Bipolar structure for a fuel cell stack

Abstract

Bipolar Structure for a Fuel Cell Stack The invention relates to a bipolar structure (100) for a fuel cell stack, comprising a first plate (1) and a second plate (2) assembled one on top of the other, each having a cooling face (4) and a reactive face (3), the reactive face (3) being intended to come into contact with a membrane electrode assembly, the structure (100) having a peripheral rim (11) having a clamping band (12) for clamping the membrane electrode assembly in the stack, the clamping band (12) having a first section (13) and a second section (14), the clamping band (12) having a first restriction (16) configured to limit the circulation of the cooling fluid between the first section (13) and the second section (14). Abstract figure: Fig. 1

Description

Title of the invention: Bipolar structure for a fuel cell stack

[0001] The present invention relates to a bipolar structure for a fuel cell stack, a fuel cell and a fuel cell.

[0002] In a manner known per se, a fuel cell is an electrochemical device which makes it possible to convert chemical energy into electrical energy from a fuel, generally dihydrogen, and an oxidant, generally dioxygen or a gas containing it such as air, the product of the reaction being water accompanied by a release of heat and a production of electricity.

[0003] A fuel cell consists of a stack of bipolar structures sandwiching a membrane electrode assembly. It is known to produce such structures by assembling two plates together. Each plate has a cooling face intended to come into contact with the cooling face of another plate, forming a cooling circuit for the circulation of a heat transfer fluid. Each plate also has a reactive face opposite the cooling face, the reactive face being intended to come into contact with a membrane electrode assembly.

[0004] The circulation of a first reactive fluid, namely the oxidant or the fuel, is carried out by the presence of reactive fluid channels made on the reactive face of the plate, for the circulation of the first reactive fluid.

[0005] Furthermore, the fuel cell needs to be cooled to ensure that its operating temperature is maintained.

[0006] Usually, fuel cells are cooled by the circulation of a heat transfer fluid, to serve as a cooling fluid, intended to circulate in a cooling circuit produced jointly by the cooling face of one plate and the cooling face of the other plate.

[0007] For the manufacture of the plates of such a structure, it is known to form reliefs and hollows on the faces of each plate. It is known, for example, to form the plates by plastic deformation, for example by stamping or hydroforming.

[0008] Such a method of manufacturing the plates involves specific constraints for the positioning and shape of each relief and each hollow, it being understood that any relief formed on one of the faces of a plate necessarily has a complementary hollow formed on the other of the faces of the same plate. This is generated by the method of forming the plates as mentioned above.

[0009] State-of-the-art bipolar structures have a parasitic conduit induced by the need to form a strip to hold the membrane electrode assembly, the strip being generally formed by a relief of the reactive face of the plate. This parasitic conduit extends between the two plates, as does the cooling circuit.

[0010] One problem is that the heat transfer fluid (in other words, the cooling fluid) does not circulate only in the cooling circuit because a significant portion is diverted inside the parasitic conduit. However, the cooling fluid is necessary for the cooling of the portion of the bipolar structure which is involved in the chemical reaction allowing the conversion of chemical energy into electrical energy. Thus, with the bipolar structures of the prior art, the cooling of the bipolar structure is not optimal and the efficiency of the fuel cell is significantly impacted.

