EP3853936A1 - Compositions for bipolar plates and methods for manufacturing said compositions - Google Patents

Compositions for bipolar plates and methods for manufacturing said compositions

Info

Publication number
EP3853936A1
EP3853936A1 EP19790668.8A EP19790668A EP3853936A1 EP 3853936 A1 EP3853936 A1 EP 3853936A1 EP 19790668 A EP19790668 A EP 19790668A EP 3853936 A1 EP3853936 A1 EP 3853936A1
Authority
EP
European Patent Office
Prior art keywords
conductive
thermoplastic polymer
conductive filler
composition
weight
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP19790668.8A
Other languages
German (de)
French (fr)
Inventor
Stéphane Bizet
Jérôme CHAUVEAU
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Arkema France SA
Original Assignee
Arkema France SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Arkema France SA filed Critical Arkema France SA
Publication of EP3853936A1 publication Critical patent/EP3853936A1/en
Pending legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B9/00—Making granules
    • B29B9/12—Making granules characterised by structure or composition
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B9/00—Making granules
    • B29B9/02—Making granules by dividing preformed material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
    • B29C43/003—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor characterised by the choice of material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/0001—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor characterised by the choice of material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0213—Gas-impermeable carbon-containing materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0221—Organic resins; Organic polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
    • B29C45/0013—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor using fillers dispersed in the moulding material, e.g. metal particles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
    • B29K2023/04—Polymers of ethylene
    • B29K2023/06—PE, i.e. polyethylene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
    • B29K2023/10—Polymers of propylene
    • B29K2023/12—PP, i.e. polypropylene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2081/00—Use of polymers having sulfur, with or without nitrogen, oxygen or carbon only, in the main chain, as moulding material
    • B29K2081/04—Polysulfides, e.g. PPS, i.e. polyphenylene sulfide or derivatives thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2507/00—Use of elements other than metals as filler
    • B29K2507/04—Carbon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2509/00—Use of inorganic materials not provided for in groups B29K2503/00 - B29K2507/00, as filler
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
    • B29K2995/0003—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds having particular electrical or magnetic properties, e.g. piezoelectric
    • B29K2995/0005—Conductive
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
    • H01M50/406—Moulding; Embossing; Cutting
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/446—Composite material consisting of a mixture of organic and inorganic materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/02—Details
    • H01M8/0202—Collectors; Separators, e.g. bipolar separators; Interconnectors
    • H01M8/0204—Non-porous and characterised by the material
    • H01M8/0223—Composites
    • H01M8/0226—Composites in the form of mixtures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/18—Regenerative fuel cells, e.g. redox flow batteries or secondary fuel cells
    • H01M8/184—Regeneration by electrochemical means
    • H01M8/188—Regeneration by electrochemical means by recharging of redox couples containing fluids; Redox flow type batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

