CN115394953B - Concave-convex array thick electrode and preparation method and application thereof - Google Patents
Concave-convex array thick electrode and preparation method and application thereof Download PDFInfo
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- 239000006258 conductive agent Substances 0.000 claims abstract description 70
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- 239000002002 slurry Substances 0.000 claims description 166
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 64
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- 229920002981 polyvinylidene fluoride Polymers 0.000 claims description 39
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 26
- 229910052744 lithium Inorganic materials 0.000 claims description 26
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- 238000003756 stirring Methods 0.000 claims description 19
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- 229910021389 graphene Inorganic materials 0.000 claims description 11
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- 238000000034 method Methods 0.000 claims description 10
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- 239000000853 adhesive Substances 0.000 claims description 7
- 230000001070 adhesive effect Effects 0.000 claims description 7
- QHGJSLXSVXVKHZ-UHFFFAOYSA-N dilithium;dioxido(dioxo)manganese Chemical compound [Li+].[Li+].[O-][Mn]([O-])(=O)=O QHGJSLXSVXVKHZ-UHFFFAOYSA-N 0.000 claims description 7
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- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims description 6
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- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 claims description 4
- 229910001416 lithium ion Inorganic materials 0.000 claims description 4
- 239000002904 solvent Substances 0.000 claims description 4
- CRHLEZORXKQUEI-UHFFFAOYSA-N dialuminum;cobalt(2+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Al+3].[Al+3].[Co+2].[Co+2] CRHLEZORXKQUEI-UHFFFAOYSA-N 0.000 claims description 3
- 229910017052 cobalt Inorganic materials 0.000 claims description 2
- 239000010941 cobalt Substances 0.000 claims description 2
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 2
- CHZUADMGGDUUEF-UHFFFAOYSA-N [Mn](=O)(=O)([O-])[O-].[Co+2] Chemical compound [Mn](=O)(=O)([O-])[O-].[Co+2] CHZUADMGGDUUEF-UHFFFAOYSA-N 0.000 claims 1
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- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 52
- 230000000052 comparative effect Effects 0.000 description 26
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 description 18
- 229910052782 aluminium Inorganic materials 0.000 description 15
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 15
- 239000006229 carbon black Substances 0.000 description 13
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- 239000002174 Styrene-butadiene Substances 0.000 description 6
- 239000011149 active material Substances 0.000 description 6
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- 239000007791 liquid phase Substances 0.000 description 6
- PFYQFCKUASLJLL-UHFFFAOYSA-N [Co].[Ni].[Li] Chemical compound [Co].[Ni].[Li] PFYQFCKUASLJLL-UHFFFAOYSA-N 0.000 description 4
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- 229910013716 LiNi Inorganic materials 0.000 description 1
- HFCVPDYCRZVZDF-UHFFFAOYSA-N [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O Chemical compound [Li+].[Co+2].[Ni+2].[O-][Mn]([O-])(=O)=O HFCVPDYCRZVZDF-UHFFFAOYSA-N 0.000 description 1
- 239000010405 anode material Substances 0.000 description 1
- 239000011324 bead Substances 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
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- 229910052759 nickel Inorganic materials 0.000 description 1
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 239000007774 positive electrode material Substances 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
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- PUZPDOWCWNUUKD-UHFFFAOYSA-M sodium fluoride Chemical compound [F-].[Na+] PUZPDOWCWNUUKD-UHFFFAOYSA-M 0.000 description 1
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- 238000000859 sublimation Methods 0.000 description 1
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Classifications
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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
- 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
-
- 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)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Battery Electrode And Active Subsutance (AREA)
Abstract
The invention provides a concave-convex array thick electrode and a preparation method and application thereof, wherein an active layer of the concave-convex array thick electrode comprises a first active strip and a second active strip which are sequentially and horizontally and alternately arranged, the first active strip contains a first conductive agent with a large length-diameter ratio, the second active strip contains a second conductive agent with a small length-diameter ratio, the thickness of the first active strip is controlled to be 5-15 mu m smaller than that of the second active strip, and the distribution of a mesoporous structure and porosity of the thick electrode is improved through the difference of the conductive agent and compaction density; the first conductive agent can enable the first active strip to keep good wettability to electrolyte and can remarkably improve the conductivity of the thick electrode; the use of a second conductive agent in the second active strip is beneficial to improving the liquid retention and hygroscopicity of the thick electrode; under the cooperation of the first active strip and the second active strip, the performance of the obtained concave-convex array thick electrode is effectively improved.
Description
Technical Field
The invention belongs to the field of lithium ion batteries, and relates to a concave-convex array thick electrode, a preparation method and application thereof.
Background
At present, with the rapid development and the continuous expansion of the scale of new energy automobiles, the market demand for high-energy high-power batteries is also continuously increased. In order to increase the energy density of the power battery, various new materials and new technologies are continuously emerging, and the main strategies for increasing the energy density of the power battery are as follows: ① Developing high-capacity anode and cathode materials, such as high-nickel materials, lithium-rich anodes, silicon cathodes, metal lithium cathodes and the like; ② Developing a high-voltage positive electrode material; ③ Developing high-performance electrolyte; ④ Developing a high-performance adhesive; ⑤ Thick electrode development, and the like.
In the technical direction of battery technology, thick electrode development is the most direct method for improving the energy density of the battery, but the thick electrode technology has some problems to be solved, such as the increase of the thickness of the electrode, the reduction of the stripping force of a pole piece, the slow infiltration rate of electrolyte, the increase of the internal resistance of the battery and the significant deterioration of the rate capability and the cycle life of the battery finally caused, although the proportion of inactive materials can be significantly reduced. A large number of researches show that the electrolyte liquid phase transmission is a speed control step in the electrochemical reaction process of the thick electrode, and the electrolyte liquid phase transmission is closely related to the pore structure, the porosity and the like in the electrode, so that the rate capability of the thick electrode can be improved based on the optimization.
