CN116190658A - Water-based adhesive and preparation method and application thereof - Google Patents

Water-based adhesive and preparation method and application thereof Download PDF

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Publication number
CN116190658A
CN116190658A CN202310212349.0A CN202310212349A CN116190658A CN 116190658 A CN116190658 A CN 116190658A CN 202310212349 A CN202310212349 A CN 202310212349A CN 116190658 A CN116190658 A CN 116190658A
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Prior art keywords
aqueous binder
monomer
initiator
polymer
represents hydrogen
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Inventor
梁华晴
刘俊
岳敏
朱文强
王想
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Shenzhen Yanyi New Materials Co Ltd
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Shenzhen Yanyi New Materials Co Ltd
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Priority to CN202310212349.0A priority Critical patent/CN116190658A/en
Publication of CN116190658A publication Critical patent/CN116190658A/en
Priority to PCT/CN2023/126030 priority patent/WO2024056103A1/en
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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

Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly relates to an aqueous binder, a preparation method and application thereof, wherein the aqueous binder comprises a polymer containing at least three monomer units, and the polymer comprises a first monomer unit and a second monomer unitAnd a third monomer unit having a structure represented by formula I, the first monomer unit having a structure represented by formula II, the second monomer unit having a structure represented by formula III,
Figure DDA0004113185220000011
wherein R is 1 、R 2 、R 3 And R is 6 The same or different and each independently represents hydrogen, a linear alkyl group or a branched alkyl group; r is R 5 A group having a hydroxyl group as a terminal group. The water-based adhesive provided by the invention has excellent adhesive property, can obviously inhibit the expansion of a silicon negative electrode, and simultaneously ensures that the prepared pole piece has excellent flexibility, thereby improving the cycle performance of a battery.

Description

Water-based adhesive and preparation method and application thereof
Technical Field
The invention belongs to the technical field of lithium ion batteries, and particularly relates to an aqueous binder, a preparation method and application thereof.
Background
Nowadays, lithium ion batteries are widely applied to products such as mobile phones, computers, electric vehicles and the like, and have great commercial value. The positive electrode material of the lithium ion battery is commercialized at present as an oxide such as LiCoO 2 、LiMn 2 O 4 And LiFePO 4 Wait for the main part; the cathode material is mainly graphite, and because the theoretical capacity of the graphite is low (372 mAh/g), the current requirement of rapid development of electronic information and energy technology is difficult to meet, so that the development of high-capacity silicon-based materials becomes a great subject for the development of lithium ion battery technology. However, since silicon-based materials undergo larger volume expansion and contraction (up to 300%) during charge and discharge, the electrode capacity decays rapidly, resulting in poor cycle performance. Therefore, development of a binder having high bonding strength and capable of reducing expansion of the silicon anode is required to achieve cycle stability of the high-capacity anode.
Silicon negative electrode binders commonly used in the prior art are SBR (styrene-butadiene rubber) binders and PAA-type binders. SBR binders are usually used in combination with CMC, SBR itself has low strength, poor adhesion, and poor inhibition effect on polar plate expansion, so that the cycle performance is often poor when applied to silicon anodes; the pole piece prepared by the PAA adhesive in the prior art has poor flexibility, poor processing performance, difficult recovery after the pole piece structure is damaged, and poor cycle performance.
Therefore, developing an adhesive with excellent adhesive property, flexibility and cycle property to meet the application requirements of high-performance electrode plates and lithium ion batteries is a problem to be solved in the field.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide the aqueous adhesive, and the preparation method and the application thereof.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
in a first aspect, the present invention provides an aqueous binder comprising a polymer comprising at least three monomer units, the polymer comprising a first monomer unit having a structure of formula I, a second monomer unit having a structure of formula II, and a third monomer unit having a structure of formula III,
Figure BDA0004113185210000021
wherein R is 1 、R 2 、R 3 And R is 6 The same or different and each independently represents hydrogen, a linear alkyl group or a branched alkyl group; r is R 5 A group having a hydroxyl group as a terminal group.
Here, R is 1 、R 2 、R 3 Is selected on the basis of maintaining the water solubility of the monomers, R 5 Is selected on the basis of maintaining the water solubility of the monomers.
The water-based adhesive provided by the invention has excellent adhesive property, can obviously inhibit the expansion of a silicon negative electrode, and simultaneously ensures that the prepared pole piece has excellent flexibility, thereby improving the cycle performance of a battery.
In the above aqueous binder, R is preferably 5 Represents a linear alkyl group having 1 to 6 carbon atoms substituted with a hydroxyl group, a branched alkyl group having 1 to 6 carbon atoms substituted with a hydroxyl group, -CH 2 CH 2 OCH 2 CH 2 OH or- (CH) 2 CH 2 O) n H, n.gtoreq.3 (e.g., n may be 3, 5, 7, 10, etc.).
In the above aqueous binder, R is preferably 1 、R 2 、R 3 And R is 6 And each independently represents hydrogen, a linear alkyl group having 1 to 6 carbon atoms, or a branched alkyl group having 1 to 6 carbon atoms.
In the above aqueous binder, R is preferably 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.gtoreq.3 (e.g., n may be 3, 5, 7, 10, etc.).
In the above aqueous binder, R is preferably 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 。
In the above aqueous binder, as a preferred embodiment, the polymer further includes a fourth monomer unit having a structure represented by formula iv:
Figure BDA0004113185210000031
wherein R is 4 Represents hydrogen, straight-chain alkyl or branched alkyl; m represents H, li, na or K.
