Electrode binder, electrode compound for lithium ion battery, and method for manufacturing electrode

Abstract

The present invention provides a binder for an electrode of a secondary battery, comprising a fluoropolymer A and an acrylic polymer B, wherein the acrylic polymer B is one or more CO2 - Li + The binder comprises monomer units containing functional groups, characterized in that the acrylic polymer B has a degree of lithiation of at least 30%.

Description

[Technical Field]

[0001] The present invention relates generally to the field of electrical energy storage in lithium ion type accumulators. More specifically, the present invention relates to a binder for electrodes. Another subject of the present invention is a method for producing electrodes by using said binder. The present invention also relates to lithium ion batteries manufactured by incorporating said electrodes. [Background technology]

[0002] The basic cell of a lithium-ion or lithium battery comprises an anode (for discharge) and a cathode (for discharge) generally made of a lithium insertion compound of the metal oxide type, such as LiMn2O4, LiCoO2 or LiNiO2, with an electrolyte that conducts lithium ions inserted between them.

[0003] Rechargeable or secondary batteries have advantages over primary (non-rechargeable) batteries because the associated chemical reactions that occur at the battery's positive and negative electrodes are reversible. The electrodes of secondary batteries can be regenerated several times by applying an electrical charge. Many advanced electrode systems have been developed for storing electrical charge. At the same time, significant efforts have been devoted to developing electrolytes that can improve the capacity of electrochemical cells.

[0004] With regard to the electrodes, they generally comprise at least one current collector on which is deposited in the form of a film a composite of a material, termed the active material because it is electrochemically active towards lithium, a polymer acting as a binder, one or more conductive additives, typically carbon black or acetylene black, and optionally a surfactant.

[0005] Binders are classified as inactive components because they do not directly contribute to the cell's capacity. However, their important role in electrode processing and their significant impact on the electrode's electrochemical performance have been widely documented. 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 purpose of using a binder is to form a stable network (cohesion) of the electrode's solid components, i.e., the active material and conductive agent. Furthermore, the binder must ensure intimate contact (adhesion) between the composite electrode and the current collector.

[0006] The current method for manufacturing electrodes for lithium-ion batteries, the "slurry" method, requires the use of a solvent. This method involves creating an ink by mixing the active material, conductive filler, and polymer binder in a solvent. This ink is then deposited onto a current collector and the solvent is evaporated.

[0007] Dry (solvent-free) manufacturing methods are also known. These methods eliminate volatile organic compound emissions and offer the possibility of producing electrodes with greater thicknesses (>120 μm) with higher energy densities in the final energy storage device. U.S. Patent Application Publication No. 2019 / 0305316 discloses dry-processed electrode films containing a particulate non-fibrillating binder with specific particle sizes, as well as a method for obtaining films flexible enough for roll-to-roll processing using a fibrillating binder. However, fibrillating binders require additional shearing in addition to dispersing the components, which consumes a large amount of energy and destroys the active material. U.S. Patent Application Publication No. 2020 / 0313193 also discloses dry-processed electrode films containing an elastic polymer binder, where the dry electrode film is self-supporting and contains only a small amount of polytetrafluoroethylene at most. The document US2020 / 0313193 discloses primarily polyethylene as an elastic polymer binder, which is not electrochemically stable enough for use in both the cathode and anode of a lithium-ion secondary battery.

[0008] There is a need for a binder that provides good electrochemical resistance, contributes to good adhesion to the metal current collector via a solvent-free manufacturing process, and allows for improved electrode conductivity. Furthermore, it is important that the binder has a high affinity for the other components of the solvent-free formulation, as this contributes to intimate cohesion during pressing. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] US Patent Application Publication No. 2019 / 0305316 [Patent Document 2] U.S. Patent Application Publication No. 2020 / 0313193 Summary of the Invention

[0010] According to a first aspect, the present invention provides a binder comprising a fluoropolymer A and an acrylic polymer B, wherein the binder comprises one or more CO2 - Li + The binder comprises monomer units containing functional groups, and the acrylic polymer B has a degree of lithiation of at least 30%.

[0011] The binder according to the present invention is made of two types of polymers, namely fluoropolymers and highly lithiated but CO2 - Li + and an acrylic polymer having a functional group. The binder can improve adhesion to a current collector and electrical conductivity of an electrode containing the binder. The binder can be used to fabricate electrodes by a slurry method or a solventless method.

[0012] According to a preferred embodiment, said acrylic polymer B has a pH of 2.0 to 10.0 measured at ambient temperature.

[0013] According to a preferred embodiment, said acrylic polymer B also comprises at least 5 mol % of monomer units containing -CO2H or carboxylic anhydride functional groups.

[0014] According to a preferred embodiment, the fluoropolymer A is selected from the group consisting of 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); perfluoro(1,3-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole) (PDD); compounds of formula CF2=CFOCF2CF(CF3)OCF2CF2X, where X is SO2F, CO2H, CH2OH, CHOCN, or CHOPO3H; compounds of formula CF2=CFOCF2CF2SO2F;n a compound of formula R 1 The compound CH2OCF=CF2 [wherein R 1 is hydrogen or F(CF2) m and m is 1, 2, 3, or 4; 2 The compound OCF=CH2, wherein R 2 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, or a mixture thereof.

[0015] According to a preferred embodiment, the fluoropolymer A is a polymer comprising monomer units derived from vinylidene fluoride and vinyl fluoride; 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); perfluoro(1,3-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole) (PDD); compounds of formula CF2=CFOCF2CF(CF3)OCF2CF2X, where X is SO2F, CO2H, CH2OH, CHOCN, or CHOPO3H; compounds of formula CF2=CFOCF2CF2SO2F; compounds of formula F(CF2) n a compound of formula R 1 The compound CH2OCF=CF2 [wherein R 1 is hydrogen or F(CF2) m and m is 1, 2, 3, or 4; 2 The compound OCF=CH2, wherein R 2 is F(CF2) pwhere p is 1, 2, 3, or 4; perfluorobutylethylene (PFBE); and optional monomer units of a monomer selected from the group consisting of 3,3,3-trifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-1-propene, or mixtures thereof.

[0016] According to a preferred embodiment, fluoropolymer A is a homopolymer of vinylidene fluoride or a copolymer comprising monomer units derived from vinylidene fluoride and monomer units derived from a monomer selected from the group consisting of trifluoroethylene, chlorotrifluoroethylene, 1,2-difluoroethylene, tetrafluoroethylene, hexafluoropropylene, or mixtures thereof.

[0017] According to a preferred embodiment, said fluoropolymer A comprises monomer units having at least one functional group selected from the group consisting of carboxylic acid, carboxylic anhydride, carboxylic ester, epoxy group, e.g. glycidyl, amide, hydroxyl, carbonyl, mercapto, sulfide, oxazoline, phenol, ester, ether, siloxane, sulfonic acid, sulfuric acid, phosphoric acid and phosphonic acid groups.

[0018] According to a preferred embodiment, the acrylic polymer B has a molecular weight of 3000 g.mol -1 It has a number average molar mass of at least 1.0.

[0019] According to a preferred embodiment, the acrylic polymer B is one or more CO2 - Li + Functional group-containing monomer units include monomer units having one or more carboxylic acid or carboxylic acid anhydride functional groups, and monomer units having one or more carboxylic acid ester functional groups.

