Stack for a fuel cell, and associated fuel cell and vehicle

Abstract

The present invention relates to a stack (11) for a fuel cell (10), the stack comprising a separator plate (12) comprising a peripheral zone (35) with a pair of plate ports (39a, 39b, 39c), the pair of plate ports (39a, 39b, 39c) comprising a plate supply port (31a, 31b, 31c) and a plate discharge port (33a, 33b, 33c). The fuel cell comprises a membrane-electrode assembly (50) comprising a peripheral portion (52) provided with a pair of ports of the assembly (59a, 59b, 59c) with an assembly supply port (51a, 51b, 51c) and an assembly discharge port (53a, 53b, 53c). The pair of plate ports (39a, 39b, 39c) are rotationally symmetrical about a plate centre axis and an area of the cross section of the assembly supply port (51a, 51 b, 51c) is smaller than an area of the cross section of the assembly discharge port (53a, 53b, 53c).

Description

[0001] TITLE: Stack for a fuel cell, associated fuel cell and vehicle

[0002] The present invention relates to a stack for a fuel cell, as well as an associated fuel cell and vehicle.

[0003] In the field of fuel cells, it is known to seek to make the flow of reactive gas and / or coolant fluid uniform, while optimizing the quantity of reactants consumed, so that the cells of the fuel cell operate in a uniform and optimal manner. To this end, CN10796821 OA describes the use of cathode and anode plates forming bipolar plates and membrane-electrode assemblies with fluid supply and discharge ports which form fluid supply and discharge galleries. The anode and cathode plates and the membrane-electrode assemblies comprise reactive gas and coolant supply and discharge ports arranged on either side of the anode, cathode plates and the membrane-electrode assemblies, these ports being asymmetrical relative to the center of the separator plates and the membrane-electrode assemblies respectively.

[0004] However, these provisions impose the geometry of the orifices of the bipolar plates, in other words the shape of these orifices, as well as the orientation of the bipolar plates relative to each other. Indeed, the bipolar plates must all be oriented in the same direction in order to be able to define supply and evacuation galleries with an optimized section.

[0005] The aim of the invention is to resolve the drawbacks of the prior art by proposing a new stack for a fuel cell making it possible to optimize the fluid flow without imposing a geometry of the orifices of the bipolar plates or a particular orientation of the bipolar plates.

[0006] For this purpose, the invention relates to a stack for a fuel cell. The stack comprises a separator plate, extending parallel to a median plane, the median plane being perpendicular to a stacking direction, the separator plate comprising: o a circulation field, and o a peripheral zone which surrounds the circulation field and which comprises a pair of plate orifices, the pair of plate orifices comprising a plate supply orifice and a plate discharge orifice, the plate supply and discharge orifices of the pair of plate orifices being fluidically connected by the circulation field, such that a functional fluid circulating through the plate supply orifice also circulates through the plate discharge orifice of the pair of plate orifices, and a membrane-electrode assembly, extending parallel to the median plane,being superimposed on the separator plate and comprising: o a central part facing the circulation field in the stacking direction, and o a peripheral part, surrounding the central part, facing the peripheral zone in the stacking direction, the peripheral part comprising a pair of assembly orifices, the pair of assembly orifices comprising an assembly supply orifice and an assembly discharge orifice, the assembly supply orifices and assembly discharge orifices being respectively superimposed on the plate supply and discharge orifices, such that the functional fluid circulating through the plate supply orifice and plate discharge orifice also circulates through the assembly supply orifice and through the assembly discharge orifice, each assembly and plate orifice delimiting a section, parallel to the median plane,the plate and assembly supply ports superimposed forming part of a supply gallery parallel to the stacking direction, so that the functional fluid circulating in the supply gallery feeds the circulation field, the superimposed discharge ports forming part of a discharge gallery, parallel to the stacking direction, so that the functional fluid having been admitted into the circulation field from the supply gallery is discharged through the discharge gallery.,

[0007] According to the invention, the pair of plate holes is symmetrical by rotation of 180 angle degrees about a plate central axis parallel to the stacking direction and passing through a plate center, and the two assembly holes belonging to the pair of assembly holes are asymmetrical with respect to an MEA central axis parallel to the stacking direction and passing through a MEA center.

[0008] An idea underlying the invention is to provide that the separator plate is symmetrical with respect to the plate center, at least for its pair of plate orifices, and that the membrane-electrode assembly is asymmetrical with respect to a central axis of MEA, parallel to the stacking direction and passing through the center of MEA, at least for its pair of assembly orifices corresponding to the same functional fluid. For each pair of assembly orifices associated with a given functional fluid, the supply and discharge orifices of each pair of assembly orifices are diametrically opposed to each other, thus the membrane-electrode assembly is asymmetrical with respect to a central axis of MEA parallel to the stacking direction and passing through a center of MEA. The fluid flow is therefore optimized, and this, independently of the geometry of the plate orifices, or the orientation of the separator plates with respect to each other.

[0009] These arrangements are particularly advantageous in a case where several separator plates and several membrane-electrode assemblies are provided in the stack, in that it can for example be provided that all the separator plates are identical and arranged alternately, being in a position which is from one separator plate to the next, rotated by 180 degrees of angle with respect to a central axis parallel to the stacking direction A11 and passing through their respective plate center, and that all the membrane-electrode assemblies are identical and arranged in the same orientation with respect to each other. The manufacture of the stack is then facilitated, without prejudice to the optimization of the functional fluid flows in the supply and discharge galleries.

[0010] According to advantageous aspects of the invention, the stack comprises one or more of the following characteristics, taken individually or in all technically possible combinations:

[0011] - An area of ​​the section of the supply orifice of the assembly is less than an area of ​​the section of the discharge orifice of the assembly, advantageously by a factor of between 5% and 50%, preferably between 8% and 33%.

[0012] - Each orifice of the assembly is delimited by a respective peripheral edge, formed by the peripheral part,

[0013] - the peripheral edge of the feed orifice of the assembly comprises an overlapping portion and an overhanging portion,

[0014] - the peripheral edge of the assembly discharge orifice comprises a superimposed portion and a recessed portion,

[0015] - the superimposed portion of the supply orifice of the assembly is of identical shape to that of the superimposed portion of the discharge orifice of the assembly, and

[0016] - the overhanging portion being further offset towards the inside of the assembly feed orifice than the recessed portion towards the inside of the assembly discharge orifice. - The superimposed portion of the assembly feed orifice is arranged between the overhanging portion and the central part.

[0017] - The peripheral edge of the assembly discharge hole forms corners;

[0018] - the peripheral edge of the assembly feed hole forms corners;

[0019] - the recessed portion forms at least one of the corners of the peripheral edge of the discharge orifice of the assembly; and none of the corners of the peripheral edge of the supply orifice of the assembly is formed by the overhanging portion.

