CN114709363A - Dry-process pole piece and preparation method thereof - Google Patents
Dry-process pole piece and preparation method thereof Download PDFInfo
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- CN114709363A CN114709363A CN202210476317.7A CN202210476317A CN114709363A CN 114709363 A CN114709363 A CN 114709363A CN 202210476317 A CN202210476317 A CN 202210476317A CN 114709363 A CN114709363 A CN 114709363A
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- 238000001035 drying Methods 0.000 title claims abstract description 41
- 238000002360 preparation method Methods 0.000 title claims abstract description 18
- 239000007772 electrode material Substances 0.000 claims abstract description 192
- 239000011149 active material Substances 0.000 claims abstract description 63
- 239000002245 particle Substances 0.000 claims abstract description 57
- 238000000034 method Methods 0.000 claims abstract description 27
- 239000002131 composite material Substances 0.000 claims abstract description 13
- 239000010410 layer Substances 0.000 claims description 170
- 239000000203 mixture Substances 0.000 claims description 42
- 239000006258 conductive agent Substances 0.000 claims description 35
- 239000011230 binding agent Substances 0.000 claims description 30
- 239000000853 adhesive Substances 0.000 claims description 24
- 230000001070 adhesive effect Effects 0.000 claims description 24
- 238000007590 electrostatic spraying Methods 0.000 claims description 22
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 18
- 239000012790 adhesive layer Substances 0.000 claims description 15
- 239000002033 PVDF binder Substances 0.000 claims description 12
- 239000011248 coating agent Substances 0.000 claims description 12
- 238000000576 coating method Methods 0.000 claims description 12
- 238000005098 hot rolling Methods 0.000 claims description 12
- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 12
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 10
- 229910002804 graphite Inorganic materials 0.000 claims description 7
- 239000010439 graphite Substances 0.000 claims description 7
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 claims description 7
- 239000007773 negative electrode material Substances 0.000 claims description 6
- 239000007774 positive electrode material Substances 0.000 claims description 6
- 239000006230 acetylene black Substances 0.000 claims description 5
- 229920000663 Hydroxyethyl cellulose Polymers 0.000 claims description 3
- 239000004354 Hydroxyethyl cellulose Substances 0.000 claims description 3
- 229910000572 Lithium Nickel Cobalt Manganese Oxide (NCM) Inorganic materials 0.000 claims description 3
- HMDDXIMCDZRSNE-UHFFFAOYSA-N [C].[Si] Chemical compound [C].[Si] HMDDXIMCDZRSNE-UHFFFAOYSA-N 0.000 claims description 3
- FBDMTTNVIIVBKI-UHFFFAOYSA-N [O-2].[Mn+2].[Co+2].[Ni+2].[Li+] Chemical compound [O-2].[Mn+2].[Co+2].[Ni+2].[Li+] FBDMTTNVIIVBKI-UHFFFAOYSA-N 0.000 claims description 3
- 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 claims description 3
- 239000002041 carbon nanotube Substances 0.000 claims description 3
- 229910021393 carbon nanotube Inorganic materials 0.000 claims description 3
- 239000001768 carboxy methyl cellulose Substances 0.000 claims description 3
- 229910021389 graphene Inorganic materials 0.000 claims description 3
- 229910021385 hard carbon Inorganic materials 0.000 claims description 3
- 235000019447 hydroxyethyl cellulose Nutrition 0.000 claims description 3
- 229910000625 lithium cobalt oxide Inorganic materials 0.000 claims description 3
- BFZPBUKRYWOWDV-UHFFFAOYSA-N lithium;oxido(oxo)cobalt Chemical compound [Li+].[O-][Co]=O BFZPBUKRYWOWDV-UHFFFAOYSA-N 0.000 claims description 3
- -1 polytetrafluoroethylene Polymers 0.000 claims description 3
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 3
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 3
- 235000019812 sodium carboxymethyl cellulose Nutrition 0.000 claims description 3
- 229920001027 sodium carboxymethylcellulose Polymers 0.000 claims description 3
- 239000000463 material Substances 0.000 abstract description 14
- 238000005056 compaction Methods 0.000 abstract description 9
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 abstract description 2
- 229910052744 lithium Inorganic materials 0.000 abstract description 2
- 238000002156 mixing Methods 0.000 description 11
- 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 10
- 239000000843 powder Substances 0.000 description 9
- 238000005507 spraying Methods 0.000 description 9
- 238000005096 rolling process Methods 0.000 description 6
- 239000002904 solvent Substances 0.000 description 3
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 2
- 239000013543 active substance Substances 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 229910001416 lithium ion Inorganic materials 0.000 description 2
- 239000003960 organic solvent Substances 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000003446 memory effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000004537 pulping Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
