Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M12/00—Hybrid cells; Manufacture thereof
  • H01M12/04—Hybrid cells; Manufacture thereof composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type
  • H01M12/06—Hybrid cells; Manufacture thereof composed of a half-cell of the fuel-cell type and of a half-cell of the primary-cell type with one metallic and one gaseous electrode
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M12/00—Hybrid cells; Manufacture thereof
  • H01M12/08—Hybrid cells; Manufacture thereof composed of a half-cell of a fuel-cell type and a half-cell of the secondary-cell type
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
  • H01M4/8605—Porous electrodes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
  • H01M4/88—Processes of manufacture

Definitions

• the present invention relates to the technical field of the production of electricity by electrochemical reaction in the context of cells, fuel cells or electric batteries.
• the invention relates more particularly to an air electrode implemented in such cells or batteries as well as its method of manufacture.
• the invention finds a particularly advantageous application in metal-air batteries, for example for light electric vehicles (electric bicycles or scooters) or for electric or hybrid vehicles (cars, boats, drones).
• a metal-air battery is an electrochemical generator using the spontaneous oxidation reaction between a metal and oxygen to produce an electric current. It conventionally comprises a cathode in contact with the ambient air, a metal anode which is the site of the oxidation of the metal, and a solution containing an electrolyte and separating the anode and the cathode.
• the metal-air battery advantageously uses ambient air as a source of oxygen in order to produce electricity. It is therefore not necessary to store oxygen in a tank to operate the battery.
• the metal-air battery thus has a high specific energy for a low cost.
• the anode is generally made of pure metal, for example lithium, zinc, magnesium, aluminum or iron.
• battery discharge i.e. when it produces electricity
• the anode undergoes oxidation and releases electrons to an external electrical circuit.
• oxygen present in the ambient air diffuses through the cathode, hence its name of air electrode.
• the air electrode captures the electrons coming from the anode, which thus allows the reduction of oxygen into oxygenated species of the ionic type.
• the electrolyte typically in aqueous solution, allows the migration of dissociated metal ions and the oxygenated species produced, the latter combining to form metal hydroxides.
• the air electrode is thus the site of the oxygen reduction reaction (more specifically gaseous oxygen contained in the air) into conductive ions in the solution.
• the air electrode is a key part of the metal-air battery. Indeed, the good performance of the metal-air battery stems directly from the effectiveness of the air electrode in reducing oxygen and the latter represents the most expensive element of the battery.
• the air electrode is flat overall and its thickness comprises three layers: a catalytic layer, a diffusion layer and a current collector.
• the catalytic layer also called active layer or surface, is composed of carbon, a catalyst (such as platinum or platinum alloys) and a binder.
• the catalytic layer is in contact with the solution and promotes the reduction of oxygen at the triple interface between the electrolyte contained in the solution, the oxygen and the catalyst.
• the diffusion layer absorbs oxygen from the surrounding air and transports it to the catalytic sites. It is made of carbon and a hydrophobic polymer designed to seal the electrode at the air inlet.
• the current collector is a metallic material which efficiently transports electrons from the external electrical circuit.
• the current collector is preferably placed in contact with the catalytic layer.
• the current collector is thus conventionally a porous and/or alveolar material which is sandwiched between the catalytic layer and the diffusion layer.
• an air electrode comprising:
• a current collector having two opposite main faces; - a catalytic layer extending over a first main face and intended to be in contact with a solution containing an electrolyte;
• the gas containing oxygen (more specifically gaseous dioxygen) is ambient air.
• the gasket is designed to be solution impermeable, which in practice means that the gasket is impermeable to aqueous solutions.
• the seal is electrically conductive in the sense that it allows the passage of an electric current, unlike materials considered as electrical insulators.
• the seal makes it possible, on the one hand, to improve current collection by increasing the conductivity of the collector-seal assembly. Indeed, the seal improves current collection by increasing the number of charge carriers within the current collector since it fills part of the pores of the latter with a conductive material.
