CN112289980A - Pole piece and cleaning method thereof - Google Patents
Pole piece and cleaning method thereof Download PDFInfo
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- CN112289980A CN112289980A CN202011225078.5A CN202011225078A CN112289980A CN 112289980 A CN112289980 A CN 112289980A CN 202011225078 A CN202011225078 A CN 202011225078A CN 112289980 A CN112289980 A CN 112289980A
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- pole piece
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- 238000000034 method Methods 0.000 title claims abstract description 51
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- 239000000758 substrate Substances 0.000 claims abstract description 45
- 238000010438 heat treatment Methods 0.000 claims abstract description 30
- 238000000576 coating method Methods 0.000 claims abstract description 28
- 239000011248 coating agent Substances 0.000 claims abstract description 26
- 239000002002 slurry Substances 0.000 claims abstract description 24
- 239000000463 material Substances 0.000 claims description 25
- -1 polytetrafluoroethylene Polymers 0.000 claims description 10
- 239000011230 binding agent Substances 0.000 claims description 9
- 239000006258 conductive agent Substances 0.000 claims description 9
- 229920000098 polyolefin Polymers 0.000 claims description 9
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 5
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 5
- 239000004814 polyurethane Substances 0.000 claims description 5
- 229920002635 polyurethane Polymers 0.000 claims description 5
- 239000011149 active material Substances 0.000 claims description 2
- 239000002861 polymer material Substances 0.000 abstract description 5
- 230000003670 easy-to-clean Effects 0.000 abstract description 4
- 239000010410 layer Substances 0.000 description 107
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 9
- 229910001416 lithium ion Inorganic materials 0.000 description 9
- 238000002360 preparation method Methods 0.000 description 9
- 229910052782 aluminium Inorganic materials 0.000 description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 8
- 238000010586 diagram Methods 0.000 description 8
- 239000011888 foil Substances 0.000 description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 7
- 238000001035 drying Methods 0.000 description 6
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 5
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 5
- 230000002209 hydrophobic effect Effects 0.000 description 5
- 229910052744 lithium Inorganic materials 0.000 description 5
- 238000003466 welding Methods 0.000 description 5
- 239000002033 PVDF binder Substances 0.000 description 4
- 239000006230 acetylene black Substances 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 229920000915 polyvinyl chloride Polymers 0.000 description 4
- 239000004800 polyvinyl chloride Substances 0.000 description 4
- 239000000853 adhesive Substances 0.000 description 3
- 230000001070 adhesive effect Effects 0.000 description 3
- 239000012790 adhesive layer Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000002156 mixing Methods 0.000 description 3
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 3
- 239000007774 positive electrode material Substances 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 229920000049 Carbon (fiber) Polymers 0.000 description 2
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 2
- 239000004743 Polypropylene Substances 0.000 description 2
- 239000004372 Polyvinyl alcohol Substances 0.000 description 2
- 239000013543 active substance Substances 0.000 description 2
- 229910021383 artificial graphite Inorganic materials 0.000 description 2
- 239000004917 carbon fiber Substances 0.000 description 2
- 239000001768 carboxy methyl cellulose Substances 0.000 description 2
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 2
- 239000005466 carboxylated polyvinylchloride Substances 0.000 description 2
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 229910021389 graphene Inorganic materials 0.000 description 2
- 239000003273 ketjen black Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000007773 negative electrode material Substances 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- 229920001155 polypropylene Polymers 0.000 description 2
- 229920002451 polyvinyl alcohol Polymers 0.000 description 2
- 229920002620 polyvinyl fluoride Polymers 0.000 description 2
- 229920000973 polyvinylchloride carboxylated Polymers 0.000 description 2
- 229920000036 polyvinylpyrrolidone Polymers 0.000 description 2
- 239000001267 polyvinylpyrrolidone Substances 0.000 description 2
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 238000005406 washing Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical group [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229920002153 Hydroxypropyl cellulose Polymers 0.000 description 1
- 239000004962 Polyamide-imide Substances 0.000 description 1
- KLARSDUHONHPRF-UHFFFAOYSA-N [Li].[Mn] Chemical compound [Li].[Mn] KLARSDUHONHPRF-UHFFFAOYSA-N 0.000 description 1
- KFDQGLPGKXUTMZ-UHFFFAOYSA-N [Mn].[Co].[Ni] Chemical compound [Mn].[Co].[Ni] KFDQGLPGKXUTMZ-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000011889 copper foil Substances 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 229920005994 diacetyl cellulose Polymers 0.000 description 1
