Classifications

• • 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
  • C09D133/00—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 only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Coating compositions based on derivatives of such polymers
  • C09D133/24—Homopolymers or copolymers of amides or imides
  • C09D133/26—Homopolymers or copolymers of acrylamide or methacrylamide
• • 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
  • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
  • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
  • C08F220/04—Acids; Metal salts or ammonium salts thereof
  • C08F220/06—Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
• • 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
  • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
  • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
  • C08F220/10—Esters
  • C08F220/26—Esters containing oxygen in addition to the carboxy oxygen
  • C08F220/28—Esters containing oxygen in addition to the carboxy oxygen containing no aromatic rings in the alcohol moiety
  • C08F220/285—Esters containing oxygen in addition to the carboxy oxygen containing no aromatic rings in the alcohol moiety and containing a polyether chain in the alcohol moiety
  • C08F220/286—Esters containing oxygen in addition to the carboxy oxygen containing no aromatic rings in the alcohol moiety and containing a polyether chain in the alcohol moiety and containing polyethylene oxide in the alcohol moiety, e.g. methoxy polyethylene glycol (meth)acrylate
• • 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
  • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
  • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
  • C08F220/10—Esters
  • C08F220/34—Esters containing nitrogen, e.g. N,N-dimethylaminoethyl (meth)acrylate
  • C08F220/343—Esters containing nitrogen, e.g. N,N-dimethylaminoethyl (meth)acrylate in the form of urethane links
  • C08F220/346—Esters containing nitrogen, e.g. N,N-dimethylaminoethyl (meth)acrylate in the form of urethane links and further oxygen
• • 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
  • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
  • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
  • C08F220/52—Amides or imides
  • C08F220/54—Amides, e.g. N,N-dimethylacrylamide or N-isopropylacrylamide
  • C08F220/56—Acrylamide; Methacrylamide
• • 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
  • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
  • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
  • C08F220/52—Amides or imides
  • C08F220/54—Amides, e.g. N,N-dimethylacrylamide or N-isopropylacrylamide
  • C08F220/58—Amides, e.g. N,N-dimethylacrylamide or N-isopropylacrylamide containing oxygen in addition to the carbonamido oxygen, e.g. N-methylolacrylamide, N-(meth)acryloylmorpholine
  • C08F220/585—Amides, e.g. N,N-dimethylacrylamide or N-isopropylacrylamide containing oxygen in addition to the carbonamido oxygen, e.g. N-methylolacrylamide, N-(meth)acryloylmorpholine and containing other heteroatoms, e.g. 2-acrylamido-2-methylpropane sulfonic acid [AMPS]
• • 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
  • C08F222/00—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 carboxyl radical and containing at least one other carboxyl radical in the molecule; Salts, anhydrides, esters, amides, imides, or nitriles thereof
  • C08F222/02—Acids; Metal salts or ammonium salts thereof, e.g. maleic acid or itaconic acid
• • 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
  • C08F230/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and containing phosphorus, selenium, tellurium or a metal
  • C08F230/02—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and containing phosphorus, selenium, tellurium or a metal containing phosphorus
• • 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
• • 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
  • H01M4/043—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
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
  • H01M4/621—Binders
  • H01M4/622—Binders being polymers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the present invention relates to a binder for a non-aqueous electrolyte rechargeable battery, a negative electrode slurry for a rechargeable battery, a negative electrode for a rechargeable battery, and a rechargeable battery comprising the same.
• Non-aqueous electrolyte rechargeable batteries such as lithium ion rechargeable batteries
• lithium ion rechargeable batteries are widely used as power sources for electronic devices. High capacity and long cycle-life characteristics are desirable, however current lithium ion batteries are limited in their storage of electrical charge by the capacity of the negative electrode.
• an active material including a silicon atom may be used in a negative electrode.
• Silicon has a theoretical capacity of about 4,200 mAh/g, thus being important for application of a high capacity battery in terms of capacity.
• the volume expansion causes irreversible reactions, such as destruction of an electrical connection between active materials, separation of an active material from a current collector, and formation of a solid electrolyte interface (SEI) layer due to erosion of the active material by an electrode, and deterioration of service life associated therewith.
• SEI solid electrolyte interface
• current binders only accommodate limited silicon loading (up to 10 wt. %) before battery lifetime is significantly reduced because of reduced charge cycle stability.
• the binder typically an organic polymer, serves as the connective matrix that maintains contact between active materials throughout the anode layer and with the current collector onto which the anode is deposited during fabrication.
