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: Fuel cell stack 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 anodic plate and a cathodic plate sandwiching a Membrane Electrode Assembly (MEA).

[0003] Fuel cell cells (anode side and cathode side) generate heat (the 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) includes one side dedicated to the circulation of reactive gases (air or hydrogen) opposite the Membrane Electrode Assembly and one side, turned towards 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, products of the reaction, 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 loss associated with high overflow air supply (typically by a factor of 2), while the sealing groove can have different geometries, depending on the sealing objectives and the limitations of the manufacturing processes.

[0007] The resulting plate exhibits fragility in areas of thinner fabric while remaining relatively thick overall. The choice of plate thickness is a compromise between the depth of the cavities arranged opposite each other and the fabric thickness (the reduced plate thickness that is desired in the areas 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 anodic plate and a cathodic plate sandwiching a Membrane Electrode Assembly, each plate comprising a reactive face and a cooling face opposite to each other, the reactive face of each plate being intended to face the Membrane Electrode 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 formed 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 formed 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 formed 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 cutting 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 overall thickness. This also makes it possible to significantly improve the strength-to-weight ratio of the plate in such an assembly. Typically, for a state-of-the-art plate that is 2.7 mm thick, such an arrangement makes it possible to save 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 includes a reagent inlet manifold formed through the plate and in fluidic communication with the reagent circuit, a reagent outlet manifold formed through the plate and in fluidic communication with the reagent circuit, a cooling fluid inlet manifold formed through the plate, and a cooling fluid outlet manifold formed through the plate.

[0013] According to one embodiment, the plate comprises at least one 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 the other 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 such that the average depth of each fourth cavity is equal to the average depth of each first, second and third cavity, notably to within 10%.

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

[0015] According to one embodiment, the first light and the fourth cavities are configured to establish fluidic communication between the reagent inlet manifold and the reagent circuit.

[0016] According to one embodiment, the first light and the fourth cavities are configured to put the reagent outlet manifold into fluidic communication with the reagent circuit.

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

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

[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 sealing plate including an electric current collection face intended to face a first electric current collection plate and a sealing face fixed to the cooling face of one of the plates of the last cell, the sealing face being in particular glued or welded to said cooling face.

[0020] According to one embodiment, the assembly comprises a distribution plate including an external face intended to face an interface plate with an inlet and outlet piping of the cooling fluid and with an inlet and outlet piping of the reactive fluid, the distribution plate including 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 plaque, 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 made from a machined plate.

[0024] The invention is particularly advantageous in the case of machined plates because with For this type of plate, 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 pile comprises a first electric current collector plate, a second electric current collector plate and an interface plate with an inlet and outlet piping 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 by way of illustration and in no way limit the invention.

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

[0030] [Fig.2] [Fig.2] is a schematic and cross-sectional representation of two plates of the whole of [Fig.1];

[0031] [Fig. 3] [Fig. 3] is a schematic cross-sectional representation of a plate of the entire [Fig. 1]; and

[0032] [Fig.4] [Fig.4] is a schematic and cross-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. 1 represents an assembly 1 comprising a stack of a plurality of proton exchange membrane fuel cell 30 cells.

[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 anodic plate 10 and a cathodic plate 20 sandwiching a Membrane Electrode Assembly 16. Each plate (anodic plate 10 and cathodic plate 20) includes 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 raised and recessed areas forming a reagent 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 in fluidic communication with the reagent circuit, a reagent outlet manifold 6, 7 formed through the plate 10, 20 and in fluidic communication with the reagent circuit, a reagent fluid inlet manifold cooling 5 formed through plate 10, 20, a cooling fluid outlet manifold 8, 9 formed through plate 10, 20.

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

[0039] In the example of [Fig.1], assembly 1 also includes 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 anodic 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] Figure 2 schematically represents, in cross-section, an anodic plate 10 and a cathodic plate 20 of the assembly shown in Figure 1. The plates (10, 20) are here bonded together to form a bipolar plate. Alternatively, the plates (10, 20) are placed side-by-side to form a bipolar plate, with the bipolar connection sealed by a gasket.

