FI20215233A1 - Lithium-ion battery cathode binder formulation - Google Patents

Lithium-ion battery cathode binder formulation Download PDF

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Publication number
FI20215233A1
FI20215233A1 FI20215233A FI20215233A FI20215233A1 FI 20215233 A1 FI20215233 A1 FI 20215233A1 FI 20215233 A FI20215233 A FI 20215233A FI 20215233 A FI20215233 A FI 20215233A FI 20215233 A1 FI20215233 A1 FI 20215233A1
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kda
water
lithium
binder
soluble
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FI20215233A
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Finnish (fi)
Swedish (sv)
Inventor
Salla Puupponen
Tapio Honkanen
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Kemira Oyj
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Priority to FI20215233A priority Critical patent/FI20215233A1/en
Priority to PCT/FI2022/050131 priority patent/WO2022184979A1/en
Publication of FI20215233A1 publication Critical patent/FI20215233A1/en

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    • 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
    • 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
    • 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
    • H01M4/13—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
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H01M4/1315—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx containing halogen atoms, e.g. LiCoOxFy
    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/52—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron
    • H01M4/525—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of nickel, cobalt or iron of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
    • 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
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • 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

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The present invention relates to a binder formulation and a composition for lithiumion battery cathode. The present invention also relates to a method for producing the composition for a lithium-ion battery cathode. The present invention further relates to an electrode comprising an active material layer formed from the composition a current collector.

Description

LITHIUM-ION BATTERY CATHODE BINDER FORMULATION
TECHNICAL FIELD The present disclosure generally relates to lithium-ion battery cathode binder formulation. The disclosure relates particularly, though not exclusively, to lithium-ion battery cathode formulation comprising water-soluble binder and water-soluble dispersing agent. The disclosure additionally relates to lithium-ion battery cathode composition comprising the binder composition, cathode active material and conductive additive.
BACKGROUND This section illustrates useful background information without admission of any technique described herein representative of the state of the art. Lithium-ion battery (LiB) cathodes usually consist of active material (e.g. lithium nickel manganese cobalt oxides (NMC) or lithium ferro phosphate LiFePO4), electrical conducitivity enhancing carbon additives (e.g. carbon nanotube, graphene, or carbon black) and binder, which binds the electrode components together and to the aluminum current collector. Currently, polyvinylidene fluoride (PVDF) is the well-established cathode binder in LiBs. PVDF is thermally stable and chemically inert over the used potential range. However, halogenated PVDF requires environmentally harmful organic N- N methylpyrrolidone (NMP) solvent and is reactive towards lithiated graphite.
N S Due to these disadvantages, other binder chemistries have been researched for S 25 PVDF replacement. Polyacrylic acids (PAA) have been identified as potential E: binders for LiB electrodes PAA can be in acidic form, or it can be partly or & completely neutralized e.g. with sodium, lithium or potassium.
LO S
Dispersion agents are generally used in LiBs to improve the slurry homogeneity of negative electrodes (graphite or silicon type electrodes) and in the LiB separators (particularly in the diaphragms / ceramic separators).
SUMMARY The following presents a simplified summary of the features disclosed herein to provide a basic understanding of some exemplary aspects of the invention. This summary is not an extensive overview of the invention. It is not intended to identify key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts disclosed herein in a simplified form as a prelude to a more detailed description. In a first aspect the present invention provides a binder formulation for a lithium-ion battery cathode, wherein the binder formulation comprises at least one water- soluble binder and at least one water-soluble dispersing agent having lower molecular weight than molecular weight of the water-soluble binder.
In a second aspect the present invention provides a composition for a lithium-ion battery cathode, wherein the composition comprises at least one cathode active material, at least one electrical conducitivity enhancing additive, at least one water- soluble binder, at least one water-soluble dispersing agent having lower molecular weight than molecular weight of the water-soluble binder and optionally at least one thickening agent. = In a third aspect the present invention provides an electrode for a lithium-ion battery N comprising an aluminum current collector and at least one active material layer on g 25 atleast one surface of the aluminum current collector, wherein the at least one active S material layer is formed from the composition for a lithium-ion battery cathode.