In the above aqueous binder, R is preferably 4 Represents hydrogen, a linear alkyl group having 1 to 6 carbon atoms or a branched alkyl group having 1 to 6 carbon atoms, e.g. R 4 Represents hydrogen, methyl, ethyl or-CH (CH) 3 ) 2 。
In the above aqueous binder, as a preferred embodiment, the aqueous binder has a solid content of 9.5 to 10.5% and a viscosity of 8000 to 30000cps (for example, the viscosity may be 8000cps, 10000cps, 15000cps, 20000cps, 25000cps, 30000cps, or the like).
In the above aqueous binder, as a preferred embodiment, the polymer has a structure represented by formula v:
Figure BDA0004113185210000032
/>
wherein M represents H, li, na or K;
R 1 represents hydrogen, straight-chain alkyl or branched alkyl, preferably 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, more preferably, 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, straight-chain alkyl or branched alkyl, preferably 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, more preferably, 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, straight-chain alkyl or branched alkyl, preferably R 3 Represents hydrogen, a linear alkyl group having 1 to 6 carbon atoms or a branched alkyl group having 1 to 6 carbon atoms, more preferably, 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, straight-chain alkyl or branched alkyl, preferably 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, e.g. R 4 Represents hydrogen, methyl, ethyl or-CH (CH) 3 ) 2 ；
R 5 A group having a hydroxyl group as a terminal group, preferably, the R 5 Represents a linear alkyl group having 1 to 6 carbon atoms substituted with a hydroxyl group, a branched alkyl group having 1 to 6 carbon atoms substituted with a hydroxyl group, -CH 2 CH 2 OCH 2 CH 2 OH or- (CH) 2 CH 2 O) n H, n.gtoreq.3, more preferably, 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, straight-chain alkyl or branched alkyl, preferably 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, more preferably, the R 6 Represents hydrogen, methyl, ethyl or-CH (CH) 3 ) 2 ；
a: b: c: d= (30-80): (0-50): (5-30), e.g., a: b: c: d may be 40:30:15:15, 40:30:10:20, 60:0:20:20, 30:20:40:10 or 30:20:20:30, etc.; and a, b, c and d are the molar ratio of each monomer unit.
In a second aspect, the present invention provides a method for preparing an aqueous binder according to the first aspect, comprising the steps of:
under the action of an initiator, a polymer monomer is subjected to polymerization reaction in a reaction solvent to obtain the water-based adhesive, wherein the polymer monomer comprises an acrylamide monomer, a vinyl ether monomer and an acrylonitrile monomer.
The aqueous binder prepared by the preparation method provided by the invention has higher binding force, can obviously inhibit the expansion of the silicon negative electrode, and improves the cycle performance of the battery.
In the above method for preparing an aqueous binder, as a preferred embodiment, the polymer monomer further includes an acrylic monomer.
In the above method for preparing an aqueous binder, as a preferred embodiment, the molar ratio of the acrylamide monomer, the acrylic monomer, the vinyl ether monomer and the acrylonitrile monomer is (30-80): 0-50): 5-30, for example, may be 40:30:15:15, 40:30:10:20, 60:0:20:20, 30:20:40:10 or 30:20:20:30, etc.
In the above-mentioned method for producing an aqueous binder, as a preferred embodiment, the total mole percentage of the acrylamide-based monomer, the acrylic monomer, the vinyl ether-based monomer and the acrylonitrile-based monomer is 30 to 80%, the mole percentage of the acrylic monomer is 0 to 50%, the mole percentage of the vinyl ether-based monomer is 5 to 50%, and the mole percentage of the acrylonitrile-based monomer is 5 to 30%.
If the mole percentage of the vinyl ether monomer is too large, the aqueous binder is poor in water solubility and low in mechanical strength, and if the mole percentage of the vinyl ether monomer is too small, the aqueous binder is poor in flexibility.
In the above-mentioned method for producing an aqueous binder, as a preferred embodiment, the acrylamide-based monomer has a structure represented by formula VI, the vinyl ether-based monomer has a structure represented by formula VII, the acrylonitrile-based monomer has a structure represented by formula VIII, the acrylic-based monomer has a structure represented by formula IX,
Figure BDA0004113185210000051
therein, M, R 1 、R 2 、R 3 、R 4 、R 5 And R is 6 Is defined as for pair M, R in the aqueous binder according to the first aspect 1 、R 2 、R 3 、R 4 、R 5 And R is 6 Is defined in (a).
In the above-mentioned method for producing an aqueous binder, as a preferred embodiment, the molar amount of the initiator is 0.02% to 1.0%, for example, 0.02%, 0.1%, 0.3%, 0.6% or 1%, based on 100% of the total molar amount of the polymer monomers.
In the above method for preparing an aqueous binder, as a preferred embodiment, the polymerization reaction of the polymer monomer in the reaction solvent under the action of the initiator is performed to obtain the aqueous binder, which comprises the following steps:
s1, adding the polymer monomer into a reaction solvent, stirring and dispersing to obtain a mixed solution;
s2, adding the initiator into the mixed solution, performing polymerization reaction, and performing vacuumizing, alkali neutralization, sieving and demagnetizing after the reaction is finished to obtain the water-based binder.
Here, the aqueous binder may be a water-soluble binder for a silicon anode.
In the above method for preparing an aqueous binder, as a preferred embodiment, the reaction solvent is water, preferably deionized water.
In the above-mentioned method for producing an aqueous binder, in step S1, the stirring speed may be, for example, 100rpm, 300rpm, 500rpm, 800rpm, or the like, as a preferable embodiment.
In the above-mentioned method for preparing an aqueous binder, in step S1, after the polymer monomer is added to the reaction solvent, an inert gas is introduced to remove oxygen from the mixed solution.
