CN116154179A - Carbon-coated aluminum foil and preparation method and application thereof - Google Patents
Carbon-coated aluminum foil and preparation method and application thereof Download PDFInfo
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- CN116154179A CN116154179A CN202310124041.0A CN202310124041A CN116154179A CN 116154179 A CN116154179 A CN 116154179A CN 202310124041 A CN202310124041 A CN 202310124041A CN 116154179 A CN116154179 A CN 116154179A
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- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 143
- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 133
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 title claims abstract description 79
- 229910052782 aluminium Inorganic materials 0.000 title claims abstract description 79
- 239000011888 foil Substances 0.000 title claims abstract description 79
- 238000002360 preparation method Methods 0.000 title abstract description 49
- 239000004005 microsphere Substances 0.000 claims abstract description 82
- 239000011248 coating agent Substances 0.000 claims abstract description 15
- 238000000576 coating method Methods 0.000 claims abstract description 15
- 238000000034 method Methods 0.000 claims abstract description 13
- 239000000463 material Substances 0.000 claims abstract description 12
- 229920005992 thermoplastic resin Polymers 0.000 claims abstract description 6
- 239000000853 adhesive Substances 0.000 claims description 44
- 230000001070 adhesive effect Effects 0.000 claims description 44
- 239000002002 slurry Substances 0.000 claims description 38
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 claims description 16
- 229920002239 polyacrylonitrile Polymers 0.000 claims description 15
- 239000011258 core-shell material Substances 0.000 claims description 14
- 229920001490 poly(butyl methacrylate) polymer Polymers 0.000 claims description 12
- 239000002245 particle Substances 0.000 claims description 11
- 239000007774 positive electrode material Substances 0.000 claims description 10
- 229920000193 polymethacrylate Polymers 0.000 claims description 9
- 239000004793 Polystyrene Substances 0.000 claims description 8
- 229920002223 polystyrene Polymers 0.000 claims description 8
- 239000002033 PVDF binder Substances 0.000 claims description 7
- 239000000178 monomer Substances 0.000 claims description 7
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 7
- 239000002994 raw material Substances 0.000 claims description 7
- 239000000839 emulsion Substances 0.000 claims description 6
- 229920003229 poly(methyl methacrylate) Polymers 0.000 claims description 6
- 239000004926 polymethyl methacrylate Substances 0.000 claims description 6
- 239000008367 deionised water Substances 0.000 claims description 5
- 229910021641 deionized water Inorganic materials 0.000 claims description 5
- 229920000058 polyacrylate Polymers 0.000 claims description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 5
- 239000011230 binding agent Substances 0.000 claims description 4
- 229920005569 poly(vinylidene fluoride-co-hexafluoropropylene) Polymers 0.000 claims description 4
- 239000006229 carbon black Substances 0.000 claims description 3
- 239000006258 conductive agent Substances 0.000 claims description 3
- 239000002270 dispersing agent Substances 0.000 claims description 3
- 238000001035 drying Methods 0.000 claims description 3
- 239000002904 solvent Substances 0.000 claims description 3
- 229920002319 Poly(methyl acrylate) Polymers 0.000 claims description 2
- 229920001577 copolymer Polymers 0.000 claims description 2
- 229910000625 lithium cobalt oxide Inorganic materials 0.000 claims description 2
- BFZPBUKRYWOWDV-UHFFFAOYSA-N lithium;oxido(oxo)cobalt Chemical compound [Li+].[O-][Co]=O BFZPBUKRYWOWDV-UHFFFAOYSA-N 0.000 claims description 2
- URIIGZKXFBNRAU-UHFFFAOYSA-N lithium;oxonickel Chemical compound [Li].[Ni]=O URIIGZKXFBNRAU-UHFFFAOYSA-N 0.000 claims description 2
- 229920000120 polyethyl acrylate Polymers 0.000 claims description 2
- 238000007334 copolymerization reaction Methods 0.000 claims 2
- 239000010405 anode material Substances 0.000 abstract description 8
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 abstract description 2
- 229910001416 lithium ion Inorganic materials 0.000 abstract description 2
- 239000010410 layer Substances 0.000 description 66
- 238000012360 testing method Methods 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- 238000007665 sagging Methods 0.000 description 7
- 239000000523 sample Substances 0.000 description 6
- 238000011056 performance test Methods 0.000 description 4
- 239000012790 adhesive layer Substances 0.000 description 3
- 238000013329 compounding Methods 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- SOGAXMICEFXMKE-UHFFFAOYSA-N Butylmethacrylate Chemical compound CCCCOC(=O)C(C)=C SOGAXMICEFXMKE-UHFFFAOYSA-N 0.000 description 2
- 239000003610 charcoal Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000007731 hot pressing Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 description 1
- 239000002390 adhesive tape Substances 0.000 description 1
