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CN114843448A - Method for relieving corrosion of electrode plate, electrode plate and lithium ion battery - Google Patents

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

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Publication number
CN114843448A
CN114843448A CN202210646044.6A CN202210646044A CN114843448A CN 114843448 A CN114843448 A CN 114843448A CN 202210646044 A CN202210646044 A CN 202210646044A CN 114843448 A CN114843448 A CN 114843448A
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conductive
electrode
current collector
protective layer
polymer material
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CN114843448B (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 corrosion of an electrode plate, the electrode plate and a lithium ion battery. In this application, electrode plate covers the electrically conductive protective layer on the mass flow body, effectively alleviates long-term use in-process thick liquids layer and drops and lead to the condition that the mass flow body corrodes, and because the electrically conductive protective layer is formed by the macromolecular material that can electrically conduct, reduces the interface contact on mass flow body and thick liquids layer for the electrochemical performance of battery can promote.

Description

Method for relieving corrosion of electrode plate, electrode plate and lithium ion battery
Technical Field
The invention relates to the field of secondary batteries, in particular to a method for relieving corrosion of an electrode plate, the electrode plate and a lithium ion battery.
Background
With the continuous development and progress of lithium ion batteries, higher requirements are placed on the aspects of the rate of lithium ion batteries, the retention rate of cycle capacity, energy density and the like. Besides the influence of the negative electrode material, the contact between the pole piece and the coating material and the formula of the conductive agent also have important influence on the aspects of the battery multiplying power, the circulating capacity retention rate, the energy density, the glass strength of the pole piece and the like. In the prior art, the preparation of the pole piece mainly mixes the slurry, the conductive agent and the binder, and the mixture is directly coated on the current collector according to a certain surface density, so that the situation that the negative coating material falls off and the current collector is corroded by the electrolyte due to the failure of the binder often occurs in the long-term use process.
Therefore, there is a great need to find corrosion resistant electrode plates or methods to mitigate corrosion of the plates.
Disclosure of Invention
The invention aims to provide an electrode plate.
The invention also aims to provide a preparation method of the electrode plate.
Another object of the present invention is to provide a method for mitigating corrosion of an electrode pad.
The invention also aims to provide a lithium ion battery containing the electrode pole piece.
In order to solve the above technical problem, a first aspect of the present invention provides an electrode sheet, including:
a current collector;
a conductive protective layer covering the current collector; and
a slurry layer covering the conductive protection layer;
the conductive protection layer comprises a conductive high polymer material.
In some preferred embodiments, the conductive polymer material includes at least one polymer or a derivative thereof selected from the group consisting of: polyacetylene; polypyrrole; a polythiophene; poly (p-phenylene vinylene); polyaniline; polyvinylbenzene sulfonic acid; polyethylene dioxythiophene, and at least two monomers selected from acetylene, pyrrole, thiophene, p-styrene, benzene, ethylene benzene sulfonic acid, aniline, 3, 4-ethylene dioxythiophene copolymer.
In some preferred embodiments, the conductive polymer material is a mixture of polyethylene dioxythiophene and polystyrene sulfonate.
In some preferred embodiments, the conductive polymer material is a copolymer of 3, 4-ethylenedioxythiophene and styrene sulfonic acid.
In some preferred embodiments, the conductive polymer material is polyaniline.
In some preferred embodiments, the conductive polymer material is a mixture of polyethylene dioxythiophene, polystyrene sulfonate and polyaniline.
In some preferred schemes, the electrode plate is a negative electrode plate, and the slurry layer comprises 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 includes carbon fibers and carbon nanotubes.
The second aspect of the present invention provides a method for preparing an electrode sheet, comprising the steps of:
coating the conductive high 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 piece.
In some preferred embodiments, the conductive polymer 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 current collector with a mixture of polyethylene dioxythiophene and polystyrene sulfonate or polyaniline, and forming 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:
heat treating the carbon black;
and/or, subjecting the carbon black to acid treatment.
A third aspect of the invention provides a method of mitigating corrosion of an electrode sheet, the method comprising the steps of:
and coating the conductive high polymer material on the current collector to form a conductive protective layer on the current collector, and coating the electrode slurry on the conductive protective layer.
