CN116355122A - Preparation method of silicon-carbon negative electrode water-based adhesive - Google Patents

Preparation method of silicon-carbon negative electrode water-based adhesive Download PDF

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CN116355122A
CN116355122A CN202310342239.6A CN202310342239A CN116355122A CN 116355122 A CN116355122 A CN 116355122A CN 202310342239 A CN202310342239 A CN 202310342239A CN 116355122 A CN116355122 A CN 116355122A
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hydrophobic monomer
hydrophobic
hydrophilic
hydrophilic monomer
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白丰瑞
王银水
赵晓东
罗贺斌
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Fujian Blue Ocean & Black Stone New Material Technology Co ltd
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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
    • C08F220/04—Acids; Metal salts or ammonium salts thereof
    • C08F220/06—Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J133/00—Adhesives based on homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by only one carboxyl radical, or of salts, anhydrides, esters, amides, imides, or nitriles thereof; Adhesives based on derivatives of such polymers
    • C09J133/02—Homopolymers or copolymers of acids; Metal or ammonium salts thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/364—Composites as mixtures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • 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
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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
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    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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    • Y02E60/10—Energy storage using batteries

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Abstract

The application relates to the technical field of aqueous adhesives, and particularly provides a preparation method of a silicon-carbon negative electrode aqueous adhesive, which comprises the following steps: mixing a first hydrophilic monomer and a first hydrophobic monomer, adding the mixture into water, heating to a preset reaction temperature, dropwise adding a first water-soluble initiator solution, continuously reacting for 0-8 hours after dropwise adding, dropwise adding a second hydrophilic monomer and a second hydrophobic monomer, continuously preserving heat for 0-6 hours after dropwise adding, and cooling to obtain the catalyst; the proportion of the first hydrophobic monomer in the weight sum of the first hydrophilic monomer and the first hydrophobic monomer is 10-60%; the proportion of the second hydrophobic monomer in the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer is not more than 20%; the ratio of the weight sum of the second hydrophilic monomer and the second hydrophobic monomer to the weight sum of the first hydrophilic monomer and the first hydrophobic monomer is 4:6-9:1. According to the preparation method, the water-based adhesive can be used for better dispersing hydrophobic graphite active particles and hydrophilic silicon material active particles, and the electrical performance of the lithium ion battery is improved.

Description

Preparation method of silicon-carbon negative electrode water-based adhesive
Technical Field
The application relates to the technical field of aqueous adhesives, in particular to a preparation method of a silicon-carbon negative electrode aqueous adhesive.
Background
The theoretical gram capacity of the simple substance material reaches 4200mAh/g, which is far more than 340mAh/g of the theoretical gram capacity of the graphite material. Therefore, in the prior art, silicon materials such as silicon oxide, silicon carbide and the like are mixed with graphite to form a silicon-carbon anode, so that gram capacity of the anode material is improved, and energy density of the lithium ion battery is improved. However, the volume change of the silicon material is larger in the lithium intercalation and deintercalation process, and the theory exceeds 300%, so that the expansion rate of the pole piece in the charge and discharge process is higher, and how to control the expansion of the pole piece is the key of using the silicon-carbon anode material.
In the preparation of the electrode plate of the lithium ion battery, the negative electrode material adhesive is prepared by dispersing and uniformly mixing the negative electrode material adhesive with electrode active materials and the like, coating the mixture on a current collector such as a copper foil, and then drying and other treatment processes. The binder is an inactive substance in the electrode material, but plays a critical role in the electrochemical performance of the electrode sheet and ultimately the lithium ion battery.
For the silicon carbon anode binder, besides the conventional connection of the electrode active material, the conductive agent and the electrode current collector, the electrode active material, the conductive agent and the current collector have integral connectivity, so that the impedance of the electrode is reduced, and the silicon material is required to be more effectively inhibited from expanding and contracting in a large volume in the circulating process, so that higher circulating stability is realized. Of course, how to disperse the silicon carbon negative electrode active material more effectively is an important factor affecting the cycling stability of the final pole piece, in addition to the suppression of the volume change of the particles by the binder.
Disclosure of Invention
At present, the cyclic stability of the silicon-carbon negative electrode plate prepared by using the polyacrylate adhesive is obviously better than that of a CMC (cellulose) +SBR (styrene butadiene rubber) adhesive. However, the pole piece prepared by using polyacrylic acid derivatives as a binder still has the defects of insufficient cycle times, hard and brittle pole piece and the like, which can be seen in the market at present, and limits the application of the high-capacity silicon-carbon anode material. The main reasons for the fact that the current silicon carbon pole piece is hard and brittle and the circulation is not high enough are as follows: 1) The silicon oxide and graphite particles are not sufficiently dispersed in the pole piece, and agglomeration of the particles still exists, so that uneven stress distribution of the pole piece is caused, and the pole piece is easy to crack; meanwhile, the volume expansion, shrinkage and other changes of the agglomerated active particles are not matched with the volume changes of other better dispersed particles in the lithium removal process, so that the pole piece structure is damaged, the circulation stability is affected, 2) the interaction between the polyacrylic acid derivative adhesive and the particles such as silicon oxide and the like is not strong enough, specifically, the hydrophobicity of the surface of a graphite negative electrode is higher, the surface hydrophilicity of silicon materials such as silicon oxide and silicon carbide is better, and when the interaction between the adhesive and the hydrophobic graphite active particles is better, the adhesive is difficult to interact with the hydrophilic silicon oxide active particles better. Therefore, for the silicon-carbon negative electrode, the water-based adhesive is difficult to achieve better wettability and dispersibility of two materials with different interface properties, and is a technical point for urgent breakthrough.
In order to solve the technical problems, the application provides a preparation method of a silicon-carbon anode water-based adhesive.
