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CN114843448B - Method for relieving electrode plate corrosion, electrode plate and lithium ion battery - Google Patents

Method for relieving electrode plate corrosion, electrode plate and lithium ion battery Download PDF

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Publication number
CN114843448B
CN114843448B CN202210646044.6A CN202210646044A CN114843448B CN 114843448 B CN114843448 B CN 114843448B CN 202210646044 A CN202210646044 A CN 202210646044A CN 114843448 B CN114843448 B CN 114843448B
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electrode
conductive
carbon black
current collector
protective layer
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CN114843448A (en
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闫永思
孙化雨
莫方杰
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Envision Power Technology Jiangsu Co Ltd
Envision Ruitai Power Technology Shanghai Co Ltd
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Envision Power Technology Jiangsu Co Ltd
Envision Ruitai Power Technology Shanghai 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
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • 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
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • 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
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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

Abstract

The application discloses a method for relieving electrode plate corrosion, an electrode plate and a lithium ion battery. According to the application, the electrode plate is covered with the conductive protective layer, so that the condition that the current collector is corroded due to falling of the slurry layer in the long-term use process is effectively relieved, and the conductive protective layer is made of conductive polymer material, so that the interface contact between the current collector and the slurry layer is reduced, and the electrochemical performance of the battery is improved.

Description

Method for relieving electrode plate corrosion, electrode plate and lithium ion battery
Technical Field
The invention relates to the field of secondary batteries, in particular to a method for relieving electrode plate corrosion, an electrode plate and a lithium ion battery.
Background
Along with the continuous development and progress of lithium ion batteries, the lithium ion batteries have higher requirements on the aspects of multiplying power, cycle capacity retention rate, energy density and the like. Besides the influence of the cathode material, the contact between the pole piece and the coating material and the formula of the conductive agent also have critical influence on the aspects of battery multiplying power, circulation capacity retention rate, energy density, pole piece glass strength and the like. In the prior art, the preparation of the pole piece mainly mixes slurry, a conductive agent and a binder, and the slurry, the conductive agent and the binder are directly coated on a current collector according to a certain surface density, and in the long-term use process, the situation that the negative electrode coating material falls off due to the failure of the binder and the current collector is corroded by electrolyte often occurs.
Therefore, there is a great need to find corrosion resistant electrode tabs or methods of mitigating tab corrosion.
Disclosure of Invention
The invention aims to provide an electrode plate.
The invention further aims at providing a preparation method of the electrode plate.
It is another object of the present invention to provide a method of alleviating corrosion of electrode sheets.
Another object of the present invention is to provide a lithium ion battery comprising the electrode tab described above.
To solve the above technical problem, a first aspect of the present invention provides an electrode pad, including:
a current collector;
a conductive protective layer covering the current collector; and
A paste layer covering the conductive protective layer;
the conductive protective layer comprises a conductive polymer material.
In some preferred embodiments, the electrically conductive polymeric material comprises at least one polymer or derivative thereof selected from the group consisting of: polyacetylene; polypyrrole; polythiophene; poly (p-styrene); polyaniline; polyethylene benzene sulfonic acid; polyethylene dioxythiophene, and at least two kinds of monomer copolymer selected from acetylene, pyrrole, thiophene, p-styrene, benzene, vinylbenzene sulfonic acid, aniline, 3, 4-ethylenedioxythiophene.
In some preferred embodiments, the electrically conductive polymeric material is a mixture of polyethylene dioxythiophene and polystyrene sulfonate.
In some preferred embodiments, the electrically conductive polymeric material is a copolymer of 3, 4-ethylenedioxythiophene and vinylbenzenesulfonic acid.
In some preferred embodiments, the electrically conductive polymeric material is polyaniline.
In some preferred embodiments, the electrically conductive polymeric material is a mixture of polyethylene dioxythiophene, polystyrene sulfonate, and polyaniline.
In some preferred embodiments, the electrode sheet is a negative electrode sheet, and the slurry layer includes an electrode active material, a conductive agent, and a binder;
The electrode active material includes silicon and carbon;
The conductive agent includes oxidized carbon black.
In some preferred embodiments, the conductive agent further comprises carbon fibers and carbon nanotubes.