For example, CN102655229B adopts a pore-forming agent solvent to coat the surface of the pole piece, the solvent volatilizes during baking, the pore-forming agent permeates into the membrane and is re-solidified to occupy a certain position, and then baking is carried out at a temperature higher than the sublimation or decomposition temperature of the pore-forming agent to form pores, so that the membrane leaves pores, and a high-porosity thick electrode is obtained; juliette Billaud et al (Nature Energy,2016,1 (8), 1-6) modify graphite negative electrode with magnetic substance, and control graphite particle orientation by using external magnetic field in homogenate stage to obtain low tortuosity graphite thick electrode, and improve battery performance by changing internal structure of electrode only, so that lithium storage capacity of electrode under actual charge rate is increased by 1.6-3 times; junsuPark (Journal of Industrial AND ENGINEERING CHEMISTRY,2019, 70:178-185) adopt laser to carry out groove etching to obtain an array groove thick electrode, thereby obviously improving the dynamic performance of the battery; however, the above thick electrode preparation methods have the following problems:
1) When the pore-forming agent is adopted for pore-forming, the thermal decomposition temperature of the pore-forming agent is incompatible with the baking temperature of the electrode, the thermal decomposition of the pore-forming agent is easy to form harmful gas, and the pore-forming efficiency is low;
2) The orientation of the particles is difficult to be controlled by an external physical field to maintain an orientation structure in the subsequent rolling, the compatibility with the current roller-to-roller process is poor, and the material modification cost is high;
3) The laser pore-forming has high destructiveness on the coating, is easy to form substances such as molten beads, dust and the like, has high self-discharge of the battery, and obviously reduces the capacity of the thick electrode surface and the energy density.
It can be seen that a new technical scheme which is simpler and more feasible and is more compatible with the electrode process is not available at present, and the states of pore structure, porosity and the like in the electrode can be effectively improved to optimize the liquid phase transmission of electrolyte under the conditions of maintaining high energy density, high power and long cycle life, so that the performance of the thick electrode is further improved.
Disclosure of Invention
In view of the problems existing in the prior art, the invention aims to provide a concave-convex array thick electrode, a preparation method and application thereof, wherein an active layer of the concave-convex array thick electrode comprises a first active strip and a second active strip which are sequentially and horizontally alternately arranged, the first active strip contains a first conductive agent with a large length-diameter ratio, the second active strip contains a second conductive agent with a small length-diameter ratio, the thickness of the first active strip is controlled to be 5-15 μm smaller than that of the second active strip, and the distribution of a mesoporous structure and porosity of the thick electrode is improved through the difference of the conductive agent and compaction density; the first conductive agent can enable the first active strip to keep good wettability to electrolyte and can remarkably improve the conductivity of the thick electrode; the use of a second conductive agent in the second active strip is beneficial to improving the liquid retention and hygroscopicity of the thick electrode; under the cooperation of the first active strip and the second active strip, the performance of the obtained concave-convex array thick electrode is effectively improved.
To achieve the purpose, the invention adopts the following technical scheme:
In a first aspect, the invention provides a concave-convex array thick electrode, which comprises a current collector and an active layer positioned on the current collector, wherein the active layer comprises a first active strip and a second active strip which are sequentially and horizontally alternately arranged; the first active strip comprises an active main material, a binder and a first conductive agent; the second active strip comprises an active main material, a binder and a second conductive agent; the aspect ratio of the first conductive agent is greater than the aspect ratio of the second conductive agent; the thickness of the first active strip is 5-15 mu m smaller than that of the second active strip; the first active strip has a compacted density greater than a compacted density of the second active strip.
According to the invention, the first conductive agent with larger length-diameter ratio is added into the first active strip, the second conductive agent with smaller length-diameter ratio is added into the second active strip, and the thickness of the first active strip is smaller than that of the second active strip but the compaction density is larger than that of the second active strip, so that the distribution of the pore structure and the porosity of the thick electrode can be improved; specifically, the first conductive agent with larger length-diameter ratio is added into the first active strip, so that the first active strip with larger compaction density can keep good wettability to electrolyte, the conductive agent with large length-diameter ratio has small specific surface area and small pore blocking effect on a thick electrode, and meanwhile, the conductive agent with large length-diameter ratio is not easy to agglomerate, active materials can be effectively dispersed, more thickness oriented pores are formed, and the electrolyte is favorably transported in the thickness direction of the thick electrode; in addition, the conductive agent with large length-diameter ratio can form an effective long-range conductive network, and meanwhile, the conductivity of the thick electrode is obviously improved; the second conductive agent with smaller length-diameter ratio is used in the second active strip, so that the liquid retention and the hygroscopicity of the thick electrode are improved; under the cooperation of the first active strip and the second active strip, the performance of the obtained concave-convex array thick electrode is effectively improved.
When the thickness difference between the first active strip and the second active strip is too small, the compaction density of the first active strip and the second active strip is not remarkably different, the second active strip cannot realize rapid absorption and infiltration of electrolyte, and the rate performance improvement effect of the thick electrode is not obvious; when the thickness difference between the first active strip and the second active strip is too large, the larger bulge of the second active strip is unfavorable for the assembly of the full battery, the bulge part is easy to fall off powder and break, and in addition, the energy density of the full battery is also reduced due to the larger bulge.
The following technical scheme is a preferred technical scheme of the invention, but is not a limitation of the technical scheme provided by the invention, and the technical purpose and beneficial effects of the invention can be better achieved and realized through the following technical scheme.
In a preferred embodiment of the present invention, the width of the first active strip is 0.5 to 100mm, for example, 0.5mm, 1mm, 5mm, 10mm, 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm or 100mm, etc., but the present invention is not limited to the above-mentioned values, and other values not shown in the above-mentioned value ranges are equally applicable.
