Separator plate, electrochemical cell and electrochemical device
The separator plate design with active teeth, homogenization zones, and buffer volumes addresses the challenge of uniform fluid distribution in electrochemical devices, optimizing surface area utilization and preventing over-compression, thereby improving device performance.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- SYMBIO FRANCE
- Filing Date
- 2023-12-28
- Publication Date
- 2026-04-10
AI Technical Summary
Existing electrochemical devices face challenges in achieving uniform distribution of reactive fluids across the active zones of electrochemical cells, leading to inefficient use of the entire surface area and potential over-compression issues during cell stacking.
The introduction of a separator plate design with active teeth, homogenization zones, and buffer volumes that facilitate uniform fluid distribution by connecting openings to active channels, using intermediate zones and teeth to balance fluid flow, and accommodate the thickness of gas diffusion layers, thereby avoiding over-compression.
This design ensures homogeneous fluid distribution, optimizing the use of the entire surface area and preventing over-compression, enhancing the performance and efficiency of electrochemical devices.
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Abstract
Description
Title of the invention: Separating plate, electrochemical cell and electrochemical device
[0001] The invention relates generally to an electrochemical device, in particular a fuel cell, more particularly an electrochemical cell, or a separator plate intended to be used in said electrochemical device.
[0002] This electrochemical device is of the type comprising a plurality of electrochemical cells stacked along a stacking direction.
[0003] Each electrochemical cell comprises:
[0004] - a membrane-electrode assembly (MEA) comprising a membrane, catalytic layers arranged on two large opposite faces of the membrane, and two gaseous diffusion layers arranged on the catalytic layers;
[0005] - a frame, internally delimiting a window in which the assembly membrane-electrode is fixed;
[0006] - two separating plates pressed against the two gaseous diffusion layers.
[0007] The separating plates have openings for the circulation of the reactive fluids. Each plate also has an active zone opposite the window, comprising longitudinal channels for the circulation of one of the reactive fluids.
[0008] The separating plate has at its two opposite longitudinal ends homogenization zones putting into fluidic communication the channels of the active zone with the circulation openings of said reactive fluid.
[0009] The homogenization zones allow the reactive 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 FAME.
[0011] In this context, the invention aims to provide an electrochemical device with separating plates allowing a particularly uniform fluid distribution.
[0012] To this end, the invention relates, according to a first aspect, to a separator plate for forming an electrochemical cell of an electrochemical device such as a fuel cell, the separator plate comprising:
[0013] - an opening for the passage of a reactive fluid;
[0014] - an active zone comprising active teeth delimiting active channels between them longitudinal circulation of the reactive fluid, the active teeth having vertices that fall within a reference plane;
[0015] - a homogenization zone fluidly connecting said opening to the channels active zone assets;
[0016] - an intermediate zone interposed longitudinally between the active zone and the zone homogenization, fluidly connecting the homogenization zone to the active channels;
[0017] the separating plate having in the homogenization zone a homogenization background located at a first altitude relative to the reference plane;
[0018] the separating plate having in the intermediate zone an intermediate bottom located with respect to the reference plane at a second altitude higher than the first altitude, the intermediate bottom being separated from the homogenization bottom by a step;
[0019] at least part of the active teeth having proximal ends defining a line of separation between the active zone and the intermediate zone;
[0020] a buffer volume being delimited between the intermediate bottom, the step and the separation line, and allowing to balance the distribution of the reactive fluid arriving from the homogenization zone in the active channels.
[0021] Because there is a buffer volume between the ends of the active teeth and the step, the reactive gas arriving from the homogenization zone can easily distribute itself into the active channels.
[0022] In particular, it can disperse transversely in this buffer volume, which allows the distribution of the reactive fluid to be balanced between the active channels.
[0023] The reactive gas flow then undergoes a significant pressure drop front, created by the gas diffusion layer, which also contributes to distributing the reactive gas transversely.
[0024] In addition, the presence of the buffer volume, and in particular its height, advantageously accommodates the extra thickness traditionally formed by the gas diffusion layer and the frame, thus avoiding over-compression problems during the stacking and compression of the cells.
[0025] The separating plate may also have one or more of the following characteristics, considered individually or in all technically possible combinations:
[0026] - the active zone presents longitudinally an active length, the separation line being separated longitudinally from the step by a longitudinal gap of between 2% and 20% of the active length;
[0027] - the intermediate zone comprises intermediate canals and teeth intermediates projecting towards the reference plane relative to the intermediate background, the intermediate teeth delimiting the intermediate canals between them;
[0028] - the intermediate teeth extend longitudinally along the entire length of the intermediate zone, from the separation line to the step;
[0029] - the intermediate teeth extend longitudinally at least part of the teeth active beyond the separation line;
[0030] - the active zone has a first number of active channels, the intermediate zone presenting a second intermediate number of channels different from the first number, preferably less than the first number, advantageously between 25 and 75% of the first number;
[0031] - the separating plate has in the active zone an active background located at the second altitude relative to the reference plane, with the active teeth protruding towards the reference plane relative to the active background;
[0032] - the intermediate teeth protrude towards the reference plane relative to the bottom intermediate on a first height, the active teeth protruding towards the reference plane relative to the active bottom on a second height equal to the first height;
[0033] - a difference between the second altitude and the first altitude 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.
