CN118165678A - Solution type binder and preparation method and application thereof - Google Patents

Solution type binder and preparation method and application thereof Download PDF

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Publication number
CN118165678A
CN118165678A CN202311767359.7A CN202311767359A CN118165678A CN 118165678 A CN118165678 A CN 118165678A CN 202311767359 A CN202311767359 A CN 202311767359A CN 118165678 A CN118165678 A CN 118165678A
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China
Prior art keywords
solution
ethoxy
ethylenically unsaturated
binder
acrylate
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Inventor
贾贵玉
王晓
岳弈君
袁满
贾元峰
孙永建
纪学顺
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Wanhua Chemical Group Battery Technology Co ltd
Wanhua Chemical Yantai Battery Material Technology Co ltd
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Wanhua Chemical Group Battery Technology Co ltd
Wanhua Chemical Yantai Battery Material Technology Co ltd
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Priority to CN202311767359.7A priority Critical patent/CN118165678A/en
Publication of CN118165678A publication Critical patent/CN118165678A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • 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
    • 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
    • C08F220/10—Esters
    • C08F220/26—Esters containing oxygen in addition to the carboxy oxygen
    • C08F220/28—Esters containing oxygen in addition to the carboxy oxygen containing no aromatic rings in the alcohol moiety
    • C08F220/281—Esters containing oxygen in addition to the carboxy oxygen containing no aromatic rings in the alcohol moiety and containing only one oxygen, e.g. furfuryl (meth)acrylate or 2-methoxyethyl (meth)acrylate
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
    • C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
    • C08F220/42—Nitriles
    • C08F220/44—Acrylonitrile
    • C08F220/46—Acrylonitrile with carboxylic acids, sulfonic acids or 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
    • C09J133/04—Homopolymers or copolymers of esters
    • C09J133/14—Homopolymers or copolymers of esters of esters containing halogen, nitrogen, sulfur or oxygen atoms in addition to the carboxy oxygen
    • 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
    • C09J133/18—Homopolymers or copolymers of nitriles
    • C09J133/20—Homopolymers or copolymers of acrylonitrile
    • 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
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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

Abstract

The invention discloses a solution type binder, a preparation method and application thereof. The binder comprises a vinyl polymer, wherein the polymer comprises, based on the total amount of vinyl polymer, as polymerized monomer: a) 2 to 10wt% of ethyleneurea ethoxy (meth) acrylate; (b) 10 to 70wt% of methoxy polyethoxy (meth) acrylate; (c) 20 to 50wt% of at least one of an ethylenically unsaturated carboxylic acid, an ethylenically unsaturated carboxylic anhydride; (d) 0% to 68% by weight of ethylenically unsaturated nitrile monomer. The binder provided by the invention is applied to the field of lithium ion batteries, and can improve the dispersibility of the negative electrode slurry and the processability of the pole piece.

Description

Solution type binder and preparation method and application thereof
Technical Field
The invention relates to a lithium ion battery material and a preparation method thereof, in particular to a lithium ion secondary battery negative electrode binder and a preparation method thereof.
Background
The lithium ion battery is considered as the most promising mobile energy storage technology due to the advantages of high energy density, long cycle life, environmental protection and the like, and is widely applied to the fields of electronic products, electric automobiles, energy storage equipment and the like.
The lithium ion battery mainly comprises a pole piece (comprising a positive pole and a negative pole), electrolyte, a diaphragm and the like; the pole piece is generally composed of an active material, a conductive agent, a dispersing agent, a binder and a current collector; in the pole piece preparation process, electrode active materials, conductive agents, dispersing agents and binder solutions are mixed and homogenized, then coated on a current collector, and then the complete pole piece is formed through processes of drying, calendaring and the like, wherein the binder mainly plays a role in binding, and the integrity of the pole piece is maintained.
