CN116487588A - Composite binder, preparation method thereof, electrode plate and lithium ion battery - Google Patents
Composite binder, preparation method thereof, electrode plate and lithium ion battery Download PDFInfo
- Publication number
- CN116487588A CN116487588A CN202210051318.7A CN202210051318A CN116487588A CN 116487588 A CN116487588 A CN 116487588A CN 202210051318 A CN202210051318 A CN 202210051318A CN 116487588 A CN116487588 A CN 116487588A
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- monomer
- binder
- composite
- composite binder
- lithium ion
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- 239000002131 composite material Substances 0.000 title claims abstract description 69
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 43
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 43
- 239000011230 binding agent Substances 0.000 title claims description 71
- 238000002360 preparation method Methods 0.000 title abstract description 12
- 239000000178 monomer Substances 0.000 claims abstract description 129
- 239000000853 adhesive Substances 0.000 claims abstract description 31
- 230000001070 adhesive effect Effects 0.000 claims abstract description 31
- 239000004020 conductor Substances 0.000 claims abstract description 27
- 150000007524 organic acids Chemical class 0.000 claims abstract description 26
- 229920000642 polymer Polymers 0.000 claims abstract description 19
- 238000001035 drying Methods 0.000 claims abstract description 15
- 230000000379 polymerizing effect Effects 0.000 claims abstract description 4
- UEXCJVNBTNXOEH-UHFFFAOYSA-N Ethynylbenzene Chemical group C#CC1=CC=CC=C1 UEXCJVNBTNXOEH-UHFFFAOYSA-N 0.000 claims description 38
- 238000000034 method Methods 0.000 claims description 27
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims description 24
- BQCIDUSAKPWEOX-UHFFFAOYSA-N 1,1-Difluoroethene Chemical group FC(F)=C BQCIDUSAKPWEOX-UHFFFAOYSA-N 0.000 claims description 21
- 239000003999 initiator Substances 0.000 claims description 18
- 239000002904 solvent Substances 0.000 claims description 16
- 239000006258 conductive agent Substances 0.000 claims description 15
- 239000007772 electrode material Substances 0.000 claims description 15
- 239000011259 mixed solution Substances 0.000 claims description 15
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical group CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 14
- 238000006243 chemical reaction Methods 0.000 claims description 13
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 claims description 12
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 12
- 239000000243 solution Substances 0.000 claims description 12
- 238000003756 stirring Methods 0.000 claims description 10
- 239000007789 gas Substances 0.000 claims description 9
- 238000010438 heat treatment Methods 0.000 claims description 8
- YTPLMLYBLZKORZ-UHFFFAOYSA-N Thiophene Chemical compound C=1C=CSC=1 YTPLMLYBLZKORZ-UHFFFAOYSA-N 0.000 claims description 7
- OZAIFHULBGXAKX-UHFFFAOYSA-N 2-(2-cyanopropan-2-yldiazenyl)-2-methylpropanenitrile Chemical compound N#CC(C)(C)N=NC(C)(C)C#N OZAIFHULBGXAKX-UHFFFAOYSA-N 0.000 claims description 6
- PAYRUJLWNCNPSJ-UHFFFAOYSA-N Aniline Chemical compound NC1=CC=CC=C1 PAYRUJLWNCNPSJ-UHFFFAOYSA-N 0.000 claims description 6
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 6
- KAESVJOAVNADME-UHFFFAOYSA-N Pyrrole Chemical compound C=1C=CNC=1 KAESVJOAVNADME-UHFFFAOYSA-N 0.000 claims description 6
- 239000012298 atmosphere Substances 0.000 claims description 6
- WLJVXDMOQOGPHL-UHFFFAOYSA-N phenylacetic acid Chemical compound OC(=O)CC1=CC=CC=C1 WLJVXDMOQOGPHL-UHFFFAOYSA-N 0.000 claims description 6
- 230000001681 protective effect Effects 0.000 claims description 6
- 238000001556 precipitation Methods 0.000 claims description 5
- MIZLGWKEZAPEFJ-UHFFFAOYSA-N 1,1,2-trifluoroethene Chemical group FC=C(F)F MIZLGWKEZAPEFJ-UHFFFAOYSA-N 0.000 claims description 4
- OMPJBNCRMGITSC-UHFFFAOYSA-N Benzoylperoxide Chemical compound C=1C=CC=CC=1C(=O)OOC(=O)C1=CC=CC=C1 OMPJBNCRMGITSC-UHFFFAOYSA-N 0.000 claims description 4
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 4
- -1 alkyl peroxide Chemical class 0.000 claims description 4
- 235000019400 benzoyl peroxide Nutrition 0.000 claims description 4
- BFKJFAAPBSQJPD-UHFFFAOYSA-N tetrafluoroethene Chemical group FC(F)=C(F)F BFKJFAAPBSQJPD-UHFFFAOYSA-N 0.000 claims description 4
- 239000012295 chemical reaction liquid Substances 0.000 claims description 3
- 238000004140 cleaning Methods 0.000 claims description 3
- 238000001914 filtration Methods 0.000 claims description 3
- 239000001257 hydrogen Substances 0.000 claims description 3
