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 .

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