T E In a fourth aspect the present invention provides a method for producing a composition for a lithium-ion battery cathode, wherein the method comprises mixing N water, at least one electrical conducitivity enhancing additive, at least one water- N 30 soluble binder, at least one water-soluble dispersing agent having lower molecular weight than molecular weight of the water-soluble binder and at least one and and optionally at least one thickening agent for producing a mixture, followed by adding at least one cathode active material to the mixture. In a fifth aspect the present invention provides a method for producing an electrode for a lithium-ion battery cathode, wherein the method comprises mixing water, at least one electrical conducitivity enhancing additive, at least one water-soluble binder, at least one water-soluble dispersing agent having lower molecular weight than molecular weight of the water-soluble binder, and optionally at least one thickening agent, followed by adding at least one cathode active material to the — mixture for producing a formulation (slurry), followed by coating an aluminum current collector with the slurry and drying the coated aluminum current collector. In a sixth aspect the present invention provides a lithium-ion battery comprising the electrode for lithium-ion battery.
In a seventh aspect the present invention provides use of the composition for a lithium-ion battery cathode for an electrode for a lithium-ion battery. It was found that cathode formulation comprising at least one water-soluble binder together with at least one water-soluble dispersion agent having lower molecular weight (MW) than molecular weight of the binder results in more even and homogeneous lithium battery cathode formulation as compared to binder alone. It was surprisingly found that cathode composition comprising water-soluble S 25 binder and water-soluble dispersion agent having lower molecular weight than se molecular weight of the binder has improved discharge capacity and charge- © discharge cycle stability as compared to a cathode containing only binder, such I as polyacrylicacid (PAA) binder, without the dispersing agent. a 0 & 30 Additionally, it was found that by selecting pH of the water-soluble binder so that N pH of the cathode composition is 7 or close to 7, corrosion of aluminum current N collector and leaching/degradation of active material, such as Ni and Li, can be prevented.
The appended claims define the scope of protection.
BRIEF DESCRIPTION OF THE FIGURES Figure 1a shows optical microscopy image of electrode formed from PAA binder slurry according to reference Example 3.
Figure 1b shows optical microscopy image of electrode formed from composition containing 75:25 PAA binder and AA-AMPS dispersion agent, respectively, (Example 7 according to the present invention).
Figure 1c shows optical microscopy image of electrode formed from composition containing 80:20 PAA binder and PMANH-DIIB dispersion agent, respectively (Example 5 according to the present invention) Figure 1d shows optical microscopy image of electrode formed from composition containing 80:20 PAA binder and PAA dispersion agent, respectively (Example 6 according to the present invention) Figure 2 shows rate capability measurements of lithium-ion battery half-cells formed of cathode slurry compositions of reference Example 2 and Example 5 according to the present invention; and as another reference, lithium-ion battery half-cell composed of PVDF and NMP as cathode binder and solvent.
DETAILED DESCRIPTION
N & 6 25 In a first aspect the present invention provides a binder formulation for a lithium-ion
O n battery cathode. The binder formulation comprises at least one water-soluble binder
O I and at least one water-soluble dispersing agent having lower molecular weight (MW) a - than molecular weight of the water-soluble binder.
O o N 30 In one embodiment solvent of the binder formulation is polar solvent.
N In one embodiment the binder formulation is aqueous (water) based formulation.
In one embodiment solvent of the binder formulation is organic. The binder formulation may comprise compounds having aromatic groups and/or 5 halogenated compounds. In one embodiment the molecular weight of the water-soluble binder is 100 kDa- 1000 kDa, preferably 100 kDa-500 kDa, more preferably 100 kDa-400 kDa even more preferably 100 kDa-300 kDa.
In one embodiment the molecular weight of the water-soluble dispersing agent is 3 kDa-60 kDa, preferably 10 kDa-40 kDa, more preferably 10 kDa-35 kDa. In one embodiment the dispersing agent is polyelectrolyte.
