Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/139—Processes of manufacture
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F8/00—Chemical modification by after-treatment
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/28—Treatment by wave energy or particle radiation
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D127/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers
  • C09D127/02—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment
  • C09D127/12—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
  • C09D127/16—Homopolymers or copolymers of vinylidene fluoride
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D127/00—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers
  • C09D127/22—Coating compositions based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Coating compositions based on derivatives of such polymers modified by chemical after-treatment
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/24—Electrically-conducting paints
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/04—Processes of manufacture in general
  • H01M4/0402—Methods of deposition of the material
  • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/04—Processes of manufacture in general
  • H01M4/0402—Methods of deposition of the material
  • H01M4/0409—Methods of deposition of the material by a doctor blade method, slip-casting or roller coating
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/04—Processes of manufacture in general
  • H01M4/043—Processes of manufacture in general involving compressing or compaction
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
  • H01M4/139—Processes of manufacture
  • H01M4/1391—Processes of manufacture of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
  • H01M4/621—Binders
  • H01M4/622—Binders being polymers
  • H01M4/623—Binders being polymers fluorinated polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F214/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen
  • C08F214/18—Monomers containing fluorine
  • C08F214/22—Vinylidene fluoride
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the present invention pertains to hydrophilic vinylidene fluoride polymers, to a process for preparing these polymers and to the use of the same for producing articles characterized by improved performances.
• Fluoropolymers such as vinylidene fluoride polymers (PVDF) are very useful in a wide range of applications such as automotive materials, pipes and fittings, bearings, linings, and vessels, where good interfacial adhesion between the fluoropolymer and metal surfaces is highly demanded.
• PVDF vinylidene fluoride polymers
• fluoropolymers have very low surface energies and thus poor adhesion with metals.
• Fluoropolymers in the form of sheets, films and shaped articles have been chemically treated, subjected to electrical discharges using corona discharge and plasmas, subjected to flame treatment, and subjected to physical treatment such as chemical adsorbing procedures to improve their adhesion with metals.
• US 6300641 discloses a process for irradiating energized ion particles onto the polymeric surface of an article, such as a PVDF surface, in order to decrease the wetting angle of said surface and to increase its adhesive strength.
• a chemical modification occurs onto the surface of the article since the irradiation is carried out in the presence of a reactive gas that chemically reacts with the surface of the polymer.
• JP3269024 discloses a method for producing a surface-modified fluororesin which comprises irradiating the fluororesin with short wavelength ultraviolet rays. Said method is preferably applied to fluororesins in the form of films, but the method can be applied to powders too.
• PVDF has been used as electrode binder of nonaqueous electrolyte secondary batteries.
• PVDF homopolymer has poor adhesion to metal.
• VDF vinylidene fluoride
• the present invention relates to an electrode-forming composition [composition (C)] comprising: a) at least one electrode active material (AM); b) at least one binder (B), wherein binder (B) comprises at least one vinylidene fluoride (VDF) polymer [polymer (A)], wherein polymer (A) is obtained by a process comprising a step of irradiating a polymer (F) with an ionizing radiation at a dosage lower than 70 kGy, wherein polymer (F) comprises:
• VDF vinylidene fluoride
• the present invention pertains to the use of the electrode forming composition (C) as above defined in a process for the manufacture of an electrode [electrode (E)], said process comprising:
• composition (B) providing an electrode-forming composition [composition (C)] as above defined;
• step (C) applying the composition (C) provided in step (B) onto the at least one surface of the metal substrate provided in step (A), thereby providing an assembly comprising a metal substrate coated with said composition (C) onto the at least one surface;
• step (D) drying the assembly provided in step (C);
• step (E) submitting the dried assembly obtained in step (D) to a compression step to obtain the electrode (E) of the invention.
• the present invention pertains to the electrode [electrode (E)] obtainable by the process of the invention.
• the present invention pertains to an electrochemical device comprising at least one electrode (E) of the present invention.
• recurring unit derived from vinylidene fluoride also generally indicated as vinylidene difluoride 1 ,1-difluoroethylene, VDF
• recurring unit derived from vinylidene fluoride also generally indicated as vinylidene difluoride 1 ,1-difluoroethylene, VDF
• CF2 CFl2
• Polymer (A) is obtained by a process comprising a step of irradiating a polymer (F) with an ionizing radiation at a dosage lower than 70 kGy, wherein polymer (F) comprises:
• VDF vinylidene fluoride
• the irradiation process provoke the modification of polymer (F) with the formation of polar groups, mainly hydroxyl groups in the backbone of the VDF copolymer, which allow obtaining a polymer (A) rendered hydrophilic to water and having remarkably lower contact angle.
