WO2024056103A1 - Liant à base d'eau, et procédé de préparation et utilisation de celui-ci - Google Patents

Liant à base d'eau, et procédé de préparation et utilisation de celui-ci Download PDF

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Publication number
WO2024056103A1
WO2024056103A1 PCT/CN2023/126030 CN2023126030W WO2024056103A1 WO 2024056103 A1 WO2024056103 A1 WO 2024056103A1 CN 2023126030 W CN2023126030 W CN 2023126030W WO 2024056103 A1 WO2024056103 A1 WO 2024056103A1
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water
monomer
initiator
polymer
monomer unit
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PCT/CN2023/126030
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English (en)
Chinese (zh)
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梁华晴
刘俊
岳敏
朱文强
王想
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深圳市研一新材料有限责任公司
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Publication of WO2024056103A1 publication Critical patent/WO2024056103A1/fr

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    • 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
    • C08F220/42—Nitriles
    • C08F220/44—Acrylonitrile
    • C08F220/48—Acrylonitrile with nitrogen-containing monomers
    • 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
    • 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
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • 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
    • 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
    • H01M2004/027—Negative 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

Definitions

  • the invention belongs to the technical field of lithium ion batteries, and specifically relates to an aqueous binder and its preparation method and use.
  • lithium-ion batteries have been widely used in products such as mobile phones, computers, and electric vehicles, and have great commercial value.
  • the cathode materials of commercial lithium-ion batteries are mainly oxides such as LiCoO 2 , LiMn 2 O 4 and LiFePO 4 ;
  • the negative electrode materials are mainly graphite. Due to the low theoretical capacity of graphite (372mAh/g), it is difficult to meet the requirements. Due to the rapid development of electronic information and energy technology today, the development of high-capacity silicon-based materials has become a major issue in the development of lithium-ion battery technology. However, since silicon-based materials are accompanied by greater volume expansion and contraction (up to 300%) during charge and discharge, the electrode capacity decays quickly and the cycle performance is poor. Therefore, there is a need to develop binders with high bonding strength and the ability to reduce the expansion of silicon anodes to achieve cycle stability of high-capacity anodes.
  • silicon anode binders in the prior art include SBR (styrene-butadiene rubber) binders and PAA binders.
  • SBR binder is usually used in conjunction with CMC.
  • SBR itself has low strength, poor bonding force, and poor resistance to expansion of the counter electrode. Therefore, when used in silicon anodes, its cycle performance is often very poor; the PAA adhesive in the existing technology is used.
  • the pole pieces prepared by the bonding agent have poor flexibility and poor processing performance. After the structure is damaged, it is difficult to recover and the cycle performance is poor.
  • the purpose of the present invention is to provide a water-based binder and its preparation method and use.
  • the water-based binder provided by the present invention has excellent bonding performance and can significantly inhibit the silicon negative electrode. expansion, while making the prepared pole piece have excellent flexibility, improving the cycle performance of the battery.
  • the present invention provides an aqueous binder.
  • the aqueous binder includes a polymer containing at least three monomer units.
  • the polymer includes a first monomer unit, a second monomer unit and The third monomer unit, the first monomer unit has a structure represented by formula I, the second monomer unit has a structure represented by formula II, and the third monomer unit has a structure represented by formula III.
  • R 1 , R 2 , R 3 and R 6 are the same or different, and each independently represents hydrogen, a linear alkyl group or a branched alkyl group; R 5 is a group containing a hydroxyl group at the end group.
  • R 1 , R 2 and R 3 are based on the principle of maintaining the water solubility of the monomer
  • the selection of R 5 is based on the principle of maintaining the water solubility of the monomer. Maintain the water solubility of the monomer as a principle.
  • the water-based binder provided by the present invention has excellent bonding properties and can significantly inhibit the expansion of the silicon negative electrode. At the same time, the prepared pole piece has excellent flexibility and improves the cycle performance of the battery.
  • R 5 represents a linear alkyl group with 1 to 6 carbon atoms substituted by a hydroxyl group, and a branched alkyl group with a carbon number of 1 to 6 substituted by a hydroxyl group. , -CH 2 CH 2 OCH 2 CH 2 OH or -(CH 2 CH 2 O) n H, n ⁇ 3 (for example, n can be 3, 5, 7 or 10, etc.).