In the above method for preparing an aqueous binder, as a preferred embodiment, the inert gas is nitrogen or argon.
In the above method for preparing an aqueous binder, as a preferred embodiment, the initiator is a water-soluble initiator.
In the above method for preparing an aqueous binder, as a preferred embodiment, the initiator includes at least one of sodium persulfate, potassium persulfate, ammonium persulfate/sodium sulfite, ammonium persulfate/sodium bisulfite, and hydrogen peroxide/ferrous ion.
In the above method for preparing an aqueous binder, as a preferred embodiment, the adding the initiator to the mixed solution to perform a polymerization reaction includes: and adding a first initiator into the mixed solution to perform a first polymerization reaction, and then adding a second initiator to perform a second polymerization reaction.
In the above-mentioned method for producing an aqueous binder, as a preferred embodiment, the molar ratio of the first initiator to the second initiator is (0.5 to 3): 1, and for example, may be 0.5:1, 1:1, 1.5:1, 2:1, 3:1, or the like.
In the above method for preparing an aqueous binder, as a preferred embodiment, the first initiator includes at least one of sodium persulfate, potassium persulfate, and ammonium persulfate.
In the above method for preparing an aqueous binder, as a preferred embodiment, the second initiator is a redox initiator including at least one of ammonium persulfate/sodium sulfite, ammonium persulfate/sodium bisulfite, and hydrogen peroxide/ferrous ion.
Here, the ferrous ion may be a ferrous salt such as ferrous sulfate, ferrous chloride, or the like.
The preparation method provided by the invention can further enable the residual monomer to react and improve the reaction rate by adding the second initiator and limiting the second initiator to be a redox initiator, so that the polymerization reaction is more complete.
In the above-mentioned method for producing an aqueous binder, as a preferred embodiment, the temperature of the first polymerization reaction is 40 to 80 ℃ (for example, 40 ℃, 45 ℃, 50 ℃, 55 ℃, 60 ℃, 70 ℃, 80 ℃ or the like) and the time is 3 to 10 hours (for example, 3 hours, 5 hours, 7 hours, 10 hours or the like); the temperature of the second polymerization reaction is 70 to 90 ℃ (for example, 70 ℃, 80 ℃ or 90 ℃ and the like) and the time is 1 to 3 hours (for example, 1 hour, 2 hours or 3 hours and the like).
In the above-mentioned method for producing an aqueous binder, in step S2, the vacuum is applied for 1 to 2 hours, and the absolute vacuum degree is 5 to 50KPa (for example, 5KPa, 10KPa, 15KPa, 20KPa, 40KPa, 50KPa, etc.), preferably 10 to 20KPa.
In the above-mentioned method for producing an aqueous binder, in step S2, the alkali neutralization includes neutralization with lithium hydroxide, sodium hydroxide or potassium hydroxide to a pH of 6.0 to 9.0 (for example, 6.0, 7.0, 8.0 or 9.0, etc.).
In the above-mentioned method for producing an aqueous binder, in step S2, the mesh number of the screen to be sieved is 150 to 400 mesh, and may be 150 mesh, 200 mesh, 300 mesh, 400 mesh, or the like, for example.
In the above-mentioned method for producing an aqueous binder, in step S2, the demagnetization is performed using a super-strong bar demagnetizer. Since the prepared aqueous binder will be applied to a secondary battery, a demagnetization treatment is performed according to the application field requirements thereof.
In the above-mentioned method for producing an aqueous binder, in step S2, the solid content is adjusted to 10±0.5% after the alkali neutralization and before the sieving.
In a third aspect, the present invention provides the use of an aqueous binder according to the first aspect or an aqueous binder prepared by the method of preparation of an aqueous binder according to the second aspect, for the preparation of a lithium ion battery.
In the use of the aqueous binder, as a preferred embodiment, the aqueous binder is used for preparing a negative electrode sheet in a lithium ion battery.
Methods of preparing a battery anode using a binder are well known to those skilled in the art. Preferably, one method of preparing the negative electrode sheet with the binder of the present invention is as follows:
the binder, the conductive agent and the active substance are subjected to slurry mixing in deionized water, and the obtained slurry is coated on a current collector to prepare the negative plate.
In the above-described use of the aqueous binder, as a preferred embodiment, the negative electrode active material in the negative electrode sheet includes a silicon-based material.
Compared with the prior art, the invention has the beneficial effects that at least one of the following is included:
(1) The water-based adhesive provided by the invention has excellent adhesive property, can obviously inhibit the expansion of a silicon negative electrode, and simultaneously ensures that the prepared pole piece has excellent flexibility, thereby improving the cycle performance of a battery.
(2) The invention adopts acrylamide and its derivative, acrylonitrile and its derivative and vinyl ether monomer to make free radical polymerization in aqueous solution so as to obtain the water-soluble polymer with a certain flexibility, and uses polar group-OH, -CONR in said polymer 2 R 3 The hydrogen bond or chemical bond is formed between CN and silicon particles in the silicon negative electrode, the interaction force between the silicon material and graphite and the interaction force between the binder and the active material are increased, and a three-dimensional network three-dimensional structure is formed, so that the binding force is improved, the expansion of the silicon negative electrode is reduced, and the cycle life of the silicon negative electrode is greatly prolonged.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions in the embodiments of the present invention will be clearly and completely described in the following in conjunction with the embodiments of the present invention. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The examples of the present invention are implemented on the premise of the technical scheme of the present invention, and detailed implementation modes and processes are given, but the protection scope of the present invention is not limited to the following examples, in which the process parameters of specific conditions are not noted, and generally according to conventional conditions.