The second aspect of the invention provides a method for preparing an electrode sheet, comprising the steps of:
coating the conductive polymer material on a current collector to form a conductive protective layer on the current collector;
And coating the electrode slurry on the conductive protective layer, and then sequentially carrying out a drying step and a rolling step to obtain the electrode plate.
In some preferred embodiments, the electrically conductive polymeric material is a mixture of polyethylene dioxythiophene and polystyrene sulfonate, or polyaniline.
The electrode slurry includes an electrode active material, a conductive agent, and a binder, wherein the conductive agent includes oxidized carbon black.
In some preferred embodiments, the method comprises the steps of: coating a mixture of polyethylene dioxythiophene and polystyrene sulfonate or polyaniline on a current collector to form a conductive protective layer on the current collector;
Coating electrode slurry containing oxidized carbon black on the conductive protective layer to form an electrode slurry layer, and irradiating the electrode slurry layer with ultraviolet light; and then sequentially carrying out a drying step and a rolling step to obtain the electrode plate.
In some preferred embodiments, the step of preparing the oxidized carbon black comprises:
Subjecting carbon black to a heat treatment;
and/or subjecting the carbon black to an acid treatment.
A third aspect of the present invention provides a method of mitigating electrode pad erosion, the method comprising the steps of:
And coating a conductive polymer material on a current collector to form a conductive protective layer on the current collector, and coating electrode slurry on the conductive protective layer.
A fourth aspect of the present invention provides a lithium ion battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte,
Wherein the electrode plate used by the positive electrode and/or the negative electrode is the electrode plate of the first aspect of the invention.
Compared with the prior art, the invention has at least the following advantages:
(1) According to the electrode plate provided by the first aspect of the invention, the current collector is covered with the conductive protective layer, so that the situation that the current collector is corroded due to falling of the slurry layer in the long-term use process is effectively relieved, and the conductive protective layer is made of conductive high polymer materials, so that the interface contact between the current collector and the slurry layer is reduced, and the electrochemical performance of the battery is improved;
(2) According to the electrode pole piece provided by the first aspect of the invention, the conductive protective layer has partial flexibility, so that buffering can be provided for pole piece expansion, and the damage of a current collector caused by material expansion can be relieved;
(3) According to the electrode plate provided by some preferred embodiments of the invention, a conductive polymer material which is excellent in conductivity and better in affinity with electrolyte is used, so that the rate performance of the battery is further improved, and the internal resistance of the battery is reduced.
It is understood that within the scope of the present invention, the above-described technical features of the present invention and technical features specifically described below (e.g., in the examples) may be combined with each other to constitute new or preferred technical solutions. And are limited to a space, and are not described in detail herein.
Detailed Description
In the prior art, the slurry layer coated on the current collector cracks or loosens, often resulting in corrosion of the current collector by the electrolyte. In order to alleviate the phenomenon, the inventor develops a corrosion-resistant electrode plate through detailed and careful experiments, wherein a conductive protection layer is added in a current collector and a slurry layer, and the slurry layer is not easy to crack or loosen due to the buffer function of the conductive protection layer, and electrolyte cannot directly contact the current collector even if the slurry layer is slightly cracked, so that the corrosion phenomenon of the electrode plate is relieved. In addition, the conductive protective layer is made of conductive polymer materials, so that the interface contact between the current collector and the slurry layer can be reduced, and the electrochemical performance of the battery can be improved. In particular, in some embodiments of the present invention there is provided an electrode pad comprising:
a current collector;
a conductive protective layer covering the current collector; and
A paste layer covering the conductive protective layer;
the conductive protective layer comprises a conductive polymer material.
In some preferred embodiments, the electrically conductive polymeric material comprises at least one polymer or derivative thereof selected from the group consisting of: polyacetylene; polypyrrole; polythiophene; poly (p-styrene); polyaniline; polyethylene benzene sulfonic acid; polyethylene dioxythiophene, and at least two kinds of monomer copolymer selected from acetylene, pyrrole, thiophene, p-styrene, benzene, vinylbenzene sulfonic acid, aniline, 3, 4-ethylenedioxythiophene.
Based on the beneficial effect of improving the conductivity of the electrode plate, in some preferred schemes, the conductive polymer material is a mixture of polyethylene dioxythiophene and polystyrene sulfonate.