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 239000011267 electrode slurry Substances 0.000 description 1
- 229910021385 hard carbon Inorganic materials 0.000 description 1
- 239000001863 hydroxypropyl cellulose Substances 0.000 description 1
- 235000010977 hydroxypropyl cellulose Nutrition 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- BDKWOJYFHXPPPT-UHFFFAOYSA-N lithium dioxido(dioxo)manganese nickel(2+) Chemical compound [Mn](=O)(=O)([O-])[O-].[Ni+2].[Li+] BDKWOJYFHXPPPT-UHFFFAOYSA-N 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
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000002905 metal composite material Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910021382 natural graphite Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 229920001495 poly(sodium acrylate) polymer Polymers 0.000 description 1
- 229920002312 polyamide-imide Polymers 0.000 description 1
- 235000019422 polyvinyl alcohol Nutrition 0.000 description 1
- 238000003672 processing method Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- NNMHYFLPFNGQFZ-UHFFFAOYSA-M sodium polyacrylate Chemical compound [Na+].[O-]C(=O)C=C NNMHYFLPFNGQFZ-UHFFFAOYSA-M 0.000 description 1
- 229910021384 soft carbon Inorganic materials 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 238000009461 vacuum packaging Methods 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Images
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
- H01M4/13—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
- 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)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention provides a pole piece and a cleaning method thereof. The invention provides a pole piece cleaning method in a first aspect, which comprises the following steps: coating a polymer which has thermal shrinkage or hydrophobicity and is decomposed by heating on the surface of the pole piece substrate in an area to be cleaned to obtain a cleaning layer; coating the active layer slurry; and carrying out heat treatment to remove the cleaning layer and obtain the active layer with blank areas. According to the pole piece cleaning method provided by the invention, the polymer with specific properties is coated in the to-be-cleaned area on the surface of the pole piece substrate, so that the active layer in the to-be-cleaned area can be effectively cleaned, and the polymer material used for the cleaning layer is easy to clean, cannot remain on the surface of the pole piece substrate, and cannot cause any influence on the use of the pole piece.
Description
Technical Field
The invention relates to a pole piece and a cleaning method thereof, relating to the technical field of lithium ion batteries.
Background
The fast charge is one of the current lithium ion battery development directions, wherein the connection position of the tab has a great influence on the fast charge performance of lithium ions. At present, the connection position of a tab is adjusted from the edge of a pole piece to the middle part of the side surface of the pole piece so as to improve the quick charging performance of a lithium ion battery.
Because the tab is connected with the pole piece substrate, the active layer arranged on the surface of the pole piece substrate needs to have a partial blank area so as to be convenient for the connection of the tab and the pole piece substrate. The blank area is usually set by adopting two methods of jump coating and pole piece cleaning, but in practical application, the jump coating method has many problems of low production efficiency, edge thinning and the like, so that pole piece cleaning is a common preparation method at present, and more attention is paid to how to efficiently and conveniently clean pole pieces.
Disclosure of Invention
The invention provides a pole piece cleaning method which is used for improving the cleaning effect of a pole piece.
The invention also provides a pole piece cleaned according to the cleaning method, no active layer residue exists in the area to be cleaned of the pole piece, and the welding tension between the pole lug and the pole piece base material is improved.
The invention provides a pole piece cleaning method in a first aspect, which comprises the following steps:
coating a polymer which has thermal shrinkage or hydrophobicity and is decomposed by heating on the surface of the pole piece substrate in an area to be cleaned to obtain a cleaning layer;
coating the active layer slurry;
carrying out heat treatment, removing the cleaning layer and obtaining an active layer with a blank area;
the area to be cleaned refers to the area on the surface of the pole piece base material for connecting the pole lug.
Further, the heat-shrinkable polymer has a heat-shrinkable temperature of 60-180 ℃ and a shrinkage ratio of not less than 10%.
Further, the polymer with the heat-shrinkable property is PET and/or polyolefin polymer.
Further, the polyolefin polymer is PVC.
Further, the polymer which has hydrophobicity and is decomposed by heat is one or more of polyurethane and polytetrafluoroethylene polymer.
Further, the thickness of the cleaning layer is 10-100 μm.
