Electrode formulations for Li-ion batteries and methods for manufacturing solvent-free electrodes

Abstract

The present invention relates generally to the field of electrical energy storage in rechargeable secondary batteries of the Li-ion type. More specifically, the present invention relates to an electrode formulation for Li-ion batteries, which comprises a binder based on a mixture of fluoropolymers. The present invention also relates to a method for preparing an electrode using said formulation by the technique of solvent-free deposition on a metal substrate. The present invention finally relates to the electrode obtained by this method, and to a Li-ion storage battery comprising at least one such electrode.

Description

[Technical Field]

[0001] The present invention generally relates to the field of electrical energy storage in lithium-ion rechargeable secondary batteries. More specifically, the present invention relates to electrode formulations for lithium-ion batteries comprising a binder based on a mixture of fluoropolymers. The present invention also relates to a method for preparing electrodes using the formulations by solvent-free deposition techniques on a metal substrate. The present invention ultimately relates to electrodes obtained by this method, and to lithium-ion batteries comprising at least one such electrode. [Background technology]

[0002] A lithium-ion battery comprises 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, generally lithium hexafluoride phosphate, mixed with a solvent which is a mixture of organic carbonates selected to optimize ion transport and dissociation.

[0003] Rechargeable or secondary batteries have advantages over primary batteries (non-rechargeable) because the related chemical reactions occurring at the positive and negative electrodes of the battery are reversible. The electrodes of secondary batteries can be regenerated multiple times by applying a charge. Many advanced electrode systems have been developed to store charge. In parallel, considerable effort has been devoted to developing electrolytes that can improve the capacity of electrochemical cells.

[0004] In that part, the electrode generally comprises at least one current collector on which a composite material is deposited in the form of a film, consisting of a material called an active substance to exhibit electrochemical activity toward lithium, a polymer acting as a binder, in addition to one or more conductive additives which are generally carbon black or acetylene black, and optionally a surfactant.

[0005] Binders are generally considered inert components because they do not directly contribute to the cell's capacity. However, their crucial role in electrode processing and their significant impact on the electrode's electrochemical performance are widely discussed. The main relevant physical and chemical properties of binders are thermal stability, chemical and electrochemical stability, tensile strength (strong adhesion and cohesiveness), and flexibility. The primary purpose of using binders is to form a stable network (cohesiveness) of the electrode's solid components, namely the active material and conductive agent. Furthermore, the binder must ensure adhesion between the composite electrode and the current collector.

[0006] Polyvinylidene fluoride (PVDF) is the most commonly used binder in lithium-ion batteries due to its excellent electrochemical stability, good adhesive capacity, and strong adhesion to electrode and current collector materials. However, PVDF is volatile, flammable, explosive, and highly toxic, and can only be dissolved in certain organic solvents such as N-methylpyrrolidone (NMP), which causes serious environmental problems. The use of organic solvents requires significant investment in production, recycling, and purification facilities. If lithium-ion battery electrodes are produced using solvent-free methods, the carbon footprint and production costs can be significantly reduced while adhering to the same specifications.

[0007] A paper by Wang et al. (J. Electrochem. Soc. 2019 166(10):A2151-A2157) analyzed the effects of several properties of PVDF binders on electrodes manufactured by a dry powder coating method (electrostatic spray deposition). A heat treatment step of 1 hour at 200°C is performed to improve adhesion to the metal substrate and electrode cohesiveness. The electrodes contain 5 wt% of the binder. Two binders with different viscosities are used: HSV900 (50 kpoise) and Alfa Aesar grade (25 kpoise).

[0008] Fluid binders provide the best adhesion but exhibit worse behavior at high discharge rates than viscous binders (under these conditions, the capacity retention rate is improved from 17% to 50% without reducing bond strength and long-term cycle performance). The porosity of the binder layer increases with the molecular weight of the PVDF.

[0009] However, the effect of different PVDF blends on the properties of electrodes manufactured by the dry coating method was not described.

[0010] Compared to conventional methods of producing electrodes in wet suspensions, dry (solvent-free) production methods are simpler, eliminate the release of volatile organic compounds, and offer the possibility of producing electrodes with greater thickness (>120 μm) and higher energy density in the final energy storage device. While changes in production technology have only a slight effect on the electrode active material, the polymer additives responsible for the electrode's mechanical integrity and its electrical behavior must be suitable for the new manufacturing conditions.

