Method for manufacturing an electrochemical device, and associated device

Abstract

A method for manufacturing an electrochemical cell, comprising the following steps: • - providing a first element (30, 30.1) comprising a first rib (34, 36, 34.1, 36.1, 34.2, 36.2) bordered by two first linking portions (37, 38, 39, 40, 37.1, 38.1, 39.1, 40.1, 37.2, 38.2, 39.2, 40.2); • - providing a second element (50, 50.1) comprising a second rib (54, 56, 54.1, 56.1, 54.2, 56.2) bordered by two second linking portions (57, 58, 59, 60, 57.1, 58.1, 59.1, 50.1, 57.2, 58.2, 59.2, 60.2); • - placing the first element (30, 30.1) opposite the second element (50, 50.1), and • - producing a first junction of a first linking portion (37, 38, 39, 40, 37.1, 38.1, 39.1, 40.1, 37.2, 38.2, 39.2, 40.2) on a second linking portion (57, 58, 59, 60, 57.1, 58.1, 59.1, 50.1, 57.2, 58.2, 59.2, 60.2) by a friction welding method. The invention further relates to an electrochemical cell thus obtained.

Description

Description Title of the invention: Method for manufacturing an electrochemical device and associated device Technical field

[0001] The field of the invention is that of electrochemical reactors comprising a stack of electrochemical cells, such as fuel cells and electrolysers, and relates more particularly to bipolar plates, of the conductive sheet type. STATE OF THE PRIOR ART

[0002] An electrochemical reactor, such as a fuel cell or an electrolyzer, usually comprises a stack of electrochemical cells, each of which includes an anode and a cathode electrically separated from each other by an electrolyte. The assembly consisting of the electrolyte and the two electrodes is known as the "cell core" or "membrane electrode assembly." A membrane electrode assembly, commonly called a cell core and also referred to by the acronym MEA, is the basic element of an electrochemical cell. It is composed of a polymer membrane and catalytic layers present on either side of the membrane. The membrane therefore separates the anodic and cathodic compartments. The catalytic layers are generally made of platinum nanoparticles supported on carbon aggregates.Carbon fabric or felt gas diffusion layers (also known as GDL for "Gas Diffusion Layer") are arranged on either side of the membrane-electrode assembly to ensure electrical conduction, the homogeneous arrival of reactants and the evacuation of products. Conventionally, a polymer frame ("RIM" in English) surrounds and holds together the elements of the MEA: membrane-electrodes-catalytic layers-gas diffusion layers.

[0003] Electrochemical cells are the site of an electrochemical reaction between two continuously introduced reactive fluids.

[0004] Generally speaking, in the case of a fuel cell, the combustible fluid (e.g. hydrogen) is supplied to the anode, while the oxidizing fluid (e.g. air) is supplied to the cathode. The electrochemical reaction is subdivided into two half-reactions, an oxidation reaction and a reduction reaction, which take place respectively at the anode / electrolyte interface and at the cathode / electrolyte interface. To take place, the electrochemical reaction requires the presence of an ionic conductor between the two electrodes, namely the electrolyte, for example, contained in a polymer membrane, and an electronic conductor formed by the electrical circuit. SUBSTITUTION SHEET (RULE 26) external. The stack of cells is thus the site of the electrochemical reaction: the reactive fluids must be brought in, the products and non-reactive species must be removed, as must the heat produced during the reaction.

[0005] The electrochemical cells are separated from each other by bipolar plates which ensure the electrical interconnection between them and the flow of the reactive fluids. The bipolar plates have an anodic face at which a distribution circuit for the combustible fluid is formed, and an opposite cathodic face at which a distribution circuit for the oxidizing fluid is formed. Each distribution circuit takes the form of a network of channels arranged to bring the reactive fluid to the corresponding electrode. The bipolar plates may also have a cooling circuit formed by a network of internal conduits which ensure the flow of a heat transfer fluid making it possible to evacuate the heat produced locally during the electrochemical reaction by the cell.

[0006] [Fig. 1] is a schematic and partial view of an example of a bipolar plate 1, of the conductive sheet type, seen from above and from the cathode side. [Fig. 2] is a cross-sectional view of the bipolar plate 1 of [Fig. 1] along the section line II-II.