The endpoints of the ranges and any values disclosed in the present invention are not limited to the precise range or value, and the range or value should be understood to include values close to the range or value. For numerical ranges, one or more new numerical ranges may be obtained in combination with each other between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point values, and are to be considered as specifically disclosed in the present invention.
The process parameters for the specific conditions not noted in the examples below are generally as usual. The experimental reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the dosage of the experimental reagent is the dosage of the reagent in the conventional experimental operation unless specified.
In a first aspect, embodiments of the present invention provide an aqueous binder comprising a polymer comprising at least three monomer units, the polymer comprising a first monomer unit having a structure of formula I, a second monomer unit having a structure of formula II, and a third monomer unit having a structure of formula III,
Figure BDA0004113185210000081
wherein R is 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 ；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；
The polymer further includes a fourth monomer unit having a structure represented by formula IV:
Figure BDA0004113185210000082
wherein R is 4 Represents hydrogen, methyl, ethyl or-CH (CH) 3 ) 2 The method comprises the steps of carrying out a first treatment on the surface of the M represents H, li, na or K;
the polymer has a structure represented by formula v:
Figure BDA0004113185210000091
therein, M, R 1 、R 2 、R 3 、R 4 、R 5 And R is 6 Is defined as the embodiment of the invention for M, R 1 、R 2 、R 3 、R 4 、R 5 And R is 6 A: b: c: d= (30-80): (0-50): (5-30);
the aqueous binder further comprises water, the solid content of the aqueous binder is 9.5-10.5%, and the viscosity is 8000-30000cps.
The invention discloses a water-soluble binder for a silicon negative electrode of a lithium ion battery and a preparation method thereof, and aims to solve the technical problems of low binding force, excessive expansion and poor cycle performance of the traditional binder applied to a high-silicon negative electrode (gram capacity is more than or equal to 500 mAh/g).
According to the invention, on the basis of a common PAA binder, a monomer containing hydroxyl is introduced, and the prepared binder has high strength and certain flexibility, so that the conductive agent and the negative electrode material can be dispersed easily when the binder is applied to a high-silicon negative electrode, and the polar groups on the polymer can form strong hydrogen bonding action and chemical bonding action with the polar groups on the surface of the silicon material, so that a three-dimensional crosslinked network structure is formed on the whole, the binding force is improved, and meanwhile, the expansion of the silicon negative electrode is reduced and the cycle life of the silicon negative electrode is greatly prolonged. In addition, after cyano groups with better complexing ability are introduced, the adhesion is further improved.
In a second aspect, an embodiment of the present invention provides a method for preparing the aqueous binder according to the first aspect, including the steps of:
s1, adding a polymer monomer into deionized water, stirring and dispersing to obtain a mixed solution, and introducing inert gas to remove oxygen in the mixed solution, wherein the stirring speed is 100-800rpm, the inert gas is nitrogen or argon, the polymer monomer comprises an acrylamide monomer, a vinyl ether monomer and an acrylonitrile monomer, the polymer monomer also comprises an acrylic monomer, and the molar ratio of the acrylamide monomer, the acrylic monomer, the vinyl ether monomer and the acrylonitrile monomer is (30-80): (0-50): (5-30); the acrylamide monomer has a structure shown in a formula VI, the vinyl ether monomer has a structure shown in a formula VII, the acrylonitrile monomer has a structure shown in a formula VIII, the acrylic monomer has a structure shown in a formula IX,
Figure BDA0004113185210000101
therein, M, R 1 、R 2 、R 3 、R 4 、R 5 And R is 6 Is defined as for pair M, R in the aqueous binder according to the first aspect 1 、R 2 、R 3 、R 4 、R 5 And R is 6 Is defined in (a).
S2, adding a first initiator into the mixed solution to perform a first polymerization reaction, then adding a second initiator to perform a second polymerization reaction, vacuumizing for 1-2 hours until the absolute vacuum degree is 5-50 KPa, and then performing alkali neutralization, sieving and demagnetizing to obtain the aqueous binder, wherein the sum of the mole numbers of the first initiator and the second initiator is 0.02% -1.0% based on 100% of the total mole number of the polymer monomers; the molar ratio of the first initiator to the second initiator is (0.5-3) 1, the first initiator comprises at least one of sodium persulfate, potassium persulfate and ammonium persulfate, the second initiator is a redox initiator and comprises at least one of ammonium persulfate/sodium sulfite, ammonium persulfate/sodium bisulfite and hydrogen peroxide/ferrous ion, the temperature of the first polymerization reaction is 40-80 ℃ and the time is 3-10 h; the temperature of the second polymerization reaction is 70-90 ℃ and the time is 1-3h, the alkali neutralization comprises neutralization by utilizing lithium hydroxide, sodium hydroxide or potassium hydroxide until the pH value is 6.0-9.0, the mesh number of the screened screen is 150-400, in the demagnetization, a super-strong magnetic bar demagnetizer is used for carrying out the demagnetization, and after the alkali neutralization, the solid content is adjusted to 10+/-0.5% before the screening.
In a third aspect, an embodiment of the present invention provides a use of the aqueous binder according to the first aspect or the aqueous binder prepared by the preparation method of the aqueous binder according to the second aspect, where the aqueous binder is used for preparing a negative electrode sheet in a lithium ion battery, and the negative electrode active material in the negative electrode sheet includes a silicon-based material.
In order to further understand the present invention, the following examples are provided to illustrate the aqueous binder, the preparation method and the use thereof in detail, and the scope of the present invention is not limited by the following examples.
Example 1
The aqueous binder provided in this example includes a polymer having the structure shown below:
Figure BDA0004113185210000111
wherein a: b: c: d=40:30:15:15.