At present, the most widely used negative electrode binder is Styrene Butadiene Rubber (SBR), and carboxymethyl cellulose (CMC) is needed to be added as a thickening agent and a dispersing agent in the use process, but CMC has general viscosity, large brittleness and poor flexibility, and a pole piece is easy to crack during charge and discharge; meanwhile, when SBR is applied to a graphite negative electrode and a silicon-based novel negative electrode based on a point-point bonding mechanism as a binder, the volume of the graphite negative electrode and the silicon-based negative electrode is repeatedly expanded and contracted during charge and discharge cycles, the point bonding is extremely easy to lose the cohesiveness, so that the capacity loss is caused, and particularly the high-temperature storage and the high-temperature cycle performance are deteriorated; in addition, SBR has a large swelling degree (50% to 200%) in an electrolyte, resulting in an increase in the interval between anode active materials, and at the same time, the large swelling of the electrolyte causes a decrease in the adhesion of a binder to a copper foil or an active material, resulting in deterioration of battery performance.
PAA is adopted as a binder in the prior art, so that the bonding strength is high, the swelling of electrolyte is low, and the high-temperature cycle performance is excellent. However, the polymer has high glass transition temperature, which is easy to cause hard and brittle problems of the pole piece after coating. Therefore, the adhesive is easy to crack in the coating process, has a plurality of stripes after cold pressing, has the edge decarburization during cutting and has the phenomenon of powder falling at the bending part of the pole piece in the winding process, and the processing performance is poor, so that the application of the adhesive in batteries is severely restricted.
CN111139002B discloses a water-soluble adhesive for lithium ion battery, which adopts ternary polymerization of acrylonitrile, 2-acrylamide-2-phenyl ethane sulfonic acid and methacrylic acid, the molecular chain characteristic of the water-soluble polymer endows the surface-surface bonding mechanism, and net bonding is formed inside the pole piece, so that bonding force between active materials and between the active materials and a base material is enhanced, meanwhile, the adhesive has better dispersion property and slurry stability, and lower swelling characteristic of electrolyte, and compared with SBR latex, the high-temperature storage and high-temperature cycle performance of lithium ion battery can be obviously improved, but the processing performance of the pole piece needs to be further improved.
CN115312779A is prepared by designing the raw materials and the content of the polymer solution A and the polymer solution B to obtain the waterborne polymer binder with a three-dimensional cross-linked structure, and the waterborne polymer binder has better flexibility and higher binding power, can be applied to preparing the lithium ion battery negative electrode pole piece, but the preparation efficiency of the binder needs to be further improved.
Therefore, aiming at the problems of current SBR dispersion performance, high-temperature cycle performance and PAA pole piece processing, the adhesive product with better dispersion, higher adhesive force and better flexibility is provided, and the technical problem to be solved is urgent.
Disclosure of Invention
The invention aims to provide a solution type binder, and a preparation method and application thereof. Compared with SBR, the binder has good mechanical property and dispersion property, and can ensure that the lithium ion battery has excellent cycle life. Meanwhile, compared with the existing PAA product, the PAA product has better flexibility, and can ensure that the lithium ion battery pole piece has excellent processing performance.
In order to achieve the above purpose, the present invention provides the following technical solutions:
In one aspect, the present invention provides a solution-type binder obtained by polymerizing raw materials comprising:
(a) 2 to 10wt% of ethyleneurea ethoxy (meth) acrylate; preferably 3wt% to 8wt%;
(b) 10 to 70wt% of methoxy polyethoxy (meth) acrylate; preferably 20wt% to 60wt%;
(c) 20 to 50wt% of at least one of an ethylenically unsaturated carboxylic acid, an ethylenically unsaturated carboxylic anhydride; preferably 25wt% to 45wt%;
(d) From 0% to 68% by weight of ethylenically unsaturated nitrile monomer, preferably from 0 to 50% by weight.
In the present invention, the ethylene urea ethoxy (meth) acrylate is at least one of ethylene urea ethoxy acrylate and ethylene urea ethoxy methacrylate, and preferably ethylene urea ethoxy methacrylate.
In the present invention, the ethoxy repeating unit in the methoxy polyethoxy (meth) acrylate is 1 to 50, preferably the ethoxy repeating unit is 1 to 10, and specifically can be selected from the group consisting of winning chemical MPEG series products, such as winning MPEG750, MPEG2005, MPEG5005.
In the present invention, among the ethylenically unsaturated carboxylic acid and the ethylenically unsaturated carboxylic acid anhydride, the ethylenically unsaturated carboxylic acid is preferable, and at least one of acrylic acid and methacrylic acid is more preferable.