Further, the temperature of the heat treatment is 80-150 ℃.
Further, the pole piece substrate is a current collector.
Further, the active layer slurry includes an active material, a conductive agent, and a binder.
The invention provides a pole piece in a second aspect, which is prepared by any one of the methods.
The implementation of the invention has at least the following advantages:
1. the invention provides a pole piece cleaning method, which can effectively clean an active layer in a region to be cleaned in a pole piece substrate by coating a polymer with specific properties in the region to be cleaned on the surface of the pole piece substrate, and the polymer material used by the cleaning layer is easy to clean, can not remain on the surface of the pole piece substrate, and can not cause any influence on the use of the pole piece.
2. The pole piece prepared by the pole piece cleaning method provided by the invention has less active layers remained on the surface of the pole piece, and effectively improves the welding tension of the pole lug and the pole piece substrate.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a flowchart of a pole piece cleaning method according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of the cleaning layer obtained in step 1 according to an embodiment of the present invention;
FIG. 3 is a schematic structural diagram of the active layer obtained in step 2 according to an embodiment of the present invention;
FIG. 4 is a schematic structural diagram of an active layer obtained in step 2 according to another embodiment of the present invention;
fig. 5 is a schematic structural diagram of the pole piece obtained in step 3 in an embodiment of the present invention.
Description of reference numerals:
1-pole piece base material;
2-cleaning the layer;
3-active layer.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a pole piece cleaning method in a first aspect, which comprises the following steps:
coating a polymer which has thermal shrinkage or hydrophobicity and is decomposed by heating on the surface of the pole piece substrate in an area to be cleaned to obtain a cleaning layer;
coating the active layer slurry;
carrying out heat treatment, removing the cleaning layer and obtaining an active layer with a blank area;
the area to be cleaned refers to the area on the surface of the pole piece base material for connecting the pole lug.
The invention provides a pole piece cleaning method, which is used for effectively cleaning a pole piece by coating a polymer material with certain properties in an area to be cleaned, and fig. 1 is a flow chart of the pole piece cleaning method provided by one embodiment of the invention, and as shown in fig. 1, the cleaning method comprises the following steps: firstly, determining a region to be cleaned according to the design of a pole piece, wherein the region to be cleaned is a region for connecting a pole lug on the surface of a pole piece substrate, an active layer is not arranged in the region, the pole lug is arranged in the region and connected with the pole piece substrate, and after the region to be cleaned is determined, selecting a polymer which has thermal shrinkage or hydrophobicity and is decomposed by heating, and coating the polymer in the region to be cleaned on the surface of the pole piece substrate to obtain a cleaning layer; secondly, coating active layer slurry according to a conventional technical means, and finally carrying out heat treatment, wherein in the heat treatment process, for a polymer with heat shrinkage, the polymer is subjected to heat shrinkage in the heat treatment process, so that the adhesive force between the polymer and a pole piece substrate is reduced, and the cleaning layer and the active layer on the surface of the cleaning layer fall off from the surface of the pole piece substrate together to complete the cleaning of the pole piece; for the polymer which has hydrophobicity and is decomposed by heating, because the slurry of the active layer is a polar substance and is not easy to adhere to the surface of the cleaning layer, the region to be cleaned only comprises the cleaning layer, and in the subsequent heat treatment process, the polymer is decomposed by heating, so that the cleaning of the pole piece is completed; after the pole piece is cleaned, a person skilled in the art can arrange the pole lug in the area and connect the pole lug with the pole piece substrate according to a conventional technical means to obtain a final pole piece. The invention provides a pole piece cleaning method, which can effectively clean an active layer in a region to be cleaned on the surface of a pole piece substrate by coating a polymer with specific properties in the region to be cleaned, and the polymer material used for the cleaning layer is easy to clean, can not remain on the surface of the pole piece substrate, and can not cause any influence on the use of the pole piece.
The cleaning method provided by the present invention is explained in detail below:
firstly, the skilled person determines the connection position of the tab in combination with the actual production and preparation requirements, and determines the region to be cleaned on the pole piece according to the connection position of the tab, for example, when the tab is connected to the middle position of the side surface of the pole piece, that is, a groove is arranged in the middle of the side surface of the active layer, the top view of the active layer is in a shape like a Chinese character 'ao', the tab is arranged at the groove and connected with the pole piece substrate, and the corresponding region of the groove on the pole piece substrate is the region to be cleaned.