[0011] The present invention aims to effectively remedy these drawbacks by proposing a bipolar structure for a fuel cell stack, comprising a first plate and a second plate assembled on top of each other, each comprising a cooling face and a reactive face, the reactive face being intended to come into contact with a membrane electrode assembly, the structure comprising: - a cooling circuit extending between the cooling face of the first plate and the cooling face of the second plate, the cooling circuit comprising a plurality of cooling conduits delimited at least partially by a first corrugated portion of the first plate, the cooling conduits being intended to allow the circulation of a cooling fluid; - a cooling fluid distribution circuit extending between the cooling face of the first plate and the cooling face of the second plate, being fluidically connected to a cooling fluid inlet manifold orifice and to the cooling circuit, the cooling fluid distribution circuit extending at least partially over a second portion of the first plate; - a peripheral edge extending around the peripheral periphery of the structure, the peripheral edge comprising a clamping strip for clamping the membrane electrode assembly in the stack, the clamping strip comprising a first section and a second section each comprising a raised portion on the side of the reactive face of the first plate and a complementary hollow portion on the side of the cooling face of the first plate, the complementary hollow portion defining a parasitic conduit extending between the cooling face of the first plate and the cooling face of the second plate, the parasitic conduit of the first section being in fluid communication with the cooling fluid distribution circuit, the clamping band comprising a first restriction configured to limit the circulation of the cooling fluid between the parasitic conduit of the first section and the parasitic conduit of the second section.

[0012] Such a restriction at the clamping band makes it possible to limit the circulation of cooling fluid inside the parasitic duct formed by the complementary hollow portion on the side of the cooling face of the first plate, at the clamping band of the membrane electrode assembly. Such a restriction forms a separation between the first section and the second section, which makes it possible to contain the cooling fluid inside the parasitic duct of the first section by limiting or preventing the circulation of this fluid towards the parasitic duct of the second section.

[0013] According to one embodiment, the first plate and / or the second plate is formed by plastic deformation, for example by stamping or hydroforming.

[0014] According to one embodiment, the first restriction comprises a first restriction groove provided on the reactive face of the first plate.

[0015] According to one embodiment, the first section is configured to form a separation wall between the second portion of the first plate and the peripheral periphery of the structure.

[0016] According to one embodiment, the first section is configured to further form a separation wall between the first portion of the first plate and the peripheral periphery of the structure.

[0017] According to one embodiment, the second section is configured to form a separation wall between the first portion of the first plate and the peripheral periphery of the structure.

[0018] According to one embodiment, the first restriction is configured to open through one of its ends onto the first corrugated portion of the first plate.

[0019] According to one embodiment, the first restriction groove of the first plate is configured to come into contact with a first complementary restriction groove of the second plate, in particular by being welded together so as to restrict or prevent any passage for the cooling fluid between the parasitic conduit of the first section and the parasitic conduit of the second section.

[0020] According to one embodiment, the first restriction groove is configured to pass through the clamping strip in its width so as to separate the first section from the second section.

[0021] According to one embodiment, the first restriction comprises a first restriction seal arranged on the reactive face of the first plate, the first restriction joint being in particular configured to allow the membrane electrode assembly to be clamped in the stack, for example by forming a peak of substantially the same height as that of the raised portion of the first section and / or the second section.

[0022] According to one embodiment, the first restriction seal is configured to be arranged in the first restriction without extending beyond the first corrugated portion of the first plate.

[0023] According to one embodiment, the peripheral edge comprises a peripheral groove for receiving a reactive face seal, the reactive face seal being in particular continuous around the entire periphery of the structure to form a sealing bead with the membrane electrode assembly.

[0024] According to one embodiment, the first restriction seal having a nominal height between 50% and 120% of the nominal height of the reactive face seal.

[0025] According to one embodiment, the first restriction opens into the peripheral groove, the first restriction seal being in particular configured to come into contact with the reactive face seal.

[0026] According to one embodiment, the first section comprises a second restriction configured to limit a passage section for the cooling fluid between the cooling fluid distribution circuit and the parasitic conduit of the first section.

[0027] According to one embodiment, the structure comprises a first reagent circuit comprising a plurality of first reagent fluid channels, intended to allow the circulation of a first reagent fluid, the first reagent fluid channels being arranged on the side of the reactive face of the first plate extending over the first corrugated portion, the first reagent circuit being in particular intended to come into contact with the membrane electrode assembly.

[0028] According to one embodiment, the structure comprises a distribution circuit for the first reactive fluid extending over the second portion of the first plate, on the side of the reactive face of the first plate, being arranged between a first reactive fluid inlet collector orifice and the first reactive circuit.

