Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
  • H01M4/621—Binders
  • H01M4/622—Binders being polymers
  • H01M4/623—Binders being polymers fluorinated polymers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/04—Processes of manufacture in general
  • H01M4/0402—Methods of deposition of the material
  • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/04—Processes of manufacture in general
  • H01M4/0402—Methods of deposition of the material
  • H01M4/0421—Methods of deposition of the material involving vapour deposition
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/04—Processes of manufacture in general
  • H01M4/043—Processes of manufacture in general involving compressing or compaction
  • H01M4/0435—Rolling or calendering
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/04—Processes of manufacture in general
  • H01M4/0471—Processes of manufacture in general involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/139—Processes of manufacture
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
  • H01M4/624—Electric conductive fillers
  • H01M4/625—Carbon or graphite
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/64—Carriers or collectors
  • H01M4/66—Selection of materials
  • H01M4/661—Metal or alloys, e.g. alloy coatings
• • 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
  • H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes
• • 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

Definitions

• the present invention relates generally to the field of electrical energy storage in rechargeable secondary batteries of Li-ion type. More specifically, the invention relates to an electrode formulation for a Li-ion battery, comprising a binder based on a mixture of fluoropolymers. The invention also relates to a process for preparing electrodes using said formulation, by a solvent-free deposition technique on a metal substrate. Finally, the invention relates to an electrode obtained by this process as well as to secondary Li-ion batteries comprising at least one such electrode.
• a Li-ion battery includes at least one negative electrode or anode coupled to a copper current collector, a positive electrode or cathode coupled to an aluminum current collector, a separator, and an electrolyte.
• the electrolyte consists of a lithium salt, usually lithium hexafluorophosphate, mixed with a solvent which is a mixture of organic carbonates, chosen to optimize the transport and dissociation of ions.
• Rechargeable or secondary batteries are more advantageous than primary (non-rechargeable) batteries because the associated chemical reactions that take place at the positive and negative electrodes of the battery are reversible.
• the electrodes of the secondary cells can be regenerated several times by the application of an electric charge.
• Many advanced electrode systems have been developed to store electrical charge. At the same time, many efforts have been devoted to the development of electrolytes capable of improving the capacities of electrochemical cells.
• the electrodes generally comprise at least one current collector on which is deposited, in the form of a film, a composite material which consists of: a so-called active material because it has electrochemical activity with respect to the lithium, a polymer which acts as a binder, plus one or more electronically conductive additives which are generally carbon black or acetylene black, and optionally a surfactant. Binders are counted among the so-called inactive components because they do not directly contribute to the capacity of cells.
• a composite material which consists of: a so-called active material because it has electrochemical activity with respect to the lithium, a polymer which acts as a binder, plus one or more electronically conductive additives which are generally carbon black or acetylene black, and optionally a surfactant. Binders are counted among the so-called inactive components because they do not directly contribute to the capacity of cells.
• binders The main relevant physical and chemical properties of binders are: thermal stability, chemical and electrochemical stability, tensile strength (strong adhesion and cohesion), and flexibility.
• the main objective of the use of a binder is to form stable networks of the solid components of the electrodes, that is to say the active materials and the conductive agents (cohesion).
• the binder must ensure close contact of the composite electrode to the current collector (adhesion).
• PVDF Poly (vinylidene fluoride)
• NMP N-methyl pyrrolidone
• the use of organic solvents requires the significant investment of means of production, recycling and purification. If lithium-ion battery electrodes are produced using a solvent-free process, meeting the same specifications, then the carbon footprint and production costs will be significantly reduced.
• the article by Wang et al. (J. Electrochem. Soc. 2019 166 (10): A2151-A2157) analyzed the influence of several properties of PVDF binders on electrodes manufactured by a dry powder coating process (electrostatic spray deposition). To improve the adhesion to the metal substrate and the cohesion of the electrode, a one hour heat treatment step at 200 ° C is performed. The electrode contains 5% by weight of binder. Two binders of different viscosities are used: HSV900 (50 kPoise) and one grade of Alfa Aesar (25 kPoise).
• the fluid binder leads to the best adhesion but a poorer behavior at high discharge speed than the viscous binder (the capacity retention improves under these conditions, from 17% to 50% without reducing the bond strength and long-term cycling performance).
• the porosity of the binder layer increases with the molecular weight of PVDF.
• the aim of the invention is therefore to provide a Li-ion battery electrode composition capable of being transformed.
