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) comprising a reactive zone (2) intended to face the Membrane Electrode Assembly, a clamping strip (9), a thinned portion (3) and a peripheral sealing zone (12), the reactive zone (2) comprising circulation channels for a reactant, the clamping strip (9) being configured to at least partially surround the reactive zone (2) while being intended for clamping the Membrane Electrode Assembly, the peripheral sealing zone (12) being configured to surround the clamping strip (9) while being intended to form, together with the Membrane Electrode Assembly, a seal of the cell with respect to the reactant, the thinned portion (3) being arranged between the peripheral sealing zone (12) and the clamping strip (9). Abstract 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 cell comprising such an assembly and a fuel cell comprising such an assembly.

[0002] The invention relates more particularly to a fuel cell plate of the proton exchange membrane type, 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 a central zone, 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 "MEA"), each plate (anodic or cathodic) comprises a side dedicated to the circulation of a reactive fluid (also called reagent) such as air or hydrogen opposite the Membrane Electrode Assembly and a side, facing the outside of the cell, dedicated to the circulation of a cooling fluid such as a coolant. The fuel cell cells, anode side and cathode side, in fact generate heat (the chemical reactions within the cell are exothermic) and must be cooled by a cooling circuit.

[0004] The fluids (reagents and cooling) are supplied and evacuated via passages or collectors formed in the plates.

[0005] We can refer for example to document FR3030120 AL

[0006] At the periphery of their reactive surface, being in particular the central part of the AME which faces the reactive zone of the reactive face of the plate, the AMEs generally have a slightly greater thickness and / or a locally greater mechanical rigidity. This extra thickness is generally due to the local superposition of several layers of components. The locally greater rigidity of the periphery of the AME is generally due to a lower residual compressibility of the gas diffusion layer ("GDL" for "Gas Diffusion Layer" in English) which composes the AME.

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

[0008] Generally, significant tightening of the stack of cells makes it possible to effectively compress the AME.

[0009] However, this additional clamping force is applied to all the components ensuring the clamping of the stack of cells (end plates, connecting means, geometric variation compensation system, etc.) and results in an overdischarge. sizing of these, which results in a higher cost, greater weight and volume, and a clamping tool that is also oversized.

[0010] One solution consists of hollowing out the plate, on the periphery of the reactive zone, to reduce the force transfer and therefore reduce the clamping force to be applied to obtain the correct compression rate 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 high.

[0012] An aim of the present invention is to overcome all or part of the drawbacks 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 opposite 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 reactant, 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 while being intended for clamping the Membrane Electrode Assembly, the peripheral sealing zone being configured to surround the clamping band while being intended to form jointly with the Membrane Electrode Assembly,sealing the cell with respect to the reagent, the thinned portion being arranged 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 FAME compression rate, 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 strip is configured to surround the reactive zone over its entire periphery.

[0018] According to one embodiment, the clamping strip is configured to at least partially surround the reactive zone while 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 such that the reagent entering the channels circulates in the channels without bypassing them and that the circulating reagent in the channels only comes out of the channels at their output.

[0020] According to one embodiment, the clamping strip is continuous, surrounding the reactive zone over its entire periphery.

[0021] According to one embodiment, the peripheral sealing zone is configured to surround the clamping strip around the entire periphery of the clamping strip.

[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 strip, the first thickness being in particular between 60 μm and 120 μm.

[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 by the first thickness determined relative to the teeth.

[0028] According to one embodiment, the peripheral sealing zone comprises a peripheral seal groove in particular configured to receive a seal.

[0029] Alternatively, the peripheral sealing zone comprises at least one elevation configured to compress a sealed reinforcing 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 seal groove is set back by a second determined thickness relative to the clamping strip, 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 comprises a reagent collection orifice formed through the plate and configured to be in fluid communication with the reactive zone via a lumen formed through the plate, the plate being in particular configured so that the clamping band at least partially surrounds the lumen.

[0033] According to one embodiment, the plate is configured so that the clamping band surrounds the light all around 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 seal groove surrounds the collector orifice, in particular over its entire periphery, 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 characteristics above or below and a Membrane Electrode Assembly, the Membrane Electrode Assembly comprising a membrane coated with a catalyst and a sealed reinforcing element, a peripheral strip of the membrane being pinched by the sealed reinforcing element, the Membrane Electrode Assembly further comprising a gas diffusion layer sandwiching the membrane and a portion of the sealed reinforcing 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 CCM type membrane.

[0037] According to one embodiment, the reactive surface is defined by the surface of the gas 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 sealed reinforcement.

[0041] The invention also relates to an assembly conforming to any one of the characteristics above or below, 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 bead; - the clamping strip is opposite a first portion of the bead, applying a first clamping force to the first portion; - the thinned portion is opposite a second portion of the bead, in particular 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 reinforcing element waterproof, 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 notably measured in the direction of the width of the clamping strip 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 characteristics above or below 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, on 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 characteristics above or below and / or a stack of assemblies conforming to any one of the characteristics above or below.

[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 for illustrative purposes but 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 sectional view illustrating an assembly capable of implementing the invention; and

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

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

[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 face cooling defining a path for a cooling fluid.

[0055] The plate 1 is intended to come into contact with the Membrane Electrode Assembly (4), in particular via the reactive face of the 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 comprises a reactive zone 2, a clamping strip 9, a thinned portion 3 and a peripheral sealing zone 12.

