Separator plate, electrochemical cell and electrochemical device comprising such a plate

Abstract

The separator plate (15, 17) comprises: - an active zone (39, 47); - a homogenization zone (68) having a field (C) in which a group of homogenization channels (69) is provided, the homogenization channels (69) being juxtaposed from a first side (01) of the field (C) in the transverse direction; each homogenization channel (69) having a rectilinear portion (75) which extends in an eigendirection and has a substantially constant width perpendicular to the eigendirection, two adjacent rectilinear portions (75) being separated by a tooth (79); the eigendirections of the rectilinear portions (75) of the homogenization channels (69) forming acute angles (a) with the longitudinal direction, at least two consecutive acute angles (a) being different, and at least some teeth (79) having divergent opposite edges (81, 83).

Description

[0001] SEPARATOR PLATE, ELECTROCHEMICAL CELL AND ELECTROCHEMICAL DEVICE COMPRISING SUCH A PLATE

[0002] The invention generally relates to an electrochemical device, in particular a fuel cell.

[0003] This electrochemical device is of the type comprising a stack of electrochemical cells.

[0004] Each electrochemical cell comprises:

[0005] - a membrane-electrode assembly;

[0006] - an anodic separator plate and a cathodic separator plate pressed from two opposite sides against the membrane-electrode assembly.

[0007] The anodic and cathodic separator plates have openings for the circulation of the anodic fluid and the cathodic fluid. They also each have an active zone opposite the membrane-electrode assembly (MEA), in which teeth delimit between them longitudinal circulation channels for the anodic or cathodic fluid.

[0008] The anodic and cathodic separator plates have at their two opposite longitudinal ends homogenization zones putting the channels of the active zone into fluid communication with the openings for circulation of the anodic or cathodic fluid.

[0009] The homogenization zones allow the anodic fluid and the cathodic fluid to be distributed in the channels of the active zone.

[0010] The fluid distribution must be as homogeneous as possible, to allow satisfactory use of the entire surface of the AME.

[0011] In this context, the invention aims to propose, according to a first aspect, a separator plate allowing a particularly uniform distribution of fluid.

[0012] To this end, the invention relates to a separator plate adapted to be used in combination with another separator plate in an electrochemical cell of an electrochemical device such as a fuel cell, the two separator plates being adapted to be pressed on two opposite sides of a membrane electrode assembly, the separator plate extending in a plane in a longitudinal direction and a transverse direction, and comprising:

[0013] - an opening for the passage of a reactive fluid;

[0014] - an active zone fluidly connected to said passage opening, said active zone comprising a receiving surface formed by a plurality of active teeth separating longitudinal active channels for circulation of reactive fluid, said receiving surface being designed to receive the membrane-electrode assembly so as to allow an electrochemical reaction;

[0015] - a homogenization zone fluidly connecting said passage opening to said active zone, and having a field in which a group of homogenization channels is arranged, each homogenization channel having a proximal end fluidly communicating with the passage opening and a distal end fluidly communicating with at least one active channel, the homogenization channels being juxtaposed from a first side of the field in the transverse direction; each homogenization channel having a rectilinear section extending in a specific direction and of substantially constant width perpendicular to said specific direction, the rectilinear section extending from the proximal end, two neighboring rectilinear sections being separated by a tooth;the proper directions of the rectilinear sections of the homogenization channels forming acute angles with the longitudinal direction, at least two of the consecutive acute angles being different, at least some teeth having diverging opposite edges.;

[0016] The combination of non-constant acute angles and non-constant tooth thickness allows for good management of the flow and velocity of the reactive fluid in the homogenization zone. This contributes to achieving a substantially equal distribution of the reactive fluid across the entire width of the active zone, with pressure drops being substantially equal along the various homogenization channels.

[0017] The separating plate may also have one or more of the following characteristics, considered individually or in all technically possible combinations:

[0018] - the acute angles remain equal to each other or increase according to the juxtaposition from the first side of the field;

[0019] - the juxtaposition of homogenization channels comprises, on the first side of the field, a first group of homogenization channels with respective strictly increasing acute angles;

[0020] - the juxtaposition of homogenization channels comprises, opposite the first side of the field, a second group of homogenization channels with acute angles equal to each other;

[0021] - each homogenization channel comprises a diverging section having a transverse width increasing from the straight section to the distal end;

[0022] - each homogenization channel, at its distal end, opens directly into longitudinal proximal ends of a number of longitudinal channels between n-6 and n+6, n being a predetermined integer; - the separator plate comprises, between the active zone and the homogenization zone, a transition zone, the transition zone comprising longitudinal transition channels fluidly connecting the active channels of the active zone to the homogenization channels, the longitudinal channels being the transition channels, each homogenization channel, at its distal end, opening directly into the longitudinal proximal ends of a number of longitudinal channels between n-3 and n+3, n being a predetermined integer;

[0023] - the proximal ends of the homogenization channels are aligned in a proximal direction forming an angle between 0° and 40° with the transverse direction;

[0024] - the proximal ends of the homogenization channels are gathered on an area of ​​the separator plate transversely occupying less than 50% of a total transverse width of the separator plate, the active channels transversely occupying at least 75% of said total transverse width of the separator plate;

[0025] - the straight sections of the homogenization channels have increasing lengths following the juxtaposition from the first side of the field;

[0026] - in the subgroup consisting of half of the homogenization channels closest to the first side of the field, the widths of the straight sections of the homogenization channels increase following the juxtaposition from the first side of the field;

[0027] - the passage opening for a reactive fluid is located transversely in the center of the separating plate, the homogenization zone has, in addition to the field, another field in which another group of homogenization channels is arranged, each having a proximal end fluidly communicating with the passage opening and a distal end fluidly communicating with at least one active channel, each homogenization channel of the other field having a rectilinear section extending in its own direction and of substantially constant width perpendicular to said own direction, the rectilinear section extending from the proximal end, two neighboring rectilinear sections being separated by a tooth;the proper directions of the rectilinear sections of the homogenization channels of the other field forming acute angles with the longitudinal direction, at least two of said consecutive acute angles being different, at least some of said teeth having divergent opposite edges.;

[0028] According to a second aspect, the invention relates to a bipolar plate for an electrochemical device such as a fuel cell, comprising an assembly of two separator plates, at least one of the two separator plates having the above characteristics. According to a third aspect, the invention relates to an electrochemical cell for an electrochemical device such as a fuel cell, comprising:

[0029] - a membrane-electrode assembly;

[0030] - an anodic separator plate and a cathodic separator plate pressed from two opposite sides against the membrane-electrode assembly; the anodic separator plate and / or the cathodic separator plate having the above characteristics.

[0031] According to a fourth aspect, the invention relates to an electrochemical device such as a fuel cell, comprising a stack of electrochemical cells, at least one of these electrochemical cells being according to the preceding claim.