Preferably, the width of the second active strip is 5-20%, for example 5%, 6%, 7%, 8%, 9%, 10%, 15% or 20% of the width of the first active strip, but is not limited to the recited values, and other non-recited values within the above-recited ranges are equally applicable.
As a preferred technical solution of the present invention, the first conductive agent includes any one or a combination of at least two of carbon nanotubes, carbon fibers, or graphene, and typical but non-limiting examples of the combination include a combination of carbon nanotubes and carbon fibers, a combination of carbon nanotubes and graphene, a combination of carbon fibers and graphene, and a combination of carbon nanotubes and carbon fibers and graphene.
Preferably, the second conductive agent includes any one or a combination of at least two of carbon black, acetylene black, or ketjen black, and typical but non-limiting examples of the combination include a combination of carbon black and acetylene black, a combination of carbon black and ketjen black, a combination of acetylene black and ketjen black, a combination of carbon black and acetylene black and ketjen black.
In a preferred embodiment of the present invention, the active material in the first active strip is the same as the active material in the second active strip.
Preferably, the active host material includes a positive electrode host material or a negative electrode host material.
Preferably, the positive electrode host comprises any one or a combination of at least two of lithium cobaltate, lithium manganate, lithium nickelate or lithium nickelate aluminate, and typical but non-limiting examples of the combination include a combination of lithium cobaltate and lithium manganate, a combination of lithium cobaltate and lithium nickelate, a combination of lithium manganate and lithium nickelate, and a combination of lithium manganate and lithium nickelate aluminate.
Preferably, the negative electrode host comprises any one or a combination of at least two of graphite, hard carbon, soft carbon, silicon carbon, or tin, typical but non-limiting examples of which include a combination of graphite and soft carbon, a combination of graphite and hard carbon, a combination of graphite and tin, a combination of hard carbon and tin, a combination of soft carbon and tin, a combination of silicon and tin, and a combination of silicon carbon and tin.
As a preferred embodiment of the present invention, the binder content in the first active strip is lower than the binder content in the second active strip.
Preferably, the adhesive in the first active strip is the same as the adhesive in the second active strip.
Preferably, the binder comprises any one or a combination of at least two of sodium hydroxymethyl cellulose, styrene-butadiene rubber, polyvinylidene fluoride, or polyacrylic acid, typical but non-limiting examples of which include sodium hydroxymethyl cellulose in combination with styrene-butadiene rubber, sodium hydroxymethyl cellulose in combination with polyvinylidene fluoride, sodium hydroxymethyl cellulose in combination with polyacrylic acid, styrene-butadiene rubber in combination with polyvinylidene fluoride, styrene-butadiene rubber in combination with polyacrylic acid, and polyvinylidene fluoride in combination with polyacrylic acid.
As a preferred embodiment of the present invention, the active layer is disposed on one or both surfaces of the current collector.
In a second aspect, the present invention provides a method for preparing the concave-convex array thick electrode according to the first aspect, the method comprising the following steps:
(1) Selecting a corresponding active main material, a binder and a first conductive agent to prepare a first slurry; selecting a corresponding active main material, a binder and a second conductive agent to prepare a second slurry;
(2) Coating the first slurry obtained in the step (1) on a current collector to form a first slurry strip with gaps; coating the second slurry in the gap to form a second slurry strip;
(3) And sequentially baking and rolling to form a first active strip from the first slurry strip, forming a second active strip from the second slurry strip, controlling the thickness of the first active strip to be 5-15 mu m smaller than that of the second active strip, and enabling the compaction density of the first active strip to be greater than that of the second active strip to obtain the concave-convex array thick electrode.
In a preferred embodiment of the present invention, the content of the binder in the first slurry is 30 to 80%, for example, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75% or 80% of the content of the binder in the second slurry, but the present invention is not limited to the above-mentioned values, and other non-mentioned values in the above-mentioned value ranges are equally applicable.
The invention preferably ensures that the content of the binder in the second slurry is higher, is favorable for the diffusion of the binder from the second slurry stripes to the first slurry stripes in the baking and rolling processes, obviously improves the migration of the binder, improves the distribution uniformity of the binder in the thick electrode, and improves the peeling strength.
Preferably, the content of the binder is 1 to 3wt%, for example, 1wt%, 1.2wt%, 1.4wt%, 1.6wt%, 1.8wt%, 2wt%, 2.2wt%, 2.4wt%, 2.6wt%, 2.8wt% or 3wt%, etc., based on 100wt% of the total mass of the active host material, the binder and the first conductive agent in the first slurry, but is not limited to the recited values, and other non-recited values within the above-recited value range are equally applicable.
Preferably, the thickness of the first slurry strip is the same as the thickness of the second slurry strip.
Preferably, the thickness of each of the first slurry stripes and the second slurry stripes is 100 to 1000 μm, for example, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm or 1000 μm, etc., but not limited to the above-mentioned values, other non-mentioned values within the above-mentioned value ranges are equally applicable.
