Fuel cell plate

Abstract

Fuel cell plate (1) intended to come into contact with a Membrane Electrode Assembly, the plate (1) comprising a reactive face (11) including a reactive zone (2) intended to face the Membrane Electrode Assembly, a clamping band (9), a thinned portion (3) and a peripheral sealing zone (12), the reactive zone (2) having circulation channels for a reagent, the clamping band (9) being configured to at least partially surround the reactive zone (2) and being intended to clamp the Membrane Electrode Assembly, the peripheral sealing zone (12) being configured to surround the clamping band (9) and being intended to form, together with the Membrane Electrode Assembly, a seal of the fuel cell with respect to the reagent, the thinned portion (3) being disposed between the peripheral sealing zone (12) and the clamping band (9). (Shorthand figure: Fig. 2)

Description

Title of the invention: Fuel cell plate

[0001] The invention relates to a fuel cell plate, a fuel cell assembly comprising such a plate, a fuel cell comprising such an assembly and a fuel cell comprising such an assembly.

[0002] The invention relates more particularly to a proton exchange membrane fuel cell plate, the plate comprising two opposite faces respectively a reactive face intended to face a Membrane Electrode Assembly and a cooling face, the reactive face comprising a reactive zone, in particular central, provided with at least one circulation channel for a reactant.

[0003] In the case of a cell composed of two plates sandwiching a Membrane Electrode Assembly (also called an "MEA"), each plate (anodic or cathodic) includes one side dedicated to the circulation of a reactive fluid (also called a reactant) such as air or hydrogen opposite the Membrane Electrode Assembly and one side, facing outwards from the cell, dedicated to the circulation of a cooling fluid such as a coolant. Fuel cell cells, on both the anode and cathode sides, generate heat (the chemical reactions within the cell are exothermic) and must be cooled by a cooling circuit.

[0004] The fluids (reactants and coolant) are supplied and discharged via passages or collectors formed in the plates.

[0005] Reference may be made, for example, to document FR3030120 AL

[0006] At the periphery of their reactive surface, particularly the central part of the AME facing the reactive zone of the plate's reactive face, AMEs generally have a slightly greater thickness and / or locally greater mechanical stiffness. This increased thickness is generally due to the local superposition of several component layers. The locally greater stiffness of the AME periphery is generally due to a lower residual compressibility of the gas diffusion layer (GDL) that makes up the AME.

[0007] This difference in thickness between the periphery of the AME and its reactive surface which is exposed to the reagents can be on the order of a few tens of microns.

[0008] Generally, a significant tightening of the cell stack allows for efficient compression of the AME.

[0009] However, this additional clamping force is applied to all components ensuring the clamping of the cell stack (end plates, means of connection, geometric variation compensation system ...) and leads to oversizing of these, which results in higher cost, greater weight and volume, and an oversized clamping tool.

[0010] One solution is to hollow out the plate, around the periphery of the reactive zone, to reduce the force return and thus decrease the clamping force to be applied to obtain the correct compression ratio of the AME.

[0011] With such a solution, there is a risk of leaks appearing although from a mechanical point of view the force transfer remains too important.

[0012] One object of the present invention is to overcome all or part of the disadvantages of the prior art noted above.

[0013] To this end, the invention relates to a fuel cell plate, of the proton exchange membrane type, intended to come into contact with a Membrane Electrode Assembly, the plate comprising two opposing faces respectively a reactive face intended to face the Membrane Electrode Assembly and a cooling face, the reactive face comprising a reactive zone, a clamping band, a thinned portion and a peripheral sealing zone, the reactive zone being provided with reliefs and hollows forming circulation channels for a reagent, each of the channels being separated from another of the channels by a tooth, the clamping band being configured to at least partially surround the reactive zone by being intended to clamp the Membrane Electrode Assembly, the peripheral sealing zone being configured to surround the clamping band by being intended to form jointly with the Membrane Electrode Assembly,The battery is sealed against the reagent, with the thinned portion positioned between the peripheral sealing zone and the clamping band.

[0014] This arrangement makes it possible to optimize the clamping force to be applied to obtain the correct compression ratio of FAME, while eliminating any risk of fluid from the reagent.

[0015] According to one embodiment, the cooling face is intended to allow the circulation of a cooling fluid.

[0016] According to one embodiment, the cooling face is intended to face the cooling face of another fuel cell plate.

[0017] According to one embodiment, the clamping band is configured to surround the reactive area on its entire perimeter.

[0018] According to one embodiment, the clamping band is configured to at least partially surround the reactive area by being intended for clamping a bead of the Membrane Electrode Assembly, in particular when the plate is mounted in a fuel cell stack.

[0019] According to one embodiment, the clamping band is configured to form a seal between the reactive zone and the Membrane Electrode Assembly so that the incoming reagent the reagent circulating in the channels flows through the channels without bypassing them, and the reagent circulating in the channels only exits the channels at their outlet.

[0020] According to one embodiment, the clamping band is continuous, surrounding the reactive area on its entire perimeter.

[0021] According to one embodiment, the peripheral sealing zone is configured to surround the clamping band all around the clamping band.

[0022] According to one embodiment, the plate is configured so that one of the channels separates a tooth from the clamping band.

[0023] According to one embodiment, the plate comprises a plurality of teeth, each tooth separating two of the channels from each other.

[0024] According to one embodiment, the average width of each tooth is less than the average width of the clamping band.

[0025] According to one embodiment, the plate is configured so that, in a direction transverse to the plane of the plate, the thinned portion is set back by a first thickness determined relative to the clamping band, the first thickness being in particular between 60 pm and 120 pm.

[0026] According to one embodiment, the first thickness is between 5% and 20% of the nominal thickness of the plate.

[0027] According to one embodiment, the plate is configured so that, in the direction transverse to the plane of the plate, the thinned portion is set back from the first thickness determined with respect to the teeth.

[0028] According to one embodiment, the peripheral sealing area includes a peripheral seal groove specifically configured to receive a seal.

[0029] Alternatively, the peripheral sealing area includes at least one raised section configured to compress a sealing reinforcement element of the Membrane Electrode Assembly.

[0030] According to one embodiment, the plate is configured so that, in the direction transverse to the plane of the plate, the peripheral sealing groove is recessed by a second determined thickness relative to the clamping band, the second determined thickness being greater than the first determined thickness.

[0031] According to one embodiment, the second thickness is between 30% and 70% of the nominal thickness of the plate, for example between 30% and 50% of the nominal thickness of the plate.

[0032] According to one embodiment, the plate has a reagent collecting orifice formed through the plate and configured to be in fluidic communication with the reactive zone via a light formed through the plate, the plate being configured in particular so that the clamping band surrounds at least partially the light.

[0033] According to one embodiment, the plate is configured so that the clamping band surrounds the light on its entire perimeter so that the reagent passing through the light can only pass between the collecting orifice and the channels.

[0034] According to one embodiment, the plate is configured so that the peripheral sealing groove surrounds the collector orifice, in particular on its entire perimeter, being provided between the collector orifice and the thinned portion, in a direction parallel to the plane of the plate.

[0035] The invention also relates to a fuel cell assembly comprising a plate conforming to any one of the above or below characteristics and a Membrane Electrode Assembly, the Membrane Electrode Assembly comprising a membrane coated with a catalyst and a sealing reinforcement element, a peripheral strip of the membrane being pinched by the sealing reinforcement element, the Membrane Electrode Assembly further comprising a gas diffusion layer sandwiching the membrane and a portion of the sealing reinforcement element, the Membrane Electrode Assembly having a reactive surface in contact with the reactive zone and an inert surface comprising a bead and a thinned peripheral edge, the bead connecting the thinned peripheral edge to the reactive surface.

[0036] According to one embodiment, the membrane on which the catalyst element is deposited is a CTM type membrane.

[0037] According to one embodiment, the reactive surface is defined by the surface of the gaseous diffusion layer which is in contact with the membrane.

[0038] According to one embodiment, the reactive surface is in contact with the teeth of the reactive zone.

[0039] According to one embodiment, the reactive surface is in contact with the reliefs of the reactive zone.

[0040] According to one embodiment, the inert surface is defined by the surface of the gas diffusion layer which is in contact with the sealing reinforcement.

[0041] The invention also relates to an assembly conforming to any one of the above or below characteristics, intended to be assembled in a fuel cell stack, being configured so that, when assembled: - the reactive zone is opposite the reactive surface without contacting the rim; - the clamping band is opposite a first portion of the bead, applying a first clamping force on the first portion; - the thinned portion is opposite a second portion of the ridge, by applying a second clamping force to the second portion, the second clamping force being less than the first clamping force, for example being zero; - the peripheral sealing zone is opposite the sealing reinforcement element, in particular without coming into contact with the gas diffusion layer.

[0042] According to one embodiment, the assembly is configured so that a second width of the second portion is greater than a first width of the first portion, the widths being measured in particular in the direction of the width of the clamping band which is opposite the first portion considered.

[0043] According to one embodiment, the first width is between 2.5 and 30% of the second width.

[0044] The invention also relates to a fuel cell comprising an assembly conforming to any one of the above or below characteristics and a second fuel cell plate, the plate and the second plate sandwiching the Membrane Electrode Assembly, the cell being intended to be mounted in a fuel cell stack, being configured so that, during its mounting, the second plate applies a third clamping force, in particular constant, over at least 80% of the bead.

[0045] According to one embodiment, the third clamping force is applied to a maximum of 20% of the bead.

[0046] The invention also relates to a fuel cell comprising a stack of cells conforming to any one of the above or below characteristics and / or a stack of assemblies conforming to any one of the above or below characteristics.

[0047] The invention may also relate to any alternative device or method comprising any combination of the above or below features within the scope of the claims.

[0048] The invention will be better understood upon reading the following description and examining the accompanying figures. These figures are given only by way of illustration and in no way limit the invention.

[0049] [Fig. 1] represents a perspective and schematic view illustrating a fuel cell plate capable of implementing the invention;

[0050] [Fig.2] represents a schematic and partial cross-sectional view illustrating an assembly capable of implementing the invention; and

[0051] [Fig.3] represents a schematic and partial cross-sectional view illustrating an example of a battery cell capable of implementing the invention.

[0052] The fuel cell plate 1 schematically illustrated in [Fig.1] is a plate for a proton exchange membrane type fuel cell.

[0053] The plate 1 is flat and preferably made of metallic and / or composite material. It is molded and / or stamped and / or machined.

[0054] The plate 1 conventionally comprises two opposite faces respectively a reactive face 11 intended to face a Membrane Electrode Assembly 4 and a cooling face defining a path for a cooling fluid.

[0055] Plate 1 is intended to come into contact with the Membrane Electrode Assembly (4), in particular via the reactive face of plate 1.

[0056] The cooling face is intended to face the cooling face of another fuel cell plate, defining between them the path for the cooling fluid.

[0057] The reactive face 11 includes a reactive zone 2, a clamping band 9, a thinned portion 3 and a peripheral sealing zone 12.

[0058] The reactive zone 2 is provided with reliefs and hollows forming channels 5 for the circulation of a reagent.

[0059] Each of the canals 5 is separated from another of the canals 5 by a tooth 7.

[0060] The clamping band 9 is configured to at least partially surround the reactive area 2, being intended for clamping the Membrane Electrode Assembly 4.

[0061] The clamping band 9 is configured to surround the reactive zone 2 around its entire perimeter. This clamping band 9, together with the Membrane Electrode Assembly 4, forms a sealing bead for the reactive fluid entering the channels 5. This prevents the reactive fluid entering the channels 5 from bypassing them.

[0062] The clamping band 9 is intended for clamping a bead of the Membrane Electrode Assembly 4, in particular when the plate 1 is mounted in a fuel cell stack.

[0063] The clamping band 9 is configured to form a seal between the reactive area and the Membrane Electrode Assembly 4 so that the reagent entering the channels 5 flows through the channels 5 without bypassing them and the reagent flowing through the channels 5 only exits the channels 5 at their end.

[0064] The clamping band 9 is continuous, surrounding the reactive area all around its perimeter.

[0065] The peripheral sealing zone 12 is configured to surround the clamping band 9 and is intended to form, together with the Membrane Electrode Assembly 4, a seal of the cell with respect to the reagent.

[0066] The thinned portion 3 is disposed between the peripheral sealing zone 12 and the clamping band 9.

[0067] The plate 1 is configured so that one of the channels 5 separates a tooth 7 from the clamping band 9.

[0068] The plate 1 has a plurality of teeth 7, each tooth 7 separating two of the channels 5 from each other.

[0069] The average width of each tooth 7 is less than the average width of the clamping band 9.

[0070] The plate 1 is configured so that, along a direction transverse to the plane of the plate 1, the thinned portion 3 is set back by a first thickness H1 determined with respect to the clamping band 9, the first thickness H1 being in particular between 60 pm and 120 pm.

[0071] The first thickness is between 5% and 20% of the nominal thickness of plate 1.

[0072] The plate 1 is configured so that, according to the direction transverse to the plane of the plate, the thinned portion 3 is set back from the first thickness H1 determined with respect to the teeth 7.

[0073] The peripheral sealing area 12 includes a peripheral sealing groove 12 specifically configured to receive a sealing gasket.

[0074] The plate 1 is configured such that, in the direction transverse to the plane of the plate 1, the peripheral sealing groove 12 is recessed by a second determined thickness H2 relative to the clamping band 9, the second determined thickness H2 being greater than the first determined thickness HL

[0075] The second thickness H2 is between 30% and 70% of the nominal thickness of the plate, for example between 30% and 50% of the nominal thickness of plate 1.

[0076] The plate 1 has a reagent collecting orifice 8 formed through the plate 1 and configured to be in fluidic communication with the reactive zone 2 via a light 10 formed through the plate 1, the plate 1 being configured in particular so that the clamping band 9 surrounds at least partially the light 10.

[0077] The plate 1 is configured so that the clamping band 9 surrounds the light 10 on its entire perimeter so that the reagent passing through the light 10 can only pass between the collecting orifice 8 and the channels 5.

[0078] The plate 1 is configured so that the peripheral sealing groove 12 surrounds the collector orifice 8, in particular on its entire perimeter, being provided between the collector orifice 8 and the thinned portion 3, in a direction parallel to the plane of the plate 1.

[0079]

[0080] [Fig.2] schematically illustrates a fuel cell assembly 26 comprising plate 1 of [Fig.1] and a Membrane Electrode Assembly 4.

[0081] The Membrane Electrode Assembly 4 comprises a membrane 27 coated with a catalyst and a sealing reinforcement element 28, a peripheral strip of the membrane being pinched by the sealing reinforcement element 28

[0082] The Membrane Electrode Assembly 4 further comprises a gas diffusion layer 29 sandwiching the membrane 27 and a portion of the sealing reinforcement element 28

[0083] The Membrane Electrode Assembly 4 has a reactive surface 22 in contact with the reactive zone 2 and an inert surface 23 having a bead 24 and a thinned peripheral edge 25

[0084] The bead 24 connects the thinned peripheral edge 25 to the reactive surface 22.

[0085] The membrane 27 on which the catalyst element is deposited is called a CCM type membrane for "Catalyst Coated Membrane". More simply, it can be referred to as a CCM.

[0086] Assembly 26 is intended to be assembled in a fuel cell stack. Assembly 26 is configured so that, once assembled: - the reactive zone 2 is opposite the reactive surface 22 without contacting the bead 24; - the clamping band 9 is opposite a first portion PI of the bead 24, applying a first clamping force on the first portion PI; - the thinned portion 3 is opposite a second portion P2 of the bead 24, by applying in particular a second clamping force on the second portion P2, the second clamping force being less than the first clamping force, for example being zero; - the peripheral sealing zone 12 is opposite the sealing reinforcement element 28, in particular without coming into contact with the gaseous diffusion layer 29.

[0087] The assembly 26 is configured so that a second width of the second portion P2 is greater than a first width of the first portion PI, the widths being measured in particular in the direction of the width of the clamping band 9 which is opposite the first portion PI considered.

[0088] Fig. 3 schematically illustrates a fuel cell 6 comprising an assembly 26 as described above and a second fuel cell plate 21.

[0089] Plate 1 and the second plate 21 sandwich the Membrane Electrode Assembly 4.

[0090] Plate 1 is an anodic plate, respectively a cathodic plate. The second plate 21 is a cathodic plate, respectively an anodic plate.

[0091] The cell 6 is intended to be mounted in a fuel cell stack, being configured so that, during its mounting, the second plate 21 applies a third clamping force, in particular constant, on at least 80% of the bead 24.

[0092] This architecture makes it possible to reduce the clamping force which reduces or eliminates mechanical stresses on the clamping plates clamping the stack of cells 6 and the joining means.

[0093] Preferably, the localized thickness reduction concerns only one plate per cell 6. This makes it possible to better guarantee dimensional accuracy. Indeed, in this case, the machining tolerance of the plate or of a mold for manufacturing the cells is taken into account only once per cell.

[0094] In this embodiment, only plate 1 conforms to the plate in [Fig. 1], the second plate 21 being, for example, devoid of a thinned area 3.

[0095] Alternatively, plate 1 and the second plate 21 are both in accordance with the plate in [Fig.1].

Claims

1. Demands Fuel cell assembly (26) comprising a fuel cell plate (1), of the proton exchange membrane type, and a Membrane Electrode Assembly (4), the plate (1) being intended to come into contact with the Membrane Electrode Assembly (4), the plate (1) comprising two opposing faces respectively a reactive face (11) intended to face the Membrane Electrode Assembly (4) and a cooling face, the reactive face (11) comprising a reactive zone (2), a clamping band (9), a thinned portion (3) and a peripheral sealing zone (12), the reactive zone (2) being provided with reliefs and hollows forming channels (5) for the circulation of a reagent, each of the channels (5) being separated from another of the channels (5) by a tooth (7), the clamping band (9) being configured to at least partially surround the reactive zone (2) by being intended for clamping the Membrane Electrode Assembly (4),The peripheral sealing zone (12) is configured to surround the clamping band (9) and, together with the Membrane Electrode Assembly (4), forms a seal between the cell and the reagent. The thinned portion (3) is disposed between the peripheral sealing zone (12) and the clamping band (9). The Membrane Electrode Assembly (4) comprises a membrane (27) coated with a catalyst and a sealing reinforcement element (28). A peripheral band of the membrane is pinched by the sealing reinforcement element (28). The Membrane Electrode Assembly (4) further comprises a gas diffusion layer (29) sandwiching the membrane (27) and a portion of the sealing reinforcement element (28). The Membrane Electrode Assembly (4) has a reactive surface (22) in contact with the reactive zone (2) and an inert surface (23) comprising a bead (24) and a thinned peripheral edge. (25),the bead (24) connecting the thinned peripheral edge (25) to the reactive surface (22), the assembly (26) being intended to be assembled in a fuel cell stack, being configured so that, when assembled:, - the reactive zone (2) is opposite the reactive surface (22) without contacting the rim (24); - the clamping band (9) is opposite a first portion (PI) of the bead (24), applying a first clamping force on the first portion (PI); - the thinned portion (3) is opposite a second portion (P2) of the bead (24), applying in particular a second clamping force on the second portion (P2), the second clamping force being less than the first clamping force, for example being zero; - the peripheral sealing zone (12) is opposite the sealing reinforcement element (28), in particular without coming into contact with the gas diffusion layer (29).

2. Assembly (26) according to the preceding claim, the plate (1) being configured so that, along a direction transverse to the plane of the plate (1), the thinned portion (3) is set back by a first thickness (Hl) determined with respect to the clamping band (9), the first thickness (Hl) being in particular between 60 pm and 120 pm.

3. Assembly (26) according to any one of the preceding claims, the peripheral sealing area (12) comprising a peripheral sealing groove (12) in particular configured to receive a seal.

4. Assembly (26) according to the preceding claim, the plate (1) being configured such that, along the direction transverse to the plane of the plate (1), the peripheral sealing groove (12) is recessed by a second thickness (H2) determined relative to the clamping band (9), the second determined thickness (H2) being greater than the first determined thickness (H1).

5. Assembly (26) according to any one of the preceding claims, the plate (1) having a reagent collecting orifice (8) formed through the plate (1) and configured to be in fluidic communication with the reactive zone (2) via a light (10) formed through the plate (1), the plate (1) being in particular configured so that the clamping band (9) at least partially surrounds the light (10).

6. Assembly (26) according to the preceding claim, the plate (1) being configured so that the peripheral sealing groove (12) surrounds the collector orifice (8), in particular around its entire circumference, by being space provided between the collecting orifice (8) and the thinned portion (3), in a direction parallel to the plane of the plate (1).

7. Assembly (26) according to any one of the preceding claims, being configured so that a second width of the second portion (P2) is greater than a first width of the first portion (PI), the widths being in particular measured in the direction of the width of the clamping band (9) which is opposite the first portion (PI) considered.

8. Fuel cell (6) comprising an assembly (26) according to any one of claims 1 to 7 and a second fuel cell plate (21), the plate (1) and the second plate (21) sandwiching the Membrane Electrode Assembly (4), the cell (6) being intended to be mounted in a fuel cell stack, being configured so that, during its mounting, the second plate (21) applies a third clamping force, in particular constant, over at least 80% of the bead (24).

9. Fuel cell comprising a stack of cells (6) according to claim 8 and / or a stack of assemblies (26) according to any one of claims 1 to 7.

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