[0020] According to a preferred embodiment, the acrylic polymer B has the formula R 1 R 2 C=C(R 3 )((X 1 ) n- CO2 - Li + ) monomer units M0 derived from the monomer of formula (wherein the substituent R 1 , R 2 and R 3 are each independently selected from the group consisting of H, COH and C1-C5 alkyl optionally substituted with COH or CO2R' groups, where R' is C1-C5 alkyl; 1 R 2 C=C(R 3 )((X 2 ) n -COH) monomer units M1, where R 1 , R 2 and R 3 are independently selected from the group consisting of H, COH and C1-C5 alkyl optionally substituted with CO2H or CO2R' groups, where R' is C1-C5 alkyl; X 1 and X 2 are, independently of one another, C1-C optionally bearing one or more hydroxyl groups; 10 alkyl hydrocarbon group; n is 0 or 1], and 4 R 5 C=C(R 6 )C(O)R 7 Monomer units M2 derived from the monomer of formula (wherein the substituent R 4 , R 5 and R 6 are each independently selected from the group consisting of H, COH and C1-C5 alkyl optionally substituted with CO2H or CO2R' groups, where R' is C1-C5 alkyl; R 7 is selected from the group consisting of -NHC(CH3)2CH2C(O)CH3 or -OR', where R' is a C1-C2 alkyl group optionally substituted with one or more -OH groups. 18 alkyl, or a 5- or 6-membered heterocycle containing at least one nitrogen atom in its cyclic chain.

[0021] According to a preferred embodiment, said acrylic polymer B in solution in water has a pH, measured in water at ambient temperature, of 2.0 to 10.0.

[0022] According to a preferred embodiment, the weight content of the acrylic polymer B relative to the fluoropolymer A is 1% to 70%.

[0023] According to a preferred embodiment, said acrylic polymer B also contains divalent cations.

[0024] According to another aspect, the present invention provides an electrode comprising a binder according to the present invention, an active material, and optionally a conductive agent.

[0025] According to a preferred embodiment, the electrode has the following composition by weight: a. 50% to 99.9%, preferably 50% to 99%, of an active material; b. 25% to 0%, preferably 25% to 0.5%, of a conductive agent; c. 25% to 0.05%, preferably 25% to 0.5%, of a binder according to the present invention; d. 0% to 5% of at least one additive selected from the group consisting of plasticizers, ionic liquids, dispersants for conductive additives, and flow aids; All these percentages add up to 100%.

[0026] According to a preferred embodiment, the conductive agent is composed of one or more materials selected from the group consisting of carbon black such as acetylene black or ketjen black; carbon fibers such as carbon nanotubes, carbon nanofibers, or vapor-grown carbon fibers; and metal powders such as SUS powder and aluminum powder.

[0027] According to a preferred embodiment, in the positive electrode, the active material is LiCoO2, Li(Ni, Co, Al)O2, Li (1+x) Ni a Mn b Co c(x is a real number of 0 or more, a = 0.8, 0.6, 0.5 or 1 / 3, b = 0.1, 0.2, 0.3 or 1 / 3, c = 0.1, 0.2 or 1 / 3), LiNiO2, LiMn2O4, LiCoMnO4, Li3NiMn3O3, Li3Fe2(PO4)3, Li3V2(PO4)3, Li 1+x Mn 2-x-y M y LiMn spinel substituted with different elements having a composition represented by O4 [M represents at least one metal selected from Al, Mg, Co, Fe, Ni, and Zn, and x and y independently represent real numbers from 0 to 2], lithium titanate Li x TiO y [x and y independently represent real numbers from 0 to 2], and a lithium metal phosphate having a composition represented by LiMPO4 [M represents Fe, Mn, Co or Ni] is selected from the group consisting of.

[0028] According to a preferred embodiment, in the negative electrode, the active material is selected from the group consisting of a lithium alloy, lithium metal, metal oxide, a carbon material such as graphite or hard carbon, silicon, silicon alloy and Li4Ti5O 12 selected from the group consisting of.

[0029] According to another aspect, the present invention is a method for producing a dry-coated electrode, comprising: mixing a binder, an active material and optionally a conductive agent according to the present invention in powder form; depositing the mixture obtained in the previous step on a current collector to obtain an electrode; when Tg>Tm, at a temperature T1 between Tm - 50°C < T1 < Tg + 50°C, or when Tm>Tg, at a temperature T1 between Tg - 50°C < T1 < Tm + 50°C, by a thermomechanical treatment step of consolidating the electrode, where Tm is the melting point of the fluoropolymer A and Tg is the glass transition temperature of the acrylic polymer B.

[0030] According to another aspect, the present invention is a method for producing an electrode by a solvent route, comprising: mixing said binder according to the present invention, an active material and optionally a conductive agent in the presence of a solvent; depositing the mixture obtained in the previous step on a current collector to obtain an electrode; drying the electrode.

[0031] According to a preferred embodiment, the present invention preferably provides a lithium-ion battery comprising a positive electrode, a negative electrode and a separator, at least one electrode being an electrode according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0032] According to a first aspect, there is provided a binder for an electrode. Preferably, the binder comprises a mixture of at least two polymers. Thus, the binder comprises a fluoropolymer A and an acrylic polymer B.

[0033] Preferably, the binder is in powder form. The use of a binder in powder form allows for the use of solvent-free binders from the mixing stage of the components to the deposition and solidification stage on the current collector. Furthermore, the use of a binder in powder form for the production of the electrode makes it possible to avoid resorting to a grinding or dispersion step after mixing with the active material and the conductive agent. In particular, the powder has a particle size distribution with a D90 of 750 μm or less, advantageously 700 μm or less, preferably 650 μm or less, more preferentially 600 μm or less, in particular 550 μm or less, and more particularly 500 μm or less. D90 is the particle size at the 90th percentile (by volume) of the cumulative particle size distribution. This parameter is determined by laser particle size analysis. A particle size analyzer of the Malvern Insitec System type is used for the measurement. This is performed in a dry manner by laser diffraction on the powder with a focal length of 100 mm. Advantageously, said powder has a particle size distribution with a D90 of less than or equal to 450 μm, preferably less than or equal to 400 μm, more preferentially less than or equal to 350 μm, in particular less than or equal to 300 μm, more particularly less than or equal to 250 μm, preferably less than or equal to 200 μm, advantageously preferably less than or equal to 150 μm, preferentially preferably less than or equal to 100 μm and particularly preferably less than or equal to 50 μm.

[0034] According to a preferred embodiment, said fluoropolymer A contains in its chain a vinyl group that can be ring-opened to polymerize and contains at least one monomer chosen from compounds containing at least one fluorine atom, a fluoroalkyl group or a fluoroalkoxy group directly bonded to this vinyl group.

[0035] Preferably, the fluoropolymer A is selected from the group consisting of 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); perfluoro(1,3-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole) (PDD); compounds of formula CF2=CFOCF2CF(CF3)OCF2CF2X, where X is SO2F, CO2H, CH2OH, CHOCN, or CHOPO3H; compounds of formula CF2=CFOCF2CF2SO2F; n a compound of formula R 1 The compound CH2OCF=CF2 [wherein R 1 is hydrogen or F(CF2) m and m is 1, 2, 3, or 4; 2 The compound OCF=CH2, wherein R 2 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, or a mixture thereof.