A fourth aspect of the invention provides a lithium ion battery comprising 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 of the first aspect of the present 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 conductive protective layer is covered on the current collector, so that the situation that the current collector is corroded due to the falling of the slurry layer in the long-term use process is effectively relieved, and the interface contact between the current collector and the slurry layer is reduced because the conductive protective layer is made of a conductive high polymer material, so that the electrochemical performance of the battery is improved;
(2) according to the electrode plate provided by the first aspect of the invention, the conductive protection layer has partial flexibility, so that the electrode plate can buffer the expansion of the electrode plate and relieve the damage of a current collector caused by the expansion of materials;
(3) the electrode pole piece provided by some preferred embodiments of the invention uses the conductive high polymer material with excellent conductivity and better affinity with the electrolyte, so that the rate capability of the battery is further improved, and the internal resistance of the battery is reduced.
It is to be understood that within the scope of the present invention, the above-described features of the present invention and those specifically described below (e.g., in the examples) may be combined with each other to form new or preferred embodiments. Not to be reiterated herein, but to the extent of space.
Detailed Description
In the prior art, a slurry layer coated on a current collector cracks or loosens, so that the current collector is often corroded by electrolyte. In order to relieve the phenomenon, the inventor develops a corrosion-resistant electrode plate through detailed and thorough experiments, wherein a conductive protective layer is added in a current collector and a slurry layer, the slurry layer is not easy to crack or loosen due to the buffering effect of the conductive protective layer, and even if the slurry layer cracks slightly, electrolyte cannot directly contact the current collector, so that the corrosion phenomenon of the electrode plate is relieved. In addition, the conductive protective layer is made of conductive high 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 slurry layer covering the conductive protection layer;
the conductive protection layer comprises a conductive high polymer material.
In some preferred embodiments, the conductive polymer material includes at least one polymer or a derivative thereof selected from the group consisting of: polyacetylene; polypyrrole; a polythiophene; poly (p-phenylene vinylene); polyaniline; polyvinylbenzene sulfonic acid; polyethylene dioxythiophene, and at least two kinds of monomer copolymer selected from acetylene, pyrrole, thiophene, p-styrene, benzene, styrene sulfonic acid, aniline, 3, 4-ethylene dioxythiophene.
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 styrene 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 aspects, the conductive agent includes at least one of carbon black, carbon fiber, and carbon nanotube.
In some preferred embodiments, the carbon black is preferably an at least partially oxidized carbon black.
In some preferred embodiments, the conductive agent comprises oxidized carbon black.
In some preferred aspects, the conductive agent includes oxidized carbon black, and at least one of carbon fibers and carbon nanotubes.
In some preferred aspects, the conductive agent includes oxidized carbon black, carbon fiber, and carbon nanotube.
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 0.1 to 1 μm.
In some preferred schemes, the electrode pole piece is a positive pole piece or a negative pole piece.
In some preferred schemes, the electrode plate is a negative electrode plate; and the electrode active material contains silicon and carbon.
Because the theoretical specific capacity of the silicon/carbon negative electrode is far higher than that of a commercial graphite negative electrode, the silicon/carbon negative electrode has serious volume expansion in the charging and discharging process, the pole piece is easy to crack, and the conductivity of the silicon/carbon negative electrode is not as good as that of the graphite negative electrode. In order to simultaneously realize the buffer of the volume change of the silicon/carbon negative electrode and the improvement of the conductivity of the silicon/carbon negative electrode, in some more preferred embodiments of the invention, the electrode pole piece is a negative pole piece; the electrode active material contains silicon and carbon; and is provided with
The conductive high polymer material is a mixture of polyethylene dioxythiophene and polystyrene sulfonate. The inventors found that the conductivity and rate capability of a silicon/carbon anode can be improved more significantly by using a conductive protective layer formed from a mixture of polyethylenedioxythiophene and polystyrene sulfonate in 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 high polymer material is a mixture of polyethylene dioxythiophene and polystyrene sulfonate. The inventor finds that when the conductive agent comprises the oxidized carbon black, hydroxyl on the surface of the conductive agent can be connected with a sulfonic acid group 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 expansion 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 high polymer material is polyaniline. The inventor finds that when the conductive agent comprises oxidized carbon black, carboxyl on the surface of the conductive agent can be connected with amine bonds in polyaniline of the conductive polymer material layer, and similarly, the conductive protective layer and the slurry layer are combined more tightly, and the expansion phenomenon of the silicon-carbon negative electrode is further relieved.
