CN114671980A - Preparation method of butylbenzene emulsion for negative electrode slurry, product, negative electrode slurry, negative electrode sheet and secondary battery - Google Patents

Preparation method of butylbenzene emulsion for negative electrode slurry, product, negative electrode slurry, negative electrode sheet and secondary battery Download PDF

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CN114671980A
CN114671980A CN202210393000.7A CN202210393000A CN114671980A CN 114671980 A CN114671980 A CN 114671980A CN 202210393000 A CN202210393000 A CN 202210393000A CN 114671980 A CN114671980 A CN 114671980A
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negative electrode
parts
styrene
weight
monomer
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李永芳
高云雷
胡宁
刘关心
于子龙
陈杰
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Huizhou Liwinon Energy Technology Co Ltd
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Huizhou Liwinon Energy 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
    • C08F236/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds
    • C08F236/02—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds
    • C08F236/04—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated
    • C08F236/10—Copolymers of compounds having one or more unsaturated aliphatic radicals, at least one having two or more carbon-to-carbon double bonds the radical having only two carbon-to-carbon double bonds conjugated with vinyl-aromatic 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
    • C08F2/00—Processes of polymerisation
    • C08F2/12—Polymerisation in non-solvents
    • C08F2/16—Aqueous medium
    • C08F2/22—Emulsion polymerisation
    • C08F2/24—Emulsion polymerisation with the aid of emulsifying agents
    • C08F2/26—Emulsion polymerisation with the aid of emulsifying agents anionic
    • 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
    • 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

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The invention provides a preparation method of butylbenzene emulsion for negative electrode slurry, which comprises the following steps: s1, reacting fatty alcohol with a styrene monomer under the action of a catalyst to obtain a modified styrene monomer; s2, mixing the modified styrene monomer obtained in the step S1 with a nano silica compound, a carboxylic acid monomer, a butadiene monomer, a molecular weight regulator, an emulsifier and an initiator, and carrying out emulsion polymerization reaction for 2-15 hours at 40-100 ℃ to obtain a pre-product; and adjusting the pH value of the pre-product to 6-10 to obtain the butylbenzene emulsion. Compared with the prior art, the styrene-butadiene emulsion provided by the invention adopts the styrene monomer modified by the fatty alcohol as one of the raw materials, the obtained styrene-butadiene emulsion has low surface tension and high interfacial activity, and the slurry can be effectively inhibited from flowing to the edge in the coating and baking processes, so that the phenomenon of thick edge is effectively avoided.

Description

Preparation method of butylbenzene emulsion for negative electrode slurry, product, negative electrode slurry, negative electrode sheet and secondary battery
Technical Field
The invention relates to the technical field of secondary batteries, in particular to a preparation method and a product of butylbenzene emulsion for negative electrode slurry, the negative electrode slurry, a negative electrode sheet and a secondary battery.
Background
The occupancy of lithium ion batteries in the market is promoted year by year and the lithium ion batteries are widely applied to consumer batteries and power batteries. The current lithium ion battery manufacturing process is mature more and more, the coating is one of the most critical steps in the lithium ion battery manufacturing process, namely, the uniformly dispersed slurry is uniformly coated on a current collector, and then a pole piece is formed by baking, rolling, slitting and sheet making, and the uniform coating of the slurry is the key for ensuring the performance of a battery core.
The first step of the preparation of the lithium ion battery is raw material stirring, for example, negative electrode stirring is to mix and stir a negative electrode main material, a binder, a conductive agent, deionized water and a thickening agent. The stirring process is a complicated process, and the solid particles are uniformly dispersed by the thickener and water. After stirring, the slurry was transferred to a current collector (copper foil) by a coater. The stirred slurry is a fluid with uniformly dispersed solid-liquid phases, is a non-Newtonian fluid, and can expand when the slurry is extruded, and the expansion effect of the slurry at the edge is more obvious due to the additional stress of the wall surface at the edge of the die head of the coating machine, so that the phenomenon of thick edge which is often called can occur. In addition, in the drying process, the casting phenomenon can occur under the action of the surface tension of the slurry, and the thick edge can also be caused.
