Fuel cell stack and fuel cell comprising such a stack

Abstract

The invention relates to an assembly (1) comprising a stack of a plurality of fuel cell cells, each comprising an anodic plate (10) and a cathodic plate (20), each comprising a reactive face and a cooling face. The reactive face is provided with raised and recessed areas forming a reactive circuit comprising a plurality of first cavities (51, 52). The cooling face forms a cooling circuit comprising a plurality of second cavities (55). Each plate (10, 20) has a third cavity (53, 54) for receiving a seal. Each plate (10, 20) is configured such that the average depth (P1, P2, P3, P4, P5) of all the cavities is equal. (Shorthand figure: Fig. 2)

Description

Title of the invention: Stack of fuel cell cells and fuel cell comprising such a stack

[0001] The present invention relates to an assembly comprising a stack of fuel cell cells and a fuel cell comprising such an assembly.

[0002] The invention relates more particularly to an assembly comprising a stack of a plurality of proton exchange membrane fuel cell cells in which the cells each comprise an anode plate and a cathode plate sandwiching a Membrane Electrode Assembly (MEA).

[0003] Fuel cell cells (anode side and cathode side) generate heat (chemical reactions within the cell are exothermic) and must be cooled by a cooling circuit.

[0004] In the case of a cell composed of two plates sandwiching a Membrane Electrode Assembly, each plate (anodic or cathodic) comprises a side dedicated to the circulation of reactive gases (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 (often a liquid).

[0005] A fuel cell plate, in particular a monopolar plate, dedicated to the circulation of reactants, reaction products, and a heat transfer fluid, usually has cavities of different depths, particularly in the case of machined plates such as machined graphite plates.

[0006] The air circuit is often relatively deep to reduce the pressure drop associated with the supply of air at high excess flow (typically by a factor of 2), while the seal groove can have different geometries, depending on the sealing objectives and the limits of the manufacturing processes.

[0007] The plate thus obtained exhibits fragility in the areas of reduced canvas thickness while remaining relatively thick overall. The choice of the thickness of the plate is a compromise between the depth of the cavities which are arranged opposite each other and the thickness of the canvas (the reduced thickness of the plate which one wishes to maintain at the location where the cavities are arranged opposite each other).

[0008] The present invention aims to effectively overcome these drawbacks by proposing an assembly comprising a stack of a plurality of proton exchange membrane fuel cell cells, each cell of the plurality comprising an anode plate and a cathode plate sandwiching a Membrane Electrode Assembly, each plate comprising a reactive face and a cooling face opposite each other, the reactive face of each plate being intended to face the Membrane Electrodes Assembly and being provided with reliefs and hollows forming a reagent circuit for the circulation of a reactive fluid, the reagent circuit comprising a plurality of first cavities arranged on the reactive face of the plate, the cooling face of the cathode plate of at least one of the cells being intended to face the cooling face of the anode plate of another of the cells, defining between them reliefs and hollows to form a cooling circuit for the circulation of a cooling fluid, the cooling circuit comprising a plurality of second cavities arranged on the cooling face of the anode plate and / or the cathode plate, each plate comprising at least a third cavity for receiving a seal, the third cavity being arranged on the reactive face of the anode plate and / or the cathode plate,each cavity having an average depth, the depth being measured in a plane orthogonal to the plane of the plate intersecting the cavity, the plate being configured so that the average depths of all the cavities are equal, in particular to within 10%.

[0009] Such an arrangement makes it possible to significantly reduce the thickness of a plate, and therefore the thickness of the assembly. This also makes it possible to significantly improve the compactness / fragility ratio of the plate of such an assembly. Typically, for a state-of-the-art plate that would be 2.7 mm thick, such an arrangement makes it possible to gain 0.7 mm in thickness without affecting its strength.

[0010] According to one embodiment, the first cavities are intended to allow the circulation of the reactive fluid.

[0011] According to one embodiment, the second cavities are intended to allow the circulation of the cooling fluid.

[0012] According to one embodiment, each plate comprises a reagent inlet manifold formed through the plate and being in fluid communication with the reagent circuit, a reagent outlet manifold formed through the plate and being in fluid communication with the reagent circuit, a cooling fluid inlet manifold formed through the plate, a cooling fluid outlet manifold formed through the plate.

[0013] According to one embodiment, the plate comprises at least a first lumen formed through the plate and a plurality of fourth cavities arranged on the cooling face of the plate, each fourth cavity opening at one end into the reagent inlet manifold or the reagent outlet manifold and at another end into the first lumen, each fourth cavity having an average depth, the depth being measured in a plane orthogonal to the plane of the plate intersecting the fourth cavity, the plate being configured so that the average depth of each fourth cavity is equal to the average depth of each first, second and third cavities, in particular to within 10%.