[0020] - The central part comprises a proton exchange polymer membrane, the central part being surrounded by the peripheral part and being superimposed on the circulation field according to the stacking direction.

[0021] - The separator plate is a bipolar plate which comprises an anodic polar plate and a cathodic polar plate superimposed.

[0022] - This stack comprises several membrane-electrode assemblies, and several separating plates, alternately superimposed in the stacking direction.

[0023] - The separating plates are identical and, for each separating plate in the stack, the immediately succeeding separating plate in the stack according to the stacking direction, is arranged, relative to said separating plate, in a position pivoted by 180 degrees of angle around the central plate axis.

[0024] - This stack further comprises a stiffening or sealing element, which is interposed between, on the one hand, the peripheral part of one of the membrane-electrode assemblies, close to the overhanging portion, and, on the other hand, the peripheral part of the membrane-electrode assembly immediately following in the stacking direction, close to the overhanging portion, the stiffening or sealing element passing through the plate feed orifice of the separating plate which separates these two membrane-electrode assemblies.

[0025] - The sections of the feed orifices of the assembly forming part of the same feed gallery are of different area for at least two different membrane-electrode assemblies of the stack.

[0026] - Each separator plate comprises a connector, on a peripheral edge of the separator plate, each connector being configured to receive a pin of a measurement module, and for each separator plate in the stack, the connector of the separator plate and the connector of the immediately successive separator plate in the stack according to the stacking direction, are arranged symmetrically according to an axial symmetry with respect to the central axis. The invention also relates to a fuel cell comprising a stack as described above.

[0027] According to other advantageous aspects of the invention, the fuel cell comprises one or more of the following characteristics, taken individually or in all technically possible combinations:

[0028] - This fuel cell further comprises a functional fluid supply line, connected to the supply gallery to supply the supply gallery with functional fluid, and a discharge line, connected to the discharge gallery to discharge the functional fluid from the discharge gallery, the supply and discharge lines being connected to the same end of the stack.

[0029] The invention also relates to a vehicle comprising at least one fuel cell as described above.

[0030] The invention will appear more clearly on reading the description which follows, given solely by way of non-limiting example, and made with reference to the drawings in which:

[0031] [Fig. 1] Figure 1 represents a schematic perspective view of a fuel cell according to one embodiment of the invention;

[0032] [Fig 2] Figure 2 shows a schematic view of a stack of the fuel cell of Figure 1;

[0033] - [Fig 3] Figure 3 represents a schematic and perspective view of the connection between the modules and the cells of the stack of bipolar plates of the fuel cell of Figure 1;

[0034] [Fig 4] Figure 4 schematically represents the stack of Figure 1, shown in partially exploded perspective;

[0035] [Fig 5] Figure 5 is a top view of a bipolar plate and membrane-electrode assembly

[0036] [Fig 6] Figure 6 is a sectional view along plane A-A' of the fuel cell stack of Figure 4

[0037] [Fig 7] Figure 7 is a sectional view along plane B-B' of the fuel cell stack of Figure 4.

[0038] [Fig 8] Figure 8 is a top view of a membrane-electrode assembly according to another embodiment of the invention.

[0039] Figures 1 and 2 show a fuel cell 10 according to a first embodiment of the invention. The fuel cell 10 is for example intended to be used in a motor vehicle, in particular an electric motor, the electrical energy supplying the motor being essentially, if not entirely, provided by the fuel cell 10.

[0040] The fuel cell 10 comprises a stack 11 comprising separator plates, here bipolar plates 12.

[0041] Each bipolar plate 12 has two opposite external faces: an anodic face and a cathodic face.

[0042] Each bipolar plate 12 is here formed by two monopolar plates 13, superimposed, the two monopolar plates 13 including a first polar plate 13A, here a cathode plate, and a second polar plate 13B, here an anode plate. The expression “two successive monopolar plates 13” designates the two monopolar cathode plates 13A and anode plates 13B associated to form the same bipolar plate 12. The monopolar plates 13 are also simply called “polar plates 13”. In such a bipolar plate 12 formed by two superimposed monopolar plates 13, the anode monopolar plate 13B forms the anode face of the bipolar plate 12, and the cathode monopolar plate 13A forms the cathode face of the bipolar plate 12. The anode and cathode faces of the bipolar plate 12 are external faces of the bipolar plate 12.

[0043] The two monopolar plates 13 are assembled to each other in a sealed manner. Each bipolar plate 12 has a substantially flat shape which extends along a median plane P12.

[0044] In this embodiment, the two associated monopolar plates 13, which form the same bipolar plate 12, are made of metal and are welded or glued to each other, or even clamped against each other by a compressive force applied, in the stacking direction A11, to the stack 11.

[0045] The stack 10 comprises a plurality of cells 14 produced in the form of a stack of bipolar plates 12, a cell 14 being formed between two consecutive bipolar plates 12. The stack 11, comprising several stacked bipolar plates 12, is thus made up of several individual cells 14 electrically connected in series. For each individual cell 14, the fuel cell 10 also comprises a membrane-electrode assembly 50, belonging to the stack 11, which is interposed between the two bipolar plates 12 associated with this cell 14. The membrane-electrode assembly 50 is also designated MEA 50 (abbreviation of the expression “membrane electrode assembly”). Thus, the stack 11 comprises several stacked bipolar plates 12 and several stacked MEA 50, an MEA 50 being stacked between two successive bipolar plates 12.In particular, an MEA 50 is in contact on the one hand with the cathode face of a first bipolar plate 12, on the other hand with the anodic face of the following bipolar plate 12 in the stack 11, according to the stacking direction A11.

[0046] Each bipolar plate 12 is thus common to two neighboring cells 14. Each membrane-electrode assembly 50 extends along a mean plane P50, which is parallel to the two median planes P12 associated with the bipolar plates 12 between which this membrane-electrode assembly 50 is interposed.

[0047] The bipolar plates 12 and the MEAs 50 are stacked in a stacking direction A11. The stacking direction A11 is orthogonal to the median plane P12 of the stacked bipolar plates 12 and to the median plane P50 of the MEAs 50. In other words, the median plane P12 is a plane transverse to the stacking direction A11. A longitudinal direction L and a transverse direction T are also defined, which form an orthogonal reference frame with the stacking direction A11. For each bipolar plate 12, a plate center C12 of this bipolar plate 12 is defined, located in the median plane P12.

[0048] The fuel cell 10 also comprises two end plates 16, which are arranged on either side of the stack 11. The stack 11 is sandwiched between the two end plates 16 and is compressed in the stacking direction A11 between the end plates 16. The end plates 16 are for example made of aluminum.

