 is similar to Figure 5 , which also shows the collector seal.

[0043] [ Figure 7 ] Figure 7 is similar to Figure 1 A perspective view showing a manufacturing step of a fuel cell.

[0044] [ Figure 8 ] Figure 8 is similar to Figure 1 A perspective view showing another manufacturing step of a fuel cell.

[0045] [ Figure 9 ] Figure 9 is similar to Figure 1 A perspective view showing another manufacturing step of a fuel cell. DETAILED DESCRIPTION

[0046] Figure 1-3 A fuel cell 1 according to one embodiment of the present invention is shown. Figure 4-6 As shown in more detail, the fuel cell 1 includes a stack 2. The stack 2 includes: a main flow field plate 10, a secondary flow field plate 30, a membrane electrode plate 50, and preferably an end plate 70 and a circumferential seal 80. The fuel cell 1 also includes: Figure 1 The external collector 100 is shown, and Figure 2 and Figure 6 The collector seal 90 is shown. The fuel cell 1 also advantageously comprises Figure 1-3 The compression system shown in FIG. 1 includes, for example, support plates 111 and 112 , a pull rod 113 and a spring 114 .

[0047] To manufacture the fuel cell 1, specifically the centering of the different plates 10, 30, 50 and 70, as shown Figure 7-9 As shown, a circumferential centering template 130 is used, said centering template 130 comprising said centering rails 131 which are at least partially removed once the stack 2 has been prepared.

[0048] A stacking direction Z2 is defined according to which the plates 10 , 30 , 50 and 70 and the circumferential seal 80 are stacked to form the stack 2 . The stacking direction Z2 is perpendicular to the plates 10 , 30 , 50 and 70 and is fixed relative to the stack 2 .

[0049] like Figure 1-3As shown, the support plates 111 and 112 are arranged on either side of the stack 2 along the stacking direction Z2. The springs 114 are disposed between the stack 2 and the support plates 112 along the stacking direction Z2. The support plates 111 abut the stack along the stacking direction Z2. The stack 2 abuts against the springs 114, which are distributed on the surface of the support plates 112. The springs 114 are disposed between the support plates 112 and the stack 2 and abut against the support plates 112 along the stacking direction Z2. Tie rods 113, each parallel to the stacking direction Z2, are distributed around the stack 2. The tie rods 113 connect the support plates 111 and 112 together, maintaining each tie rod in position relative to the other along the stacking direction Z2. The springs 114 maintain the stack 2 in a compressed state along the stacking direction Z2. The springs 114 advantageously allow for dimensional changes in the stack 2 along the stacking direction Z2, which may occur during use of the fuel cell, particularly under the influence of thermal stress. In this example, six pull rods 113 and eight springs 114 are provided, but these elements can have different numbers. Alternatively, another type of compression system can be provided. For example, the compression system optionally includes support plates located on both sides of the stack, the entire stack and the support plates are contained in a housing, and the springs are placed between the surface of the housing and at least one support plate to compress the stack. For example, the principle of this alternative compression system is described in document WO2007 / 080472. Other compression systems are described in document US20090162728, or the situation without springs is described in document US20100261088 or document EP1597786.

[0050] Each plate 10, 30, 50 and 70 is flat and perpendicular to the stacking direction Z2 along its own plane. The plates 10, 30, 50 and 70 are parallel to each other and to the plates 111 and 112. Figure 3 and Figure 4 As can be better seen in the figure, each plate 10, 30, 50 or 70 lies flat on an adjacent plate, i.e. next to the plate that immediately follows it. Due to this flat arrangement, the plates 10, 30, 50 or 70 are stacked edge to edge with the adjacent plates, and a seal 80 may be inserted between two adjacent plates. More specifically, each circumferential seal 80 is arranged between one of the membrane electrode plates 50 and one of the flow field plates 10 or 30. Each circumferential seal 80 is arranged between the relevant plates and extends flat along a plane perpendicular to the stacking direction Z2. In the example shown in the figure, the adjacent flow field plates 10 and 30 are stacked together without a circumferential seal 80 being arranged between them.

[0051] The different plates of the stack 2 are arranged in a specific order along the stacking direction Z2 to form a group of adjacent plates, and each group of adjacent plates forms a corresponding electrochemical cell. Each electrochemical cell of the stack 2 includes, in order along the stacking direction Z2: a secondary flow field plate 30, a possible circumferential seal 80, a membrane electrode plate 50, another possible circumferential seal 80 and a mainstream field plate 10. For the operation of the electrochemical cell, the stack 2 is designed to be supplied with a working fluid, including: a cathode reaction fluid, including, for example, hydrogen; an anode reaction fluid, including, for example, oxygen (which may be contained in the air); and a cooling fluid when necessary. In each electrochemical cell, the cathode reaction fluid reacts with the anode reaction fluid to generate electricity. The cooling fluid is used to cool the stack 2. Further measures are taken to remove these working fluids and / or products produced by the reaction of these working fluids after the working fluids pass through the stack 2.

[0052] In this example, for simplicity, only 9 electrochemical cells are shown. However, in practice, the fuel cell 1 may have a greater number of electrochemical cells, for example 50-500 electrochemical cells.

[0053] Each plate 10, 30, 50 and 70 has a periphery 3 that extends along a plane perpendicular to the stacking direction Z2. Each plate 10, 30, 50 and 70 extends only within its periphery 3. The shape of each periphery 3 is generally rectangular. Advantageously, the periphery 3 of each plate of the same type of stack 2 has the same shape or a similar shape and is superimposed with the peripheries 3 of all other plates of the same type along the stacking direction Z2, that is, aligned along the stacking direction Z2. For example, all membrane electrode plates 50 have the same periphery 3 and are superimposed with the peripheries 3 of other membrane electrode plates 50 along the stacking direction Z2. For example, all mainstream field plates 10 have the same periphery 3 and are superimposed with the peripheries 3 of other mainstream field plates along the stacking direction Z2, and the periphery 3 of the mainstream field plate 10 may be different from the periphery 3 of the membrane electrode plate 50, and so on. Specifically, relative to the periphery of another type of plate, the periphery 3 of the first type of plate is wholly or partially recessed toward the interior of the stack 2, or protrudes toward the outside of the stack 2. For example, the outer periphery 3 of the membrane electrode plate 50 is defined to protrude toward the outside of the stack 2 relative to the outer periphery 3 of the flow field plate 10 .

[0054] The connection of the peripheries 3 of all the plates 10, 30, 50, and 70 of the stack forms different side faces 4 of the stack 2, and the side faces 4 are parallel to the stacking direction Z2. Since the peripheries 3 of the plates of the stack 2 have a generally rectangular shape, there are four side faces 4. Some portions of the peripheries 3 of the plates 10, 30, 50, and 70 are concave or protruding, and the side faces 4 are irregular. The concave peripheries 3 form transverse grooves perpendicular to the stacking direction Z2, and the protruding peripheries 3 form ridges perpendicular to the stacking direction Z2 and parallel to the transverse grooves.

[0055] from Figure 2 and Figure 3 It can be seen more clearly that at least one side face 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 side face 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 accompanying drawings show only one of the side faces 4 of the stack 2 provided with such an element. However, preferably, one or more other side faces 4 include such an element, or at least include a centering groove 6. Usually, it will be provided that two opposite side faces 4 of the stack 2 will have such elements to form the inlet and outlet of a given working fluid. It is also possible to provide two exchange faces 5 in one side face 4, which are arranged side by side in the tangential direction of the face perpendicular to the stacking direction Z2, in which case, for example, there are three or four centering grooves 6 and two or three secondary faces 7.

[0056] In addition to the at least one exchange surface 5 , the stack may comprise, in a known manner, one or more internal channels or internal collectors, each formed by superimposed openings arranged in the stack of plates, for the circulation and distribution of one or more other working fluids.

[0057] For each exchange surface 5 , a normal direction Y2 perpendicular to the exchange surface 5 and the stacking direction Z2 and pointing to the outside of the stack 2 is defined, as well as a tangent direction X2 parallel to the exchange surface 5 and perpendicular to the stacking direction Z2.

[0058] Preferably, the exchange surface 5 , the centering groove 6 and the secondary surface 7 extend from one end to the other end of the stacking body 2 along the stacking direction Z2 and are parallel to the stacking direction Z2 .

[0059] Each centering groove 6 extends parallel to the stacking direction Z2 and is recessed toward the interior of the stack 2 to form an opening in the normal direction Y2. The exchange surface 5 is disposed between two of the centering grooves 6 and is bounded by the centering grooves 6 in the tangential direction X2. Each centering groove 6 is disposed between the exchange surface 5 and a secondary surface 7. In the tangential direction X2, the secondary surface 7 is preferably bounded by the centering groove 6 and extends to, for example, one end of the side surface 4. Preferably, the exchange surface 5 and the secondary surface 7 are parallel to each other and to the tangential direction X2.

