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
  • H01M4/0471—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 having different levels of crystallinity.
• the invention relates firstly to a Li-ion battery electrode comprising an active load for an anode or cathode, an electronically conductive load, and a fluoropolymer (based) binder.
• said binder consists of a mixture of at least two fluoropolymers: a fluoropolymer A which comprises at least one copolymer of vinylidene fluoride (VDF) and of hexafluoropropylene (HFP) having a level of HFP greater than or equal to 3% by weight, and a fluoropolymer B which comprises a homopolymer of VDF and / or at least one VDF-HFP copolymer, said fluoropolymer B having a lower mass content of HFP of at least 3% by weight.
• VDF vinylidene fluoride
• HFP hexafluoropropylene
• the fluoropolymer A comprises 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%, advantageously greater than or equal to 9%.
• Its mass content in the binder is greater than or equal to 1% by weight and less than or equal to 20%, preferably greater than or equal to 5% and less than or equal to 20%.
• the fluoropolymer B comprises at least one VDF-HFP copolymer having an HFP rate by mass which is at least 3% lower than the mass rate of HFP of the polymer A. Its mass rate in the binder is less than or equal to 99 % and greater than or equal to 80%, preferably it is less than or equal to 95% and greater than or equal to 80%.
• 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 method which allows to obtain an electrode formulation applicable on a metal support by a “solvent-free” process; deposition of said electrode formulation on the metal substrate by a so-called “solvent-free” process, to obtain a Li-ion battery electrode, and the consolidation of said electrode by thermal and / or thermomechanical 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 prior art. More specifically, it provides a technology that makes it possible to:
• 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 allows a decrease in the level of binder required in the electrode, as well as a reduction in temperature and heat treatment time to control 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 (based) binder.
• said binder consists of a mixture of at least two fluoropolymers: a fluoropolymer A which comprises at least one copolymer of vinylidene fluoride (VDF) and of hexafluoropropylene (HFP) having a level of HFP greater than or equal to 3% by weight, and a fluoropolymer B which comprises a homopolymer of VDF and / or at least one VDF-HFP copolymer, said fluoropolymer B having a lower mass content of HFP of at least 3% by weight. weight relative to the mass rate of HFP of polymer A.
• VDF vinylidene fluoride
• HFP hexafluoropropylene
• said electrode comprises the following characters, combined where appropriate. The contents indicated are expressed by weight, unless otherwise indicated.
• Fluoropolymer A comprises 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%, advantageously greater or equal to 9%.
• Said VDF-HFP copolymer has an HFP level of less than or equal to 55%, preferably 50%.
• VDF-HFP copolymer present in the fluoropolymer A is not very crystalline.
• the incorporation of this copolymer into the electrode makes it possible in particular to control the degree of coverage of the surface of the active filler by the binder.
• the fluoropolymer A consists of a single VDF-HFP copolymer with an HFP rate greater than or equal to 3%.
• the level of HFP in this VDF-HFP copolymer is between 6% and 55% limits included, preferably between 9% and 50% limits included.
• 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%.
• each of the copolymers has an HFP level of between 6% and 55% limits included, preferably between 9% and 50% limits included.
• the molar composition of the units in fluoropolymers can be determined by various means such as infrared spectroscopy or RAMAN spectroscopy.
• Multi-core NMR techniques can also be implemented, in particular proton (1H) and fluorine (19F), by analysis of a solution of the polymer in an appropriate deuterated solvent.
• the NMR spectrum is recorded on an NMR-FT spectrometer equipped with a multinuclear probe. The specific signals given by the different monomers are then identified in the spectra produced according to one or the other nucleus.
• Fluoropolymer B comprises at least one VDF-HFP copolymer having a mass rate of HFP at least 3% lower than the mass rate of HFP of polymer A.
• each binder has a different ability to deform and to flow between and at the surface of the active charges under the effect of temperature and pressure.
• the slightly crystalline fluorinated binder A having a lower melting temperature and / or being more deformable than the crystalline fluorinated binder B has an advantageous tendency to spread on the surface of the active charges and thus promote the cohesion of the electrode.
• the fluoropolymer B is a homopolymer of vinylidene fluoride (VDF) or a mixture of homopolymers of vinylidene fluoride.
• the fluoropolymer B consists of a single VDF-HFP copolymer.
• the level of HFP in this VDF-HFP copolymer is between 1% and 10%, limits included.
• the level of HFP in this VDF-HFP copolymer is between 1% and 15%, limits included.
• the fluoropolymer B is a mixture of PVDF homopolymer with a VDF-HFP copolymer or else a mixture of two or more VDF-HFP copolymers.
• 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 mixture contains: i. a mass content of polymer A greater than or equal to 1% and less than or equal to 20%, preferably greater than or equal to 5% and less than or equal to 20%, and ii. a mass content of polymer B less than or equal to 99% and greater than or equal to 80%, preferably less than or equal to 95% and greater than or equal to 80%.
• 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 use 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 lower specific surface area 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: plasticizer, ionic liquid, dispersing agent for conductive fillers, flow agent for the formulation, fibrillation agent such as polytetrafluoroethylene (PTFE). 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:
• thermo- consolidation of said electrode by heat treatment (application of a temperature of up to 50 ° C above the melting point of the polymer, without mechanical pressure), and / or thermo-mechanical treatment such as calendering or thermo-compression.
• solvent-free process is understood to mean a process which does not require a residual solvent evaporation step downstream of the deposition step.
• Another embodiment of the method of manufacturing an electrode comprises the following steps: mixing of the active filler, of the polymer binder and of the conductive filler using a process which makes it possible to obtain an electrode formulation whose constituents are mixed homogeneously;
• thermo-mechanical process such as extrusion, calendering or thermo-compression
• the polymers A and B are used 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, either polymer A, or polymer B, or both, is mixed with a conductive filler 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, the pre-mixed conductive filler and the possible fluoropolymer not yet used are mixed with the active load. 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 (bulk density 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 (bulk density 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 for 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 ). 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.
• 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 press with trays. 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 characterized by a melt viscosity of 2600 Pa.s at 100 s 1 and 230 ° C.
• PVDF 3 Copolymer of vinylidene fluoride (VDF) and vinylidene hexafluoride (HFP) at 12% by weight of HFP characterized by a melt viscosity of 2500 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 PVDLs 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 PVDL.

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