• the invention also aims to provide a method for manufacturing an electrode for a Li-ion battery using said formulation, by a solvent-free deposition technique on a metal substrate. Finally, the invention relates to an electrode obtained by this process.
• the invention aims to provide rechargeable Li-ion secondary batteries comprising at least one such electrode.
• the technical solution proposed by the present invention is an electrode composition for a Li-ion battery, comprising a binder based on a mixture of at least two fluoropolymers, one of which carries one or more functionalities.
• the invention relates firstly to a Li-ion battery electrode comprising an active load for anode or cathode, an electronically conductive load, and a fluoropolymer (based) binder.
• said binder consists of a mixture of two fluoropolymers, a non-functionalized fluoropolymer A, and a fluoropolymer B carrying at least one functionality.
• the invention also relates to a method of manufacturing a Li-ion battery electrode, said method comprising the following steps: mixing the active filler, the polymer binder and the conductive filler using a thermo-mixture. mechanical without solvent, to obtain an electrode formulation; depositing said electrode formulation on the metal substrate, to obtain a Li-ion battery electrode, and consolidating said electrode by heat treatment.
• the invention also relates to a Li-ion battery electrode manufactured by the method described above.
• Another object of the invention is a Li-ion secondary battery comprising a negative electrode, a positive electrode and a separator, in which at least one electrode is as described above.
• the present invention overcomes the drawbacks of the state of the art. It more particularly provides a technology which makes it possible to: control the distribution of the binder and of the conductive filler at the surface of the active filler; ensure the cohesion and mechanical integrity of the electrode, guaranteeing good film formation or consolidation of the formulations which may be difficult to achieve for solvent-free processes; generate adhesion to the metal substrate; ensuring the homogeneity of the electrode composition across the thickness and width of the electrode; control the porosity of the electrode and ensure its homogeneity in the thickness and the width of the electrode; reduce the overall level of binder in the electrode, which, in the case of known solvent-free processes, remains higher compared to a standard “slurry” process, improve the mechanical strength of self-supported films of electrode formulations.
• the formulation makes it possible to obtain a mechanical behavior. sufficient for handling and winding / unwinding phases.
• the advantage of this technology is to improve the following properties of the electrode: the homogeneity of the composition in thickness, the homogeneity of the porosity, the cohesion, and the adhesion to the metal substrate. It also makes it possible to reduce the level of binder required in the electrode, as well as to reduce the temperature and / or the heat treatment time to control the porosity and improve adhesion.
• the invention relates to a Li-ion battery electrode comprising an active load for anode or cathode, an electronically conductive load, and a fluoropolymer binder.
• said binder consists of a mixture of two fluoropolymers: a non-functionalized fluoropolymer A, and a fluoropolymer B carrying at least one functionality.
• said electrode comprises the following characters, combined where appropriate. The contents indicated are expressed by weight, unless otherwise indicated.
• fluoropolymer is meant a polymer comprising fluorine -F groups.
• the fluoropolymer contains in its chain at least one monomer chosen from compounds containing a vinyl group capable of opening in order to polymerize and which contains, directly attached to this vinyl group, at least one fluorine atom, a fluoroalkyl group or a fluoroalkoxy group.
• the fluoropolymer entering into the composition of each of the polymers A and B can be: a homopolymer, or a copolymer comprising two fluorinated monomers listed above, or alternatively mixtures of homopolymer and of copolymer, or mixtures of two copolymers; it can also include non-fluorinated comonomers such as ethylene.
• Terpolymers, such as that based on VDF, TFE and HFP, are excluded from the scope of the invention.
• the binder is a mixture of fluoropolymers A and B of which only the fluoropolymer B carries function (s) capable (s) of developing adhesion to a metal substrate and ensure good cohesion of the material making up the electrode.
• the fluoropolymer B comprises monomer units bearing at least one carboxylic acid function.
• the function is introduced on the fluoropolymer B by a chemical reaction which can be grafting or a copolymerization of the fluorinated monomer with a monomer bearing at least one -COOH group and a vinyl function capable of copolymerizing with the fluorinated monomer, according to well-known techniques. known to those skilled in the art.
• the functional group carries a carboxylic acid function which is a group of (meth) acrylic acid type chosen from acrylic acid, methacrylic acid, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate and hydroxyethylhexyl (meth) acrylate.
• the units carrying the carboxylic acid function further comprise a heteroatom chosen from oxygen, sulfur, nitrogen and phosphorus.
