CN110760279A - High-cohesiveness water-based slurry for diaphragm and lithium ion battery diaphragm manufactured by using same - Google Patents
High-cohesiveness water-based slurry for diaphragm and lithium ion battery diaphragm manufactured by using same Download PDFInfo
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- CN110760279A CN110760279A CN201911008401.0A CN201911008401A CN110760279A CN 110760279 A CN110760279 A CN 110760279A CN 201911008401 A CN201911008401 A CN 201911008401A CN 110760279 A CN110760279 A CN 110760279A
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 99
- 239000002002 slurry Substances 0.000 title claims abstract description 90
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 42
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 42
- 239000002033 PVDF binder Substances 0.000 claims abstract description 74
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims abstract description 74
- 229920003229 poly(methyl methacrylate) Polymers 0.000 claims abstract description 40
- 239000004926 polymethyl methacrylate Substances 0.000 claims abstract description 40
- 229920000642 polymer Polymers 0.000 claims abstract description 29
- 239000002270 dispersing agent Substances 0.000 claims abstract description 27
- 239000011248 coating agent Substances 0.000 claims abstract description 26
- 238000000576 coating method Methods 0.000 claims abstract description 26
- 239000000080 wetting agent Substances 0.000 claims abstract description 23
- 239000003381 stabilizer Substances 0.000 claims abstract description 22
- 239000000853 adhesive Substances 0.000 claims abstract description 20
- 230000001070 adhesive effect Effects 0.000 claims abstract description 20
- 239000008367 deionised water Substances 0.000 claims abstract description 12
- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 12
- 239000002994 raw material Substances 0.000 claims abstract description 11
- 238000003756 stirring Methods 0.000 claims description 90
- 239000000203 mixture Substances 0.000 claims description 89
- 229920001577 copolymer Polymers 0.000 claims description 33
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 claims description 32
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 27
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 claims description 26
- 239000006185 dispersion Substances 0.000 claims description 22
- -1 polyethylene Polymers 0.000 claims description 20
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 19
- 238000001035 drying Methods 0.000 claims description 18
- 238000001914 filtration Methods 0.000 claims description 17
- 239000002202 Polyethylene glycol Substances 0.000 claims description 13
- 239000001768 carboxy methyl cellulose Substances 0.000 claims description 13
- 229920001223 polyethylene glycol Polymers 0.000 claims description 13
- 239000003822 epoxy resin Substances 0.000 claims description 12
- 239000001866 hydroxypropyl methyl cellulose Substances 0.000 claims description 12
- 235000010979 hydroxypropyl methyl cellulose Nutrition 0.000 claims description 12
- 229920003088 hydroxypropyl methyl cellulose Polymers 0.000 claims description 12
- UFVKGYZPFZQRLF-UHFFFAOYSA-N hydroxypropyl methyl cellulose Chemical compound OC1C(O)C(OC)OC(CO)C1OC1C(O)C(O)C(OC2C(C(O)C(OC3C(C(O)C(O)C(CO)O3)O)C(CO)O2)O)C(CO)O1 UFVKGYZPFZQRLF-UHFFFAOYSA-N 0.000 claims description 12
- 229920000609 methyl cellulose Polymers 0.000 claims description 12
- 239000001923 methylcellulose Substances 0.000 claims description 12
- 235000010981 methylcellulose Nutrition 0.000 claims description 12
- 229920002239 polyacrylonitrile Polymers 0.000 claims description 12
- 229920000647 polyepoxide Polymers 0.000 claims description 12
- 229920003048 styrene butadiene rubber Polymers 0.000 claims description 12
- OQMIRQSWHKCKNJ-UHFFFAOYSA-N 1,1-difluoroethene;1,1,2,3,3,3-hexafluoroprop-1-ene Chemical group FC(F)=C.FC(F)=C(F)C(F)(F)F OQMIRQSWHKCKNJ-UHFFFAOYSA-N 0.000 claims description 11
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 11
- DPXJVFZANSGRMM-UHFFFAOYSA-N acetic acid;2,3,4,5,6-pentahydroxyhexanal;sodium Chemical compound [Na].CC(O)=O.OCC(O)C(O)C(O)C(O)C=O DPXJVFZANSGRMM-UHFFFAOYSA-N 0.000 claims description 11
- 235000011187 glycerol Nutrition 0.000 claims description 11
- 229920003145 methacrylic acid copolymer Polymers 0.000 claims description 11
- 229940117841 methacrylic acid copolymer Drugs 0.000 claims description 11
- IWVKTOUOPHGZRX-UHFFFAOYSA-N methyl 2-methylprop-2-enoate;2-methylprop-2-enoic acid Chemical compound CC(=C)C(O)=O.COC(=O)C(C)=C IWVKTOUOPHGZRX-UHFFFAOYSA-N 0.000 claims description 11
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 claims description 11
- 229920002037 poly(vinyl butyral) polymer Polymers 0.000 claims description 11
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 11
- 229920005989 resin Polymers 0.000 claims description 11
- 239000011347 resin Substances 0.000 claims description 11
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 claims description 11
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- LNAZSHAWQACDHT-XIYTZBAFSA-N (2r,3r,4s,5r,6s)-4,5-dimethoxy-2-(methoxymethyl)-3-[(2s,3r,4s,5r,6r)-3,4,5-trimethoxy-6-(methoxymethyl)oxan-2-yl]oxy-6-[(2r,3r,4s,5r,6r)-4,5,6-trimethoxy-2-(methoxymethyl)oxan-3-yl]oxyoxane Chemical compound CO[C@@H]1[C@@H](OC)[C@H](OC)[C@@H](COC)O[C@H]1O[C@H]1[C@H](OC)[C@@H](OC)[C@H](O[C@H]2[C@@H]([C@@H](OC)[C@H](OC)O[C@@H]2COC)OC)O[C@@H]1COC LNAZSHAWQACDHT-XIYTZBAFSA-N 0.000 claims description 2
- XLOFNXVVMRAGLZ-UHFFFAOYSA-N 1,1-difluoroethene;1,1,2-trifluoroethene Chemical group FC(F)=C.FC=C(F)F XLOFNXVVMRAGLZ-UHFFFAOYSA-N 0.000 claims description 2
- KPUWHANPEXNPJT-UHFFFAOYSA-N disiloxane Chemical class [SiH3]O[SiH3] KPUWHANPEXNPJT-UHFFFAOYSA-N 0.000 claims description 2
- 229920000058 polyacrylate Polymers 0.000 claims description 2
- 229920002635 polyurethane Polymers 0.000 claims description 2
- 239000004814 polyurethane Substances 0.000 claims description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 abstract description 14
- 229910052744 lithium Inorganic materials 0.000 abstract description 14
- 239000002245 particle Substances 0.000 abstract description 13
- 230000016507 interphase Effects 0.000 abstract description 6
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- 230000008961 swelling Effects 0.000 abstract description 5
- 206010027146 Melanoderma Diseases 0.000 abstract description 4
- 239000000243 solution Substances 0.000 description 18
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 16
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- WOBHKFSMXKNTIM-UHFFFAOYSA-N Hydroxyethyl methacrylate Chemical compound CC(=C)C(=O)OCCO WOBHKFSMXKNTIM-UHFFFAOYSA-N 0.000 description 8
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 8
- 238000010438 heat treatment Methods 0.000 description 8
- 239000007788 liquid Substances 0.000 description 8
- 229910052757 nitrogen Inorganic materials 0.000 description 8
- 239000000919 ceramic Substances 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- 230000009286 beneficial effect Effects 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 2
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- 238000011161 development Methods 0.000 description 2
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- 230000001804 emulsifying effect Effects 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 230000008719 thickening Effects 0.000 description 2