[0060] On the same side 4 as that carrying the exchange surface 5, the stacking body further preferably includes one or more transverse grooves 8, here two transverse grooves 8. Each transverse groove 8 is recessed toward the interior of the stacking body 2 so as to form an opening in the normal direction Y2. Each transverse groove 8 connects two centering grooves 6 together. To this end, each transverse groove 8 preferably extends perpendicular to the stacking direction Z2, specifically, extends parallel to the tangential direction X2. The exchange surface 5 is arranged between the two transverse grooves 8 and is defined by the transverse grooves 8 in the stacking direction Z2. The centering groove 6 and the transverse grooves 8 together surround the exchange surface 5 in a closed contour.

[0061] like Figure 2 As shown, the collector seal 90 is preferably formed as a whole with the stack 2, and the external collector 100 is attached to the stack 2 and abuts against the collector seal 90, as shown. Figure 1 shown.

[0062] Advantageously, the collector seal 90 is distinct from the external collector 100. Preferably, the collector seal 90 is not attached to the external collector 100, in particular in that the collector seal 90 does not adhere to or is not anchored to the external collector 100. Preferably, the external collector 100 rests only against the collector seal 90.

[0063] Preferably, the collector seal 90 is adhered to and / or anchored to the stack 2 so as to be integral with the stack 2 .

[0064] The collector seal 90 surrounds the exchange surface 5. To this end, the collector seal 90 comprises two longitudinal seals 91 and two transverse seals 92. Each longitudinal seal 91 (e.g. Figure 6) extends parallel to the stacking direction Z2. Each of the longitudinal seals 91 is arranged on both sides of the exchange surface 5 along the tangential direction X2, and each of the longitudinal seals 91 is formed in any one of the centering grooves 6, and covers the entire height of the exchange surface 5 along the stacking direction Z2. Each of the transverse seals 92 connects the two longitudinal seals 91 together, for example, it extends parallel to the tangential direction X2. The transverse seals 92 are connected to the longitudinal seals 91 at both ends thereof. Then, the transverse seals 92 are arranged on both sides of the exchange surface 5 along the stacking direction Z2. In general, the collector seal 90 has a quadrilateral shape, or at least has a closed contour around the exchange surface 5.

[0065] Preferably, on the portion of the centering groove 6 extending along the exchange surface 5, each longitudinal sealing portion 91 completely fills the centering groove 6 it occupies, and the longitudinal sealing portion 91 matches the shape of the bottom of the centering groove 6. Similarly, preferably, on the portion of the transverse groove 8 extending along the exchange surface 5, each transverse sealing portion 92 completely fills the transverse groove 8 it occupies, and the transverse sealing portion 92 matches the shape of the bottom of the transverse groove 8. Figure 6 As shown, in the normal direction Y2, the collector seal 90 slightly protrudes to ensure close contact with the external collector 100. Specifically, in the normal direction Y2, the longitudinal seal portion 91 slightly protrudes outside the centering groove 6. Specifically, in the normal direction Y2, the transverse seal portion 92 slightly protrudes outside the transverse groove 8.

[0066] The exchange surface 5 is configured to allow the exchange of at least one working fluid, preferably a single working fluid, with the external collector 100. To this end, the external collector 100 is fluidically connected to the stack 2, specifically to the exchange surface 5, preferably only to the exchange surface 5. Figure 1 As shown, in order to be fluidically connected to the stack 2, the external collector 100 is attached to the stack 2 so that it covers the exchange surface 5. In order to ensure the sealing of this fluid connection, the collector seal 90 is provided between the external collector 100 and the stack 2 in the direction Y2.

[0067] "Exchange" refers to the introduction of the working fluid into the stack 2 through the exchange surface 5 and the subsequent supply of the working fluid by the external collector 100, or the discharge of the working fluid from the stack 2 through the exchange surface 5 and the subsequent collection of the working fluid by the external collector 100. On the surface of the exchange surface 5, the exchange of the working fluid occurs parallel to the normal direction Y2.

[0068] In practice, Figure 1 As shown, the external collector 100 comprises a connector 101, for example, having a funnel shape. A first opening of the connector 101, preferably trumpet-shaped, covers the exchange surface 5 to be fluidically connected thereto. Preferably, a second opening of the connector 101, preferably narrower than the first opening, is connected to an inlet or outlet pipe for the working fluid. The first opening connected to the exchange surface 5 is advantageously defined by a closed contour edge belonging to the connector 101, extending in planes X2, Z2 perpendicular to the normal direction Y2, and advantageously having a shape complementary to the shape of the centering groove 6 and the transverse groove 8. To ensure the tightness of the connection, this closed contour edge belonging to the external collector is in contact with the collector seal 90 around the entire exchange surface 5, specifically with the longitudinal sealing portion 91 and the transverse sealing portion 92 of the collector seal 90. The collector seal 90 is preferably made of an elastomer, such as silicone, which has a slight elasticity to fit the external collector 100 and thus ensure the tightness. Therefore, the closed contour edge defining the first opening of the connector 101 has a support surface, and the support surface is in close contact with the collector seal 90 over the entire closed contour edge, so that the collector seal 90 extends on the same contour. The support surface of the closed contour edge defining the first opening of the connector 101 can be a plane extending in a plane X2, Z2 perpendicular to the normal direction Y2, so that the support surface has a strip shape along the closed contour. The support surface has one or more ribs, and the ribs protrude relative to the plane X2, Z2 perpendicular to the normal direction Y2, preferably one or more ribs protruding along the contour, and if there are multiple ribs, the multiple ribs are parallel to each other along the contour. Therefore, the ribs extending over the entire contour can be recessed into the material of the collector seal 90 over the entire closed contour to improve the reliability of the contact seal between the connector 101 and the collector seal 90.

[0069] Preferably, the external collector 100 may further include a fixing system 102 , wherein the fixing system 102 is formed integrally with the connector 101 , and the external collector 100 may be fixed to the fuel cell 1 and / or the stack 2 via the fixing system 102 .

[0070] The securing system 102 is distinct from the collector seal 90. This allows the collector seal 90 to exclusively provide the sealing function. In other words, the collector seal 90 does not perform any securing functions. Because sealing and securing are provided by separate components, each function can be clearly distinguished. This provides a particularly simple and reliable design that is also very easy and quick to implement.

[0071] Here, the fixing system 102 is designed to be fixed to the fuel cell 1 by being fixed to the support plates 111 and 112. In other words, in this case, the external collector 100 is fixed to the stack 2 because the fixing system 102 is fixed to the support plates 111 and 112. Alternatively, the external collector 100 is fixed to the stack 2 because the fixing system 102 is fixed to only one of the support plates 111 and 112, or the fixing system 102 is fixed to another element of the fuel cell 1, in particular an element of the compression system, or to the housing of the fuel cell 1, or even to the stack 2 itself. Preferably, the fixing system 102 fixes the external collector 100 to the stack, and not to the centering groove 6 reserved for the collector seal 90.

[0072] Preferably, the fixing system 102 comprises a base 103, and the fixing system 102 is fixed to a fixing edge 115 of the support plate 111 by the base 103. Preferably, the base 103 is attached to the fixing edge 115 in a direction parallel to the normal direction Y2, and the fixing edge 115 extends parallel to the exchange surface 5 and / or along the exchange surface 5 in the stacking direction Z2.

[0073] Preferably, the fixing system 102 includes a base 104, via which the fixing system 102 is fixed to a fixing edge 116 of the support plate 112. Preferably, the base 104 is attached to the fixing edge 116 in a direction parallel to the normal direction Y2, with the fixing edge 116 extending parallel to and / or along the exchange surface 5 in the stacking direction Z2. In a direction opposite to the normal direction Y2, the connector 101 is abutted against the exchange surface 5 by the bases 103 and 104. Preferably, at least one of the bases 103 or 104 is movable in the stacking direction Z2 relative to the other base and / or relative to the connector 101, to allow the stack 2 to change in size along the stacking direction Z2 during use.

[0074] At least one base of the fixing system as described above may be fixed to a fixing edge of one or the other end plate 70 as described below.

[0075] Preferably, the stack 2 includes two end plates 70, which are arranged at the ends on both sides of the stack 2 along the stacking direction Z2. In other words, each end plate 70 ends the stack along the stacking direction Z2. This does not exclude that other plates are adjacent to either side of the stack 2 by being adjacent to the end plates 70. The end plates 70 withstand the force applied to the stack 2 by the compression system. In this example, the stack 2 is supported on the support plate 111 in a direction opposite to the stacking direction Z2 by one of the two end plates 70, and the stack 2 is supported on the spring 114 by the other of the two end plates 70. Taking into account the current involved in the stack 2, preferably, the end plate 70 is electrically insulating, has an electrically insulating coating, or has at least a portion (the portion in contact with the stack) that is electrically insulating. Advantageously, it can be provided that, along the stacking direction Z2, a channel for the working fluid passes through the support plate 111 and the end plate 70 resting against the support plate 111, in order to supply the stack 2 with the working fluid and / or to remove the working fluid from the stack 2. Thus, in addition to the connection made using the exchange surface 5 and the external collector 100, an additional connection for the working fluid can be established via the end plate 70.