• the functionality is introduced into the fluoropolymer B via the transfer agent used during the synthesis process.
• the transfer agent is a polymer with a molar mass of less than or equal to 20,000 g / mol and carrying a carboxylic acid group.
• An example of such a transfer agent are acrylic acid oligomers.
• the content of functional groups in Polymer B is at least 0.01 mole%, preferably at least 0.1 mole%, and at most 15 mole%, preferably at most 10 mole%.
• the fluoropolymers used in the invention can be obtained by known polymerization methods such as solution, emulsion or suspension polymerization. According to one embodiment, they are prepared by an emulsion polymerization process in the absence of fluorinated surfactant.
• said binder contains: a fluoropolymer A which comprises a homopolymer of VDF and / or at least one copolymer of vinylidene fluoride (VDF) and of hexafluoropropylene (HFP), and a functionalized fluoropolymer B which comprises monomer units of VDF or
• the fluoropolymer B carrying at least one carboxylic acid function.
• the fluoropolymer A comprises a VDF homopolymer and / or at least one VDF-HFP copolymer having an HFP level greater than or equal to 3% by weight, preferably greater than or equal to 6%.
• Said VDF-HFP copolymer has an HFP level of less than or equal to 55%, preferably 50%.
• the fluoropolymer A is a VDF homopolymer or a mixture of VDF homopolymers.
• the fluoropolymer A consists of a single VDF-HFP copolymer with an HFP rate greater than or equal to 3%.
• the fluoropolymer A consists of a mixture of two or more VDF-HFP copolymers, the HFP level of each copolymer being greater than or equal to 3%.
• the fluoropolymer A consists of a mixture of a PVDF homopolymer and a VDF-HFP copolymer having an HFP level greater than or equal to 3%.
• the fluoropolymer B comprises units of VDF and acrylic or methacrylic acid.
• the fluoropolymer B comprises units of VDF, HFP and acrylic or methacrylic acid.
• the polymeric binder comprises from 10% to 99% by weight of polymer A and from 1% to 90% by weight of polymer B.
• said mixture comprises: i. a mass content of polymer A greater than or equal to 10% and less than or equal to 99%, preferably greater than or equal to 10% and less than or equal to 95%, advantageously greater than or equal to 10% and less than or equal to 55%, and ii. a mass content of polymer B greater than or equal to 1% and less than or equal to 90%, preferably greater than 5% and less than 90%, advantageously greater than or equal to 45% and less than or equal to 90%.
• the materials active at the negative electrode are generally lithium metal, graphite, silicon / carbon composites, silicon, fluorinated graphites of CF X type with x between 0 and 1 and titanates of LiTisOn type.
• the materials active at the positive electrode are generally of the L1MO 2 type, of the L1MPO 4 type, of the L1 2 MPO 3 F type, of the LLMSiCL type where M is Co, Ni, Mn, Fe or a combination of these, of the type LiM CL or type Sx.
• the conductive fillers are chosen from carbon blacks, graphites, natural or synthetic, carbon fibers, carbon nanotubes, metal fibers and powders, and conductive metal oxides. Preferably, they are chosen from carbon blacks, graphites, natural or synthetic, carbon fibers and carbon nanotubes.
• a mixture of these conductive fillers can also be produced.
• the reuse of carbon nanotubes in association with another conductive filler such as carbon black can have the advantages of reducing the level of conductive charges in the electrode and of reducing the level of polymer binder due to a specific surface area. less compared to carbon black.
• a polymeric dispersant which is distinct from said binder, is used in admixture with the conductive filler to break up the agglomerates present and to help its dispersion in the final formulation with the polymeric binder and the active filler.
• the polymeric dispersant is chosen from poly (vinyl pyrrolidone), poly (phenyl acetylene), poly (meta-phenylene vinylidene), polypyrrole, poly (para-phenylene benzobisoxazole, poly (vinyl alcohol), and mixtures thereof.
• the mass composition of the electrode is:
• polymer binder 25 to 0.05% polymer binder, preferably 25 to 0.5%
• At least one additive chosen from the list: plasticizers, ionic liquid, dispersing agent for conductive fillers, flow agent for the formulation, fibrillation agent such as polytetrafluoroethylene (PTLE). the sum of all these percentages being 100%.
• the invention also relates to a method of manufacturing a Li-ion battery electrode, said method comprising the following steps:
• solvent-free process is understood to mean a process which does not require a residual solvent evaporation step downstream of the deposition step.