[0036] In particular, said fluoropolymer A comprises at least monomer units derived from vinylidene fluoride. Fluoropolymer A can be a homopolymer or a copolymer. The copolymer can also comprise non-fluorinated monomers.

[0037] According to one embodiment, fluoropolymer A is a vinylidene fluoride homopolymer.

[0038] According to another embodiment, the fluoropolymer A is a polymer comprising units deriving from vinylidene fluoride, preferably chosen from polyvinylidene fluoride homopolymers and copolymers comprising vinylidene fluoride units and units deriving from at least one other comonomer copolymerizable with vinylidene fluoride.

[0039] Thus, the fluoropolymer A may comprise monomer units derived from vinylidene fluoride and vinyl fluoride; 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); perfluoro(1,3-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole) (PDD); compounds of the formula CF2=CFOCF2CF(CF3)OCF2CF2X, where X is SO2F, CO2H, CH2OH, CHOCN, or CHOPO3H; compounds of the formula CF2=CFOCF2CF2SO2F; compounds of the formula F(CF2) n a compound of formula R 1 The compound CH2OCF=CF2 [wherein R 1 is hydrogen or F(CF2) m and m is 1, 2, 3, or 4; 2 The compound OCF=CH2, wherein R 2 is F(CF2) p where p is 1, 2, 3, or 4; perfluorobutylethylene (PFBE); and monomer units derived from a monomer selected from the group consisting of 3,3,3-trifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-1-propene, or a mixture thereof.

[0040] According to a preferred embodiment, the fluoropolymer A is a copolymer of vinylidene fluoride (VDF) units and vinyl fluoride; trifluoroethylene; chlorotrifluoroethylene; 1,2-difluoroethylene; tetrafluoroethylene; hexafluoropropylene; perfluoro(alkyl vinyl) ethers such as perfluoro(methyl vinyl) ether, perfluoro(ethyl vinyl) ether, or perfluoro(propyl vinyl) ether; perfluoro(1,3-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole); compounds of the formula CF2=CFOCF2CF(CF3)OCF2CF2X, where X is SO2F, CO2H, CH2OH, CH2OCN, or CHOPO3H; compounds of the formula CF2=CFOCF2CF2SO2F; compounds of the formula F(CF2) n a compound of formula R ’ The compound CH2OCF=CF2 [wherein R ’ is hydrogen or F(CF2) z and z is 1, 2, 3, or 4; compounds of formula R"OCF=CH2, where R" is F(CF2) z and z is 1, 2, 3, or 4; perfluorobutylethylene; and units derived from one or more monomers selected from the group consisting of 3,3,3-trifluoropropene or 2-trifluoromethyl-3,3,3-trifluoro-1-propene, or mixtures thereof.

[0041] Preferably, fluoropolymer A is a copolymer comprising monomer units derived from vinylidene fluoride and monomer units derived from a monomer selected from the group consisting of trifluoroethylene, chlorotrifluoroethylene, 1,2-difluoroethylene, tetrafluoroethylene and hexafluoropropylene, or mixtures thereof. In fluoropolymer A, the weight content of vinylidene fluoride units is at least 50%, preferably at least 60%, more preferably more than 70% and advantageously more than 80%.

[0042] According to a particular embodiment, the fluoropolymer A is fully or partially functionalized to improve adhesion to metals. Thus, said fluoropolymer A can comprise monomer units having at least one functional group selected from the group consisting of carboxylic acid, carboxylic anhydride, carboxylic ester, epoxy groups, such as glycidyl, amide, hydroxyl, carbonyl, mercapto, sulfide, oxazoline, phenol, ester, ether, siloxane, sulfonic acid, sulfuric acid, phosphoric acid and phosphonic acid groups, preferably at least one carboxylic acid or hydroxyl functional group.

[0043] The functional groups are introduced by chemical reaction, which may be grafting or copolymerization, of a fluorinated monomer with a monomer having at least one said functional group and a vinyl function copolymerizable with the fluorinated monomer, according to techniques well known to those skilled in the art.

[0044] According to one embodiment, the functional group comprises 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, hydroxyethylhexyl (meth)acrylate and acryloyloxypropyl succinate.

[0045] According to one embodiment, the unit having a carboxylic acid functionality further comprises a heteroatom selected from oxygen, sulfur, nitrogen and phosphorus.

[0046] According to one embodiment, the functionality is introduced via a transfer agent used during the synthesis method. The transfer agent is a polymer having a molar mass of 20,000 g / mol or less and having functional groups selected from the following group: carboxylic acid, carboxylic anhydride, carboxylic ester, epoxy (such as glycidyl), amide, hydroxyl, carbonyl, mercapto, sulfide, oxazoline, phenol, ester, ether, siloxane, sulfonic acid, sulfuric acid, phosphoric acid, or phosphonic acid groups. Acrylic acid oligomers are an example of this type of transfer agent. According to a preferred embodiment, the transfer agent is an acrylic acid oligomer having a molar mass of 20,000 g / mol or less. The molar mass of the transfer agent is determined according to the method described below for acrylic polymer B.

[0047] The content of functional groups in PVDF is 0.01 mol % or more, preferably 0.1 mol % or more, and 15 mol % or less, preferably 10 mol % or less.

[0048] Preferably, the PVDF is of high molecular weight. As used herein, the term "high molecular weight" refers to a PVDF that is resistant to 232°C and 100 seconds. -1 This refers to PVDF having a melt viscosity of more than 100 Pa.s, preferably more than 500 Pa.s, and more preferably more than 1000 Pa.s, as measured by the ASTM D-3835 method.

[0049] The PVDF homopolymers and VDF copolymers used in the present invention can be obtained by known polymerization methods such as emulsion polymerization or suspension polymerization.

[0050] According to one embodiment, they are made by an emulsion polymerization process in the absence of fluorinated surfactants.

[0051] Polymerization of PVDF generally results in a latex having a solids content of 10% to 60%, preferably 10% to 50%, by weight, and a weight-average particle size of less than 1 micrometer, preferably less than 1000 nm, preferably less than 800 nm, and more preferably less than 600 nm. The weight-average particle size is generally at least 20 nm, preferably at least 50 nm, and advantageously the average size is in the range of 100 to 400 nm. The polymer particles can form aggregates, the weight-average size of which is 1 to 30 micrometers, preferably 2 to 10 micrometers. The aggregates can be dispersed into discrete particles during formulation and application to a substrate.

[0052] According to a particular embodiment, the PVDF homopolymer and VDF copolymer are composed of bio-based VDF. The term "bio-based" means "obtained from biomass." This makes it possible to improve the ecological footprint of the polymer. Bio-based VDF is produced in accordance with the standard NF EN 16640. 14 It can be characterized by a content of renewable carbon, i.e. of at least 1 atomic % of naturally occurring carbon derived from biological materials or biomass, as determined by the C content. The term "renewable carbon" indicates that the carbon is of natural origin and derived from biological materials (or biomass), as shown below. According to certain embodiments, the biocarbon content of the VDF can be greater than 5%, preferably greater than 10%, preferably greater than 25%, preferably greater than 33%, preferably greater than 50%, preferably greater than 66%, preferably greater than 75%, preferably greater than 90%, preferably greater than 95%, preferably greater than 98%, preferably greater than 99%, advantageously equal to 100%.

[0053] As mentioned above, the binder also includes an acrylic polymer B.

