CN110890531A - Negative electrode material, and electrochemical device and electronic device comprising same - Google Patents

Negative electrode material, and electrochemical device and electronic device comprising same Download PDF

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CN110890531A
CN110890531A CN201911114925.8A CN201911114925A CN110890531A CN 110890531 A CN110890531 A CN 110890531A CN 201911114925 A CN201911114925 A CN 201911114925A CN 110890531 A CN110890531 A CN 110890531A
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anode material
layer
carbon
negative electrode
anode
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CN110890531B (en
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姜道义
陈志焕
崔航
谢远森
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Ningde Amperex Technology 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
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
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    • 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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
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    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/483—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides for non-aqueous cells
    • H—ELECTRICITY
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    • 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
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    • 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
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
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    • 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
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Abstract

The present application relates to an anode material, and an electrochemical device and an electronic device including the same. The cathode material comprises a silicon composite matrix, and D of the silicon composite matrixV50 is in the range of 2.5 μm to 15 μm, and the particle size distribution of the silicon composite matrix satisfies: dn10/Dv50 is more than or equal to 0.1 and less than or equal to 0.6. The negative electrode material has good cycle performance and is made of the negative electrodeThe battery prepared from the electrode material has better rate performance and lower expansion rate.

Description

Negative electrode material, and electrochemical device and electronic device comprising same
Technical Field
The application relates to the field of energy storage, in particular to a negative electrode material, an electrochemical device and an electronic device comprising the same, and particularly relates to a lithium ion battery.
Background
With the popularization of consumer electronics products such as notebook computers, mobile phones, tablet computers, mobile power sources, unmanned aerial vehicles and the like, the requirements on electrochemical devices therein are becoming stricter. For example, batteries are required not only to be lightweight but also to have high capacity and long operating life. Lithium ion batteries have already occupied a mainstream status in the market by virtue of their outstanding advantages of high energy density, high safety, no memory effect, long operating life, and the like.
Disclosure of Invention
Embodiments of the present application provide an anode material and a method of preparing the anode material in an attempt to solve at least one of the problems existing in the related art to at least some extent. The embodiment of the application also provides a negative electrode, an electrochemical device and an electronic device using the negative electrode material.
In one embodiment, the present application provides an anode material comprising a silicon composite matrix having a D V50 is in the range of about 2.5 μm to 15 μm, and the particle size distribution of the silicon composite matrix satisfies: about 0.1. ltoreq. Dn10/Dv 50. ltoreq.about 0.6.
In another embodiment, the present application provides an anode comprising an anode material according to embodiments of the present application.
In another embodiment, the present application provides an electrochemical device comprising an anode according to embodiments of the present application.
In another embodiment, the present application provides an electronic device comprising an electrochemical device according to an embodiment of the present application.
The cathode active material has good cycle performance, and a lithium ion battery prepared from the cathode active material has good rate performance and low expansion rate.
Additional aspects and advantages of embodiments of the present application will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of embodiments of the present application.
Drawings
Drawings necessary for describing embodiments of the present application or the prior art will be briefly described below in order to describe the embodiments of the present application. It is to be understood that the drawings in the following description are only some of the embodiments of the present application. It will be apparent to those skilled in the art that other embodiments of the drawings can be obtained from the structures illustrated in these drawings without the need for inventive work.
Fig. 1 shows a volume-based particle size distribution curve of an anode active material of example 2 of the present application.
Fig. 2 shows a volume-based particle size distribution curve of the negative active material of comparative example 2 of the present application.
Fig. 3 shows a schematic view of the structure of the anode active material according to an embodiment of the present application.
Fig. 4 shows a schematic view of the structure of a negative active material according to another embodiment of the present application.
Fig. 5 shows an X-ray diffraction (XRD) pattern of the negative active material of example 25 of the present application.
Fig. 6 shows an X-ray diffraction (XRD) pattern of the negative active material of comparative example 3 of the present application.
Fig. 7 shows a Scanning Electron Microscope (SEM) picture of the negative active material of example 25 of the present application.
Fig. 8 shows a Scanning Electron Microscope (SEM) picture of the negative active material of comparative example 3 of the present application.
Detailed Description
Embodiments of the present application will be described in detail below. The embodiments of the present application should not be construed as limiting the present application.
As used in this application, the term "about" is used to describe and illustrate minor variations. When used in conjunction with an event or circumstance, the terms can refer to instances where the event or circumstance occurs precisely as well as instances where the event or circumstance occurs in close proximity. For example, when used in conjunction with numerical values, the term can refer to a range of variation that is less than or equal to ± 10% of the stated numerical value, such as less than or equal to ± 5%, less than or equal to ± 4%, less than or equal to ± 3%, less than or equal to ± 2%, less than or equal to ± 1%, less than or equal to ± 0.5%, less than or equal to ± 0.1%, or less than or equal to ± 0.05%.
In the present application, Dv50 is the particle diameter corresponding to 50% of the cumulative volume percentage of the negative electrode active material, and is expressed in μm.
In the present application, Dn10 is a particle diameter in μm corresponding to the cumulative percentage of the amount of the negative electrode active material of 10%.
In the present application, the silicon compound contains elemental silicon, a silicon compound, a mixture of elemental silicon and a silicon compound, or a mixture of different silicides.
Additionally, amounts, ratios, and other numerical values are sometimes presented herein in a range format. It is to be understood that such range format is used for convenience and brevity, and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited.
In the detailed description and claims, a list of items connected by the terms "one of," "one of," or other similar terms may mean any one of the listed items. For example, if items a and B are listed, the phrase "one of a and B" means a alone or B alone. In another example, if items A, B and C are listed, the phrase "one of A, B and C" means only a; only B; or only C. Item a may comprise a single element or multiple elements. Item B may comprise a single element or multiple elements. Item C may comprise a single element or multiple elements.
