Aqueous polymer composition for dispersing carbon-based material

Abstract

The invention relates to a process for preparing a component of a rechargeable battery, wherein a composition comprising a) water, b) an electrically conductive carbon-based material, and c) a polymer comprising repeating units of polymerized monomers of i) a vinyl aromatic monomer, ii) a polyether acrylate or polyether methacrylate, and iii) an ethylenically unsaturated monomer having 1 or 2 carboxylic acid groups, wherein at least a part of the carboxylic acid groups is present in salt form, is employed for preparing the component.

Description

[0001] AQUEOUS POLYMER COMPOSITION FOR DISPERSING CARBON-BASED MATERIAL

[0002] The invention relates to a process for preparing a component of a rechargeable battery, to the use of a composition comprising water and a polymer as a dispersing agent for an electrically conductive carbon-based material for a rechargeable battery, and to a rechargeable battery.

[0003] International patent application WO 2022 / 248318 A1 relates to compositions for painting and / or coating containing particular copolymer dispersants. The compositions comprise a copolymer obtainable by polymerization of at least one acrylic monomer, at least one hydrophobic non-acrylic monomer, and at least one (C1-C12) alkoxy polyethylene glycol (meth)acrylate.

[0004] United States patent application US 2006 / 0074002 A1 describes partially esterified copolymers of mono-ethylenically unsaturated dicarboxylic anhydrides, vinyl aromatic compounds, and further non-ethylenically unsaturated monomers containing heteroatoms. The polymers are used as additive for detergents and cleaners.

[0005] Japanese patent application JP 2007 261911 A relates to a slurry composition for producing ceramics, and more particularly to a slurry composition for producing ceramics useful for the production of ceramic electronic parts such as ceramic capacitors, varistors, thermistors, dielectric filters and sensors. The slurry comprises a dispersant, which is a copolymer of polyoxyalkylene alkyl ether, maleic anhydride, and styrene.

[0006] There is an ongoing need for improved processes for preparing components for rechargeable batteries. Current processes for preparing components for rechargeable batteries often use non-aqueous liquid compositions based on organic solvents. The use of organic solvents in such processes is undesirable in view of fire risks, industrial hygiene risks, and undesirable health effects associated with organic solvents. Hence, there is a desire to use aqueous compositions in such processes. Compositions for preparing components for rechargeable batteries often comprise particles of an electrically conductive carbon-based material in dispersed form. It is important that such particles are and remain well dispersed. Poor particles dispersion often manifests itself in a high viscosity of the dispersion. High viscosity compositions are undesirable, because they are difficult to handle and require additional diluent to achieve the required viscosity. Moreover, a too high viscosity of such dispersion signals inadequate and uneven dispersion of the particles of electrically conductive carbon-based material. In addition to the handling properties mentioned above, inadequate and uneven dispersion detracts from the quality of the battery components prepared form such compositions. The present invention addresses the above-mentioned problems.

[0007] The invention provides a process for preparing a component of a rechargeable battery, wherein a composition comprising a) water, b) an electrically conductive carbon-based material, and c) a polymer comprising repeating units of polymerized monomers of i) a vinyl aromatic monomer, ii) a polyether acrylate or polyether methacrylate, and iii) an ethylenically unsaturated monomer having 1 or 2 carboxylic acid groups, wherein at least a part of the carboxylic acid groups is present in salt form, is employed for preparing the component.

[0008] The process of the invention alleviates or eliminates the drawbacks mentioned above.

[0009] The process of the invention relates to a process for preparing a component of a rechargeable battery. The rechargeable battery in a preferred embodiment of the present invention is described by taking a lithium-ion rechargeable battery as a specific example. The lithium-ion rechargeable battery has a structure in which an anode and a cathode are soaked in an electrolyte. In a lithium-ion rechargeable battery, a separator may be provided between a cathode and anode. Examples of the separator include non-woven fabric, cloth, and a microporous film each mainly containing polyolefin such as polyethylene and polypropylene, a combination thereof, and the like.

[0010] As an electrolyte forming the lithium-ion rechargeable battery in a preferred embodiment of the present invention, a known organic electrolyte, inorganic solid electrolyte, and polymer solid electrolyte may be used. In the process of the invention a composition is employed for preparing the component of a rechargeable battery. The composition comprises a) water, b) an electrically conductive carbon-based material, and c) a polymer comprising repeating units of polymerized monomers of i) a vinyl aromatic monomer, ii) a polyether acrylate or polyether methacrylate, and iii) an ethylenically unsaturated monomer having 1 or 2 carboxylic acid groups, wherein at least a part of the carboxylic acid groups is present in salt form.

[0011] The composition comprises water. Water is present as liquid diluent to render the composition liquid or paste-like. In typical embodiments, water is present in the composition in an amount of 95 to 30 % by weight, calculated on the total weight of the composition. In preferred embodiments, water is present in the composition in amount of 90 to 40 % by weight. When the water content is very high, the viscosity of the composition may become too low and evaporation of water after application of the composition may take too long. When the water content is very low, the viscosity of the composition may become too high to bring the composition into a required shape for a component of a rechargeable battery.