  • R 1 , R 2 , R 3 and R 6 are the same or different, and each independently represents hydrogen, a linear alkyl group with 1 to 6 carbon atoms or carbon Branched alkyl group with atomic number 1-6.
  • R 5 represents -CH 2 CH 2 OH, CH 2 CH 2 CH 2 OH, -CH 2 CH 2 OCH 2 CH 2 OH or -(CH 2 CH 2 O ) n H, n ⁇ 3 (for example, n can be 3, 5, 7 or 10, etc.).
  • R 1 represents hydrogen, methyl, ethyl, propyl, -CH(CH 3 ) 2 , -CH 2 CH 2 CH 2 CH 3 or -CH 2 CH (CH 3 ) 2
  • R 2 represents hydrogen, methyl, ethyl, propyl, -CH(CH 3 ) 2 , -CH 2 CH 2 CH 2 CH 3 or -CH 2 CH(CH 3 ) 2
  • R 3 Represents hydrogen, methyl, ethyl, propyl, -CH(CH 3 ) 2 , -CH 2 CH 2 CH 2 CH 3 or -CH 2 CH(CH 3 ) 2
  • R 6 represents hydrogen, methyl, ethyl or -CH(CH 3 ) 2 .
  • the polymer further includes a fourth monomer unit, and the fourth monomer unit has a structure represented by Formula IV:
  • R 4 represents hydrogen, linear alkyl or branched alkyl
  • M represents H, Li, Na or K.
  • R 4 represents hydrogen, a linear alkyl group with 1 to 6 carbon atoms or a branched alkyl group with 1 to 6 carbon atoms.
  • R 4 represents Hydrogen, methyl, ethyl or -CH(CH 3 ) 2 .
  • the solid content of the water-based binder is 9.5-10.5%
  • the viscosity is 8000-30000cps (for example, the viscosity can be 8000cps, 10000cps, 15000cps, 20000cps, 25000cps or 30000cps wait).
  • the polymer has a structure represented by Formula V:
  • M represents H, Li, Na or K
  • R 1 represents hydrogen, a linear alkyl group or a branched alkyl group.
  • R 1 represents hydrogen, a linear alkyl group having 1 to 6 carbon atoms or a branched alkyl group having 1 to 6 carbon atoms, and more
  • the R 1 represents hydrogen, methyl, ethyl, propyl, -CH(CH 3 ) 2 , -CH 2 CH 2 CH 2 CH 3 or -CH 2 CH(CH 3 ) 2 ;
  • R 2 represents hydrogen, a linear alkyl group or a branched alkyl group.
  • R 2 represents hydrogen, a linear alkyl group having 1 to 6 carbon atoms or a branched alkyl group having 1 to 6 carbon atoms, and more
  • the R 2 represents hydrogen, methyl, ethyl, propyl, -CH(CH 3 ) 2 , -CH 2 CH 2 CH 2 CH 3 or -CH 2 CH(CH 3 ) 2 ;
  • R 3 represents hydrogen, a linear alkyl group or a branched alkyl group.
  • R 3 represents hydrogen, a linear alkyl group with 1 to 6 carbon atoms or a branched alkyl group with 1 to 6 carbon atoms, and more
  • the R 3 represents hydrogen, methyl, ethyl, propyl, -CH(CH 3 ) 2 , -CH 2 CH 2 CH 2 CH 3 or -CH 2 CH(CH 3 ) 2 ;
  • R 4 represents hydrogen, a linear alkyl group or a branched alkyl group.
  • R 4 represents hydrogen, a linear alkyl group having 1 to 6 carbon atoms or a branched alkyl group having 1 to 6 carbon atoms.
  • R 4 represents hydrogen, methyl, ethyl or -CH(CH 3 ) 2 ;
  • R 5 is a group containing a hydroxyl group at the terminal group.
  • the terminal hydroxyl group is more likely to contact and interact with the active material, making it easier for the pole piece coating to form a three-dimensional network structure and improve the ability to inhibit expansion.