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- 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
-
- 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)
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- Materials Engineering (AREA)
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- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention relates to the technical field of lithium batteries, in particular to a dry-method pole piece and a preparation method thereof. The dry-process pole piece comprises a current collector and a composite layer. The composite bed is including the multilayer electrode material layer of range upon range of setting, and the two-layer that is closest to the mass flow body among the multilayer electrode material layer is first electrode material layer and second electrode material layer respectively, and wherein first electrode material layer coats in one side of the mass flow body, and the second electrode material layer coats in one side that the mass flow body was kept away from to first electrode material layer, and the active material particle diameter in the first electrode material layer is greater than the second electrode material layer. The dry-process pole piece provided by the invention can balance the particle size ratio of the active material. When the dry-method pole piece is compressed, the active materials on different layers are arranged at adjacent positions, and interpenetration compaction of large-particle-size particles and small-particle-size particles can be realized, so that the compaction degree between different material layers can be improved.
Description
Technical Field
The invention relates to the technical field of lithium batteries, in particular to a dry-method pole piece and a preparation method thereof.
Background
With the improvement of global energy shortage and environmental protection consciousness, the development of new energy becomes the most important research direction in the current energy field, and the lithium ion battery as a green energy storage device has the advantages of high working voltage, no memory effect, small self-discharge, long cycle life and the like, gradually becomes a development hotspot of the energy industry, and is widely applied to various electronic products.
At present, the electrode of a commercial lithium ion battery finally obtains a positive pole piece and a negative pole piece with proper thickness through a series of steps of material mixing, homogenate, coating, drying, rolling and the like, but a large amount of solvents are required to be used in the homogenate process, for example: NMP, deionized water, etc., wherein NMP is expensive and toxic, and then the solvent is dried and removed by a drying process, which results in a great waste of energy.
Compared with the traditional wet pulping method, the dry electrode technology does not use any solvent in the preparation process of the pole piece, the pole piece can be prepared only by mixing dry powder, the preparation process is environment-friendly and pollution-free, and the production cost of the battery can be reduced to a great extent. However, the dry-method electrode is prone to have the situation that the powder in the electrode sheet is unevenly distributed in the preparation process, and the problems of large charge transfer resistance, large ion diffusion resistance, obvious expansion effect and the like are prone to occur due to the fact that the electrode material layer of the dry-method electrode is thick.
Disclosure of Invention
The invention provides a dry-method pole piece and a preparation method thereof, which are used for solving the problems that in the prior art, a dry-method electrode has large charge transfer resistance and obvious expansion effect, and the uneven distribution of powder in the pole piece is easy to occur, and the like, and achieving the purposes of obviously reducing the expansion of the pole piece and solving the problem of powder falling.
The invention provides a dry-process pole piece, which comprises the following steps:
a current collector;
the composite bed, the composite bed is including the multilayer electrode material layer that stacks up the setting, and the multilayer is the closest in the electrode material layer two-layer of mass flow body is first electrode material layer and second electrode material layer respectively, wherein first electrode material layer coat in one side of the mass flow body, second electrode material layer coat in first electrode material layer keeps away from one side of the mass flow body, active material particle diameter in the first electrode material layer is greater than the second electrode material layer.
According to the dry electrode piece provided by the invention, in any two adjacent electrode material layers, the minimum particle size of the active material in the electrode material layer close to the current collector is larger than the maximum particle size of the active material in the electrode material layer far away from the current collector.