As a preferable technical scheme of the invention, the preparation method comprises the following steps:
(1) Selecting corresponding active main materials, a binder, a first conductive agent and a second conductive agent, stirring and dispersing the active main materials, the binder, the first conductive agent and the second conductive agent with a solvent, and respectively preparing a first slurry and a second slurry; the first slurry contains a first conductive agent, the second slurry contains a second conductive agent, and the length-diameter ratio of the first conductive agent is larger than that of the second conductive agent; the first conductive agent comprises any one or a combination of at least two of carbon nanotubes, carbon fibers or graphene; the second conductive agent comprises any one or a combination of at least two of carbon black, acetylene black or ketjen black;
The content of the binder is 1-3% based on 100wt% of the total mass of the active main material, the binder and the first conductive agent in the first slurry; the material of the adhesive in the first active strip is the same as that of the adhesive in the second active strip; the content of the binder in the first slurry is 30-80% of the content of the binder in the second slurry; the binder comprises any one or a combination of at least two of sodium hydroxymethyl cellulose, styrene-butadiene rubber, polyvinylidene fluoride or polyacrylic acid;
the active main material comprises an anode main material or a cathode main material; the positive electrode main material comprises any one or a combination of at least two of lithium cobaltate, lithium manganate, lithium nickelate cobalt or lithium nickelate cobalt aluminate; the negative electrode main material comprises any one or a combination of at least two of graphite, hard carbon, soft carbon, silicon carbon or tin; the active main material in the first slurry and the active main material in the second slurry are the same in material;
(2) Coating the first slurry obtained in the step (1) on a current collector to form a first slurry strip with gaps; the width of the first slurry strip is 0.5-100 mm, and the gap is 5-20% of the width of the first slurry strip; the thickness of the first slurry strip is 100-1000 mu m; coating the second slurry obtained in the step (1) in the gap to form a second slurry strip, wherein the thickness of the second slurry strip is the same as that of the first slurry strip;
(3) And after baking, rolling the first slurry strip and the second slurry strip to form a first active strip, forming a second active strip by the second slurry strip, controlling the thickness of the first active strip to be 5-15 mu m smaller than that of the second active strip, and enabling the compaction density of the first active strip to be greater than that of the second active strip to obtain the concave-convex array thick electrode.
In a third aspect, the invention provides an application of the concave-convex array thick electrode in the first aspect or the concave-convex array thick electrode obtained by the preparation method in the second aspect, wherein the application comprises the step of using the concave-convex array thick electrode in a lithium ion battery.
Compared with the prior art, the invention has at least the following beneficial effects:
(1) According to the invention, by arranging two active strips with different thickness and compaction density which are alternated in turn, the distribution of pore structures and porosity can be improved; the compaction density of the first active strip is higher, higher energy density can be obtained, the compaction density of the second active strip is smaller, the second active strip has larger porosity, the liquid phase transmission rate can be obviously improved, the rate performance is improved, and the performance of the obtained concave-convex array thick electrode is effectively improved;
(2) The first conductive agent with larger length-diameter ratio can ensure that the first active strip with larger compaction density keeps good wettability to electrolyte, and improves the conductivity of the thick electrode; the second active strip uses a second conductive agent with smaller length-diameter ratio, which is beneficial to improving the liquid retention and hygroscopicity of the thick electrode;
(3) Compared with the prior art of pore-forming of thick electrodes, the active layer has complete structure, no residue and no dust, and the cycle performance of the electrode is obviously improved; the preparation method disclosed by the invention has the advantages of simple process, high production efficiency and remarkable reduction of the preparation cost of the thick electrode;
(4) The binder content in the second slurry is higher than that in the first slurry, so that the binder in the second slurry strip can be diffused into the first slurry strip in a surrounding radiation manner during coating and baking, the migration condition of the binder is obviously improved, the distribution uniformity of the binder of the whole thick electrode is improved, and the peeling strength is effectively improved.
Drawings
FIG. 1 is a schematic top view of a thick electrode of a concave-convex array of lithium iron phosphate according to example 1 of the present invention;
FIG. 2 is a schematic cross-sectional view taken along the direction A-A in FIG. 1;
in the figure: 1-first active strip, 2-second active strip, 3-current collector.
Detailed Description
The technical scheme of the invention is further described below by the specific embodiments with reference to the accompanying drawings. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.
Example 1
The embodiment provides a lithium iron phosphate concave-convex array thick electrode, and the preparation method of the lithium iron phosphate concave-convex array thick electrode comprises the following steps:
(1) Stirring and dispersing lithium iron phosphate, PVDF (polyvinylidene fluoride), carbon nano tubes and carbon fibers in NMP (N-methyl pyrrolidone), wherein the content of PVDF is 2wt%, and the total content of carbon nano tubes and carbon fibers is 1.5wt%, so as to obtain uniform first slurry; stirring and dispersing lithium iron phosphate, PVDF and carbon black in NMP, wherein the content of PVDF is 3wt%, and the content of carbon black is 2.5wt%, so as to obtain uniform second slurry;
(2) Coating the first slurry in the step (1) on an aluminum current collector to form an array formed by first slurry stripes with gaps of 2mm and widths of 20mm, wherein the thickness of the first slurry stripes is 200 mu m; coating the second slurry obtained in the step (1) in the obtained gap to form second slurry stripes with the thickness equal to that of the first slurry stripes;
(3) And after baking, rolling the first slurry strip and the second slurry strip respectively, so that the first slurry strip forms a first active strip with the thickness of 150 mu m, the second slurry strip forms a second active strip with the thickness of 160 mu m, and the compaction density of the first active strip is larger than that of the second active strip, thus obtaining the lithium iron phosphate concave-convex array thick electrode.
The schematic structural diagram of the thick electrode of the lithium iron phosphate concave-convex array in this embodiment is shown in fig. 1 and 2, where the thick electrode of the lithium iron phosphate concave-convex array includes a current collector 3 formed by aluminum foil, and an active layer formed by sequentially and horizontally alternately arranging a first active strip 1 and a second active strip 2 on the current collector 3; the width of the first active stripe 1 is 20mm, and the thickness is 150 μm; the second active stripe 2 has a width of 2mm and a thickness of 160 μm.