[0029] According to one embodiment, the second section is configured to form a wall of one of the first reactive fluid channels.

[0030] The invention further relates to a fuel cell comprising two structures as described above and a membrane electrode assembly, the membrane electrode assembly being sandwiched between the two structures.

[0031] The invention finally relates to a fuel cell comprising a stack comprising a plurality of cells as described above.

[0032] The invention will be better understood upon reading the following description and upon examining accompanying figures. These figures are given only for illustrative purposes but in no way limit the invention.

[0033] [Fig-1] [Fig. 1] is a representation in elevation and in section, of a detail of a structure according to the invention;

[0034] [Fig.2] [Fig.2] is a representation in elevation and in section, of another detail of the structure of [Fig.l].

[0035] [Fig.3] [Fig.3] is an elevational representation of another detail of the structure of figures 1 and 2; and

[0036] [Fig.4] [Fig.4] is a schematic and elevational representation of a cell of fuel cell according to the invention.

[0037] With reference to [Fig.4], a fuel cell 101 is shown comprising a membrane electrode assembly 23 sandwiched between the two bipolar structures 100.

[0038] With reference to [Fig. 3], a detail of such a bipolar structure 100 is shown in elevation. [Fig. 1] represents, in section along BB, another detail of the bipolar structure 100 of [Fig. 3]. [Fig. 3] represents, in section along AA, another detail of the bipolar structure 100 of [Fig. 3].

[0039] With reference to figures 1 to 3, the bipolar structure 100 comprises a first plate 1 and a second plate 2 assembled on top of each other, each comprising a cooling face 4 and a reactive face 3.

[0040] The first plate 1 and the second plate 2 are both formed by plastic deformation, for example by stamping or hydroforming.

[0041] The reactive face 3 is intended to come into contact with the membrane electrode assembly 23.

[0042] The structure 100 comprises a cooling circuit 5 extending between the cooling face 4 of the first plate 1 and the cooling face 4 of the second plate 2. The cooling circuit 5 comprises a plurality of cooling conduits 6 delimited at least partially by a first corrugated portion 7 of the first plate 1, the cooling conduits 6 being intended to allow the circulation of a cooling fluid.

[0043] The structure 100 comprises a cooling fluid distribution circuit 8 extending between the cooling face 4 of the first plate 1 and the cooling face 4 of the second plate 2, being fluidically connected to a cooling fluid inlet collector orifice 9 and to the cooling circuit 5. The cooling fluid distribution circuit 8 extends at least partially over a second portion 10 of the first plate 1.

[0044] The structure 100 comprises a peripheral border 11 extending around the peripheral periphery of the structure 100. The peripheral border 11 comprises a strip of clamping 12 for clamping the membrane electrode assembly 23 in the stack. The clamping strip 12 comprises a first section 13 and a second section 14 each comprising a raised portion on the side of the reactive face 3 of the first plate 1 and a complementary hollow portion on the side of the cooling face 4 of the first plate 1.

[0045] As shown in [Fig. 1], the complementary hollow portion forms a parasitic conduit 15 extending between the cooling face 4 of the first plate 1 and the cooling face 4 of the second plate 2.

[0046] The parasitic conduit 15 of the first section 13 is in fluid communication with the cooling fluid distribution circuit 8.

[0047] The clamping band 12 comprises a first restriction 16 configured to limit the circulation of the cooling fluid between the parasitic conduit 15 of the first section 13 and the parasitic conduit 15 of the second section 14.

[0048] The first restriction 16 comprises a first restriction groove 16 formed on the reactive face 3 of the first plate 1.

[0049] The first section 13 is configured to form a separation wall between the second portion 10 of the first plate 1 and the peripheral periphery of the structure 100. In other words, the first section 13 being formed by a relief of the first plate, it forms jointly with the membrane electrode assembly with which it is compressed, a separation wall between the second portion 10 of the first plate 1 and the peripheral periphery of the structure 100.