In some more preferred schemes, the electrode pole piece is a negative pole piece; the electrode active material contains silicon and carbon; the conductive agent further includes carbon nanotubes and carbon fibers. The inventor finds that the conductive agent simultaneously comprises oxidized carbon black, carbon nanotubes and carbon fibers, and the carbon nanotube (such as single-walled carbon nanotube) conductive agent is wound on the carbon fibers by taking the carbon fiber conductive agent as a guide to better bridge a silicon negative electrode, and the expansion of the silicon carbon negative electrode is further limited by the rigidity of the carbon fibers.
In some embodiments of the present invention, there is provided a method for preparing an electrode sheet, the method comprising the steps of:
coating the conductive high 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 piece.
In some preferred schemes, the conductive polymer material is a mixture of polyethylene dioxythiophene and polystyrene sulfonate; and is
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 conductive polymer material is polyaniline; and is
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 schemes, the conductive polymer material is a mixture of polyethylene dioxythiophene, polystyrene sulfonate and polyaniline; and is
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: heat treating the carbon black;
or, subjecting the carbon black to acid treatment;
alternatively, the carbon black is subjected to both heat and acid treatment;
or, the carbon black is sequentially subjected to heat treatment and acid treatment;
alternatively, the carbon black is subjected to acid treatment and heat treatment in this order.
In some preferred embodiments, the method comprises the steps of: coating a current collector with a mixture of polyethylene dioxythiophene and polystyrene sulfonate 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 by using 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, there is provided a method of mitigating corrosion of an electrode sheet, the method comprising the steps of:
coating a conductive high 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.
Some embodiments of the present invention provide a lithium ion battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte,
wherein the electrode sheet 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 the electrode sheets according to the first aspect of the present invention.
As a method for preparing the lithium ion battery of the present invention, a method commonly used in the art can be referred to. In some embodiments of the present 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 (the 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 electrolytic solution is a lithium main body, the positive electrode active material constituting the positive electrode (ii) is not particularly limited as long as it is a material that can be charged and discharged, and examples thereof include materials containing at least one selected from the group consisting of (a) a lithium transition metal composite oxide containing at least one or more metals of nickel, manganese, and cobalt and having a layered structure, (B) a lithium manganese composite oxide having a spinel structure, (C) a lithium-containing olivine-type phosphate, and (D) a lithium-excess layered transition metal oxide having a layered rock-salt structure.
As the negative electrode, a negative electrode active material layer (the same as the negative electrode slurry layer herein) and a current collector are included, and as the negative electrode active material, a material capable of inserting and extracting lithium is used. Including, but not limited to, carbon materials such as crystalline carbon (natural graphite, artificial graphite, and the like), 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 also be lithium metal or a metal material that can form an alloy 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 two or more of them may be used in combination. From the viewpoint of high energy density, a carbon material such as graphite and an Si-based active material such as Si, an Si alloy, and an Si oxide may be combined as the negative electrode active material. From the viewpoint of both cycle characteristics and high energy density, graphite and an Si-based active material may be combined as the negative electrode active material. In the combination, 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, where a silicon/carbon negative electrode is used, the phrase "the electrode active material includes silicon and carbon" refers to a carbon material such as negative electrode active material graphite and a Si-based active material such as Si, Si alloy, Si oxide.
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 electrolytic solution in the present invention, a nonaqueous solvent, a lithium salt and an additive are included as known to those skilled in the art.
The separator is not particularly limited, and an aluminum laminated film, an SUS laminated film, a silicon oxide-coated polypropylene, a polyethylene-coated laminated film, 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 "conductable polymeric material" refers to an organic polymeric material containing a pi-electron conjugated structure that can be converted from an insulator to a conductor or semiconductor after chemical or electrochemical doping.