[0034] According to a second aspect, the invention relates to an electrochemical cell for an electrochemical device such as a fuel cell, the electrochemical cell comprising:
[0035] - a membrane-electrode assembly comprising a membrane, layers catalytic layers arranged on two large opposite faces of the membrane and two gaseous diffusion layers arranged on the catalytic layers;
[0036] - a frame, internally delimiting a window in which the assembly membrane-electrode is fixed;
[0037] - two separating plates pressed against the two gaseous diffusion layers, at least one of the separating plates being as defined above, the active area of the or each separating plate being located opposite the window, the homogenization area of the or each separating plate being located opposite the frame.
[0038] The electrochemical cell may further exhibit one or more of the following characteristics, considered individually or in all technically possible combinations:
[0039] - the gaseous diffusion layer plated against said at least one plate the separator ends longitudinally towards the homogenization zone with an edge, the edge being separated longitudinally from the step by a longitudinal gap of between 2% and 20% of the active length;
[0040] - the homogenization zone presents, at the step (59), a first passage cross-section for the reactive fluid taken perpendicular to the longitudinal direction; the buffer volume having, between said edge and the step, a second passage section for the reactive fluid taken perpendicular to the longitudinal direction, between the first passage section + 20% and the first passage section + 80%, preferably substantially equal to the first passage section + 60%;
[0041] - the intermediate teeth having vertices located at a distance from the frame
[0042] - the gaseous diffusion layer extends longitudinally beyond the window and covers an edge area of the frame, the edge of the gaseous diffusion layer being located opposite the intermediate area.
[0043] The invention relates according to a third aspect to an electrochemical device, comprising a plurality of electrochemical cells stacked along a stacking direction, each electrochemical cell having the above characteristics.
[0044] The invention will become clearer upon reading the following description, given solely by way of non-limiting example, and made with reference to the drawings in which: - [Fig.1] The [Fig.1] is a perspective view of an electrochemical device; - [Fig. 2] [Fig. 2] is an exploded view of an electrochemical cell of the device of [Fig.1], considered in perspective;
[0045] - [Fig.3] [Fig.3] is a schematic longitudinal sectional view of the cell electrochemical image of [Fig. 2], showing in particular the intermediate zones of the separating plates; and
[0046] - [Fig.4] [Fig.4] is an enlarged perspective view of a detail of the area intermediate of the cathode ray separator plate of figures 2 and 3.
[0047] The electrochemical device 1 shown in [Fig.1] is typically a fuel cell.
[0048] Alternatively, it is an electrolyzer or any other corresponding type of electrochemical device.
[0049] This electrochemical device comprises a stack of 3 electrochemical cells.
[0050] The electrochemical cells 5 are stacked along a stacking direction E, one on top of the other.
[0051] The electrochemical device 1 further comprises two end plates 7, arranged on either side of the stack 3.
[0052] The electrochemical cells 5 of the stack are pressed against each other between the two end plates 7.
[0053] Each electrochemical cell 5 comprises, as illustrated in Figures 2 and 3, a membrane-electrode assembly 8 (MEA).
[0054] The AME 8 comprises a membrane 9, catalytic layers 10 arranged on two large opposite faces of the membrane 9 and two gas diffusion layers 11 arranged on the catalytic layers 10.
[0055] Thus the membrane 8 is intercalated between two catalytic layers 10, themselves intercalated between two gaseous diffusion layers 11.
[0056] Each electrochemical cell 5 also includes two separating plates 15, 17 pressed against the two gaseous diffusion layers 11.
[0057] More specifically, a first separating plate 15 is in contact with a first gaseous diffusion layer 11 and a second separating plate 17 is in contact with a second gaseous diffusion layer 11. In other words, the two separating plates 15,17 sandwich the two gaseous diffusion layers 11 which themselves sandwich the membrane-electrode assembly.
[0058] The two separating plates 15, 17 are arranged on two opposite sides of the membrane-electrode assembly 8.
[0059] The two gas diffusion layers 11 (GDL, i.e. Gas Diffusion Layer in English) are interposed each between one of the separating plates 15, 17 and one of the catalytic layers 10.
[0060] One of the catalytic layers 10 constitutes an anode and is called the anodic catalytic layer. The separating plate located on the same side of the membrane 9, and separated from the anodic catalytic layer 10 by one of the GDLs, is called the anodic separating plate 15.