  • R 5 represents a linear alkyl group with 1 to 6 carbon atoms substituted by hydroxyl group, a branched alkyl group with 1 to 6 carbon atoms substituted by hydroxyl group, -CH 2 CH 2 OCH 2 CH 2 OH or -(CH 2 CH 2 O) n H, n ⁇ 3, more preferably, the R 5 represents -CH 2 CH 2 OH, CH 2 CH 2 CH 2 OH, -CH 2 CH 2 OCH 2 CH 2 OH or -(CH 2 CH 2 O) n H, n ⁇ 3;
  • R 6 represents hydrogen, a linear alkyl group or a branched alkyl group.
  • R 6 represents hydrogen, a linear alkyl group having 1 to 6 carbon atoms or a branched alkyl group having 1 to 6 carbon atoms, and more
  • the R 6 represents hydrogen, methyl, ethyl or -CH(CH 3 ) 2 ;
  • a:b:c:d (30 ⁇ 80):(0 ⁇ 50):(5 ⁇ 50):(5-30), for example, a:b:c:d can be 40:30:15:15, 40:30:10:20, 60:0:20:20, 30:20:40:10 or 30:20:20:30, etc.; a:b:c:d are the individual monomers.
  • other preferred value ranges of a can include: (30-60), (30-40), (40-60).
  • other preferred value ranges of b can be listed as: (0-40), (0-30), (0-20), (0.5-40), (0.5 ⁇ 30), (0.5 ⁇ 20), (0.5 ⁇ 40), (1 ⁇ 30), (1 ⁇ 20), (5 ⁇ 40), (10 ⁇ 40), (10 ⁇ 30), (10 ⁇ 20 ), (5 ⁇ 30), (5 ⁇ 20).
  • the mole percentage of the monomer unit corresponding to d is 10% to 30 % can be, for example, 10% to 15%, 15% to 20%, or 20% to 30%.
  • the present invention can improve the peeling strength of the binder and at the same time improve the ability to inhibit the expansion of the silicon negative electrode.
  • the molar ratio of the hydroxyl group to the cyano group is 1/4 to 4, which can enable the resulting polymer to maintain high intermolecular hydrogen bonding force, thereby improving
  • the cohesion of the high-pole coating further improves its ability to inhibit expansion.
  • the molar ratio of the hydroxyl group to the cyano group is 1/4 to 1.
  • the molar ratio of the hydroxyl group to the cyano group is 1/4 to 1.5.
  • the molar ratio of the hydroxyl group to the cyano group is 1.5 to 4.
  • the present invention provides a method for preparing an aqueous adhesive as described in the first aspect, comprising the following steps:
  • polymer monomers undergo a polymerization reaction in a reaction solvent to obtain the water-based binder, wherein the polymer monomers include acrylamide monomers, vinyl ether monomers and acrylonitrile. Class singleton.
  • the aqueous binder prepared by the preparation method provided by the invention has high adhesive force, can significantly inhibit the expansion of the silicon negative electrode, and improve the cycle performance of the battery.
  • the polymer monomer further includes an acrylic monomer.
  • the molar ratio of the acrylamide monomer, acrylic acid monomer, vinyl ether monomer and the acrylonitrile monomer is (30 ⁇ 80):(0 ⁇ 50):(5 ⁇ 50):(5-30), for example, it can be 40:30:15:15, 40:30:10:20, 60:0:20:20, 30 :20:40:10 or 30:20:20:30 etc.
  • the total number of moles of the acrylamide monomer, acrylic acid monomer, vinyl ether monomer and acrylonitrile monomer is On a 100% basis, the molar percentage of the acrylamide monomer is 30% to 80%, the molar percentage of the acrylic monomer is 0% to 50%, and the molar percentage of the vinyl ether monomer is 5 % to 50%, the molar percentage of the acrylonitrile monomer is 5% to 30%, preferably, the molar percentage of the acrylonitrile monomer is 10% to 30%.
  • the water-based adhesive will have poor water solubility and low mechanical strength. If the molar percentage of the vinyl ether monomer is too small, the water-based adhesive will have poor flexibility.