In the detailed description and claims, a list of items linked by the term "at least one of," "at least one of," or other similar terms may mean any combination of the listed items. For example, if items a and B are listed, the phrase "at least one of a and B" means a only; only B; or A and B. In another example, if items A, B and C are listed, the phrase "at least one of A, B and C" means a only; or only B; only C; a and B (excluding C); a and C (excluding B); b and C (excluding A); or A, B and C. Item a may comprise a single element or multiple elements. Item B may comprise a single element or multiple elements. Item C may comprise a single element or multiple elements.
First, negative electrode material
The embodiment of the application provides a negative electrode material, which comprises a silicon composite matrix, wherein D of the silicon composite matrix isV50 is in the range of 2.5 μm to 15 μm, and the particle size distribution of the silicon composite matrix satisfies: dn10/Dv50 is more than or equal to 0.1 and less than or equal to 0.6.
In some embodiments, D of the silicon composite substrate V50 is in the range of about 2.5 μm to 15 μm. In some embodiments, D of the silicon composite substrate V50 is in the range of about 2.5 μm to 10 μm. In some embodiments, D of the silicon composite substrate V50 is in the range of about 3 μm to 9 μm. In some embodiments, D of the silicon composite substrate V50 is in the range of about 4 μm to 7 μm.
In some embodiments, the particle size distribution of the silicon composite matrix satisfies about 0.3. ltoreq. Dn10/Dv 50. ltoreq.about 0.5. In some embodiments, the particle size distribution of the silicon composite matrix satisfies about Dn10/Dv50 of about 0.35 or about 0.4.
In some embodiments, the silicon composite matrix comprises a silicon-containing species, wherein the silicon-containing species in the silicon composite matrix and one or more of the other species in the anode material other than the silicon-containing species may form a composite. In some embodiments, the silicon composite matrix comprises particles capable of intercalating and deintercalating lithium ions.
In some embodiments, the silicon composite matrix comprises SiOxAnd x is greater than or equal to about 0.6 and less than or equal to about 1.5.
In some embodiments, the silicon composite matrix comprises nano-Si grains, SiO2Or any combination thereof.
In some embodiments, the nano-Si grains are less than about 100nm in size. In some embodiments, the nano-Si grains are less than about 50nm in size. In some embodiments, the nano-Si grains are less than about 20nm in size. In some embodiments, the nano-Si grains are less than about 5nm in size. In some embodiments, the nano-Si grains are less than about 2nm in size. In some embodiments, the nano-Si grains are less than about 0.5nm in size
In some embodiments, the anode material further comprises an oxide MeOyLayer of said oxide MeOyA layer coating at least a portion of the silicon composite matrix, wherein Me comprises at least one of Al, Si, Ti, Mn, V, Cr, Co, or Zr, wherein y is about 0.5-3; and wherein the oxide MeOyThe layer comprises a carbon material.
In some embodiments, the oxide MeOyIncluding Al2O3、SiO2、TiO2、Mn2O3、MnO2、CrO3、Cr2O3、CrO2、V2O5、VO、CoO、Co2O3、Co3O4、ZrO2Or any combination thereof.
In some embodiments, the oxide MeOyThe carbon material in the layer comprises amorphous carbon, carbon nanotubes, carbon nanoparticles, carbon fibers, graphene, or any combination thereof. In some embodiments, the amorphous carbon is a carbon material obtained by sintering a carbon precursor at a high temperature. In some embodiments, the carbon precursor comprises polyvinylpyrrolidone, sodium carboxymethylcellulose, polyvinyl alcohol, polypropylene, acid phenolic resin, polyester resin, polyamide resin, epoxy resin, polyurethane, polyacrylic resin, or any combination thereof.
In some embodiments, the oxide MeOyThe thickness of the layer is about 1nm to 1000 nm. In some embodiments, the oxide MeOyThe thickness of the layer is about 10nm to 900 nm. In some embodiments, the oxide MeOyThe thickness of the layer is about 20nm to 800 nm. In some embodiments, the oxide MeOyThe thickness of the layer is about 1nm to 20 nm. In some embodiments, the oxide MeOyThe thickness of the layer is about 2nm, about 5nm, about 10nm, about 15nm, about 20nm, or about 50 nm.
In some embodiments, the weight percentage of Me element is about 0.01 wt% to 1 wt% based on the total weight of the anode material. In some embodiments, the weight percentage of Me element is about 0.02 wt% to 1 wt% based on the total weight of the anode material. In some embodiments, the weight percentage of Me element is about 0.03 wt% to 0.9 wt% based on the total weight of the anode material. In some embodiments, the weight percentage of Me element is about 0.05 wt%, about 0.1 wt%, about 0.2 wt%, about 0.3 wt%, about 0.4 wt%, about 0.5 wt%, about 0.6 wt%, about 0.7 wt%, or about 0.8 wt%, based on the total weight of the anode material.
In some embodiments, the oxide MeO is based on the total weight of the anode materialyThe weight percent of carbon material in the layer is between about 0.05 wt% and 1 wt%. In some embodiments, the oxide MeO is based on the total weight of the anode materialyThe weight percent of carbon material in the layer is between about 0.1 wt% and 0.8 wt%. In some embodiments, the oxide MeO is based on the total weight of the anode materialyThe weight percent of carbon material in the layer is between about 0.2 wt% and 0.7 wt%. In some embodiments, the oxide MeO is based on the total weight of the anode materialyThe weight percent of carbon material in the layer is about 0.3 wt%, about 0.4 wt%, about 0.5 wt%, about 0.6 wt%, about 0.7 wt%, or about 0.8 wt%.
In some embodiments, the anode material further comprises a polymer layer encapsulating the oxide MeOyAt least a portion of a layer, and the polymer layer comprises a carbon material.