The application adopts the following technical scheme:
a preparation method of a silicon-carbon anode water-based adhesive comprises the following steps: will be of the chemical formula CH 2 ＝CR 1 R 2 Is of the formula CH 2 ＝CR 3 R 4 Mixing the first hydrophobic monomer of (2), adding into water, heating to a preset reaction temperature, dripping a first water-soluble initiator solution, continuing to react for 0-8 hours after dripping, and dripping a compound with a chemical formula of CH 2 ＝CR 5 R 6 The second hydrophilic monomer of (C) is CH 2 ＝CR 7 R 8 The second hydrophobic monomer is added dropwise, the heat preservation reaction is continued for 0 to 6 hours, and the temperature is reduced, thus obtaining the hydrophobic monomer;
the proportion of the first hydrophobic monomer in the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer is 10-60%;
the proportion of the second hydrophobic monomer in the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer is not more than 20%;
the weight sum of the second hydrophilic monomer and the second hydrophobic monomer and the weight sum of the first hydrophilic monomer and the first hydrophobic monomer are in a ratio of 4:6-9:1;
R 1 、R 3 、R 5 and R is 7 Independently selected from H or C1-C4 alkyl;
R 2 and R is 6 Independently selected from the group consisting of C1-C18 carboxylates, C1-C18 sulfonates, C1-C18 sulfates, C1-C18 phosphates, hydroxy-containing C1-C4 substituted alkyl groups, amino-containing C1-C4 substituted alkyl groups, carboxy-containing C1-C8 substituted alkyl groups, and CONR of formula 9 R 10 The amide group or formula of (C) is COO (CH) 2 CH 2 O) m R 11 Polyether modified esters, wherein R 9 And R is 10 Independently selected from H, methyl or ethyl, R 11 Selected from H, C-C4 alkyl or C1-C4 substituted alkyl, m=1-30;
R 4 and R is 8 Independently selected from COOR 12 An ester group, a phenyl group, a substituted phenyl group or a nitrile group, wherein R 12 Is a C1-C22 alkyl group.
Preferably, the proportion of the first hydrophobic monomer in the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer is not higher than 50%;
preferably, the proportion of the second hydrophobic monomer in the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer is not more than 15%.
Preferably, the ratio of the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer to the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer is not less than 4:6 and is less than 5:5.
Preferably, the ratio of the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer to the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer is higher than 5:5 and lower than 7:3.
More preferably, the ratio of the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer to the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer is not less than 6:4.
Preferably, the first water-soluble initiator is selected from one or a combination of a polysulfide initiator, a peroxide initiator, an azo initiator and a redox initiator, and the dosage of the first water-soluble initiator is 0.05-1.0% of the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer.
Preferably, the re-dropwise addition chemical formula is CH 2 ＝CR 5 R 6 The second hydrophilic monomer of (C) is CH 2 ＝CR 7 R 8 Simultaneously with the second hydrophobic monomer of (a), a second water-soluble initiator aqueous solution is added dropwise.
More preferably, the second water-soluble initiator is selected from one or a combination of a polysulfide initiator, a peroxide initiator, an azo initiator and a redox initiator, and the dosage of the second water-soluble initiator is 0.05-1.0% of the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer.
Preferably, the re-dropwise addition chemical formula is CH 2 ＝CR 5 R 6 The second hydrophilic monomer of (C) is CH 2 ＝CR 7 R 8 The dripping time of the second hydrophobic monomer is30 minutes to 8 hours.
In summary, the present application has the following beneficial effects:
1. the structural design of the acrylic ester polymer in the aqueous adhesive starts from 2 dimensions of the hydrophobic surface of graphite and the hydrophilic surface of a silicon material, and forms a similar 2-block or 3-block copolymer with sequentially changed hydrophilcity and hydrophobicity, so that the aqueous adhesive has good wettability and dispersibility for active particle substances of electrode materials, namely hydrophobic graphite, hydrophilic silica particles and the like, can effectively improve the wetting dispersion of the active particles, and reduces the aggregation phenomenon of the active particles. The dispersibility of active particles is improved, and the problems of unstable charge and discharge performance and short service life caused by volume change of the silicon material in the lithium intercalation and deintercalation process are also solved. Meanwhile, the active particles are dispersed more uniformly, and the softness of the pole piece is improved.
2. The application adopts a 2-stage polymerization method, and has simple process and easy operation. The 2-stage polymerization method can be divided into 2-stage polymers and 3-stage polymers according to the reaction time between the completion of the first monomer drop and the pre-second monomer drop. And after the first monomer is added dropwise, continuing to react for a period of time until the first hydrophilic monomer and the first hydrophobic monomer are basically reacted, wherein the 2-stage polymer is obtained after the second hydrophilic monomer and the second hydrophobic monomer are added dropwise, and the hydrophobicity of the first-stage polymer obtained by the reaction of the first hydrophilic monomer and the first hydrophobic monomer is higher than the hydrophobicity of the second-stage polymer obtained by the reaction of the second hydrophilic monomer and the second hydrophobic monomer. The first section polymer has better interaction with the hydrophobic carbon black conductive agent and the graphite active particles, and the second section polymer has better interaction with the hydrophilic silicon material, so that synchronous better wetting and dispersion of the graphite active particles and the silicon material active particles are realized. When the continuous reaction time after the first monomer is added dropwise is insufficient to enable the first hydrophilic monomer and the first hydrophobic monomer to basically react, 3-stage polymer is obtained after the second hydrophilic monomer and the second hydrophobic monomer are added dropwise, namely, after the second hydrophilic monomer and the second hydrophobic monomer are added dropwise, the weight ratio of the unreacted hydrophilic monomer and the hydrophobic monomer (the intermediate polymer generated by the reaction) in the reaction system is between the weight ratio of the first hydrophilic monomer and the first hydrophobic monomer and the weight ratio of the second hydrophilic monomer and the second hydrophobic monomer, and the hydrophobicity of the first-stage polymer, the intermediate polymer and the second-stage polymer is sequentially reduced and the hydrophilicity is sequentially increased. The first stage polymer has better interaction with the hydrophobic carbon black conductive agent and the graphite active particles, the middle stage polymer plays a transitional role, or can respectively interact with the carbon black conductive agent, the graphite particles and the silicon material particles according to a hydrophilic and hydrophobic state, and the second stage polymer has better interaction with the hydrophilic silicon material, so that synchronous better dispersion of the graphite active particles and the silicon material active particles is realized.