- 239000005030 aluminium foil Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000010406 cathode material Substances 0.000 description 1
- 239000006255 coating slurry Substances 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- FCZCIXQGZOUIDN-UHFFFAOYSA-N ethyl 2-diethoxyphosphinothioyloxyacetate Chemical compound CCOC(=O)COP(=S)(OCC)OCC FCZCIXQGZOUIDN-UHFFFAOYSA-N 0.000 description 1
- 229910021389 graphene Inorganic materials 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 238000004381 surface treatment Methods 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
- H01M4/64—Carriers or collectors
- H01M4/66—Selection of materials
- H01M4/665—Composites
- H01M4/667—Composites in the form of layers, e.g. coatings
-
- 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
-
- 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
- H01M4/64—Carriers or collectors
- H01M4/66—Selection of materials
- H01M4/661—Metal or alloys, e.g. alloy coatings
-
- 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
- H01M4/64—Carriers or collectors
- H01M4/66—Selection of materials
- H01M4/663—Selection of materials containing carbon or carbonaceous materials as conductive part, e.g. graphite, carbon fibres
-
- 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
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Composite Materials (AREA)
- Manufacturing & Machinery (AREA)
- Cell Electrode Carriers And Collectors (AREA)
Abstract
The application relates to the technical field of lithium ion batteries, in particular to a carbon-coated aluminum foil and a preparation method and application thereof. The carbon-coated aluminum foil comprises an aluminum foil body and conductive carbon layers coated and solidified on two sides of the aluminum foil body, wherein a plurality of bonding microspheres protruding out of thermoplastic resin materials of the conductive carbon layers are arranged in the conductive carbon layers. The bonding microsphere in the application can effectively improve the compatibility of the conductive carbon layer and the anode material by means of the characteristics of the bonding microsphere, and can also ensure the fastness of the coating, and the obtained carbon-coated aluminum foil has the advantages of safety, long service life, suitability for high current, stable and difficult falling of the coating in the application process and the like.
Description
Technical Field
The application relates to the technical field of lithium ion batteries, in particular to a carbon-coated aluminum foil and a preparation method and application thereof.
Background
The carbon-coated aluminum foil is a breakthrough technical innovation for carrying out surface treatment on a battery conductive base material by utilizing a functional material, is widely used as a carrier of a positive electrode material, has excellent static conductive performance, and can be further processed into the positive electrode material by coating slurry such as lithium iron phosphate and the like.
The lithium iron phosphate anode material in the related art consists of an aluminum foil, and a lithium iron phosphate layer (LFP layer) and a conductive carbon layer which are sequentially coated on two sides of the aluminum foil, and the anode material benefits from the characteristics of the lithium iron phosphate material and the conductive carbon layer, so that the contact resistance between the anode material and a current collecting layer can be greatly reduced;
however, the lithium iron phosphate positive electrode material has the defects of low electron and ion conductivity, relatively small mass density and tap density and the like, so that the problems of poor conductive performance, poor adhesive force (cohesiveness) of a conductive carbon layer, easy powder falling and the like exist in practical application.
In summary, there is an urgent need to provide a carbon-coated aluminum foil, and a preparation method and application thereof, where the carbon-coated aluminum foil overcomes the drawbacks of directly coating lithium iron phosphate material in the prior art in the practical application process, and has excellent conductivity and conductive carbon layer adhesion, and the conductive carbon layer is not easy to fall off or fall off.
Disclosure of Invention
In order to ensure that the carbon-coated aluminum foil has excellent conductivity and conductive carbon layer fixing force in the application process, and the conductive carbon layer is not easy to fall off or fall off, the application particularly provides the carbon-coated aluminum foil and a preparation method and application thereof.
In a first aspect, the present application provides a carbon-coated aluminum foil, which adopts the following technical scheme:
the carbon-coated aluminum foil comprises an aluminum foil body and conductive carbon layers coated and solidified on two sides of the aluminum foil body, wherein a plurality of bonding microspheres protruding from thermoplastic resin materials of the conductive carbon layers are arranged in the conductive carbon layers.