[0011] There is still a need to develop new electrode compositions for lithium-ion batteries that are suitable for use without the use of organic solvents.

[0012] Therefore, an object of the present invention is to provide a Li-ion battery electrode composition that can be converted.

[0013] The present invention also aims to provide a method for producing electrodes for Li-ion batteries using the aforementioned formulation by solvent-free deposition on a metal substrate. Finally, the present invention relates to electrodes obtained by this method.

[0014] Finally, the present invention aims to provide a rechargeable lithium-ion battery having at least one such electrode. [Prior art documents] [Non-patent literature]

[0015]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0016] The technical solution proposed by the present invention is an electrode composition for a Li-ion battery, which contains a binder based on a mixture of at least two fluoropolymers, one of which has one or more functional groups.

[0017] The present invention relates first to a Li-ion battery electrode containing an active filler for an anode or a cathode, an electron-conductive filler, and a fluoropolymer (system) binder. Characteristically, the binder consists of a mixture of two fluoropolymers, a non-functional fluoropolymer A and a fluoropolymer B having at least one functional group.

[0018] The present invention also relates to a method for producing a Li-ion battery electrode, comprising the following operations: - Using solvent-free thermomechanical mixing to mix an active filler, a polymer binder, and a conductive filler to obtain an electrode mixture, - Depositing the electrode mixture on a metal substrate to obtain a Li-ion battery electrode, - Consolidating the electrode by heat treatment, and relates to a method comprising the above. <000082>

[0019] The present invention also relates to a Li-ion battery electrode produced by the above method.

[0020] The present invention also provides a Li-ion secondary battery comprising a negative electrode, a positive electrode, and a separator, wherein at least one electrode is as described above.

[0021] The present invention makes it possible to overcome the drawbacks of the prior art. More specifically, the present invention - Controlling the distribution of the binder and the conductive filler on the surface of the active filler - Ensuring the cohesiveness and mechanical integrity of the electrode by guaranteeing good film formation or densification of the formulation, which may be difficult to achieve with solventless methods - Generating adhesiveness on the metal substrate - Ensuring the uniformity of the electrode composition in the thickness and width of the electrode - Controlling the porosity of the electrode and ensuring its uniformity in the thickness and width of the electrode - Reducing the overall binder content in the electrode, remaining higher than the binder content of the standard slurry method in the case of known solventless methods - Providing a technique that enables improving the mechanical strength of the self-supporting film of the electrode formulation. This means that when the solventless electrode production method proceeds through an intermediate stage of producing the self-supporting film of the formulation before assembly on the current collector, the formulation achieves sufficient mechanical behavior in the handling and winding / unwinding stages This means making it possible.

[0022] The advantages of this technique are to improve the following characteristics of the electrode: uniformity of the thickness composition, uniformity of the porosity, cohesiveness, and adhesiveness to the metal substrate. Also, the content of the binder required for the electrode can be reduced, the porosity can be controlled, and the heat treatment temperature and / or time can be reduced to improve adhesiveness.

Mode for Carrying Out the Invention

[0023] Here, the present invention will be described in more detail and non-limitingly in the following description.

[0024] According to a first aspect, the present invention relates to a Li-ion battery electrode comprising an active filler for an anode or cathode, an electronically conductive filler, and a fluoropolymer binder. Characteristically, the binder consists of a mixture of two fluoropolymers: a non-functional fluoropolymer A and a fluoropolymer B having at least one functional group.

[0025] According to various embodiments, the electrodes, when combined as appropriate, include the following features. The stated contents are expressed by weight unless otherwise specified.

[0026] The present invention utilizes fluoropolymers. The term "fluoropolymer" means a polymer containing a fluorine group -F. A fluoropolymer contains a vinyl group that can be ring-opened for polymerization, and contains in its chain at least one monomer selected from compounds containing at least one fluorine atom, a fluoroalkyl group, or a fluoroalkoxy group, directly bonded to this vinyl group.