[0014] According to one embodiment, the reagent circuit opens into the first lumen.

[0015] According to one embodiment, the first lumen and the fourth cavities are configured to put the reagent inlet manifold into fluid communication with the reagent circuit.

[0016] According to one embodiment, the first lumen and the fourth cavities are configured to put the reagent outlet manifold in fluid communication with the reagent circuit.

[0017] According to one embodiment, the first lumen and the fourth cavities are configured to allow the reactive fluid entering through the reactive inlet manifold to successively circulate in the plurality of fourth cavities, pass through the first lumen, circulate in the plurality of first cavities.

[0018] According to one embodiment, the first lumen and the fourth cavities are configured to allow the reactive fluid circulating in the plurality of first cavities to successively pass through the first lumen, circulate in the plurality of fourth cavities, and circulate in the reactive outlet manifold.

[0019] According to one embodiment, the plurality of cells comprises a first cell at a first end of the stack and a last cell at a second end of the stack, the assembly comprising a closure plate comprising an electric current collection face intended to face a first electric current collector plate and a closure face fixed to the cooling face of one of the plates of the last cell, the closure face being in particular glued or welded to said cooling face.

[0020] According to one embodiment, the assembly comprises a distribution plate comprising an external face intended to face an interface plate with an inlet and outlet pipe for the cooling fluid and with an inlet and outlet pipe for the reactive fluid, the distribution plate comprising an internal face fixed to the cooling face of one of the plates of the first cell, the internal face being in particular glued or welded to said cooling face.

[0021] According to one embodiment, there is a ratio between the average depth of the cavities and the maximum thickness of the plate, the ratio being between 25 and 50%, in particular between 30% and 45%.

[0022] According to one embodiment, the maximum thickness of the plate is measured in a plane orthogonal to the plane of the plate and being measured on a portion of the plate which is devoid of cavities on its reactive face and on its cooling face.

[0023] According to one embodiment, the anodic plate and the cathodic plate are each produced by a machined plate.

[0024] The invention is particularly advantageous in the case of machined plates because with this type of plates, the robustness of such a plate is dependent on the different material shrinkages.

[0025] According to one embodiment, the plate comprises graphite or a carbon-based composite material.

[0026] The invention further relates to a fuel cell comprising an assembly as described above.

[0027] According to one embodiment, the cell comprises a first electric current collector plate, a second electric current collector plate and an interface plate with an inlet and outlet pipe for the cooling fluid and the reactive fluid.

[0028] The invention will be better understood upon reading the following description and examining the figures. These figures are given only for illustrative purposes but in no way limit the invention.

[0029] [Fig-1] [Fig.l] is a schematic perspective representation of a set according to the invention;

[0030] [Fig.2] [Fig.2] is a schematic and sectional representation of two plates of the assembly of [Fig.l];

[0031] [Fig.3] [Fig.3] is a schematic, cross-sectional representation of a plate of the assembly of [Fig.l]; and

[0032] [Fig.4] [Fig.4] is a schematic and sectional representation of a portion of a battery according to the invention.

[0033] Identical, similar, or analogous elements retain the same reference from one figure to another.

[0034] [Fig.l] represents an assembly 1 comprising a stack of a plurality of proton exchange membrane fuel cell cells 30.

[0035] The plurality of cells 30 comprises a first cell 30 at a first end of the stack and a last cell 30 at a second end of the stack.

[0036] Each cell 30 of the plurality comprises an anode plate 10 and a cathode plate 20 sandwiching a Membrane Electrode Assembly 16. Each plate (anode plate 10 and cathode plate 20) comprises a reactive face and a cooling face opposite each other. The reactive face of each plate 10, 20 is intended to face the Membrane Electrode Assembly 16 (or MEA) and is provided with reliefs and hollows forming a reactive circuit for the circulation of a reactive fluid.

[0037] Each plate 10, 20 comprises a reagent inlet manifold 3, 4 formed through the plate 10, 20 and being in fluid communication with the reagent circuit, a reagent outlet manifold 6, 7 formed through the plate 10, 20 and being in fluid communication with the reagent circuit, a reagent fluid inlet manifold 7 formed through the plate 10, 20 and being in fluid communication with the reagent circuit, a reagent fluid outlet manifold 8 formed through the plate 10, 20 and being in fluid communication with the reagent circuit, a reagent fluid outlet manifold 9 formed through the plate 10, 20 and being in fluid communication with the reagent circuit, a reagent fluid outlet manifold 10 formed through the plate 10, 20 and being in fluid communication with the reagent circuit, a reagent fluid outlet manifold 11 formed through the plate 10, 20 and being in fluid communication with the reagent circuit, a reagent fluid outlet mani cooling 5 formed through the plate 10, 20, a cooling fluid outlet manifold 8, 9 formed through the plate 10, 20.