[0061] The other catalytic layer 10 constitutes a cathode and is called the cathodic catalytic layer. The separating plate located on the same side of the membrane 9, and separated from the cathodic catalytic layer by the other GDL, is called the cathodic separating plate 17.
[0062] When several cells 3 are stacked one on top of the other, the anodic separating plate 15 of a given cell is placed against the cathodic separating plate 17 of the neighboring cell, with an interposed sealing device, for example a gasket or a weld. 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.
[0063] Membrane 9 is typically a proton exchange polymer membrane.
[0064] The proton exchange membrane is for example made of a sulfonated perfluorinated polymer material, such as the material known under the trade name "Nafion".
[0065] The anodic and cathodic catalytic layers 10 are typically made up of porous structures, which allow the transport of reactive fluids, i.e. hydrogen and oxygen, into the catalytic layers.
[0066] These layers are typically formed of three different materials, namely:
[0067] - a material for transporting protons, for example the same material as the proton exchange membrane, such as the "Nafion" material mentioned above,
[0068] - a material for transporting electrons, for example carbon, and
[0069] - a material for catalyzing electrochemical oxidation and reactions reduction, for example of platinum.
[0070] The reactive fluids are an anodic fluid and a cathodic fluid.
[0071] The anodic fluid is typically dihydrogen.
[0072] The cathode fluid is typically air or dioxygen.
[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, with the catalytic anodic and cathodic layers interposed.
[0074] When the fuel cell 1 is operating, an oxidation reaction occurs in 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 to the cathodic catalytic layer, while the electrons are conducted through the gaseous diffusion layer to the anodic separator plate and then to the cathodic separator plate. At the same time, a reduction reaction occurs in the cathodic catalytic layer. This reaction consists of reacting the oxygen supplied by the anodic fluid with the protons passing through the proton exchange membrane, as well as with the electrons supplied by the cathodic separator plate of the cell in question, thus forming water molecules.
[0075] Each cell 5 also includes a frame 19, internally delimiting a window 20 in which the AME 8 is fixed.
[0076] The frame 19 has an edge area 21 delimiting the window 20.
[0077] The edge area 21 has a closed contour.
[0078] Window 20 is preferably rectangular.
[0079] The frame 19 is typically formed of two layers 22 of a polymer film, for example of polyethylene naphthalate or terephthalate (PEN or PET).
[0080] 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.
[0081] In the example shown, frame 19 is generally rectangular in shape.
[0082] The AME 8 is substantially flat, and extends in the same plane as the frame 19.
[0083] The AME 8 has, at its two opposite longitudinal ends, two edges called overlap zones 23.
[0084] The overlap zones 23 extend transversely over the entire width of the AME 8.
[0085] In the example shown, the AME 8 is rectangular. The overlap areas 23 are straight and transverse strips.
[0086] As can be seen in [Fig.3], in each overlap zone 23, the edge zone 21 is interposed between the membrane 9 and at least one of the gas diffusion layers 11.
[0087] This allows the membrane 9 to be maintained and ensures a seal between the two faces of the membrane.
[0088] In each overlap zone 23, the two polymer film layers 22 constituting the edge zone 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.
[0089] According to an alternative not shown, one of the two polymer film layers 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 polymer film layer 22 does not extend between the membrane 9 and the gas diffusion layers 11. It stops before covering the membrane 9.
[0090] According to another variant not shown, the frame 19 consists of a single layer of polymer film. The portion 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
[0091] The overlap zones 23 extend over a fraction of the longitudinal length of the AME 8. For example, the edge zone 21 covers the membrane 9 longitudinally over a length of between 0.5 and 8 mm in each overlap zone.
[0092] The gas diffusion layers 11 cover all the large faces of the membrane 9.
[0093] In particular, the gaseous diffusion layers 11 cover the overlap areas 23 of FAME 8.
[0094] This ensures that there is no area of the membrane not covered by the gas diffusion layer and possibly to fix the gas diffusion layer to the frame 19 by different bonding techniques.
[0095] The gaseous diffusion layers 11 terminate longitudinally with edges 25.
[0096] The edges 25 are transverse.
[0097] In the example illustrated in [Fig.3], the edges 25 are located longitudinally immediately beyond the overlap area 23.
[0098] Alternatively, the edges 25 are offset from the overlap zone 23, each GDL 11 covering a strip of the frame 19 adjoining this overlap zone 23.
[0099] According to yet another variant, the gas diffusion layers 11 are longitudinally shorter than the membrane 9, and only partially cover the overlap areas 23 of the AME 8. They only partially cover the edge area 21.
[0100] The separating plates 15, 17 each extend substantially in a longitudinal and transverse plane, each being perpendicular to the stacking direction E. They are typically metallic.
[0101] The separating plates 15, 17 are generally rectangular in shape.