[0007] The bipolar plate 1 comprises two conductive metal sheets 10, 20 superimposed on each other. The conductive sheets 10, 20 each comprise a distribution circuit 7 adapted to convey a reactive fluid to the corresponding electrode. The distribution circuits 7 are superimposed on each other, and define, in the XY plane, the reaction zone of the electrochemical cell. An air collector 2 and a hydrogen collector 3 are adjacent to each other, and are here separated by a collector 4 of the heat transfer liquid. These collectors 2, 3, 4 are arranged, in the XY plane, opposite the inlet of the distribution circuit 7. The air collector 2 is adapted to supply the distribution circuit 7 with air, here via an injection zone 8 then a homogenization zone 9.

[0008] The conductive sheets 10, 20 comprise ribs superimposed two by two, and associated with sealing gaskets, which participate in ensuring the sealing of the bipolar plate. Thus, an upper rib 15 and a lower rib 25, called collector ribs, form a collector sealing line 14 which each surrounds a collector in the XY plane, here the collector sealing line 14 surrounds the air collector 6. They are in contact with so-called collector sealing gaskets 6, and make it possible to prevent the reactive fluids from flowing on the same side of the bipolar plate 1 and from mixing. In addition, an upper rib 12 and a lower rib 22, called external, form an external sealing line 24 which extends over the periphery of the bipolar plate 1 and surrounds the collectors 2, 3, 4 and the distribution circuits 7 in the XY plane. They are in contact with sealing gaskets 5 said to be external, and make it possible to prevent the reactive fluids from flowing outside the bipolar plate 1. The upper ribs 12, 15 have the same profile as the respective lower ribs 22, 25, this profile being defined so as to provide the desired mechanical resistance and elasticity.

[0009] Furthermore, the ribs are bordered by flat portions. The flat portions 11, 13, 16 of a conductive sheet are superimposed and in contact with the flat portions 21, 23, 26 of the opposite conductive sheet at the level of the same reference plane P ref(parallel to the XY plane). Thus, if we consider the upper sheet 10 (cathodic), an external flat portion 11 extends between the external upper rib 12 and the edge of the bipolar plate 1; an intermediate flat portion 13 extends between the external upper rib 12 and the upper collector rib 15; and an internal flat portion 16 extends between the upper collector rib 15 and the edge of the air collector 2.

[0010] Thus, in operation, the air is supplied by the inlet manifold 2, flows through the injection zone 8 then the homogenization zone 9, and comes into contact with the cathode by means of the distribution circuit 7. The unconsumed air then flows through the homogenization zone, the injection zone, to finally reach the outlet manifold 2 (see solid arrows in [Fig.1]). The same applies to the hydrogen on the anode side.

[0011] Conventionally, the conductive sheets 10 and 20 are made by stamping or hydroforming stainless steel or titanium plates. These materials are very good electrical conductors and offer adequate mechanical strength. They also have excellent barrier properties, particularly to limit the diffusion of hydrogen. However, the weak point of such metals is their low resistance to corrosion and pollution of the membrane by the cations formed during this degradation is often observed, prematurely altering the performance and durability of the battery. It is then necessary to carry out surface treatments of the conductive sheets 10 and 20 thus produced.The resulting bipolar plate is heavy, expensive and the available surface treatments are also expensive and do not guarantee significant durability for applications where lifespan is an important factor such as automotive type mobility applications. SUBJECT OF THE INVENTION

[0012] The object of the invention is to improve the technical and economic performance of an electrochemical cell. Statement of the invention

[0013] For this purpose, a method of manufacturing an electrochemical cell is provided. comprising at least one bipolar plate and a membrane-electrode assembly, the method comprising the following steps of manufacturing the bipolar plate: - providing a first element made of a first polymer composite material impregnated with resin of a second thermoplastic polymer material, the first element comprising a first rib, which is bordered by two first connecting portions; - providing a second element made of a third material impregnated with resin of a fourth thermoplastic polymer material, the second element comprising a second rib which is bordered by two second connecting portions; - presenting the first element opposite the second element so that a first connecting portion extends opposite a second connecting portion; - making a first junction of a first connecting portion on a second connecting portion by a friction welding process, preferably an ultrasonic welding process.

[0014] A bipolar plate 1 is then obtained comprising a first panel and a second polymer panel connected by ultrasonic welding. Such welding is economical to produce, has high repeatability and is easily controllable. The use of polymer plates makes it possible to reduce the mass of the bipolar plates and the electrochemical cell.