According to the dry electrode piece provided by the invention, the thickness of the first electrode material layer is smaller than that of the second electrode material layer.
According to the dry pole piece provided by the invention, the thickness of the first electrode material layer is 10-50 μm, and the thickness of the second electrode material layer is 50-200 μm.
According to the dry-process pole piece provided by the invention, the first electrode material layer comprises a first active material, a first conductive agent and a first binder;
the second electrode material layer includes a second active material, a second conductive agent, and a second binder.
According to the dry-method pole piece provided by the invention, the first active material and the second active material are positive active materials, and the positive active material is lithium iron phosphate or lithium nickel cobalt manganese oxide or lithium cobalt oxide;
or the first active material and the second active material are negative active materials, and the negative active materials are graphite, silicon carbon or hard carbon.
According to the dry-method pole piece provided by the invention, the first conductive agent and the second conductive agent are conductive carbon black or acetylene black or carbon nano tubes or graphene;
the first binder and the second binder are polytetrafluoroethylene or sodium carboxymethylcellulose or polyvinylidene fluoride or hydroxyethyl cellulose.
According to the dry electrode piece provided by the invention, in the first electrode material layer, the weight percentage of the first active material is 60-99%, the weight percentage of the first conductive agent is 0.1-10%, and the weight percentage of the first binder is 1-10%.
According to the dry electrode piece provided by the invention, in the second electrode material layer, the weight proportion of the second active material is 60-99%, the weight proportion of the second conductive agent is 5-20%, and the weight proportion of the second binder is 1-10%.
According to the dry electrode piece provided by the invention, in the first electrode material layer, the weight ratio of the first conductive agent is a;
and in the second electrode material layer, the weight ratio of the second conductive agent is b, wherein a is less than b.
According to the dry-process pole piece provided by the invention, in the first electrode material layer, the particle size of the first active material is 1-30 μm;
in the second electrode material layer, the particle diameter of the second active material is 0.1 μm to 20 μm.
The dry-method pole piece further comprises a conductive adhesive layer, wherein the conductive adhesive layer is coated on one side surface of the current collector, and the conductive adhesive layer is located between the current collector and the composite layer.
According to the dry-process pole piece provided by the invention, the conductive adhesive layer is constructed by conductive adhesive, the conductive adhesive is a mixture of a binder and a conductive agent, and the thickness of the conductive adhesive layer is 0.5-10 μm.
The invention also provides a preparation method of the dry-process pole piece, wherein the dry-process pole piece is the dry-process pole piece, and the preparation method comprises the following steps:
the method comprises the steps of obtaining a first electrode material mixture containing a first active material, a first conductive agent and a first binder, and coating the first electrode material mixture on the surface of a current collector in an electrostatic spraying manner to obtain a first electrode material layer;
obtaining a second electrode material mixture containing a second active material, a second conductive agent and a second binder, and coating the second electrode material mixture on one side, away from the current collector, of the first electrode material layer in an electrostatic spraying manner to obtain a second electrode material layer;
and carrying out hot rolling on the current collector sprayed with the first electrode material layer and the second electrode material layer to obtain the dry-process pole piece.
According to the preparation method of the dry electrode piece provided by the invention, in the step of obtaining the first electrode material mixture containing the first active material, the first conductive agent and the first binder, coating the first electrode material mixture on the surface of the current collector in an electrostatic spraying manner to obtain the first electrode material layer,
coating conductive adhesive on the surface of the current collector, and coating the first electrode material mixture on the conductive adhesive in an electrostatic spraying manner.
According to the dry-method pole piece provided by the invention, the particle size of the active material in the first electrode material layer is larger than that of the active material in the second electrode material layer, so that the particle size ratio of the active material can be balanced. When the dry-method pole piece is compressed, the active materials on different layers are arranged at adjacent positions, so that the interpenetration compaction of large-particle-size particles and small-particle-size particles can be realized, and the compaction degree among different material layers can be improved.