Example 2
The embodiment provides an NCM523 (LiNi 5Co2Mn3O2) concave-convex array thick electrode, and the preparation method of the NCM523 concave-convex array thick electrode comprises the following steps:
(1) Stirring and dispersing NCM523, PVDF and carbon nanotubes in NMP, wherein the PVDF content is 3wt% and the carbon nanotubes content is 3wt%, so as to obtain uniform first slurry; stirring and dispersing NCM523, PVDF and acetylene black in NMP, wherein the PVDF content is 3.5wt% and the acetylene black content is 2.5wt%, so as to obtain uniform second slurry;
(2) Coating the first slurry in the step (1) on an aluminum current collector to form an array formed by first slurry stripes with gaps of 3mm and widths of 30mm, wherein the thickness of the first slurry stripes is 300 mu m; coating the second slurry obtained in the step (1) in the obtained gap to form second slurry stripes with the thickness equal to that of the first slurry stripes;
(3) And after baking, rolling the first slurry strip and the second slurry strip respectively, so that the first slurry strip forms a first active strip with the thickness of 200 mu m, the second slurry strip forms a second active strip with the thickness of 215 mu m, and the compaction density of the first active strip is greater than that of the second active strip, thus obtaining the NCM523 concave-convex array thick electrode.
Example 3
The embodiment provides a thick electrode of a graphite concave-convex array, and the preparation method of the thick electrode of the graphite concave-convex array comprises the following steps:
(1) Stirring and dispersing graphite, SBR (styrene butadiene rubber), carbon nano tubes and carbon fibers in NMP, wherein the content of SBR is 2wt%, and the total content of the carbon nano tubes and the carbon fibers is 1wt%, so as to obtain uniform first slurry; stirring and dispersing graphite, SBR and carbon black in NMP, wherein the content of SBR is 2.5wt% and the content of carbon black is 2wt%, so as to obtain uniform second slurry;
(2) Coating the first slurry in the step (1) on an aluminum current collector to form an array formed by first slurry stripes with gaps of 4mm and widths of 20mm, wherein the thickness of the first slurry stripes is 180 mu m; coating the second slurry obtained in the step (1) in the obtained gap to form second slurry stripes with the thickness equal to that of the first slurry stripes;
(3) And after baking, rolling the first slurry strip and the second slurry strip respectively, so that the first slurry strip forms a first active strip with the thickness of 150 mu m, the second slurry strip forms a second active strip with the thickness of 160 mu m, and the compaction density of the first active strip is larger than that of the second active strip, thus obtaining the graphite concave-convex array thick electrode.
Example 4
The embodiment provides a lithium cobaltate concave-convex array thick electrode, and the preparation method of the lithium cobaltate concave-convex array thick electrode comprises the following steps:
(1) Stirring and dispersing lithium cobaltate, PVDF and graphene in NMP, wherein the content of PVDF is 1wt% and the content of graphene is 2wt%, so as to obtain uniform first slurry; stirring and dispersing lithium cobaltate, PVDF and ketjen black in NMP, wherein the content of PVDF is 3.3wt% and the content of carbon black is 1.5wt%, so as to obtain uniform second slurry;
(2) Coating the first slurry in the step (1) on an aluminum current collector to form an array formed by first slurry stripes with gaps of 2.5mm and widths of 15mm, wherein the thickness of the first slurry stripes is 100 mu m; coating the second slurry obtained in the step (1) in the obtained gap to form second slurry stripes with the thickness equal to that of the first slurry stripes;
(3) And after baking, rolling the first slurry strip and the second slurry strip respectively, so that the first slurry strip forms a first active strip with the thickness of 80 mu m, the second slurry strip forms a second active strip with the thickness of 85 mu m, and the compaction density of the first active strip is greater than that of the second active strip, thus obtaining the lithium cobaltate concave-convex array thick electrode.
Example 5
The embodiment provides a nickel cobalt lithium aluminate concave-convex array thick electrode, and the preparation method of the nickel cobalt lithium aluminate concave-convex array thick electrode comprises the following steps:
(1) Stirring and dispersing nickel cobalt lithium aluminate, PVDF, carbon fiber and graphene in NMP, wherein the content of the PVDF is 2.4wt%, and the total content of the carbon fiber and the graphene is 2.5wt%, so as to obtain uniform first slurry; stirring and dispersing nickel cobalt lithium aluminate, PVDF, carbon black, acetylene black and ketjen black in NMP, wherein the content of PVDF is 3wt%, and the total content of carbon black, acetylene black and ketjen black is 3wt%, so as to obtain uniform second slurry;
(2) Coating the first slurry in the step (1) on an aluminum current collector to form an array formed by first slurry stripes with gaps of 10mm and widths of 100mm, wherein the thickness of the first slurry stripes is 500 mu m; coating the second slurry obtained in the step (1) in the obtained gap to form second slurry stripes with the thickness equal to that of the first slurry stripes;
(3) And after baking, rolling the first slurry strip and the second slurry strip respectively, so that the first slurry strip forms a first active strip with the thickness of 380 mu m, the second slurry strip forms a second active strip with the thickness of 390 mu m, and the compaction density of the first active strip is greater than that of the second active strip, thus obtaining the lithium iron phosphate concave-convex array thick electrode.
Example 6
The present embodiment provides a lithium iron phosphate concave-convex array thick electrode, and the preparation method of the lithium iron phosphate concave-convex array thick electrode is exactly the same as that of embodiment 1 except that the content of the binder PVDF in the second slurry is adjusted from 3wt% to 8wt% in step (1).
Example 7
The present example provides a lithium iron phosphate concave-convex array thick electrode, and the preparation method of the lithium iron phosphate concave-convex array thick electrode is exactly the same as that of example 1 except that the content of the binder PVDF in the second slurry is adjusted from 3wt% to 6.6wt% in step (1).
Example 8
The present example provides a lithium iron phosphate concave-convex array thick electrode, and the preparation method of the lithium iron phosphate concave-convex array thick electrode is identical to that of example 1 except that the content of the binder PVDF in the second slurry in step (1) is adjusted from 3wt% to 2.5 wt%.
Example 9
The present example provides a lithium iron phosphate concave-convex array thick electrode, and the preparation method of the lithium iron phosphate concave-convex array thick electrode is identical to that of example 1 except that the content of the binder PVDF in the second slurry in step (1) is adjusted from 3wt% to 2.2 wt%.