• the seal improves the quality of the electrical connection between the external electrical circuit and the current collector.
• the seal makes it possible to increase the surface of the electrical contact between the external electrical circuit and the current collector insofar as the entire surface of the seal can be used for this electrical connection and where it levels the porous surface of the current collector. current and therefore increases its usable area for connection.
• the seal according to the invention therefore makes it possible to collect higher current densities by reducing the ohmic losses so that a metal-air battery equipped with the air electrode according to the invention can produce more electrical power. high for an equivalent size.
• an air-aluminum battery comprising an air electrode according to the invention with a catalytic layer of 25 cm 2 could generate a power density greater than 310 mW/cm 2 .
• the seal according to the invention makes it possible, on the other hand, to prevent the risk of solution leaks in that it blocks the percolation of the solution towards the area of the current collector used for connection to the external electrical circuit.
• the seal fills its pores with an impermeable material.
• the catalytic layer extends only over a central region of the first main face of the current collector.
• the current collector thus has, at the level of the first main face, at least one peripheral region which is complementary to the central region and which offers an adequate surface for connecting the external electric circuit to the current collector.
• the catalytic layer extends at a distance from at least part of the peripheral edge of the current collector, and preferably, the catalytic layer extends over the central region at a distance non-zero of a perimeter of the current collector over the entire perimeter or peripheral edge.
• the aforementioned peripheral region therefore extends all along the periphery of the current collector, which offers a current collection surface which is both large and both accessible, that is to say arranged in such a way that the connection with the external electrical circuit is simple to make.
• the seal forms a band surrounding the catalytic layer.
• the solution containing the electrolyte cannot leak laterally via the edges of the first main face.
• the seal is then arranged along the periphery of the current collector while impregnating the latter.
• the conductive peripheral seal defines at the periphery of the catalytic layer a region with a greater density of charge carriers than the rest of the catalytic layer and of the collector.
• the catalytic layer extends over more than half of the first main face, which makes it possible to generate high current densities thanks to an extended oxygen reduction active surface. and optimized with respect to the overall size of the electrode.
• the seal impregnates a thickness of the current collector of between 0.2 mm and 1 mm.
• the seal comprises a powder of an electrically conductive material and a resin or elastomer matrix in which the electrically conductive material is dispersed, or an electrically conductive resin.
• the joint comprises a powder metal and an elastomeric matrix in which the metal powder is dispersed.
• the elastomer matrix comprising, for example silicone, provides sealing while the metal powder gives the seal its electrically conductive character. Remarkably, such a seal is inexpensive to produce.
• This composition also makes it possible to deposit the joint when the elastomer matrix is still viscous (for example before polymerization), which facilitates in particular its impregnation in the current collector.
• the elastomeric matrix can advantageously have adhesive properties.
• the air electrode further comprises a metal reinforcement bonded to the first main face by the joint.
• the reinforcement makes it possible to consolidate the electrode, typically with a view to its integration into the battery. Since the reinforcement is metallic, it then constitutes a favorable connection surface for the external electrical circuit because it is smoother and more rigid than the current collector.
• the metal reinforcement has a flat surface, which further simplifies the connection with the external electrical circuit.
• the electrical contact and the mechanical contact (that is to say the adhesion) between the current collector and the reinforcement are both effectively ensured by the seal.
• the electrode can be manipulated by means of the reinforcement, which makes it possible not to degrade the catalytic layer, in particular during its integration into the metal-air battery or its removal therefrom.
• the electrode can be removed, for example for repair or replacement of the components of the battery, then put back within the battery without degradation of the catalytic layer and therefore without loss of performance.
• the metal reinforcement forms a belt having an opening of a shape complementary to that of the catalytic layer.
• the reinforcement surrounds the catalytic layer.
• the belt then constitutes a favorable connection surface for the external electrical circuit all around the electrode, which simplifies the integration of the electrode into the battery.
