CN116960332A - Positive plate and battery comprising same - Google Patents
Positive plate and battery comprising same Download PDFInfo
- Publication number
- CN116960332A CN116960332A CN202210412730.7A CN202210412730A CN116960332A CN 116960332 A CN116960332 A CN 116960332A CN 202210412730 A CN202210412730 A CN 202210412730A CN 116960332 A CN116960332 A CN 116960332A
- Authority
- CN
- China
- Prior art keywords
- positive electrode
- active material
- electrode active
- binder
- material layer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000011230 binding agent Substances 0.000 claims abstract description 45
- 239000000178 monomer Substances 0.000 claims abstract description 35
- 238000007334 copolymerization reaction Methods 0.000 claims abstract description 27
- 239000007774 positive electrode material Substances 0.000 claims description 61
- 239000006258 conductive agent Substances 0.000 claims description 14
- HCDGVLDPFQMKDK-UHFFFAOYSA-N hexafluoropropylene Chemical group FC(F)=C(F)C(F)(F)F HCDGVLDPFQMKDK-UHFFFAOYSA-N 0.000 claims description 14
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 6
- 229920001577 copolymer Polymers 0.000 claims description 5
- BQCIDUSAKPWEOX-UHFFFAOYSA-N 1,1-Difluoroethene Chemical group FC(F)=C BQCIDUSAKPWEOX-UHFFFAOYSA-N 0.000 claims description 2
- NLHHRLWOUZZQLW-UHFFFAOYSA-N Acrylonitrile Chemical compound C=CC#N NLHHRLWOUZZQLW-UHFFFAOYSA-N 0.000 claims description 2
- IAYPIBMASNFSPL-UHFFFAOYSA-N Ethylene oxide Chemical compound C1CO1 IAYPIBMASNFSPL-UHFFFAOYSA-N 0.000 claims description 2
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 claims description 2
- VVQNEPGJFQJSBK-UHFFFAOYSA-N Methyl methacrylate Chemical compound COC(=O)C(C)=C VVQNEPGJFQJSBK-UHFFFAOYSA-N 0.000 claims description 2
- BZHJMEDXRYGGRV-UHFFFAOYSA-N Vinyl chloride Chemical compound ClC=C BZHJMEDXRYGGRV-UHFFFAOYSA-N 0.000 claims description 2
- SUPCQIBBMFXVTL-UHFFFAOYSA-N ethyl 2-methylprop-2-enoate Chemical compound CCOC(=O)C(C)=C SUPCQIBBMFXVTL-UHFFFAOYSA-N 0.000 claims description 2
- 125000005397 methacrylic acid ester group Chemical group 0.000 claims description 2
- BOQSSGDQNWEFSX-UHFFFAOYSA-N propan-2-yl 2-methylprop-2-enoate Chemical compound CC(C)OC(=O)C(C)=C BOQSSGDQNWEFSX-UHFFFAOYSA-N 0.000 claims description 2
- NHARPDSAXCBDDR-UHFFFAOYSA-N propyl 2-methylprop-2-enoate Chemical compound CCCOC(=O)C(C)=C NHARPDSAXCBDDR-UHFFFAOYSA-N 0.000 claims description 2
- CERQOIWHTDAKMF-UHFFFAOYSA-M Methacrylate Chemical compound CC(=C)C([O-])=O CERQOIWHTDAKMF-UHFFFAOYSA-M 0.000 claims 1
- 239000003792 electrolyte Substances 0.000 abstract description 6
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 5
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 5
- 238000009792 diffusion process Methods 0.000 abstract description 2
- 150000002500 ions Chemical class 0.000 abstract description 2
- 239000011148 porous material Substances 0.000 abstract description 2
- 238000011160 research Methods 0.000 abstract description 2
- 230000008961 swelling Effects 0.000 abstract description 2
- 239000002002 slurry Substances 0.000 description 14
- 238000007600 charging Methods 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 7
- 230000001070 adhesive effect Effects 0.000 description 7
- 239000011248 coating agent Substances 0.000 description 6
- 238000000576 coating method Methods 0.000 description 6
- 238000000034 method Methods 0.000 description 5
- 239000000853 adhesive Substances 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- 238000007599 discharging Methods 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 229910002804 graphite Inorganic materials 0.000 description 3
- 239000010439 graphite Substances 0.000 description 3
- 229910052744 lithium Inorganic materials 0.000 description 3
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 239000002041 carbon nanotube Substances 0.000 description 2
- 229910021393 carbon nanotube Inorganic materials 0.000 description 2
- 239000006255 coating slurry Substances 0.000 description 2
- 238000005056 compaction Methods 0.000 description 2
- 238000010280 constant potential charging Methods 0.000 description 2
- 239000011888 foil Substances 0.000 description 2
- -1 lithium hexafluorophosphate Chemical group 0.000 description 2
- 230000014759 maintenance of location Effects 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