The preparation method of the aqueous binder provided by the embodiment comprises the following steps:
adding 300g of deionized water into a reaction kettle at normal temperature, then sequentially adding 0.4mol of acrylamide, 0.3mol of acrylic acid, 0.15mol of vinyl glycol ether and 0.15mol of acrylonitrile, stirring and dispersing, wherein the stirring speed is 200rpm, introducing nitrogen (the flow rate of nitrogen is 2L/h), introducing nitrogen for 1h, so as to remove oxygen in a solution system (mixed solution), heating to 50 ℃, adding 0.001mol of initiator potassium persulfate after stabilizing the temperature, and carrying out polymerization reaction for 7h; and (3) regulating the temperature to 80 ℃, adding 0.001mol of ammonium persulfate and 0.001mol of sodium bisulfate serving as redox initiators, performing polymerization reaction for 2 hours to remove residual monomers, vacuumizing for 1 hour after the reaction is finished to an absolute vacuum degree of 10KPa to further remove the residual monomers, adding lithium hydroxide monohydrate to neutralize until the pH value is 7.5, adding deionized water to dilute to obtain light yellow glue solution, sieving the glue solution with a 150-mesh sieve, and performing demagnetization by using a super-strong magnetic rod demagnetizer to obtain a target product (aqueous binder), wherein the solid content of the aqueous binder is 10.4%, and the viscosity is 21500cps.
Example 2
The aqueous binder provided in this example includes a polymer having the structure shown below:
Figure BDA0004113185210000112
wherein a: b: c: d=40:30:10:20.
The preparation method of the aqueous binder provided by the embodiment comprises the following steps:
400g of deionized water is added into a reaction kettle at normal temperature, then 0.4mol of acrylamide, 0.3mol of acrylic acid, 0.1mol of vinyl glycol ether and 0.2mol of methacrylonitrile are added in sequence, stirring and dispersing are carried out, the stirring speed is 200rpm, nitrogen is introduced (the flow rate of nitrogen is 2L/h), the time for introducing the nitrogen is 1h, so that oxygen in a solution system (mixed solution) is removed, then the temperature is raised to 60 ℃, the initiator ammonium persulfate is added after the temperature is stabilized, and polymerization reaction is carried out for 5h; and (3) regulating the temperature to 80 ℃, adding 0.001mol of redox initiator ammonium persulfate and 0.001mol of sodium bisulphite, performing polymerization reaction for 2 hours to remove residual monomers, vacuumizing for 1 hour after the reaction is finished to an absolute vacuum degree of 8KPa to further remove the residual monomers, adding lithium hydroxide monohydrate to neutralize until the pH value is 7.6, adding deionized water to dilute to obtain light yellow glue solution, sieving the glue solution with a 150-mesh sieve, and performing demagnetization by using a super-strong magnetic rod demagnetizer to obtain a target product (aqueous binder), wherein the solid content of the aqueous binder is 10.2%, and the viscosity is 14600cps.
Example 3
The aqueous binder provided in this example includes a polymer having the structure shown below:
Figure BDA0004113185210000121
wherein a: c: d=60:20:20.
The preparation method of the aqueous binder provided by the embodiment comprises the following steps:
adding 300g of deionized water into a reaction kettle at normal temperature, then sequentially adding 0.6mol of acrylamide, 0.2mol of vinyl diethylene glycol ether and 0.2mol of acrylonitrile, stirring and dispersing, wherein the stirring speed is 400rpm, introducing nitrogen (the flow rate of the nitrogen is 2L/h), introducing nitrogen for 1h to remove oxygen in a solution system (mixed solution), then heating to 50 ℃, adding 0.001mol of initiator potassium persulfate after the temperature is stable, and carrying out polymerization reaction for 7h; and (3) regulating the temperature to 80 ℃, adding 0.001mol of ammonium persulfate and 0.001mol of sodium bisulfate serving as redox initiators, performing polymerization reaction for 2 hours to remove residual monomers, vacuumizing to an absolute vacuum degree of 12KPa after the reaction is finished to further remove the residual monomers, adding lithium hydroxide monohydrate to neutralize until the pH value is 7.7, adding deionized water to dilute to obtain light yellow glue solution, sieving the glue solution with a 150-mesh sieve, and performing demagnetization by using a super-strong magnetic rod demagnetizer to obtain a target product (aqueous binder), wherein the solid content of the aqueous binder is 10.2%, and the viscosity is 17000cps.
Example 4
The aqueous binder provided in this example includes a polymer having the structure shown below:
Figure BDA0004113185210000122
wherein a: b: c: d=30:20:40:10.
The preparation method of the aqueous binder provided by the embodiment comprises the following steps:
400g of deionized water is added into a reaction kettle at normal temperature, then 0.3mol of acrylamide, 0.2mol of methacrylic acid, 0.4mol of vinyl glycol ether and 0.1mol of acrylonitrile are added in sequence, stirring and dispersing are carried out, the stirring speed is 200rpm, nitrogen is introduced (the flow rate of nitrogen is 2L/h), the time for introducing the nitrogen is 1h, so that oxygen in a solution system (mixed solution) is removed, then the temperature is raised to 50 ℃, the initiator potassium persulfate is added after the temperature is stabilized, and polymerization reaction is carried out for 7h; and (3) regulating the temperature to 80 ℃, adding 0.001mol of ammonium persulfate and 0.001mol of sodium bisulfate serving as redox initiators, performing polymerization reaction for 2 hours to remove residual monomers, vacuumizing for 1 hour after the reaction is finished to an absolute vacuum degree of 15KPa to further remove the residual monomers, adding lithium hydroxide monohydrate to neutralize until the pH value is 7.7, adding deionized water to dilute to obtain light yellow glue solution, sieving the glue solution with a 150-mesh sieve, and performing demagnetization by using a super-strong magnetic rod demagnetizer to obtain a target product (aqueous binder), wherein the solid content of the aqueous binder is 10.1%, and the viscosity is 18000cps.