- 229910052739 hydrogen Inorganic materials 0.000 claims description 3
- 239000003960 organic solvent Substances 0.000 claims description 3
- 229960003424 phenylacetic acid Drugs 0.000 claims description 3
- 239000003279 phenylacetic acid Substances 0.000 claims description 3
- 229930192474 thiophene Natural products 0.000 claims description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 2
- 125000005396 acrylic acid ester group Chemical group 0.000 claims description 2
- 230000000052 comparative effect Effects 0.000 description 12
- 239000000463 material Substances 0.000 description 8
- 238000005098 hot rolling Methods 0.000 description 7
- 230000014759 maintenance of location Effects 0.000 description 6
- 238000006116 polymerization reaction Methods 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000011056 performance test Methods 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 239000003792 electrolyte Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000005096 rolling process Methods 0.000 description 3
- 229910052786 argon Inorganic materials 0.000 description 2
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 2
- 238000013329 compounding Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 239000010439 graphite Substances 0.000 description 2
- 229910002804 graphite Inorganic materials 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 238000003475 lamination Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 239000013557 residual solvent Substances 0.000 description 2
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical group [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910001228 Li[Ni1/3Co1/3Mn1/3]O2 (NCM 111) Inorganic materials 0.000 description 1
- 101150058243 Lipf gene Proteins 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 239000006230 acetylene black Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 239000012300 argon atmosphere Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000002041 carbon nanotube Substances 0.000 description 1
- 229910021393 carbon nanotube Inorganic materials 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- AIJRZQRTCRIQFY-UHFFFAOYSA-N dilithium cobalt(2+) dioxido(dioxo)manganese nickel(2+) Chemical compound [Li+].[Mn](=O)(=O)([O-])[O-].[Co+2].[Ni+2].[Li+].[Mn](=O)(=O)([O-])[O-].[Mn](=O)(=O)([O-])[O-] AIJRZQRTCRIQFY-UHFFFAOYSA-N 0.000 description 1
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 1
- 239000012153 distilled water Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 229910021385 hard carbon Inorganic materials 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 229920001519 homopolymer Polymers 0.000 description 1
- 150000002431 hydrogen Chemical class 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 1
- 230000003446 memory effect Effects 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 239000012934 organic peroxide initiator Substances 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000002985 plastic film Substances 0.000 description 1
- 229920006255 plastic film Polymers 0.000 description 1
- 239000007774 positive electrode material Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
- 229910021384 soft carbon Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
- H01M4/623—Binders being polymers fluorinated 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
- C08F214/00—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
- C08F214/18—Monomers containing fluorine
- C08F214/22—Vinylidene fluoride
- C08F214/225—Vinylidene fluoride with non-fluorinated comonomers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
-
- 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
- C08F238/00—Copolymers of compounds having one or more carbon-to-carbon triple bonds
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The embodiment of the invention discloses a composite adhesive and a preparation method thereof, an electrode plate and a lithium ion battery, wherein the composite adhesive comprises a polymer formed by polymerizing an adhesive monomer, an organic acid monomer and a conductive material monomer, so that the adhesive can be used for preparing the electrode plate and the lithium ion battery by a dry process, the adhesive force between the dry electrode layer on the electrode plate and a current collector can be effectively improved, and the cycle performance of the lithium ion battery is improved; meanwhile, the composite adhesive has certain conductivity, so that the conductivity of the electrode plate can be effectively improved, the internal resistance of the electrode plate can be reduced, and the rate capability of the lithium ion battery can be effectively improved.