[0049] Supply lines 17a, 17b, 17c and discharge lines 19a, 19b and 19c shown in dotted lines in FIG. 1 are connected to the fuel cell 10 at one of the end plates 16. In particular, the supply lines 17a, 17b, 17c and discharge lines 19a, 19b, 19c are located at the same end of the stack 11. The supply lines 17a, 17b, 17c supply the fuel cell 10 with functional fluids and the discharge lines 19a, 19b, 19c discharge the functional fluids and any reaction products formed in the fuel cell 10. More particularly, there are three functional fluids: two reactive gases and a cooling fluid. The reactant gases are hydrogen and air. Air can optionally be replaced by oxygen. The supply lines 17a, 17b and 17c supply the fuel cell 10 with hydrogen, coolant and air respectively.The supply lines 19a, 19b and 19c respectively evacuate the hydrogen, the cooling fluid and the air possibly enriched with the reaction products from the fuel cell 10.

[0050] The order and relative arrangement of the lines 17a, 17b, 17c, 19a, 19b and 19c shown in FIG. 1 is given by way of example and can be modified depending on the application. In order to measure the electrical characteristics of the cells 14, for example an electrical voltage across one or more cells 14, modules 18 for measuring at least one electrical characteristic of the cells 14 are connected to the stack 11 of bipolar plates 12. Each module 18 makes it possible to monitor the state of the stack 11 in order to adapt the operation of the fuel cell system 10.

[0051] Two successive monopolar plates 13, therefore belonging to the same bipolar plate 12, are advantageously arranged back to back and form between them at least one pocket 20 on one edge of the bipolar plate 12, for example on a peripheral edge of the bipolar plate 12 which extends parallel to the transverse direction T.

[0052] Each pocket 20 is configured to receive a pin 22 of a module 18 for measuring the electrical characteristics of the cells 14.

[0053] More generally, a separator plate may comprise an electrical connector, male or female, preferably arranged on a peripheral edge of the separator plate. The pocket 20 is an example of such a female electrical connector.

[0054] The 12 bipolar plates are identical to each other. In the example, two successive bipolar plates 12 are stacked head to tail, that is to say that one of the bipolar plates 12 is arranged relative to the other bipolar plate 12, in a position which is pivoted by 180 degrees of angle relative to a central axis of plate A12, parallel to the stacking direction A1 1 and passing through the center of plate C12, as visible in FIG. 2. Thus, in the example comprising modules 18 on only one side of the stack 11, only the at least one pocket 20 of one bipolar plate 12 out of two is flush with the vicinity of the modules 18. Alternatively, the modules 18 can be located on either side of the stack 11, such that each pocket 20 is flush with the vicinity of a module 18.

[0055] According to the example shown, each bipolar plate 12 forms exactly two pockets 20 for receiving a pin 22 each. For each bipolar plate 12, the pockets 20 for receiving this bipolar plate 12 are arranged in the vicinity of each other, forming a connection zone 24A of this bipolar plate 12.

[0056] Each bipolar plate 12 also comprises a complementary zone 24B. The complementary zone 24B of the bipolar plate 12 is a portion of the bipolar plate 12 in which the material constituting the plate extends, preferably a smooth portion. For each bipolar plate 12, the complementary zone 24B is located symmetrically opposite the connection zone 24A relative to the central plate axis A12, parallel to the stacking direction A11 and passing through the plate center C12 of this bipolar plate 12. Thus, for any two consecutive bipolar plates 12 of the stack 11, the connection zone 24A of one of the two plates 12 is arranged opposite, in the stacking direction A11, the complementary zone 24B of the other bipolar plate 12.For any three consecutive bipolar plates 12 of the stack 11, the connection zone 24A of one of the two plates 12, which is located between the two other bipolar plates 12 which frame it in the stacking direction A11, is arranged opposite, in the stacking direction A11, the complementary zone 24B of each of the two other bipolar plates 12 which frame it in the stacking direction A11.

[0057] As illustrated in Figure 2, the stack 11 comprises two rows 23 of connection zones 24A, each of the rows 23 extending in the stacking direction A11. The two rows 23 are located symmetrically to each other with respect to the central plate axis A12 parallel to the stacking direction A11 and passing through the plate center C12 of each of the bipolar plates 12. In the example, the two rows 23 are located on either side of a transverse plane of the stack, the transverse plane being orthogonal to the longitudinal direction L. In the example illustrated, the modules 18 are connected to only one of the rows 23, located on the top of Figure 2, the other row being left unused. In a variant not shown, other modules of the type 18 modules are connected to the other row of connection zones 24A.

[0058] What is valid for one of the rows 23 of connection zones 24A is transposable to the other row 23 of connection zones 24A. In the following, we mainly describe the row 23 to which the modules 18 are connected.

[0059] The second pocket 20 allows the measurement of four wires per group of twenty cells 14. It is used for an impedance measurement. In particular, each pocket 20 is shaped to cooperate with said pin 22.

[0060] Each module 18 here comprises ten aligned pins 22 configured to connect ten pockets 20 to said module 18, i.e. twenty cells 14, and an additional pin 25 to connect the second pocket 20 of one of the twenty cells 14, as visible in FIG. 3. The ten aligned pins 22 make it possible to measure between two consecutive pins 22 the voltage at the terminals of two consecutive cells 14. The pins 22, 25 of a module 18 are preferably identical.

[0061] In the embodiment shown, each connection area 24A comprises two pockets 20, one of the pockets 20 being associated with one of the pins 22 of the module 18, while the other pocket 20 is configured to receive the additional pin 25.

[0062] The example shown comprises two modules 18, however the fuel cell 10 is not limited to two modules but may comprise more, for example ten modules 18 to connect two hundred cells 14. Similarly, the number of pins 22 for each module 10 is not limiting. The additional pin 25 is arranged substantially parallel to the alignment of pins 20 and preferably at a longitudinal end of the module 18. For example, the additional pin 25 is configured to inject current into the pocket 20 in which it is received, and thus makes it possible to carry out an impedance measurement on twenty cells 14.

[0063] Referring to Figure 4, each bipolar plate 12 includes plate supply ports 31a, 31b and 31c and plate exhaust ports 33a, 33b and 33c. In the example, a row of three plate orifices 31a, 33b and 33c is located on one side of the bipolar plate 12 relative to the transverse direction T, the three plate orifices 31a, 33b and 33c being aligned in the transverse direction T. Another row, comprising three further plate orifices 31c, 31b and 33a, is located on the other side of the bipolar plate 12, the three further plate orifices 31c, 31b and 33a also being aligned in the transverse direction T. Thus, in the example each of the two rows is provided near a respective longitudinal end of the bipolar plate 12. However, another arrangement of the orifices is possible with, for example, a pair of orifices, or more, located along the longitudinal edges of the bipolar plate.The plate orifices 31 a, b, c and 33 a, b and c are orifices passing through the bipolar plate 12, along the stacking axis A11. Each bipolar plate 12 comprises a peripheral zone 35, three circulation fields 36 and six homogenization fields 38.