[0054] The acrylic polymer B may be one or more CO2 - Li +Preferably, the acrylic polymer B has a degree of lithiation of at least 30%. The degree of lithiation is determined by the ratio of -CO2 in the acrylic polymer B to the monomer unit containing the functional group. - Li + The moles of the group, the carboxylic acid group and -CO2 - Li + The moles of carboxylic acid groups can be determined by conventional analytical techniques (e.g., NMR). - Li + The number of moles of groups is estimated from the number of moles of carboxylic acid groups before and after the lithiation step (100% yield). In particular, the acrylic polymer has a degree of lithiation of at least 35%, advantageously at least 40%, preferably at least 45%, more preferentially at least 50%, in particular at least 55%. The acrylic polymer B having a degree of lithiation expressed herein makes it possible to improve the electrical conductivity of electrodes containing the binder.

[0055] Preferably, said acrylic polymer B in solution in water has a pH, measured at ambient temperature, of between 2.0 and 10.0, advantageously between 2.5 and 9.0, preferably between 3.0 and 8.0.

[0056] Preferably, the acrylic polymer B comprises at least 5 mol %, advantageously at least 10 mol %, preferably at least 15 mol %, in particular at least 20 mol % of monomer units containing -COH or carboxylic anhydride functional groups. The presence of carboxylic acid or carboxylic anhydride groups also improves adhesion to the current collector.

[0057] According to a preferred embodiment, the acrylic polymer B has a molecular weight of 3000 g.mol -1 More than 10,000 g.mol -1 More than 50,000 g.mol, preferably -1 or more preferably 100 000 g.mol -1 Above, especially 150,000 g.mol -1The polymer has a number-average molar mass of 0.05 mol / L or more. The molecular weight or molar mass is determined by size exclusion chromatography (SEC). A test sample of the polymer solution, equivalent to 90 mg of dry substance, is placed in a 10 mL flask. A mobile phase supplemented with 0.04% dimethylformamide (DMF) is added to a total weight of 10 g. The mobile phase has the following composition: NaHCO3: 0.05 mol / L, NaNO3: 0.1 mol / L, triethanolamine: 0.02 mol / L, and NaN3: 0.03 wt%. The SEC line consists of a Waters 510 type isocratic pump with a flow rate adjusted to 0.8 ml / min, a Waters 717+ autosampler, an oven containing a Waters Ultrahydrogel Guard Column type precolumn with a length of 6 cm and an internal diameter of 40 mm, followed by a Waters Ultrahydrogel type linear column with a length of 30 cm and an internal diameter of 7.8 mm. Detection is provided by a Waters 410 RI type differential refractometer. The oven is set to a temperature of 60°C and the refractometer is set to a temperature of 45°C. The SEC device is set to a temperature of 1000 g / mol to 1 x 10 6 It is calibrated with a series of sodium polyacrylate standards supplied by Polymer Standards Service with peak top molecular weights in g / mol and polydispersity indices between 1.4 and 1.7. The calibration curve is of linear type and takes into account the correction obtained with the flow marker: dimethylformamide (DMF).

[0058] Preferably, the acrylic polymer B contains one or more CO2 - Li + Functional group-containing monomer units include monomer units having one or more carboxylic acid or carboxylic acid anhydride functional groups, and monomer units having one or more carboxylic acid ester functional groups.

[0059] The use of an acrylic polymer B having such functional groups according to the invention makes it possible to improve the adhesion of the current collector onto which the binder according to the invention is deposited and the conductivity of the electrode containing the binder according to the invention.

[0060] According to a preferred embodiment, the acrylic polymer B is formula R 1 R 2 C=C(R 3 )((X 1 ) n -CO2 - Li + ) monomer units M0 derived from the monomer of formula (wherein the substituent R 1 , R 2 and R 3 are each independently selected from the group consisting of H, CO2H and C1-C5 alkyl optionally substituted with CO2H or CO2R' groups, where R' is C1-C5 alkyl; formula R 1 R 2 C=C(R 3 )((X 2 ) n -COH) monomer units M1, where R 1 , R 2 and R 3 are independently selected from the group consisting of H, COH and C1-C5 alkyl optionally substituted with CO2H or CO2R' groups, where R' is C1-C5 alkyl; X 1 and X 2 are, independently of one another, C1-C optionally bearing one or more hydroxyl groups; 10 an alkyl hydrocarbon group; n is 0 or 1; and formula R 4 R 5 C=C(R 6 )C(O)R 7 Optional monomeric units M2 derived from monomers of formula (I) 4 , R 5 and R 6 are each independently selected from the group consisting of H, COH and C1-C5 alkyl optionally substituted with COH or COR' groups, where R' is C1-C5 alkyl, and R 7 is selected from the group consisting of -NHC(CH3)2CH2C(O)CH3 or -OR', where R' is a C1-C2 alkyl group optionally substituted with one or more -OH groups. 18alkyl or a 5- or 6-membered heterocycle containing at least one nitrogen atom in its cyclic chain.

[0061] The presence of the combined functionality of lithium carboxylate, carboxylic acid and carboxylic acid ester not only improves the adhesion to the current collector and the conductivity of the electrode, but also makes it possible to obtain polymer particles that are deformable and compatible with fluoropolymer A.

[0062] In particular, the monomer unit M0 has the formula R 1 R 2 C=C(R 3 )((X 1 ) n -CO2 - Li + ) [wherein, substituent R 1 and R 2 are, independently of each other, H or COH; R 3 is H, CH2CO2H or CH3; X 1 is a C1-C5 alkyl hydrocarbon group optionally bearing one or more hydroxyl groups; n is 0 or 1. More particularly, the monomer unit M0 is derived from a monomer of formula R 1 R 2 C=C(R 3 )((X 1 ) n -CO2 - Li + ) [wherein, substituent R 1 and R 2 are, independently of each other, H or COH; R 3 is H, CH2CO2H or CH3; X 1 is a C1-C3 alkyl hydrocarbon group optionally bearing one or more hydroxyl groups; n is 0 or 1. Advantageously, the monomer unit M0 is derived from a monomer of formula R 1 R 2 C=C(R 3 )(CO2 - Li + ) [wherein, substituent R 1 and R 2 are, independently of each other, H or COH; R 3is H, CH2CO2H or CH3].

[0063] In particular, the monomer unit M1 has the formula R 1 R 2 C=C(R 3 )((X 2 ) n -CO2H) "In the formula, substituent R 1 and R 2 are, independently of each other, H or COH; R 3 is H, CH2CO2H or CH3; X 2 is a C1-C5 alkyl hydrocarbon group optionally bearing one or more hydroxyl groups; n is 0 or 1. More particularly, the monomer unit M1 is derived from a monomer of formula R 1 R 2 C=C(R 3 )((X 2 ) n -CO2H)[wherein, substituent R 1 and R 2 are, independently of each other, H or COH; R 3 is H, CH2CO2H or CH3; X 2 is a C1-C3 alkyl hydrocarbon group optionally bearing one or more hydroxyl groups; n is 0 or 1. Preferably, the monomer unit M1 is derived from a monomer of formula R 1 R 2 C=C(R 3 )(CO2H)[wherein the substituent R 1 and R 2 are, independently of each other, H or COH; R 3 is H, CH2CO2H or CH3. According to a preferred embodiment, the acrylic polymer B comprises at least 5 mol %, advantageously at least 10 mol %, preferably at least 15 mol %, in particular at least 20 mol %, more particularly at least 30 mol %, preferably at least 40 mol % and particularly preferably at least 50 mol % of monomer units M1.