[0102] They are typically obtained by stamping, machining or any other manufacturing method.
[0103] The anodic separator plate 15, as seen in [Fig.2], has at least a first anodic opening 27a for the passage of the anodic fluid and a second anodic opening 29a for the passage of the cathodic fluid.
[0104] The anodic separator plate 15 further has third, fourth, fifth and sixth anodic openings 31a, 33a, 35a, 37a.
[0105] Openings 31a and 33a are provided for the circulation of the anodic fluid and cathodic fluid respectively.
[0106] For example, the opening 27a allows the anodic fluid to be supplied and the opening 31a is provided for the evacuation of the anodic fluid.
[0107] Preferably, the openings 33a and 29a are provided respectively for the supply of cathodic fluid and for the evacuation of cathodic fluid.
[0108] Openings 35a and 37a are provided for the circulation of the heat transfer fluid. For example, opening 35a is provided for the supply of the heat transfer fluid and opening 37a for the discharge of the heat transfer fluid.
[0109] The openings 27a and 31a are diagonally opposite in the anodic separator plate 15. Similarly, the openings 29a and 33a are diagonally opposite.
[0110] The openings 27a, 35a and 29a are placed at one longitudinal end of the plate 15. They are aligned transversely, in that order.
[0111] The openings 31a, 37a and 33a are placed at the opposite longitudinal end of the plate 15. They are aligned transversely, in that order.
[0112] Similarly, the cathodic separator plate 17 has at least a first cathodic opening 27c for the passage of the anodic fluid and a second cathodic opening 29c for the passage of the cathodic fluid.
[0113] The cathode separating plate 17 also has third, fourth, fifth and sixth cathode openings 31c, 33c, 35c, 37c.
[0114] Openings 31c and 33c are provided for the circulation of the anodic fluid and cathodic fluid respectively.
[0115] For example, the opening 27c allows the anodic fluid to be supplied and the opening 31c is provided for the evacuation of the anodic fluid.
[0116] Preferably, the openings 33c and 29c are provided respectively for the supply of cathodic fluid and for the evacuation of cathodic fluid.
[0117] 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.
[0118] The openings 27c and 31c are diagonally opposite in the cathode separating plate 17. Similarly, the openings 29c and 33c are diagonally opposite.
[0119] The openings 27c, 35c and 29c are placed at one longitudinal end of the plate 17. They are aligned transversely, in that order.
[0120] The openings 31c, 37c and 33c are placed at the opposite longitudinal end of the plate 17. They are aligned transversely, in that order.
[0121] The frame 19 includes 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.
[0122] Frame 19 also presents third, fourth, fifth and sixth intermediate openings 31b, 33b, 35b, 37b.
[0123] Openings 31b and 33b are provided for the circulation of the anodic fluid and cathodic fluid respectively.
[0124] For example, the opening 27b allows the anodic fluid to be supplied and the opening 31b is provided for the evacuation of the anodic fluid.
[0125] Openings 33b and 29b are provided respectively for the supply of cathodic fluid and for the evacuation of cathodic fluid.
[0126] 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.
[0127] Openings 27b and 31b are diagonally opposite in frame 19. Similarly, openings 29b and 33b are diagonally opposite.
[0128] The openings 27b, 35b and 29b are placed at one longitudinal end of the frame 19. They are aligned transversely, in that order.
[0129] The openings 31b, 37b and 33b are placed at the opposite longitudinal end of the frame 19. They are aligned transversely, in that order.
[0130] As can be seen in [Fig.2], the openings 27a / 27b / 27c are coincident and together constitute a portion of the anodic fluid supply manifold.
[0131] Similarly, the openings 29a / 29b / 29c are coincident and together constitute a portion of the cathode fluid evacuation manifold.
[0132] The openings 31a / 31b / 31c are coincident and together constitute a portion of the anodic fluid evacuation collector.
[0133] The openings 33a / 33b / 33c are coincident and together constitute a portion of a cathode fluid supply manifold.
[0134] The openings 35a / 35b / 35c are coincident and together constitute a portion of a heat transfer fluid supply manifold.
[0135] The openings 37a / 37b / 37c are coincident and together constitute a portion of the heat transfer fluid evacuation manifold.
[0136] Joints (unreferenced dashed lines on [Fig.2]) are placed around these openings and are interposed between the anodic separating plate 15, the frame 19 and the cathodic separating plate 17.
[0137] According to the invention, at least one of the separating plates of cell 5 comprises:
[0138] - an active zone 39 comprising active teeth 71 delimiting between them 41 longitudinal active channels for the circulation of a reactive fluid;
[0139] - a homogenization zone 43 fluidly connecting one of the openings of the separator plate for active channels 41 from active zone 39;
[0140] - an intermediate zone 45 interposed longitudinally between the active zone 39 and the homogenization zone 43, fluidly connecting the homogenization zone 43 to the active channels 4L
[0141] By "fluidically connecting" it is preferably understood that the areas 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, but not limited to, a channel, a groove, a slot, etc. It is then understood that the sealing of the fluidic connection is achieved by an added part on the separating plate, such as another separating plate.
