Polar component for an electrochemical cell of a fuel cell, and associated electrochemical cell, fuel cell and electric vehicle

Abstract

The invention relates to a polar plate (7) for an electrochemical cell of a fuel cell, comprising a central portion (73) that forms a flow field (73.1) for a functional fluid, and a peripheral portion (74), which surrounds the central portion and which comprises two distribution holes (74.1, 74.2) arranged on either side of the central portion in order to feed and discharge the functional fluid, respectively, with respect to the flow field. For each distribution hole, the peripheral portion comprises a flow rim (74.1A, 74.2A), which partly defines the distribution hole on a portion of the distribution hole, facing the central portion, and a plurality of fluid passage openings (74.7, 74.8) which are all located between the flow rim of the distribution hole and the central portion, and each elongate in a main direction that is parallel to the flow rim.

Description

[0001] DESCRIPTION

[0002] TITLE: Polar component for an electrochemical cell of a fuel cell, and associated electrochemical cell, fuel cell, and electric vehicle

[0003] The present invention relates to a polar plate for an electrochemical cell of a fuel cell. It also relates to a polar component for an electrochemical cell of a fuel cell, comprising such a polar plate. It also relates to an electrochemical cell comprising such a polar component. It further relates to a fuel cell comprising such cells, as well as to a vehicle comprising such a fuel cell.

[0004] A fuel cell is a device for generating electricity by electrochemical reaction between two reactive fluids, namely a fuel, typically hydrogen, and an oxidizer, typically oxygen contained in the air. We are interested here in fuel cells comprising several electrochemical cells, each of which constitutes an electrochemical generator and which are stacked against each other in a stacking direction. Schematically, each electrochemical cell comprises two polar components, namely an anode component and a cathode component, which extend perpendicular to the stacking axis and between which an electrolyte is inserted. Cooling of the fuel cell is often ensured by a coolant which flows between the electrochemical cells.

[0005] Conventionally, a polar component comprises a polar plate which is made up of a metal plate comprising, for each of the different functional fluids, namely the reactive fluids and the cooling fluid, two distribution orifices allowing respectively the supply and the evacuation of the functional fluid for the cell concerned. These orifices are generally located in a peripheral part of the plate, which surrounds a central part of the latter where the electrochemical reaction between the reactive fluids takes place. The flow conditions of the functional fluids between the orifices and this central part impact the efficiency of the fuel cell.

[0006] The aim of the invention is to provide a polar component for an electrochemical cell of a fuel cell, which improves the performance of the flow of functional fluids within the fuel cell, while taking into account the structural integrity constraints of the polar plate. To this end, the subject of the invention is a polar component for an electrochemical cell of a fuel cell, the polar component comprising:

[0007] - a polar plate, extending along a plate plane and having first and second faces which are opposite each other along an axis perpendicular to the plate plane, the plate comprising:

[0008] - a central part which, on the first face, forms a flow field for a functional fluid, and

[0009] - a peripheral part, which surrounds the central part and which includes:

[0010] - two distribution orifices which each pass through the plate, connecting the first and second faces to each other and which are arranged on either side of the central part to respectively supply and evacuate the functional fluid with respect to the flow field,

[0011] - for each distribution orifice, a flow rim which partially delimits the distribution orifice on a portion of the distribution orifice, facing the central part, and

[0012] - for each distribution orifice, a plurality of fluid passage holes, each of which passes through the plate, connecting the first and second faces to each other, all being located between the flow rim of the distribution orifice and the central part, and each of which is elongated in a main direction which is substantially parallel to the flow rim of the distribution orifice,

[0013] - for each distribution orifice of the polar plate, a first seal, which is attached projecting from the first face of the polar plate and which surrounds the distribution orifice in a sealed manner, a portion of this first seal being arranged between the distribution orifice and said plurality of fluid passage holes and extending along the flow rim of the distribution orifice, and

[0014] - for each distribution orifice of the polar plate, spacer pads, which are attached projectingly on the first face of the polar plate and which are arranged between said plurality of fluid passage holes and the flow field, being spaced apart from each other parallel to the main direction of said plurality of passage holes, each of the spacer pads associated with each distribution orifice of the polar plate extending longitudinally in a flow direction, said flow direction being preferably perpendicular to the main direction of said plurality of fluid passage holes associated with the distribution orifice, the spacer pads associated with each distribution orifice of the polar plate being aligned with each other parallel to the main direction of said plurality of fluid passage holes associated with the distribution orifice,by forming flow channels therebetween, and wherein each of said plurality of fluid passage holes is substantially aligned and centered on at least one of the flow channels along the flow direction, respectively.,

[0015] Thanks to the invention, the fluidic performances of an electrochemical cell comprising a component according to the invention are improved. Indeed, thanks to their elongated shape, the fluidic passage holes, through which the functional fluids flow between each of the distribution orifices and the flow field, provide a substantial flow section, in particular increased compared to holes with a circular profile. The elongated shape of the fluidic passage holes also makes it possible to limit the pressure losses at their level, while contributing to good homogeneity of the distribution of the functional fluids. Furthermore, the elongated shape of the fluidic passage holes makes it possible to limit the loss of rigidity of the pole plate, "despite" the increase in the flow section.Furthermore, since the main direction in which the fluid passage holes are elongated is parallel to the flow edge of the corresponding distribution orifice, the size associated with the presence of these fluid passage holes is optimized, in the sense that, perpendicular to the main direction, this size is limited and therefore does not reduce the extent of the flow field. More generally, the elongated shape and the arrangement of the fluid passage holes prove to be particularly advantageous for optimizing both the flow conditions of the functional fluids between each distribution orifice and the flow field and the structural constraints of the polar plate according to the invention. Thanks to the spacer pads, the invention also allows the flow of the fluid while controlling the pressure losses, more particularly by minimizing them.