[0064] Preferably, the acrylic polymer B is of formula R 4R 5 C=C(R 6 )C(O)R 7 and a substituent R 4 , R 5 and R 6 are each independently selected from the group consisting of H, COH and C1-C5 alkyl optionally substituted with COH or COR' groups, where R' is C1-C5 alkyl, and R 7 is selected from the group consisting of -NHC(CH3)2CH2C(O)CH3 or -OR', where R' is a C1-C2 alkyl group optionally substituted with one or more -OH groups. 18 The heterocycle may be selected from the group consisting of alkyl or 5- or 10-membered heterocycles containing at least one nitrogen atom in its cyclic chain. The heterocycle may be saturated, unsaturated, or aromatic. The heterocycle may be monocyclic or bicyclic. The heterocycle may be pyrrole, pyrrolidine, pyridine, piperidine, pyrimidine, pyrazine, 1,4-dihydropyridine, indole, oxindole, isatin, quinoline, isoquinoline, quinazoline, imidazoline, pyrazolidine, 2-pyrrolidone, δ-lactam, succinimide, 2-imidazolidinone, or 4-imidazolidinone ring. The heterocycle may be substituted with one or more C1-C5 alkyl groups. As described above, the C1-C5 alkyl groups may be substituted with one or more C1-C5 alkyl groups. 18 The alkyl is optionally substituted on said heterocycle. The latter can be attached to the alkyl chain via a nitrogen atom or any other atom forming the heterocycle. Preferably, the heterocycle is 2-pyrrolidone, δ-lactam, succinimide, 2-imidazolidinone or 4-imidazolidinone. In the present patent application, the term "alkyl" includes linear and branched alkyl. According to a preferred embodiment, the substituent R' is selected from the group consisting of methyl, ethyl, propyl, n-butyl, isobutyl, t-butyl, n-dodecyl, amyl, isoamyl, hexyl, 2-ethylhexyl, lauryl, n-octyl, hydroxybutyl, hydroxypropyl, ethyl substituted with a ureido group, and hydroxyethyl. In particular, said acrylic polymer B comprises a substituent R 4 and R 5 is H and R 6is H or CH3, and R 7 is —OR′, and R′ is selected from the group consisting of methyl, ethyl, propyl, n-butyl, isobutyl, t-butyl, n-dodecyl, amyl, isoamyl, hexyl, 2-ethylhexyl, lauryl, n-octyl, hydroxypropyl, hydroxybutyl, 2-pyrrolidone, δ-lactam, succinimide, 2-imidazolidinone, 4-imidazolidinone, ethyl substituted with a ureido group, and hydroxyethyl; 4 R 5 C=C(R 6 )C(O)R 7 Thus, the acrylic polymer B contains monomer units M2 derived from methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-dodecyl acrylate, amyl acrylate, isoamyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, diacetone acrylamide, lauryl acrylate, n-octyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, methylacrylic acid, methyl methacrylate, or ureido methacrylate. The term "acrylate" in this example includes acrylate and methacrylate.

[0065] According to a preferred embodiment, said acrylic polymer B comprises at least 1 mol %, advantageously at least 5 mol %, preferably at least 10 mol %, in particular at least 25 mol %, more particularly at least 20 mol % of monomer units M2.

[0066] Optionally, the acrylic polymer B also has the formula R 1 R 2 C=C(R 3 )((X 2 ) n -CO2H), R 1 R 2 C=C(R 3 )((X 1 ) n -CO2 - Li+ ) and monomers of formula R as defined above 4 R 5 C=C(R 6 )C(O)R 7 Advantageously, the monomeric unit M3 derived from an unsaturated monomer copolymerizable with a monomer of formula (R 8 )(R 9 )C=C(R 10 )(R 11 -R 12 ), (R 8 )(R 9 )C=C(R 10 )(P(O)(OR 13 )(OR 14 )), (R 8 )(R 9 )C=C(R 10 )(C(O)NH(R 17 -R 18 )) or (R 8 )(R 9 )C=C(R 10 )(C(O)N(R 15 -R 16 )(R 17 -R 18 ))[wherein, substituent R 8 , R 9 and R 10 are each independently selected from the group consisting of H and C1-C5 alkyl; R 11 , R 15 and R 17 are independent of each other, C1-C 18 Alkyl, C6-C 18 Aryl, C4-C 18 Cycloalkyl, C1-C 18 Fluoroalkyl, C6-C 18 Fluoroaryl, C4-C 18 R is selected from the group consisting of fluorocycloalkyl, oligomers of propylene glycol, oligomers of ethylene glycol, oligomers of hexafluoropropylene oxide, and oligomers of tetrafluoroethylene oxide; 12 , R 16 and R 18are, independently of each other, CO2H, COOM, OH, CONH2, CON(R 19 )2, SO3H, SO3M, and R 19 is C1-C5 alkyl and M is NH4 + , N.R. 19 4 + , Na + or K + and;R 13 and R 14 are, independently of each other, H, C1-C 18 Alkyl, C6-C 18 Aryl, C4-C 18 Cycloalkyl, C1-C 18 Fluoroalkyl, C6-C 18 Fluoroaryl, C4-C 18 Fluorocycloalkyl, propylene glycol oligomer, ethylene glycol oligomer, hexafluoropropylene oxide oligomer, tetrafluoroethylene oxide oligomer, alkali cation, NH4 + and NR 19 4 +Preferably, the monomer unit M3 is selected from the group consisting of fumaric acid, crotonic acid, itaconic acid, vinyl acetate, vinyl neodecanoate, acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, N-alkylacrylamide, N-alkylmethacrylamide, N,N-dialkylacrylamide, N,N-dialkylmethacrylamide, diacetoneacrylamide, 2-hydroxyethyl acrylate, N-dialkylaminoethyl acrylate, glycidyl acrylate, n- The copolymer may be derived from a monomer selected from the group consisting of dodecyl acrylate, fluoroalkyl acrylate, dialkylaminoethyl methacrylate, fluoroalkyl methacrylate, 2-hydroxyethyl methacrylate, n-octyl methacrylate, t-butyl methacrylate, glycidyl methacrylate, ethylene glycol dimethacrylate, maleic anhydride, and alkenyl glycidyl ether compounds such as allyl glycidyl ether, 1,3-butadiene, isoprene, divinylbenzene, acrylonitrile, and methacrylonitrile. Among these, itaconic acid, fumaric acid, N-methylol acrylamide, N-methylol methacrylamide, diacetone acrylamide, acrylamido-2-methylpropanesulfonic acid, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, allyl glycidyl ether, 1,3-butadiene, and acrylonitrile are preferred. These compounds may be used alone or in combination. Preferably, the acrylic polymer B comprises less than 30 mol %, advantageously less than 20 mol %, of monomer units M3.

[0067] The acrylic polymer B used in the present invention can be obtained by polymerizing the monomers by a known polymerization method such as emulsion polymerization or suspension polymerization. The acrylic polymer B thus obtained is then contacted with a solution or dispersion of lithium hydroxide to obtain a monomer containing -CO2Li groups. The concentration of LiOH is adjusted to the desired content of -CO2Li groups.