3. According to the method, the wetting and dispersing capacity of the aqueous adhesive is adjusted by adjusting the weight ratio of the hydrophilic monomer to the hydrophobic monomer in the 2-stage polymerization method, the weight ratio of the first-stage monomer (namely the first hydrophilic monomer and the first hydrophobic monomer) to the weight ratio of the second-stage monomer (namely the second hydrophilic monomer and the second hydrophobic monomer) and the polymerization process, and the aqueous adhesive with good wetting and dispersing capacities on both hydrophobic graphite and hydrophilic silicon materials is obtained, and has strong cohesiveness.
Drawings
Fig. 1 is a stability test result of the negative electrode slurry obtained from the aqueous binder of example 1.
Fig. 2 is a stability test result of the negative electrode slurry obtained from the aqueous binder of comparative example 1.
FIG. 3 is a graph showing the AC impedance of example 1, comparative example 2, and comparative example 5;
wherein curve a-example 1, curve b-comparative example 2, curve c-comparative example 5.
FIG. 4 is a graph of cycle stability versus comparative example 1 and comparative example 4;
wherein curve d-example 1, curve e-comparative example 4.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below.
Throughout the specification, unless specifically indicated otherwise, the terms used herein should be understood as meaning as commonly used in the art. Accordingly, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification will control.
The application provides a preparation method of a silicon-carbon negative electrode water-based adhesive, which comprises the following steps: will be of the chemical formula CH 2 ＝CR 1 R 2 Is of the formula CH 2 ＝CR 3 R 4 Mixing the first hydrophobic monomer of (2), adding into water, heating to a preset reaction temperature, dripping a first water-soluble initiator solution, continuing to react for 0-8 hours after dripping, and dripping a compound with a chemical formula of CH 2 ＝CR 5 R 6 The second hydrophilic monomer of (C) is CH 2 ＝CR 7 R 8 The second hydrophobic monomer is added dropwise, the heat preservation reaction is continued for 0 to 6 hours, and the temperature is reduced, thus obtaining the hydrophobic monomer;
the proportion of the first hydrophobic monomer in the weight sum of the first hydrophilic monomer and the first hydrophobic monomer is 10-60%; the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer refers to the weight of the composition composed of the first hydrophilic monomer and the first hydrophobic monomer.
The proportion of the second hydrophobic monomer in the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer is not more than 20%; the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer refers to the weight of the composition composed of the second hydrophilic monomer and the second hydrophobic monomer.
The weight ratio of the second hydrophilic monomer to the second hydrophobic monomer to the weight ratio of the first hydrophilic monomer to the weight ratio of the second hydrophobic monomer to the weight ratio of the first hydrophobic monomer to the weight ratio of the second hydrophilic monomer to the weight ratio of the second hydrophobic monomer to the weight ratio of the first hydrophilic monomer to the weight ratio of the second hydrophobic monomer to the weight ratio of the second hydrophilic monomer to the weight ratio of the first hydrophobic monomer to the weight ratio of the first hydrophilic monomer to the weight ratio of the second hydrophilic monomer to the;
R 1 、R 3 、R 5 and R is 7 Independently selected from H or C1-C4 alkyl;
R 2 and R is 6 Representing a hydrophilic functional group. R is R 2 And R is 6 Independently selected from the group consisting of C1-C18 carboxylates, C1-C18 sulfonates, C1-C18 sulfates, C1-C18 phosphates, hydroxyl-containing C1-C4 substituted alkyl groups, amine-containing C1-C4 substituted alkyl groups, and carboxyl-containing groupsC1-C8 substituted alkyl of the formula CONR 9 R 10 The amide group or formula of (C) is COO (CH) 2 CH 2 O) m R 11 Polyether modified esters, wherein R 9 And R is 10 Independently selected from H, methyl or ethyl, R 11 Selected from H, C-C4 alkyl or C1-C4 substituted alkyl, m=1-30;
R 4 and R is 8 Representing a hydrophobic functional group. R is R 4 And R is 8 Independently selected from COOR 12 An ester group, a phenyl group, a substituted phenyl group or a nitrile group, wherein R 12 Is a C1-C22 alkyl group.
In the present application, the first hydrophilic monomer and the second hydrophilic monomer may be selected from Acrylic Acid (AA), methacrylic acid (MAA), sodium acrylate (AANa), lithium acrylate (AALi), sodium methacrylate (MAANa), lithium Methacrylate (MAALi), hydroxyethyl methacrylate (HEMA), hydroxyethyl acrylate (HEA), hydroxypropyl methacrylate (HPMA), hydroxypropyl acrylate (HPA), acrylamide (AM), N-Dimethylacrylamide (DMAA), monomethoxy polyether (meth) acrylate, and the like, respectively, by way of example. The first and second hydrophobic monomers may be respectively selected from Acrylonitrile (AN), methyl Methacrylate (MMA), methyl Acrylate (MA), ethyl Methacrylate (EMA), ethyl Acrylate (EA), lauryl Methacrylate (LMA), lauryl Acrylate (LA), stearyl Methacrylate (SMA), stearyl Acrylate (SA), isooctyl methacrylate (2-EHA), isooctyl acrylate (2-EHMA), n-Butyl Methacrylate (BMA), n-Butyl Acrylate (BA), styrene (St), p-methylstyrene, and the like.
In a preferred embodiment of the present application, the ratio of the first hydrophobic monomer in the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer is not higher than 50%; in a more preferred embodiment, the proportion of the first hydrophobic monomer in the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer is less than 30%; in yet a more preferred embodiment, the proportion of the first hydrophobic monomer in the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer is higher than 35% and lower than 50%. It may still further be preferred that the proportion of the first hydrophobic monomer in the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer is higher than 40% and lower than 50%.
In a preferred embodiment of the present application, the proportion of the second hydrophobic monomer in the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer is not more than 15%.
In this application, it is more preferable that the ratio of the first hydrophobic monomer in the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer is not lower than the ratio of the second hydrophobic monomer in the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer. It is further preferred that the proportion of the first hydrophobic monomer in the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer is 5% or more higher than the proportion of the second hydrophobic monomer in the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer. That is, for example, the proportion of the second hydrophobic monomer in the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer is 10%, and the proportion of the first hydrophobic monomer in the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer is not less than 15%, and may be 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% or 30%. For example, the proportion of the second hydrophobic monomer in the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer is 15%, and the proportion of the first hydrophobic monomer in the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer is not less than 20%, and may be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% or 30%. Still further preferably, the proportion of the first hydrophobic monomer in the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer is 10% or more higher than the proportion of the second hydrophobic monomer in the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer.
