Cell and electrochemical device, in particular a fuel cell
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- SYMBIO FRANCE
- Filing Date
- 2024-08-02
- Publication Date
- 2026-06-10
AI Technical Summary
The existing electrochemical devices, such as fuel cells, face inefficiencies due to over-compression at the recovery zones, which disrupts the flow of active gases and can lead to deformation of separator plates, causing sealing issues and a decrease in the active area's effectiveness.
The design includes an intermediate zone with transversely offset teeth on the anodic and cathodic separator plates, allowing for a wavy section between the active and homogenization zones, which accommodates the frame edge and reduces over-compression, ensuring better gas passage and preventing plate deformation.
This configuration enhances gas flow and reduces over-compression, maintaining efficiency and preventing sealing issues, thereby improving the performance and longevity of the electrochemical device.
Smart Images
Figure EP2024072049_06022025_PF_FP_ABST
Abstract
Description
[0001] TITLE: Electrochemical cell and device, in particular fuel cell
[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 comprising a membrane, anodic and cathodic catalytic layers arranged on two large opposite faces of the membrane and two gas diffusion layers arranged on the anodic and cathodic catalytic layers;
[0006] - a frame, internally delimiting a window in which the membrane-electrode assembly is fixed, the window having an edge;
[0007] - an anodic separator plate and a cathodic separator plate pressed against the two gas diffusion layers.
[0008] 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.
[0009] 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.
[0010] At both longitudinal ends of the MEA, the window edges may be interposed between the membrane and at least one of the gas diffusion layers, along the two opposite edges of the MEA. These edges are called overlap zones.
[0011] The central area of the AME, between the overlapping areas, has, in the absence of compression, a first thickness. At the overlapping areas, the AME and the edges together have, in the absence of compression, a second thickness greater than the first.
[0012] As a result, the gas diffusion layers are more strongly compressed in the overlap zone than in the central zone. The teeth of the separator plates are excessively pressed into the gas diffusion layers in the overlap zones. The flow section offered to the anode gas and the cathode gas in the channels is therefore reduced. The back pressure in the overlap zones is therefore relatively high. As a result, the flow of active gases is disrupted, particularly in the overlap zone. This results in a loss of efficiency and a reduction in the active zone. The excess thickness can also lead to deformation of the separator plates, including up to their peripheral zone, which can lead to a loss of tightness at their peripheral joints.
[0013] In this context, the invention aims to provide an electrochemical cell or an electrochemical device which does not have the above defects.
[0014] To this end, the invention relates, according to a first aspect, to an electrochemical cell comprising:
[0015] - a membrane-electrode assembly comprising a membrane, anodic and cathodic catalytic layers arranged on two large opposite faces of the membrane and two gas diffusion layers arranged on the anodic and cathodic catalytic layers;
[0016] - a frame, internally delimiting a window in which the membrane-electrode assembly is fixed, the window having an edge;
[0017] - an anodic separator plate and a cathodic separator plate pressed against the two gas diffusion layers; the anodic separator plate comprising at least a first anodic opening for the passage of an anodic fluid, a second anodic opening for the passage of a cathodic fluid, an active anodic zone comprising anodic channels for the circulation of the anodic fluid and an anodic homogenization zone fluidically connecting the first anodic opening to the anodic channels of the active anodic zone;the cathode separator plate comprising at least a first cathode opening for the passage of the anodic fluid, a second cathode opening for the passage of the cathodic fluid, an active cathode zone comprising cathode channels for the circulation of the cathode fluid and a cathode homogenization zone fluidly connecting the second cathode opening to the cathode channels of the active cathode zone, the first cathode opening being superimposed on the first anodic opening, the second cathode opening being superimposed on the second anodic opening; the anodic separator plate comprising, between the anodic homogenization zone and the active anodic zone, an intermediate anodic zone with intermediate anodic channels fluidly connecting the anodic homogenization zone to the anodic channels, these intermediate anodic channels being delimited between transversely juxtaposed intermediate anodic teeth;the cathode separator plate comprising, between the cathode homogenization zone and the active cathode zone, an intermediate cathode zone with intermediate cathode channels fluidly connecting the cathode homogenization zone to the cathode channels, these intermediate cathode channels being delimited by transversely juxtaposed intermediate cathode teeth; the edge of the frame being interposed between the membrane and at least one of the gas diffusion layers, between the intermediate anodic zone and the intermediate cathode zone, and not between the active anodic zone and the active cathode zone; the intermediate anodic teeth and the intermediate cathode teeth are transversely offset from each other, such that each intermediate anodic tooth faces an intermediate cathode channel and each intermediate cathode tooth faces an intermediate anodic channel.;
[0018] The cell may also have one or more of the following characteristics, considered individually or in all technically possible combinations:
[0019] - the membrane-electrode assembly has a transversely corrugated section between the intermediate anodic zone and the intermediate cathodic zone;
[0020] - said corrugated section alternately comprises anodic bumps bulging towards the anodic separator plate and cathodic bumps bulging towards the cathodic separator plate, each anodic bump being located between an intermediate cathodic tooth and an intermediate anodic channel, and each cathodic bump being located between an intermediate anodic tooth and an intermediate cathodic channel;
[0021] - the membrane-electrode assembly has, in the absence of compression, a first thickness, the membrane-electrode assembly and the edge together having, in the absence of compression, a second thickness greater than the first;
[0022] - the anode channels of the active anode zone are delimited between active anode teeth juxtaposed transversely and having a first anode altitude, and the cathode channels of the active cathode zone are delimited between active cathode teeth juxtaposed transversely and having a first cathode altitude;
[0023] - the intermediate anode teeth have a second anode altitude substantially equal to the first anode altitude, and / or the intermediate cathode teeth have a second cathode altitude substantially equal to the first cathode altitude;
[0024] - an active anodic tooth on N extends into the intermediate anodic zone and forms one of the intermediate anodic teeth, N-1 active anodic teeth on N not extending into the intermediate anodic zone, N being an integer between 2 and 4; and / or - an active cathodic tooth on N' extends into the intermediate cathodic zone and forms one of the intermediate cathodic teeth, N'-1 active cathodic teeth on N' not extending into the intermediate cathodic zone, N' being an integer between 2 and 4;
[0025] - the intermediate anodic teeth and the intermediate cathodic teeth are parallel to each other;
[0026] - the intermediate anodic teeth and the intermediate cathodic teeth are straight;
[0027] - the intermediate cathode zone extends transversely over the entire width of the active cathode zone, and / or the intermediate anodic zone extends transversely over the entire width of the active anodic zone;
[0028] - the intermediate anodic teeth have a first anodic width transversely and the intermediate cathodic channels have a first cathodic width transversely greater than the first anodic width;
[0029] - the intermediate cathode teeth have a second cathode width transversely and the intermediate anodic channels have a second anodic width transversely greater than the second cathode width.