Based on the beneficial effect of improving the conductivity of the electrode plate, in some preferred schemes, the conductive polymer material is a copolymer of 3, 4-ethylenedioxythiophene and vinylbenzene sulfonic acid.
Based on the beneficial effect of improving the conductivity of the electrode plate, in some preferred schemes, the conductive polymer material is polyaniline.
In some preferred embodiments, the slurry layer includes an electrode active material, a conductive agent, and a binder.
In some preferred embodiments, the conductive agent includes at least one of carbon black, carbon fiber, and carbon nanotubes.
In some preferred embodiments, the carbon black is preferably at least partially oxidized carbon black.
In some preferred embodiments, the conductive agent comprises oxidized carbon black.
In some preferred embodiments, the conductive agent comprises oxidized carbon black, and at least one of carbon fibers and carbon nanotubes.
In some preferred embodiments, the conductive agent comprises oxidized carbon black, carbon fibers, and carbon nanotubes.
In some preferred embodiments, the conductive protective layer has a thickness of 0.1 to 1 μm.
In some preferred embodiments, the thickness of the slurry layer is from 0.1 to 1 μm.
In some preferred embodiments, the electrode sheet is a positive electrode sheet or a negative electrode sheet.
In some preferred embodiments, the electrode sheet is a negative electrode sheet; and the electrode active material contains silicon and carbon.
Since the theoretical specific capacity of a silicon/carbon anode is much higher than that of a commercial graphite anode, however, the silicon/carbon anode has serious volume expansion in the charge and discharge process, so that the electrode piece is more likely to crack, and the conductivity of the silicon/carbon anode is lower than that of a graphite anode. To simultaneously achieve buffering of the volume change of the silicon/carbon anode and improving the conductivity of the silicon/carbon anode, in some more preferred embodiments of the invention, the electrode sheet is an anode sheet; the electrode active material contains silicon and carbon; and is also provided with
The conductive polymer material is a mixture of polyethylene dioxythiophene and polystyrene sulfonate. The inventors have found that the use of a conductive protective layer formed from a mixture of polyethylene dioxythiophene and polystyrene sulfonate in a silicon-carbon anode can more significantly improve the conductivity and rate capability of the silicon/carbon anode.
In a more preferred embodiment of the present invention, the electrode sheet is a negative electrode sheet; the electrode active material contains silicon and carbon; the conductive agent comprises oxidized carbon black;
The conductive polymer material is a mixture of polyethylene dioxythiophene and polystyrene sulfonate. The inventor finds that when oxidized carbon black is included in the conductive agent, hydroxyl groups on the surface of the conductive agent can be connected with sulfonic acid groups in polystyrene sulfonate of the conductive polymer material layer, so that the conductive protective layer and the slurry layer are combined more tightly, and the swelling phenomenon of the silicon-carbon negative electrode is further relieved.
In a more preferred embodiment of the present invention, the electrode sheet is a negative electrode sheet; the electrode active material contains silicon and carbon; the conductive agent comprises oxidized carbon black;
the conductive polymer material is polyaniline. The inventor finds that when oxidized carbon black is included in the conductive agent, carboxyl groups on the surface of the conductive agent can be connected with amino bonds in polyaniline of the conductive polymer material layer, and as such, the conductive protective layer and the slurry layer are combined more tightly, so that the swelling phenomenon of the silicon-carbon negative electrode is further relieved.
In some more preferred embodiments, the electrode sheet is a negative electrode sheet; the electrode active material contains silicon and carbon; the conductive agent further comprises carbon nanotubes and carbon fibers. The inventor finds that the conductive agent comprises oxidized carbon black, carbon nano tube and carbon fiber, the carbon fiber conductive agent is used as a guide, the carbon nano tube (such as single-wall carbon nano tube) conductive agent is wound on the carbon fiber, so that the silicon negative electrode can be bridged better, and the expansion of the silicon carbon negative electrode is further limited by the rigidity of the carbon fiber.
In some embodiments of the present invention, a method for preparing an electrode sheet is provided, the method comprising the steps of:
coating the conductive polymer material on a current collector to form a conductive protective layer on the current collector;
And coating the electrode slurry on the conductive protective layer, and then sequentially carrying out a drying step and a rolling step to obtain the electrode plate.