In the present invention, the ethylenically unsaturated nitrile monomer is at least one selected from the group consisting of acrylonitrile, α -haloacrylonitrile, and α -alkylacrylonitrile, preferably at least one selected from the group consisting of acrylonitrile, α -chloroacrylonitrile, α -bromoacrylonitrile, methacrylonitrile, and ethylacrylonitrile.
On the other hand, the invention also provides a preparation method of the solution type adhesive, which comprises the following steps:
Step one, placing an aqueous solution of protective glue in a reaction kettle, introducing inert gas into the reaction kettle, and heating;
Step two, adding the four monomers and the initiator in the monomer tank and the initiator tank respectively, and simultaneously adding the mixed monomers and the initiator in the reaction kettle to initiate polymerization reaction;
Step three, carrying out reduced pressure distillation to remove residual monomers after polymerization is finished and heat preservation is carried out;
and step four, adding a neutralizer to regulate the pH value to obtain the viscous water-soluble binder.
In the invention, the protective glue in the first step is selected from polyvinyl alcohol and/or carboxymethyl cellulose; the usage amount of the protective adhesive is 0.1-2wt% of the total amount of the four monomers (a), (b), (c) and (d), and preferably 0.2-1.5wt%; the concentration of the aqueous solution of the protective paste is 0.1-0.5%, preferably 0.2-0.4%.
In the first step, the inert gas is selected from nitrogen or argon, and the temperature of the heating is 30-85 ℃.
In the invention, the initiator in the second step comprises an oxidant and a reducing agent, and the mass ratio of the oxidant to the reducing agent is 1:2-2:1, preferably 1:1-2:1. The oxidant is at least one selected from ammonium persulfate, sodium persulfate, potassium persulfate, tert-butyl hydroperoxide and hydrogen peroxide, preferably sodium persulfate; the reducing agent is at least one selected from sodium hydrosulfite, isoascorbic acid, sodium metabisulfite and sodium bisulphite, preferably sodium bisulphite. The oxidant is used in an amount of 0.1 to 1wt%, preferably 0.2 to 0.8wt%, based on the total amount of the four monomers (a), (b), (c) and (d); the reducing agent is used in an amount of 0.1 to 1wt%, preferably 0.2 to 0.8wt%, based on the total amount of the four monomers (a), (b), (c) and (d).
In the invention, the temperature of the reaction in the second step is 30-85 ℃, preferably 35-80 ℃; the reaction time is 3 to 6 hours, preferably 4 to 5 hours.
In the invention, the time of heat preservation in the step three is 1 to 3 hours, preferably 1.5 to 2 hours.
In the invention, the neutralizing agent in the fourth step is one or more selected from NaOH, na 2CO3 and LiOH aqueous solution, and the concentration is 5-15%; the pH value after the adjustment is 5-9.
In the present invention, the solid content of the solution-type binder is 4 to 10wt%, preferably 5 to 8wt%.
Finally, the invention provides the application of the solution type binder in the aspect of a negative electrode active material binder, wherein the negative electrode material is selected from artificial graphite, natural graphite, hard carbon and silicon carbon.
The invention has the following beneficial effects:
(1) The solution type binder contains ethylene urea groups, so that the mechanical property, electrolyte swelling resistance and lithium ion transmission performance of the binder can be improved, and excellent cycle performance and dynamic performance of the battery are provided.
(2) The solution type adhesive uses methoxy polyethoxy acrylate monomer, can improve the flexibility of the adhesive and endow the battery with excellent pole piece processing performance.
(3) The solution type binder is rich in carboxyl groups, improves the interaction of polymer molecular chains with the anode active material and the conductive agent, and endows the slurry with excellent dispersing effect.
(4) The solution type binder is added with the functional monomer containing cyano functional groups in the polymerization process, and the existence of the polar functional groups is beneficial to promoting the conduction of lithium ions, reducing the internal resistance of the lithium battery and improving the low-temperature performance of the lithium battery. In addition, the cyano monomer can also enhance the acting force between the binder and the negative electrode active material and the current collector.
(5) The solution type binder polymer molecular chain contains an ethylene urea group, a methoxy polyethoxy group and a cyano functional group, and the three groups are synergistic to generate certain hydrogen bond crosslinking between the polymer molecular chains, so that the polymer has certain strength while the flexibility is improved, and the pole piece is endowed with excellent processing performance and cycle performance.