[0030] According to a second aspect, the invention relates to an electrochemical device comprising a stack of cells, each cell having the above characteristics. Preferably, the electrochemical device is a fuel cell.
[0031] Other characteristics and advantages of the invention will emerge from the detailed description given below, with reference to the appended figures, among which:
[0032] - Figure 1 is a perspective view of an electrochemical device;
[0033] - Figure 2 is an exploded, schematic view of an electrochemical cell of the device of Figure 1, considered in perspective;
[0034] - Figure 3 is a simplified schematic representation in longitudinal section of the overlap area of the electrochemical cell of Figure 2;
[0035] - Figure 4 is a schematic top view of one end of the electrochemical cell of Figure 2; and
[0036] - Figures 5 and 6 are sections of the electrochemical cell of Figure 4, taken transversely according to the incidence of arrows V and VI.
[0037] The electrochemical device 1 shown in Figure 1 is typically a fuel cell.
[0038] Alternatively, it is an electrolyzer or any other type of corresponding electrochemical device. This electrochemical device comprises a stack 3 of electrochemical cells 5.
[0039] The electrochemical cells 5 are stacked in a stacking direction E, one on top of the other.
[0040] The electrochemical device 1 also comprises two end plates 7, arranged on either side of the stack 3.
[0041] The electrochemical cells 5 of the stack are pressed against each other between the two end plates 7.
[0042] Each electrochemical cell 5 comprises, as illustrated in Figures 2 and 3, a membrane-electrode assembly 8 (MEA) comprising a membrane 9, anodic and cathodic catalytic layers 10, 10' arranged on two large opposite faces of the membrane 9 and two gas diffusion layers 11 arranged on the anodic and cathodic catalytic layers 10, 10'.
[0043] The electrochemical cell 5 also comprises an anode separator plate 15 and a cathode separator plate 17 pressed against the two gas diffusion layers 11.
[0044] The two gas diffusion layers 11 are interposed, one between the anode separator plate 15 and the anode catalytic layer 10 of the AME 8, and the other between the cathode separator plate 17 and the cathode catalytic layer 10' of the AME 9.
[0045] 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 such as a gasket or a weld, so as to form a bipolar plate. 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.
[0046] The membrane is typically a proton exchange polymer membrane. The anodic catalytic layer constitutes an anode, and the cathodic catalytic layer constitutes a cathode.
[0047] The proton exchange membrane is, for example, made of a perfluorinated sulfide polymer material, such as the material known under the trade name “Nation”.
[0048] The anodic and cathodic catalytic layers are typically made of porous structures, which allow the transport of reactive fluids, i.e. hydrogen and oxygen inside the catalytic layers.
[0049] These layers are typically formed from three different materials, namely:
[0050] - a material for transporting protons, for example the same material as the proton exchange membrane, such as the “Nation” material mentioned above, - a material for transporting electrons, for example carbon, and
[0051] - a material for catalyzing electrochemical oxidation and reduction reactions, for example platinum.
[0052] 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.
[0053] The anode fluid is typically dihydrogen.
[0054] The cathode fluid is typically air or oxygen.
[0055] Each cell 5 also has a frame 19, internally delimiting a window 20 in which the AME 8 is fixed. The window 20 has an edge 21.
[0056] Edge 21 has a closed contour. It delimits window 20.
[0057] Window 20 is rectangular.
[0058] The frame 19 is typically formed from two layers 22 of a polymer film, for example polyethylene naphthalate or terephthalate (PEN or PET).
[0059] 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.
[0060] In the example shown, it is generally rectangular in shape.
[0061] The AME 8 is substantially flat, and extends in the same plane as the frame 19.
[0062] The AME 8 has, at its two opposite longitudinal ends, two edges called overlap zones 23, 23'.
[0063] The overlap zones 23, 23' extend transversely across the entire width of the AME 8.
[0064] In the example shown, the AME 8 is rectangular. The overlapping zones 23, 23' are rectilinear and transverse strips.
[0065] As can be seen in Figure 3, in one of the overlapping zones 23, 23' or each overlapping zone 23, 23', the edge 21 of the window 20 is interposed between the membrane 9 and at least one of the gas diffusion layers 11. This makes it possible to maintain the membrane 9 and to guarantee a seal between the two faces of the membrane and each other.