- 229920000049 Carbon (fiber) Polymers 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- OIFBSDVPJOWBCH-UHFFFAOYSA-N Diethyl carbonate Chemical compound CCOC(=O)OCC OIFBSDVPJOWBCH-UHFFFAOYSA-N 0.000 description 1
- KMTRUDSVKNLOMY-UHFFFAOYSA-N Ethylene carbonate Chemical group 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
- 239000002033 PVDF binder Substances 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000002174 Styrene-butadiene Substances 0.000 description 1
- HFCVPDYCRZVZDF-UHFFFAOYSA-N [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O Chemical compound [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O HFCVPDYCRZVZDF-UHFFFAOYSA-N 0.000 description 1
- 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 description 1
- 239000006230 acetylene black Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- MTAZNLWOLGHBHU-UHFFFAOYSA-N butadiene-styrene rubber Chemical compound C=CC=C.C=CC1=CC=CC=C1 MTAZNLWOLGHBHU-UHFFFAOYSA-N 0.000 description 1
- 239000004917 carbon fiber Substances 0.000 description 1
- 239000002134 carbon nanofiber Substances 0.000 description 1
- 239000001768 carboxy methyl cellulose Substances 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000010277 constant-current charging Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 239000011267 electrode slurry Substances 0.000 description 1
- 230000034964 establishment of cell polarity Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000011010 flushing procedure Methods 0.000 description 1
- 229910021389 graphene 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
- 230000007774 longterm Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000007773 negative electrode material Substances 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 239000002985 plastic film Substances 0.000 description 1
- 229920006255 plastic film Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- MCSINKKTEDDPNK-UHFFFAOYSA-N propyl propionate Chemical compound CCCOC(=O)CC MCSINKKTEDDPNK-UHFFFAOYSA-N 0.000 description 1
- RUOJZAUFBMNUDX-UHFFFAOYSA-N propylene carbonate Chemical compound CC1COC(=O)O1 RUOJZAUFBMNUDX-UHFFFAOYSA-N 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 description 1
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000011115 styrene butadiene Substances 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 239000002562 thickening agent Substances 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
-
- 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
- H01M4/04—Processes of manufacture in general
- H01M4/0402—Methods of deposition of the material
- H01M4/0404—Methods of deposition of the material by coating on electrode collectors
-
- 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
- H01M4/04—Processes of manufacture in general
- H01M4/0402—Methods of deposition of the material
- H01M4/0416—Methods of deposition of the material involving impregnation with a solution, dispersion, paste or dry powder
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
- H01M4/139—Processes of manufacture
-
- 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
- H01M4/36—Selection of substances as active materials, active masses, active liquids
- H01M4/362—Composites
- H01M4/366—Composites as layered products
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M4/621—Binders
- H01M4/622—Binders being polymers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M4/00—Electrodes
- H01M4/02—Electrodes composed of, or comprising, active material
- H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
- H01M2004/028—Positive electrodes
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The application provides a positive plate and a battery comprising the positive plate; the research shows that the higher the copolymerization proportion of the second monomer or the third monomer in the binder is, the larger the swelling rate is, the electrolyte can more easily enter the pores of the positive plate, and enough channels can be provided for the diffusion of lithium ions, so that the ion conductivity of the positive plate is improved, and the impedance of the positive plate is reduced.
Description
Technical Field
The application belongs to the technical field of batteries, and particularly relates to a positive plate and a battery comprising the positive plate.
