Electrochemical device, assembly comprising two electrochemical devices, motor vehicle and assembly method

Abstract

Electrochemical device, assembly comprising two electrochemical devices, motor vehicle and assembly method The electrochemical device (1) comprises a solid structure (5) comprising: - a plurality of electrochemical cells (7) constituting a block (9); - end plates (11) placed at the two ends of the block (9) according to the stacking direction of the cells; - mechanical connecting members (13) forcing the end plates (11) towards each other along the stacking direction (E);the electrochemical device (1) further comprising a first external collector (33), pressed against the first main face (17) of the block (9) and communicating fluidly with the circulation passages (15) of each electrochemical cell (7), the first collector (33) comprising first stops (35) cooperating with the first and / or second lateral faces (21, 23) of the block (9) and / or with the mechanical connecting members (13) and defining the position of the first external collector (33) on the first main face (17) along a transverse direction (T) perpendicular to the stacking direction (E). Figure for the abbreviation: 1;

Description

Title of the invention: Electrochemical device, assembly comprising two electrochemical devices, motor vehicle and assembly method

[0001] The invention relates generally to an electrochemical device, in particular a fuel cell, especially of the proton exchange membrane fuel cell (PEMFC) type.

[0002] Such an electrochemical device typically comprises a bulk structure including:

[0003] - a plurality of electrochemical cells, stacked one on top of the other according to a stacking direction and constituting a block, each cell presenting a passage for the circulation of a first fluid, the block having first and second principal faces substantially parallel to the stacking direction and opposite each other, the block also having first and second lateral faces substantially parallel to the stacking direction and opposite each other;

[0004] - end plates placed at both ends of the block along the direction stacking;

[0005] - mechanical connecting elements connecting the end plates one to the other and forcing the end plates towards each other along the stacking direction, the end plates pressing the electrochemical cells together.

[0006] It is possible to provide in the electrochemical device a first external collector, pressed against the first main face of the block and communicating fluidly with the circulation passages of each electrochemical cell.

[0007] Sealing problems have been observed between the first external collector and the block made up of electrochemical cells for this type of device.

[0008] These problems do not allow the use of a first fluid under pressure, for example at 2 or 3 absolute bars.

[0009] In this context, the invention aims to provide an electrochemical device that does not have the above defects.

[0010] To this end, the invention relates to an electrochemical device, comprising a bulk structure including:

[0011] - a plurality of electrochemical cells, stacked one on top of the other according to a stacking direction and constituting a block, each electrochemical cell having a passage for the circulation of a first fluid, the block having first and second principal faces substantially parallel to the stacking direction and opposite each other, the block further having first and second lateral faces substantially parallel to the stacking direction and opposite each other;

[0012] - end plates placed at both ends of the block along the direction stacking;

[0013] - mechanical connecting elements connecting the end plates one to the other and forcing the end plates towards each other along the stacking direction, the end plates pressing the electrochemical cells together;

[0014] the electrochemical device further comprising a first external collector, pressed against the first main face of the block and communicating fluidly with the circulation passages of each electrochemical cell, the first collector comprising first stops cooperating with the first and / or second lateral faces of the block and / or with the mechanical connecting members and defining the position of the first external collector on the first main face along a transverse direction perpendicular to the stacking direction.

[0015] Due to the presence of the first stops cooperating with the lateral faces of the block and / or with the mechanical connecting elements, the position of the first manifold on the first main face is well defined in the transverse direction. When the electrochemical cells are pressurized via the mechanical connecting elements, the first outer manifold does not shift transversely. Its position is well controlled. This helps to ensure a good seal between the first outer manifold and the block. It becomes possible to use a first pressurized fluid (2-3 bar, for example). Furthermore, these first stops still allow a certain axial displacement when the cells are pressurized. This allows for precise adjustment of the position of the first manifold, which also helps to ensure a good seal between the first outer manifold and the block.

[0016] Because the first stops come to rest against the lateral faces of the block or against the mechanical connecting elements, the locking in position of the first external collector is obtained in a particularly simple, reliable and inexpensive manner.

[0017] The electrochemical device may further have one or more of the following characteristics, considered individually or in all technically possible combinations:

[0018] - the first external collector has a substantially parallel flat area On the first main face, a zone, preferably convex, protruding from the flat zone opposite the first main face and delimiting a circulation volume of the first fluid, and folded edges attached to the flat area, defining the stops;

[0019] - the first stops extend in respective planes perpendicular to the area plane;

[0020] - a closed contour joint is interposed between the flat area and the first face main, the closed contour joint preferably comprising a joint portion carried by the flat area and a joint portion carried by the first main face;

[0021] - the closed contour joint comprises two main branches parallel to each other the other, extending along the stacking direction;

[0022] - the first stops extend over at least 80% of the total length of the first outer collector following the stacking direction;

[0023] - the first stops are supported against the first and / or second lateral faces of the block and / or against the mechanical connecting parts;

[0024] - the first stops have a stop spacing between them according to the transverse direction, the first and second lateral faces of the block having between them said stop spacing along the transverse direction or the mechanical connecting elements having between them said stop spacing along the transverse direction;

[0025] - the passages for the circulation of the first fluid have initial openings opening onto the first main face of the block, and have second openings opening onto the second main face of the block;

[0026] - the first openings are located closer to one of the first and second lateral faces of the block than the other of the first and second lateral faces of the block, and the second openings are located closer to said other of the first and second lateral faces of the block than to said one of the first and second lateral faces of the block;

[0027] - the electrochemical device further comprises a second external collector, pressed against the second main face of the block and communicating fluidly with the circulation passages of each electrochemical cell, the second external collector comprising second stops cooperating with the first and / or second lateral faces of the block and / or with the mechanical connecting elements and defining the position of the second external collector on the second main face along the transverse direction;

[0028] - the electrochemical device includes flanges placed on the first and second external collectors and drawing the first and second external collectors towards each other;

[0029] - the electrochemical device further comprises collectors for at least one second fluid, arranged inside the block.

[0030] According to a second aspect, the invention relates to an assembly comprising two electrochemical devices having the above characteristics, the first external collectors of the electrochemical devices being of a single piece.

[0031] According to a third aspect, the invention relates to a motor vehicle comprising an electrochemical device having the above characteristics or an assembly having the above characteristics.