[0050] The first restriction 16 opens through one of its ends onto the first corrugated portion 7 of the first plate 1.

[0051] The first restriction groove 16 of the first plate 1 is configured to come into contact with a first complementary restriction groove 16 of the second plate 2, in particular by being welded together so as to restrict or prevent the passage of the cooling fluid between the parasitic conduit 15 of the first section 13 and the parasitic conduit 15 of the second section 14.

[0052] The first restriction groove 16 is configured to cut the clamping strip 12 across its width, so as to separate the first section 13 from the second section 14.

[0053] The first restriction 16 comprises a first restriction seal 24 disposed in the first restriction groove 16.

[0054] The first restriction seal 24 is configured to allow the membrane electrode assembly 23 to be clamped in the stack, for example by forming a peak whose height is at least equal to the height of the raised portion of the first section 13 and / or of the second section 14.

[0055] The first restriction seal 24 is configured to be disposed in the first restriction groove 16 without extending over the first corrugated portion 7 of the first plate 1. This avoids impacting the circulation of the first reactive fluid at the level of the reactive face 3 of the first plate 1.

[0056] The peripheral edge 11 comprises a peripheral groove 17 in particular for receiving a reactive face seal 22.

[0057] The reactive face seal 22 is continuous, extending around the entire perimeter of the structure 100 to form a sealing bead with the membrane electrode assembly 23.

[0058] The first restriction 16 opens into the peripheral groove 17. The first restriction seal 24 is configured to come into contact with the reactive face seal 22.

[0059] The first section 13 comprises a third restriction 21 configured to limit a passage section for the cooling fluid between the cooling fluid distribution circuit 8 and the parasitic conduit 15 of the first section 13.

[0060] The third restriction 21 comprises a third restriction groove 21 formed on the reactive face 3 of the first plate 1.

[0061] The third restriction groove 21 of the first plate 1 is configured to come into contact with a third complementary restriction groove of the second plate 2, in particular by being welded together so as to restrict the passage for the cooling fluid between the cooling fluid distribution circuit 8 and the parasitic conduit 15 of the first section 13.

[0062] The third restriction groove 21 is configured to extend substantially in the direction in which the first section 13 extends.

[0063] The third restriction 21 comprises a third restriction seal arranged in the third restriction groove 21. The third restriction seal is configured to allow the membrane electrode assembly 23 to be clamped in the stack, for example by forming a peak whose height is at least equal to the height of the raised portion of the first section 13 and / or of the second section 14.

[0064] The third restriction seal makes it possible to better channel the flows of the first reactive fluid on the side of the reactive face 3.

[0065] The structure 100 comprises a first reagent circuit 18 comprising a plurality of first reagent fluid channels 19, intended to allow the circulation of a first reagent fluid, the first reagent fluid channels 18 being arranged on the side of the reactive face 3 of the first plate 1 extending over the first corrugated portion, the first reagent circuit 18 being in particular intended to come into contact with the membrane electrode assembly 23.

[0066] The structure 100 comprises a distribution circuit for the first reactive fluid 20 extending over the second portion 10 of the first plate 1, on the side of the reactive face 3 of the first plate 1, being arranged between a first reactive fluid inlet collector orifice 26 and the first reactive circuit 18.

[0067] The first section 13 extends over a first length. The second section 14 extends over a second length. The second length is strictly greater than the first length. More precisely, the second length is strictly greater than twice the first length.

[0068] The clamping strip 12 comprises a second restriction 25 configured to limit the circulation of the cooling fluid between the parasitic conduit 15 of the first section 13 and the parasitic conduit 15 of the second section 14. The second restriction 25 comprises a second restriction groove 25 formed on the reactive face 3 of the first plate 1. The second restriction 25 opens via one of its ends onto the first corrugated portion 7 of the first plate 1.