Through adopting above-mentioned technical scheme, a plurality of bonding microballoons that outstanding thermoplastic resin material in electrically conductive charcoal layer, it is when being fixed in the aluminium foil and using as the carrier, can rely on self sagging degree and adhesion, when strengthening the adhesion fastness, compares in the tie coat still difficult conductive property who influences oneself.
Preferably, the bonding microsphere is in a core-shell structure, the softening point of the shell is 60-80 ℃, and the softening point of the inner core is 120-200 ℃.
By adopting the technical scheme, when the core-shell structure bonding microsphere is fixed on an aluminum foil and is used as a carrier, the shell structure of the core-shell structure bonding microsphere can be properly softened in the post-treatment anode/diaphragm/cathode hot-pressing process besides firmly bonding and reinforcing the aluminum foil and the anode material, so that the conductivity and the bonding property of the core-shell structure bonding microsphere are both considered.
Preferably, the bonding microsphere is formed by mixing and copolymerizing polyvinylidene fluoride and one or more of copolymer thereof, polyacrylate, polymethacrylate, polystyrene and polyacrylonitrile.
Preferably, the bonding microsphere is formed by mixing and copolymerizing one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polymethyl acrylate, polyethyl acrylate, polybutyl methacrylate, polymethyl methacrylate, polystyrene and polyacrylonitrile.
Preferably, the shell of the bonding microsphere is composed of polybutylmethacrylate and one of polyacrylate or polymethyl methacrylate according to the weight ratio of 1 (1-10);
the inner core of the bonding microsphere is formed by copolymerizing one or more monomers of polystyrene, polyacrylonitrile, polyvinylidene fluoride-hexafluoropropylene and polymethyl methacrylate.
By adopting the technical scheme, the adhesive microsphere with the components and/or the proportion has excellent adhesive force by virtue of the characteristics, and also has proper sagging degree and softening point by virtue of the multi-component compounding and structure, so that the conductive performance and the adhesive performance are both realized.
Preferably, the coverage of the bonded microsphere is 10-80% and the average particle size is 3-5um.
By adopting the technical scheme, the adhesive microsphere with the particle size and/or the coverage rate not only can provide excellent adhesive force for the conductive carbon layer and ensure that the conductive carbon layer is not easy to fall off, but also can give consideration to the overall conductivity and fastness of the carbon-coated aluminum foil.
Preferably, the slurry of the conductive carbon layer consists of the following components in percentage by weight: 7.8-13.5% of conductive carbon powder, 0.2-1.5% of bonding microsphere and the balance of deionized water.
By adopting the technical scheme, the slurry of the conductive carbon layer with the components and/or the proportion not only can provide excellent fastness for the carbon-coated aluminum foil by virtue of the characteristics of the bonding microspheres, but also is not easy to influence the original conductive performance of the carbon-coated aluminum foil, so that the carbon-coated aluminum foil has higher application value.
In a second aspect, the present application provides a method for preparing a carbon-coated aluminum foil, comprising the steps of:
s1, preparing slurry of a conductive carbon layer: sequentially adding conductive carbon powder and raw material emulsion of bonding microspheres into deionized water, and obtaining slurry of a conductive carbon layer after the raw material emulsion is uniformly dispersed;
s2, coating a conductive carbon layer: and (3) coating the slurry of the conductive carbon layer obtained in the step (S1) on two sides of the aluminum foil, and drying and solidifying the slurry to obtain the carbon-coated aluminum foil.
By adopting the technical scheme, the method has the advantages that the process steps and conditions are obviously simplified, and meanwhile, the obtained carbon-coated aluminum foil has stable performance and excellent fastness and conductivity, so that the method is suitable for mass industrialized production.
In a third aspect, the present application provides an application of a carbon-coated aluminum foil, which adopts the following technical scheme:
the application of the carbon-coated aluminum foil is that the carbon-coated aluminum foil is coated and solidified with a positive electrode material;
the positive electrode material is one or more of lithium iron phosphate, lithium cobalt oxide and lithium nickel oxide.
Preferably, the carbon-coated aluminum foil is coated and solidified with lithium iron phosphate, and the lithium iron phosphate slurry comprises the following components in proportion:
40-50% of lithium iron phosphate LFP, 1-3% of dispersing agent, 2-3% of conductive agent carbon black and binder PVDF:2-4% of NMP solvent and the balance.