[0032] According to a fourth aspect, the invention relates to a method for assembling the electrochemical device having the above characteristics, the method comprising the following steps:

[0033] - stacking of electrochemical cells one on top of the other according to the direction stacking;

[0034] - arrangement of the end plates at both ends of the block according to the stacking direction, the mechanical connecting parts connecting the end plates to each other;

[0035] - placement of the first external collector against the first main face of the block ;

[0036] - stressing of the end plates towards each other along the direction stacking by mechanical connecting elements, the end plates pressing the electrochemical cells together;

[0037] during the stressing step, the first outer collector being free in translation along the stacking direction relative to the electrochemical cells, the first stops of the first outer collector cooperating with the lateral faces of the block and / or with the mechanical connecting elements and defining the position of the first outer collector on the first main face along a transverse direction perpendicular to the stacking direction.

[0038] Other features and advantages of the invention will become apparent from the detailed description given below, by way of example and not limitation, with reference to the accompanying figures, among which: - [Fig.1] Fig.1 is a perspective view of an electrochemical device according to a first embodiment of the invention; - [Fig.2] The [Fig.2] is a simplified schematic representation of a motor vehicle equipped with the electrochemical device of the [Fig.1]; - [Fig.3] The [Fig.3] is a cross-sectional view of the electrochemical device of the [Fig.1], taken perpendicular to the stacking direction; - [Fig.4] The [Fig.4] is a perspective view of the first main face of the block made up of the electrochemical cells, the collector not being shown in order to show the openings of the circulation passages of the first fluid; - [Fig. 5] [Fig. 5] is a front view of a plate from one of the cells electrochemical, showing the trace of the circulation path of the first fluid; - [Fig. 6] [Fig. 7] [Fig. 8] Figures 6, 7 and 8 are section and lateral views perspective, enlarged, showing three forms of realization of the joint interposed between the first external collector and the first main face of the block; - [Fig. 9] [Fig. 10] Figures 9 and 10 are views similar to those of Figures 1 and 3, for a second embodiment of the invention; and - [Fig. 11] The [Fig. 11] is a perspective view of an assembly comprising several electrochemical devices of the type shown in figures 1 to 8.

[0039] The electrochemical device 1 shown in [Fig.1] is typically a fuel cell.

[0040] In this case, it is advantageously carried on board a motor vehicle 3, as shown in [Fig.2]. The fuel cell then generates electricity, which powers a battery connected to, and / or, an electric propulsion motor of the vehicle.

[0041] The electrochemical device is typically a PEMFC (Proton Exchange Membrane Fuel Cell).

[0042] A PEMFC transforms the chemical energy released during the electrochemical reaction of hydrogen H2 and oxygen O2 into electrical energy.

[0043] The principle is known and will not be detailed here.

[0044] Alternatively, the electrochemical device 1 is a fuel cell of another type, or an electrolyzer or any other type of electrochemical device.

[0045] The electrochemical device 1 comprises a bulk structure 5 including:

[0046] - a plurality of electrochemical cells 7, stacked one on top of the other according to a stacking direction E and constituting a block 9;

[0047] - end plates 11 placed at both ends of block 9 according to the stacking direction E;

[0048] - mechanical connecting elements 13 connecting the end plates 11 one to the other and forcing the end plates 11 towards each other along the stacking direction E, the end plates 11 pressing the electrochemical cells 7 together.

[0049] The term "massive structure" refers, for example, to any assembly of several components, in this case the various components that usually constitute a fuel cell. For example, the massive structure 5 can be likened to a "stack," that is, a stacking or assembly of elements individual current-producing cells, in this case a stack of 7 electrochemical cells.

[0050] The term "block" refers, for example, to any polyhedron, regardless of its shape, said polyhedron thus comprising the stack of electrochemical cells. Preferably, as illustrated, the block 9 is substantially parallelepiped in shape, preferably rectangular, that is to say, it is advantageously formed by a stack of electrochemical cells 7, each of which is itself rectangular parallelepiped in shape. More precisely, each electrochemical cell 7 is then preferably formed by a rectangular separating plate.

[0051] In a known manner, each electrochemical cell 7 comprises:

[0052] - a membrane-electrode assembly (MEA); and

[0053] - an anodic separating plate and a cathodic separating plate pressed from two opposite sides of the membrane-electrode assembly.

[0054] The AME comprises a membrane, anodic and cathodic catalytic layers arranged on two large opposite faces of the membrane and two gaseous diffusion layers arranged on the anodic and cathodic catalytic layers.

[0055] When the electrochemical cells 7 are stacked one on top of the other, the anodic plate of a given cell is placed against the cathodic plate of the neighboring cell, with interposition of a sealing device, for example a gasket or a weld.

[0056] The anodic separating plate and cathodic separating plate assembly then forms a bipolar plate.

[0057] Each electrochemical cell 7 has a passage 15 for the circulation of a first fluid (see [Fig. 5]). The first fluid is preferably a gas, preferably comprising oxygen. For example, the first fluid is air. Preferably, the first fluid supplies the electrochemical device 1 at a pressure between 1.5 and 5 bar absolute, typically between 2 and 3 bar absolute.

[0058] Each electrochemical cell 7 also has a passage for the circulation of a second fluid. The second fluid is preferably also a gas, and consists mainly of hydrogen. The second fluid also supplies the electrochemical device at a pressure higher than atmospheric pressure.

[0059] Typically, a circulation passage for a heat transfer fluid is provided within each bipolar plate, in particular between the aforementioned anodic and cathodic separator plate assembly. The heat transfer fluid is intended to cool the electrochemical cells in the case of a fuel cell.

[0060] Block 9 has first and second principal faces 17, 19 substantially parallel to the stacking direction E and opposite each other ([Fig. 3]). Block 9 also has first and second lateral faces 21, 23 substantially parallel to the stacking direction E and opposite each other. In other words, block 9 thus defines a parallelepiped.

[0061] Figures 1 and 3 show a longitudinal direction L and a transverse direction T. The transverse direction T is perpendicular to the stacking direction E. The longitudinal direction L is perpendicular to the stacking direction E and perpendicular to the transverse direction T.

[0062] The first and second main faces 17, 19 extend in planes parallel to the stacking direction E and the transverse direction T.