[0068] According to a preferred embodiment, the acrylic polymer B also contains a divalent cation. The divalent cation is Ca 2+ , Mg 2+ , Ba 2+ , Cu 2+ or Zn 2+ or a mixture thereof. Preferably, the divalent cation is Ca 2+ or Zn 2+ or a mixture thereof. The divalent cation is preferably a carboxylate group CO2 of the acrylic polymer B. - The divalent cation can be added in the form of a solution or dispersion of the hydroxide of the cation. The solution or dispersion is added to the acrylic polymer B simultaneously with or separately from the LiOH solution or dispersion described above. In this case, the degree of lithiation is determined by the following formula: (-CO2 - Li + and [CO2 - ]2X 2+ (the number of moles of carboxylic acid groups in the acrylic polymer B and -CO2 - Li + and [CO2 - ]2X 2+ where X is a divalent cation. The presence of this divalent cation makes it possible to improve the efficiency of a battery containing the acrylic polymer B. The molar ratio of the divalent cation to lithium is 0.01 to 1, preferably 0.05 to 0.5.

[0069] According to a preferred embodiment, the weight content of acrylic polymer B relative to fluoropolymer A is between 1% and 70%, advantageously between 2% and 60%, preferably between 3% and 50%, more preferentially between 4% and 40%, in particular between 5% and 30%.

[0070] According to another aspect, the present invention provides a method for making the binder according to the invention. According to a preferred embodiment, the method also comprises the steps of: mixing the fluoropolymer A in latex form with the acrylic polymer B in the form of an aqueous solution or in the form of a latex; Optionally, drying the mixture obtained in the previous step, preferably by spray drying or co-spray drying; Optionally, grinding the dry mixture obtained in the previous step.

[0071] The drying step can be carried out by spray drying or co-spray drying, preferably at temperatures between 100°C and 220°C. Powders can also be obtained by grinding techniques such as cryogenic grinding, in which the mixture is brought to a temperature below ambient temperature, for example with liquid nitrogen, before grinding. At the end of the powder production step, i.e. after the drying step, the particle size can be adjusted and optimized by selection or screening methods and / or grinding. The drying and grinding steps are carried out once the binder is in powder form.

[0072] Alternatively, the fluoropolymer A and the acrylic polymer B may be mixed in the presence of an organic solvent or a mixture of water and an organic solvent.

[0073] According to another aspect, the present invention provides an electrode comprising the binder according to the present invention, a conductive agent, and an active material.

[0074] In a preferred embodiment, the electrode has the following composition by weight: a. 50% to 99.9%, preferably 50% to 99%, of an active material; b. 25% to 0%, preferably 25% to 0.5%, of a conductive agent; c. 25% to 0.05%, preferably 25% to 0.5%, of a binder according to the present invention; d. 0% to 5% of at least one additive selected from the group consisting of plasticizers, ionic liquids, dispersants for conductive additives, and flow aids.

[0075] All these percentages add up to 100%.

[0076] The conductive agent in the electrode is composed of one or more materials capable of improving electrical conductivity. Some examples include carbon black such as acetylene black or ketjen black; carbon fibers such as carbon nanotubes, carbon nanofibers, or vapor-grown carbon fibers; and metal powders such as SUS powder and aluminum powder.

[0077] The active material is a material that can store and release lithium ions.

[0078] In a preferred embodiment, the electrode is a negative electrode. In particular, in a negative electrode, the active material is selected from the group consisting of lithium alloys, lithium metal, metal oxides, carbon materials such as graphite or hard carbon, silicon, silicon alloys, and Li4Ti5O 12 The form of the negative electrode active material is not particularly limited, but is preferably in the form of particles.

[0079] In another preferred embodiment, the electrode is a positive electrode. Preferably, in the positive electrode, the active material is LiCoO2, Li(Ni, Co, Al)O2, Li (1+x) Ni a Mn b Co c (x is a real number greater than or equal to 0, a=0.8, 0.6, 0.5 or 1 / 3, b=0.1, 0.2, 0.3 or 1 / 3, c=0.1, 0.2 or 1 / 3), LiNiO2, LiMn2O4, LiCoMnO4, Li3NiMn3O3, Li3Fe2(PO4)3, Li3V2(PO4)3, Li 1+x Mn 2-x-y M y LiMn spinel substituted with different elements having a composition represented by O4 [M represents at least one metal selected from Al, Mg, Co, Fe, Ni, and Zn, and x and y independently represent real numbers from 0 to 2], lithium titanate Li x TiO y [x and y independently represent real numbers of 0 to 2], and lithium metal phosphate having a composition represented by LiMPO4 [M represents Fe, Mn, Co, or Ni].

[0080] In addition, the surfaces of each of the above-described materials can be coated. The coating material is not particularly limited as long as it has conductivity with respect to lithium ions and can be maintained in the form of a coating layer on the surface of the active material. Examples of the coating material include LiNbO3, Li4Ti5O 12 and include Li3PO4.

[0081] The form of the positive electrode active material is not particularly limited, but is preferably particulate.

[0082] According to another aspect of the present invention, a method for producing a dry-coated electrode is provided.

[0083] The method for producing a dry-coated electrode includes the following steps: A step of mixing an active material, a binder according to the present invention in powder form as described above, and a conductive agent, using a method for providing an electrode composition that can be applied to a metal substrate by a "solvent-free" method, <​​​​​​​​​​A "solvent-free" method is one that does not require a step to evaporate residual solvent after the deposition step.

[0086] The thermomechanical treatment can be carried out, for example, by means of a calendering device with rolls which can be heated, or a plate press which can also be heated.

[0087] Without being exhaustive, methods for solvent-free mixing of the various components of the electrode formulation prior to the deposition stage on a collector may include mixing by stirring, air jet mixing, 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, mixing in a planetary mixer, mixing by mechanofusion, mixing by extrusion, mixing by calendering, mixing by grinding.

[0088] According to one embodiment, after the powder mixing step, the electrode is manufactured by solventless spraying, deposition of the formulation on a metal substrate, pneumatic spraying, electrostatic spraying, immersion in a fluidized powder bed, sprinkling, electrostatic screen printing, deposition by rotating brush, deposition by rotating metering roll, calendering.

[0089] According to one embodiment, the consolidation of the electrode after the method of deposition onto the metal substrate by solvent-free spraying (by pneumatic spraying method, by electrostatic spraying, by immersion in a fluidized powder bed, by sprinkling, by electrostatic screen printing, by deposition by rotating brush, by deposition by rotating metering roll) is carried out by a calendering method, which consists in applying pressure to the electrode using two optionally heated rolls.

[0090] According to one embodiment, after the powder mixing step, the electrode is manufactured by a two-step solventless method. The first step consists of producing a free-standing film from the premixed formulation by a thermomechanical method such as extrusion, calendering, or thermocompression. In the second step, the free-standing film is laminated to a metal substrate by a combined temperature and pressure method such as calendering or thermocompression.

[0091] According to one embodiment, after the powder mixing step, the electrode is produced by a solventless method using a calendering method, which allows the steps of film formation and transfer of the coating onto the current collector to be carried out in a single step, i.e., without the step of producing a free-standing film. To do this, the calender used has several rolls (at least three). The powder obtained after the mixing step is generally heated to shear the powder and introduced between the first two rolls, which have different rotation speeds. The coating formed and remaining attached to the fastest roll is then directly laminated to the current collector with the third roll. The electrode thus obtained can then be passed through the calender again to adjust its porosity or thickness, if necessary.