[0142] If the separator plate is of the anodic type, the homogenization zone 43 fluidly connects the anodic fluid supply opening 27a to the active channels 4L
[0143] If the separator plate is of the cathodic type, the homogenization zone 43 connects the cathodic fluid supply opening 29c to the active channels 4L
[0144] The active area 39 is located opposite window 20.
[0145] The active zone 39, longitudinally, is located entirely opposite the membrane 9.
[0146] The homogenization zone 43 is located opposite frame 19.
[0147] The homogenization zone 43 is located opposite a flat zone 49 of the frame.
[0148] The intermediate zone 45 is located opposite the edge zone 21 of the frame 19. It extends longitudinally beyond the edge zone 21, up to the homogenization zone 43. On the opposite side of the homogenization zone 43, it stops at the level of the window 20, or extends slightly inside the window 20.
[0149] The active channels 41 are straight and longitudinal. Alternatively, they extend in a general longitudinal direction, forming undulations on either side of this general longitudinal direction.
[0150] The active teeth 71 have respective proximal ends 72 defining a separation line LS between the active zone 41 and the intermediate zone 45.
[0151] This separation line LS is, for example, transverse, as shown in [Fig. 4]. Alternatively, it is oblique to the transverse direction. The separation line LS is typically a straight line.
[0152] The active teeth 71 have vertices 73 inscribed in a reference plane P, as illustrated in [Fig.3].
[0153] The reference plane P is parallel to the plane in which the frame 19 extends.
[0154] As illustrated in [Fig.3], the separating plate has in the homogenization zone 43 a homogenization background 51 located at a first altitude al relative to the reference plane P.
[0155] The homogenization background 51 is a region of the separating plate, extending along a plane preferably substantially perpendicular to the stacking direction E, i.e. parallel to the reference plane P. The altitude al is taken along the stacking direction E. It corresponds to the separation between the homogenization background 51 and the plane P.
[0156] The separating plate advantageously presents in the homogenization zone 43 also reliefs 53 projecting towards the reference plane P relative to the homogenization background 51.
[0157] The reliefs 53 are provided to direct the flow of the reactive gas stream from the opening to the intermediate zone 45.
[0158] These reliefs 53 can have all sorts of shapes. For example, they are teeth spaced apart from each other and delimiting continuous or discontinuous channels between them. Alternatively, they are circular, triangular or any other shaped bumps.
[0159] The separating plate has in the intermediate zone 45 an intermediate bottom 55 located with respect to the reference plane P at a second altitude a2 higher than the first altitude al.
[0160] The intermediate zone 45 preferentially comprises intermediate channels 47 and intermediate teeth 57 projecting towards the reference plane P relative to the intermediate background 55. The intermediate teeth 57 delimit the intermediate channels 47 to each other.
[0161] The intermediate base 55 is formed by one or more regions of the separator plate. These regions lie in the same plane perpendicular to the stacking direction E (i.e., parallel to the reference plane P). For example, these regions are substantially flat (see [Fig. 4]). This notably simplifies the manufacture of the separator plate.
[0162] 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 along the stacking direction E.
[0163] The intermediate bottom 55 defines the bottom of the intermediate channels 47.
[0164] As can be seen in [Fig. 3], the intermediate bottom 55 is separated from the bottom homogenization 51 by a step 59.
[0165] This step 59 results from the difference in altitude between the homogenization base 51 and the intermediate base 55, and can take any shape allowing the homogenization base 51 and the intermediate base 55 to be connected continuously. Preferably, as illustrated in [Fig.3], the step can have a step nose that is straight (i.e. rectilinear) oriented at an angle to the stacking direction, i.e. oriented along a direction secant to the reference plane P. Alternatively, one could imagine, without departing from the scope of the invention, a step nose that is oriented perpendicular to the reference plane P. One could also imagine a non-rectilinear step nose, for example, one that is rounded.
[0166] This step, whatever its shape and orientation, thus makes it possible to constitute a boundary, an obstacle, a wall for the fluid.
[0167] The difference between the second altitude a2 and the first altitude al 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 an anode or cathode type polar plate.
[0168] Preferably, the intermediate background 55 is located at an altitude a2 between 0.1 mm and 0.5 mm, advantageously between 0.2 and 0.3 mm, for example by being substantially equal to one of these latter limits, the latter preferentially relating respectively to an anodic polar plate or a cathodic polar plate.
[0169] Preferably, the homogenization background 51 is located at an altitude al between 0.05 mm and 0.3 mm, advantageously between 0.1 and 0.2 mm, for example by being approximately equal to 0.12 mm and 0.14 mm, the latter preferentially relating respectively to an anodic polar plate or a cathodic polar plate.