[0032] Other characteristics and advantages of the invention will emerge from the detailed description given below, for information purposes only and in no way limiting, with reference to the appended figures, among which:

[0033] - [Fig.1] Figure 1 is a perspective view of an electrochemical device;

[0034] - [Fig.2] Figure 2 is an exploded view of an electrochemical cell of the device of Figure 1, considered in perspective;

[0035] - [Fig.3] Figure 3 is a top view of one end of the anode plate of Figure 2, showing in particular the homogenization zone;

[0036] - [Fig.4] [Fig 5] Figures 4 and 5 are zooms of zones IV and V of figure 3;

[0037] - [Fig 6] Figure 6 is a view similar to that of Figure 4, illustrating an alternative embodiment of the invention which comprises a transition zone;

[0038] - [Fig 7] Figure 7 is a schematic representation, in longitudinal section, of the transition zone of Figure 6; and

[0039] - [Fig 8] Figure 8 is a top view of one end of a bipolar plate, illustrating another alternative embodiment of the invention.

[0040] The electrochemical device 1 shown in Figure 1 is typically a fuel cell.

[0041] Alternatively, it is an electrolyzer or any other type of corresponding electrochemical device.

[0042] This electrochemical device comprises a stack 3 of electrochemical cells 5.

[0043] The electrochemical cells 5 are stacked in a stacking direction E, one on top of the other.

[0044] The electrochemical device 1 further comprises two end plates 7, arranged on either side of the stack 3. The electrochemical cells 5 of the stack are pressed against each other between the two end plates 7.

[0045] Each electrochemical cell 5 comprises, as illustrated in Figure 2:

[0046] - a membrane-electrode assembly 9 (MEA);

[0047] - an anodic separator plate 15 and a cathodic separator plate 17 pressed on two opposite sides of said membrane-electrode assembly 9.

[0048] The AME 9 (Figure 7) comprises a membrane 10, anodic and cathodic catalytic layers 11 arranged on two large opposite faces of the membrane 10 and two gas diffusion layers 13 arranged on the anodic and cathodic catalytic layers 11.

[0049] The two gas diffusion layers 13 are interposed, one between the anode separator plate 15 and the anode catalytic layer 11 of the AME 9, and the other between the cathode separator plate 17 and the cathode catalytic layer 11 of the AME 9.

[0050] When several cells 3 are stacked on top of each other, the anode plate 15 of a given cell is placed against the cathode plate 17 of the neighboring cell, with the interposition of a sealing device, for example a gasket or a weld.

[0051] The assembly of anode separator plate 15 and cathode separator plate 17 forms a bipolar plate.

[0052] These two plates delimit between them a passage for the circulation of a heat transfer fluid, intended to cool the cells in the case of a fuel cell.

[0053] The membrane 10 is typically a proton exchange polymer membrane. The anodic catalytic layer constitutes an anode, and the cathodic catalytic layer constitutes a cathode.

[0054] The proton exchange membrane is, for example, made of a perfluorinated sulfide polymer material, such as the material known under the trade name “Nation”.

[0055] The anodic and cathodic catalytic layers 11 are typically made of porous structures, which allow the transport of reactive fluids, i.e. hydrogen and oxygen inside the catalytic layers.

[0056] These layers are typically formed from three different materials, namely:

[0057] - a material for transporting protons, for example the same material as the proton exchange membrane, such as the “Nation” material mentioned above,

[0058] - a material to transport electrons, for example carbon, and

[0059] - a material for catalyzing electrochemical oxidation and reduction reactions, for example platinum.

[0060] The gas diffusion layers 13 are formed of a porous material such as a carbon fiber fabric or porous carbon paper. They are pressed against the large faces of the membrane 10, with the anodic and cathodic catalytic layers 11 interposed.

[0061] When the fuel cell 1 is in operation, an oxidation reaction occurs at the anodic catalytic layer. This reaction consists of catalytically splitting the hydrogen supplied by the anodic fluid into protons and electrons. The protons thus produced pass through the proton exchange membrane until they reach the cathodic catalytic layer, while the electrons are conducted by the gas diffusion layer to the anodic plate and then conducted to the cathodic plate. At the same time, a reduction reaction occurs at the cathodic catalytic layer. This reaction consists of reacting the oxygen supplied by the cathodic fluid with the protons passing through the proton exchange membrane, as well as with the electrons supplied by the cathodic plate of the cell in question, thus forming water molecules.

[0062] The anode fluid is typically dihydrogen.

[0063] The cathode fluid is typically air or oxygen.

[0064] Each electrochemical cell 5 also comprises a frame 19, internally delimiting a window 20 in which the AME 9 is fixed (figure 7).

[0065] The frame 19 is typically formed from two layers of a polymer film, for example polyethylene naphthalate or terephthalate (PEN or PET).

[0066] The frame 19 extends in a longitudinal and transverse plane, substantially perpendicular to the stacking direction E. The longitudinal direction L and transverse direction T are shown in Figures 1 and 2.

[0067] In the example shown, it is generally rectangular in shape.

[0068] The AME 9 is substantially flat, and extends in the same plane as the frame 19.

[0069] Preferably, AME 9 includes frame 19, which makes it possible to form a separate sub-assembly.

[0070] The anodic separator plate 15 extends substantially in a longitudinal and transverse plane, perpendicular to the stacking direction E. It is typically metallic.

[0071] The anode separator plate 15 is generally rectangular in shape.

[0072] It is typically obtained by stamping, machining or any other manufacturing method.

[0073] Likewise, the cathode plate 17 also extends in a longitudinal and transverse plane substantially perpendicular to the stacking direction E.

[0074] It is preferably metallic, typically obtained by stamping, machining or any other manufacturing method.

[0075] It has a generally rectangular shape. The anode separator plate 15, as seen in FIG. 2, has at least a first anode opening 27a for the passage of the anode fluid and a second anode opening 29a for the passage of the cathode fluid.

[0076] The anode separator plate 15 further has third, fourth, fifth and sixth anode openings 31a, 33a, 35a, 37a.

[0077] The openings 31a and 33a are provided for the circulation of the anodic fluid and the cathodic fluid respectively.

[0078] For example, opening 27a allows the supply of the anode fluid and opening 31a is provided for the evacuation of the anode fluid.

[0079] The openings 33a and 29a are provided respectively for the supply of the cathode fluid and for the evacuation of the cathode fluid.

[0080] The openings 35a and 37a are provided for the circulation of the heat transfer fluid. For example, the opening 35a is provided for the supply of the heat transfer fluid and the opening 37a for the evacuation of the heat transfer fluid.

[0081] The openings 27a and 31a are diagonally opposite in the anode separator plate 15. Similarly, the openings 29a and 33a are diagonally opposite.

[0082] The openings 27a, 35a and 29a are placed at one longitudinal end of the plate 15. They are aligned transversely, in this order.

[0083] The openings 31a, 37a and 33a are placed at the opposite longitudinal end of the plate 15. They are aligned transversely, in this order.

[0084] In the same way, the cathode separator plate 17 comprises at least a first cathode opening 27c for the passage of the anodic fluid and a second cathode opening 29c for the passage of the cathodic fluid.

[0085] The cathode separator plate 17 further has third, fourth, fifth and sixth cathode openings 31c, 33c, 35c, 37c.