In some preferred embodiments, the electrically conductive polymeric material is a mixture of polyethylene dioxythiophene and polystyrene sulfonate; and is also provided with
The electrode slurry includes an electrode active material, a conductive agent, and a binder, wherein the conductive agent includes oxidized carbon black.
In some preferred embodiments, the electrically conductive polymeric material is polyaniline; and is also provided with
The electrode slurry includes an electrode active material, a conductive agent, and a binder, wherein the conductive agent includes oxidized carbon black.
In some preferred embodiments, the electrically conductive polymeric material is a mixture of polyethylene dioxythiophene, polystyrene sulfonate, and polyaniline; and is also provided with
The electrode slurry includes an electrode active material, a conductive agent, and a binder, wherein the conductive agent includes oxidized carbon black.
In some preferred embodiments, the step of preparing the oxidized carbon black comprises: subjecting carbon black to a heat treatment;
Or subjecting the carbon black to an acid treatment;
Or subjecting the carbon black to both heat and acid treatment;
Or subjecting the carbon black to heat treatment and acid treatment in sequence;
or subjecting the carbon black to acid treatment and heat treatment in this order.
In some preferred embodiments, the method comprises the steps of: coating a mixture of polyethylene dioxythiophene and polystyrene sulfonate on a current collector to form a conductive protective layer on the current collector;
Coating electrode slurry containing oxidized carbon black on the conductive protective layer to form a slurry layer, and irradiating the slurry layer with ultraviolet light; and then sequentially carrying out a drying step and a rolling step to obtain the electrode plate.
In some embodiments of the invention, a method of mitigating electrode pad erosion is provided, the method comprising the steps of:
And coating a conductive polymer material on a current collector to form a conductive protective layer on the current collector, and coating electrode slurry on the conductive protective layer.
In some embodiments of the present invention, a lithium ion battery is provided that includes a positive electrode, a negative electrode, a separator, and an electrolyte,
Wherein the electrode sheet used for the positive electrode and/or the negative electrode is the electrode sheet according to the first aspect of the present invention.
In some preferred embodiments, the electrode sheets used for the positive electrode and the negative electrode are both electrode sheets according to the first aspect of the present invention.
As a method for preparing the lithium ion battery of the present invention, reference may be made to a method commonly used in the art. In some embodiments of the invention, the lithium ion battery is a pouch-type (soft pack) secondary battery.
As the positive electrode, it includes a positive electrode active material layer (same as the positive electrode slurry layer herein) and a current collector. As the positive electrode active material layer, it includes a positive electrode active material, a binder, and a conductive agent. As the positive electrode active material, it preferably contains at least one oxide and/or polyanion compound. In the case of a lithium ion battery in which the cation in the nonaqueous electrolyte is a lithium host, the positive electrode active material constituting the positive electrode (ii) is not particularly limited as long as it is a material capable of charge and discharge, and examples thereof include a material containing at least one selected from (a) lithium transition metal composite oxides containing at least one metal selected from nickel, manganese and cobalt and having a layered structure, (B) lithium manganese composite oxides having a spinel structure, (C) lithium-containing olivine-type phosphates, and (D) lithium excess layered transition metal oxides having a layered rock salt type structure.
The negative electrode includes a negative electrode active material layer (similar to the negative electrode slurry layer herein) and a current collector, and the negative electrode active material is a material capable of inserting and extracting lithium. Including, but not limited to, crystalline carbon (natural graphite, artificial graphite, etc.), carbon materials such as amorphous carbon, carbon-coated graphite, and resin-coated graphite, and oxide materials such as indium oxide, silicon oxide, tin oxide, lithium titanate, zinc oxide, and lithium oxide. The negative electrode active material may be lithium metal or a metal material that can be alloyed with lithium. Specific examples of metals that can be alloyed with lithium include Cu, sn, si, co, mn, fe, sb and Ag. Binary or ternary alloys containing these metals and lithium may also be used as the negative electrode active material. These negative electrode active materials may be used alone or in combination of two or more. From the viewpoint of increasing the energy density, a carbon material such as graphite and a Si-based active material such as Si, si alloy, si oxide or the like may be combined as the negative electrode active material. From the standpoint of both cycle characteristics and high energy density, graphite and Si-based active materials may be combined as the negative electrode active material. The ratio of the mass of the Si-based active material to the total mass of the carbon material and the Si-based active material may be 0.5% to 95%, 1% to 50%, or 2% to 40%. For example, in some embodiments of the present invention, a silicon/carbon anode is used, and the "electrode active material includes silicon and carbon" refers to an anode active material such as graphite and an Si-based active material such as Si, si alloy, si oxide and the like.