[0016] According to additional advantageous aspects of the invention, the polar plate has one or more of the following characteristics, taken individually or in all technically possible combinations: the flow edges of the two distribution orifices are parallel to each other and are each inclined relative to long sides and short sides of a rectangular peripheral contour of the polar plate, each of the fluid passage holes associated with the distribution orifice is respectively aligned and centered on only one of the flow channels, each of the holes of said plurality of fluid passage holes associated with each distribution orifice has a main dimension along the main direction and a secondary dimension along a direction perpendicular to the main direction in the plate plane, the main dimension being greater than the secondary dimension by at least 10%, advantageously 50%,preferably 100%, of the secondary dimension, all the holes of the plurality of fluid passage holes associated with each distribution orifice are aligned with each other in their main direction, forming a single row between the flow rim of the distribution orifice and the central part, each of the holes of the plurality of fluid passage holes associated with each distribution orifice has a profile which is either oblong, or elliptical, or oval, or of essentially rectangular shape with rounded corners, or of rectangular shape, the holes of the plurality of fluid passage holes respectively associated with the two distribution orifices have respective profiles which are identical to each other, the spacer pads associated with each distribution orifice of the polar plate are made of material between them, forming a mat which is attached to the first face of the polar plate,the spacer pads associated with each distribution orifice of the polar plate are separate from each other on the first face of the first polar plate.,

[0017] The invention also relates to an electrochemical cell for a fuel cell, comprising:

[0018] - a polar component, which conforms to the above, and whose polar plate is a first polar plate,

[0019] - a second polar plate, which is applied against the first polar plate along the axis, the respective first faces of the first and second polar plates being turned towards each other,

[0020] - a membrane-electrode assembly, which is interposed, along the axis, between the respective first faces of the first and second polar plates, and

[0021] - for each distribution orifice of the first polar plate, a second seal, which is attached projecting from the first face of the second polar plate and a portion of which is arranged opposite, along the axis, the spacer pads so as to axially pinch the membrane-electrode assembly between the second seal and the spacer pads.

[0022] According to an additional advantageous aspect of the invention, the electrochemical cell has the characteristic that the second polar plate belongs to a second polar component according to the above. The invention further relates to a fuel cell comprising electrochemical cells, each of which is according to the above and which are stacked against each other along the axis.

[0023] The invention further relates to a vehicle comprising a fuel cell in accordance with the above.

[0024] The invention will appear more clearly on reading the description which follows, given solely by way of non-limiting example, and made with reference to the drawings in which:

[0025] - [Fig 1] Figure 1 is a schematic perspective view of a fuel cell according to the invention;

[0026] - [Fig 2] Figure 2 is an elevation view of a first polar component, in accordance with the invention, belonging to the fuel cell of Figure 1;

[0027] - [Fig 3] Figure 3 is a larger scale view of the detail in box III of Figure 2;

[0028] - [Fig 4] Figure 4 includes inserts AA and BB which are sections, according to the respective cutting lines IVA-IVA and IVB-IVB of Figure 3, of the first polar component;

[0029] - [Fig 5] Figure 5 is an elevational view of a second polar component, in accordance with the invention, belonging to the fuel cell of Figure 1; and

[0030] - [Fig 6] Figure 6 includes inserts AA and BB, which are sections respectively similar to inserts AA and BB of Figure 4 but of an electrochemical cell combining the first and second polar components.

[0031] Figure 1 shows a fuel cell 1. The fuel cell 1 is for example intended to be installed in a vehicle and to produce, from reactive fluids, electricity supplying, possibly via a battery, an electric motor of this vehicle, ensuring the propulsion of the vehicle, in particular on the ground.

[0032] The fuel cell 1 comprises a stack 3 of electrochemical cells 2, in which the electrochemical cells 2 are arranged against each other along a stacking axis X. The stack of electrochemical cells 2 is held between two end plates 4 of the fuel cell 1, which in particular make it possible to keep the stack 3 of electrochemical cells 2 compressed, i.e. clamped, along the stacking axis X, and to supply this stack with reactive fluids.

[0033] According to a preferred example which will be relied upon subsequently, the fuel reactive fluid consists of hydrogen in gaseous form and the oxidant reactive fluid consists of oxygen in gaseous form, it being noted that, in practice, the fuel cell 1 is not supplied with pure oxygen, but with air, or even with a gaseous mixture comprising oxygen, for example a mixture of oxygen and nitrogen, a mixture which may be in a ratio between oxygen and nitrogen which is similar to that of air or in a different ratio. Here, the terms “oxygen” and “dioxygen” are undifferentiated; similarly, the terms “hydrogen” and “dihydrogen” are undifferentiated. For the sake of simplicity, the terms “oxygen” and “dioxygen” will also cover air or any gaseous mixture containing oxygen in a significant proportion.

[0034] As visible in Figure 6, each electrochemical cell 2 comprises a membrane-electrode assembly 5, as well as two polar plates arranged on either side, along the stacking axis X, of the membrane-electrode assembly 5, namely an anodic plate 6 and a cathodic plate 7.

[0035] Each cathode polar plate 7, shown in isolation in Figures 2 to 4, extends along a plate plane P7 and has a first face 71 and a second face 72, opposite each other along an axis perpendicular to the plate plane P7, this axis being, in the assembled state of the stack 3, coincident with the stack axis X and being called “axis X” hereinafter for convenience.

[0036] Each anode polar plate 6, shown in isolation in FIG. 5, extends along a plate plane P6 and has a first face 61 and a second face 62, opposite each other along an axis perpendicular to the plate plane P6, this axis being, in the assembled state of the stack 3, coincident with the stack axis X and being called “axis X” hereinafter for convenience.

[0037] In the assembled state of the stack 3, the face 61 of the anode plate 6 and the face 71 of the cathode plate 7 of each electrochemical cell 2 are turned towards each other and are applied axially against each other, with the membrane-cathode assembly 5 intercalated. As detailed below, for each electrochemical cell 2, the anode plate 6 allows hydrogen to flow into the electrochemical cell, more precisely between its face 61 and the membrane-cathode assembly 5, while the cathode plate 7 allows oxygen to flow into this electrochemical cell, more precisely between its face 71 and the membrane-cathode assembly 5.For each pair of two electrochemical cells 2 immediately adjacent to each other, the anode plate 6 of one of the two electrochemical cells 2 and the cathode plate 7 of the other of the two electrochemical cells are arranged directly against each other along the stacking axis X and form, in the assembled state of the stack 3, an assembly commonly called a “bipolar plate”. The anode 6 and cathode 7 plates of each bipolar plate form between them free passages for the circulation of a cooling fluid, which are separated from the flows of hydrogen and oxygen within the electrochemical cells 2.The coolant does not play any direct role in the electrochemical reactions occurring in the electrochemical cells 2, but the circulation of this coolant makes it possible to control the temperature of the electrochemical cells 2, therefore the temperature of the electrochemical reaction and thereby the operating conditions of the electrochemical reaction. The coolant, hydrogen and oxygen correspond to three “functional fluids” for the electrochemical cells 2.