Through adopting above-mentioned technical scheme, by the charcoal-coated aluminum foil that obtains in this application, when as the carrier, except can rely on the sagging degree and the binder of bonding microballon self effectual guarantee its and positive electrode material's bonding fastness, still be difficult for influencing positive electrode material's conductive properties.
In summary, the present application has the following beneficial effects:
1. the adhesive microspheres of the thermoplastic resin material and/or the core-shell structure protruding from the conductive carbon layer can strengthen the coating fastness by virtue of the sagging degree and the adhesive force of the adhesive microspheres after being fixed on the aluminum foil, and meanwhile, the adhesive microspheres are not easy to influence the conductivity of the carbon-coated aluminum foil compared with an adhesive layer when being used as a carrier;
2. the carbon-coated aluminum foil has the advantages that the process and conditions are obviously simplified, and meanwhile, the obtained carbon-coated aluminum foil has stable performance and excellent fastness and conductivity, so that the carbon-coated aluminum foil has high application value and is suitable for mass industrialized production; 3. the carbon-coated aluminum foil obtained in the application is not easy to influence the conductivity of the anode material except that the sagging degree and the binding force of the binding microsphere can be used as a carrier to effectively ensure the binding fastness of the binding microsphere and the anode material.
Detailed Description
The present application is described in further detail below with reference to examples.
Preparation example
Preparation example 1
A bonding microsphere is composed of polybutylmethacrylate, polymethacrylate and polyacrylonitrile according to a weight ratio of 1:1:2.
Preparation example 2
The bonding microsphere is different from the preparation example 1 in that the bonding microsphere has a core-shell structure, the shell of the bonding microsphere is composed of polybutylmethacrylate and polymethacrylate according to the weight ratio of 1:1, the core is formed by copolymerizing polyacrylonitrile monomers, and the weight ratio of the shell to the core is 1:1.
Preparation example 3
The bonding microsphere is different from the preparation example 1 in that the bonding microsphere has a core-shell structure, the shell of the bonding microsphere is composed of polybutylmethacrylate and polyacrylate according to the weight ratio of 1:1, the core is formed by copolymerizing polyacrylonitrile monomers, and the weight ratio of the shell to the core is 1:1.
Preparation example 4
The bonding microsphere is different from the preparation example 1 in that the bonding microsphere has a core-shell structure, the shell of the bonding microsphere is composed of polybutylmethacrylate and polymethacrylate according to the weight ratio of 1:5, the core is formed by copolymerizing polyacrylonitrile monomers, and the weight ratio of the shell to the core is 1:1.
Preparation example 5
The bonding microsphere is different from the preparation example 1 in that the bonding microsphere has a core-shell structure, the shell of the bonding microsphere is composed of polybutylmethacrylate and polymethacrylate according to the weight ratio of 1:10, the core is formed by copolymerizing polyacrylonitrile monomers, and the weight ratio of the shell to the core is 1:1.
Preparation example 6
The bonding microsphere is different from the preparation example 1 in that the bonding microsphere has a core-shell structure, the shell of the bonding microsphere is composed of polybutylmethacrylate and polymethacrylate according to the weight ratio of 1:15, the core is formed by copolymerizing polyacrylonitrile monomers, and the weight ratio of the shell to the core is 1:1.
Preparation example 7
The bonding microsphere is different from the preparation example 1 in that the bonding microsphere has a core-shell structure, the shell of the bonding microsphere is composed of polybutylmethacrylate and polymethacrylate according to the weight ratio of 1:1, the inner core is formed by copolymerizing polystyrene and polyacrylonitrile according to the weight ratio of 1:1, and the weight ratio of the shell to the inner core is 1:1.
Preparation examples 8 to 12
The conductive carbon layer slurry is prepared by mixing the following components in parts by weight (calculated according to each 100 kg) at the normal temperature of 1200r/min for 30 min;
table: the conductive carbon layer slurries of preparation examples 8 to 12 were composed of the components and weight (kg)
Wherein the conductive carbon powder is graphene with the particle size of 1000nm, all the adopted bonding microspheres are prepared from preparation example 1, and the average particle size is 3um.