[0064] The peripheral zone 35 extends around the entire circumference of the bipolar plate 12, and here comprises the plate orifices 31 a, b, c and 33a, b, c, the homogenization fields 38 and the circulation fields 36. The plate orifices 31 a, b, c, 33a, b and c are located in the peripheral zone, the homogenization fields 38 and the circulation fields 36 are surrounded by the peripheral zone 35. The peripheral zone 35 extends in a plane perpendicular to the stacking direction A11, i.e. in a plane parallel to the median plane P12.

[0065] A first circulation field 36 is formed on the anode face of the bipolar plate 12, and extends, between two first homogenizing fields 38 in the longitudinal direction L, on the anode face of the bipolar plate 12. The two first homogenizing fields 38 are respectively arranged between the first circulation field 36 and the plate orifices 31a, b, c, respectively the plate orifices 33a, b and c, in the longitudinal direction L. Hydrogen flows from the plate supply orifice 31a through one of the two first homogenizing fields, the first circulation field 36, the other of the two first homogenizing fields 38 to the plate discharge orifice 33a. Thus, the plate feed orifice 31a is intended for the injection of hydrogen, and the plate discharge orifice 33a, for the discharge of hydrogen, possibly enriched with reaction products.

[0066] A second circulation field 36 is formed on the cathode surface of the bipolar plate 12. It extends between two second homogenizing fields 38, in the longitudinal direction L on the cathode face of the bipolar plate 12. The two second homogenizing fields 38 are arranged respectively between the second circulation field 36 and the plate orifices 31a, b, c, respectively the plate orifices 33a, b and c, in the longitudinal direction L. Air circulates from the plate supply orifice 31c through one of the two second homogenizing fields 38, the second circulation field 36, the other second homogenizing field 38, to the plate discharge orifice 33c. Thus, the plate feed port 31c is intended for the injection of air, and the plate discharge port 33c, for the discharge of air, possibly enriched with reaction products.

[0067] A third circulation field 36 is formed inside the bipolar plate 12. It extends between the last two homogenizing fields 38, in the longitudinal direction L, between the two polar plates 13 of the bipolar plate 12. The last two homogenizing fields 38 are respectively arranged between the third circulation field 36 and the plate orifices 31 a, b, c, respectively the plate orifices 33 a, b and c, in the longitudinal direction L. Cooling fluid circulates from the plate supply orifice 31 b through one of the last two homogenizing fields 38, the third circulation field 36, the last homogenizing field 38, to the plate discharge orifice 33 b. Thus, the plate feed port 31b is intended for the injection of cooling fluid, and the plate discharge port 33b, for its discharge.

[0068] Each homogenization field 38 generally comprises channels, which connect one of the plate orifices 31 a, b, c or 33 a, b or c to the circulation field 36. In the example illustrated, the channels of the homogenization fields 38 are similar and formed in the same way as those of the circulation field 36, except for their orientation, here fan-shaped. This geometry makes it possible to distribute the functional fluid throughout the circulation field 36, or to recover the functional fluid from the circulation field 36 and then discharge it through the plate discharge orifice 33 a, b or c corresponding to the circulation field 36.

[0069] For each reactive gas or cooling fluid, and therefore for each fluid circulation field of the cell, the two homogenization fields 38 are symmetrical according to an axial symmetry, i.e. according to a rotation at 180 degrees of angle, relative to the central axis of plate A12, both in the geometry of the homogenization fields 38 and in the arrangement of the channels of the homogenization fields 38.

[0070] The plate feed ports 31a, b, c are each delimited respectively by a peripheral edge 37a, b, c, and the plate discharge ports 33a, b and c are each delimited respectively by a peripheral edge 41a, b, and c, the peripheral edges 37a, b, c and 41a, b, c being closed.

[0071] The plate supply ports 31a, 31b and 31c are located symmetrically opposite relative to the plate central axis A12, relative to the plate discharge ports 33a, 33b and 33c respectively. The plate ports 31a and 33a, 31b and 33b and 31c and 33c respectively form pairs of plate ports 39a, 39b and 39c. Thus, the bipolar plate 12 comprises three pairs of plate ports 39a, b and c, in which hydrogen, coolant and air circulate respectively. A pair of plate ports 39a, 39b and 39c is therefore associated with a given functional fluid.

[0072] For each pair of plate orifices 39a, b or c, the two plate orifices 31a, b or c and 33a, b or c belonging to the pair of plate orifices 39a, b or c are of symmetrical geometry, in other words of symmetrical shape, according to an axial symmetry with respect to the central axis of plate A12. For each pair of plate orifices 39a, b or c, the two plate orifices 31a, b or c and 33a, b or c have in particular an identical area and the peripheral edges 37a, b or c and 41a, b or c have a symmetrical shape according to an axial symmetry with respect to the central axis of plate A12. The plate holes 31a, b, c and 33a, b, c belonging to different plate hole pairs 39a, b, c may have different areas, as shown in Figures 4 to 6.

[0073] In the illustrated example, the MEA 50 comprises a peripheral portion 52, assembly feed orifices 51 a, b and c, assembly discharge orifices 53 a, b and c, and a central portion 56. The peripheral portion 52 extends in a plane perpendicular to the stacking direction A11, parallel to the median plane P12. The peripheral portion 52 extends around the entire circumference of the MEA 50, and includes the assembly orifices 51 a, b, c, 53a, b, c and the central portion 56, which are located within the peripheral portion 52. The assembly supply orifices 51 a, b, c are each respectively delimited by a peripheral edge 57a, 57b and 57c, and the assembly discharge orifices 53a, b and c are each respectively delimited by a peripheral edge 61 a, 61 b ​​and 61 c, the peripheral edges 57a, b, c and 61 a, b, c being closed.Here, the peripheral edges 57a, b, c and 61a, b, c are broken lines forming polygons with corners, for example four corners. More generally, the peripheral edges 57a, b, c and 61a, b, c are closed curves. The assembly feed and discharge orifices 51a, b, c and 53a, b, c of the MEA 50 are made in the membrane-electrode assembly 50 to allow the circulation of the functional fluids through the MEA 50 in the stacking direction A11. Each assembly feed opening 51a, b, c extends one of the plate feed orifices 31a, b or c of the bipolar plate 12 in the stacking direction A11. Similarly, each assembly discharge port 53a, b, c extends respectively one of the plate discharge ports 33a, b or c in the stacking direction A11.In other words, the plate feed ports 31a, b, c are respectively opposite the assembly feed ports 51a, b and c in the stacking direction A11. Similarly, the plate discharge ports 33a, b, c are respectively opposite the assembly discharge ports 53a, b and c in the stacking direction A11. Each assembly feed and discharge port 51a, b, c and 53a, b and c delimits a section, parallel to the plane of the MEA P50.