[0038] In the example of [Fig.l], the assembly 1 further comprises a closure plate 21 comprising an electric current collection face intended to face a first electric current collector plate and a closure face fixed to the cooling face of one of the plates 10, 20 of the last cell 30, the closure face being in particular glued or welded to said cooling face.

[0039] In the example of [Fig.l], the assembly 1 also comprises a distribution plate 11.

[0040] The cooling face of the cathode plate 20 of at least one of the cells 30 is intended to face the cooling face of the anode plate 10 of another of the cells 30, defining between them reliefs and hollows to form a cooling circuit 15 for the circulation of a cooling fluid.

[0041] [Fig. 2] schematically represents in section, an anode plate 10 and a cathode plate 20 of the assembly of [Fig. 1]. The plates (10, 20) are here assembled by gluing to each other, to form a bipolar plate. Alternatively, the plates (10, 20) are juxtaposed to form a bipolar plate, the sealing of the bipolar connection being ensured by a seal.

[0042] [Fig.3] schematically represents in section one of the plates (10, 20) of [Fig.2],

[0043] The reagent circuit comprises a plurality of first cavities 51, 52 for the circulation of the reagent fluid 60. In [Fig. 3], the reagent fluid 60 is shown with an arrow indicating its direction of circulation from the reagent inlet manifold 3, 4 to the reagent circuit.

[0044] The first cavities 51, 52 are provided on the reactive face of the plate 10, 20.

[0045] The cooling circuit 15 comprises a plurality of second cavities 55 arranged on the cooling face of the anode plate 10 and / or the cathode plate 20.

[0046] Each plate 10, 20 comprises at least one third cavity 53, 54 for receiving a seal, the third cavity 53, 54 being provided on the reactive face of the anode plate 10 and / or the cathode plate 20.

[0047] The seal, once tightened against the AME, prevents any leakage of the reactive fluid outside the cell.

[0048] Each cavity 51, 52, 53, 54, 55 has an average depth P1, P2, P3, P4, P5. The depth is measured in a plane orthogonal to the plane of the plate 10, 20 intersecting the cavity 51, 52, 53, 54, 55.

[0049] The plate 10, 20 is configured so that the average depths of all the cavities 51, 52, 53, 54, 55 are equal, in particular to within 10%.

[0050] The value of 10% corresponds to a tolerance generally imposed by the manufacturers of the parts making up such an assembly 1.

[0051] As visible in [Fig.2], the plate 10, 20 comprises at least a first light 2 formed through the plate 10, 20 and a plurality of fourth cavities 56 arranged on the cooling face of the plate 10, 20.

[0052] Each fourth cavity 56 opens at one end into the reagent inlet manifold 3, 4 or the reagent outlet manifold 6, 7 and at another end into the first lumen 2.

[0053] Each fourth cavity 56 has an average depth P6.

[0054] The depth is measured in a plane orthogonal to the plane of the plate 10, 20 intersecting the fourth cavity 56.

[0055] The plate 10, 20 is configured so that the average depth of each fourth cavity 56 is equal to the average depth P1, P2, P3, P4, P5 of each first, second and third cavity 51, 52, 53, 54, 55, in particular to within 10%.

[0056] There is a ratio between the average depth PI, P2, P3, P4, P5, P6 of the cavities 51, 52, 53, 54, 55, 56 and the maximum thickness of the plate 10, 20.

[0057] The maximum thickness of the plate 10, 20 is measured in a plane orthogonal to the plane of the plate and is measured on a portion of the plate which is devoid of cavities 51, 52, 53, 54, 55, 56 on its reactive face and on its cooling face.

[0058] The ratio is between 25 and 50%, in particular between 30% and 45%.

[0059] In an exemplary embodiment of the anode plate 10 or respectively of the cathode plate 20, the average depth of the cavities is equal to 0.35 mm and the maximum thickness of the plate 10, 20 is equal to 0.8 mm. In this example, the ratio is equal to 0.4375.

[0060] In this embodiment, the cathode plate 20 or respectively the anodic plate 10 has an average cavity depth of 0.35 mm and a maximum thickness of the plate 10, 20 of 1.15 mm. The ratio is equal to 0.3043.

[0061] [Fig. 4] represents a fuel cell 100 comprising an assembly 1 as described above. As represented in [Fig. 4], the distribution plate 11 comprises an external face intended to face an interface plate 17 with an inlet and outlet pipe for the cooling fluid and with an inlet and outlet pipe for the reactive fluid, the distribution plate 11 comprising an internal face fixed to the cooling face of one of the plates 10, 20 of the first cell 30, the internal face being in particular glued or welded to said cooling face.