In a preferred embodiment of the present application, the ratio of the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer to the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer is not less than 4:6 and is less than 5:5. That is, the ratio of the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer to the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer is between 4:6 and 5:5, but does not include 5:5.
In a preferred embodiment of the present application, the ratio of the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer to the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer is higher than 5:5 and lower than 7:3. That is, the ratio of the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer to the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer is between 5:5 and 7:3, but does not include 5:5 and 7:3.
By adjusting the weight sum of the second hydrophilic monomer and the second hydrophobic monomer and the weight sum of the first hydrophilic monomer and the first hydrophobic monomer in the above-described range, good wetting and dispersing ability of the aqueous binder to the hydrophobic graphite active particles and the hydrophilic silica active particles can be achieved.
In a more preferred embodiment of the present application, the ratio of the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer to the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer is not less than 6:4. That is, the ratio of the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer to the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer is between 6:4 and 7:7, but does not include 7:3.
Further adjusting the weight sum of the second hydrophilic monomer and the second hydrophobic monomer and the weight sum of the first hydrophilic monomer and the first hydrophobic monomer in the above range can achieve better wetting and dispersing ability of the aqueous binder to the hydrophobic graphite active particles and the hydrophilic silica active particles.
In a preferred embodiment of the present application, the first water-soluble initiator is selected from one or a combination of several of a persulfate initiator, a peroxide initiator, an azo initiator and a redox initiator, and the amount of the first water-soluble initiator is 0.05-1.0% of the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer. In a more preferred embodiment, the first water-soluble initiator is present in an amount of from 0.2 to 1.0% by weight of the sum of the first hydrophilic monomer and the first hydrophobic monomer. In a further preferred embodiment, the first water-soluble initiator is used in an amount of 0.3 to 0.8% by weight, specifically, 0.3%, 0.4%, 0.5%, 0.6%, 0.7% or 0.8% by weight of the sum of the first hydrophilic monomer and the first hydrophobic monomer.
In a preferred embodiment of the present application, the re-dropwise addition chemical formula is CH 2 ＝CR 5 R 6 The second hydrophilic monomer of (C) is CH 2 ＝CR 7 R 8 Is a second thinning of (2)And (3) dropwise adding a second water-soluble initiator aqueous solution while water monomer.
In a more preferred embodiment of the present application, the second water-soluble initiator is selected from one or a combination of several of a persulfate initiator, a peroxide initiator, an azo initiator and a redox initiator, and the amount of the second water-soluble initiator is 0.05-1.0% of the sum of the weight of the second hydrophilic monomer and the weight of the second hydrophobic monomer. In a further preferred embodiment, the second water-soluble initiator is present in an amount of 0.1 to 1.0% by weight of the sum of the second hydrophilic monomer and the second hydrophobic monomer. In a still further preferred embodiment, the second water-soluble initiator is used in an amount of 0.2 to 0.5%, in particular, 0.2%, 0.3%, 0.4% or 0.5% of the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer.
In the present application, the first water-soluble initiator and the second water-soluble initiator may be respectively selected from persulfate initiators, and may be, for example, ammonium persulfate, potassium persulfate, sodium persulfate, or the like; the first water-soluble initiator and the second water-soluble initiator may also be independently selected from peroxide initiators, for example, from hydrogen peroxide; the first water-soluble initiator and the second water-soluble initiator may also be selected from azo-based initiators, for example, azo diisobutylamidine hydrochloride (AIBA), azo diiso Ding Mi-ine hydrochloride (AIBI), etc.; the first water-soluble initiator and the second water-soluble initiator may also be selected from redox initiators, respectively, and may be selected from ammonium persulfate/sodium bisulfite, potassium persulfate/sodium bisulfite, hydrogen peroxide/tartaric acid, hydrogen peroxide/sodium metabisulfite, ammonium persulfate/ferrous sulfate, hydrogen peroxide/ferrous sulfate, and the like, for example.
In a preferred embodiment of the present application, the re-dropwise addition chemical formula is CH 2 ＝CR 5 R 6 The second hydrophilic monomer of (C) is CH 2 ＝CR 7 R 8 The second hydrophobic monomer of (2) is added dropwise for 30 minutes to 8 hours. In a more preferred embodiment, the re-dropwise addition formula is CH 2 ＝CR 5 R 6 The second hydrophilic monomer of (C) is CH 2 ＝CR 7 R 8 The second hydrophobic monomer of (2) was added dropwise over 1 hour-4 hours.
In the present application, the second water-soluble initiator is added dropwise for a time not exceeding or exceeding the re-dropwise addition chemical formula CH 2 ＝CR 5 R 6 The second hydrophilic monomer of (C) is CH 2 ＝CR 7 R 8 Is added to the mixture at a time of dropping the second hydrophobic monomer. For example, the above re-dropwise addition chemical formula is CH 2 ＝CR 5 R 6 The second hydrophilic monomer of (C) is CH 2 ＝CR 7 R 8 The second hydrophobic monomer of (2) may be added dropwise for 4 hours, and the second water-soluble initiator may be added dropwise for 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, or 6 hours, etc.
In the present application, the concentration of the first water-soluble initiator solution and the second water-soluble initiator solution is not particularly limited, and may be 1 to 10wt%, for example, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, or 10wt%.