• the metal reinforcement offering a large contact surface with the conductive gasket, it helps to optimize current collection and reduces ohmic losses.
• the air electrode further comprises a second metal reinforcement located on the side of the second main face and in vis-à-vis the metal reinforcement bonded to the first main face.
• the air electrode is consolidated on either side, that is to say on the side of each main face.
• the second metal reinforcement has a shape identical to that of the first metal reinforcement, which makes it possible to consolidate the air electrode in a homogeneous manner.
• the electrode comprises a second seal tight to the solution and electrically conductive, bordering the diffusion layer and at least partially impregnating the current collector.
• the second gasket further improves the impermeability of the portion of the current collector that protrudes from the catalytic layer and the diffusion layer. It also increases the number of charge carriers in the current collector.
• the second metal reinforcement is bonded to the second main face by means of the second seal.
• the second reinforcement is also electrically connected to the current collector.
• the second reinforcement then constitutes a favorable connection surface for collecting the current on the side of the second main face.
• the second metal reinforcement forms a belt having an opening of complementary shape to that of the diffusion layer.
• the second reinforcement surrounds the diffusion layer, which provides a favorable external electrical circuit connection surface all around the air electrode.
• ambient air entering the air electrode is thus channeled through the diffusion layer.
• At least one of the metal powder, the first metal reinforcement, the second metal reinforcement and the current collector comprises nickel or stainless steel.
• nickel and stainless steel have very good conductivity and high resistance to corrosion. Thus, the service life and the electrochemical performance of the air electrode are increased.
• the current collector comprises a porous and/or cellular material
• the current collector is a metal foam plate or a grid;
• the metallic foam plate or the grid comprises nickel or stainless steel;
• the diffusion layer is permeable to gas and impermeable to the solution
• the diffusion layer comprises carbon and a hydrophobic polymer
• the catalytic layer is permeable to the solution and to the gas.
• the invention also proposes a metal-air battery comprising an air electrode as presented above.
• the metal-air battery according to the invention generates greater electrical power than conventional metal-air batteries.
• the invention finally proposes a method for manufacturing an air electrode comprising the following steps:
• the manufacturing method comprises a step of gluing a metal reinforcement by means of the seal.
• the catalytic layer and the diffusion layer are deposited by means of a roll-to-roll type process.
• the thicknesses of the catalytic layer and of the diffusion layer can thus be controlled very precisely.
• Figure 1 is a schematic view of a metal-air battery comprising an air electrode according to the invention.
• Figure 2 is a sectional view of the air electrode of Figure 1;
• Figure 3 is an exploded perspective view of the air electrode of Figure 1;
• Figure 4 is a block diagram of a sequence of steps for manufacturing the air electrode of Figure 1.
• the metal-air battery 100 comprises an air electrode 1 (playing the role of cathode), an anode 2, an external electrical circuit 3 connecting the air electrode 1 and the anode 2, and a solution 4 containing an electrolyte which is interposed between the anode 2 and the air electrode 1.
• the metal-air battery 1 also comprises a confinement chamber 5 designed to contain the solution 4. The containment enclosure 5 therefore opens on one side to the anode 2 and on the other to the air electrode 1 .
• ionic species transit from the air electrode 1 to the anode 2 while electrons (represented by the letter “e” in Figure 1) perform the reverse path through the external electrical circuit 3, which generates an electrical current.
• Solution 4 is an ionic aqueous solution containing salts which, once dissolved, constitute the electrolyte.
• Solution 4 is for example a solution of sodium, potassium or lithium hydroxide.
• the solution can be an acid solution, for example sulfuric or perchloric acid, or a basic one or even a molten salt such as alkali carbonates (Li2COs, Na2COs, K2CO3) or even a strong electrolyte such as a solution sodium chloride or potassium chloride.
• the air electrode 1 comprises:
• a diffusion layer 30 intended to be in contact with the gas 6;
• a first seal 40 and a second seal 50 both tight to the solution 4 and electrically conductive;
• the current collector 10 serves both to support the catalytic layer 20 and the diffusion layer 30 and to transport the electrons between the external electrical circuit 3 and the catalytic layer 20.