  • the acrylamide monomer has a structure represented by formula VI
  • the vinyl ether monomer has a structure represented by formula VII
  • the The acrylonitrile monomer has a structure represented by formula VIII
  • the acrylic acid monomer has a structure represented by formula IX
  • M, R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are the same as those of M, R 1 , R 2 , R 3 , R 4 , in the water-based binder described in the first aspect. Definition of R 5 and R 6 .
  • the mole number of the initiator is 0.02% to 1.0%, for example, it can be 0.02%, 0.1%, 0.3%, 0.6% or 1%, etc.
  • the polymer monomer undergoes a polymerization reaction in a reaction solvent to obtain the water-based binder, which includes the following steps:
  • the aqueous binder may be a water-soluble binder for the silicon negative electrode.
  • the reaction solvent is water, preferably deionized water.
  • the stirring speed is 100-800rpm, for example, it can be 100rpm, 300rpm, 500rpm or 800rpm.
  • step S1 after the polymer monomer is added to the reaction solvent, an inert gas is introduced to remove oxygen in the mixed solution.
  • the inert gas is nitrogen or argon.
  • the initiator is a water-soluble initiator.
  • the initiator includes Including at least one of sodium persulfate, potassium persulfate, ammonium persulfate, ammonium persulfate/sodium sulfite, ammonium persulfate/sodium bisulfite, and hydrogen peroxide/ferrous ion.
  • adding the initiator to the mixed solution to perform a polymerization reaction includes: adding a first initiator to the mixed solution to perform a polymerization reaction. The first polymerization reaction is carried out, and then the second initiator is added to perform the second polymerization reaction.
  • the molar ratio of the first initiator to the second initiator is (0.5-3):1, for example, it can be 0.5:1, 1 :1, 1.5:1, 2:1 or 3:1 etc.
  • the first initiator includes at least one of sodium persulfate, potassium persulfate, and ammonium persulfate.
  • the second initiator is a redox initiator, including ammonium persulfate/sodium sulfite, ammonium persulfate/sodium bisulfite, hydrogen peroxide/ At least one type of ferrous ions.
  • the ferrous ion may be a ferrous salt, such as ferrous sulfate, ferrous chloride, etc.
  • the preparation method provided by the invention can further react the residual monomers and increase the reaction rate by adding a second initiator and limiting the second initiator to a redox initiator, making the polymerization reaction more complete.
  • the temperature of the first polymerization reaction is 40°C to 80°C (for example, it can be 40°C, 45°C, 50°C, 55°C, 60°C, 70°C or 80°C, etc.), the time is 3 to 10h (for example, it can be 3h, 5h, 7h or 10h, etc.);
  • the temperature of the second polymerization reaction is 70°C to 90°C (for example, it can be 70°C, 80°C, or 90°C, etc.), and the time is 1-3h (for example, it can be 1h, 2h, or 3h, etc.).
  • step S2 vacuum is evacuated for 1 to 2 hours, and the absolute vacuum degree is 5 to 50KPa (for example, it can be 5KPa, 10KPa, 15KPa, 20KPa, 40KPa or 50KPa etc.), preferably 10 to 20KPa.
  • the absolute vacuum degree is 5 to 50KPa (for example, it can be 5KPa, 10KPa, 15KPa, 20KPa, 40KPa or 50KPa etc.), preferably 10 to 20KPa.
  • the alkali neutralization includes neutralizing with lithium hydroxide, sodium hydroxide or potassium hydroxide until the pH value is 6.0 ⁇ 9.0 (for example, it can be 6.0, 7.0, 8.0 or 9.0, etc.).
  • the mesh number of the sieved mesh is 150 to 400 mesh, for example, it can be 150 mesh, 200 mesh, 300 mesh or 400 mesh etc.
  • step S2 in the demagnetization, a super-strong magnetic rod demagnetizer is used for demagnetization. Since the prepared aqueous binder will be used in secondary batteries, demagnetization treatment must be performed according to the requirements of its application field.
  • step S2 after the alkali neutralization and before the sieving, the solid content is adjusted to 10 ⁇ 0.5%.