Preparation examples 13 to 18
The slurry of the conductive carbon layer is different from that of preparation example 8 in that the adhesive microspheres used are used differently, as shown in the following table:
table: use of adhesive microspheres in preparation examples 13 to 18
| Group of | Use of adhesive microspheres |
| Preparation example 13 | Adhesive microspheres were prepared from preparation 2 |
| PREPARATION EXAMPLE 14 | Adhesive microspheres were prepared from preparation 3 |
| Preparation example 15 | Adhesive microspheres were prepared from preparation 4 |
| PREPARATION EXAMPLE 16 | Adhesive microspheres were prepared from preparation 5 |
| Preparation example 17 | Adhesive microspheres were prepared from preparation 6 |
| PREPARATION EXAMPLE 18 | Adhesive microspheres were prepared from preparation 7 |
Performance test the carbon coated aluminum foils prepared in each example and comparative example were selected as test objects, and then tested for adhesion and conductivity, respectively, as follows:
adhesion force: firstly cutting a sample to be tested into a sample with the thickness of 10mm and 100mm, then placing the sample on a clamp of a testing machine, setting the speed to be 100 mm/mm, adhering the sample on one side of a coating by using a 3M adhesive tape, recording the force required for stripping the coating by 180 degrees, and taking an average value of test results.
Conductive properties: and (3) selecting a lattice ST2258 film sheet resistance four-probe tester to perform surface resistance test of the sample to be tested, wherein the size range of the surface resistance test is <10mΩ.
Examples
Examples 1 to 5
The carbon-coated aluminum foil comprises an aluminum foil body (thickness 13 um) and conductive carbon layers (thickness 1 um) coated on two sides of the aluminum foil, and is prepared by adopting the following process:
s1, preparing slurry of a conductive carbon layer: sequentially adding conductive carbon powder and raw material emulsion of bonding microspheres into deionized water, and obtaining slurry of a conductive carbon layer after the raw material emulsion is uniformly dispersed;
s2, coating a conductive carbon layer and an LFP layer: and (3) coating the slurry of the conductive carbon layer obtained in the step (S1) on two sides of an aluminum foil (the coverage rate of the bonding microspheres is 80%), and drying and solidifying the slurry to obtain the carbon-coated aluminum foil.
The use conditions of the conductive carbon layer slurry are shown in the following table:
table: use cases of conductive carbon layer paste in examples 1 to 5
| Group of | Use condition of conductive carbon layer slurry |
| Example 1 | The conductive carbon layer slurry was prepared in preparation example 8 |
| Example 2 | The conductive carbon layer slurry was prepared in preparation example 9 |
| Example 3 | Conductive carbon layer slurry was prepared from preparation example 10 |
| Example 4 | Conductive carbon layer slurry was prepared from preparation 11 |
| Example 5 | The conductive carbon layer slurry was prepared in preparation example 12 |
Comparative example 1
The carbon-coated aluminum foil is different from example 1 in that the conductive carbon layer does not contain adhesive microspheres, and the conductive carbon layer is coated with a methacrylic acid Ding Zhijiao adhesive layer with a thickness of 1um.
Comparative example 2
The carbon coated aluminum foil is different from example 1 in that the adhesive microspheres in the conductive carbon layer have a particle size of 0.8um, i.e., less than the thickness of the conductive carbon layer, and are not protruded from the conductive carbon layer.
The carbon-coated aluminum foils of examples 1-5 and comparative examples 1-2 were drawn and then tested for adhesion and conductivity, respectively, and the average value of the test results was recorded in the following table.
Table: results of Performance test of examples 1-5 and comparative examples 1-2
As can be seen from the above table, the carbon-coated aluminum foils prepared in examples 1 to 5 all have excellent adhesion and conductivity, the adhesion is as high as 300 to 328N/m, the conductivity is 3 to 5mΩ, and compared with the group using butyl methacrylate as the adhesive layer in comparative example 1, the conductivity is significantly improved;
as shown in examples 1-3, the adhesion force can be further improved with the increase of the amount of the bonding microspheres, but the negative effect on the conductivity cannot be avoided, and the defect can be overcome by properly increasing the ratio of the conductive carbon powder, but the proportion of the conductive carbon powder and the bonding microspheres is noted, otherwise the adhesion force is influenced;
it is also known from examples 2 and 4 to 5 that the basic conductivity is constant when the amount of the conductive carbon powder is constant, but the adhesive force and conductivity of the adhesive microspheres cannot be effectively compatible with the small amount and the large amount, so that the amount of the adhesive microspheres is preferably 0.2 to 1.5%.