• the current collector 10 has open pores forming an interconnected network, which increases the contact surface with the catalytic layer 20 and the gas 6 to diffuse through the current collector 10 from the diffusion layer to the catalytic layer.
• the current collector 10 is for example made of a metal offering good resistance to corrosion under the conditions of use of the battery, preferably of stainless steel or nickel, to ensure efficient transport of the electrons.
• the current collector 10 has two main faces 11, 12 opposite each other: a first main face 11 on which the catalytic layer 20 extends and a second main face 12 on which the diffusion layer 30.
• main faces means the faces of larger dimensions, that is to say larger surfaces, of the current collector 10.
• intended to be in contact means that the catalytic layer 20 and the diffusion layer 30 are designed to be in contact, respectively with the solution 4 or the gas 6, and that they are once the air electrode 1 is mounted in a metal-air battery 100.
• the current collector 10 is a metal foam plate which has an open-pore honeycomb structure.
• the two main faces 11, 12 are then the two opposite faces of this plate.
• the current collector 10 can also be a mesh of woven and/or knitted or even needled conductive threads.
• the current collector 10 is here generally planar. As illustrated in Figure 3, the current collector 10 extends in a main plane P (corresponding to the plane of Figure 3) to which the two main faces 11, 12 are substantially parallel.
• the current collector 10 has a thickness, between its two main faces 11, 12, much less than its extension in the main plane P.
• the two main faces 11, 12 are here rectangular or square.
• the main faces 11, 12 have sides which are for example between 5 cm and 15 cm.
• the thickness of the current collector 10 is for example between 0.5 mm and 1.5 mm.
• the current collector 10 thus has the shape of a flattened parallelepiped of very small thickness.
• the catalytic layer 20, permeable to the solution 4 and to the gas 6, constitutes the active surface of the air electrode 1 making it possible (as its name suggests) to catalyze the reduction of oxygen.
• the catalytic layer 20 here comprises:
• - carbon for example in the form of carbon black, activated carbon, carbon nanotubes or graphene;
• a catalyst for example platinum, oxides of transition metals such as cobalt, manganese or iron;
• a binder for example a fluoropolymer, a polytetrafluoroethylene, a polyvinylidene fluoride, a copolymer based on sulfonated tetrafluoroethylene or else a rubber based on styrene-butadiene.
• the catalytic layer 20 extends over only a portion of the first main face 11 and at a distance from at least one of the sides of the first main face 11. As clearly shown in FIG. 3, the catalytic layer 20 extends here only over a central region 13 of the first main face 11 .
• the central region 13 of the first main face 11 is defined as an internal portion of the first main face which includes the isobarycentre of the first main face 11 .
• the first main face 11 also comprises a peripheral region 14, complementary to its central region 13, devoid of catalytic layer 20.
• the peripheral region 14 of the first main face 11 is adjacent to a perimeter 15 of the collector of current 10. Due to the small thickness of the current collector 10, the periphery 15 here also corresponds to the contour of the first main face 11, that is to say at its sides.
• the central region 13 of the first main face 11 extends at a non-zero distance, that is to say greater than zero, from the perimeter 15. In other words , the central region 13 of the first main face 11 extends at a non-zero distance from each side of the first main face 11. As represented in FIG. 3, the central region 13 of the first main face 11 here extends at a constant distance, for example between 1 cm and 3 cm, on each side of the first main face 11 . The central region 13 of the first main face 11 therefore also forms a rectangle or a square. On the first main face 11, the peripheral region 14 surrounds, more specifically frames, the central region 13. The surface of the central region 13 of the first main face 11 is preferably greater than 50% of the surface of the latter.
• the diffusion layer 30 is impermeable to the solution 4 but gas permeable 6 so that it can diffuse as far as the catalytic layer 20.