  • the present invention provides a use of a water-based adhesive prepared according to the water-based adhesive described in the first aspect or by the preparation method of the water-based adhesive described in the second aspect, wherein the water-based adhesive Junction agents are used in the preparation of lithium-ion batteries.
  • the water-based adhesive is used Preparation of negative electrode sheets in lithium-ion batteries.
  • a method for preparing a negative electrode sheet using the binder of the present invention is as follows:
  • the binder, conductive agent and active material of the present invention are slurried together in deionized water, and the obtained slurry is coated on the current collector to prepare a negative electrode sheet.
  • the negative active material in the negative electrode sheet includes silicon-based material.
  • the beneficial effects of the present invention include at least one of the following:
  • the water-based binder provided by the present invention has excellent bonding properties and can significantly inhibit the expansion of the silicon negative electrode. At the same time, the prepared pole piece has excellent flexibility and improves the cycle performance of the battery.
  • the present invention uses acrylamide and its derivatives, acrylonitrile and its derivatives and vinyl ether monomers to perform free radical polymerization in an aqueous solution to obtain a water-soluble polymer with certain flexibility.
  • Medium polar groups -OH, -CONR 2 R 3 , -CN, etc. form hydrogen bonds or chemical bonds with silicon particles in the silicon negative electrode, increasing the interaction between the silicon material and graphite, the binder and the active material, A three-dimensional network structure is formed, thereby improving the adhesion force, reducing the expansion of the silicon anode and greatly improving its cycle life.
  • the process parameters that do not indicate specific conditions in the following examples generally follow conventional conditions.
  • the experimental reagents used in the following examples are all conventional biochemical reagents; the experimental reagent dosages, unless otherwise specified, are the dosages of reagents used in routine experimental operations.
  • inventions of the present invention provide an aqueous adhesive.
  • the aqueous adhesive includes a polymer containing at least three monomer units.
  • the polymer includes a first monomer unit, a second monomer unit, and a first monomer unit. unit and a third monomer unit, the first monomer unit has a structure represented by formula I, the second monomer unit has a structure represented by formula II, and the third monomer unit has a structure represented by formula III. Structure,
  • R 1 represents hydrogen, methyl, ethyl, propyl, -CH(CH 3 ) 2 , -CH 2 CH 2 CH 2 CH 3 or -CH 2 CH(CH 3 ) 2
  • R 2 represents hydrogen, methyl base, ethyl, propyl, -CH(CH 3 ) 2 , -CH 2 CH 2 CH 2 CH 3 Or -CH 2 CH(CH 3 ) 2
  • R 3 represents hydrogen, methyl, ethyl, propyl, -CH(CH 3 ) 2 , -CH 2 CH 2 CH 2 CH 3 or -CH 2 CH(CH 3 ) 2
  • R 6 represents hydrogen, methyl, ethyl or -CH(CH 3 ) 2
  • R 5 represents -CH 2 CH 2 OH, CH 2 CH 2 OH, -CH 2 CH 2 OCH 2 CH 2 OH or -(CH 2 CH 2 O) n H, n ⁇ 3;
  • the polymer further includes a fourth monomer unit, and the fourth monomer unit has a structure represented by Formula IV:
  • R 4 represents hydrogen, methyl, ethyl or -CH(CH 3 ) 2 ;
  • M represents H, Li, Na or K;
  • the polymer has the structure shown in formula V:
  • a:b:c:d (30 ⁇ 80):(0 ⁇ 50):(5 ⁇ 50):(5-30); preferably, the monomer units corresponding to a, b, c, d When the total number of moles is 100%, the molar percentage of the monomer unit corresponding to d is 10% to 30%.
  • the water-based binder also includes water, the solid content of the water-based binder is 9.5-10.5%, and the viscosity is 8000-30000 cps.
  • the invention discloses a water-soluble binder for the silicon negative electrode of a lithium ion battery and a preparation method thereof.
  • the technical problem solved is the problems of low bonding force, excessive expansion and poor cycle performance when traditional binders are used in high-silicon negative electrodes (gram capacity ⁇ 500mAh/g).
  • the present invention introduces hydroxyl-containing monomers on the basis of commonly used PAA binders.