[0069] The second restriction 25 comprises a second restriction seal arranged in the second restriction groove 25. The second restriction seal 25 is configured to allow the membrane electrode assembly 23 to be clamped in the stack, for example by forming a peak whose height is at least equal to the height of the raised portion of the first section 13 and / or of the second section 14.

[0070] The second restriction seal is configured to be arranged in the second restriction groove without overflowing onto the first corrugated portion 7 of the first plate 1.

Claims

Claims

1. Bipolar structure (100) for a fuel cell stack, comprising a first plate (1) and a second plate (2) assembled on top of each other, each comprising a cooling face (4) and a reactive face (3), the reactive face (3) being intended to come into contact with a membrane electrode assembly (23), the structure (100) comprising: - a cooling circuit (5) extending between the cooling face (4) of the first plate (1) and the cooling face (4) of the second plate (2), the cooling circuit (5) comprising a plurality of cooling ducts (6) delimited at least partially by a first corrugated portion (7) of the first plate (1), the cooling ducts (6) being intended to allow the circulation of a cooling fluid; - a cooling fluid distribution circuit (8) extending between the cooling face (4) of the first plate (1) and the cooling face (4) of the second plate (2), being fluidically connected to a cooling fluid inlet collector orifice (9) and to the cooling circuit (5), the cooling fluid distribution circuit (8) extending at least partially over a second portion (10) of the first plate (1); - a peripheral edge (11) extending over the peripheral periphery of the structure (100), the peripheral edge (11) comprising a clamping strip (12) for clamping the membrane electrode assembly in the stack, the clamping strip (12) comprising a first section (13) and a second section (14) each comprising a raised portion on the side of the reactive face (3) of the first plate (1) and a complementary hollow portion on the side of the cooling face (4) of the first plate (1), the complementary hollow portion defining a parasitic conduit (15) extending between the cooling face (4) of the first plate (1) and the cooling face (4) of the second plate (2), the parasitic conduit (15) of the first section (13) being in fluid communication with the dis- coolant supply (8), the clamping band (12) comprising a first restriction (16) configured to limit the circulation of the coolant between the parasitic conduit (15) of the first section (13) and the parasitic conduit (15) of the second section (14).

2. Structure (100) according to the preceding claim, the first restriction (16) comprising a first restriction groove (16) formed on the reactive face (3) of the first plate (1).

3. Structure (100) according to the preceding claim, the first section (13) being configured to form a separation wall between the second portion (10) of the first plate (1) and the peripheral periphery of the structure (100).

4. Structure (100) according to one of the preceding claims, the first restriction (16) being configured to open via one of its ends onto the first corrugated portion (7) of the first plate (1).

5. Structure (100) according to one of the preceding claims, the first restriction (16) comprising a first restriction joint (24) arranged on the reactive face (3) of the first plate (1), the first restriction joint (24) being in particular configured to allow the membrane electrode assembly to be clamped in the stack, for example by forming a peak substantially of the same height as that of the raised portion of the first section (13) and / or of the second section (14).

6. Structure (100) according to the preceding claim, the first restriction seal (24) being configured to be arranged in the first restriction (16) without extending over the first corrugated portion (7) of the first plate (1).

7. Structure (100) according to one of the preceding claims, the peripheral edge (11) comprising a peripheral groove (17) for receiving a reactive face seal (22), the reactive face seal (22) being in particular continuous around the entire periphery of the structure (100) to form a sealing bead with the membrane electrode assembly.

8. Structure (100) according to one of the preceding claims, the first section (13) comprising a third restriction (21) configured to limit a passage section for the cooling fluid between the cooling fluid distribution circuit (8) and the conduit

9. parasitic (15) of the first section (13). Fuel cell (101) comprising two structures (100) according to one of the preceding claims and a membrane electrode assembly (23), the membrane electrode assembly (23) being sandwiched between the two structures (100).

10. Fuel cell comprising a stack comprising a plurality of cells (101) according to the preceding claim.

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