[0092] The weight ratio of the conductive agent to the active material is preferably 0% to 10%, and more preferably 0% to 7%.

[0093] The weight ratio of the binder to the active material is preferably 0.1% to 10%, and more preferably 0.5% to 7%.

[0094] According to one embodiment, all of the components of the electrode are mixed together at once according to conventional methods to produce the electrode formulation.

[0095] In one embodiment, the electrode formulation is applied to a substrate by electrostatic screen printing. Some examples of substrates are current collectors such as metal sheets or meshes, polymer films, or layers of solid electrolyte in solid-state batteries.

[0096] The preferred thickness of the electrode is 0.1 μm to 1000 μm, and more preferably 0.1 μm to 300 μm.

[0097] According to another aspect, the present invention provides a method for making an electrode by a solvent route, comprising the steps of: mixing said binder according to the present invention, an active material and optionally a conductive agent in the presence of a solvent; depositing the mixture obtained in the previous step on a current collector to obtain an electrode; drying the electrode.

[0098] In this method, the solvent can be water or an organic solvent or a mixture of the two. The organic solvent can be selected from the group consisting of N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), triethyl phosphite (TEP), acetone, cyclopentanone, tetrahydrofuran, methyl ethyl ketone (MEK), methyl isobutyl ketone (MiBK), ethyl acetate (EA), butyl acetate (BA), ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), γ-butyrolactone, and N-butylpyrrolidone; and mixtures thereof.

[0099] According to another aspect of the present invention, there is provided a lithium ion battery. Preferably, the lithium ion battery comprises a positive electrode, a negative electrode, and a separator, and at least one electrode is an electrode according to the present invention. [Example]

[0100] The following examples illustrate the invention without limiting the latter.

[0101] [pH measurement method] A Mettler Toledo SevenEasy brand pH meter or equivalent and an InLab Routine Pro electrode are used. Before calibration, check the electrode's cleanliness. If necessary, clean the electrode with warm soapy water. Ensure the pH electrode is always filled with KCl filling solution. Calibrate the device with pH 10, 7, and 4 buffer solutions. To calibrate, immerse the electrode in pH 10 buffer solution, and once the pH stabilizes, repeat the procedure with pH 7 and then pH 4 buffer solutions, aided by Calibration. Rinse the electrode with distilled water and allow it to dry between each buffer solution. The electrode is pre-conditioned by immersing it in a 0.1 M HCl solution for 1-2 hours, followed by rinsing with deionized water, before measurement. To measure pH, immerse the electrode in the compound to be tested and stir for a few seconds. Allow the measurement to stabilize for 15 minutes and then read the value displayed by the pH meter. Measurements are performed at ambient temperature.

[0102] Polymer B 416 g of deionized water and 3.2 g of 97% sodium dodecyl sulfate were weighed into a 1000 ml glass reactor with mechanical stirring and oil bath heating. In a first vessel with magnetic bar stirring, 150 g of deionized water, 1.06 g of 97% sodium dodecyl sulfate, 0.7 g of diallyl phthalate, 163 g of methyl methacrylate, and 116 g of methacrylic acid were weighed. This mixture was continuously stirred throughout the polymerization. A solution consisting of 0.7 g of ammonium persulfate and 10 g of deionized water was prepared in a second vessel. A solution consisting of 0.1 g of sodium metabisulfite and 10 g of deionized water was prepared in a third vessel. The reactor was heated to 76°C. The contents of the second and third vessels were introduced into the reactor, and then the contents of the first vessel were introduced into the reactor using a peristaltic pump, while still stirring, for 120 minutes at 76°C. The dispersion was heated at 78°C for 60 minutes. A dispersion containing 28% dry matter was obtained. The particles had a median diameter of 100 nm as measured by DLS. The pH of the aqueous dispersion was 3.1. A 20% aqueous dispersion of lithium hydroxide was added to this solution to obtain a degree of lithiation of 35%.

[0103] Polymer A An aqueous dispersion of PVDF polymer in the form of a latex with a solids content of 24.1% and a particle size of 145 nm, pH 3.6, is prepared. PVDF is a copolymer of vinylidene fluoride and hexafluoropropylene, characterized by a melting point of 148°C as measured by DSC (differential scanning calorimetry).

[0104] The aqueous formulation is prepared according to the following method. Polymer A is weighed in a container, and while stirring with a mechanical stirrer, acrylic polymer B is added over 10 minutes. The stirring time after adding the acrylic polymer is 10 minutes.

[0105] Example 1 70.11 g of polymer A was weighed out and 30.04 g of polymer B was added. The aqueous formulation, containing 70% PVDF and 30% acrylic polymer by weight on a dry basis, was placed in a crystallizing dish and dried in an oven at 110 °C for 24 hours. A homogeneous powder was obtained, which was first ground using an electric knife mill of the coffee grinder type and then cryogenically ground using a ball mill. The resulting powder was particularly homogeneous, allowing it to be very easily compressed to obtain a polymer layer on the metal surface, for example, using a calender or press. This method therefore allows dry coating to be carried out on aluminum-type supports, which makes it possible to produce cathodes without the presence of toxic solvents such as NMP, and in fact even makes it possible to avoid aqueous methods that require particularly expensive drying operations and complex formulations that require difficult rheological control. A similar solventless method can be used to produce anodes.

Claims

1. A binder comprising a fluoropolymer A and an acrylic polymer B, wherein the acrylic polymer B is one or more CO ２ － Li ＋ A binder comprising monomer units containing functional groups, characterized in that said acrylic polymer B has a degree of lithiation of at least 30%.

2. The acrylic polymer B is —CO ２ 2. The binder of claim 1, characterized in that it also comprises at least 5 mol % of monomer units containing H or carboxylic acid anhydride functionality.

3. Fluoropolymer A may be selected from the group consisting of 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); perfluoro(1,3-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole) (PDD); ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ A compound of formula X, wherein X is SO ２ F, CO ２ H, CH ２ OH, CH ２ OCN or CH ２ OPO ３ H]; ２ = CFOCF ２ CF ２ SO ２ Compounds of formula F(CF ２ ) ｎ CH ２ OCF = CF ２ wherein n is 1, 2, 3, 4 or 5; １ CH ２ OCF = CF ２ wherein R １ is hydrogen or F(CF ２ ) ｍ and m is 1, 2, 3 or 4; ２ OCF=CH ２ wherein R ２ is F(CF ２ ) ｐ and p is 1, 2, 3 or 4; perfluorobutylethylene (PFBE); 3,3,3-trifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-1-propene, or a mixture thereof.