On the other hand, in the electrode material layers with different particle sizes, the large particle size is positioned on one side close to the current collector, and the small particle size is positioned on one side far away from the current collector, so that each layer of material can form a stacking structure on one side of the current collector, the large particle size and the small particle size are combined in a staggered mode, gaps among different layer materials can be reduced, a more compact network structure is favorably constructed, and the powder falling phenomenon is reduced.
Drawings
In order to more clearly illustrate the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the description of 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 other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a cross-sectional view of a dry-process pole piece provided by the present invention;
reference numerals:
100: dry-process pole pieces;
150: a current collector;
110: compounding layers; 120: a first electrode material layer;
130: a second electrode material layer; 140: and the conductive adhesive layer.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all 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 dry-process pole piece 100 of the present invention is described below in conjunction with fig. 1. The dry-process pole piece 100 may be an electrode piece made by a dry-process. In the related technology, in the preparation process of the wet pole piece, an organic solvent needs to be mixed into an active substance, so that environmental pollution is easily caused. In the preparation process of the dry-method pole piece 100, an organic solvent is not required to be mixed into the active substance.
Referring to fig. 1, the dry-process pole piece 100 includes a current collector 150 and a composite layer 110. It should be noted that the current collector 150 has a sheet shape, and the composite layer 110 is disposed on at least one of the two side surfaces of the current collector 150.
Specifically, the composite layer 110 includes a plurality of electrode material layers stacked, for example, the electrode material layers may be two layers, three layers, or four layers. Two layers of the multi-layered electrode material layer closest to the current collector 150 are a first electrode material layer 120 and a second electrode material layer 130, respectively, wherein the first electrode material layer 120 is coated on one side of the current collector 150, where the first electrode material layer 120 may be uniformly coated on the surface of the current collector 150. The second electrode material layer 130 is coated on the side of the first electrode material layer 120 away from the current collector 150, where the second electrode material layer 130 may be uniformly coated on the surface of the first electrode material layer 120 away from the current collector 150. That is, the first electrode material layer 120 and the second electrode material layer 130 are stacked on one side of the current collector 150. The particle size of the active material in the first electrode material layer 120 is larger than that in the second electrode material layer 130.
It should be noted that the particle size of the active material in the first electrode material layer 120 is larger than that of the active material in the second electrode material layer 130, so that the particle size ratio of the active material can be balanced. When the dry-method pole piece 100 is pressed, the active materials on different layers are arranged at adjacent positions, so that the interpenetration compaction of large-particle-size particles and small-particle-size particles can be realized, and the compaction degree among different material layers can be improved.
On the other hand, in the electrode material layers with different particle sizes, the large particle size is positioned on one side close to the current collector 150, and the small particle size is positioned on one side far away from the current collector 150, so that each layer of material can form a stacking structure on one side of the current collector 150, the large particle size and the small particle size are combined in a staggered mode, gaps among different layer materials can be reduced, a tighter network structure can be constructed, the powder falling phenomenon is reduced, the edge of the dry-method pole piece 100 is smoother, and the tear resistance is enhanced.
According to some embodiments of the present invention, in any two adjacent electrode material layers, the minimum particle diameter of the active material in the electrode material layer close to the current collector 150 is larger than the maximum particle diameter of the active material in the electrode material layer far from the current collector 150. Therefore, for the dry-process pole piece 100 with the multiple electrode material layers, the compression degree of the dry-process pole piece 100 can be well improved, and the technical defects of powder falling, tearing and the like of the dry-process pole piece 100 can be effectively overcome.
In some embodiments, the thickness of the first electrode material layer 120 is less than the thickness of the second electrode material layer 130. Therefore, the material layer with smaller thickness has better wrapping performance, can effectively improve the powder falling defect of the dry pole piece 100, and is beneficial to compressing the dry pole piece 100. In addition, it should be noted that the setting of different thicknesses can effectively suppress material expansion, and the combination of the thickness setting and the particle size setting can also effectively suppress material expansion, so that the dry electrode sheet 100 with a more compact structure and a higher density is easily obtained.
To further enhance the particle compaction of the dry-process pole piece 100, according to some embodiments of the present invention, the thickness of the first electrode material layer 120 is 10 μm to 50 μm and the thickness of the second electrode material layer 130 is 50 μm to 200 μm.