In some embodiments, the polymer layer comprises polyvinylidene fluoride and derivatives thereof, carboxymethylcellulose and derivatives thereof, sodium carboxymethylcellulose and derivatives thereof, polyvinylpyrrolidone and derivatives thereof, polyacrylic acid and derivatives thereof, poly (styrene-butadiene rubber), polyacrylamide, polyimide, polyamideimide, or any combination thereof.
In some embodiments, the carbon material in the polymer layer comprises carbon nanotubes, carbon nanoparticles, carbon fibers, graphene, or any combination thereof.
In some embodiments, the weight percentage of the polymer layer is about 0.1 to 10 wt% based on the total weight of the anode material. In some embodiments, the weight percentage of the polymer layer is about 0.2 to 8 wt% based on the total weight of the anode material. In some embodiments, the weight percentage of the polymer layer is about 0.3-7 wt% based on the total weight of the anode material. In some embodiments, the weight percentage of the polymer layer is about 1 wt%, about 1.5 wt%, about 2 wt%, about 4 wt%, about 5 wt%, or about 6 wt%, based on the total weight of the anode material.
In some embodiments, the polymer layer has a thickness of about 2nm to 100 nm. In some embodiments, the polymer layer has a thickness of about 10nm to 90 nm. In some embodiments, the polymer layer has a thickness of about 15nm to 80 nm. In some embodiments, the polymer layer has a thickness of about 5nm, about 20nm, about 25nm, about 45nm, about 55nm, or about 75 nm.
In some embodiments, the anode material has a specific surface area of about 1-50m2(ii) in terms of/g. In some embodiments, the anode material has a specific surface area of about 1-30m2(ii) in terms of/g. In some embodiments, the anode material has a specific surface area of about 1-10m2(ii) in terms of/g. In some embodiments, the anode material has a specific surface area of about 1m2G, about 5m2In the range of/g or about 10m2/g。
In some embodiments, the anode material has a maximum intensity value of I within a range of about 27.0-30.0 in X-ray diffraction pattern due to 2 θ2The highest intensity value assigned to the range of about 20.0-22.0 is I1Wherein is about 0<I2/I1Less than or equal to about 1.
In some embodiments, the anode material has a 2 θ ascribed to a maximum intensity value of I of about 28.4 ° in an X-ray diffraction pattern2The highest intensity value assigned to the range of about 21.0 is I1Of which about 0.1<I2/I1Less than or equal to about 1. In some embodiments, I2/I10.2, 0.4 or 0.5.
Preparation method of anode material
An embodiment of the present application provides a method for preparing any one of the above-mentioned anode materials, including: to silicon oxide SiOxGrading to obtain the anode material with the particle size distribution meeting the following conditions: dn10/Dv50 is more than or equal to 0.1 and less than or equal to 0.6, wherein x is more than or equal to 0.6 and less than or equal to 1.5.
In some embodiments, the fractionation method comprises gas flow fractionation.
In some embodiments, the method further comprises coating the oxide MeOyStep of layer, said coating oxide MeOyThe steps of the layer include:
(1) classifying the solid, carbon precursor and oxide precursor MeT obtained by the classificationnForming a mixed solution in the presence of an organic solvent and deionized water;
(2) drying the mixed solution to obtain powder; and
(3) sintering the powder at about 200-900 ℃ for about 0.5-20h to obtain the powder with the oxide MeO on the surfaceyA negative electrode material of the layer;
wherein y is from about 0.5 to about 3,
wherein Me comprises at least one of Al, Si, Ti, Mn, Cr, V, Co or Zr,
wherein T comprises at least one of methoxy, ethoxy, isopropoxy, or halogen, and
wherein n is 1, 2, 3 or 4.
In some embodiments, the oxide precursor MeTnIncluding isopropyl titanate, aluminum isopropoxide, or combinations thereof.
In some embodiments, the carbon material comprises amorphous carbon, carbon nanotubes, carbon nanoparticles, carbon fibers, graphene, or any combination thereof. In some embodiments, the amorphous carbon is a carbon material obtained by sintering a carbon precursor at a high temperature. In some embodiments, the carbon precursor comprises polyvinylpyrrolidone, sodium carboxymethylcellulose, polyvinyl alcohol, polypropylene, acid phenolic resin, polyester resin, polyamide resin, epoxy resin, polyurethane, polyacrylic resin, or any combination thereof.
In some embodiments, the sintering temperature is about 250-. In some embodiments, the sintering temperature is about 300-. In some embodiments, the sintering temperature is about 400 ℃, about 500 ℃, or about 600 ℃.
In some embodiments, the sintering time is about 1-18 hours. In some embodiments, the sintering time is about 1-16 h. In some embodiments, the sintering time is about 1-12 hours. In some embodiments, the sintering time is about 1.5-6 hours. In some embodiments, the sintering time is about 1.5h, about 2.5h, about 3.5h, about 5h, or about 6.5 h.
In some embodiments, the organic solvent comprises at least one of: ethanol, methanol, N-hexane, N-dimethylformamide, pyrrolidone, acetone, toluene, isopropanol or N-propanol. In some embodiments, the organic solvent is ethanol.
In some embodiments, the halogen comprises F, Cl, Br, or a combination thereof.
In some embodiments, the sintering is performed under an inert gas blanket. In some embodiments, the inert gas comprises nitrogen, argon, or a combination thereof.
In some embodiments, the drying is spray drying, with a drying temperature of about 100-.
In some embodiments, the method further comprises the step of coating a polymer layer, the step of coating a polymer layer comprising:
(1) classifying the solid obtained by the above steps or the solid with the oxide MeO on the surfaceyDispersing the negative electrode material, the carbon material and the polymer in the solvent at a high speed for 1-15h to obtain a suspension; and
(2) removing the solvent from the suspension.
In some embodiments, the polymer comprises polyvinylidene fluoride and derivatives thereof, carboxymethylcellulose and derivatives thereof, sodium carboxymethylcellulose and derivatives thereof, polyvinylpyrrolidone and derivatives thereof, polyacrylic acid and derivatives thereof, poly (styrene-butadiene rubber), polyacrylamide, polyimide, polyamideimide, or any combination thereof.