[0012] Water is generally the main liquid diluent in the composition. In some embodiments, the composition may additionally comprise one or more organic liquid diluents, also referred to as organic solvents. If such organic solvents are present, it is preferred to use water-miscible organic solvents. In view of solvent emissions and industrial hygiene is preferred that the composition comprises a low amount of organic solvent. That denotes a composition suitably comprising organic solvent in an amount from 0.0 and to 15.0 % by weight, preferably 0.0 to 10.0 % by weight of volatile organic solvent, more preferably 0.0 to 7.0 % by weight of volatile organic solvent, calculated on the total weight of the composition.

[0013] The optional organic solvent may also comprise more than one type of organic solvent, for example a mixture of two or more types of solvents. Examples of suitable solvents include ester solvents, such as methyl acetate, ethyl acetate, butyl butyrate, y-butyrolactone, and E- caprolactone; or a carbonate-based solvent such as dimethyl carbonate (DMC), diethyl carbonate (DEC), methylethyl carbonate (MEC), ethylmethyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); an alcohol-based solvent such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R is a linear, branched, or cyclic C2-C20 hydrocarbon group and may include a double-bond aromatic ring or ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes may be used as the organic solvent. Examples of further suitable solvents include aprotic dipolar solvents, such as dimethyl sulfoxide, dimethyl formamide or N-methyl pyrrolidone, or other solvents comprising an amide group.

[0014] In further preferred embodiments, the polymer c) is dissolved in the water, or in the aqueous liquid phase of the composition. When the polymer is dissolved in water or in the aqueous liquid phase of the composition, the polymer and the water form a continuous homogenous single phase, as opposed to an aqueous dispersion or emulsion, wherein the polymer would be present as a non-continuous phase in the form of solid or liquid particles.

[0015] The composition further comprises an electrically conductive-carbon-based material. A carbon-based material is a material which consists for 90 to 100 % by weight of carbon. For use in the field of component manufacture for batteries, a carbon-based material is selected which is electrically conductive. The electrically conductive carbon-based material is present in the composition in the form of solid particles. In preferred embodiments, the electrically conductive carbon-based material comprises at least one of carbon nano tubes, carbon black, graphene, fullerene, and carbon fibers. Carbon nano tubes are particularly preferred.

[0016] A carbon nano tube (CNT) is a tube made of carbon with a diameter in the nanometer range. They are one of the allotropes of carbon. Single-walled carbon nano tubes have diameters around 0.5-2.0 nanometers. They can be idealized as cutouts from a two-dimensional graphene sheet rolled up to form a hollow cylinder.

[0017] Multi -walled carbon nano tubes consist of nested single-wall carbon nano tubes in a nested, tube-in-tube structure. Double- and triple-walled carbon nano tubes are special cases of multi-walled carbon nano tubes.

[0018] The composition further comprises a polymer comprising repeating units of polymerized monomers of i) a vinyl aromatic monomer, ii) a polyether acrylate or polyether methacrylate, and iii) an ethylenically unsaturated monomer having 1 or 2 carboxylic acid groups, wherein at least a part of the carboxylic acid groups is present in salt form. The polymer in the composition acts as dispersing agent for the electrically conductive- carbon-based material.

[0019] The polymer comprises repeating units of a polymerized vinyl aromatic monomer.

[0020] Vinyl aromatic monomers are monomers having a polymerizable olefinically unsaturated group and an aromatic group. Preferably, the polymerizable olefinically unsaturated group is in conjugation with the aromatic group. In some embodiments, the vinyl aromatic monomer is a hydrocarbon monomer, such as styrene and various isomeric methyl styrenes, such as 2- methyl styrene, 3-methyl styrene, 4-methyl styrene, alpha-methyl styrene, and beta-methyl styrene. Analogous isomers of dimethyl styrene and trimethyl styrene can be used as well.

[0021] In some embodiments, the vinyl aromatic monomer comprises one or more of an ether group and hydroxyl group. Examples of such monomers include p-coumaryl alcohol, coniferyl alcohol, sinapyl alcohol, 4-vinyl phenol, 4-vinyl guaiacol, and 4-vinyl syringol.

[0022] Styrene is readily available on a commercial scale and provides good properties to the polymer as dispersing agent. Therefore, styrene is a preferred vinyl aromatic monomer.

[0023] It is preferred that the vinyl aromatic monomer does not comprise carboxylic acid groups.

[0024] The polymer comprises repeating units of polymerized monomers of i) a vinyl aromatic monomer in an amount of 50 to 90 mol-%, preferably 55 to 85 mol-%, wherein the mol-% are calculated on the total number of moles of polymerized monomers. Within these ranges a very good balance of properties of the polymer is obtained, in particular the polymer acts as an efficient dispersant for electrically conductive carbon-based materials and also has a sufficient solubility in water.

[0025] Furthermore, the polymer comprises repeating units of a polymerized polyether acrylate or polyether methacrylate monomer.