Detailed Description
The present invention will be further illustrated by the following specific examples, which are merely detailed illustrations of the present invention and are not intended to limit the scope of the invention.
Raw materials and sources:
raw material name Abbreviations (abbreviations) Manufacturing factories
Ethylene urea ethoxy methacrylate MEEU50W Win-win chemistry
Methoxy acrylic acid ethyl ester MEA Hubei zhen Bo chemical industry
Acrylic acid AA Wanhua chemistry
Methacrylic acid MAA Wanhua chemistry
Ethylene urea ethoxy acrylate V50M Shanghai loyalty chemical industry
Acrylonitrile (Acrylonitrile) AN Wanhua chemistry
Methoxy polyethoxy methacrylate (ethoxy repeating unit 17) MPEG750 Win-win chemistry
Methoxy polyethoxy methacrylate (ethoxy repeat unit 45) MPEG2005 Win-win chemistry
Methoxy polyethoxy methacrylate (ethoxy repeating unit 113) MPEG5005 Win-win chemistry
Ammonium persulfate APS Jinan Jin chemical Co., ltd
Sodium bisulfite NaHSO3 Wanhua chemistry
Polyvinyl alcohol 2488 PVA2488 Sichuan Utility Co Ltd
Sodium carboxymethyl cellulose CMC Chinese medicinal chemistry
Conductive carbon black Super-P Yiruishi group
The main raw materials and proportions used in the examples and comparative examples are shown in Table 1:
Table 1 main raw materials and formulation for preparing solution type adhesive
The invention also provides a preparation method of the solution-type binder.
Example 1
(1) Adding 0.5g PVA2488 and 500g deionized water into a reaction kettle, stirring and heating to 50 ℃;
(2) 2g of ethyleneurea ethoxy methacrylate, 70g of ethyl methoxyacrylate, 28g of acrylic acid were mixed;
(3) 0.5gAPS was dissolved in 50g of water and 0.3. 0.3gNaHSO 3 was dissolved in 50g of water to prepare an oxy-still initiator solution;
(4) Simultaneously dropwise adding the mixed monomer in the step (2) and the initiator aqueous solution in the step (3) into the reaction kettle in the step (1) for 3 hours, and preserving heat for 2 hours after the dropwise adding is finished for reduced pressure distillation;
(5) Heating to 80 ℃, adding 10% sodium hydroxide aqueous solution to adjust the pH value of the solution to 8.0, and adjusting the solid content to 6wt% to obtain the solution type negative electrode binder.
Example 2
(1) Adding 0.5g PVA2488 and 500g deionized water into a reaction kettle, stirring and heating to 50 ℃;
(2) 10g of ethyleneurea ethoxy methacrylate, 40g of ethyl methoxyacrylate, 50g of acrylic acid were mixed;
(3) 0.1gAPS was dissolved in 50g of water and 0.1gNaHSO 3 was dissolved in 50g of water to prepare an oxy-still initiator solution;
(4) Simultaneously dropwise adding the mixed monomer in the step (2) and the initiator aqueous solution in the step (3) into the reaction kettle in the step (1) for 3 hours, and preserving heat for 2 hours after the dropwise adding is finished for reduced pressure distillation;
(5) Heating to 80 ℃, adding 10% sodium hydroxide aqueous solution to adjust the pH value of the solution to 8.0, and adjusting the solid content to 6wt% to obtain the solution type negative electrode binder.
Example 3
(1) Adding 0.5g PVA2488 and 500g deionized water into a reaction kettle, stirring and heating to 50 ℃;
(2) 5g of ethyleneurea ethoxy acrylate, 45g of methoxypolyethoxy methacrylate (repeat unit 17), 50g of methacrylic acid were mixed;
(3) 0.5gAPS was dissolved in 50g of water and 0.3. 0.3gNaHSO 3 was dissolved in 50g of water to prepare an oxy-still initiator solution;
(4) Simultaneously dropwise adding the mixed monomer in the step (2) and the initiator aqueous solution in the step (3) into the reaction kettle in the step (1) for 3 hours, and preserving heat for 2 hours after the dropwise adding is finished for reduced pressure distillation;
(5) Heating to 80 ℃, adding 10% sodium hydroxide aqueous solution to adjust the pH value of the solution to 8.0, and adjusting the solid content to 6wt% to obtain the solution type negative electrode binder.