[0038] Before describing the polar plates 6 and 7 in more detail, it will be noted that, as schematically illustrated in FIG. 1, the fuel cell 1 comprises a hydrogen inlet 11 supplying hydrogen to the anode plates 6 and a hydrogen outlet 12 discharging the hydrogen from the anode plates 6. The fuel cell 1 also comprises an oxygen inlet 13 supplying oxygen to the cathode plates 7 and an oxygen outlet 14 discharging the oxygen from the cathode plates 7. The fuel cell 1 also comprises a cooling fluid inlet 15 supplying cooling fluid to the bipolar plates and a cooling fluid outlet 16 discharging the cooling fluid from the bipolar plates. In practice, these inlets and outlets are for example arranged in one of the two aforementioned terminal plates 4 and are themselves connected to hydrogen, oxygen and cooling fluid supply circuits.

[0039] Also before describing the polar plates 6 and 7 in more detail, structural and functional characteristics of the membrane-electrode assembly 5 of each electrochemical cell 2 are described in more detail below, it being emphasized that the specificities of these characteristics are not limiting. Thus, in a preferred embodiment, not shown in detail in the figures, the membrane-electrode assembly 5 of each electrochemical cell 2 comprises a first and a second gas diffusion layer, not shown, which are arranged on either side, along the stacking axis X, of a proton exchange membrane of the membrane-electrode assembly 5, the two opposite faces of which are respectively covered by, or in contact with, an anodic catalytic layer and a cathodic catalytic layer.In the assembled state of the fuel cell 1, each electrochemical cell 2 thus comprises, successively along the stacking axis X, the anode plate 6, the first gas diffusion layer, the anode catalytic layer, the proton exchange membrane, the cathode catalytic layer, the second gas diffusion layer, and the cathode plate 7. For each electrochemical cell 2, the first gas diffusion layer partly covers the face 61 of the anode plate 6 and allows the transport of hydrogen from this face 61 to the anode catalytic layer. Similarly, the second gas diffusion layer partly covers the face 71 of the cathode plate 7 and allows the transport of oxygen from this face 71 to the cathode catalytic layer. In practice, the gas diffusion layers and are formed from a porous material such as a carbon fiber fabric or porous carbon paper.For each electrochemical cell 2, the proton exchange membrane allows hydrogen ions, or protons, to be conducted from the anodic catalytic layer to the cathodic catalytic layer, while preventing the flow of electrons. The proton exchange membrane is, for example, made of a perfluorinated sulfurized polymer material, such as the material known under the trade name “Nation”. The proton exchange membrane also allows the flow of water in liquid form, for the purpose of removing the water produced at the cathodic catalytic layer from the electrochemical cell 2. Within each electrochemical cell 2, when the fuel cell 1 is in operation, an oxidation reaction occurs at the anodic catalytic layer and consists of catalytically splitting the hydrogen provided by the first gas diffusion layer into protons and electrons.The protons thus produced pass through the proton exchange membrane until they reach the cathodic catalytic layer, while the electrons thus produced are captured by the anode plate 6 and then conducted towards the cathodic plate 7 of the bipolar plate to which the anode plate 6 of the electrochemical cell 2 considered belongs. At the same time, a reduction reaction occurs at the cathodic catalytic layer and consists of reacting the oxygen supplied by the second gas diffusion layer with the protons passing through the proton exchange membrane, as well as with electrons supplied by the plate.

[0040] In practice, the membrane-electrode assembly 5 of each electrochemical cell 2 comprises a peripheral part forming a holding frame 51 which supports the aforementioned gas diffusion layers and the proton exchange membrane. This holding frame 51 is for example formed of two films superimposed and glued to each other, for example PET or PEN films themselves in the form of a frame to delimit an internal window whose contour is slightly smaller than the contour of the proton exchange membrane, the contour of the latter being trapped, along the contour of the internal window, between the two films of the holding frame 51.

[0041] In the embodiment considered in the figures, the anode 6 and cathode 7 plates and the support frames 51 have respective peripheral contours, which are rectangular and substantially identical to each other.

[0042] We will now describe in more detail the polar plates 6 and 7 of each electrochemical cell 2, starting with the cathode plate 7.

[0043] As clearly visible in Figure 2, the cathode plate 7 comprises both a central part 73, which, along the axis X, extends from one to the other of the faces 71 and 72, and a peripheral part 74, which also extends axially from one to the other of the faces 71 and 72 and which, around the axis X, surrounds the central part 73.

[0044] The peripheral portion 74 is provided with six distribution orifices 74.1, 74.2, 74.3, 74.4, 74.5 and 74.6 which each pass through the cathode plate 7 from one side to the other, connecting the faces 71 and 72 to each other. In other words, the distribution orifices 74.1, 74.2, 74.3, 74.4, 74.5 and 74.6 are each through orifices. In practice, the distribution orifices 74.1, 74.2, 74.3, 74.4, 74.5 and 74.6 here pass through the cathode plate 7 along the X axis.

[0045] The distribution orifices 74.1 and 74.2 allow oxygen to flow into the corresponding electrochemical cell 2. For this purpose, the distribution orifice 74.1 is, upstream of the cathode plate 7, supplied with oxygen by the oxygen inlet 13 while the distribution orifice 74.2 is, downstream of the cathode plate 7, connected to the oxygen outlet 14. In addition, the distribution orifices 74.1 and 74.2 are arranged on either side of the central part 73 of the cathode plate 7. In other words, transversely to the X axis, the distribution orifice 74.1, the central part 73 and the distribution orifice 74.2 follow one another. Inside the electrochemical cell 2, the oxygen flows from the orifice 74.1 to the orifice 74.2 via the central part 73 of the cathode plate 7, in particular via a flow field 73.1 formed by this central part 73 on the face 71 of the cathode plate 7, as indicated by the wavy arrows drawn in FIG. 2. In other words, the distribution orifice 74.1 participates in bringing the oxygen from the peripheral part 74 to the flow field 73.1 and can therefore be described as a supply orifice, while the distribution orifice 74.2 participates in evacuating the oxygen from the flow field 73.1 to the peripheral part 74 and can therefore be described as an evacuation orifice.

