CN115566139A - Positive pole piece and preparation method and application thereof - Google Patents

Positive pole piece and preparation method and application thereof Download PDF

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Publication number
CN115566139A
CN115566139A CN202211406512.9A CN202211406512A CN115566139A CN 115566139 A CN115566139 A CN 115566139A CN 202211406512 A CN202211406512 A CN 202211406512A CN 115566139 A CN115566139 A CN 115566139A
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Prior art keywords
layer
positive electrode
mass
mass fraction
bisphenol
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Chinese (zh)
Inventor
崔新然
孟凡佳
郭英伦
李军泽
韩聪
杨宇
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FAW Jiefang Automotive Co Ltd
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FAW Jiefang Automotive Co Ltd
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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
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1391—Processes of manufacture of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/572—Means for preventing undesired use or discharge
    • H01M50/584—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries
    • H01M50/586—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries inside the batteries, e.g. incorrect connections of electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/50—Current conducting connections for cells or batteries
    • H01M50/572—Means for preventing undesired use or discharge
    • H01M50/584—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries
    • H01M50/59—Means for preventing undesired use or discharge for preventing incorrect connections inside or outside the batteries characterised by the protection means
    • H01M50/593—Spacers; Insulating plates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/028—Positive electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The invention provides a positive pole piece and a preparation method and application thereof, wherein the positive pole piece comprises a positive pole current collector, and a substrate layer, an intermediate layer and an active layer which are sequentially stacked on the surface of the positive pole current collector, wherein the substrate layer, the intermediate layer and the active layer all comprise bisphenol-S epoxy resin.

Description

Positive pole piece and preparation method and application thereof
Technical Field
The invention belongs to the technical field of lithium ion batteries, and relates to a positive pole piece, and a preparation method and application thereof.
Background
With the rapid development of scientific technology, lithium ion batteries, as an ideal chemical energy source recognized by the present society, are widely applied to electronic products such as cameras, mobile phones, notebook computers and the like due to their advantages of small volume, large capacitance, small repeated use capacity loss and the like, but the safety problems, such as leakage, expansion, combustion, even explosion and other dangerous situations, are more and more emphasized by people, and meanwhile, the popularization and application of the lithium ion batteries in the fields of power and large-scale energy storage are seriously hindered, and people have to reduce the harm brought to people by the defects by adding high-temperature safety materials and the like.
Nowadays, the development of electric vehicles is vigorous, and the requirements on lithium ion batteries are higher and higher, and the electric vehicles relate to various aspects such as long service life, high power, quick charging, high safety and the like. The conventional lithium ion battery positive plate is obtained by coating an electrode active material on a current collector, and the main reason for thermal runaway of the lithium ion battery adopting the electrode positive plate is short circuit inside the battery.
Under abnormal operation, the lithium ion battery may suffer from conditions of thermal shock, needling, extrusion, severe collision and the like, so that the internal short circuit of the battery is caused, a large amount of heat is released, the diaphragm has failure behaviors such as volume shrinkage and the like, the thermal runaway deterioration is further caused, and safety problems such as fire, explosion and the like are caused.
CN109004175A discloses a positive electrode plate and a lithium ion battery, the positive electrode plate includes: a current collector; a first active material layer including a first active material; and a second active material layer; the first active material layer is arranged between the current collector and the second active material layer and comprises a first active material, and the first active material is selected from at least one of the combination of a modified ternary cathode material and a modified nickel-cobalt-manganese ternary material.
CN112531174A discloses a positive electrode sheet and a battery, wherein the positive electrode sheet is sequentially stacked with a third coating, a first positive electrode coating and a second positive electrode coating on a positive electrode current collector. When the battery is short-circuited, the first positive coating can increase the contact impedance of the positive pole piece, reduce short-circuit current in the battery, further reduce the heat generated in the battery, and reduce the risk of safety out of control of the battery.
According to the scheme, the positive pole piece cannot give consideration to both the cycle performance and the high-temperature safety performance, and the application of the positive pole piece in practice is limited, so that the lithium ion battery with good cycle performance and high-temperature safety guarantee is needed.
Disclosure of Invention
The invention aims to provide a positive pole piece and a preparation method and application thereof, and the invention ensures that BPSER does not influence the normal operation of a lithium ion battery by the design of the proportion of bisphenol-S epoxy resin (BPSER) materials in a substrate layer, an intermediate layer and an active layer, the layer thickness and the mixed sequence design of key materials.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the invention provides a positive pole piece, which comprises a positive pole current collector, and a substrate layer, an intermediate layer and an active layer which are sequentially stacked on the surface of the positive pole current collector, wherein the substrate layer, the intermediate layer and the active layer all comprise bisphenol-S epoxy resin.
According to the invention, a bisphenol-S epoxy resin (BPSER) material is added into the coating of the traditional lithium ion battery anode material, and is insoluble in electrolyte, so that an insulating layer can be rapidly and effectively formed under the condition that the lithium ion battery is suddenly heated due to short circuit or failure and a diaphragm fails, the electrochemical reaction is cut off, and the high-temperature safety performance of the battery is improved.
As the BPSER is non-conductive and does not participate in electrochemical reaction, the invention ensures that the BPSER does not influence the normal operation of the lithium ion battery and improves the safety performance of the battery by the differential design of the substrate layer, the intermediate layer and the active layer and the mixed sequential design of key materials, wherein the substrate layer is close to the current collector, and the active layer is far away from the current collector and is close to the diaphragm.
Preferably, the base layer further includes a positive electrode active material, a conductive agent, and a binder.
Preferably, the mass fraction of the positive electrode active material is 60 to 75% based on 100% by mass of the base layer, for example: 60%, 68%, 70%, 72%, 75%, etc.
Preferably, the mass fraction of the bisphenol-S epoxy resin is 1 to 3%, such as: 1%, 1.5%, 2%, 2.5%, 3%, etc.
Preferably, the mass fraction of the conductive agent is 15 to 25%, for example: 15%, 18%, 20%, 22%, 25%, etc.
Preferably, the mass fraction of the binder is 8 to 15%, for example: 8%, 9%, 10%, 12%, 15%, etc.
Preferably, the thickness of the substrate layer is 10 to 30 μm, for example: 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, or the like.
Preferably, the intermediate layer further includes a positive electrode active material, a conductive agent, and a binder.
Preferably, the mass fraction of the positive electrode active material is 70 to 85% based on 100% by mass of the intermediate layer, for example: 70%, 72%, 75%, 80%, 85%, etc.
Preferably, the mass fraction of the bisphenol-S epoxy resin is 0.5 to 1%, for example: 0.5%, 0.6%, 0.7%, 0.8%, or 1%, etc.
Preferably, the mass fraction of the conductive agent is 10 to 15%, for example: 10%, 11%, 12%, 13%, 14%, 15%, etc.
Preferably, the mass fraction of the binder is 5 to 10%, for example: 5%, 6%, 7%, 8%, 10%, etc.
Preferably, the thickness of the intermediate layer is 20 to 50 μm, for example: 20 μm, 25 μm, 30 μm, 40 μm, or 50 μm, etc.
Preferably, the active layer further includes a positive electrode active material, a conductive agent, and a binder.
Preferably, the mass fraction of the positive electrode active material is 75 to 90% based on 100% by mass of the active layer, for example: 75%, 78%, 80%, 85%, 90%, etc.
Preferably, the mass fraction of the bisphenol-S epoxy resin is 0.5 to 1%, for example: 0.5%, 0.6%, 0.7%, 0.8%, or 1%, etc.
Preferably, the mass fraction of the conductive agent is 5 to 10%, for example: 5%, 6%, 7%, 8%, 10%, etc.
Preferably, the mass fraction of the binder is 4 to 10%, for example: 4%, 5%, 6%, 8%, 10%, etc.
Preferably, the thickness of the active layer is 50 to 100 μm, for example: 50 μm, 60 μm, 70 μm, 80 μm, 100 μm, or the like.
In a second aspect, the invention provides a method for preparing the positive electrode plate according to the first aspect, wherein the method for preparing the positive electrode plate comprises the following steps:
(1) Respectively according to the proportion of each material in the basal layer, the middle layer and the active layer, uniformly mixing all the positive active materials with the designed mass and the conductive agent with the designed mass of 2/3, adding the binder with the designed mass of 1/2, continuously and uniformly mixing to form slurry 1, uniformly mixing all the bisphenol-S epoxy resin with the designed mass and the conductive agent with the designed mass of 1/3, adding the binder with the designed mass of 1/2, continuously and uniformly mixing to form slurry 2, and uniformly mixing the slurry 1 and the slurry 2 for coating;
(2) And coating the base layer slurry, the intermediate layer slurry and the active layer slurry on the surface of the positive current collector in sequence and drying to obtain the positive pole piece.
Preferably, the temperature of the drying in the step (2) is less than 120 ℃.
In a third aspect, the present invention provides a lithium ion battery, which includes the positive electrode plate according to the first aspect.
Compared with the prior art, the invention has the following beneficial effects:
(1) According to the invention, the proportion of bisphenol-S epoxy resin (BPSER) materials in the substrate layer, the intermediate layer and the active layer, the layer thickness design and the mixing sequence design of key materials are adopted, so that the BPSER is ensured not to influence the normal operation of the lithium ion battery.
(2) The retention rate of 500-time cycle capacity of the positive pole piece can reach more than 97%, and 100% of the positive pole piece can pass acupuncture, extrusion and noon impact tests, so that the positive pole piece has good electrochemical performance and safety performance.
Drawings
Fig. 1 is a schematic cross-sectional view of the positive electrode sheet described in example 1 of the present invention, 1.1-active layer, 1.2-intermediate layer, 1.3-base layer, 2-current collector.
Detailed Description
The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitation of the present invention.
The positive pole pieces of embodiments 1-9 of the invention are all prepared by the following method:
(1) Respectively mixing all positive active materials with the designed mass and 2/3 of conductive agents with the designed mass uniformly according to the proportion of all materials in the substrate layer, the intermediate layer and the active layer, adding 1/2 of binder with the designed mass, continuously mixing uniformly to form slurry 1, mixing all bisphenol-S epoxy resin with the designed mass and 1/3 of conductive agents with the designed mass uniformly, adding 1/2 of binder with the designed mass, continuously mixing uniformly to form slurry 2, and mixing the slurry 1 and the slurry 2 uniformly for coating;
(2) And coating the base layer slurry, the intermediate layer slurry and the active layer slurry on the surface of the positive current collector in sequence, and drying at 110 ℃ to obtain the positive pole piece.
Example 1
This embodiment provides a positive pole piece, positive pole piece include the aluminium foil mass collector with set up in the basal layer that the thickness on aluminium foil mass collector surface is 80 μm, the intermediate level that thickness is 30 μm and the active layer that thickness is 20 μm, wherein, the basal layer comprises nickel cobalt manganese ternary material positive pole material, bisphenol-S epoxy resin, conductive carbon black SP, polyvinylidene fluoride, and the quality accounts for the ratio and is 85%, 0.5%, 9.5%, 5% respectively, the intermediate layer comprises nickel cobalt manganese ternary material positive pole material, bisphenol-S epoxy resin, conductive carbon black SP, polyvinylidene fluoride, and the quality accounts for the ratio and is 80%, 1%, 11%, 8% respectively, the active layer comprises nickel cobalt manganese ternary material positive pole material, bisphenol-S epoxy resin, conductive carbon black SP, polyvinylidene fluoride, and the quality accounts for the ratio and is 75%, 3%, 12%, 10% respectively.
The schematic cross-sectional view of the positive electrode sheet is shown in fig. 1, wherein 1.1 is an active layer, 1.2 is an intermediate layer, 1.3 is a substrate layer, and 2 is a current collector.
Example 2
This embodiment provides a positive pole piece, positive pole piece include the aluminium foil mass collector with set up in the basal layer that the thickness on aluminium foil mass collector surface is 80 μm, the intermediate level that thickness is 30 μm and the active layer that thickness is 20 μm, wherein, the basal layer comprises nickel cobalt manganese ternary material positive pole material, bisphenol-S epoxy resin, conductive carbon black SP, polyvinylidene fluoride, and the quality accounts for the ratio and is 90%, 0.5%, 5%, 4.5% respectively, the intermediate layer comprises nickel cobalt manganese ternary material positive pole material, bisphenol-S epoxy resin, conductive carbon black SP, polyvinylidene fluoride, and the quality accounts for the ratio and is 80%, 1%, 10%, 9% respectively, the active layer comprises nickel cobalt manganese ternary material positive pole material, bisphenol-S epoxy resin, conductive carbon black SP, polyvinylidene fluoride, and the quality accounts for the ratio and is 70%, 3%, 17%, 10% respectively.
Example 3
This example differs from example 1 only in that the material compositions of the base layer, intermediate layer and active layer are identical (all using the material ratios of the base layer).