  • the present invention relates to novel compositions for bipolar plates and to the methods for manufacturing these compositions.
  • Bipolar plates are used in fuel cells and in redox flux batteries. They can be made from different materials: bipolar metal plates, graphite plates and carbon-polymer composite plates.
  • bipolar plates based on organic composite materials is based on the use of conductive fillers (carbon, graphite, ...) dispersed in a thermoplastic or thermosetting polymer.
  • the charges will give the bipolar plates the electrical conductivity necessary for the collection of the current and the polymer matrix their good mechanical strength necessary for the assembly of the various elements.
  • Carbon-polymer composite bipolar plates have interesting properties: high electrical conductivity, good corrosion resistance, good performance at high temperature, and good mechanical properties, with a relatively low manufacturing cost.
  • a thermosetting or thermoplastic polymer is used as matrix for a carbonaceous filler chosen from graphite, carbon fibers, carbon black or carbon nanotubes.
  • the thermosetting resins studied as possible matrices for composite bipolar plates are mainly epoxy type resins, phenolic resins and vinylester or polyester type resins.
  • Bipolar matrix plates based on thermoplastic polymers have also been manufactured, as reported for example by the publication of Planesa E. et al. "Polymer composites bipolar plates for PEMFCs" published in Energy Procedia 20 (2012) 311 - 323.
  • thermoplastic polymers listed in this context are polypropylene, polyvinylidene fluoride or poly (phenylene sulfide).
  • the results of various tests using different thermosetting polymers and polypropylene made it possible to characterize the mechanical properties and electrical conductivities of the bipolar plates thus manufactured. As a result, the final properties of the plate depend on the manufacturing process of the polymer matrices and that of the bipolar plates.
  • the document FR 3021811 describes a process for manufacturing a composite bipolar plate from a composition comprising at least one lamellar graphite and at least one thermoplastic polymer, said process comprising the steps of dry sieving of the composition, mixing with dry the sieved composition, depositing the mixed composition in a mold, thermocompression molding of the mixed composition.
  • EP 1466372 and EP 1207535 describe microcomposite powders consisting of graphite particles and particles of a fluoropolymer which can be extruded or injected into a press to manufacture bipolar plates.
  • the invention relates to the manufacture of a composition comprising the following steps:
  • thermoplastic polymer in the molten state with a first conductive filler in order to obtain a conductive thermoplastic polymer
  • the second conductive filler is graphite.
  • the first conductive filler is chosen from: electronic conductive polymers, carbon black, carbon nanotubes, graphene, graphite, carbon fibers and their mixtures, preferably the first conductive filler being carbon black.
  • the conductive thermoplastic polymer is chosen from polypropylene, polyethylene and poly (phenylene sulfide).
  • the invention further relates to a composition obtained by the process described above.
  • the invention also relates to a composition
  • a composition comprising a second conductive filler and particles of a conductive thermoplastic polymer.
  • the particles of the conductive thermoplastic polymer comprise a matrix of thermoplastic polymer in which a first conductive filler is dispersed.
  • the conductive thermoplastic polymer is present in an amount ranging from 10% to 40%, preferably from 10 to 30%, advantageously from 10 to 25%
  • the second filler driver is present in an amount ranging from 60% to 90%, preferably from 70 to 90%, advantageously from 75 to 90% based on the total weight of the composition.
  • the first conductive filler is present in an amount of 0.1% to 35% by weight, preferably from 1% to 20% by weight, advantageously 2.5 % to 15% by weight, based on the total weight of this composition.
  • the invention relates to a method for manufacturing a bipolar plate, comprising the following steps:
  • the invention further relates to a bipolar plate obtained by the method described above or comprising the composition described above.
  • the present invention overcomes the drawbacks of the state of the art. More particularly, it provides compositions which can be easily implemented for manufacturing bipolar plates having at least one of the following characteristics: a surface resistivity less than 0.01 Ohm.cm, a volume resistivity less than 0.03 Ohm.cm, a thermal conductivity greater than 10 W / m / K and good mechanical properties such as flexural strength and compressive strength.
  • a binder comprising a thermoplastic polymer in which a conductive filler is dispersed.
  • the use of an electrically conductive binder thus obtained has several advantages.
  • the use of a conductive binder makes it possible to reduce the resistivity of the plates by reducing, or even eliminating, the electrical insulating domains of polymer between the particles of the majority charge of the plate.
  • this makes it possible to avoid the subsequent treatment of the surfaces of the bipolar plates, for example by sandblasting, which is often required following the manufacture by compression molding of the plates, in order to eliminate the layer of insulating polymer when the binder consists of a thermoplastic polymer alone.
  • the invention also provides a process for preparing the compositions having the above-mentioned advantages.
  • the fact of mixing a thermoplastic polymer in the molten state with a first conductive filler, then incorporating into said mixture a second conductive filler, in a separate step, makes it possible to obtain a composition for composite bipolar plate in which the binder comprises a conductive thermoplastic polymer, in other words a thermoplastic polymer in which a first conductive filler is dispersed. Then, the conductive thermoplastic polymer can be implemented easily.
  • the invention relates to a composition suitable for use in the manufacture of bipolar plates.
  • the composition comprises a mixture of particles of a conductive filler based on carbon, designated here as “second conductive filler”, and particles of a conductive thermoplastic polymer, which comprise a conductive filler (designated here as “first conductive filler” ) dispersed in a thermoplastic polymer matrix.
  • said composition comprises the following characters, where appropriate combined.
  • the composition may be in powder form and, in this case, the particles of conductive thermoplastic polymer are mixed with the particles of the second conductive filler.
  • the composition can be in an agglomerated solid form, and, in this case, the particles of the second conductive filler are bonded to the particles (or domains) of conductive thermoplastic polymer. It is in this agglomerated form that the composition is shaped into a bipolar plate.
  • the dispersion of the first conductive filler in the thermoplastic polymer has the effect of making the latter conductive.
  • a thermoplastic polymer is conductive when the resistance of a filament of this polymer is less than 10 6 Ohm.
  • the loading of the first conductive load is such that the percolation threshold through the matrix of thermoplastic polymer is reached.
  • the second conductive filler and the first conductive filler dispersed in the thermoplastic polymer are different from each other with regard to their average size or their size distribution and / or their nature.
  • the second conductive filler is graphite.
  • the volume average diameter (Dv50) of the second conductive charge can be equal to or less than 2500 pm, preferably equal to or less than 1000 pm, and more preferably equal to or less than 500 pm.
  • the Dv50 of the second conductive charge varies from 10 pm to 50 pm, or from 50 to 100 pm, or from 100 to 150 pm, or from 150 to 200 pm, or from 200 to 250 pm, or 250 to 300 pm, or 300 to 350 pm, or 350 to 400 pm, or 400 to 450 pm, or 450 to 500 pm, or 500 to 600 pm, or 600 to 700 pm, or 700 to 800 pm, or from 800 to 900 pm, or from 900 to 1000 pm, or from 1000 to 1100 pm, or from 1100 to 1200 pm, or from 1200 to 1300 pm, or from 1300 to 1400 pm, or from 1400 at 1500 pm, or from 1500 to 1600 pm, or from 1600 to 1700 pm, or from 1700 to 1800 pm, or from 1900 to 2000 pm, or from 2000 to 2100 pm, or from 2100 to 2200 pm, or from 2200 to 2300 pm, or from 2300 to 2400 pm, or from 2400 to 2500 pm.
  • the Dv50 is the particle diameter at the fiftieth percentile of the cumulative particle size distribution. This parameter can be measured by laser particle size.
  • the composition can comprise from 60 to 90% by weight of a second conductive filler, based on the total weight of the composition.
  • the composition comprises, by weight, from 60 to 65%, or from 65 to 70%, or from 70 to 75%, or from 75 to 80%, or from 80 to 85%, or from 85 90% of a second conductive filler, based on the total weight of the composition.
  • the particles of conductive thermoplastic polymer may have a Dv50 ranging from 0.1 pm to 1 mm, more particularly from 0.1 pm to 5 pm, or from 5 pm to 50 pm, or from 50 pm to 100 pm, or from 100 pm to 200 pm, or from 200 pm to 300 pm, or from 300 pm to 400 pm, or from 400 pm to 500 pm, or from 500 pm to 600 pm, or from 600 pm to 700 pm, or from 700 pm to 800 pm, or from 800 pm to 900 pm, or from 900 pm to 1 mm.
  • the first conductive filler dispersed in the conductive thermoplastic polymer may be an electronic conductive polymer.
  • Electronic conductive polymers which are suitable for this purpose are polyacetylene, polyphenylene vinylene, polythiophene, polyaniline, polypyrrole, poly (phenylene sulfide) or mixtures thereof.
  • the first conductive charge may include carbon particles electrically conductive, such as carbon black, carbon nanotubes, graphene, graphite, carbon fibers or a mixture of two types of particles from this list.
  • the first conductive filler dispersed in the matrix of thermoplastic polymer may have a specific surface area measured by the adsorption of nitrogen by the BET method according to standard ASTM D3037 ranging from 0.1 m 2 / g to 2000 m 2 / g and preferably from 10 m 2 to 1000 m 2 / g.
  • the first conductive filler may have a BET specific surface area ranging from 0.1 to 1 m 2 / g, or from 1 to 10 m 2 / g, or from 10 to 50 m 2 / g, or from 10 to 50 m 2 / g, or from 50 to 200 m 2 / g, or from 200 to 400 m 2 / g, or from 400 to 600 m 2 / g, or from 600 to 800 m 2 / g, or from 800 to 1000 m 2 / g, or from 1000 to 1200 m 2 / g, or from 1200 to 1400 m 2 / g, or from 1400 to 1600 m 2 / g, or from 1600 to 1800 m 2 / g, or from 1800 to 2000 m 2 / g.
  • the conductive thermoplastic polymer is preferably chosen from polypropylene, polyethylene and poly (phenylene sulfide). It can be a mixture of at least two of these polymers.
  • the conductive thermoplastic polymer is present in an amount ranging from 10% to 40%, preferably from 10 to 30%, advantageously from 15 to 25%, based on the weight total of the composition.
  • the invention also relates to a bipolar plate comprising the composition described above, in an agglomerated form.
  • a bipolar plate is a plate which separates the elementary cells in fuel cells and redox flux batteries. In general, it has the shape of a parallelepiped having a thickness of a few millimeters (typically between 0.2 and 6 mm) and comprises on each face a network of channels for the circulation of gases and fluids. Its functions are to supply the fuel cell with gaseous fuel, to evacuate the reaction products and to collect the electric current produced by the cell.
  • the bipolar plate has at least one of the following characteristics, and preferably all of these characteristics:
  • the flexural strength is measured according to DIN EN ISO 178.
  • the compressive strength is measured according to ISO 604.
  • the thermal conductivity is measured according to the Laser Llash technique according to DIN EN ISO 821.
  • the surface resistivity is measured by means of four-point probe samples on ground samples having a thickness of 4 mm.
  • the volume resistivity is measured with an installation with two electrodes and a contact pressure of 1 N / mm 2 on surfaced samples having a diameter of 13 mm and a thickness of 2 mm.
  • the bipolar plate has a surface resistivity equal to or less than 0.008 Ohm.cm, or equal to or less than 0.005 Ohm.cm, or equal to or less than 0.003 Ohm.cm, or equal to or less than 0.001 Ohm. cm.
  • the bipolar plate has a through resistivity equal to or less than 0.025 Ohm.cm, or equal to or less than 0.02 Ohm.cm, or equal to or less than 0.015 Ohm.cm.
  • the bipolar plate has a thermal conductivity equal to or greater than 15 W / m / K, or equal or greater than 20 W / m / K.
  • the bipolar plate has a flexural strength equal to or greater than 30 N / mm 2 , or equal to or greater than 35 N / mm 2 .
  • the invention relates to a process for manufacturing the composition described above comprising the following steps:
  • thermoplastic polymer in the molten state with the first conductive filler in order to obtain the conductive thermoplastic polymer
  • the first conductive filler, the thermoplastic polymer and the second conductive filler may have any of the characteristics described above as optional or preferred, in relation to the composition for bipolar plate.
  • the method according to the invention comprises a step of mixing in the molten state of the thermoplastic polymer with the first conductive filler in order to obtain the polymer conductive thermoplastic.
  • This step makes it possible to formulate an intimate mixture of the thermoplastic polymer with the first conductive filler, a mixture called “the conductive thermoplastic polymer”.
  • said first conductive filler is dispersed in the thermoplastic polymer.
  • thermoplastic polymer and the first conductive filler to be mixed in the molten state are in powder form.
  • the first conductive filler dispersed in the matrix of thermoplastic polymer may have a specific surface area measured by the adsorption of nitrogen by the BET method according to standard ASTM D3037 ranging from 0.1 m 2 / g to 2000 m 2 / g and preferably from 10 m 2 to 1000 m 2 / g.
  • the first conductive filler may have a BET specific surface area ranging from 0.1 to 1 m 2 / g, or from 1 to 10 m 2 / g, or from 10 to 50 m 2 / g, or from 10 to 50 m 2 / g, or from 50 to 200 m 2 / g, or from 200 to 400 m 2 / g, or from 400 to 600 m 2 / g, or from 600 to 800 m 2 / g, or from 800 to 1000 m 2 / g, or from 1000 to 1200 m 2 / g, or from 1200 to 1400 m 2 / g, or from 1400 to 1600 m 2 / g, or from 1600 to 1800 m 2 / g, or from 1800 to 2000 m 2 / g.
  • the mixing step in the molten state is carried out by extrusion, using for example a kneader or a twin-screw extruder.
  • a screw profile leading to the dispersive mixture thanks to a high shear rate, will be preferred.
  • the polymer granules are melted by transporting them along the screw which is heated to temperatures ranging from Tm +20 to Tm + 70 ° C (Tm being the melting temperature of the thermoplastic polymer).
  • the conductive load is preferably supplied by means of a metering unit.
  • the granules are obtained by a filament cutting process or by granulation under water.
  • the conductive thermoplastic polymer may contain, by weight, from 0.1% to 1%, or from 1% to 2.5%, or from 2.5% to 5%, or from 5% to 10%, or from 10 % to 15%, or 15% to 20%, or 20% to 25%, or 25% to 30%, or 30% to 35%, of first conductive charge, based on the weight of the conductive thermoplastic polymer .
  • the conductive thermoplastic polymer can be produced in the form of granules.
  • the method according to the invention further comprises a step of grinding said conductive thermoplastic polymer to reduce it to powder. Any grinding means can be used, for example a hammer mill.
  • the conductive thermoplastic polymer powder can have a Dv50 ranging from 0.1 pm to 1 mm, more particularly from 0.1 pm to 5 pm, or from 5 pm to 50 pm, or from 50 pm to 100 pm, or from 100 pm to 200 pm, or from 200 pm to 300 pm, or from 300 pm to 400 pm, or from 400 pm to 500 pm, or from 500 pm to 600 pm, or from 600 pm to 700 pm , or from 700 pm to 800 pm, or from 800 pm to 900 pm, or from 900 pm to 1 mm.
  • the conductive thermoplastic polymer powder is then mixed with the second conductive filler.
  • the second conductive filler can be in powder form.
  • the volume average diameter (Dv50) of the second conductive charge can be equal to or less than 2500 pm, preferably equal to or less than 1000 pm, and more preferably equal to or less than 500 pm.
  • the Dv50 of the second conductive charge varies from 10 pm to 50 pm, or from 50 to 100 pm, or from 100 to 150 pm, or from 150 to 200 pm, or from 200 to 250 pm, or 250 to 300 pm, or 300 to 350 pm, or 350 to 400 pm, or 400 to 450 pm, or 450 to 500 pm, or 500 to 600 pm, or 600 to 700 pm, or 700 to 800 pm, or from 800 to 900 pm, or from 900 to 1000 pm, or from 1000 to 1100 pm, or from 1100 to 1200 pm, or from 1200 to 1300 pm, or from 1300 to 1400 pm, or from 1400 at 1500 pm, or from 1500 to 1600 pm, or from 1600 to 1700 pm, or from 1700 to 1800 pm, or from 1900 to 2000 pm, or from 2000 to 2100 pm, or from 2100 to 2200 pm, or from 2200 to 2300 pm, or from 2300 to 2400 pm, or from 2400 to 2500 pm.
  • the mixing step can be carried out by incorporating the second conductive filler into the conductive thermoplastic polymer powder.
  • this mixing step is a compounding step carried out in an extruder, for example in a twin screw extruder.
  • the conductive thermoplastic polymer is present in an amount ranging from 10% to 40%, preferably from 10 to 30%, advantageously from 10 to 25%, based on the total weight of the composition.
  • the conductive thermoplastic polymer is preferably present in a mass proportion ranging from 10% to 15%, or from 15% to 20%, or from 20% to 25%, or from 25% to 30%, or from 30% to 35 %, or 35% to 40%, based on the total weight of the bipolar plate composition.
  • the second conductive filler can be present in a mass proportion of 60 to 90%, or from 60 to 65%, or from 65 to 70%, or from 70 to 75%, or from 75 to 80%, or from 80 to
  • the invention also relates to a bipolar plate composition made by the method described above.
  • the invention relates to a process for manufacturing a bipolar plate comprising the following steps:
  • composition subjecting the composition to compression molding.
  • the composition for bipolar plate is subjected to compression molding in the form of powder.
  • the method according to the invention may further comprise a step of grinding this powder, for example by means of a disc mill.
  • Compression molding of compositions intended to produce bipolar plates can be carried out by introducing said composition into a mold, for example a stainless steel mold, which is then closed and heated to a temperature ranging from 200 ° C. to 350 ° C., preferably from 250 ° C to 300 ° C. Then, a compression force of 300 t to 800 t, preferably from 400 t to 600 t, is applied to the mold, for a mold with dimensions of 100,000 to 150,000 mm 2 . Typically, a compression force of 500 t is applied when the mold size is 130,000 mm 2 and a compression force of 300 t is applied when the mold size is 44,000 mm 2 . The mold is then cooled to a temperature of 50 ° C to 120 ° C, preferably from 60 ° C to 100 ° C, and the plate is removed from the mold.
  • the bipolar plate has at least one of the following characteristics, and preferably all of these characteristics:
  • the flexural strength is measured according to DIN EN ISO 178.
  • the compressive strength is measured according to ISO 604.
  • the thermal conductivity is measured using the Laser Llash technique according to DIN EN ISO 821.
  • the surface resistivity is measured by means of four-point probe samples on ground samples having a thickness of 4 mm.
  • the volume resistivity is measured with an installation with two electrodes and a contact pressure of 1 N / mm 2 on surfaced samples having a diameter of 13 mm and a thickness of 2 mm.
  • the bipolar plate has a surface resistivity equal to or less than 0.008 Ohm.cm, or equal to or less than 0.005 Ohm.cm, or equal or less than 0.003 Ohm.cm, or equal or less than 0.001 Ohm. cm.
  • the bipolar plate has a through resistivity equal to or less than 0.025 Ohm.cm, or equal to or less than 0.02 Ohm.cm, or equal to or less than 0.015 Ohm.cm.
  • the bipolar plate has a thermal conductivity equal to or greater than 15 W / m / K, or equal or greater than 20 W / m / K.
  • the bipolar plate has a flexural strength equal to or greater than 30 N / mm 2 , or equal to or greater than 35 N / mm 2 .