[0046] By "flow field" we preferably mean any element making it possible to form a fluid path, that is to say a device for guiding and channeling the fluid, so as to bring it from a first point to a second point, in this case between the distribution orifices.

[0047] In the embodiment considered in the figures, the distribution orifices 74.1 and 74.2 are arranged along a first of the two diagonals of the rectangular peripheral contour of the cathode plate 7. This makes it possible in particular to maximize the extent of the flow of oxygen in the flow field 73.1.

[0048] In all cases, each of the distribution orifices 74.1 and 74.2 is partly delimited, on its portion facing the central part 73, by a flow rim 74.1 A, respectively 74.2A which is here advantageously rectilinear for reasons which will appear later. Taking into account the explanations given just above, it is understood that the flow rim 74.1 A can be described as a supply rim and the flow rim 74.2A can be described as a discharge rim. In the example envisaged here, the flow rims 74.1 A and 74.2A are parallel to each other and are each inclined relative to the long sides and short sides of the rectangular peripheral contour of the cathode plate 7. Of course, other arrangements of the flow rims 74.1 A and 74.2A are conceivable.

[0049] According to a preferred aspect, which is implemented in the example envisaged in the figures, the flow field 73.1 includes three successive adjacent zones, namely a homogenization zone 73.2, an active zone 73.3 and a homogenization zone 73.4. The homogenization zone 73.2 is arranged between the flow rim 74.1 A and the active zone 73.3, participating in fluidically connecting the flow rim 74.1 A and the active zone 73.3 and homogenizing the flow of oxygen flowing therein towards the active zone 73.3, by means of the distribution of this flow of oxygen over the entire transverse extent of the active zone. Similarly, the homogenization zone 73.4 is disposed between the flow rim 74.2A and the active zone 73.3, participating in fluidly connecting the flow rim 74.2A and the active zone 73.3 and homogenizing the flow of oxygen flowing therein from the active zone 73.3.

[0050] The flow edges 74.1 A and 74.2A are each inclined relative to the long sides and short sides of the rectangular peripheral contour of the cathode plate 7, the edges 74.1 A and 74.2A are not perpendicular to a longitudinal flow direction of the fluid between the homogenization zones 73.2 and 73.4. Thus, the homogenization zones 73.2 and 73.4 are triangular in shape, ensuring good distribution of the fluid over an entire width of the homogenization zones 73.2 and 73.4, parallel to the short sides. The inclination of the edges 74.1 A and 74.2A relative to the long sides and short sides of the rectangular peripheral contour of the cathode plate 7 therefore makes it possible to improve the distribution of the fluid while optimizing the footprint of the homogenization zones 73.2 and 73.4 on the cathode plate 7.

[0051] The active zone 73.3 fluidly connects the homogenization zones 73.2 and 73.4 to each other and for this purpose includes channels, in which oxygen flows from the homogenization zone 73.2 to the homogenization zone 73.4 and which, in the assembled state of the corresponding electrochemical cell 2, are covered by the membrane-electrode assembly 5 to supply oxygen to the redox reactions occurring in the latter, as detailed above. The channels of the active zone 73.3 may be rectilinear, as illustrated, or else have undulations. As illustrated, the channels of the active zone extend longitudinally over the central portion 73 of the cathode plate 7, along the length of the plate, when the latter preferably has a rectangular peripheral contour. In particular, the active zone 73.3 has substantially the same dimensions as the aforementioned window which delimits the holding frame 51 and it is generally expected that the corresponding gas diffusion layer completely covers at least the active zone 73.3.

[0052] In all cases, as clearly visible in Figures 2 to 4, each of the distribution orifices 74.1 and 74.2 is associated with a plurality of fluid passage holes 74.7, respectively 74.8, which are delimited in the peripheral part 74 of the cathode plate 7 and which each pass through the cathode plate 7 by connecting the faces 71 and 72 to each other. All the fluid passage holes 74.4 are located between the central part 73 and the flow rim 74.1A while all the fluid passage holes 74.8 are located between the central part 73 and the flow rim 74.2A. As explained in more detail below, the fluid passage holes 74.7 participate in fluidly connecting the flow rim 74.1 A and the flow field 73.1 to each other, allowing the flow of oxygen flowing from the distribution orifice 74.1 to the flow field 73.1 to pass through the cathode plate 7, passing from its face 72 to its face 71; similarly, the fluid passage holes 74.8 participate in fluidly connecting the flow rim 74.2A and the flow field 73.1 to each other, by allowing the flow of oxygen flowing from the flow field 73.1 to the distribution orifice 74.1 to pass through the cathode plate 7, passing from its face 71 to its face 72. In practice, the plurality of fluid passage holes 74.7 includes at least three fluid passage holes 74.7, for example five as in the example illustrated in the figures, or even more; in any case, the fluid passage holes 74.7 of this plurality are all provided, in use, to pass therethrough respective non-zero fractions of the entire oxygen flow flowing from the distribution orifice 74.1 to the flow field 73.1. Similarly, the plurality of fluid passage holes 74.8 includes at least three fluid passage holes 74.8, for example five as in the example illustrated in the figures, or even more; in all cases, the fluid passage holes 74.8 of this plurality are all provided, in service, to pass through them respective non-zero fractions of the entire flow of oxygen flowing from the flow field 73.1 to the distribution orifice 74.2.