Example 5
The aqueous binder provided in this example includes a polymer having the structure shown below:
Figure BDA0004113185210000131
wherein a: b: c: d=30:20:20:30.
The preparation method of the aqueous binder provided by the embodiment comprises the following steps:
450g of deionized water is added into a reaction kettle at normal temperature, then 0.3mol of acrylamide, 0.2mol of methacrylic acid, 0.2mol of vinyl diethylene glycol ether and 0.3mol of acrylonitrile are added in sequence, stirring and dispersing are carried out, the stirring speed is 300rpm, nitrogen is introduced (the flow rate of nitrogen is 2L/h), the time for introducing the nitrogen is 1h, so that oxygen in a solution system (mixed solution) is removed, then the temperature is raised to 50 ℃, the initiator potassium persulfate is added after the temperature is stabilized, and polymerization reaction is carried out for 7h; and (3) regulating the temperature to 80 ℃, adding 0.001mol of ammonium persulfate and 0.001mol of sodium bisulfate serving as redox initiators, performing polymerization reaction for 2 hours to remove residual monomers, vacuumizing for 1 hour after the reaction is finished to an absolute vacuum degree of 9KPa to further remove the residual monomers, adding lithium hydroxide monohydrate to neutralize until the pH value is 7.5, adding deionized water to dilute to obtain light yellow glue solution, sieving the glue solution with a 150-mesh sieve, and performing demagnetization by using a super-strong magnetic rod demagnetizer to obtain a target product (aqueous binder), wherein the solid content of the aqueous binder is 10.1%, and the viscosity is 9000cps.
Example 6
The aqueous binder provided in this example includes a polymer having the structure shown below:
Figure BDA0004113185210000141
wherein a: b: c: d=40:30:15:15.
The preparation method provided in this example was substantially the same as that of example 1, except that acrylamide was replaced with methacrylamide, and the prepared aqueous adhesive had a solids content of 10.2% and a viscosity of 12000cps.
Example 7
The aqueous binder provided in this example includes a polymer having the structure shown below:
Figure BDA0004113185210000142
wherein a: b: c: d=50:10:30:10.
The preparation method provided in this example was substantially the same as in example 1 except that 0.4mol of acrylamide was replaced with the monomer corresponding to the 0.5mol of monomer unit a, 0.3mol of acrylic acid was replaced with 0.1mol of ethacrylic acid, 0.15mol of vinyl glycol ether was replaced with 0.3mol of vinyl propylene glycol ether, 0.15mol of acrylonitrile was replaced with the monomer corresponding to the 0.1mol of monomer unit d, and the prepared aqueous adhesive had a solid content of 9.5% and a viscosity of 13100cps.
Example 8
The aqueous binder provided in this example includes a polymer having the structure shown below:
Figure BDA0004113185210000143
wherein a: b: c: d=40:30:15:15.
The preparation method of the aqueous binder provided by the embodiment comprises the following steps:
adding 400g of deionized water into a reaction kettle at normal temperature, sequentially adding 0.4mol of N-isopropyl acrylamide, 0.3mol of isopropyl acrylic acid, 0.15mol of vinyl glycol ether and 0.15mol of acrylonitrile, stirring and dispersing at 400rpm, introducing nitrogen (the flow rate of the nitrogen is 2L/h), introducing nitrogen for 1h to remove oxygen in a solution system (mixed solution), heating to 70 ℃, stabilizing the temperature, adding 0.001mol of initiator potassium persulfate, and carrying out polymerization reaction for 6h; the temperature is adjusted to 90 ℃, then 0.001mol of ammonium persulfate and 0.001mol of sodium bisulphite serving as redox initiators are added for polymerization reaction for 1.5 hours, residual monomers are removed, after the reaction is finished, the reaction is carried out for 1 hour, the absolute vacuum degree is 30KPa, the residual monomers are further removed, then sodium hydroxide monohydrate is added for neutralization until the pH value is 7.5, deionized water is added for dilution, light yellow glue solution is obtained, the glue solution is sieved by a 250-mesh sieve, a super-strong magnetic rod demagnetizer is used for demagnetizing, and a target product (aqueous binder) is obtained, wherein the solid content of the aqueous binder is 10.5%, and the viscosity is 23000cps.
Example 9
The aqueous binder provided in this example includes a polymer having the structure shown below:
Figure BDA0004113185210000151
wherein a: b: c: d=30:20:40:10.
The preparation method provided in this example was substantially the same as in example 1, except that 0.4mol of acrylamide was replaced with 0.3mol of N, N-dimethylacrylamide, 0.3mol of acrylic acid was replaced with 0.2mol of methacrylic acid, 0.15mol of vinyl glycol ether was replaced with 0.4mol of vinyl triethylene glycol ether, 0.15mol of acrylonitrile was replaced with 0.1mol of the monomer corresponding to monomer unit d, and the prepared aqueous adhesive had a solid content of 10% and a viscosity of 16800cps.
Comparative example 1
The styrene butadiene rubber SBR sold by a certain company is used as a binder and is mixed with sodium carboxymethylcellulose (CMC) with the mass ratio of 1:1.
Comparative example 2
An acrylic resin PAA commercially available from a company is used as the binder.
Comparative example 3
The aqueous binder provided in this comparative example has the structure shown below:
Figure BDA0004113185210000161
wherein a: b: d=47:35:18.