[0066] In each overlap zone 23, 23', the two layers of polymer film 22 constituting the edge 21 are arranged on either side of the membrane 9, between the membrane 9 and the gas diffusion layers 11. They cover the large faces of the membrane 9. Typically, they are plated on the anodic and cathodic catalytic layers 10, 10'.
[0067] According to a variant not shown, one of the two layers of polymer film 22 constituting the edge 21 is arranged on one side of the membrane 9, between the membrane 9 and one of the gas diffusion layers 11. The other layer of polymer film 22 does not extend between the membrane 9 and the gas diffusion layers 11. It stops before covering the membrane 9.
[0068] According to another variant not shown, the frame 9 is made up of a single layer of polymer film. The part of this layer constituting the edge 21 is arranged on one side of the membrane 9, between the membrane 9 and one of the gas diffusion layers 11
[0069] The edge 21 extends transversely across the entire width of each overlap zone 23, 23'.
[0070] On the other hand, the edge 21 does not extend beyond the overlapping zones 23, 23', and does not cover the central zone 25 of the membrane 9, located longitudinally between the two overlapping zones 23, 23'.
[0071] Edge 21 also reinforces the other two edges of AME 8, located transversely on the two opposite sides of AME 8.
[0072] The overlapping areas 23, 23' extend over a fraction of the longitudinal length of the MEA 8. For example, the edge 21 covers the membrane 9 longitudinally over a length of between 0.5 and 8 mm in each overlapping area.
[0073] The gas diffusion layers 11 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 9, with the interposition of the anodic and cathodic catalytic layers 10, 10'.
[0074] They cover all the large faces of the membrane 9.
[0075] In particular, the gas diffusion layers 1 1 cover the overlapping zones 23, 23' of the AME 8.
[0076] This ensures that there is no area of the membrane not covered with the gas diffusion layer and possibly to fix the gas diffusion layer to the frame by different bonding techniques. As illustrated in Figure 3, the gas diffusion layers 11 typically have edge areas 26 which extend beyond the overlap areas 23, 23', on the strip 26zc of the frame 19 adjoining the edge 21. This strip is called here overlap area CDG / frame 26zc. The edge areas 26 thus extend longitudinally beyond the membrane 9. Only the frame 19 is interposed between the edge areas 26, without the membrane 9 or the anodic and cathodic catalytic layers 10, 10'.
[0077] Alternatively, the gas diffusion layers 11 stop at the same level of the membrane 9, and do not have edge zones 26 which extend beyond the overlap zones 23, 23', on the strip 26zc of the frame 19 adjoining the edge 21.
[0078] According to yet another variant, the gas diffusion layers 11 are longitudinally shorter than the membrane 9, and only partially cover the overlapping zones 23, 23' of the MEA 8. They only partially cover the edge 21.
[0079] The CDG / frame 26zc overlap area has a longitudinal length of between 0 and 10 mm.
[0080] In the central zone 25, the AME 8 has a thickness e1 in the absence of compression. As can be seen in Figure 3, the thickness e1 is formed by the thickness of the membrane 9 and two thicknesses of catalytic layers, in this case a thickness of anodic catalytic layer 10 and a thickness of cathodic catalytic layer 10', the latter two being preferably equal.
[0081] Along the overlapping zones 23, 23', the AME 8 and the edge 21 together have a thickness e2 in the absence of compression. As can be seen in Figure 3, the thickness e2 is formed by the thickness of the membrane 9, two frame thicknesses 19 and two catalytic layer thicknesses, in this case an anodic catalytic layer thickness 10 and a cathodic catalytic layer thickness 10', the latter two being preferably equal. In other words, the thickness e2 is formed by the thickness e1 plus two frame thicknesses 19. The thickness e2 is therefore greater than the thickness e1.
[0082] In the CGD / frame overlap zone 26zc, the gas diffusion layers 11 and the frame 19 together have a thickness e3 in the absence of compression. As can be seen in Figure 3, the thickness e3 is formed by two frame thicknesses 19 and two catalytic layer thicknesses, in this case an anodic catalytic layer thickness 10 and a cathodic catalytic layer thickness 10', the latter two being preferably equal. In other words, the thickness e3 is formed by the thickness e2 minus the thickness e1. In still other words, the thickness e3 is less than the thickness e2 of the membrane thickness 9. The thickness e3 is therefore greater than the thickness e1 and less than the thickness e2. For example, the difference between the thickness e2 and the thickness e1 is between 0.01 and 0.5 mm, preferably between 0.02 and 0.4 mm, and more preferably between 0.03 and 0.1 mm.This therefore corresponds to two thicknesses of catalytic layers.
[0083] For example, the difference between the thickness e2 and the thickness e3 is between 0.001 and 0.05 mm, preferably between 0.003 and 0.03 mm, and more preferably between 0.005 and 0.025 mm. This therefore corresponds to the thickness of the membrane 9, which may for example be of the order of 10 μm.
[0084] As can be clearly seen in Figure 3, there is an excess thickness at the level of the overlap zone 23, 23'. This excess thickness, due to the local superposition of the membrane 9, the frame 19 and two catalytic layers, makes it possible to guarantee good sealing of each of the faces of the membrane and good maintenance of the latter.
[0085] These different thicknesses e1, e3 and in particular e2, can cause overcompression problems at the level of the overlap zone 23, which can compromise the proper passage of the active gases, in particular in the catalytic layer. A deformation of the separating plates 15, 17 is also to be feared.