• polycarboxylate binders and derivatives including polyacrylic acids, polyamic acids, polyacrylamides, and other hydrogen bonding structures.
• WO2015/163302 discloses that capacity retention rates after 10 cycles of charging and discharging may be improved by using an aqueous solution of a crosslinked sodium polyacrylate copolymer.
• Sodium polyacrylate has been used as a water-soluble high-strength, high-elasticity binder. By using sodium polyacrylate, it is expected that volume changes accompanying charging and discharging of a battery including a silicon- containing active material is suppressed or reduced and cycle characteristics may be improved.
• US 2020/0343556 provides a binder for a non-aqueous electrolyte rechargeable battery including a blend of a first copolymer that includes a unit derived from a (meth)acrylic acid-based monomer, and a unit derived from a (meth)acrylonitrile monomer, and a second copolymer that includes a unit derived from an aromatic vinyl-based monomer, and a unit derived from an ethylenic unsaturated monomer comprising a carboxylic acid moiety.
• Said binder is capable of suppressing or reducing electrode expansion of the negative electrode, and to improve cycle characteristics.
• (A1) recurring units derived from an a,p-ethylenically unsaturated carboxylic acid monomer [monomer (AA)] of formula (III) wherein R a , R b and R c , equal to or different from each other, are independently selected from a hydrogen atom and a C1-C3 hydrocarbon group;
• R 1 and R 2 being the same or different from each other, may be selected from a hydrogen atom, from a linear or branched alkyl group having 1 to 6 carbon atoms, a carboxylic group or an amide group,
• R 3 represents a hydrogen atom or a methyl group
• R 4 and R 5 being the same or different from each other, may be selected from a hydrogen atom or from a linear or branched alkyl group having 1 to 6 carbon atoms;
• R' is selected from the group consisting of H, -COOH, -CH2COOH or an alkyl group, wherein the alkyl group is preferably a methyl group;
• R" and R iH being the same or different from each other, may be selected from a hydrogen atom or from a linear or branched alkyl group having 1 to 6 carbon atoms, or can be -COOH group;
• A is a linkage selected from the group consisting of a -C(O)-O- group or a -C(O)-NH- group;
• R x is selected from a hydrogen atom or a linear or branched C3-C20 hydrocarbon chain moiety comprising at least one functional groups selected from the group consisting of ether (-O-), heterocyclic group, sulfonic acid group (-SO3H), phosphonic acid group (-PO3H2) and phosphoric acid group (-OPO3H2).
• composition (Comp) for use in the preparation of electrodes for electrochemical devices, characterized by comprising: a) at least one polymer (P), b) an electrode active material, c) an aqueous solvent, and d) optionally at least one electroconductivity-imparting additive.
• the present invention provides a process for preparing an electrode [electrode (E)], said process comprising:
• step (iii) applying the composition (Comp) provided in step (ii) onto the at least one surface of the metal substrate provided in step (i), thereby providing an assembly comprising a metal substrate coated with said composition (Comp) onto the at least one surface;
• step (v) submitting the dried assembly obtained in step (iv) 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.
• the term “percent by weight” indicates the content of a specific component in a mixture, calculated as the ratio between the weight of the component and the total weight of the mixture.
• weight percent indicates the ratio between the weight of all non-volatile ingredients in the liquid.
• electrochemical cell By the term “electrochemical cell”, it is hereby intended to denote an electrochemical cell comprising a positive electrode, a negative electrode and a liquid electrolyte, wherein a monolayer or multilayer separator is adhered to at least one surface of one of said electrodes.
• Non-limitative examples of electrochemical cells include, notably, batteries, preferably secondary batteries, and electric double layer capacitors.
• secondary battery it is intended to denote a rechargeable battery.
• Non-limitative examples of secondary batteries include, notably, alkaline or alkaline-earth secondary batteries.
• an electrode forming composition is a composition of matter, typically a fluid composition, wherein solid components are dissolved or dispersed in a liquid, which can be applied onto a metallic substrate and subsequently dried thus forming an electrode wherein the metallic substrate acts as current collector.
• Electrode forming compositions typically comprise at least an electro active material and at least a binder.
• the electrode-forming composition [composition (Comp)] of the present invention comprises at least one polymer (P), which functions as a binder.
• Polymer (P) can be obtained by radical copolymerization of a mixture of a monomer (M) as above defined, an a,p-ethylenically unsaturated carboxylic acid monomer [monomer (AA)] and a (meth)acrylamide monomer [monomer (AM)], as above defined.