Abstract

The present invention relates to new compositions for bipolar plates and to methods for manufacturing said compositions. More specifically, the invention relates to a method for manufacturing a composition, comprising the following steps: mixing a thermoplastic polymer in the molten state with a first conductive charge in order to obtain a conductive thermoplastic polymer; grinding said conductive thermoplastic polymer in order to reduce it to a powder; mixing the conductive thermoplastic polymer powder with a second conductive charge.

Description

COMPOSITIONS POUR PLAQUES BIPOLAIRES ET METHODES DE  COMPOSITIONS FOR BIPOLAR PLATES AND METHODS OF
FABRICATION DE CES COMPOSITIONS  MANUFACTURE OF THESE COMPOSITIONS
DOMAINE TECHNIQUE TECHNICAL AREA
La présente invention concerne de nouvelles compositions pour plaques bipolaires et les procédés de fabrications de ces compositions.  The present invention relates to novel compositions for bipolar plates and to the methods for manufacturing these compositions.
CONTEXTE TECHNIQUE TECHNICAL BACKGROUND
Les plaques bipolaires sont utilisées dans les piles à combustible et dans les batteries à flux redox. Elles peuvent être réalisées à partir de différents matériaux : plaques bipolaires métalliques, plaques en graphite et plaques en composites carbone - polymère.  Bipolar plates are used in fuel cells and in redox flux batteries. They can be made from different materials: bipolar metal plates, graphite plates and carbon-polymer composite plates.
Le principe des plaques bipolaires à base de matériaux composites organiques repose sur rutilisation de charges conductrices (carbone, graphite,...) dispersées dans un polymère thermoplastique ou thermodurcissable. Les charges vont conférer aux plaques bipolaires la conductivité électrique nécessaire à la collecte du courant et la matrice polymère leur bonne tenue mécanique nécessaire à l’assemblage des différents éléments.  The principle of bipolar plates based on organic composite materials is based on the use of conductive fillers (carbon, graphite, ...) dispersed in a thermoplastic or thermosetting polymer. The charges will give the bipolar plates the electrical conductivity necessary for the collection of the current and the polymer matrix their good mechanical strength necessary for the assembly of the various elements.
Les plaques bipolaires composites carbone-polymère présentent des propriétés intéressantes : une haute conductivité électrique, une bonne résistance à la corrosion, de bonnes performances à haute température, et de bonnes propriétés mécaniques, avec un coût de fabrication relativement faible. Dans ces plaques bipolaires composites, un polymère thermodurcissable ou thermoplastique est utilisé comme matrice pour une charge carbonée choisie parmi le graphite, les fibres de carbone, le noir de carbone ou les nanotubes de carbone. Bien que la performance électrique des plaques bipolaires composites est principalement déterminée par la charge carbonée, le matériau de la matrice polymère influence également le comportement électrique du composite. Les résines thermodurcissables étudiées comme matrices possibles pour les plaques bipolaires composites sont principalement des résines de type époxy, des résines phénoliques et des résines de type vinylester ou polyester. Elles présentent de nombreux avantages, tels que : viscosité faible, leur permettant d’être chargées avec des taux élevés en charges conductrices ; résistance à la corrosion ; stabilité thermique et dimensionnelle. Cependant, ces matrices poreuses sont fragiles. Afin d’améliorer leurs propriétés mécaniques à la rupture, des matrices à base de polymère thermodurcissable englobant des nodules en polymère thermoplastique ont été préparées, mais l’adhésion entre les deux types de polymères reste insuffisante pour améliorer leur propriété de la matrice polymère. Carbon-polymer composite bipolar plates have interesting properties: high electrical conductivity, good corrosion resistance, good performance at high temperature, and good mechanical properties, with a relatively low manufacturing cost. In these composite bipolar plates, a thermosetting or thermoplastic polymer is used as matrix for a carbonaceous filler chosen from graphite, carbon fibers, carbon black or carbon nanotubes. Although the electrical performance of composite bipolar plates is mainly determined by the carbon charge, the material of the polymer matrix also influences the electrical behavior of the composite. The thermosetting resins studied as possible matrices for composite bipolar plates are mainly epoxy type resins, phenolic resins and vinylester or polyester type resins. They have many advantages, such as: low viscosity, allowing them to be charged with high rates of conductive charges; corrosion resistance ; thermal and dimensional stability. However, these porous matrices are fragile. In order to improve their mechanical properties at break, matrices based on thermosetting polymer including nodules in thermoplastic polymer were prepared, but the adhesion between the two types of polymers remains insufficient to improve their property of the polymer matrix.
Des plaques bipolaires à matrice à base de polymères thermoplastiques ont également été fabriquées, comme rapportées par exemple par la publication de Planesa E. et al. « Polymer composites bipolar plates for PEMFCs » parue dans Energy Procedia 20 (2012) 311 - 323. Parmi les polymères thermoplastiques listés dans ce cadre figurent le polypropylène, le polyfluorure de vinylidène ou encore le poly(sulfure de phénylène). Les résultats de différents essais mettant en œuvre différents polymères thermodurcissables et du polypropylène ont permis de caractériser les propriétés mécaniques et de conductivités électriques des plaques bipolaires ainsi fabriquées. Il en résulte que les propriétés finales de la plaque dépendent du procédé de fabrication des matrices polymères et de celui des plaques bipolaires.  Bipolar matrix plates based on thermoplastic polymers have also been manufactured, as reported for example by the publication of Planesa E. et al. "Polymer composites bipolar plates for PEMFCs" published in Energy Procedia 20 (2012) 311 - 323. Among the thermoplastic polymers listed in this context are polypropylene, polyvinylidene fluoride or poly (phenylene sulfide). The results of various tests using different thermosetting polymers and polypropylene made it possible to characterize the mechanical properties and electrical conductivities of the bipolar plates thus manufactured. As a result, the final properties of the plate depend on the manufacturing process of the polymer matrices and that of the bipolar plates.
Le document FR 3021811 décrit un procédé de fabrication d'une plaque bipolaire composite à partir d'une composition comprenant au moins un graphite lamellaire et au moins un polymère thermoplastique, ledit procédé comprenant les étapes de tamisage à sec de la composition, le mélangeage à sec de la composition tamisée, le dépôt de la composition mélangée dans un moule, le moulage par thermocompression de la composition mélangée.  The document FR 3021811 describes a process for manufacturing a composite bipolar plate from a composition comprising at least one lamellar graphite and at least one thermoplastic polymer, said process comprising the steps of dry sieving of the composition, mixing with dry the sieved composition, depositing the mixed composition in a mold, thermocompression molding of the mixed composition.
Les documents EP 1466372 et EP 1207535 décrivent des poudres microcomposites constituées de particules de graphite et de particules d'un polymère fluoré qui peuvent être extradées ou injectées dans une presse pour fabriquer des plaques bipolaires.  The documents EP 1466372 and EP 1207535 describe microcomposite powders consisting of graphite particles and particles of a fluoropolymer which can be extruded or injected into a press to manufacture bipolar plates.
Le document US 2005/0042496 décrit un procédé de fabrication d’articles façonné à base de composites conducteurs, tels que des plaques bipolaires, dans lequel une matière plastique choisie parmi les thermoplastiques et les élastomères, et du graphite, sont mélangés à l’état fondu et la masse fondue est soumise à un procédé de moulage pour produire l'article façonné conducteur. Cependant, lorsque du PVDF est utilisé dans ce procédé, le mélange des composants à l’état fondu sera visqueux et par conséquent difficile à mettre en œuvre. Document US 2005/0042496 describes a process for manufacturing shaped articles based on conductive composites, such as bipolar plates, in which a plastic material chosen from thermoplastics and elastomers, and graphite, are mixed in the state melted and the melt is subjected to a molding process to producing the conductive shaped article. However, when PVDF is used in this process, the mixture of the components in the molten state will be viscous and therefore difficult to process.
Il existe un besoin de fournir une composition permettant de fabriquer des plaques bipolaires qui présentent à la fois de bonnes propriétés de conductivité thermique et conductivité électrique, ainsi que des propriétés mécaniques satisfaisantes, et qui soit facilement mise en œuvre.  There is a need to provide a composition for manufacturing bipolar plates which have both good thermal conductivity and electrical conductivity properties, as well as satisfactory mechanical properties, and which is easily implemented.
RÉSUMÉ DE L’INVENTION SUMMARY OF THE INVENTION
Selon un premier aspect, l’invention concerne la fabrication d’une composition comprenant les étapes suivantes: According to a first aspect, the invention relates to the manufacture of a composition comprising the following steps:
- mélanger un polymère thermoplastique à l'état fondu avec une première charge conductrice afin d’obtenir un polymère thermoplastique conducteur;  - mixing a thermoplastic polymer in the molten state with a first conductive filler in order to obtain a conductive thermoplastic polymer;
- broyer ledit polymère thermoplastique conducteur pour le réduire en poudre;  - grinding said conductive thermoplastic polymer to reduce it to powder;
- mélanger la poudre de polymère thermoplastique conducteur avec une seconde charge conductrice.  - mix the conductive thermoplastic polymer powder with a second conductive filler.