To the phenomenon of thick limit, consumption class or conventional structure electricity core can be when before the roll-in with the thick limit district cutting off at coating direction material district edge in order to guarantee that pole piece thickness is even, nevertheless to power battery or novel book core structure, like multi-tab structure and lamination, will keep empty foil district, can't cut off thick limit material district. In contrast, in order to reduce the surface tension of the slurry, a surfactant is usually added during stirring, or the viscosity of the slurry is reduced, so that the casting of the slurry to the edge in the drying process is inhibited, but the effect of the method is limited, and the thick edge phenomenon cannot be effectively solved.
Disclosure of Invention
One of the objects of the present invention is: aiming at the defects of the prior art, the preparation method of the butylbenzene emulsion for the negative electrode slurry is provided, the obtained butylbenzene emulsion can effectively reduce the surface tension and improve the interfacial activity, and therefore the problem of thick edges formed at the edges of the pole pieces in the coating and baking processes of the current negative electrode slurry is effectively solved.
In order to achieve the purpose, the invention adopts the following technical scheme:
a preparation method of styrene-butadiene emulsion for negative electrode slurry comprises the following steps:
s1, reacting fatty alcohol with a styrene monomer under the action of a catalyst to obtain a modified styrene monomer;
s2, mixing the modified styrene monomer obtained in the step S1 with a nano silica compound, a carboxylic acid monomer, a butadiene monomer, a molecular weight regulator, an emulsifier and an initiator, and carrying out emulsion polymerization reaction for 2-15 hours at 40-100 ℃ to obtain a pre-product; and adjusting the pH value of the pre-product to 6-10 to obtain the butylbenzene emulsion.
Preferably, the weight part of the fatty alcohol is 0.5-10 parts, the weight part of the styrene monomer is 20-60 parts, and the weight part of the catalyst is 0.1-3 parts.
Preferably, the fatty alcohol is at least one of n-heptanol, n-octanol, n-nonanol and n-decanol; the catalyst is at least one of dilute sulfuric acid, dilute hydrochloric acid, acetic acid and nitric acid.
Preferably, the modified styrene monomer is 10-80 parts by weight, the nano silica compound is 5-10 parts by weight, the carboxylic acid monomer is 2-5 parts by weight, the butadiene monomer is 10-80 parts by weight, the molecular weight regulator is 1-5 parts by weight, the emulsifier is 0.5-5 parts by weight, and the initiator is 0.2-5 parts by weight.
Preferably, the nanosilicon oxide compound is nanosilicon dioxide or nanosilicon oxide; the carboxylic acid monomer is at least one of acrylic acid, maleic acid, fumaric acid and itaconic acid; the molecular weight regulator is n-dodecyl mercaptan and/or tertiary dodecyl mercaptan; the emulsifier is at least one of sodium dodecyl benzene sulfonate and sodium alkyl diphenyl ether disulfonate; the initiator is at least one of potassium sulfate, sodium sulfate, potassium persulfate and ammonium persulfate.
Preferably, the styrene-butadiene emulsion is characterized in that the solid content of the obtained styrene-butadiene emulsion is 35-55%, the average particle size is 50-200 nm, and the glass transition temperature is-15-10 ℃.
The invention also aims to provide a styrene-butadiene emulsion for negative electrode slurry, which is prepared by the preparation method of the styrene-butadiene emulsion for negative electrode slurry.
The invention also aims to provide a negative electrode slurry, which comprises a negative electrode active material, a conductive agent, a binder and a solvent, wherein the binder is the butylbenzene emulsion for the negative electrode slurry.
The fourth object of the present invention is to provide a negative electrode sheet, comprising a negative electrode current collector and a negative electrode active material layer coated on at least one surface of the negative electrode current collector, wherein the negative electrode active material layer is formed by coating the negative electrode slurry.
The fifth object of the present invention is to provide a secondary battery, comprising a positive plate, a negative plate and a diaphragm spaced between the positive plate and the negative plate, wherein the negative plate is the negative plate.