[0076] Preferably, each of the membrane electrode plates 50 is composed of a membrane electrode assembly, and in certain embodiments includes an outer frame forming the periphery 3 of the membrane electrode plate 50. In view of the current involved in the stack 2, the outer frame is preferably electrically insulating. The membrane electrode plate 50 also includes a membrane surrounded by the outer frame, thereby allowing protons to be exchanged from one side of the membrane electrode plate 50 to the other side. One side of the membrane, that is, a side oriented along the stacking direction Z2, is covered by a cathode catalyst layer, and the cathode catalyst itself is covered by a cathode gas diffusion layer. The other side of the membrane, that is, a side oriented in the direction opposite to the stacking direction Z2, is covered by an anode catalyst layer, and the anode catalyst layer itself is covered by an anode gas diffusion layer. The membrane of each membrane electrode plate 50 is the site of an electrochemical reaction, which involves an anode reaction fluid and a cathode reaction fluid, the anode reaction fluid being brought to a side carrying the anode catalyst, and the cathode reaction fluid being brought to a side carrying the cathode catalyst, generating a potential difference across the membrane and ultimately generating electrical energy for the fuel cell. Optionally, the outer periphery 3 of the membrane electrode plate 50 is formed by the membrane itself, and the membrane electrode plate 50 does not have an outer frame.

[0077] Preferably, to manufacture the fuel cell 1 , each membrane electrode plate 50 is preassembled before being added to the stack 2 , ie, when the membrane electrode plate 50 is added to the stack 2 , the above-mentioned components of the membrane electrode plate 50 are already fixed to each other.

[0078] Considering the current flow within the stack 2, each of the flow field plates 10 and 30 is preferably electrically conductive. A flow field is formed on one side of each of the flow field plates 10 and 30, namely, a plurality of channels extending transversely through the stack 2 relative to the stacking direction Z2, to guide the circulation of a working fluid within each channel. The channels of the flow field plates 10 and 30 are formed along the gas diffusion layer of the membrane electrode plate 50 adjacent to the flow field plate 10 or 30, allowing the working fluid circulating in the channels to contact the gas diffusion layer and ensure electrochemical reaction with the membrane electrode plate 50.

[0079] All of the mainstream field plates 10 are dedicated to guiding the circulation of the first working fluid (e.g., cathode reaction fluid), and their channels are directed toward the corresponding gas diffusion layer of the membrane electrode plate 50 adjacent to the mainstream field plate 10. Here, this is the cathode diffusion layer of the membrane electrode plate 50. In this sense, the mainstream field plate 10 can be identified as a plate, here the cathode. In this example, the channels of the mainstream field plate 10 are directed toward the membrane electrode plate 50 adjacent to the mainstream field plate 10 in a direction opposite to the stacking direction Z2. For example, the channels of the mainstream field plate 10 are generally parallel to the normal direction Y2. Through the electrochemical reaction in the adjacent membrane electrode plate 50, each conductive mainstream field plate 10 is given the cathode potential of the electrochemical cell under consideration. The circumferential seal 80 disposed between the mainstream field plate 10 and the adjacent membrane electrode plate 50 ensures sealing between the mainstream field plate 10 and the membrane electrode plate 50, thereby preventing the first working fluid from escaping from the stack at the periphery 3 of the mainstream field plate 10 and the membrane electrode plate 50. To this end, the circumferential seal 80 advantageously forms a closed profile extending along the periphery 3, the closed profile being flush with the periphery 3 or possibly slightly recessed inwardly.

[0080] All of the secondary flow field plates 30 are dedicated to guiding the circulation of the second working fluid (e.g., the anode reaction fluid), and their channels are directed toward the corresponding gas diffusion layer of another membrane electrode plate 50 adjacent to the secondary flow field plate 30. Here, this is the anode diffusion layer of the membrane electrode plate 50. Therefore, the mainstream field plates 10 and secondary flow field plates 30 adjacent to each other separate their two adjacent membrane electrode plates 50. The secondary flow field plates 30 can be regarded as pole plates, here the anodes. In this example, along the stacking direction Z2, the channels of the secondary flow field plates 30 are directed toward the membrane electrode plates 50 adjacent to the secondary flow field plates 30. In this example, the channels of the secondary flow field plates 30 are generally parallel to the normal direction Y2 or parallel to the tangential direction X2. Through the electrochemical reaction in the adjacent membrane electrode plates 50, each conductive secondary flow field plate 30 is given the anode potential of the electrochemical cell under consideration. The circumferential seal 80 disposed between the secondary flow field plate 30 and the adjacent membrane electrode plate 50 ensures sealing between the secondary flow field plate 30 and the membrane electrode plate 50, thereby preventing the second working fluid from escaping from the stack at the periphery 3 of the secondary flow field plate 30 and the membrane electrode plate 50. To this end, the circumferential seal 80 advantageously forms a closed profile extending along the periphery 3.

[0081] 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, and the channels of the flow field plates 30 and 10 facing the membrane electrode plate 50 are surrounded by a circumferential seal 80. From one electrochemical cell to its adjacent electrochemical cell, the channels of the flow field plate 10 of the first electrochemical cell face away from the channels of the flow field plate 30 of the second electrochemical cell. The adjacent flow field plates 10 and 30 belonging to two adjacent cells together form a bipolar plate. Through electrical conduction between the two adjacent flow field plates 10 and 30, the two plates are at the same electrical potential.

[0082] Advantageously, between adjacent flow field plates 10 and 30, i.e., within the bipolar plate, another circulation field is formed by the flow field plates 10 and 30. This other circulation field comprises channels defined by the flow field plates 10 and 30 to guide the circulation of a third working fluid (i.e., a cooling fluid) between the flow field plates 10 and 30, thereby cooling the stack 2 during use.

[0083] In this example, the bipolar plates of the stack are composed of two different flow field plates 10 and 30 and are connected to each other. For example, each flow field plate 10 and 30 is composed of a metal plate, preferably formed into a circulation field by stamping the metal plate. Optionally, all or part of the flow field plate 10 or 30 can be formed by a machined plate of metal, graphite or other conductive material. Preferably, for each bipolar plate, the two flow field plates 10 and 30 are pre-assembled, that is, they are fixed to each other before they are added to the stack 2. For example, the flow field plates 10 and 30 of the same bipolar plate are pre-assembled by welding or brazing to each other.

[0084] Preferably, to manufacture the fuel cell 1, each of the circumferential seals 80 is preassembled with one of the plates 10, 30, or 50. Preferably, before being added to the stack 2, each of the bipolar plates is provided with two circumferential seals 80, one of which is formed on the flow field plate 30 extending in the stacking direction Z2, and the other of which is formed on the flow field plate 10 extending in the direction opposite to the stacking direction Z2. Alternatively, each of the membrane electrode plates 50 may be provided with two circumferential seals 80, one of which extends in the stacking direction Z2 to be positioned between the membrane electrode plate 50 and the adjacent flow field plate 10, and the other of which extends in the direction opposite to the stacking direction Z2 to be positioned 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 of said circumferential seals 80 is overmoulded, cast or printed directly on the plate 10, 30 or 50 carrying said circumferential seal, in order to facilitate assembly. However, it is also feasible to use separate circumferential seals.

[0085] Furthermore, it may be provided that the membrane electrode plate 50 is bonded to one or the other of the flow field plates 10 and 30 , or the membrane electrode plate 50 is bonded to both the flow field plates 10 and 30 , for example, by single-sided bonding or double-sided bonding.

[0086] At their respective peripheries 3, each of the plates 10, 30, 50 and 70 has a plurality of edges formed at the periphery 3 of the plate, including at least one exchange edge and at least one secondary edge, as well as a plurality of centering notches. In other words, the exchange edges, secondary edges and centering notches belong to the periphery 3 of the plate in question and constitute part of said plate. The exchange edges are intended to be covered by the confines of the external collector 100 and therefore lie within the closed contour of the collector seal 90. The centering notches are intended to continuously perform a first function, namely, during the addition of the plate to the stack 2, by cooperating with one of the centering rails 131, or at least having a centering rail 131 pass through them, in order to ensure the guidance and centering of the plate 10, 30, 50 or 70 provided with the centering notch; and a second function, namely, once the stack 2 is completed, by accommodating the longitudinal sealing portion 91 of the collector seal 90, so as to facilitate sealing with the external collector 100.

[0087] Figure 4 As shown in more detail in FIG, each main flow field plate 10 includes an exchange edge 11, two centering notches 12 and two secondary edges 13, each secondary flow field plate 30 includes an exchange edge 31, two centering notches 32 and two secondary edges 33, each membrane electrode plate 50 includes an exchange edge 51, two centering notches 52 and two secondary edges 53, and as shown in FIG. Figure 2 As shown in FIG, each end plate 70 comprises an exchange edge 71, two centering notches 72 and two secondary edges 73.

[0088] Preferably, for each plate, the centering recess is adjacent to the exchange edge and the secondary edge, i.e., at the end of the exchange edge and the end of the secondary edge, so as to connect the exchange edge and the secondary edge together. In other words, each centering recess is advantageously located between one of the exchange edges and one of the secondary edges of the corresponding plate. Here, each plate of the stack 2 comprises only two centering recesses, one exchange edge, and two secondary edges. Advantageously, the exchange edge is parallel to the tangential direction X2. Advantageously, the secondary edge adjacent to the exchange edge is parallel to the tangential direction X2. The centering recess adjacent to the exchange edge is recessed relative to the exchange edge in a direction opposite to the normal direction Y2, or is open in the normal direction Y2.