[0026] Such repeating units are suitably provided by monomers of the following formula (I) wherein

[0027] R1represents H or CH3,

[0028] Rarepresents a linear or branched alkylene group with 2 to 6 carbon atoms,

[0029] Rbrepresents aralkyl, preferably benzyl; or alkyl with 1 to 8 carbon atoms, preferably methyl, ethyl, propyl or butyl; or H, and n represents an integer from 1 to 150, preferably 1 to 50, more preferably 1 to 25, and in case at least two different types of residue Raare present the n [RaO] units, the [RaO]nchain may have a random, block or gradient architecture along the chain.

[0030] Examples of suitable monomers include (meth)acrylic acid esters of polyether monoalcohols, such as ethers, polyethylene glycols, polypropylene glycols, polybutylene glycols or mixed polyalkylene glycols having 4 to 80 carbon atoms and a statistical, a block or a gradient distribution of the different monomers along the chain, such as, for example, di(ethylene glycol) methyl ether (meth)acrylate, 2-butoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, methyltriglycol (meth)acrylate, ethyltriglycol (meth)acrylate, butyldiglycol (meth)acrylate, polypropylene glycol) methyl ether (meth)acrylate and poly(ethylene glycol) alkyl ether (meth)acrylate, wherein alkyl stands for a straight-chain or branched alkyl residue having 1 to 22, preferably 1 to 15, more preferably 1 to 13, even more preferably 1 to 10 carbon atoms and most preferable 1 to 7 carbon atoms.

[0031] In preferred embodiments, the polyether acrylate or polyether methacrylate comprises polymerized units of at least one of ethylene oxide and propylene oxide. The presence of polymerized units of ethylene oxide, optionally combined with polymerized units of propylene oxide, increases the water-solubility of the polymer.

[0032] In preferred embodiments, the polyether acrylate or polyether methacrylate comprises 3 to 50, more preferably 4 to 35 non-cyclic ether groups.

[0033] Suitably, the polyether of the polyether acrylate or polyether methacrylate is terminated by a hydroxyl group or by a hydrocarbyl group.

[0034] In typical embodiments, 20 to 80 %, preferably 30 to 70 % by weight of the repeating units of the polymer c) are based on the polyether acrylate or polyether methacrylate described above.

[0035] In a further embodiment, 5 to 45 mol-%, preferably 10 to 35 mol-% of the repeating units of the polymer c) are based on a polyether acrylate or polyether methacrylate, wherein the mol- % are calculated on the total number of moles of polymerized monomers. Furthermore, the polymer comprises repeating units of a polymerized ethylenically unsaturated monomer having 1 or 2 carboxylic acid groups, wherein at least a part of the carboxylic acid groups is present in salt form.

[0036] Examples of suitable ethylenically unsaturated monomers having one carboxylic acid group are acrylic acid and methacrylic acid. Other examples include 2-phenyl acrylic acid and 3- phenyl acrylic acid, as well as 2 or 3-alkyl acrylic acid, wherein the alkyl group has 2 to 6 carbon atoms.

[0037] Ethylenically unsaturated monomers having 2 carboxylic acid groups are maleic acid, fumaric acid, itaconic acid, citraconic acid, and mesaconic acid. Instead of the dicarboxylic acids mentioned above, it is also possible to use the corresponding cyclic anhydrides in the polymerization process and to subsequently hydrolyze the anhydride groups.

[0038] In view of commercial availability and good dispersant properties of the resulting polymers it is preferred that the ethylenically unsaturated monomer having 1 or 2 carboxylic acid groups comprises at least one of maleic acid, acrylic acid, and methacrylic acid.

[0039] It is preferred that the ethylenically unsaturated monomer having 1 or 2 carboxylic acid groups does not comprise aromatic groups.

[0040] At least a part of the carboxylic acid groups in the polymer are present in the form of a salt.

[0041] In typical embodiments, the salt is an alkali metal salt or an ammonium salt. In preferred embodiments, the salt is a sodium salt or the salt of ammonia or an amine having 1 to 18 carbon atoms. The amine can be a primary, secondary or tertiary amine.

[0042] In typical embodiments polymer c) comprises repeating units of polymerized monomers of an ethylenically unsaturated monomer having 1 or 2 carboxylic acid groups in an amount of 5 to 45 mol-%, preferably 10 to 35 mol-%, wherein the mol-% are calculated on the total number of moles of polymerized monomers.

[0043] Due to the presence of repeating units of polymerized monomers of an ethylenically unsaturated monomer having 1 or 2 carboxylic acid groups the polymer c) has carboxylic acid groups. The amount of carboxylic acid groups can be determined by titration. The acid number is the KOH quantity in mg that is required for neutralizing 1 g of substance. The acid numbers are suitably determined by a neutralization reaction with a 0.1 N KOH in Ethanol according to DIN EN ISO 2114. In preferred embodiments, the polymer has an acid number in the range of 30 to 180 mg KOH / g, more preferably 50 to 160 mg KOH / g. The mentioned acid numbers refer to the total number of acid groups of the polymer, including neutralized acid groups which are present in salt form.

[0044] Suitably, the polymer c) has a number average molecular weight in the range of 1500 to 30000 g / mol, preferably in the range of 2000 to 20000 g / mol, or 2000 to 15000 g / mol.