Compared with the prior art, the invention has the beneficial effects that: according to the preparation method of the styrene-butadiene emulsion, fatty alcohol is adopted to modify styrene, the fatty alcohol and a benzene ring are subjected to substitution reaction to obtain modified styrene, the modified styrene is used as a raw material for preparing the styrene-butadiene emulsion, a hydroxyl functional group in the fatty alcohol can effectively reduce the surface tension of slurry, the interfacial activity is improved, and the phenomenon of thick edge caused by the flowing of the slurry to the edge is inhibited in the coating and baking processes, so that the problem of the thick edge formed at the edge of a pole piece in the coating and baking processes of the conventional negative pole slurry is effectively solved.
Detailed Description
1. Butylbenzene emulsion for negative electrode slurry
The invention aims to provide a preparation method of styrene-butadiene emulsion for negative electrode slurry, which comprises the following steps:
s1, reacting fatty alcohol with a styrene monomer under the action of a catalyst to obtain a modified styrene monomer;
s2, mixing the modified styrene monomer obtained in the step S1 with a nano silica compound, a carboxylic acid monomer, a butadiene monomer, a molecular weight regulator, an emulsifier and an initiator, and carrying out emulsion polymerization reaction for 2-15 hours at 40-100 ℃ to obtain a pre-product; and adjusting the pH value of the pre-product to 6-10 to obtain the butylbenzene emulsion.
In the step S1, the fatty alcohol and the styrene monomer are subjected to substitution reaction, and the fatty alcohol and the benzene ring are subjected to substitution reaction under the action of the acid catalyst to obtain the modified styrene monomer. Compared with styrene for preparing conventional styrene-butadiene rubber, the modified styrene of the invention contains a large amount of hydroxyl functional groups, can effectively improve the activity of the surface of the slurry, can inhibit the slurry from flowing to the edge in the coating and baking processes, and greatly reduces the formation of a thick edge phenomenon. Compared with a method for adding the surfactant or reducing the viscosity of the negative electrode slurry in the stirring process, the method plays a role of the surfactant for modifying the binder, avoids adding the surfactant serving as a new raw material on one hand, and reduces the possibility of uneven stirring of the slurry; on the other hand, the viscosity of the binder is not required to be reduced, and the problem of viscosity reduction of the negative active material layer is avoided, so that the bonding strength of the negative active material layer and the negative current collector is ensured.
In addition, the nano silica compound is added in the styrene-butadiene emulsion provided by the invention, and the nano silica compound and the styrene-butadiene copolymer can form a core-shell structure with the nano silica compound as a core and the styrene-butadiene copolymer as a shell, so that the obtained styrene-butadiene emulsion has the characteristics of small particle size and high viscosity, and the bonding effect of the styrene-butadiene emulsion is effectively ensured.
Specifically, the reaction temperature of the emulsion polymerization may be 40 to 50 ℃, 50 to 60 ℃, 60 to 70 ℃, 70 to 80 ℃, 80 to 90 ℃ or 90 to 100 ℃. Preferably, the reaction temperature of the emulsion polymerization is 40-80 ℃.
In addition, because the modified styrene is adopted, the modified styrene contains a large amount of hydroxyl, the nano silica compound is dispersed together to form silica sol particles, the silica sol has stronger penetrability on a base layer, the styrene-butadiene emulsion can be effectively bonded, and the bonding strength between the negative active material layer and the negative current collector is greatly enhanced.
In some embodiments, the weight parts of the fatty alcohol is 0.5 to 10 parts, the weight parts of the styrene monomer is 20 to 60 parts, and the weight parts of the catalyst is 0.1 to 3 parts.
Specifically, the weight part of the fatty alcohol can be 0.5-2 parts, 2-3 parts, 3-4 parts, 4-5 parts, 5-6 parts, 6-7 parts, 7-8 parts, 8-9 parts or 9-10 parts, and the preferred weight part of the fatty alcohol can be 3-8 parts; the styrene monomer can be 20-25 parts, 25-30 parts, 30-32 parts, 32-35 parts, 35-38 parts, 38-40 parts, 40-43 parts, 43-48 parts, 48-50 parts, 50-53 parts, 53-56 parts or 56-60 parts by weight, and the preferred styrene monomer is 35-50 parts by weight. The proper contents of the fatty alcohol, the styrene monomer and the catalyst can ensure that the fatty alcohol and the styrene monomer can generate sufficient substitution reaction, and provide a foundation for subsequent polymerization reaction with the butadiene monomer.