[0015] According to other particular, non-exclusive and optional embodiments of the invention: - the first material and / or the second material is reinforced with conductive fibers and / or an electrically conductive filler; - the first material and / or the second material comprises graphite, carbon black, carbon fibers and / or carbon nanotubes; - the first material and / or the second material are chosen from the following materials: Polyethylene naphthalate, Polyetheretherketone, polyetherimide, fluorinated ethylene propylene; - the third thermoplastic polymer material and / or the fourth thermoplastic polymer material comprise fluorinated ethylene-propylene; - the step of making the first junction comprises a welding step whose duration is between one and four seconds, preferably equal to two seconds; - the method comprises a first additional step prior to the production of the first junction of adding a first film comprising a fifth thermoplastic polymer between the first element and the second element ; - the method also comprises the following additional second steps: • present the membrane-electrode assembly opposite the first element so that the membrane-electrode assembly extends opposite the first rib, the membrane-electrode assembly being preferentially in contact with the first rib; • make a second junction of the membrane-electrode assembly on the first rib by a friction welding process, preferably an ultrasonic welding process; - the method comprises a third additional step prior to the production of the second junction of adding a second film between the first element and / or between the membrane-electrode assembly and the second element; - the second film comprises a fifth thermoplastic polymer and / or the second film comprises at least one insert of calibrated glass beads or glass fibers; - the first connecting portion and the second connecting portion respectively comprise a first and a second connecting block, the step of making a first junction of a first connecting portion on a second connecting portion by a friction welding method comprising a step of joining the first connecting block and the second connecting block.

[0016] The invention also relates to an electrochemical cell comprising at least one bipolar plate and a membrane-electrode assembly, the bipolar plate comprising: - a first element made of a first material impregnated with resin of a second thermoplastic polymer material, the first element comprising a first rib which is bordered by two first connecting portions, - a second element made of a third material impregnated with resin of a fourth thermoplastic polymer material, the second element comprising a second rib which is bordered by two first connecting portions, in which

[0017] the first connecting portion is connected to the second connecting portion by friction welding, preferably ultrasonic welding.

[0018] Other characteristics and advantages of the invention will appear on reading the following description of a particular non-limiting embodiment of the invention. Brief description of the drawings

[0019] Reference will be made to the attached figures, including:

[0020] [Fig.1] [Fig.1] is a partial schematic representation in top view of a prior art bipolar plate;

[0021] [Fig.2] [Fig.2] is a partial schematic cross-sectional representation of a turbomachine;

[0022] [Fig.3] [Fig.3] is a partial schematic representation of a first step of the manufacturing method according to a first embodiment of the invention;

[0023] [Fig.4] [Fig.4] is a partial schematic representation of a second step of the manufacturing method according to the first embodiment of the invention;

[0024] [Fig.5] [Fig.5] is a partial schematic representation of a third and fourth step of the manufacturing method according to the first embodiment of the invention;

[0025] [Fig.6] [Fig.6] is a partial schematic representation of a fifth and sixth step of the manufacturing method according to the first embodiment of the invention;

[0026] [Fig.7] [Fig.7] is a partial schematic representation of a step of the manufacturing method according to a second embodiment of the invention;

[0027] [Fig.8] [Fig.8] is a partial schematic representation of an assembly step of the manufacturing method according to the second embodiment of the invention;

[0028] [Fig.9] [Fig.9] is a partial schematic representation of a joining step of the manufacturing method according to the second embodiment of the invention;

[0029] [Fig.10] [Fig.10] is a partial schematic representation of an electrochemical cell obtained at the end of the manufacturing process according to the second embodiment of the invention;

[0030] [Fig.11] [Fig.11] is a partial schematic representation of a preparation step of the manufacturing method according to a third embodiment of the invention;

[0031] [Fig.12] [Fig.12] is a partial schematic representation of an electrochemical cell obtained at the end of the manufacturing process according to the third embodiment of the invention.

[0032] DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

[0033] With reference to [Fig. 3] and according to a first step of the manufacturing process of the bipolar plate 1, a first panel 30 of ethylene polynapthalate reinforced with conductive nanotubes 3 and which is impregnated at the core with a fluorinated ethylene-propylene resin 32 is provided. The first panel 30 has a first upper face 30.10 and a first lower face 30.20.

[0034] The panel 30 comprises a first left rib 34 (as shown in [Fig. 3]), a first central rib 35 and a first right rib 36. The rib 34 is bordered by a first left end connecting portion 37 and a first left intermediate connecting portion 38. The rib 35 is bordered by the connecting portion 38 and a first right intermediate connecting portion 39. The rib 36 is bordered by the connecting portion 39 and a first right end connecting portion 40.