- XOOUIPVCVHRTMJ-UHFFFAOYSA-L zinc stearate Chemical compound [Zn+2].CCCCCCCCCCCCCCCCCC([O-])=O.CCCCCCCCCCCCCCCCCC([O-])=O XOOUIPVCVHRTMJ-UHFFFAOYSA-L 0.000 description 2
- 238000005054 agglomeration Methods 0.000 description 1
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- 239000007864 aqueous solution Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000000084 colloidal system Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 239000003906 humectant Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 229920000098 polyolefin Polymers 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Images
Classifications
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- 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
- C09J127/00—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 a halogen; Adhesives based on derivatives of such polymers
- C09J127/02—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 a halogen; Adhesives based on derivatives of such polymers not modified by chemical after-treatment
- C09J127/12—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 a halogen; Adhesives based on derivatives of such polymers not modified by chemical after-treatment containing fluorine atoms
- C09J127/16—Homopolymers or copolymers of vinylidene fluoride
-
- 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
- C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
- C09J11/02—Non-macromolecular additives
- C09J11/06—Non-macromolecular additives organic
-
- 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
- C09J11/00—Features of adhesives not provided for in group C09J9/00, e.g. additives
- C09J11/08—Macromolecular additives
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/403—Manufacturing processes of separators, membranes or diaphragms
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/411—Organic material
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/409—Separators, membranes or diaphragms characterised by the material
- H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
- H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
- H01M50/46—Separators, membranes or diaphragms characterised by their combination with electrodes
- H01M50/461—Separators, membranes or diaphragms characterised by their combination with electrodes with adhesive layers between electrodes and separators
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K2201/00—Specific properties of additives
- C08K2201/014—Additives containing two or more different additives of the same subgroup in C08K
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2203/00—Applications
- C08L2203/20—Applications use in electrical or conductive gadgets
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2205/00—Polymer mixtures characterised by other features
- C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2205/00—Polymer mixtures characterised by other features
- C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group
- C08L2205/025—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2205/00—Polymer mixtures characterised by other features
- C08L2205/03—Polymer mixtures characterised by other features containing three or more polymers in a blend
- C08L2205/035—Polymer mixtures characterised by other features containing three or more polymers in a blend containing four or more polymers in a blend
-
- 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
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- 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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Abstract
The invention relates to the technical field of lithium ion battery diaphragm coating, in particular to a high-cohesiveness water-based slurry for a diaphragm and a lithium ion battery diaphragm manufactured by applying the water-based slurry, wherein the water-based slurry comprises the following raw materials in parts by weight: 5-15% of PVDF polymer, 1-2.5% of PMMA copolymer, 3-5% of adhesive, 6-10% of stabilizer, 0.1-0.2% of wetting agent, 0.1-0.3% of dispersant and the balance of deionized water. According to the invention, the polarity and the steric hindrance of the PVDF polymer and the PMMA copolymer with different particle sizes and properties are utilized, so that colloidal particles in the prepared water system slurry can form an interphase form, the colloidal particles are coated on the surface of the diaphragm to improve the binding power of the diaphragm, and the risk of black spot lithium precipitation caused by swelling of a large amount of PMMA copolymer is reduced; the prepared water system slurry is applied to the lithium ion battery diaphragm, so that the strong bonding force between the lithium ion battery diaphragm and a pole piece can be enhanced, and the stability and the safety performance of the prepared lithium battery are effectively improved.
Description
Technical Field
The invention relates to the technical field of lithium ion battery diaphragm coating, in particular to a high-cohesiveness water-based slurry for a diaphragm and a lithium ion battery diaphragm manufactured by applying the same.
Background
The lithium ion battery diaphragm is used as an important component of the lithium ion battery, and the property of the diaphragm directly determines the capacity, the cycle performance, the charge-discharge current density and the safety of the battery. The adhesion between the diaphragm and the pole piece is also an important index for evaluating the quality of the diaphragm, and the direct bonding influences the hardness and the shape retention capability of the battery core. However, with the current demands of power and energy storage systems for high output and high capacity of batteries and the demands of 3C lithium battery rapid charging performance, the adhesion force of the diaphragm and the pole piece cannot meet the demands of these developments, so that the development of a more stable and more adhesive lithium ion battery diaphragm is urgently needed, and deformation and battery softening caused by thermal shock or other factors are reduced to the maximum extent.
Disclosure of Invention
In order to overcome the defects and shortcomings in the prior art, the invention aims to provide the water system slurry for the high-adhesion diaphragm, and the water system slurry for the high-adhesion diaphragm is prepared by utilizing the PVDF polymer and the PMMA copolymer with different particle sizes and properties, and the colloidal particles in the prepared water system slurry can form an interphase form and are coated on the surface of the ceramic diaphragm due to the polarity and the steric hindrance of the PVDF polymer and the PMMA copolymer, so that the higher adhesion is met, the risk of lithium precipitation caused by the swelling of a large amount of PMMA copolymer is reduced, and the stability and the safety performance of a lithium ion battery in use are improved.
The invention also aims to provide the application of the high-adhesion water-based slurry for the diaphragm in the lithium ion battery diaphragm, the lithium ion battery diaphragm using the water-based slurry has strong adhesion with a pole piece, and the stability and the safety performance of the prepared lithium battery in use are effectively improved.