In some embodiments, the fatty alcohol is at least one of n-heptanol, n-octanol, n-nonanol, n-decanol; the catalyst is at least one of dilute sulfuric acid, dilute hydrochloric acid, acetic acid and nitric acid.
In some embodiments, the modified styrene monomer is 10 to 80 parts by weight, the nanosilicon compound is 5 to 10 parts by weight, the carboxylic acid monomer is 2 to 5 parts by weight, the butadiene monomer is 10 to 80 parts by weight, the molecular weight regulator is 1 to 5 parts by weight, the emulsifier is 0.5 to 5 parts by weight, and the initiator is 0.2 to 5 parts by weight.
Specifically, the modified styrene monomer may be 10 to 20 parts by weight, 20 to 25 parts by weight, 25 to 30 parts by weight, 30 to 35 parts by weight, 35 to 40 parts by weight, 40 to 45 parts by weight, 45 to 50 parts by weight, 50 to 55 parts by weight, 55 to 60 parts by weight, 60 to 65 parts by weight, 65 to 70 parts by weight, 70 to 75 parts by weight or 75 to 80 parts by weight, preferably 30 to 70 parts by weight; the nano silicon-oxygen compound is 5-6 parts, 6-7 parts, 7-8 parts, 8-9 parts or 9-10 parts by weight, and the silicon-oxygen compound is nano-scale, small in particle size, high in permeability and high in binding power; the weight part of the carboxylic acid monomer can be 2-3 parts, 3-4 parts or 4-5 parts; the butadiene monomer can be 10-20 parts, 20-25 parts, 25-30 parts, 30-35 parts, 35-40 parts, 40-45 parts, 45-50 parts, 50-55 parts, 55-60 parts, 60-65 parts, 65-70 parts, 70-75 parts or 75-80 parts by weight, preferably 30-70 parts by weight of butadiene monomer, and the weight ratio of the butadiene monomer to the modified styrene monomer can be (1.11-1.5): 1.
in some embodiments, the nanosilicon compound is nanosilicon dioxide or nanosilicon dioxide, preferably the nanosilicon compound is nanosilicon dioxide; the carboxylic acid monomer is at least one of acrylic acid, maleic acid, fumaric acid and itaconic acid; the molecular weight regulator is n-dodecyl mercaptan and/or tertiary dodecyl mercaptan; the emulsifier is at least one of sodium dodecyl benzene sulfonate and sodium alkyl diphenyl ether disulfonate; the initiator is at least one of potassium sulfate, sodium sulfate, potassium persulfate and ammonium persulfate.
In some embodiments, the styrene-butadiene emulsion obtained has a solid content of 35-55%, an average particle size of 50-200 nm, and a glass transition temperature (Tg) of-15-10 ℃. The butylbenzene emulsion is a milky colloidal solution, the solid content of 35-55% ensures that the butylbenzene emulsion is used as a binder to be uniformly mixed with a negative electrode active substance, a conductive agent and the like, and the binding effect of the butylbenzene emulsion cannot be influenced due to the fact that the solid content is too high. The glass transition temperature of-15-10 ℃ can ensure that the molecular chain of the butylbenzene emulsion is in a relaxed state at normal temperature, the whole molecular chain moves to show viscous flow property, and the butylbenzene emulsion is more convenient to coat.
The second aspect of the present invention is directed to providing the styrene-butadiene emulsion for negative electrode slurry prepared by the above preparation method. The butylbenzene emulsion is used as a binder in the negative electrode slurry, can effectively improve the activity of the surface of the negative electrode slurry, and can effectively inhibit the thick edge phenomenon caused by the flowing of the slurry to the edge in the coating and baking processes.
2. Negative electrode slurry
The third aspect of the invention aims to provide a negative electrode slurry, which comprises a negative electrode active material, a conductive agent, a binder and a solvent, wherein the binder is the styrene-butadiene emulsion for the negative electrode slurry.