Example 4
The present example is different from example 1 only in that the mass fraction of the base layer bisphenol-S epoxy resin is 0.3% (the reduction part is replaced by nickel-cobalt-manganese ternary material), and other conditions and parameters are completely the same as example 1.
Example 5
The present example is different from example 1 only in that the mass fraction of the base bisphenol-S epoxy resin is 1.5% (the added part is subtracted by the nickel-cobalt-manganese ternary material), and other conditions and parameters are completely the same as those of example 1.
Example 6
The difference between the present example and example 1 is only that the mass fraction of the bisphenol-S epoxy resin in the intermediate layer is 0.3% (the reduction part is replaced by a nickel-cobalt-manganese ternary material), and the other conditions and parameters are completely the same as those in example 1.
Example 7
The present example is different from example 1 only in that the mass fraction of the bisphenol-S epoxy resin in the intermediate layer is 1.5% (the added part is subtracted by the ternary material of nickel cobalt manganese), and other conditions and parameters are completely the same as those in example 1.
Example 8
The difference between the present example and example 1 is only that the mass fraction of the active layer bisphenol-S epoxy resin is 0.5% (the reduction part is replaced by a nickel-cobalt-manganese ternary material), and other conditions and parameters are exactly the same as those in example 1.
Example 9
This example is different from example 1 only in that the active layer bisphenol-S epoxy resin has a mass fraction of 4% (the added part is subtracted from the nickel-cobalt-manganese ternary material), and the other conditions and parameters are identical to those of example 1.
Comparative example 10
The comparative example is different from example 1 only in that a nickel-cobalt-manganese ternary material cathode material, bisphenol-S epoxy resin, conductive carbon black SP and polyvinylidene fluoride are directly mixed with a solvent in the process of preparing each layer of slurry, and other conditions and parameters are completely the same as those of example 1.
Comparative example 1
This comparative example differs from example 1 only in that the bisphenol-S epoxy resin (BPSER) material was not added, and the other conditions and parameters were exactly the same as in example 1.
Comparative example 2
This comparative example is different from example 1 only in that an active layer is not provided, and other conditions and parameters are exactly the same as those of example 1.
And (3) performance testing:
the positive electrode plates obtained in examples 1-9 and comparative examples 1-2 were mixed with corresponding graphite negative electrode plates, 12 μ M PP + PE separators, and 1.0M LiPF 6 EC + EMC electricityThe electrolyte is matched, the diaphragm is positioned between the positive electrode and the negative electrode, then the bare cell is obtained by winding or laminating, the bare cell is arranged in an outer package aluminum-plastic film or an aluminum shell to be assembled into a cell, the electrolyte is injected into the dried cell, the lithium ion battery is obtained by aging, formation, shaping, packaging and other processes, the lithium ion battery is subjected to cycle performance test and safety performance test, and the test results are shown in table 1:
TABLE 1
Figure BDA0003936812130000081
Figure BDA0003936812130000091
As can be seen from table 1, the retention rate of the capacity of the positive electrode sheet of the present invention after 500 cycles can reach 97% or more, and the positive electrode sheet can pass through needling, extrusion and noon impact tests by 100%, and exhibits good electrochemical performance and safety performance, as can be seen from examples 1-2.
Compared with the embodiment 1, the embodiment 3 and the comparative example 2, the invention ensures that the BPSER does not influence the normal operation of the lithium ion battery through the difference design of the substrate layer, the intermediate layer and the active layer and the mixing sequence design of key materials.
It can be seen from comparison between example 1 and examples 4 to 9 that the electrical properties and safety properties of the prepared electrode sheet are significantly affected by the mass ratio of the bisphenol-S epoxy resin (BPSER) material in the base layer, the intermediate layer and the active layer of the positive electrode sheet, the mass ratio of the bisphenol-S epoxy resin (BPSER) material in the base layer is controlled to be 0.5 to 1%, the mass ratio of the bisphenol-S epoxy resin (BPSER) material in the intermediate layer is controlled to be 0.5 to 1%, the mass ratio of the bisphenol-S epoxy resin (BPSER) material in the active layer is controlled to be 1 to 3%, the prepared positive electrode sheet can give consideration to both the good electrical properties and safety properties of each layer, if the mass ratio of the bisphenol-S epoxy resin (BPSER) material is too high, the safety properties are not affected, but the electrochemical properties are significantly affected, and if the mass ratio of the bisphenol-S epoxy resin (BPSER) material is too low, the safety properties are drastically reduced.