[0063] For example, block 9 is rectangular parallelepiped in shape, the first and second lateral faces 21, 23 being perpendicular to the first and second principal faces 17, 19. The first and second lateral faces 21, 23 then extend in planes parallel to the stacking direction E and the longitudinal direction L.

[0064] The first fluid circulation passages 15 have first openings 25 opening onto the first main face 17 of the block, and second openings 27 opening onto the second main face 19 of the block. The first fluid flows from the first opening 25 to the second opening 27 in channels formed in the cathode plate 29, as illustrated in [Fig. 5]. The first external collector is then arranged so as to simply cover the first openings.

[0065] The second fluid flows through channels formed in the anodic plate. These channels and the anodic plate are not shown.

[0066] The electrochemical cells 7 are thin structures, parallel to each other and perpendicular to the stacking direction. They each have a rectangular shape. The edges of the cells 7 define the first and second principal faces 17, 19, and define the first and second lateral faces 21, 23.

[0067] As can be seen in particular in Figures 1 and 4, the end plates 11 are placed against the cells 7 located at both ends of the stack.

[0068] The mechanical elements 13 are preferably tie rods (for example threaded rods) extending along the stacking direction E. Half of the mechanical elements 13 are located opposite the first lateral face 21, and the other half of the mechanical elements 13 are located opposite the second lateral face 23.

[0069] The mechanical parts 13 are separated from the lateral face 21, 23, a space remaining between the mechanical parts 13 and the lateral face 21, 23.

[0070] Two mechanical connecting members 13 are located at the two ends of each lateral face 21, 23. In other words, two mechanical members 13 are located along the edge by which the first lateral face 21 connects to the first and second main faces 17, 19. Two other mechanical elements 13 are located along the edges by which the second lateral face 23 connects to the first main face 17 and to the second main face 19.

[0071] In the example shown, an additional mechanical element 13 is located longitudinally in the center of each of the lateral faces 21, 23.

[0072] Support plates 31 are placed on either side of the stack of electrochemical cells, opposite the end plates 11. Springs not shown are interposed between each support plate 31 and the corresponding end plate 11.

[0073] The opposite ends of each mechanical member 13 pass through eyelets provided in support plates 31. The mechanical members 13 stress the support plates 31 towards each other in the stacking direction E, these support plates 31 themselves stressing the two end plates 11 towards each other in the stacking direction E.

[0074] The electrochemical device 1 further comprises a first external manifold 33, attached to the first main face 17 of the block 9 and communicating fluidly with the circulation passages 15 of each electrochemical cell 7. By "external manifold," we mean any element capable of transporting, in a sealed manner and advantageously under pressure, a fluid, preferably a gas (oxygen, air, hydrogen, for example) located outside the block 9. In other words, the external manifold 33 allows the fluid to be conveyed to the block 9, and more specifically to the electrochemical cells 7 thereof, without passing through the interior of the block 9, that is to say, without passing through the electrochemical cells 7 themselves. The external manifold 33 is, however, advantageously part of the bulk structure 5, particularly in that it is attached to the block 9, as will be detailed later.

[0075] In the first embodiment of the invention, shown in Figures 1 to 8, the first outer collector 33 includes first stops 35, cooperating with the mechanical connecting members 13, and defining the position of the first outer collector 33 on the first main face 17 along the transverse direction T. The first stops 35 can include any mechanical element that can perform a stop function, such as, for example, a surface, a chamfer, an edge, a fold, a pin, etc.

[0076] As can be seen in particular in Figures 1 and 3, the first external collector 33 comprises a flat area 37 substantially parallel to the first main face 17 and an area 39 projecting from the flat area 37 opposite the first main face 17. The projecting area 39 thus delimits a circulation volume for the first fluid, outside the block 9. The projecting area 39 is preferably convex, that is to say- said with a curve oriented outwards from block 9, so as to preserve said circulation volume.

[0077] The first outer collector 33 further comprises folded edges integral with the flat area 37 and defining the stops 35. Thus, stops are created in a particularly simple and economical manner (a simple folding operation). It is also possible to easily create a seal between the flat area and the first main face. These folded edges also ensure, in a so-called "multistack" configuration for assembling several devices to pool the power delivered by them, a dielectric distance between the cells and therefore an electrical insulation function. Indeed, the various folded edges forming stops 35 of the different outer collectors 33 then act as spacers (or mechanical stops) between the different electrochemical devices, guaranteeing the presence of a space between the devices and in particular between the cells of the different devices.In other words, an electrical safety distance is created between the cells of the different devices thanks to the stops 35. Overall safety is thus improved.

[0078] More specifically, as illustrated, the flat zone 37 is an intermediate zone connected on one side to, and connecting with each other, the first stop 35 and the projecting zone 39. Preferably, the flat zone 37 is perpendicular to the first stop 35.

[0079] The flat area 37 is pressed against the first main face 17 when the solid structure is assembled. It preferably has a curved shape, for example substantially annular, and delimits a closed-contour opening 41. The first fluid then flows between the first openings 25 and the internal volume of the first collector 33 through the opening 4L. The area 39 then connects to the flat area 37 around the entire circumference of the opening 4L. The opening 41 covers the first openings 25 of the circulation passages 15 of all the electrochemical cells.

[0080] As shown in [Fig. 1], the first external manifold 33 has an orifice 43 opening into the circulation volume of the first fluid. This orifice 43 is an inlet or outlet for the first fluid. It is connected to a supply or discharge line for the first fluid (not shown) allowing the electrochemical device to be supplied with or discharged with the first fluid.

[0081] The protruding zone 39 is elongated along the stacking direction E. The orifice 43 is located at one end of the zone 39 along the stacking direction E. The circulation volume of the first fluid within the protruding zone 39 advantageously has, perpendicular to the stacking direction E, a cross-section that decreases from the orifice 43 to the opposite end of the protruding zone 39. Such a reduction in cross-section makes it possible, in particular, to ensure a distribution homogeneous fluid for each electrochemical cell 7, including those far from orifice 43.