[0074] In a manner similar to that described for the bipolar plate 12, the assembly orifices 51a, b, c and 53a, b, c, located symmetrically opposite each other with respect to a central axis of MEA A50 parallel to the stacking direction A11 and passing through a center of MEA C50, respectively form pairs of assembly orifices 59a, b, c. Thus, the MEA 50 comprises three pairs 59a, 59b and 59c of assembly orifices. Hydrogen circulates in the pair of assembly orifices 59a, cooling fluid in the pair of assembly orifices 59b and air, possibly enriched with reaction products in the pair of assembly orifices 59c. For at least one given pair of assembly orifices 59a, b, c, both assembly orifices 51a, b or c and 53a, b or c belonging to that pair of assembly orifices 59a, b, c are asymmetrical relative to the central axis of MEA A50.

[0075] For at least one given pair of orifices of the assembly 59a, b, c, possibly for several pairs or even for each pair of orifices of the assembly 59a, b, c, the two orifices of the assembly 51 a, b, or c and 53a, b or c of this given pair of orifices of the assembly 59a, b, c are advantageously of different area, an area of ​​the section of the supply orifice of the assembly 51a, b or c is less than an area of ​​the section of the discharge orifice of the assembly 53a, b or c.

[0076] For at least one pair of orifices of the assembly 59a, b, c, the area of ​​the section of the supply orifice of the assembly 51a, b or c is advantageously less than the area of ​​the section of the discharge orifice of the assembly 53a, b or c by a factor of between 5% and 50%, and preferably between 8% and 33%. The reduction factor between the areas of the sections of the supply and discharge orifices of the assembly 51a, b, c and 53a, b, c may be different from one pair of orifices of the assembly 59a, b, c to the other. For example, the area reduction factor for the pair of holes in assembly 59a may be between 5% and 20%, the area reduction factor for the pair of holes in assembly 59b may be between 15% and 35%, and the area reduction factor for the pair of holes in assembly 59c may be between 10% and 30%.This makes it possible, in particular, to adjust the flow conditions for each functional fluid and to ensure, on the one hand, optimal reaction conditions for the two reactive gases, and on the other hand, optimal cooling by the cooling fluid.

[0077] The peripheral edges 41a, b, c and 61a, b, c of the plate and assembly discharge ports 33a, b, c and 53a, b, c that are superimposed in the stack 11 may not coincide exactly, so that the cross-sectional area of ​​the assembly discharge ports 53a, b or c is for example less than a cross-sectional area of ​​the plate discharge port 33a, b or c. However, the peripheral edges 41a, b, c and 61a, b, c of the superimposed plate and assembly discharge ports 33a, b, c and 53a, b, c may have the same shape. For example, a shape of the peripheral edge 61a of the discharge orifice of the assembly 53a may be a homothety by a factor less than 1 of a shape of the peripheral edge 41a of the plate discharge orifice 33a. This arrangement is particularly advantageous because it limits the risk of short circuits between two bipolar plates 12.

[0078] The peripheral edge 57a, b, c of each supply port of the assembly 51a, b, c comprises a superimposed portion and an overhanging portion, i.e., each comprises a superimposed portion 64a, 64b, 64c and an overhanging portion 65a, 65b and 65c, respectively. The peripheral edge 61a, b, c of each discharge port of the assembly 53a, b, c comprises a superimposed portion and a recessed portion, i.e., each comprises a superimposed portion 68a, 68b, 68c and a recessed portion 69a, 69b, 69c, respectively. The following explanation is given for the pair 59a, but is also valid for the pairs 59b and 59c. The overlapped portion 64a of the supply port of the assembly 51a is of identical shape to that of the overlapped portion 68a of the discharge port of the assembly 53a after a rotation of 180 degrees of angle around the central axis of MEA A50.In other words, the superimposed portions 64a and 68a are symmetrical according to an axial symmetry with respect to the central axis of MEA A50. Conversely, the projecting portion 65a projects more towards the inside of the supply orifice of the assembly 51a than the recessed portion 69a towards the inside of the discharge orifice of the assembly 53a. In particular, if the assembly feed and discharge ports 51a and 53a were superimposed such that the superimposed edges 64a and 68a coincide, the overhanging portion 65a would be offset toward the inside of the port relative to the recessed portion 69a, as seen by comparing Figures 6 and 7. The overhanging portion 65a is therefore more offset toward the inside of the assembly feed port 51a than is the recessed portion 69a toward the inside of the assembly discharge port 53a.In other words, the overhanging portion 65a makes it possible to form a supply orifice of the assembly 51a of smaller area than that of the discharge orifice of the assembly 53a, and it is the overhanging portion 65a and the recessed portion 68a which are asymmetrical with respect to each other. Thus, the two orifices of the assembly 51a, b, or c and 53a, b or c of a given pair of orifices of the assembly 59a, b, c are therefore of different shape, in the sense of different geometry, in addition to being of different area, as mentioned previously.

[0079] The overhanging portion 65a is, in the example of Figures 4 and 5, a straight line connecting two ends of the superimposed portion 64a. In particular, the overhanging portion 65a does not form corners, unlike the recessed portion 68a which is a broken line, with one or more breaks forming one or more corners. Thus, the overhanging portion 65a does not form any of the corners of the peripheral edge 57a. More precisely, the overhanging portion 65a forms corners of the peripheral edge 57a only by its intersection with the superimposed portion 64a, but does not form one or more corners of the peripheral edge 57a on its own.

[0080] The straight line shape makes it possible to maintain a geometry of the peripheral edge 57a which is as simple as possible, in order to limit pressure losses and to optimize the circulation of functional fluids, here air, through the supply orifices of the assembly 51a.

[0081] The superimposed portion 64a is ideally located between the overhanging portion 65a and the central portion 56. Thus, the overhanging portion 65a is the portion of the peripheral edge 57a which is furthest from the central portion 56. This makes it possible to keep potential turbulence away from the central portion 56 and to limit any supply disparities which could result therefrom.

[0082] The central portion 56 faces the circulation field 36 and completely covers the circulation field 36 in the stacking direction A11. A peripheral periphery of the central portion 56 may optionally overlap an inner periphery of the peripheral portion 52, as can be understood from the following description.

[0083] With reference to Figures 4 to 6, the central portion 56 comprises a membrane 58, which is a proton exchange polymer membrane. The membrane 58 extends parallel to the median plane P12, opposite the circulation field 36 in the stacking direction A11, and is substantially planar. The membrane 58 is preferably coplanar with the peripheral portion 52. The membrane 58 may be covered with a layer of catalyst on its two faces parallel to the median plane P12. In the example illustrated, the membrane 58 extends beyond the circulation field 36, in particular in the case where the central portion 56 overlaps a portion of the peripheral portion 52.

[0084] The membrane 58 of each MEA 50 is taken between two gas diffusion layers 77, also called GDL, acronym for “Gas Diffusion Layer”, visible in figures 6 and 7. Each gas diffusion layer 77 extends parallel to the median plane P12 and is interposed between the central part 56 of the MEA 50 and the opposite bipolar plate 12, following the stacking direction A11.