The purpose of the invention is realized by the following technical scheme: the high-cohesiveness water-based slurry for the diaphragm comprises the following raw materials in parts by weight:
the aqueous slurry is prepared by the following steps:
1) adding deionized water, PVDF polymer, PMMA copolymer and adhesive into a stirrer with the rotation rate of 1000-1500r/min and the revolution rate of 30-40r/min according to the weight ratio, and stirring for 30-60min to obtain a mixture A for later use;
2) adding a stabilizer into the mixture A, and stirring for 30-60min while keeping the stirring speed unchanged to obtain a stable dispersion system B;
3) adding a dispersing agent into the dispersion system B, and stirring for 1.5-2h under the same stirring condition; then adding a wetting agent, reducing the stirring speed until the revolution speed is 10-20r/min, the rotation speed is 100-.
The water system slurry prepared by the method can form an interphase form by utilizing the polarity and steric hindrance of the PVDF polymer and the PMMA copolymer with different particle sizes and properties, and is coated on the surface of the ceramic diaphragm, so that higher cohesive force is met, the risk of black spot lithium precipitation caused by swelling of a large amount of PMMA copolymer is reduced, and the stability and the safety performance of a lithium ion battery in use are improved. In addition, the step 1) in the preparation process of the water system slurry mainly aims at enabling colloidal particles in the prepared water system slurry to form an interphase form by utilizing the polarity and the steric hindrance of the PVDF polymer and the PMMA copolymer and coating the colloidal particles on the surface of the ceramic diaphragm, so that higher cohesive force is met; meanwhile, the rotation rate of 1000-; the addition of the adhesive can effectively improve the adhesiveness of a slurry system, is beneficial to firmly combining the water system slurry and the matrix diaphragm when the water system slurry is coated on the diaphragm, and effectively improves the stability and safety performance of the prepared lithium battery in use.
Preferably, each part of the PVDF polymer is at least one of polyvinylidene fluoride, vinylidene fluoride-trifluoroethylene, polyvinyl alcohol resin, polyvinyl butyral and vinylidene fluoride-hexafluoropropylene; more preferably, the PVDF polymer is a mixture of modified polyvinylidene fluoride, polyvinyl alcohol resin, polyvinyl butyral and vinylidene fluoride-hexafluoropropylene in a weight ratio of 0.8-1.2:0.4-0.8:0.6-1.0: 0.1-0.5; the modified polyvinylidene fluoride is prepared by the following method: s1, adding 20-30 parts of polyvinylidene fluoride into 1-5 parts of N-methyl pyrrolidone and 4-8 parts of hydroxyethyl methacrylate solution, introducing ozone, and stirring for 20-40min to obtain a mixture solution for later use; s2, placing the mixture liquid obtained in the step S1 in a water bath, heating to 50-60 ℃ under the protection of nitrogen, stirring for 1-3h, and finally standing, filtering and drying to obtain the modified polyvinylidene fluoride.
The polyvinylidene fluoride used in the invention has stable chemical property and good heat resistance, but the membrane surface prepared from the polyvinylidene fluoride has strong hydrophobicity and is easy to generate adsorption pollution, so that the polyvinylidene fluoride needs to be modified, and the surface hydrophilic ability of the polyvinylidene fluoride modified by the method is enhanced, thus being beneficial to the dispersion of the polyvinylidene fluoride in slurry; the polyvinyl alcohol resin can avoid the characteristic of weak bonding property of pure PVDF, and can synergistically modify the excellent bonding property of polyvinylidene fluoride, polyvinyl butyral and vinylidene fluoride-hexafluoropropylene, so that the bonding property of the prepared water-based slurry can be further enhanced, and the bonding force of the lithium ion battery diaphragm and the pole piece prepared by the water-based slurry is favorably utilized.
Preferably, each part of the PMMA copolymer is at least one of a methyl methacrylate-methacrylic acid copolymer, a methyl methacrylate-ethacrylic acid copolymer, a methyl methacrylate-ethyl methacrylate copolymer and a methyl methacrylate-butyl methacrylate copolymer; more preferably, the PMMA copolymer is a mixture of a methyl methacrylate-methacrylic acid copolymer, a methyl methacrylate-ethacrylic acid copolymer, a methyl methacrylate-ethyl methacrylate copolymer and a methyl methacrylate-butyl methacrylate copolymer in a weight ratio of 0.6-1.0:0.8-1.2:0.1-0.5: 0.4-0.8.
According to the invention, the PMMA copolymer is adopted, so that the defect that color spots are easy to precipitate when pure PMMA is used for preparing the slurry can be avoided, and the polarity and the steric hindrance of the PMMA copolymer are utilized to enable colloidal particles in the prepared water system slurry to form an interphase form when the PMMA copolymer is compounded with the PVDF polymer, so that the prepared water system slurry can be coated on the surface of a ceramic diaphragm, and therefore, higher binding power is met, and the stability and the safety performance of the prepared lithium battery are effectively improved when the lithium battery.
Preferably, each part of the stabilizer is at least one of hydroxypropyl methylcellulose, sodium carboxymethyl cellulose and methylcellulose; more preferably, the stabilizer is a mixture of sodium carboxymethyl cellulose, methylcellulose and 4% of hydroxypropyl methylcellulose in a weight ratio of 0.6-1.0:0.8-1.2: 0.1-0.5. Each part of the adhesive is at least one of styrene-butadiene rubber, polyurethane, epoxy resin, acrylic polymer and acrylonitrile polymer; more preferably, the adhesive is a mixture of styrene-butadiene rubber, epoxy resin and acrylonitrile polymer in a weight ratio of 0.8-1.2:0.6-1.0: 0.4-0.8.
The hydroxypropyl methyl cellulose adopted in the invention can be dissolved in cold water to form transparent viscous solution, and has the characteristics of thickening, bonding, dispersing, emulsifying, film forming, suspending, adsorbing, gelling, surface activity, moisture retention, protective colloid and the like; the methyl cellulose is quite stable in aqueous solution at normal temperature, can be gelled at high temperature, can be mutually transformed with the solution along with the temperature, has excellent wettability, dispersibility, adhesiveness, thickening property, emulsifying property, water-retaining property and film-forming property, is beneficial to firmly combining water-based slurry and a substrate diaphragm when the water-based slurry is sprayed on the diaphragm, and strengthens the adhesive force between the lithium ion battery diaphragm and a pole piece; the adopted binder can well ensure that the water system slurry is uniformly coated on the surface of the substrate diaphragm and is not easy to fall off.
Preferably, each part of the wetting agent is at least one of siloxane, glycerol and N-methyl pyrrolidone; more preferably, the humectant is a mixture of silicone, glycerin and N-methyl pyrrolidone in a weight ratio of 0.8-1.2:0.4-0.8: 0.6-1.0. Each part of the dispersing agent is at least one of ethanol, polyethylene glycol and isopropanol; more preferably, the dispersing agent is a mixture of polyethylene glycol, isopropanol and 99% of ethanol by weight ratio of 0.4-0.8:0.8-1.2: 0.6-1.0.