Secondly, a polymer is selected which has heat-shrinkable properties, or which is hydrophobic and thermally decomposes, in particular: when the polymer has thermal shrinkage, the polymer is heated to shrink, and the polymer with the thermal shrinkage temperature of 60-180 ℃ and the shrinkage ratio of more than or equal to 10 percent can be selected by combining the drying temperature in the preparation process of the pole piece at present, namely the polymer can generate the thermal shrinkage phenomenon at 60-180 ℃, and the shrinkage ratio of more than or equal to 10 percent.
Further, the polymer with the heat-shrinkable property is PET and/or polyolefin polymer.
One skilled in the art can select PET or polyolefin polymer, or can select a mixture of PET and polyolefin polymer, and further, the polyolefin polymer is PVC.
When a mixture of PET and polyolefin-based polymer is selected, the present invention does not further limit the mixing ratio of the two.
When the polymer is hydrophobic and is decomposed by heat, the polymer is a nonpolar molecule, is not easy to dissolve in water and is decomposed by heat, and specifically, the polymer which is hydrophobic and is decomposed by heat is one or more of polyurethane polymers and polytetrafluoroethylene polymers.
Finally, coating a proper polymer on a to-be-cleaned area on the surface of the pole piece substrate to obtain a cleaning layer, wherein when the polymer has hydrophobicity and is decomposed by heat, the polymer can be directly coated on the to-be-cleaned area on the surface of the pole piece substrate, in order to improve the bonding force between the polymer and the pole piece substrate, the polymer can also be coated on the surface of the pole piece substrate by using an adhesive layer, and in order to facilitate subsequent removal of the adhesive layer, the adhesive layer can be the polymer with the thermal shrinkage property, so that in order to improve the cleaning efficiency of the pole piece, the polymer with the thermal shrinkage property is usually used in the actual preparation.
In the coating process, the applicant researches and discovers that the cleaning layer is not beneficial to cleaning the pole piece if the thickness of the cleaning layer is too high, and the thickness of the cleaning layer is 10-100 mu m in order to further improve the cleaning effect of the pole piece.
Through the above steps, a pole piece substrate and a cleaning layer arranged on the surface of the pole piece substrate can be obtained, fig. 2 is a schematic structural diagram of the cleaning layer obtained in step 1 in an embodiment of the present invention, as shown in fig. 2, a cleaning layer 2 is arranged in a corresponding area on the surface of the pole piece substrate 1, and the position of the cleaning layer 2 is an area to be cleaned.
first, the application of the slurry for the active layer can be performed according to the prior art, but due to the difference in the materials used for the washing layer, there is a difference in the application effect of the active layer:
in one embodiment, when the polymer has thermal shrinkage, the active layer slurry covers the surface of the cleaning layer during the process of coating the active layer slurry, fig. 3 is a schematic structural diagram of the active layer obtained in step 2 according to an embodiment of the present invention, and as shown in fig. 3, when the polymer has thermal shrinkage, the active layer 3 is disposed on the upper surfaces of the pole piece substrate 1 and the cleaning layer 2.
In another embodiment, when the polymer is hydrophobic and is decomposed by heat, during the process of coating the active layer slurry, since the polymer is hydrophobic and the substance used for the active layer is usually polar molecules, the active layer cannot be attached to the surface of the cleaning layer, so that the active layer can only be disposed on the surface of the pole piece substrate, i.e. the corresponding area of the active layer to the cleaning layer is a blank area. Fig. 4 is a schematic structural diagram of the active layer obtained in step 2 in another embodiment of the present invention, as shown in fig. 4, when the cleaning layer includes a polymer that has hydrophobicity and is decomposed by heat, the active layer 3 cannot be attached to the surface of the cleaning layer 2, so that the active layer 3 is only disposed on the surface of the pole piece substrate 1, and a corresponding area on the active layer 3 and the cleaning layer 2 is a blank area.