[0045] The weight average molecular weight of the polymer can suitably be determined by gel permeation chromatography (GPC), using polystyrene as calibration standard and THF as eluent.

[0046] In a preferred embodiment polymer c) comprises repeating units of polymerized monomers of i) a vinyl aromatic monomer in an amount of 50 to 90 mol-%, ii) a polyether acrylate or polyether methacrylate in an amount of 5 to 45 mol-%, and iii) an ethylenically unsaturated monomer having 1 or 2 carboxylic acid groups in an amount of 5 to 45 mol-%, wherein the mol-% are calculated on the total number of moles of polymerized monomers.

[0047] In a further preferred embodiment polymer c) comprises repeating units of polymerized monomers of i) a vinyl aromatic monomer in an amount of 50 to 80 mol-%, ii) a polyether acrylate or polyether methacrylate in an amount of 10 to 40 mol-%, and iii) an ethylenically unsaturated monomer having 1 or 2 carboxylic acid groups in an amount of 10 to 40 mol-%, wherein the mol-% are calculated on the total number of moles of polymerized monomers

[0048] The repeating units of polymerized monomers i), ii), and iii) in polymer c) may be present in random order or in the form of blocks of repeating units of one type of monomer. It is preferred, that the repeating units are present in random order.

[0049] In some embodiments, the polymer consists of the repeating units of polymerized monomers i), ii), and iii) as described above. However, it is also possible to include small amounts of other monomers in the polymer. Generally, other monomers are present in an amount of 0 to 10 mol-% of the repeating units. Optional other monomers include (meth)acrylic esters of straight-chain, branched or cycloaliphatic alcohols having 1 to 22, preferably 1 to 12, more preferably 1 to 8 and most preferably 1 to 6 carbon atoms. Further optional monomers include ethylenically unsaturated polymerizable compounds having an amide group, such as acrylic amide and methacrylic amide, as well as N-substituted derivatives thereof. For use in the process for preparing a component of a rechargeable battery the composition suitably further comprises an organic polymeric binder, which is different from polymer c).

[0050] The binder improves the adhesion between the components and any surfaces to which the composition is applied, such as a current collector, or any other component of an electrochemical device. Examples of the binder include known binders such as: fluorinebased polymers such as polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, and polytetrafluoroethylene; rubber-based binders such as styrene-butadiene rubber (SBR), nitril-butadiene rubber (NBR), hydrogenated nitrile-butadiene rubber (HNBR), ethylene-propylene-diene monomer rubber (EPDM), a sulfonated EPDM, and a fluorine rubber; polyethylene; polypropylene; polyvinyl alcohol; polyvinylpyrrolidone, polyacrylonitrile; carboxymethyl cellulose (CMC); starch; hydroxypropyl cellulose; regenerated cellulose; and binders based on polyacrylates such as poly(acrylic acid) (PAA). If so desired, the binder may be used in the form of an aqueous dispersion.

[0051] A suitable use amount of the binder is 1.0 to 50.0 parts by mass in terms of 100 parts by mass of the non-volatile material of the composition, and in particular, the used amount is preferably about 1.0 to 20.0, more preferably 1.0 to 10.0 parts by mass.

[0052] The organic polymeric binder is suitably present in the form of an aqueous solution, dispersion or emulsion.

[0053] As mentioned above, the invention relates to a process for preparing a component of a rechargeable battery.

[0054] In preferred embodiments, the component of the rechargeable battery is an anode or a cathode.

[0055] If the component is a cathode, the composition, suitably also comprises a cathode-active material. A transition metal oxide containing lithium, or a lithium metal phosphate, such as LiFePO4, is generally used as a cathode-active material, and preferably, an oxide mainly containing lithium and at least one kind of transition metal element selected from the group consisting of Ti, V, Cr, Mn, Fe, Co, Ni, Mo, and W.

[0056] In particularly preferred embodiments, the component of the rechargeable battery is an anode. In some embodiments, the anode is a silicon containing anode.

[0057] An electrode may be formed of a molding of the above-mentioned composition for an electrode. For this purpose, the composition may be in the form of a paste. The electrode is obtained, for example, by applying the paste for an electrode to a current collector, followed by drying and pressure molding.

[0058] Examples of the current collector include foils and mesh of aluminum, nickel, copper, stainless steel and the like. The coating thickness of the paste is generally 40 to 200 pm. There is no particular limitation to the paste coating method, and an example of the coating method includes a method involving coating with a doctor blade or a bar coater, followed by molding with roll pressing or the like. Examples of the pressure molding include roll pressure molding, compression molding, and the like.

[0059] In a further preferred embodiment of the process of the invention, the component of the rechargeable battery is a current collector of an anode or cathode, preferably a current collector of an anode. A current collector of an anode preferably consists of copper. A current collector of a cathode preferably consists of aluminum.

[0060] In this embodiment, the composition is applied as a primer coating to the current collector. The primer is suitably applied to the current collector in a layer thickness of 1 to 10 micrometer. The primer layer is an intermediate layer between the current collector and the active electrode material.