Description
Technical Field
The invention relates to the technical field of secondary batteries, in particular to a composite binder, a preparation method thereof, an electrode plate and a lithium ion battery.
Background
The lithium ion battery has the advantages of high specific capacity, long cycle life, low self-discharge rate, no memory effect, environmental friendliness and the like, so that the lithium ion battery is widely applied to various fields. The electrode plate is an important component in the lithium ion battery, is a carrier and a transmission path of lithium ions and electrons, and the performance of the electrode plate influences the internal resistance of the battery, thereby influencing the multiplying power performance and the cycle performance of the battery. Currently, the preparation method of the electrode sheet comprises a wet process and a dry process. The dry process avoids the use of solvents, so that energy loss during drying of the solvents can be reduced, and adverse effects of residual solvents on the service life of the battery are avoided. However, the existing dry process electrode plate has the defects that the internal resistance of the positive electrode plate and the negative electrode plate is high due to poor distribution uniformity of components and poor cohesive force of a binder during mixing, and the rate performance and the cycle performance of the battery are affected.
Disclosure of Invention
The embodiment of the invention aims to provide a composite adhesive, a preparation method thereof, an electrode plate and a lithium ion battery, which can solve at least part of the defects in the prior art.
In a first aspect, embodiments of the present invention provide a composite binder comprising a polymer formed by polymerizing a binder monomer, an organic acid monomer, and a conductive material monomer.
In some embodiments, the binder monomer is a vinylidene fluoride monomer, the organic acid monomer is an acrylic acid monomer, and the conductive material monomer is a phenylacetylene monomer; the mass ratio of the vinylidene fluoride monomer to the acrylic acid monomer to the phenylacetylene monomer is 1.0 (0.2-1.0) to 0.2-1.0.
In some embodiments, the mass ratio of the vinylidene fluoride monomer, the acrylic monomer and the phenylacetylene monomer is 1.0 (0.4-0.8): 0.5-1.0.
In a second aspect, an embodiment of the present invention further provides a method for preparing a composite binder, where the method includes the following steps: dissolving a binder monomer, an organic acid monomer and a conductive material monomer in a first solvent to form a mixed solution, wherein the first solvent is an organic solvent without active hydrogen; adding an initiator into the mixed solution, and heating and stirring under a protective gas atmosphere to obtain a reaction solution; and adding the reaction liquid into a polymer precipitant for precipitation, and filtering, cleaning and drying to obtain the composite binder.
In some embodiments, the binder monomer is a vinylidene fluoride monomer, the organic acid monomer is an acrylic acid monomer, and the conductive material monomer is a phenylacetylene monomer; the mass ratio of the vinylidene fluoride monomer to the acrylic acid monomer to the phenylacetylene monomer is 1.0 (0.2-1.0) to 0.2-1.0.
In some embodiments, the ratio of the mass of the initiator to the sum of the mass of the binder monomer, the organic acid monomer, and the conductive material monomer is 0.1:100 to 3:100.
In some embodiments, the temperature of the heating and stirring under the protective gas atmosphere is 30-120 ℃ for 10-24 hours.
In some embodiments, the reaction solution is allowed to stand at room temperature prior to adding the reaction solution to the polymer precipitant for precipitation.
In some embodiments, the drying is at a temperature of less than 50 ℃ for a period of 8 to 24 hours.
In some embodiments, the binder monomer comprises at least one of vinylidene fluoride, trifluoroethylene, or tetrafluoroethylene; the conductive material monomer comprises at least one of phenylacetylene, aniline, thiophene or pyrrole; the organic acid monomer comprises at least one of acrylic acid, acrylic acid ester or phenylacetic acid.
In some embodiments, the initiator comprises at least one of azobisisobutyronitrile, dibenzoyl peroxide, or an alkyl peroxide.
In some embodiments, the first solvent is N, N-dimethylformamide or N-methylpyrrolidone, and the polymer precipitant comprises methanol or ethanol.