The wetting agent adopted in the invention has the advantages of heat resistance, cold resistance, small viscosity change along with temperature, small surface tension, heat conductivity and the like, and can further assist in improving the caking property, the flame retardance and the electric conductivity of the prepared ceramic slurry in the process of preparing the water system slurry; the dispersing agent is a mixture consisting of polyethylene glycol, isopropanol and ethanol with the mass fraction of 99% according to the weight ratio of 0.4-0.8:0.8-1.2:0.6-1.0, and can increase the repulsive force among particles so as to overcome the agglomeration caused by the van der Waals attractive force among the particles.
The invention also provides a lithium ion battery diaphragm containing the high-adhesion water-based slurry coating for the diaphragm, which is obtained by coating the high-adhesion water-based slurry for the diaphragm on the surface of a polyethylene base film by a micro gravure coating mode at the speed of 40-60m/min, wherein the coating thickness is 1 mu m, and finally drying at the temperature of 40-50 ℃ for 0.5-3.0 min.
The lithium ion battery diaphragm using the water system slurry has strong binding power with the pole piece, and the stability and the safety performance of the prepared lithium battery during use are effectively improved.
The invention has the beneficial effects that: according to the invention, by utilizing the polarity and steric hindrance of the PVDF polymer and the PMMA copolymer with different particle sizes and properties, colloidal particles in the prepared water system slurry can form an interphase form and can be coated on the surface of the diaphragm, so that higher binding power is met, the risk of lithium precipitation caused by the swelling of a large amount of PMMA copolymer is reduced, and the stability and safety performance of the lithium ion battery in use are improved; the prepared water system slurry is applied to the lithium ion battery diaphragm, so that the strong bonding force between the lithium ion battery diaphragm and the pole piece can be enhanced, and the dry pressing bonding force between the diaphragm and the pole piece with the stability and safety performance when the prepared lithium battery is used is effectively improved.
Drawings
FIG. 1 is a graph comparing the dry press adhesion of aqueous slurry coating to a pole piece in accordance with the present invention.
Detailed Description
For the understanding of those skilled in the art, the present invention will be further described with reference to the following examples and the accompanying fig. 1, and the description of the embodiments is not intended to limit the present invention.
Example 1
The high-cohesiveness water-based slurry for the diaphragm comprises the following raw materials in parts by weight:
each part of the PVDF polymer is a mixture of modified polyvinylidene fluoride, polyvinyl alcohol resin, polyvinyl butyral and vinylidene fluoride-hexafluoropropylene in a weight ratio of 0.8:0.4:0.6: 0.1.
The modified polyvinylidene fluoride is prepared by the following method:
s1, adding 20 parts of polyvinylidene fluoride into 1 part of N-methyl pyrrolidone and 4 parts of hydroxyethyl methacrylate solution, introducing ozone, and stirring for 20min to obtain a mixture solution for later use;
s2, placing the mixture liquid obtained in the step S1 in a water bath, heating to 50 ℃, stirring for 1h under the protection of nitrogen, and finally standing, filtering and drying to obtain the modified polyvinylidene fluoride.
Each part of the PMMA copolymer is a mixture of methyl methacrylate-methacrylic acid copolymer, methyl methacrylate-ethacrylic acid copolymer, methyl methacrylate-ethyl methacrylate copolymer and methyl methacrylate-butyl methacrylate copolymer according to the weight ratio of 0.6:0.8:0.15: 0.4.
Each part of the stabilizer is a mixture of sodium carboxymethylcellulose, methylcellulose and 4% of hydroxypropyl methylcellulose in a weight ratio of 0.6:0.8: 0.1.
Each part of the adhesive is a mixture of styrene-butadiene rubber, epoxy resin E44 and acrylonitrile polymer PN-107 according to the weight ratio of 0.8:0.6: 0.4.
Each part of the wetting agent is a mixture of dimethyl siloxane, glycerol and N-methyl pyrrolidone according to the weight ratio of 0.8:0.4: 0.6.
Each part of the dispersing agent is a mixture of polyethylene glycol, isopropanol and 99% ethanol in a weight ratio of 0.4:0.8: 0.6.
The aqueous slurry is prepared by the following steps:
1) adding deionized water, PVDF polymer, PMMA copolymer and binder into a stirrer with the rotation rate of 1000r/min and the revolution rate of 30r/min according to the weight ratio, and stirring for 30min to obtain a mixture A for later use;
2) adding a stabilizer into the mixture A, and stirring for 30min while keeping the stirring speed unchanged to obtain a stable dispersion system B;
3) adding a dispersing agent into the dispersion system B, and stirring for 1.5h under the same stirring condition; and then adding a wetting agent, reducing the stirring speed until the revolution speed is 10r/min, the rotation speed is 100r/min and the stirring time is 25min, and filtering to obtain the finished product of the water system slurry.
The lithium ion battery diaphragm is prepared by coating the water-based slurry for the high-adhesion diaphragm on the surface of a polyethylene base film at the speed of 40m/min by utilizing a micro-gravure coating mode, wherein the coating thickness is 1 mu m, and finally, the lithium ion battery diaphragm is obtained after drying at the temperature of 40 ℃ for 0.5 min.
Example 2
The high-cohesiveness water-based slurry for the diaphragm comprises the following raw materials in parts by weight:
each part of the PVDF polymer is a mixture of modified polyvinylidene fluoride, polyvinyl alcohol resin, polyvinyl butyral and vinylidene fluoride-hexafluoropropylene in a weight ratio of 0.90.5:0.7: 0.2.
The modified polyvinylidene fluoride is prepared by the following method:
s1, adding 23 parts of polyvinylidene fluoride into 2 parts of N-methyl pyrrolidone and 5 parts of hydroxyethyl methacrylate solution, introducing ozone, and stirring for 25min to obtain a mixture solution for later use;
s2, placing the mixture liquid obtained in the step S1 in a water bath, heating to 53 ℃, stirring for 1.5 hours under the protection of nitrogen, and finally standing, filtering and drying to obtain the modified polyvinylidene fluoride.
Each part of the PMMA copolymer is a mixture of methyl methacrylate-methacrylic acid copolymer, methyl methacrylate-ethacrylic acid copolymer, methyl methacrylate-ethyl methacrylate copolymer and methyl methacrylate-butyl methacrylate copolymer according to the weight ratio of 0.7:0.9:0.2: 0.5.
Each part of the stabilizer is a mixture of sodium carboxymethyl cellulose, methylcellulose and 4% of hydroxypropyl methylcellulose in a weight ratio of 0.7:0.9: 0.2.