[0089] During the manufacturing process, each centering rail 131 extends parallel to the stacking direction Z2. Figure 5 and Figure 7-9As shown, each of the centering recesses 12, 32, 52 and 72 corresponds to a centering rail 131 in the tangential direction X2, and engages across or around the centering rail 131 in the normal direction Y2, so that the centering rail 131 is at least partially accommodated in each centering recess 12, 32, 52 and 72. In order to be able to slide along the stacking direction Z2 in cooperation with the centering rail 131 during the manufacturing process, at least some of the centering recesses 12, 32, 52 and 72, that is, the centering recesses 32, 52 and 71 here, are "contact centering recesses" that have a shape complementary to the centering rail 131 to match the shape of the centering rail 131, or at least contact the centering rail 131 to center the relevant plate relative to the centering rail 131 in the tangential direction X2 and / or the normal direction Y2. Preferably, the other centering recesses (here named centering recesses 12) are “non-contact centering recesses”, which allow the centering rail 131 to pass through, are only passed through by the centering rail 131 during the manufacturing process, and do not need to be complementary to the centering rail 131, but only need to be sufficiently recessed and / or wide enough to be passed through by the centering rail 131 while maintaining a distance from the centering rail 131. The shape of the centering recesses 12, 32, 52 and 72 also allows the centering rail 131 to be removed, and once the stack 2 is prepared, the centering rail is removed from the stack 2 along the normal direction Y2.

[0090] In this example, if Figure 5 and 7 As shown in FIG. 9 , the centering rail 131 has a cylindrical shape with a circular bottom, the center of which is located on an axis parallel to the stacking direction Z2. Figure 5 and 6 As shown, for each of the plates, the centering recess 12, 32, 52 or 72 has an arc-shaped profile in the projection of a projection plane P2 perpendicular to the stacking direction Z2. The projection plane P2 is parallel to the drawing direction Z2. Figure 5 and 6The "profile" refers to the edge of the centering recess. In other words, the centering recess is preferably circular, which allows it to be used both for centering the plate during the manufacture of the fuel cell 1 and for accommodating the longitudinal seal 91 of the collector seal 90. However, other profiles can be provided, such as a "U" shape, a "V" shape, etc. In the event that the centering rail 131 has a shape different from that provided here, the centering recess can be provided with another corresponding shape. In this example, the edge profile of the centering recess with contact has the same characteristics as the cross-sectional profile of the centering rail 131, thereby allowing contact along a section of this edge profile of the centering recess with a specific length. However, it is conceivable that the profile of the edge of the centering recess with contact and the cross-sectional profile of the centering rail 131 are provided to ensure only point contact, preferably sufficient point contact for the contact between the edge of the centering recess with contact and the centering rail 131 to accurately determine the relative position of the centering recess with respect to the centering rail in both transverse directions X2 and Y2.

[0091] like Figure 4As shown, each of the circumferential seals 80 preferably includes an exchange edge portion 81, which is located between the exchange edge 11 or 31 of the adjacent flow field plate 10 or 30 and the exchange edge 51 of the adjacent membrane electrode plate 50 in the stacking direction Z2. The exchange edge portion 81 is parallel to these exchange edges 11, 31, 51 of the adjacent plate and extends along these exchange edges 11, 31, 51 of the adjacent plate. Each of the circumferential seals 80 preferably includes a secondary edge portion 83, which is located between the secondary edge 13 or 33 of the adjacent flow field plate 10 or 30 on the one hand and the secondary edge 53 of the adjacent membrane electrode plate 50 on the other hand in the stacking direction Z2. The secondary edge portion 83 is parallel to these secondary edges and extends along these secondary edges. Each of the circumferential seals 80 preferably includes a recessed portion 82, which is located between the centering recesses 12 or 32 of the adjacent flow field plates 10 or 30 and the centering recesses 52 of the adjacent membrane electrode plates 50 in the stacking direction Z2. The recessed portion 82 extends along these centering recesses and preferably has a profile similar to these centering recesses, in particular so as to be able to be passed through by the centering rail 131 during the manufacturing process. Preferably, for each of the circumferential seals 80, the recessed portion 82 is adjacent to the exchange edge portion 81 and the secondary edge portion 83, that is, the recessed portion 82 is at the end of the exchange edge portion 81 and the end of the secondary edge portion 83 to connect the exchange edge portion 81 and the secondary edge portion 83 together. In other words, it is advantageous that each of the recessed portions 82 is located between portions 81 and 83 of the exchange edge portion 81 and the secondary edge portion 83, respectively. Here, each circumferential seal 80 comprises only two recesses 82, one exchange edge portion 81, and two secondary edge portions 83, corresponding to the number of exchange edges, secondary edges, and centering recesses per plate. Advantageously, the exchange edge portion 81 is parallel to the tangential direction X2. Advantageously, the secondary edge portion 83 adjacent to the exchange edge portion 81 is parallel to the tangential direction X2. The recesses 82 adjacent to the exchange edge portion 81 are recessed relative to the exchange edge portion 81 in a direction opposite to the normal direction Y2, or open in the normal direction Y2.

[0092] In this example, said recess 82 has a profile in the shape of an arc of a circle in projection onto the projection plane P2 or, more generally, as described above, has a profile of the same shape or corresponding to that of the adjacent centering notch 12 , 52 or 72 belonging respectively to the plate 10 , 50 or 70 .

[0093] The successive exchange edges 11, 31, 51, and 71 of the sheets 10, 30, 50, or 70 are stacked in the stacking direction Z2. For this particular case, the term "stacked" has a special meaning, as it does not exclude that some exchange edges may be recessed while others protrude in the normal direction Y2, as described below. However, "stacked" means that, in general, the exchange edges extend in the same plane perpendicular to the normal direction Y2. Aside from this special case and several other cases described below, the term "stacked" is used in its usual sense.

[0094] The exchange edges together form the exchange surface 5, or one of the exchange surfaces. Therefore, the exchange surface 5 does not have to be flat and may in particular have a groove corresponding to the concave exchange edge. If the circumferential seal 80 is provided, the exchange edge portion 81 also belongs to the exchange surface 5. Preferably, the exchange edges 11, 31, 51 and 71 stacked in the stacking direction Z2 are parallel to each other. Preferably, the stacked exchange edges 11 of the main flow field plates 10 in the stacking direction Z2 are arranged in the same plane parallel to the stacking direction Z2, and they are arranged in the same position along the tangential direction X2, or even have the same length in the tangential direction X2. Preferably, the stacked exchange edges 31 of the secondary flow field plates 30 in the stacking direction Z2 are arranged in the same plane parallel to the stacking direction Z2, and they are arranged in the same position along the tangential direction X2, or even have the same length in the tangential direction X2. Preferably, in the stacking direction Z2, the overlapping exchange edges 51 of the membrane electrode plates 50 are arranged in the same plane parallel to the stacking direction Z2, and are arranged at the same position along the tangential direction X2, or even have the same length in the tangential direction X2. Preferably, in the stacking direction Z2, the overlapping exchange edges 71 of the end plates 70 are arranged in the same plane parallel to the stacking direction Z2, and are arranged at the same position along the tangential direction X2, or even have the same length in the tangential direction X2.

[0095] The continuous secondary edges 13, 33, 53 and 73 of the plates are superimposed in the stacking direction Z2. In this case, "superimposed" also has a special meaning, since the term does not exclude that some secondary edges may be recessed while others protrude in the normal direction Y2, as described below. However, "superimposed" means that, in general, the secondary edges extend in the same plane perpendicular to the normal direction Y2. The secondary edges together form one of the secondary faces 7. If the circumferential seal 80 is provided, the secondary edge portion 83 also belongs to this secondary face. Preferably, the secondary edges 13, 33, 53 and 73 superimposed in the stacking direction Z2 are parallel to each other. Preferably, the superimposed secondary edges 13 of the mainstream field plates 10 in the stacking direction Z2 are arranged in the same plane parallel to the stacking direction Z2 and are arranged in the same position along the tangential direction X2, or even have the same length in the tangential direction X2. Preferably, in the stacking direction Z2, the overlapping secondary edges 33 of the secondary flow field plates 30 are arranged in the same plane parallel to the stacking direction Z2 and are arranged at the same position along the tangential direction X2, or even have the same length in the tangential direction X2. Preferably, in the stacking direction Z2, the overlapping secondary edges 53 of the membrane electrode plates 50 are arranged in the same plane parallel to the stacking direction Z2 and are arranged at the same position along the tangential direction X2, or even have the same length in the tangential direction X2. Preferably, in the stacking direction Z2, the overlapping secondary edges 73 of the end plates 70 are arranged in the same plane parallel to the stacking direction Z2 and are arranged at the same position along the tangential direction X2, or even have the same length in the tangential direction X2.