In one embodiment functional groups and monomers of the water-soluble binder and the water-soluble dispersing agent comprise carboxylic acids and anhydrides (such as acrylic acid, methacrylic acid, acetic acid, maleic anhydride, maleic acid, fumaric acid, itaconic acid, aconitic acid, mesaconic acid, citraconic acid, crotonic acid, isocrotonic acid, angelic acid, tiglic acid, vinyl acetic acid, hydroxyethyl methacrylic acid (HEMA), hydroxyethyl acrylic acid (HEA)), sulphonic acid (such as vinyl sulphonic acid, allyl sulphonic acid, styrene-p-sulphonic acid, acryloamido-2-methylpropanesulfonic acid (AMPS)), acrylamides (such as terybutylacrylamides), alcohols (such as vinyl alcohol, propargyl alcohol having S 25 formula HC=C—CH>—OH; butyr-1,4-diol), vinyl chloride, and salts of any of these se groups and mixtures of any of these groups thereof. 2 I In one embodiment functional groups and monomers of the water-soluble binder en and the water-soluble dispersing agent comprise carboxylic acids and anhydrides, & 30 sulphonic acid, acrylamides, alcohols, vinylchloride and salts of any of these N groups, and mixtures of any of these groups thereof.
N
In one embodiment the water-soluble binder comprises homopolymer and/or copolymer of acrylic acid, methacrylic acid, maleic acid, AMPS, acrylamide, styrene-p-sulphonic acid and mixtures thereof.
In one embodiment the water-soluble dispersing agent monomers comprises acrylic acid, methacrylic acid, maleic acid, AMPS, acrylamide, styrene-p-sulphonic acid and mixtures thereof In one embodment the water-soluble binder is selected so that pH of the formulation is 7 or close to 7, such as 6-8.
The water-soluble binder can be in acidic form, or it can be partly or completely neutralized (i.e. 100 % of acid groups are neutralized) e.g. with sodium, lithium or potassium. pH of the water-soluble binder can be selected so that pH of the formulation is 7 or close to 7, such as 6-8 In one embodiment the water-soluble binder is polyacrylic acid (PAA) and/or carboxymethyl cellulose (CMC). In one embodiment molecular weight (MW) of the PAA is 100 kDa-1000 kDa, preferably 100 kDa-500 kDa, more preferably 100kDa-400 kDa. The PAA can be in acidic form, or it can be partly or completely neutralized e.g. with sodium, lithium or potassium. In one embodiment the PAA is partly neutralized and having such pH that the pH of the water based formulation is 7 or close to 7, such as 6-8. S 25 se In one embodiment the binder formulation comprises 50-99 wt.%, preferably 75-95 © wt. %, and more preferably 90-95 wt. % of the water-soluble binder.
E en In one embodiment the binder formulation comprises 1-50 wt.%, preferably 5-25 & 30 wt%, more preferably 2-15 wt.% and even more preferably 5-10 wt.% of the N water-soluble dispersing agent.
N The weights are calculated as weight of active coponent.
In one embodiment the formulation is produced by mixing water, the at least one water-soluble binder and the at least one water-soluble dispersing agent having lower molecular weight than molecular weight of the water-soluble binder.
One or more of the above disclosed embodiments can be combined. In a second aspect the present invention provides a composition for lithium-ion battery cathode. The composition comprises at least one cathode active material, at least one electrical conducitivity enhancing additive, at least one water-soluble binder and at least one water-soluble dispersing agent having lower molecular weight than molecular weight of the water-soluble binder. In one embodiment solvent of the composition is polar solvent.
In one embodiment the composition is aqueous (water) based composition. In one embodiment solvent of the composition is organic. The composition may comprise compounds having aromatic groups and/or halogenated compounds. In one embodiment the cathode active material comprises lithium nickel manganese cobalt oxides (NMC LiNixMnyC0ozO2), lithium ferro phosphate (LFP, S 25 LiFePO4), lithium cobalt oxide (LCO, LiCoO2), lithium manganese oxide (LMO, se LiMn204), lithium nickel cobalt aluminum oxide (LiNiCoAIO2), lithium titanate © (LTO, Li2TiO3) and mixtures thereof.
E en In one embodiment the electrical conducitivity enhancing additive comprises & 30 carbon nanotube, graphene, carbon black, activated carbon and mixtures thereof. 3 In one embodiment the composition comprises at least one thickening agent, e.g. carbohydrate type polymer such as carboxymethyl cellulose, CMC, xanthan gum or quar gum (to increase the viscosity of the composition (slurry) and to prevent the solvent — solid particles phase separation). In one embodiment the molecular weight of the water-soluble binder is 100 kDa- 1000 kDa, preferably 100 kDa-500 kDa, more preferably 100 kDa-400 kDa even more preferably 100 kDa-300 kDa. In one embodiment the molecular weight of the water-soluble dispersing agent is 3 kDa-60 kDa, preferably 10 kDa-40 kDa, more preferably 10 kDa-35 kDa.