In some embodiments, the carbon material comprises carbon nanotubes, carbon nanoparticles, carbon fibers, graphene, or any combination thereof.
In some embodiments, the solvent comprises water, ethanol, methanol, tetrahydrofuran, acetone, chloroform, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, toluene, xylene, or any combination thereof.
In some embodiments, the silicon oxide SiOxCan be commercial silicon oxide and can also be silicon oxide SiO prepared by the method of the inventionxIn which the silicon oxide SiO prepared according to the process of the invention x2 theta in the X-ray diffraction pattern has a maximum intensity value I within a range of about 27.0 DEG to 30.0 DEG2The highest intensity value assigned to the range of about 20.0-22.0 is I1Wherein is about 0<I2/I1Less than or equal to about 1. In some embodiments, I2/I1About 0.2, about 0.4, or about 0.5.
Satisfies about 0 in the present invention<I2/I1Silicon oxide SiO ≦ about 1xThe preparation method comprises the following steps:
(1) mixing silicon dioxide and metal silicon powder in a molar ratio of about 1:6-6:1 to obtain a mixed material;
(2) at about 10-4-10-1Heating the mixed material at a temperature in the range of about 1100 ℃ and 1800 ℃ for about 1-25h under the kPa pressure range to obtain a gas;
(3) condensing the gas obtained to obtain a solid;
(4) pulverizing and sieving the solids; and
(5) heat treating said solid in the range of about 400-1500 ℃ for about 0.5-24h, cooling said heat treated solid to obtain a temperature satisfying about 0<I2/I1Silicon oxide SiO ≦ about 1x。
In some embodiments, the silica to metal silicon powder molar ratio is about 1:4 to 4: 1. In some embodiments, the silica to metal silicon powder molar ratio is about 1:3 to 3: 1. In some embodiments, the silica to metal silicon powder molar ratio is about 1:2 to 2: 1. In some embodiments, the silica to metal silicon powder molar ratio is about 1:1, about 1.5:1, or about 2.5: 1.
In some embodiments, the pressure range is about 10-4-10-1kPa. In some embodiments, the pressure is about 1Pa, about 10Pa, about 20Pa, about 30Pa, about 40Pa, about 50Pa, about 60Pa, about 70Pa, about 80Pa, about 90Pa, or about 100 Pa.
In some embodiments, the heating temperature is about 1100-. In some embodiments, the heating temperature is about 1150 ℃, about 1200 ℃, about 1250 ℃, or about 1400 ℃.
In some embodiments, the heating time is about 1-20 hours. In some embodiments, the heating time is about 5-15 hours. In some embodiments, the heating time is about 2h, about 4h, about 6h, about 8h, about 10h, about 12h, about 14h, about 16h, or about 18 h.
In some embodiments, the mixing is performed by a ball mill, a V-blender, a three-dimensional blender, an air blender, or a horizontal blender.
In some embodiments, the heating and heat treating are performed under an inert gas blanket. In some embodiments, the inert gas comprises nitrogen, argon, helium, or a combination thereof.
In some embodiments, the method further comprises the step of heat treating after sieving.
In some embodiments, the heat treatment time is about 500-1500 ℃. In some embodiments, the heat treatment time is about 400-1200 ℃. In some embodiments, the time of the heat treatment is about 600 ℃, about 800 ℃, or about 1000 ℃.
In some embodiments, the heat treatment time is about 1-24 hours. In some embodiments, the heat treatment time is about 2-12 hours. In some embodiments, the time for the heat treatment is about 5 hours, about 10 hours, or about 15 hours.
Fig. 1 is a volume-based particle size distribution curve of the negative active material of example 2. It can be seen from fig. 1 that the particle size distribution of the anode active material particles of example 2 is relatively uniform and the distribution is relatively narrow. The lithium ion battery prepared from the negative active material of example 2 exhibited more satisfactory cycle characteristics and anti-swelling properties.
Fig. 2 is a volume-based particle size distribution curve of the negative active material of comparative example 2. It can be seen from fig. 2 that the negative active material of comparative example 2 has a certain number of small particles and thus has poor cycle performance. The presence of small fine particles accelerates the etching of the particles by the electrolyte and thus accelerates deterioration of cycle performance. On the other hand, since the small particles are rapidly etched by the electrolyte, a large amount of by-products are generated on the surface thereof, and thus the anti-swelling property of the lithium ion battery prepared therefrom is inferior to that of the lithium ion battery prepared from the negative active material of comparative example 2.
Fig. 3 shows a schematic view of the structure of the anode active material according to an embodiment of the present application. Wherein the inner layer 1 is a silicon composite matrix and the outer layer 2 is an oxide MeO comprising a carbon materialyAnd (3) a layer.
Oxide MeO coating the silicon composite matrixyThe oxide can react with HF in the electrolyte to reduce the content of HF in the electrolyte in the circulating process and reduce the etching of HF on the surface of the silicon material, so that the circulating performance of the material is further improved. Oxide MeOyThe carbon material doped in the layer is beneficial to forming a lithium ion conductor after lithium is embedded in the first charge-discharge process, and is beneficial to realizing the conduction of ions. In addition, the oxide MeOyThe doping of the layer with a certain amount of carbon may enhance the conductivity of the negative active material.
Fig. 4 shows a schematic view of the structure of a negative active material according to another embodiment of the present application. Wherein the inner layer 1 is a silicon composite matrix and the intermediate layer 2 is an oxide MeO comprising a carbon materialyThe outer layer 3 is a polymer layer containing a carbon material. The negative active material of the present application may also have only a silicon composite matrix and a polymer layer without MeOyAnd (3) a layer. That is, the polymer layer of the present application may be coated directly on the surface of the silicon composite substrate.