[0096] The continuous centering recesses 12, 32, 52 and 72 of the plates are superimposed in the stacking direction Z2. Here, "superimposed" again has a special meaning, since the term does not exclude that some centering recesses may be recessed, while others protrude in the normal direction Y2, as preferably described below. However, "superimposed" means that, in general, the centering recesses are aligned along the same axis parallel to the axis Z2. The centering recesses together form one of the centering grooves 6. If the circumferential seal 80 is provided, the recess 82 also belongs to this centering groove. Preferably, the superimposed centering recesses 12 of the main flow field plates in the stacking direction Z2 are identical and are arranged in the same position in the tangential direction X2 and in the normal direction Y2. Preferably, the superimposed centering recesses 32 of the secondary flow field plates 30 in the stacking direction Z2 are identical and are arranged in the same position in the tangential direction X2 and in the normal direction Y2. Preferably, the stacking centering recesses 52 of the membrane electrode plates 50 are identical in the stacking direction Z2 and are arranged at the same position in the tangential direction X2 and the normal direction Y2. Preferably, the stacking centering recesses 72 of the end plates 70 are identical in the stacking direction Z2 and are arranged at the same position in the tangential direction X2 and the normal direction Y2.

[0097] Advantageously, at least some of the flow field plates 10 and 30 form exchange openings 19. Each exchange opening 19 opens into one of the exchange edges 11 and / or 31 in the normal direction Y2, i.e., the exchange opening 19 opens onto the surface of the exchange face 5 formed by these exchange edges 11 and 31. Thus, the exchange openings 19 are opened inside the external collector 100, in particular inside the connector 101, and are covered by the external collector 100, in particular by the connector 101, and are surrounded by the collector seal 90. Preferably, each exchange edge 11 and / or 31 comprises a row of exchange openings 19, the row being parallel to the tangential direction X2, so that the assembly formed by the stack of exchange edges 11, 31 presents a grid of exchange openings 19 extending over all or a large part of the exchange face 5, along the tangential direction X2 and the stacking direction Z2.

[0098] The exchange openings 19 connect the external collector 100 to the reaction working fluid circulation field fluid of the flow field plate 10, or to the reaction working fluid circulation field fluid of the flow field plate 30, or to the cooling working fluid circulation field fluid formed between adjacent flow field plates 10 and 30. To this end, each exchange opening 19 leads to one or more of the multiple channels of the relevant circulation field. Advantageously, no exchange openings 19 are provided on the stack outside the exchange surface 5. Therefore, the exchange of working fluid between the external collector 100 and the stack 2 is carried out through the exchange openings 19 carried by the exchange surface 5 to which the external collector 100 is connected. In this example, the exchange openings 19 are formed only by the flow field plate 10 on its corresponding exchange edge 11. For a specific exchange surface 5 corresponding to a specific external collector 100, all the exchange openings 19 leading to this exchange surface are specifically connected to the circulation field of the same working fluid of all electrochemical cells covered by this exchange surface 5.

[0099] Preferably, if Figure 2 and Figure 3 As shown, each of said transverse grooves 8 is formed on a corresponding exchange edge 71 of one of the end plates 70. Thus, for each of these end plates 70, said transverse groove 8 connects together the centering notches 72 of the end plate 70 in question, so as to open into each of these centering notches 72 of the end plate 70 in question, thus connecting the centering grooves 6.

[0100] Preferably, for at least one plate of the stack 2, and preferably for all plates of the stack 2, the exchange edge 11, 31, 51 or 71 of the plate in question protrudes slightly towards the outside of the stack 2, i.e. in the normal direction Y2, relative to the adjacent secondary edge 13, 33, 53 or 73. Thus, Figure 5 The figure shows that the exchange edge 11, 31 of each flow field plate 10, 30 protrudes toward the outside of the stack 2, i.e., in the normal 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 0.05-3 mm, more preferably 0.2-1 mm. As a result, when the longitudinal seals 91 are formed and / or when they are compressed by the external collector 100, the longitudinal seals are less likely to protrude from the sides of the exchange surface 5 and to accidentally block the exchange opening 19. Optionally, the exchange edge is aligned with the secondary edge, i.e., extends along the same axis in the tangential direction X1.

[0101] Preferably, for at least one of the membrane electrode plates 50, preferably for all of the membrane electrode plates 50 of the stack 2, the exchange edge 51 of the membrane electrode plate 50 projects toward the outside of the stack 2, i.e. in the normal 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, preferably for all of the membrane electrode plates 50 of the stack 2, the secondary edge 53 of the membrane electrode plate 50 projects toward 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 allow reducing the risk of short circuits between the exchange edges 11 and 31 and between the secondary edges 13 and 33 of these flow field plates 10 and 30 by improving their isolation by the electrically insulating exchange edges 51 and 53. Thus, Figure 5 , the exchange edge 51 of each membrane electrode plate 50 protrudes toward the outside of the stack 2, i.e., in the normal direction Y2, relative to the exchange edges 11 and 31 of the adjacent flow field plates 10 and 30, by an amount called a membrane electrode plate offset "d50", which is preferably 0.1-2 mm, preferably 0.2-1 mm. Similarly, for all membrane electrode plates 50 in the stack 2, the secondary edges 53 of the membrane electrode plates 50 protrude toward the outside of the stack 2, i.e., in the normal direction Y2, relative to the secondary edges 13 and 33 of the adjacent flow field plates 10 and 30, the membrane electrode plate offset "d50" in the same sense is preferably 0.1-2 mm, preferably 0.2-1 mm.

[0102] Preferably, for at least one of the bipolar plates, and preferably for all bipolar plates, the exchange edge 11 of the main flow field plate 10 and the exchange edge 31 of the secondary flow field plate 30 are flush with each other, that is, they are at the same level in the normal direction Y2. Preferably, similarly, the secondary edge 13 of the main flow field plate 10 and the secondary edge 33 of the secondary flow field plate 30 are flush with each other, that is, they are at the same level in the normal direction Y2.

[0103] Preferably, for at least one bipolar plate, and preferably for all bipolar plates, the centering recess 12 of the primary flow field plate 10 is recessed toward the interior of the stack 2, i.e., in a direction opposite to the normal direction Y2, relative to the centering recess 32 of the secondary flow field plate 30. Furthermore, the centering recess 32 of the secondary flow field plate 30 may be smaller in both the tangential direction X2 and the normal direction Y2 than the centering recess 12 of the primary flow field plate 10. Therefore, during the manufacturing process of the fuel cell 1, for each bipolar plate, the centering recess 32 of the secondary flow field plate 30 forms a lateral support on the centering rail 131 to ensure the lateral positioning of the bipolar plate, and thus can be considered as a contacting centering recess. While the centering recess 12 remains away from the centering rail 131 when traversed by the centering rail 131 in the stacking direction Z2, and thus can be considered as a contacting centering recess. This is obviously possible when the bipolar plate consists of flow field plates 10 and 30 that are preassembled together and added to the stack, or when the stack is made by stacking preassembled electrochemical cells. Figure 5 , it is shown that for at least one of the bipolar plates, and preferably for all bipolar plates, the centering notch 12 of the main flow field plate 10 is recessed toward the interior of the stack 2, i.e., in a direction opposite to the normal direction Y, relative to the centering notch 32 of the secondary flow field plate 30, by an amount called centering notch offset "d12-32", which is preferably 0.1-1 mm, more preferably 0.2-0.6 mm. Of course, the centering notch offset between the centering notch 12 of the main flow field plate 10 and the centering notch 32 of the secondary flow field plate 30 is independent of, for example, whether the main flow field plate 10 is a cathode or anode plate and the secondary flow field plate 30 is an anode or cathode plate.

[0104] Preferably, the centering recess 52 of at least one membrane electrode plate 50 or all membrane electrode plates 50 is flush with the centering recess 32 of the adjacent secondary flow field plate 30. In addition, the centering recess 52 of at least one membrane electrode plate 50 or all membrane electrode plates 50 may have the same dimensions as the centering recess 32 of its adjacent secondary flow field plate 30 in both the tangential direction X2 and the normal direction Y2. Therefore, during the manufacturing process of the stack 2, when the membrane electrode plate 50 is added to the stack 2, the centering recess 52 forms a support on the centering rail 131 to ensure the lateral positioning of the membrane electrode plate 50, and thus it can also serve as a contacting centering recess.

[0105] In one variant, the centering recess 52 of at least one membrane electrode plate 50 or all membrane electrode plates 50 is slightly recessed toward the interior of the stack 2 relative to the centering recess 32 of its adjacent secondary flow field plate 30, and therefore in this case it can be regarded as a contactless centering recess. Preferably, the centering recess 52 protrudes toward the outside of the stack 2 relative to the centering recess 12 of its adjacent mainstream flow field plate 10. In this case, the centering recess 52 has an intermediate size between the centering recesses 12 and 32 in the tangential direction X2 and the normal direction Y2. In this case, in order to ensure that the membrane electrode plate 50 is centered during the stacking process, it is provided that, for example, the membrane electrode plate 50 is pre-assembled with another plate having a contacting centering recess, where, for example, the other plate is its adjacent secondary flow field plate 30. In order to align the membrane electrode plate 50 with the other plate for their preassembly, or to stack the membrane electrode plates 50 without preassembly, measures can be taken to ensure centering of the membrane electrode plate 50, for example by optical alignment or by geometric pre-aligned shapes between two adjacent plates.