[0082] As mentioned above, the flat area 37 is shaped like a frame around the opening 41. Two arms 45 ([Fig. 3]) of this frame extend parallel to the stacking direction E, and two arms (not visible) extend transversely. The arms 45 have an edge adjacent to the opening 41 and defining its boundary. This edge is connected to the projecting area 39. The first stops 35 are connected to the edges of the arms 45 located opposite the opening 41 along the transverse direction.

[0083] Relative to the flat area 37, the first stops 35 protrude along the longitudinal direction on a side opposite to the protruding area 39. The first stops 35 extend over at least 80% of the total length of the first collector 33 along the stacking direction, and preferably over 100% of the total length of the first collector 33. Thus, the position of the first collector along the transverse direction is defined in a particularly precise manner: the greater the length in contact, the greater the precision.

[0084] The first stops 35 preferably extend in respective planes perpendicular to the flat area 37. Thus, the stops are created in a simple manner and allow the first collector to be precisely locked in position on the first main face. Furthermore, they are preferably supported against the mechanical connecting elements 13. By "support" here we mean direct support, that is to say, the first stops 35 are in direct contact with the mechanical connecting elements 13.

[0085] To do this, the first stops 35 have a stop spacing between them along the transverse direction T. This spacing is taken between the inner faces 47 of the two stops 35, that is to say between the faces of the stops 35 opposite each other.

[0086] The mechanical connecting members 13 have the aforementioned stop gap between them along the transverse direction T. This gap is taken between the generatrices of the mechanical members 13 rotated in opposite directions. The fastening members 13 are thus pressed against the internal surfaces 47 of the stops 35.

[0087] In other words, the stops 35 are located outside the two mechanical members 13 and are in (direct) contact against the mechanical members 13. In this case, the first stops 35 and the connecting mechanical members 13 all have the same transverse spacing between them.

[0088] The stops 35 bear against the mechanical elements 13 located closest to the first main face 17, that is to say the mechanical element 13 located along the edge separating the first main face 17 and the lateral face 21, and the element mechanical 13 located along the edge separating the first main face 17 and the second lateral face 23.

[0089] When the first stops have the same spacing in the transverse direction as the lateral faces of the block (embodyment of figures 9 and 10) or as the mechanical connecting members (embodyment of figures 1 to 8), the support of the first stops is obtained simply and directly.

[0090] As illustrated in the figures, the electrochemical device further comprises a second external collector 49, attached to the second main face 19 of the block 9 and communicating fluidly with the circulation passages 15 of each electrochemical cell 7. The second external collector 49 includes second stops 51 cooperating with the mechanical connecting members 13 and defining the position of the second external collector 49 on the second main face 19 along the transverse direction T. It is particularly advantageous for the second collector 49 to be held in position along the transverse direction by second stops 51, in the same way as the first collector 33. This simplifies the design of the electrochemical device.

[0091] As illustrated, the second stops 51 cooperate with the mechanical connecting members 13 located closest to the second main face 19. These are the mechanical connecting members 13 located along the edges separating the first lateral face 21 from the second main face 19, and separating the second lateral face 23 from the second main face 19.

[0092] The second outer collector 49 is typically of the same type as the first collector 33. Consequently, many elements of the second outer collector 49 are symmetrical to the corresponding elements on the first outer collector 33, with respect to a central plane located at the center of the block 9, and will not necessarily be detailed in this description. The plane of symmetry is parallel to the stacking direction and to the transverse direction.

[0093] As can be seen in particular in Figures 1 and 3, the second external collector 49 thus comprises a flat area 53 substantially parallel to the second main face 19 and an area 55 projecting from the flat area 53 opposite the second main face 19. This flat area 53 is then symmetrical to the flat area 37 described previously. The projecting area 55 is preferably convex and is substantially symmetrical to the projecting area 39 of the first collector. The projecting area 55 delimits a circulation volume for the first fluid outside the block 9. The area 55 connects to the flat area 53 around the entire circumference of the opening 57. The opening 57 covers the second openings 27 of all the electrochemical cells 7.

[0094] The second external collector 49 also has folded edges attached to the flat area 53 and defining the stops 51, the latter being in particular symmetrical to the first stop 35.

[0095] The flat area 53 is pressed against the second main face 19. It has an annular shape, and delimits an opening 57 with a closed contour, symmetrically to the opening 41 of the first external collector 33.

[0096] The first fluid circulates between the second openings 27 and the internal volume of the second collector 49 through the opening 57.

[0097] As shown in [Fig. 1], the second external manifold 49 has an orifice 63 opening into the circulation volume of the first fluid. This orifice 63 is an inlet or outlet for the first fluid. It is connected to a supply or discharge line for the first fluid. In this case, the first external manifold 33 advantageously forms a supply line for the first fluid to the electrochemical cells 7, while the second external manifold 49 forms a discharge line for the first fluid, after the latter has passed through the block 9, or vice versa.

[0098] The protruding zone 55 is elongated along the stacking direction E. The orifice 63 is located at one end of the zone 55 along the stacking direction E. The circulation volume of the first fluid inside the protruding zone 55 advantageously has, perpendicular to the stacking direction E, a cross-section that decreases from the orifice 63 to the opposite end of the protruding zone 55. Such a reduction in cross-section makes it possible in particular to ensure a homogeneous distribution of the fluid for each electrochemical cell 7, including those far from the orifice 63.

[0099] As mentioned above, the flat area 53 is shaped like a frame around the opening 57. Two arms 59 ([Fig. 3]) of this frame extend parallel to the stacking direction E, and two arms extend transversely. The arms 59 have an edge adjacent to the opening 57 and defining its boundary. This edge is connected to the projecting area 55. The second stops 51 are connected to the edges of the arms 59 located opposite the opening 57 along the transverse direction.

[0100] Relative to the flat area 53, the second stops 51 protrude along the longitudinal direction on a side opposite to the protruding area 55. The second stops 51 extend over at least 80% of the total length of the second collector 49 along the stacking direction, and preferably over 100% of the total length of the second collector 49.

[0101] The second stops 51 extend preferentially in respective planes perpendicular to the flat area 53.