[0061] In typical embodiments, the primer layer comprises or consists of an electrically conductive carbon-based material, a polymer comprising repeating units of polymerized monomers of i) a vinyl aromatic monomer, ii) a polyether acrylate or polyether methacrylate, and iii) an ethylenically unsaturated monomer having 1 or 2 carboxylic acid groups, wherein at least a part of the carboxylic acid groups is present in salt form, and a polymeric binder, which is different from the aforementioned polymer. Examples of suitable binders are carboxymethyl cellulose, styrene-butadiene rubber, polyacrylic acid, as well as combinations thereof.

[0062] The primer layer reduces the electrical resistance between the current collector and the active electrode material, improves the adhesion of the active electrode material to the current collector, and provides corrosion protection of the current collector.

[0063] As mentioned above, the polymer present in the composition is very suitable for dispersing an electrically conductive carbon-based material in an aqueous composition. Therefore, the invention also relates to the use of a composition comprising water and a polymer comprising repeating units of polymerized monomers of i) a vinyl aromatic monomer, ii) a polyether acrylate or polyether methacrylate, and iii) an ethylenically unsaturated monomer having 1 or 2 carboxylic acid groups, wherein at least a part of the carboxylic acid groups is present in salt form, as a dispersing agent for an electrically conductive carbon-based material for a rechargeable battery.

[0064] In a further embodiment, the invention relates to a rechargeable battery comprising an electrically conductive carbon-based material and a polymer comprising repeating units of polymerized monomers of i) a vinyl aromatic monomer, ii) a polyether acrylate or polyether methacrylate, and iii) an ethylenically unsaturated monomer having 1 or 2 carboxylic acid groups, wherein at least a part of the carboxylic acid groups is present in salt form.

[0065] Examples

[0066] Raw materials an abbreviations

[0067] Alpha-MSD: a-methyl styrene dimer

[0068] MPEG500MA: methacrylate of polyethylene glycol mono-methylether having a number average molecular weight of 500 g / mol

[0069] MPEG750MA: methacrylate of polyethylene glycol mono-methylether having a number average molecular weight of 750 g / mol

[0070] MPEG1000MA: methacrylate of polyethylene glycol mono-methylether having a number average molecular weight of 1000 g / mol

[0071] C18-PEG1105MA: methacrylate of polyethylene glycol mono-stearylether having a number average molecular weight of 1105 g / mol

[0072] AIVN: 2,2'-Azobisisovaleronitrile

[0073] Trigonox®21S (tert-Butyl peroxy-2-ethylhexanoate)

[0074] Comparative Example 1: aqueous polymer solution with neutralized carboxylic acid groups

[0075] Comparative Example 2: Polyvinylpyrrolidon Comparative Example 3: cationic polyether-modified styrene maleic anhydride copolymer Comparative Example 4: Polyether modified epoxy amine addition product

[0076] Comparative Example 5: Aqueous solution of polyether-modified styrene maleic anhydride copolymer

[0077] Comparative Example 6 Carboxymethylcellulose

[0078] Preparation of Polymers

[0079] Example 1

[0080] 24.38 g Methoxypropylacetate and 1.57 g (0.0066 mol) alpha-MSD were added in a 4-neck flask and heated up to 130°C. 12.00 g (0.1152 mol) styrene, 14.40 g (0.0288 mol) MPEG500MA and 6.00 g methoxypropylacetate were mixed and dosed over a period of 2 h. Simultaneously, the dosing of a mixture of 2.82 g (0.0288 mol) maleic anhydride, 14.78 g methoxypropylacetate and 0.87 g (0.0053mol) AIVN was started and dosed over a period of 2.5 h. When dosing was complete, the mixture was kept at 130 °C for one more h. Subsequently, a mixture of 3 g methoxypropylacetate and 0.44 g (0.027 mol) AIVN was dosed over a period of 0.5 h. The mixture was kept at 130 °C for 1 more h. The acid number of the polymer was 100 mg KOH / g. Mn (GPC): 2815 g / mol

[0081] The polymer solution was cooled to 40°C, and 132 g water was added. Then 8.85 g (0.0473 mol KOH) 30 % aqueous potassium hydroxide solution was added. The mixture was stirred for 0.5 h and subsequently heated up to 100°C. Methoxypropylacetate and water was distilled off, and the removed amount was replaced by water until no more methoxypropylacetate was distilled off. The final non-volatile content of the aqueous polymer solution was 20 % by weight.

[0082] Example 2

[0083] The polymer of Example 2 was prepared analogously to Example 1. Raw materials and properties are summarized below.

[0084] 24.38 g Methoxypropylacetat and

[0085] 1.57 g (0.0066 mol) alpha-MSD 12 g (0.1152 mol) Styrene

[0086] 14.4 g (0.0288mol) MPEG500MA

[0087] 6 g Methoxypropylacetate.

[0088] 2.82 g (0.0288mol) Maleic Acid Anhydride

[0089] 14.78 g Methoxypropylacetate

[0090] 0.87 g (0.0053 mol) AIVN

[0091] 3 g Methoxypropylacetate

[0092] 0.44 g (0.027 mol) AIVN

[0093] Acid number 100 mg KOH / g, Mn 3279 g / mol

[0094] 130.87 g Water

[0095] 5.74 g (0.0473 mol) 33 % aqueous sodium hydroxide solution.

[0096] The final non-volatile content of the aqueous polymer solution was 20 % by weight.

[0097] Example 3

[0098] The polymer of Example 3 was prepared analogously to Example 1. Raw materials and properties are summarized below.

[0099] 16.32 g Methoxypropylacetat

[0100] 1.35 g (0.0057 mol) alpha-MSD

[0101] 10.32 g (0.0991 mol) Styrene

[0102] 24.77 g (0.0248 mol) MPEG1000MA 20.64 g Methoxypropylacetate

[0103] 2.43 g (0.0248 mol Maleic Anhydride,

[0104] 12.72 g Methoxypropylacetate

[0105] 0.75 g (0 0046 mol) AIVN

[0106] 10.32 g Methoxypropylacetate

[0107] 0.38 g (0.0023 mol) AIVN

[0108] Acid number is 62.5 mgKOH / g. Mn: 4082 g / mol

[0109] 57 g water

[0110] 9.27 g (0.0496 mol) 30 % potassium hydroxide solution

[0111] The final non-volatile content of the aqueous polymer solution was 40 % by weight.

[0112] Example 4

[0113] The polymer of Example 4 was prepared analogously to Example 1. Raw materials and properties are summarized below.

[0114] 12.22 g Methoxypropylacetat

[0115] 1.28 g (0.0054mol) alpha-MSD

[0116] 9.78 g (0.0939 mol) Styrene,

[0117] 17.61 g (0.0235 mol) MPEG750MA

[0118] 7.82 g Methoxypropylacetate

[0119] 2.3 g (0.0235 mol) Maleic Anhydride,

[0120] 24.1 g Methoxypropylacetate

[0121] 0.71 g (0.0043 mol) AIVN

[0122] 3.91 g Methoxypropylacetate 0.36 g (0.0022 mol) AIVN

[0123] Acid number was 72.5 mg KOH / g. Mn: 2853 g / mol

[0124] 138.5 g Water

[0125] 8.77 g (0.0469 mol) 30 % potassium hydroxide

[0126] The final non-volatile content of the aqueous polymer solution was 20 % by weight.

[0127] Example 5

[0128] The polymer of Example 5 was prepared analogously to Example 1 . Raw materials and properties are summarized below.

[0129] 51.11 g Methoxypropylacetat

[0130] 3.49 g (0.0148 mol) alpha-MSD

[0131] 20.0 g (0.192 mol) Styrene,

[0132] 64.01 g (0.128 mol) MPEG500MA

[0133] 10 g Methoxypropylacetate

[0134] 6.27 g (0.064 mol) Maleic Anhydride,

[0135] 73.92 g Methoxypropylacetate

[0136] 1.94 g (0.0118 mol) AIVN

[0137] 10 g Methoxy propyl acetate

[0138] 0.97 g (0.0059 mol) AIVN

[0139] Acid number was 66.5 mg KOH / g. Mn: 3187 g / mol

[0140] 398.7 g Water

[0141] 23.9 g (0.128 mol) 30 % potassium hydroxide

[0142] The final non-volatile content of the aqueous polymer solution was 20 % by weight. Example 6

[0143] The polymer of Example 6 was prepared analogously to Example 1. Raw materials and properties are summarized below.

[0144] 39.7 g Methoxypropylacetat

[0145] 40.0 g (0.384 mol) Styrene,

[0146] 48.1 g (0.096 mol) MPEG500MA,

[0147] 9.41 g (0.096 mol) Maleic Anhydride

[0148] 19.48 g Methoxypropylacetate

[0149] 77.93 g Methoxypropylacetate

[0150] 2.92 g (0.0177 mol) AIVN

[0151] 5.59 g Methoxypropylacetate

[0152] 1.46 g (0.0089 mol) AIVN

[0153] Acid number was 100 mgKOH / g. Mn: 4326 g / mol

[0154] 425.15 g Water

[0155] 35.88 g (0.192 mol) 30 % potassium hydroxide solution

[0156] The final non-volatile content of the aqueous polymer solution was 20 % by weight.

[0157] Comparative Example 7

[0158] The polymer of Comparative Example 7 was prepared analogously to Example 1. Raw materials and properties are summarized below.

[0159] 44.39 g Methoxypropylacetate

[0160] 3.84 g (0.0112 mol) alpha-MSD 33. 0 g (0.3169 mol) Styrene,

[0161] 105.62 g (0.1056 mol) MPEG1000MA,

[0162] 34.32 g Methoxypropylacetate

[0163] 1.14 g (0.007mol) AIVN

[0164] 2.86 g Methoxypropylacetate

[0165] 0.29 g (0.0017 mol) AIVN

[0166] 7.04 g Methoxypropylacetate

[0167] 0.7g (0.0043mol) AIVN

[0168] Acid number was 0 mg KOH / g. Mn: 4598 g / mol

[0169] 220.0 g Water

[0170] The final non-volatile content of the aqueous polymer solution was 30 % by weight.