• the at least one a,p-ethylenically unsaturated carboxylic acid monomer (AA) of formula (III) as above defined is preferably selected from the group consisting of acrylic acid, methacrylic acid, ethacrylic acid, crotonic, methyl (meth)acrylic acid, ethyl (meth)acrylic acid, propyl (meth)acrylic acid, isopropyl (meth)acrylic acid, n-butyl (meth)acrylic acid, 2-ethylhexyl (meth)acrylic acid, n-hexyl (meth)acrylic acid and n-octyl (meth)acrylic acid.
• the (meth)acrylamide monomer [monomer (AM)] of formula (I) is preferably selected from the group consisting of (meth)acrylamides or N- substituted (meth)acrylamide such as N-alkyl acrylamides, N,N- dialkylacrylamides.
• the “heterocyclic group” in residue R x of monomer (M) includes saturated heterocyclic group having at least one nitrogen atom compound, such as imidazolidinone.
• the monomer (M) may for example be a compound of formula (Ila)
• the monomer (M) may for example be a compound of formula (lid) or a compound of formula (He) wherein in the formulae (lid) and (He) R', R" and R iH are as above defined.
• the polymer (P) is obtained by radical copolymerization of a mixture of:
• Any source of free radicals can be used. It is possible in particular to generate free radicals spontaneously, for example by increasing the temperature, with appropriate monomers, such as styrene. It is possible to generate free radicals by irradiation, in particular by UV irradiation, preferably in the presence of appropriate UV-sensitive initiators. It is possible to use initiators or initiator systems of radical or redox type.
• the source of free radicals may or may not be water-soluble. It may be preferable to use water-soluble initiators or at least partially water-soluble initiators.
• - peroxides such as: hydrogen peroxides, tert-butyl hydroperoxide, cumene hydroperoxide, tbutyl peroxyacetate, t-butyl peroxybenzoate, t-butyl peroxyoctoate, t-butyl peroxyneodecanoate, t-butyl peroxyisobutyrate, lauroyl peroxide, t-amyl peroxypivalate, tbutyl peroxy pivalate, dicumyl peroxide, benzoyl peroxide, potassium persulfate or ammonium persulfate,
• - azo compounds such as: 2,2’-azobisisobutyronitrile, 2,2’-azobis(2- butanenitrile), 4,4’- azobis(4-pentanoic acid), 1 ,T- azobis(cyclohexanecarbonitrile), 2-(t-butylazo)-2- cyanopropane, 2,2’- azobis ⁇ 2-methyl-N-[1 ,1-bis(hydroxymethyl)-2- hydroxyethyl]propionamide ⁇ , 2,2’-azobis[2-methyl-N- (hydroxyethyl)propionamide], 2,2’- azobis(N,N’- dimethyleneisobutyramidine) dihydrochloride, 2,2’-azobis(2- amidinopropane) dihydrochloride, 2,2’-azobis(N,N’- dimethyleneisobutyramide), 2,2’-azobis ⁇ 2-methyl-N-[1 ,1- bis(hydroxymethyl)-2-hydroxyethyl]propion
• - redox systems comprising combinations, such as: mixtures of hydrogen peroxide, alkyl peroxide, peresters, percarbonates and the like and of any iron salt, titanous salt, zinc formaldehydesulfoxylate or sodium formaldehydesulfoxylate, and reducing sugars, - alkali metal or ammonium persulfates, perborates or perchlorates, in combination with an alkali metal bisulfite, such as sodium metabisulfite, and reducing sugars, and
• the polymerization temperature can in particular be between 25°C and 95°C.
• the temperature can depend on the source of free radicals. If it is not a source of UV initiator type, it will be preferable to operate between 50°C and 95°C, more preferably between 60°C and 80°C. Generally, the higher the temperature, the more easily the polymerization is initiated (it is promoted) but the lower the molar masses of the copolymers obtained.
• a polymer (P) is obtained by radical polymerization of one monomer (AA), one monomer (AM), and one monomer (M) in the presence of a source of free radicals, in order to obtain a polymer comprising recurring units derived from monomer (AA,) recurring units derived from monomer (AM) and recurring units derived from monomer (M).
• Polymer (P) can also be prepared by any controlled radical polymerization. Among these, reversible addition-fragmentation chain transfer (RAFT) and macromolecular design via inter-exchange of xanthate (MADIX) can be mentioned.
• RAFT reversible addition-fragmentation chain transfer
• MADIX macromolecular design via inter-exchange of xanthate
• RAFT/MADIX agents RAFT or MADIX controlled radical polymerization agents, hereinafter referred to as “RAFT/MADIX agents”, has been disclosed for instance WO 98/058974 A (RHODIA CHIMIE) 30 Dec. 1998 and WO 98/01478 A (E.L DUPONT DE NEMOURS AND COMMONWEALTH SCIENTIFIC AND INDUSTRIAL RESEARCH ORGANIZATION) 15 Jan. 1998.