Background
Lithium ion batteries have been widely used in consumer electronics over the last three decades since commercialization, and have evolved toward high energy densities and fast charging. The development of the current anode and cathode materials tends to be bottleneck, the energy density requirement is continuously improved, and higher requirements are put on the high-compaction anode and cathode, so that the high compaction is required, and meanwhile, higher dynamic performance is required to be maintained.
Because the resistivity of the positive electrode active material is far greater than that of the negative electrode graphite, the impedance of the positive electrode plate is far greater than that of the negative electrode plate, and the duty ratio of the positive electrode impedance in the battery cell is also far greater than that of the negative electrode impedance, so that the positive electrode active material is a main source of battery cell polarization. Particularly, in the later stage of high-temperature cycle of the lithium ion battery, the reactive sites of the positive electrode active material are gradually reduced, the adhesive property is reduced due to aging of the adhesive, the adhesive between the positive electrode active material and the conductive agent is gradually weakened, the effective capacity of the positive electrode active material is reduced, and the phenomena of capacity attenuation and the like of the battery occur. Therefore, the method reduces the initial impedance of the positive electrode, improves the dynamics of the positive electrode, and is an effective way for improving the cycle performance of the battery, in particular the high-temperature cycle performance.
Disclosure of Invention
In order to overcome the defects in the prior art, the application provides a positive plate and a battery comprising the positive plate; specifically, the application constructs the positive plate containing the double-layer positive electrode active material layer, and prepares the positive plate with dynamics and high cohesiveness by adjusting the copolymerization proportion of the comonomer of the binder in the positive electrode active material layer, and the positive plate has lower initial impedance while guaranteeing the processing performance, so that the dynamics of the positive electrode can be improved, the high-temperature cycle attenuation caused by the rapid deterioration of the positive plate impedance in the later cycle is relieved, and the battery comprising the positive plate has excellent multiplying power performance, constant current flushing ratio, low-temperature performance and high-temperature cycle performance.
The application aims at realizing the following technical scheme:
a positive electrode sheet including a positive electrode current collector, a first positive electrode active material layer provided on the positive electrode current collector, and a second positive electrode active material layer provided on the first positive electrode active material layer;
the first positive electrode active material layer comprises a first positive electrode active material, a first conductive agent and a first binder; the second positive electrode active material layer comprises a second positive electrode active material, a second conductive agent and a second binder;
the first binder is a copolymer of a first monomer and a second monomer; the second binder is a copolymer of a first monomer and a third monomer;
the first monomer is selected from vinylidene fluoride, the second monomer and the third monomer are the same or different, and are independently selected from at least one of methacrylic acid, methacrylic acid ester (such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate), hexafluoropropylene, acrylonitrile, ethylene oxide, vinyl chloride and ethylene glycol;
the copolymerization mole ratio of the second monomer in the first binder is less than the copolymerization mole ratio of the third monomer in the second binder.
According to an embodiment of the present application, the copolymerization molar ratio of the second monomer in the first binder is a percentage of the molar amount of the second monomer in the first binder to the total molar amount of the first monomer and the second monomer.
According to an embodiment of the present application, the copolymerization molar ratio of the third monomer in the second binder is a percentage of the molar amount of the third monomer in the second binder to the total molar amount of the first monomer and the third monomer.
According to an embodiment of the present application, the copolymerization molar ratio of the second monomer in the first binder is 0 to 10mol%, for example, 1mol%, 2mol%, 3mol%, 4mol%, 5mol%, 6mol%, 7mol%, 8mol% or 10mol%.
According to an embodiment of the present application, the copolymerization molar ratio of the third monomer in the second binder is 6mol% to 50mol%, for example, 6mol%, 8mol%, 10mol%, 15mol%, 20mol%, 25mol%, 30mol%, 35mol%, 40mol%, 45mol% or 50mol%.
According to an embodiment of the present application, the number average molecular weight of the first binder is 80 to 120 tens of thousands, for example 100 to 120 tens of thousands.
According to an embodiment of the application, the second binder has a number average molecular weight of 80-140 tens of thousands, for example 100-120 tens of thousands.
According to an embodiment of the present application, the mass of the first binder is 1wt% to 2wt%, for example, 1wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt%, or 2wt% of the total mass of the first positive electrode active material layer.
According to an embodiment of the present application, the mass of the second binder is 1wt% to 2wt%, for example, 1wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt%, or 2wt% of the total mass of the second positive electrode active material layer.