The binder used for the positive electrode and the negative electrode is not particularly limited, and a binder commonly used in the art may be used.
As the electrolyte in the present invention, nonaqueous solvents, lithium salts, and additives are included as known to those skilled in the art.
The separator is not particularly limited, and an aluminum laminate film, an SUS laminate film, a laminate film of polypropylene, polyethylene, or the like coated with silicon oxide, or the like can be used. In some embodiments of the invention, a separator formed of three layers of PP/PE/PP is used.
As used herein, the term "conductive polymer material" refers to an organic polymer material containing pi-electron conjugated structure that can be converted from an insulator to a conductor or a semiconductor after chemical or electrochemical doping.
As used herein, "derivative of a polymer" refers to a polymer formed from monomers derived from the original monomers from which the polymer was formed, the derived monomers being obtained by substitution of at least one hydrogen in the original monomers with a substituent such as C 1-4 alkyl, C 2-4 alkenyl or C 3-6 alkoxy, in one embodiment of the invention, polyethylene dioxythiophene is derived from the original monomersPolymerization to form, among the derivatives of polyethylene dioxythiophene, the original monomerAt least one hydrogen of which is substituted by C 1-4 alkyl, C 2-4 alkenyl or C 3-6 alkoxy to form a derivative monomer(R 1 and R 2 are independently hydrogen, C 1-4 alkyl, C 2-4 alkenyl or C 3-6 alkoxy, and R 1 and R 2 are not both hydrogen), a derivative of polyethylene dioxythiophene being polymerized from the derivative monomer;
Or when the polymer is an acidic or basic polymer, the "derivative of the polymer" may also be a salt thereof, for example in one embodiment of the invention the derivative of the polyphenylsulphonic acid is a polyphenylsulphonic acid salt, preferably sodium polyphenylsulphonic acid.
The present invention will be further described with reference to specific embodiments in order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent. It is to be understood that these examples are illustrative of the present invention and are not intended to limit the scope of the present invention. The experimental methods, in which specific conditions are not noted in the following examples, are generally conducted under conventional conditions or under conditions recommended by the manufacturer. Percentages and parts are weight percentages and parts unless otherwise indicated. The experimental materials and reagents used in the following examples were obtained from commercial sources unless otherwise specified.
Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs, it is to be noted that the terms used herein are used merely to describe specific embodiments and are not intended to limit exemplary embodiments of the application.
Example 1 preparation of Si/C negative electrode sheet
(1) The cathode current collector is coated with conductive polymer material to form a conductive protective layer
Taking aluminum foil with the thickness of about 8um as a negative current collector, coating a mixture of polyethylene dioxythiophene and polystyrene sulfonate at the two sides of the negative current collector in a ratio of 1:3, drying the pole piece at about 80 ℃, and forming a conductive protective layer on the current collector, wherein the thickness of the conductive protective layer is about 0.1-1 mu m.
(2) The cathode sizing agent is coated on the conductive polymer material
Pretreatment of a conductive agent: mixing carbon black, carbon nano tubes and carbon fibers according to the mass ratio of 5:2:3, and carrying out high-temperature treatment at 300 ℃ to enable hydroxyl or carboxyl functional groups to grow on the surface of the conductive agent.
A negative electrode slurry was prepared by dissolving 97% by weight of a silicon-carbon material (20% of silicon and 80% of graphite) as a negative electrode active material, 1% by weight of carbon black, a carbon nanotube and carbon fiber mixture as a conductive agent, 1% by weight of SBR as a binder, and 1% by weight of CMC as a thickener in water. And (3) coating the negative electrode slurry on one side of the negative electrode current collector coated with the conductive polymer material, irradiating for 180 minutes by using an ultraviolet lamp, drying, and then rolling and die-cutting to obtain the negative electrode plate.