[0085] The MEA 50 advantageously comprises a holding frame 76 for supporting the central part 56, in particular for supporting the membrane 58. The holding frame 76 then forms the peripheral part 52. In the example of FIG. 5, the holding frame 76 clamps an external peripheral periphery of the membrane 58, in the stacking direction A11, in order to hold the membrane 58. The holding frame 76 then encloses an entire part of the membrane 58 which overlaps the peripheral part 52 in the stacking direction A11.

[0086] In a variant not illustrated, instead of the holding frame 76, it could be provided that the same membrane, such as the membrane 58, forms both the central part 56 and the peripheral part 52. The holding frame 76 is preferably made up of two half-frames of substantially identical shapes which are intended to come into plane support against each other, and which are, for example, made of polymer film, for example of polyethylene terephthalate, known by the abbreviation PET, or of polyethylene naphthalate, known by the abbreviation PEN. In the latter case, the two half-frames are for example assembled to each other by gluing.

[0087] In the example illustrated, each gas diffusion layer 77 completely covers the central portion 56 opposite, in particular covers the membrane 58, and advantageously extends over the peripheral portion 52, namely over the inner periphery of the holding frame 76 pinching the membrane 58. The gas diffusion layer 77 is advantageously formed from a porous material, and allows the reactive gas to diffuse from the circulation fields 36 to the membrane 58 when the cell 14 is in operation. In particular, one of the two GDLs 77 is in contact with the cathode face of one of the bipolar plates 12 of the stack 11, thus air can diffuse through the GDL 77 until it reaches the membrane 58, and the other GDL 77 is in contact with the anodic face of the next bipolar plate 12 in the stack, allowing hydrogen to diffuse through the GDL 77 until it reaches the membrane 58.The central part 56, taken between the GDLs 77, extends along the mean plane P50. Seals 79, interposed between the bipolar plates 12 and the MEA 50 in the direction of the stack A11, allow the functional fluids to circulate only in the circulation fields 36 dedicated to them, for example the reactive field 36 of the cathode face of the bipolar plate 12 for air or oxygen, and the reactive field 36 of the anodic face of the bipolar plate 12 for hydrogen, and prevent the functional fluids from mixing.

[0088] The stack 11 may further comprise spacers 80, as shown in FIGS. 4 to 6. A given spacer 80 is associated with a given overhanging portion 65a, b or c of the MEA 50. These spacers 80 are interposed in the stacking direction A11 between the peripheral parts 52 of two successive MEAs 50 in the stack 11, close to the overhanging portion 65a, b or c of the MEA 50 with which it is associated, so as to be opposite that of the plate feed orifices 31a, b or c, which belongs to the bipolar plate 12 separating these two MEAs 50, and which corresponds to the feed orifice of the assembly 51a, b, c. Preferably, such a spacer 80 has an axial dimension such that it passes through that of the plate supply orifices 31 a, b or c of the bipolar plate 12 which separates these two MEAs 50 and which is opposite the supply orifice of the associated assembly 51 a, b, c.When the stack 10 is in operation, ideally, each spacer 80 bears against the two MEAs 50 between which it is interposed. The spacers 80 make it possible to limit or even eliminate a potential vibration of the peripheral part 52, in particular the overhanging portions 65a, b and c, due to the circulation of the functional fluids through the supply orifices 51a, b and c. These spacers 80 are for example pads which are affixed to the MEA 50, made of a material identical to that forming the seals, or which are made of the same material as the peripheral part 52.

[0089] According to a variant not shown, there may be several spacers 80 per overhanging portion 65a, b or c.

[0090] According to another variant not shown, the spacers may extend from a sealing element, free or carried by the MEA, the sealing element being interposed between an MEA of the stack and the bipolar plate bearing against this MEA in the stacking direction. More precisely, the spacers extend from the sealing element towards the inside of the orifice of the nearest assembly. Preferably, such a spacer passes through one of the plate supply orifices 51a, b or c of the bipolar plate 12 which separates two successive MEAs 50 in the stack 11. When the stack 10 is in operation, each spacer bears against the two MEAs 50 between which it is interposed. The sealing element is for example a seal, which prevents the reactive fluid from circulating along the peripheral part 52 near the overhanging portion 65a, b or c.

[0091] According to another variant not shown, the spacers form pairs of spacers, such that two spacers of a pair of spacers are aligned in the stacking direction and carried by the MEA, on either side of the MEA in the stacking direction. Preferably, such a spacer bears against the MEA and against the spacer carried by the next MEA in the stack.

[0092] In the stack 11, the plate and assembly feed ports 31a, b, c and 51a, b, c and the plate and assembly discharge ports 33a, b, c and 53a, b, c together form respectively feed galleries 81a, 81b, 81c and discharge galleries 83a, 83b and 83c, internal to the stack 11, also called “internal manifold” in English. In particular, three feed galleries 81a, b, c and three discharge galleries 83a, b, c are formed respectively by the plate and assembly feed ports 31a, b, c and 51a, b, c and by the plate and assembly feed ports 33a, b, c and 53a, b and c. In the same way as for the orifices, pairs of galleries 89a, 89b and 89c are defined, corresponding to the pairs 39a, b, c and 59a, b, c of the plate orifices 31a, b, c and 33a, b, c and of the assembly 51a, b, c and 53a, b, c.The following description describes only the feed gallery 81a and the discharge gallery 83a, but is applicable to the feed galleries 81b and 81c and the discharge galleries 83b and 83c. Useful sections of the feed gallery 81a are defined by the smallest section of the orifices forming the feed gallery 81a, i.e. the section of the feed orifices of the assembly 51a. Useful sections of the discharge gallery 83 are defined by the sections of the discharge orifices of the assembly 53a, according to the drawings P50. Thus, for the pair of galleries 89a, the areas of the useful sections of the supply gallery 81a are smaller than the areas of the useful sections of the discharge gallery 83a, a consequence of the fact that the area of ​​the section of each supply orifice of the assembly 51a is smaller than the area of ​​the section of the discharge orifice of the assembly 53a.

[0093] According to a variant not shown, within the same stack, the feed orifices of the assembly defining together the same feed gallery do not all have the same section. For example, two different feed orifices of the assembly have a different area of ​​their section. Thus, the feed gallery has variable useful sections along its extension according to the stacking direction. The MEAs are for example organized in such a way that the areas of the sections of the feed orifices of the assembly are increasing in the direction of circulation of one of the functional fluids. This makes it possible to better optimize the flow of functional fluid, since in addition to adapting the area of ​​the useful sections of the feed galleries, the useful section is adapted along the same gallery.