[0042] Fig. 3 schematically represents, in cross-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 represented with an arrow indicating its direction of flow 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 provided on the cooling face of the anodic plate 10 and / or the cathodic plate 20.

[0046] Each plate 10, 20 has at least one third cavity 53, 54 for receiving a seal, the third cavity 53, 54 being provided on the reactive face of the anodic plate 10 and / or the cathodic 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 PI, P2, P3, P4, P5. The depth is measured in a plane orthogonal to the plane of the plate 10, 20 cutting 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 composing such an assembly 1.

[0051] As can be seen in [Fig.2], the plate 10, 20 has at least one first light 2 formed through the plate 10, 20 and a plurality of fourth cavities 56 provided on the cooling face of the plate 10, 20.

[0052] Each fourth cavity 56 opens at one end into the reagent inlet collector 3, 4 or the reagent outlet collector 6, 7 and at the other 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 cutting 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 PI, 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 example of an embodiment of the anodic plate 10 or respectively of the For a cathode ray tube 20, the average cavity depth is 0.35 mm and the maximum thickness of the tube 10, 20 is 0.8 mm. In this example, the ratio is 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 plate 10, 20 of 1.15 mm. The ratio is equal to 0.3043.

[0061] Figure 4 represents a fuel cell 100 comprising an assembly 1 as described above. As shown in Figure 4, the distribution plate 11 comprises an external face intended to face an interface plate 17 with a cooling fluid inlet and outlet piping and with a reactive fluid inlet and outlet piping, 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 pile 100 comprises a first electric current collector plate, a second electric current collector plate and an interface plate 17 with an inlet and outlet piping for the cooling fluid and the reactive fluid.

Claims

Demands

1. An assembly (1) comprising a stack of a plurality of proton exchange membrane fuel cell (30) cells, each cell (30) of the plurality comprising an anodic plate (10) and a cathodic plate (20) sandwiching a Membrane Electrode Assembly (16), each plate (10, 20) comprising a reactive face and a cooling face opposite to each other, the reactive face of each plate (10, 20) being designed to face the Membrane Electrode Assembly (16) and being provided with ridges and recesses forming a reactive circuit for the circulation of a reactive fluid (60), the reactive circuit comprising a plurality of first cavities (51, 52) formed on the reactive face of the plate (10, 20), the cooling face of the cathodic plate (20) of at least one of the cells (30) being designed to face the cooling face of the anodic plate (10) of another of the cells (30),by defining reliefs and hollows between them to form a cooling circuit (15) for the circulation of a cooling fluid, the cooling circuit (15) comprising a plurality of second cavities (55) formed on the cooling face of the anodic plate (10) and / or the cathodic plate (20), each plate (10, 20) comprising at least one third cavity (53, 54) for receiving a seal, the third cavity (53, 54) being formed on the reactive face of the anodic plate (10) and / or the cathodic 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 such that the average depths of all the cavities should be 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 fluidic communication with the reagent circuit, a reagent outlet manifold (6, 7) formed through the plate (10, 20) and being in fluidic communication with the reagent circuit, a coolant inlet manifold (5) formed through the plate (10, 20), a coolant 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) provided on the cooling face of the plate (10, 20), each fourth cavity (56) opening at one end into the reagent inlet collector (3, 4) or the reagent outlet collector (6, 7) and at the other 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 (PI, 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 any 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 sealing plate (21) comprising an electric current collection face intended to face a first electric current collection plate and a sealing face fixed to the cooling face of one of the plates (10, 20) of the last cell (30), the sealing face being in particular glued or welded to said cooling face.

5. Assembly (1) according to the preceding claim, comprising a distribution plate (11) including an external face intended to face an interface plate (17) with a cooling fluid inlet and outlet piping and with a reactive fluid inlet and outlet piping, the distribution plate (11) including 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. Together (1) according to any 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 that is devoid of cavities (51, 52, 53, 54, 55, 56) on its reactive face and on its cooling face.

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

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

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

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