In the present application, the continued reaction time after the completion of the dropwise addition of the first initiator aqueous solution has an influence on the acrylate polymer structure of the aqueous adhesive. When the reaction is continued for a long period of time, such as 6 hours, 7 hours or 8 hours, the first hydrophilic monomer and the first hydrophobic monomer react more completely, and when the second hydrophilic monomer and the second hydrophobic monomer are added dropwise, the composition of the monomer being reacted in the reaction system is substantially the same as the composition of the second hydrophilic monomer and the second hydrophobic monomer, the acrylate polymer is a 2-stage polymer, the 1 st stage is composed of the first hydrophilic monomer and the first hydrophobic monomer, and the 2 nd stage is composed of the second hydrophilic monomer and the second hydrophobic monomer. When the continuous reaction time is insufficient, more unreacted first hydrophilic monomer and first hydrophobic monomer are added into the reaction system, and the second hydrophilic monomer and the second hydrophobic monomer are added dropwise, wherein the composition of the hydrophilic monomer and the hydrophobic monomer which are undergoing reaction in the reaction system is between the composition of the first hydrophilic monomer and the first hydrophobic monomer and the composition of the second hydrophilic monomer and the second hydrophobic monomer; along with the progress of the polymerization reaction and the continuous dropwise addition of the second hydrophilic monomer and the second hydrophobic monomer, the compositions of the hydrophilic monomer and the hydrophobic monomer in the reaction system are more and more similar to the compositions of the second hydrophilic monomer and the second hydrophobic monomer until the compositions of the hydrophilic monomer and the hydrophobic monomer in the reaction system are equivalent to the compositions of the second hydrophilic monomer and the second hydrophobic monomer, the acrylic ester polymer is a 3-segment polymer, and an intermediate transition segment exists between the 1 st segment and the 2 nd segment.
In the method for producing a silicon carbon anode aqueous binder of the present application, the stirring speed of the reaction system is not particularly limited, and may be 100 to 1000rpm, or further, may be 200 to 600rpm, and may be, for example, 200rpm, 250rpm, 300rpm, 350rpm, 400rpm, 450rpm, 500rpm, 550rpm, or 600rpm.
The following describes the preparation method of the silicon carbon anode aqueous binder of the present application in detail with reference to examples, comparative examples and experimental data. Unless otherwise indicated, the parts in the examples and comparative examples below are parts by weight.
Example 1
200 parts of water, 24 parts of MAA monomer and sodium bicarbonate are added to adjust the pH to be neutral, 8 parts of EA monomer and 8 parts of HEA monomer are added, stirring is carried out at 200rpm, the monomers are fully mixed, the temperature is raised to 70 ℃, 30 parts of ammonium persulfate aqueous solution with the concentration of 3wt% is dropwise added, the dropwise addition is carried out for 240min, and the temperature is kept for 1h after the dropwise addition is finished; and (3) dropwise adding 6 parts of EA monomer and 54 parts of AA monomer for 240min, simultaneously dropwise adding 10 parts of ammonium persulfate aqueous solution with the concentration of 2wt% for 270min, keeping the reaction temperature of 70 ℃ for 2 h after the dropwise adding of the ammonium persulfate aqueous solution is finished, and adding deionized water and sodium carbonate solution to adjust the solid content and pH of the adhesive to be neutral after the heat preservation is finished, so that the solid content of the aqueous adhesive is 15.2%, and the viscosity (25 ℃) is 3700 mPa.s.
Example 2
250 parts of water, 20 parts of MAA monomer and sodium bicarbonate are added to adjust the pH to be neutral, 9 parts of EA monomer and 7 parts of HEA monomer are added, stirring is carried out at 200rpm, the monomers are fully mixed, the temperature is raised to 70 ℃, 30 parts of ammonium persulfate aqueous solution with the concentration of 3wt% is dropwise added, the dropwise addition is carried out for 240min, and the temperature is kept for 4h after the dropwise addition; and (3) dropwise adding 6 parts of EA monomer and 58 parts of MAA monomer for 300min, simultaneously dropwise adding 10 parts of ammonium persulfate aqueous solution with the concentration of 2wt% for 330min, keeping the reaction temperature at 70 ℃ for 2 h after the dropwise adding of the ammonium persulfate aqueous solution, and adjusting the solid content and pH of the adhesive to be neutral by adding deionized water and sodium carbonate solution after the heat preservation, wherein the solid content of the prepared aqueous adhesive is 15.0%, and the viscosity (25 ℃) is 3800 mPa.s.
Example 3
200 parts of water and 25 parts of MAA monomer are added into a reaction bottle, sodium bicarbonate is added to adjust the pH to be neutral, 25 parts of 2-EHA monomer and 5 parts of HEA monomer are added, stirring is carried out at 200rpm, the monomers are fully mixed, the temperature is raised to 70 ℃, 30 parts of ammonium persulfate aqueous solution with the concentration of 3wt% is dropwise added, 300 minutes of the aqueous solution is dropwise added, 6.5 parts of EA and 38.5 parts of MAA monomer are continuously dropwise added after the dropwise addition is finished, the dropwise addition time is 240 minutes, 10 parts of ammonium persulfate aqueous solution with the concentration of 2wt% is simultaneously started to be dropwise added, the dropwise addition time is 210 minutes, the monomers are dropwise added, the reaction temperature is kept at 70 ℃ for 4 hours, the heat preservation is finished, deionized water and sodium carbonate solution are added to adjust the solid content and the pH of the adhesive to be neutral, and the solid content of the aqueous adhesive is 18.2%, and the viscosity (25 ℃) is 4600 mPa.s.
Example 4
200 parts of water, 24 parts of AA monomer and sodium bicarbonate are added to adjust the pH to be neutral, 16 parts of 2-EHA are added, stirring is carried out at 200rpm, the monomers are fully mixed, the temperature is raised to 70 ℃, 30 parts of ammonium persulfate aqueous solution with the concentration of 3wt% is dropwise added, the dropwise addition is carried out for 300min, and the temperature is kept for 120min after the dropwise addition is finished; 54 parts of MAA monomer and 6 parts of EA monomer are added dropwise for 180min, 10 parts of ammonium persulfate aqueous solution with the concentration of 2wt% is added dropwise for 240min, the reaction temperature of 70 ℃ is kept for 3h after the completion of the dropwise addition of the ammonium persulfate aqueous solution, deionized water and sodium carbonate solution are added after the completion of the heat preservation, the solid content and pH of the adhesive are regulated to be neutral, and the solid content of the aqueous adhesive is 17.9%, and the viscosity (25 ℃) is 4500 mPa.s.