According to an embodiment of the present application, the thickness ratio of the first positive electrode active material layer and the second positive electrode active material layer is 8 to 5:2 to 5, for example, 8:2, 7:3, 6:4, or 5:5.
According to an embodiment of the present application, the first positive electrode active material and the second positive electrode active material are the same or different and are independently selected from at least one of lithium cobaltate, lithium iron phosphate, lithium nickel cobalt manganate, and the like.
According to an embodiment of the present application, the mass of the first positive electrode active material is 95wt% to 98.5wt% of the total mass of the first positive electrode active material layer.
According to an embodiment of the present application, the mass of the second positive electrode active material is 95wt% to 98.5wt% of the total mass of the first positive electrode active material layer.
According to an embodiment of the present application, the first conductive agent and the second conductive agent are the same or different and are independently selected from at least one of SP, conductive graphite, carbon fiber (VGCF), CNT, graphene, and the like.
According to an embodiment of the present application, the mass of the first conductive agent is 0.5wt% to 2wt%, for example, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt% or 2wt% of the total mass of the first positive electrode active material layer.
According to an embodiment of the present application, the mass of the second conductive agent is 0.5wt% to 2wt%, for example, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt% or 2wt% of the total mass of the second positive electrode active material layer.
The application also provides a preparation method of the positive plate, which comprises the following steps:
1) Preparing a slurry for forming a first positive electrode active material layer and a slurry for forming a second positive electrode active material layer, respectively;
2) And coating the slurry for forming the first positive electrode active material layer on the two side surfaces of the positive electrode current collector by using a coating machine, drying, and coating the slurry for forming the second positive electrode active material layer on the two side surfaces of the first positive electrode active material layer to prepare the positive electrode sheet.
According to an embodiment of the present application, in step 1), the solid content of the slurry for forming the first positive electrode active material layer and the slurry for forming the second positive electrode active material layer is 70wt% to 80wt%. The viscosity of the slurry for forming the first positive electrode active material layer and the slurry for forming the second positive electrode active material layer is 2000-7000 mPas.
The application also provides a battery, which comprises the positive plate.
According to an embodiment of the present application, the battery further includes a negative electrode sheet, a separator, and an electrolyte.
The application has the beneficial effects that:
the application provides a positive plate and a battery comprising the positive plate; the research shows that the higher the copolymerization proportion of the second monomer or the third monomer in the binder is, the larger the swelling rate is, the electrolyte can more easily enter the pores of the positive plate, and enough channels can be provided for the diffusion of lithium ions, so that the ion conductivity of the positive plate is improved, and the impedance of the positive plate is reduced.
Drawings
Fig. 1 shows a positive electrode sheet structure according to a preferred embodiment of the present application.
Detailed Description
The present application will be described in further detail with reference to specific examples. It is to be understood that the following examples are illustrative only and are not to be construed as limiting the scope of the application. All techniques implemented based on the above description of the application are intended to be included within the scope of the application.
The experimental methods used in the following examples are all conventional methods unless otherwise specified; the reagents, materials, etc. used in the examples described below are commercially available unless otherwise specified. In the description of the present application, it should be noted that the terms "first," "second," and the like are used for descriptive purposes only and are not indicative or implying relative importance.
Example 1
Preparing slurry A: mixing positive active material lithium cobaltate, conductive carbon black of a conductive agent, a carbon nano tube and polyvinylidene fluoride (copolymerization proportion is 0%, number average molecular weight is 100-120 ten thousand) according to a mass ratio of 97.5:0.7:0.5:1.3, adding NMP, and uniformly stirring to prepare an A slurry with viscosity of 3000-6000 mPa.s and solid content of 70-80 wt%;
preparing slurry B: mixing positive active material lithium cobaltate, conductive carbon black of a conductive agent, a carbon nano tube and a binder vinylidene fluoride-hexafluoropropylene copolymer (the content of hexafluoropropylene is 5mol percent, namely the copolymerization proportion is 5mol percent, the number average molecular weight is 100 ten thousand-120 ten thousand) according to the mass ratio of 97.5:0.7:0.5:1.3, adding NMP, and uniformly stirring to prepare a B slurry with the viscosity of 3000-6000 mPa.s and the solid content of 70-80wt percent;
and coating the slurry on an aluminum foil, specifically coating slurry A on the two side surfaces of the aluminum foil to form a first positive electrode active material layer, coating slurry B on the surface of the first positive electrode active material layer to form a second positive electrode active material layer, and drying and rolling at 80-110 ℃ to obtain the required positive electrode sheet. The thickness ratio of the first positive electrode active material layer to the second positive electrode active material layer in the positive electrode sheet is 7:3.