[0053] As clearly visible in Figures 2 to 4, each of the fluid passage holes 74.7 and 74.8 has an elongated shape, it being understood that this elongated shape is considered in the plate plane P7, that is to say in orthogonal projection on this plate plane P7. Indeed, in practice, each of the fluid passage holes 74.7 and 74.8 has a dimension along the X axis, which is much smaller than its two other orthonormal dimensions. The elongated shape of each of the fluid passage holes 74.7 and 74.8 extends lengthwise in the plate plane P7 in a main direction, denoted D1 for the fluid passage holes 74.7 in FIG. 3. Each of the fluid passage holes 74.7 and 74.8 thus has a main dimension in the main direction, which is denoted L1 for the fluid passage holes 74.7 in FIG. 3, and a secondary dimension in a direction, denoted D2 for the fluid passage holes 74.7 in Figure 3, which is perpendicular to the main direction in the plate plane P7, this secondary dimension being noted L2 for the fluid passage holes 74.7 in Figure 3. With regard to the aforementioned elongated shape, the main dimension L1 is strictly greater than the secondary dimension L2. In addition, the main direction D1 along which the fluid passage holes 74.7 are elongated is parallel to the associated flow rim 74.1 A. Similarly, the main direction along which the fluid passage holes 74.8 are elongated is parallel to the associated flow rim 74.1 A.

[0054] Thanks to their elongated shape, the fluid passage holes 74.7 and 74.8 provide a substantial flow section for the aforementioned oxygen flow and thus make it possible to limit the pressure losses at their level, while contributing to good homogeneity of the distribution of the oxygen flow and limiting the loss of rigidity and damage to the structural integrity of the cathode plate 7. In addition, the size linked to the presence of these fluid passage holes 74.7 and 74.8 is limited in the direction perpendicular to their main direction, which maximizes the extent of the flow field 73.1.

[0055] Advantageously, the fluid passage holes 74.7 are aligned with each other along their main direction D1, forming a single row between the flow rim 74.1 A and the central part 73. This single row thus runs along the flow rim 74.1 A. Similarly, the fluid passage holes 74.8 are aligned with each other along their main direction, forming a single row between the flow rim 74.2A and the central part 73. This arrangement makes it possible to minimize the pressure losses at the fluid passage holes 74.7 and 74.8 and to minimize the size of these fluid passage holes.

[0056] According to an advantageous dimensioning which improves the fluidic performances of the fluidic passage holes 74.7 and 74.8, the main dimension L1 is greater than the secondary dimension L2 by at least 10%, preferably 50%, even more preferably 100%, of the secondary dimension L2.

[0057] According to another advantageous aspect, combinable with all of the above, each of the fluid passage holes 74.7 and 74.8 has an oblong, elliptical, oval, essentially rectangular with rounded corners, or rectangular profile, it being understood that this profile is considered in the plate plane P7, that is to say in orthogonal projection on this plate plane P7. These various profile geometries induce specific fluid performances. For both practical and fluid balancing reasons, the fluid passage holes 74.7 and the fluid passage holes 74.8 advantageously have respective profiles which are identical to each other.

[0058] As indicated above, the peripheral part 74 is provided, in addition to the distribution orifices 74.1 and 74.2 which, as detailed so far, allow the oxygen to flow into the corresponding electrochemical cell 2, with distribution orifices 74.3 and 74.4. These distribution orifices 74.3 and 74.4 are respectively connected to the hydrogen inlet 11 upstream of the electrochemical cell 2 and to the hydrogen outlet 12 downstream of the electrochemical cell 2 and allow the hydrogen to pass through the cathode plate 7 without the latter being able to reach the flow field 73.1. In the embodiment considered in the figures, the distribution orifices 74.3 and 74.4 are arranged along the second of the two diagonals of the rectangular peripheral contour of the cathode plate 7. The specificities of these distribution orifices 74.3 and 74.4 are not limiting.

[0059] Also as indicated above, the peripheral part 74 is provided, in addition to the distribution orifices 74.1, 74.2, 74.3 and 74.4 detailed so far, with the distribution orifices 74.5 and 74.6. The distribution orifices 74.5 and 74.6 allow the cooling fluid to flow into the bipolar plate to which the cathode plate 7 belongs. For this purpose, the distribution orifices 74.5 and 74.6 are respectively connected to the cooling fluid inlet 15 upstream of the bipolar plate and to the cooling fluid outlet 16 downstream of the bipolar plate. In operation, the cooling fluid is designed to, in the bipolar plate, go from the distribution orifice 74.5 to the distribution orifice 74.6, flowing exclusively on the face 72 of the cathode plate. The corresponding specifications are not limiting.

[0060] Before describing the anode plate 6 in more detail, we are interested in what is reported on the cathode plate 7 and which, together with the latter, forms what can be called a polar component, in this case a cathode component 7' of the corresponding electrochemical cell 2.

[0061] As clearly visible in Figure 2, each electrochemical cell 2 thus comprises a peripheral seal 75, which is carried by the peripheral part 74 of the cathode plate 7 and which is attached projecting from the face 71 of this cathode plate, along the peripheral edges of the cathode plate so as to form a closed loop. Also on the face 71, the peripheral seal 75 completely surrounds each of the six distribution orifices 74.1, 74.2, 74.3, 74.4, 74.5 and 74.6 in a sealed manner. Thus, in the assembled state of the electrochemical cell 2, the peripheral seal 75 fluidly isolates, on the face 71 of the cathode plate 7, the respective outlets of the distribution orifices 74.1, 74.2, 74.3, 74.4, 74.5 and 74.6 both from each other and from the rest of this face 71, in particular the flow field 73.1.The peripheral seal 75 is sealed against the aforementioned functional fluids and prevents them from mixing with each other and escaping outside the corresponding electrochemical cell 2. The peripheral seal 75 is electrically insulating and is for example made of an elastomer material.

[0062] As clearly visible in Figures 2 to 4, the peripheral seal 75 includes a portion

[0063] 75.1 which is arranged between the distribution orifice 74.1 and the fluid passage holes 74.7. This portion 75.1 thus fluidly isolates, on the face 71 of the cathode plate 7, the outlet of the distribution orifice 74.1 from the outlets of the fluid passage holes 74.7. The portion 75.1 of the peripheral seal 75 extends along the flow rim 74.1A, here in a rectilinear manner. Similarly, the peripheral seal 75 includes a portion 75.2, which is arranged between the distribution orifice 74.2 and the fluid passage holes 74.8 and which extends along the flow rim 74.2A, here in a rectilinear manner.

[0064] As clearly visible in Figure 2, the peripheral seal 75 also includes a portion 75.3, which is arranged between the distribution orifice 74.3 and the flow field.