Specifically, the negative active material may be one or more of graphite, soft carbon, hard carbon, carbon fiber, mesocarbon microbeads, silicon-based materials, tin-based materials, lithium titanate, or other metals capable of forming an alloy with lithium. Wherein, the graphite can be selected from one or more of artificial graphite, natural graphite and modified graphite; the silicon-based material can be one or more selected from simple substance silicon, silicon-oxygen compound, silicon-carbon compound and silicon alloy; the tin-based material can be one or more selected from simple substance tin, tin oxide compound and tin alloy. And the conductive agent includes, but is not limited to, carbon-based materials (e.g., carbon black, acetylene black, ketjen black, carbon fibers, carbon nanotubes, graphene, etc.), metal-based materials (e.g., copper, nickel, aluminum, silver, etc.), conductive polymers (e.g., polyphenylene derivatives), and mixtures thereof. The solvent may be water. The negative electrode slurry also includes a dispersant, sodium carboxymethyl cellulose (CMC).
3. Negative plate
The invention aims at providing a negative plate, which comprises a negative current collector and a negative active material layer coated on at least one surface of the negative current collector, wherein the negative active material layer is formed by coating the negative slurry.
The negative electrode current collector is generally a structure or a part for collecting current, and the negative electrode current collector may be any material suitable for use as a negative electrode current collector of a lithium ion battery in the art, for example, the negative electrode current collector may include, but is not limited to, a metal foil, and the like, and more specifically, may include, but is not limited to, a copper foil, and the like.
4. Secondary battery
A fifth aspect of the present invention is directed to a secondary battery, including a positive electrode sheet, a negative electrode sheet, and a separator interposed between the positive electrode sheet and the negative electrode sheet, wherein the negative electrode sheet is the negative electrode sheet described above.
Wherein, the active material layer coated on the positive plate can be an active material including but not limited to a chemical formula such as LiaNixCoyMzO2-bNb(wherein a is more than or equal to 0.95 and less than or equal to 1.2, x>0, y is more than or equal to 0, z is more than or equal to 0, and x + y + z is 1,0 is more than or equal to b and less than or equal to 1, M is selected from one or more of Mn and Al, N is selected from one or more of F, P and S), and the positive electrode active material can also be selected from one or more of LiCoO (lithium LiCoO), but not limited to2、LiNiO2、LiVO2、LiCrO2、LiMn2O4、LiCoMnO4、Li2NiMn3O8、LiNi0.5Mn1.5O4、LiCoPO4、LiMnPO4、LiFePO4、LiNiPO4、LiCoFSO4、CuS2、FeS2、MoS2、NiS、TiS2And the like. The positive electrode active material may be further modified, and the method of modifying the positive electrode active material is known to those skilled in the art, for example, the positive electrode active material may be modified by coating, doping, and the like, and the material used in the modification may be one or a combination of more of Al, B, P, Zr, Si, Ti, Ge, Sn, Mg, Ce, W, and the like. And the positive plate adoptsThe positive electrode current collector used is generally a structure or a part for collecting current, and may be any material suitable for use as a positive electrode current collector of a lithium ion battery in the art, for example, the positive electrode current collector may include, but is not limited to, a metal foil, and the like, and more specifically, may include, but is not limited to, an aluminum foil, and the like.
And the separator may be any material suitable for lithium ion battery separators in the art, for example, may be a combination including, but not limited to, one or more of polyethylene, polypropylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester, natural fiber, and the like.
In order to make the technical solutions and advantages of the present invention clearer, the present invention and its advantageous effects will be described in further detail with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.
Example 1
A preparation method of styrene-butadiene emulsion for negative electrode slurry comprises the following steps:
s1, reacting 5 parts of n-octanol and 35 parts of styrene monomer under the catalysis of 1 part of dilute sulfuric acid to obtain a modified styrene monomer;
s2, mixing 40 parts of modified styrene monomer and 2 parts of nano TiO according to parts by weight2Mixing 2 parts of maleic acid (carboxylic acid monomer), 50 parts of butadiene monomer, 2 parts of n-dodecyl mercaptan (molecular weight regulator), 2 parts of sodium dodecyl benzene sulfonate (emulsifier) and 0.5 part of potassium sulfate (initiator) in a pressure kettle, and carrying out emulsion polymerization reaction for 4 hours at 55 ℃ to obtain a pre-product; and mixing the pre-product with a sodium hydroxide solution to adjust the pH value of the mixture to 7.0 to obtain the butylbenzene emulsion.