[0102] Advantageously, the electrochemical device 1 comprises flanges 65, 67 placed on the first and second external collectors 33, 49 and pressing the first and second collectors 33, 49 towards each other. "Flanges" include, in particular, any mechanical element enabling the first and second external collectors 33, 49 to be mechanically connected, such as plates, cables, tie rods, straps, etc. The flange 65 is preferably pressed against the flat area 37. It presses the flat area 37 against the first main face 17. The flange 67 is preferably pressed against the flat area 53 and presses the flat area 53 against the second main face 19. Thanks to the flanges 65, 67, these first and second external collectors 33, 49 can be held in position in a simple, reliable, and economical manner.

[0103] Preferably, tie rods (not shown) rigidly connect the flanges 65 and 67 to each other. These tie rods are positioned relatively further from the first and second lateral faces 21, 23 than the mechanical connecting elements 13. In other words, they extend outwards from the mechanical connecting elements 13. The tie rods are, for example, parallel to the longitudinal direction. They apply stress to the flanges 65, 67 towards each other along the longitudinal direction.

[0104] As can be seen in figures 3 and 5, the first openings 25 of the circulation passages of the first fluid are preferentially offset towards one of the two lateral faces of the block 21 23, and the second openings 27 are offset towards the other of the two lateral faces of the block 23, 21. The first external collector 33 must in this case also be offset towards one of the lateral faces of the block, and the presence of the stops 35 makes it remarkably well secured in position.

[0105] In the example shown, the first openings 25, made on the first main face 17, are offset towards the first lateral face 21. The second openings 27, made on the second main face of the block 19, are offset towards the second lateral face 23. This means that the first openings 25 are closer to the first lateral face 21 than to the second lateral face 23. Conversely, the second openings 27 are closer to the second lateral face 23 than to the first lateral face 21.

[0106] The channels connecting the first aperture 25 to the second aperture 27 thus have a main trajectory at an angle, substantially along a diagonal of the separating plate, and can therefore be slightly sinuous, as seen in [Fig. 5]. This makes it possible to maximize the length of the channels by bypassing the homogenization zone and thus to enlarge the active zone of the bipolar plate (proton exchange zone).

[0107] In other words, it is not necessary to provide on the bipolar plate a homogenization zone to distribute the first fluid, from the collector, into the channels running through the active zone of the bipolar plate.

[0108] In a bipolar plate of traditional design, the homogenization zone serves to distribute the first fluid substantially equally in all the channels of the active zone. It occupies a significant surface area on the bipolar plate, which reduces the surface area available for the active zone accordingly.

[0109] On the contrary, in the present device, each channel of the active zone opens directly into the external collector, so that the surface traditionally covered by the homogenization zone can be wholly or partly integrated into the active zone.

[0110] Consequently, the projecting area 39 of the first collector 33 is also offset towards the first lateral face 21. The branch 45 separating the projecting area 39 from the first lateral face 21 has, along the transverse direction, a smaller width than the branch 45 separating the projecting area 39 from the second lateral face 23.

[0111] Conversely, the projecting area 55 of the second external collector 49 is located transversely closer to the second lateral face 23 than to the first lateral face 21. As a result, the branch 59 separating the projecting area 55 from the second lateral face 23 is less wide than the branch 59 separating the projecting area 55 from the first lateral face 21.

[0112] The electrochemical device 1 preferably further comprises collectors 69 for the second fluid, which could possibly constitute an invention in its own right. These collectors are preferably provided inside the block 9, unlike the external collectors 33, 49. The collectors 69 are preferably formed by a stack of orifices 71 provided in the anodic and cathodic plates, with sealing gaskets interposed between the plates.

[0113] Such an architecture being known to those skilled in the art, it will not be described in further detail here. However, the original combination of an electrochemical device combining at least one external fluid collector 33, 49 to a block 9 and a fluid collector 69 internal to the block could be the subject of a separate invention. It should be noted that the invention could then be defined as relating to an electrochemical device comprising a solid structure including:

[0114] - a plurality of electrochemical cells, stacked one on top of the other according to a stacking direction and constituting a block, each electrochemical cell having a passage for the circulation of a first fluid, the block having first and second principal faces substantially parallel to the stacking direction and opposite each other, the block further having first and second lateral faces substantially parallel to the stacking direction and opposite each other;

[0115] - advantageously, end plates placed at both ends of the block according to the stacking direction;

[0116] - advantageously, mechanical connecting elements connecting the plates from end to end and forcing the end plates towards each other along the stacking direction, the end plates pressing the electrochemical cells together;

[0117] the electrochemical device further comprising a first external collector, pressed against the first main face of the block and communicating fluidly with the circulation passages of each electrochemical cell,

[0118] the electrochemical device further comprising collectors for at least a second fluid, arranged inside the block. This electrochemical device could advantageously also have the characteristics described above, and / or which are the subject of the claims.

[0119] In particular, thanks to the internal manifold 69, the overall size of the electrochemical device in the transverse direction is reduced. Furthermore, because the manifolds for the first fluid are arranged outside the block, the available volume for routing the manifolds inside the block is greater and / or the choice of location is flexible. In addition, such an architecture maximizes the active surface area (gas exchange) formed by the circulation passages 15.

[0120] The electrochemical device 1 also includes collectors 73 for the circulation of the heat transfer fluid. These collectors 73 are provided within the block 9. Each collector 73 consists of a stack of orifices 75 cut into the anodic and cathodic plates. The heat transfer fluid is intended to circulate between the anodic and cathodic separating plate assembly. Seals are interposed between the anodic and cathodic plates around the orifices 75.

[0121] As can be seen in particular in Figures 3 and 4, a closed-contour seal 76 is interposed between the flat area 37 of the first manifold 33 and the first main face 17. Thus, the seal between the first outer manifold and the block is created simply and effectively. Furthermore, due to the presence of the stops 35, the portions of the seal belonging to the flat area and the first main face are correctly positioned relative to each other. The correct positioning of these two surfaces is ensured, in particular, during compression of the block along the stacking direction. It is also ensured during pressurization of the first outer manifold. This is particularly advantageous when the first fluid is at a high pressure, for example, between two and three bars. absolute. During pressurization, the first outer manifold can deform laterally, i.e., in the transverse direction, and compromise the correct positioning of the gasket portion belonging to the flat area relative to the gasket portion belonging to the first main face. In the first embodiment, the base 95 of the projecting area 39 bears against the inner edge 97 of the flange 65, which prevents the deformation of the first outer manifold 33 ([Fig. 6]) in the transverse direction. The base 95 corresponds to the region where the projecting area 39 connects to the flat area 37.