Example 2
The other points are that the content of hexafluoropropylene of the second binder of the positive electrode sheet is 10mol%, that is, the copolymerization ratio is 10mol%, and the number average molecular weight is 100 to 120 ten thousand, which is the same as that of example 1.
Example 3
The other points are that the content of hexafluoropropylene of the second binder of the positive electrode sheet is 20mol%, that is, the copolymerization ratio is 20mol%, and the number average molecular weight is 100 to 120 ten thousand, which is the same as that of example 1.
Example 4
The other points are that the content of hexafluoropropylene of the second binder of the positive electrode sheet is 40mol%, that is, the copolymerization ratio is 40mol%, and the number average molecular weight is 100 to 120 ten thousand, which is the same as that of example 1.
Example 5
The other points are that the content of hexafluoropropylene of the first binder of the positive electrode sheet is 10mol%, that is, the copolymerization ratio is 10mol%, and the number average molecular weight is 100 to 120 ten thousand, which is the same as that of example 1. The hexafluoropropylene content of the second binder is 40mol%, i.e. the copolymerization ratio is 40mol%, and the number average molecular weight is 100-120 ten thousand.
Comparative example 1
The other points are that the content of hexafluoropropylene of the first binder of the positive electrode sheet is 0mol%, that is, the copolymerization ratio is 0mol%, and the number average molecular weight is 100 to 120 ten thousand, which is the same as that of example 1. The hexafluoropropylene content of the second binder is 0mol%, i.e., the copolymerization ratio is 0mol%, and the number average molecular weight is 100 to 120 ten thousand.
Comparative example 2
The other points are that the content of hexafluoropropylene of the first binder of the positive electrode sheet is 40mol%, that is, the copolymerization ratio is 40mol%, and the number average molecular weight is 100 to 120 ten thousand, which is the same as that of example 1. The hexafluoropropylene content of the second binder is 40mol%, i.e. the copolymerization ratio is 40mol%, and the number average molecular weight is 100-120 ten thousand.
Comparative example 3
The other points are that the content of hexafluoropropylene of the first binder of the positive electrode sheet is 50mol%, that is, the copolymerization ratio is 50mol%, and the number average molecular weight is 100 to 120 ten thousand, which is the same as that of example 1. The hexafluoropropylene content of the second binder is 40mol%, i.e. the copolymerization ratio is 40mol%, and the number average molecular weight is 100-120 ten thousand.
Table 1 composition of positive electrode sheets of examples and comparative examples
Test example 1
Preparing a negative plate:
adding graphite as a negative electrode active material, a conductive agent (acetylene black), a thickening agent (sodium carboxymethylcellulose) and a binder (styrene-butadiene) into a stirring tank according to the mass ratio of 96:1:1.5:1.5, adding deionized water, fully stirring, passing through a 150-mesh screen to prepare a negative electrode slurry, coating the slurry on a copper foil by using a coating machine, and drying at the temperature of 80-120 ℃ to obtain the negative electrode plate.
Preparing an electrolyte:
the electrolyte is provided by New Sakubang corporation, the solvent is ethylene carbonate, propylene carbonate, diethyl carbonate, n-propyl propionate, and the solute is lithium hexafluorophosphate (LiPF) 6 ) And the content of the water and the free acid is qualified through detection.
Preparing a diaphragm:
an 8 μm polyethylene membrane (available from Asahi chemical Co., ltd.) was used.
Assembling an electric core:
and winding the prepared positive plate, negative plate and diaphragm to form a winding core, packaging with an aluminum plastic film, injecting electrolyte after baking moisture is qualified, and performing thermocompression forming process to form, sealing and sorting to obtain the battery core.