Each part of the adhesive is a mixture of styrene-butadiene rubber, epoxy resin E44 and acrylonitrile polymer PN-107 according to the weight ratio of 0.9:0.7: 0.5.
Each part of the wetting agent is a mixture of dimethyl siloxane, glycerol and N-methyl pyrrolidone according to the weight ratio of 0.9:0.5: 0.7.
Each part of the dispersing agent is a mixture of polyethylene glycol, isopropanol and 99% ethanol in a weight ratio of 0.5:0.9: 0.7.
The aqueous slurry is prepared by the following steps:
1) adding deionized water, PVDF polymer, PMMA copolymer and adhesive into a stirrer with the rotation rate of 1125r/min and the revolution rate of 33r/min according to the weight ratio, and stirring for 38min to obtain a mixture A for later use;
2) adding a stabilizer into the mixture A, and stirring for 38min while keeping the stirring speed unchanged to obtain a stable dispersion system B;
3) adding a dispersing agent into the dispersion system B, and stirring for 1.625h under the same stirring condition; and then adding a wetting agent, reducing the stirring speed until the revolution speed is 13r/min, the rotation speed is 125r/min, stirring for 28min, and filtering to obtain the finished product of water system slurry.
The lithium ion battery diaphragm is obtained by coating the high-adhesion water-based slurry for the diaphragm on the surface of a polyethylene base film at a speed of 45m/min by using a micro gravure coating mode, wherein the coating thickness is 1 mu m, and finally drying at the temperature of 43 ℃ for 1.1 min.
Example 3
The high-cohesiveness water-based slurry for the diaphragm comprises the following raw materials in parts by weight:
each part of the PVDF polymer is a mixture of modified polyvinylidene fluoride, polyvinyl alcohol resin, polyvinyl butyral and vinylidene fluoride-hexafluoropropylene in a weight ratio of 1.0:0.6:0.8: 0.3.
The modified polyvinylidene fluoride is prepared by the following method:
s1, adding 25 parts of polyvinylidene fluoride into 3 parts of N-methyl pyrrolidone and 6 parts of hydroxyethyl methacrylate solution, introducing ozone, and stirring for 30min to obtain a mixture solution for later use;
s2, placing the mixture liquid obtained in the step S1 in a water bath, heating to 55 ℃, stirring for 2 hours under the protection of nitrogen, and finally standing, filtering and drying to obtain the modified polyvinylidene fluoride.
Each part of the PMMA copolymer is a mixture of methyl methacrylate-methacrylic acid copolymer, methyl methacrylate-ethacrylic acid copolymer, methyl methacrylate-ethyl methacrylate copolymer and methyl methacrylate-butyl methacrylate copolymer according to the weight ratio of 0.8:1.0:0.3: 0.6.
Each part of the stabilizer is a mixture of sodium carboxymethylcellulose, methylcellulose and 4% of hydroxypropyl methylcellulose in a weight ratio of 0.8:1.0: 0.3.
Each part of the adhesive is a mixture of styrene-butadiene rubber, epoxy resin E44 and acrylonitrile polymer PN-107 according to the weight ratio of 1.0:0.8: 0.6.
Each part of the wetting agent is a mixture of dimethyl siloxane, glycerol and N-methyl pyrrolidone according to the weight ratio of 1.0:0.6: 0.8.
Each part of the dispersing agent is a mixture of polyethylene glycol, isopropanol and 99% ethanol in a weight ratio of 0.6:1.0: 0.8.
The aqueous slurry is prepared by the following steps:
1) adding deionized water, PVDF polymer, PMMA copolymer and binder into a stirrer with the rotation rate of 1250r/min and the revolution rate of 35r/min according to the weight ratio, and stirring for 45min to obtain a mixture A for later use;
2) adding a stabilizer into the mixture A, keeping the stirring speed unchanged, and stirring for 45min to obtain a stable dispersion system B;
3) adding a dispersing agent into the dispersion system B, and stirring for 1.75h under the same stirring condition; and then adding a wetting agent, reducing the stirring speed until the revolution speed is 15r/min, the rotation speed is 150r/min and the stirring time is 30min, and filtering to obtain the finished product of the water system slurry.
The lithium ion battery separator is obtained by coating the high-adhesion water-based slurry for the separator on the surface of a polyethylene base film at a speed of 50m/min by using a micro gravure coating method, wherein the coating thickness is 1 mu m, and finally drying at the temperature of 45 ℃ for 1.75 min.
Example 4
The high-cohesiveness water-based slurry for the diaphragm comprises the following raw materials in parts by weight:
each part of the PVDF polymer is a mixture of modified polyvinylidene fluoride, polyvinyl alcohol resin, polyvinyl butyral and vinylidene fluoride-hexafluoropropylene in a weight ratio of 1.1:0.7:0.9: 0.4.
The modified polyvinylidene fluoride is prepared by the following method:
s1, adding 28 parts of polyvinylidene fluoride into 4 parts of N-methyl pyrrolidone and 7 parts of hydroxyethyl methacrylate solution, introducing ozone, and stirring for 35min to obtain a mixture solution for later use;
s2, placing the mixture liquid obtained in the step S1 in a water bath, heating to 58 ℃ under the protection of nitrogen, stirring for 2.5 hours, and finally standing, filtering and drying to obtain the modified polyvinylidene fluoride.
Each part of the PMMA copolymer is a mixture of methyl methacrylate-methacrylic acid copolymer, methyl methacrylate-ethacrylic acid copolymer, methyl methacrylate-ethyl methacrylate copolymer and methyl methacrylate-butyl methacrylate copolymer according to the weight ratio of 0.9:1.1:0.4: 0.7.
Each part of the stabilizer is a mixture of sodium carboxymethylcellulose, methylcellulose and 4% of hydroxypropyl methylcellulose in a weight ratio of 0.9:1.1: 0.4.
Each part of the adhesive is a mixture of styrene-butadiene rubber, epoxy resin E44 and acrylonitrile polymer PN-107 according to the weight ratio of 1.1:0.9: 0.7.
Each part of the wetting agent is a mixture of dimethyl siloxane, glycerol and N-methyl pyrrolidone according to the weight ratio of 1.1:0.7: 0.9.
Each part of the dispersing agent is a mixture of polyethylene glycol, isopropanol and 99% ethanol in a weight ratio of 0.7:1.1: 0.9.