[0122] More specifically, the closed contour seal 76 extends over the entire periphery of the opening 41, and ensures that the first fluid cannot leak along the first main face 17.

[0123] The closed contour seal 76 preferably comprises a sealing portion carried by the flat area 37 and a sealing portion carried by the first main face 17, for example by having a portion attached to the flat area 37 and a portion attached to the main face 17. For example, each sealing portion can be overmolded and / or cut out on the flat area 37 or on the main face 17. This makes it possible in particular to facilitate the assembly operation of the external manifold 33, 49 while taking into account the assembly tolerances and thus ensuring a good seal.

[0124] The closed-contour seal 76 preferably comprises two main branches 77, or two lips, parallel to each other extending along the stacking direction E. The closed-contour seal 76 also preferably comprises two transverse branches, or lips 79, extending along the transverse direction and connecting the two main branches 77 to each other. The presence of these branches notably ensures a seal between the outer manifold and the block 9.

[0125] Furthermore, the presence of the stops 35 ensures a good seal, particularly at these two parallel branches. The sealing portions belonging to the first outer manifold and the first main face, and defining these two branches, are held securely in position relative to each other.

[0126] Thus, the stops 35 contribute to maintaining good alignment of the joint parts belonging to the first outer collector and the first main face with each other.

[0127] In the example shown, the closed contour joint 76 thus has a substantially rectangular shape. The main branches 77 and the transverse branches 79 are then formed by continuity of material.

[0128] According to a first embodiment, shown in particular in [Fig. 6], a first groove 81 is formed in the flat area 37, along the entire trace of the closed contour joint 76. A second groove 83 is formed on the first principal face 17, along the entire path of the closed contour joint 76, opposite the first groove 81. A first seal 85 is housed in the first groove 81, and a second seal 87 in the second groove 83. The first seal 85 and the second seal 87 are in watertight contact with each other along the entire path of the closed contour joint and guarantee the seal between the first external manifold 33 and the block 9.

[0129] A second embodiment will now be described, with reference to [Fig.7]. Only the points by which this embodiment differs from that of [Fig.6] will be detailed below.

[0130] In the embodiment of [Fig.7], the joint portion carried by the flat area 37 does not have a first groove 81, but is a flat surface 89. The second joint 87 is in direct contact with this flat surface 89. The closed contour joint 76 does not have the first joint 85.

[0131] A third embodiment will now be described with reference to [Fig.8]. Only the points by which this embodiment differs from that of [Fig.6] will be detailed below.

[0132] In the embodiment shown in [Fig. 8], the first groove 81 is replaced by a closed-contour rib 91. The closed-contour rib 91 extends along the entire length of the joint. It is engaged in the second groove 83 and compresses the second joint 87 at the bottom of the second groove 83.

[0133] A closed contour seal 92 is interposed between the second outer collector 49 and the second main face 19. The closed contour seal 92 is identical to the closed contour seal 76. It can be according to one of the three variants described above for the first closed contour seal 76.

[0134] A second embodiment of the invention will now be described, with reference to Figures 9 and 10. In this embodiment, the external manifold(s) is / are supported on the lateral face(s) 21, 23 and not on the mechanical connecting elements, as described previously in the first embodiment. Only the points by which this second embodiment differs from the first will be detailed below. Identical elements or elements performing the same functions will be designated by the same reference numerals in both embodiments.

[0135] In the second embodiment, the first stops 35 cooperate with the first and second lateral faces 21, 23 of the block to define the position of the first external collector 33 on the first main face 17 along the transverse direction T. The first stops 35 are supported against the first and second lateral faces 21, 23. By "support" we mean here a direct support, that is to say that the first stops 35 are in direct contact with the first and second lateral faces 21, 23.

[0136] The first and second lateral faces 21, 23 of the block have a spacing between them, along the transverse direction, equal to the abutment spacing. For reference, the stop spacing corresponds to the spacing along the transverse direction between the first stops 35, and more precisely between the inner faces 47 of the stops 35.

[0137] The first stops 35, as seen in particular on [Fig. 10], are inserted between the first or second lateral face 21, 23 and the mechanical connecting member 13 extending along the edge connecting the lateral face to the first main face 17.

[0138] For example, there is a gap between the stop 35 and the mechanical connecting member 13. In other words, the outer face 93 of the stop, opposite the inner face 47, is not in contact with the mechanical connecting member 13.

[0139] Alternatively, the stop 35 is in contact with the mechanical connecting member.

[0140] In both cases, the correct positioning of the two parts of the closed contour joint 76 is guaranteed at the time of pressurization of the first outer manifold by the cooperation of the first stops 35 against the mechanical connecting members 13. The lateral deformation of the first outer manifold is limited by the stops 35 bearing against the mechanical connecting members 13.

[0141] Advantageously, the second stops 51 cooperate with the first and second lateral faces 21, 23 of the block to define the position of the second external collector 49 on the second main face 19 along the transverse direction T. The second stops 51 are arranged like the first stops 35, for example according to the principle of central symmetry mentioned previously.

[0142] According to a third embodiment of the invention, the first embodiment (outer collector in contact with the mechanical connecting elements) and the second embodiment (outer collector in contact with the lateral faces) are combined: thus the first outer collector 33 (and where applicable the second outer collector 49) is (are) simultaneously in contact with the mechanical connecting elements 13 and with the first lateral face 21 or with the second lateral face 23 or even with the first lateral face and second lateral face 21, 23.

[0143] In the second and third embodiments, the fact that the stops 35, 51 are positioned between the lateral faces 21, 23 and the mechanical fixing elements 13 contributes to maintaining the alignment of the cells in the longitudinal direction and in the transverse direction in the different life situations of the device, in particular when it is subjected to mechanical stresses (passage of the vehicle over a speed bump, impact on the vehicle, impact during manufacturing, etc.).

[0144] According to an advantageous embodiment, the invention relates to an assembly comprising several electrochemical devices 1 having the above characteristics. This assembly 98 is shown in [Fig. 11].

[0145] The blocks 9 of the various electrochemical devices 1 are juxtaposed transversely next to each other in a single alignment. They are rigidly fixed to each other and together constitute a single mass. The stacking directions E of the various blocks 9 are parallel to each other.