4. The fluoropolymer A is a copolymer of monomer units derived from vinylidene fluoride and vinyl fluoride; 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); perfluoro(1,3-dioxole); perfluoro(2,2-dimethyl-1,3-dioxole) (PDD); ２ = CFOCF ２ CF (CF ３ ) OCF ２ CF ２ A compound of formula X, wherein X is SO ２ F, CO ２ H, CH ２ OH, CH ２ OCN or CH ２ OPO ３ H]; ２ = CFOCF ２ CF ２ SO ２ Compounds of formula F(CF ２ ) ｎ CH ２ OCF = CF ２ wherein n is 1, 2, 3, 4 or 5; １ CH ２ OCF = CF ２ wherein R １ is hydrogen or F(CF ２ ) ｍ and m is 1, 2, 3 or 4; ２ OCF=CH ２ wherein R ２ is F(CF ２ ) ｐ and p is 1, 2, 3 or 4; perfluorobutylethylene (PFBE); and optional monomer units of a monomer selected from the group consisting of 3,3,3-trifluoropropene and 2-trifluoromethyl-3,3,3-trifluoro-1-propene, or mixtures thereof.

5. 5. The binder according to claim 1, wherein the fluoropolymer A is a homopolymer of vinylidene fluoride or a copolymer comprising monomer units derived from vinylidene fluoride and monomer units derived from a monomer selected from the group consisting of trifluoroethylene, chlorotrifluoroethylene, 1,2-difluoroethylene, tetrafluoroethylene, hexafluoropropylene, or a mixture thereof.

6. 6. A binder according to any one of claims 1 to 5, characterized in that the fluoropolymer A comprises monomer units having at least one functional group selected from the group consisting of carboxylic acid, carboxylic anhydride, carboxylic ester, epoxy group, e.g. glycidyl, amide, hydroxyl, carbonyl, mercapto, sulfide, oxazoline, phenol, ester, ether, siloxane, sulfonic acid, sulfuric acid, phosphoric acid and phosphonic acid groups.

7. Acrylic polymer B is 3000 g.mol －１ 7. The binder according to claim 1, characterized in that it has a number-average molar mass of at least 1000 .mu.m.sup.

2.

8. The acrylic polymer B is one or more CO ２ － Li ＋ 8. The binder according to claim 1, comprising a monomer unit containing a functional group, a monomer unit having one or more carboxylic acid or carboxylic anhydride functional groups, and a monomer unit having one or more carboxylic acid ester functional groups.

9. The acrylic polymer B is represented by the formula R １ R ２ C=C(R ３ ) ((X １ ) ｎ － CO ２ － Li ＋ ) monomer units M0 derived from a monomer of the formula １ , R ２ and R ３ are, independently of each other, H, CO ２ H, and CO ２ H or CO ２ C optionally substituted with R′ groups １ -C ５ alkyl, and R' is C １ -C ５ alkyl], formula R １ R ２ C=C(R ３ ) ((X ２ ) ｎ -CO ２ H) derived from the monomer unit M1 [wherein the substituent R １ , R ２ and R ３ are, independently of each other, H, CO ２ H, and CO ２ H or CO ２ C optionally substituted with R′ groups １ -C ５ alkyl, and R' is C １ -C ５ is alkyl; X １ and X ２ are, independently of one another, C optionally having one or more hydroxyl groups; １ -C １０ alkyl hydrocarbon group; n is 0 or 1; and ４ R ５ C=C(R ６ ) C(O)R ７ Optional monomeric units M2 derived from a monomer of formula ４ , R ５ and R ６ are, independently of each other, H, CO ２ H, and CO ２ H or CO ２ C optionally substituted with R′ groups １ -C ５ alkyl, and R' is C １ -C ５ alkyl; R ７ is -NHC(CH ３ ) ２ CH ２ C(O)CH ３ or —OR′, where R′ is a C optionally substituted with one or more —OH groups. １ -C １８ 9. The binder according to claim 1, wherein the alkyl group is selected from the group consisting of alkyl, aryl, arylsulfonyl ...

10. 10. Binder according to any one of claims 1 to 9, characterized in that the acrylic polymer B in aqueous solution has a pH, measured in water at ambient temperature, of 2.0 to 10.

0.

11. 11. The binder according to claim 1, wherein the weight content of the acrylic polymer B relative to the fluoropolymer A is 1% to 70%.

12. 12. Binder according to any one of claims 1 to 11, characterized in that the acrylic polymer B also contains divalent cations.

13. An electrode comprising the binder according to any one of claims 1 to 12, an active material, and an optional conductive agent.

14. Composition by weight: a. 50% to 99.9%, preferably 50% to 99%, of active material; b. 25% to 0%, preferably 25% to 0.5%, of a conductive agent; c. 25% to 0.05%, preferably 25% to 0.5%, of the binder according to any one of claims 1 to 12; d. 0% to 5% of at least one additive selected from the group consisting of plasticizers, ionic liquids, dispersants for conductive additives, and flow aids; 14. The electrode of claim 13, wherein the sum of all these percentages is 100%.

15. 15. The electrode according to claim 13 or 14, wherein the conductive agent is composed of one or more materials selected from the group consisting of carbon black such as acetylene black or ketjen black; carbon fiber such as carbon nanotube, carbon nanofiber, or vapor-grown carbon fiber; and metal powder such as SUS powder and aluminum powder.

16. In the positive electrode, the active material is LiCoO ２ , Li(Ni, Co, AI)O ２ , Li （１＋ｘ） Ni ａ Mn ｂ Co ｃ (x is a real number equal to or greater than 0; a = 0.8, 0.6, 0.5, or 1 / 3; b = 0.1, 0.2, 0.3, or 1 / 3; c = 0.1, 0.2, or 1 / 3), LiNiO ２ , LiMn ２ O ４ , LiCoMnO ４ , Li ３ NiMn ３ O ３ , Li ３ Fe ２ (P.O. ４ ) ３ , Li ３ V ２ (P.O. ４ ) ３ , Li １＋ｘ Mn ２－ｘ－ｙ M ｙ O ４ LiMn spinel substituted with different elements having a composition represented by the formula: [wherein M represents at least one metal selected from Al, Mg, Co, Fe, Ni, and Zn, and x and y independently represent real numbers of 0 to 2], lithium titanate Li ｘ TiO ｙ [x and y independently represent real numbers from 0 to 2], and LiMPO ４ The electrode according to any one of claims 13 to 15, wherein the electrode is selected from the group consisting of lithium metal phosphates having a composition represented by the formula: [wherein M represents Fe, Mn, Co, or Ni].

17. In the negative electrode, the active material is selected from the group consisting of lithium alloys, lithium metal, metal oxides, carbon materials such as graphite or hard carbon, silicon, silicon alloys, and Li ４ Ti ５ O １２ The electrode according to any one of claims 13 to 15, selected from the group consisting of:

18. 1. A method of making a dry-coated electrode, comprising: Mixing the binder according to any one of claims 1 to 12 in powder form, an active material and, optionally, a conductive agent; depositing the mixture obtained in the previous step on a current collector to obtain an electrode; consolidating said electrode by a thermomechanical treatment step carried out at a temperature T1 between Tm-50°C<T1<Tg+50°C if Tg>Tm, or at a temperature T1 between Tg-50°C<T1<Tm+50°C if Tm>Tg, wherein Tm is the melting point of fluoropolymer A and Tg is the glass transition temperature of acrylic polymer B; A method comprising:

19. 1. A method for making an electrode by a solvation route, comprising: Mixing the binder according to any one of claims 1 to 12, an active material and, optionally, a conductive agent in the presence of a solvent; depositing the mixture obtained in the previous step on a current collector to obtain an electrode; drying the electrode; A method comprising:

20. A lithium ion battery comprising a positive electrode, a negative electrode, and a separator, wherein at least one electrode is the electrode according to any one of claims 13 to 17.

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