The performance test was performed on the lithium ion batteries assembled with the positive electrode tabs of the above examples and comparative examples, the test procedure being as follows,
1. rate charging performance-constant current charging ratio
Under the environment of 25 ℃, the battery cell discharges to 3V at 0.2 ℃; standing for 10min, charging to 4.45V at 1C and 2C respectively, and charging at 4.45V at constant voltage, and cutting off current at 0.05C; discharging to cut-off voltage of 3.0V with 0.2C current, recording constant current charge capacity Q and total charge capacity Q under each multiplying power 0 Constant current flush ratio (%) was calculated: q (Q) 0 /Q 1 ×100％。
2. Temperature characteristic test
Under the environment of 25 ℃, the battery cell discharges to 3V at 0.2 ℃; standing for 10min, charging to 4.45V at 0.7C, charging at constant voltage of 4.45V, cutting off current 0.05C, discharging to 3V at 0.2C, and recording initial discharge capacity Q 0 The method comprises the steps of carrying out a first treatment on the surface of the Charging to 4.45V at 0.7C, constant voltage charging at 4.45V, and constant voltage charging at 4.45V, stopping current at 0.05C, respectively standing at 25deg.C/45deg.C/0deg.C/20deg.C for 4 hours, discharging to 3V at 0.2C, recording corresponding capacity Q, and calculating capacity retention rate: Q/Q 0 ×100％。
3. 45 ℃ 1.5C ladder charge/0.7C cycle test
Under 45 ℃ environment, the battery is charged to 4.25V according to 1.5C, charged to 4.45V according to 0.8C, and charged to 4.45V at constant voltage of 4.45V, cut-off current is 0.05C, then discharged to 3V according to 0.7C, and initial capacity Q is recorded 0 And (3) circulating according to the system, recording the discharge capacity Q when the number of circulating turns reaches 800 times, and calculating the capacity retention (%): Q/Q 0 ×100％。
Table 2 results of performance test of the batteries of examples and comparative examples
From the table, the positive plate prepared by the method has excellent bonding performance, and can obtain better multiplying power performance, low-temperature discharge performance and high-temperature cycle performance on the premise of ensuring the stripping force requirement of the positive plate.
Further, the batteries of comparative examples 3 and 4 were less different in electrical properties after a short period in cycle from those of examples 1 to 4 mainly because the temperature characteristics and rate charging examined short-term properties, the adhesive properties required for the adhesive were lower, the cycle properties were long-term properties, and the adhesive properties required for the adhesive were higher.
In summary, by adjusting the copolymerization ratio of the monomers in the binder of the first positive electrode active material layer and the second positive electrode active material layer, a positive electrode sheet having both high adhesion and excellent kinetics is constructed, and a battery including the positive electrode sheet is significantly improved in terms of rate performance, low-temperature discharge performance, and high-temperature cycle performance as compared with the comparative example.
The embodiments of the present application have been described above. However, the present application is not limited to the above embodiment. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.
Claims (10)
1. A positive electrode sheet, characterized in that the positive electrode sheet includes a positive electrode current collector, a first positive electrode active material layer provided on the positive electrode current collector, and a second positive electrode active material layer provided on the first positive electrode active material layer; the first positive electrode active material layer comprises a first positive electrode active material, a first conductive agent and a first binder; the second positive electrode active material layer comprises a second positive electrode active material, a second conductive agent and a second binder; the first binder is a copolymer of a first monomer and a second monomer; the second binder is a copolymer of a first monomer and a third monomer;
the first monomer is selected from vinylidene fluoride, the second monomer and the third monomer are the same or different, and are independently selected from at least one of methacrylic acid, methacrylic acid ester, hexafluoropropylene, acrylonitrile, ethylene oxide, vinyl chloride and ethylene glycol;
the copolymerization mole ratio of the second monomer in the first binder is less than the copolymerization mole ratio of the third monomer in the second binder.
2. The positive electrode sheet according to claim 1, wherein the copolymerization molar ratio of the second monomer in the first binder is 0 to 10mol%.
3. The positive electrode sheet according to claim 1 or 2, wherein the copolymerization molar ratio of the third monomer in the second binder is 6mol% to 50mol%.
4. The positive electrode sheet according to claim 1, wherein the methacrylate is at least one of methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, and isopropyl methacrylate.