Example 4
(1) Adding 0.5g PVA2488 and 500g deionized water into a reaction kettle, stirring and heating to 35 ℃;
(2) 5g of ethyleneurea ethoxy acrylate, 45g of methoxypolyethoxy methacrylate (repeat unit 45), 50g of methacrylic acid were mixed;
(3) 0.5gAPS was dissolved in 50g of water and 0.3. 0.3gNaHSO 3 was dissolved in 50g of water to prepare an oxy-still initiator solution;
(4) Simultaneously dropwise adding the mixed monomer in the step (2) and the initiator aqueous solution in the step (3) into the reaction kettle in the step (1) for 3 hours, and preserving heat for 2 hours after the dropwise adding is finished for reduced pressure distillation;
(5) Heating to 80 ℃, adding 10% sodium hydroxide aqueous solution to adjust the pH value of the solution to 8.0, and adjusting the solid content to 6wt% to obtain the solution type negative electrode binder.
Example 5
(1) Adding 0.5g PVA2488 and 500g deionized water into a reaction kettle, stirring and heating to 50 ℃;
(2) 2g of ethyleneurea ethoxy methacrylate, 45g of methoxyethyl methacrylate, 20g of acrylic acid, 33g of acrylonitrile are mixed;
(3) 0.5gAPS was dissolved in 50g of water and 1gNaHSO3 was dissolved in 50g of water to prepare an oxy-still initiator solution;
(4) Simultaneously dropwise adding the mixed monomer in the step (2) and the initiator aqueous solution in the step (3) into the reaction kettle in the step (1) for 3 hours, and preserving heat for 2 hours after the dropwise adding is finished for reduced pressure distillation;
(5) Heating to 80 ℃, adding 10% sodium hydroxide aqueous solution to adjust the pH value of the solution to 8.0, and adjusting the solid content to 6wt% to obtain the solution type negative electrode binder.
Example 6
(1) Adding 0.5g PVA2488 and 500g deionized water into a reaction kettle, stirring and heating to 80 ℃;
(2) 2g of ethyleneurea ethoxy methacrylate, 10g of methoxyethyl methacrylate, 20g of acrylic acid, 68g of acrylonitrile are mixed;
(3) 1gAPS g of NaHSO3 was dissolved in 50g of water to prepare an oxygen-returning initiator solution;
(4) Simultaneously dropwise adding the mixed monomer in the step (2) and the initiator aqueous solution in the step (3) into the reaction kettle in the step (1) for 3 hours, and preserving heat for 2 hours after the dropwise adding is finished for reduced pressure distillation;
(5) Heating to 80 ℃, adding 10% sodium hydroxide aqueous solution to adjust the pH value of the solution to 8.0, and adjusting the solid content to 6wt% to obtain the solution type negative electrode binder.
Comparative example 1
Ethylene urea ethoxy methacrylate was not added and the acrylic acid was 30g, otherwise as in example 1.
Comparative example 2
Using 0.5g of ethyleneurea ethoxy methacrylate, 29.5g of acrylic acid, the same procedure as in example 1 was followed.
Comparative example 3
Methoxy-free ethyl methacrylate, acrylonitrile 40g, otherwise as in example 2.
Comparative example 4
Methoxy polyethoxy methacrylate (ethoxy repeat unit 113) otherwise as in example 3.
Comparative example 5
Example 1 was repeated except that 5g of ethyleneurea ethoxy methacrylate, 15g of ethyl methoxyacrylate, 15g of methacrylic acid and 65g of acrylonitrile were used.
Comparative example 6
Commercial SBR3001A/BCQ15-2CMC binder system.
Comparative example 7
Commercial Yindile LA136D PAA adhesive
Comparative example 8
Following the procedure of example 8 of patent CN112567549a, ethylene urea ethoxy methacrylate/butadiene/styrene=0.1/49.95/49.95.