[0027] Examples of fluorinated vinyl monomers include 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), 5-perfluoro(ethyl vinyl) ether (PEVE), and perfluoro(propyl vinyl) ether (PPVE); perfluoro(1,3-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole) (PDD); formula CF2 = CFOCF2CF(CF3)OCF2 Products of CF2X (wherein X is SO2F, CO2H, CH2OH, CH2OCN, or CH2OPO3H); products of CF2=CFOCF2CF2SO2F; products of F(CF2)nCH2OCF=CF2 (wherein n is 1, 2, 3, 4, or 5); products of R1CH2OCF=CF2 (wherein R1 is hydrogen or F(CF2)m, and m is equal to 1, 2, 3, or 4); products of R2OCF=CH2 (wherein R2 is F(CF2)p, and p is 1, 2, 3, or 4); perfluorobutylethylene (PFBE); 3,3,3-trifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-1-propene can be mentioned. The fluoropolymer may be a homopolymer or a copolymer, and it may also contain non-fluoro monomers such as ethylene.

[0028] The fluoropolymers that are part of each composition of polymers A and B may be homopolymers, copolymers containing two or more of the fluoromonomers listed above, mixtures of homopolymers and copolymers, or mixtures of two copolymers, and may also include non-fluorocomonomers such as ethylene. Terpolymers such as those based on VDF, TFE, and HFP are excluded from the scope of the present invention.

[0029] In the electrode composition according to the present invention, the binder is a mixture of fluoropolymers A and B, and only fluoropolymer B has one or more functional groups that can exhibit good adhesion to a metal substrate and good cohesiveness of the materials constituting the electrode.

[0030] Fluoropolymer B comprises monomer units having at least one carboxylic acid functional group.

[0031] The functional groups are introduced onto fluoropolymer B by a chemical reaction, which may be grafting or copolymerization, of a fluoromonomer with a monomer having at least one -COOH group and a vinyl functional group copolymerizable with the fluoromonomer, according to techniques well known to those skilled in the art.

[0032] According to one embodiment of fluoropolymer B, the functional group has a carboxylic acid functional group which is a (meth)acrylic acid type group selected from acrylic acid, methacrylic acid, hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, and hydroxyethylhexyl (meth)acrylate.

[0033] According to one embodiment, the unit having a carboxylic acid functional group further contains a heteroatom selected from oxygen, sulfur, nitrogen, and phosphorus.

[0034] According to one embodiment, functional groups are introduced onto fluoropolymer B by a transfer agent used during the synthesis process. The transfer agent is a polymer having a molar mass of 20,000 g / mol or less and containing carboxylic acid groups. Acrylic acid oligomers are an example of this type of transfer agent.

[0035] The functional group content of polymer B is at least 0.01 mol%, preferably at least 0.1 mol%, and at most 15 mol%, preferably at most 10 mol%.

[0036] The fluoropolymers used in the present invention can be obtained by known polymerization methods such as solution, emulsion, or suspension polymerization. According to one embodiment, they are prepared by emulsion polymerization in the absence of a fluorinated surfactant.

[0037] According to one embodiment, the binder is -Fluoropolymer A comprising a VDF homopolymer and / or at least one copolymer of vinylidene fluoride (VDF) and hexafluoropropylene (HFP), -A functionalized fluoropolymer B comprising VDF monomer units or VDF and HFP monomer units, having at least one carboxylic acid functional group, It contains.

[0038] Preferably, fluoropolymer A comprises a VDF homopolymer and / or at least one VDF-HFP copolymer having an HFP content of 3% by weight or more, preferably 6% by weight or more. The VDF-HFP copolymer has an HFP content of 55% or less, preferably 50% or less.

[0039] According to one embodiment, fluoropolymer A is a VDF homopolymer or a mixture of VDF homopolymers.

[0040] According to one embodiment, fluoropolymer A consists of a single VDF-HFP copolymer having an HFP content of 3% or more.

[0041] According to one embodiment, fluoropolymer A consists of a mixture of two or more VDF-HFP copolymers, and the HFP content of each copolymer is 3% or more.

[0042] According to one embodiment, fluoropolymer A consists of a mixture of a PVDF homopolymer having an HFP content of 3% or more and a VDF-HFP copolymer.

[0043] According to one embodiment, fluoropolymer B comprises VDF and acrylic acid units or methacrylic acid units.