[0086] Openings 31c and 33c are provided for the circulation of the anode fluid and the cathode fluid respectively.

[0087] For example, opening 27c allows the supply of the anode fluid and opening 31c is provided for the evacuation of the anode fluid.

[0088] Openings 33c and 29c are provided respectively for the supply of the cathode fluid and for the evacuation of the cathode fluid.

[0089] Openings 35c and 37c are provided for the circulation of the heat transfer fluid. For example, opening 35c is provided for the supply of the heat transfer fluid and opening 37c for the discharge of the heat transfer fluid.

[0090] The openings 27c and 31c are diagonally opposite in the cathode separator plate 17. Similarly, the openings 29c and 33c are diagonally opposite. The openings 27c, 35c and 29c are placed at one longitudinal end of the plate 17. They are aligned transversely, in that order.

[0091] The openings 31c, 37c and 33c are placed at the opposite longitudinal end of the plate 17. They are aligned transversely, in this order.

[0092] The frame 19 comprises at least a first intermediate opening 27b for the passage of the anodic fluid and a second intermediate opening 29b for the passage of the cathodic fluid.

[0093] The frame further has third, fourth, fifth and sixth intermediate openings 31b, 33b, 35b, 37b.

[0094] The openings 31b and 33b are provided for the circulation of the anodic fluid and the cathodic fluid respectively.

[0095] For example, opening 27b allows the supply of the anode fluid and opening 31b is provided for the evacuation of the anode fluid.

[0096] The openings 33b and 29b are provided respectively for the supply of the cathode fluid and for the evacuation of the cathode fluid.

[0097] Openings 35b and 37b are provided for the circulation of the heat transfer fluid. For example, opening 35b is provided for the supply of the heat transfer fluid and opening 37b for the discharge of the heat transfer fluid.

[0098] Openings 27b and 31b are diagonally opposite in frame 19. Similarly, openings 29b and 33b are diagonally opposite.

[0099] The openings 27b, 35b and 29b are placed at one longitudinal end of the frame 19. They are aligned transversely, in this order.

[0100] The openings 31b, 37b and 33b are placed at the opposite longitudinal end of the frame 19. They are aligned transversely, in this order.

[0101] As seen in Figure 2, the openings 27a / 27b / 27c are coincident and together constitute a portion of the anode fluid supply manifold.

[0102] Similarly, the openings 29a / 29b / 29c are coincident and together constitute a portion of the cathode fluid discharge collector.

[0103] The openings 31a / 31b / 31c are coincident and together constitute a portion of the anode fluid discharge collector.

[0104] The openings 33a / 33b / 33c are coincident and together constitute a portion of the cathode fluid supply collector.

[0105] The openings 35a / 35b / 35c are coincident and together constitute a portion of the heat transfer fluid supply manifold.

[0106] The openings 37a / 37b / 37c are coincident and together constitute a portion of the heat transfer fluid discharge collector. Gaskets (broken lines not referenced in Figure 2) are placed around these openings and are interposed between the anode separator plate 15, the frame 19 and the cathode separator plate 17.

[0107] The anode separator plate 15 also comprises an active anode zone 39 fluidly connected to the first anode opening 27a.

[0108] The active anode zone 39 comprises a receiving surface S formed by a plurality of active anode teeth 40 separating longitudinal active anode channels 41 for circulation of the anode fluid.

[0109] The receiving surface S is designed to receive the membrane-electrode assembly 9 so as to allow an electrochemical reaction.

[0110] The active anodic zone 39 extends opposite the anodic catalytic layer 11 integrated in the AME 9. It is substantially of the same shape and size as the anodic catalytic layer 11.

[0111] The AME 9 is for example larger than the active anodic area 39. The gas diffusion layers 13 extend beyond the anodic catalytic layer 11 and cover the edge of the window 20 of the frame 19.

[0112] The anode separator plate 15 also comprises an anode homogenization zone 42 fluidly connecting the first anode opening 27a to the active anode channels 41 of the active anode zone 39.

[0113] By "fluidically connecting" or "fluidically connecting" we preferably mean that the zones in question are connected to each other via a fluidic connection means, that is to say by any means capable of conveying a fluid, such as, for example, in a non-exhaustive and non-limiting manner, a channel, a groove, a slot, etc. It is then understood that the sealing of the fluidic connection is achieved by a part added to the separating plate, such as for example another separating plate.

[0114] Furthermore, the anode separator plate 15 has another anode homogenization zone 42' fluidically connecting the active anode channels 40 of the active anode zone 39 to the opening 31a for the passage of the anode fluid.

[0115] The anodic homogenization zones 42 / 42' have fluid circulation channels not shown in Figure 2.

[0116] The active anodic zone 39 and the homogenizing anodic zones 42 / 42' are formed on a face 43 of the anodic plate 15 facing the AME 9, and pressed against it.

[0117] The anodic homogenization zones 42, 42' are placed opposite solid zones 45, 45' of the frame 19. The cathodic separator plate 17 comprises an active cathodic zone 47 fluidly connected to the second cathodic opening 29c.

[0118] The active cathode zone 47 comprises a receiving surface S formed by a plurality of active cathode teeth 48 separating longitudinal active cathode channels 49 for circulation of the cathode fluid.

[0119] The receiving surface S is designed to receive the membrane-electrode assembly 9 so as to allow an electrochemical reaction.

[0120] The active cathodic zone 47 extends opposite the cathodic catalytic layer 11 integrated in the AME 9. It is substantially of the same shape and size as the cathodic catalytic layer 11.

[0121] The AME 9 is for example larger than the active cathode area 47. The gas diffusion layers 13 extend beyond the cathode catalytic layer and cover the edge of the window 20 of the frame 19 (figure 7).

[0122] The cathode separator plate 17 also comprises a cathode homogenization zone 51 fluidly connecting the second cathode opening 29c to the active cathode channels 49 of the active cathode zone 45.

[0123] Furthermore, the cathode separator plate 17 has another cathode homogenization zone 51' fluidically connecting the active cathode channels 49 of the active cathode zone 47 to the opening 33c for the passage of the cathode fluid.

[0124] The 51 / 5T homogenization cathode zones have fluid circulation channels not shown in Figure 2.

[0125] The active cathode zone 47 and the homogenization cathode zones 51 / 51' are formed on a face 53 of the cathode plate 17 facing the AME 9, and pressed against it.

[0126] The cathode homogenization zones 51 / 51' are placed opposite the solid zones 45 / 45' of frame 19.

[0127] The separator plate of the invention will now be described, with reference to Figures 3 to 5.

[0128] This separator plate may be an anode plate 15 of the type described above or a cathode plate 17 of the type described above.

[0129] In Figure 2, the homogenization zones of the anodic plate and the cathodic plate are shown schematically. These shapes do not correspond exactly to that shown in Figure 3.

[0130] Furthermore, in Figure 3, the various openings of the plate are not shown, only a surface 55 in which the openings are provided being shown. The separating plate comprises a plate zone 57, comprising longitudinal channels 59 provided for the circulation of a reactive fluid, here the anode fluid or the cathode fluid.

[0131] These longitudinal channels 59 extend in general directions parallel to the longitudinal direction L.