In a third aspect, the embodiment of the invention also provides an electrode slice, which comprises a current collector and a dry electrode layer; the dry electrode layer is arranged on the current collector and comprises an electrode active material, a conductive agent and a composite binder; wherein the composite binder comprises the composite binder according to the first aspect or the composite binder obtained according to the method of the second aspect.
In some embodiments, the mass percentage of the electrode active material in the dry electrode layer is 90-98%; the mass percentage of the conductive agent in the dry electrode layer is 1-5%; the mass percentage of the composite binder in the dry electrode layer is 1-5%.
In a fourth aspect, an embodiment of the present invention further provides a lithium ion battery, including an electrode slice according to the third aspect.
The embodiment of the invention provides a composite binder, a preparation method of the composite binder, an electrode plate and a lithium ion battery, wherein the composite binder comprises a polymer formed by polymerizing binder monomers, organic acid monomers and conductive material monomers, so that the electrode plate and the lithium ion battery which are prepared by a dry process by using the composite binder can effectively improve the adhesive force between a dry electrode layer on the electrode plate and a current collector and improve the cycle performance of the lithium ion battery; meanwhile, the composite adhesive has certain conductivity, so that the conductivity of the electrode plate can be effectively improved, the internal resistance of the electrode plate can be reduced, and the rate capability of the lithium ion battery can be effectively improved.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent from the following description of embodiments of the present invention with reference to the accompanying drawings, in which:
FIG. 1 is a schematic flow chart of a method for preparing a composite adhesive according to an embodiment of the present invention;
fig. 2 is a schematic flow chart of a method for manufacturing an electrode sheet according to an embodiment of the present invention;
fig. 3 is a schematic diagram showing the results of the lithium ion battery magnification test of example 1 and comparative example of the present invention;
fig. 4 is a schematic diagram showing the results of the cycle performance test of the lithium ion battery of example 1 and comparative example of the present invention.
Detailed Description
The present invention is described below based on examples, but the present invention is not limited to only these examples. In the following detailed description of the present invention, certain specific details are set forth in detail. The present invention will be fully understood by those skilled in the art without the details described herein. Well-known methods, procedures, flows, components and circuits have not been described in detail so as not to obscure the nature of the invention.
Moreover, those of ordinary skill in the art will appreciate that the drawings are provided herein for illustrative purposes and that the drawings are not necessarily drawn to scale.
Unless the context clearly requires otherwise, the words "comprise," "comprising," and the like throughout the application are to be construed as including but not being exclusive or exhaustive; that is, it is the meaning of "including but not limited to".
In the description of the present invention, it should be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Furthermore, in the description of the present invention, unless otherwise indicated, the meaning of "a plurality" is two or more.
Fig. 1 is a schematic flow chart of a method for preparing a composite adhesive according to an embodiment of the present invention.
Referring to fig. 1, the method for preparing a composite adhesive according to an embodiment of the present invention includes steps S110 to S130 as follows:
step S110, the binder monomer, the organic acid monomer and the conductive material monomer are dissolved in a first solvent to form a mixed solution.
The adhesive monomer, the organic acid monomer and the conductive material monomer are dissolved in a first solvent according to a certain proportion to form a mixed solution.
In an embodiment of the invention, the binder monomer is used to play a binding role in the composite binder formed by polymerization. The kind of the binder monomer may be selected as needed, and specifically, the monomer material of the binder for an electrode may be selected, and for example, at least one of vinylidene fluoride (VDF), trifluoroethylene (TrFE), tetrafluoroethylene (TFE), or other binder monomer may be included.
The organic acid monomer may include acrylic acid (C 3 H 4 O 2 ) Acrylate (ch2=chcoor), phenylacetic acid (C 8 H 8 O 2 ) Or one or more of the other carboxylic acid-containing weak acids. When the composite adhesive prepared by the method disclosed by the embodiment of the invention is used for preparing the dry electrode slice, the organic acid can generate a certain micro corrosion effect on the surface of the current collector, so that a plurality of micro pits are formed on the surface of the current collector, and the adhesive force between the electrode material and the current collector can be enhanced.