The polymer layer containing the Carbon Nano Tube (CNT) is coated on the surface of the negative active material, and the CNT can be bound on the surface of the negative active material by using the polymer, so that the interface stability of the CNT on the surface of the negative active material is favorably improved, and the cycle performance of the CNT is improved.
Fig. 5 shows an X-ray diffraction (XRD) pattern of the negative active material of example 25 of the present application. As can be seen from FIG. 5, the anode active material has a maximum intensity value I in the range of 28.0 to 29.0 in terms of 2 θ in the X-ray diffraction pattern2The highest intensity value in the range of 20.5-21.5 is I1Wherein 0 is<I2/I1≤1。I2/I1The magnitude of the number reflects the degree to which the material is affected by disproportionation. I is2/I1The larger the value, the larger the size of the nano silicon crystal grains inside the negative electrode active material. When I is2/I1When the value is more than 1, the negative electrode active material may cause a sharp increase in stress in a local region during lithium intercalation, thereby causing structural deterioration of the negative electrode active material during cycling. In addition, the ability of the grain boundaries to diffuse during ion diffusion can be affected by the creation of nanocrystalline distributions. The inventor of the present application finds that when I2/I1The value satisfies 0<I2/I1When the content is less than or equal to 1, the negative electrode active material has good cycle performance, and the lithium ion battery prepared from the negative electrode active material has good expansion resistance.
Fig. 6 shows an X-ray diffraction (XRD) pattern of the negative active material of comparative example 3 of the present application. As can be seen from fig. 6, I of the negative active material of comparative example 32/I1The value is clearly greater than 1. The negative active material of comparative example 3 had inferior cycle performance, and the lithium ion battery prepared therefrom had higher expansion rate and inferior rate performance, compared to the negative active material of example 25.
Fig. 7 and 8 show Scanning Electron Microscope (SEM) pictures of the anode active materials in example 25 and comparative example 3, respectively. The size distribution of the particles can be seen visually in fig. 7 and 8. Fig. 8 shows that a certain number of small particles are present in the anode active material of comparative example 3.
Third, negative pole
The embodiment of the application provides a negative electrode. The negative electrode includes a current collector and a negative active material layer on the current collector. The negative active material layer includes a negative electrode material according to an embodiment of the present application.
In some embodiments, the negative active material layer includes a binder. In some embodiments, the adhesive includes, but is not limited to: polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene 1, 1-difluoroethylene, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, or nylon.
In some embodiments, the negative active material layer includes a conductive material. In some embodiments, the conductive material includes, but is not limited to: natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, metal powder, metal fiber, copper, nickel, aluminum, silver, or polyphenylene derivative.
In some embodiments, the current collector includes, but is not limited to: copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, or a polymer substrate coated with a conductive metal.
In some embodiments, the negative electrode may be obtained by: the active material, the conductive material, and the binder are mixed in a solvent to prepare an active material composition, and the active material composition is coated on a current collector.
In some embodiments, the solvent may include, but is not limited to: n-methyl pyrrolidone.
Fourth, positive electrode
Materials, compositions, and methods of making positive electrodes useful in embodiments of the present application include any of the techniques disclosed in the prior art. In some embodiments, the positive electrode is the positive electrode described in U.S. patent application No. US9812739B, which is incorporated by reference herein in its entirety.
In some embodiments, the positive electrode includes a current collector and a positive active material layer on the current collector.
In some embodiments, the positive active material includes, but is not limited to: lithium cobaltate (LiCoO2), lithium Nickel Cobalt Manganese (NCM) ternary materials, lithium iron phosphate (LiFePO4) or lithium manganate (LiMn2O 4).
In some embodiments, the positive active material layer further includes a binder, and optionally a conductive material. The binder improves the binding of the positive electrode active material particles to each other, and also improves the binding of the positive electrode active material to the current collector.
In some embodiments, the adhesive includes, but is not limited to: polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene 1, 1-difluoroethylene, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, or the like.
In some embodiments, the conductive material includes, but is not limited to: carbon-based materials, metal-based materials, conductive polymers, and mixtures thereof. In some embodiments, the carbon-based material is selected from natural graphite, artificial graphite, carbon black, acetylene black, ketjen black, carbon fiber, or any combination thereof. In some embodiments, the metal-based material is selected from metal powder, metal fiber, copper, nickel, aluminum, or silver. In some embodiments, the conductive polymer is a polyphenylene derivative.
In some embodiments, the current collector may include, but is not limited to: aluminum.
The positive electrode may be prepared by a preparation method well known in the art. For example, the positive electrode can be obtained by: the active material, the conductive material, and the binder are mixed in a solvent to prepare an active material composition, and the active material composition is coated on a current collector. In some embodiments, the solvent may include, but is not limited to: n-methyl pyrrolidone.
Fifth, electrolyte
The electrolyte that may be used in the embodiments of the present application may be an electrolyte known in the art.
In some embodiments, the electrolyte includes an organic solvent, a lithium salt, and an additive. The organic solvent of the electrolyte according to the present application may be any organic solvent known in the art that can be used as a solvent of the electrolyte. The electrolyte used in the electrolyte according to the present application is not limited, and may be any electrolyte known in the art. The additive of the electrolyte according to the present application may be any additive known in the art as an additive of electrolytes.
In some embodiments, the organic solvent includes, but is not limited to: ethylene Carbonate (EC), Propylene Carbonate (PC), diethyl carbonate (DEC), Ethyl Methyl Carbonate (EMC), dimethyl carbonate (DMC), propylene carbonate or ethyl propionate.
In some embodiments, the lithium salt comprises at least one of an organic lithium salt or an inorganic lithium salt.
In some embodiments, the lithium salt includes, but is not limited to: lithium hexafluorophosphate (LiPF)6) Lithium tetrafluoroborate (LiBF)4) Lithium difluorophosphate (LiPO)2F2) Lithium bis (trifluoromethanesulfonylimide) LiN (CF)3SO2)2(LiTFSI), lithium bis (fluorosulfonyl) imide Li (N (SO)2F)2) (LiFSI), lithium bis (oxalato) borate LiB (C)2O4)2(LiBOB) or lithium difluorooxalato borate LiBF2(C2O4)(LiDFOB)。
In some embodiments, the concentration of lithium salt in the electrolyte is: about 0.5 to 3mol/L, about 0.5 to 2mol/L, or about 0.8 to 1.5 mol/L.
Sixth, the barrier film
In some embodiments, a separator is provided between the positive and negative electrodes to prevent short circuits. The material and shape of the separation film that can be used for the embodiment of the present application are not particularly limited, and may be any of the techniques disclosed in the prior art. In some embodiments, the separator includes a polymer or inorganic substance or the like formed of a material stable to the electrolyte of the present application.
For example, the release film may include a substrate layer and a surface treatment layer. The substrate layer is a non-woven fabric, a film or a composite film with a porous structure, and the material of the substrate layer is at least one selected from polyethylene, polypropylene, polyethylene terephthalate and polyimide. Specifically, a polypropylene porous film, a polyethylene porous film, a polypropylene nonwoven fabric, a polyethylene nonwoven fabric, or a polypropylene-polyethylene-polypropylene porous composite film can be used.
At least one surface of the substrate layer is provided with a surface treatment layer, and the surface treatment layer can be a polymer layer or an inorganic layer, or a layer formed by mixing a polymer and an inorganic substance.
The inorganic layer comprises inorganic particles and a binder, wherein the inorganic particles are selected from one or more of aluminum oxide, silicon oxide, magnesium oxide, titanium oxide, hafnium oxide, tin oxide, cerium dioxide, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide and barium sulfate. The binder is selected from one or a combination of more of polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polymethyl methacrylate, polytetrafluoroethylene and polyhexafluoropropylene.
The polymer layer comprises a polymer, and the material of the polymer is selected from at least one of polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride or poly (vinylidene fluoride-hexafluoropropylene).
Seventh, electrochemical device
Embodiments of the present application provide an electrochemical device including any device in which an electrochemical reaction occurs.
In some embodiments, the electrochemical device of the present application includes a positive electrode having a positive electrode active material capable of occluding and releasing metal ions; a negative electrode according to an embodiment of the present application; an electrolyte; and a separator interposed between the positive electrode and the negative electrode.
In some embodiments, the electrochemical devices of the present application include, but are not limited to: all kinds of primary batteries, secondary batteries, fuel cells, solar cells or capacitors.
In some embodiments, the electrochemical device is a lithium secondary battery.
In some embodiments, the lithium secondary battery includes, but is not limited to: a lithium metal secondary battery, a lithium ion secondary battery, a lithium polymer secondary battery, or a lithium ion polymer secondary battery.
Eight, electronic device
The electronic device of the present application may be any device using the electrochemical device according to the embodiment of the present application.
In some embodiments, the electronic devices include, but are not limited to: a notebook computer, a pen-input computer, a mobile computer, an electronic book player, a cellular phone, a portable facsimile machine, a portable copier, a portable printer, a headphone, a video recorder, a liquid crystal television, a portable cleaner, a portable CD player, a mini-disc, a transceiver, an electronic organizer, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, an automobile, a motorcycle, a power-assisted bicycle, a lighting apparatus, a toy, a game machine, a clock, an electric tool, a flashlight, a camera, a large-sized household battery or a lithium ion capacitor, and the like.
Taking a lithium ion battery as an example and describing the preparation of the lithium ion battery with reference to specific examples, those skilled in the art will understand that the preparation method described in the present application is only an example, and any other suitable preparation method is within the scope of the present application.
Examples
The following describes performance evaluation according to examples and comparative examples of lithium ion batteries of the present application.
Method for evaluating performance of negative electrode active material
1. Method for testing powder property of negative electrode active material
(1) And (3) observing the micro-morphology of the powder particles: observing the microscopic morphology of the powder by using a scanning electron microscope to represent the surface coating condition of the material, wherein the selected test instruments are as follows: OxFORD EDS (X-max-20 mm)2) The accelerating voltage is 15KV, the focal length is adjusted, the observation multiple is observed from 50K at high power and low power500-2000 was used to observe mainly particle agglomeration.
(2) Specific surface area test: after the adsorption amount of the gas on the solid surface at different relative pressures is measured at constant temperature and low temperature, the adsorption amount of the monolayer of the sample is obtained based on the Bronuore-Eltt-Taylor adsorption theory and the formula (BET formula) thereof, and the specific surface area of the solid is calculated.
About 1.5-3.5g of the powder sample was weighed into a test sample tube of TriStar II 3020, degassed at about 200 ℃ for 120min and tested.
(3) And (3) testing the granularity: about 0.02g of the powder sample was added to a 50ml clean beaker, about 20ml of deionized water was added, a few drops of 1% surfactant were added dropwise to completely disperse the powder in water, sonicated in a 120W ultrasonic cleaner for 5 minutes, and the particle size distribution was measured using a MasterSizer 2000.
(4) And (3) testing the carbon content: the sample is heated and combusted at high temperature by a high-frequency furnace under the condition of oxygen enrichment to respectively oxidize carbon and sulfur into carbon dioxide and sulfur dioxide, the gas enters a corresponding absorption cell after being treated, corresponding infrared radiation is absorbed, and then the infrared radiation is converted into corresponding signals by a detector. The signal is sampled by a computer, is converted into a numerical value in direct proportion to the concentration of carbon dioxide and sulfur dioxide after linear correction, then the value of the whole analysis process is accumulated, after the analysis is finished, the accumulated value is divided by a weight value in the computer, and then multiplied by a correction coefficient, and blank is deducted, thus the percentage content of carbon and sulfur in the sample can be obtained. The sample was tested using a high frequency infrared carbon sulfur analyzer (Shanghai DE Ky HCS-140).
(5) XRD test: weighing 1.0-2.0g of sample, pouring the sample into a groove of a glass sample rack, compacting and grinding the sample by using a glass sheet, testing by using an X-ray diffractometer (Bruk, D8) according to JJS K0131-2And the highest intensity I attributed to 21.0 DEG1Thereby calculating I2/I1The ratio of (a) to (b).
(6) And (3) testing metal elements: weighing a certain amount of sample, adding a certain amount of concentrated nitric acid into the sample, performing microwave digestion to obtain a solution, washing the obtained solution and filter residue for multiple times, fixing the volume to a certain volume, testing the plasma intensity of metal elements in the solution through ICP-OES, and calculating the metal content in the solution according to a standard curve of the measured metal, thereby calculating the amount of the metal elements contained in the material.
The weight percentages of each material in the following tables are calculated based on the total weight of the anode active material.
Second, electrical property test method of negative electrode active material
1. The button cell testing method comprises the following steps:
under dry argon atmosphere, LiPF is added into a solvent formed by mixing Propylene Carbonate (PC), Ethylene Carbonate (EC) and diethyl carbonate (DEC) (the weight ratio is about 1: 1: 1)6Mixing uniformly, wherein LiPF6Was added with about 7.5 wt% of fluoroethylene carbonate (FEC), and mixed uniformly to obtain an electrolyte solution.
The negative electrode active materials, conductive carbon black, and a binder PAA (modified polyacrylic acid, PAA) obtained in examples and comparative examples were mixed in a weight ratio of about 80: 10: 10 adding the mixture into deionized water, stirring to form slurry, coating by using a scraper to form a coating with the thickness of about 100 mu m, drying at about 85 ℃ for about 12 hours in a vacuum drying oven, cutting into round pieces with the diameter of about 1cm by using a punch in a drying environment, taking a metal lithium piece as a counter electrode in a glove box, selecting a ceglard composite film as an isolating film, and adding electrolyte to assemble the button cell. The charging and discharging tests are carried out on the battery by using a blue electricity (LAND) series battery test, the charging and discharging capacity of the battery is tested, and the first coulombic efficiency of the battery is the ratio of the charging capacity to the discharging capacity.
2. Full battery test
(1) Preparation of lithium ion battery
Preparation of the Positive electrode
Subjecting LiCoO to condensation2Conductive carbon black and polyvinylidene fluoride (PVDF) in a weight ratio of about 95% to 2.5% in an N-methylpyrrolidone solvent systemAnd fully stirring and uniformly mixing to obtain the anode slurry. And coating the prepared anode slurry on an anode current collector aluminum foil, drying and cold pressing to obtain the anode.
Preparation of the negative electrode
Graphite, negative electrode active materials prepared according to examples and comparative examples, and a conductive agent (conductive carbon black, Super)
Figure BDA0002273783730000151
) And binder PAA in a weight ratio of about 70%: 15%: 5%: 10%, adding an appropriate amount of water, and kneading at a solid content of about 55 wt% to 70 wt%. Adding a proper amount of water, and adjusting the viscosity of the slurry to about 4000-6000 Pa.s to prepare the cathode slurry.
And coating the prepared negative electrode slurry on a negative electrode current collector copper foil, drying and cold pressing to obtain a negative electrode.
Preparation of the electrolyte
Under dry argon atmosphere, LiPF is added into a solvent formed by mixing Propylene Carbonate (PC), Ethylene Carbonate (EC) and diethyl carbonate (DEC) (the weight ratio is about 1: 1: 1)6Mixing uniformly, wherein LiPF6The concentration of (A) was about 1.15mol/L, and about 7.5 wt% of fluoroethylene carbonate (FEC) was further added thereto and mixed uniformly to obtain an electrolyte solution.
Preparation of the separator
The PE porous polymer film is used as a separation film.
Preparation of lithium ion battery
The anode, the isolating film and the cathode are sequentially stacked, and the isolating film is positioned between the anode and the cathode to play a role in isolation. And winding to obtain the naked electric core. And arranging the bare cell in an external package, injecting electrolyte and packaging. The lithium ion battery is obtained through the technological processes of formation, degassing, edge cutting and the like.
(2) And (3) testing the cycle performance:
the test temperature was 25/45 ℃, and the test temperature was constant current charged to 4.4V at 0.7C, constant voltage charged to 0.025C, and discharged to 3.0V at 0.5C after standing for 5 minutes. And taking the capacity obtained in the step as the initial capacity, carrying out a cyclic test of 0.7C charging/0.5C discharging, and taking the ratio of the capacity of each step to the initial capacity to obtain a capacity fading curve. The cycle number of the battery with the capacity retention rate of 90% after the cycle at 25 ℃ is recorded as the room-temperature cycle performance of the battery, the cycle number of the battery with the capacity retention rate of 80% after the cycle at 45 ℃ is recorded as the high-temperature cycle performance of the battery, and the cycle performance of the materials is compared by comparing the cycle number of the two cases.
(3) And (3) testing discharge rate:
discharging to 3.0V at 0.2C at 25 ℃, standing for 5min, charging to 4.45V at 0.5C, charging to 0.05C at constant voltage, standing for 5min, adjusting discharge rate, performing discharge tests at 0.2C, 0.5C, 1C, 1.5C and 2.0C respectively to obtain discharge capacity, comparing the capacity obtained at each rate with the capacity obtained at 0.2C, and comparing rate performance by comparing the ratio of 2C to 0.2C.
(4) And (3) testing the full charge expansion rate of the battery:
and (3) testing the thickness of the fresh battery in the half-charging (50% charging State (SOC)) by using a spiral micrometer, circulating to 400 circles, and testing the thickness of the battery at the moment by using the spiral micrometer when the battery is in the full-charging (100% SOC) state, and comparing the thickness of the battery with the thickness of the fresh battery in the initial half-charging (50% SOC) state to obtain the expansion rate of the full-charging (100% SOC) battery at the moment.