  • the resulting binder has high strength and a certain degree of flexibility, which is beneficial when applied to high-silicon negative electrodes.
  • the polar groups on the polymer can form strong hydrogen bonds and chemical bonds with the polar groups on the surface of the silicon material, thereby forming a three-dimensional cross-linked network structure as a whole and improving adhesion.
  • it reduces the expansion of the silicon anode and greatly improves its cycle life.
  • the bonding force will be further improved.
  • embodiments of the present invention provide a method for preparing the water-based adhesive as described in the first aspect, including the following steps:
  • the polymer monomers include acrylamide monomers, vinyl ether monomers and acrylonitrile monomers
  • the polymer monomers also include the acrylic monomers, the acrylamide
  • the molar ratio of the acrylic monomer, the acrylic monomer, the vinyl ether monomer and the acrylonitrile monomer is (30 ⁇ 80): (0 ⁇ 50): (5 ⁇ 50): (5-30) ;
  • the acrylamide monomer has a structure represented by formula VI
  • the vinyl ether monomer has a structure represented by formula VII
  • the acrylonitrile monomer has a structure represented by formula VIII
  • the acrylic acid The quasi-monomer has the structure shown in Formula IX,
  • M, R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are the same as those of M, R 1 , R 2 , R 3 , R 4 , in the water-based binder described in the first aspect. Definition of R 5 and R 6 .
  • the first initiator includes: At least one of sodium sulfate, potassium persulfate, and ammonium persulfate, and the second initiator is a redox initiator, including ammonium persulfate/sodium sulfite, ammonium persulfate/sodium bisulfite, hydrogen peroxide/sodium persulfite,
  • embodiments of the present invention provide a use of the water-based adhesive prepared according to the water-based adhesive described in the first aspect or by the preparation method of the water-based adhesive described in the second aspect, so
  • the aqueous binder is used for the preparation of negative electrode sheets in lithium ion batteries, wherein the negative active material in the negative electrode sheets includes silicon-based materials.
  • a:b:c:d 40:30:15:15.
  • Reaction react for 7 hours; adjust the temperature to 80°C, then add 0.001 mol of redox initiator ammonium persulfate and 0.001 mol of sodium bisulfite, carry out polymerization reaction, and react for 2 hours to remove residual monomers.
  • the value is 7.5, add deionized water to dilute it to obtain a light yellow glue, pass the glue through a 150 mesh sieve, and use a super strong magnetic rod demagnetizer to demagnetize to obtain the target product (water-based binder), which is a water-based binder.
  • the solid content is 10.4% and the viscosity is 21500cps.
  • a:b:c:d 40:30:10:20.
  • a:c:d 60:20:20.
  • a:b:c:d 30:20:20:30.
  • a:b:c:d 40:30:15:15.
  • the preparation method provided in this example is basically the same as that in Example 1, except that acrylamide is replaced by methacrylamide, and the solid content of the prepared water-based adhesive is 10.2% and the viscosity is 12,000 cps.
  • the preparation method provided in this example is basically the same as that in Example 1, except that 0.4 mol of acrylamide is replaced by 0.5 mol of the monomer corresponding to monomer unit a, 0.3 mol of acrylic acid is replaced by 0.1 mol of ethylacrylic acid, and 0.15 mol vinyl glycol ether replaced with 0.3 mol vinyl propylene glycol Ether, replace 0.15 mol of acrylonitrile with 0.1 mol of the monomer corresponding to monomer unit d.
  • the solid content of the prepared water-based adhesive is 9.5% and the viscosity is 13100 cps.
  • a:b:c:d 40:30:15:15.
  • the initiator is added Potassium persulfate 0.001mol, polymerization reaction, reaction 6h; adjust the temperature to 90°C, then add redox initiator ammonium persulfate 0.001mol and sodium bisulfite 0.001mol, polymerization reaction, reaction 1.5h, in order to divide Remove the residual monomer. After the reaction is completed, vacuum for 1 hour to an absolute vacuum of 30KPa to further remove the residual monomer.
  • the preparation method provided in this example is basically the same as that in Example 1, except that 0.4 mol acrylamide is replaced by 0.3 mol N, N-dimethylacrylamide, and 0.3 mol acrylic acid is replaced by 0.2 mol methacrylic acid.