The aqueous slurry is prepared by the following steps:
1) adding deionized water, PVDF polymer, PMMA copolymer and adhesive into a stirrer with the rotation rate of 1375r/min and the revolution rate of 38r/min according to the weight ratio, and stirring for 52min to obtain a mixture A for later use;
2) adding a stabilizer into the mixture A, and stirring for 52min while keeping the stirring speed unchanged to obtain a stable dispersion system B;
3) adding a dispersing agent into the dispersion system B, and stirring for 1.825h under the same stirring condition; and then adding a wetting agent, reducing the stirring speed until the revolution speed is 18r/min, the rotation speed is 175r/min and the stirring time is 33min, and filtering to obtain the finished product of water system slurry.
The lithium ion battery diaphragm is prepared by coating the high-adhesion water-based slurry for the diaphragm on the surface of a polyethylene base film at a speed of 55m/min by using a micro gravure coating mode, wherein the coating thickness is 1 mu m, and finally, drying at the temperature of 48 ℃ for 2.3 min.
Example 5
The high-cohesiveness water-based slurry for the diaphragm comprises the following raw materials in parts by weight:
each part of the PVDF polymer is a mixture of modified polyvinylidene fluoride, polyvinyl alcohol resin, polyvinyl butyral and vinylidene fluoride-hexafluoropropylene in a weight ratio of 1.2:0.8:1.0: 0.5.
The modified polyvinylidene fluoride is prepared by the following method:
s1, adding 30 parts of polyvinylidene fluoride into 5 parts of N-methyl pyrrolidone and 8 parts of hydroxyethyl methacrylate solution, introducing ozone, and stirring for 40min to obtain a mixture solution for later use;
s2, placing the mixture liquid obtained in the step S1 in a water bath, heating to 60 ℃, stirring for 3 hours under the protection of nitrogen, and finally standing, filtering and drying to obtain the modified polyvinylidene fluoride.
Each part of the PMMA copolymer is a mixture consisting of a methyl methacrylate-methacrylic acid copolymer, a methyl methacrylate-ethacrylic acid copolymer, a methyl methacrylate-ethyl methacrylate copolymer and a methyl methacrylate-butyl methacrylate copolymer according to the weight ratio of 1.0:1.2:0.5: 0.8.
Each part of the stabilizer is a mixture of sodium carboxymethylcellulose, methylcellulose and 4% of hydroxypropyl methylcellulose in a weight ratio of 1.0:1.2: 0.5.
Each part of the adhesive is a mixture of styrene-butadiene rubber, epoxy resin E44 and acrylonitrile polymer PN-107 according to the weight ratio of 1.2:1.0: 0.8.
Each part of the wetting agent is a mixture of dimethyl siloxane, glycerol and N-methyl pyrrolidone according to the weight ratio of 1.2:0.8: 1.0.
Each part of the dispersing agent is a mixture of polyethylene glycol, isopropanol and 99% ethanol in a weight ratio of 0.8:1.2: 1.0.
The aqueous slurry is prepared by the following steps:
1) adding deionized water, PVDF polymer, PMMA copolymer and binder into a stirrer with the rotation rate of 1500r/min and the revolution rate of 40r/min according to the weight ratio, and stirring for 60min to obtain a mixture A for later use;
2) adding a stabilizer into the mixture A, and stirring for 60min while keeping the stirring speed unchanged to obtain a stable dispersion system B;
3) adding a dispersing agent into the dispersion system B, and stirring for 2 hours under the same stirring condition; and then adding a wetting agent, reducing the stirring speed until the revolution speed is 20r/min, the rotation speed is 200r/min and the stirring time is 35min, and filtering to obtain the finished product of the water system slurry.
The lithium ion battery diaphragm is prepared by coating the high-adhesion water-based slurry for the diaphragm on the surface of a polyethylene base film at a speed of 60m/min by using a micro gravure coating mode, wherein the coating thickness is 1 mu m, and finally, drying at the temperature of 50 ℃ for 3.0 min.
Comparative example 1
The high-cohesiveness water-based slurry for the diaphragm comprises the following raw materials in parts by weight:
each part of the PMMA copolymer is a mixture of methyl methacrylate-methacrylic acid copolymer, methyl methacrylate-ethacrylic acid copolymer, methyl methacrylate-ethyl methacrylate copolymer and methyl methacrylate-butyl methacrylate copolymer according to the weight ratio of 0.6:0.8:0.15: 0.4.
Each part of the stabilizer is a mixture of sodium carboxymethylcellulose, methylcellulose and 4% of hydroxypropyl methylcellulose in a weight ratio of 0.6:0.8: 0.1.
Each part of the adhesive is a mixture of styrene-butadiene rubber, epoxy resin E44 and acrylonitrile polymer PN-107 according to the weight ratio of 0.8:0.6: 0.4.
Each part of the wetting agent is a mixture of dimethyl siloxane, glycerol and N-methyl pyrrolidone according to the weight ratio of 0.8:0.4: 0.6.
Each part of the dispersing agent is a mixture of polyethylene glycol, isopropanol and 99% ethanol in a weight ratio of 0.4:0.8: 0.6.
The aqueous slurry is prepared by the following steps:
1) adding deionized water, pure PVDF, PMMA copolymer and adhesive into a stirrer with the rotation rate of 1000r/min and the revolution rate of 30r/min according to the weight ratio, and stirring for 30min to obtain a mixture A for later use;
2) adding a stabilizer into the mixture A, and stirring for 30min while keeping the stirring speed unchanged to obtain a stable dispersion system B;
3) adding a dispersing agent into the dispersion system B, and stirring for 1.5h under the same stirring condition; and then adding a wetting agent, reducing the stirring speed until the revolution speed is 10r/min, the rotation speed is 100r/min and the stirring time is 25min, and filtering to obtain the finished product of the water system slurry.
The lithium ion battery diaphragm is prepared by coating the water-based slurry for the high-adhesion diaphragm on the surface of a polyethylene base film at the speed of 40m/min by utilizing a micro-gravure coating mode, wherein the coating thickness is 1 mu m, and finally, the lithium ion battery diaphragm is obtained after drying at the temperature of 40 ℃ for 0.5 min.
Comparative example 2
The high-cohesiveness water-based slurry for the diaphragm comprises the following raw materials in parts by weight:
each part of the PVDF polymer is a mixture of modified polyvinylidene fluoride, polyvinyl alcohol resin, polyvinyl butyral and vinylidene fluoride-hexafluoropropylene in a weight ratio of 1.0:0.6:0.8: 0.3.
The modified polyvinylidene fluoride is prepared by the following method:
s1, adding 25 parts of polyvinylidene fluoride into 3 parts of N-methyl pyrrolidone and 6 parts of hydroxyethyl methacrylate solution, introducing ozone, and stirring for 30min to obtain a mixture solution for later use;
s2, placing the mixture liquid obtained in the step S1 in a water bath, heating to 55 ℃, stirring for 2 hours under the protection of nitrogen, and finally standing, filtering and drying to obtain the modified polyvinylidene fluoride.