Selon un mode de réalisation, la seconde charge conductrice est le graphite.  According to one embodiment, the second conductive filler is graphite.
Selon un mode de réalisation, la première charge conductrice est choisie parmi : les polymères conducteurs électroniques, le noir de carbone, les nanotubes de carbone, le graphène, le graphite, les fibres de carbone et leurs mélanges, de préférence la première charge conductrice étant le noir de carbone.  According to one embodiment, the first conductive filler is chosen from: electronic conductive polymers, carbon black, carbon nanotubes, graphene, graphite, carbon fibers and their mixtures, preferably the first conductive filler being carbon black.
Selon un mode de réalisation, le polymère thermoplastique conducteur est choisi parmi le polypropylène, le polyéthylène et le poly( sulfure de phénylène).  According to one embodiment, the conductive thermoplastic polymer is chosen from polypropylene, polyethylene and poly (phenylene sulfide).
L’invention concerne en outre une composition obtenue par le procédé décrit ci- dessus.  The invention further relates to a composition obtained by the process described above.
L’invention concerne également une composition comprenant une seconde charge conductrice et des particules d’un polymère thermoplastique conducteur. De manière caractéristique, les particules du polymère thermoplastique conducteur comprennent une matrice de polymère thermoplastique dans laquelle est dispersée une première charge conductrice.  The invention also relates to a composition comprising a second conductive filler and particles of a conductive thermoplastic polymer. Typically, the particles of the conductive thermoplastic polymer comprise a matrix of thermoplastic polymer in which a first conductive filler is dispersed.
Selon un mode de réalisation, dans la composition selon l’invention, le polymère thermoplastique conducteur est présent en une quantité allant de 10% à 40%, de préférence de 10 à 30%, avantageusement de 10 à 25%, et la seconde charge conductrice est présente en une quantité allant de 60% à 90%, de préférence de 70 à 90%, avantageusement de 75 à 90% basé sur le poids total de la composition. According to one embodiment, in the composition according to the invention, the conductive thermoplastic polymer is present in an amount ranging from 10% to 40%, preferably from 10 to 30%, advantageously from 10 to 25%, and the second filler driver is present in an amount ranging from 60% to 90%, preferably from 70 to 90%, advantageously from 75 to 90% based on the total weight of the composition.
Selon un mode de réalisation, dans la composition de polymère thermoplastique conducteur, la première charge conductrice est présente en une quantité de 0,1% à 35% en poids, de préférence de 1% à 20% en poids, avantageusement de 2,5% à 15% en poids, basé sur le poids total de cette composition.  According to one embodiment, in the conductive thermoplastic polymer composition, the first conductive filler is present in an amount of 0.1% to 35% by weight, preferably from 1% to 20% by weight, advantageously 2.5 % to 15% by weight, based on the total weight of this composition.
L’invention concerne selon un autre aspect un procédé de fabrication d’une plaque bipolaire, comprenant les étapes suivantes:  According to another aspect, the invention relates to a method for manufacturing a bipolar plate, comprising the following steps:
- préparer une composition selon le procédé décrit ci-dessus, ou fournir une composition telle que décrite ci-dessus, et  preparing a composition according to the method described above, or providing a composition as described above, and
- soumettre ladite composition à un moulage par compression.  - subjecting said composition to a compression molding.
L’invention concerne en outre une plaque bipolaire obtenue par le procédé décrit ci-dessus ou comprenant la composition décrite ci-dessus.  The invention further relates to a bipolar plate obtained by the method described above or comprising the composition described above.
La présente invention permet de surmonter les inconvénients de l’état de l’art. Elle fournit plus particulièrement des compositions pouvant être mises en œuvre facilement pour fabriquer des plaques bipolaires présentant au moins une des caractéristiques suivantes : une résistivité surfacique inférieure à 0,01 Ohm.cm, une résistivité volumique inférieure à 0,03 Ohm.cm, une conductivité thermique supérieure à 10 W/m/K et de bonnes propriétés mécaniques telles que résistance à la flexion et résistance à la compression.  The present invention overcomes the drawbacks of the state of the art. More particularly, it provides compositions which can be easily implemented for manufacturing bipolar plates having at least one of the following characteristics: a surface resistivity less than 0.01 Ohm.cm, a volume resistivity less than 0.03 Ohm.cm, a thermal conductivity greater than 10 W / m / K and good mechanical properties such as flexural strength and compressive strength.
Cela est réalisé grâce à l’utilisation d’un liant comprenant un polymère thermoplastique dans lequel est dispersée une charge conductrice. L’utilisation d’un liant conducteur électrique ainsi obtenu a plusieurs avantages. D’une part, l’utilisation d’un liant conducteur permet de réduire la résistivité des plaques en réduisant, voire supprimant, les domaines isolants électriques de polymère entre les particules de la charge majoritaire de la plaque. D’autre part, cela permet d’éviter le traitement subséquent des surfaces des plaques bipolaires, par exemple par sablage, qui est souvent exigé suite à la fabrication par moulage par compression des plaques, afin d’éliminer la couche de polymère isolant lorsque le liant consiste en un polymère thermoplastique seul.  This is achieved through the use of a binder comprising a thermoplastic polymer in which a conductive filler is dispersed. The use of an electrically conductive binder thus obtained has several advantages. On the one hand, the use of a conductive binder makes it possible to reduce the resistivity of the plates by reducing, or even eliminating, the electrical insulating domains of polymer between the particles of the majority charge of the plate. On the other hand, this makes it possible to avoid the subsequent treatment of the surfaces of the bipolar plates, for example by sandblasting, which is often required following the manufacture by compression molding of the plates, in order to eliminate the layer of insulating polymer when the binder consists of a thermoplastic polymer alone.
L’invention fournit également un procédé pour préparer les compositions présentant les avantages susmentionnés. Le fait de mélanger un polymère thermoplastique à l'état fondu avec une première charge conductrice, puis d’incorporer audit mélange une seconde charge conductrice, dans une étape distincte, permet d’obtenir une composition pour plaque bipolaire composite dans laquelle le liant comprend un polymère thermoplastique conducteur, autrement dit un polymère thermoplastique dans lequel une première charge conductrice est dispersée. Ensuite, le polymère thermoplastique conducteur peut être mis en œuvre facilement. The invention also provides a process for preparing the compositions having the above-mentioned advantages. The fact of mixing a thermoplastic polymer in the molten state with a first conductive filler, then incorporating into said mixture a second conductive filler, in a separate step, makes it possible to obtain a composition for composite bipolar plate in which the binder comprises a conductive thermoplastic polymer, in other words a thermoplastic polymer in which a first conductive filler is dispersed. Then, the conductive thermoplastic polymer can be implemented easily.
DESCRIPTION DE MODES DE RÉALISATION DE L’INVENTION DESCRIPTION OF EMBODIMENTS OF THE INVENTION
L’invention est décrite de manière détaillée ci-après. The invention is described in detail below.
Les pourcentages indiqués dans le texte sont des pourcentages massiques.  The percentages given in the text are mass percentages.
Composition pour plaque bipolaire Composition for bipolar plate
Selon un premier aspect, l’invention concerne une composition apte à être utilisée dans la fabrication de plaques bipolaires. La composition comprend un mélange de particules d’une charge conductrice à base de carbone, désigné ici comme « seconde charge conductrice », et des particules d’un polymère thermoplastique conducteur, qui comprennent une charge conductrice (désignée ici comme « première charge conductrice ») dispersée dans une matrice de polymère thermoplastique.  According to a first aspect, the invention relates to a composition suitable for use in the manufacture of bipolar plates. The composition comprises a mixture of particles of a conductive filler based on carbon, designated here as “second conductive filler”, and particles of a conductive thermoplastic polymer, which comprise a conductive filler (designated here as “first conductive filler” ) dispersed in a thermoplastic polymer matrix.
Selon diverses réalisations, ladite composition comprend les caractères suivants, le cas échéant combinés.  According to various embodiments, said composition comprises the following characters, where appropriate combined.
La composition peut être sous forme de poudre et, dans ce cas, les particules de polymère thermoplastique conducteur sont mélangées aux particules de la seconde charge conductrice.  The composition may be in powder form and, in this case, the particles of conductive thermoplastic polymer are mixed with the particles of the second conductive filler.
Selon un autre mode de réalisation, la composition peut être sous une forme solide agglomérée, et, dans ce cas, les particules de la seconde charge conductrice sont liées aux particules (ou domaines) de polymère thermoplastique conducteur. C’est sous cette forme agglomérée que la composition est façonnée en une plaque bipolaire.  According to another embodiment, the composition can be in an agglomerated solid form, and, in this case, the particles of the second conductive filler are bonded to the particles (or domains) of conductive thermoplastic polymer. It is in this agglomerated form that the composition is shaped into a bipolar plate.
