CN117089017A - Non-fluorine binder for positive electrode of lithium ion battery, positive electrode using same and battery - Google Patents
Non-fluorine binder for positive electrode of lithium ion battery, positive electrode using same and battery Download PDFInfo
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- CN117089017A CN117089017A CN202311104026.6A CN202311104026A CN117089017A CN 117089017 A CN117089017 A CN 117089017A CN 202311104026 A CN202311104026 A CN 202311104026A CN 117089017 A CN117089017 A CN 117089017A
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- positive electrode
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- acrylamide
- acrylic acid
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- 239000011230 binding agent Substances 0.000 title claims abstract description 39
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 title claims abstract description 38
- 229910001416 lithium ion Inorganic materials 0.000 title claims abstract description 38
- 229910052731 fluorine Inorganic materials 0.000 title claims abstract description 17
- 239000011737 fluorine Substances 0.000 title claims abstract description 17
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 claims abstract description 29
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 claims abstract description 29
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 claims abstract description 26
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims abstract description 26
- 230000001070 adhesive effect Effects 0.000 claims abstract description 26
- 239000000853 adhesive Substances 0.000 claims abstract description 23
- -1 alkyl glycidyl ether Chemical compound 0.000 claims abstract description 23
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 claims abstract description 15
- 229920001577 copolymer Polymers 0.000 claims abstract description 10
- 239000000178 monomer Substances 0.000 claims abstract description 10
- 239000002994 raw material Substances 0.000 claims abstract description 8
- 238000007334 copolymerization reaction Methods 0.000 claims abstract description 7
- 238000000034 method Methods 0.000 claims description 18
- 239000000376 reactant Substances 0.000 claims description 18
- 238000006243 chemical reaction Methods 0.000 claims description 15
- 239000003999 initiator Substances 0.000 claims description 11
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 10
- 239000012986 chain transfer agent Substances 0.000 claims description 4
- 239000011248 coating agent Substances 0.000 claims description 4
- 238000000576 coating method Methods 0.000 claims description 4
- 239000003995 emulsifying agent Substances 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 4
- 125000000217 alkyl group Chemical group 0.000 claims description 3
- 239000012298 atmosphere Substances 0.000 claims description 2
- 238000002156 mixing Methods 0.000 claims description 2
- 239000002245 particle Substances 0.000 claims description 2
- 230000001681 protective effect Effects 0.000 claims description 2
- 239000002904 solvent Substances 0.000 claims description 2
- 239000011883 electrode binding agent Substances 0.000 abstract description 25
- 239000002033 PVDF binder Substances 0.000 abstract description 12
- 238000006116 polymerization reaction Methods 0.000 abstract 1
- 238000012360 testing method Methods 0.000 description 23
- 230000000052 comparative effect Effects 0.000 description 20
- 239000011267 electrode slurry Substances 0.000 description 17
- 239000002002 slurry Substances 0.000 description 11
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 9
- 238000009472 formulation Methods 0.000 description 8
- 239000000203 mixture Substances 0.000 description 8
- 238000002360 preparation method Methods 0.000 description 7
- 239000000243 solution Substances 0.000 description 6
- VMSIYTPWZLSMOH-UHFFFAOYSA-N 2-(dodecoxymethyl)oxirane Chemical compound CCCCCCCCCCCCOCC1CO1 VMSIYTPWZLSMOH-UHFFFAOYSA-N 0.000 description 5
- 239000003792 electrolyte Substances 0.000 description 5
- 230000002522 swelling effect Effects 0.000 description 5
- 238000010998 test method Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 4
- 239000004642 Polyimide Substances 0.000 description 3
- 239000006257 cathode slurry Substances 0.000 description 3
- 239000006258 conductive agent Substances 0.000 description 3
- 239000006185 dispersion Substances 0.000 description 3
- 229920001721 polyimide Polymers 0.000 description 3
- 238000002791 soaking Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 2
- 239000006230 acetylene black Substances 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium persulfate Chemical compound [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 description 2
- 239000003013 cathode binding agent Substances 0.000 description 2
- 239000011247 coating layer Substances 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- GYZLOYUZLJXAJU-UHFFFAOYSA-N diglycidyl ether Chemical compound C1OC1COCC1CO1 GYZLOYUZLJXAJU-UHFFFAOYSA-N 0.000 description 2