In one embodiment the dispersing agent is polyelectrolyte. In one embodiment functional groups and monomers of the water-soluble binder and the water-soluble dispersing agent comprise carboxylic acids and anhydrides — (such as acrylic acid, methacrylic acid, acetic acid, maleic anhydride, maleic acid, fumaric acid, itaconic acid, aconitic acid, mesaconic acid, citraconic acid, crotonic acid, isocrotonic acid, angelic acid, tiglic acid, vinyl acetic acid, hydroxyethyl methacrylic acid (HEMA), hydroxyethyl acrylic acid (HEA)), sulphonic acid (such as vinyl sulphonic acid, allyl sulphonic acid, styrene-p-sulphonic acid, acryloamido-2-methylpropanesulfonic acid (AMPS)) acrylamides (such as terybutylacrylamides), alcohols (such as vinyl alcohol, propargyl alcohol having formula HC=C—CH>—OH; butyr-1,4-diol), vinyl chloride and salts of any of these groups and mixtures of any of these groups thereof. S 25 In one embodiment functional groups and monomers of the water-soluble binder se and the water-soluble dispersing agent comprise carboxylic acids and anhydrides, © sulphonic acid, acrylamides, alcohols, vinylchloride and salts of any of these I groups, and mixtures of any of these groups thereof. 0 & 30 In one embodiment the water-soluble binder comprises homopolymer and/or N copolymer of acrylic acid, methacrylic acid, maleic acid, AMPS, acrylamide, N styrene-p-sulphonic acid and mixtures thereof.
In one embodiment the water-soluble dispersing agent monomers comprises acrylic acid, methacrylic acid, maleic acid, AMPS, acrylamide, styrene-p-sulphonic acid and mixtures thereof In one embodment the water-soluble binder is selected so that pH of the composition is 7 or close to 7 such as 6-8, therefore corrosion of aluminum current collector and leaching/degradation of active material, such as Ni and Li, can be prevented.
The water-soluble binder can be in acidic form, or it can be partly or completely neutralized (i.e. 100 % of acid groups are neutralized) e.g. with sodium, lithium or potassium. pH of the water-soluble binder can be selected so that pH of the formulation is 7 or close to 7, such as 6-8 In one embodiment the water-soluble binder is polyacrylic acid (PAA) and/or carboxymethyl cellulose (CMC).
In one embodiment molecular weight (MW) of the PAA is 100 kDa-1000 kDa, preferably 100 kDa-500 kDa, more preferably 100kDa-400 kDa. The PAA can be in acidic form, or it can be partly or completely neutralized e.g. with sodium, lithium or potassium. In one embodiment the PAA is partly neutralized and having such pH that the pH of the water based formulation is 7 or close to 7, such as 6-8.
In one embodiment the cathode composition (slurry) consists of solids fraction and S 25 water solvent. The solids fraction comprises cathode active material, electrical se conductivity enhancing additive, binder formulation (binder and dispersing agent) © and optionally thickening agent.
E en In one embodiment the solids fraction comprises 70-95 wt.%, preferably 80-95 & 30 wt. % of the cathode active material. 3 In one embodiment the solids fraction comprises 1-15 wt.%, preferably 2-10 wt. %, more preferably 2-5 wt.% of the electrical conducitivity enhancing additive.
In one embodiment the solids fraction comprises 1-15 wt. %, preferably 2-8 wt.% of the water-soluble binder formulation consisting of binder and dispersion agent. In one embodiment the binder formulation comprises 1-50 wt.%, preferably 2-20 wt. %, more preferably 2-10 wt.% of the water-soluble dispersing agent. In one embodiment solids fraction (dry fraction) in the electrode consists the cathode active material : the electrical conductivity enhancing agent : the binder and the dispersing agent in weight fractions of 95 : 2 : 3 (wt.%), respectively. The weight fractions are calculated as weight fractions of active coponent. If there is less than 1 wt.% of the dispersing agent in the composition, it has minor or no effects on the composition properties. If there is more than 50 wt.% of the dispersing agent in the composition, the properties of the composition are impaired. Large amount of dispersing agent impaires binding ability of the binder. It is preferred to have total amount of binder and dispersing agent as low as possible and amount of cathode active material as high as possible on electrode. One or more of the above disclosed embodiments can be combined. In a third aspect the present invention provides an electrode for a lithium-ion battery comprising an aluminum current collector and at least one active material layer on at least one surface of the aluminum current collector, wherein the at least one active S 25 material layer is formed from the composition for lithium-ion battery cathode se according to the present invention. S In one embodiment dry fraction (solids) in the electrode consists the cathode E active material : the electrical conductivity enhancing agent : the binder and the & dispersing agent in weight fractions of 95 : 2:3 (wt %), respectively. The weight = 30 fractions are calculated as weight fractions of active coponent.