According to some embodiments of the present invention, the first electrode material layer 120 includes a first active material, a first conductive agent, and a first binder. The second electrode material layer 130 includes a second active material, a second conductive agent, and a second binder. Further, the first active material and the second active material are positive active materials, and the positive active materials are lithium iron phosphate or lithium nickel cobalt manganese oxide or lithium cobalt oxide; or the first active material and the second active material are negative active materials, and the negative active materials are graphite, silicon carbon or hard carbon.
In some embodiments, the first and second conductive agents are conductive carbon black or acetylene black or carbon nanotubes or graphene; the first binder and the second binder are polytetrafluoroethylene or sodium carboxymethylcellulose or polyvinylidene fluoride or hydroxyethyl cellulose.
According to some embodiments of the present invention, in the first electrode material layer 120, the weight ratio of the first active material is 60% to 99%, the weight ratio of the first conductive agent is 0.1% to 10%, and the weight ratio of the first binder is 1% to 10%. In some embodiments, the second active material may be 60 to 99% by weight, the second conductive agent may be 5 to 20% by weight, and the second binder may be 1 to 10% by weight in the second electrode material layer 130.
Further, in the first electrode material layer 120, the weight ratio of the first conductive agent is a; the second conductive agent in the second electrode material layer 130 has a weight ratio b, where a is smaller than b. Because the more away from the position of the current collector 150 the higher the requirement on the conductive adhesive, through setting up the conductive adhesive that contains different proportions, when promoting the degree of adhesion, can also arrange the conductive adhesive that viscosity is high selectively in the electrode material layer department of keeping away from the conductive adhesive, reach the purpose of reduce cost.
According to some embodiments of the present invention, in the first electrode material layer 120, the first active material has a particle size of 1 μm to 30 μm; in the second electrode material layer 130, the particle diameter of the second active material is 0.1 μm to 20 μm.
According to some embodiments of the present invention, the dry-process pole piece 100 may further include a conductive adhesive layer 140, the conductive adhesive layer 140 is coated on one side surface of the current collector 150, and the conductive adhesive layer 140 is located between the current collector 150 and the composite layer 110. In this way, the composite layer 110 can be stably bonded to the current collector 150, and thus the structural stability of the dry electrode sheet 100 can be improved. Further, the conductive adhesive layer 140 is formed by a conductive adhesive, the conductive adhesive is a mixture of a binder and a conductive agent, and the thickness of the conductive adhesive layer 140 is 0.5 μm to 10 μm.
According to the preparation method of the dry pole piece 100 of the embodiment of the invention, the dry pole piece 100 is the dry pole piece 100, and the preparation method comprises the following steps:
obtaining a first electrode material mixture containing a first active material, a first conductive agent and a first binder, and coating the first electrode material mixture on the surface of the current collector 150 by an electrostatic spraying manner to obtain a first electrode material layer 120;
obtaining a second electrode material mixture containing a second active material, a second conductive agent and a second binder, and coating the second electrode material mixture on the side, away from the current collector 150, of the first electrode material layer 120 in an electrostatic spraying manner to obtain a second electrode material layer 130;
and (3) carrying out hot rolling on the current collector 150 sprayed with the first electrode material layer 120 and the second electrode material layer 130 to obtain the dry-process pole piece 100.
According to the preparation method of the dry-process pole piece 100 provided by the embodiment of the invention, the particle size of the active material in the first electrode material layer is larger than that of the active material in the second electrode material layer, so that the particle size ratio of the active material can be balanced. When the dry-method pole piece is compressed, the active materials on different layers are arranged at adjacent positions, so that the interpenetration compaction of large-particle-size particles and small-particle-size particles can be realized, and the compaction degree among different material layers can be improved.
On the other hand, in the electrode material layers with different particle sizes, the large particle size is positioned on one side close to the current collector, and the small particle size is positioned on one side far away from the current collector, so that each layer of material can form a stacking structure on one side of the current collector, the large particle size and the small particle size are combined in a staggered mode, gaps among different layer materials can be reduced, a more compact network structure is favorably constructed, and the powder falling phenomenon is reduced.