And 3, carrying out heat treatment to remove the cleaning layer and obtain an active layer with a blank area:
because the polymer that the cleaning layer used is all heat-resistant, consequently can clear away the polymer through heat treatment, accomplish the washing of pole piece, because the material that the cleaning layer used is different, there is the difference in the clearance process too:
when the polymer has thermal shrinkage, the polymer is sensitive to temperature change and shrinks when being heated, in the heat treatment process, the polymer shrinks, so that the adhesive force between the polymer and the pole piece substrate is reduced, the polymer is separated from the pole piece substrate, the active layer on the surface of the cleaning layer is separated from the active layer on the surface of the pole piece substrate, after the heat treatment is finished, the cleaning area can be swept by combining a tuyere or a brush, the cleaning layer 2 and the active layer 3 in the cleaning area are thoroughly removed, and the cleaning of the pole piece is finished.
When the polymer has hydrophobicity and is decomposed by heating, the slurry of the active layer can not be attached to the surface of the cleaning layer, so that the polymer in the region to be cleaned is decomposed by heating in the heat treatment process, and the cleaning of the pole piece can be completed.
In a specific preparation process, since the drying treatment is required after the active layer slurry is coated, the drying treatment and the heat treatment can be combined, and the heat treatment temperature can be properly lower than the heating temperature of the polymer for protecting other materials of the pole piece, specifically, the heat treatment temperature is 80-150 ℃.
When the polymer has thermal shrinkage, the heat treatment process can be finished when the shrinkage rate of the polymer is more than or equal to 30 percent;
when the polymer has hydrophobicity and is decomposed by heat, the polymer can be decomposed in 1 to 20 min.
Through the above steps, the cleaning layer and the active layer in the region to be cleaned can be effectively removed to complete the cleaning of the pole piece, fig. 5 is a schematic structural diagram of the pole piece obtained in step 3 in an embodiment of the present invention, as shown in fig. 5, the pole piece includes a pole piece substrate 1 and an active layer 3, and the pole piece includes a blank region for the subsequent connection of the tab.
It is understood that fig. 2-5 are only used to illustrate the cleaning method of the pole piece, the structure of the cleaning layer is emphasized, and fig. 2-5 do not show the actual structure of the pole piece.
After the pole piece is cleaned, according to the prior art, the pole lugs are arranged in the blank area obtained by cleaning and connected with the pole piece base material, and the final pole piece is obtained.
The pole piece cleaning method provided by the invention is suitable for the positive pole piece and the negative pole piece, and a person skilled in the art can select the material of the base material and the active layer of the pole piece according to the actual preparation requirement:
wherein, the pole piece base material can be a current collector, and when the pole piece is a positive pole piece, the pole piece base material is an aluminum foil; when the pole piece is a negative pole piece, the base material of the pole piece is copper foil.
The material of the active layer and the preparation method can adopt the conventional technical means in the prior art, for example, the active layer slurry generally comprises an active substance, a conductive agent and a binder, and the active layer slurry is coated on the surface of the pole piece substrate to obtain the active layer.
When the pole piece is a positive pole piece, the positive active material can be selected from one or more than two of the existing metal composite oxides of lithium, cobalt, manganese, nickel and the combination thereof. For example, the composite oxide includes lithium cobaltate, lithium nickelate, lithium manganate, nickel cobalt manganese ternary material, nickel cobalt aluminum ternary material, lithium iron phosphate (LFP), lithium nickel manganate, lithium manganese rich-based material, and the like.
The binder may be selected from one or more of polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, polyethylene, polypropylene, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, ethylene oxide containing polymers, polyvinyl pyrrolidone, polyurethane.
The conductive agent can be one or more selected from carbon black, acetylene black, graphene, ketjen black and carbon fiber.
On the basis of selecting proper materials, dispersing a positive active substance, a binder and a conductive agent in a proper amount of N-methylpyrrolidone (NMP) solvent, fully stirring and mixing to form uniform positive slurry, and uniformly coating the positive slurry on a positive pole piece substrate.
When the electrode sheet is a negative electrode sheet, the negative active material may be selected from one or more of the existing carbon-containing materials, such as artificial graphite, hard carbon, soft carbon, and the like.
The conductive agent can be selected from one or more of natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber and graphene.
The binder may be selected from one or more of carboxymethyl cellulose, styrene-butadiene rubber, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamideimide, polyvinyl alcohol, sodium polyacrylate.
On the basis of selecting a proper active layer material, dispersing a negative active material, a conductive agent and a binder in a proper amount of deionized water, and fully stirring and mixing to form uniform negative slurry; and uniformly coating the negative electrode slurry on the negative electrode pole piece base material.