La dispersion de la première charge conductrice dans le polymère thermoplastique a pour effet de rendre celui-ci conducteur. Un polymère thermoplastique est conducteur lorsque la résistance d’un filament de ce polymère est inférieure à 106 Ohm. De préférence, le chargement de la première charge conductrice est tel que le seuil de percolation à travers la matrice de polymère thermoplastique est atteint. The dispersion of the first conductive filler in the thermoplastic polymer has the effect of making the latter conductive. A thermoplastic polymer is conductive when the resistance of a filament of this polymer is less than 10 6 Ohm. Preferably, the loading of the first conductive load is such that the percolation threshold through the matrix of thermoplastic polymer is reached.
De préférence, la seconde charge conductrice et la première charge conductrice dispersée dans le polymère thermoplastique sont différentes l’une de l’autre en ce qui concerne leur taille moyenne ou leur répartition des tailles et/ou leur nature. Avantageusement, la seconde charge conductrice est le graphite. Preferably, the second conductive filler and the first conductive filler dispersed in the thermoplastic polymer are different from each other with regard to their average size or their size distribution and / or their nature. Advantageously, the second conductive filler is graphite.
Le diamètre moyen en volume (Dv50) de la seconde charge conductrice peut être égal ou inférieur à 2500 pm, de préférence égal ou inférieur à 1000 pm, et plus préférablement égal ou inférieur à 500 pm.  The volume average diameter (Dv50) of the second conductive charge can be equal to or less than 2500 pm, preferably equal to or less than 1000 pm, and more preferably equal to or less than 500 pm.
Selon certains modes de réalisation, le Dv50 de la seconde charge conductrice varie de 10 pm à 50 pm, ou de 50 à 100 pm, ou de 100 à 150 pm, ou de 150 à 200 pm, ou de 200 à 250 pm, ou de 250 à 300 pm, ou de 300 to 350 pm, ou de 350 à 400 pm, ou de 400 à 450 pm, ou de 450 à 500 pm, ou de 500 à 600 pm, ou de 600 à 700 pm, ou de 700 à 800 pm, ou de 800 à 900 pm, ou de 900 à 1000 pm, ou de 1000 à 1100 pm, ou de 1100 à 1200 pm, ou de 1200 à 1300 pm, ou de 1300 à 1400 pm, ou de 1400 à 1500 pm, ou de 1500 à 1600 pm, ou de 1600 à 1700 pm, ou de 1700 à 1800 pm, ou de 1900 à 2000 pm, ou de 2000 à 2100 pm, ou de 2100 à 2200 pm, ou de 2200 à 2300 pm, ou de 2300 à 2400 pm, ou de 2400 à 2500 pm.  According to certain embodiments, the Dv50 of the second conductive charge varies from 10 pm to 50 pm, or from 50 to 100 pm, or from 100 to 150 pm, or from 150 to 200 pm, or from 200 to 250 pm, or 250 to 300 pm, or 300 to 350 pm, or 350 to 400 pm, or 400 to 450 pm, or 450 to 500 pm, or 500 to 600 pm, or 600 to 700 pm, or 700 to 800 pm, or from 800 to 900 pm, or from 900 to 1000 pm, or from 1000 to 1100 pm, or from 1100 to 1200 pm, or from 1200 to 1300 pm, or from 1300 to 1400 pm, or from 1400 at 1500 pm, or from 1500 to 1600 pm, or from 1600 to 1700 pm, or from 1700 to 1800 pm, or from 1900 to 2000 pm, or from 2000 to 2100 pm, or from 2100 to 2200 pm, or from 2200 to 2300 pm, or from 2300 to 2400 pm, or from 2400 to 2500 pm.
Le Dv50 est le diamètre des particules au cinquantième percentile de la distribution des tailles cumulative des particules. Ce paramètre peut être mesuré par granulométrie laser.  The Dv50 is the particle diameter at the fiftieth percentile of the cumulative particle size distribution. This parameter can be measured by laser particle size.
La composition peut comprendre de 60 à 90% en poids d’une seconde charge conductrice, basé sur le poids total de la composition. Selon certains modes de réalisation, la composition comprend, en poids, de 60 à 65%, ou de 65 à 70%, ou de 70 à 75%, ou de 75 à 80%, ou de 80 à 85%, ou de 85 à 90%, d’une seconde charge conductrice, basé sur le poids total de la composition.  The composition can comprise from 60 to 90% by weight of a second conductive filler, based on the total weight of the composition. According to certain embodiments, the composition comprises, by weight, from 60 to 65%, or from 65 to 70%, or from 70 to 75%, or from 75 to 80%, or from 80 to 85%, or from 85 90% of a second conductive filler, based on the total weight of the composition.
Les particules de polymère thermoplastique conducteur peuvent avoir une Dv50 allant de 0,1 pm à 1 mm, plus particulièrement de 0,1 pm à 5 pm, ou de 5 pm à 50 pm, ou de 50 pm à 100 pm, ou de 100 pm à 200 pm, ou de 200 pm à 300 pm, ou de 300 pm à 400 pm, ou de 400 pm à 500 pm, ou de 500 pm à 600 pm, ou de 600 pm à 700 pm, ou de700 pm à 800 pm, ou de800 pm à 900 pm, ou de 900 pm à 1 mm.  The particles of conductive thermoplastic polymer may have a Dv50 ranging from 0.1 pm to 1 mm, more particularly from 0.1 pm to 5 pm, or from 5 pm to 50 pm, or from 50 pm to 100 pm, or from 100 pm to 200 pm, or from 200 pm to 300 pm, or from 300 pm to 400 pm, or from 400 pm to 500 pm, or from 500 pm to 600 pm, or from 600 pm to 700 pm, or from 700 pm to 800 pm, or from 800 pm to 900 pm, or from 900 pm to 1 mm.
La première charge conductrice dispersée dans le polymère thermoplastique conducteur peut être un polymère conducteur électronique. Des polymères conducteurs électroniques qui conviennent à cet effet sont les polymères de polyacétylène, polyphénylène vinylène, polythiophène, polyaniline, polypyrrole, poly(sulfure de phénylène) ou leurs mélanges. Selon une autre variante de réalisation, ou en addition, la première charge conductrice peut comprendre des particules de carbone électriquement conductrices, telles que le noir de carbone, les nanotubes de carbone, le graphène, le graphite, les fibres de carbone ou un mélange de deux types de particules parmi cette liste. The first conductive filler dispersed in the conductive thermoplastic polymer may be an electronic conductive polymer. Electronic conductive polymers which are suitable for this purpose are polyacetylene, polyphenylene vinylene, polythiophene, polyaniline, polypyrrole, poly (phenylene sulfide) or mixtures thereof. According to another alternative embodiment, or in addition, the first conductive charge may include carbon particles electrically conductive, such as carbon black, carbon nanotubes, graphene, graphite, carbon fibers or a mixture of two types of particles from this list.
La première charge conductrice dispersée dans la matrice de polymère thermoplastique peut avoir une surface spécifique mesurée par l’adsorption de l'azote par la méthode BET selon la norme ASTM D3037 allant de 0.1 m2/g à 2000 m2/g et de préférence de 10 m2 à 1000 m2/g. Selon certains modes de réalisation, première charge conductrice peut avoir une surface spécifique BET allant de 0.1 à 1 m2/g, ou de 1 à 10 m2/g, ou de 10 à 50 m2/g, ou de 10 à 50 m2/g, ou de 50 à 200 m2/g, ou de 200 à 400 m2/g, ou de 400 à 600 m2/g, ou de 600 à 800 m2/g, ou de 800 à 1000 m2/g, ou de 1000 à 1200 m2/g, ou de 1200 à 1400 m2/g, ou de 1400 à 1600 m2/g, ou de 1600 à 1800 m2/g, ou de 1800 à 2000 m2/g. The first conductive filler dispersed in the matrix of thermoplastic polymer may have a specific surface area measured by the adsorption of nitrogen by the BET method according to standard ASTM D3037 ranging from 0.1 m 2 / g to 2000 m 2 / g and preferably from 10 m 2 to 1000 m 2 / g. According to certain embodiments, the first conductive filler may have a BET specific surface area ranging from 0.1 to 1 m 2 / g, or from 1 to 10 m 2 / g, or from 10 to 50 m 2 / g, or from 10 to 50 m 2 / g, or from 50 to 200 m 2 / g, or from 200 to 400 m 2 / g, or from 400 to 600 m 2 / g, or from 600 to 800 m 2 / g, or from 800 to 1000 m 2 / g, or from 1000 to 1200 m 2 / g, or from 1200 to 1400 m 2 / g, or from 1400 to 1600 m 2 / g, or from 1600 to 1800 m 2 / g, or from 1800 to 2000 m 2 / g.
Le polymère thermoplastique conducteur est de préférence choisi parmi le polypropylène, le polyéthylène et le poly(sulfure de phénylène). Il peut être un mélange d’au moins deux de ces polymères.  The conductive thermoplastic polymer is preferably chosen from polypropylene, polyethylene and poly (phenylene sulfide). It can be a mixture of at least two of these polymers.
Selon un mode de réalisation, dans la composition selon l’invention, le polymère thermoplastique conducteur est présent en une quantité allant de 10% à 40%, de préférence de 10 à 30%, avantageusement de 15 à 25%, basé sur le poids total de la composition.  According to one embodiment, in the composition according to the invention, the conductive thermoplastic polymer is present in an amount ranging from 10% to 40%, preferably from 10 to 30%, advantageously from 15 to 25%, based on the weight total of the composition.
Plaque bipolaire Bipolar plate
L’invention concerne également une plaque bipolaire comprenant la composition décrite ci-dessus, sous une forme agglomérée. Une plaque bipolaire est une plaque sui sépare les cellules élémentaires dans les piles à combustible et les batteries à flux redox. En général, elle a une forme de parallélépipède ayant une épaisseur de quelques millimètres (typiquement comprise entre 0,2 et 6 mm) et comprend sur chaque face un réseau de canaux pour la circulation des gaz et des fluides. Ses fonctions consistent à alimenter la pile à combustible avec du carburant gazeux, à évacuer les produits de réaction et à collecter le courent électrique produit par la cellule.  The invention also relates to a bipolar plate comprising the composition described above, in an agglomerated form. A bipolar plate is a plate which separates the elementary cells in fuel cells and redox flux batteries. In general, it has the shape of a parallelepiped having a thickness of a few millimeters (typically between 0.2 and 6 mm) and comprises on each face a network of channels for the circulation of gases and fluids. Its functions are to supply the fuel cell with gaseous fuel, to evacuate the reaction products and to collect the electric current produced by the cell.
Avantageusement, la plaque bipolaire présente au moins une des caractéristiques suivantes, et de préférence toutes ces caractéristiques :  Advantageously, the bipolar plate has at least one of the following characteristics, and preferably all of these characteristics:
une résistivité surfacique égale ou inférieure à 0,01 Ohm.cm ;  a surface resistivity equal to or less than 0.01 Ohm.cm;
une résistivité volumique égale ou inférieure à 0,03 Ohm.cm;  a volume resistivity equal to or less than 0.03 Ohm.cm;
une conductivité thermique égale ou supérieure à 10 W/m/K;  a thermal conductivity of 10 W / m / K or more;