[0065] 73.1 and which therefore participates in the fluidic isolation, on the face 71 of the cathode plate 7, between the outlet of the distribution orifice 74.3 and the flow field 73.1. For reasons which will appear later, this portion 75.3 here extends lengthwise in a rectilinear manner. Similarly, the peripheral seal 75 includes a portion 75.4, which is arranged between the distribution orifice 74.4 and the flow field 73.1 and which here extends lengthwise in a rectilinear manner.

[0066] Also as clearly visible in Figure 2, each electrochemical cell 2 further comprises spacer pads 76.1 associated with the distribution orifice 74.1 and spacer pads 76.2 associated with the distribution orifice 74.2. These spacer pads 76.1 and 76.2 are attached projecting from the face 71 of the cathode plate 7 and are designed to contribute to the mechanical stability of the electrochemical cell 2, and thereby to the reliability of the fuel cell 1, by maintaining the spacing along the X axis between the face 71 of the cathode plate and the rest of the electrochemical cell 2, more precisely the membrane-electrode assembly 5. In the assembled state of the electrochemical cell 2 and the stack 3, the spacer pads 76.1 and 76.2 participate in the transmission of mechanical stresses between the cathode plate 7 and the rest of the electrochemical cell 2, in particular by avoiding untimely deformations of the cathode plate 7 within the stack 3. These spacer pads therefore act as mechanical support pads. In the example illustrated in the figures, the spacer pads 76.1 are ten in number and the spacer pads 76.2 are also ten in number, this number not being limiting. The spacer pads 76.1 and 76.2 are electrically insulating and are for example made of an elastomeric material.

[0067] As clearly visible in Figures 2 to 4, the spacer pads 76.1 are arranged, on the face 71 of the cathode plate 7, between the fluid passage holes

[0068] 74.7 and the flow field 73.1. In addition, the spacer pads 76.1 are spaced apart from each other parallel to the main direction D1 of the fluid passage holes

[0069] 74.7 and thus form between them flow passages 77.1 through which, in operation, oxygen flows onto the face 71 of the cathode plate 7 from the outlet of the fluid passage holes 74.7 to the flow field 73.1, as indicated schematically by the wavy arrows in Figure 3. Similarly, the spacer pads 76.2 are arranged, on the face 71 of the cathode plate 7, between the fluid passage holes

[0070] 74.8 and the flow field 73.1, being spaced apart from each other parallel to the main direction of the fluid passage holes 74.8 and thus forming between them flow passages 77.2 through which, in service, the oxygen flows onto the face 71 from the flow field 73.1 at the outlet of the fluid passage holes 74.8. The flow channels 77.1 and 77.2 thus allow the flow of oxygen onto the face 71 of the cathode plate 7 while controlling the pressure losses.

[0071] According to an advantageous arrangement improving the flow of oxygen in the flow channels 77.1, each of the spacer pads 76.1 extends longitudinally in a flow direction, which is preferably perpendicular to the main direction D1 of the fluid passage holes 74.7 and therefore parallel to the secondary direction D2 of these fluid passage holes 74.7. Thus, each of the spacer pads 76.1 has an elongated shape, for example with a rectangular profile as here. Similarly, each of the spacer pads 76.2 extends longitudinally in a flow direction, which is preferably perpendicular to the main direction of the fluid passage holes 74.8.

[0072] In particular for the purpose of optimizing the mechanical and fluidic performances, the spacer pads 76.1 are advantageously aligned with each other parallel to the main direction D1 of the fluid passage holes 74.7, here forming a single rectilinear row and so that the flow channels 77.1 are here identical to each other. Each of the fluid passage holes 74.7 is then advantageously aligned and centered on at least one, or even only one as here, of the flow channels 77.1 according to the aforementioned flow direction, respectively. This minimizes the pressure losses on the face 71 of the cathode plate 7 between the outlet of the fluid passage holes 74.7 and the flow channels 77.1. Similarly, the spacer pads 76.2 are advantageously aligned with each other parallel to the main direction of the fluid passage holes 74.8 and each of the fluid passage holes 74.8 is then advantageously aligned and centered on at least one, or even just one as here, of the flow channels 77.2 according to the corresponding flow direction, respectively.

[0073] The cathode component 7' mentioned above comprises the cathode plate 7, the peripheral seal 75 and the spacer pads 76.1 and 76.2. This cathode component 7' can thus be described as a "sealed cathode plate".

[0074] Before considering the anode plate 6, it will be noted that the cathode plate 7 described in detail above is preferably a shaped sheet, in particular stamped, made of metal, in particular stainless steel. This being the case, other embodiments are conceivable, the cathode plate 7 being able to be made of other materials, in particular for example graphite, and / or being able to be shaped other than by stamping, for example by machining, by chemical etching, by electroerosion, or by additive manufacturing. Whatever the method of manufacturing the cathode plate 7, the peripheral seal 75 and the spacer pads 76.1 and 76.2 are attached to the face 71 of the cathode plate 7 by overmolding or by any appropriate assembly method. In the example illustrated in the figures, the spacer pads 76.1 came from the material between them, forming a carpet which is attached in one piece to the face 71 of the cathode plate 7; in this case and, more generally, since the assembly of the spacer pads 76.1 and 76.2 to the cathode plate 7 is independent of the fluid passage holes 74.7 and 74.8, the latter can be produced both before and after the assembly of the spacer pads 76.1 and 76.2, in particular during the manufacture of the cathode plate 7. According to an alternative not shown, the spacer pads 76.1 and 76.2 are overmolded or, more generally, attached to the face 71, without being made of material directly between them, but each being made of material with the peripheral seal 75 by respective ad hoc connecting strands which extend in particular from the portion 75.1 to the spacer pads 76.1 and from the portion 75.2 to the spacer pads 76.2: in in this case, the fluid passage holes 74.7 and 74.8 are advantageously produced by cutting after the assembly of the spacer pads 76.1 and 76.2 to the cathode plate, so that the cutting carried out removes the aforementioned connecting strands, which, on the face 71 of the cathode plate 7, makes the spacer pads 76.1 separate from each other and from the peripheral seal 75 and makes the spacer pads 76.2 separate from each other and from the peripheral seal 75. More generally, the specificities relating to the manufacture of the cathode component 7' are not limiting. We will now look in more detail at the anode plate 6 of the electrochemical cell 2 to which the cathode plate 7 and the cathode component 7' described above belong.