- IEJIGPNLZYLLBP-UHFFFAOYSA-N dimethyl carbonate Chemical compound COC(=O)OC IEJIGPNLZYLLBP-UHFFFAOYSA-N 0.000 description 2
- 239000011888 foil Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000007773 negative electrode material Substances 0.000 description 2
- 230000008961 swelling Effects 0.000 description 2
- YSUQLAYJZDEMOT-UHFFFAOYSA-N 2-(butoxymethyl)oxirane Chemical compound CCCCOCC1CO1 YSUQLAYJZDEMOT-UHFFFAOYSA-N 0.000 description 1
- YZUMRMCHAJVDRT-UHFFFAOYSA-N 2-(hexadecoxymethyl)oxirane Chemical compound CCCCCCCCCCCCCCCCOCC1CO1 YZUMRMCHAJVDRT-UHFFFAOYSA-N 0.000 description 1
- ZXJBWUAALADCRI-UHFFFAOYSA-N 2-(octadecoxymethyl)oxirane Chemical compound CCCCCCCCCCCCCCCCCCOCC1CO1 ZXJBWUAALADCRI-UHFFFAOYSA-N 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-M Acrylate Chemical compound [O-]C(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-M 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical compound O=C1OCCO1 KMTRUDSVKNLOMY-UHFFFAOYSA-N 0.000 description 1
- 229910013872 LiPF Inorganic materials 0.000 description 1
- 101150058243 Lipf gene Proteins 0.000 description 1
- QSNQXZYQEIKDPU-UHFFFAOYSA-N [Li].[Fe] Chemical compound [Li].[Fe] QSNQXZYQEIKDPU-UHFFFAOYSA-N 0.000 description 1
- UGAPHEBNTGUMBB-UHFFFAOYSA-N acetic acid;ethyl acetate Chemical compound CC(O)=O.CCOC(C)=O UGAPHEBNTGUMBB-UHFFFAOYSA-N 0.000 description 1
- 125000005396 acrylic acid ester group Chemical group 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 239000002390 adhesive tape Substances 0.000 description 1
- 229910001870 ammonium persulfate Inorganic materials 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000009831 deintercalation Methods 0.000 description 1
- 239000002612 dispersion medium Substances 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000000839 emulsion Substances 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 238000001746 injection moulding Methods 0.000 description 1
- 230000002687 intercalation Effects 0.000 description 1
- 238000009830 intercalation Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 239000010702 perfluoropolyether Substances 0.000 description 1
- JRKICGRDRMAZLK-UHFFFAOYSA-L persulfate group Chemical group S(=O)(=O)([O-])OOS(=O)(=O)[O-] JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 description 1
- 229920002239 polyacrylonitrile Polymers 0.000 description 1
- 239000007774 positive electrode material Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000000750 progressive effect Effects 0.000 description 1
- GUYXXEXGKVKXAW-UHFFFAOYSA-N prop-2-enenitrile Chemical compound C=CC#N.C=CC#N GUYXXEXGKVKXAW-UHFFFAOYSA-N 0.000 description 1
- BWJUFXUULUEGMA-UHFFFAOYSA-N propan-2-yl propan-2-yloxycarbonyloxy carbonate Chemical compound CC(C)OC(=O)OOC(=O)OC(C)C BWJUFXUULUEGMA-UHFFFAOYSA-N 0.000 description 1
- 238000006479 redox reaction Methods 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- DAJSVUQLFFJUSX-UHFFFAOYSA-M sodium;dodecane-1-sulfonate Chemical compound [Na+].CCCCCCCCCCCCS([O-])(=O)=O DAJSVUQLFFJUSX-UHFFFAOYSA-M 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 230000008719 thickening Effects 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances 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
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
- C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
- C08F220/42—Nitriles
- C08F220/44—Acrylonitrile
- C08F220/48—Acrylonitrile with nitrogen-containing monomers
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F8/00—Chemical modification by after-treatment
- C08F8/14—Esterification
-
- 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
-
- 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)
- General Chemical & Material Sciences (AREA)
- Electrochemistry (AREA)
- Engineering & Computer Science (AREA)
- Health & Medical Sciences (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention provides a non-fluorine binder for a positive electrode of a lithium ion battery, a positive electrode and a battery using the non-fluorine binder, wherein raw materials for preparing the binder comprise acrylamide, acrylic acid, acrylonitrile and alkyl glycidyl ether; after the copolymerization of acrylamide, acrylic acid and acrylonitrile, alkyl glycidyl ether is grafted to obtain the adhesive. The polymerization monomer (acrylamide, acrylic acid and acrylonitrile) used in the invention has higher hard brittleness, but the alkyl glycidyl ether is introduced, so that the flexibility and dispersibility of the copolymer can be improved, the positive electrode binder obtained in the invention is ensured to have good mechanical property and binding property, and the positive electrode non-fluorine binder which can be comparable to the performance of the existing PVDF binder is realized, so that the invention is suitable for the future market demand.