[0106] Preferably, if Figure 4 As shown, each flow field plate 10 occupies a thickness E10 in the stack, and the thickness E10 is measured parallel to the stacking direction Z2. E10 is the thickness occupied at the periphery 3 of the flow field plate 10. Preferably, each flow field plate 30 occupies a thickness E30 in the stack 2, and the thickness E30 is measured parallel to the stacking direction Z2. E30 is the thickness occupied at the periphery 3 of the flow field plate 30. Preferably, each membrane electrode plate 50 occupies a thickness E50 in the stack 2, and the thickness E50 is measured parallel to the stacking direction Z2. E50 is the thickness occupied at the periphery 3 of the membrane electrode plate 50. Preferably, the thickness 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 channel in the direction of the stacking direction Z2. In addition, it is advantageous that the thickness E10 is greater than the thickness E30. For example, the thickness E10 is at least 1.5 times, or even twice, the thickness E30. This difference between the thicknesses E10 and E30, combined with the positioning and / or relative dimensions of the centering recesses 12 and 32, makes it possible to reduce the risk of short circuits between flow field plates 10 and 30 adjacent to the same membrane electrode plate. In fact, within the centering groove 6, due to the concavity of the centering recess 12 and the thickness of the flow field plate 10, as well as the presence of the insulating and protruding centering recess 52, the distance covered by the arc used to form the connection between the centering recess 12 and the centering recess 32 located outside the membrane electrode plate 50 is particularly large.

[0107] Preferably, for at least one of the circumferential seals 80, if not all of the circumferential seals 80, the exchange edge portion 81 is flush with the exchange edge 11 or 31 of the flow field plate 10 or 30 in the normal direction Y2, and the circumferential seal 80 is formed against the exchange edge 11 or 31. Alternatively, the exchange edge portion 81 is slightly recessed in a direction opposite to the normal direction Y2 relative to the exchange edge 11 or 31 of the flow field plate 10 or 30, or slightly protrudes in the normal direction Y2, and the circumferential seal 80 is formed against the exchange edge 11 or 31. Preferably, for at least one of the circumferential seals 80, if not all of the circumferential seals 80, the exchange edge portion 81 is recessed in a direction opposite to the normal direction Y2 relative to the exchange edge 51 of the membrane electrode plate 50, and the circumferential seal 80 is formed against the exchange edge 51. In other words, the exchange edge 51 advantageously protrudes in the normal direction Y2 relative to the exchange edge portion 81 .

[0108] Preferably, for at least one of the circumferential seals 80, if not all of the circumferential seals 80, the secondary edge portion 83 is flush with the secondary edge 13 or 33 of the flow field plate 10 or 30 in the normal direction Y2, and the circumferential seal 80 is formed against the secondary edge 13 or 33. Optionally, the secondary edge portion 83 is slightly recessed in a direction opposite to the normal direction Y2 relative to the secondary edge 13 or 33 of the flow field plate 10 or 30, or slightly protrudes in the normal direction Y2, and the circumferential seal 80 is formed against the secondary edge 13 or 33. Preferably, for at least one of the circumferential seals 80, if not all of the circumferential seals 80, the secondary edge portion 83 is recessed in a direction opposite to the normal direction Y2 relative to the secondary edge 53 of the membrane electrode plate 50, and the circumferential seal 80 is formed against the secondary edge 53. In short, the secondary edge 53 advantageously protrudes in the normal direction Y2 relative to the secondary edge portion 83 .

[0109] Preferably, for at least one of the circumferential seals 80 provided between the flow field plate 10 and the membrane electrode plate 50, if not all of the circumferential seals 80 provided between the flow field plate 10 and the membrane electrode plate 50, the recess 82 is flush with the centering recess 12 of the flow field plate 10 in the normal direction Y2, against which the circumferential seal 80 is formed. Preferably, these same recesses 82 are recessed relative to the centering recess 52 of the membrane electrode plate 50 in the normal direction Y2, against which the circumferential seal 80 is formed. This may mean that the size of the recess 82 is larger than the size of the centering recess 52. Therefore, during the manufacturing process, the recess 82 can be passed through by the centering track 131 without the centering track 131 contacting the recess.

[0110] Preferably, for at least one circumferential seal 80 disposed between the flow field plate 30 and the membrane electrode plate 50, if not all circumferential seals 80 disposed between the flow field plate 30 and the membrane electrode plate 50, the recess 82 is recessed relative to the centering recesses 32 and 52 of the flow field plate 30 and the membrane electrode plate 50 along the normal direction Y2, and the circumferential seal 80 is located between the centering recesses 32 and 52 of the flow field plate 30 and the membrane electrode plate 50. This may mean that the size of the recess 82 is larger than the size of the centering recesses 32 and 52. During the manufacturing process, the recess 82 of the circumferential seal 80 can be penetrated by the centering rail 131 without the centering rail 131 contacting the recess.

[0111] Preferably, for at least one of the end plates 70, and preferably for both end plates 70, the exchange edges 71, the secondary edges 73 and the centering recesses 72 are arranged in the same manner as the exchange edges 31, the secondary edges 33 and the centering recesses 32 of the flow field plate 30. In other words, the exchange edges 71, the secondary edges 73 and the centering recesses 72 have the same shape and arrangement as the flow field plate 30, except at the level of the transverse grooves 8. Preferably, the thickness of the end plate 70 measured at the periphery 3 parallel to the thicknesses E10 and E30 is greater than the thicknesses E10 and E30.

[0112] like Figure 2 and 6 As shown, in the direction opposite to the normal direction Y2, the longitudinal sealing portion 91 of the collector seal 90 matches and fills the shape of the different centering recesses 12, 32, 52 and 72 and the recess 82. In particular, the centering recesses 32 and 52 that protrude relative to the other centering recesses are advantageously encapsulated by the longitudinal sealing portion 91 of the collector seal 90. In other words, the collector seal 90 is arranged between the corresponding peripheries 3 of the consecutive flow field plates 30 and membrane electrode plates 50 along the stacking direction Z2, and at the level of the centering recesses 32 and 52, it is accommodated in the centering recess 12 and the recess 82. By these arrangements, not only is the optimal tightness of the fluid connection between the external collector 100 and the exchange surface 5 ensured, but the risk of arcing in the centering groove 6 is also reduced.

[0113] Furthermore, the collector seal 90 projects in the normal direction Y2 beyond the exchange edges 11, 31, 51 and 71. Preferably, the collector seal 90 thus projects over its entire circumference, ie both for the longitudinal seal 91 and for the transverse seal 92.

[0114] To manufacture the fuel cell 1, the method defined below may be implemented, such as Figure 7-9 shown.

[0115] like Figure 7 As shown, the support plate 111 is preferably arranged on a horizontal surface so that the stacking direction Z2 is vertical and upward. When the plates 10, 30, 50, and 70 and the circumferential seal 80 have not yet been stacked and the collector seal 90 has not yet been formed, the circumferential centering template 130, including centering rails 131, is temporarily installed. Here, only two centering rails 131 are provided for the centering template 130, but a different number of centering rails 131 can be provided by providing a corresponding number of centering grooves 6 on the plates 10, 30, 50, and 70. The centering template 130 also includes a fastening base 132 to which the centering rails 131 are fixedly attached.

[0116] The centering template 130 is attached to the periphery of the stack 2, i.e., outside the stack 2, resting against the side 4 of the stack 2 bearing the centering grooves 6. To attach to the support plate 111, the centering template 130 is attached by moving it until it comes into contact with the support plate 111 parallel to the normal direction Y2, or at least with a movement having a component in the normal direction Y2.

[0117] For fastening to the support plate 111, the fastening base 132 is advantageously attached against the fastening edge 115 of the support plate 111, i.e., advantageously, the same fastening edge 115 will later be used to fasten the external collector 100. Preferably, the fastening base 132 is fastened to the fastening edge 115 by means of a screw connection. Threaded holes made in the fastening edge 115 can be used to screw the screws onto the centering template 130 and subsequently onto the external collector 100.

[0118] When the centering template 130 is installed, the centering rails 131 protrude from the fastening base 132 along the stacking direction Z2 and are distributed in a plane perpendicular to the tangential direction X2.

[0119] At this stage, further circumferential centering templates may be provided, placed against the other side faces 4 of the stack 2, if the other side faces 4 have corresponding centering grooves. Finally, centering means may be provided inside the stack 2, such as rods parallel to the stacking direction Z2 and passing through the interior of the support plate 111 of the stack 2.