[0086] The anodic separator plate 15 extends substantially in a longitudinal and transverse plane, perpendicular to the stacking direction E. It is typically metallic.
[0087] The anode separator plate 15 is generally rectangular in shape.
[0088] It is typically obtained by stamping, machining or any other manufacturing method.
[0089] Likewise, the cathode plate 17 also extends in a longitudinal and transverse plane substantially perpendicular to the stacking direction E.
[0090] It is preferably metallic, typically obtained by stamping or machining.
[0091] It has a generally rectangular shape.
[0092] 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.
[0093] The anode separator plate 15 further has third, fourth, fifth and sixth anode openings 31a, 33a, 35a, 37a.
[0094] The openings 31a and 33a are provided for the circulation of the anodic fluid and the cathodic fluid respectively.
[0095] For example, opening 27a allows the supply of the anode fluid and opening 31a is provided for the evacuation of the anode fluid. Openings 33a and 29a are provided respectively for the supply of the cathode fluid and for the evacuation of the cathode fluid.
[0096] 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.
[0097] The openings 27a and 31a are diagonally opposite in the anode separator plate 15. Similarly, the openings 29a and 33a are diagonally opposite.
[0098] The openings 27a, 35a and 29a are placed at one longitudinal end of the plate 15. They are aligned transversely, in this order.
[0099] The openings 31a, 37a and 33a are placed at the opposite longitudinal end of the plate 15. They are aligned transversely, in this order.
[0100] 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.
[0101] The cathode separator plate 17 further has third, fourth, fifth and sixth cathode openings 31c, 33c, 35c, 37c.
[0102] Openings 31c and 33c are provided for the circulation of the anode fluid and the cathode fluid respectively.
[0103] For example, opening 27c allows the supply of the anode fluid and opening 31c is provided for the evacuation of the anode fluid.
[0104] Openings 33c and 29c are provided respectively for the supply of the cathode fluid and for the evacuation of the cathode fluid.
[0105] 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.
[0106] Openings 27c and 31c are diagonally opposite in the cathode separator plate 17. Similarly, openings 29c and 33c are diagonally opposite.
[0107] The openings 27c, 35c and 29c are placed at one longitudinal end of the plate 17. They are aligned transversely, in this order.
[0108] The openings 31c, 37c and 33c are placed at the opposite longitudinal end of the plate 17. They are aligned transversely, in this order.
[0109] 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.
[0110] The frame further has third, fourth, fifth and sixth intermediate openings 31 b, 33 b, 35 b, 37 b. The openings 31 b and 33 b are provided for the circulation of the anode fluid and the cathode fluid respectively.
[0111] For example, opening 27b allows the supply of the anode fluid and opening 31b is provided for the evacuation of the anode fluid.
[0112] The openings 33b and 29b are provided respectively for the supply of the cathode fluid and for the evacuation of the cathode fluid.
[0113] 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.
[0114] Openings 27b and 31b are diagonally opposite in frame 19. Similarly, openings 29b and 33b are diagonally opposite.
[0115] The openings 27b, 35b and 29b are placed at one longitudinal end of the frame 19. They are aligned transversely, in this order.
[0116] The openings 31b, 37b and 33b are placed at the opposite longitudinal end of the frame 19. They are aligned transversely, in this order.
[0117] As seen in Figure 2, the openings 27a / 27b / 27c are coincident and together constitute a portion of the anode fluid supply manifold.
[0118] Similarly, the openings 29a / 29b / 29c are coincident and together constitute a portion of the cathode fluid discharge collector.
[0119] The openings 31a / 31b / 31c are coincident and together constitute a portion of the anode fluid discharge collector.
[0120] The openings 33a / 33b / 33c are coincident and together constitute a portion of the cathode fluid supply collector.
[0121] The openings 35a / 35b / 35c are coincident and together constitute a portion of the heat transfer fluid supply manifold.
[0122] The openings 37a / 37b / 37c are coincident and together constitute a portion of the heat transfer fluid evacuation collector.
[0123] 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.
[0124] The anode separator plate 15 also comprises an active anode zone 39 comprising anode channels 41 for circulation of the anode fluid.
[0125] It also comprises an anodic homogenization zone 43 fluidly connecting the first anodic opening 27a to the anodic channels 41 of the active anodic zone 39. In addition, the anodic separator plate 15 has another anodic homogenization zone 43' fluidly connecting the anodic channels 41 of the active anodic zone 39 to the opening 31a for the passage of the anodic fluid.
[0126] The anodic homogenization zones 43 / 43' comprise fluid circulation channels not shown. Alternatively, the anodic homogenization zones 43 / 43' comprise other reliefs such as studs to direct the flow of the anodic fluid.
[0127] As illustrated in Figures 2 and 4, the anode separator plate 15 comprises, between the anode homogenization zone 43 and the active anode zone 39, an intermediate anode zone 45 with intermediate anode channels 47.
[0128] The anodic homogenization zone 43 is interposed longitudinally between the intermediate anodic zone 45 and the first anodic opening 27a.
[0129] The intermediate anode zone 45 longitudinally extends the active anode zone 39. It adjoins the active anode zone 39.
[0130] It has the shape of a strip, extending transversely over the entire width of the active anode zone 39. It fluidically connects the active anode zone 39 to the homogenization anode zone 43.
[0131] It extends the active anodic zone 39 towards the homogenization anodic zone 43.