Example 2 preparation of Si/C negative electrode sheet
(1) The cathode current collector is coated with conductive polymer material to form a conductive protective layer
Taking aluminum foil with the thickness of about 8um as a negative current collector, coating a mixture of polyethylene dioxythiophene and polystyrene sulfonate at the two sides of the negative current collector in a ratio of 1:3, drying the pole piece at about 80 ℃, and forming a conductive protective layer on the current collector, wherein the thickness of the conductive protective layer is about 0.1-1 mu m.
(2) The cathode sizing agent is coated on the conductive polymer material
Pretreatment of a conductive agent: the carbon black is treated at high temperature to make the surface grow hydroxyl or carboxyl functional groups.
A negative electrode slurry was prepared by dissolving 97% by weight of a silicon-carbon material (20% of silicon and 80% of graphite) as a negative electrode active material, 1% by weight of carbon black as a conductive agent, 1% by weight of SBR as a binder, and 1% by weight of CMC as a thickener in water. And (3) coating the negative electrode slurry on one side of the negative electrode current collector coated with the conductive polymer material, irradiating for 180 minutes by using an ultraviolet lamp, drying, and then rolling and die-cutting to obtain the negative electrode plate.
Example 3 preparation of Si/C negative electrode sheet
(1) The cathode current collector is coated with conductive polymer material to form a conductive protective layer
Taking aluminum foil with the thickness of about 8um as a negative current collector, coating polyaniline on two sides of the negative current collector, drying the pole piece at about 80 ℃, and forming a conductive protective layer on the current collector, wherein the thickness of the conductive protective layer is about 0.1-1 mu m.
(2) The cathode sizing agent is coated on the conductive polymer material
Pretreatment of a conductive agent: mixing carbon black, carbon nano tubes and carbon fibers according to the mass ratio of 5:2:3, and carrying out high-temperature treatment at 300 ℃ to enable hydroxyl or carboxyl functional groups to grow on the surface of the conductive agent.
A negative electrode slurry was prepared by dissolving 97% by weight of a silicon-carbon material (20% of silicon and 80% of graphite) as a negative electrode active material, 1% by weight of carbon black, a carbon nanotube and carbon fiber mixture as a conductive agent, 1% by weight of SBR as a binder, and 1% by weight of CMC as a thickener in water. The negative electrode slurry is coated on one side of the negative electrode current collector coated with the conductive polymer material, irradiated for 180 minutes by an ultraviolet lamp, dried, and then rolled and die-cut to obtain a negative electrode plate.
Example 4 preparation of Si/C negative electrode sheet
(1) The cathode current collector is coated with conductive polymer material to form a conductive protective layer
Taking aluminum foil with the thickness of about 8um as a negative current collector, coating polypyrrole on two sides of the negative current collector, drying a pole piece at about 80 ℃, and forming a conductive protective layer on the current collector, wherein the thickness of the conductive protective layer is about 0.1-1 mu m.
(2) The cathode sizing agent is coated on the conductive polymer material
Pretreatment of a conductive agent: the carbon black, the carbon nano tube and the carbon fiber are mixed according to the mass ratio of 5:2:3 and subjected to high-temperature treatment at 300 ℃ so that hydroxyl or carboxyl functional groups grow on the surface of the conductive agent.
A negative electrode slurry was prepared by dissolving 97% by weight of a silicon-carbon material (20% of silicon and 80% of graphite) as a negative electrode active material, 1% by weight of carbon black, a carbon nanotube and carbon fiber mixture as a conductive agent, 1% by weight of SBR as a binder, and 1% by weight of CMC as a thickener in water. And (3) coating the negative electrode slurry on one side of the negative electrode current collector coated with the conductive polymer material, irradiating for 180 minutes by using an ultraviolet lamp, drying, and then rolling and die-cutting to obtain the negative electrode plate.
Example 5 preparation of graphite negative electrode sheet
(1) The cathode current collector is coated with conductive polymer material to form a conductive protective layer
Taking aluminum foil with the thickness of about 8um as a negative current collector, coating a mixture of polyethylene dioxythiophene and polystyrene sulfonate at the two sides of the negative current collector in a ratio of 1:3, drying the pole piece at about 80 ℃, and forming a conductive protective layer on the current collector, wherein the thickness of the conductive protective layer is about 0.1-1 mu m.