Example 5
200 parts of water and 24 parts of AA monomer are added into a reaction bottle, sodium bicarbonate is added to adjust the pH to be neutral, 16 parts of 2-EHA is added, stirring is carried out at 200rpm, the monomers are fully mixed, the temperature is raised to 70 ℃, 30 parts of ammonium persulfate aqueous solution with the concentration of 3wt% is added dropwise, the dropwise addition is carried out for 300min, the dropwise addition is finished, the reaction is carried out for 1 hour under the heat preservation condition, 60 parts of MAA monomer is continuously added dropwise for 180min, meanwhile, 10 parts of ammonium persulfate aqueous solution with the concentration of 2wt% is started to be added dropwise, the dropwise addition is carried out for 210min, the ammonium persulfate aqueous solution is added dropwise, the reaction is carried out for 3 hours under the reaction temperature of 70 ℃, the heat preservation is finished, deionized water and sodium carbonate solution are added to adjust the solid content and the pH of the adhesive to be neutral, and the solid content of the aqueous adhesive is 16.1%, and the viscosity (25 ℃) is 4000 mPa.
Example 6
200 parts of water and 45 parts of AA monomer are added into a reaction bottle, sodium bicarbonate is added to adjust the pH to be neutral, 15 parts of 2-EHA is added, stirring is carried out at 200rpm, the monomers are fully mixed, the temperature is raised to 70 ℃, 30 parts of ammonium persulfate aqueous solution with the concentration of 3wt% is added dropwise, the dropwise addition is carried out for 300min, the dropwise addition is finished, the reaction is carried out for 1.5 hours under the heat preservation, 38 parts of MAA monomer and 2 parts of EA monomer are continuously added dropwise, the dropwise addition is carried out for 180min, 10 parts of ammonium persulfate aqueous solution with the concentration of 2wt% is simultaneously started to be added dropwise, the dropwise addition is carried out for 210min, the ammonium persulfate aqueous solution is added to be ended, the reaction is carried out at the temperature of 70 ℃ for 3 hours under the heat preservation, deionized water and sodium carbonate solution are added to adjust the solid content and pH of the adhesive to be neutral, and the solid content of the aqueous adhesive is 18.1%, and the viscosity (25 ℃) is 4600 mPa.s.
Comparative example 1
200 parts of water, 54 parts of AA monomer and sodium bicarbonate are added to adjust the pH to be neutral, 6 parts of EA monomer are added, stirring is carried out at 200rpm, the monomers are fully mixed, the temperature is raised to 70 ℃, 30 parts of ammonium persulfate aqueous solution with the concentration of 3wt% is dropwise added, the dropwise addition is completed for 240min, and the temperature is kept for 1h; and (3) dropwise adding 24 parts of MAA monomer, 8 parts of EA monomer and 8 parts of HEA monomer for 240min, simultaneously dropwise adding 10 parts of ammonium persulfate aqueous solution with the concentration of 2wt% for 270min, finishing dropwise adding the ammonium persulfate aqueous solution, maintaining the reaction temperature at 70 ℃ for 2 h, keeping the temperature, finishing heat preservation, adding deionized water and sodium carbonate solution to adjust the solid content and pH of the adhesive to be neutral, and obtaining the aqueous adhesive with the solid content of 15.2% and the viscosity (25 ℃) of 3600 mPa.s.
Comparative example 2
200 parts of water, 8 parts of MAA monomer and sodium bicarbonate are added to adjust the pH to be neutral, 28 parts of EA monomer and 4 parts of HEA monomer are added, stirring is carried out at 200rpm, the monomers are fully mixed, the temperature is raised to 70 ℃, 30 parts of ammonium persulfate aqueous solution with the concentration of 3wt% is dropwise added, the dropwise addition is carried out for 240min, and the temperature is kept for 1h after the dropwise addition is finished; and (3) dropwise adding 6 parts of EA monomer and 54 parts of AA monomer for 240min, simultaneously dropwise adding 10 parts of ammonium persulfate aqueous solution with the concentration of 2wt% for 270min, keeping the reaction temperature of 70 ℃ for 2 h after the completion of dropwise adding of the ammonium persulfate aqueous solution, and adding deionized water and sodium carbonate solution to adjust the solid content and pH of the adhesive to be neutral after the completion of heat preservation, wherein the solid content of the prepared aqueous adhesive is 15.5%, and the viscosity (25 ℃) is 3800 mPa.s.
Comparative example 3
200 parts of water, 14 parts of MAA monomer and sodium bicarbonate are added to adjust the pH to be neutral, 49 parts of EA monomer and 7 parts of HEA monomer are added, stirring is carried out at 200rpm, the monomers are fully mixed, the temperature is raised to 70 ℃, 30 parts of ammonium persulfate aqueous solution with the concentration of 3wt% is dropwise added, the dropwise addition is carried out for 240min, and the temperature is kept for 1h after the dropwise addition is finished; 3 parts of EA monomer and 27 parts of AA monomer are added dropwise for 240min, 10 parts of ammonium persulfate aqueous solution with the concentration of 2wt% is added dropwise for 270min, the reaction temperature of 70 ℃ is kept for 2 h, the heat preservation is finished, deionized water and sodium carbonate solution are added to regulate the solid content and pH of the adhesive to be neutral, and the solid content of the aqueous adhesive is 14.9%, and the viscosity (25 ℃) is 3600 mPa.s.
Comparative example 4
200 parts of water, 26 parts of MAA monomer and sodium bicarbonate are added to adjust the pH to be neutral, 4 parts of EA monomer and 10 parts of HEA monomer are added, stirring is carried out at 200rpm, the monomers are fully mixed, the temperature is raised to 70 ℃, 30 parts of ammonium persulfate aqueous solution with the concentration of 3wt% is dropwise added, the dropwise addition is carried out for 240min, and the temperature is kept for 1h after the dropwise addition is finished; and (3) dropwise adding 6 parts of EA monomer and 54 parts of AA monomer for 240min, simultaneously dropwise adding 10 parts of ammonium persulfate aqueous solution with the concentration of 2wt% for 270min, keeping the reaction temperature of 70 ℃ for 2 h after the completion of dropwise adding of the ammonium persulfate aqueous solution, and adding deionized water and sodium carbonate solution to adjust the solid content and pH of the adhesive to be neutral after the completion of heat preservation, wherein the solid content of the prepared aqueous adhesive is 15.0%, and the viscosity (25 ℃) is 3600 mPa.s.