The monomer of conductive material is used for making the prepared composite adhesive have certain conductivity, and can be selected from compound with conjugated effect, for example phenylacetylene (C 8 H 6 ) Aniline (C) 6 H 7 N), thiophene (1-thia-2, 4-cyclopentadiene, C 4 H 4 S), pyrrole (C) 4 H 5 N) or other conductive material monomers. When the composite adhesive prepared by the method disclosed by the embodiment of the invention is used for preparing the dry electrode slice, the conductive material monomer can enable the composite adhesive to have certain conductive performance, so that the internal resistance of the dry electrode slice can be reduced.
In one embodiment, the binder monomer is vinylidene fluoride monomer, the organic acid monomer is acrylic acid monomer, the conductive material monomer is phenylacetylene monomer, and the mass ratio of the vinylidene fluoride monomer, the acrylic acid monomer and the phenylacetylene monomer is 1.0 (0.2-1.0). Preferably, the mass ratio of the vinylidene fluoride monomer, the acrylic monomer and the phenylacetylene monomer is 1.0 (0.4-0.8): (0.5-1.0), and can be 1.0:0.4:0.5, 1.0:0.8:0.5, 1.0:0.4:1.0, 1.0:0.6:0.6, etc.
In step S110, the first solvent is an organic solvent that does not contain active hydrogen, and is prevented from reacting with the organic acid monomer. For example, the first solvent may include N, N-Dimethylformamide (DMF), N-methylpyrrolidone (NMP), dimethylsulfoxide (DMSO), and the like.
And step S120, adding an initiator into the mixed solution, and heating and stirring under the atmosphere of protective gas to obtain a reaction solution.
And (2) adding an initiator into the mixed solution obtained in the step (S110), and heating and stirring the mixed solution added with the initiator under the atmosphere of protective gas to enable the mixed solution added with the initiator to undergo polymerization reaction so as to obtain a reaction solution.
The initiator is heated to decompose into free radicals, and the binder monomer, the organic acid monomer and the conductive material monomer in the mixed solution are initiated to polymerize. The kind of the initiator may be selected according to the kind of the binder monomer, the temperature of the polymerization reaction, and the like. For example, the initiator in the present embodiment may include at least one of azo-type initiators (e.g., azobisisobutyronitrile), organic peroxide initiators (e.g., dibenzoyl peroxide, alkyl peroxide, etc.).
In step S120, when an initiator is added to the mixed solution, the ratio of the mass of the initiator to the sum of the mass of the binder monomer, the organic acid monomer, and the conductive material monomer in the mixed solution is 0.1:100 to 3:100, for example, may be 0.1: 100. 1: 100. 1.5: 100. 3:100, etc.
The shielding gas may be helium, argon or other shielding gas. For example, argon may be selected as the shielding gas in this embodiment. The temperature of the heating and stirring is 30 to 120℃and may be, for example, 30℃60℃90℃120 ℃. The heating and stirring time is 10 to 24 hours, and may be, for example, 10 hours, 15 hours, 19 hours, 24 hours, or the like.
And step S130, adding the reaction liquid into a polymer precipitant for precipitation, and filtering, cleaning and drying to obtain the composite adhesive.
After the polymerization reaction in step S120 is sufficient, the reaction solution may be left to stand at room temperature for a certain period of time, for example, may be left to stand for 4 hours, 5 hours, or the like. Then, the reaction solution is added into a polymer precipitant to precipitate, and the precipitated polymer is filtered, washed and dried to obtain the composite binder.
The kind of the polymer precipitant may be selected according to the kind of the first solvent, and in particular, the polymer precipitant miscible with the first solvent may be selected. For example, the first solvent of the present embodiment is DMF, and the polymer precipitant may include methanol, ethanol, and the like.
In step S130, the drying temperature is less than 50 ℃, and the drying time is 8-24 hours.
The preparation method of the composite adhesive can obtain a novel composite adhesive. The composite binder is a high-molecular polymer, and the monomers of the high-molecular polymer comprise binder monomers, organic acid monomers and conductive material monomers.
The composite binder of the embodiment of the invention can be used for preparing the electrode slice by adopting a dry process. In this embodiment, the electrode sheet includes a current collector and a dry electrode layer disposed on the current collector. The dry electrode layer includes an electrode active material, a conductive agent, and a composite binder in at least some embodiments of the invention.