Example 10
The present embodiment provides a lithium iron phosphate concave-convex array thick electrode, and the preparation method of the lithium iron phosphate concave-convex array thick electrode is exactly the same as that of embodiment 1 except that the content of the binder PVDF in the second slurry is adjusted from 3wt% to 2wt% in step (1).
Example 11
The present embodiment provides a thick electrode of a lithium iron phosphate concave-convex array, and the preparation method of the thick electrode of a lithium iron phosphate concave-convex array is exactly the same as that of embodiment 1 except that the first slurry in step (2) is coated on an aluminum current collector to form an array formed by first slurry stripes with a gap of 1mm and a width of 20 mm.
Example 12
The present embodiment provides a thick electrode of a lithium iron phosphate concave-convex array, and the preparation method of the thick electrode of a lithium iron phosphate concave-convex array is exactly the same as that of embodiment 1 except that the first slurry in step (2) is coated on an aluminum current collector to form an array formed by first slurry stripes with a gap of 3mm and a width of 20 mm.
Example 13
The present embodiment provides a thick electrode of a lithium iron phosphate concave-convex array, and the preparation method of the thick electrode of a lithium iron phosphate concave-convex array is exactly the same as that of embodiment 1 except that the first slurry in step (2) is coated on an aluminum current collector to form an array formed by first slurry stripes with a gap of 4mm and a width of 20 mm.
Example 14
The present embodiment provides a thick electrode of a lithium iron phosphate concave-convex array, and the preparation method of the thick electrode of a lithium iron phosphate concave-convex array is identical to that of embodiment 1 except that the first slurry in step (2) is coated on an aluminum current collector to form an array formed by first slurry stripes with a gap of 0.5mm and a width of 20 mm.
Example 15
The present embodiment provides a thick electrode of a lithium iron phosphate concave-convex array, and the preparation method of the thick electrode of a lithium iron phosphate concave-convex array is exactly the same as that of embodiment 1 except that the first slurry in step (2) is coated on an aluminum current collector to form an array formed by first slurry stripes with a gap of 10mm and a width of 20 mm.
Example 16
The present embodiment provides a thick electrode of a lithium iron phosphate concave-convex array, and the preparation method of the thick electrode of a lithium iron phosphate concave-convex array is exactly the same as that of embodiment 1 except that the first slurry in step (2) is coated on an aluminum current collector to form an array formed by first slurry stripes with a gap of 20mm and a width of 20 mm.
Comparative example 1
The comparative example provides a lithium iron phosphate thick electrode, and the preparation method of the lithium iron phosphate thick electrode comprises the following steps:
Stirring and dispersing lithium iron phosphate, PVDF, carbon nano tubes and carbon fibers in NMP, wherein the content of the PVDF is 2wt%, and the total content of the carbon nano tubes and the carbon fibers is 1.5wt%, so as to obtain uniform slurry; coating the slurry on an aluminum current collector to form a slurry layer with the thickness of 200 mu m; and baking and rolling sequentially to form an active layer with the thickness of 150 mu m on the slurry layer, thereby obtaining the lithium iron phosphate thick electrode.
Comparative example 2
The comparative example provides a NCM523 thick electrode, and the preparation method of the NCM523 thick electrode comprises the following steps:
Stirring and dispersing NCM523, PVDF and carbon nanotubes in NMP, wherein the PVDF content is 3wt% and the carbon nanotubes content is 3wt%, so as to obtain uniform slurry; coating the slurry on an aluminum current collector to form a slurry layer with the thickness of 300 mu m; and baking and rolling in sequence to form an active layer with the thickness of 200 mu m on the slurry layer to obtain the NCM523 thick electrode.
Comparative example 3
The comparative example provides a graphite thick electrode, and the preparation method of the graphite thick electrode comprises the following steps:
Stirring and dispersing graphite, SBR, carbon nano tubes and carbon fibers in NMP, wherein the content of SBR is 2wt% and the total content of carbon nano tubes and carbon fibers is 1wt% to obtain uniform slurry; coating the first slurry on an aluminum current collector to form a slurry layer with the thickness of 180 mu m; and baking and rolling sequentially to form an active layer with the thickness of 150 mu m on the slurry layer, thereby obtaining the graphite thick electrode.
Comparative example 4
The present comparative example provides a lithium iron phosphate concave-convex array thick electrode, wherein the first conductive agent in the first active strip in the lithium iron phosphate concave-convex array thick electrode is made of the same material as the second conductive agent, that is, the step (1) is:
Stirring and dispersing lithium iron phosphate, PVDF and carbon black in NMP, wherein the content of PVDF is 2wt%, and the content of carbon black is 1.5wt%, so as to obtain uniform first slurry; stirring and dispersing lithium iron phosphate, PVDF and carbon black in NMP, wherein the content of PVDF is 3wt%, and the content of carbon black is 2.5wt%, so as to obtain uniform second slurry;
other conditions of this comparative example were exactly the same as in example 1.
Comparative example 5
The present comparative example provides a lithium iron phosphate concave-convex array thick electrode, wherein the second conductive agent in the second active strip in the lithium iron phosphate concave-convex array thick electrode uses the same material as the first conductive agent, that is, step (1) is:
Stirring and dispersing lithium iron phosphate, PVDF, carbon nano tubes and carbon fibers in NMP, wherein the content of PVDF is 2wt%, and the total content of carbon nano tubes and carbon fibers is 1.5wt%, so as to obtain uniform first slurry; stirring and dispersing lithium iron phosphate, PVDF and carbon black in NMP, wherein the PVDF content is 3wt%, and the total content of the carbon nano tube and the carbon fiber is 2.5wt%, so as to obtain uniform second slurry;
other conditions of this comparative example were exactly the same as in example 1.