Comparative example 5
200 parts of water, 16 parts of MAA monomer and sodium bicarbonate are added to adjust the pH to be neutral, 20 parts of EA monomer and 4 parts of HEA monomer are added, stirring is carried out at a speed of 200rpm, the monomers are fully mixed, the temperature is raised to 70 ℃, 30 parts of ammonium persulfate aqueous solution with the concentration of 3wt% is dropwise added, the dropwise addition is carried out for 240min, and the temperature is kept for 1h after the dropwise addition is finished; and (3) dropwise adding 18 parts of EA monomer and 32 parts of AA monomer for 240min, simultaneously dropwise adding 10 parts of ammonium persulfate aqueous solution with the concentration of 2wt% for 270min, keeping the reaction temperature of 70 ℃ for 2 h after the dropwise adding of the ammonium persulfate aqueous solution, and adjusting the solid content and pH of the adhesive to be neutral by adding deionized water and sodium carbonate solution after the heat preservation, wherein the solid content of the prepared aqueous adhesive is 15.0%, and the viscosity (25 ℃) is 3600 mPa.s.
Comparative example 6
200 parts of water, 24 parts of MAA monomer and 54 parts of AA monomer are added into a reaction bottle, sodium bicarbonate is added to adjust the pH to be neutral, 14 parts of EA monomer and 8 parts of HEA monomer are added, stirring is carried out at 200rpm, the monomers are fully mixed, the temperature is raised to 70 ℃, 40 parts of ammonium persulfate aqueous solution with the concentration of 3wt% is dropwise added, the dropwise addition is carried out for 240min, the reaction is carried out for 3h under the condition of heat preservation, deionized water and sodium carbonate solution are added to adjust the solid content and the pH of the adhesive to be neutral, and the solid content of the aqueous adhesive is 15.1%, and the viscosity (25 ℃) is 3800 mPa.s.
Test method
Preparation of silicon carbon negative electrode plate
The water addition amount was calculated as 45% based on the slurry solid content before the viscosity of the anode slurry was not adjusted. 3.5 parts of the aqueous binders of examples 1 to 6 and comparative examples 1 to 6 were mixed with 50% water, dispersed at 300rpm for 12 minutes, and then 1 part of SP conductive carbon black was added, stirred at 150rpm for 10 minutes, and then stirred at 800rpm for 120 minutes; the rotation speed is regulated to 300rpm, 47.725 parts of negative electrode material (80% graphite and 20% silicon oxide) is added, dispersed for 20 minutes, and then the mixture is added47.725 parts of negative electrode material and the remaining 50% of water were dispersed for 30 minutes, followed by stirring at a high speed of 800rpm for 120 minutes, followed by adding 0.05 parts of SWCNTs and dispersing at 1000rpm for 30 minutes. After the dispersion is finished, the viscosity (25 ℃) is regulated to 4000-6000 mPa.s, and the discharging is finished by filtering with a 150-mesh filter screen, so as to obtain the cathode slurry. Placing copper foil on a coater, adjusting the scale of a scraper of a wet film preparation device, uniformly pouring the negative electrode slurry, sending into 100 ℃ environment, blowing and baking until drying, and cutting to obtain a product with a specification of 12.5cm×5cm and a single-sided surface density of 70-80g/m 2 Is a negative electrode plate.
Slurry stability test: the test was performed using a formula company turbo LAB stability tester.
Bulk density testing: taking five points in the middle and four corners of the negative pole piece, measuring and recording the thickness of the pole piece by using a screw micrometer, and obtaining the average thickness of the pole piece after removing a maximum value and a minimum value, wherein the stacking density=the pole piece surface density/(the average thickness of the pole piece-the average thickness of the copper foil).
And (3) pole piece resistance test: a clean glass sheet of 20cm by 15cm was selected, weighed m1, the above negative electrode slurry was poured uniformly over the wide end, a 20cm by 8cm coating was uniformly applied by a 250 μm wet film maker, and the glass sheet was sent to an atmosphere of 100deg.C for air drying for 30 minutes. The multimeter was adjusted to the appropriate range, the dried glass sheet was taken out, two current collectors were placed at the wide ends, the coating resistance value was measured, and the coated glass sheet was weighed for m2, then the sheet resistance = coating resistance x (m 2-m 1).
The button cell is manufactured by the following steps:
the assembly sequence is from bottom to top negative electrode shell, elastic sheet, gasket, lithium sheet, electrolyte, diaphragm, electrolyte, electrode sheet and positive electrode shell.
Electrolyte composition: 1M LiPF6 in EC:DMC:EMC =1:1:1;
a diaphragm: celgard 2325;
lithium sheet: coriander 15.0 x 1.0mm;
the first discharge capacity, first coulombic efficiency, ac impedance and cycle test were as follows:
the capacity test current is 0.1C,0.005-1.5V charge and discharge; the impedance sweep was from 100kHz to 0.1Hz.
The results are shown in Table 1 below.