Description
Technical Field
The invention belongs to the field of lithium ion batteries, and particularly relates to a non-fluorine binder for a positive electrode of a lithium ion battery, and a positive electrode and a battery applying the non-fluorine binder.
Background
The lithium ion battery has high energy density and long cycle life, and has wide application in the fields of portable electronic equipment, electric automobiles, energy storage and the like. The lithium ion battery mainly comprises a positive electrode, a negative electrode, a diaphragm, electrolyte and a shell, and the working principle of the lithium ion battery is that electric energy is stored and released through oxidation-reduction reaction of reversible intercalation/deintercalation of lithium ions in an active material. The preparation method of the positive electrode and the negative electrode of the lithium ion battery comprises the steps of preparing positive electrode active materials or negative electrode active materials, electrode binders, conductive agents, dispersion media and the like into slurry, coating the slurry on corresponding current collectors, and carrying out processing technologies such as drying, cold pressing, die cutting and the like.
In the prior art, polyvinylidene fluoride (PVDF) still takes the dominant role in the positive electrode binder, so that the binder which is applicable to emulsion homopolymerization of an iron-lithium battery system and suspension copolymerization modified PVDF in a ternary battery system is formed, and the state cannot be shocked in a short period. However, with the progressive disablement of fluorine materials in europe, non-fluorine positive electrode binders must go on the history stage and their performance must be close to, and even reach, the overrun state with existing PVDF binders.
The development of the positive electrode non-fluorine binder is not optimistic, the main development direction is a polyacrylonitrile modification route, acrylonitrile is taken as a main body, and the multipolymer is obtained through copolymerization modification of acrylamide and acrylic acid ester. The copolymer of the route has great defects that the material is hard and brittle, has poor dispersion performance, cannot be used purely, and can reach the performance of the existing PVDF adhesive only by being mixed with PVDF. The acrylate route is similar to the acrylonitrile route, the functions of adhesion, dispersion and the like of the prepared binder can not meet the requirement of a positive electrode, and the prepared binder is large in swelling and has great influence on the electrical property. The technical route in the polyimide direction is difficult to realize functions such as thickening, and the like, and because the polyimide has higher melting point and decomposition temperature, some molding processes such as injection molding, extrusion and the like have technical difficulties, and the processability of the polyimide is influenced.
Thus, there is a need to provide a positive non-fluorine binder that can compete with the performance of existing PVDF binders to accommodate future market demands.
Disclosure of Invention
In order to improve the mechanical property and the adhesive property of the positive electrode non-fluorine adhesive, the invention provides a positive electrode non-fluorine adhesive of a lithium ion battery, and a positive electrode and a battery applying the same.
According to one aspect of the invention, there is provided a non-fluorine binder for a positive electrode of a lithium ion battery, wherein raw materials for preparing the binder comprise acrylamide, acrylic acid, acrylonitrile and alkyl glycidyl ether; after the copolymerization of acrylamide, acrylic acid and acrylonitrile, alkyl glycidyl ether is grafted to obtain the adhesive.