Each part of the PMMA copolymer is a mixture of methyl methacrylate-methacrylic acid copolymer, methyl methacrylate-ethacrylic acid copolymer, methyl methacrylate-ethyl methacrylate copolymer and methyl methacrylate-butyl methacrylate copolymer according to the weight ratio of 0.8:1.0:0.3: 0.6.
Each part of the stabilizer is a mixture of sodium carboxymethylcellulose, methylcellulose and 4% of hydroxypropyl methylcellulose in a weight ratio of 0.8:1.0: 0.3.
Each portion of the binder is carboxymethyl cellulose.
Each part of the wetting agent is a mixture of dimethyl siloxane, glycerol and N-methyl pyrrolidone according to the weight ratio of 1.0:0.6: 0.8.
Each part of the dispersing agent is a mixture of polyethylene glycol, isopropanol and 99% ethanol in a weight ratio of 0.6:1.0: 0.8.
The aqueous slurry is prepared by the following steps:
1) adding deionized water, PVDF polymer, PMMA copolymer and binder into a stirrer with the rotation rate of 1250r/min and the revolution rate of 35r/min according to the weight ratio, and stirring for 45min to obtain a mixture A for later use;
2) adding a stabilizer into the mixture A, keeping the stirring speed unchanged, and stirring for 45min to obtain a stable dispersion system B;
3) adding a dispersing agent into the dispersion system B, and stirring for 1.75h under the same stirring condition; and then adding a wetting agent, reducing the stirring speed until the revolution speed is 15r/min, the rotation speed is 150r/min and the stirring time is 30min, and filtering to obtain the finished product of the water system slurry.
The lithium ion battery separator is obtained by coating the high-adhesion water-based slurry for the separator on the surface of a polyethylene base film at a speed of 50m/min by using a micro gravure coating method, wherein the coating thickness is 1 mu m, and finally drying at the temperature of 45 ℃ for 1.75 min.
Comparative example 3
The high-cohesiveness water-based slurry for the diaphragm comprises the following raw materials in parts by weight:
each part of the PVDF polymer is a mixture of modified polyvinylidene fluoride, polyvinyl alcohol resin, polyvinyl butyral and vinylidene fluoride-hexafluoropropylene in a weight ratio of 1.2:0.8:1.0: 0.5.
The modified polyvinylidene fluoride is prepared by the following method:
s1, adding 30 parts of polyvinylidene fluoride into 5 parts of N-methyl pyrrolidone and 8 parts of hydroxyethyl methacrylate solution, introducing ozone, and stirring for 40min to obtain a mixture solution for later use;
s2, placing the mixture liquid obtained in the step S1 in a water bath, heating to 60 ℃, stirring for 3 hours under the protection of nitrogen, and finally standing, filtering and drying to obtain the modified polyvinylidene fluoride.
Each part of the PMMA copolymer is a mixture consisting of a methyl methacrylate-methacrylic acid copolymer, a methyl methacrylate-ethacrylic acid copolymer, a methyl methacrylate-ethyl methacrylate copolymer and a methyl methacrylate-butyl methacrylate copolymer according to the weight ratio of 1.0:1.2:0.5: 0.8.
Each part of the stabilizer is a mixture of sodium carboxymethylcellulose, methylcellulose and 4% of hydroxypropyl methylcellulose in a weight ratio of 1.0:1.2: 0.5.
Each part of the adhesive is a mixture of styrene-butadiene rubber, epoxy resin E44 and acrylonitrile polymer PN-107 according to the weight ratio of 1.2:1.0: 0.8.
Each part of the wetting agent is a mixture of dimethyl siloxane, glycerol and N-methyl pyrrolidone according to the weight ratio of 1.2:0.8: 1.0.
Each part of the dispersing agent is a mixture of zinc stearate and amine stearate according to the weight ratio of 0.8: 1.0.
The aqueous slurry is prepared by the following steps:
1) adding deionized water, PVDF polymer, PMMA copolymer and binder into a stirrer with the rotation rate of 1500r/min and the revolution rate of 40r/min according to the weight ratio, and stirring for 60min to obtain a mixture A for later use;
2) adding a stabilizer into the mixture A, and stirring for 60min while keeping the stirring speed unchanged to obtain a stable dispersion system B;
3) adding a dispersing agent into the dispersion system B, and stirring for 2 hours under the same stirring condition; and then adding a wetting agent, reducing the stirring speed until the revolution speed is 20r/min, the rotation speed is 200r/min and the stirring time is 35min, and filtering to obtain the finished product of the water system slurry.
The lithium ion battery diaphragm is prepared by coating the high-adhesion water-based slurry for the diaphragm on the surface of a polyethylene base film at a speed of 60m/min by using a micro gravure coating mode, wherein the coating thickness is 1 mu m, and finally, drying at the temperature of 50 ℃ for 3.0 min.
The lithium ion battery separators containing the water-based slurry coating for high-adhesion separators according to the present invention according to the above-described examples 1 to 5 and comparative examples 1 to 3 were subjected to insulation breakdown, peel strength and dry-press adhesion tests, and the results are shown in the following table 1:
taking a 12um polyolefin diaphragm as an example, a single-sided 1um high-adhesion slurry coating is coated, and the dry-pressing adhesion of the coating to a pole piece is shown in the attached figure 1: from the data comparison result of the attached figure 1, the dry-pressing adhesion of the diaphragm and the pole piece coated by the formula is about 3 times that of the pure PVDF coated by the same gram weight, and is much smaller than that of the pure PMMA coated by the same gram weight, but if the PMMA coated by the same gram weight is coated, the problems of black spot lithium precipitation and the like caused by excessive PMMA swelling can be caused, and the diaphragm and the pole piece are not suitable for actual production (the coating amount of the PMMA is greatly reduced to prevent the black spot lithium precipitation during the actual production, but the dry-pressing adhesion of the appropriate coating amount is almost the same as that of the pure PVDF);
the dry-pressing adhesion testing method comprises the following steps: the diaphragm coated by the aqueous slurry is cut into blocks with the size of 30mm x 50mm, and is hot-pressed for 5min with a positive plate with the same size under the conditions of 90 ℃ and 1MPa of pressure, and the stripping force between the pole piece and the diaphragm in the length direction is tested.