[0044] According to one embodiment, fluoropolymer B comprises VDF, HFP, and acrylic acid units or methacrylic acid units.

[0045] The polymer binder contains 10% to 99% by weight of polymer A and 1% to 90% by weight of polymer B.

[0046] According to one embodiment, the mixture is i. A weight content of polymer A of 10% to 99%, preferably 10% to 95%, and advantageously 10% to 55%, ii. A weight content of polymer B of 1% or more and 90% or less, preferably more than 5% and less than 90%, and advantageously 45% or more and 90% or less, Includes.

[0047] The active material at the negative electrode is generally lithium metal, graphite, silicon / carbon composite, silicon, or CF with x of 0-1. x Fluorographite of type, and LiTi5O 12 It is a type of titanate.

[0048] The active material in the positive electrode is generally of the LiMO2 type, LiMPO4 type, Li2MPO3F type, Li2MSiO4 type (where M is Co, Ni, Mn, Fe, or a combination thereof), LiMn2O4 type, or S8 type.

[0049] Conductive fillers are selected from carbon black, natural or synthetic graphite, carbon fibers, carbon nanotubes, metal fibers and powders, and conductive metal oxides. They are preferentially selected from carbon black, natural or synthetic graphite, carbon fibers and carbon nanotubes.

[0050] Mixtures of these conductive fillers can also be produced. In particular, the use of carbon nanotubes in combination with other conductive fillers such as carbon black has the advantage of reducing the content of conductive fillers in electrodes and thus reducing the content of polymer binders, due to their lower specific surface area compared to carbon black.

[0051] According to one embodiment, a polymer dispersant different from the polymer binder is used in a mixture with a conductive filler to break down existing aggregates and to help disperse them in the final formulation containing the polymer binder and the active filler. The polymer dispersant is selected from poly(vinylpyrrolidone), poly(phenylacetylene), poly(meth-phenylenevinylidene), polypyrrole, poly(para-phenylenebenzobisoxazole), poly(vinyl alcohol), and mixtures thereof.

[0052] The weight composition of the electrodes is, -50% to 99%, preferably 50% to 99% of the active filler, -25% to 0.05%, preferably 25% to 0.5% conductive filler, -25% to 0.05%, preferably 25% to 0.5% of a polymer binder, -0 to 5% of at least one additive, selected from: plasticizers, ionic liquids, dispersants for conductive fillers, fluidizers for formulations, fibrillating agents such as polytetrafluoroethylene (PTFE), The sum of all these percentages is 100%.

[0053] The present invention also relates to a method for producing Li-ion battery electrodes, comprising the following steps: - A method that enables obtaining an electrode formulation that can be applied to a metal support by a solvent-free method, comprising the steps of mixing an active filler, a polymer binder, a conductive filler, and an optional additive, - A step of depositing the electrode compound onto a metal substrate by a "solvent-free" method to obtain a Li-ion battery electrode, - A step of compacting the electrodes by a thermomechanical treatment such as heat treatment (applying a temperature in the range up to 50°C higher than the melting temperature of the polymer without mechanical pressure) and / or calendering, This includes methods.

[0054] The term "solvent-free" is understood to mean a method that does not require a step to evaporate residual solvent downstream of the deposition step.

[0055] Another embodiment of the method for producing electrodes is as follows: - A method that enables obtaining an electrode formulation in which the constituent components are uniformly mixed, comprising the steps of mixing an active filler, a polymer binder, and a conductive filler, - A step of producing a self-supporting film of the compound by thermomechanical methods such as extrusion, calendering, or thermal compression, - A step of depositing a self-supporting film onto a metal substrate by calendering or thermal compression, - A step of compacting the electrode by heat treatment and / or thermomechanical treatment such as calendering, wherein this final step is optional if the preceding step has already achieved a sufficient level of adhesion and / or porosity. Includes.

[0056] Steps to prepare electrode formulations Polymers A and B are in powder form, with an average particle size of 10 nm to 1 mm, preferably 50 nm to 500 μm, and even more preferably 50 nm to 50 μm.