The prepolymer (acrylamide, acrylic acid and acrylonitrile) used in the invention has higher hard brittleness, but the flexibility and dispersibility of the prepolymer can be improved due to the introduction of the alkyl glycidyl ether. In addition, the acrylonitrile and the acrylamide can provide basic structural strength for the adhesive, so that the adhesive force of the positive electrode adhesive is ensured; acrylic acid, acrylamide, can then provide sites for grafting (-COOH and-NH) 2 ) So that the glycidyl ether can be smoothly grafted on the copolymer. Therefore, the positive electrode binder obtained by the invention has good mechanical property and binding property, and the prepared positive electrode non-fluorine binder can achieve the performance comparable to the existing polyvinylidene fluoride (PVDF) binder, and can adapt to the future market demand.
Preferably, the alkyl glycidyl ether has a long carbon chain alkyl group having 8 to 20 carbon chains in its molecular structure. After the long carbon chain alkyl is grafted, the flexibility of the copolymer can be improved, and meanwhile, the dispersion performance of the adhesive can be improved.
Preferably, the acrylamide is calculated according to the mass ratio: acrylic acid: acrylonitrile=0.5 to 1.5:1.5 to 2.5:6.5 to 7.5.
Preferably, the raw materials for preparing the adhesive comprise, by mass, 15-25 parts of acrylamide, 30-50 parts of acrylic acid, 120-150 parts of acrylonitrile and 5-15 parts of alkyl glycidyl ether.
Preferably, the weight average molecular weight of the binder is 90 to 110 tens of thousands and the particle size is 10 to 50 μm.
Preferably, the method of preparing the binder comprises the steps of: s1, under a protective atmosphere, mixing a solvent, an emulsifying agent, a chain transfer agent, an initiator and a first reactant, thereby constructing a reaction system, and then heating to 50-90 ℃, wherein the first reactant comprises 5-10 parts of acrylamide, 10-20 parts of acrylic acid and 50-70 parts of acrylonitrile according to parts by weight; s2, continuously adding a second reactant and an initiator into the reaction system, wherein the second reactant comprises 10-15 parts of acrylamide, 20-30 parts of acrylic acid and 70-80 parts of acrylonitrile according to parts by weight, and carrying out copolymerization reaction for 3-5 hours to obtain an acrylamide-acrylic acid-acrylonitrile copolymer; s3, adding alkyl glycidyl ether into the reaction system, and performing grafting reaction for 2-4 hours at the temperature of 50-90 ℃ to obtain the adhesive.
Preferably, the emulsifier comprises at least one of sodium dodecyl sulfonate, perfluoropolyether.
Preferably, the chain transfer agent comprises at least one of acetic acid ethyl acetate, isopropanol.
Preferably, the initiator comprises at least one of persulfates, diisopropyl peroxydicarbonate (IPP).
Preferably, the acrylamide-acrylic acid-acrylonitrile copolymer obtained after completion of S2 has a weight average molecular weight of not more than 90 ten thousand.
Preferably, in S4, the second reactant and the initiator are added to the reaction system by dropwise addition.
Preferably, in S4, the second reactant has a dropping rate of 0.3 to 0.6 parts/min.
Preferably, in S4, the initiator has a dropping rate of 0.01 to 0.05 parts/min.
According to a second aspect of the present invention, there is provided a lithium ion battery positive electrode comprising a current collector and a positive electrode active coating layer disposed on the surface of the current collector, the positive electrode active coating layer comprising a binder as described above.
According to a third aspect of the present invention there is provided a lithium ion battery comprising a lithium ion battery positive electrode as described above.
Detailed Description
In order to make the technical solution of the present invention better understood by those skilled in the art, the technical solution of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
Example 1
1. Raw materials for preparing positive electrode binder
The raw materials for preparing the positive electrode binder are shown in table 1.