(2) The cathode sizing agent is coated on the conductive polymer material
Pretreatment of a conductive agent: the carbon black, the carbon nano tube and the carbon fiber are mixed according to the mass ratio of 5:2:3 and subjected to high-temperature treatment at 300 ℃ so that hydroxyl or carboxyl functional groups grow on the surface of the conductive agent.
A negative electrode slurry was prepared by dissolving 97% by weight of a silicon-carbon material (20% of silicon and 80% of graphite) as a negative electrode active material, 1% by weight of carbon black, a carbon nanotube and carbon fiber mixture as a conductive agent, 1% by weight of SBR as a binder, and 1% by weight of CMC as a thickener in water. And (3) coating the negative electrode slurry on one side of the negative electrode current collector coated with the conductive polymer material, irradiating for 180 minutes by using an ultraviolet lamp, drying, and then rolling and die-cutting to obtain the negative electrode plate.
Example 6 preparation of Si/C negative electrode sheet
(1) The cathode current collector is coated with conductive polymer material to form a conductive protective layer
Taking aluminum foil with the thickness of about 8um as a negative current collector, coating a mixture of polyethylene dioxythiophene and polystyrene sulfonate at a ratio of 1:1 on two sides of the negative current collector, drying a pole piece at about 80 ℃, and forming a conductive protective layer on the current collector, wherein the thickness of the conductive protective layer is about 0.1-1 mu m.
(2) The cathode sizing agent is coated on the conductive polymer material
Pretreatment of a conductive agent: mixing carbon black, carbon nano tubes and carbon fibers according to the mass ratio of 5:2:3, and carrying out high-temperature treatment at 300 ℃ to enable hydroxyl or carboxyl functional groups to grow on the surface of the conductive agent.
A negative electrode slurry was prepared by dissolving 97% by weight of a silicon-carbon material (20% of silicon and 80% of graphite) as a negative electrode active material, 1% by weight of carbon black, a carbon nanotube and carbon fiber mixture as a conductive agent, 1% by weight of SBR as a binder, and 1% by weight of CMC as a thickener in water. And (3) coating the negative electrode slurry on one side of the negative electrode current collector coated with the conductive polymer material, irradiating for 180 minutes by using an ultraviolet lamp, drying, and then rolling and die-cutting to obtain the negative electrode plate.
Comparative example 1 preparation of negative electrode sheet
The method for preparing the negative electrode sheet in comparative example 1 was substantially the same as in example 1, except that the conductive protective layer was not coated.
Comparative example 2 preparation of negative electrode sheet
The method for preparing the negative electrode sheet in comparative example 2 was substantially the same as in example 5, except that the conductive protective layer was not coated.
Example 7 preparation of Positive electrode sheet
(1) Positive electrode current collector coated with conductive polymer material
Taking a copper foil with the thickness of about 15um as a positive current collector, coating a mixture of polyethylene dioxythiophene and polystyrene sulfonate at the two sides of the positive current collector in a ratio of 1:3, drying a pole piece at about 80 ℃, and forming a conductive protective layer on the current collector, wherein the thickness of the conductive protective layer is about 0.1-1 mu m.
(2) The positive electrode slurry is coated on the conductive polymer material
97% By weight of lithium iron phosphate as a positive electrode active material, 2% by weight of carbon black as a conductive agent, and 1% by weight of PVDF as a binder were added to NMP as a solvent to prepare a positive electrode slurry. And (3) coating the positive electrode slurry on one side of the positive electrode current collector coated with the conductive polymer material, irradiating for 180 minutes by using an ultraviolet lamp, drying, and then rolling and die-cutting to obtain the positive electrode plate.
Comparative example 3 preparation of Positive electrode sheet
The method for preparing the positive electrode sheet in comparative example 3 was substantially the same as in example 7, except that the conductive protective layer was not coated.
[ Preparation of lithium ion Battery ]
The negative electrode sheets prepared in examples 1 to 6 were assembled with the positive electrode sheet prepared in example 7 to prepare lithium ion batteries, respectively, specifically: the positive electrode sheet and the negative electrode sheet were prepared together with a separator formed of three layers of PP/PE/PP in a conventional manner, and then a nonaqueous electrolyte (10% by mass of lithium hexafluorophosphate was dissolved in a nonaqueous solvent system of EC: emc=1:3) was injected to obtain a lithium ion battery.