• preferred polymers (A) have contact angles below 73°, preferably below 70°.
• contact angle or “water contact angle”used in the present invention is defined as the angle formed between a tangential line of a water drop put on a surface and the surface itself in which the water drop exists.
• a decrease in the contact angle means that the water drop is spread widely and thinly onto material surface, whereby the attraction property of the surface to water, that is to say hydrophilicity, increases.
• a film of polymer (A) may be prepared by any known process starting from polymer (A) in the form of powder, such as processing a composition of polymer (A) in a suitable solvent by casting onto an inert support, preferably a glass support, followed by suitable drying to remove the solvent. Water contact angle measurements can then be performed on the side of the film exposed to the substrate.
• water contact angle measurements are suitably performed on polymer films cast from a NMP solution on a glass surface at room temperature using a Contact Angle System OCA20 (DataPhysics Instruments GmbH) instrument. Drops of MilliQ water are automatically deposited on the film surface exposed to the glass substrate during film preparation. The contact angle is determined as an average of 10 measurements.
• the polymer (F) is preferably a semi-crystalline polymer.
• semi-crystalline means a fluoropolymer that has, besides the glass transition temperature Tg, at least one crystalline melting point on DSC analysis.
• a semi-crystalline fluoropolymer is hereby intended to denote a fluoropolymer having a heat of fusion determined according to ASTM D 3418 of advantageously at least 0.4 J/g, preferably of at least 0.5 J/g, more preferably of at least 1 J/g.
• the intrinsic viscosity of polymer (F), measured in dimethylformamide at 25 0 C is comprised between 0.1 l/g and 0.80 l/g, more preferably between 0.15 l/g and 0.45 l/g even more preferably between 0.25 l/g and 0.35 l/g.
• the polymer (F) used in the process of the present invention usually has a melting temperature (T m ) comprised in the range from 120 to 200°C.
• the melting temperature may be determined from a DSC curve obtained by differential scanning calorimetry (hereinafter, also referred to as DSC).
• DSC differential scanning calorimetry
• T m melting temperature
• the polymer (F) may optionally comprise recurring units derived from one or more fluorinated comonomers (CF) different from VDF.
• fluorinated comonomer CF
• fluorinated comonomer CF
• Non-limitative examples of suitable fluorinated comonomers include, notably, the followings:
• C2-C8 fluoro- and/or perfluoroolefins such as tetrafluoroethylene (TFE), hexafluoropropylene (HFP), pentafluoropropylene and hexafluoroisobutylene;
• polymer (F) comprises from 0.1 to 10.0% by moles, preferably from 0.3 to 5.0% by moles, more preferably from 0.5 to 3.0% by moles of recurring units derived from said fluorinated comonomer (CF).
• the polymer (F) does not include any fluorinated copolymer (CF).
• the polymer (F) may be obtained by polymerization of a VDF monomer and optionally at least one comonomer (CF), either in suspension in organic medium, or in aqueous emulsion, according to the procedures known in literature.
• the procedure for preparing the polymer (F) comprises polymerizing in an aqueous medium in the presence of a radical initiator the vinylidene fluoride (VDF), and optionally at least one comonomer (CF), optionally in the presence of a chain transfer agent and of a dispersing agent in a reaction vessel.
• VDF vinylidene fluoride
• CF comonomer
• the process of the invention is carried out at a temperature of at least 20° C, preferably of at least 30° C, more preferably of at least 35° C.
• polymer (F) is typically provided in form of powder.
• polymer (F) is typically provided in the form of an aqueous dispersion (D), which may be used as directly obtained by the emulsion polymerization or after a concentration step.
• aqueous dispersion (D) preferably, the solid content of polymer (F) in dispersion (D) is in the range comprised between 20 and 50% by weight.
• Polymer (F) obtained by emulsion polymerization can be isolated from the aqueous dispersion (D) by concentration and/or coagulation of the dispersion and obtained in powder form by subsequent drying.
• Polymer (F) in the form of powder may be optionally further extruded to provide polymer (F) in the form of pellets.
• Extrusion is suitably carried out in an extruder. Duration of extrusion suitably ranges from few seconds to 3 minutes.
• the polymer (F) may be dissolved in any suitable organic solvent to provide a solution (Sol) of polymer (F).