O N
In one embodiment solids loading in the electrode is 20-60 %, preferably 40-60 %. In a fourth aspect the present invention provides a method for producing a composition for a lithium-ion battery cathode. The method comprises mixing water, at least one electrical conducitivity enhancing additive, at least one water-soluble binder, at least one water-soluble dispersing agent having lower molecular weight than molecular weight of the water-soluble binder and optionally at least one thickening agent for producing a mixture, followed by adding at least one cathode active material to the mixture. In one embodiment the electrical conducitivity enhancing additive, the water- soluble binder, the water-soluble dispersing agent, and the optional thickening agent and the cathode active material are the same as defined above.
In a preferred embodiment, the method of the present invention produces the composition for lithium-ion battery cathode according to the present invention. In a fifth aspect the present invention provides a method for producing an electrode for a lithium-ion battery cathode. The method comprises mixing water, at least one electrical conducitivity enhancing additive, at least one water-soluble binder, at least one water-soluble dispersing agent having lower molecular weight than molecular weight of the water-soluble binder and optionally at least one thickening N agent, followed by adding at least one cathode active material to the mixture for N 25 producing a composition (slurry), followed by coating an aluminum current 3 collector with the slurry and drying the coated aluminum current collector.
O z In one embodiment the dryed and coated aluminum current collector is 2 calendered. LO 30 3
The coating of the aluminum current collector can be performed by any suitable method known for a skilled person. Such methods for example comprises slot- die, blade, roll-to-roll and gravure coating technologies.
The drying of the coated aluminum current collector can be performed by any suitable method known for a skilled person. Such methods for example comprises industrial dryer, oven drying and vacuum drying.
In one embodiment the electrical conducitivity enhancing additive, the water- soluble binder, the water-soluble dispersing agent, the optional thickening agent and the cathode active material are the same as defined above. In a preferred embodiment, the method of the present invention produces the electrode for lithium-ion battery cathode according to the present invention.
In a sixth aspect the present invention provides a lithium-ion battery comprising the electrode for a lithium-ion battery according to the present invention. In a seventh aspect the present invention provides use of the composition for a lithium-ion battery cathode according to the present invention for an electrode for a lithium-ion battery.
EXAMPLES a N 25 Example 1 — reference slurry with PVDF/NMP binder S 5-10 w-% polyvinylidene fluoride (PVDF) in N-methylpyrrolidone (NMP) solvent S is prepared by dissolving first the polymer to solvent. The dried carbon (Timcal z C65) is added to PVDF solution and mixing is continued for 30-60 min. The dried & lithium nickel manganese cobalt oxide active material (type NMC622, Targray is = 30 added in 2-4 parts. Mixture is stirred for 30-60 minutes between each addition. Viscosity is checked after mixing and more NMP is added if needed. The slurry is let to stand for 30-60 min to remove most of the bubbles formed during mixing.
The slurry is coated with DoctorBlade to Al foild. 120-200 um wet thicknesses have been used to achieve 1 mAh cm? (~5 mg cm? of active material). The coated foils are dried in a fume hood overnight, after which the foils are dried in an oven at 80 *C for 4 h.
The electrodes are cut and calandered using 2.5 t/cm? force.
Example 2 — general composition of cathode composition (slurry) according to the present invention Agueous binder cathode slurry is formed by first mixing water solvent, the carbon black conductive additive (Timcal C65), binder and dispersion agent (if used) together.
After this, lithium nickel manganese cobalt active material (type NMC622, Targray) is added to the mixture.
The dry weight fraction of the slurry is 30-35 w-% and the dry fraction of the slurry consists of NMC active material: binder+dispersion agent : conductive additive in weight fractions of 95 : 3 : 2, — respectively.