[0132] Symmetrically, the anode separator plate 15 has another intermediate anode zone 45', extending the active anode zone 39 longitudinally opposite the intermediate anode zone 45.
[0133] The other anodic homogenization zone 43' is interposed longitudinally between the other intermediate anodic zone 45' and the opening 31a.
[0134] The other intermediate anode zone 45' has the shape of a strip, extending transversely over the entire width of the active anode zone 39. It fluidically connects the active anode zone 39 to the other homogenization anode zone 43'.
[0135] The other intermediate anode zone 45' extends the active anode zone 39 towards the other homogenization anode zone 43'.
[0136] The active anodic zone 39, the intermediate anodic zones 45 / 45' and the homogenization anodic zones 43 / 43' are formed on a face 49 of the anodic plate 15 facing the gas diffusion layer 11, and pressed against it.
[0137] The active anodic zone 39 covers the central zone 25 of the membrane 9. It has substantially the same size and shape.
[0138] The intermediate anodic zone 45 covers the overlap zone 23.
[0139] It has the same size and shape as the overlap area 23. Alternatively, to take into account the positional tolerances of all the elements during assembly, the intermediate anodic area is larger than the overlap area in order to ensure that after assembly the intermediate anodic area completely covers the overlap area.
[0140] Similarly, the other intermediate anode zone 45' covers the other overlap zone 23'.
[0141] It has the same size and shape as the other overlap area 23'. Alternatively, to accommodate positional tolerances of all elements during assembly, the other intermediate anode area is larger than the other overlap area to ensure that after assembly the other intermediate anode area completely covers the other overlap area.
[0142] The anodic homogenization zones 43, 43' are placed opposite solid zones 51, 5T of the frame 19.
[0143] The cathode separator plate 17 comprises an active cathode zone 53 comprising cathode channels 55 for circulation of the cathode fluid.
[0144] It also comprises a cathode homogenization zone 57 fluidly connecting the second cathode opening 29c to the cathode channels 55 of the active cathode zone 53.
[0145] Furthermore, the cathode separator plate 17 has another cathode homogenization zone 57' fluidically connecting the cathode channels 55 of the active cathode zone 53 to the opening 33c for the passage of the cathode fluid.
[0146] The cathode homogenization zones 57 / 57' comprise fluid circulation channels not shown. Alternatively, the cathode homogenization zones 57I5T comprise other reliefs such as studs to direct the flow of the cathode fluid.
[0147] As illustrated in FIG. 2, the cathode separator plate 17 comprises, between the homogenization cathode zone 57 and the active cathode zone 53, an intermediate cathode zone 59 with intermediate cathode channels 61.
[0148] The homogenization cathode zone 57 is interposed longitudinally between the intermediate cathode zone 59 and the second cathode opening 29c.
[0149] The intermediate cathode zone 59 longitudinally extends the active cathode zone 53. It adjoins the active cathode zone 53.
[0150] It has the shape of a strip, extending transversely over the entire width of the active cathode zone 53. It fluidically connects the active cathode zone 53 to the homogenization cathode zone 57.
[0151] It extends the active cathode zone 53 towards the homogenization cathode zone 57. Symmetrically, the cathode separator plate 17 has another intermediate cathode zone 59', extending the active cathode zone 53 longitudinally opposite the intermediate cathode zone 59.
[0152] The other homogenization cathode zone 57' is interposed longitudinally between the other intermediate cathode zone 59' and the opening 33c.
[0153] The other intermediate cathode zone 59' has the shape of a strip, extending transversely over the entire width of the active cathode zone 53. It fluidically connects the active cathode zone 53 to the other homogenization cathode zone 57'.
[0154] The other intermediate cathode zone 59' extends the active cathode zone 53 towards the other homogenization cathode zone 57'.
[0155] The active cathode zone 53, the intermediate cathode zones 59 / 59' and the homogenization cathode zones 57 / 57' are formed on a face 63 of the cathode plate 17 facing the gas diffusion layer 11, and pressed against it, as visible in FIG. 2.
[0156] The active cathode zone 53 covers the central zone 25 of the membrane 9. It has substantially the same size and shape.
[0157] The intermediate cathode area 59 covers the overlap area 23.
[0158] It has the same size and shape as the overlap area 23. Alternatively, to take into account the position tolerances of all the elements during assembly, the intermediate cathode area is larger than the overlap area 23.
[0159] Similarly, the other intermediate cathode area 59' covers the other overlap area 23'.
[0160] It has the same size and shape as the other overlap area 23'. Alternatively, to take into account the positional tolerances of all the elements during assembly, the other intermediate cathode area is larger than the other overlap area 23'.
[0161] The cathode homogenization zones 57 / 57' are placed opposite the solid zones 51 / 5T of frame 19.
[0162] In Figure 4, a longitudinal end of the cell 5 is shown schematically in top view, the anode separator plate 15 upwards. The anode separator plate 15 and the cathode separator plate 17 are shown superimposed. The AME 9 and the frame 19 are taken between the two plates 15, 17. The anode homogenization zone 43, the intermediate anode zone 45 and a part of the active anode zone 39 are visible by transparency.
[0163] The intermediate cathode zone 59 and the overlap zone 23 are superimposed under the intermediate anodic zone 45. The active cathode zone 53 and the central zone 25 of the membrane 9 are superimposed under the active anodic zone 39.
[0164] In other words, the edge 21 of the frame 19 is interposed between the membrane 9 and at least one of the gas diffusion layers 11, between the intermediate anodic zone 45 and the intermediate cathodic zone 59, and not between the active anodic zone 39 and the active cathodic zone 53.