TABLE 1 raw materials for preparing the Positive Binder in this example
2. Step of preparing Positive Binder
S1, adding water into a reactor, performing vacuumizing operation and nitrogen introducing operation, then adding an emulsifier, a first reactant and a chain transfer agent, heating to 70 ℃ under a nitrogen atmosphere, then adding 6 parts of ammonium persulfate initiator with the concentration of 15wt% and controlling the temperature to be 70+/-2 ℃, wherein the first reactant comprises 10 parts of acrylamide, 20 parts of acrylic acid and 70 parts of acrylonitrile according to parts by weight, and heating to 50-90 ℃;
s2, continuously adding a second reactant and an initiator into the reaction system, wherein the second reactant comprises 10-15 parts of acrylamide, 20-30 parts of acrylic acid and 70-80 parts of acrylonitrile according to parts by weight, the dripping speed of the second reactant is 0.48 part/min, the dripping speed of the initiator is 0.024 part/min, and the reaction is carried out for 3.5 hours to obtain an acrylamide-acrylic acid-acrylonitrile copolymer;
s3, adding alkyl glycidyl ether into the reaction system, and performing grafting reaction for 24 hours at the temperature of 70+/-2 ℃ to obtain the adhesive.
Treatment groups 2A to 5A of example 1 were prepared with reference to the formulation and method provided for treatment group 1A to prepare a positive electrode binder, a positive electrode slurry, a positive electrode, and a lithium ion battery, differing from treatment group 1A of example 1 in that treatment groups 2A to 5A of example 1 were subjected to the types of alkyl glycidyl ethers used in preparing positive electrode binders or the parts by mass added as variables, which are shown in table 2. Except for the above differences, the procedure for preparing the positive electrode binder, positive electrode slurry, positive electrode and lithium ion battery of treatment groups 2A to 5A of example 1 was strictly consistent with treatment group 1A.
TABLE 2 variable for each treatment group of EXAMPLE 1
| Group of | Types of alkyl glycidyl ethers | Alkyl glycidyl ether in parts by weight |
| Treatment group 1A | Dodecyl glycidyl ether (C) 15 H 30 O 2 ) | 10 |
| Treatment group 2A | Dodecyl glycidyl ether (C) 15 H 30 O 2 ) | 5 |
| Treatment group 3A | Dodecyl glycidyl ether (C) 15 H 30 O 2 ) | 15 |
| Treatment group 4A | Dodecyl glycidyl ether (C) 15 H 30 O 2 ) | 20 |
| Treatment group 5A | Cetyl glycidyl ether (C) 19 H 38 O 2 ) | 10 |
| Treatment group 6A | Octadecyl glycidyl ether (C) 21 H 42 O 2 ) | 10 |
| Treatment group 7A | Butyl glycidyl ether (C) 7 H 14 O 2 ) | 10 |
3. Application of positive electrode binder
Cathode material 0.25Li 2 MnO 3 ·0.75LiMn 0.375 Ni 0.375 Co 0.25 O 2 The conductive agent acetylene black and the positive electrode binder are prepared into slurry according to the mass ratio of 95:3.5:1.5, the slurry is coated on an aluminum foil current collector, and then the aluminum foil current collector is dried in vacuum to prepare the positive electrode plate.
Preparing slurry from a negative electrode material graphite, a conductive agent acetylene black, a binder CMC and SBR according to a mass ratio of 94:1:2:3, coating the slurry on a copper foil current collector, and then carrying out vacuum drying to obtain a negative electrode plate;
the positive electrode sheet, the negative electrode sheet, the Celgard2400 separator and the electrolyte prepared above were then assembled into a soft-pack battery. Wherein the electrolyte used is a solution in which 1mol/L LiPF is dissolved 6 The volume ratio of the ethylene carbonate to the dimethyl carbonate is calculated as: dimethyl carbonate=1:1.
Comparative example 1
This comparative example the formulation and method provided by the treatment group 1A of example 1 were used to prepare a cathode slurry, a cathode and a lithium ion battery, with the difference that the treatment group 1A of example 1 was used to prepare a cathode slurry in which PVDF was replaced with an equal mass fraction of the cathode binder, and the operation steps of the preparation of the cathode binder, the cathode slurry, the cathode and the lithium ion battery were strictly consistent with the treatment group 1A of example 1, except for the above differences.