[ Battery Performance test ]
The above-prepared soft pack battery was subjected to the following battery performance test, and the results were recorded in table 1.
(1) Rate capability test
Battery performance test system (test cabinet) of Cheng Hong electric appliance shares electric company, equipment model: BTS05/10C8D-HP, the prepared lithium ion battery is placed in a test cabinet for testing, the discharge capacity of the battery under 3C and the discharge capacity under 0.33C are tested, and the discharge capacity under 3C is divided by the discharge capacity under 0.33C to obtain the 3C capacity retention rate.
(2) DC internal resistance test
Battery performance test system (test cabinet) of Cheng Hong electric appliance shares electric company, equipment model: BTS05/10C8D-HP, and the small soft pack was placed in a test cabinet for testing the discharge DCR of the battery at 50% SOC.
(3) Volume resistivity
The Hitachi resistance meter is adopted, and the equipment model is as follows: RM9003, cut the negative pole piece into small round piece with diameter of 14mm, and test.
TABLE 1
It will be understood by those of ordinary skill in the art that the foregoing embodiments are specific examples of carrying out the invention and that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

Claims (8)

1. An electrode pad, characterized in that the electrode pad comprises:
a current collector;
a conductive protective layer covering the current collector; and
A paste layer covering the conductive protective layer;
wherein the conductive protective layer comprises a conductive polymer material;
The conductive polymer material is a mixture of polyethylene dioxythiophene and polystyrene sulfonate in a weight ratio of 1:3; the electrode plate is a negative electrode plate, and the slurry layer comprises electrode active substances, a conductive agent and a binder; and the electrode active material contains silicon and carbon; the conductive agent comprises oxidized carbon black, wherein the oxidized carbon black is obtained by heat treatment of carbon black.
2. The electrode tab of claim 1 wherein the oxidized carbon black is obtained by subjecting carbon black to a high temperature of 300 ℃.
3. The electrode pad of claim 1, wherein the conductive agent further comprises carbon fibers and carbon nanotubes.
4. The preparation method of the electrode plate is characterized by comprising the following steps:
coating a conductive polymer material on a current collector to form a conductive protective layer on the current collector;
coating electrode slurry on the conductive protective layer, and sequentially performing a drying step and a rolling step to obtain the electrode plate;
the conductive polymer material is a mixture of polyethylene dioxythiophene and polystyrene sulfonate in a weight ratio of 1:3;
the electrode plate is a negative electrode plate, and the electrode slurry comprises electrode active substances, a conductive agent and a binder; and the electrode active material contains silicon and carbon; the conductive agent comprises oxidized carbon black, wherein the oxidized carbon black is obtained by heat treatment of carbon black.
5. The method according to claim 4, wherein the oxidized carbon black is obtained by subjecting carbon black to a high temperature of 300 ℃.
6. The method of manufacturing according to claim 5, characterized in that the method comprises the steps of: coating a mixture of polyethylene dioxythiophene and polystyrene sulfonate on a current collector to form a conductive protective layer on the current collector;
Coating electrode slurry containing oxidized carbon black on the conductive protective layer to form an electrode slurry layer, and irradiating the electrode slurry layer with ultraviolet light; and then sequentially carrying out a drying step and a rolling step to obtain the electrode plate.
7. A method of mitigating electrode pad erosion, the method comprising the steps of:
Coating a conductive polymer material on a current collector to form a conductive protective layer on the current collector, and coating electrode slurry on the conductive protective layer; the conductive polymer material is a mixture of polyethylene dioxythiophene and polystyrene sulfonate in a weight ratio of 1:3; the electrode plate is a negative electrode plate, and the electrode slurry comprises electrode active substances, a conductive agent and a binder; and the electrode active material contains silicon and carbon; the conductive agent comprises oxidized carbon black, wherein the oxidized carbon black is obtained by heat treatment of carbon black.
8. A lithium ion battery is characterized by comprising a positive electrode, a negative electrode, a diaphragm and electrolyte,
Wherein the electrode sheet used for the negative electrode is the electrode sheet according to any one of claims 1 to 3.
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