It is also known from examples 1 to 5 and comparative example 2 that the adhesive microspheres should protrude from the conductive carbon layer to exert their adhesion enhancing effect, i.e., the adhesive force is only 220N/m and the conductive properties are not substantially affected when the particle size of the adhesive microspheres is smaller than the thickness of the conductive carbon layer.
The slurry of the conductive carbon layer with the components and/or the proportions not only can obviously strengthen the coating fastness through the sagging degree and the binding force of the adhesive microsphere which is made of thermoplastic resin material and protrudes out of the conductive carbon layer, but also does not easily influence the conductive performance of the carbon-coated aluminum foil and the processed anode, thereby taking the overall conductive performance and the fastness of the carbon-coated aluminum foil into account.
Examples 6 to 11
The carbon-coated aluminum foil is different from example 1 in the use condition of the conductive carbon layer slurry, specifically shown in the following table:
table: use cases of conductive carbon layer paste in examples 6 to 11
| Group of | Use condition of conductive carbon layer slurry |
| Example 1 | The conductive carbon layer slurry was prepared in preparation example 8 |
| Example 6 | Conductive carbon layer slurry was prepared from preparation example 13 |
| Example 7 | Conductive carbon layer slurryThe materials were prepared in accordance with preparation 14 |
| Example 8 | Conductive carbon layer slurry was prepared from preparation example 15 |
| Example 9 | The conductive carbon layer paste was prepared in preparation example 16 |
| Example 10 | The conductive carbon layer slurry was prepared in preparation example 17 |
| Example 11 | The conductive carbon layer slurry was prepared in preparation example 18 |
The carbon coated aluminum foils of examples 6-11 above were drawn and then tested for adhesion and conductivity, respectively, and the average of the test results was reported in the following table.
Table: examples 1, 6-11 Performance test results
As can be seen from the table, the carbon-coated aluminum foils prepared in examples 6 to 11 all have excellent adhesive force and conductivity, the adhesive force is as high as 321 to 328N/m, the conductivity is 1.5 to 2.0mΩ, and compared with the bonding microsphere with a non-core-shell structure in example 1, the properties of the carbon-coated aluminum foil are improved to different degrees;
as can be seen from examples 1 and 6, the adhesive microsphere with core-shell structure can firmly adhere the conductive carbon layer and the anode material coated by the subsequent process on the premise of the same raw material components compared with the pure mixed adhesive microsphere, thereby guaranteeing the adhesive force;
the softening point of the bonded microsphere shell is 60-80 ℃, the softening point of the inner core is 120-200 ℃, and the shell structure of the bonded microsphere shell can be properly softened in the post-treatment positive electrode/diaphragm/negative electrode hot pressing process, and the inner core is not affected, so that the conductivity and the bonding performance of the carbon-coated aluminum foil are both considered.
It is also clear from examples 6, 8 to 10 that the conductive properties are substantially unchanged in the case of the polyacrylonitrile core, and the conductive properties are 2.0mΩ, and further preferred is a core formed by copolymerizing polystyrene and polyacrylonitrile, and the surface resistance is 1.5mΩ, as shown in examples 6 to 11;
the adhesive force of the adhesive is higher than the relative degree of the components of the shell, preferably, the adhesive is formed by polybutylmethacrylate and polymethacrylate according to the weight ratio of 1 (1-10), after the adhesive force exceeds the range, the adhesive force is reduced, and the situation that the ratio difference of the two components is too large is presumed, and the compounding effect is lost.
The adhesive microsphere prepared from the components and/or the proportions has excellent adhesive force by virtue of the characteristics, and also has proper sagging degree and softening point by virtue of multi-component compounding and a structure, so that the conductive performance and the adhesive performance are both realized.
Examples 12 to 16
The carbon coated aluminum foil differs from example 1 in that the coverage and/or average particle size of the bonded microspheres in the conductive carbon layer slurry employed is different, as shown in the following table:
table: coverage and/or average particle size of the bonded microspheres in examples 12-16
The carbon coated aluminum foils of examples 12-16 above were drawn and then tested for adhesion and conductivity, respectively, and the average of the test results is reported in the following table.