  • the solid content of the prepared water-based binder is 10%, viscosity is 16800cps.
  • the preparation method provided in this example is basically the same as that in Example 1, except that 0.4 mol acrylamide is replaced with 0.45 mol acrylamide, 0.3 mol acrylic acid is replaced with 0.33 mol acrylic acid, and 0.15 mol vinyl glycol ether is replaced. Replaced with 0.17 mol of vinyl glycol ether and 0.15 mol of acrylonitrile with 0.05 mol of acrylonitrile.
  • the solid content of the prepared water-based adhesive was 10% and the viscosity was 17900 cps.
  • CMC carboxymethylcellulose
  • the acrylic resin PAA commercially available from a certain company was used as the binder.
  • the water-based binder provided in this comparative example has the structure shown below:
  • the preparation method provided in this comparative example is basically the same as that in Example 1, except that no vinyl glycol ether is added, and 0.47 mol of acrylamide, 0.35 mol of acrylic acid, and 0.18 mol of acrylonitrile are added.
  • the water-based binder provided in this comparative example includes a polymer with the following structure:
  • the preparation method provided in this comparative example is basically the same as that in Example 1, except that acrylonitrile is not added, and 0.47 mol of acrylamide, 0.35 mol of acrylic acid, and 0.18 mol of vinyl glycol ether are added.
  • the preparation method provided in this comparative example is basically the same as that in Example 1. The difference is that "redox initiator ammonium persulfate 0.001 mol and sodium bisulfite 0.001 mol" are replaced by "potassium persulfate 0.002 mol”. Add redox initiators ammonium persulfate and sodium bisulfite.
  • the binders prepared in Examples 1-9 and Comparative Examples 1-5 are used as silicon negative electrode material binders to prepare negative electrode plates.
  • the method is as follows:
  • Silicon-carbon composite materials (using silicon-based/graphite composite negative electrode materials with a gram capacity of 600mAh/g), Conductive carbon black, single-walled carbon nanotubes and the binder prepared in the examples or comparative examples (take the water-based binder prepared in the examples or comparative examples, where the quality of the solids in the water-based binder is different from that of the silicon-carbon composite material
  • the mass ratio of the silicon-carbon composite material, conductive carbon black, single-walled carbon nanotubes and the binder prepared in the embodiment or comparative example is mixed. The ratio is 93.0:0.5:0.25:6.25. Add an appropriate amount of deionized water according to the total solid content of 35% to make the battery electrode slurry.
  • the uniformly dispersed slurry is passed through a 100-mesh screen, and then coated on a 10 ⁇ m thick copper foil as a current collector. After drying at 120°C for 5 minutes, it is obtained by rolling at room temperature with a unit length load of 10 ⁇ 10 4 N/m. Negative pole piece.
  • a 425060P lithium-ion battery is made with nickel cobalt manganese oxide NCM622 as the positive electrode, a mixed solvent of ethylene carbonate EC: ethyl methyl carbonate EMC: diethyl carbonate DEC in a mass ratio of 3:2:5, containing 1M LiPF6, as the electrolyte, and the existing PP material as the diaphragm.
  • the performance measurement method is as follows:
  • Measurement of peel strength Cut the negative electrode sheet made of the adhesive prepared in the Examples and Comparative Examples into strips of 10 cm A transparent tape is attached to the layer side, peeled off in the 180° direction using a tensile testing machine at a speed of 100mm/min, and the peeling stress is measured.
  • Capacity retention Rate 300th cycle discharge gram capacity/1st cycle discharge gram capacity.
  • the adhesives provided in Examples 1-10 have excellent peel strength, first effect, full-charge expansion and cycle retention rate.
  • the water-based binder provided by the present invention has excellent bonding properties and can significantly inhibit the expansion of the silicon negative electrode.
  • the prepared pole piece has excellent flexibility and improves the cycle performance of the battery. .
  • Example 10 Compared with Example 1, the content of the acrylonitrile monomer described in Example 10 is reduced, and the corresponding expansion inhibition ability is reduced.