• the polymer (P) is obtained by radical copolymerization of a mixture having the following molar ratio, based on the total quantity of monomer (AA), monomer (AM) and monomer (M): monomer (AA): from 1 to 95%, notably from 5 to 50%, preferably from 20 to 40%, monomer (AM): from 1 to 90%, preferably from 25 to 90%, more preferably from 60 to 80%, monomer (M): from 0.1 to 50%, for example from 1 to 30%, notably from 1 to 20% and even 2 to 15%
• polymer (P) preferably comprises: from 1 to 95%, notably from 5 to 50%, preferably from 20 to 40% of recurring units derived from monomer (AA), from 1 to 90%, preferably from 25 to 90%, more preferably from 50 to 80% of recurring units derived from monomer (AM), and from 0.1 to 50%, for example from 1 to 30%, notably from 1 to 20% and even 2 to 15% of recurring units derived from monomer (M) all the aforementioned % by moles being referred to the total moles of recurring units of the polymer (P).
• polymer (P) comprises:
• the polymer (P) according to the invention preferably has a number average molecular weight (Mn) of at least 90 kDa, for example between 90 and 5000 kDa, preferably from 850 kDa to 2000 kDa.
• Mn number average molecular weight
• polymer (P) is a statistical (random) copolymer having a weight average molecular weight of about 100 kDa to 10000 kDa, preferably from 1000 kDa to 3000 kDa, which is obtained by radical polymerization of a mixture of monomer (AA), monomer (AM), and a monomer (M), preferably in a molar ratio of about:
• polymer (P) is a block copolymer obtained by controlled radical polymerization using RAFT/MADIX agents.
• block copolymer as used herein it is intended any controlled- architecture copolymer, including but not limited to true block polymers, which could be di- blocks, tri-blocks, or multi-blocks; branched block copolymers, also known as linear star polymers; comb; and gradient polymers.
• Gradient polymers are linear polymers whose composition changes gradually along the polymer chains, potentially ranging from a random to a block-like structure.
• Each block of the block copolymers may itself be a homopolymer, a random copolymer, a random terpolymer, or a gradient polymer.
• Polymer (P) can be provided in solid or dry form or in a vectorized form, for example in the form of a solution or of an emulsion or of a suspension, in particular in the form of an aqueous solution.
• the vectorized form for example an aqueous solution, can in particular comprise from 3 to 50% by weight of the polymer (P), for example from 5 to 30% by weight.
• the aqueous solution comprising polymer (P) can in particular be a solution obtained by an aqueous phase preparation process at the end of a radical polymerization process.
• polymer (P) comprises recurring units deriving from a monomer (AA), it may suitably be converted into its neutralized form polymer [polymer (P-N)], thus comprising the recurring units derived from the at least an a,p-ethylenically unsaturated carboxylic acid in a neutralized form.
• the present invention thus provides a polymer (P-N), said polymer consisting of:
• (A1) recurring units derived from an a,p-ethylenically unsaturated carboxylic acid monomer [monomer (AA)] in neutralized form;
• R 1 and R 2 being the same or different from each other, may be selected from a hydrogen atom, from a linear or branched alkyl group having 1 to 6 carbon atoms, a carboxylic group or an amide group,
• R 3 represents a hydrogen atom or a methyl group
• R 4 and R 5 being the same or different from each other, may be selected from a hydrogen atom or from a linear or branched alkyl group having 1 to 6 carbon atoms;
• (B) recurring units derived from at least one monomer (M), different from monomer (AA) and from monomer (AM), said monomer (M) having the formula (II) below: wherein:
• R' is selected from the group consisting of H, -COOH, -CH2COOH or an alkyl group, wherein the alkyl group is preferably a methyl group;
• R" and R iH being the same or different from each other, may be selected from a hydrogen atom or from a linear or branched alkyl group having 1 to 6 carbon atoms, or can be -COOH group;
• A is a linkage selected from the group consisting of a -C(O)-O- group or a -C(O)-NH- group;
• R x is selected from a hydrogen atom or a linear or branched C3-C20 hydrocarbon chain moiety comprising at least one functional groups selected from the group consisting of ether (-O-), heterocyclic group, sulfonic acid group (-SO3H), phosphonic acid group (-PO3H2) and phosphoric acid group (-OPO3H2).
• Polymer (P-N) can be prepared by neutralizing the acid groups of the recurring units derived from monomer (AA) of polymer (P) as above defined, wherein the neutralization of acid groups is carried out either with a salt [salt (S)] including a monovalent cation, preferably an alkaline metal salt, in a suitable solvent, or with ammonia.
• a salt [salt (S)] including a monovalent cation, preferably an alkaline metal salt preferably an alkaline metal salt
• the salt (S) can be any salt capable of neutralizing the acid groups.
• the salt (S) is a lithium salt selected from the group consisting of lithium carbonate, lithium hydroxide, lithium bicarbonate, and combinations thereof, preferably lithium carbonate.
• the lithium salt is free of lithium hydroxide.
• the solvent for use in the step of neutralization of polymer (P) can be any solvent capable of dissolving the salt (S) or ammonia and the resulting polymer (P-N).
• the solvent is selected from at least one of an aqueous solvent, such as water, NMP, and alcohols, such as, for example, methanol, isopropanol, and ethanol.
• the solvent is an aqueous solvent. Still more preferably the solvent is water.
• the content of the salt (S) in the solvent ranges from 0.5 to 10 wt. %, preferably from 1 to 5 wt. %, based on the total weight of the solvent and the salt (S).
• the concentration of the lithium salt in the solvent provides at least 0.25 eq, 0.5 eq, 0.8 eq, 1 eq, 1.5 eq, 2 eq, 2.5 eq, 3 eq, 4, eq of lithium to acid groups. In some embodiments, the concentration of the lithium salt in the solvent provides at most 5 eq, preferably at most 4, eq of lithium to acid groups.
• the polymer (P-N) comprises recurring units derived from the lithiated form of the at least one a,p-ethylenically unsaturated carboxylic acid monomer.
• the content of polymer (P-N) in the solution after neutralization, based on the total weight of the solvent and the polymer (P-N), ranges from 0.5 to 40 wt %, preferably from 2 to 30 wt %, more preferably 4 to 20 wt %.
• the polymer (P-N) can be isolated as a solid from the solution after neutralization and optionally stored for later use.
• the solid polymer (P-N) can also be dissolved (or re-dissolved) in water to prepare the electrodeforming composition described below.
• the solution including the polymer (P-N) after neutralization is an aqueous solution that can be used directly, optionally with further dilution with water, in preparing binder composition as described below.
• a lithium salt of polymer (P), namely polymer (P-Li) was prepared by adding an amount of LiOH to fully neutralize an aqueous solution containing about 10 wt. % polymer (P).
• the resulting solution had a pH in the range of 6.5 to 9 and contained approximately 10 wt. % of polymer (P-Li).
• the neutralized polymer solution has advantages in the processing and dispersing ability of the slurry because neutralized polymer shows increased viscosity.
• polymer (P-Li) has a pH more compatible with lithiated silicon types that usually show better performance if processed with slurry having a pH higher than 7.
• An additional advantage is that the salified form of the recurring units derived from the monomer (AA) can avoid sequestration of lithium ions by the free acid groups in the cell, which can diminish the first cycle coulombic efficiency and thus the initial capacity.
• the amount of polymer (P) which may be used in the electrode-forming composition (Comp) is subject to various factors.
• One such factor is the surface area and amount of the active material, and the surface area and amount of any electroconductivity-imparting additive which are added to the electrode-forming composition. These factors are believed to be important because the binder particles provide bridges between the conductor particles and conductive material particles, keeping them in contact.
• the electrode forming composition [composition (Comp)] of the present invention includes one or more electrode active material.
• electrode active material is intended to denote a compound that 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 electrode active material is preferably able to incorporate or insert and release lithium ions.
• the nature of the electrode active material in the electrode forming composition (Comp) of the invention depends on whether said composition is used in the manufacture of a negative electrode (anode) or a positive electrode (cathode).
• the electrode active material may comprise a composite metal chalcogenide of formula LiMGb, wherein M is at least one metal selected from transition metals such as Co, Ni, Fe, Mn, Cr and V 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
• Q is a chalcogen such as O or S.
• Preferred examples thereof may include LiCoOs, LiNiOs, LiNi x Coi-xO2 (0 ⁇ x ⁇ 1) and spinel-structured LiMn2O4.
• the electrode active material may comprise a lithiated or partially lithiated transition metal oxyanion-based electroactive material of formula MiM2(JO4)fEi-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, including 0, JO4 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 JO4 oxyanion, generally comprised between 0.75 and 1.