In some embodiments, in the step of obtaining a first electrode material mixture including a first active material, a first conductive agent and a first binder, applying the first electrode material mixture to the surface of the current collector 150 by means of electrostatic spraying, to obtain the first electrode material layer 120,
the conductive adhesive is coated on the surface of the current collector 150, and then the first electrode material mixture is coated on the conductive adhesive in an electrostatic spraying manner. In this way, the first electrode material can be stably bonded to the current collector 150, and thus the structural stability of the dry electrode sheet 100 can be improved.
In some embodiments, the electrostatic spraying voltage is 10-100 kV, and the flow speed pressure is 0.1-5 MPa; the pressure of hot rolling is less than or equal to 50t, the width of a roll gap is less than or equal to 1000 mu m, and the rolling temperature is 50-200 ℃.
The method for preparing the dry-process pole piece according to the embodiment of the invention is described in detail by specific examples.
Example 1
The embodiment provides a method for preparing a dry electrode sheet 100, where the structure of the dry electrode sheet 100 is shown in fig. 1, and the method includes:
(1) mixing graphite, acetylene black and polyvinylidene fluoride according to the weight ratio of 93: 2: 5 to obtain a first electrode material mixture in which the particle diameter of graphite was 25 μm.
(2) And electrostatically spraying the first electrode material mixture on the surface of the current collector 150 coated with the conductive adhesive to obtain a first electrode material layer 120, wherein the thickness of the conductive adhesive is 0.5 mu m, the thickness of the first electrode material layer 120 is 20 mu m, the voltage of electrostatic spraying is 20kV, and the flow rate pressure is 3 MPa.
(3) Mixing graphite, acetylene black and polyvinylidene fluoride according to the weight ratio of 90: 5: 5 to obtain a second electrode material mixture in which the particle diameter of graphite is 15 μm.
(4) And electrostatically spraying a second electrode material mixture on the side, away from the current collector 150, of the first electrode material layer 120 to obtain a second electrode material layer 130, wherein the thickness of the second electrode material layer 130 is 60 μm, the voltage of electrostatic spraying is 20kV, and the flow rate pressure is 3 MPa.
(5) And (3) carrying out hot rolling on the current collector 150 sprayed with the first electrode material layer 120 and the second electrode material layer 130, wherein the pressure of the hot rolling is 10t, the width of a roll gap is 70 mu m, and the rolling temperature is 175 ℃, so as to obtain the dry electrode plate 100.
Example 2
The embodiment provides a method for preparing a dry-process pole piece 100, which comprises the following steps:
(1) mixing lithium iron phosphate, conductive carbon black and polyvinylidene fluoride according to the weight ratio of 90: 5: 5 to obtain a first electrode material mixture, wherein the particle size of the lithium iron phosphate is 3 mu m.
(2) And electrostatically spraying the first electrode material mixture on the surface of the current collector coated with the conductive adhesive to obtain a first electrode material layer 120, wherein the thickness of the conductive adhesive is 1 micrometer, the thickness of the first electrode material layer is 25 micrometers, the voltage of electrostatic spraying is 30kV, and the flow speed pressure is 5 MPa.
(3) Mixing lithium iron phosphate, conductive carbon black and polyvinylidene fluoride according to the weight ratio of 85: 10: 5 to obtain a second electrode material mixture, wherein the particle size of the lithium iron phosphate is 5 μm.
(4) And electrostatically spraying a second electrode material mixture on the side, away from the current collector 150, of the first electrode material layer 120 to obtain a second electrode material layer 130, wherein the thickness of the second electrode material layer 130 is 45 μm, the voltage of electrostatic spraying is 25kV, and the flow rate pressure is 5 MPa.
(5) And (3) carrying out hot rolling on the current collector 100 sprayed with the first electrode material layer 120 and the second electrode material layer 130, wherein the pressure of the hot rolling is 15t, the width of a roll gap is 50 micrometers, and the rolling temperature is 180 ℃, so as to obtain the dry electrode sheet 100.