[0057] Fluoropolymer powders may be obtained by various methods. The powder can be obtained directly by emulsion or suspension synthesis methods, such as spray drying or freeze-drying. The powder may also be obtained by grinding techniques, such as cryogenic grinding. Upon completion of the powder production step, the particle size can be adjusted and optimized by selection or screening methods.

[0058] According to one embodiment, polymers A and B are introduced simultaneously with the active filler and conductive filler at the mixing step.

[0059] According to another embodiment, polymers A and B are mixed together before being mixed with the active filler and the conductive filler. For example, a mixture of polymers A and B can be produced by co-spraying the latex of polymers A and B to obtain a mixture in powder form. The mixture thus obtained can then be mixed with the active filler and the conductive filler.

[0060] Another embodiment of the mixing step consists of two steps. First, polymer A or polymer B, or both, are mixed with the conductive filler by a solvent-free method or co-spraying. This step makes it possible to obtain a homogeneous mixture of the binder and the conductive filler. Next, in the second step, the pre-mixed binder and conductive filler, as well as any unused fluoropolymer, are mixed with the active filler. The active filler is mixed with the homogeneous mixture using a solvent-free mixing method to obtain an electrode formulation.

[0061] Another embodiment of the mixing step consists of proceeding in two stages. First, polymer A or polymer B, or both, are mixed with the active filler by a solvent-free method or by spraying a liquid containing the binder and / or conductive filler onto a fluid powder bed of the active filler. This step makes it possible to obtain a homogeneous mixture of the binder and the active filler. Next, in the second step, the binder, the active filler and any unused fluoropolymer are mixed with the conductive filler.

[0062] Another embodiment of the mixing step consists of two steps. First, the active filler is mixed with the conductive filler by a solvent-free method. Then, in the second step, two polymers A and B are mixed simultaneously with the pre-mixed active filler and conductive filler, or polymers A and B are mixed successively with the pre-mixed active filler and conductive filler.

[0063] Solvent-free mixing methods for various components of electrode formulations include, but are not exhaustive, mixing by stirring, air jet mixing, high shear mixing, mixing by V-mixer, mixing by screw mixer, double cone mixing, drum mixing, conical mixing, double Z-arm mixing, fluidized bed mixing, planetary mixer mixing, mechanofusion mixing, extrusion mixing, calendering mixing, and grinding mixing.

[0064] Other mixing methods include mixing options using a liquid such as water, such as spray drying (co-spraying) or spraying a liquid containing a binder and / or conductive filler onto a fluid powder bed of active filler.

[0065] At the end of this mixing step, the resulting formulation may undergo a final grinding and / or screening and / or selection step to optimize the particle size of the formulation in preparation for the deposition step on the metal substrate.

[0066] Powdered formulations are characterized by their bulk density. Low-density formulations are known in the art to be very limited in their use and applications. The main component contributing to high density is carbon black (0.4 g / cm³). 3 (Bulk density less than 0.1 g / cm³), carbon nanotubes (0.1 g / cm³) 3 (Bulk density less than 0.9 g / cm³), polymer powder (0.9 g / cm³) 3These are carbon-based additives (with a bulk density of less than 100%). Combinations of low-density components to obtain additives that combine polymer binders / electron conductors / other additives are recommended to improve the pre-mixing step downstream of the deposition of the above-mentioned formulations. Such combinations can be made by the following methods: a) After dispersing the components in water or an organic solvent, remove the solvent (e.g., co-spraying, freeze-drying, extrusion / formulation in the presence of solvent or water). b) After dry or "wet" co-grinding using a known grinding method such as a ball mill or bead mill, a drying step is performed as necessary. It can be produced by doing so.

[0067] Such methods are particularly advantageous for significantly increasing bulk density.

[0068] Step of depositing the electrode mixture onto a support. According to one embodiment, at the end of the mixing step, the electrode is manufactured by a solvent-free powder coating method, which involves depositing the compound onto a metal substrate by methods such as pneumatic spraying, electrostatic spraying, immersion in a fluidized powder bed, dusting, electrostatic transfer, deposition by a rotating brush, deposition by a rotating weighing roll, and calendering.

[0069] According to one embodiment, at the end of the mixing step, the electrodes are manufactured by a two-step solvent-free powder coating method. A first step is performed, which consists of producing a self-supporting film from a pre-mixed formulation by a thermomechanical method such as extrusion, calendering, or thermal compression. This self-supporting film is then assembled with a metal substrate by a method combining temperature and pressure, such as calendering or thermal compression.