[0094] The supply galleries 81a, b, c are respectively connected to the supply pipes 17a, b, c, which supply the supply galleries 81a, b and c respectively with hydrogen, cooling fluid and air, and the evacuation galleries 83a, b, c are respectively connected to the evacuation pipes 19a, b, c which evacuate the hydrogen, the cooling fluid and the air and possibly the reaction products, which allows the cell 10 to operate and in particular to generate electricity.

[0095] Figure 8 shows an alternative embodiment of an MEA 150. Aspects of the MEA 150 that are identical to those of the MEA 50 described in Figures 1-6 are referenced with the same reference signs and are not described again in detail. The MEA 150 may be used in a manner identical to the MEA 50, such as as a replacement for the MEA 50 in the stack 11.

[0096] The MEA 150 differs from the MEA 50 in that it includes assembly feed ports 151a, b, c, which replace the assembly feed ports 51a, b, c. The feed ports 151a, b, c are respectively delimited by a peripheral edge 157a, b, c, which replaces the peripheral edges 57a, b, c. The peripheral edges 157a, b, c are closed broken lines, each peripheral edge 157a, b, c forming a polygon with corners.

[0097] The feed orifices 151a, b, c are made in the membrane electrode assembly 150. Each feed orifice of the assembly 151a, b and c delimits a section, parallel to a plane of the MEA P150.

[0098] As with MEA 50, in MEA 150, assembly holes 151 a, b, c and 53a, b and c, which are located symmetrically opposite each other with respect to a central axis of MEA A150 parallel to the stacking direction A11 and passing through a center of MEA C150, form assembly hole pairs 159a, 159b and 159c, which respectively replace assembly hole pairs 59a, b and c and are respectively similar to assembly hole pairs 59a, b and c. Thus, MEA 150 includes three assembly hole pairs 159a, 159b and 159c. The following description describes only the pair of holes 159a, but this description is valid for the pairs 159b and 159c. For at least one pair of holes of the assembly 159a, the two holes of the assembly 151a and 53a belonging to this pair of holes of the assembly 159a are asymmetrical with respect to the central axis A150.

[0099] For the pair of orifices of the assembly 159a, the two orifices of the assembly 151a and 53a are advantageously of different geometry with, in particular, an area of ​​the section of the supply orifice of the assembly 151a which is less than an area of ​​the section of the discharge orifice of the assembly 53a.

[0100] Advantageously, the area of ​​the section of the supply orifice of the assembly 151a is less than the area of ​​the section of the discharge orifice of the assembly 53a by a factor identical to that described for the MEA 50.

[0101] The reduction factor between the cross-sectional areas of the supply and exhaust ports of the assembly 151 a, b, c and 53a, b and c may be different for the different pairs of ports of the assembly 159a, 159b and 159c, as described for the MEA 50.

[0102] The peripheral edge 157a, b, c of each supply port of the assembly 151 a, b, c respectively comprises a superimposed portion 164a, 164b, 164c and an overhanging portion 165a, 165b, 165c. The following explanation is given for the pair 159a, but is also valid for the pairs 159b and 159c. The superimposed portion 164a of the supply port of the assembly 151 a is of identical shape to that of the superimposed portion 68a of the discharge port of the assembly 53a after a rotation of 180 degrees of angle about the central axis A150. In other words, the superimposed portions 164a and 68a are symmetrical according to an axial symmetry with respect to the central axis A150. The overhanging portion 165a is offset more towards the inside of the supply orifice of the assembly 151a than is the recessed portion 69a towards the inside of the discharge orifice of the assembly 53a.Unlike the previous embodiment illustrated by the MEA 50, the overhanging portion 165a of the MEA 150 is a broken line forming one or more corners. According to a variant not shown, the overhanging portion may be a curved line.

[0103] Thus, the feed galleries 81a, b, c and evacuation galleries 83a, b and c have their useful sections optimized. This is achieved thanks to the MEAs 50 or 150, and does not depend on the orientation of the bipolar plates 12, which are arranged in the stack 11 by being symmetrical according to an axial symmetry with respect to the central axis A12 to allow the use of the modules 18. It is therefore possible to combine the use of modules 18 whose pins 22, 25 are inserted in the pockets 20, in order to monitor the state of the stack 11, with feed galleries 81 optimized in order to improve an efficiency of the cell 10.

[0104] The embodiments and variations mentioned above can be combined with each other to generate new embodiments of the invention.

Claims

CLAIMS 1. Stack (11), for a fuel cell (10), the stack (11) comprising: a separator plate (12), extending parallel to a median plane (P12), the median plane (P12) being perpendicular to a stacking direction (A1 1 ), the separator plate (12) comprising: o a circulation field (36), and o a peripheral zone (35) which surrounds the circulation field (36) and which comprises a pair of plate orifices (39a, 39b, 39c), the pair of plate orifices (39a, 39b, 39c) comprising a plate supply orifice (31a, 31b, 31c) and a plate discharge orifice (33a, 33b, 33c), the supply orifices (31a, 31b, 31c) and plate discharge ports (33a, 33b, 33c) of the pair of plate ports (39a, 39b, 39c) being fluidically connected by the circulation field (36), such that a functional fluid circulating through the plate supply port (31a, 31b, 31c) also circulates through the plate discharge port (33a,33b, 33c) of the pair of plate orifices (39a, 39b, 39c), and a membrane-electrode assembly (50; 150), extending parallel to the median plane (P12), being superimposed on the separator plate (12) and comprising: o a central portion (56) facing the circulation field (36) in the stacking direction (A11), and o a peripheral portion (52), surrounding the central portion (56), facing the peripheral zone (35) in the stacking direction (A11), the peripheral portion (52) comprising a pair of assembly orifices (59a, 59b, 59c; 159a, 159b, 159c), the pair of assembly orifices (59a, 59b, 59c; 159a, 159b, 159c) comprising an assembly feed port (51 a, 51 b, 51c; 151 a, 151 b, 151c) and an assembly discharge port (53a, 53b, 53c), the assembly feed ports (51 a, 51 b, 51c; 151 a, 151 b, 151c) and assembly discharge ports (53a, 53b,53c) being respectively superimposed on the plate supply and discharge ports (31a, 31b, 31c, 33a, 33b, 33c), such that the functional fluid circulating through the plate supply port (31a, 31b, 31c) and plate discharge port (33a, 33b, 33c) also circulates through the supply port, of the assembly (51 a, 51 b, 51 c; 151 a, 151 b, 151 c) and through the assembly discharge orifice (53a, 53b, 53c), each assembly and plate orifice (51a, 51b, 51c, 53a, 53b, 53c, 31a, 31b, 31c, 33a, 33b, 33c; 151a, 151b, 151c) delimiting a section, parallel to the median plane (P12), the plate and assembly supply orifices (31a, 31b, 31c, 51a, 51b 51c;151a, 151b, 151c) superimposed forming part of a supply gallery (81a, 81b, 81c) parallel to the stacking direction (A11), so that the functional fluid circulating in the supply gallery (81a, 81b, 81c) feeds the circulation field (36), the discharge orifices (33a, 33b, 33c, 53a, 53b, 53c) superimposed forming part of a discharge gallery (83a, 83b, 83c), parallel to the stacking direction (A11), so that the functional fluid having been admitted into the circulation field (36) from the supply gallery (81a, 81b, 81c) is discharged through the discharge gallery (83a, 83b, 83c), the stack (11) being characterized in that:; - the pair of plate holes (39a, 39b, 39c) is symmetrical by rotation of 180 degrees of angle about a plate central axis (A12) parallel to the stacking direction (A11) and passing through a plate center (C12), and the two assembly holes (51a, 51b, 51c; 151a, 151b, 151c, 53a, 53b, 53c; 153a, 153b, 153c) belonging to the pair of assembly holes (59a, 59b, 59c, 159a, 159b, 159c) are asymmetrical with respect to an MEA central axis (A50, A150) parallel to the stacking direction (A11) and passing through an MEA center (C50).