[0062] The cell 100 comprises a first electric current collector plate, a second electric current collector plate and an interface plate 17 with an inlet and outlet pipe for the cooling fluid and the reactive fluid.

Claims

Claims

1. An assembly (1) comprising a stack of a plurality of proton exchange membrane fuel cell cells (30), each cell (30) of the plurality comprising an anode plate (10) and a cathode plate (20) sandwiching a Membrane Electrode Assembly (16), each plate (10, 20) comprising a reactive face and a cooling face opposite each other, the reactive face of each plate (10, 20) being intended to face the Membrane Electrode Assembly (16) and being provided with reliefs and hollows forming a reagent circuit for the circulation of a reactive fluid (60), the reagent circuit comprising a plurality of first cavities (51, 52) arranged on the reactive face of the plate (10, 20), the cooling face of the cathode plate (20) of at least one of the cells (30) being intended to face the face cooling the anode plate (10) of another of the cells (30),by defining between them reliefs and hollows to form a cooling circuit (15) for the circulation of a cooling fluid, the cooling circuit (15) comprising a plurality of second cavities (55) arranged on the cooling face of the anode plate (10) and / or the cathode plate (20), each plate (10, 20) comprising at least one third cavity (53, 54) for receiving a seal, the third cavity (53, 54) being arranged on the reactive face of the anode plate (10) and / or the cathode plate (20), each cavity (51, 52, 53, 54, 55) having an average depth (P1, P2, P3, P4, P5), the depth being measured in a plane orthogonal to the plane of the plate (10, 20) intersecting the cavity, the plate (10, 20) being configured so that the average depths of all cavities are equal, in particular to within 10%.,

2. Assembly (1) according to the preceding claim, each plate (10, 20) comprising a reagent inlet manifold (3, 4) formed through the plate (10, 20) and being in fluid communication with the reagent circuit, a reagent outlet manifold (6, 7) formed through the plate (10, 20) and being in fluid communication with the reagent circuit, a cooling fluid inlet manifold (5) formed through the plate (10, 20), a cooling fluid outlet manifold (8, 9) formed through the plate (10, 20).

3. Assembly (1) according to the preceding claim, the plate (10, 20) comprising at least one first lumen (2) formed through the plate (10, 20) and a plurality of fourth cavities (56) arranged on the cooling face of the plate (10, 20), each fourth cavity (56) opening at one end into the reagent inlet manifold (3, 4) or the reagent outlet manifold (6, 7) and at another end into the first lumen (2), each fourth cavity (56) having an average depth (P6), the depth being measured in a plane orthogonal to the plane of the plate (10, 20) intersecting the fourth cavity (56), the plate (10, 20) being configured so that the average depth of each fourth cavity (56) is equal to the average depth (P1, P2, P3, P4, P5) of each first, second and third cavity (51, 52, 53, 54, 55), in particular to within 10%.

4. Assembly (1) according to one of the preceding claims, the plurality of cells (30) comprising a first cell (30) at a first end of the stack and a last cell (30) at a second end of the stack, the assembly (1) comprising a closure plate (21) comprising an electric current collection face intended to face a first electric current collector plate and a closure face fixed to the cooling face of one of the plates (10, 20) of the last cell (30), the closure face being in particular glued or welded to said cooling face.

5. Assembly (1) according to the preceding claim, comprising a distribution plate (11) comprising an external face intended to face an interface plate (17) with an inlet and outlet pipe for the cooling fluid and with an inlet and outlet pipe for the reactive fluid, the distribution plate (11) comprising an internal face fixed to the cooling face of one of the plates (10, 20) of the first cell (30), the internal face being in particular glued or welded to said cooling face.

6. Assembly (1) according to one of the preceding claims, a ratio between the average depth (PI, P2, P3, P4, P5, P6) of the cavities (51, 52, 53, 54, 55, 56) and the maximum thickness of the plate (10, 20) being between 25 and 50%, in particular between 30% and 45%.

7. Assembly (1) according to the preceding claim, the maximum thickness of the plate (10, 20) being measured in a plane orthogonal to the plane of the plate and being measured on a portion of the plate which is devoid of cavities (51, 52, 53, 54, 55, 56) on its reactive face and on its cooling face.

8. Assembly (1) according to one of the preceding claims, the anodic plate (10) and the cathodic plate (20) each being produced by a machined plate.

9. Fuel cell (100) comprising an assembly (1) according to any one of the preceding claims.

10. Battery (100) according to the preceding claim, comprising a first electric current collector plate, a second electric current collector plate and an interface plate (17) with an inlet and outlet pipe for the cooling fluid and the reactive fluid.

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