[0035] Similarly, and according to a second step of the method shown in [Fig.4], a second panel 50 of ethylene polynapthalate reinforced with conductive nanotubes 5 let is provided, which is impregnated at the core with a fluorinated ethylene-propylene resin 52. The second panel has a second upper face 50.10 and a second lower face 50.20.

[0036] The membrane panel 50 comprises a second left rib 54 (as shown in [Fig. 4]), a second central rib 55 and a second right rib 56. The rib 54 is bordered by a second left end connecting portion 57 and a second left intermediate connecting portion 58. The rib 55 is bordered by the connecting portion 58 and a second right intermediate connecting portion 59. The rib 56 is bordered by the connecting portion 59 and a second right end connecting portion 60.

[0037] For reasons of conciseness and clarity of the description, only one central rib 35- respectively 55- has been described, the invention obviously applies to plates 30 and 50 comprising a plurality of central ribs 35 and 55, as signified by the truncation symbols shown in the figures.

[0038] According to a third step represented in [Fig.5], the panel 30 is presented opposite the panel 50 so that the first connecting portions 37 to 40 extend respectively opposite the second connecting portions 57 to 60.

[0039] According to a fourth optional step (which constitutes a first additional step), a first film 70 of fluorinated ethylene-propylene is added between the panel 30 and the panel 50, which film comprises perforations 71 whose shapes correspond to the ribs 34 to 36, 54 to 56 and to the connecting portions 38, 39, 58 and 59. In other words, the film 70 comprises solid zones 72 delimited by perforations 71 and which extend between the connecting portions 37 and 57, as well as 40 and 60.

[0040] According to a fifth step shown in [Fig.6], the panels 30 and 50 are brought into contact with the film 70. In doing so, the connecting portions 37 to 40 and 57 to 60 come into contact with the solid zones 72. A stack 75 is then obtained consisting of the panel 30, the film 70 and the panel 50.

[0041] The junction of panels 30 and 50 is carried out using a welding assembly by ultrasound 80 during a sixth step. The assembly 80 comprises an anvil 81 and a sonotrode 82 connected by an amplifier 83 to an ultrasonic pulse transmitter 84.

[0042] The anvil 81 has two horns 81.1 and 81.2 which respectively bear on the connecting portions 57 and 60 of the panel 50. The sonotrode 82 comprises, for its part, two applicators 82.1 and 82.2 which respectively bear on the connecting portions 37 and 40 of the panel 30. The junction of the left terminal connection 37 on the second left terminal connection portion 57 as well as the junction of the right terminal connection 40 on the second right terminal connection portion 60 are carried out by ultrasonic welding by activating the emitter 84 for a duration of between one and four seconds, preferably equal to two seconds (eighth step).

[0043] For reasons of clarity and conciseness, the invention has been described in connection with a section of the bipolar plate, it clearly appears that the sonotrode 82 and the anvil 81 have a shape adapted to the production of the junction by welding of the sealing line 5 and / or 14.

[0044] A bipolar plate 1 is then obtained comprising a first panel 30 and a second panel 50 which comprise a first connecting portion 37 which is connected to a second connecting portion 57 by ultrasonic welding. Such a weld is easily characterized using a metallographic type examination known to those skilled in the art and can also be recognized, in most cases, by simple visual examination and tested for gas tightness (nitrogen) by pressure drop: a pressure of 0.5 bars relative is applied, the gas supply is stopped and it is checked whether the pressure is stable. If this is the case, the component is sealed and compliant in terms of gas tightness, therefore the weld is also compliant.

[0045] Such a bipolar plate can then be used to produce an electrochemical cell according to methods known to those skilled in the art.

[0046] Elements identical or analogous to those previously described will bear a numerical reference identical to this one in the following description of a second and a third embodiment of the invention.

[0047] According to a second embodiment shown in [Fig.7], a first membrane-electrode assembly 90 comprises a first membrane 91 whose first upper face 91.1 carries a first anode 92 and whose first lower face 91.2 carries a first cathode 93. A first layer 110 of gas diffusion felt extends opposite the cathode 93. The first membrane-electrode assembly 90 comprises a first frame 90.1 made of ethylene polynapthalate. The frame 90.1 extends around the periphery of the membrane-electrode assembly 90 and also holds the first layer 110 in place.

[0048] A second membrane-electrode assembly 94 comprises a second membrane 95 whose second upper face 95.1 carries a second anode 96 and whose second lower face 95.2 carries a second cathode 97. A second layer 120 of gas diffusion felt extends facing the anode 96 and a third layer 130 of gas diffusion felt extends facing the cathode 97. The second membrane-electrode assembly 94 comprises a second frame 94.1 made of polyethylene napthalate. Optionally, in the case where the composite of the frame 94.1 does not comprise sufficient polymer (too high a carbon load), an additional polymer frame can be inserted between the ribs 54.1 / 56.1 and the membrane-electrode assembly 94. The frame 94.1 extends at the periphery of the membrane-electrode assembly 94 and also holds the second layer 120 and the third layer 130 in place.Finally, a third membrane-electrode assembly 98 comprises a third membrane 99 whose third upper face 99.1 carries a third anode 100 and whose third lower face 99.2 carries a third cathode 101. A fourth layer 140 of gas diffusion felt extends opposite the anode 100. The third membrane-electrode assembly 98 comprises a third frame 98.1 made of ethylene polynapthalate impregnated at the core with a fluorinated ethylene-propylene resin. The frame 98.1 extends at the periphery of the membrane-electrode assembly 98 and also holds the fourth layer 140 in place. A first stack 75-referenced 75.1 and composed of a panel 30.1 and a panel. 50.1 - is placed between the assembly 90 and the assembly 94 so as to extend between the cathode 93 and the anode 96. A second stack 75-referenced 75.2 and composed of a panel 30.2 and a panel 50.2- is placed between the assembly 94 and the assembly 98 so as to extend between the cathode 97 and the anode 100 ([Fig.8]).

[0049] A second film 105 of fluorinated ethylene-propylene is added between the cathode 93 and the stack 75.1. The second film 105 extends opposite the cathode 93 and comprises a perforation 106 whose shape corresponds to the rib 35 (referenced 35.1 for panel 30.1) and to the connecting portions 38 (referenced 38.1 for panel 30.1) and 39 (referenced 39.1 for panel 30.1). In other words, the film 105 comprises solid zones 107 which extend directly above the ribs 34 (referenced 34.1 for panel 30.1) and 36 (referenced 36.1 for panel 30.1).

[0050] Symmetrically, a third film 115 of fluorinated ethylene-propylene is added between the stack 75.1 and the anode 96. The third film 115 extends opposite the anode 96 and comprises a perforation 116 whose shape corresponds to the rib 55 (referenced 55.1 for the panel 50.1) and to the connecting portions 58 (referenced 58.1 for the panel 50.1) and 59 (referenced 59.1 for the panel 50.1). In other words, the film 115 comprises solid zones 117 which extend directly above the ribs 54 (referenced 54.1 for the panel 50.1) and 56 (referenced 56.1 for the panel 50.1).

[0051] Identicaly, a fourth film 125 of fluorinated ethylene-propylene is added between the cathode 97 and the stack 75.2. The fourth film 125 extends opposite the cathode 97 and comprises a perforation 126 whose shape corresponds to the rib 35 (referenced 35.2 for panel 30.2) and to the connecting portions 38 and 39 (referenced 38.2 and 39.2 for panel 30.2). In other words, the film 125 comprises solid zones 127 which extend directly above the ribs 34 and 36 (referenced 34.2 and 36.2 for panel 30.2).

[0052] Symmetrically, a fifth film 135 of fluorinated ethylene-propylene is added between the stack 75.2 and the anode 100. The fifth film 135 extends opposite the anode 100 and comprises a perforation 136 whose shape corresponds to the rib 55 (referenced 55.2 for the panel 50.2) and to the connecting portions 58 and 59 (referenced 58.2 and 59.2 for panel 50.2). In other words, the film 135 comprises solid zones 137 which extend directly above the ribs 54 and 56 (referenced 54.2 and 56.2 for panel 30.2).

[0053] As visible in [Fig.8], and according to an advantageous embodiment, the film 105 comprises an insert 108 of glass beads 109 which extends in line with the rib 35.1 the film 115 comprises an insert 118 of glass beads 119 which extends directly above the rib 55.1. The film 125 comprises an insert 128 of glass beads 129 which extends directly above the rib 35.2 and the film 135 comprises an insert 138 of glass beads 139 which extends directly above the rib 55.2.

[0054] The junction of panels 30 and 50 is carried out using an anvil 81 adapted to carrying out four welds simultaneously.

[0055] The anvil 81 has four additional horns 81.3, 81.4, 81.5 and 81.6. The first additional horn 81.3 and the second additional horn 81.4 support the frame 98.1. The first additional horn 81.3 is located directly above the ribs 34.1, 54.1, 34.2, 54.2 and the second additional horn 81.4 is located directly above the ribs 36.1, 56.1, 36.2, 56.2. The third additional horn 81.5 comes into contact with the left end connecting portion 57.2 of the panel 50.2 and the fourth additional horn 81.6 comes into contact with the right end connecting portion 60.2 of the panel 50.2.

[0056] The sonotrode 82 comprises, for its part, four additional applicators 82.3, 82.4, 82.5 and 82.6. The first additional applicator 82.3 and the second additional applicator 82.4 come to bear on the frame 90.1. The first additional applicator 82.3 is located directly above the ribs 34.1, 54.1, 34.2, 54.2 and the second additional applicator 82.4 is located directly above the ribs 36.1, 56.1, 36.2, 56.2. The third additional applicator 82.5 comes into contact with the left terminal connection portion 37.2 of the panel 30.2 of the second stack 70.2 and the fourth additional applicator 82.6 comes into contact with the portion of right terminal connection 40.2 of panel 30.2 of second stack 75.2.

[0057] After activation of the transmitter 84, the following junctions are made by ultrasonic welding ([Fig.9]): - junction of the left terminal connection 37.1 of the first plate on the second portion of the left terminal connection 57.1; - junction of the right terminal link 40.1 on the second portion of the right terminal link 60.1; - junction of the left terminal connection 37.2 of the first plate on the second portion of the left terminal connection 57.2; - junction of the right terminal connection 40.2 on the second portion of the right terminal connection 60.2 Junction of the frame 90.1 on the ribs 34.1 and 36.1; - junction of frame 94.1 on ribs 54.1 and 56.1; - junction of frame 94.1 on ribs 34.2 and 36.2; - junction of frame 98.1 on ribs 54.2 and 56.2.

[0058] The glass beads 109, 119, 129 and 139 of the inserts 108, 118, 128 and 138 make it possible, by acting as mechanical shims, to limit the crushing of the gas diffusion layers 110, 120, 130 and 140.

[0059] Such a set of bipolar plates 1 and membrane-electrode assemblies 90, 94 and 98 is advantageously incorporated into the manufacture of an electrochemical cell 1000 ([Fig.11]) according to methods known to those skilled in the art.

[0060] According to a third embodiment of the invention shown in [Fig.l 1], the panel 30.1 comprises a first solid left junction block 230.1 of height substantially identical to that of the rib 34.1 and a first right junction block 240.1 solid with a height substantially identical to that of rib 36.1. The panel 50.1 includes a second solid left junction block 250.1 of height substantially identical to that of rib 54.1 and a second right junction block 260.1 massif of height substantially identical to that of rib 56.1.

[0061] Similarly, the panel 30.2 comprises a third solid left junction block 230.2 of height substantially identical to that of the rib 34.2 and a third solid right junction block 240.2 of height substantially identical to that of the rib 36.2. The panel 50.2 comprises a fourth left junction block 250.2 solid block of height substantially identical to that of rib 54.2 and a fourth straight junction block 260.2 solid block of height substantially identical to that of rib 56.2.

[0062] Blocks 230.1 and 240.1 are located to extend opposite the edges of frame 90.1. Blocks 250.1, 260.1, 230.2 and 240.2 are located to extend opposite the edges of frame 94.1. Blocks 250.2 and 260.2 are located to extend opposite the edges of frame 98.1.

[0063] The other steps described for the second embodiment apply.

[0064] According to this third embodiment, the sonotrode 80 then exclusively comprises the applicators 82.3 and 82.4 and the anvil exclusively comprises the horns 81.3 and 81.4. After activation of the emitter 84, the following junctions are made by ultrasonic welding ([Fig.12]): - junction of plate 90.1 on block 230.1 and block 240.1; - junction of block 230.1 on block 250.1; - junction of block 240.1 on block 260.1; - junction of plate 94.1 on block 250.1 and block 260.1; - junction of plate 94.1 on block 230.2 and block 240.2; - junction of plate 98.1 on block 250.2 and block 260.2.

[0065] The blocks 230.1, 240.1, 250.1, 260.1, 230.2, 240.2, 250.2, 260.2 being massive they ensure efficient transmission of ultrasonic mechanical energy and contribute to improving the quality of the welds.

[0066] Of course, the invention is not limited to the embodiments described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0067] Especially,

[0068] - although the steps of the method of manufacturing an electrochemical cell have been described one after the other, the invention also applies to a method in which certain steps are carried out simultaneously or in a different order;

[0069] - although here the bipolar plate comprises a first and a second polynaphthalate panel, the invention also applies to other types of first and second polymer composite elements such as for example first and second molded elements, on which the ribs have been formed during molding;

[0070] - although here the first panel is made of Polyethylene naphthalate, the invention also applies to other types of first conductive polymer material such as for example Polyetheretherketone, polyetherimide, fluorinated ethylene propylene;

[0071] - although here the first panel is impregnated with fluorinated ethylene propylene, the invention also applies to other types of third thermoplastic polymer material such as for example polyethylene (PE), high density polyethylene (HDPE), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), polyamide (PA). Preferably, an electrically conductive composite impregnated with polymer is selected. If it is necessary to make an assembly with a membrane-electrode assembly between components made of different polymers, it is then preferable to select two polymers having a close melting temperature in order to be able to weld them together them. Finally, the selected polymers may present characteristics improving their resistance to the environments / atmospheres of the operation of a battery without deterioration;

[0072] - although here the second panel is impregnated with fluorinated ethylene propylene, the invention also applies to other types of fourth thermoplastic polymer material such as for example polyethylene (PE), high density polyethylene (HDPE), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), polyamide (PA);

[0073] - although here the first panel is made of ethylene polynaphthalate, the invention also applies to other types of third conductive polymer material such as for example polyetheretherketone, polyetherimide, fluorinated ethylene propylene;

[0074] - although here the second panel is reinforced by carbon nanotubes, the invention also applies to other types of reinforcement such as for example reinforcement by conductive fibers and / or an electrically conductive filler in materials such as graphite, carbon black, carbon fibers and / or carbon nanotubes;

[0075] - although here the first film is made of ethylene polynaphthalate, the invention also applies to other types of fifth thermoplastic material such as for example polyetheretherketone, polyetherimide, fluorinated ethylene propylene;

[0076] - although here the second film is made of Polyethylene naphthalate, the invention also applies to other types of thermoplastic material such as for example Polyetheretherketone, polyetherimide, fluorinated ethylene propylene

[0077] - although here the assembly is carried out by ultrasonic welding, the invention also applies to other types of friction welding process such as for example a friction / stirring process;

[0078] - although here the films comprise two glass bead inserts, the invention also applies to films comprising a single insert or more than two;

[0079] - although here the inserts comprise glass beads, the invention also applies to other types of compression limiting elements such as for example calibrated glass fibers;

[0080] - although here the glass bead inserts are an integral part of the second, third, fourth and fifth films, the invention also applies to other types of inserts such as inserts independent of the films or integral with additional films;

[0081] - although here the frame is made of polyethylene naphthalate, the invention also applies to other types of composite materials for making the frame, or even a frame made of a thermoplastic material.

[0082]

Claims

Claims

1. A method of manufacturing an electrochemical cell (1000) comprising at least one bipolar plate (1) and a membrane-electrode assembly (90, 94, 98), the method comprising the following steps of manufacturing the bipolar plate (1): - providing a first element (30, 30.1) made of a first polymer composite material impregnated with resin of a second thermoplastic polymer material, the first element comprising a first rib (34, 36, 34.1, 36.1, 34.2, 36.2), which is bordered by two first connecting portions (37, 38, 39, 40, 37.1, 38.1, 39.1, 40.1, 37.2, 38.2, 39.2, 40.2); - providing a second element (50, 50.1) made of a third resin-impregnated material of a fourth thermoplastic polymer material, the second element comprising a second rib (54, 56, 54.1, 56.1, 54.2, 56.2) which is bordered by two second connecting portions (57, 58, 59, 60, 57.1, 58.1, 59.1, 50.1, 57.2, 58.2, 59.2, 60.2); - presenting the first element (30, 30.1) opposite the second element (50, 50.1) so that a first connecting portion (37, 38, 39, 40, 37.1, 38.1, 39.1, 40.1, 37.2, 38.2, 39.2, 40.2) extends opposite a second connecting portion (57, 58, 59, 60, 57.1, 58.1, 59.1, 50.1, 57.2, 58.2, 59.2, 60.2); - make a first junction of a first connecting portion (37, 38, 39, 40, 37.1, 38.1, 39.1, 40.1, 37.2, 38.2, 39.2, 40.2) on a second connecting portion (57, 58, 59, 60, 57.1, 58.1, 59.1, 50.1, 57.2, 58.2, 59.2, 60.2) by a friction welding process, preferably an ultrasonic welding process.