[0170] As can be seen in [Fig.4], this step 59 is preferentially substantially transverse, and extends over the entire transverse width of the homogenization zone 43. It is formed in the separating plate.
[0171] A buffer volume 60 is thus delimited between the intermediate bottom 55, the step 59 and the separation line LS, thus allowing the distribution of the reactive fluid arriving from the homogenization zone 43 to be balanced in the active channels 41.
[0172] The active zone 41 has a determined active length LA longitudinally.
[0173] The separation line LS is separated longitudinally from step 59 by a The longitudinal spacing is advantageously between 2% and 20% of the active length LA. Preferably, the longitudinal spacing is between 4% and 15%, and even more preferably between 5% and 10% of the active length LA. This longitudinal spacing corresponds to the longitudinal length of the buffer volume 60.
[0174] The edge 25 of the GDL is separated longitudinally from the step 59 by a longitudinal gap advantageously between 2% and 20% of the active length (LA). Preferably, the longitudinal gap is between 4% and 15%, and even more preferably between 5% and 10% of the active length LA.
[0175] Furthermore, the homogenization zone 43 has, at the step 59, a first passage section PI for the reactive gas. This passage section PI is taken perpendicular to the longitudinal direction.
[0176] The passage section is taken at the top of step 59, i.e. at the boundary between the homogenization bottom 51 and step 59.
[0177] The first passage section PI corresponds to the free section offered to the reactive fluid flowing from the homogenization zone 43 into the intermediate zone 45. The first section corresponds to the section delimited between the homogenization bottom 51 and the frame 19, less the section possibly occupied by the reliefs formed at the step 59. As described below, in the example shown, the intermediate teeth 57 extend to the step 59, the ends of the intermediate teeth reducing the first passage section PL
[0178] The buffer volume 60 has, between the edge 25 and the step 59, a second passage section P2 for the reactive fluid, advantageously located between the first passage section PI plus 20% and the first passage section PI plus 80%, preferably between the first passage section PI plus 40% and the first passage section PI plus 70%, typically substantially equal to the first passage section PI plus 60%. The second passage section P2 is taken perpendicular to the longitudinal direction L.
[0179] The condition stated above is verified for all sections of the buffer volume 60 located between the step 59 and the edge 25. In other words, the passage section of the buffer volume 60 is preferentially substantially constant from the step 59 to the edge 25 of the GDL.
[0180] The passage section corresponds to the free section offered to the reactive fluid to circulate longitudinally in the buffer volume 60. It thus corresponds to the section delimited between the intermediate bottom 55 and the frame 19, less the section occupied by the intermediate teeth 57.
[0181] The intermediate teeth 57 have vertices 61 designed to be located at a distance from the frame 19.
[0182] This distance is taken along the stacking direction E.
[0183] Each intermediate tooth 57 has a first segment 63 intended to be pressed against the GDL 11, and a second free segment 65, extending longitudinally from the first segment 63. The first segment 63 adjoins the active zone 39. The second segment 65 is intended to be located longitudinally beyond the edge 25 of the GDL.
[0184] Preferably, each intermediate tooth 57 also has a third segment 67, formed on the step 59, and extending slightly inside the homogenization zone 43. In this case, the third segment 67 reduces the first passage section PL
[0185] In other words, the intermediate teeth 57 extend longitudinally along the entire length of the intermediate zone 45, up to the step 59, or even beyond the step 59.
[0186] The reactive fluid can therefore circulate transversely between the apexes 61 of the intermediate teeth 57 and the frame 19 at the level of the second segments 65.
[0187] As can be seen in particular in figures 3 and 4, the separating plate has, in the active zone 39, an active bottom 69 located preferably at the second altitude a2 relative to the reference plane P, the active teeth 71 protruding towards the reference plane P relative to the active bottom 69. The altitude of the active bottom 69 is taken along the stacking direction E, that is to say perpendicular to the reference plane P.
[0188] The active bottom 69 consists of regions of the separating plate inscribed in the same plane substantially perpendicular to the stacking direction E. This plane is preferably located at the same altitude a2 as the intermediate bottom 55. This makes it possible in particular to simplify the manufacture of the separating plate.
[0189] These regions are separated from each other by the active teeth 71 and delimit the bottom of the active canals 4L
[0190] In other words, the intermediate bottom 55 and the active bottom 69 are preferentially inscribed in the same plane perpendicular to the stacking direction E, located at altitude a2 relative to the reference plane P.
[0191] The vertices 73 of the active teeth are located in contact with the GDL 11 when the cell is assembled.
[0192] The intermediate teeth 57 project towards the reference plane P relative to the intermediate bottom 57 over a first height hl. The active teeth 71 project towards the reference plane P relative to the active bottom 69 over a second height h2, preferably equal to the first height hl.