The preparation method provided in this comparative example was substantially the same as in example 1, except that no vinyl glycol ether, 0.47mol of acrylamide, 0.35mol of acrylic acid, and 0.18mol of acrylonitrile were added.
Comparative example 4
The aqueous binder provided in this comparative example includes a polymer having the structure shown below:
Figure BDA0004113185210000162
wherein a: b: c=47:35:18.
The preparation method provided in this comparative example was substantially the same as in example 1, except that acrylonitrile, 0.47mol of acrylamide, 0.35mol of acrylic acid, and 0.18mol of vinyl glycol ether were not added.
Comparative example 5
The preparation method provided in this comparative example was substantially the same as in example 1, except that "0.001 mol of ammonium persulfate and 0.001mol of sodium hydrogensulfite as redox initiators" were replaced with "0.002 mol of potassium persulfate" and that the redox initiators ammonium persulfate and sodium hydrogensulfite were not added.
Performance testing
The binders prepared in examples 1 to 9 and comparative examples 1 to 5 were used as binders for silicon negative electrode materials to prepare negative electrode tabs, as follows:
the silicon-carbon composite (using a silicon-based/graphite composite anode material with a gram capacity of 600 mAh/g), the conductive carbon black, the single-walled carbon nanotube and the binder prepared in the example or the comparative example (taking the aqueous binder prepared in the example or the comparative example, wherein the mass ratio of the solid in the aqueous binder to the mass of the silicon-carbon composite is 6.25:93.0), and the mass ratio of the silicon-carbon composite, the conductive carbon black, the single-walled carbon nanotube and the binder prepared in the example or the comparative example (based on the mass of the solid in the binder) is 93.0:0.5:0.25: and 6.25, adding a proper amount of deionized water according to the proportion of 35% of total solid components to prepare the battery pole piece slurry. The uniformly dispersed slurry was passed through a 100-mesh screen, and then coated on a 10 μm thick copper foil as a current collector, and dried at 120℃for 5 minutes, and then at room temperature, the slurry was dried at 10X 10 4 And carrying out load rolling of N/m unit length to obtain the negative electrode plate.
Nickel cobalt lithium manganate NCM622 is used as a positive electrode, and ethylene carbonate EC: ethyl methyl carbonate EMC: diethyl carbonate DEC is prepared from the following components in percentage by mass: 2:5, the mixed solvent contains 1MLiPF6 which is used as electrolyte, and the PP material in the prior art is used as a diaphragm to prepare the 425060P lithium ion battery.
The performance measurement method is as follows:
determination of peel strength: the negative electrode sheets made of the binders prepared in examples and comparative examples were cut into a long shape of 10cm×2.5cm, a steel plate having a thickness of 1mm was adhered to the current collector side with a double-sided tape, a transparent adhesive tape was adhered to the coating layer side, and the sheet was peeled at a speed of 100mm/min in a direction of 180 ° by a tensile tester, and the peel stress was measured.
Measuring the flexibility of the pole piece: a mandrel with a diameter Φ=3mm was placed on the current collector side of the rolled pole piece made of the binders prepared in examples and comparative examples, and a bending experiment was performed, and the state of the pole piece at this time was observed by an optical microscope, and the pole piece was marked as good as o, and the occurrence of falling or cracking was marked as x.
Measuring the initial effect of the battery: at 25 ℃, under the voltage range of 2.5-4.2V, 0.33C is subjected to charge-discharge cycle, and the first coulomb efficiency of the charge-discharge cycle is tested by adopting a constant current method;
full electrical expansion was measured: at 25 ℃, under the voltage range of 2.5-4.2V, after two circles of charge-discharge circulation are carried out on 0.33 ℃, the battery is fully charged again, the battery is disassembled, and the thickness d of the negative plate is tested 2 Let the original thickness of the pole piece be d 1 The full electrical expansion ratio is: (d) 2 -d 1 )/d 1 ×100％。
The 300-week cycle capacity retention rate was measured: at 25 ℃, charging at 0.5-4.2V, and discharging at 1.0C for charge-discharge circulation, wherein the capacity retention rate after 300 weeks of circulation is tested by adopting a constant current method, and the capacity retention rate=300 weeks of circulation discharge gram capacity/1 week of circulation discharge gram capacity.
The test results are shown in tables 1 and 2.
TABLE 1
Figure BDA0004113185210000171
TABLE 2
Project Example 7 Example 8 Example 9
Peel strength (N/m) 76.21 74.28 73.69
Flexibility of pole piece ○ ○ ○
First effect (%) 85.30 85.24 85.27
Full electrical expansion (%) 35.89 36.34 36.18
300 cycle Capacity Retention Rate (%) 81.18 80.92 80.71
As can be seen from tables 1 and 2, the binders provided in examples 1-9 provide very significant improvements in peel strength, initial efficiency, full charge expansion and cycle retention over the commercially available SBR (comparative example 1); compared with the PAA adhesive (comparative example 2) on the market, the adhesive provided in examples 1-9 is also obviously improved in terms of peel strength, pole piece flexibility, initial effect, full-charge expansion and cycle retention, so that the aqueous adhesive provided by the invention has excellent adhesive property, can obviously inhibit the expansion of a silicon negative electrode, and simultaneously enables the prepared pole piece to have excellent flexibility and improve the cycle performance of a battery.
In comparative example 3, the binder was prepared without adding vinyl glycol ether, resulting in poor flexibility of the pole piece and a significant drop in cycle performance, as compared with example 1.
In comparative example 4, acrylonitrile was not added during the preparation of the binder, resulting in a decrease in peel strength of the pole piece, compared with example 1.