Because the conductive material monomer in the composite adhesive has the function of a conductor, the composite adhesive provided by the embodiment of the invention is used for manufacturing the electrode plate by adopting a dry process, the conductivity of the electrode plate can be effectively improved, the internal resistance of the electrode plate is reduced, and the rate capability of the lithium ion battery can be effectively improved. Meanwhile, carboxylic acid functional groups of the organic acid can generate certain micro corrosion on the current collector, so that uneven micro pits are formed on the surface of the smooth current collector, the binding force between the dry electrode layer and the current collector is enhanced, and the cycle performance of the lithium ion battery can be improved. Therefore, the composite adhesive provided by the embodiment of the invention has good bonding capability and can also have good improvement effect on the rate performance and the cycle performance of the lithium ion battery.
The current collector can be made of a corresponding material according to the polarity of the electrode plate, for example, when the electrode plate is a positive electrode plate, aluminum can be selected as the current collector; when the electrode plate is a negative electrode, the current collector can be copper.
According to the polarity of the electrode plate, the electrode active material is selected from corresponding materials. For example, when the electrode sheet is a positive electrode sheet, the electrode active material may be selected from one or more of lithium iron phosphate, lithium nickel cobalt lithium manganate (e.g., NCM111, NCM523, NCM622, NCM 811), lithium manganate, lithium cobaltate, or other positive electrode active materials; when the electrode sheet is a negative electrode sheet, the electrode active material may be one or more of graphite, a silicon-based material, soft carbon, hard carbon, or other negative electrode active materials.
The conductive agent may include one or more of carbon black, acetylene black, carbon nanotubes, conductive fibers, small particle size graphite, or other conductive agents, as embodiments of the present invention are not limited in this respect.
In this embodiment, the mass percentage of the electrode active material in the dry electrode layer is 90 to 98%, the mass percentage of the conductive agent in the dry electrode layer is 1 to 5%, and the mass percentage of the composite binder in the dry electrode layer is 1 to 5%. For example, the mass ratio of the electrode active material, the conductive agent, and the composite binder in the dry electrode layer may be 90:5: 5. 93:3: 4. 96:2: 2. 98:1:1, etc.
Fig. 2 is a schematic flow chart of a method for manufacturing an electrode sheet according to an embodiment of the present invention. The embodiment of the present invention also provides a preparation method capable of preparing the electrode sheet in at least some embodiments of the present invention, referring to fig. 2, the preparation method may include the following steps S210 to S230:
and step S210, mixing and stirring the electrode active material, the conductive agent and the composite binder to obtain a mixed material.
According to the proportion requirement of the electrode active material, the conductive agent and the composite binder in the dry electrode layer, the electrode active material, the conductive agent and the composite binder are mixed according to a preset proportion, stirred uniformly and finely crushed to obtain a mixed material.
And S220, rolling the mixed material to obtain the electrode film strip.
And carrying out hot rolling on the mixed material to obtain an electrode film strip with a preset thickness, wherein the thickness of the electrode film strip is consistent with the thickness of a dry electrode layer of the electrode sheet. The temperature of the hot rolling may be 100 to 200 ℃, for example, 100 ℃, 150 ℃,200 ℃, and the like.
And step S230, fixing the electrode film strip on the current collector by rolling.
And compounding the electrode film on the current collector in a mode of rolling through a belt to form a dry electrode layer on the electrode plate. The temperature of the hot rolling may be 100 to 200 ℃, for example, 100 ℃, 150 ℃,200 ℃, and the like. The temperature of the hot rolling in step S230 may be lower than the temperature of the hot rolling in step S220. Then, the current collector combined with the electrode film strip is cut into a proper size to obtain an electrode sheet.
The embodiment of the invention also provides a lithium ion battery, which comprises the electrode plate in at least part of the embodiments of the invention. The positive plate and the negative plate of the lithium ion battery can both adopt the electrode plate in the embodiment of the invention, and one of the positive plate and the negative plate can also adopt the electrode plate in the embodiment of the invention. The lithium ion battery also includes an electrolyte, a separator, and the like. The diaphragm is arranged between the positive plate and the negative plate, and electrolyte infiltrates the positive plate, the negative plate and the diaphragm to assemble the lithium ion battery.