[0120] Once the centering template 130 is installed, the plates 10, 30, 50 and 70 and the circumferential seal 80 are stacked to form the stack 2, while the collector seal 90 remains unformed. For stacking, each plate slides along the centering rail 131 parallel to the stacking direction Z2, the corresponding centering recess of each plate accommodating the centering rail 131. In other words, the function of the centering rail 131 is to guide the plates through the corresponding centering recess. As mentioned above, preferably, some plates are stacked individually, such as plates 50 and 70, while other plates, i.e., plates 10 and 30, are pre-assembled in pairs before stacking. Preferably, each of the circumferential seals 80 is pre-assembled with one of the plates (preferably with one of plates 10 and 30) before being added to the stack 2. In practice, except possibly at the ends of the stack 2 , a complete bipolar plate is added to the stack 2 , the bipolar plate comprising two adjacent preassembled flow field plates 10 and 30 and two circumferential seals 80 formed on the flow field plates 10 and 30 , respectively.

[0121] For each plate, or each preassembled group of several plates, at least one centering recess is mechanically engaged with the centering rail 131 to guide its sliding movement along the stacking direction Z2 and to center the preassembled group or plate along the tangential direction X2 and the normal direction Y2, while the other centering recesses, which are recessed relative to the orientation rail 131 along the normal direction Y2, are only penetrated by the centering rail 131 along the stacking direction Z2. In this example, only the centering recesses 32, 52, and 72 of the secondary flow field plate 30, the membrane electrode plate 50, and the end plate are contact centering recesses that mechanically engage with the centering rail 131, while the centering recess 12 and the recess 82 of the main flow field plate 10 and the circumferential seal 80 are recessed further inward, are at a certain distance from the centering rail 131, and are only penetrated by the centering rail 131 in the stacking direction Z2, and are therefore non-contact centering recesses. The cooperation of the centering rails 131 with the centering recesses ensures that, once the stack 2 is completed, each plate of the stack 2 is correctly positioned against the adjacent plates, in particular in the tangential direction X2 and in the normal direction Y2.

[0122] In order to stack, such as Figure 7 As shown, the end plates 70 are advantageously stacked on the support plate 111 by sliding the end plates 70 along the centering rails 131 through the centering recesses 72. The current collectors and the flat seals (not shown) are then advantageously stacked.

[0123] The secondary flow field plates 30 are then stacked and guided along the stacking direction Z2 by the cooperation of the centering rails 131 and the centering recesses 32 until the membrane electrode plates 50 abut against elements already assembled in the direction opposite to the stacking direction Z2.

[0124] One of the stacked membrane electrode plates 50 is then guided along the stacking direction Z2 by the engagement of the centering rail 131 with the centering recess 52 until it rests against the already assembled secondary flow field plate 30. A preassembled bipolar plate assembly comprises: a flow field plate 10 carrying a circumferential seal 80, which faces the already stacked membrane electrode plate 50; a flow field plate 30 secured to the flow field plate 10 along the stacking direction Z2; and a second seal 80 formed on the flow field plate 30 along the stacking direction Z2. The flow field plate 10, flow field plate 30, and second seal 80 are then stacked together. This preassembled assembly is guided by the centering rail 131 through the engagement of the centering rail with the centering recess 32. Another membrane electrode plate 50 is then stacked, and so on, alternating between preassembled bipolar plate assemblies and membrane electrode plates 50. Once the last membrane electrode plate 50 is stacked, the last flow field plate 10 is added, onto which another current external collector and possible collector seal is stacked.The second end plate 70 is then stacked.

[0125] The stack 2 is then finished and remains centered by means of the centering rails 131 which are still in place.

[0126] Once the stack 2 is prepared, while the collector seal 90 is still in place, the tie rod 113 is mounted on the support plate 111. Then, the spring 114 and support plate 112 are mounted so that the spring 114 is positioned between the support plate 112 and the end plate 70 at the top of the stack 2 along the stacking direction Z2. The mounting of the support plate 112 preferably includes threading the support plate 112 onto the tie rod 113.

[0127] The support plate 112 preferably carries a fastening base 134, which is fixed to the fixing edge 116 of the support plate 112, preferably by screwing it to the fixing edge 115 of the support plate 111 in a similar manner to the fastening base 132. The fastening base 134, which belongs to the centering template 130 and is initially separated from the centering template 130, is configured to be screwed onto the centering rail 131 so as to be guided slidingly by the centering rail in the stacking direction Z2. To install the support plate 112, it is advantageously screwed onto the tie rods 113, preferably with the fastening base 134 screwed onto the centering rail 131 in the stacking direction Z2, while the spring 114 is inserted between the support plate 112 and the end plate 70 at the top of the stack.

[0128] Once the stack 2 is placed between the two support plates 111 and 112, and while the centering template 130, in particular the centering rails 131, is still in place, the stack 2 is compressed using the tie rods 113, for example by tightening the nuts at the ends of the tie rods 113, so that the support plates 111, 112 are brought toward each other in the stacking direction Z2. Press-fitting can also be performed by tightening the torque of the tie rod nuts.

[0129] Once the stacking body 2 has been compressed between the support plates 111 and 112 and before the collector seal 90 is formed, the centering rail 131 is removed, for example by removing the centering template 130 as a whole. To this end, the fastening bases 132 and 134 are advantageously separated from the support plates 111 and 112 in order to separate the centering rail 131 from the support plates 111 and 112. The centering template 130 is then moved laterally away from the stacking body 2 relative to the stacking direction Z2, i.e. along a movement which includes a component in the normal direction Y2 relative to the stacking body 2. It is noteworthy that the centering rail 131 is extracted from the centering groove 6 by being moved laterally relative to the stacking direction Z2, in particular in the normal direction Y2 relative to the stacking body 2. Removal of the centering rail 131 is therefore particularly easy. It is then obtained Figure 3 Configuration.

[0130] Once the centering rails 131 are removed, the collector seal 90 is put into place, in particular, the longitudinal seal portion 91 is disposed in the centering groove 6 and the transverse seal portion 92 is disposed in the transverse groove 8. Preferably, the collector seal 90 is formed in situ by pouring, injecting, or overmolding a liquid or pasty collector seal 90 into the centering groove 6 and transverse groove 8 and then hardening the collector seal 90. In order to form the collector seal 90 while the collector seal 90 is in a liquid or pasty state, it is preferred that the fuel cell 1 be oriented such that the normal direction Y2 points upwards so that gravity helps the liquid or pasty material to be contained in the centering groove 6 and transverse groove 8 without overflowing and to follow the inner contours of the centering groove 6 and transverse groove 8.

[0131] To form the collector seal 90, preferably, as Figure 6As shown, a first bead 95 of a first material in liquid or pasty form is first applied to the centering groove 6 and transverse grooves 8 around the entire perimeter of the future collector seal 90. The first material is advantageously silicone-based or another suitable elastomer that is non-crosslinked during application, remaining in a liquid or pasty state. Thus, it conforms to the bottoms of the centering groove 6 and transverse grooves 8, particularly by encapsulating the protruding centering notches 32 and 52. A low-viscosity material is advantageously selected to impart self-leveling and / or filling properties. This ensures that the material conforms to the centering groove 6 and transverse grooves 8, particularly the centering groove 6, which is irregular due to some protruding notches and others recessed. Despite its low viscosity, the material can be applied very precisely, preventing the material from spreading in the tangential direction X2 through the centering groove 6 and in the stacking direction Z2 through the transverse grooves 8.

[0132] Once the first bead 95 has been applied, it cures in situ. In the case of silicone, curing can be achieved, for example, by crosslinking the silicone at room temperature. The first bead 95 then forms the base of the future collector seal 90, which fills and fits the centering groove 6 and the transverse grooves 8 around the entire periphery of the collector seal 90.

[0133] Once the first bead 95 is applied, a second bead 96 of a second material in liquid or pasty form is applied over the first bead 95. The second bead 96 can be applied when the first bead 95 is only partially cured to ensure a good bond between the first bead 95 and the second bead 96. The second bead 96 covers the first bead around the entire periphery of the collector seal 90, which is formed by the first bead 95 and the second bead 96. The second bead 96 is formed to protrude relative to the centering groove 6 and the transverse groove 8 around the entire periphery of the collector seal 90.

[0134] The second bead 96 is advantageously made of a second material which differs from the first material in at least viscosity, the viscosity being compared when the materials are in an uncured state. Advantageously, the second material forming the second bead 96 in liquid or pasty form is chosen to be more viscous than the first material forming the first bead 95 when the first material itself is in a liquid or pasty state. This advantageously allows the second bead 96, which is applied in liquid or pasty form, to maintain a raised shape above the first bead 95 even when the second material has not yet cured. This advantageously allows the second bead 96, and even the collector seal 90, to be formed without a mould. Preferably, the second material is also silicone-based, or another suitable elastomer. Once the second bead 96 has been applied, it cures in situ, for example by cross-linking the silicone at room temperature. This results in Figure 2 Configuration.

[0135] Even though the above-described method for forming the collector seal 90 is preferred, as a variant it may also be provided that the collector seal is formed in a single material casting, or that the collector seal is formed according to another suitable method.

[0136] Once the collector seal 90 is formed, the external collector 100 is fluidically connected to the exchange surface 5. To this end, the external collector 100, in particular the connector 101, is brought against the exchange surface 5 by approaching the connector 101 parallel to the normal direction Y2. At least, the approaching movement of the connector 101 has a component along the normal direction Y2. The connector 101 is matched with the collector seal 90 so that the connector 101 is in sealing contact over the entire periphery of the collector seal 90. In particular, the external collector 100 is sealingly supported on the collector seal 90 by a second bead 96. When the external collector 100 abuts against the exchange surface 5, it is advantageous to provide that the collector seal 90 has already cured or cross-linked, or in any case no longer adheres, so that the external collector 100 does not adhere to the collector seal 90, but is simply in sealing contact with the collector seal 90.