• a solution (Sol) of polymer (F) Preferably, the solid content of polymer (F) in solution (Sol) is in the range comprised between 2 and 30% by weight.
• Non-limitative examples of suitable organic solvents for dissolving polymer (F) are N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, hexamethylphosphamide, dioxane, tetrahydrofuran, tetramethylurea, triethyl phosphate, and trimethyl phosphate, aliphatic ketones, cycloaliphatic ketones, cycloaliphatic esters. These organic solvents may be used singly or in mixture of two or more species.
• the polymer (F) subjected to the ionizing is preferably in the form of powder.
• the step of irradiating a polymer (F) can be carried out with any ionizing radiation, which can thus be an a ray, b ray, g ray, or electron beam; however, from the perspectives of safety and reactivity, b ray, g ray and electron beam are preferred.
• any ionizing radiation which can thus be an a ray, b ray, g ray, or electron beam; however, from the perspectives of safety and reactivity, b ray, g ray and electron beam are preferred.
• the irradiation has to be carried out in the presence of oxygen. It may be performed in air.
• Irradiation in the presence of oxygen may further favour the formation of said hydroxyl groups (Choi, Y. Kim, M. Preparation and characterization of polyvinylidene fluoride by irradiating electron beam. Appl. Chem. Eng. 22, 353- 357).
• the irradiation step of the process of the present invention is performed at a dosage of preferably from 0.1 kGy to 70 kGy, and more preferably from 1 kGy to 40 kGy, even more preferably from 1 kGy to 20 kGy.
• polymer (F) can be modified and rendered hydrophilic under such soft conditions allowing to minimize the damages to the original backbone structure of the polymer (F). This is mainly due to the low intensity radiation used.
• the monomer composition of polymer (A) and polymer (F) is substantially the same.
• the low intensity radiation used in the process of the invention allows polymer (A) to become hydrophilic thanks to the presence of polar groups in the backbone of the polymer chain.
• a decrease in the contact angle means the formation of hydrophilic groups on the surface of polymer and the formation of hydrophilic groups would mean a decrease in the contact angle.
• the electrode forming compositions (C) of the present invention include one or more electro-active materials (AM).
• AM electro-active materials
• the term “electro-active material” is intended to denote a compound which is able to incorporate or insert into its structure and substantially release therefrom alkaline or alkaline-earth metal ions during the charging phase and the discharging phase of an electrochemical device.
• the electro active material is preferably able to incorporate or insert and release lithium ions.
• electro active material in the electrode forming composition of the invention depends on whether said composition is used in the manufacture of a positive electrode [electrode (Ep)] or a negative electrode [electrode (En)].
• the electro active compound may comprise a Lithium containing compound.
• the lithium containing compound can be a metal chalcogenide of formula LiMCh, wherein M is at least one metal selected from transition metals such as Co, Ni, Fe, Mn, Cr and V or a metal such as Al and a mixture of thereof and Q is a chalcogen such as O or S.
• M is at least one metal selected from transition metals such as Co, Ni, Fe, Mn, Cr and V or a metal such as Al and a mixture of thereof and Q is a chalcogen such as O or S.
• M is at least one metal selected from transition metals such as Co, Ni, Fe, Mn, Cr and V or a metal such as Al and a mixture of thereof and Q is a chalcogen such as O or S.
• M is at least one metal selected from transition metals such as Co, Ni, Fe, Mn, Cr and V or a metal such as Al and a mixture of thereof and Q is a chalcogen such as O or S.
• M is the same as defined above.
• the electro active compound may comprise a lithiated or partially lithiated transition metal oxyanion-based electro-active material of formula MiM2(J04) f Ei- f , wherein Mi is lithium, which may be partially substituted by another alkali metal representing less than 20% of the Mi metals, M2 is a transition metal at the oxidation level of +2 selected from Fe, Mn, Ni or mixtures thereof, which may be partially substituted by one or more additional metals at oxidation levels between +1 and +5 and representing less than 35% of the M2 metals, JO 4 is any oxyanion wherein J is either P, S, V, Si, Nb, Mo or a combination thereof, E is a fluoride, hydroxide or chloride anion, f is the molar fraction of the JO 4 oxyanion, generally comprised between 0.75 and 1.