TABLE 1
| Item | Dry pressure bonding (N/m) | Insulation breakdown (V) | Peel strength (gf) |
| Example 1 | 16 | 1466 | 736 |
| Example 2 | 15 | 1473 | 740 |
| Example 3 | 13 | 1487 | 744 |
| Example 4 | 14 | 1436 | 737 |
| Example 5 | 15 | 1442 | 735 |
| Comparative example 1 | 5 | 1342 | 536 |
| Comparative example 2 | 3 | 1238 | 542 |
| Comparative example 3 | 4 | 1412 | 659 |
As can be seen from table 1 above, the separator coated with the aqueous slurry containing the high-adhesion separator in embodiments 1 to 5 of the present invention has good insulation breakdown, peel strength and dry-pressing adhesion, so that the problem of poor adhesion between the separator and the electrode plate at present is fundamentally solved, and the adhesion between the separator coated with the aqueous slurry and the electrode plate is improved, thereby improving the stability and safety of the lithium ion battery in use, and simultaneously reducing the complexity of the conventional process and the production cost in the production process.
Compared with the example 1, in the comparative example 1, pure PVDF is used for replacing PVDF polymers when the aqueous slurry is prepared, insulation breakdown, peeling strength and dry-pressing adhesion force tests are carried out on the lithium ion battery diaphragm coated by the aqueous slurry, and analysis shows that the dry-pressing adhesion force of the battery diaphragm is remarkably reduced, and the insulation breakdown and peeling strength are relatively reduced; the PVDF polymer is added when the water system slurry is prepared, so that the prepared water system slurry can improve various performances of the diaphragm, particularly dry-pressing adhesion, after the prepared water system slurry is coated on the lithium ion battery diaphragm.
Compared with example 3, in comparative example 2, the mixed adhesive consisting of styrene-butadiene rubber, epoxy resin E44 and acrylonitrile polymer PN-107 in a weight ratio of 1.0:0.8:0.6 is replaced by carboxymethyl cellulose when the aqueous slurry is prepared, and after the lithium ion battery diaphragm coated by the aqueous slurry is subjected to insulation breakdown, peeling strength and dry pressure adhesion test, analysis shows that the dry pressure adhesion of the battery diaphragm is remarkably reduced, and the insulation breakdown and the peeling strength are relatively reduced; the invention is proved that when the water system slurry is prepared, the mixed adhesive which consists of the styrene butadiene rubber, the epoxy resin and the acrylonitrile polymer according to the weight ratio of 1.0:0.8:0.6 is added, so that the prepared water system slurry can improve various performances of the diaphragm, particularly the dry-pressing binding power after the prepared water system slurry is coated on the lithium ion battery diaphragm.
Compared with example 5, in comparative example 3, the mixed dispersant consisting of ethanol, polyethylene glycol and isopropanol with the mass fraction of 99% is used for replacing the mixed dispersant consisting of zinc stearate and amine stearate in the weight ratio of 0.8:1.0 in the preparation of the water-based slurry, and the tests of insulation breakdown, peeling strength and dry pressure bonding force are carried out after the lithium ion battery diaphragm coated by the water-based slurry, and the dry pressure bonding force, insulation breakdown and peeling strength of the battery diaphragm are relatively reduced through analysis; the invention is shown that when the water system slurry is prepared, a mixed dispersant consisting of ethanol, polyethylene glycol and isopropanol with the mass fraction of 99% according to the weight ratio of 0.8:1.2:1.0 is added, so that the prepared water system slurry can improve various performances of the diaphragm after being coated on the lithium ion battery diaphragm.
The above-described embodiments are preferred implementations of the present invention, and the present invention may be implemented in other ways without departing from the spirit of the present invention.
Claims (10)
1. A high-cohesiveness water-based slurry for a diaphragm is characterized in that: the feed comprises the following raw materials in parts by weight:
the balance being deionized water.
2. A high-adhesiveness water-based paste for separators as claimed in claim 1, wherein: each part of the PVDF polymer is at least one of polyvinylidene fluoride, vinylidene fluoride-trifluoroethylene, polyvinyl alcohol resin, polyvinyl butyral and vinylidene fluoride-hexafluoropropylene.
3. A high-adhesiveness water-based paste for separators as claimed in claim 1, wherein: each part of the PMMA copolymer is at least one of methyl methacrylate-methacrylic acid copolymer, methyl methacrylate-ethacrylic acid copolymer, methyl methacrylate-ethyl methacrylate copolymer and methyl methacrylate-butyl methacrylate copolymer.
4. A high-adhesiveness water-based paste for separators as claimed in claim 1, wherein: each part of the stabilizer is at least one of hydroxypropyl methylcellulose, sodium carboxymethylcellulose and methylcellulose.
5. A high-adhesiveness water-based paste for separators as claimed in claim 1, wherein: each part of the adhesive is at least one of styrene-butadiene rubber, polyurethane, epoxy resin, acrylic polymer and acrylonitrile polymer.
6. A high-adhesiveness water-based paste for separators as claimed in claim 1, wherein: each part of the wetting agent is at least one of siloxane, glycerol and N-methyl pyrrolidone.
7. A high-adhesiveness water-based paste for separators as claimed in claim 1, wherein: each part of the dispersing agent is at least one of ethanol, polyethylene glycol and isopropanol.
8. A high-cohesiveness aqueous slurry for separators as set forth in any one of claims 1 to 7, wherein: the aqueous slurry is prepared by the following steps:
1) adding deionized water, PVDF polymer, PMMA copolymer and binder into a stirrer according to the weight ratio, and stirring to obtain a mixture A for later use;
2) adding a stabilizer into the mixture A, and stirring while keeping the stirring speed unchanged to obtain a stable dispersion system B;
3) and adding a dispersing agent into the dispersion system B, stirring under the same stirring condition, adding a wetting agent, reducing the stirring speed, stirring, and filtering to obtain the finished product of the water-based slurry.
9. A high-adhesiveness water-based paste for separators as claimed in claim 8, wherein: the stirring speed in the step 1) is 1000-1500r/min of rotation speed and 30-40r/min of revolution speed; the stirring time in the step 2) is 30-60 min; the stirring time after the dispersant is added into the dispersion system B in the step 3) is 1.5 to 2 hours, the stirring speed after the wetting agent is added is 10 to 20r/min of revolution speed, 200r/min of rotation speed and 25 to 35min of stirring speed.
10. A lithium ion battery diaphragm containing a high-cohesiveness water-based slurry coating for diaphragms is characterized in that: the lithium ion battery diaphragm is obtained by coating the water-based slurry for the high-adhesion diaphragm of claims 1 to 7 on the surface of a polyethylene base film at a speed of 40 to 60m/min by utilizing a micro-gravure coating mode, wherein the coating thickness is 1 mu m, and finally, drying at the temperature of 40 to 50 ℃ for 0.5 to 3.0 min.
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