The present invention is not limited to the selection of the materials for the positive electrode and the negative electrode, and may be materials commonly used in lithium ion batteries at present, and is not limited to the materials.
In summary, the invention provides a pole piece cleaning method, which can effectively clean an active layer in a region to be cleaned in the surface of a pole piece substrate by coating a polymer with specific properties in the region to be cleaned, and the polymer material used in the cleaning layer is easy to clean, does not remain on the surface of the pole piece substrate, and does not affect the use of the pole piece.
The invention provides a pole piece in a second aspect, which is prepared by any one of the methods.
The invention provides a pole piece, and on the basis of the pole piece cleaning method provided by the invention, the pole piece can be obtained by arranging a lug in a blank area obtained by cleaning. The pole piece prepared by the pole piece cleaning method provided by the invention has less active layers remained on the surface of the pole piece, and effectively improves the welding tension of the pole lug and the pole piece substrate.
The third aspect of the invention provides a lithium ion battery, which comprises the pole piece prepared by any one of the preparation methods.
The third aspect of the invention provides a lithium ion battery, on the basis of the pole piece prepared by the pole piece cleaning method provided by the invention, the lithium ion battery can be prepared by matching a diaphragm and an electrolyte according to the existing preparation method, for example, a positive pole, a diaphragm and a negative pole are sequentially stacked, the diaphragm is positioned between the positive pole and the negative pole to play a role of isolation, then winding is carried out to obtain a naked electric core, the naked electric core is placed in an outer packaging shell, the electrolyte is injected after drying, and the lithium ion battery is prepared by the working procedures of vacuum packaging, standing, formation, shaping and the like.
The following description is given with reference to specific examples:
example 1
Comparative example 1
and 2, cleaning the active layer in the area to be cleaned by adopting a laser processing method to complete the cleaning of the pole piece.
The invention further produces a certain amount of positive plates according to the methods provided by the embodiment 1 and the comparative example 1, and measures the residual rate of the active layer in the area to be cleaned, the breakage rate of the positive plates and the like, and the measurement results are shown in the table 1:
wherein the residue rate is detected by a CCD camera, and the residue judgment standard is more than 0.5mm2；
The breakage rate is detected by a CCD camera, and the breakage judgment standard is more than 0.5mm2；
The welding tension is tested by a manual tension meter;
and (4) calculating to obtain the yield of the pole piece by adopting (total production quantity-residual quantity-damaged quantity)/total production quantity according to the residual rate and the damaged quantity.
Table 1 cleaning efficiency test results of the pole piece cleaning methods provided in example 1 and comparative example 1
From the test results provided in table 1, the pole piece obtained by cleaning according to the pole piece cleaning method provided in the present application has a surface residue and breakage rate significantly lower than that of comparative example 1, and a welding tension and a product yield higher than that of comparative example 1, which indicates that the cleaning method provided in the present application can effectively improve the cleaning efficiency of the pole piece.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. A pole piece cleaning method is characterized by comprising the following steps:
coating a polymer which has thermal shrinkage or hydrophobicity and is decomposed by heating on the surface of the pole piece substrate in an area to be cleaned to obtain a cleaning layer;
coating the active layer slurry;
carrying out heat treatment, removing the cleaning layer and obtaining an active layer with a blank area;
the area to be cleaned refers to the area on the surface of the pole piece base material for connecting the pole lug.
2. The method according to claim 1, wherein the polymer having heat-shrinkable property has a heat-shrinking temperature of 60 to 180 ℃ and a shrinkage ratio of not less than 10%.
3. Method according to claim 1 or 2, characterized in that the polymer with heat-shrinking properties is PET and/or a polyolefin-based polymer.
4. The method of claim 3, wherein the polyolefin-based polymer is PVC.
5. The method according to claim 1, wherein the polymer which has hydrophobicity and is decomposed by heat is one or more of polyurethane and polytetrafluoroethylene polymer.
6. The method according to any one of claims 1 to 5, wherein the thickness of the cleaning layer is 10 to 100 μm.
7. The method according to any one of claims 1 to 6, wherein the temperature of the heat treatment is 80 to 150 ℃.
8. The method of claim 1, wherein the pole piece substrate is a current collector.
9. The method of claim 1, wherein the active layer slurry comprises an active material, a conductive agent, and a binder.
10. A pole piece prepared according to the method of any one of claims 1 to 9.
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Application publication date: 20210129 |