Aluminum current collector is coated with well-mixed, homogeneous cathode slurry.
The coating is done on Al foil either manually using metallic rolling pin or using Doctor Blade.
In the case of Doctor Blade coating, 120-200 um wet thicknesses have been used to achieve 1 mAh cm? (~5 mg cm? of active material). Usually 170 um is the most suitable.
The cathode is dried (first 2 h at 80 °C, cut and calendered using 2.5 t/cm? force.
Finally, the cut electrodes are dried overnight either 120 °C in a vacuum oven or 140 °C in a heating cabinet.
S 25 Example 3 -reference compositions (slurries) containing only PAA binder se Used binder in first reference composition is partly sodium neutralized polyacrylic © acid (PAA, molecular weight appr. 250-280 kDa). Dispersion agent is not used in I the composition.
The dry fraction of the slurry consists of NMC : PAA binder : en conductive additive in weight fractions of 95 : 3 : 2, respectively.
The compositions & 30 and electrode are produced according to Example 2. 3 Example 4— slurry composition 4 with PAA binder and dispersion agent according to the present invention
Used binder is partly sodium neutralized PAA (MW appr. 250 kDa) and dispersion agent is polyacrylic acid-2-acrylamido-2-methylpropane sulfonic acid dispersion agent (MW of polymer appr 30 kDa). The dry fraction of the slurry consists of NMC: binder : dispersion agent : conductive additive in weight fractions of 95: 2.4
0.6: 2, respectively. The composition and electrode are produced according to Example 2. Example 5 — slurry composition 5 with PAA binder and dispersion agent according to the present invention Used binder is partly sodium neutralized PAA (MW appr. 250 kDa) and dispersion agent is poly(maleic anhydride)-diisobutylene (PMANH-DIIB) (MW appr. 18 kDa). The dry fraction of the slurry consists of NMC: binder : dispersion agent : conductive additive in weight fractions of 95: 2.4 : 0.6 : 2, respectively. The slurry and electrode are produced according to Example 2.
Example 6— slurry composition 6 with PAA binder and dispersion agent according to the present invention Used binder is partly sodium neutralized PAA (MW appr. 250 kDa) and dispersion agent is sodium neutralized PAA (MW appr. 3 kDa). The dry fraction of the slurry consists of NMC: binder : dispersion agent : conductive additive in weight fractions of 95: 2.4: 0.6: 2, respectively. The slurry and electrode are produced according to Example 2. Example 7— slurry composition 7 with PAA binder and dispersion agent according S 25 tothe present invention se used binder is partly sodium neutralized PAA (MW appr 250 kDa) and dispersion © agent is polyacrylic acid-2-acrylamido-2-methylpropane sulfonic acid dispersion I agent (MW appr 30 kDa). The dry fraction of the slurry consists of NMC: binder : en dispersion agent : conductive additive in weight fractions of 95 : 2.25 : 0.75 : 2, & 30 respectively. The slurry and electrode are produced according to Example 2. 3 Example 8 — slurry composition 8 with PAA binder and dispersion agent according to the present invention
Used binder is partly sodium neutralized PAA (MW appr. 250 kDa) and dispersion agent is polyacrylic acid-2-acrylamido-2-methylpropane sulfonic acid dispersion agent (MW appr. 30 kDa). The dry fraction of the slurry consists of NMC: binder : dispersion agent : conductive additive in weight fractions of 95 : 2.7 : 0.3 : 2, respectively. The slurry and electrode are produced according to Example 2.