It can be seen from the comparison between example 1 and example 10 that, in the preparation process of the positive electrode plate, the amount of the conductive agent and the bisphenol-S epoxy resin added in each step significantly affects the performance of the prepared positive electrode plate, and needs to be strictly controlled, and BPSER is non-conductive and does not participate in the electrochemical reaction, and if a traditional homogenization method is adopted, BPSER can significantly reduce the electrochemical performance of the positive electrode plate.
Compared with the comparative example 1, the bisphenol-S epoxy resin (BPSER) material is added into the coating of the traditional lithium ion battery anode material, is insoluble in electrolyte, and can quickly and effectively form an insulating layer to cut off electrochemical reaction and improve the high-temperature safety performance of the battery under the condition that the lithium ion battery suddenly heats up due to short circuit or fault and a diaphragm fails.
The applicant declares that the above description is only a specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and it should be understood by those skilled in the art that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention disclosed herein fall within the scope and disclosure of the present invention.

Claims (10)

1. The positive pole piece is characterized by comprising a positive pole current collector, and a basal layer, an intermediate layer and an active layer which are sequentially arranged on the surface of the positive pole current collector in a stacked manner, wherein the basal layer, the intermediate layer and the active layer all contain bisphenol-S epoxy resin.
2. The positive electrode sheet according to claim 1, wherein the base layer further comprises a positive electrode active material, a conductive agent, and a binder;
preferably, the mass fraction of the positive electrode active material is 60 to 75% based on 100% by mass of the base layer;
preferably, the mass fraction of the bisphenol-S epoxy resin is 1-3%;
preferably, the mass fraction of the conductive agent is 15-25%;
preferably, the mass fraction of the binder is 8 to 15%.
3. The positive electrode sheet according to claim 1 or 2, wherein the base layer has a thickness of 10 to 30 μm.
4. The positive electrode sheet according to any one of claims 1 to 3, wherein the intermediate layer further comprises a positive electrode active material, a conductive agent and a binder;
preferably, the mass fraction of the positive electrode active material is 70 to 85% based on 100% by mass of the intermediate layer;
preferably, the mass fraction of the bisphenol-S epoxy resin is 0.5-1%;
preferably, the mass fraction of the conductive agent is 10-15%;
preferably, the mass fraction of the binder is 5 to 10%.
5. The positive electrode sheet according to any one of claims 1 to 4, wherein the intermediate layer has a thickness of 20 to 50 μm.
6. The positive electrode sheet according to any one of claims 1 to 5, wherein the active layer further comprises a positive electrode active material, a conductive agent and a binder;
preferably, the mass fraction of the positive electrode active material is 75 to 90% based on 100% by mass of the active layer;
preferably, the mass fraction of the bisphenol-S epoxy resin is 0.5-1%;
preferably, the mass fraction of the conductive agent is 5-10%;
preferably, the mass fraction of the binder is 4 to 10%.
7. The positive electrode sheet according to any one of claims 1 to 6, wherein the active layer has a thickness of 50 to 100 μm.
8. A preparation method of the positive pole piece according to any one of claims 1 to 7, characterized by comprising the following steps:
(1) Respectively according to the proportion of each material in the basal layer, the middle layer and the active layer, uniformly mixing all the positive active materials with the designed mass and the conductive agent with the designed mass of 2/3, adding the binder with the designed mass of 1/2, continuously and uniformly mixing to form slurry 1, uniformly mixing all the bisphenol-S epoxy resin with the designed mass and the conductive agent with the designed mass of 1/3, adding the binder with the designed mass of 1/2, continuously and uniformly mixing to form slurry 2, and uniformly mixing the slurry 1 and the slurry 2 for coating;
(2) And coating the base layer slurry, the intermediate layer slurry and the active layer slurry on the surface of the positive current collector in sequence and drying to obtain the positive pole piece.
9. The method of claim 8, wherein the temperature of the drying in step (2) is < 120 ℃.
10. A lithium ion battery comprising the positive electrode sheet according to any one of claims 1 to 7.
CN202211406512.9A 2022-11-10 2022-11-10 Positive pole piece and preparation method and application thereof Pending CN115566139A (en)

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Application Number Priority Date Filing Date Title
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