Swelling degree test of electrolyte on water-soluble binder:
The water-soluble adhesive of the formed film and the adhesive of the comparative example are cut into square films with the side length of 1cm, the square films are dried in an oven at the temperature of 60 ℃ for 24 hours, the weight is marked as M1, the square films are placed in a glass sealing bottle with a cover and filled with electrolyte of ethylene carbonate EC, ethylmethyl carbonate EMC and diethyl carbonate DEC, the volume ratio of the EC to the DEC is 3:2:5, the square films are gently sucked away from the surface electrolyte of the films in a drying room after being kept at 60 ℃ for 48 hours, the weight is marked as M2, and the swelling degree of the electrolyte is Swelling:
swelling = (M2-M1)/m1×100%, test results are shown in table 3;
The water-soluble binders for lithium ion batteries prepared in examples 1 to 6 and the binders in comparative examples 1 to 8 of the present invention were mixed and dispersed with graphite, conductive carbon black and CMC dispersant, respectively, to prepare lithium ion negative electrode sheets.
The preparation method comprises the following steps:
Preparing a negative electrode plate slurry: the graphite cathode material, the conductive carbon black, the water-soluble binder (calculated by solid content) for the lithium ion battery of the embodiment and the comparative example are mixed according to the mass fraction of 96.5wt%, 1.0wt% and 2.5 wt%, and deionized water is added according to the mass fraction of 45wt% of the total solid component, so as to prepare the cathode electrode plate slurry. And (3) after passing through a 100-mesh screen, coating the uniformly dispersed slurry on a copper foil with the thickness of 10 mu m serving as a current collector, directly putting the copper foil into a furnace for drying at 120 ℃ for 5 minutes, naturally cooling the copper foil to room temperature, and calendering the copper foil with the unit length load of 10 multiplied by 10 4 N/m to obtain an electrode plate serving as a negative electrode of the lithium ion battery.
The stability of the slurry of the negative electrode plate is measured by the following method:
The anode electrode plate slurries prepared by the examples and the comparative examples are kept stand for 48 hours, the upper layer slurry and the lower layer slurry are respectively weighed and then are placed in a baking oven at 150 ℃ for 30 minutes, the dry weight of the upper layer and the dry weight of the lower layer are weighed, and the stability of the slurries is measured by comparing the solid content difference of the upper layer and the lower layer.
The peel strength of the negative electrode plate is measured by the following method:
the electrode sheets of examples and comparative examples were cut into 20cm X2.5 cm strips, a steel plate 1mm thick was bonded with a double-sided tape on the current collector side, a transparent adhesive tape was bonded on the coating layer side, and the strips were peeled at a speed of 100mm/min in a direction of 180℃by a tensile tester, and the peel stress was measured, and the test results are shown in Table 3.
The flexibility evaluation of the negative pole piece adopts the following method:
A mandrel with a diameter Φ=1.0mm was placed on the current collector side of the rolled pole piece of the examples and comparative examples, and a bending experiment was performed, the state of the pole piece at this time was observed by an optical microscope, the pole piece was marked as good as o, the occurrence of falling or cracking was marked as x, and the test results are shown in table 3.
The graphite negative electrode material electrode plate manufactured by the water-soluble binder, the conventional positive electrode plate, electrolyte and the diaphragm are manufactured into the lithium ion battery. Wherein the positive electrode main material adopts LG chemical NCM811, the negative electrode main material adopts Bei Terui SFC-R, the diaphragm adopts lithium excellent new energy P25 diaphragm, and the electrolyte adopts Wanhua WT325.
Lithium ion battery performance evaluation:
The lithium ion battery is tested by adopting a constant current method to obtain the initial coulomb efficiency of charge and discharge cycle, the coulomb efficiency after 50 times of cycle and the capacity retention rate, and the ratio of the thickness increasing value of the electrode plate to the thickness of the electrode plate before charge and discharge is recorded as the expansion rate of the electrode plate in the state of embedding lithium into the electrode plate after 50 weeks of charge and discharge, and the obtained results are shown in Table 3.
TABLE 3 Table 3
As shown in Table 3, the binders prepared in examples 1 to 6 of the present invention have the characteristics of good slurry stability, high peel strength, good flexibility of the pole piece, excellent cycle performance, low expansion rate of the pole piece, and the like, as compared with the binders prepared in comparative examples 1 to 8.