[0171] Example 7

[0172] The polymer of Example 7 was prepared analogously to Example 1. Raw materials and properties are summarized below.

[0173] 48.32 g Methoxypropylacetate

[0174] 6.55 g (0.0277 mol) alpha-MSD

[0175] 50 g (0.48 mol) Styrene,

[0176] 67.69 g (0.12 mol) MPEG500MA,

[0177] 24.38 g Methoxypropylacetate,

[0178] 10.33 g (0.12 mol) Methacrylic Acid

[0179] 2.44 g (0.0148 mol) AIVN 12.1 g Methoxypropylacetate

[0180] 1.2 g (0.0073 mol) AIVN

[0181] Acid number was 55 mgKOH / g. Mn: 5049 g / mol

[0182] 323.9 g Water

[0183] 14.45 g (0.12 mol) 33 % sodium hydroxide solution

[0184] The final non-volatile content of the aqueous polymer solution was 30 % by weight.

[0185] Example 8

[0186] The polymer of Example 8 was prepared analogously to Example 1. Raw materials and properties are summarized below.

[0187] 24.38 g Methoxypropylacetate

[0188] 1.57 g (0.0066 mol) alpha-MSD

[0189] 12 g (0.1152 mol) Styrene

[0190] 14.4 g (0.0288 mol) MPEG500MA

[0191] 6 g Methoxypropylacetate

[0192] 2.82 g (0.0288 mol) Maleic Anhydride,

[0193] 14.78 g Methoxypropylacetate

[0194] 0.87 g (0.0053 mol) AIVN

[0195] 3 g Methoxypropylacetate

[0196] 0.44 g (0 027 mol) AIVN

[0197] Acid number was 100 mg KOH / g. Mn: 3279 g / mol

[0198] 130.87 g Water

[0199] 2.87 g (0.0237 mol) 33 % sodium hydroxide

[0200] The final non-volatile content of the aqueous polymer solution was 20 % by weight. Example 9

[0201] The polymer of Example 9 was prepared analogously to Example 1. Raw materials and properties are summarized below.

[0202] 51.46 g Methoxypropylacetate

[0203] 4.58 g (0.0194 mol) alpha-MSD

[0204] 30.0 g (0.3899 mol) Styrene,

[0205] 40.61 g (0.0720 mol) MPEG500MA,

[0206] 10.38 g (0.1440 mol) acrylic acid

[0207] 1.71 g (0.0077 mol) Trigonox 21S

[0208] 1.71 g Methoxypropylacetate

[0209] 1.71 g (0.0077 mol) of Trigonox 21S

[0210] 1.71 g of Methoxypropylacetate

[0211] Acid number was 102 mg KOH / g. Mn: 4583 g / mol

[0212] 48.88 g Water

[0213] 17.96 g (0.1483 mol) 33 % Sodium hydroxide solution

[0214] The final non-volatile content of the aqueous polymer solution was 20 % by weight.

[0215] Preparation of compositions comprising electrically conductive carbon-based material

[0216] In a 100 ml glass bottle 0.4 g of the respective polymer, 18.3 g of demineralized water, 0.8 g of carbon nanotubes (Cnano FT7320), 0.1 g defoamer (BYK-024) and 60 g of zirconiumoxide beads (1.0 mm) were added. Dispersion was carried out using a LAU-Disperser DAS 200 for 720 minutes at cooling level 3 followed by sieving-off the zirconium-oxide beads.

[0217] Finally, the slurries were evaluated by measurement of the viscosity on an Anton Paar MCR 102 at 23°C in cone / plate geometry (25 1°). The results are summarized in the Table below.

[0218] It can be concluded that the compositions according to the invention have a significantly lower viscosity than the composition with Comparative Example 1. The composition of Comparative Example 1 has a too high viscosity for being used in the preparation of a component for a rechargeable battery.

[0219] In a 100 ml glass bottle 0.4 g of the respective polymer, 18.7 g of demineralized water, 0.8 g of carbon nanotubes (Cnano FT7320), 0.1 g defoamer (BYK-024) and 60 g of zirconium- oxide beads (1.0 mm) were added. Dispersion was carried out using a LAU-Disperser DAS 200 for 720 minutes at cooling level 3 followed by sieving-off the zirconium-oxide beads. Finally, the slurries were evaluated by measurement of the viscosity on an Anton Paar MCR 102 at 23°C in cone / plate geometry (25 1°). t can be concluded that the composition according to the invention has a significantly lower viscosity than the compositions with Comparative Examples. The compositions of the Comparative Examples have a too high viscosity for being used in the preparation of a component for a rechargeable battery. In a 100 ml glass bottle 0.3 g of the respective polymer, 19.0 g of demineralized water, 0.6 g of carbon nanotubes (Nanocyl NC 7000), 0.1 g defoamer (BYK-024) and 60 g of zirconiumoxide beads (1.0 mm) were added. Dispersion was carried out using a LAU-Disperser DAS 200 for 720 minutes at cooling level 3 followed by sieving-off the zirconium-oxide beads. Finally, the slurries were evaluated by measurement of the viscosity on an Anton Paar MCR 102 at 23°C in cone / plate geometry (25 1°).