• the MiM 2 lithiated or partially lithiated transition metal oxyanion-based electro-active material of formula MiM2(J04)
• the electro active compound in the case of forming a positive electrode has formula Li3- x M’ y M” 2-y (J0 4 )3 wherein 0 ⁇ x ⁇ 3, 0 ⁇ y ⁇ 2, M’ and M” are the same or different metals, at least one of which being a transition metal, JO4 is preferably PO4 which may be partially substituted with another oxyanion, wherein J is either S, V, Si, Nb, Mo or a combination thereof.
• the electro active compound is a phosphate-based electro-active material of formula Li(Fe x Mni- x )P0 4 wherein 0 ⁇ x ⁇ 1, wherein x is preferably 1 (that is to say, lithium iron phosphate of formula LiFePC ).
• the electro active material for a positive electrode is selected from lithium-containing complex metal oxides of general formula (III)
• the electro active material in this embodiment is preferably a compound of formula (III) wherein Y is O.
• M1 is Mn and M2 is Co or Ml is Co and M2 is Al.
• Examples of such active materials include LiNi x Mn y Co z 0 2 , herein after referred to as NMC, and LiNi x Co y Al z 0 2 , herein after referred to as NCA.
• the compound AM is a compound of formula (III) as above defined, wherein 0.5 ⁇ x ⁇ 1 , 0.1 ⁇ y ⁇ 0.5, and 0 ⁇ z ⁇ 0.5.
• Non limitative examples of suitable electro active materials for positive electrode of formula (III) include, notably:
• LiNlo,9Mno,o5Coo,o502. are particularly preferred.
• the electro active compounds may preferably comprise one or more carbon-based materials and/or one or more silicon-based materials.
• the carbon-based materials may be selected from graphite, such as natural or artificial graphite, graphene, carbon black and carbon nano tubes (CNT).
• graphite such as natural or artificial graphite, graphene, carbon black and carbon nano tubes (CNT).
• the carbon-based material is preferably graphite.
• the silicon-based compound may be one or more selected from the group consisting of chlorosilane, alkoxysilane, aminosilane, fluoroalkylsilane, silicon, silicon chloride, silicon carbide and silicon oxide. More particularly, the silicon-based compound may be silicon oxide or silicon carbide.
• the silicon-based compounds are comprised in an amount ranging from 1 to 60 % by weight, preferably from 5 to 20 % by weight with respect to the total weight of the electro active compounds.
• the electrode forming compositions of the invention comprise at least one solvent (S).
• the solvent in cathode forming composition comprises one or more organic solvents, preferably polar solvents, examples of which may include: N-methyl-2- pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide, hexamethylphosphamide, dioxane, tetrahydrofuran, tetramethylurea, triethyl phosphate, and trimethyl phosphate. These organic solvents may be used singly or in mixture of two or more species.
• the electrode forming compositions of the present invention typically comprise from 0.5 wt % to 10 wt %, preferably from 0.7 wt % to 5 wt % of polymer (A).
• the composition also comprises from 80 wt % to 99 wt %, of electro active material(s). All percentages are weight percentages of the total “solids”. For “solids” it is intended “all the ingredients of the electrode forming composition of the invention excluding the solvent”.
• the solvent is from 10 wt % to 90 wt % of the total amount of the composition.
• the solvent is preferably from 25 wt % to 75 wt %, more preferably from 30 wt % to 60 wt % of the total amount of the composition.
• the solvent is preferably from 5 wt % to 60 wt%, more preferably from 15 wt % to 40 wt % of the total amount of the composition.
• the electrode forming compositions of the present invention may further include one or more optional conductive agents in order to improve the conductivity of a resulting electrode made from the composition of the present invention.
• Conducting agents for batteries are known in the art.
• Examples thereof may include: carbonaceous materials, such as carbon black, graphite fine powder carbon nanotubes (CNT), graphene, or fiber, or fine powder or fibers of metals such as nickel or aluminum.
• the optional conductive agent is preferably carbon black. Carbon black is available, for example, under the brand names, Super P ® or Ketjenblack ® .
• the conductive agent is different from the carbon-based material described above.
• the amount of optional conductive agent is preferably from 0 to 30 wt % of the total solids in the electrode forming composition.
• the optional conductive agent is typically from 0 wt % to 10 wt %, more preferably from 0 wt % to 5 wt % of the total amount of the solids within the composition.
• the optional conductive agent is typically from 0 wt % to 5 wt %, more preferably from 0 wt % to 2 wt % of the total amount of the solids within the composition, while for anode forming compositions comprising silicon based electro active compounds it has been found to be beneficial to introduce a larger amount of optional conductive agent, typically from 5 wt % to 20 wt % of the total amount of the solids within the composition.