• the electrode active material in the case of forming a positive electrode has formula Li3- x M’ y M”2- y (JO4)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 electrode active material is a phosphate-based electro-active material of formula Li(Fe x Mni- x )PO4 wherein 0 ⁇ x ⁇ 1 , wherein x is preferably 1 (that is to say, lithium iron phosphate of formula LiFePC ).
• the electrode active material 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, or carbon black. These materials may be used alone or as a mixture of two or more thereof.
• 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, silicon oxide and lithiated silicon.
• the silicon-based compound may be silicon oxide or silicon carbide.
• the silicon-based compounds are comprised in an amount ranging from 1 to 70 % by weight, preferably from 5 to 30 % by weight with respect to the total weight of the electro active compounds.
• One or more optional electroconductivity-imparting additives may be added 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, 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 0.5 to 30 wt. % of the total amount of the solids within the composition.
• the electrode-forming composition of the invention can contain at least one thickener; when present, the amount of thickener (also designated as rheology modifier) is not particularly limited and generally ranges between 0.1 and 10 wt %, preferably between 0.5 and 5 wt %, with respect to the total weight of the composition (Comp).
• the thickener is generally added in order to prevent or slow down the settling of the powdery electrode material from the aqueous composition of the invention, while providing appropriate viscosity of the composition for a casting process.
• Non-limitative examples of suitable thickeners include, notably, organic thickeners such as carboxylated alkyl cellulose like carboxylated methyl cellulose and inorganic thickeners such as natural clays like montmorillonite and bentonite, manmade clays like laponite and others like silica and talc.
• the total solid content (TSC) of the composition (Comp) of the present invention is typically comprised between 15 and 70 wt. %, preferably from 40 to 60 wt. % over the total weight of the composition (Comp).
• the total solid content of the composition (Comp) is understood to be cumulative of all non-volatile ingredients thereof, notably including polymer (P), the electrode active material and any solid, non-volatile additional additive such as the thickener.
• composition (Comp)
• an amount of water sufficient to create a stable solution is employed.
• the amount of water used may range from the minimum amount needed to create a stable solution to an amount needed to achieve a desired total solid content in an electrode mixture after the active electrode material, optional conductive material, and other solid additives have been added.
• the electrode-forming composition (Comp) of the invention can be used in a process for the manufacture of an electrode [electrode (E)], said process comprising:
• step (iii) applying the composition (Comp) provided in step (ii) onto the at least one surface of the metal substrate provided in step (i), thereby providing an assembly comprising a metal substrate coated with said composition (Comp) onto the at least one surface;
• step (v) submitting the dried assembly obtained in step (iv) 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, aluminum, iron, stainless steel, nickel, titanium or silver.
• the electrode forming composition (Comp) is applied onto at least one surface of the metal substrate typically by any suitable procedures such as casting, printing and roll coating.
• step (iii) may be repeated, typically one or more times, by applying the electrode forming composition (Comp) provided in step (ii) onto the assembly provided in step (iv).
• drying may be performed either under atmospheric pressure or under vacuum.
• drying may be performed under modified atmosphere, e.g. under an inert gas, typically exempt notably from moisture (water vapour content of less than 0.001 % v/v).
• the drying temperature will be selected so as to effect removal by evaporation of the aqueous medium from the electrode (E) of the invention.
• step (v) the dried assembly obtained in step (iv) is submitted to a compression step such as a calendaring process, to achieve the target porosity and density of the electrode (E) of the invention.
• the dried assembly obtained at step (iv) is hot pressed, the temperature during the compression step being comprised from 25°C and 130°C, preferably being of about 60°C.
• Preferred target density for electrode (E) is comprised between 1.4 and 2 g/cc, preferably at least 1.55 g/cc.
• the density of electrode (E) is calculated as the sum of the product of the densities of the components of the electrode multiplied by their mass ratio in the electrode formulation.
• the present invention pertains to the electrode [electrode (E)] obtainable by the process of the invention.
• an electrode (E) comprising:
• composition directly adhered onto at least one surface of said metal substrate corresponds to the electrode forming composition (Comp) of the invention wherein the aqueous solvent has been at least partially removed during the manufacturing process of the electrode, for example in step (iv) (drying) and/or in the compression step (v). Therefore all the preferred embodiments described in relation to the electrode forming compositions (Comp) of the invention are also applicable to the composition directly adhered onto at least one surface of said metal substrate, in electrodes of the invention, except for the aqueous medium removed during the manufacturing process.
• the electrode (E) is a negative electrode. More preferably, the negative electrode comprises a silicon based electro active material.