Comparative example 6
This comparative example provides a lithium iron phosphate concave-convex array thick electrode in which the thickness of the second active bar is smaller than that of the first active bar, that is, the preparation method of the lithium iron phosphate concave-convex array thick electrode is exactly the same as that of example 1 except that the thickness of the second paste bar is adjusted from 160 μm to 130 μm in step (4).
Comparative example 7
This comparative example provides a lithium iron phosphate concave-convex array thick electrode in which the thickness of the second active bar is the same as that of the first active bar, that is, the preparation method of the lithium iron phosphate concave-convex array thick electrode is exactly the same as that of example 1 except that the thickness of the second paste bar is adjusted from 160 μm to 150 μm in step (4).
Comparative example 8
This comparative example provides a lithium iron phosphate concavo-convex array thick electrode, which was prepared in exactly the same manner as in example 1 except that the thickness of the second paste bar was adjusted from 160 μm to 153 μm in step (4).
Comparative example 9
This comparative example provides a lithium iron phosphate concavo-convex array thick electrode, which was prepared in exactly the same manner as in example 1 except that the thickness of the second paste bar was adjusted from 160 μm to 170 μm in step (4).
The capacity retention rates of the batteries prepared in examples and comparative examples at 25 ℃ under different rates were measured, the voltage interval of the battery in which the electrode active material was lithium iron phosphate was 2.5 to 3.65V, the voltage interval of ncm523, lithium cobaltate, lithium nickel cobalt manganate was 2.5 to 4.2V, the voltage interval of graphite was 2.5 to 3.65V, the rates were 0.5C, 1C, 2C and 3C, respectively, and the capacity retention rate was calculated by dividing the capacity of XC by the capacity of 0.33C (X was 0.5, 1, 2 or 3), and the capacity retention rate under the corresponding rates was obtained, and the measurement results are shown in table 1.
TABLE 1
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As can be seen from table 1:
(1) Comparing example 1 with comparative example 1, comparing example 2 with comparative example 2, and comparing example 3 with comparative example 3, respectively, it was found that: compared with the conventional thick electrode, the concave-convex array thick electrode adopted by the invention can obviously improve the multiplying power performance of the lithium iron phosphate thick electrode;
(2) Comparing example 1 with comparative examples 4 and 5, it was found that: the rate performance of the concave-convex array thick electrode prepared by adopting a single conductive agent is not better than that of the scheme provided by the invention. The first active strip adopts a first conductive agent with a large length-diameter ratio, and the second active strip adopts a second conductive agent with a small length-diameter ratio. The first conductive agent can effectively improve the liquid-phase lithium ion transmission of the thick electrode, the second conductive agent can obviously improve the liquid absorption and liquid retention capacity of the electrolyte, and the two different conductive agents act cooperatively, so that the rate performance of the thick electrode is obviously improved, and the synergistic effect cannot be achieved by a single conductive agent;
(3) Comparing example 1 with examples 6-10, it was found that: the second active bar binder content is higher than the 1 st active bar binder content, which is more beneficial to the improvement of the rate performance of the thick electrode. When the content of the second binder is too high, the resistance of the pole piece is obviously increased, so that the internal resistance of the battery is increased, and the multiplying power performance is attenuated; when the content of the second binder is low, the non-uniformity of binder migration is obviously increased when the thick electrode is baked, the interface impedance of the thick electrode is obviously increased, the internal resistance is increased, and the multiplying power performance of the thick electrode is obviously attenuated, so that the binder content of the first active strip and the binder content of the second active strip are required to meet a certain proportion, and based on the results of a large number of experiments, the binder content of the first active strip is 30-80% of the binder content of the second active strip.
(4) Comparing example 1 with examples 11-16, it was found that: too large or too small a ratio of the first active bar width to the second active bar width will result in a decay in the rate capability of the thick electrode. When the second active strip is too small, the electrolyte absorption rate is low, and meanwhile, the total content of the second active strip binder is reduced, so that the problems of reduced stripping force and increased internal resistance caused by migration of the first active strip binder are difficult to effectively relieve. Similarly, too large a width of the second active bar results in a significant decrease in the effective compacted density of the thick electrode, while too much total binder in the second active bar will also significantly increase the thick electrode resistivity, resulting in an increase in the internal resistance of the thick electrode and a significant deterioration in the rate capability. Based on experimental results, the preferred width of the second active strip of the present invention is 5-20% of the width of the first active strip.
(5) Comparing example 1 with comparative examples 6-9, it was found that: too large or too small a difference between the thickness of the second active strip and the thickness of the first active strip is not beneficial to the rate capability of the lithium iron phosphate thick electrode. The thickness of the second active strip is too small, the compaction density and the porosity of the second active strip are not obviously different from those of the first active strip, and the second active strip can not effectively improve the liquid phase transmission of the electrolyte in the thick electrode; the second active strip has a significantly lower compaction density than the first active strip if the second active strip is too thick, however, the smaller compaction density is unfavorable for close contact between the active materials and the current collector, resulting in reduced peel strength and adhesion of the second active strip, and significantly increased contact resistance of the pole piece, while the second active strip is prone to breakage and powder fall, resulting in reduced rate performance. Therefore, the thickness of the first active material is preferably 5-15 μm smaller than that of the second active material, so that the internal resistance of the thick electrode is significantly reduced, and a thick electrode with excellent rate performance is obtained.
The detailed structural features of the present invention are described in the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must be implemented depending on the above detailed structural features. It should be apparent to those skilled in the art that any modifications of the present invention, equivalent substitutions of selected components of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope of the present invention and the scope of the disclosure.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the scope of the technical concept of the present invention, and all the simple modifications belong to the protection scope of the present invention.
In addition, the specific features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various possible combinations are not described further.
Moreover, any combination of the various embodiments of the invention can be made without departing from the spirit of the invention, which should also be considered as disclosed herein.