OPTICAL MICROSCOPY Figures 1a, 1b, 1c and 1d present optical microscopy images of electrodes formed of slurries of Examples 3, 7, 5 and 6, respectively. In these samples, dry weight fraction of the slurries was 30 w-%. After slurry formation, the samples are coated to Al foil manually using metallic rolling pin and dried in a heating cabinet at 140 °C overnight. The samples are imaged using Leica DMLM microscope with LAS-X software using 10x magnification, 5.0 brightness, 1.0 contrast and white light. The binder and/or dispersion agents used in the cathodes: Fig. 1a: PAA binder (Ref. Example 3); Fig. 1b: composition containing 75:25 PAA binder and AA-AMPS dispersion agent, respectively (Example 7 according to the present invention) Fig.1c: formulation containing 80:20 PAA binder and PMANH-DIIB dispersion agent, respectively (Example 5 according to the present invention) Fig.1d: formulation containing 80:20 PAA binder and PAA dispersion agent, respectively (Example 6 according to the present invention) S 25 GALVANOSTATIC RATE CAPABILITY MEASUREMENTS se Figure 2 presents the results of rate capability measurements of LiBs (lithium ion © batteries) composed of slurries of Ref. Example 3 and Example 9 of the present I invention. As a reference, LiB half-cell (reference electrode lithium metal) en composed of PVDF and NMP as cathode binder and solvent, respectively, has & 30 been measured. 3 Cathodes of LiBs are prepared by coating the sample to Al foil using Doctor Blade technique and drying the electrodes in a vacuum oven overnight at 120 °C. In the case of PVDF/NMP cathode, the electrodes are dried in an oven at 80 °C for 4 h. In aqueous cathode compositions, dry weight fraction of the electrodes is 35 w- %, whereas in PVDF/NMP cathode the dry weight fraction is 60 w-%. The dry weight fractions of all cathodes consist of NMC active material:binder+dispersion agent:conductive additive in 95:3:2 weight fractions. Cathodes are assembled as half cells (2016 Hohsen coin cells, 2 20 mm, 1.6 mm thickness) for electrochemical measurements. Glass fiber separator (Whatman GF/A, 0.26 mm),
0.75 mm thick lithium metal counter electrode (Alfa Aesar), 0.2 mm thick stainless steel spacer (MTI) and 1 M LiPF4 in 1:1 EC:DMC (BASF, LP30) have been used for the half cell assembly. The electrochemical measurements were started 24 h after cell assembly. The galvanostatic rate capability measurements are done with Neware battery cycler. Rate capabilities of the Li half-cells are measured in voltage ranges of 3-4.4 V by varying discharge C-rates from 0.2 C to 5.0 C while retaining the charge C-rate constant at 0.2 C. At least three parallel measurements are carried out of similar electrode structure to ensure the repeatability of the results. The specific discharge capacity of LiB half cell composed of cathode of Example 7 (PAA binder and AA-AMPS dispersion agent in weight fractions of 9:1, respectively) is on average 9% higher as compared to Example 2 containing PAA binder alone. The discharge capacity of Example 7 sample is higher as compared to sample of Example 2 when the discharge C-rate is higher. Furthermore, the _ charge-discharge cycling stability of the half-cell with Example 7 cathode seems O 25 to be better as compared to cathode containing only PAA binder (Example 2) or se PVDF/NMP reference sample. Indeed, in the first three 0.1C discharge cycles, O the discharge capacities of Example 2 and Example 5 samples are on average I 5% and 11 % lower, respectively, than the capacity of PVDF/NMP sample. In the N last three 0.1C cycles, the discharge capacity of Example 7 is practically the same & 30 as that of PVDF/NMP sample (2% lower), whereas the discharge capacity of N Example 2 is still 11% lower than that of PVDF/NMP sample.
N
Various embodiments have been presented. It should be appreciated that in this document, words comprise, include, and contain are each used as open-ended expressions with no intended exclusivity. The foregoing description has provided by way of non-limiting examples of particular implementations and embodiments a full and informative description of the best mode presently contemplated by the inventors for carrying out the invention. It is however clear to a person skilled in the art that the invention is not restricted to details of the embodiments presented in the foregoing, but that it can be implemented in other embodiments using equivalent means or in different combinations of embodiments without deviating from the characteristics of the invention. Furthermore, some of the features of the afore-disclosed example embodiments may be used to advantage without the corresponding use of other features. As such, the foregoing description shall be considered as merely illustrative of the principles of the present invention, and not in limitation thereof. Hence, the scope of the invention is only restricted by the appended patent claims.
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Claims (15)

1. A binder formulation for a lithium-ion battery cathode, wherein the binder formulation comprises at least one water-soluble binder and at least one water- soluble dispersing agent having lower molecular weight than molecular weight of the water-soluble binder.
2. The binder formulation according to claim 1, wherein the molecular weight of the water-soluble dispersing agent is 3 kDa-60 kDa, preferably 10 kDa-40 kDa, more preferably 10 kDa-35 kDa
3. The binder formulation according to claim 1 or 2, wherein the molecular weight of the water-soluble binder is 100 kDa-1000 kDa, preferably 100 kDa-500 kDa, more preferably 100 kDa-400 kDa even more preferably 100 kDa-300 kDa.