2. Stack (11) according to claim 1, wherein an area of the section of the feed orifice of the assembly (51a, 51b, 51c; 151a, 151b, 151c) is less than an area of the section of the discharge orifice of the assembly (53a, 53b, 53c), advantageously by a factor of between 5% and 50%, preferably between 8% and 33%.

3. Stack (11) according to claim 1 or 2, wherein: each orifice of the assembly (51a, 51b, 51c, 53a, 53b, 53c; 151a, 151b, 151c) is delimited by a respective peripheral edge (57a, 57b, 57c, 61a, 61b, 61c; 157a, 157b, 157c), formed by the peripheral portion (52), the peripheral edge (57a, 57b and 57c; 157a, 157b, 157c) of the feed orifice of the assembly (51a, 51b, 51c; 151a, 151b, 151c) comprises a superimposed portion (64a, 64b, 64c; 164a, 164b, 164c) and an overhanging portion (65a, 65b and 65c; 165a, 165b, 165c), the peripheral edge (61a, 61b, 61c) of the assembly discharge port (53a, 53b, 53c) comprises a superimposed portion (68a, 68b, 68c) and a recessed portion (69a, 69b, 69c), the superimposed portion (64a, 64b, 64c; 164a, 164b, 164c) of the assembly supply port (51a, 51b, 51c; 151a, 151b, 151c) is of identical shape to that of the superimposed portion (68a, 68b, 68c) of the assembly discharge port (53a, 53b, 53c), and - the overhanging portion (65a, 65b and 65c; 165a, 165b, 165c) being further offset towards the inside of the assembly supply orifice (51a, 51b, 51c; 151a, 151b, 151c) than the recessed portion (69a, 69b, 69c) towards the inside of the assembly discharge orifice (53a, 53b, 53c).

4. Stack (11) according to claim 3, wherein the superimposed portion (64a, 64b, 64c; 164a, 164b, 164c) of the feed orifice of the assembly (51a, 51b, 51c; 151a, 151b, 151c) is arranged between the overhanging portion (65a, 65b and 65c; 165a, 165b, 165c) and the central part (56).

5. Stack (11) according to claim 3 or 4, wherein: the peripheral edge (61a, 61b, 61c) of the assembly discharge orifice (53a, 53b, 53c) forms corners; the peripheral edge (57a, 57b and 57c) of the assembly feed orifice (51a, 51b, 51c) forms corners; the recessed portion (69a, 69b, 69c) forms at least one of the corners of the peripheral edge (61a, 61b, 61c) of the assembly discharge orifice (53a, 53b, 53c); and none of the corners of the peripheral edge (57a, 57b and 57c) of the assembly feed port (51a, 51b, 51c) is formed by the overhanging portion (65a, 65b and 65c).

6. Stack (11) according to any one of the preceding claims, in which the central part (56) comprises a proton exchange polymer membrane (58), the central part (56) being surrounded by the peripheral part (52) and being superimposed on the circulation field (36) according to the stacking direction (A1 1).

7. Stack (11) according to any one of the preceding claims, in which the separator plate (12) is a bipolar plate (12) which comprises an anodic polar plate (13B) and a cathodic polar plate (13A) superimposed.

8. Stack (11) according to any one of the preceding claims, comprising several membrane-electrode assemblies (50), and several separator plates (12), alternately superimposed in the stacking direction (A11).

9. Stack (1 1 ) according to claim 8, wherein the separating plates (12) are identical and, for each separating plate (12) in the stack (1 1 ), the immediately successive separating plate (12) in the stack (1 1 ) according to the stacking direction (A1 1 ), is arranged, relative to said separating plate (12), in a position pivoted by 180 degrees of angle around the central plate axis (A12).

10. Stack (11) according to one of claims 8 or 9, which further comprises a stiffening (80) or sealing element, which is interposed between, on the one hand, the peripheral part (52) of one of the membrane-electrode assemblies (50; 150), close to the overhanging portion (65a, 65b and 65c; 165a, 165b, 165c), and, on the other hand, the peripheral part (52) of the membrane-electrode assembly (50; 150) immediately following in the stacking direction (A11), close to the overhanging portion (65a, 65b and 65c; 165a, 165b, 165c), the stiffening (80) or sealing element passing through the plate feed orifice (31a, 31 b, 31 c) of the separating plate (12) which separates these two membrane-electrode assemblies (50; 150).

11. Stack (11) according to one of claims 8 to 10, in which the sections of the supply orifices of the assembly (51 a, 51 b, 51 c; 151 a, 151 b, 151 c) forming part of the same supply gallery (81a, 81 b, 81c) are of different area for at least two different membrane-electrode assemblies (50; 150) of the stack (11).

12. Stack (11) according to any one of claims 8 to 11, wherein each separator plate (12) comprises a connector (20), on a peripheral edge (21) of the separator plate (12), each connector (20) being configured to receive a pin (22) of a measurement module (18), and for each separator plate (12) in the stack (11), the connector (20) of the separator plate (12) and the connector (20) of the separator plate (12) immediately successive in the stack (11) according to the stacking direction (A11), are arranged symmetrically according to an axial symmetry with respect to the central axis (A12).

13. Fuel cell (10) comprising a stack (11) according to any one of the preceding claims.

14. Fuel cell (10) according to claim 13, further comprising a supply line (17a, 17b, 17c) for functional fluid, connected to the supply gallery (81 a, 81 b, 81 c) for supplying the supply gallery (81 a, 81 b, 81 c) with functional fluid, and a discharge line (19a, 19b, 19c), connected to the discharge gallery (83a, 83b, 83c) for discharging the functional fluid from the discharge gallery (83a, 83b, 83c), the supply and discharge lines (81 a, 81 b, 81c, 83a, 83b, 83c) being connected to the same end of the stack (11).

15. Vehicle comprising at least one fuel cell (10) according to the preceding claim.

Images