Example 2
Different from the example 1, the modified styrene monomer is prepared by reacting 5 parts by weight of n-octanol with 40 parts by weight of styrene monomer under the catalysis of 1 part by weight of dilute sulfuric acid.
The rest is the same as embodiment 1, and the description is omitted here.
Example 3
Different from example 1, modified styrene monomer is prepared by reacting 5 parts by weight of n-octanol with 45 parts by weight of styrene monomer under the catalysis of 1 part by weight of dilute sulfuric acid.
The rest is the same as embodiment 1, and the description is omitted here.
Example 4
Different from example 1, the modified styrene monomer is prepared by reacting 5 parts by weight of n-octanol with 60 parts by weight of styrene monomer under the catalysis of 1 part by weight of dilute sulfuric acid.
The rest is the same as embodiment 1, and the description is omitted here.
Example 5
Different from example 1, modified styrene monomer is prepared by reacting 1 part by weight of n-octanol with 35 parts by weight of styrene monomer under the catalysis of 1 part by weight of dilute sulfuric acid.
The rest is the same as embodiment 1, and the description is omitted here.
Example 6
Different from the example 1, the modified styrene monomer is prepared by reacting 1 part by weight of n-octanol with 45 parts by weight of styrene monomer under the catalysis of 1 part by weight of dilute sulfuric acid.
The rest is the same as embodiment 1, and the description is omitted here.
Example 7
Different from the embodiment 1, the modified styrene monomer is prepared by reacting 5 parts by weight of n-nonanol with 40 parts by weight of styrene monomer under the catalysis of 1 part by weight of dilute sulfuric acid.
The rest is the same as embodiment 1, and the description is omitted here.
Example 8
The difference from example 1 is the parts by weight of the modified styrene monomer and the butadiene monomer, the part by weight of the modified styrene monomer being 45 parts, and the part by weight of the butadiene monomer being 50 parts.
The rest is the same as embodiment 1, and the description is omitted here.
Example 9
The difference from example 1 is the weight parts of the modified styrene monomer and the butadiene monomer, the weight part of the modified styrene monomer is 45 parts, and the weight part of the butadiene monomer is 60 parts.
The rest is the same as embodiment 1, and the description is omitted here.
Example 10
The difference from example 1 is the weight parts of the modified styrene monomer and the butadiene monomer, the weight part of the modified styrene monomer is 50 parts, and the weight part of the butadiene monomer is 40 parts.
The rest is the same as embodiment 1, and the description is omitted here.
Example 11
The difference from example 1 is that the reaction temperature of the butylbenzene emulsion polymerization is 25 ℃, and the reaction time is 4 h.
The rest is the same as embodiment 1, and the description is omitted here.
Example 12
The difference from example 1 is that the reaction temperature of the butylbenzene emulsion polymerization is 75 ℃, and the reaction time is 4 h.
The rest is the same as embodiment 1, and the description is omitted here.
Example 13
A preparation method of styrene-butadiene emulsion for negative electrode slurry comprises the following steps:
s1, reacting 5 parts of n-nonanol and 40 parts of styrene monomer under the catalysis of 1 part of dilute sulfuric acid to obtain modified styrene monomer;
s2, mixing 45 parts of modified styrene monomer and 2 parts of nano TiO according to parts by weight2Mixing 2 parts of maleic acid (carboxylic acid monomer), 50 parts of butadiene monomer, 2 parts of n-dodecyl mercaptan (molecular weight regulator), 2 parts of sodium dodecyl benzene sulfonate (emulsifier) and 0.5 part of potassium sulfate (initiator) in a pressure kettle, and carrying out emulsion polymerization reaction for 4 hours at 55 ℃ to obtain a pre-product; and mixing the pre-product with a sodium hydroxide solution to adjust the pH value of the mixture to 7.0 to obtain the butylbenzene emulsion.