As used herein, a "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 monomers in which at least one hydrogen in the original monomer is replaced by C 1-4 Alkyl radical, C 2-4 Alkenyl or C 3-6 Alkoxy, etc., and in one embodiment of the present invention, the polyethylenedioxythiophene is substituted with the original monomer
Figure BDA0003685947250000071
Polymerization formation of the original monomer in the derivative of polyethylene dioxythiophene
Figure BDA0003685947250000072
In which at least one hydrogen is replaced by C 1-4 Alkyl radical, C 2-4 Alkenyl or C 3-6 Alkoxy substitution to form derivative monomers
Figure BDA0003685947250000073
(R 1 And R 2 Independently of one another is hydrogen, C 1-4 Alkyl radical, C 2-4 Alkenyl or C 3-6 Alkoxy, and R 1 And R 2 Not simultaneously hydrogen), the derivative of the polyethylene dioxythiophene is formed by polymerizing the derivative monomer;
alternatively, 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 polyphenylsulfonic acid is a polyphenylsulfonate, preferably sodium polyphenylsulfonate.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the present invention is further described below with reference to specific embodiments. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. The experimental procedures, in which specific conditions are not noted in the following examples, are generally carried out under conventional conditions or conditions recommended by the manufacturers. Unless otherwise indicated, percentages and parts are percentages and parts by weight. The test materials and reagents used in the following examples are commercially available without specific reference.
Unless otherwise defined, 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, and it is to be noted that the terms used herein are merely for describing particular embodiments and are not intended to limit exemplary embodiments of the present application.
Example 1 preparation of Si/C negative electrode sheet
(1) Coating conductive high polymer material on the negative current collector to form a conductive protective layer
Taking an aluminum foil with the thickness of about 8 mu m as a negative current collector, coating the mixture of polyethylene dioxythiophene and polystyrene sulfonate in a ratio of 1:3 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) Coating the negative electrode slurry on a 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 wt% of a silicon-carbon material (20% of silicon and 80% of graphite) as a negative electrode active material, 1 wt% of carbon black, a carbon nanotube and carbon fiber mixture as a conductive agent, 1 wt% of SBR as a binder, and 1 wt% of CMC as a thickener in water. Coating the negative electrode slurry on one side of a negative electrode current collector coated with a conductive high polymer material, irradiating for 180 minutes by using an ultraviolet lamp, drying, and then rolling and die-cutting the negative electrode slurry to obtain a negative electrode sheet.
Example 2 preparation of Si/C negative electrode sheet
(1) Coating conductive high polymer material on the negative current collector to form a conductive protective layer
Taking an aluminum foil with the thickness of about 8 mu m as a negative current collector, coating the mixture of polyethylene dioxythiophene and polystyrene sulfonate in a ratio of 1:3 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) Coating the negative electrode slurry on a conductive polymer material
Pretreatment of a conductive agent: the carbon black is treated at high temperature to grow hydroxyl or carboxyl functional groups on the surface.
A negative electrode slurry was prepared by dissolving 97 wt% of a silicon-carbon material (20% of silicon and 80% of graphite) as a negative electrode active material, 1 wt% of carbon black as a conductive agent, 1 wt% of SBR as a binder, and 1 wt% of CMC as a thickener in water. Coating the negative electrode slurry on one side of a negative electrode current collector coated with a conductive high polymer material, irradiating for 180 minutes by using an ultraviolet lamp, drying, and then rolling and die-cutting the negative electrode slurry to obtain a negative electrode sheet.
Example 3 preparation of Si/C negative electrode sheet
(1) Coating conductive high polymer material on the negative current collector to form a conductive protective layer
Taking an 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) Coating the negative electrode slurry on a 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 wt% of a silicon-carbon material (20% of silicon and 80% of graphite) as a negative electrode active material, 1 wt% of carbon black, a carbon nanotube and carbon fiber mixture as a conductive agent, 1 wt% of SBR as a binder, and 1 wt% of CMC as a thickener in water. Coating the negative electrode slurry on one side of a negative electrode current collector coated with a conductive high polymer material, irradiating for 180 minutes by using an ultraviolet lamp, drying, and then rolling and die-cutting the negative electrode slurry to obtain a negative electrode sheet.