une résistance à la flexion égale ou supérieure à 25 N/mm2; une résistance à la compression égale ou supérieure à 25 N/mm2. a flexural strength of 25 N / mm 2 or more ; a compressive strength of 25 N / mm 2 or more .
La résistance à la flexion est mesurée selon la norme DIN EN ISO 178. La résistance à la compression est mesurée selon la norme ISO 604. La conductivité thermique est mesurée selon la technique Laser Llash selon la norme DIN EN ISO 821. La résistivité surfacique est mesurée au moyen d’échantillons de sonde à quatre points sur des échantillons broyés ayant une épaisseur de 4 mm. La résistivité volumique est mesurée avec une installation à deux électrodes et une pression de contact de 1 N/mm2 sur des échantillons surfacés ayant un diamètre de 13 mm et une épaisseur de 2 mm. The flexural strength is measured according to DIN EN ISO 178. The compressive strength is measured according to ISO 604. The thermal conductivity is measured according to the Laser Llash technique according to DIN EN ISO 821. The surface resistivity is measured by means of four-point probe samples on ground samples having a thickness of 4 mm. The volume resistivity is measured with an installation with two electrodes and a contact pressure of 1 N / mm 2 on surfaced samples having a diameter of 13 mm and a thickness of 2 mm.
Selon certains modes de réalisation, la plaque bipolaire présente une résistivité surfacique égale ou inférieure à 0,008 Ohm.cm, ou égale ou inférieure à 0,005 Ohm.cm, ou égale ou inférieure à 0,003 Ohm.cm, ou égale ou inférieure à 0,001 Ohm.cm.  According to certain embodiments, the bipolar plate has a surface resistivity equal to or less than 0.008 Ohm.cm, or equal to or less than 0.005 Ohm.cm, or equal to or less than 0.003 Ohm.cm, or equal to or less than 0.001 Ohm. cm.
Selon certains modes de réalisation, la plaque bipolaire présente une résistivité traversante égale ou inférieure à 0,025 Ohm.cm, ou égale ou inférieure à 0,02 Ohm.cm, ou égale ou inférieure à 0,015 Ohm.cm.  According to certain embodiments, the bipolar plate has a through resistivity equal to or less than 0.025 Ohm.cm, or equal to or less than 0.02 Ohm.cm, or equal to or less than 0.015 Ohm.cm.
Selon certains modes de réalisation, la plaque bipolaire possède une conductivité thermique égale ou supérieure à 15 W/m/K, ou égale ou supérieure à 20 W/m/K.  According to certain embodiments, the bipolar plate has a thermal conductivity equal to or greater than 15 W / m / K, or equal or greater than 20 W / m / K.
Selon certains modes de réalisation, la plaque bipolaire présente une résistance à la flexion égale ou supérieure à 30 N/mm2, ou égale ou supérieure à 35 N/mm2. According to certain embodiments, the bipolar plate has a flexural strength equal to or greater than 30 N / mm 2 , or equal to or greater than 35 N / mm 2 .
Procédés Processes
Selon un autre aspect, l’invention concerne un procédé de fabrication de la composition décrite ci-dessus comprenant les étapes suivantes:  According to another aspect, the invention relates to a process for manufacturing the composition described above comprising the following steps:
- mélanger le polymère thermoplastique à l'état fondu avec la première charge conductrice afin d’obtenir le polymère thermoplastique conducteur;  - mixing the thermoplastic polymer in the molten state with the first conductive filler in order to obtain the conductive thermoplastic polymer;
- broyer ledit polymère thermoplastique conducteur pour le réduire en poudre;  - grinding said conductive thermoplastic polymer to reduce it to powder;
- mélanger la poudre de polymère thermoplastique conducteur avec la seconde charge conductrice.  - mix the conductive thermoplastic polymer powder with the second conductive filler.
Dans ce procédé, la première charge conductrice, le polymère thermoplastique et la seconde charge conductrice peuvent avoir n’importe quelle caractéristique décrite ci- dessus comme étant optionnelle ou préférée, en rapport avec la composition pour plaque bipolaire.  In this process, the first conductive filler, the thermoplastic polymer and the second conductive filler may have any of the characteristics described above as optional or preferred, in relation to the composition for bipolar plate.
Le procédé selon l’invention comprend une étape de mélange à l'état fondu du polymère thermoplastique avec la première charge conductrice afin d’obtenir le polymère thermoplastique conducteur. Cette étape permet de formuler un mélange intime du polymère thermoplastique avec la première charge conductrice, mélange appelé « le polymère thermoplastique conducteur ». De préférence, ladite première charge conductrice est dispersée dans le polymère thermoplastique. The method according to the invention comprises a step of mixing in the molten state of the thermoplastic polymer with the first conductive filler in order to obtain the polymer conductive thermoplastic. This step makes it possible to formulate an intimate mixture of the thermoplastic polymer with the first conductive filler, a mixture called “the conductive thermoplastic polymer”. Preferably, said first conductive filler is dispersed in the thermoplastic polymer.
De préférence, le polymère thermoplastique et la première charge conductrice à mélanger à l’état fondu sont sous forme de poudre.  Preferably, the thermoplastic polymer and the first conductive filler to be mixed in the molten state are in powder form.
La première charge conductrice dispersée dans la matrice de polymère thermoplastique peut avoir une surface spécifique mesurée par l’adsorption de l'azote par la méthode BET selon la norme ASTM D3037 allant de 0,1 m2/g à 2000 m2/g et de préférence de 10 m2 à 1000 m2/g. Selon certains modes de réalisation, première charge conductrice peut avoir une surface spécifique BET allant de 0.1 à 1 m2/g, ou de 1 à 10 m2/g, ou de 10 à 50 m2/g, ou de 10 à 50 m2/g, ou de 50 à 200 m2/g, ou de 200 à 400 m2/g, ou de 400 à 600 m2/g, ou de 600 à 800 m2/g, ou de 800 à 1000 m2/g, ou de 1000 à 1200 m2/g, ou de 1200 à 1400 m2/g, ou de 1400 à 1600 m2/g, ou de 1600 à 1800 m2/g, ou de 1800 à 2000 m2/g. The first conductive filler dispersed in the matrix of thermoplastic polymer may have a specific surface area measured by the adsorption of nitrogen by the BET method according to standard ASTM D3037 ranging from 0.1 m 2 / g to 2000 m 2 / g and preferably from 10 m 2 to 1000 m 2 / g. According to certain embodiments, the first conductive filler may have a BET specific surface area ranging from 0.1 to 1 m 2 / g, or from 1 to 10 m 2 / g, or from 10 to 50 m 2 / g, or from 10 to 50 m 2 / g, or from 50 to 200 m 2 / g, or from 200 to 400 m 2 / g, or from 400 to 600 m 2 / g, or from 600 to 800 m 2 / g, or from 800 to 1000 m 2 / g, or from 1000 to 1200 m 2 / g, or from 1200 to 1400 m 2 / g, or from 1400 to 1600 m 2 / g, or from 1600 to 1800 m 2 / g, or from 1800 to 2000 m 2 / g.
Selon un mode de réalisation, l’étape de mélange à l'état fondu est réalisée par extrusion, en utilisant par exemple un malaxeur ou une extrudeuse à deux vis. Afin d’obtenir une bonne dispersion des premières charges conductrices à l’intérieur du polymère thermoplastique, un profil de vis, conduisant au mélange dispersif grâce à un taux de cisaillement élevé, sera préféré.  According to one embodiment, the mixing step in the molten state is carried out by extrusion, using for example a kneader or a twin-screw extruder. In order to obtain good dispersion of the first conductive fillers inside the thermoplastic polymer, a screw profile, leading to the dispersive mixture thanks to a high shear rate, will be preferred.
Selon un mode de réalisation, dans un procédé d’extrusion classique pour mélanger à l’état fondu un polymère thermoplastique avec la première charge conductrice, les granulés de polymère sont fondus en les transportant le long de la vis qui est chauffée jusqu’à des températures allant de Tm +20 à Tm+70 °C (Tm étant la température de fusion du polymère thermoplastique). La charge conductrice est alimentée de préférence au moyen d’une unité de dosage. De préférence, après l’extrusion, les granulés sont obtenus par un procédé de découpe de filaments ou par granulation sous eau.  According to one embodiment, in a conventional extrusion method for melting a thermoplastic polymer with the first conductive filler, the polymer granules are melted by transporting them along the screw which is heated to temperatures ranging from Tm +20 to Tm + 70 ° C (Tm being the melting temperature of the thermoplastic polymer). The conductive load is preferably supplied by means of a metering unit. Preferably, after extrusion, the granules are obtained by a filament cutting process or by granulation under water.
Le polymère thermoplastique conducteur peut contenir, en poids, de 0,1% à 1%, ou de 1% à 2,5%, ou de 2,5% à 5%, ou de 5% à 10%, ou de 10% à 15%, ou de 15% à 20%, ou de 20% à 25%, ou de 25% à 30%, ou de 30% à 35%, de première charge conductrice, basé sur le poids du polymère thermoplastique conducteur.  The conductive thermoplastic polymer may contain, by weight, from 0.1% to 1%, or from 1% to 2.5%, or from 2.5% to 5%, or from 5% to 10%, or from 10 % to 15%, or 15% to 20%, or 20% to 25%, or 25% to 30%, or 30% to 35%, of first conductive charge, based on the weight of the conductive thermoplastic polymer .
Le polymère thermoplastique conducteur peut être produit sous forme de granulés. Le procédé selon l’invention comprend en outre une étape de broyage dudit polymère thermoplastique conducteur pour le réduire en poudre. Tout moyen de broyage peut être employé, par exemple un broyeur à marteau. Selon certains modes de réalisation, la poudre de polymère thermoplastique conducteur peut avoir une Dv50 allant de 0,1 pm à 1 mm, plus particulièrement de 0,1 pm à 5 pm, ou de 5 pm à 50 pm, ou de 50 pm à 100 pm, ou de 100 pm à 200 pm, ou de 200 pm à 300 pm, ou de 300 pm à 400 pm, ou de 400 pm à 500 pm, ou de 500 pm à 600 pm, ou de 600 pm à 700 pm, ou de700 pm à 800 pm, ou de800 pm à 900 pm, ou de 900 pm à 1 mm. The conductive thermoplastic polymer can be produced in the form of granules. The method according to the invention further comprises a step of grinding said conductive thermoplastic polymer to reduce it to powder. Any grinding means can be used, for example a hammer mill. According to certain embodiments, the conductive thermoplastic polymer powder can have a Dv50 ranging from 0.1 pm to 1 mm, more particularly from 0.1 pm to 5 pm, or from 5 pm to 50 pm, or from 50 pm to 100 pm, or from 100 pm to 200 pm, or from 200 pm to 300 pm, or from 300 pm to 400 pm, or from 400 pm to 500 pm, or from 500 pm to 600 pm, or from 600 pm to 700 pm , or from 700 pm to 800 pm, or from 800 pm to 900 pm, or from 900 pm to 1 mm.