Claims (15)
1. The concave-convex array thick electrode is characterized by comprising a current collector and an active layer positioned on the current collector, wherein the active layer comprises a first active strip and a second active strip which are sequentially and horizontally alternately arranged; the first active strip comprises an active main material, a binder and a first conductive agent; the second active strip comprises an active main material, a binder and a second conductive agent;
The aspect ratio of the first conductive agent is greater than the aspect ratio of the second conductive agent; the first conductive agent comprises any one or a combination of at least two of carbon nanotubes, carbon fibers or graphene; the second conductive agent comprises any one or a combination of at least two of carbon black, acetylene black or ketjen black;
the width of the second active strip is 5-20% of the width of the first active strip;
the thickness of the first active strip is 5-15 mu m smaller than that of the second active strip;
the compacted density of the first active strip is greater than the compacted density of the second active strip;
The content of the binder in the first active strip is 30-80% of the content of the binder in the second active strip.
2. The relief array thick electrode of claim 1, wherein the width of the first active strip is 0.5-100 mm.
3. The relief array thick electrode according to claim 1, wherein the active host material in the first active strip is the same material as the active host material in the second active strip.
4. The concave-convex array thick electrode according to claim 1, wherein the active host material comprises a positive electrode host material or a negative electrode host material.
5. The relief array thick electrode according to claim 4, wherein the positive electrode host material comprises any one or a combination of at least two of lithium cobaltate, lithium manganate, lithium nickelate cobalt manganate or lithium nickelate cobalt aluminate.
6. The relief array thick electrode according to claim 4, wherein said negative electrode host material comprises any one or a combination of at least two of graphite, hard carbon, soft carbon, silicon carbon, or tin.
7. The relief array thick electrode of claim 1, wherein the binder in the first active strip is the same material as the binder in the second active strip.
8. The relief array thick electrode according to claim 1, wherein the binder comprises any one or a combination of at least two of sodium hydroxymethyl cellulose, styrene-butadiene rubber, polyvinylidene fluoride, or polyacrylic acid.
9. The concave-convex array thick electrode according to claim 1, wherein the active layer is provided on a surface of one or both sides of the current collector.
10. A method for manufacturing a thick electrode of a concave-convex array according to any one of claims 1 to 9, comprising the steps of:
(1) Selecting a corresponding active main material, a binder and a first conductive agent to prepare a first slurry; selecting a corresponding active main material, a binder and a second conductive agent to prepare a second slurry;
(2) Coating the first slurry obtained in the step (1) on a current collector to form a first slurry strip with gaps; coating the second slurry in the gap to form a second slurry strip;
(3) And sequentially baking and rolling to form a first active strip from the first slurry strip, forming a second active strip from the second slurry strip, controlling the thickness of the first active strip to be 5-15 mu m smaller than that of the second active strip, and enabling the compaction density of the first active strip to be greater than that of the second active strip to obtain the concave-convex array thick electrode.
11. The method of manufacturing a thick electrode of a concave-convex array according to claim 10, wherein the content of the binder is 1 to 3wt% based on 100wt% of the total mass of the active host material, the binder and the first conductive agent in the first slurry.
12. The method of manufacturing a thick electrode of a concave-convex array according to claim 10, wherein the thickness of the first paste bar is the same as the thickness of the second paste bar.
13. The method of manufacturing a thick electrode of a concave-convex array according to claim 12, wherein the thickness of each of the first paste bar and the second paste bar is 100 to 1000 μm.
14. The method for manufacturing a thick electrode of a concave-convex array according to claim 10, comprising the steps of:
(1) Selecting corresponding active main materials, a binder, a first conductive agent and a second conductive agent, stirring and dispersing the active main materials, the binder, the first conductive agent and the second conductive agent with a solvent, and respectively preparing a first slurry and a second slurry; the first slurry contains a first conductive agent, the second slurry contains a second conductive agent, and the length-diameter ratio of the first conductive agent is larger than that of the second conductive agent; the first conductive agent comprises any one or a combination of at least two of carbon nanotubes, carbon fibers or graphene; the second conductive agent comprises any one or a combination of at least two of carbon black, acetylene black or ketjen black;
The content of the binder is 1-3% based on 100wt% of the total mass of the active main material, the binder and the first conductive agent in the first slurry; the material of the adhesive in the first active strip is the same as that of the adhesive in the second active strip; the content of the binder in the first slurry is 30-80% of the content of the binder in the second slurry; the binder comprises any one or a combination of at least two of sodium hydroxymethyl cellulose, styrene-butadiene rubber, polyvinylidene fluoride or polyacrylic acid;
the active main material comprises an anode main material or a cathode main material; the positive electrode main material comprises any one or a combination of at least two of lithium cobaltate, lithium manganate, lithium nickelate cobalt or lithium nickelate cobalt aluminate; the negative electrode main material comprises any one or a combination of at least two of graphite, hard carbon, soft carbon, silicon carbon or tin; the active main material in the first slurry and the active main material in the second slurry are the same in material;
(2) Coating the first slurry obtained in the step (1) on a current collector to form a first slurry strip with gaps; the width of the first slurry strip is 0.5-100 mm, and the gap is 5-20% of the width of the first slurry strip; the thickness of the first slurry strip is 100-1000 mu m; coating the second slurry obtained in the step (1) in the gap to form a second slurry strip, wherein the thickness of the second slurry strip is the same as that of the first slurry strip;
(3) And after baking, rolling the first slurry strip and the second slurry strip to form a first active strip, forming a second active strip by the second slurry strip, controlling the thickness of the first active strip to be 5-15 mu m smaller than that of the second active strip, and enabling the compaction density of the first active strip to be greater than that of the second active strip to obtain the concave-convex array thick electrode.
15. Use of a thick relief array electrode according to any one of claims 1-9 or obtained by a method according to any one of claims 10-14, wherein said use comprises using said thick relief array electrode in a lithium ion battery.
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2022
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