[0165] In the same way, the edge 21 of the frame 19 is interposed between the membrane 9 and at least one of the gas diffusion layers 11, between the other intermediate anodic zone 45' and the other intermediate cathodic zone 59'.
[0166] As visible in Figure 6, the anode channels 41 of the active anode zone 39 are delimited between active anode teeth 65. These teeth are represented by continuous lines in Figure 4. They are juxtaposed transversely.
[0167] In the same way, the cathode channels 55 of the active cathode zone 53 are delimited between transversely juxtaposed active cathode teeth 67. These teeth are visible by transparency in Figure 4 and represented by broken lines.
[0168] The active anode teeth 65, in the example shown, are sinuous. They are parallel to each other. Each tooth 65 forms bumps alternately on either side of a longitudinal line. The bumps are all of the same height.
[0169] Similarly, the active cathode teeth 67, in the example shown, are sinuous. They are parallel to each other. Each tooth 67 forms bumps alternately on either side of a longitudinal line. The bumps are all of the same height, and are of the same height as the bumps formed by the teeth 65.
[0170] The bumps of the active anode teeth 65 are in phase opposition with respect to the bumps formed by the active cathode teeth 67.
[0171] The active anodic teeth 65 and the active cathodic teeth 67 intersect in places, with certain portions of these teeth being superimposed.
[0172] Alternatively, the teeth 65, 67 are straight and longitudinal.
[0173] As seen in Figure 5, the intermediate anode channels 47 are delimited between transversely juxtaposed intermediate anode teeth 69.
[0174] Likewise, the intermediate cathode channels 61 are delimited by transversely juxtaposed intermediate cathode teeth 71. The intermediate anodic teeth 69 and the intermediate cathode teeth 71 are rectilinear.
[0175] They extend longitudinally.
[0176] Typically, the intermediate anode teeth 69 are extensions of at least some active anode teeth 65. Similarly, the intermediate cathode teeth 71 are extensions of at least some active cathode teeth 67.
[0177] The anode intermediate teeth 69 and the cathode intermediate teeth 71 are transversely offset relative to each other, such that each anode intermediate tooth 69 faces an intermediate cathode channel 61. In the same way, each intermediate cathode tooth 71 faces an intermediate anode channel 47.
[0178] Such a shift of the teeth in the intermediate zone makes it possible to guarantee that the intermediate teeth of the separating plates do not overlap. This makes it possible, remarkably, to create free spaces to accommodate, locally, in particular the excess thicknesses e1, e3 and / or e2, defined previously. In other words, the AME 8 will be able to easily fit into the free spaces formed by the alternation of the intermediate teeth. The excess thicknesses e1, e3 and in particular the excess thickness e2 are therefore “absorbed” by the alternation of the teeth in the intermediate zone. This results in a reduction, or even an elimination, of the overcompression phenomenon in the overlap zone. Therefore, the active gases can easily and freely circulate, without overpressure, and the aforementioned disadvantages are eliminated.
[0179] Preferably, the AME 8 has a transversely undulating section along the overlap zone 21, that is to say between the intermediate anodic zone 45 and the intermediate cathodic zone 59.
[0180] Each intermediate anodic tooth 69 has a peak 73 framed by two flanks 75. The peak 73, in the example shown, is flat.
[0181] Each channel 47 is delimited by a base 77, and by the sides 75 of the two teeth 69 which frame it. The teeth 69 protrude relative to the base 77 of the channels 47. The base 77 is flat in the example shown.
[0182] The anode intermediate teeth 69 have a first anode width 11 transversely, and the anode intermediate channels 47 have a second anode width 12 transversely.
[0183] Widths 11 and 12 are taken transversely.
[0184] The widths 11 are taken at mid-height of the teeth. The widths 12 are taken at mid-depth of the channels, which corresponds substantially to mid-height of the teeth. In the same way, the intermediate cathode channels 61 have a transverse first cathode width 11'. The intermediate cathode teeth 71 have a transverse second cathode width 12'.
[0185] The widths 11' and 12' are taken as the widths 11 and 12.
[0186] The intermediate cathode teeth 71 each have a top 79 and two flanks 81 framing the top 79. The top 79, in the example shown, is flat.
[0187] Each intermediate cathode channel 61 is delimited by a base 83 and the flanks 81 of the two teeth 71 which frame it. The teeth 71 protrude relative to the base 83 of the channels 61. The base 83 is flat in the example shown.
[0188] Advantageously, the first cathode width IT is greater than the first anodic width 11. Conversely, the second anodic width I2 is greater than the second cathodic width I2'.
[0189] This situation is illustrated in Figure 5. Such width ratios make it possible to further accentuate the size of the free spaces and facilitate the oscillation of the AME 8 in the intermediate zone,
[0190] The first cathode width IT is typically between two and four times the first anodic width 11, and is for example three times the first anodic width 11.
[0191] The second anodic width I2 is typically between two and four times the second cathodic width I2', and is for example three times the second anodic width I2'.
[0192] More specifically, the corrugated section alternately comprises anodic bumps 85 bulging towards the anodic separator plate 15, and cathodic bumps 87 bulging towards the cathodic separator plate 17.
[0193] Each anodic bump 85 is located, according to the stacking direction E, between an intermediate cathodic tooth 71 and an intermediate anodic channel 47. The concave side of the bump 85 is placed on the intermediate cathodic tooth 71. The convex side of the bump 85 is engaged in the intermediate anodic channel 47.