Example 3
The embodiment provides a method for preparing a dry-process pole piece 100, which comprises the following steps:
(1) mixing nickel cobalt lithium manganate, conductive carbon black and polyvinylidene fluoride according to a ratio of 95: 2: 3 to obtain a first electrode material mixture, wherein the particle size of the nickel cobalt lithium manganate is 9 μm.
(2) And electrostatically spraying the first electrode material mixture on the surface of the current collector coated with the conductive adhesive to obtain a first electrode material layer 120, wherein the thickness of the conductive adhesive is 1 micrometer, the thickness of the first electrode material layer 120 is 30 micrometers, the voltage of electrostatic spraying is 25kV, and the flow speed pressure is 4 MPa.
(3) Mixing nickel cobalt lithium manganate, conductive carbon black and polyvinylidene fluoride according to the weight ratio of 90: 7: 3 to obtain a second electrode material mixture, wherein the particle size of the nickel cobalt lithium manganate is 12 μm.
(4) And electrostatically spraying a second electrode material mixture on the side, away from the current collector 150, of the first electrode material layer 120 to obtain a second electrode material layer 130, wherein the thickness of the second electrode material layer 130 is 60 μm, the voltage of electrostatic spraying is 25kV, and the flow rate pressure is 4 MPa.
(5) And (3) carrying out hot rolling on the current collector 150 sprayed with the first electrode material layer 120 and the second electrode material layer 130, wherein the pressure of the hot rolling is 12t, the width of a roll gap is 70 mu m, and the rolling temperature is 180 ℃, so as to obtain the dry-process pole piece 100.
Example 4
The embodiment provides a method for preparing a dry-process pole piece 100, which comprises the following steps:
(1) mixing nickel cobalt lithium manganate, conductive carbon black and polyvinylidene fluoride according to a ratio of 96: 1: 3 to obtain a first electrode material mixture, wherein the particle size of the nickel cobalt lithium manganate is 7 μm.
(2) And electrostatically spraying the first electrode material mixture on the surface of the current collector 150 coated with the conductive adhesive to obtain a first electrode material layer 120, wherein the thickness of the conductive adhesive is 1 micrometer, the thickness of the first electrode material layer is 20 micrometers, the voltage of electrostatic spraying is 25kV, and the flow rate pressure is 5 MPa.
(3) Mixing nickel cobalt lithium manganate, conductive carbon black and polyvinylidene fluoride according to a weight ratio of 92: 5: 3 to obtain a second electrode material mixture, wherein the particle size of the nickel cobalt lithium manganate is 9 μm.
(4) And electrostatically spraying a second electrode material mixture on the side, away from the current collector 150, of the first electrode material layer 120 to obtain a second electrode material layer 130, wherein the thickness of the second electrode material layer 130 is 50 μm, the voltage of electrostatic spraying is 25kV, and the flow rate pressure is 4 MPa.
(5) Mixing nickel cobalt lithium manganate, conductive carbon black and polyvinylidene fluoride according to the weight ratio of 90: 7: 3 to obtain a third electrode material mixture, wherein the particle size of the nickel cobalt lithium manganate is 12 μm.
(6) And electrostatically spraying a third electrode material mixture on the side, away from the first electrode material layer 120, of the second electrode material layer 130 to obtain a third electrode material layer, wherein the thickness of the third electrode material layer is 60 micrometers, the voltage of electrostatic spraying is 30kV, and the flow rate pressure is 5 MPa.
(5) And (3) carrying out hot rolling on the current collector 150 sprayed with the first electrode material layer 120, the second electrode material layer 130 and the third electrode material layer, wherein the pressure of the hot rolling is 15t, the width of a roll gap is 100 micrometers, and the rolling temperature is 180 ℃, so as to obtain the dry-process pole piece 100.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (15)
1. A dry-process pole piece, comprising:
a current collector;
the composite bed, the composite bed is including the multilayer electrode material layer that stacks up the setting, and the multilayer is the closest in the electrode material layer two-layer of mass flow body is first electrode material layer and second electrode material layer respectively, wherein first electrode material layer coat in one side of the mass flow body, second electrode material layer coat in first electrode material layer keeps away from one side of the mass flow body, active material particle diameter in the first electrode material layer is greater than the second electrode material layer.