• thermo-mechanical process such as extrusion, calendering or thermo-compression
• the polymers A and B are in powder form, the average particle size of which is between 10 nm and 1 mm, preferably between 50 nm and 500 ⁇ m and even more preferably between 50 nm and 50 ⁇ m.
• Fluoropolymer powder can be obtained by various methods.
• the powder can be obtained directly by a process of synthesis in emulsion or suspension by spray drying (“spray drying”), by lyophilization (“freeze drying”).
• the powder can also be obtained by grinding techniques, such as cryo-grinding.
• the particle size can be adjusted and optimized by selection or sieving methods.
• the polymers A and B are introduced at the same time as the active and conductive charges at the time of the mixing step.
• the polymers A and B are mixed together before mixing with the active and conductive fillers.
• a mixture of polymers A and B can be produced by co-atomization of the latexes of polymers A and B to obtain a mixture in powder form. The mixture thus obtained can, in turn, be mixed with the active and conductive fillers.
• Another embodiment of the mixing step consists of proceeding in two stages. First of all, either polymer A, or polymer B, or both, is mixed with a filler conductive by a solvent-free process or by co-atomization. This step makes it possible to obtain an intimate mixture of the binder and of the conductive filler. Then, in a second step, the binder and the pre-mixed conductive filler and the optional fluoropolymer not yet used are mixed with the active filler. The active filler is mixed with said intimate mixture using a solvent-free mixing process, to obtain an electrode formulation.
• Another embodiment of the mixing step is to proceed in two stages. First, either polymer A or polymer B, or both, is mixed with an active filler by a solvent-free process or a method of spraying a liquid containing the binder and / or the conductive filler onto a fluidized powder bed of the active charge. This step makes it possible to obtain an intimate mixture of the binder and the active filler. Then, in a second step, the binder, the active filler and any fluoropolymer not yet used are mixed with the conductive filler.
• Another embodiment of the mixing step is to proceed in two stages. First, an active filler is mixed with a conductive filler by a solvent-free process. Then, in a second step, either one mixes the two polymers A and B at the same time with the active filler and the conductive filler premixed, or one mixes the polymers A and B one after the other with the active filler and the conductive filler premixed.
• mixing by stirring mixing by air jet, mixing at high shear, mixing by V-mixer, mixing by mass mixer. screw, mixing by double cone, mixing by drum, conical mixing, mixing by double Z-arm, mixing in a fluidized bed, mixing in a planetary mixer, mixing by mechanical fusion, mixing by extrusion, mixing by calendering, mixing by grinding.
• mixing routes using a liquid such as water such as spray drying (co-atomization or “spray drying”) or a process for spraying a liquid containing the binder and / or the spray.
• a liquid such as water
• spray drying co-atomization or “spray drying”
• a process for spraying a liquid containing the binder and / or the spray conductive charge on a fluidized powder bed of the active charge.
• the formulation obtained can undergo a final step of grinding and / or sieving and / or selection to optimize the size of the particles of the formulation for the deposition step on the substrate. metallic.
• the powder formulation is characterized by bulk density. It is known in the art of the art that low density formulations are very restrictive in their uses and applications.
• the main components contributing to the increase in density are carbon additives such as carbon black (bulk density less than 0.4 g / cm 3 ), carbon nanotubes (bulk density less than 0.1 g / cm 3) ), polymer powders (density apparent less than 0.9 g / cm 3 ).
• carbon additives such as carbon black (bulk density less than 0.4 g / cm 3 ), carbon nanotubes (bulk density less than 0.1 g / cm 3) ), polymer powders (density apparent less than 0.9 g / cm 3 ).
• a combination of low density components in order to obtain an additive combining polymer binder / electronic conductor / other additive is recommended to improve the premixing step downstream of the deposition of the formulation described above.
• Such a combination can be carried out by the following methods: a) dispersion of the components in water or the organic solvent followed by the elimination of the solvent (co-atomization, lyophilization, extrusion / compounding in the presence of the solvent or of water , etc). b) dry or "wet" co-grinding using a grinding method known as a ball or ball mill, followed by a drying step if necessary.
• Such a method is particularly interesting for the significant increase in bulk density.
• the electrode is manufactured by a powdering method without solvent, by depositing the formulation on the metal substrate by a method of pneumatic spraying, electrostatic spraying, soaking in a fluidized powder bed, dusting, electrostatic transfer, deposition with rotating brushes, deposition with rotating metering rollers, calendering.
• the electrode is manufactured by a two-step solvent-free powder coating process.