[0132] By "general directions parallel to the longitudinal direction" is meant channels whose flow direction is substantially parallel to the longitudinal direction L. Thus, without departing from the scope of the invention, the longitudinal channels 59 may be rectilinear (i.e. straight) or have undulations (or waves) so as to give the fluid that they convey a slight zigzag movement in the transverse direction, without however calling into question the overall flow direction in the longitudinal direction L.

[0133] In the example shown in Figures 2 to 5, the plate area 57 is the active anode area 39.

[0134] The longitudinal channels 59 are the active anode channels 40.

[0135] If the separator plate is of the cathode type, the plate area 57 is the active cathode area 47.

[0136] The longitudinal channels 59 are then the active cathode channels 49.

[0137] The longitudinal channels 59 have longitudinal proximal ends 67.

[0138] The longitudinal proximal ends 67 are transversely aligned in the example shown.

[0139] In other words, they are all preferably located, along the longitudinal direction L, at the same position.

[0140] Alternatively, they are arranged in another layout.

[0141] The longitudinal proximal ends 67 transversely occupy at least 75% of the total transverse width of the separator plate, preferably at least 80%, more preferably at least 90% of the total transverse width.

[0142] This means that the sum of the transverse widths of the longitudinal proximal ends and the teeth separating these ends from each other is greater than 75%, 80% or 90% of said total transverse width.

[0143] The separating plate comprises a homogenization zone 68 fluidly connecting the active zone of the plate to the passage opening of the reactive fluid.

[0144] When the plate is an anodic plate 15, the homogenizing zone is zone 41 or zone 4T, and the opening is opening 27a or opening 31a. When the plate is a cathodic plate 17, the homogenizing zone is zone 51 or zone 5T, and the opening is opening 29c or opening 33c.

[0145] The homogenization zone 68 has a field C in which a group of homogenization channels 69 is arranged, each homogenization channel 69 having a proximal end 71 fluidly communicating with the passage opening 27a, 29c and a distal end 73 fluidly communicating with at least one active channel.

[0146] In the example shown in Figures 2 to 5, all the homogenization channels 69 are in field C, and are therefore part of said group.

[0147] Alternatively, additional homogenization channels are delimited outside the field C, and are therefore not part of the group of channels to be described below. These additional homogenization channels may have a different shape than the shape described below.

[0148] The field C is delimited by a first transverse side C1, and, on the opposite side by a second transverse side C2.

[0149] As illustrated in Figure 3, the term "transverse side" means an edge of the field C which extends at least in a secant manner to one of the longitudinal directions L or transverse T of the plate, and preferably which extends perpendicularly to the transverse direction T of the plate (i.e. which extends parallel to the longitudinal direction L of the plate).

[0150] Along the longitudinal direction, the field C is delimited towards the surface 55 (i.e. towards the plate openings) by a side C3 advantageously having the shape of a V, pointing towards the surface 55. The side C3 thus has a rectilinear branch C3' connected to the first transverse side C1 and a rectilinear branch C3” connected to the second transverse side C2.

[0151] Longitudinally opposite the surface 55, the field C is delimited by a line intersecting the longitudinal direction, preferably transverse (i.e. parallel to the transverse direction T of the plate) corresponding substantially to the longitudinal proximal ends 67.

[0152] Field C in the example shown is transversely as wide or slightly wider than plate area 57.

[0153] The homogenization channels 69 of the field C are juxtaposed from the first side C1 of the field in the transverse direction. They thus form a juxtaposition of channels.

[0154] Here, juxtaposed from the side C1 in the transverse direction means that the channels 69 are placed side by side transversely, each channel 69 being framed by two other channels placed transversely on either side of said channel, except for the channels placed at the ends of the juxtaposition.

[0155] The proximal ends 71 ​​of the homogenization channels 69 are preferentially aligned in a proximal direction DP.

[0156] This proximal DP direction is substantially parallel to the C3' branch.

[0157] The proximal direction DP forms an angle between 0° and 40° with the transverse direction, preferably between 5° and 30°, and more preferably between 10° and 20°.

[0158] The proximal ends 71 ​​transversely occupy less than 50% of the total transverse width of the separator plate.

[0159] This means that, in projection onto a transverse line, the sum of the transverse widths of the proximal ends 71 ​​and of the teeth separating these ends from each other is less than 50% of said total transverse width. In other words, the opening of the channels 69 extends over less than half the width of the plate.

[0160] In Figure 3, the median longitudinal line LM of the separator plate has been marked by a dot-and-dash line. This line divides the separator plate into two equal halves.

[0161] The proximal ends 71 ​​of all the homogenization channels 69, in the example shown, are located on the same side of the line LM in the transverse direction. They are preferably located between the side C1 and the line LM.

[0162] They are arranged along one side of opening 27a or opening 31a if the separator plate is of the anode type. They are arranged along one side of opening 29c or opening 33c if the separator plate is of the cathode type.

[0163] Each homogenizing channel 69 has a channel length between the proximal end 71 and the distal end 73. The length is taken along the center line LC of each channel. The center line LC passes through the midpoints of each of the segments of said channel. The center lines LC of several of the channels are shown in Figure 3.

[0164] Each homogenization channel 69 preferably comprises a rectilinear section 75 extending rectilinearly in a specific direction from the proximal end 71. Such a rectilinear section advantageously makes it possible to convey the active fluid without inducing any pressure loss, at constant speed and pressure.

[0165] The rectilinear section 75 advantageously extends over a length greater than 30% of the channel length. The lengths of the rectilinear sections 75 of the homogenization channels 69 are preferentially increasing when the juxtaposition is followed from the first side C1 of the field C.

[0166] In other words, for a given homogenization channel 69, the homogenization channel 69 located next to said given channel, opposite the side C1, has a rectilinear section 75 preferably longer than the rectilinear section 75 of said given channel.

[0167] The rectilinear section 75 of the homogenization channel 69 closest to the side C1 is advantageously the shortest. The rectilinear section 75 of the homogenization channel 69 located at the other end of the juxtaposition, that is to say the furthest from the channel C1, preferably has the greatest length.

[0168] For example, the length of the straight sections closest to the C1 side is between 30% and 60% of the total length of the corresponding channel. Opposite the C1 side, the length of the straight section is between 70% and 95% of the total length of the homogenization channel.

[0169] These different lengths of rectilinear section 75 of the homogenization channels were remarkably optimized during the design of the plate in order to find the best possible compromise(s) between compactness of the homogenization zone (and therefore optimization of the size of the active zone) and fluidic performances.

[0170] The proper directions of the rectilinear sections 75 correspond to the directions in which the central lines LC of the channels extend along said rectilinear sections 75.

[0171] These natural directions form acute angles α with the longitudinal direction L. Preferably, at least two of the consecutive acute angles α are different. Such a variation of the angles α advantageously makes it possible, on the one hand, to optimize the size of the homogenization channels (and therefore to maximize the surface area of ​​the active zone) and, on the other hand, to properly manage the fluid flow over the entire width of the active zone. This results in a good compromise between the compactness of the homogenization zone and its fluidic performance.