[0146] The first principal faces 17 of the different blocks 9 are juxtaposed transversely and are inscribed in the same first plane. They thus form a first support plane 99.

[0147] The second main faces 19 of the different blocks 9 are juxtaposed transversely and are inscribed in the same second plane. They form a second support plane 101.

[0148] The first lateral face 21 of each block 9 is affixed to the second lateral face 23 of the adjacent block, except for the blocks located at the ends of the alignment. The first lateral face 21 of the block 9 located at one end of the alignment delimits the block on one side, perpendicular to the transverse direction. It will be referred to here as the first end lateral face 103. The second lateral face 23 of the block 9 located at the other end of the alignment delimits the block on a second side, perpendicular to the transverse direction. It will be referred to here as the second end lateral face 105.

[0149] The first external collectors 33 of the electrochemical devices 1 are made in one piece 107.

[0150] They are connected in parallel to the same collector conduit, not shown.

[0151] The single piece 107 constituting the first external collectors is pressed against the first support plane 99, that is to say against the first main faces 17.

[0152] The second external collectors 49 of the electrochemical devices 1 are also made in one piece 109.

[0153] They are connected in parallel to the same collector conduit, not shown.

[0154] The single part 109 is pressed against the second support plane 101, that is to say against the second main faces 19.

[0155] The bearing plates 31 located on one side of the blocks 9 are made of the same piece and form a single bearing plate 111.

[0156] The support plates 31 located on the other side of the blocks 9 along the stacking directions E are also made of the same piece and form another single support plate 113.

[0157] The single support plates 111 and 113 are connected to each other by two sets of mechanical connecting members 13, located opposite the first and second lateral end faces 103, 105.

[0158] The single part 107 constituting the first external collectors 33 includes two first stops 115, defining the position of the single part 107 on the first support plane 99 along a transverse direction T. One of the first two stops 115 cooperates with the first end lateral face 103 or with one of the mechanical connecting members 13 located opposite the first end lateral face 103. The other of the first two stops 115 cooperates with the second end lateral face 105 or with one of the mechanical connecting members 13 located opposite the second end lateral face 105.

[0159] Similarly, the single part 109 constituting the second external collectors 49 includes two second stops 117, defining the position of the single part 109 on the second support plane 101 along a transverse direction T. One of the first two stops 117 cooperates with the first end lateral face 103 or with one of the mechanical connecting members 13 located opposite the first end lateral face 103. The other of the first two stops 117 cooperates with the second end lateral face 105 or with one of the mechanical connecting members 13 located opposite the second end lateral face 105.

[0160] The flanges 65 of the various electrochemical devices are made of a single piece, forming a single flange 119. Similarly, the flanges 67 of the various electrochemical devices are made of a single piece, forming another single flange 121. The single flanges 119 and 121 are connected to each other by two sets of tie rods not shown, located opposite the first and second lateral end faces 103, 105.

[0161] In this configuration, the external collectors can be made in one piece for example in PPS, PPSU, PSU, injected PVDF selected to have a coefficient of thermal expansion equivalent to that of the blocks 9. This coefficient is for example between 2 and 50*10 5 K1.

[0162] According to yet another aspect, the invention relates to a method of assembling the electrochemical device 1 described above.

[0163] The method is specifically designed for assembling the electrochemical device 1 described above. Conversely, the electrochemical device 1 is particularly well-suited for assembly by the method that will now be described.

[0164] The process comprises the following steps, preferably carried out in the order below:

[0165] - stacking of the electrochemical cells 7 one on top of the other according to the direction stacking E;

[0166] - arrangement of the end plates 11 at both ends of the block 9 according to the stacking direction E, with the mechanical connecting elements 13 connecting the end plates 11 to each other;

[0167] - placement of the first external collector 33 against the first main face 17 from block 9;

[0168] - stressing of the end plates 11 towards each other along the direction stacking E by the mechanical connecting elements 13, the end plates 11 pressing the electrochemical cells 7 together.

[0169] The electrochemical cells 7 are as described above.

[0170] The end plates 11 are as described above.

[0171] Typically, the mechanical connecting members 13 connect the end plates 11 to each other via the support plates 31 and springs, as described above.

[0172] The first external collector 33 is as described above.

[0173] At the end of the arrangement step, the mechanical connecting elements 13 are in place but do not clamp the electrochemical cells 7 together.

[0174] The stressing step occurs after the placement of the first external collector 33 against the first main face 17 of the block 9.

[0175] During this solicitation step, the first collector 33 is free in translation along the stacking direction E relative to the electrochemical cells 7.

[0176] The first stops 35 of the first external collector 33 cooperate with the lateral faces 21, 23 of the block and / or with the mechanical connecting members 13 and define the position of the first external collector 33 on the first main face 17 along a transverse direction perpendicular to the stacking direction E.

[0177] Thus, the first external collector 33 is well aligned with respect to the block 9 along the transverse direction.

[0178] This allows the two parts of the closed contour seal 76 to coincide precisely, namely the part of the seal 76 carried by the first external collector 33 and the part of the seal 76 carried by the first main face 17.

[0179] Typically, the assembly process includes a step of placing the second outer collector 49 against the second main face 19 of the block. This placement takes place before the stressing step.

[0180] The second external collector 49 is as described above.

[0181] During the stressing step, the second outer collector 49 is free in translation along the stacking direction relative to the electrochemical cells 7. The second stops 51 belonging to the second outer collector 49 cooperate with the lateral faces of the block 21, 23 and / or with the mechanical connecting members 13 and define the position of the second outer collector 49 on the second main face 19 along the transverse direction.

[0182] The electrochemical device described above can have multiple variants.

[0183] As indicated above, the first fluid does not necessarily contain oxygen. The first fluid could be the anodic fluid, containing hydrogen. In this case, the circulation passage corresponds to the channels formed on the anodic plate of each electrochemical cell.

[0184] Alternatively, the first fluid could be used to cool the electrochemical cells. In this case, the circulation passage for the first fluid is provided between the electrochemical cells, between the anodic plate of one electrochemical cell and the cathodic plate of a neighboring electrochemical cell.

[0185] The electrochemical device could comprise only one external collector of the type described above, the second external collector being of a different type.