  • Example 3 Compared with Example 1, in Comparative Example 3, no vinyl glycol ether was added during the preparation process of the binder, resulting in poor flexibility of the pole piece and a significant decrease in cycle performance.
  • Example 4 Compared with Example 1, in Comparative Example 4, acrylonitrile was not added during the preparation process of the binder, which resulted in a decrease in the peel strength of the pole piece and its ability to suppress expansion at full power.
  • Example 5 Compared with Example 1, in Comparative Example 5, the redox initiators ammonium persulfate and sodium bisulfite were not added during the preparation process of the binder, resulting in a decrease in the peel strength, first effect and cycle performance of the pole piece.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Electrochemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Battery Electrode And Active Subsutance (AREA)
  • Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)

Abstract

L'invention appartient au domaine technique des batteries au lithium-ion, et concerne en particulier un liant à base d'eau et un procédé de préparation et une utilisation de celui-ci. Le liant à base d'eau comprend un polymère contenant au moins trois unités monomères. Le polymère comprend une première unité monomère, une deuxième unité monomère et une troisième unité monomère. La première unité monomère a une structure représentée dans la formule I, la deuxième unité monomère a une structure représentée dans la formule II, et la troisième unité monomère a une structure représentée dans la formule III, R1, R2, R3 et R6 étant identiques ou différents, et représentant chacun indépendamment de l'hydrogène, alkyle linéaire ou alkyle ramifié ; R5 étant un groupe contenant un groupe hydroxyle au niveau d'un groupe terminal. Le liant à base d'eau fourni dans la présente invention présente de bonnes performances de liaison, peut inhiber de manière significative l'expansion d'une électrode négative en silicium, et permet en même temps à la pièce polaire préparée d'avoir une excellente flexibilité, ce qui permet d'améliorer les performances de cycle de la batterie.
PCT/CN2023/126030 2023-03-07 2023-10-23 Liant à base d'eau, et procédé de préparation et utilisation de celui-ci WO2024056103A1 (fr)

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CN116190658A (zh) * 2023-03-07 2023-05-30 深圳市研一新材料有限责任公司 一种水性粘结剂及其制备方法和用途
CN117720869A (zh) * 2024-02-07 2024-03-19 深圳市研一新材料有限责任公司 一种水溶型粘结剂、电池极片及其应用

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WO2022113860A1 (fr) * 2020-11-30 2022-06-02 日本ゼオン株式会社 Composition de liant pour électrodes de batteries secondaires au lithium-ion non aqueux, son procédé de production, solution de liant pour électrodes de batteries secondaires au lithium-ion non aqueux, composition de suspension pour électrodes de batteries secondaires au lithium-ion non aqueux, électrode pour batteries secondaires au lithium-ion non aqueux, et batterie secondaire au lithium-ion non aqueux
KR102468277B1 (ko) * 2021-10-15 2022-11-21 주식회사 한솔케미칼 분리막용 공중합체 및 이를 포함하는 이차전지
CN116190658A (zh) * 2023-03-07 2023-05-30 深圳市研一新材料有限责任公司 一种水性粘结剂及其制备方法和用途

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CN112447973A (zh) * 2019-09-05 2021-03-05 荒川化学工业株式会社 锂离子电池电极用粘合剂水溶液、锂离子电池电极用浆料、锂离子电池电极及锂离子电池
WO2022113860A1 (fr) * 2020-11-30 2022-06-02 日本ゼオン株式会社 Composition de liant pour électrodes de batteries secondaires au lithium-ion non aqueux, son procédé de production, solution de liant pour électrodes de batteries secondaires au lithium-ion non aqueux, composition de suspension pour électrodes de batteries secondaires au lithium-ion non aqueux, électrode pour batteries secondaires au lithium-ion non aqueux, et batterie secondaire au lithium-ion non aqueux
KR102468277B1 (ko) * 2021-10-15 2022-11-21 주식회사 한솔케미칼 분리막용 공중합체 및 이를 포함하는 이차전지
CN116190658A (zh) * 2023-03-07 2023-05-30 深圳市研一新材料有限责任公司 一种水性粘结剂及其制备方法和用途

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