2. The dry electrode sheet according to claim 1, wherein, in any two adjacent electrode material layers, the minimum particle size of the active material in the electrode material layer close to the current collector is larger than the maximum particle size of the active material in the electrode material layer far from the current collector.
3. The dry pole piece of claim 1, wherein the thickness of the first electrode material layer is less than the thickness of the second electrode material layer.
4. The dry pole piece according to claim 3, wherein the thickness of the first electrode material layer is 10 μm to 50 μm and the thickness of the second electrode material layer is 50 μm to 200 μm.
5. The dry pole piece of claim 1, wherein the first electrode material layer comprises a first active material, a first conductive agent, and a first binder;
the second electrode material layer includes a second active material, a second conductive agent, and a second binder.
6. The dry-process pole piece according to claim 5, wherein the first active material and the second active material are positive active materials, and the positive active materials are lithium iron phosphate or lithium nickel cobalt manganese oxide or lithium cobalt oxide;
or the first active material and the second active material are negative active materials, and the negative active materials are graphite, silicon carbon or hard carbon.
7. The dry-process pole piece according to claim 5, wherein the first conductive agent and the second conductive agent are conductive carbon black or acetylene black or carbon nanotubes or graphene;
the first binder and the second binder are polytetrafluoroethylene or sodium carboxymethylcellulose or polyvinylidene fluoride or hydroxyethyl cellulose.
8. The dry-process pole piece according to claim 5, wherein in the first electrode material layer, the weight ratio of the first active material is 60% -99%, the weight ratio of the first conductive agent is 0.1% -10%, and the weight ratio of the first binder is 1% -10%.
9. The dry-process pole piece according to claim 5, wherein in the second electrode material layer, the weight ratio of the second active material is 60% -99%, the weight ratio of the second conductive agent is 5% -20%, and the weight ratio of the second binder is 1% -10%.
10. The dry pole piece according to claim 5, wherein the weight ratio of the first conductive agent in the first electrode material layer is a;
and in the second electrode material layer, the weight ratio of the second conductive agent is b, wherein a is less than b.
11. The dry pole piece according to claim 5,
in the first electrode material layer, the particle diameter of the first active material is 1 μm to 30 μm;
in the second electrode material layer, the particle diameter of the second active material is 0.1 μm to 20 μm.
12. The dry-process pole piece according to claim 1, further comprising a conductive adhesive layer coated on one side surface of the current collector, wherein the conductive adhesive layer is located between the current collector and the composite layer.
13. The dry-process pole piece according to claim 12, wherein the conductive adhesive layer is formed by a conductive adhesive, the conductive adhesive is a mixture of a binder and a conductive agent, and the thickness of the conductive adhesive layer is 0.5 μm to 10 μm.
14. A preparation method of a dry pole piece, which is characterized in that the dry pole piece is the dry pole piece according to any one of claims 1 to 13, and the preparation method comprises the following steps:
the method comprises the steps of obtaining a first electrode material mixture containing a first active material, a first conductive agent and a first binder, and coating the first electrode material mixture on the surface of a current collector in an electrostatic spraying manner to obtain a first electrode material layer;
obtaining a second electrode material mixture containing a second active material, a second conductive agent and a second binder, and coating the second electrode material mixture on one side, away from the current collector, of the first electrode material layer in an electrostatic spraying manner to obtain a second electrode material layer;
and carrying out hot rolling on the current collector sprayed with the first electrode material layer and the second electrode material layer to obtain the dry-process pole piece.
15. The method for preparing the dry electrode sheet according to claim 14, wherein in the step of obtaining a first electrode material mixture comprising a first active material, a first conductive agent and a first binder, and applying the first electrode material mixture to the surface of the current collector by electrostatic spraying to obtain the first electrode material layer,
coating conductive adhesive on the surface of the current collector, and coating the first electrode material mixture on the conductive adhesive in an electrostatic spraying manner.
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