Claims (10)

1. A solution-type adhesive, the adhesive being polymerized from a raw material comprising:
(a) 2 to 10wt% of ethyleneurea ethoxy (meth) acrylate; preferably 3wt% to 8wt%;
(b) 10 to 70wt% of methoxy polyethoxy (meth) acrylate; preferably 20wt% to 60wt%;
(c) 20 to 50wt% of at least one of an ethylenically unsaturated carboxylic acid, an ethylenically unsaturated carboxylic anhydride; preferably 25wt% to 45wt%;
(d) From 0% to 68% by weight of ethylenically unsaturated nitrile monomer, preferably from 0 to 50% by weight.
2. The solution adhesive according to claim 1, wherein the ethyleneurea ethoxy (meth) acrylate is at least one of ethyleneurea ethoxy acrylate, ethyleneurea ethoxy methacrylate, preferably ethyleneurea ethoxy methacrylate.
3. A solution adhesive according to claim 1 or 2, wherein the methoxy polyethoxy (meth) acrylate has an ethoxy repeat unit of 1 to 50, preferably an ethoxy repeat unit of 1 to 10.
4. A solution-type adhesive according to any one of claims 1 to 3, wherein the ethylenically unsaturated carboxylic acid or the ethylenically unsaturated carboxylic anhydride is preferably an ethylenically unsaturated carboxylic acid, more preferably at least one of acrylic acid and methacrylic acid.
5. The solution-type adhesive according to any one of claims 1 to 4, wherein the ethylenically unsaturated nitrile-based monomer is selected from at least one of acrylonitrile, α -halogenated acrylonitrile, α -alkylacrylonitrile, preferably at least one of acrylonitrile, α -chloroacrylonitrile, α -bromoacrylonitrile, methacrylonitrile, ethylacrylonitrile.
6. A method of preparing a solution adhesive according to any one of claims 1 to 4, comprising the steps of:
Step one, placing an aqueous solution of protective glue in a reaction kettle, introducing inert gas into the reaction kettle, and heating;
Step two, adding the four monomers and the initiator in the monomer tank and the initiator tank respectively, and simultaneously adding the mixed monomers and the initiator in the reaction kettle to initiate polymerization reaction;
Step three, carrying out reduced pressure distillation to remove residual monomers after polymerization is finished and heat preservation is carried out;
and step four, adding a neutralizer to regulate the pH value to obtain the viscous water-soluble binder.
7. The method according to claim 6, wherein the protective glue in the first step is selected from polyvinyl alcohol and/or carboxymethyl cellulose; the usage amount of the protective adhesive is 0.1-2wt% of the total amount of the four monomers (a), (b), (c) and (d), and preferably 0.2-1.5wt%; and/or the initiator in the second step comprises an oxidant and a reducing agent, wherein the mass ratio of the oxidant to the reducing agent is 1:2-2:1, and is preferably 1:1-2:1.
8. The method according to claim 6 or 7, wherein the oxidizing agent is at least one selected from ammonium persulfate, sodium persulfate, potassium persulfate, t-butyl hydroperoxide, hydrogen peroxide, preferably sodium persulfate; the reducing agent is at least one selected from sodium hydrosulfite, isoascorbic acid, sodium metabisulfite and sodium bisulphite, preferably sodium bisulphite; and/or the oxidant is used in an amount of 0.1 to 1wt%, preferably 0.2 to 0.8wt%, based on the total amount of the four monomers (a), (b), (c) and (d); the reducing agent is used in an amount of 0.1 to 1wt%, preferably 0.2 to 0.8wt%, based on the total amount of the four monomers (a), (b), (c) and (d).
9. The preparation method according to any one of claims 6 to 8, wherein the temperature of the reaction in step two is 30-85 ℃, preferably 35-80 ℃; the reaction time is 3-6h, preferably 4-5h; and/or, the heat preservation time in the step three is 1 to 3 hours, preferably 1.5 to 2 hours; and/or, the neutralizing agent in the fourth step is selected from one or more of NaOH, na 2CO3 and aqueous solution of LiOH.
10. Use of the solution-type binder according to any one of claims 1 to 5 or the solution-type binder prepared by the preparation method according to any one of claims 6 to 9 as a binder for negative electrode active materials selected from the group consisting of artificial graphite, natural graphite, hard carbon, and silicon carbon.
CN202311767359.7A 2023-12-21 2023-12-21 Solution type binder and preparation method and application thereof Pending CN118165678A (en)

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