[0137] Finally, the external collector 100 is fixed by means of the fixing system 102, specifically by screwing the base 103 to the fixing edge 115 and screwing the fixing base 104 to the fixing edge 116. This results in Figure 1 Configuration.

[0138] Where technically feasible, any feature of one of the above-described embodiments or variants may be used in the other above-described embodiments or variants.

Claims

1. A 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), the plates (10, 30, 50, 70) of the stack (2) being stacked along a stacking direction (Z2) to form an electrochemical cell, each of the plates (10, 30, 50, 70) being oriented perpendicularly to the stacking direction (Z2) and lying flat on an adjacent plate (10, 30, 50, 70), each of the plates (10, 30, 50, 70) comprising a respective exchange edge (11, 31, 51, 71), the exchange edges (11, 31, 51, 71) being parallel to one another and jointly forming an exchange surface (5) belonging to the stack (2), the exchange surface (5) extending parallel to the stacking direction (Z2); - an external collector (100) in fluid connection with the stack (2), the external collector (100) being attached against the stack (2) so as to cover the exchange surface (5) for exchanging the working fluid between the external collector (100) and the stack (2) via the exchange surface (5); - a collector seal (90) surrounding the exchange surface (5) and interposed between the stack (2) and the external collector (100) to ensure a fluid-tight connection between the external collector (100) and the stack (2); - a fixing system (102), different from the collector seal (90), by means of which the external collector (100) is fixed to the stack (2); wherein Each of the plates (10, 30, 50, 70) comprises a respective centering notch (12, 32, 52, 72) adjacent to the exchange edge (11, 31, 51, 71), said centering notches (12, 32, 52, 72) together forming a centering groove (6) belonging to the stack (2), said centering groove (6) adjoining the exchange face (5) and extending parallel to the stacking direction (Z2); and The collector seal (90) comprises a longitudinal sealing portion (91) parallel to the stacking direction (Z2), the longitudinal sealing portion (91) being formed in the centering groove (6) so that the longitudinal sealing portion (91) is arranged between the stacking body (2) and the external collector (100) to ensure a fluid-tight connection between the external collector (100) and the stacking body (2).

2. The fuel cell (1) according to claim 1, wherein at least one flow field plate (10, 30) forms an exchange opening (19), wherein the exchange opening (19) is formed at the exchange edge (11, 31) of the flow field plate (10, 30) to open on the surface of the exchange surface (5) and be covered by the external collector (100), and the exchange of the working fluid between the external collector (100) and the stack (2) is carried out through the exchange opening (19).

3. A fuel cell (1) according to any one of the preceding claims, wherein the plates (10, 30, 50, 70) of the stack (2) comprise respective secondary edges (13, 33, 53, 73) which are parallel to the exchange edge (11, 31, 51, 71) and are connected to the exchange edge (11, 31, 51, 71) via the centering recess (12, 32, 52, 72).

4. The fuel cell (1) according to claim 3, wherein for the plates (10, 30, 50, 70) of at least one 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. A fuel cell (1) according to claim 3 or 4, wherein for at least one membrane electrode plate (50), the secondary edge (53) of the membrane electrode plate (50) protrudes toward the outside of the stack (2) relative to the secondary edge (13, 33) of the adjacent flow field plate (10, 30).

6. A fuel cell (1) according to any one of the preceding claims, wherein: - the flow field plates (10, 30) include a primary flow field plate (10) and a secondary flow field plate (30); - at least one primary flow field plate (10) adjacent to one of the secondary flow field plates (30) to form a bipolar plate together with the secondary flow field plate (30); and -For at least one bipolar plate: The exchange edge (11) of the main flow field plate (10) and the exchange edge (31) of the secondary flow field plate (30) are flush with each other, and The centering recess (12) of the primary flow field plate (10) is recessed toward the interior of the stack (2) relative to the centering recess (32) of the secondary flow field plate (30).

7. A fuel cell (1) according to claim 6, wherein the centering recess (52) of at least one membrane electrode plate (50) is flush with or recessed toward the interior of the stack (2) relative to the centering recess (32) of its adjacent secondary flow field plate (30), and protrudes toward the outside of the stack (2) relative to the centering recess (12) of its adjacent primary flow field plate (10).

8. A fuel cell (1) according to any one of the preceding claims, wherein for at least one membrane electrode plate (50), the exchange edge (51) of the membrane electrode plate (50) protrudes toward the outside of the stack (2) relative to the exchange edge (11, 31) of its adjacent flow field plate (10, 30).

9. The fuel cell (1) according to any one of the preceding claims, wherein the stack (2) further comprises circumferential seals (80), each circumferential 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 circumferential seal (80) comprising: - an exchange edge portion (81) which is placed between the exchange edges (11, 31) of the flow field plates (10, 30) and the exchange edges (51) of the membrane electrode plates (50) along the stacking direction (Z2), and is flush with the exchange edges (11, 31) of the flow field plates (10, 30) or is recessed toward the interior of the stack (2) relative to the exchange edges (11, 31) of the flow field plates (10, 30); and - a recessed portion (82), which is placed between the centering recesses (12, 32) of the flow field plates (10, 30) and the centering recesses (52) of the membrane electrode plates (50) along the stacking direction (Z2), the recessed portion (82) being recessed toward the interior of the stack (2) relative to the centering recesses (52) of the membrane electrode plates (50), and being flush with the stack (2) or recessed toward the interior of the stack (2) relative to the centering recesses (12, 32) of the flow field plates (10, 30).

10. A 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 recess (12, 32, 52, 72) has an arc-shaped profile in a projection of a projection plane (P2) perpendicular to the stacking direction (Z2).

11. A 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) which terminates the stack (2) along the stacking direction (Z2); - the exchange edge (71) of the end plate (70) is provided with a transverse groove (8) connected to the centering groove (6) by a centering notch (72) leading to the end plate (70); and - the collector seal (90) comprises a transverse seal (92) perpendicular to the stacking direction (Z2), the transverse seal (92) being formed in the transverse groove (8) and being joined to the longitudinal seal (91) so that the transverse seal (92) is located between the end plate (70) and the external collector (100), thereby ensuring a fluid-tight connection between the external collector (100) and the stack (2).

12. A method for manufacturing a fuel cell (1) according to any one of the preceding claims, the method comprising: - when the plates (10, 30, 50, 70) of the stack (2) have not yet been stacked and the collector seal (90) has not yet been formed, installing centering rails (131) which are parallel to the stacking direction (Z2) and can be accommodated in corresponding centering recesses (12, 32, 52, 72) of the plates (10, 30, 50, 70); - while installing the centering rail (131), the panels (10, 30, 50, 70) are stacked successively to form a stack (2), the panels (10, 30, 50, 70) being guided by the mechanical cooperation of at least one centering notch (12, 32, 52, 72) with the centering rail (131), so that the centering rail (131) ensures transverse centering of the panels (10, 30, 50, 70) relative to the stacking direction (Z2); - once the stack (2) has been prepared, the centering rail (131) is removed by moving it transversely relative to the stacking direction (Z2) away from the stack (2); - once the stack (2) has been prepared and the centering rails (131) have been removed, the collector seal (90) is installed, wherein the longitudinal seal (91) is formed in the centering groove (6); - once the collector seal (90) has been installed, the external collector (100) is placed against the stack (2) to cover the exchange surface (5) and the collector seal (90) including the longitudinal seal (91) is positioned between the stack (2) and the external collector (100) to ensure a fluid-tight connection between the external collector (100) and the stack (2); and - Fixing the external collector (100) to the stack (2) using a fixing system (102).

13. The method according to claim 12, wherein: - the installation of the centering rail (131) comprises fixing the centering rail (131) on a support plate (111) belonging to the fuel cell (1); - the continuous stacking of the plates (10, 30, 50, 70) comprises stacking one of the plates (10, 30, 50, 70) on the support plate (111) in a direction parallel to the stacking direction (Z2); and - Removal of the centering rail (131) comprises separating the centering rail (131) from the support plate (111).

14. The method according to claim 12 or 13, wherein the installing of the collector seal (90) comprises: - applying a first bead (95) made of an elastomer in a non-crosslinked state into the centering groove (6) to form a longitudinal seal (91); and - Once said first bead (95) is applied, the non-crosslinked elastomer of said first bead (95) is crosslinked in situ.

15. The method of claim 14, wherein installing the collector seal (90) further comprises: Once the first layer (95) is applied, a second layer (96) made of an elastomer in a non-crosslinked state is applied to the first layer (95), so that the second layer (96) protrudes toward the outside of the stack (2) relative to the exchange surface (5), and the elastomer of the second layer (96) when the second layer (96) is applied has a higher viscosity than the elastomer of the first layer (95) when the first layer (95) is applied.

Images