5. The positive electrode sheet according to claim 1 or 2, wherein the number average molecular weight of the first binder is 80 to 120 tens of thousands;
and/or the number average molecular weight of the second binder is 80-140 ten thousand.
6. The positive electrode sheet according to claim 1, wherein the mass of the first binder is 1 to 2wt% of the total mass of the first positive electrode active material layer;
and/or the mass of the second binder accounts for 1-2 wt% of the total mass of the second positive electrode active material layer.
7. The positive electrode sheet according to claim 1, wherein the thickness ratio of the first positive electrode active material layer and the second positive electrode active material layer is 8 to 5:2 to 5.
8. The positive electrode sheet according to claim 1, wherein the mass of the first positive electrode active material is 95 to 98.5wt% of the total mass of the first positive electrode active material layer;
and/or, the mass of the second positive electrode active material accounts for 95-98.5 wt% of the total mass of the first positive electrode active material layer.
9. The positive electrode sheet according to claim 1, wherein,
the mass of the first conductive agent accounts for 0.5-2wt% of the total mass of the first positive electrode active material layer;
and/or the mass of the second conductive agent accounts for 0.5-2 wt% of the total mass of the second positive electrode active material layer.
10. A battery comprising the positive electrode sheet according to any one of claims 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210412730.7A CN116960332A (en) | 2022-04-19 | 2022-04-19 | Positive plate and battery comprising same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210412730.7A CN116960332A (en) | 2022-04-19 | 2022-04-19 | Positive plate and battery comprising same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116960332A true CN116960332A (en) | 2023-10-27 |
Family
ID=88444902
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210412730.7A Pending CN116960332A (en) | 2022-04-19 | 2022-04-19 | Positive plate and battery comprising same |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116960332A (en) |
-
2022
- 2022-04-19 CN CN202210412730.7A patent/CN116960332A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110635133B (en) | Quick-charging type lithium ion battery and preparation method thereof | |
| CN111725509B (en) | Negative electrode material, negative electrode slurry, negative electrode plate and lithium ion battery | |
| CN105514488A (en) | Adhesive and lithium ion battery with same | |
| WO2015018114A1 (en) | Aqueous composite binder of natural polymer derivative-conducting polymer and application thereof | |
| CN111533851A (en) | Preparation method of polymer electrolyte and application of polymer electrolyte in all-solid-state battery | |
| KR20110063671A (en) | Silicon negative electrode, lithium ion battery and a method of preparing the same | |
| CN112103468B (en) | Negative plate and lithium ion battery comprising same | |
| CN109957361B (en) | Water-based binder and secondary battery | |
| CN113113605B (en) | Network structure ion conductive adhesive and preparation method and application thereof | |
| JP7160696B2 (en) | Electrodes for non-aqueous electrolyte secondary batteries | |
| CN114335900A (en) | Diaphragm and battery containing same | |
| CN110459723A (en) | Battery diaphragm and preparation method thereof and battery with the battery diaphragm | |
| CN111934020B (en) | High-pressure-resistant all-solid-state lithium battery interface layer and in-situ preparation method and application thereof | |
| CN112563563A (en) | Composite solid electrolyte, solid battery and preparation method thereof | |
| CN101826640B (en) | Pole core for lithium ion battery and lithium ion battery using pole core | |
| CN112615111A (en) | High-liquid-retention self-repairing diaphragm, preparation method thereof and lithium ion battery | |
| CN109461935A (en) | Electrode slice and electrochemical energy storage device | |
| CN114937813A (en) | Lithium ion battery and electronic device | |
| JP2002251999A (en) | Nonaqueous battery, paste for electrode used in battery and electrode | |
| JP2022536290A (en) | In-situ polymerized polymer electrolyte for lithium-ion batteries | |
| KR20200123781A (en) | Slurry composition for lithium ion secondary battery and electrode for lithium ion secondary battery | |
| CN116144290B (en) | Terpolymer adhesive, preparation method thereof and application thereof in silicon-based lithium ion battery | |
| CN116666550A (en) | Preparation methods of positive plate, solid electrolyte and battery thereof | |
| CN114142039B (en) | Adhesive and lithium ion battery comprising same | |
| CN114927749A (en) | Preparation method of high-performance polymer/inorganic ceramic composite solid electrolyte |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication |