CN115241447A - Composite negative electrode active material and preparation method and application thereof - Google Patents

Composite negative electrode active material and preparation method and application thereof Download PDF

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Publication number
CN115241447A
CN115241447A CN202211060363.5A CN202211060363A CN115241447A CN 115241447 A CN115241447 A CN 115241447A CN 202211060363 A CN202211060363 A CN 202211060363A CN 115241447 A CN115241447 A CN 115241447A
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water
polymer
active material
copolymer
homopolymer
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岳敏
杜宁
王露琪
闫允涛
张瑞
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Zhejiang Coyi New Energy Co ltd
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Zhejiang Coyi New Energy 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/133—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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • 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 Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Composite Materials (AREA)
  • Inorganic Chemistry (AREA)
  • Battery Electrode And Active Subsutance (AREA)

Abstract

The invention provides a composite negative active material and a preparation method and application thereof. The composite negative active material includes a polymer, a conductive material, and a negative active material, the polymer including a water-soluble polymer and a water-insoluble polymer in combination or a water-soluble polymer. The composite negative active material provided by the invention can greatly improve the manufacturing efficiency of the lithium battery, reduce the manufacturing cost of the lithium battery, improve the cycle performance of the battery and reduce the expansion rate of the electrode.

Description

Composite negative electrode active material and preparation method and application thereof
Technical Field
The invention belongs to the technical field of negative electrode materials, and particularly relates to a composite negative electrode active material and a preparation method and application thereof.
Background
In recent years, in order to further meet the demand of product electromotion, especially the rapid development in the fields of electronic products and electric vehicles, how to improve the productivity of lithium ion batteries also faces a series of problems. Currently, the demand of lithium ion batteries in the market is increasing, and the cost requirement for controlling the lithium ion batteries is also increasing.
In the production process of the lithium ion battery, the slurry mixing process is an important part of the production process. The slurry after slurry mixing needs to have good stability, which is one of the important indexes for ensuring the consistency and the production efficiency of the battery in the production process of the battery. In the prior art, the slurry mixing process of the negative electrode material needs to perform the steps of dissolving carboxymethyl cellulose (CMC), dispersing a conductive agent, dispersing the negative electrode material, dispersing a binder and the like, so that a long time needs to be consumed, and the production efficiency and the manufacturing cost of the battery are seriously influenced. In addition, the conventional wet dispersion process has a problem of easily causing agglomeration of the conductive agent and the binder, thereby causing poor electrochemical performance of the battery. CN112713257A discloses a preparation method of negative electrode slurry, which specifically comprises the following steps: firstly, mixing a negative electrode active material, conductive agent powder and water to obtain wetting slurry; adding thickening agent powder in three steps, adding water, and stirring to obtain slurry with preset solid content; and finally, adding the aqueous solution of the binder, and stirring to obtain the cathode slurry. Although the slurry prepared by the method does not need a preparation process of glue solution, the operation steps are more complicated, and the production efficiency of the battery is reduced.
Therefore, in the field, it is urgently needed to develop a negative electrode material, and a preparation method of the negative electrode material is simple to operate, and can improve the production efficiency of the lithium ion battery and reduce the production cost of the battery, and meanwhile, the lithium ion battery prepared from the negative electrode material has good electrochemical performance.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a composite anode active material, and a preparation method and application thereof. In the preparation of the lithium battery, the composite negative active material provided by the invention can greatly improve the preparation efficiency of the lithium battery, reduce the preparation cost of the lithium battery, improve the cycle performance of the battery and reduce the expansion rate of an electrode.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a composite anode active material comprising a polymer, a conductive material, and an anode active material, the polymer comprising a water-soluble polymer or a combination of a water-soluble polymer and a water-insoluble polymer.
According to the invention, the polymer is added into the negative electrode material, so that the composite negative electrode material has the comprehensive advantages of the rigidity of the water-soluble polymer and the flexibility of the water-insoluble polymer, and has the effect of increasing the dispersion performance of the negative electrode active material and the conductive agent, and the adhesion force and compactness of the composite negative electrode active material and the current collector are improved in the subsequent wet preparation process of the negative electrode sheet. In addition, the conductive material and the polymer are dispersed and fixed around the negative active material in the composite material provided by the invention, so that the steps of dispersing a conductive agent, graphite, a binder and the like are omitted, deionized water can be directly added or a dry film is directly added to prepare the negative plate, and the agglomeration phenomenon generated in the preparation process is reduced.
In the invention, compared with a pure water-soluble polymer, the combination of the water-soluble polymer and the water-insoluble polymer has a better technical effect, because the water-soluble polymer has a hard and brittle texture, and the water-insoluble polymer has a soft texture, the pole piece is hard and brittle when the water-soluble polymer is used alone, and the problems can be avoided when the water-soluble polymer is matched with the water-insoluble polymer.
Preferably, the mass ratio of the polymer, the conductive material and the anode active material in the composite anode active material is (0.10-20.00): 100.00, preferably (0.5-10.0): 100.0, and can be, for example, 0.10.
In the invention, the conductivity, the adhesive property and the energy density of the negative electrode material of the pole piece are relatively high by controlling the mass ratio of the three components.
Preferably, when the polymer is a combination of a water-soluble polymer and a water-insoluble polymer, the mass ratio of the water-soluble polymer to the water-insoluble polymer is 1 (0.05-20.00), preferably 1.0 (0.1-9.0), and for example, the mass ratio can be 1.00.
In the invention, the pole piece has good performance by controlling the mass ratio of the water-soluble polymer to the water-insoluble polymer.
Preferably, the water-soluble polymer comprises a water-soluble natural polymer and a modified substance thereof and/or a water-soluble synthetic polymer.
Preferably, the water-soluble natural polymer and the modified substances thereof comprise any one or a combination of at least two of acacia gum and modified substances thereof, carrageenan and modified substances thereof, xanthan gum and modified substances thereof, guar gum and modified substances thereof, agar and modified substances thereof, gelatin and modified substances thereof, locust bean gum and modified substances thereof, konjac gum and modified substances thereof, pectin and modified substances thereof, or microcrystalline cellulose and modified substances thereof.
Preferably, the water-soluble natural polymer and the modified substances thereof comprise any one or the combination of at least two of carboxymethyl cellulose salt and modified substances thereof, alginate and modified substances thereof, chitosan and modified substances thereof or flaxseed gum and modified substances thereof, and preferably carboxymethyl cellulose salt and modified substances thereof.
In the present invention, the carboxymethyl cellulose salt and its modified products include, but are not limited to, carboxymethyl cellulose sodium salt.
Preferably, the structure of the water-soluble synthetic polymer includes any one or a combination of at least two of a carboxyl group, a hydroxyl group, a carbonyl group, an amide group, a sulfonic acid group, a cyano group, an ether group, an amine group, or a phosphoric acid group.
In the present invention, the water-soluble synthetic polymer may be used alone or in combination, and the water-soluble synthetic polymer may be a homopolymer or a copolymer.
In the present invention, the carbonyl group is more preferably a cyclic carbonyl group containing a hetero atom, and the water-soluble synthetic polymer contains a pyrrolidone structure.
Preferably, the structure of the water-soluble synthetic polymer includes any one or a combination of at least two of a carboxyl group, a carbonyl group, a cyano group, an ether group, an amine group, and a phosphoric acid group.
Preferably, the water-soluble synthetic polymer comprises any one or a combination of at least two of homopolymer of polymethacrylate and copolymer thereof, homopolymer of polyitaconate and copolymer thereof, homopolymer of polymaleate and copolymer thereof, homopolymer of polyethylene glycol and copolymer thereof, homopolymer of polypropylene glycol and copolymer thereof, homopolymer of polyvinylpyrrolidone and copolymer thereof, homopolymer of polymethacrylamide and copolymer thereof, homopolymer of polyethylenic alkyl ether and copolymer thereof, homopolymer of polyethylenic alkyl alcohol and copolymer thereof, or homopolymer of polyethylenic alkyl amine and copolymer thereof.
Preferably, the water-soluble synthetic polymer includes any one of an acrylic acid-acrylamide copolymer, an acrylic acid-acrylamide-acrylonitrile copolymer, or an acrylic acid-vinyl-2-hydroxyethanol-acrylamide copolymer or a combination of at least two thereof.
Preferably, the water-soluble synthetic polymer comprises any one or a combination of at least two of homopolymer of polymethacrylate and copolymer thereof, homopolymer of polyitaconate and copolymer thereof, homopolymer of polymaleate and copolymer thereof, homopolymer of polyvinylpyrrolidone and copolymer thereof, homopolymer of polyethylenic alkyl ether and copolymer thereof or homopolymer of polyethylenic alkyl amine and copolymer thereof, preferably homopolymer of polymethacrylate and copolymer thereof.
In the present invention, the polymethacrylate salt in the homopolymer and the copolymer thereof includes, but is not limited to, sodium polymethacrylate salt or lithium polymethacrylate salt.
Preferably, the water-insoluble polymer includes water-insoluble natural polymers and modifications thereof and/or water-insoluble synthetic polymers.
Preferably, the water-insoluble natural polymer and its modification include natural rubber and its modification.
Preferably, the water-insoluble synthetic polymer structure includes any one or a combination of at least two of an alkyl group, a cyano group, an aryl group, an ether group, an ester group, an aldehyde group, a halogen atom, an epoxy group, an imide group, or an amide group.
Preferably, the water-insoluble synthetic polymer structure includes any one or a combination of at least two of an alkyl group, a cyano group, an aryl group, an ester group, a halogen atom, an imide group, or an amide group.
In the present invention, the water-insoluble synthetic polymer may be used alone or in combination, and the water-insoluble synthetic polymer may be a homopolymer or a copolymer.
In the present invention, the ester group is more preferably a urethane group.
Preferably, the water-insoluble synthetic polymer comprises any one of a substituted or unsubstituted polyethylenic alkyl compound, a polyurethane, a copolymer of a polyurethane, a polyimide, or a copolymer of a polyimide, or a combination of at least two thereof.
Preferably, the substituted group includes any one or a combination of at least two of a cyano group, an aryl group, an ester group, or a halogen atom.
Preferably, the water-insoluble synthetic polymer comprises styrene butadiene rubber or nitrile butadiene rubber.
In the present invention, the polyethylenic alkyl compound is more preferably a homopolymer of polydiene and a copolymer thereof.
Preferably, the conductive material comprises any one of carbon black, carbon nanotubes, carbon fibers, graphene or conductive graphite or a combination of at least two thereof.
Preferably, the negative active material includes any one of or a combination of at least two of hard carbon, soft carbon, artificial graphite, natural graphite, graphitized carbon, mesocarbon microbeads, petroleum coke, carbon fibers, pyrolytic resin carbon, lithium titanate, silicon carbon compounds, silicon oxygen compounds, tin oxide compounds, tin-based alloys, silicon-based alloys, germanium-based alloys, aluminum-based alloys, antimony-based alloys, magnesium-based alloys, lithium-containing transition metal nitrides, or carbon nanotubes.
In a second aspect, the present invention provides a method for preparing the composite anode active material according to the first aspect, the method comprising the steps of:
the composite negative active material is prepared by a spray drying method or an internal mixing dispersion method;
the preparation process of the spray drying method comprises the following steps: mixing a negative electrode material, a conductive material and a polymer solution to obtain slurry, and then carrying out spray drying on the slurry to obtain the composite negative electrode active material;
the preparation process of the banburying dispersion method is as follows: mixing the negative electrode material, the conductive material and the polymer to obtain a mixed material, and then carrying out banburying dispersion on the mixed material to obtain the composite negative electrode active material.
Preferably, the inlet temperature of the spray drying method is 200-300 ℃, for example, 200 ℃, 220 ℃, 250 ℃, 280 ℃, 300 ℃.
Preferably, the outlet temperature of the spray drying process is 100-200 ℃, for example 100 ℃, 120 ℃, 150 ℃, 180 ℃, 200 ℃.
Preferably, the pressure of the spray drying method is 0.2 to 0.8MPa, and may be, for example, 0.2MPa, 0.3MPa, 0.4MPa, 0.5MPa, 0.6MPa, 0.7MPa, or 0.8MPa.
Preferably, the feed rate of the slurry in the spray drying method is 5-15mL/min, for example, 5mL/min, 6mL/min, 7mL/min, 8mL/min, 9mL/min, 10mL/min, 11mL/min, 12mL/min, 13mL/min, 14mL/min, 15mL/min.
Preferably, the temperature of the banburying dispersion method is 50-300 ℃, for example, 50 ℃, 60 ℃, 80 ℃, 100 ℃, 120 ℃, 150 ℃, 180 ℃, 200 ℃, 220 ℃, 250 ℃, 280 ℃ and 300 ℃.
Preferably, the turning angle of the banburying dispersion method is 0 to 140 °, for example, it may be 0 °, 5 °, 8 °, 10 °, 12 °, 15 °, 18 °, 20 °, 50 °, 80 °, 100 °, 120 °, 140 °.
Preferably, the rotating speed of the front rotor shaft of the banburying dispersion method is 10-100 r/min, for example, 10r/min, 30r/min, 50r/min, 80r/min and 100r/min.
Preferably, the rotation speed of the rear rotor shaft of the banburying dispersion method is 10-100 r/min, for example, 10r/min, 30r/min, 50r/min, 80r/min and 100r/min.
In a third aspect, the present invention provides a negative electrode sheet comprising a current collector and an active material coating disposed on the current collector, wherein the material in the active material coating comprises the composite negative electrode active material according to the first aspect.
In the invention, the negative plate can be prepared by adopting a dry film forming method or a wet film forming method.
In the invention, the dry film forming method comprises the steps of directly preparing the pole piece by a solvent-free method such as electrostatic spraying or hot-pressing film forming; the wet film forming method is to directly mix the composite negative active material provided by the invention with optional carboxymethyl cellulose solution to obtain negative slurry, and the steps of dispersing a conductive agent, dispersing graphite, dispersing a binder and the like are omitted.
In the invention, the preparation of the dry film forming method can avoid the condition of uneven dispersion of the conductive agent and the binder during the conventional wet dispersion; the wet film forming method can save the steps of dispersing a conductive agent, dispersing graphite, dispersing a binder and the like, so that the manufacturing efficiency of the lithium battery can be greatly improved, and meanwhile, the production cost of the lithium battery is reduced.
In a fourth aspect, the present invention provides an electrochemical energy storage device comprising a negative electrode sheet according to the third aspect.
Preferably, the electrochemical energy storage device comprises any one of a lithium ion battery, a sodium ion battery, a supercapacitor, a fuel cell or a solar cell.
In the invention, the composite negative active material provided by the invention can improve the cycle performance of the battery and reduce the expansion rate of the electrode.
Compared with the prior art, the invention has the following beneficial effects:
the present invention provides a composite anode active material having an effect of being capable of increasing the dispersion properties of an anode active material and a conductive agent. In addition, the steps of dispersing a conductive agent, dispersing graphite, dispersing a binder and the like can be omitted in the prepared negative plate, so that the manufacturing efficiency of the lithium battery can be greatly improved, and the production cost of the lithium battery is reduced.
The preparation method provided by the invention is simple to operate and good in repeated stability. The spray drying method can play a role in uniformly dispersing various components, and avoids the floating phenomenon of the common pole piece during drying; the banburying dispersion method does not use solvent water, and agglomeration is prevented in the drying process.
Detailed Description
The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
In the present invention, the sodium carboxymethylcellulose of the examples was purchased from xylonite corporation, model 2200; the styrene butadiene rubber in the examples and the comparative examples is purchased from Shenzhen, new materials, limited liability company and has the model number of BONE-Z.
Example 1
The embodiment provides a composite anode active material, which comprises a polymer, carbon black and artificial graphite, wherein the mass ratio of the polymer to the carbon black to the artificial graphite is 3. Wherein the mass ratio of the sodium carboxymethylcellulose to the styrene butadiene rubber is 1:4.
The preparation method of the composite negative active material comprises the following steps:
stirring aqueous solutions of artificial graphite, carbon black and a polymer to obtain slurry, feeding the slurry at the speed of 10mL/min, and performing spray drying, wherein the inlet temperature of the spray drying method is 250 ℃, the outlet temperature of the spray drying method is 150 ℃, and the pressure of the spray drying method is 0.5MPa, so as to obtain the composite cathode active material.
The invention also provides a negative plate, and the preparation method of the negative plate comprises the following steps:
and carrying out hot pressing treatment on the obtained composite negative electrode active material, wherein the hot pressing temperature is 90 ℃, and the hot pressing pressure is 1.0MPa, so as to obtain the negative electrode plate.
Example 2
The embodiment provides a composite anode active material, which comprises a polymer, carbon black and artificial graphite, wherein the mass ratio of the polymer to the carbon black to the artificial graphite is 3. Wherein the mass ratio of the sodium carboxymethylcellulose to the styrene butadiene rubber is 1:2.
The preparation method of the composite anode active material comprises the following steps:
stirring aqueous solutions of artificial graphite, carbon black and a polymer to obtain slurry, feeding the slurry at a speed of 7mL/min, and performing spray drying, wherein the inlet temperature of the spray drying method is 220 ℃, the outlet temperature of the spray drying method is 120 ℃, and the pressure of the spray drying method is 0.3MPa, so as to obtain the composite cathode active material.
The invention also provides a negative plate, and the preparation method of the negative plate comprises the following steps:
and carrying out hot pressing treatment on the obtained composite negative electrode active material, wherein the hot pressing temperature is 100 ℃, and the hot pressing pressure is 0.9MPa, so as to obtain the negative electrode plate.
Example 3
The embodiment provides a composite anode active material, which comprises a polymer, carbon black and artificial graphite, wherein the mass ratio of the polymer to the carbon black to the artificial graphite is 6.0. Wherein the mass ratio of the sodium carboxymethylcellulose to the styrene butadiene rubber is 1:7.
The preparation method of the composite negative active material comprises the following steps:
stirring aqueous solutions of artificial graphite, carbon black and a polymer to obtain slurry, feeding the slurry at the speed of 12mL/min, and performing spray drying, wherein the inlet temperature of the spray drying method is 280 ℃, the outlet temperature of the spray drying method is 180 ℃, and the pressure of the spray drying method is 0.6MPa, so as to obtain the composite cathode active material.
The invention also provides a negative plate, and the preparation method of the negative plate comprises the following steps:
and carrying out hot pressing treatment on the obtained composite negative electrode active material, wherein the hot pressing temperature is 110 ℃, and the hot pressing pressure is 0.8MPa, so as to obtain the negative electrode plate.
Example 4
The embodiment provides a composite anode active material, which comprises a polymer, carbon black and artificial graphite, wherein the mass ratio of the polymer to the carbon black to the artificial graphite is 2. Wherein the mass ratio of the sodium carboxymethylcellulose to the styrene butadiene rubber is 1.
The preparation method of the composite negative active material comprises the following steps:
stirring aqueous solutions of artificial graphite, carbon black and a polymer to obtain slurry, feeding the slurry at a speed of 5mL/min, and performing spray drying, wherein the inlet temperature of the spray drying method is 200 ℃, the outlet temperature of the spray drying method is 100 ℃, and the pressure of the spray drying method is 0.2MPa, so as to obtain the composite cathode active material.
The invention also provides a negative plate, and the preparation method of the negative plate comprises the following steps:
and carrying out hot pressing treatment on the obtained composite negative electrode active material, wherein the hot pressing temperature is 80 ℃, and the hot pressing pressure is 1.1MPa, thus obtaining the negative electrode plate.
Example 5
The embodiment provides a composite anode active material, which comprises a polymer, carbon black and artificial graphite, wherein the mass ratio of the polymer to the carbon black to the artificial graphite is 8. Wherein the mass ratio of the sodium carboxymethylcellulose to the styrene butadiene rubber is 1:9.
The preparation method of the composite negative active material comprises the following steps:
stirring aqueous solutions of artificial graphite, carbon black and a polymer to obtain slurry, feeding the slurry at a speed of 15mL/min, and performing spray drying, wherein the inlet temperature of the spray drying method is 300 ℃, the outlet temperature of the spray drying method is 200 ℃, and the pressure of the spray drying method is 0.8MPa, so as to obtain the composite cathode active material.
The invention also provides a negative plate, and the preparation method of the negative plate comprises the following steps:
and carrying out hot pressing treatment on the obtained composite negative electrode active material, wherein the hot pressing temperature is 70 ℃, and the hot pressing pressure is 1.2MPa, so as to obtain the negative electrode plate.
Example 6
The embodiment provides a composite negative electrode active material, which comprises sodium polymethacrylate, carbon nanotubes and silicon carbon compounds, wherein the mass ratio of the sodium polymethacrylate to the carbon nanotubes to the silicon carbon compounds is 3.
The preparation method of the composite negative active material comprises the following steps:
mixing a silicon-carbon compound, a carbon nano tube and sodium polymethacrylate to obtain a mixed material, and then carrying out banburying dispersion on the mixed material, wherein the temperature of a banburying dispersion method is 150 ℃, the turnover angle is 70 degrees, the rotating speed of a front rotor shaft is 55r/min, and the rotating speed of a rear rotor shaft is 55r/min, so as to obtain the composite cathode active material.
The invention also provides a negative plate, and the preparation method of the negative plate comprises the following steps:
and mixing the obtained composite negative electrode active material with a carboxymethyl cellulose solution to obtain negative electrode slurry, and drying at 60 ℃ for 12 hours to obtain a negative electrode sheet.
Example 7
This example differs from example 1 in that the polymers are polymethacrylate and nitrile rubber, and the rest is the same as example 1.
Example 8
The difference between the embodiment and the embodiment 1 is that the mass ratio of the sodium carboxymethyl cellulose to the styrene-butadiene rubber is 1.
Example 9
The difference between the embodiment and the embodiment 1 is that the mass ratio of the sodium carboxymethyl cellulose to the styrene-butadiene rubber is 1.
Example 10
This example differs from example 1 in that the polymer is sodium carboxymethyl cellulose, the rest being the same as example 1.
Example 11
This example differs from example 1 in that the polymers are polypropylene glycol and polyurethane, wherein the mass ratio of polypropylene glycol to polyurethane is 1:4, and is otherwise the same as example 1.
Example 12
The comparative example provides a negative electrode slurry which comprises sodium carboxymethylcellulose, styrene butadiene rubber, carbon black and artificial graphite, and the preparation method comprises the following steps:
mixing artificial graphite, carbon black, styrene-butadiene rubber and sodium carboxymethylcellulose according to a mass ratio of 100 4 And (4) rolling the N/m load per unit length to obtain the negative plate.
Comparative example 1
This comparative example differs from example 1 in that the polymer was replaced with styrene-butadiene rubber, sodium carboxymethylcellulose was not used, and the other examples are the same as example 1.
Application examples 1 to 12 and comparative application example 1
The preparation method of the lithium ion battery comprises the following steps:
the negative electrode sheets provided in examples 1 to 12 and the negative electrode sheet provided in comparative example 1 were assembled into a lithium ion battery, and the preparation method of the lithium ion battery was as follows:
(1) Preparing a positive plate: respectively mixing a positive electrode active substance (lithium iron phosphate material), conductive carbon black and a binder (PVDF) according to a solid content of 96.5 parts by mass 4 Rolling the N/m load per unit length to obtain a positive plate;
(2) And (3) negative plate: as described hereinbefore;
(3) A diaphragm: a PE porous polymer film (purchased from Shenzhen star source material science and technology corporation) is adopted as a diaphragm;
(4) Assembling the lithium ion battery: winding the positive plate, the diaphragm and the negative plate in sequence to obtain a battery cell; and packaging the battery core by using an aluminum-plastic film, baking to remove water, injecting electrolyte, and performing vacuum packaging, shelving, formation, secondary sealing, shaping and other processes to obtain the lithium ion battery.
Test conditions
The lithium ion batteries provided in application examples 1 to 12 and the lithium ion battery provided in comparative application example 1 were tested by the following test method:
(1) Cycle performance testing of lithium ion batteries
Charging the prepared lithium ion battery to 4.2V at a constant current of 0.33C, then charging at a constant voltage to a cut-off current of 0.02C, and discharging to 2.5V at 0.33C; the cell was left standing for 5min, and then was subjected to constant current charging at 0.33C to 4.2V, constant voltage charging at 0.02C to cut-off current, and discharging at 0.33C to 2.5V, thereby performing initial adjustment.
Charging the lithium ion battery adjusted in the initial stage to 4.2V at a constant current of 0.5C at 25 ℃, then charging at a constant voltage to a cut-off current of 0.02C, standing for 5min, then discharging at a constant current of 1C to 2.5V, standing for 5min, and measuring the first cycle discharge capacity; after 100 cycles of this cycle, charge/discharge, the 100 th cycle discharge capacity was measured, and the 100 th cycle capacity retention ratio was calculated using the following formula:
capacity retention (%) of 100 cycles (%) = (100 th-cycle discharge capacity/first-cycle discharge capacity) × 100%;
(2) Testing full-electric expansion rate of pole piece of lithium ion battery
Measuring the thickness of the copper foil by using a ten-thousandth micrometer to obtain T';
measuring the thickness of the prepared negative plate by using a micrometer to obtain T 0 ；
The lithium ion battery prepared above was charged to 4.2V at a constant current of 0.33C, and then charged at a constant voltage to an off current of 0.02C. Testing the internal resistance and voltage of the battery cell, and disassembling the battery cell in a glove box (the moisture content is less than or equal to 0.01ppm, and the oxygen content is less than or equal to 0.01 ppm) after confirming the 100% charge state of the battery cell;
measuring the thickness of the disassembled full-charge negative plate by using a ten-thousandth scale to obtain T 1 ；
Full electrical expansion rate (%) = (T) 1 -T 0 )/(T 0 -T')×100％
The test results are shown in table 1:
TABLE 1
Figure BDA0003824502070000141
Figure BDA0003824502070000151
As can be seen from the data in table 1, examples 1 to 5 provided by the present invention have a lower full electrical expansion rate of the electrode sheet and a higher capacity retention rate, specifically, the full electrical expansion rate of the electrode sheet is not more than 21.8%, and the capacity retention rate after 100 cycles is not less than 96.8%, which is mainly because the conductive material and the polymer are dispersed and fixed around the negative active material in the composite material provided by the present invention, so that the agglomeration phenomenon occurring in the preparation process is reduced. In example 6, the negative electrode material is prepared by adopting an internal mixing dispersion method, compared with the negative electrode sheet prepared by the traditional wet dispersion method, the lithium ion battery prepared by adopting the internal mixing dispersion method has good electrochemical properties because the components are prevented from agglomerating.
Compared with the embodiment 1, the embodiment 8 to the embodiment 9 are the case that the mass ratio of the sodium carboxymethyl cellulose to the styrene-butadiene rubber is not in the preferable range, which affects the quality of the final negative electrode plate, and increases the volume expansion phenomenon, and the full-electricity expansion rate of the provided lithium ion battery is higher than that of the battery provided by the embodiment 1, and the capacity retention rate is reduced.
Compared with the embodiment 1, the embodiment 10 is the case of simply using sodium carboxymethyl cellulose, and the comprehensive performance of the lithium ion battery provided by the embodiment is not as good as that of the lithium ion battery provided by the embodiment 1, mainly because the pole piece becomes hard and brittle by simply using the water-soluble polymer.
Example 12 is a negative electrode sheet prepared by a conventional wet dispersion method, and the negative electrode sheet has the disadvantages of uneven dispersion of components, easy occurrence of agglomeration and the like in the preparation process, so that the comprehensive performance of the prepared lithium ion battery is poor;
comparative example 2 is the case of a simple water-insoluble polymer, so that the formed negative electrode material is poor in molding and easy to fall off, and the performance of the lithium ion battery provided by the negative electrode material is not ideal.
The applicant states that the present invention is illustrated by the above examples of the process of the present invention, but the present invention is not limited to the above process steps, i.e. it is not meant that the present invention must rely on the above process steps to be carried out. It will be apparent to those skilled in the art that any modifications to the present invention, equivalent substitutions of selected materials and additions of auxiliary components, selection of specific forms, etc., are within the scope and disclosure of the present invention.

Claims (10)

1. A composite anode active material, characterized in that the composite anode active material comprises a polymer, a conductive material and an anode active material, wherein the polymer comprises a water-soluble polymer and a water-insoluble polymer in combination or a water-soluble polymer.
2. The composite negative active material according to claim 1, wherein the mass ratio of the polymer, the conductive material and the negative active material in the composite negative active material is (0.10-20.00): (0.01-20.00): 100.00, preferably (0.5-10.0): (0.1-10.0): 100.0.
3. The composite anode active material according to claim 1 or 2, wherein when the polymer is a combination of a water-soluble polymer and a water-insoluble polymer, the mass ratio of the water-soluble polymer to the water-insoluble polymer is 1 (0.05-20.00), preferably 1.0 (0.1-9.0).
4. The composite anode active material according to any one of claims 1 to 3, wherein the water-soluble polymer includes a water-soluble natural polymer and a modified product thereof and/or a water-soluble synthetic polymer;
preferably, the water-soluble natural polymer and the modified substances thereof comprise any one or a combination of at least two of Arabic gum and modified substances thereof, carrageenan and modified substances thereof, xanthan gum and modified substances thereof, guar gum and modified substances thereof, agar and modified substances thereof, gelatin and modified substances thereof, locust bean gum and modified substances thereof, konjac gum and modified substances thereof, pectin and modified substances thereof, or microcrystalline cellulose and modified substances thereof;
preferably, the water-soluble natural polymer and the modified substances thereof comprise any one or the combination of at least two of carboxymethyl cellulose salt and modified substances thereof, alginate and modified substances thereof, chitosan and modified substances thereof or flaxseed gum and modified substances thereof, and preferably carboxymethyl cellulose salt and modified substances thereof;
preferably, the structure of the water-soluble synthetic polymer includes any one or a combination of at least two of a carboxyl group, a hydroxyl group, a carbonyl group, an amide group, a sulfonic acid group, a cyano group, an ether group, an amine group, or a phosphoric acid group;
preferably, the structure of the water-soluble synthetic polymer includes any one or a combination of at least two of a carboxyl group, a carbonyl group, a cyano group, an ether group, an amine group, or a phosphoric acid group;
preferably, the water-soluble synthetic polymer comprises any one or a combination of at least two of homopolymer and copolymer of polymethacrylate, homopolymer and copolymer of polyitaconate, homopolymer and copolymer of polymaleate, homopolymer and copolymer of polyethylene glycol, homopolymer and copolymer of polypropylene glycol, homopolymer and copolymer of polyvinylpyrrolidone, homopolymer and copolymer of polymethacrylamide, homopolymer and copolymer of polyethylenic alkyl ether, homopolymer and copolymer of polyethylenic alkyl alcohol or homopolymer and copolymer of polyethylenic alkyl amine;
preferably, the water-soluble synthetic polymer comprises any one of or a combination of at least two of acrylic acid-acrylamide copolymer, acrylic acid-acrylamide-acrylonitrile copolymer or acrylic acid-vinyl-2-hydroxyethanol-acrylamide copolymer;
preferably, the water-soluble synthetic polymer comprises any one or a combination of at least two of homopolymer of polymethacrylate and copolymer thereof, homopolymer of polyitaconate and copolymer thereof, homopolymer of polymaleate and copolymer thereof, homopolymer of polyvinylpyrrolidone and copolymer thereof, homopolymer of polyethylenic alkyl ether and copolymer thereof or homopolymer of polyethylenic alkyl amine and copolymer thereof, preferably homopolymer of polymethacrylate and copolymer thereof.
5. The composite anode active material according to any one of claims 1 to 4, wherein the water-insoluble polymer includes a water-insoluble natural polymer and a modified product thereof and/or a water-insoluble synthetic polymer;
preferably, the water-insoluble natural polymer and its modification include natural rubber and its modification;
preferably, the water-insoluble synthetic polymer structure comprises any one or a combination of at least two of alkyl, cyano, aryl, ether, ester, aldehyde, halogen atom, epoxy, imide or amide;
preferably, the structure of the water-insoluble synthetic polymer comprises any one or a combination of at least two of alkyl, cyano, aryl, ester, halogen atoms, imide groups or amide groups;
preferably, the water-insoluble synthetic polymer comprises any one of or a combination of at least two of substituted or unsubstituted polyethylenic alkyl compound, polyurethane, copolymer of polyurethane, polyimide or copolymer of polyimide;
preferably, the substituted group comprises any one or a combination of at least two of cyano, aryl, ester or halogen atoms;
preferably, the water-insoluble synthetic polymer comprises styrene butadiene rubber or nitrile butadiene rubber.
6. The composite anode active material according to any one of claims 1 to 5, wherein the conductive material comprises any one of carbon black, carbon nanotubes, carbon fibers, graphene or conductive graphite or a combination of at least two thereof;
preferably, the negative active material includes any one of or a combination of at least two of hard carbon, soft carbon, artificial graphite, natural graphite, graphitized carbon, mesocarbon microbeads, petroleum coke, carbon fibers, pyrolytic resin carbon, lithium titanate, silicon carbon compounds, silicon oxygen compounds, tin oxide compounds, tin-based alloys, silicon-based alloys, germanium-based alloys, aluminum-based alloys, antimony-based alloys, magnesium-based alloys, lithium-containing transition metal nitrides, or carbon nanotubes.
7. A method for preparing a composite anode active material according to any one of claims 1 to 6, characterized by comprising the steps of:
the composite negative active material is prepared by adopting a spray drying method or an internal mixing dispersion method;
wherein the preparation process of the spray drying method is as follows: mixing a negative electrode material, a conductive material and a polymer solution to obtain slurry, and then carrying out spray drying on the slurry to obtain the composite negative electrode active material;
the preparation process of the banburying dispersion method is as follows: mixing the negative electrode material, the conductive material and the polymer to obtain a mixed material, and then carrying out banburying dispersion on the mixed material to obtain the composite negative electrode active material.
8. The method according to claim 7, wherein the inlet temperature of the spray drying process is 200-300 ℃;
preferably, the outlet temperature of the spray drying method is 100-200 ℃;
preferably, the pressure of the spray drying method is 0.2-0.8MPa;
preferably, the feeding speed of the slurry in the spray drying method is 5-15mL/min;
preferably, the temperature of the banburying dispersion method is 50-300 ℃;
preferably, the turning angle of the banburying dispersion method is 0-140 degrees;
preferably, the rotating speed of a front rotor shaft of the banburying dispersion method is 10-100 r/min;
preferably, the rotation speed of the rear rotor shaft of the internal mixing and dispersing method is 10-100 r/min.
9. A negative electrode sheet comprising a current collector and an active material coating disposed on the current collector, wherein a material in the active material coating comprises the composite negative electrode active material according to any one of claims 1 to 6.
10. An electrochemical energy storage device, characterized in that it comprises a negative electrode sheet according to claim 9;
preferably, the electrochemical energy storage device comprises any one of a lithium ion battery, a sodium ion battery, a supercapacitor, a fuel cell or a solar cell.
CN202211060363.5A 2022-08-31 2022-08-31 Composite negative electrode active material and preparation method and application thereof Pending CN115241447A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116230902A (en) * 2023-03-28 2023-06-06 盐城工学院 Negative electrode material of power battery and preparation method thereof

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116230902A (en) * 2023-03-28 2023-06-06 盐城工学院 Negative electrode material of power battery and preparation method thereof

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