[0172] Preferably, these acute angles a remain equal to each other or increase according to the juxtaposition from the first side C1 of the field C.

[0173] In other words, when the rectilinear sections 75 of the different homogenization channels are considered in turn, starting from the side C1 and going towards the side C2, the proper directions of the rectilinear sections 75 form increasingly larger angles α with the longitudinal direction. In the example shown, the rectilinear section 75 of the homogenization channel closest to the side C1 is substantially longitudinal. Its proper direction forms an angle α close to zero with the longitudinal direction L.

[0174] The rectilinear section 75 of the homogenization channel immediately adjacent to this first channel has a specific direction which forms an angle a close to 40° with the longitudinal direction L. The homogenization channel furthest from the side C1 has a rectilinear section 75 whose specific direction forms an angle a close to 60° with the longitudinal direction.

[0175] Each rectilinear section 75 is preferably of constant width. This width is taken perpendicular to the proper direction of the rectilinear section.

[0176] The respective widths of the rectilinear sections 75 of the homogenization channels advantageously increase overall following the juxtaposition from the first side C1 of the field C.

[0177] In particular, in the subgroup consisting of half of the homogenization channels 69 closest to the first side C1 of the field C, the widths of the rectilinear sections 75 of the homogenization channels 69 increase following the juxtaposition from the first side C1 of the field.

[0178] In other words, the rectilinear section 75 of a first homogenization channel 69 has a first width. The immediately neighboring homogenization channel 69, opposite the first side C1, will have a rectilinear section 75 having a second width greater than or equal to the first.

[0179] The length and width of the rectilinear sections of the different homogenization channels 69 are chosen to obtain substantially the same flow rate downstream in the longitudinal channels 59.

[0180] Each homogenization channel 69 preferably comprises a divergent section 77, having a transverse width increasing from the rectilinear section 75 to the distal end 73.

[0181] The divergent section 77 first has a first zone Z1 adjoining the rectilinear section, having a transverse width which increases as one moves away from the rectilinear section 75 (figure 4). This first zone Z1 is extended by a second zone Z2 of constant transverse width, extending to the distal end 73 of the homogenization channel 69.

[0182] The central line LC, at the level of zone Z2, is preferentially substantially longitudinal.

[0183] It is preferably curved or oblique at the level of zone Z1. Each homogenization channel 69, at its distal end 73, opens directly into the longitudinal proximal ends 67 of a number of longitudinal channels 59 between n-6 and n+6, n being a predetermined integer. n is for example the average of the number of longitudinal channels 59 supplied by the different homogenization channels 69, rounded to the nearest integer.

[0184] For example, half of the homogenization channels 69 furthest from the C1 side open into a number of longitudinal channels 59 between n and n+6, for example between 12 and 18.

[0185] For example, half of the homogenization channels 69 closest to the C1 side open into a number of longitudinal channels 59 between n and n-6, for example between 6 and 12.

[0186] Two neighboring rectilinear sections 75 are separated by a tooth 79.

[0187] Each tooth 79 is a raised shape, made in the separator plate.

[0188] Each tooth 79 has two opposite edges 81, 83.

[0189] Each edge 81, 83 is a surface projecting relative to the bottom of the homogenization channel and connecting to this bottom, making it possible to channel the fluid.

[0190] Each rectilinear section 75 is delimited on one side by the edge 81 of a tooth 79, and on the other side by the edge 83 of another tooth 79, close to the first.

[0191] Because the rectilinear sections 75 are of constant width, the edges 81 and 83 delimiting the same rectilinear section 75 are parallel to each other. These edges belong to two different teeth, adjacent to each other.

[0192] At least some teeth 79 preferentially have opposite edges 81, 83 that diverge.

[0193] These edges diverge from a tip 84 of the tooth 79, located at the proximal end of the channels delimited by said tooth 79.

[0194] More precisely, the juxtaposition of homogenization channels 69 comprises, towards the first side C1 of the field C, a first group of homogenization channels 69 with respective acute angles a strictly increasing transversely away from the side C1. Some of these channels are shown in FIG. 5. The rectilinear sections 75 of this first group of homogenization channels 69 are delimited by a first group of teeth 79 each having opposite edges 81, 83 diverging.

[0195] The juxtaposition of homogenization channels 69 preferably also comprises, opposite the first side C1 of the field, a second group of homogenization channels 69 with acute angles a equal to each other. Some of these channels are shown in Figure 4. The rectilinear sections 75 of this second group of homogenization channels 69 are delimited by a second group of teeth 79 each having opposite edges 81, 83 parallel to each other.

[0196] For example, the plate has N homogenization channels in field C, separated by N-1 teeth 79.

[0197] Preferably, between 50% and 70% of the N-1 teeth 79 have opposite edges 81, 83 diverging. These teeth 79 are closest to the C1 side. They constitute a first group of teeth.

[0198] Preferably, between 30% and 50% of the N-1 teeth 79 have opposite edges 81, 83 parallel to each other, these teeth 79 being the furthest from the C1 side. They constitute a second group of teeth.

[0199] As seen in Figure 3, the teeth 79 are juxtaposed transversely, in the same way as the channels 69.

[0200] Preferably, the teeth 79 of the first group of teeth each have opposite edges 81, 83 which diverge, and which form an angle p between them.

[0201] Advantageously, the angle p decreases when following the first group of teeth 79 from the side C1. For example, the tooth 79 closest to the side C1 has an angle p of approximately 30°. The tooth 79 of the first group furthest from the side C1 has an angle p close to zero. These values, judiciously chosen by design and fluid simulations, make it possible to optimize the fluid distribution while minimizing the size.

[0202] Remarkably, the architecture of the homogenization zone as defined by the invention, and in particular the combination of the non-constant angles a as well as the non-constant thickness of the teeth 79, makes it possible to properly manage the flow and speed of the fluid in the homogenization zone, which makes it possible to have an equal distribution of the fluid over the entire width of the active zone (i.e. in the transverse direction T), in particular at the level of the fluid pressure. This results in better efficiency and better performance of the plate, therefore of the cell, therefore of the electrochemical device concerned.

[0203] Preferably, the separating plate 15 also has longitudinal teeth 85, each longitudinal tooth 85 extending one of the teeth 79.

[0204] The longitudinal teeth 85 are advantageously parallel to the longitudinal direction L. They extend the corresponding tooth 79 to the distal end 73 of the channels 69. They separate the diverging sections 77 of the channels 69 from each other.

[0205] Each longitudinal tooth 85 is delimited by two edges 87, 89.

[0206] The edges 87, 89 are longitudinal and preferably parallel to each other. The tooth 79 closest to the C1 side has a different shape from the others and will be described below.

[0207] For the other teeth 79, the edge 81 is preferably rectilinear and has a portion 88 which extends beyond the rectilinear section 75, up to the edge 87 (figure 5). The edge 87 is of short length longitudinally.

[0208] The edge 83 extends to an angle 91 marking the limit between the rectilinear section 75 and the divergent section 77 of the homogenization channel 69.