Comparative example 2
This comparative example was prepared by referring to the formulation and method provided for treatment group 1A of example 1 to prepare a positive electrode binder, positive electrode slurry, positive electrode and lithium ion battery, differing from treatment group 1A of example 1 in that no dodecyl glycidyl ether was added in the preparation of the binder. Except for the above-mentioned differences, the procedure for preparing the positive electrode binder, positive electrode slurry, positive electrode and lithium ion battery of this comparative example was strictly consistent with the treatment group 1A of example 1.
Test example 1
1. Test object
Example 1 each treatment group and the positive electrode slurry, positive electrode and battery prepared in comparative example 1.
2. Test method
(1) Swelling properties: soaking the prepared pole piece in electrolyte at 50deg.C for 8 days, taking out the pole piece at 24 hr intervals, sucking the electrolyte on the surface of the pole piece, testing the thickness and weight of the pole piece, and calculating swelling ratio according to formula (1), wherein w is the mass of the pole piece before soaking, and w is the total weight of the pole piece before soaking i Is the mass at time i;
(2) Viscosity of the positive electrode slurry: testing was performed using a german HAAKE MARS rheometer;
(3) And (3) testing the stripping force of the positive electrode slurry to the positive electrode: according to GB 2792 2014 test method for adhesive tape peel strength, 180 DEG peel test method is adopted to test the peel force of slurry to the positive electrode;
(4) Flexibility test of positive electrode: a cylindrical shaft bending experiment instrument is used, and the specific method is that a pole piece is cut into rectangular sample strips with the width of 5cm, then the rectangular sample strips are wound on a metal cylinder with the diameter of 2mm, the metal cylinder is pulled at a constant speed of 180 degrees, and whether the pole piece has breakage and cracks is observed. The flexibility of the pole piece is good, general and good from poor to good.
(5) Testing the normal temperature cycle performance of the battery: at 25 ℃, the lithium ion battery is charged to a voltage of 4.2V at a constant current of 0.5C (nominal capacity), then is charged to a current of less than or equal to 0.05C at a constant voltage of 4.2V, and is discharged to a voltage of 2.5V at a constant current of 1C after being placed for 10min, and the above is one charge-discharge cycle. The lithium ion battery is subjected to 500 charge-discharge cycles at 25 ℃ according to the conditions. Wherein the capacity retention is calculated according to equation (2).
3. Test results and analysis
The test results of test example 1 are shown in table 3, and the present test example mainly explores the influence of the kind of alkyl glycidyl ether or the added parts by mass on the prepared binder and the slurry, positive electrode and battery using the same. Compared with comparative example 1, it was found that the positive electrode binder provided by the present invention was comparable to PVDF. In the treatment groups 1A to 4A of example 1, it was found that as the mass fraction of the alkyl glycidyl ether increases, the flexibility of the produced positive electrode shows a tendency to be increased and then decreased, indicating that the mass fraction of the alkyl glycidyl ether affects the brittleness of the binder. In treatment group 1A and treatment groups 5A to 7A, however, it was found that as the number of carbon chains in the long carbon chain alkyl glycidyl ether increases, the flexibility of the prepared positive electrode showed a tendency of a change in which the number of carbon chains in the alkyl glycidyl ether used was increased and then decreased, thereby indicating that the flexibility of the binder was affected. In comparative example 2, however, the resulting positive electrode was brittle and the flexibility was drastically lowered because no alkyl glycidyl ether was added.
TABLE 3 test results for test example 1
Example 2
Treatment group 1B
Treatment group 1B positive electrode binders, positive electrode slurries, positive electrodes, and lithium ion batteries were prepared according to the formulation and method provided in treatment group 1A.