[0194] Conversely, each cathode bump 87 is located, according to the stacking direction E, between an anodic intermediate tooth 69 and a cathodic intermediate channel 61. The concave side of the bump 87 is placed on the anodic intermediate tooth 69. The convex side of the bump 87 is engaged in the cathodic intermediate channel 61.
[0195] Due to the large width of the intermediate anodic and cathodic channels 47, 61, the bumps can be inserted into these channels without being compressed between the intermediate anodic and cathodic teeth 69, 71. Furthermore, the widening of the intermediate anodic and cathodic channels 47, 61 makes it possible to provide the anodic and cathodic fluids with a large passage section, such that the pressure losses are limited.
[0196] The active anode teeth 65 have a first anode altitude h1, visible in figure 6.
[0197] The intermediate anode teeth 69 have a second anode altitude h2, substantially equal to the first anode altitude h1.
[0198] Similarly, the active cathode teeth 67 have a first cathode altitude h T.
[0199] The intermediate cathode teeth 79 have a second cathode altitude h2' substantially equal to the first cathode altitude h1
[0200] The altitude of the teeth is taken relative to a reference plane P.
[0201] This plane P is perpendicular to the elevation direction E.
[0202] The reference plane P is defined as being halfway, along the stacking direction E, between the planes Pa and Pc (figure 6).
[0203] The plane Pa is the plane in which the tops of the active anode teeth 65 extend. This plane Pa is perpendicular to the elevation direction E.
[0204] The plane Pc is the plane in which the tops of the active cathode teeth 67 extend. This plane Pc is perpendicular to the elevation direction E.
[0205] Thus, the teeth in the active zone and in the intermediate zones of the anode plate have approximately the same altitude, which facilitates manufacturing.
[0206] The teeth in the active area and in the intermediate areas of the cathode plate also have the same altitude, which facilitates manufacturing.
[0207] As can be seen in Figure 6, the spacing along the elevation direction E between the active anode teeth 65 and the active cathode teeth 67 is slightly less than the thickness e1, i.e. the thickness of the AME 8. The difference is a few tens of μm. Thus, the AME 8 is very slightly compressed between the active anode zone 39 and the active cathode zone 53 at the points where the active anode teeth 65 cross the active cathode teeth 67.
[0208] Each active anode channel 41 has a third anode width I3, shown in Figure 6.
[0209] Each active cathode channel 55 has a third cathode width I3', also shown in Figure 6.
[0210] These widths are taken perpendicular to the central line along which the channel extends, at mid-depth of the channels, i.e. mid-height of the teeth framing the channels. Advantageously, the second anodic width I2 is between two and four times the third anodic width I3.
[0211] Similarly, the second cathode width I2' is between two and four times the third cathode width I3'.
[0212] This makes it possible to provide a sufficient passage section for the anodic fluid and the cathodic fluid in the intermediate zones 45 and 59.
[0213] To achieve this result, an active anode tooth 65 on N extends into the intermediate anode zone 45 and forms one of the intermediate anode teeth 69. N-1 active anode teeth 65 on N does not extend into the intermediate anode zone 45 (figure 4). N is an integer between 2 and 4.
[0214] Typically, N is 2. In this case, as seen in Figure 4, each active anode tooth 65 which extends into the intermediate anode zone 45 is framed by two active anode teeth 65 which do not extend into the intermediate anode zone 45.
[0215] Thus, there are approximately half as many teeth in the intermediate anode zone 45 as in the active anode zone 39.
[0216] Each intermediate anode channel 47 therefore has a transverse width corresponding substantially to the cumulative transverse widths of two active anode channels 41 and one active anode tooth 65.
[0217] The situation is the same for cathode teeth.
[0218] An active cathode tooth 67 on N' extends into the intermediate cathode area 59 and forms one of the intermediate cathode teeth 71. N'-1 active cathode teeth 67 on N' do not extend into the intermediate cathode area 59. N' is an integer between 2 and 4.
[0219] Typically, N' is 2. In this case, each active cathode tooth 67 which extends into the intermediate cathode zone 59 is framed by two active cathode teeth 67 which do not extend into the intermediate cathode zone 59.
[0220] The intermediate cathode zone 59 thus has approximately half as many teeth as the active zone.
[0221] Each intermediate cathode channel 61 therefore has a transverse width corresponding substantially to the cumulative widths of two active cathode channels 55 and one active cathode tooth 67.
[0222] The above description relates to the arrangement of the overlap zone 23 and the intermediate anode zone 45 and the intermediate cathode zone 59. Advantageously, the other overlap zone 23' and the other intermediate anode zone 45' and the other intermediate cathode zone 59' are arranged in the same way.
[0223] The other intermediate anode zone 45' has intermediate anode channels and intermediate anode teeth identical to those of the intermediate anode zone 45.
[0224] The other intermediate cathode area 59' has intermediate cathode channels and intermediate cathode teeth identical to those of the intermediate cathode area 59. The other overlap area 23' has a wavy cross-section, identical to that of the overlap area 23.