[0070] The metal supports of the electrodes are generally made of aluminum for the cathode and copper for the anode. The metal supports may be surface-treated and may have a conductive primer with a thickness of 5 μm or more. The supports may also be made of carbon fiber woven or nonwoven fabric.

[0071] Step to compact the electrode mixture. The electrodes are compacted by heat treatment, passing through an oven, under an infrared lamp, passing through a calender with heated rollers, or passing through a press with heated plates. Another alternative consists of a two-step process. First, the electrodes are subjected to heat treatment in an oven, under an infrared lamp, or in contact with a heated plate without pressure. Next, a compression step at ambient temperature or a high temperature is performed using a calender or plate press. This step makes it possible to adjust the porosity of the electrodes and improve their adhesion to the metal substrate.

[0072] The present invention also relates to Li-ion battery electrodes produced by the above method.

[0073] According to one embodiment, the electrode is an anode.

[0074] According to one embodiment, the electrode is a cathode.

[0075] The present invention also provides a lithium-ion secondary battery comprising a negative electrode, a positive electrode, and a separator, wherein at least one electrode is as described above. [Examples]

[0076] The following examples illustrate the scope of the present invention in a non-limiting manner.

[0077] product: PVDF1: Vinylidene fluoride homopolymer, 100s -1 It is also characterized by a melt viscosity of 2500 Pa·s at 230°C.

[0078] PVDF2: A vinylidene fluoride homopolymer having a carboxylic acid functional group with a functional value content of approximately 1% by weight, 100s -1 and a vinylidene fluoride homopolymer characterized by a viscosity of 4000 Pa·s at 230°C.

[0079] Graphite C-NERGY ACTILION GHDR 15-4: Graphite sold by Imerys, characterized by a volume average diameter (Dv50) of 17 μm and a BET specific surface area of 4.1 m 2 / g, graphite.

[0080] Preparation of a mixture of fluoropolymer and graphite: A mixture of a fluoropolymer and graphite composed of 5 wt% PVDF and 95 wt% graphite was produced by a dry method using a Minimix mixer sold by Merris International. A mixture of 50 grams of each formulation was prepared in a 250 ml metal jar by shaking in a blender for 1 minute and 30 seconds at temperature.

[0081] Electrode preparation For the production of electrodes, each fluoropolymer / graphite mixture was manually sprinkled onto the surface of a 18 μm thick copper current collector sold by Hohsen Corp. The basis weight of the produced deposit was approximately 30 mg / cm 2 on the surface of about 5×5 cm 2 . At the end of the deposition, the electrode was densified under a hot plate press by placing silicone paper between the deposited coating and the upper platen of the press. Each coating was pressed at 205 °C, 6 bar for 10 minutes. At the end of this pressing step, the electrode was removed from the press and left to cool to ambient temperature. Then, the silicone paper was removed.

[0082] Electrode evaluation The objective of the manufacturing process is to obtain a coating of approximately 100 microns on a metal support with sufficient cohesiveness to allow electrode operation without cracking or splitting of the coating. Therefore, the first thing to check is the ability of the formulation to form a cohesive and uniform coating on the surface of the current collector. An indicator of this compaction level is the amount of powder / formulation that is transferred to and remains attached to the surface of the silicone paper at the end of the pressing stage. If no fragments of the coating remain attached to the silicone paper, the coating is judged to have good film coating and compaction within the context of the described protocol.

[0083] Another criterion for good mechanical integrity is the level of adhesion achieved on the current collector, and any spontaneous delamination of the coating must be avoided.

[0084] Table 1 shows the composition of the PVDF used in the examples according to the present invention.

[0085] [Table 1]

[0086] Table 2 shows the properties of electrodes with a composition of 95% graphite and 5% PVDF.

[0087] [Table 2]

Claims

1. A Li-ion battery electrode comprising an active filler for the anode or cathode, an electronically conductive filler, and a fluoropolymer binder, The binder consists of a mixture of two fluoropolymers: a non-functional fluoropolymer A and a fluoropolymer B having at least one functional property. The fluoropolymer A is a homopolymer of vinylidene fluoride (VDF), The fluoropolymer B comprises VDF and a monomer unit having at least one carboxylic acid functional group. The fluoropolymers A and B are in powder form and have an average particle size of 50 nm to 50 μm. A Li-ion battery electrode characterized by the following features.