TABLE 1
Figure SMS_1
The data result in table 1 shows that the aqueous adhesive is used for dispersing silicon-carbon anode active particles, has high stacking density and low coating resistance, and has good dispersion performance on anode active materials, and meanwhile, the stability of a pole piece structure can be ensured in the charge-discharge process, so that better cycle performance is brought. Comparative example 1 and example 1, comparative example 1 prepared a hydrophilic segment first and then a hydrophobic segment, the performance of the aqueous adhesive was inferior to example 1; comparative example 2 and example 1, in which the weight ratio of the first hydrophobic monomer in the first hydrophilic monomer and the first hydrophobic monomer composition is increased, the difference between the hydrophilic and hydrophobic properties of the front and rear polymers is too large, and it is difficult to achieve better dispersion for both hydrophobic graphite particles and hydrophilic silica particles; comparative example 3 and example 1, the weight sum of the second hydrophilic monomer and the second hydrophobic monomer in comparative example 3 is lower than the weight sum of the first hydrophilic monomer and the first hydrophobic monomer, the difference between the hydrophilic and hydrophobic properties of the front and rear polymers is too large, and it is difficult to achieve better dispersion for both hydrophobic graphite particles and hydrophilic silica particles; comparing comparative example 4 with example 1, the weight ratio of the second hydrophobic monomer in the second hydrophilic monomer and the second hydrophobic monomer combination is equal to the weight ratio of the first hydrophobic monomer in the first hydrophilic monomer and the first hydrophobic monomer combination, the hydrophilic hydrophobicity of the front and rear stage polymers is too close, and it is difficult to achieve better dispersion for both hydrophobic graphite particles and hydrophilic silica particles; comparative example 5 and example 1, respectively, increased the ratio of the first hydrophobic monomer in the first hydrophilic monomer and the first hydrophobic monomer combination and the ratio of the second hydrophobic monomer in the second hydrophilic monomer and the second hydrophobic monomer combination, it was difficult to achieve better dispersion for both hydrophobic graphite particles and hydrophilic silica particles due to the overall increase in hydrophobicity; in comparison with comparative example 6 and example 1, all of the hydrophilic monomer and the hydrophobic monomer were fed at one time, and the obtained random copolymer was difficult to achieve better dispersion for both the hydrophobic graphite particles and the hydrophilic silica particles.
The present embodiment is merely illustrative of the present application and is not intended to be limiting, and those skilled in the art, after having read the present specification, may make modifications to the present embodiment without creative contribution as required, but is protected by patent laws within the scope of the claims of the present application.

Claims (9)

1. The preparation method of the silicon-carbon anode water-based adhesive is characterized by comprising the following steps of: will be of the chemical formula CH 2 =CR 1 R 2 Is of the formula CH 2 =CR 3 R 4 Mixing the first hydrophobic monomer of (2), adding into water, heating to a preset reaction temperature, dripping a first water-soluble initiator solution, continuing to react for 0-8 hours after dripping, and dripping a compound with a chemical formula of CH 2 =CR 5 R 6 The second hydrophilic monomer of (C) is CH 2 =CR 7 R 8 The second hydrophobic monomer is added dropwise, the heat preservation reaction is continued for 0 to 6 hours, and the temperature is reduced, thus obtaining the hydrophobic monomer;
the proportion of the first hydrophobic monomer in the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer is 10-60%;
the proportion of the second hydrophobic monomer in the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer is not more than 20%;
the weight sum of the second hydrophilic monomer and the second hydrophobic monomer and the weight sum of the first hydrophilic monomer and the first hydrophobic monomer are in a ratio of 4:6-9:1;
R 1 、R 3 、R 5 and R is 7 Independently selected from H or C1-C4 alkyl;
R 2 and R is 6 Independently selected from the group consisting of C1-C18 carboxylates, C1-C18 sulfonates, C1-C18 sulfates, C1-C18 phosphates, hydroxyl-containing C1-C4 substituted alkyls, amine-containing C1-C4 substituted alkanesA C1-C8 substituted alkyl group containing carboxyl and a molecular formula of CONR 9 R 10 The amide group or formula of (C) is COO (CH) 2 CH 2 O) m R 11 Polyether modified esters, wherein R 9 And R is 10 Independently selected from H, methyl or ethyl, R 11 Selected from H, C-C4 alkyl or C1-C4 substituted alkyl, m=1-30;
R 4 and R is 8 Independently selected from COOR 12 An ester group, a phenyl group, a substituted phenyl group or a nitrile group, wherein R 12 Is a C1-C22 alkyl group.
2. The method for preparing a silicon-carbon anode aqueous binder according to claim 1, wherein the proportion of the first hydrophobic monomer in the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer is not higher than 50%;
the method of preparing a silicon carbon anode aqueous binder according to claim 1, wherein the proportion of the second hydrophobic monomer in the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer is not more than 15%.
3. The method for preparing a silicon-carbon anode aqueous binder according to claim 1, wherein the ratio of the weight sum of the second hydrophilic monomer and the second hydrophobic monomer to the weight sum of the first hydrophilic monomer and the first hydrophobic monomer is not lower than 4:6 and lower than 5:5.
4. The method of preparing a silicon carbon anode aqueous binder according to claim 1, wherein the ratio of the weight sum of the second hydrophilic monomer and the second hydrophobic monomer to the weight sum of the first hydrophilic monomer and the first hydrophobic monomer is higher than 5:5 and lower than 7:3.
5. The method for producing a silicon-carbon anode aqueous binder according to claim 5, wherein the ratio of the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer to the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer is not less than 6:4.
6. The preparation method of the silicon-carbon anode water-based adhesive according to claim 1, wherein the first water-soluble initiator is one or a combination of a plurality of polysulfide initiator, peroxide initiator, azo initiator and redox initiator, and the dosage of the first water-soluble initiator is 0.05-1.0% of the sum of the weights of the first hydrophilic monomer and the first hydrophobic monomer.
7. The method for preparing a silicon-carbon anode water-based adhesive according to claim 1, wherein the re-dropwise addition chemical formula is CH 2 =CR 5 R 6 The second hydrophilic monomer of (C) is CH 2 =CR 7 R 8 Simultaneously with the second hydrophobic monomer of (a), a second water-soluble initiator aqueous solution is added dropwise.
8. The preparation method of the silicon-carbon anode water-based adhesive according to claim 8, wherein the second water-soluble initiator is one or a combination of several of a polysulfide initiator, a peroxide initiator, an azo initiator and a redox initiator, and the amount of the second water-soluble initiator is 0.05-1.0% of the sum of the weights of the second hydrophilic monomer and the second hydrophobic monomer.
9. The method for preparing a silicon-carbon anode water-based adhesive according to claim 1, wherein the re-dropwise addition chemical formula is CH 2 =CR 5 R 6 The second hydrophilic monomer of (C) is CH 2 =CR 7 R 8 The second hydrophobic monomer of (2) is added dropwise for 30 minutes to 8 hours.
CN202310342239.6A 2022-12-26 2023-04-01 Preparation method of silicon-carbon negative electrode water-based adhesive Pending CN116355122A (en)

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