The following describes the composite binder, the preparation method thereof, the electrode sheet and the lithium ion battery in detail by combining specific examples.
Example 1
In example 1, 100mg of vinylidene fluoride monomer, 50mg of acrylic acid monomer and 80mg of phenylacetylene monomer (i.e., the mass ratio of vinylidene fluoride monomer, acrylic acid monomer and phenylacetylene monomer is 1.0:0.5:0.8) were dissolved in a round bottom flask containing 20ml of an N, N-dimethylformamide solvent to obtain a mixed solution. Then, 1.15mg of dibenzoyl peroxide initiator (i.e., the ratio of the mass of the initiator to the sum of the mass of vinylidene fluoride monomer, acrylic acid monomer and phenylacetylene monomer is 0.5:100) was added to the mixed solution, and the mixture was heated and stirred at 60℃under the protection of argon atmosphere for reaction for 20 hours. Then, the reaction solution was allowed to stand at room temperature for 4 hours. The reaction solution is precipitated by excessive methanol, filtered and thoroughly washed by distilled water to remove residual solvent, monomer and homopolymer in the precipitate, and the mixture is dried in vacuum at 40 ℃ for 10 hours to obtain the composite binder.
The electrode film strip is formed by uniformly stirring, finely crushing and hot rolling a mixed material consisting of an electrode active material NCM523, a conductive agent SP and a composite binder. Wherein, the mass ratio of the NCM523, the conductive agent SP and the composite binder is 95.5:2.5:2.5. And compounding the electrode film strip onto an aluminum foil current collector in a hot rolling mode to obtain a coiled dry-method positive electrode strip. And cutting the dry-method positive electrode strip into a certain size to obtain the positive plate.
And taking a conventional negative plate and an obtained positive plate, and carrying out Z-shaped lamination through a diaphragm by adopting a lamination process. Wherein the diaphragm uses a diaphragm with a thickness of 14um and double-sided adhesive coating. And packaging by an aluminum plastic film, injecting liquid, pre-charging and forming to prepare the 2Ah dry electrode lithium ion battery. Wherein, liPF of electrolyte 6 The concentration was 1.15mol/L.
Comparative example
In this comparative example, a polymer of vinylidene fluoride monomer was selected as a binder, the same conductive agent and active material as in example 1 were selected, a pole piece was prepared according to the same pole piece preparation process as in example 1, and a 2Ah dry electrode lithium ion battery was prepared using the pole piece.
Fig. 3 is a schematic diagram showing the results of the lithium ion battery magnification test of example 1 and comparative example of the present invention; fig. 4 is a schematic diagram showing the results of the cycle performance test of the lithium ion battery of example 1 and comparative example of the present invention.
The lithium ion battery prepared in example 1 and the lithium ion battery of comparative example were subjected to a rate test and a cycle performance test under the same test conditions, and the test results obtained are shown in fig. 3 and 4. The rate test is carried out by adopting a discharge rate of 3C/1C, and the cycle performance test is carried out at 25 ℃ and a charge-discharge rate of 1C.
In the rate test, the battery was charged with 1C current, and the discharge capacities at 1C current and 3C current were measured, and the ratio of the discharge capacity at 3C current to the discharge capacity at 1C current was calculated and recorded as a 3C/1C capacity retention rate. Referring to fig. 3, it can be seen that the 3C/1C capacity retention rate of the lithium ion battery of example 1 was 90.50%, while the 3C/1C capacity retention rate of the lithium ion battery of comparative example was 86.30%, and thus it can be seen that the rate performance of the lithium ion battery of example 1 using the composite binder was significantly improved as compared with the comparative example.
Referring to fig. 4, it can be seen that the capacity retention rate of the lithium ion battery of example 1 was 97.6% and the capacity retention rate of the lithium ion battery of comparative example was 96.7% after 200 cycles. The capacity retention rate of the lithium ion battery of example 1 was higher than that of the comparative example after the same number of cycles, indicating that the battery cycle performance of the lithium ion battery of example 1 was superior to that of the comparative example.