Example 4 preparation of Si/C negative electrode sheet
(1) Coating conductive high polymer material on the negative current collector to form a conductive protective layer
Taking an aluminum foil with the thickness of about 8um as a negative current collector, coating polypyrrole 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) Coating the negative electrode slurry on a 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 wt% of a silicon-carbon material (20% of silicon and 80% of graphite) as a negative electrode active material, 1 wt% of carbon black, a carbon nanotube and carbon fiber mixture as a conductive agent, 1 wt% of SBR as a binder, and 1 wt% of CMC as a thickener in water. Coating the negative electrode slurry on one side of a negative electrode current collector coated with a conductive high polymer material, irradiating for 180 minutes by using an ultraviolet lamp, drying, and then rolling and die-cutting the negative electrode slurry to obtain a negative electrode sheet.
Example 5 preparation of graphite negative electrode sheet
(1) Coating conductive high polymer material on the negative current collector to form a conductive protective layer
Taking an aluminum foil with the thickness of about 8 mu m as a negative current collector, coating the mixture of polyethylene dioxythiophene and polystyrene sulfonate in a ratio of 1:3 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) Coating the negative electrode slurry on a 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 wt% of a silicon-carbon material (20% of silicon and 80% of graphite) as a negative electrode active material, 1 wt% of carbon black, a carbon nanotube and carbon fiber mixture as a conductive agent, 1 wt% of SBR as a binder, and 1 wt% of CMC as a thickener in water. And coating the negative electrode slurry on one side of the negative electrode current collector coated with the conductive high polymer material, irradiating for 180 minutes by using an ultraviolet lamp, drying, and then rolling and die-cutting the negative electrode slurry to obtain the negative electrode sheet.
Example 6 preparation of Si/C negative electrode sheet
(1) Coating conductive high polymer material on the negative current collector to form a conductive protective layer
Taking an aluminum foil with the thickness of about 8 mu m as a negative current collector, coating the mixture of polyethylene dioxythiophene and polystyrene sulfonate in a ratio of 1:1 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) Coating the negative electrode slurry on a 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 wt% of a silicon-carbon material (20% of silicon and 80% of graphite) as a negative electrode active material, 1 wt% of carbon black, a carbon nanotube and carbon fiber mixture as a conductive agent, 1 wt% of SBR as a binder, and 1 wt% of CMC as a thickener in water. Coating the negative electrode slurry on one side of a negative electrode current collector coated with a conductive high polymer material, irradiating for 180 minutes by using an ultraviolet lamp, drying, and then rolling and die-cutting the negative electrode slurry to obtain a negative electrode sheet.
Comparative example 1 preparation of negative electrode sheet
The method of preparing the negative electrode sheet in comparative example 1 was substantially the same as example 1 except that the conductive protective layer was not coated.
Comparative example 2 preparation of negative electrode sheet
The method of preparing the negative electrode sheet in comparative example 2 was substantially the same as example 5, except that the conductive protective layer was not coated.
Example 7 preparation of Positive electrode sheet
(1) Conductive high polymer material coated on positive current collector
Taking a copper foil with the thickness of about 15 mu m as a positive current collector, coating a mixture of polyethylene dioxythiophene and polystyrene sulfonate in a ratio of 1:3 on two sides of the positive 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 positive electrode slurry is coated on the conductive high polymer material
A positive electrode slurry was prepared by adding 97 wt% of lithium iron phosphate as a positive electrode active material, 2 wt% of carbon black as a conductive agent, and 1 wt% of PVDF as a binder to NMP as a solvent. Coating the positive electrode slurry on one side of a positive electrode current collector coated with a conductive high polymer material, irradiating for 180 minutes by using an ultraviolet lamp, drying, and then rolling and die-cutting the positive electrode slurry to obtain the positive electrode plate.
Comparative example 3 preparation of Positive electrode sheet
The method of preparing the positive electrode sheet in comparative example 3 is substantially the same as example 7 except that the conductive protective layer is not coated.