Table: examples 1, 12-16 Performance test results
As can be seen from the above table, the carbon-coated aluminum foils prepared in examples 12 to 16 all have excellent adhesion and conductivity, the adhesion is as high as 291-315N/m, and the conductivity is 2.0-3.0mΩ;
it is also evident from examples 12 to 16 that the higher the coverage of the bonded microspheres, the stronger the adhesion thereof; the particle size is mainly related to the conductivity and is preferably 4 um;
the adhesive microsphere with the particle size and/or coverage rate can provide excellent adhesive force for the conductive carbon layer, so that the conductive carbon layer is not easy to fall off, and the overall conductivity and the fastness of the carbon-coated aluminum foil are also considered.
Application example
The positive electrode material of the carbon-coated aluminum foil in application example 1 further comprises LFP layer slurry (coating thickness 140 um) coated and cured on two sides of the carbon-coated aluminum foil;
the LFP layer slurry used consists of the following components in percentage by weight: 45% of lithium iron phosphate LFP, 2% of dispersing agent, 2.5% of conductive agent carbon black, 3% of binder PVDF and 45% of solvent NMP.
Through detection, the cathode material effectively overcomes the defect of the original direct coating of the lithium iron phosphate material, has excellent conductivity and conductive carbon layer fixing force, and is not easy to fall off or fall off.
The present embodiment is merely illustrative of the present application and is not intended to be limiting, and those skilled in the art, after having read the present specification, may make modifications to the present embodiment without creative contribution as required, but is protected by patent laws within the scope of the claims of the present application.
Claims (10)
1. The carbon-coated aluminum foil comprises an aluminum foil body and conductive carbon layers coated and solidified on two sides of the aluminum foil body, and is characterized in that a plurality of bonding microspheres protruding from thermoplastic resin materials of the conductive carbon layers are arranged in the conductive carbon layers.
2. The carbon-coated aluminum foil according to claim 1, wherein the bonded microspheres have a core-shell structure with a shell softening point of 60-80 ℃ and a core softening point of 120-200 ℃.
3. The carbon-coated aluminum foil according to any one of claims 1-2, wherein the binding microspheres are formed by copolymerization of polyvinylidene fluoride and its copolymer, polyacrylate, polymethacrylate, polystyrene, and polyacrylonitrile.
4. A carbon coated aluminum foil according to claim 3 wherein said binding microspheres are formed by the mixed copolymerization of one or more of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene, polymethyl acrylate, polyethyl acrylate, polybutyl methacrylate, polymethyl methacrylate, polystyrene and polyacrylonitrile.
5. The carbon-coated aluminum foil according to claim 4, wherein the shell of the adhesive microsphere is composed of polybutylmethacrylate and one of polyacrylate or polymethyl methacrylate according to a weight ratio of 1 (1-10);
the inner core of the bonding microsphere is formed by copolymerizing one or more monomers of polystyrene, polyacrylonitrile, polyvinylidene fluoride-hexafluoropropylene and polymethyl methacrylate.
6. The carbon coated aluminum foil of any one of claims 1-5, wherein the bonded microspheres have a coverage of 10-80% and an average particle size of 3-5um.
7. The carbon-coated aluminum foil of claim 1, wherein the slurry of the conductive carbon layer is comprised of the following components in weight percent: 7.8-13.5% of conductive carbon powder, 0.2-1.5% of bonding microsphere and the balance of deionized water.
8. The method for preparing the carbon-coated aluminum foil as claimed in any one of claims 1 to 7, comprising the steps of:
s1, preparing slurry of a conductive carbon layer: sequentially adding conductive carbon powder and raw material emulsion of bonding microspheres into deionized water, and obtaining slurry of a conductive carbon layer after the raw material emulsion is uniformly dispersed;
s2, coating a conductive carbon layer: and (3) coating the slurry of the conductive carbon layer obtained in the step (S1) on two sides of the aluminum foil, and drying and solidifying the slurry to obtain the carbon-coated aluminum foil.
9. The use of the carbon-coated aluminum foil according to any one of claims 1 to 7, wherein the carbon-coated aluminum foil is coated with a positive electrode material;
the positive electrode material is one or more of lithium iron phosphate, lithium cobalt oxide and lithium nickel oxide.
10. The application of the carbon-coated aluminum foil according to claim 9, wherein the carbon-coated aluminum foil is coated and solidified with lithium iron phosphate, and the lithium iron phosphate slurry comprises the following components in proportion:
40-50% of lithium iron phosphate LFP, 1-3% of dispersing agent, 2-3% of conductive agent carbon black and binder PVDF:2-4% of NMP solvent and the balance.
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