• the present invention relates to a negative electrode comprising, based on the total weight of the electrode:
• the electrode (E) of the invention is particularly suitable for use in electrochemical devices, in particular in secondary batteries.
• 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.
• An electrochemical device according to the present invention can be prepared by standard methods known to a person skilled in the art.
• AM Acrylamide monomer (50% water solution) available from SNF; Itaconic acid available from Aldrich;
• MPEGMA750 (methoxy polyoxyethylene methacrlylate), available from Evonik, 50% in water under commercial name VISIOMER® MPEG 750 MA W;
• Transfer agent freshly prepared 1 % wt. solution in ethanol of RAFT-type transfer agent available as Rhodixan A1 from Solvay;
• V-50 initiator (2,2'-Azobis(2-methyl-propionamidine) dihydrochloride) available in powder form from Aldrich; (10% wt. water solution was prepared just before the polymerization experiment);
• Lithium hydroxide monohydrate (purity 98%) available from Sigma-Aldrich; (8% wt. water solution was prepared just before the polymerization experiment in case of the example P-1)
• Silicon oxide, KSC-1064 commercially available from Shin-Etsu, theoretical capacity is about 2100 mAh/g;
• SBR Styrene-Butadiene Rubber
• the reactor was equipped with a lid containing multiple entries into which were installed a small reflux system, a mechanical stirring system, a nitrogen purge line and a raw materials feed line.
• a first step all monomers, solvent (water) and optionally a transfer agent, were charged into the reactor and kept under stirring and nitrogen purging for around 1 hour at room temperature.
• the redox type initiator was added to the reaction mixture.
• the thermal initiator was also added at same time into the reaction mixture. The initiator was homogenized in the reaction mixture for few minutes with mechanical stirring, then the stirring and nitrogen purge were stopped.
• the mass distribution of the polymers was measured by SEC MALS analysis (SEC: Size Exclusion Chromatography - MALS: Multi-Angle Laser Scattering) in order to obtain the real values, expressed in g/mol.
• MALS detector Multi-Angle Laser Scattering
• Electrode-forming compositions and negative electrodes were prepared as detailed below using the following equipment:
• Mechanical mixer planetary mixer (Speedmixer) and high shear mechanical mixer of the Dispermat® series with inclined impeller; Film coater/doctor blade: Elcometer® 4340 motorised I Zehntner ZUA2000;
• Vacuum oven BINDER VD 23 with vacuum; and Roll press: precision 4" hot rolling press/calender up to 100°C.
• Example 1 - terpolymer anode 3% binder
• An aqueous composition was prepared by mixing 22.0 g of a 2% by weight solution of CMC, in water, 0.44 g of carbon black, 8.448 g of silicon oxide, 33.792 g of graphite and 17.790 g of deionized water. After moderate stirring in the planetary mixer for 10 min, 17.53 g of 5% solid content solution in water of polymer P-3 was added. The mixture was homogenized by moderate stirring in a planetary mixer for 10 min and then mixed again by moderate stirring for 1 h. After 1 h, the shear is reduced and the slurry mixed again by low stirring.
• a negative electrode was obtained by casting the binder composition thus obtained on a 18.5 pm thick copper foil with a doctor blade and drying the coating layer in an oven at temperature of 90°C for about 70 minutes. The thickness of the dried coating layer was about 60 pm. The electrode was then hot pressed at 60°C in a roll press to achieve target density of 1 .6 g/cc.
• the resulting negative electrode had the following composition: 19.2 wt.% of silicon oxide, 76.8 wt.% of graphite, 2 wt.% of Itaconic acid ( content 21.4% - id48), 1 wt.% of CMC and 1 wt. % of carbon black. Electrode E1 was thus obtained. Electrode quality is good enough for cell testing.
• An aqueous composition was prepared by mixing 22.0 g of a 2% by weight solution of CMC, in water, 0.44 g of carbon black, 8.448 g of silicon oxide, 33.792 g of graphite and 26.153 g of deionized water. After moderate stirring in the planetary mixer for 10 min, 9.167 g of 9.6% solid content solution in water of polymer P-6 was added. The mixture was homogenized by moderate stirring in a planetary mixer for 10 min and then mixed again by moderate stirring for 1 h. After 1 h, the shear is reduced and the slurry mixed again by low stirring.
• a negative electrode was obtained by casting the binder composition thus obtained on a 18.5 pm thick copper foil with a doctor blade and drying the coating layer in an oven at temperature of 90°C for about 70 minutes. The thickness of the dried coating layer was about 60 pm. The electrode was then hot pressed at 60°C in a roll press to achieve target density of 1.6 g/cc.