[ preparation of lithium ion batteries ]
The negative electrode sheets prepared in examples 1 to 6 were assembled with the positive electrode sheet prepared in example 7 to prepare a lithium ion battery, specifically: the positive electrode sheet and the negative electrode sheet were produced together with a separator formed of three layers of PP/PE/PP in a conventional manner to prepare a laminate pouch battery, and then a nonaqueous electrolytic solution (10% by mass of lithium hexafluorophosphate dissolved in a nonaqueous solvent system having EC: EMC ═ 1: 3) was injected to obtain a lithium ion battery.
[ Battery Performance test ]
The soft package battery prepared by the method is subjected to the following battery performance test, and the result is recorded in table 1.
(1) Rate capability test
Adopt the battery performance test system (test cabinet) of the Shenghong electrical apparatus member electrical limited company, equipment model: and BTS05/10C8D-HP, placing the prepared lithium ion battery in a test cabinet for testing, testing the discharge capacity of the battery at 3C and the discharge capacity at 0.33C, and dividing the discharge capacity at 3C by the discharge capacity at 0.33C to obtain the 3C capacity retention rate.
(2) DC internal resistance test
Adopt flourishing electronic apparatus share electric limited company battery capability test system (test cabinet), equipment model: BTS05/10C8D-HP, the small pouch was placed in a test cabinet for testing, and the cells were tested for discharge DCR at 50% SOC.
(3) Volume resistivity
Adopting a Hitachi resistance meter, and the equipment model is as follows: RM9003, the negative pole piece is cut into small round pieces with the diameter of 14mm, and the test is carried out.
TABLE 1
Figure BDA0003685947250000111
Figure BDA0003685947250000121
It will be understood by those of ordinary skill in the art that the foregoing embodiments are specific examples for 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 in practice.

Claims (12)

1. An electrode sheet, comprising:
a current collector;
a conductive protective layer covering the current collector; and
a slurry layer covering the conductive protection layer;
the conductive protection layer comprises a conductive high polymer material.
2. The electrode sheet according to claim 1, wherein the conductive polymer material comprises at least one polymer or its derivative selected from the group consisting of: polyacetylene; polypyrrole; a polythiophene; poly (p-phenylene vinylene); polyaniline; polyvinylbenzene sulfonic acid; polyethylene dioxythiophene, and at least two monomers selected from acetylene, pyrrole, thiophene, p-styrene, benzene, ethylene benzene sulfonic acid, aniline, 3, 4-ethylene dioxythiophene copolymer.
3. The electrode sheet according to claim 1, wherein the conductive polymer material is a mixture of polyethylene dioxythiophene and polystyrene sulfonate;
or the conductive high polymer material is a copolymer of 3, 4-ethylenedioxythiophene and styrene sulfonic acid;
or the conductive polymer material is polyaniline.
4. The electrode plate according to claim 3, wherein the electrode plate is a negative electrode plate, and the slurry layer comprises 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.
5. The electrode tab of claim 4, wherein the conductive agent further comprises carbon fibers and carbon nanotubes.
6. A preparation method of an electrode plate is characterized by comprising the following steps:
coating a conductive high 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 performing a drying step and a rolling step to obtain the electrode piece.
7. The preparation method according to claim 6, wherein the conductive polymer 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.
8. The method for preparing according to claim 7, characterized in that it comprises the steps of: coating a current collector with a mixture of polyethylene dioxythiophene and polystyrene sulfonate or polyaniline, and forming 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.
9. The method of claim 7 or 8, wherein the step of preparing the oxidized carbon black comprises:
heat treating the carbon black;
and/or, subjecting the carbon black to acid treatment.
10. A method of mitigating corrosion of an electrode sheet, the method comprising the steps of:
and coating the conductive high polymer material on the current collector to form a conductive protective layer on the current collector, and coating the electrode slurry on the conductive protective layer.
11. A method of mitigating corrosion of an electrode sheet, the method comprising the steps of:
and coating the conductive high polymer material on the current collector to form a conductive protective layer on the current collector, and coating the electrode slurry on the conductive protective layer.
12. A lithium ion battery is characterized by comprising a positive electrode, a negative electrode, a diaphragm and electrolyte,
wherein the electrode sheet for the positive electrode and/or the negative electrode is the electrode sheet according to any one of claims 1 to 5.
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