2. The aforementioned binder is - The fluoropolymer A, - A functionalized fluoropolymer B comprising VDF monomer units or VDF and HFP monomer units, having at least one carboxylic acid functional group, The electrode according to claim 1, comprising the same material.

3. The electrode according to claim 1 or 2, wherein the fluoropolymer B comprises VDF units or VDF and HFP units and acrylic acid units or methacrylic acid units.

4. The aforementioned mixture i. The weight content of polymer A, which is between 10% and 99%, ii. The weight content of polymer B, which is between 1% and 90%, The electrode according to any one of claims 1 to 3, including the electrode described in any one of claims 1 to 3.

5. The activated filler for the negative electrode is lithium metal, graphite, silicon / carbon composite material, silicon, CFx-type fluorographite (where x is 0 to 1), and LiTi ５ O １２ An electrode according to any one of claims 1 to 4, selected from type titanates.

6. The active filler is LiMO for the positive electrode ２ type, LiMPO ４ type, Li ２ MPO ３ F type, Li ２ MSiO ４ type (where M is Co, Ni, Mn, Fe or a combination thereof), LiMn ２ O ４ type or S ８ type, and the electrode according to any one of claims 1 to 5, which is selected from active materials

7. The electrode according to any one of claims 1 to 6, wherein the conductive filler is selected from carbon black, natural or synthetic graphite, carbon fibers, carbon nanotubes, metal fibers and powders, conductive metal oxides, or mixtures thereof.

8. The composition by weight is as follows: -50% to 99% active filler, -0.05% to 25% conductive filler, -0.05% to 25% polymer binder, - A compound comprising at least one additive in an amount of -0 to 5%, selected from the list: plasticizers, ionic liquids, dispersants for fillers, fluidizers for formulations, fibrillating agents, The electrode according to any one of claims 1 to 7, wherein the sum of all these percentages is 100%.

9. A method for manufacturing a Li-ion battery electrode according to any one of claims 1 to 8, comprising the following steps: - A method that enables obtaining an electrode formulation that can be applied to a metal support by a solvent-free method, comprising the steps of mixing the active filler, the polymer binder, and the filler, - A step of depositing the electrode compound onto the metal substrate by a solvent-free method to obtain a Li-ion battery electrode, - A step of compacting the electrode by heat treatment and / or thermomechanical treatment, Methods that include...

10. The mixing step, To obtain a dense mixture, the conductive filler and the polymer binder are mixed using a solvent-free method or by co-spraying, and then To obtain the electrode compound, the active filler and the dense mixture are mixed using a solvent-free mixing method. The method according to claim 9, which is carried out in two steps.

11. The method according to claim 9 or 10, wherein the mixing step is performed by stirring, air jet mixing, grinding of the mixture, high shear mixing, mixing with a V-mixer, mixing with a screw mixer, double cone mixing, drum mixing, conical mixing, double Z-arm mixing, mixing in a fluidized bed, planetary mixer, extrusion, calendering, or mechanofusion.

12. The method according to any one of claims 9 to 11, wherein the solvent-free powder coating method is carried out by depositing the compound onto the metal substrate by a method selected from the following: pneumatic spraying, electrostatic spraying, immersion in a fluidized powder bed, dusting, electrostatic transfer, deposition by a rotating brush, deposition by a rotating weighing roll, and calendering.

13. The method according to any one of claims 9 to 11, wherein the solvent-free powder coating method comprises two steps: a first step of producing a self-supporting film from the formulation premixed using a thermomechanical method; and a second step of assembling the self-supporting film with the metal substrate by a method of matching temperature and pressure.

14. The method according to any one of claims 9 to 13, wherein the compaction of the electrode is carried out by heat treatment by passing it through an oven, under an infrared lamp, or through a calender having a heated roll.

15. A secondary lithium-ion battery comprising an anode, a cathode, and a separator, wherein at least one of the electrodes has the composition described in any one of claims 1 to 7.

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