[0209] The edge 89 preferably extends in a straight line up to the angle 91. It thus delimits the end 94 of the tooth 79 opposite the tip 84.

[0210] The diverging section 77 is thus delimited on one side by the edge 89, and on the other side by the edge 87 and the portion 88 of the edge 81 extending beyond the rectilinear section 75.

[0211] As visible in Figure 5, the homogenization channel 69 located closest to the side C1 is advantageously delimited on one side by a tooth 95 of substantially longitudinal orientation, with two edges parallel to each other and on the other by a tooth 79 having diverging edges 81, 83.

[0212] Tooth 95 is straight and extends into plate area 57.

[0213] The edge 81 of the tooth 79 stops at an angle 97 marking the end of the straight section. It is connected to the edge 87 of the extension 85 by an inclined edge 99. The edge 99 forms for example an angle of approximately 120° with the edge 81. It also forms an angle of approximately 120° with the edge 87.

[0214] The teeth 79 of the second group have, as described above, first and second edges 81, 83 parallel to each other.

[0215] These teeth 79 are therefore of constant width from the tip 84 to the end 94 opposite the tip 84.

[0216] It should be noted that the tips 84 of all the teeth 79 are of substantially the same width. On the other hand, the ends 94 of the teeth 79 of the second group are much less wide than the ends 94 of the teeth 79 of the first group.

[0217] The longitudinal teeth 85 extending the teeth 79 of the second group are substantially of the same width as said teeth 79.

[0218] As seen in Figures 3 and 4, the homogenization channel 69 located opposite the side C1 is delimited on one side by a tooth 79 of the second group, and on the other side by an end tooth 100. The end tooth 100 is of the same type as the teeth 79 of the second group. It is of constant width, with two edges parallel to each other.

[0219] It should be noted that the longitudinal length of the longitudinal teeth 85 increases as one moves away from the side C1. In the example shown, the longitudinal teeth 85 separating the channels 69 of the first group are all substantially the same length. On the other hand, the longitudinal teeth 85 separating the channels 69 of the second group have lengths that increase as one moves away from the edge C1.

[0220] When the separator plate is an anode plate 15, it can be arranged as described above only on one of the two homogenization zones 42, 42', or on both homogenization zones 42, 42'.

[0221] When the separator plate is a cathode plate 17, it can be arranged as described above only on one of the two homogenization zones 51, 5T, or on both homogenization zones 51, 5T.

[0222] An alternative embodiment of the invention will now be described, with reference to Figure 6. Only the points by which this alternative differs from that of Figures 2 to 5 will be detailed below. Elements that are identical, or provide the same functions, will be designated by the same references as in the alternative of Figures 2 to 5.

[0223] In the variant of figure 6, the separating plate comprises, between the active zone 39 / 47 and the homogenization zone 68, a transition zone 101.

[0224] The transition zone 101 is interposed longitudinally between the active zone 39 / 47 and the homogenization zone 68. It extends substantially over the entire transverse width of the separating plate.

[0225] The transition zone 101 comprises transition channels 103, fluidically connecting the active channels 41 / 49 of the active zone to the homogenization channels 69.

[0226] The transition zone 101 extends for example opposite an edge of the membrane electrode assembly 9, at which the gas diffusion layers cover the edge of the window 20 of the frame 19 (figure 7). The transition zone 101 is not located opposite the anodic or cathodic catalytic layer.

[0227] The transition channels 103 are longitudinal.

[0228] The number of transition channels 103 is less than the number of active channels 41 / 49. For example, several active channels 41 / 49 open into each transition channel 103. In the example shown, two active channels 41 / 49 open into each anode transition channel 103.

[0229] In the variant of Figure 6, the plate area 57 is the transition area 101. The longitudinal channels 59 are the transition channels 103. The longitudinal proximal ends 67 are the longitudinal proximal ends of the transition channels 103.

[0230] The distal ends of the homogenization channels open directly into the longitudinal proximal ends of the transition channels 103. In the variant of FIG. 6, each homogenization channel 69, at its distal end 73, opens directly into the longitudinal proximal ends of a number of longitudinal channels 59 between n-3 and n+3, n being a predetermined integer.

[0231] According to another aspect of the invention applicable to the variant of figure 6 or 7, the active teeth 40, 48 have respective proximal ends 105 defining a separation line LS between the active zone 39, 47 and the transition zone 101.

[0232] This dividing line LS is for example transverse, as shown in Figure 6. Alternatively, it is oblique to the transverse direction. The dividing line LS is typically a straight line.

[0233] The active teeth 40, 48 have vertices 107 which are inscribed in a reference plane P (figure 7).

[0234] The reference plane P is parallel to the plane in which the frame 19 extends.

[0235] As illustrated in Figure 7, the separating plate has in the homogenization zone 68 a homogenization bottom 109 located at a first altitude a1 relative to the reference plane P.

[0236] The homogenization bottom 109 is a flat region of the separating plate, substantially perpendicular to the stacking direction E. The altitude a1 is taken along the stacking direction E. It corresponds to the distance between the homogenization bottom 109 and the plane P.

[0237] The separating plate also has in the homogenization zone 68 reliefs projecting towards the reference plane P relative to the homogenization bottom 109.

[0238] These reliefs correspond to the homogenization teeth 79.

[0239] The separating plate has in the transition zone 101 a transition bottom 111 located relative to the reference plane P at a second altitude a2 greater than the first altitude a1.

[0240] The transition bottom 111 is constituted by one or more regions of the separating plate. These regions are inscribed in the same plane perpendicular to the stacking direction E. For example, these regions are substantially flat.

[0241] The second altitude a2 corresponds to the distance between this plane and the reference plane P, taken perpendicular to the reference plane P, that is to say following the stacking direction E.

[0242] The transition background defines the background of the transition channels 103.

[0243] As seen in Figure 7, the transition bottom 111 is separated from the homogenization bottom 109 by a step 113. This step 113 results from the difference in altitude between the homogenization bottom 109 and the transition bottom 111.

[0244] The difference between the second altitude a2 and the first altitude a1 is between 10 pm and 300 pm, preferably between 50 pm and 200 pm, for example being substantially equal to 80 pm or 160 pm, advantageously respectively for a polar plate of the anode or cathode type.

[0245] As visible in Figure 6, this step 113 is substantially transverse, and extends over the entire transverse width of the homogenization zone 68. It is formed in the separating plate.

[0246] A buffer volume 115 is thus delimited between the transition bottom 111, the step 113 and the separation line LS, thus making it possible to balance the distribution of the reactive fluid arriving from the homogenization zone 68 in the active channels 41, 49.

[0247] The active zone 39, 47 has a determined active length LA longitudinally.

[0248] The separation line LS is separated longitudinally from the step 113 by a longitudinal spacing of between 2% and 20% of the active length LA. Preferably, the longitudinal spacing is between 4 and 15%, and more preferably between 5 and 10% of the active length LA. This longitudinal spacing corresponds to the longitudinal length of the buffer volume 115.

[0249] The edge 117 of the GDL is separated longitudinally from the step 113 by a longitudinal spacing of between 2% and 20% of the active length (LA). Preferably, the longitudinal spacing is between 4 and 15%, and more preferably between 5 and 10% of the active length LA.