• a first step which consists in making a self-supported film from the premixed formulation using a thermomechanical process such as extrusion, calendering or thermo-compression. Then, this self-supported film is assembled with the metal substrate by a process combining temperature and pressure such as calendering or thermo-compression.
• Metal electrode supports are usually aluminum for the cathode and copper for the anode.
• Metal substrates can be surface treated and have a conductive primer 5 ⁇ m or more thick.
• the supports can also be woven or non-woven carbon fiber.
• the consolidation of said electrode is carried out by heat treatment by passing it through an oven, under an infrared radiation lamp, in a calender with heated rollers or in a press with heated plates.
• Another alternative is a two-step process. First of all, the electrode undergoes a heat treatment in an oven, under an infrared radiation lamp or in contact with pressureless heating plates. Then a compression step at room temperature or hot is carried out using a calender or a plate press. This step makes it possible to adjust the porosity of the electrode and to improve the adhesion to the metal substrate.
• the invention also relates to a Li-ion battery electrode manufactured by the method described above.
• said electrode is an anode.
• said electrode is a cathode.
• Another object of the invention is a Li-ion secondary battery comprising a negative electrode, a positive electrode and a separator, in which at least one electrode is as described above.
• PVDF 1 Homopolymer of vinylidene fluoride characterized by a melt viscosity of 2500 Pa.s at 100 s 1 and 230 ° C.
• PVDF 2 Homopolymer of vinylidene fluoride bearing carboxylic acid functionalities with a functionality level of about 1% by mass, characterized by a viscosity of 4000 Pa.s at 100 s -1 and 230 ° C.
• Graphite C-NERGY ACTILION GHDR 15-4 Graphite marketed by the company IMERYS characterized by an average diameter by volume (Dv50) of 17 ⁇ m and a BET specific surface area of 4.1 m 2 / g.
• each mixture of fluoropolymer / graphite was sprinkled manually on the surface of an 18 ⁇ m thick copper current collector marketed by the company Hohsen Corp.
• the basis weight of the deposit produced is approximately 30 mg / cm 2 over an area of 5 ⁇ 5 cm 2 .
• the electrodes were consolidated in a press with heated plates by positioning a silicone paper between the deposited coating and the upper plate of the press. Each coating was pressed at 205 ° C under 6 bar for 10 minutes. At the end of this pressing phase, the electrodes were removed from the press and left to cool to room temperature. Then the silicone paper was removed.
• the goal of the manufacturing process is to achieve a coating of around one hundred microns on a metal support that has sufficient cohesion to allow manipulation of the electrodes without the coating cracking or cracking.
• the first thing to check is therefore the ability of the formulation to form a cohesive and homogeneous coating on the surface of the current collector.
• An indicator of this level of consolidation is the amount of powder / formulation that is transferred and remains stuck to the surface of the silicone paper after the pressing phase.
• a coating is judged to be well filmed and consolidated within the framework of the protocol described if no coating fragment remains stuck on the silicone paper.
• Another criterion of good mechanical integrity is the level of adhesion obtained on the collector, any spontaneous delamination of the coating to be avoided.
• Table 1 illustrates the composition of the PVDFs used in the examples according to the invention.
• Table 2 illustrates the properties of the electrodes, the composition of which is 95% by weight of graphite and 5% by weight of PVDF.
• Li-ion battery electrode comprising an active load for anode or cathode, an electronically conductive load, and a fluoropolymer binder, characterized in that: o said binder consists of a mixture of two fluoropolymers: a polymer fluorinated non-functionalized A, and a fluorinated polymer B carrying at least one functionality, o said fluorinated polymers A and B contain at least one fluorinated monomer chosen from: vinyl fluoride; vinylidene fluoride (VDF); trifluoroethylene (VF3); chlorotrifluoroethylene (CTFE); 1,2-difluoroethylene; tetrafluoroethylene (TFE); hexafluoropropylene (HFP); perfluoro (alkyl vinyl) ethers such as perfluoro (methyl vinyl) ether (PMVE), perfluoro (ethyl vinyl) ether (PEVE) and perfluoro (propyl vinyl) ether (PPVE); per
• fluoropolymer A which comprises a homopolymer of VDF and / or at least one copolymer of vinylidene fluoride (VDF) and hexafluoropropylene (HFP), and
• a functionalized fluoropolymer B which comprises monomer units of VDF or of VDF and of HFP, said fluoropolymer B carrying at least one carboxylic acid function.

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