• the resulting negative electrode had the following composition: 19.2 wt.% of silicon oxide, 76.8 wt.% of graphite, 2 wt.% of Sipomer WAMII (content 2.5% - id56), 1 wt.% of CMC and 1 wt. % of carbon black. Electrode E2 was thus obtained. Electrode quality is good enough for cell testing.
• Example 3 - terpolymer anode 3% binder An aqueous composition was prepared by mixing 20.0 g of a 2% by weight solution of CMC, in water, 0.40 g of carbon black, 7.52 g of silicon oxide, 30.080 g of graphite and 10.127 g of deionized water. After moderate stirring in the planetary mixer for 10 min, 31.873 g of 5% solid content solution in water of polymer P-1 was added. The mixture was homogenized by moderate stirring in a planetary mixer for 10 min and then mixed again by moderate stirring for 1 h. After 1 h, the shear is reduced and the slurry mixed again by low stirring.
• a negative electrode was obtained by casting the binder composition thus obtained on a 18.5 pm thick copper foil with a doctor blade and drying the coating layer in an oven at temperature of 90°C for about 70 minutes. The thickness of the dried coating layer was about 60 pm. The electrode was then hot pressed at 60°C in a roll press to achieve target density of 1 .6 g/cc.
• the resulting negative electrode had the following composition: 18.8 wt.% of silicon oxide, 75.2 wt.% of graphite, 4 wt.% of AMPS (content 20% - id27), 1 wt.% of CMC and 1 wt. % of carbon black. Electrode E3 was thus obtained. Electrode quality is good enough for cell testing.
• Example 4 - terpolymer anode 3% binder
• An aqueous composition was prepared by mixing 20.0 g of a 2% by weight solution of CMC, in water, 0.40 g of carbon black, 7.52 g of silicon oxide, 30.080 g of graphite and 10.127 g of deionized water. After moderate stirring in the planetary mixer for 10 min, 31.873 g of 5% solid content solution in water of polymer P-2 was added. The mixture was homogenized by moderate stirring in a planetary mixer for 10 min and then mixed again by moderate stirring for 1 h. After 1 h, the shear is reduced and the slurry mixed again by low stirring.
• a negative electrode was obtained by casting the binder composition thus obtained on a 18.5 pm thick copper foil with a doctor blade and drying the coating layer in an oven at temperature of 90°C for about 70 minutes. The thickness of the dried coating layer was about 60 pm. The electrode was then hot pressed at 60°C in a roll press to achieve target density of 1 .6 g/cc.
• the resulting negative electrode had the following composition: 18.8 wt.% of silicon oxide, 75.2 wt.% of graphite, 4 wt.% of MPEGMa (content 10% - id30), 1 wt.% of CMC and 1 wt. % of carbon black. Electrode E4 was thus obtained. Electrode quality is good enough for cell testing.
• Comparative Example CE1 Negative Electrode Including Styrene- Butadiene Rubber (SBR) and Carboxymethyl Cellulose (CMC)
• An aqueous composition was prepared by mixing 25.0 g of a 2% by weight solution of CMC, in water, and 0.50 g of carbon black; after moderate stirring in planetary mixer for 10 min, 9.60 g of silicon oxide 38.4 g of graphite and 23.861 g of deionized water were added. The mixture was homogenized by moderate stirring in a planetary mixer for 10 min and then mixed again by moderate stirring for 1h.
• a negative electrode was obtained by casting the binder composition thus obtained on a 18.5 pm thick copper foil with a doctor blade and drying the coating layer in an oven at temperature of 90°C for about 70 minutes. The thickness of the dried coating layer was about 60 pm. The electrode was then hot pressed at 60°C in a roll press to achieve target density of 1.6 g/cc.
• the resulting negative electrode had the following composition: 19.2 wt.% of silicon oxide, 76.8 wt.% of graphite, 2 wt.% of SBR, 1 wt.% of CMC and 1 wt.% of carbon black. Electrode CE1 was thus obtained. Electrode quality is good enough for cell testing.
• Coin cells (CR2032 type, 20 mm diameter) were prepared in a glove box under an Ar gas atmosphere by punching a small disk of the negative electrode prepared according to E1 , E2, E3, E4 and CE1 together a balanced NMC positive electrode disk, purchased from CUSTOMCELLS.
• the electrolyte used in the preparation of the coin cells was a mixture of 1M LiPF6 solution in EC/DMC 1/1 v/v with 2% wt VC and 10% wt F1 EC, from Solvionic; polyethylene separators (commercially available from Tonen Chemical Corporation) were used as received.

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