[0250] Furthermore, the homogenization zone 68 has, at the level of the step 113, a first passage section P1 for the reactive gas. This passage section P1 is taken perpendicular to the longitudinal direction.

[0251] The passage section is taken at the top of step 113, that is to say at the limit between the homogenization bottom 109 and step 113.

[0252] The first passage section P1 corresponds to the free section, offered to the reactive fluid which flows from the homogenization zone 68 into the transition zone 101. The first section corresponds to the section delimited between the homogenization bottom 109 and the frame 19, less the section possibly occupied by the reliefs formed at the level of the step 113. For example, the transition channels are delimited by transition teeth 119. The transition teeth 119 extend to the step 113, the ends of the transition teeth 119 reducing the first passage section P1.

[0253] The buffer volume 115 has, between the edge 117 and the step 113, a second passage section P2 for the reactive fluid, between the first passage section P1 plus 20% and the first passage section P1 plus 80%, preferably between the first passage section P1 plus 40% and the first passage section P1 plus 70%, typically substantially equal to the first passage section P1 plus 60%. The second passage section P2 is taken perpendicular to the longitudinal direction L.

[0254] The condition stated above is verified for all sections of the buffer volume 115 located between the step 113 and the edge 117. In other words, the passage section of the buffer volume 115 is substantially constant from the step 113 to the edge 117 of the GDL.

[0255] The passage section corresponds to the free section offered to the reactive fluid to circulate longitudinally in the buffer volume 115. It thus corresponds to the section delimited between the transition bottom 111 and the frame 19, minus the section occupied by the transition teeth 119.

[0256] The transition teeth 119 have vertices 121 located at a distance from the frame 19.

[0257] This distance is taken along the stacking direction E.

[0258] Each transition tooth 119 has a first segment 123 pressed against the GDL 11, and a second free segment 125, longitudinally extending the first segment 123. The first segment 123 adjoins the active zone 39, 47. The second segment 125 is located longitudinally beyond the edge 117 of the GDL.

[0259] Each transition tooth 119 also has a third segment 127, formed on the step 113, and extending slightly inside the homogenization zone 68. The third segment 127 reduces the first passage section P1.

[0260] In other words, the transition teeth 119 extend longitudinally over the entire length of the transition zone 101, up to the step 113.

[0261] The reactive fluid can therefore circulate transversely between the tops 121 of the transition teeth and the frame 19 at the level of the second sections 125.

[0262] As can be seen in Figure 7, the separator plate has, in the active zone 39, 47, an active bottom 129 located at the second altitude a2 relative to the reference plane P, the active teeth 40, 48 projecting towards the reference plane P relative to the active bottom 129. The altitude of the active bottom 129 is taken according to the stacking direction E.

[0263] The active bottom 129 is made up of regions of the separating plate lying in the same plane substantially perpendicular to the stacking direction E. This plane is located at the same altitude a2 as the transition bottom 111.

[0264] These regions are separated from each other by the active teeth 40, 48 and delimit the bottom of the active channels 41, 49. In other words, the transition bottom 111 and the active bottom 129 are inscribed in the same plane perpendicular to the stacking direction E, located at the altitude a2 relative to the reference plane P.

[0265] The apices 107 of the active teeth are located in contact with the GDL 11.

[0266] The transition teeth 119 project towards the reference plane P relative to the transition bottom 111 over a first height h1. The active teeth 40, 48 project towards the reference plane P relative to the active bottom 129 over a second height h2 equal to the first height h1.

[0267] Another alternative embodiment of the invention will now be described, with reference to Figure 8. Only the points by which this variant differs from that of Figures 2 to 5 will be detailed below. Identical elements, or those providing the same functions, will be designated by the same references as in the variant of Figures 2 to 5.

[0268] As indicated above, the homogenization zone 68 has a field C in which a group of homogenization channels 69 is arranged, placing one of the openings of the plate in fluid communication with the longitudinal channels 59. This opening 131 is here located transversely to the center of the plate and is provided for the passage of the anodic fluid or the cathodic fluid, depending on the type of plate.

[0269] The homogenization zone 68 has, in addition to the field C, another field D in which another group of homogenization channels 69 is arranged, each having a proximal end 71 fluidly communicating with the passage opening 131 and a distal end 73 fluidly communicating with at least one active channel 41, 49.

[0270] In the example shown in Figure 7, half of the homogenization channels 69 connecting said opening with the longitudinal channels 59 are in field C, and the other half in field D.

[0271] Field D is delimited by a first transverse side D1.

[0272] In the example shown, the D1 side is confused with the C1 side, and the D field is symmetrical to the C field with respect to the median line LM.

[0273] Field C in the example shown extends transversely over half the width of plate area 57. Field D also extends transversely over half the width of plate area 57.

[0274] The homogenization channels 69 of the field D are juxtaposed from the first side D1 of the field in the transverse direction. They thus form a juxtaposition of channels.

[0275] Each homogenization channel 69 of the field D comprises a rectilinear section 75 extending in a rectilinear manner in a specific direction. The specific directions of the rectilinear sections 75 correspond to the directions in which the central lines LC of the channels extend along said rectilinear sections 75.

[0276] These proper directions form acute angles a with the longitudinal direction L. At least two of the consecutive acute angles a are different

[0277] Typically, acute angles a are equal or increasing depending on the juxtaposition from the first side D1 of the field D.

[0278] Two adjacent rectilinear sections 75 in alignment are separated by a tooth 79. At least some teeth 79 have opposite edges 81 and 83 which diverge.

[0279] The rectilinear sections of the homogenization channels of field C and the rectilinear sections of the homogenization channels of field D together fan out around the orifice 131 of the plate.

[0280] The homogenizing channels 69 of field D, and the teeth 79 separating the straight sections, are as described above for field C.

[0281] The invention described above has multiple advantages.

[0282] Because the natural directions of the rectilinear sections of the homogenization channels form acute angles with the longitudinal direction remaining equal to each other or increasing according to the juxtaposition from the first side of the field, so that at least some teeth have opposite edges diverge, it is possible to distribute the homogenization channels in a fan-shaped pattern in the field considered. This distribution is particularly suitable when the opening of the plate bringing the reactive fluid is at an angle. It allows the reactive fluid to be distributed over a large width with little or no change of direction along each channel, which helps to reduce pressure losses and homogenize the flow rates in the longitudinal channels.

[0283] The fact that the juxtaposition of homogenization channels comprises, on the first side of the field, a first group of homogenization channels with strictly increasing respective acute angles, contributes to making the distribution of the homogenization channels well adapted to the case where the opening of the plate is located on the first side of the field.

[0284] The fact that the juxtaposition of homogenization channels comprises, opposite the first side of the field, a second group of homogenization channels with acute angles equal to each other, contributes to making the distribution of the homogenization channels well adapted to the case where the opening of the plate is located on the first side of the field. When each homogenization channel comprises a diverging section having an increasing transverse width from the straight section to the distal end, it is possible to choose the width of the straight section so as to equalize the pressure losses in the different homogenization channels, and thus homogenize the flow rates in the longitudinal channels.