• the diffusion layer 30 here comprises carbon and a hydrophobic polymer.
• the diffusion layer 30 comprises for example a carbon powder, such as activated carbon and preferably carbon black, or graphite.
• the hydrophobic polymer is, for example, polytetrafluoroethylene (better known by the acronym PTFE), polyvinylidene fluoride or a copolymer based on sulfonated tetrafluoroethylene.
• the diffusion layer 30 extends over the second main face 12 facing the catalytic layer 20.
• the diffusion layer 30 extends only over a central region 15 of the second main face 12, which has the same dimensions as the central region 13 of the first main face 11 and which extends opposite the latter.
• the second main face 12 thus also comprises a peripheral region 16 complementary to and bordering its central region 15.
• the diffusion layer 30 and the catalytic layer 20 extend inside of the current collector 10 or interpenetrate the current collector 10 so as to come into contact with one another.
• the first seal 40 and the second seal 50 are sealed. They are here in particular impermeable to solution 4 in the sense that solution 4 cannot pass through them or soak them. This means in particular here that they are impermeable to aqueous solutions, for example acids or bases.
• the first seal 40 and the second seal 50 are also designed to be electrically conductive, as opposed to an insulating material. Thus, their surface electrical resistance is preferably less than 10 mQ cm 2 . They thus allow the circulation of electrons between the external electrical circuit 3 and the current collector 10.
• the first seal 40 and the second seal 50 generally comprise a powder of an electrically conductive material dispersed in a resin or elastomeric matrix, or an electrically conductive resin.
• the first gasket 40 and the second gasket 50 here comprise a metallic powder, preferably nickel or stainless steel, and an elastomeric matrix in which the metallic powder is dispersed.
• the elastomer matrix is for example made of silicone.
• the metal powder provides electrical conductivity while the elastomer matrix provides sealing.
• the metal powder has, for example, a particle size between 3 ⁇ m and 50 ⁇ m.
• the concentration of metal powder in the elastomer matrix is for example between 10% and 60% by mass.
• the compositions of the first gasket 40 and of the second gasket 50 are identical.
• the elastomer matrix can be loaded with carbon powder, for example in the form of graphite or carbon black.
• the joints can comprise a metal powder dispersed in an epoxy resin.
• the joints can also comprise a conductive epoxy resin.
• the first seal 40 is arranged on the peripheral region 14 of the first main face 11.
• the first seal 40 is more particularly arranged only on this peripheral region 14 and on the entirety of the latter .
• the first seal 40 thus borders the catalytic layer 20 while being in contact with the latter.
• the first main face 11 is thus not in direct contact with the solution 4.
• the first seal 40 In addition to bordering the catalytic layer 20, the first seal 40 impregnates the current collector 10 at the level of the peripheral region 14 of the first main face 11 .
• the term “impregnates” here means that the first seal 40 (and the second seal 50) has penetrated and spread into part of the pores of the current collector 10.
• the first seal 40 impregnates the current collector 10 over half of its thickness in this region.
• the thickness of the current collector 10 impregnated by the first seal 40 is between 0.2 mm and 1 mm.
• the first gasket 40 impregnates the current collector 10 over a distance of between 0.2 mm and 1 mm from the first main face 11 .
• the solution 4 can not leak through the periphery 15 of the current collector 10 since, in this region of the current collector 10, the pores of the latter are filled by the first seal 40 sealed.
• the first seal 40 also has adhesive properties, which are conferred on it here by the elastomeric matrix, allowing it to bond the first reinforcement 60 to the current collector 10.
• the purpose of the first reinforcement 60 is to facilitate the handling of the air electrode 1 as well as the connection of the external electrical circuit 3 to the air electrode 1 on the side of the first main face 11.
• the first reinforcement 60 is therefore designed to be electrically conductive.
• the first reinforcement 60 is for example here a smooth metal part.
• the electrons circulate between the reinforcement 60 and the current collector 10 thanks to the first joint 40 which is electrically conductive.