[0220] It can be concluded that the composition according to the invention has a significantly lower viscosity than the compositions with Comparative Examples. The compositions of the Comparative Examples have a too high viscosity for being used in the preparation of a component for a rechargeable battery.

[0221] In a 100 ml glass bottle 0.3 g of the respective polymer, 16.6 g of demineralized water, 3.0 g of conductive carbon black (IMERYS C-NERGY SUPER C 65), 0.1 g defoamer (BYK-024) and 60 g of zirconium-oxide beads (1.0 mm) were added. Dispersion was carried out using a LAU-Disperser DAS 200 for 300 minutes at cooling level 3 followed by sieving-off the zirconium-oxide beads. Finally, the slurries were evaluated by measurement of the viscosity on an Anton Paar MCR 102 at 23°C in cone / plate geometry (25 1°).

[0222] In a 100 ml glass bottle 0.3 g of the respective polymer, 19.0 g of demineralized water, 0.6 g of carbon nanotubes (Nanocyl NC 7000), 0.1 g defoamer (BYK-024) and 60 g of zirconiumoxide beads (1.0 mm) were added. Dispersion was carried out using a LAU-Disperser DAS 200 for 720 minutes at cooling level 3 followed by sieving-off the zirconium-oxide beads. Finally, the slurries were evaluated by measurement of the viscosity on an Anton Paar MCR 102 at 23°C in cone / plate geometry (25 1°).

[0223] It can be concluded that the compositions according to the invention have a significantly lower viscosity than the compositions with Comparative Examples. The compositions of the Comparative Examples have a too high viscosity for being used in the preparation of a component for a rechargeable battery.

Claims

Claims1. A process for preparing a component of a rechargeable battery, wherein a composition comprising a) water, b) an electrically conductive carbon-based material, and c) a polymer comprising repeating units of polymerized monomers of i) a vinyl aromatic monomer, ii) a polyether acrylate or polyether methacrylate, and iii) an ethylenically unsaturated monomer having 1 or 2 carboxylic acid groups, wherein at least a part of the carboxylic acid groups is present in salt form, is employed for preparing the component.

2. The process according to claim 1 , wherein the polymer is dissolved in the water.

3. The process according to claim 1 or 2, wherein the vinyl aromatic monomer is styrene.

4. The process according to any one of the preceding claims, wherein the polyether acrylate or polyether methacrylate comprises polymerized units of at least one of ethylene oxide and propylene oxide.

5. The process according to any one of the preceding claims, wherein the polyether acrylate or polyether methacrylate comprises 3 to 50 non-cyclic ether groups.

6. The process according to any one of the preceding claims, wherein the polyether of the polyether acrylate or polyether methacrylate is terminated by a hydroxyl group or by a hydrocarbyl group.

7. The process according to any one of the preceding claims, wherein the ethylenically unsaturated monomer having 1 or 2 carboxylic acid groups comprises at least one of maleic acid, acrylic acid, and methacrylic acid.

8. The process according to any one of the preceding claims, wherein the polymer c) has a number average molecular weight in the range of 1500 to 30000 g / mol.

9. The process according to any one of the preceding claims, wherein 20 to 80 % by weight of the repeating units of the polymer c) are based on the polyether acrylate or polyether methacrylate.

10. The process according to any one of the preceding claims, wherein the polymer has an acid number in the range of 30 to 180 mg KOH / g11. The process according to any one of the preceding claims, wherein the polymer c) comprises repeating units of polymerized monomers of i) a vinyl aromatic monomer in an amount of 50 to 90 mol-%, ii) a polyether acrylate or polyether methacrylate in an amount of 5 to 45 mol-%, and iii) an ethylenically unsaturated monomer having 1 or 2 carboxylic acid groups in an amount of 5 to 45 mol-%, wherein the mol-% are calculated on the total number of moles of polymerized monomers.

12. The process according to any one of the preceding claims, wherein the electrically conductive carbon-based material comprises at least one of carbon nano tubes, carbon black, graphene, fullerene, and carbon fibers.

13. The process according to any one of the preceding claims, wherein the composition further comprises an organic polymeric binder, which is different from polymer c).

14. The process according to any one of the preceding claims wherein the component of the rechargeable battery is an anode or a cathode.

15. Use of a composition comprising water and a polymer comprising repeating units of polymerized monomers of i) a vinyl aromatic monomer, ii) a polyether acrylate or polyether methacrylate, and iii) an ethylenically unsaturated monomer having 1 or 2 carboxylic acid groups, wherein at least a part of the carboxylic acid groups is present in salt form, as a dispersing agent for an electrically conductive carbon-based material for a rechargeable battery.

16. A rechargeable battery comprising an electrically conductive carbon-based material and a polymer comprising repeating units of polymerized monomers of i) a vinyl aromatic monomer, ii) a polyether acrylate or polyether methacrylate, and iii) an ethylenically unsaturated monomer having 1 or 2 carboxylic acid groups, wherein at least a part of the carboxylic acid groups is present in salt form.

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