[0075] The anode plate 6 is similar to the cathode plate 7, but in a manner adapted to the anode function of this plate 6. The plate 6 can thus be described in terms similar to those of the cathode plate 7, but adapted to this anode function, in particular by replacing the term “oxygen” with the term “hydrogen” and vice versa. In particular, the anode plate 6 comprises elements and arrangements, which are similar to those of the cathode plate 7 but whose references begin with “6” instead of “7”. Thus, in summary and based on Figures 5 and 6, the anode plate 6 comprises, among other things:

[0076] - central parts 63 and peripheral parts 64, respectively similar to the central part 73 and the peripheral part 74 of the cathode plate 7,

[0077] - a flow field 63.1, similar to the flow field 73.1 of the cathode plate 7,

[0078] - distribution orifices 64.1 and 64.2, respectively similar to the distribution orifices 74.1 and 74.2 of the cathode plate 7 and allowing the hydrogen to flow into the corresponding electrochemical cell 2,

[0079] - flow edges 64.1 A and 64.2A, respectively similar to the flow edges 74.1 A and 74.2A of the cathode plate 7,

[0080] - distribution orifices 64.3 and 64.4, respectively similar to the distribution orifices 74.3 and 74.4 of the cathode plate 7 and allowing oxygen to pass through the anodic plate 6 without the latter being able to reach the flow field 63.1,

[0081] - distribution orifices 64.5 and 64.6, respectively similar to the distribution orifices 74.5 and 74.6 of the cathode plate 7 and allowing the cooling fluid to flow into the bipolar plate to which the anode plate 6 belongs, and

[0082] - fluid passage holes 64.7 and 64.8, respectively similar to the fluid passage holes 74.7 and 74.8 of the cathode plate 7.

[0083] Similarly, an anode component 6' of the electrochemical cell 2 can be described in terms similar to those of the cathode component 7', but adapted to the anode function of this component e', in particular by replacing the term "oxygen" with the term "hydrogen" and vice versa. In particular, the anode component 6' comprises elements and arrangements, which are similar to those of the cathode component 7' but whose references begin with "6" instead of "7". Thus, in summary and based on Figures 5 and 6, the anode component 6' comprises: - the anode plate 6,

[0084] - a peripheral seal 65, which is similar to the peripheral seal 75 of the cathode component 7' and which includes portions 65.1, 65.2, 65.3 and 65.4, respectively similar to the portions 75.1, 75.2, 75.3 and 75.4 of the seal 75, and

[0085] - spacer pads 66.1 and 66.2, which are respectively similar to the spacer pads 76.1 and 76.2 of the cathode component 7' and which delimit between them flow channels 67.1 and 67.2, respectively similar to the flow channels 77.1 and 77.2.

[0086] As illustrated in Figure 6, in the assembled state of the electrochemical cell 2 within the stack 3, the portion 65.3 of the seal 65 is arranged opposite, along the axis X, the spacer pads 76.1 so as to axially pinch, between this portion 65.3 of the seal 65 and these spacer pads 76.1, the membrane-electrode assembly 5, in particular the holding frame 51. Similarly, the portion 65.4 of the seal 65 is arranged opposite, along the axis X, the spacer pads 76.2 so as to axially pinch, between this portion 65.4 of the seal 65 and these spacer pads 76.2, the membrane-electrode assembly 5, in particular the holding frame 51. Similarly, the portion 75.3 of the seal 75 is arranged opposite, along the X axis, the spacer pads 66.1 so as to axially pinch, between this portion 75.3 of the seal 75 and these spacer pads 66.1, the membrane-electrode assembly 5, in particular the holding frame 51.Likewise, the portion 75.4 of the seal 75 is arranged opposite, along the axis X, the spacer pads 66.2 so as to axially pinch, between this portion 75.4 of the seal 75 and these spacer pads 66.2, the membrane-electrode assembly 5, in particular the holding frame 51.

[0087] In the assembled state of the stack 3, the distribution orifices 74.1, 74.2, 74.3, 74.4, 74.5 and 74.6 of the cathode plates 7 are both respectively aligned with each other along the X axis and respectively aligned with the distribution orifices 64.3, 64.4, 64.1, 64.2, 64.5 and 64.6 of the anode plates 6. In the assembled and operating state of the stack 3, the oxygen circulates in the electrochemical cells 2 as indicated by the wavy arrows in FIG. 6: the oxygen feeds the electrochemical cells 2 through the distribution orifices 74.1 and 64.3 and, for each of the electrochemical cells 2, enters them through the flow rim 74.1 A by flowing along the face 72 of the cathode plate 7, before passing onto the face 71 via the fluid passage holes 74.7 from where the oxygen flows to the inlet of the flow field 63.1 via the flow channels 77.1 between the spacer pads 76.1.At the outlet of the flow field, the oxygen flows, via the flow channels 77.2 between the spacer pads 76.2, to the fluid passage holes 74.8 through which the oxygen passes from the face 71 to the face 72 of the cathode plate, before joining the flow rim 74.2A by flowing along the face 72 and reaching the distribution orifice 74.2 to be evacuated from the electrochemical cells via the distribution orifices 74.2 and 64.4. The circulation of hydrogen is similar but via the distribution orifices 64.1, 74.3, 64.2 and 74.4. In a variant not shown, fluid passage holes and, where appropriate, spacer pads, similar to those detailed so far for the flow of reactive fluids, can be implemented for the flow of the coolant.

[0088] Any feature described above for one embodiment or variant is applicable to other embodiments and variants described above, as far as technically possible.