Treatment groups 2B to 4B of example 2 positive electrode binder, positive electrode slurry, positive electrode and lithium ion battery were prepared with reference to the formulation and method provided for treatment group 1B of example 2, treatment groups 2B to 4B of example 2 were distinguished from treatment group 1B of example 2 in that treatment groups 2B to 4B of example 2 were subjected to the preparation of the pre-polymerized monomers used in the positive electrode binder, namely, acrylamide, acrylic acid, acrylonitrile, in the mass ratio as variables shown in table 4. Wherein the mass percent of each material added in the second reactant is consistent with the mass percent of each material added in the second reactant. Except for the above differences, the procedure for preparing the positive electrode binder, positive electrode slurry, positive electrode, and lithium ion battery in the treatment groups 2B to 4B of example 2 was strictly consistent with the treatment group 1B of example 2.
TABLE 4 variation of the mass ratio between non-fluorine-based monomers for each treatment group of EXAMPLE 2
| Group of | Acrylamide: acrylic acid: acrylonitrile (Acrylonitrile) |
| Treatment group 1B | 1：2：7 |
| Treatment group 2B | 0.5：1.5：6.5 |
| Treatment group 3B | 1.5：2.5：7.5 |
| Treatment group 4B | 2：3：5 |
Comparative example 3
This comparative example was prepared with reference to the formulation and method provided for treatment group 1B of example 1 to prepare a positive electrode binder, positive electrode slurry, positive electrode and lithium ion battery, in contrast to treatment group 1B of example 1 in that no acrylamide was added during the preparation of the binder, wherein acrylic acid, acrylonitrile were added according to 2: and 7 parts by mass of acrylamide is replaced by equal parts by mass. Except for the above-mentioned differences, the procedure for preparing the positive electrode binder, positive electrode slurry, positive electrode and lithium ion battery of this comparative example was strictly consistent with the treatment group 1B of example 1.
Comparative example 4
This comparative example was prepared by referring to the formulation and method provided in treatment group 1B of example 1 to prepare a positive electrode binder, positive electrode slurry, positive electrode and lithium ion battery, differing from treatment group 1B of example 1 in that no acrylic acid was added in the preparation of the binder, wherein acrylamide and acrylonitrile were substituted for acrylonitrile in the mass ratio of 1:7, etc. Except for the above-mentioned differences, the procedure for preparing the positive electrode binder, positive electrode slurry, positive electrode and lithium ion battery of this comparative example was strictly consistent with the treatment group 1B of example 1.
Comparative example 5
This comparative example was prepared by referring to the formulation and method provided in treatment group 1B of example 1 to prepare a positive electrode binder, positive electrode slurry, positive electrode and lithium ion battery, differing from treatment group 1B of example 1 in that acrylonitrile was not added in the preparation of the binder, wherein acrylamide, acrylic acid and the like were substituted for acrylonitrile in a mass ratio of 1:2. Except for the above-mentioned differences, the procedure for preparing the positive electrode binder, positive electrode slurry, positive electrode and lithium ion battery of this comparative example was strictly consistent with the treatment group 1B of example 1.
Test example 2
1. Test object
The positive electrode slurry, positive electrode, and battery obtained in each treatment group of example 2 and comparative examples 3 to 5.
2. Test method
Reference is made to the test method performed in test example 1.
3. Test results and analysis
The test results of test example 2 are shown in table 5, and the present test example mainly explores the influence of the ratio of the pre-polymerized monomer and the kind added to the prepared binder and the slurry, positive electrode and battery using the same. In the treatment groups 1B to 4B of example 2, it was found that the adhesive, slurry, positive electrode, viscosity, flexibility and swelling properties of the prepared adhesive, slurry, positive electrode were varied to different extents as the mass ratio of the parts by mass of acrylamide, acrylic acid and acrylonitrile was varied. This is because, although acrylamide, acrylic acid and acrylonitrile have relatively high hard brittleness, they can provide good adhesive properties and swelling properties at a proper ratio. In particular, the acrylamide-acrylic acid-acrylonitrile copolymer can improve the dispersibility, flexibility and swelling property after being grafted with alkyl glycidyl ether. In comparative examples 3 and 5, however, the adhesive strength and flexibility of the prepared adhesive were remarkably lowered since acrylamide or acrylonitrile was not added; in comparative example 4, since acrylic acid was not added, the flexibility, adhesive property, and swelling property of the prepared positive electrode were remarkably lowered.