4. The binder formulation according to any of claims 1-4, wherein functional groups and monomers of the water-soluble binder and the water-soluble dispersing agent comprise carboxylic acids and anhydrides, sulphonic acid, acrylamides, alcohols, vinylchloride and salts of any of these groups, and mixtures of any of these groups thereof.
5. A composition for lithium-ion battery cathode, wherein the composition comprises at least one cathode active material, at least one electrical _ conducitivity enhancing additive, at least one water-soluble binder, at least one O 25 water-soluble dispersing agent having lower molecular weight than molecular se weight of the water-soluble binder and optionally at least one thickening agent. 2 z
6. The composition according to claim 5, wherein the cathode active material N comprises lithium nickel manganese cobalt oxides (NMC LiNixMnyC0ozO2), & 30 lithium ferro phosphate (LFP, LiFePO4), lithium cobalt oxide (LCO, LiCo02), N lithium manganese oxide (LMO, LiMn204), lithium nickel cobalt aluminum N oxide (LiNiCoAlO2), lithium titanate (LTO, Li2TiO3) and mixtures thereof.
7. The composition acording to claim 5 or 6, wherein electrical conducitivity enhancing additive comprises carbon nanotube, graphene, carbon black, activated carbon and mixtures thereof.
8. The composition according to any of claims 5-7, wherein molecular weight of the water-soluble dispersing agent is 3 kDa-60 kDa, preferably 10 kDa-40 kDa, more preferably 10 kDa-35 kDa.
9. The composition according to any of claims 5-8, wherein molecular weight of the water-soluble binder is 100 kDa-1000 kDa, preferably 100 kDa-500 kDa, more preferably 100 kDa-450 kDa.
10. The composition according to any of claims 5-9, wherein functional groups and monomers of the water-soluble binder and the water-soluble dispersing agent comprise carboxylic acids and anhydrides, sulphonic acid, acrylamides, alcohols, vinylchloride and salts of any of these groups, and mixtures of any of these groups thereof.
11. An electrode for a lithium-ion battery comprising an aluminum current collector and at least one active material layer on at least one surface of the aluminum current collector, wherein the at least one active material layer is formed from the composition for lithium-ion battery cathode according to any of claims 5-10.
12. A method for producing a composition for lithium-ion battery cathode, wherein S 25 the method comprises mixing water, at least one electrical conducitivity se enhancing additive, at least one water-soluble binder, at least one water-soluble © dispersing agent having lower molecular weight than molecular weight of the I water-soluble binder and at least one thickening agent for producing a mixture a en followed by adding at least one cathode active material to the mixture. & 30 N 13. A method for producing an electrode for a lithium-ion battery cathode, wherein N the method comprises mixing water, at least one electrical conducitivity enhancing additive, at least one water-soluble binder and at least one water-
soluble dispersing agent having lower molecular weight than molecular weight of the water-soluble binder and optionally at least one thickening agent followed by adding at least one cathode active material to the mixture for producing a composition (slurry) followed by coating an aluminum current collector with the slurry and drying the coated aluminum current collector.
14. A lithium-ion battery comprising the electrode for lithium-ion battery according to claim 11.
15. Use of the composition for a lithium-ion battery cathode according to any of claims 5-10 for an electrode for a lithium-ion battery.
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US5248425A (en) * 1992-10-28 1993-09-28 Corning Incorporated Aqueous thermite coated filter
JPH09137156A (en) * 1995-11-16 1997-05-27 Mitsubishi Chem Corp Polishing composition for hard disk substrate and polishing method therewith
JP3951420B2 (en) * 1998-03-19 2007-08-01 株式会社村田製作所 Ceramic slurry composition
KR102049679B1 (en) * 2015-08-11 2019-11-28 쇼와 덴코 가부시키가이샤 The lithium ion secondary battery provided with the positive electrode for lithium ion secondary batteries obtained using the slurry for positive electrodes of a lithium ion secondary battery, the slurry for positive electrodes of a lithium ion secondary battery, and its manufacturing method, and the positive electrode for lithium ion secondary batteries, and its manufacturing method

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