Claims

CLAIMS 1. Polar component (6', 7') for an electrochemical cell (2) of a fuel cell, the polar component (6', 7') comprising: - a polar plate (6, 7), extending along a plate plane (P6, P7) and having first (61, 71) and second (62, 72) faces which are opposite each other along an axis (X) perpendicular to the plate plane, the plate comprising: - a central part (63, 73) which, on the first face, forms a flow field (63.1, 73.1) for a functional fluid, and - a peripheral part (64, 74), which surrounds the central part and which comprises: - two distribution orifices (64.1, 64.2, 74.1, 74.2) which each pass through the plate, connecting the first and second faces to each other and which are arranged on either side of the central part to respectively supply and evacuate the functional fluid with respect to the flow field, - for each distribution orifice, a flow rim (64.1 A, 64.2A, 74.1 A, 74.2A) which partially delimits the distribution orifice on a portion of the distribution orifice, facing the central part, and - for each distribution orifice, a plurality of fluid passage holes (64.7, 64.8, 74.7, 74.8), each of which passes through the plate, connecting the first and second faces to each other, all being located between the flow rim of the distribution orifice and the central part, and each of which is elongated in a main direction (D1) which is substantially parallel to the flow rim of the distribution orifice, - for each distribution orifice (64.1, 64.2, 74.1, 74.2) of the polar plate, a first seal (65, 75), which is attached projectingly on the first face of the polar plate and which surrounds the distribution orifice in a sealed manner, a portion (65.1, 65.2, 75.1, 75.2) of this first seal being arranged between the distribution orifice and said plurality of fluid passage holes (64.7, 64.8, 74.7, 74.8) and extending along the flow rim (64.1 A, 64.2A, 74.1 A, 74.2A) of the distribution orifice, and - for each distribution orifice of the polar plate, spacer pads (66.1, 66.2, 76.1, 76.2), which are attached projectingly on the first face of the polar plate and which are arranged between said plurality of fluid passage holes and the flow field (63.1, 73.1), being spaced apart from each other parallel to the main direction (D1) of said plurality of passage holes, each of spacer pads (66.1, 66.2, 76.1, 76.2) associated with each distribution orifice (64.1, 64.2, 74.1, 74.2) of the polar plate extending longitudinally in a flow direction, said flow direction being preferably perpendicular to the main direction (D1) of said plurality of fluid passage holes (64.7, 64.8, 74.7, 74.8) associated with the distribution orifice, the spacer pads (66.1, 66.2, 76.1, 76.2) associated with each distribution orifice (64.1, 64.2, 74.1, 74.2) of the polar plate being aligned with each other parallel to the main direction (D1) of said plurality of fluid passage holes (64.7, 64.8, 74.7, 74.8) associated with the distribution orifice, forming between them flow channels (67.1, 67.2, 77.1, 77.2), and wherein each of said plurality of fluid passage holes is substantially aligned and centered on at least one of the flow channels along the flow direction, respectively.

2. Polar component (6', 7') according to claim 1, wherein the flow edges (64.1 A, 64.2A, 74.1 A, 74.2A) of the two distribution orifices (64.1, 64.2, 74.1, 74.2) are parallel to each other and are each inclined relative to long sides and short sides of a rectangular peripheral contour of the polar plate (6, 7).

3. Polar component (6', 7') according to any one of claims 1 or 2, wherein each of the fluid passage holes (64.7, 64.8, 74.7, 74.8) associated with the dispensing orifice (64.1, 64.2, 74.1, 74.2) is respectively aligned and centered on only one of the flow channels (67.1, 67.2, 77.1, 77.2).

4. Polar component (6', 7') according to any one of the preceding claims, wherein each of the holes of said plurality of fluid passage holes (64.7, 64.8, 74.7, 74.8) associated with each dispensing orifice (64.1, 64.2, 74.1, 74.2) has a main dimension (L1) along the main direction (D1) and a secondary dimension (L2) along a direction perpendicular (D2) to the main direction in the plate plane, the main dimension (L1) being greater than the secondary dimension (L2) by at least 10%, advantageously 50%, preferably 100%, of the secondary dimension.

5. Polar component (6', 7') according to any one of the preceding claims, wherein all the holes of the plurality of fluid passage holes (64.7, 64.8, 74.7, 74.8) associated with each dispensing orifice (64.1, 64.2, 74.1, 74.2) are aligned with each other along their main direction (D1), forming a single row between the flow rim (64.1 A, 64.2A, 74.1 A, 74.2A) of the dispensing orifice and the central part (63, 73).

6. A polar component (6', 7') according to any preceding claim, wherein each of the plurality of fluid passage holes (64.7, 64.8, 74.7, 74.8) associated with each dispensing orifice (64.1, 64.2, 74.1, 74.2) has a profile which is either oblong, elliptical, oval, substantially rectangular with rounded corners, or rectangular.

7. Polar component (6', 7') according to any one of the preceding claims, wherein the holes of the plurality of fluid passage holes (64.7, 64.8, 74.7, 74.8) respectively associated with the two distribution orifices (64.1, 64.2, 74.1, 74.2) have respective profiles which are identical to each other.

8. -Polar component according to any one of the preceding claims, in which the spacer pads (66.1, 66.2, 76.1, 76.2) associated with each distribution orifice (64.1, 64.2, 74.1, 74.2) of the polar plate (6, 7) are made of one material between them, forming a mat which is attached to the first face (61, 71) of the polar plate (6, 7).

9. Polar component according to any one of claims 1 to 7, in which the spacer pads (66.1, 66.2, 76.1, 76.2) associated with each distribution orifice (64.1, 64.2, 74.1, 74.2) of the polar plate (6, 7) are separate from each other on the first face (61, 71) of the first polar plate (6, 7).

10. Electrochemical cell (2) for a fuel cell (1), comprising: - a polar component, which is in accordance with any one of the preceding claims and of which the polar plate (6, 7) is a first polar plate, - a second polar plate (6, 7), which is applied against the first polar plate (6, 7) along the axis (X), the respective first faces (61, 71) of the first and second polar plates being turned towards each other, - a membrane-electrode assembly (5), which is interposed, along the axis, between the respective first faces of the first and second polar plates, and - for each distribution orifice (64.1, 64.2, 74.1, 74.2) of the first polar plate, a second seal (65, 75), which is attached projectingly on the first face of the second polar plate and of which a portion (65.3, 65.4, 75.3, 75.4) is arranged opposite, along the axis (X), the spacer pads (66.1, 66.2, 76.1, 76.2) so as to axially pinch the membrane-electrode assembly between the second seal and the spacer pads.

11. Electrochemical cell according to the preceding claim, in which the second polar plate (6, 7) belongs to a second polar component according to any one of claims 1 or 3 to 6.

12. Fuel cell (1), comprising electrochemical cells (2), which each conform to any one of claims 10 to 11 and which are stacked against each other along the axis (X).

13. Vehicle comprising a fuel cell (1) according to the preceding claim.

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