[0285] When each homogenization channel, at its distal end, opens directly into the longitudinal proximal ends of a number of longitudinal channels between n-6 and n+6, n being a predetermined integer, the homogenization channels serve a number of longitudinal channels not too different from each other, which facilitates the homogenization of the flow rates in the longitudinal channels.

[0286] When the longitudinal proximal ends of the longitudinal channels are aligned transversely, with the proximal ends of the homogenizing channels aligned along a proximal direction forming an angle between 0° and 40° with the transverse direction, the fan-shaped distribution of the homogenizing channels is easier to organize.

[0287] When the proximal ends of the homogenizing channels are gathered on an area of ​​the separator plate transversely occupying less than 50% of a total transverse width of the separator plate, the longitudinal proximal ends of the longitudinal channels transversely occupying at least 75% of said total transverse width of the separator plate, the fan-shaped distribution of the homogenizing channels is easier to organize.

[0288] Providing that, in the subgroup consisting of half of the homogenization channels closest to the first side of the field, the widths of the straight sections of the homogenization channels increase following the juxtaposition from the first side of the field helps to equalize the pressure losses in the different homogenization channels.

Claims

CLAIMS 1. A separator plate (15, 17) adapted to be used in combination with another separator plate (17, 15) in an electrochemical cell of an electrochemical device such as a fuel cell, the two separator plates (15, 17) being adapted to be pressed from two opposite sides of a membrane electrode assembly (9), the separator plate (15, 17) extending in a plane in a longitudinal direction (L) and a transverse direction (T), and comprising: - an opening (27a, 31a; 29c, 33c) for the passage of a reactive fluid; - an active zone (39, 47) fluidically connected to said passage opening (27a, 31a; 29c, 33c), said active zone (39, 47) comprising a receiving surface (S) formed by a plurality of active teeth (40, 48) separating longitudinal active channels (41, 49) for circulation of reactive fluid, said receiving surface (S) being designed to receive the membrane-electrode assembly (9) so as to allow an electrochemical reaction; - a homogenization zone (68) fluidly connecting said passage opening (27a, 31a; 29c, 33c) to said active zone (40, 48), and having a field (C) in which a group of homogenization channels (69) is arranged, each homogenization channel (69) having a proximal end (71) fluidly communicating with the passage opening (27a, 31a; 29c, 33c) and a distal end (73) fluidly communicating with at least one active channel (41, 49), the homogenization channels (69) being juxtaposed from a first side (C1) of the field (C) in the transverse direction; each homogenization channel (69) having a rectilinear section (75) extending in a specific direction and of substantially constant width perpendicular to said specific direction, the rectilinear section (75) extending from the proximal end (71), two neighboring rectilinear sections (75) being separated by a tooth (79);the proper directions of the rectilinear sections (75) of the homogenization channels (69) forming acute angles (a) with the longitudinal direction, at least two of the consecutive acute angles (a) being different, at least some teeth (79) having opposite edges (81, 83) diverging.; 2. Separator plate according to claim 1, in which the acute angles (a) remain equal to each other or increase according to the juxtaposition from the first side (C1) of the field.

3. Separator plate according to claim 1 or 2, in which the juxtaposition of homogenization channels (69) comprises, on the first side (C1) of the field, a first group of homogenization channels (69) with respective strictly increasing acute angles (a).

4. Separator plate according to any one of the preceding claims, wherein the juxtaposition of homogenization channels (69) comprises, opposite the first side (C1) of the field, a second group of homogenization channels (69) with acute angles (a) equal to each other.

5. Separator plate according to any one of the preceding claims, in which each homogenization channel (69) comprises a diverging section (77) having a transverse width increasing from the straight section (75) to the distal end (73).

6. Separator plate according to any one of the preceding claims, in which each homogenization channel (69), at its distal end (73), opens directly into longitudinal proximal ends (67) of a number of longitudinal channels (59) between n-6 and n+6, n being a predetermined integer.

7. Separator plate according to claim 6, wherein the separator plate comprises, between the active zone (39, 47) and the homogenization zone (68), a transition zone (101), the transition zone (101) comprising longitudinal transition channels (103) fluidly connecting the active channels (41, 49) of the active zone (39, 47) to the homogenization channels (69), the longitudinal channels (59) being the transition channels (103), each homogenization channel (69), at its distal end (73), opening directly into the longitudinal proximal ends (67) of a number of longitudinal channels (59) between n-3 and n+3, n being a predetermined integer.

8. Separator plate according to any one of the preceding claims, in which the proximal ends (71) of the homogenization channels (69) are aligned in a proximal direction forming an angle of between 0° and 40° with the transverse direction.

9. Separator plate according to any one of the preceding claims, wherein the proximal ends (71) of the homogenizing channels (69) are gathered on an area of ​​the separator plate (15, 17) transversely occupying less than 50% of a total transverse width of the separator plate (15, 17), the active channels (59) transversely occupying at least 75% of said total transverse width of the separator plate (15, 17).

10. Separator plate according to any one of the preceding claims, in which the rectilinear sections (75) of the homogenization channels (69) have increasing lengths following the juxtaposition from the first side (C1) of the field.

11. Separator plate according to any one of the preceding claims, in which, in the subgroup consisting of half of the homogenization channels (69) closest to the first side (C1) of the field, the widths of the rectilinear sections (75) of the homogenization channels (69) increase according to the juxtaposition from the first side (C1) of the field.

12. Separator plate according to any one of the preceding claims, in which the opening (131) for the passage of a reactive fluid is located transversely to the center of the separator plate, the homogenization zone (68) has, in addition to the field (C), another field (D) in which another group of homogenization channels (69) is arranged, each having a proximal end (71) fluidly communicating with the passage opening (131) and a distal end (73) fluidly communicating with at least one active channel (41, 49), each homogenization channel (69) of the other field (D) having a rectilinear section (75) extending in a specific direction and of substantially constant width perpendicular to said specific direction, the rectilinear section (75) extending from the proximal end (71), two neighboring rectilinear sections (75) being separated by a tooth (79);the proper directions of the rectilinear sections (75) of the homogenization channels (69) of the other field (D) forming acute angles (a) with the longitudinal direction, at least two of said consecutive acute angles (a) being different, at least some of said teeth (79) having opposite edges (81, 83) diverging.; 13. Bipolar plate for an electrochemical device such as a fuel cell, comprising an assembly of two separator plates (15, 17), at least one of the two separator plates (15, 17) being according to one of the preceding claims.

14. Electrochemical cell (5) for an electrochemical device such as a fuel cell, comprising: - a membrane-electrode assembly (9); - an anodic separator plate (15) and a cathodic separator plate (17) pressed from two opposite sides against the membrane-electrode assembly (9); the anodic separator plate (15) and / or the cathodic separator plate (17) being according to any one of claims 1 to 12.

15. Electrochemical device such as a fuel cell, comprising a stack of electrochemical cells (5), at least one of these electrochemical cells (5) being according to the preceding claim.

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