• the first reinforcement 60 is for example made of a metal or a metal alloy having corrosion resistance under the conditions of implementation of the battery.
• the first reinforcement 60 is made of stainless steel or nickel, which allows it to resist corrosion while being a very good electrical conductor.
• the first reinforcement 60 is for example made from a metal sheet, a mesh of metal wires or even a compacted metal powder.
• the first reinforcement 60 forms a belt having an opening 61 of complementary shape to the shape of the catalytic layer 20.
• the passage section defined by the opening 61 has substantially the same shape as that of the catalytic layer 20.
• the first reinforcement 60 thus forms a frame covering the peripheral region 14 of the first main face 11.
• the first reinforcement 60 thus covers in particular the entirety of the first joint 40.
• the first reinforcement 60 therefore also makes it possible to maintain the current collector 10.
• the first reinforcement 60 is generally flat in the sense that its thickness, dimension perpendicular to the main plane P, is much less than its extension along the main plane P.
• the thickness of the first reinforcement 60 is for example between 0, 03mm and 0.5mm. This contributes to the small thickness of the air electrode 1 which is preferably between 0.5 mm and 1.0 mm at the level peripheral regions 14, 16.
• the first reinforcement 50 also forms a flat and smooth sealing surface against which the containment enclosure 5 can be easily pressed or fixed so as to hermetically seal the latter on the side of air electrode 1 .
• the second seal 50 is arranged on the peripheral region 16 of the second main face 12.
• the second seal 50 is more particularly arranged only on the peripheral region 16 of the second main face 12 and on its entirety.
• the second seal 50 thus borders the diffusion layer 30.
• the second seal 50 therefore extends here facing the first seal 40.
• the second gasket 50 impregnates the current collector 10.
• the second gasket 50 impregnates the current collector 10 over half of its thickness at the level of the peripheral region 14.
• the two seals 40, 50 are in contact and the entire thickness of the current collector 10 is impregnated by a waterproof material at the level of its periphery 15.
• the probability of solution leaks 4 is thus extremely reduced.
• the thickness of the current collector 10 impregnated by the second seal 50 is between 0.2 mm and 1 mm. In other words, the second seal 50 impregnates the current collector 10 over a distance of between 0.2 mm and 1 mm from the second main face 12.
• the second seal 50 also has adhesive properties which allow it to stick the second reinforcement 70 to the current collector 10.
• the second reinforcement 70 is here a sheet metal contributing to facilitate the manipulation of the air electrode 1 and the connection of the external electrical circuit 3 (this time at the level of the second main face 12).
• the second reinforcement 70 also makes it possible to channel the gas 6 through the diffusion layer 30.
• the second reinforcement 70 has a shape similar to that of the first reinforcement 60. As shown in Figure 3, the second reinforcement 70 forms a belt framing the diffusion layer 30. The second reinforcement 70 thus has an opening 71 of complementary to the shape of the diffusion layer 30. The second reinforcement 70 covers the peripheral region 16 of the second face main 12.
• the first seal 40 and the second seal 50 thus each form a thin layer of electrically conductive material, adhesive and sealed between the current collector 10 and, respectively, the first reinforcement 60 and the second reinforcement 70.
• the thickness of the seals 40, 50 between the main faces 11, 12 of the current collector 10 and the reinforcements 60, 70 is then for example between 0.8 mm and 3 mm.
• the external electrical circuit 3 comprises electrical contacts, for example electrodes, arranged on the first reinforcement 60 and on the second reinforcement 70.
• the electrical contacts can be clamped against the reinforcements 60, 70 at the means of a plastic material support. This makes it possible to increase the contact surface between the external electrical circuit 3 and the reinforcements 60, 70 and thus to improve current collection.
• the implementation of the air electrode 1 according to the invention makes it possible to produce a metal-air battery 100 having a high specific energy.
• the air electrode 1 according to the invention can also make it possible to produce aqueous or organic-based liquid electrolyte fuel cells such as microbial, alkaline or acid fuel cells.