La poudre de polymère thermoplastique conducteur est ensuite mélangée avec la seconde charge conductrice.  The conductive thermoplastic polymer powder is then mixed with the second conductive filler.
La seconde charge conductrice peut être sous forme de poudre. Le diamètre moyen en volume (Dv50) de la seconde charge conductrice peut être égal ou inférieur à 2500 pm, de préférence égal ou inférieur à 1000 pm, et plus préférablement égal ou inférieur à 500 pm.  The second conductive filler can be in powder form. The volume average diameter (Dv50) of the second conductive charge can be equal to or less than 2500 pm, preferably equal to or less than 1000 pm, and more preferably equal to or less than 500 pm.
Selon certains modes de réalisation, le Dv50 de la seconde charge conductrice varie de 10 pm à 50 pm, ou de 50 à 100 pm, ou de 100 à 150 pm, ou de 150 à 200 pm, ou de 200 à 250 pm, ou de 250 à 300 pm, ou de 300 to 350 pm, ou de 350 à 400 pm, ou de 400 à 450 pm, ou de 450 à 500 pm, ou de 500 à 600 pm, ou de 600 à 700 pm, ou de 700 à 800 pm, ou de 800 à 900 pm, ou de 900 à 1000 pm, ou de 1000 à 1100 pm, ou de 1100 à 1200 pm, ou de 1200 à 1300 pm, ou de 1300 à 1400 pm, ou de 1400 à 1500 pm, ou de 1500 à 1600 pm, ou de 1600 à 1700 pm, ou de 1700 à 1800 pm, ou de 1900 à 2000 pm, ou de 2000 à 2100 pm, ou de 2100 à 2200 pm, ou de 2200 à 2300 pm, ou de 2300 à 2400 pm, ou de 2400 à 2500 pm.  According to certain embodiments, the Dv50 of the second conductive charge varies from 10 pm to 50 pm, or from 50 to 100 pm, or from 100 to 150 pm, or from 150 to 200 pm, or from 200 to 250 pm, or 250 to 300 pm, or 300 to 350 pm, or 350 to 400 pm, or 400 to 450 pm, or 450 to 500 pm, or 500 to 600 pm, or 600 to 700 pm, or 700 to 800 pm, or from 800 to 900 pm, or from 900 to 1000 pm, or from 1000 to 1100 pm, or from 1100 to 1200 pm, or from 1200 to 1300 pm, or from 1300 to 1400 pm, or from 1400 at 1500 pm, or from 1500 to 1600 pm, or from 1600 to 1700 pm, or from 1700 to 1800 pm, or from 1900 to 2000 pm, or from 2000 to 2100 pm, or from 2100 to 2200 pm, or from 2200 to 2300 pm, or from 2300 to 2400 pm, or from 2400 to 2500 pm.
L’étape de mélange peut être effectuée en incorporant la seconde charge conductrice dans la poudre de polymère thermoplastique conducteur. Avantageusement, cette étape de mélange est une étape de compoundage réalisée dans une extrudeuse, par exemple dans une extrudeuse à deux vis.  The mixing step can be carried out by incorporating the second conductive filler into the conductive thermoplastic polymer powder. Advantageously, this mixing step is a compounding step carried out in an extruder, for example in a twin screw extruder.
Selon un mode de réalisation, le polymère thermoplastique conducteur est présent en une quantité allant de 10% à 40%, de préférence de 10 à 30%, avantageusement de 10 à 25%, basé sur le poids total de la composition. Le polymère thermoplastique conducteur est de préférence présent dans une proportion massique allant de 10% à 15%, ou de 15% à 20%, ou de 20% à 25%, ou de 25% à 30%, ou de 30% à 35%, ou de 35% à 40%, basé sur le poids total de la composition de plaque bipolaire. La seconde charge conductrice peut être présente dans une proportion massique de 60 à 90%, ou de 60 à 65%, ou de 65 à 70%, ou de 70 à 75%, ou de 75 à 80%, ou de 80 àAccording to one embodiment, the conductive thermoplastic polymer is present in an amount ranging from 10% to 40%, preferably from 10 to 30%, advantageously from 10 to 25%, based on the total weight of the composition. The conductive thermoplastic polymer is preferably present in a mass proportion ranging from 10% to 15%, or from 15% to 20%, or from 20% to 25%, or from 25% to 30%, or from 30% to 35 %, or 35% to 40%, based on the total weight of the bipolar plate composition. The second conductive filler can be present in a mass proportion of 60 to 90%, or from 60 to 65%, or from 65 to 70%, or from 70 to 75%, or from 75 to 80%, or from 80 to
85%, ou de 85 à 90%, basé sur le poids total de la composition de plaque bipolaire. 85%, or 85 to 90%, based on the total weight of the bipolar plate composition.
L’invention concerne également une composition de plaque bipolaire fabriquée au moyen du procédé décrit ci-dessus.  The invention also relates to a bipolar plate composition made by the method described above.
Selon un autre aspect, l’invention a trait à un procédé de fabrication d’une plaque bipolaire comprenant les étapes suivantes:  According to another aspect, the invention relates to a process for manufacturing a bipolar plate comprising the following steps:
préparer une composition selon le procédé décrit ci-dessus ;  preparing a composition according to the method described above;
soumettre la composition à un moulage par compression.  subjecting the composition to compression molding.
De préférence, la composition pour plaque bipolaire est soumise à un moulage par compression sous forme de poudre.  Preferably, the composition for bipolar plate is subjected to compression molding in the form of powder.
Le procédé selon l’invention peut comprendre en outre une étape de broyage de cette poudre, par exemple au moyen d’un broyeur à disques.  The method according to the invention may further comprise a step of grinding this powder, for example by means of a disc mill.
Le moulage par compression de compositions destinées à produire des plaques bipolaires peut être réalisé en introduisant ladite composition dans un moule, par exemple un moule en acier inoxydable, qui est ensuite fermé et chauffé à une température allant de 200°C à 350°C, de préférence de 250°C à 300°C. Ensuite, une force de compression de 300 t à 800 t, de préférence de 400 t à 600 t, est appliquée au moule, pour un moule de dimensions de 100000 à 150000 mm2. Typiquement, une force de compression de 500 t est appliquée lorsque la taille du moule est de 130000 mm2 et une force de compression de 300 t est appliquée lorsque la taille du moule est de 44000 mm2. Le moule est ensuite refroidi à une température de 50°C à l20°C, de préférence de 60°C à l00°C, et la plaque est démoulée. Compression molding of compositions intended to produce bipolar plates can be carried out by introducing said composition into a mold, for example a stainless steel mold, which is then closed and heated to a temperature ranging from 200 ° C. to 350 ° C., preferably from 250 ° C to 300 ° C. Then, a compression force of 300 t to 800 t, preferably from 400 t to 600 t, is applied to the mold, for a mold with dimensions of 100,000 to 150,000 mm 2 . Typically, a compression force of 500 t is applied when the mold size is 130,000 mm 2 and a compression force of 300 t is applied when the mold size is 44,000 mm 2 . The mold is then cooled to a temperature of 50 ° C to 120 ° C, preferably from 60 ° C to 100 ° C, and the plate is removed from the mold.
Avantageusement, la plaque bipolaire présente au moins une des caractéristiques suivantes, et de préférence toutes ces caractéristiques :  Advantageously, the bipolar plate has at least one of the following characteristics, and preferably all of these characteristics:
une résistivité surfacique égale ou inférieure à 0,01 Ohm.cm ;  a surface resistivity equal to or less than 0.01 Ohm.cm;
une résistivité volumique égale ou inférieure à 0,03 Ohm.cm;  a volume resistivity equal to or less than 0.03 Ohm.cm;
une conductivité thermique égale ou supérieure à 10 W/m/K;  a thermal conductivity of 10 W / m / K or more;
une résistance à la flexion égale ou supérieure à 25 N/mm2; a flexural strength of 25 N / mm 2 or more ;
une résistance à la compression égale ou supérieure à 25 N/mm2.a compressive strength of 25 N / mm 2 or more .
La résistance à la flexion est mesurée selon la norme DIN EN ISO 178. La résistance à la compression est mesurée selon la norme ISO 604. La conductivité thermique est mesurée selon la technique Laser Llash selon la norme DIN EN ISO 821. La résistivité surfacique est mesurée au moyen d’échantillons de sonde à quatre points sur des échantillons broyés ayant une épaisseur de 4 mm. La résistivité volumique est mesurée avec une installation à deux électrodes et une pression de contact de 1 N/mm2 sur des échantillons surfacés ayant un diamètre de 13 mm et une épaisseur de 2 mm. The flexural strength is measured according to DIN EN ISO 178. The compressive strength is measured according to ISO 604. The thermal conductivity is measured using the Laser Llash technique according to DIN EN ISO 821. The surface resistivity is measured by means of four-point probe samples on ground samples having a thickness of 4 mm. The volume resistivity is measured with an installation with two electrodes and a contact pressure of 1 N / mm 2 on surfaced samples having a diameter of 13 mm and a thickness of 2 mm.
Selon certains modes de réalisation, la plaque bipolaire présente une résistivité surfacique égale ou inférieure à 0,008 Ohm.cm, ou égale ou inférieure à 0,005 Ohm.cm, ou égale ou inférieure à 0,003 Ohm.cm, ou égale ou inférieure à 0.001 Ohm.cm.  According to certain embodiments, the bipolar plate has a surface resistivity equal to or less than 0.008 Ohm.cm, or equal to or less than 0.005 Ohm.cm, or equal or less than 0.003 Ohm.cm, or equal or less than 0.001 Ohm. cm.
Selon certains modes de réalisation, la plaque bipolaire présente une résistivité traversante égale ou inférieure à 0,025 Ohm.cm, ou égale ou inférieure à 0,02 Ohm.cm, ou égale ou inférieure à 0,015 Ohm.cm.  According to certain embodiments, the bipolar plate has a through resistivity equal to or less than 0.025 Ohm.cm, or equal to or less than 0.02 Ohm.cm, or equal to or less than 0.015 Ohm.cm.
Selon certains modes de réalisation, la plaque bipolaire possède une conductivité thermique égale ou supérieure à 15 W/m/K, ou égale ou supérieure à 20 W/m/K.  According to certain embodiments, the bipolar plate has a thermal conductivity equal to or greater than 15 W / m / K, or equal or greater than 20 W / m / K.
Selon certains modes de réalisation, la plaque bipolaire présente une résistance à la flexion égale ou supérieure à 30 N/mm2, ou égale ou supérieure à 35 N/mm2. According to certain embodiments, the bipolar plate has a flexural strength equal to or greater than 30 N / mm 2 , or equal to or greater than 35 N / mm 2 .