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

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

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

[0061] The clamping strip 9 is configured to surround the reactive zone 2 over its entire periphery. This clamping strip 9 makes it possible to form, together with the Membrane Electrode Assembly 4, a sealing bead for the reactive fluid entering the channels 5. This makes it possible to prevent the reactive fluid entering the channels 5 from being able to bypass the channels 5.

[0062] The clamping strip 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 strip 9 is configured to form a seal between the reactive zone and the Membrane Electrode Assembly 4 so that the reagent entering the channels 5 circulates in the channels 5 without bypassing them and the reagent circulating in the channels 5 only exits the channels 5 at their end.

[0064] The clamping strip 9 is continuous, surrounding the reactive zone around its entire circumference.

[0065] The peripheral sealing zone 12 is configured to surround the clamping strip 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 arranged between the peripheral sealing zone 12 and the clamping strip 9.

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

[0068] The plate 1 comprises 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 strip 9.

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

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

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

[0073] The peripheral sealing zone 12 comprises a peripheral seal groove 12 configured in particular to receive a seal.

[0074] The plate 1 is configured so that, in the direction transverse to the plane of the plate 1, the peripheral seal groove 12 is set back by a second determined thickness H2 relative to the clamping strip 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 the plate 1.

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

[0077] The plate 1 is configured so that the clamping band 9 surrounds the lumen 10 around its entire periphery so that the reagent passing through the lumen 10 can only pass between the collector orifice 8 and the channels 5.

[0078] The plate 1 is configured so that the peripheral seal groove 12 surrounds the collector orifice 8, in particular over its entire periphery, being arranged 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 the plate 1 of [Fig.l] and a Membrane Electrode Assembly 4.

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

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

[0083] The Membrane Electrodes 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

[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”. We can speak more simply of a CCM.

[0086] The assembly 26 is intended to be assembled in a fuel cell stack. The 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 strip 9 is opposite a first portion PI of the bead 24, applying a first clamping force to the first portion PI; - the thinned portion 3 is opposite a second portion P2 of the bead 24, in particular by applying a second clamping force to 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 sealed reinforcement element 28, in particular without coming into contact with the gas 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 notably measured in the direction of the width of the clamping strip 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 second plate 21 sandwich the Membrane Electrodes Assembly 4.

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

[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 enclosing the stack of cells 6 and the joining means.

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

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

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

Claims

Claims

1. Fuel cell plate (1), of the proton exchange membrane type, intended to come into contact with a Membrane Electrode Assembly (4), the plate (1) comprising two opposite 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 circulation channels (5) for a reactant, 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) while being intended for clamping the Membrane Electrode Assembly (4),the peripheral sealing zone (12) being configured to surround the clamping strip (9) and being intended to form, together with the Membrane Electrode Assembly (4), a seal of the cell with respect to the reagent, the thinned portion (3) being arranged between the peripheral sealing zone (12) and the clamping strip (9).,

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

3. Plate according to one of the preceding claims, the peripheral sealing zone (12) comprising a peripheral seal groove (12) in particular configured to receive a seal.

4. Plate (1) according to the preceding claim, the plate (1) being configured so that, in the direction transverse to the plane of the plate (1), the peripheral seal groove (12) is set back by a second thickness (H2) determined relative to the clamping strip (9), the second determined thickness (H2) being greater than the first determined thickness (H1).

5. Plate (1) according to one of the preceding claims, comprising a reagent collecting orifice (8) formed through the plate (1) and configured to be in fluid communication with the reactive zone (2) via a lumen (10) formed through the plate (1), the plate (1) being in particular configured so that the strip of clamping (9) at least partially surrounds the lumen (10).

6. Plate (1) according to one of the preceding claims, being configured so that the peripheral seal groove (12) surrounds the collector orifice (8), in particular over its entire periphery, being arranged between the collector orifice (8) and the thinned portion (3), in a direction parallel to the plane of the plate (1).

7. Fuel cell assembly (26) comprising a plate (1) according to one of the preceding claims and a Membrane Electrode Assembly (4), the Membrane Electrode Assembly (4) comprising a membrane (27) coated with a catalyst and a sealed reinforcing element (28), a peripheral strip of the membrane being pinched by the sealed reinforcing element (28), the Membrane Electrode Assembly (4) further comprising a gas diffusion layer (29) sandwiching the membrane (27) and a portion of the sealed reinforcing element (28), the Membrane Electrode Assembly (4) having 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).

8. Assembly (26) according to the preceding claim, 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 bead (24); - the clamping strip (9) is opposite a first portion (PI) of the bead (24), by applying a first clamping force to 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 to 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 sealed reinforcing element (28), in particular without coming into contact with the gas diffusion layer (29).

9. Assembly (26) according to the preceding claim, being configured of such that a second width of the second portion (P2) is greater than a first width of the first portion (PI), the widths being notably measured in the direction of the width of the clamping strip (9) which is opposite the first portion (PI) considered.

10. Fuel cell cell (6) comprising an assembly (26) according to one of claims 7 to 9 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, on at least 80% of the bead (24).

11. Fuel cell comprising a stack of cells (6) according to claim 10 and / or a stack of assemblies (26) according to one of claims 7 to 9.

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