The monomer formed by polymerization of the composite binder provided by the embodiment of the invention comprises three monomers, namely a binder monomer, an organic acid monomer and a conductive material monomer. The organic acid monomer can enhance the bonding force between the dry electrode layer and the current collector, and improves the cycle performance of the lithium ion battery; the conductive material monomer can enable the composite adhesive to have certain conductivity, is beneficial to reducing the internal resistance of the electrode plate and improving the cycle performance of the lithium ion battery.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, and various modifications and variations may be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (15)
1. A composite binder comprising a polymer formed by polymerizing a binder monomer, an organic acid monomer, and a conductive material monomer.
2. The composite binder of claim 1 wherein the binder monomer is vinylidene fluoride monomer, the organic acid monomer is acrylic acid monomer, and the conductive material monomer is phenylacetylene monomer;
the mass ratio of the vinylidene fluoride monomer to the acrylic acid monomer to the phenylacetylene monomer is 1.0 (0.2-1.0) to 0.2-1.0.
3. The composite binder according to claim 2, wherein the mass ratio of the vinylidene fluoride monomer, the acrylic acid monomer and the phenylacetylene monomer is 1.0 (0.4-0.8): 0.5-1.0.
4. A method of preparing a composite adhesive, the method comprising:
dissolving a binder monomer, an organic acid monomer and a conductive material monomer in a first solvent to form a mixed solution, wherein the first solvent is an organic solvent without active hydrogen;
adding an initiator into the mixed solution, and heating and stirring under a protective gas atmosphere to obtain a reaction solution; and
and adding the reaction liquid into a polymer precipitant for precipitation, and filtering, cleaning and drying to obtain the composite binder.
5. The method for preparing a composite adhesive according to claim 4, wherein the adhesive monomer is vinylidene fluoride monomer, the organic acid monomer is acrylic acid monomer, and the conductive material monomer is phenylacetylene monomer;
the mass ratio of the vinylidene fluoride monomer to the acrylic acid monomer to the phenylacetylene monomer is 1.0 (0.2-1.0) to 0.2-1.0.
6. The method of preparing a composite binder according to claim 4, wherein the ratio of the mass of the initiator to the sum of the mass of the binder monomer, the organic acid monomer and the conductive material monomer is 0.1:100 to 3:100.
7. The method of producing a composite adhesive according to claim 4, wherein the temperature of the heating and stirring under the protective gas atmosphere is 30 to 120 ℃ for 10 to 24 hours.
8. The method of preparing a composite binder according to claim 4, wherein the reaction solution is allowed to stand at room temperature before the reaction solution is added to the polymer precipitant for precipitation.
9. The method of preparing a composite binder according to claim 4, wherein the drying temperature is less than 50 ℃ for 8 to 24 hours.
10. The method of preparing a composite binder according to claim 4, wherein the binder monomer comprises at least one of vinylidene fluoride, trifluoroethylene, or tetrafluoroethylene;
the conductive material monomer comprises at least one of phenylacetylene, aniline, thiophene or pyrrole;
the organic acid monomer comprises at least one of acrylic acid, acrylic acid ester or phenylacetic acid.
11. The method of preparing a composite adhesive according to claim 4, wherein the initiator comprises at least one of azobisisobutyronitrile, dibenzoyl peroxide, or alkyl peroxide.
12. The method of preparing a composite binder according to claim 4, wherein the first solvent is N, N-dimethylformamide or N-methylpyrrolidone, and the polymer precipitant comprises methanol or ethanol.
13. An electrode sheet, characterized by comprising:
a current collector; and
a dry electrode layer disposed on the current collector, the dry electrode layer including an electrode active material, a conductive agent, and a composite binder;
wherein the composite binder comprises the composite binder of any one of claims 1-3, or the composite binder comprises the composite binder obtained according to the method of any one of claims 4-12.
14. The electrode sheet according to claim 13, wherein the mass percentage of the electrode active material in the dry electrode layer is 90-98%;
the mass percentage of the conductive agent in the dry electrode layer is 1-5%;
the mass percentage of the composite binder in the dry electrode layer is 1-5%.
15. A lithium ion battery comprising an electrode sheet according to any one of claims 13-14.
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