• the air electrode 1 according to the invention can for example be implemented in cells using as electrolyte: liquid phosphoric acid occluded in a porous solid matrix, liquid potash, molten lithium or potassium carbonates , or wastewater or buffer solutions containing phosphate.
• the air electrode 1 can also be implemented in electrochemical devices generating gas emissions.
• An air electrode as thus constituted can be manufactured according to a process comprising, as shown in Figure 4, the main steps:
• the manufacturing process is here implemented manually by a operator. However, it can also be implemented automatically using a dedicated system.
• the method begins more specifically here with step E1 of implementing the current collector 10.
• the implementation of the current collector 10 can mean the manufacture or supply of the current collector.
• the current collector 10 is for example manufactured by electrodeposition of a metal on a polymer foam, generally polyurethane.
• the current collector 10 can for example be cut from a sheet of metal foam of large dimensions.
• the current collector can also be ordered as is. In any case, the current collector 10 is ready to be used at the end of step E1.
• step E2 of depositing the catalytic layer 20 and the diffusion layer 30 on the two main faces 11, 12.
• the catalytic layer 20 and the diffusion layer 30 are for example deposited by dipping or spin coating.
• the catalytic layer 20 and the diffusion layer 30 are deposited by means of a roll-to-roll type process.
• two cylindrical rollers are arranged one above the other with their hilly axes of rotation.
• the catalytic layer 20 or the diffusion layer 30 is deposited, in the form of a viscous paste, on a support plate which passes between the two rollers.
• the spacing between the two rollers makes it possible to determine with precision, typically to plus or minus 0.1 mm, the thickness of the deposited layer.
• the thickness of the catalytic layer 20 is for example between 0.20 mm and 1 mm.
• the thickness of the diffusion layer 30 is for example between 0.20 mm and 1 mm.
• the catalytic layer 20 or the diffusion layer 30 is then removed from the support plate to be deposited on the current collector 10.
• the first roller can also be partially immersed in a bath comprising the catalytic layer or the diffusion layer. in the form of viscous ink. The viscous layer wraps around the first roller then around the second roller before being deposited on a main face.
• the gaskets 40, 50 are deposited on the peripheral regions during step E3.
• the seals 40, 50 are deposited, their elastomeric matrix is still in viscous form.
• the seals 50, 60 can penetrate into the thickness of the current collector 10.
• the seals 50, 60 are for example deposited using a syringe or an applicator mounted on a robotic arm.
• the method then comprises a step E4 of gluing the reinforcements 60, 70.
• the reinforcements 60, 70 are then placed opposite the peripheral regions 14, 16 and in contact with the seals 40, 50 and this before the gaskets 40, 50 do not set, that is to say when they are still in viscous form.
• the reinforcements are held in position until the seals 40, 50 have set, that is to say until the solvent from the elastomer matrix has evaporated.
• the reinforcements 60, 70 are thus glued to the current collector 10 by the seals 40, 50.
• the reinforcements are for example held in position by means of a hydraulic press or a uniaxial press exerting a pressure between 50 MPa and 200 MPa.
• the air electrode 1 is ready to be integrated into an electrochemical device, typically the metal-air battery 100 shown schematically in FIG. 1.
• This integration notably comprises a step of connecting the air electrode 1 to the external electrical circuit 3, the connection being advantageously made on the reinforcements 60, 70 metal.
• the metal-air battery 100 of Figure 1 comprises a single cell but several of these cells can be connected in series within the same battery to increase the voltage delivered by the battery.
• the current collector comprises, instead of a metal foam plate or a mesh of braided metal wires, a metal film comprising a plurality of holes or openings of small dimensions .
• the dimensions of the air electrode can be adapted to the dimensions of the metal-air battery in which it will be integrated. Its largest dimension can for example range from 1 cm to several tens of centimeters.
• the overall shape of the air electrode is also not limited to the example illustrated in the figures, namely a planar electrode of rectangular shape.