In comparison with example 1, in comparative example 5, the redox initiator ammonium persulfate and sodium bisulphite were not added during the preparation of the binder, resulting in a decrease in the peel strength, initial effect and cycle performance of the pole piece.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While still being apparent from variations or modifications that may be made by those skilled in the art are within the scope of the invention.

Claims (10)

1. An aqueous binder comprising a polymer comprising at least three monomer units, the polymer comprising a first monomer unit having a structure of formula I, a second monomer unit having a structure of formula II, and a third monomer unit having a structure of formula III,
Figure FDA0004113185200000011
wherein R is 1 、R 2 、R 3 And R is 6 The same or different and each independently represents hydrogen, a linear alkyl group or a branched alkyl group; r is R 5 A group having a hydroxyl group as a terminal group.
2. The aqueous binder of claim 1 wherein R is 5 Represents a linear alkyl group having 1 to 6 carbon atoms substituted with a hydroxyl group, a branched alkyl group having 1 to 6 carbon atoms substituted with a hydroxyl group, -CH 2 CH 2 OCH 2 CH 2 OH or- (CH) 2 CH 2 O) n H，n≥3；
And/or, the R 1 、R 2 、R 3 And said R 6 And each independently represents hydrogen, a linear alkyl group having 1 to 6 carbon atoms, or a branched alkyl group having 1 to 6 carbon atoms.
3. The aqueous binder of claim 1 wherein R is 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 is more than or equal to 3; the R is 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 The method comprises the steps of carrying out a first treatment on the surface of the The R is 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 The method comprises the steps of carrying out a first treatment on the surface of the The R is 3 Represents hydrogen, methyl, ethyl, propyl, -CH # -, orCH 3 ) 2 、-CH 2 CH 2 CH 2 CH 3 or-CH 2 CH(CH 3 ) 2 The method comprises the steps of carrying out a first treatment on the surface of the The R is 6 Represents hydrogen, methyl, ethyl or-CH (CH) 3 ) 2 。
4. The aqueous binder of any one of claims 1-3 wherein the polymer further comprises a fourth monomer unit having a structure of formula iv:
Figure FDA0004113185200000021
wherein R is 4 Represents hydrogen, straight-chain alkyl or branched alkyl; m represents H, li, na or K.
5. The aqueous binder of claim 4 wherein R is 4 Represents hydrogen, a linear alkyl group having 1 to 6 carbon atoms, or a branched alkyl group having 1 to 6 carbon atoms;
and/or the aqueous binder has a solids content of 9.5 to 10.5% and a viscosity of 8000 to 30000cps.
6. The aqueous binder of claim 4 wherein the polymer has the structure of formula v:
Figure FDA0004113185200000022
therein, M, R 1 、R 2 、R 3 、R 4 、R 5 And R is 6 Is defined in claim 4 to M, R 1 、R 2 、R 3 、R 4 、R 5 And R is 6 A, b, c, d= (30-80): (0-50): (5-30).
7. A method of preparing an aqueous binder according to any one of claims 1 to 6, comprising the steps of:
under the action of an initiator, a polymer monomer is subjected to polymerization reaction in a reaction solvent to obtain the water-based adhesive, wherein the polymer monomer comprises an acrylamide monomer, a vinyl ether monomer and an acrylonitrile monomer.
8. The method of producing an aqueous binder according to claim 7, wherein the polymer monomer further comprises an acrylic monomer, and the molar ratio of the acrylamide monomer, acrylic monomer, vinyl ether monomer and acrylonitrile monomer is (30-80): 0-50): 5-30;
and/or, under the action of an initiator, the polymer monomer is subjected to polymerization reaction in a reaction solvent to obtain the aqueous binder, which comprises the following steps:
s1, adding the polymer monomer into a reaction solvent, stirring and dispersing to obtain a mixed solution;
s2, adding a first initiator into the mixed solution to perform a first polymerization reaction, then adding a second initiator to perform a second polymerization reaction, and performing vacuumizing, alkali neutralization, sieving and demagnetizing after the reaction is completed to obtain the aqueous binder, wherein the molar ratio of the first initiator to the second initiator is (0.5-3): 1, the first initiator comprises at least one of sodium persulfate, potassium persulfate and ammonium persulfate, and the second initiator is a redox initiator comprising at least one of ammonium persulfate/sodium sulfite, ammonium persulfate/sodium bisulfite and hydrogen peroxide/ferrous ions.
9. The method for preparing an aqueous binder according to claim 8, wherein the temperature of the first polymerization reaction is 40 to 80 ℃ for 3 to 10 hours; the temperature of the second polymerization reaction is 70-90 ℃ and the time is 1-3h.
10. Use of an aqueous binder according to any one of claims 1 to 6 or prepared by a method of preparation of an aqueous binder according to any one of claims 7 to 9, characterized in that the aqueous binder is used in the preparation of lithium ion batteries.
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CN110690451B (en) * 2018-07-05 2022-09-13 贝特瑞新材料集团股份有限公司 Conductive aqueous adhesive for lithium ion battery and preparation method and application thereof
KR102336689B1 (en) * 2019-09-05 2021-12-08 아라까와 가가꾸 고교 가부시끼가이샤 Binder aqueous solution for lithium-ion battery electrode, slurry for lithium-ion battery electrode, electrode for lithium-ion battery, and lithium-ion battery
EP4253435A1 (en) * 2020-11-30 2023-10-04 Zeon Corporation Binder composition for nonaqueous lithium ion secondary battery electrodes, method for producing same, binder solution for nonaqueous lithium ion secondary battery electrodes, slurry composition for nonaqueous lithium ion secondary battery electrodes, electrode for nonaqueous lithium ion secondary batteries, and nonaqueous lithium ion secondary battery
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