Example 14
A preparation method of styrene-butadiene emulsion for negative electrode slurry comprises the following steps:
s1, reacting 5 parts of n-nonanol and 45 parts of styrene monomer under the catalysis of 1 part of dilute sulfuric acid to obtain a modified styrene monomer;
s2, mixing 45 parts of modified styrene monomer and 2 parts of nano TiO according to parts by weight2Mixing 2 parts of maleic acid (carboxylic acid monomer), 60 parts of butadiene monomer, 2 parts of n-dodecyl mercaptan (molecular weight regulator), 2 parts of sodium dodecyl benzene sulfonate (emulsifier) and 0.5 part of potassium sulfate (initiator) in a pressure kettle, and carrying out emulsion polymerization reaction for 4 hours at 55 ℃ to obtain a pre-product; and mixing the pre-product with a sodium hydroxide solution to adjust the pH value of the mixture to 7.5 to obtain the butylbenzene emulsion.
Comparative example 1
A butylbenzene emulsion for negative electrode slurry is a butylbenzene emulsion which can be purchased on the market conventionally, and styrene is conventional styrene which is not subjected to substitution reaction.
The above examples 1 to 14 and comparative example 1 were applied to a negative electrode slurry, and a negative electrode sheet was prepared.
Preparing a negative plate: mixing the styrene-butadiene emulsion, graphite, conductive carbon black and CMC in a mass ratio of 1.3: 97.7: and (3) mixing the components at a ratio of 0.8:1.2 to prepare negative electrode slurry, coating the negative electrode slurry on the surface of the copper foil, and drying to obtain the negative electrode sheet.
And testing the single-side adhesive force and the thick edge condition of the pole piece. Wherein, the adhesive force is a land adhesive force testing method commonly used in the industry at present. The thick edge is formed by recording the height H of the highest point of the edge of the pole piece1And an intermediate height H2And calculating the difference between the two to obtain the "thick edge" height H ═ H1-H2。
The test results are shown in table 1 below.
TABLE 1
Styrene-butadiene emulsion solid content% Average particle size/nm Pole piece adhesive force (single side)/N/m H/μm
Example 1 40％ 98 14 2
Example 2 40％ 100 13 2
Example 3 40％ 102 12 2
Example 4 41％ 100 11 3
Example 5 40％ 115 9 4
Example 6 40％ 116 8 4
Example 7 40％ 100 13 2
Example 8 42％ 120 15 2
Example 9 42％ 150 12 3
Example 10 43％ 110 16 2
Example 11 40％ 120 10 3
Example 12 40％ 130 11 3
Example 13 43％ 150 10 3
Example 14 44％ 200 8 2
Comparative example 1 40％ 120 8 5
The test results show that compared with the conventionally used butylbenzene emulsion, the butylbenzene emulsion used as the binder for the negative electrode slurry can effectively improve the phenomenon of thick edge formed at the edge of the negative electrode plate, and has better bonding performance as the binder.
Specifically, it can be seen from the comparison of examples 1 to 6 that the modified styrene monomers obtained with different contents of fatty alcohol have different performances finally appearing on the negative electrode sheet, and the more the proportion of the fatty alcohol "thick edge" phenomenon is, the more the improvement is, the better the adhesion of the electrode sheet is. The reason why the proportion of the fatty alcohol is more is probably that the fatty alcohol and the styrene monomer are subjected to full substitution reaction, so that the surface activity of the negative electrode slurry is more favorably improved, and the nano silicon dioxide is promoted to be dispersed to form silica sol and form a core-shell structure with the styrene-butadiene copolymer, so that the adhesive property of the pole piece is better improved.
In conclusion, the styrene-butadiene emulsion provided by the invention adopts the styrene monomer modified by the fatty alcohol as one of the raw materials, the obtained styrene-butadiene emulsion has low surface tension and high interfacial activity, and the slurry can be effectively inhibited from flowing to the edge in the coating and baking processes, so that the phenomenon of thick edge is effectively avoided.
Variations and modifications to the above-described embodiments may become apparent to those skilled in the art to which the invention pertains based upon the disclosure and teachings of the above specification. Therefore, the present invention is not limited to the above-mentioned embodiments, and any obvious modifications, substitutions or alterations based on the present invention will fall within the protection scope of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims (10)

1. The preparation method of the butylbenzene emulsion for the negative electrode slurry is characterized by comprising the following steps of:
s1, reacting fatty alcohol with a styrene monomer under the action of a catalyst to obtain a modified styrene monomer;
s2, mixing the modified styrene monomer obtained in the step S1 with a nano silica compound, a carboxylic acid monomer, a butadiene monomer, a molecular weight regulator, an emulsifier and an initiator, and carrying out emulsion polymerization reaction for 2-15 hours at 40-100 ℃ to obtain a pre-product; and adjusting the pH value of the pre-product to 6-10 to obtain the butylbenzene emulsion.