• the shape of the electrode can indeed be adapted to that of the metal-air battery in which it will be integrated.
• the air electrode according to the invention can for example be round or oval, for example to be mounted in a cylindrical battery.
• the air electrode is not necessarily planar in cross-section and may have a curved or even wavy shape.
• the current collector can also have a variable thickness between its main faces.
• the regions occupied by the catalytic layer and the facing diffusion layer can extend at variable distances from the sides of the current collector.
• the regions occupied by the catalytic layer and the facing diffusion layer can even be partially in contact with the sides of the current collector.
• the region of the second main face occupied by the catalytic layer can delimit two free lateral bands along two opposite sides of the second main face and extend to the edge of the collector on the other two opposite sides.
• the diffusion layer extends from one large edge to the other of the second main face, for example, and at a distance from the small edges of the second main face.
• the diffusion layer occupies the entire surface of the second main face of the collector.
• the second seal is all the same preferably deposited on the entire periphery of the second main face so as to form a strip along the periphery, which makes it possible in particular to improve current collection. It is then partly deposited on the diffusion layer.
• the first seal can also be partially deposited on the catalytic layer.
• the central region of the first main face and the central region of the second main face can be of different shapes or positioned differently, in the sense that they do not then strictly face each other.
• the central regions can also have shapes different from those of the current collector.
• the current collector can be square while the central region of the first main face is hexagonal.
• the shape of the opening of the first reinforcement then corresponds to the shape of the central region of the first main face.
• the shape of the perimeter of the catalytic layer is part of the shape of the perimeter of the diffusion layer
• the air electrode comprises only the first seal without the second seal. It is also possible that it comprises only the first reinforcement without the second reinforcement.
• the first seal is then deposited so that it impregnates the entire thickness of the current collector on its region extending outside the catalytic layer, this to minimize the probability of leakage of the solution.
• the first seal can for example impregnate the collector as far as the diffusion layer when the latter extends over the entire second main face.
• the first seal and the second seal may have different properties, for example conductivity or sealing or adhesion values.
• the first gasket may include nickel powder, and the second gasket, less subject to corrosion, aluminum or copper powder. Their electrical conductivity is then different.
• the first seal and the second seal may also not protrude from the main faces but only impregnate in the current collector and are flush with the level of the main faces, so as to all the same seal the periphery of the current collector and bond the reinforcements.
• the reinforcements can be wider than the current collector.
• the fact that they protrude from the current collector makes it possible, for example, to establish electrical contact with the external electrical circuit by pinching the reinforcements.
• the air electrode may comprise several catalytic layers, distinct from each other, distributed over the first main face of the current collector.
• the parts occupied by the catalytic layer and the facing diffusion layer are not necessarily unitary but can form disjoint blocks separated by zones occupied by the conductive joint according to the invention which may be, if necessary covered with an electrical insulator impermeable to the electrolyte solution.
• the first reinforcement then has several openings, each having a shape complementary to one of the catalytic layers. The first reinforcement is then glued to the current collector by the first gasket which is distributed over the entire surface of the first main face which is not occupied by the catalytic layers.
• the two gaskets can be deposited on only one of the two main faces so as to impregnate the current collector until part of the gasket crosses the current collector and emerges at the level of the other main face. It is then possible to glue the two reinforcements.
• the two gaskets can also be deposited simultaneously by dipping the sides of the current collector.
• the reinforcements can also be glued to the current collector before depositing the catalytic layer and the diffusion layer.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Inert Electrodes (AREA)
• Hybrid Cells (AREA)

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Publications (1)

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• 2021
  • 2021-12-21 FR FR2114102A patent/FR3131095B1/fr active Active
• 2022
  • 2022-12-20 WO PCT/EP2022/087008 patent/WO2023118155A1/fr not_active Ceased
  • 2022-12-20 EP EP22843193.8A patent/EP4454033A1/de active Pending

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