[0186] The first external manifold may be a supply manifold for the electrochemical device with the first fluid, the second external manifold being a discharge manifold for the first fluid. Alternatively, the first external manifold is a discharge manifold and the second external manifold is a supply manifold.

[0187] The mechanical connecting elements could directly connect the end plates to each other, and not via support plates.

[0188] The mechanical connecting elements could be of any suitable type, and are not necessarily tie rods. These mechanical connecting elements could be bars, screws, etc.

[0189] The first stops can cooperate either with the first and second lateral faces, or with two mechanical connecting members, or one with the first lateral face and the other with a mechanical connecting member, or one with the second lateral face and the other with a mechanical connecting member. Each first stop can also cooperate with both the first or second lateral face and a mechanical connecting member.

[0190] The same possibilities are envisaged for the second stops.

[0191] The electrochemical device described above offers several advantages. In general, the invention notably allows the use of pressurized fluid, greater tolerance during assembly, and the ability to account for the expansion of the block during operation. Furthermore, the solution of the invention is simple, easy to implement, reliable, and inexpensive.

Claims

Demands

1. Electrochemical device (1), comprising a solid structure (5) having: - a plurality of electrochemical cells (7), stacked one on top of the other along a stacking direction (E) and constituting a block (9), each electrochemical cell (7) having a passage (15) for the circulation of a first fluid, the block (9) having first and second principal faces (17, 19) substantially parallel to the stacking direction (E) and opposite to each other, the block (9) further having first and second lateral faces (21, 23) substantially parallel to the stacking direction (E) and opposite to each other; - end plates (11) placed at the two ends of the block (9) along the stacking direction;- mechanical connecting elements (13) connecting the end plates (11) to each other and forcing the end plates (11) towards each other along the stacking direction (E), the end plates (11) pressing the electrochemical cells (7) together; the electrochemical device (1) further comprising a first external collector (33), pressed against the first main face (17) of the block (9) and communicating fluidly with the circulation passages (15) of each electrochemical cell (7), the first collector (33) comprising first stops (35) cooperating with the first and / or second lateral faces (21, 23) of the block (9) and / or with the mechanical connecting elements (13) and defining the position of the first external collector (33) on the first main face (17) along a transverse direction (T) perpendicular to the stacking direction (E).;

2. Electrochemical device according to claim 1, wherein the first outer collector (33) has a flat area (37) substantially parallel to the first main face (17), an area (39), preferably convex, projecting from the flat area (37) opposite the first main face (17) and delimiting a circulation volume of the first fluid, and folded edges integral with the flat area (37), defining the stops (35).

3. Electrochemical device according to claim 2, wherein the first stops (35) extend in respective planes perpendicular to the planar area (37).

4. Electrochemical device according to any one of claims 2 or 3, wherein a closed contour seal (76) is interposed between the flat area (17) and the first principal face (17), the closed contour seal (76) preferably comprising a seal portion carried by the flat area (37) and a seal portion carried by the first principal face (17).

5. Electrochemical device according to claim 4, wherein the closed contour joint (76) comprises two main branches (77) parallel to each other, extending along the stacking direction.

6. Electrochemical device according to any one of the preceding claims, wherein the first stops (35) extend over at least 80% of a total length of the first outer collector (33) along the stacking direction.

7. Electrochemical device according to any one of the preceding claims, wherein the first stops (35) bear against the first and / or second lateral faces (21, 23) of the block (9) and / or against the mechanical connecting members (13).

8. Electrochemical device according to any one of the preceding claims, wherein the first stops (35) have a stop spacing between them in the transverse direction, the first and second lateral faces (21, 23) of the block (9) having said stop spacing between them in the transverse direction or the mechanical connecting members (13) having said stop spacing between them in the transverse direction.

9. Electrochemical device according to any one of the preceding claims, wherein the circulation passages (15) of the first fluid have first openings (25) opening onto the first main face (17) of the block (9), and have second openings (27) opening onto the second main face (19) of the block (9).

10. An electrochemical device according to claim 9, wherein the first openings (25) are located closer to one of the first and second lateral faces (21, 23) of the block than to the other of the first and second lateral faces (21, 23) of the block, and the second openings (27) are located closer to said other of the first and second lateral faces (21, 23) of the block than of said one of the first and second lateral faces (21, 23) of the block.

11. Electrochemical device according to any one of the preceding claims, wherein the electrochemical device (1) further comprises a second external collector (49), pressed against the second main face (19) of the block (9) and communicating fluidly with the circulation passages (15) of each electrochemical cell (7), the second external collector (49) comprising second stops (51) cooperating with the first and / or second lateral faces (21, 23) of the block (9) and / or with the mechanical connecting members (13) and defining the position of the second external collector (49) on the second main face (19) along the transverse direction.

12. Electrochemical device according to claim 11, wherein the electrochemical device (1) comprises flanges (65, 67) placed on the first and second external collectors (33, 49) and forcing the first and second external collectors (33, 49) towards each other.

13. Electrochemical device according to any one of the preceding claims, wherein the electrochemical device (1) further comprises collectors (69) for at least a second fluid, arranged inside the block (9).

14. Assembly comprising a plurality of electrochemical devices (1) according to any one of the preceding claims, the first outer collectors (33) of the electrochemical devices (1) being of one piece.

15. Motor vehicle comprising an electrochemical device according to any one of claims 1 to 13 or an assembly according to claim 14.

16. Method of assembling the electrochemical device according to any one of claims 1 to 13, the method comprising the following steps: - stacking the electrochemical cells (7) one on top of the other in the stacking direction; - arranging the end plates (11) at both ends of the block (9) in the stacking direction, the mechanical connecting members (13) connecting the end plates (11) to each other; - placing the first outer collector (33) against the first main face (17) of the block (9); - stressing of the end plates (11) towards each other along the stacking direction by the mechanical connecting elements (13), the end plates (11) pressing the electrochemical cells (7) together; during the stressing step, the first outer collector (33) being free in translation along the stacking direction relative to the electrochemical cells (7), the first stops (35) of the first outer collector (33) cooperating with the lateral faces (21, 23) of the block (9) and / or with the mechanical connecting members (13) and defining the position of the first outer collector (33) on the first main face (17) along a transverse direction perpendicular to the stacking direction.

Images