TABLE 5 test results for test example 2
The above embodiments are only for illustrating the technical solution of the present invention and not for limiting the scope of the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention may be modified or substituted without departing from the spirit and scope of the technical solution of the present invention.
Claims (10)
1. The non-fluorine binder for the positive electrode of the lithium ion battery is characterized in that raw materials for preparing the binder comprise a pre-polymerized monomer and a grafting monomer, and the pre-polymerized monomer is subjected to a grafting reaction with the grafting monomer after a copolymerization reaction to obtain the binder; wherein the pre-polymerized monomer comprises at least two of acrylamide, acrylic acid and acrylonitrile, and the grafting monomer comprises alkyl glycidyl ether.
2. The adhesive according to claim 1, wherein the alkyl glycidyl ether has a molecular structure comprising a long carbon chain alkyl group having 8 to 20 carbon chains.
3. The adhesive of claim 1, wherein the acrylamide, calculated as a mass ratio: the acrylic acid: acrylonitrile=0.5 to 1.5:1.5 to 2.5:6.5 to 7.5.
4. The adhesive according to claim 3, wherein the raw materials for preparing the adhesive comprise, by mass, 15-25 parts of the acrylamide, 30-50 parts of the acrylic acid, 120-150 parts of the acrylonitrile and 5-15 parts of the alkyl glycidyl ether.
5. The binder of claim 1 wherein said binder has a weight average molecular weight of 90 to 110 tens of thousands and a particle size of 10 to 50 μm.
6. The adhesive according to claims 1 to 5, wherein the method for preparing the adhesive comprises the steps of:
s1, under a protective atmosphere, mixing a solvent, an emulsifying agent, a chain transfer agent, an initiator and a first reactant, thereby constructing a reaction system, and then heating to 50-90 ℃, wherein the first reactant comprises 5-10 parts of acrylamide, 10-20 parts of acrylic acid and 50-70 parts of acrylonitrile according to parts by weight;
s2, continuously adding a second reactant and an initiator into the reaction system, wherein the second reactant comprises 10-15 parts of acrylamide, 20-30 parts of acrylic acid and 70-80 parts of acrylonitrile according to parts by weight, and carrying out copolymerization reaction for 3-5 hours to obtain an acrylamide-acrylic acid-acrylonitrile copolymer;
s3, adding the alkyl glycidyl ether into the reaction system, and performing grafting reaction for 2-4 hours at the temperature of 50-90 ℃ to obtain the binder.
7. The adhesive of claim 6 wherein said acrylamide-acrylic acid-acrylonitrile copolymer obtained after completion of said S2 has a weight average molecular weight of not more than 90 ten thousand.
8. The binder according to claim 7, wherein the second reactant and the initiator are added dropwise to the reaction system in S2.
9. The positive electrode of the lithium ion battery is characterized in that: the positive electrode of the lithium ion battery comprises a current collector and a positive electrode active coating arranged on the surface of the current collector, wherein the positive electrode active coating comprises the binder as claimed in any one of claims 1 to 8.
10. A lithium ion battery, characterized in that: the lithium ion battery comprises the lithium ion battery positive electrode as claimed in claim 9.
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|---|---|---|---|
| CN202311104026.6A CN117089017A (en) | 2023-08-30 | 2023-08-30 | Non-fluorine binder for positive electrode of lithium ion battery, positive electrode using same and battery |
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| CN202311104026.6A CN117089017A (en) | 2023-08-30 | 2023-08-30 | Non-fluorine binder for positive electrode of lithium ion battery, positive electrode using same and battery |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116217794A (en) * | 2023-01-09 | 2023-06-06 | 万华化学集团电池科技有限公司 | Solution type binder and preparation method and application thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116217794A (en) * | 2023-01-09 | 2023-06-06 | 万华化学集团电池科技有限公司 | Solution type binder and preparation method and application thereof |
| CN116217794B (en) * | 2023-01-09 | 2024-04-09 | 万华化学集团电池科技有限公司 | Solution type binder and preparation method and application thereof |
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