2. A manufacturing method according to claim 1, wherein the first material and / or the second material is reinforced with conductive fibers (31, 51) and / or an electrically conductive filler.

3. A manufacturing method according to claim 2, wherein the first material and / or the second material comprises graphite, carbon black, carbon fibers and / or carbon nanotubes (31, 51)

4. Manufacturing method according to any one of the preceding claims, wherein the first material and / or the second material are chosen from the following materials: Polyethylene naphthalate, Polyetheretherketone, polyetherimide, fluorinated ethylene propylene.

5. A manufacturing method according to any preceding claim, wherein the third thermoplastic polymer material and / or the fourth thermoplastic polymer material comprises fluorinated ethylene-propylene.

6. Manufacturing method according to any one of the preceding claims, in which the step of making the first junction comprises a welding step whose duration is between one and four seconds, preferably equal to two seconds.

7. Manufacturing method according to any one of the preceding claims, comprising a first additional step prior to the production of the first junction of adding a first film (70) comprising a fifth thermoplastic polymer between the first element (30, 30.1) and the second element (50, 50.1).

8. A manufacturing method according to any preceding claim, also comprising the following additional second steps: - presenting the membrane-electrode assembly (90, 94, 98) opposite the first element (30, 30.1) so that the membrane-electrode assembly (90, 94, 98) extends opposite the first rib (34, 36, 34.1, 36.1, 34.2, 36.2), the membrane-electrode assembly (90, 94, 98) being preferentially in contact with the first rib (34, 36, 34.1, 36.1, 34.2, 36.2); - making a second junction of the membrane-electrode assembly (90, 94, 98) on the first rib (34, 36, 34.1, 36.1, 34.2, 36.2) by a friction welding process, preferably an ultrasonic welding process.

9. Manufacturing method according to claim 8, comprising a third additional step prior to the production of the second junction of adding a second film (105, 125) between the membrane-electrode assembly (90, 94, 98) and the first element (30, 30.1, 30.2) and / or between the membrane-electrode assembly (90, 94, 98) and the second element (50, 50.1, 50.2).

10. Manufacturing method according to claim 9, in which the second film comprises a fifth thermoplastic polymer.and / or the second film (105, 125) comprises at least one insert (108, 118, 128, 138) of glass beads (109, 119, 129, 139) or calibrated glass fibers which come into contact with the two first connecting portions (37, 38, 39, 40, 37.1, 38.1, 39.1, 40.1, 37.2, 38.2, 39.2, 40.2).

11. A manufacturing method according to any preceding claim, wherein the first connecting portion (37, 38, 39, 40, 37.1, 38.1, 39.1, 40.1, 37.2, 38.2, 39.2, 40.2) and the second connecting portion (57, 58, 59, 60, 57.1, 58.1, 59.1, 50.1, 57.2, 58.2, 59.2, 60.2) respectively comprise a first and a second connecting block, the step of making a first junction of a first connecting portion (37, 38, 39, 40, 37.1, 38.1, 39.1, 40.1, 37.2, 38.2, 39.2, 40.2) on a second connecting portion (57, 58, 59, 60, 57.1, 58.1, 59.1, 50.1, 57.2, 58.2, 59.2, 60.2) by a friction welding method comprising a step of joining the first connecting block and the second connecting block.

12. Electrochemical cell (1000) comprising at least one bipolar plate (1) and a membrane-electrode assembly (90, 94, 98), the bipolar plate (1) comprising: - a first element (30, 30.1) made of a first material impregnated with resin of a second thermoplastic polymer material, the first element (30, 30.1) comprising a first rib (34, 36, 34.1, 36.1, 34.2, 36.2) which is bordered by two first connecting portions (37, 38, 39, 40, 37.1, 38.1, 39.1, 40.1, 37.2, 38.2, 39.2, 40.2), - a second element (50, 50.1) made of a third material impregnated with resin of a fourth thermoplastic polymer material, the second element (50, 50.1) comprising a second rib (54, 56, 54.1, 56.1, 54.2, 56.2) which is bordered by two first connecting portions (57, 58, 59, 60, 57.1, 58.1, 59.1, 50.1, 57.2, 58.2, 59.2, 60.2), wherein the first connecting portion (37, 38, 39, 40, 37.1, 38.1, 39.1, 40.1, 37.2, 38.2, 39.2, 40.2) is connected to the second connecting portion (57, 58, 59, 60, 57.1, 58.1, 59.1, 50.1, 57.2, 58.2, 59.2, 60.2) by a weld by friction, preferably ultrasonic welding.

Images