• the electrode-forming composition (C) of the invention can be used in a process for the manufacture of an electrode, said process comprising:
• composition (B) providing an electrode-forming composition [composition (C)] as above defined;
• step (C) applying the composition (C) provided in step (B) onto the at least one surface of the metal substrate provided in step (A), thereby providing an assembly comprising a metal substrate coated with said composition (C) onto the at least one surface;
• step (D) drying the assembly provided in step (C);
• step (E) submitting the dried assembly obtained in step (D) to a compression step to obtain the electrode (E) of the invention.
• the metal substrate is generally a foil, mesh or net made from a metal, such as copper, aluminium, iron, stainless steel, nickel, titanium or silver.
• the electrode forming composition is applied onto at least one surface of the metal substrate typically by any suitable procedures such as casting, printing and roll coating.
• step (C) may be repeated, typically one or more times, by applying the electrode forming composition provided in step (B) onto the assembly provided in step (D).
• the assembly obtained at step (D) may be further subjected to a compression step, such as a calendaring process, to achieve the target porosity and density of the electrode.
• a compression step such as a calendaring process
• the assembly obtained at step (D) is hot pressed, the temperature during the compression step being comprised from 25°C and 130°C, preferably being of about 90°C.
• Preferred target porosity for the obtained electrode is comprised between 15% and 40%, preferably from 20% and 30%.
• the porosity of the electrode is calculated as the complementary to unity of the ratio between the measured density and the theoretical density of the electrode, wherein:
• the measured density is given by the mass divided by the volume of a circular portion of electrode having diameter equal to 24 mm and a measured thickness;
• the theoretical density of the electrode is calculated as the sum of the product of the densities of the components of the electrode multiplied by their volume ratio in the electrode formulation.
• the present invention pertains to the electrode obtainable by the process of the invention.
• the present invention relates to an electrode comprising:
• composition comprising:
• polymer (A) at least one vinylidene fluoride (VDF) polymer [polymer (A)], wherein polymer (A) is obtained by a process comprising a step of irradiating a polymer (F) with an ionizing radiation at a dosage lower than 70 kGy, wherein polymer (F) comprises:
• VDF vinylidene fluoride
• the electrode-forming composition (C) of the present invention is particularly suitable for the manufacturing of positive electrodes for electrochemical devices.
• the Applicant has surprisingly found that the electrode (E) of the present invention shows outstanding adhesion of the binder to current collector.
• the electrode (E) of the invention is thus particularly suitable for use in electrochemical devices, in particular in secondary batteries.
• the term “secondary battery” is intended to denote a rechargeable battery.
• the secondary battery of the invention is preferably an alkaline or an alkaline-earth secondary battery.
• the secondary battery of the invention is more preferably a Lithium-ion secondary battery.
• the present invention pertains to an electrochemical device comprising at least one electrode (E) of the present invention.
• the electrochemical device according to the present invention being preferably a secondary battery, comprises:
• the positive electrode and the negative electrode is the electrode (E) of the present invention.
• an electrochemical device is a secondary battery comprising:
• the negative electrode is the electrode (E) according to the present invention.
• An electrochemical device according to the present invention can be prepared by standard methods known to a person skilled in the art.
• Intrinsic viscosity ( h ) [dl/g] was measured using the following equation on the basis of dropping time, at 25° C, of a solution obtained by dissolving the polymer in N,N-dimethylformamide at a concentration of about 0.2 g/dl using a Ubbelhode viscosimeter: where c is polymer concentration [g/dl], h r is the relative viscosity, i.e. the ratio between the dropping time of sample solution and the dropping time of solvent, h S p is the specific viscosity, i.e. h r -1 , and G is an experimental factor, which for polymer (A) corresponds to 3.
• Positive electrodes having final composition of 96.5% by weight of NMC, 1.5% by weight of polymer, 2% by weight of conductive additive were prepared as follows.
• a first dispersion was prepared by pre-mixing for 10 minutes in a centrifugal mixer 34.7 g of a 6% by weight solution of a polymer in NMP, 133.8 g of NMC, 2.8 g of SC-65 and 8.8 g of NMP.
• Polymer (F-1) was treated with e-beam (b radiation) radiation of 0.6 Mrad.
• the characteristics of the polymer A-1 are shown in Table 1.

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• 2022
  • 2022-04-11 CN CN202280043342.4A patent/CN117529507A/zh active Pending
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