Claims
CLAIMS 1. Electrochemical cell (5) comprising: - a membrane-electrode assembly (8) comprising a membrane (9), anodic and cathodic catalytic layers (10, 10') arranged on two large opposite faces of the membrane (9) and two gas diffusion layers (11) arranged on the anodic and cathodic catalytic layers (10, 10'); - a frame (19), internally delimiting a window (20) in which the membrane-electrode assembly (8) is fixed, the window (20) having an edge (21); - an anode separator plate (15) and a cathode separator plate (17) pressed against the two gas diffusion layers (11); the anode separator plate (15) comprising at least: a first anode opening (27a) for the passage of an anode fluid, a second anode opening (29a) for the passage of a cathode fluid, - an active anodic zone (39) comprising anodic channels (41) for circulation of the anodic fluid and an anodic homogenization zone (43) fluidically connecting the first anodic opening (27a) to the anodic channels (41) of the active anodic zone (39); the cathodic separator plate (17) comprising at least: - a first cathodic opening (27c) for the passage of the anodic fluid, - a second cathode opening (29c) for the passage of the cathode fluid, - an active cathodic zone (53) comprising cathodic channels (55) for circulating the cathodic fluid and a cathodic homogenization zone (57) fluidically connecting the second cathodic opening (29c) to the cathodic channels (55) of the active cathodic zone (53), the first cathodic opening (27c) being superimposed on the first anodic opening (27a), the second cathodic opening (29c) being superimposed on the second anode opening (29a); the anode separator plate (15) comprising, between the anode homogenization zone (43) and the active anode zone (39), an intermediate anode zone (45) with intermediate anode channels (47) fluidly connecting the anode homogenization zone (43) to the anode channels (41), these intermediate anode channels (47) being delimited between intermediate anode teeth (69) juxtaposed transversely; the cathode separator plate (17) comprising, between the cathode homogenization zone (57) and the active cathode zone (53), an intermediate cathode zone (59) with intermediate cathode channels (61) fluidly connecting the cathode homogenization zone (57) to the cathode channels (55), these intermediate cathode channels (61) being delimited by intermediate cathode teeth (71) juxtaposed transversely;the edge (21) of the frame (19) being interposed between the membrane (9) and at least one of the gas diffusion layers (11), between the intermediate anodic zone (45) and the intermediate cathodic zone (59), and not between the active anodic zone (39) and the active cathodic zone (53); characterized in that the intermediate anodic teeth (69) and the intermediate cathodic teeth (71) are offset transversely relative to each other, such that each intermediate anodic tooth (69) faces an intermediate cathodic channel (61) and each intermediate cathodic tooth (71) faces an intermediate anodic channel (47).; 2. Electrochemical cell according to claim 1, in which the membrane-electrode assembly (8) has a transversely corrugated section between the intermediate anodic zone (45) and the intermediate cathodic zone (59).
3. An electrochemical cell according to claim 2, wherein said corrugated section alternately comprises anodic bumps (85) bulging towards the anodic separator plate (15) and bulging cathodic bumps (87) towards the cathodic separator plate (17), each anodic bump (85) being located between an intermediate cathodic tooth (71) and an intermediate anodic channel (47), and each bump cathode (87) being located between an intermediate anodic tooth (69) and an intermediate cathodic channel (61).
4. Electrochemical cell according to any one of claims 1 to 5. 3, in which the membrane-electrode assembly (8) has, in the absence of compression, a first thickness (e1), the membrane-electrode assembly (8) and the edge (21) together having, in the absence of compression, a second thickness (e2) greater than the first.
5. Electrochemical cell according to any one of claims 1 to 5. 4, in which the anodic channels (41) of the active anodic zone (39) are delimited between active anodic teeth (65) juxtaposed transversely and having a first anodic altitude (h 1 ), and the cathodic channels (55) of the active cathodic zone (53) are delimited between active cathodic teeth (67) juxtaposed transversely and having a first cathodic altitude (hT).
6. Electrochemical cell according to claim 5, in which the intermediate anode teeth (69) have a second anode altitude (h2) substantially equal to the first anode altitude (h1), and / or the intermediate cathode teeth (71) have a second cathode altitude (h2') substantially equal to the first cathode altitude (hT).
7. Electrochemical cell according to claim 5 or 6, in which: - one active anodic tooth (65) out of N extends into the intermediate anodic zone (45) and forms one of the intermediate anodic teeth (69), N-1 active anodic teeth (65) out of N not extending into the intermediate anodic zone (45), N being an integer between 2 and 4; and / or - an active cathode tooth (67) on N' extends into the intermediate cathode zone (59) and forms one of the intermediate cathode teeth (71), N'-1 active cathode teeth (67) on N' not extending into the intermediate cathode zone (71), N' being an integer between 2 and 4.
8. Electrochemical cell according to any one of the preceding claims, in which the intermediate anode teeth (69) and the intermediate cathode teeth (71) are parallel to each other.
9. Electrochemical cell according to any one of the preceding claims, in which the intermediate anode teeth (69) and the intermediate cathode teeth (71) are rectilinear.
10. Electrochemical cell according to any one of the preceding claims, in which the intermediate cathode zone (59) extends transversely over the entire width of the active cathode zone (53), and / or the zone intermediate anode (45) extends transversely across the entire width of the active anode zone (39).
11. Electrochemical cell according to any one of the preceding claims in which the intermediate anode teeth (69) transversely have a first anode width (11) and the intermediate cathode channels (61) transversely have a first cathode width (IT) greater than the first anode width (11); 12. Electrochemical cell according to any one of the preceding claims in which the intermediate cathode teeth (71) transversely have a second cathode width (I2') and the intermediate anodic channels (47) transversely have a second anodic width (I2) greater than the second cathodic width (I2'); 13. Electrochemical device comprising a stack of cells, each cell being according to one of the preceding claims.
14. Device according to the preceding claim, in which the electrochemical device (1) is a fuel cell.