[0193] In other words, the intermediate teeth 57 and the active teeth 71 preferentially have the same height.
[0194] The intermediate teeth 57, as seen in particular on [Fig.4], extend longitudinally at least part of the active teeth 71.
[0195] For example, the active zone 39 has a first number of active channels 41, the intermediate zone 45 has a second number of intermediate channels 47 between 25 and 75% of the first number.
[0196] In other words, the number of intermediate canals 47 is less than the number of active canals 4L. Consequently, the number of intermediate teeth 57 is less than the number of active teeth 71.
[0197] In the example shown in [Fig. 4], the number of intermediate teeth 57 is approximately 50% of the number of active teeth 71. One out of every two active teeth 71 is extended by an intermediate tooth 57. One out of every two active teeth 71 is not extended by an intermediate tooth 57 and stops at the boundary separating the active zone 39 from the intermediate zone 45. Each active tooth 71 extended by an intermediate tooth 57 is framed by two active teeth 71 that are not extended by intermediate teeth 57.
[0198] This difference in the number of intermediate teeth 57 and active teeth 71 is advantageously studied in design in order to optimize the fluidic distribution between the intermediate zone and the active zone while minimizing the loss of useful cross-section for the passage of the fluid.
[0199] Thus, the intermediate canals 47 have a width much greater than the active canals 4L. This width, for example, corresponds transversely to the cumulative width of two active canals and one active tooth.
[0200] Such an arrangement is used for example for anodic and / or cathodic type separator plates.
[0201] According to another variant not shown, the number of active channels 41 is equal to the number of intermediate channels 47.
[0202] Consequently, the number of active teeth 71 is substantially equal to the number of intermediate teeth 57. Each active tooth 71 is extended longitudinally by an intermediate tooth 57.
[0203] The separating plate, the electrochemical cell and the electrochemical device described above have multiple advantages.
[0204] The fact that the edge of the gas diffusion layer is also separated longitudinally from the step by a significant longitudinal gap helps to facilitate the distribution of the reactive gas exiting the homogenization zone into the active channels.
[0205] The passage cross-section for the reactive gas between the homogenization zone and the edge of the gas diffusion layer is also particularly large, which also helps to facilitate the distribution of the reactive gas in the active channels.
[0206] Because the intermediate teeth have apexes located away from the frame, the reactive fluid from the homogenization zone can easily flow transversely into the intermediate zone and distribute itself into the different active channels.
[0207] The fact that the separating plate preferentially presents an active bottom in the active zone located at the second altitude relative to the reference plane, i.e., that the bottoms of the active zone and the intermediate zone are preferentially located at the same altitude, makes it possible to create a significant volume in the intermediate zone to distribute the reactive fluid. This volume acts as a collector or buffer zone.
[0208] The fact that the intermediate teeth and the active teeth have the same height simplifies the design and manufacture of the separating plate and allows for uniform compression of the gas diffusion layer.
[0209] The separating plate, the electrochemical cell and the electrochemical device described above have multiple variants.
[0210] The electrochemical device may not be a fuel cell, but an electrolyzer or any other corresponding type of electrochemical device.
[0211] As a result, the catalytic layers are not necessarily anodic and cathodic catalytic layers of the type described above.
[0212] The homogenization zone has been described as fluidly connected to an inlet port for either an anodic reactive fluid or a cathodic reactive fluid, depending on the type of separator plate. The homogenization zone can also be connected to the outlet port for the anodic reactive fluid or to the outlet port for the cathodic reactive fluid.
[0213] It can also, depending on the type of electrochemical device, be connected to an opening for supplying or draining a fluid of another type.
[0214] The two homogenization zones and the two intermediate zones of the separating plate can be of the type described above.
[0215] Alternatively, only one of the homogenization zones and one of the intermediate zones, located on one longitudinal side of the plate, are as described below. above. The other intermediate zone and the other homogenization zone, located on the other side of the plate, are not as described above.
[0216] Preferably, the two separating plates of each electrochemical cell are as described above.
[0217] Alternatively, only one of the separating plates of the electrochemical cell is as described above, the other plate is of a different type.
[0218] Some cells may have one or two separator plates that are not of the type described above.