2. The preparation method of the styrene-butadiene emulsion for the negative electrode slurry according to claim 1, wherein the weight parts of the fatty alcohol are 0.5 to 10 parts, the weight parts of the styrene monomer are 20 to 60 parts, and the weight parts of the catalyst are 0.1 to 3 parts.
3. The method for preparing a styrene-butadiene emulsion for negative electrode slurry according to claim 1 or 2, characterized in that the fatty alcohol is at least one of n-heptanol, n-octanol, n-nonanol and n-decanol; the catalyst is at least one of dilute sulfuric acid, dilute hydrochloric acid, acetic acid and nitric acid.
4. The preparation method of the styrene-butadiene emulsion for the negative electrode slurry according to claim 1, wherein the modified styrene monomer is 10 to 80 parts by weight, the nano silica compound is 5 to 10 parts by weight, the carboxylic acid monomer is 2 to 5 parts by weight, the butadiene monomer is 10 to 80 parts by weight, the molecular weight regulator is 1 to 5 parts by weight, the emulsifier is 0.5 to 5 parts by weight, and the initiator is 0.2 to 5 parts by weight.
5. The method for preparing styrene-butadiene emulsion for negative electrode slurry according to claim 1 or 4, wherein the nanosilicon compound is nanosilicon dioxide or nanosilicon oxide; the carboxylic acid monomer is at least one of acrylic acid, maleic acid, fumaric acid and itaconic acid; the molecular weight regulator is n-dodecyl mercaptan and/or tertiary dodecyl mercaptan; the emulsifier is at least one of sodium dodecyl benzene sulfonate and sodium alkyl diphenyl ether disulfonate; the initiator is at least one of potassium sulfate, sodium sulfate, potassium persulfate and ammonium persulfate.
6. The preparation method of the styrene-butadiene emulsion for the negative electrode slurry according to any one of claims 1 to 2 and 4, wherein the obtained styrene-butadiene emulsion has a solid content of 35 to 55 percent, an average particle size of 50 to 200nm and a glass transition temperature of-15 to 10 ℃.
7. A styrene-butadiene emulsion for negative electrode slurry, which is characterized by being prepared by the preparation method of the styrene-butadiene emulsion for negative electrode slurry according to any one of claims 1 to 6.
8. A negative electrode slurry comprising a negative electrode active material, a conductive agent, a binder and a solvent, wherein the binder is the styrene-butadiene emulsion for the negative electrode slurry according to claim 7.
9. A negative electrode sheet comprising a negative electrode current collector and a negative electrode active material layer coated on at least one surface of the negative electrode current collector, wherein the negative electrode active material layer is formed by coating the negative electrode slurry according to claim 8.
10. A secondary battery comprising a positive electrode sheet, a negative electrode sheet, and a separator interposed between the positive electrode sheet and the negative electrode sheet, wherein the negative electrode sheet is the negative electrode sheet according to claim 9.
CN202210393000.7A 2022-04-15 2022-04-15 Preparation method of butylbenzene emulsion for negative electrode slurry, product, negative electrode slurry, negative electrode sheet and secondary battery Pending CN114671980A (en)

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Citations (2)

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Publication number Priority date Publication date Assignee Title
CN101376682A (en) * 2008-09-27 2009-03-04 上海东升新材料有限公司 Modified butyl benzene emulsion and preparation thereof
CN113736002A (en) * 2021-09-13 2021-12-03 江西迪比科股份有限公司 Modified polyhalogenated styrene-1, 3-butadiene emulsion binder, preparation and application thereof

Patent Citations (2)

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Publication number Priority date Publication date Assignee Title
CN101376682A (en) * 2008-09-27 2009-03-04 上海东升新材料有限公司 Modified butyl benzene emulsion and preparation thereof
CN113736002A (en) * 2021-09-13 2021-12-03 江西迪比科股份有限公司 Modified polyhalogenated styrene-1, 3-butadiene emulsion binder, preparation and application thereof

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