Claims

REVENDICATIONS
1. Procédé de fabrication d’une composition comprenant les étapes suivantes: o mélanger un polymère thermoplastique à l'état fondu avec une première charge conductrice afin d’obtenir un polymère thermoplastique conducteur; 1. A method of manufacturing a composition comprising the following steps: o mixing a thermoplastic polymer in the molten state with a first conductive filler in order to obtain a conductive thermoplastic polymer;
o broyer ledit polymère thermoplastique conducteur pour le réduire en poudre;  o grinding said conductive thermoplastic polymer to reduce it to powder;
o mélanger la poudre de polymère thermoplastique conducteur avec une seconde charge conductrice.  o mix the conductive thermoplastic polymer powder with a second conductive filler.
2. Procédé selon la revendication 1 , dans lequel la seconde charge conductrice est le graphite. 2. The method of claim 1, wherein the second conductive filler is graphite.
3. Procédé selon l’une des revendications 1 ou 2, dans lequel la première charge conductrice est choisie parmi : les polymères conducteurs électroniques, le noir de carbone, les nanotubes de carbone, le graphène, le graphite, les fibres de carbone et leurs mélanges, de préférence la première charge conductrice étant le noir de carbone. 3. Method according to one of claims 1 or 2, wherein the first conductive filler is chosen from: electronic conductive polymers, carbon black, carbon nanotubes, graphene, graphite, carbon fibers and their mixtures, preferably the first conductive filler being carbon black.
4. Procédé selon l’une des revendications 1 à 3, dans lequel l’étape où la poudre de polymère thermoplastique conducteur est mélangée avec une seconde charge conductrice est une étape de compoundage effectuée dans une extrudeuse. 4. Method according to one of claims 1 to 3, wherein the step where the conductive thermoplastic polymer powder is mixed with a second conductive filler is a compounding step carried out in an extruder.
5. Procédé selon l’une des revendications 1 à 4, dans lequel la première charge conductrice constitue de 0,1% à 35% en poids, de préférence de 1% à 20% en poids, avantageusement de 2,5% à 15% en poids, basé sur le poids dudit polymère thermoplastique conducteur. 5. Method according to one of claims 1 to 4, wherein the first conductive filler constitutes from 0.1% to 35% by weight, preferably from 1% to 20% by weight, advantageously from 2.5% to 15 % by weight, based on the weight of said conductive thermoplastic polymer.
6. Procédé selon l’une des revendications 1 à 5, dans lequel le polymère thermoplastique conducteur est présent en une quantité allant de 10% à 40%, de préférence de 10 à 30%, avantageusement de 10 à 25% et la seconde charge conductrice est présente en une quantité allant de 60% à 90%, de préférence de 70 à 90%, avantageusement de 75 à 90% basé sur le poids total de la composition. 6. Method according to one of claims 1 to 5, wherein the conductive thermoplastic polymer is present in an amount ranging from 10% to 40%, preferably from 10 to 30%, advantageously from 10 to 25% and the second conductive filler is present in an amount ranging from 60% to 90%, preferably from 70 to 90%, advantageously from 75 to 90% based on the total weight of the composition.
7. Procédé selon l’une des revendications 1 à 6, dans lequel le polymère thermoplastique conducteur est broyé en une poudre ayant un diamètre moyen en volume (Dv50) allant de 0,1 pm à 1 mm. 7. Method according to one of claims 1 to 6, wherein the conductive thermoplastic polymer is ground into a powder having a volume average diameter (Dv50) ranging from 0.1 pm to 1 mm.
8. Procédé selon l’une des revendications 1 à 7, dans lequel le polymère thermoplastique conducteur est choisi parmi le polypropylène, le polyéthylène et le poly(sulfure de phénylène). 8. Method according to one of claims 1 to 7, wherein the conductive thermoplastic polymer is chosen from polypropylene, polyethylene and poly (phenylene sulfide).
9. Composition comprenant une seconde charge conductrice et des particules d’un polymère thermoplastique conducteur, caractérisée en ce que les particules du polymère thermoplastique conducteur comprennent une matrice de polymère thermoplastique dans laquelle est dispersée une première charge conductrice. 9. Composition comprising a second conductive filler and particles of a conductive thermoplastic polymer, characterized in that the particles of the conductive thermoplastic polymer comprise a matrix of thermoplastic polymer in which a first conductive filler is dispersed.
10. La composition selon la revendication 9, dans laquelle la seconde charge conductrice est le graphite et/ou la première charge conductrice est choisie parmi : les polymères conducteurs électroniques, le noir de carbone, les nanotubes de carbone, le graphène, le graphite, les fibres de carbone et leurs mélanges, la première charge conductrice étant de préférence le noir de carbone. 10. The composition according to claim 9, in which the second conductive filler is graphite and / or the first conductive filler is chosen from: electronic conductive polymers, carbon black, carbon nanotubes, graphene, graphite, carbon fibers and their mixtures, the first conductive filler preferably being carbon black.
11. La composition selon l’une des revendications 9 ou 10, dans laquelle la seconde charge conductrice est présente en une quantité allant de 60% à 90%, de préférence de 70 à 90%, avantageusement de 75 à 90% basé sur le poids total de la composition et/ou la première charge conductrice est présente en une quantité de 0,1% à 35% en poids, de préférence de 1% à 20% en poids, avantageusement de 2,5% à 15% en poids basé sur le poids du polymère thermoplastique conducteur. 11. The composition according to one of claims 9 or 10, in which the second conductive filler is present in an amount ranging from 60% to 90%, preferably from 70 to 90%, advantageously from 75 to 90% based on the total weight of the composition and / or the first conductive filler is present in an amount of 0.1% to 35% by weight, preferably from 1% to 20% by weight, advantageously from 2.5% to 15% by weight based on the weight of the conductive thermoplastic polymer.
12. Procédé de fabrication d’une plaque bipolaire, comprenant les étapes suivantes: 12. Method for manufacturing a bipolar plate, comprising the following steps:
■ préparer une composition selon le procédé selon l’une des revendications 1 à 8 ou fournir une composition selon l’une des revendications 9 à 11; ■ prepare a composition according to the method according to one of claims 1 to 8 or provide a composition according to one of claims 9 to 11;
■ soumettre la composition à un moulage par compression. ■ subjecting the composition to compression molding.
13. Plaque bipolaire obtenue par le procédé selon la revendication 12 ou comprenant la composition selon l’une des revendications 9 à 11. 13. Bipolar plate obtained by the method according to claim 12 or comprising the composition according to one of claims 9 to 11.
EP19790668.8A 2018-09-21 2019-09-18 Compositions for bipolar plates and methods for manufacturing said compositions Pending EP3853936A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR1858598A FR3086292B1 (en) 2018-09-21 2018-09-21 COMPOSITIONS FOR BIPOLAR PLATES AND METHODS OF MANUFACTURING SUCH COMPOSITIONS
PCT/FR2019/052175 WO2020058627A1 (en) 2018-09-21 2019-09-18 Compositions for bipolar plates and methods for manufacturing said compositions

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EP3853936A1 true EP3853936A1 (en) 2021-07-28

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US (1) US20210354332A1 (en)
EP (1) EP3853936A1 (en)
JP (1) JP7460610B2 (en)
KR (1) KR20210060499A (en)
CN (1) CN112655104A (en)
FR (1) FR3086292B1 (en)
WO (1) WO2020058627A1 (en)

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FR2817076A1 (en) 2000-11-20 2002-05-24 Atofina MICROCOMPOSITE POWDER BASED ON AN ELECTRICAL CONDUCTOR AND A FLUOROPOLYMER AND OBJECTS MADE WITH THIS POWDER
FR2834818B1 (en) 2002-01-14 2006-09-15 Atofina MICROCOMPOSITE POWDER BASED ON GRAPHITE PLATES AND A FLUOROPOLYMER AND OBJECTS MADE WITH THE POWDER
WO2003069707A1 (en) 2002-02-13 2003-08-21 Dupont Canada Inc. Method for manufacturing fuel cell separator plates under low shear strain
KR100764008B1 (en) * 2006-10-27 2007-10-09 이중희 Preparing method of polymer hybrid composite for bipolar plate of fuel cell and resin composition for bipolar plate
JP5224860B2 (en) * 2008-03-24 2013-07-03 信越ポリマー株式会社 Fuel cell separator and method for producing the same
KR101011014B1 (en) * 2008-06-13 2011-01-26 한국타이어 주식회사 Process for preparing separator material for a fuel cell having high electrical conductivity, separator for a fuel cell and feul cell
JP5349267B2 (en) * 2009-12-03 2013-11-20 信越ポリマー株式会社 Manufacturing method of fuel cell separator and fuel cell separator
FR3021811B1 (en) 2014-05-27 2016-07-29 Commissariat Energie Atomique METHOD FOR MANUFACTURING COMPOSITE BIPOLAR PLATE, COMPOSITE BIPOLAR PLATE, USES THEREOF, AND FUEL CELL COMPRISING SUCH COMPOSITE BIPOLAR PLATE

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JP7460610B2 (en) 2024-04-02
KR20210060499A (en) 2021-05-26
WO2020058627A1 (en) 2020-03-26
CN112655104A (en) 2021-04-13
FR3086292B1 (en) 2021-05-07
JP2022501464A (en) 2022-01-06
FR3086292A1 (en) 2020-03-27
US20210354332A1 (en) 2021-11-18

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