Claims
Demands
1. Separating plate (15, 17) for forming an electrochemical cell of an electrochemical device such as a fuel cell, the separating plate comprising: - an opening for the passage of a reactive fluid; - an active zone (39) having active teeth (71) delimiting between themselves longitudinal active channels (41) for the circulation of the reactive fluid, the active teeth (71) having vertices (73) inscribed in a reference plane (P); - a homogenizing zone (43) fluidly connecting said opening to the active channels (41) of the active zone (39); - an intermediate zone (45) interposed longitudinally between the active zone (39) and the homogenizing zone (43), fluidly connecting the homogenizing zone (43) to the active channels (41); the separating plate (15, 17) presenting in the homogenization zone (43) a homogenization background (51) located at a first altitude (al) relative to the reference plane (P);the separating plate (15, 17) having in the intermediate zone (45) an intermediate bottom (55) located relative to the reference plane (P) at a second altitude (a2) higher than the first altitude (al), the intermediate bottom (55) being separated from the homogenization bottom (51) by a step (59); at least a part of the active teeth (71) having proximal ends (72) defining a separation line (LS) between the active zone (39) and the intermediate zone (45); a buffer volume (60) being delimited between the intermediate bottom (55), the step (59) and the separation line (LS), and allowing to balance the distribution of the reactive fluid arriving from the homogenization zone (43) in the active channels (41).;
2. Separating plate (15, 17) according to claim 1, wherein the active zone (41) has longitudinally an active length (LA), the separation line (LS) being separated longitudinally from the step (59) by a longitudinal gap of between 2% and 20% of the active length (LA).
3. Separating plate (15, 17) according to claim 1 or 2, wherein the intermediate zone (45) comprises channels intermediates (47) and intermediate teeth (57) projecting towards the reference plane (P) relative to the intermediate bottom (55), the intermediate teeth (57) delimiting between themselves the intermediate canals (47).
4. Separating plate (15, 17) according to claim 3, wherein the intermediate teeth (57) extend longitudinally over the entire length of the intermediate zone (45), from the separation line (LS) to the step (59).
5. Separating plate (15, 17) according to claim 3 or 4, wherein the intermediate teeth (57) longitudinally extend at least a portion of the active teeth (71) beyond the separation line (LS).
6. Separator plate (15, 17) according to any one of claims 3 to 5, wherein the active zone (39) has a first number of active channels (41), the intermediate zone (45) has a second intermediate number of channels (47) different from the first number, preferably less than the first number, advantageously between 25 and 75% of the first number.
7. Separating plate (15, 17) according to any one of claims 1 to 6, wherein the separating plate (15, 17) has in the active zone (39) an active bottom (69) located at the second altitude (a2) relative to the reference plane (P), the active teeth (71) projecting towards the reference plane (P) relative to the active bottom (69).
8. Separating plate (15, 17) according to any one of claims 3 to 6 in combination with claim 7, wherein the intermediate teeth (57) protrude towards the reference plane (P) relative to the intermediate bottom (55) over a first height (hl), the active teeth (71) protrude towards the reference plane (P) relative to the active bottom (69) over a second height (h2) equal to the first height (hl).
9. Separator plate (15, 17) according to any one of claims 1 to 8, wherein a difference between the second altitude and the first altitude 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.
10. Electrochemical cell (5) for an electrochemical device such as a fuel cell, the electrochemical cell comprising: - a membrane-electrode assembly (8) comprising a membrane (9), catalytic layers (10) arranged on two large opposite faces of the membrane (9) and two gas diffusion layers (11) arranged on the catalytic layers (10); - a frame (19), internally delimiting a window (20) in which the membrane-electrode assembly (8) is fixed; - two separating plates (15, 17) pressed against the two gas diffusion layers (11), at least one of the separating plates being according to any one of claims 1 to 9, the active area (39) of the separating plate(s) (15, 17) being located opposite the window (20), the homogenization area (43) of the separating plate(s) (15, 17) being located opposite the frame (19).
11. Electrochemical cell (5) according to claim 10, wherein the gas diffusion layer (11) plated against said at least one separating plate (15, 17) terminates longitudinally towards the homogenization zone (43) by an edge (25), the edge (25) being separated longitudinally from the step (59) by a longitudinal gap of between 2% and 20% of the active length (LA).
12. Electrochemical cell (5) according to claim 11, wherein the homogenization zone (43) has, at the step (59), a first passage section (SI) for the reactive fluid taken perpendicular to the longitudinal direction; the buffer volume (60) having, between said edge (25) and the step (59), a second passage section (S2) for the reactive fluid taken perpendicular to the longitudinal direction, comprising between the first passage section (SI) + 20% and the first passage section (SI) + 80%, preferably substantially equal to the first passage section (SI) + 60%.
13. Electrochemical cell (5) according to any one of claims 10 to 12, wherein at least one separating plate (15, 17) is according to any one of claims 3 to 6, the intermediate teeth (57) having vertices (61) located at a distance from the frame (19).
14. Electrochemical cell (5) according to any one of claims 10 to 12, wherein the gaseous diffusion layer (11) extends longitudinally beyond the window (20) and covers an edge area (21) of the frame (20), the edge (25) of the gaseous diffusion layer (11) being located opposite the intermediate zone (45).
15. Electrochemical device, comprising a plurality of electrochemical cells (5) stacked along a stacking direction, each electrochemical cell (5) being defined according to any one of claims 10 to 14.