Preparation of negative active material
1. For commercially purchased silicon oxide SiOx(0.6. ltoreq. x.ltoreq.1.5, and Dv50 of about 5 μm) was subjected to a classification treatment to prepare anode active materials of examples 1 to 3 and comparative examples 1 to 2:
tables 1 to 1 and tables 1 to 2 show performance test results of the anode active materials of examples 1 to 3 and comparative examples 1 and 2.
TABLE 1-1
Figure BDA0002273783730000161
Tables 1 to 2
Figure BDA0002273783730000162
Figure BDA0002273783730000171
The Dn10/Dv50 value is the cumulative 10% diameter Dn10 in the volume-based distribution and the cumulative 50% diameter D in the volume-based distribution measured by a laser scattering particle sizerVA ratio of 50, a larger value indicating a smaller number of small particles in the material.
From the test results of examples 1 to 3 and comparative examples 1 and 2, it can be seen that the cycle performance and rate capability and anti-swelling performance of the lithium ion battery prepared from the negative active material satisfying 0.1. ltoreq. Dn10/Dv 50. ltoreq.0.6 are superior to those of the lithium ion battery prepared from the negative active material of Dn10/Dv50<0.1 or 0.6< Dn10/Dv 50.
2. Preparation of a catalyst having an oxide MeO on the surfaceyNegative active material of layer
Negative active materials of examples 4 to 12 were prepared by the following methods:
(1) the negative electrode active material, the carbon precursor, and the oxide precursor wet in example 2 were mixednAdding to about 150mL of ethanol and about 1.47mL of deionized water, and stirring for about 4 hours until a homogeneous suspension is formed;
(2) spray drying (inlet temperature about 220 ℃, outlet temperature about 110 ℃) the suspension to obtain a powder; and
(3) sintering the powder at about 200900 ℃ for about 0.5-20h to obtain a powder with a surface oxide MeOyA negative active material of the layer.
Process conditions for preparing the anode active materials in examples 4 to 12 are shown in table 2-1.
TABLE 2-1
Figure BDA0002273783730000172
Figure BDA0002273783730000181
Wherein "-" means that the substance was not added.
Tables 2-2 and tables 2-3 show the performance test results of the anode active materials of examples 2 and examples 4-12.
Tables 2 to 2
Figure BDA0002273783730000182
Wherein "-" means that the substance was not added.
Tables 2 to 3
Figure BDA0002273783730000183
Figure BDA0002273783730000191
As can be seen from the test results of example 2 and examples 4 to 12, the anode active material satisfying the condition of 0.1. ltoreq. Dn10/Dv 50. ltoreq.0.6 is coated with the oxide MeOyThe layer can further improve the cycle performance and the rate capability of the lithium ion battery, and the first efficiency and the battery expansion rate are not obviously changed.
3. Preparation of negative active Material having Polymer layer on surface
Negative electrode active materials in examples 13 to 17 and 20 to 21 were prepared by the following methods:
(1) dispersing a carbon material (single-walled carbon nanotubes (SCNT) and/or multi-walled carbon nanotubes (MCNT)) and a polymer in water at a high speed for about 12 hours to obtain a uniformly mixed slurry;
(2) adding the negative active material of example 4 to the slurry uniformly mixed in (1) and stirring for about 4 hours to obtain a uniformly mixed dispersion liquid; and
(3) the dispersion was spray dried (inlet temperature about 200 ℃ C., outlet temperature about 110 ℃ C.) to give a powder.
In which negative active materials in examples 18 and 19 were prepared in a similar manner to the above method except that the solvent of the first step in examples 18 and 19 was N-vinylpyrrolidone.
Table 3-1 shows the compositions of the anode active materials of examples 13-21.
TABLE 3-1
Figure BDA0002273783730000192
Wherein "-" means that the substance was not added.
The full name of English abbreviations in Table 3-1 is as follows:
the English abbreviations in Table 3-1 are all as follows:
SCNT: single-walled carbon nanotubes
MCNT: multiwalled carbon nanotube
CMC-Na: sodium carboxymethylcellulose
PVP: polyvinylpyrrolidone
PVDF: polyvinylidene fluoride
PAANa: polyacrylamide sodium salt
Table 3-2 shows the performance test results of the negative active materials of example 4 and examples 13-21.
TABLE 3-2
Figure BDA0002273783730000201
As can be seen from the test results of example 4 and examples 13 to 21, the cycle performance and rate capability of the lithium ion battery can be significantly improved by coating a certain amount of the CNT-containing polymer layer on the basis of the negative active material in example 4.
4. Negative active materials of examples 22 to 24 and comparative example 3 were prepared as follows:
(1) respectively carrying out mechanical dry mixing and ball milling mixing on silicon dioxide and metal silicon powder in a molar ratio of about 1:1 to obtain a mixed material;
(2) at Ar2Under an atmosphere of about 10 deg.C-3-10-1Heating the mixed material at a temperature in the range of about 1100 ℃ and 1800 ℃ for about 1-25h under the kPa pressure range to obtain a gas;
(3) condensing the gas obtained to obtain a solid;
(4) crushing and screening the solid; and
(5) heat treating the solid at about 400-1500 ℃ for about 0.5-24h under a nitrogen atmosphere, cooling the heat treated solid and subjecting it to a classification treatment;
(6) coating solid obtained after classification with carbon-containing material oxide MeOyLayer, coating step see above for preparation of surface oxide MeOyA method of forming a negative active material of the layer;
(7) coating the solid obtained in the step (6) with a polymer layer containing a carbon material, specifically referring to the step of preparing the negative electrode active material having the polymer layer on the surface.
Specific process parameters in steps (1) - (5) are shown in table 4-1, and specific process parameters in step (6) are shown in table 4-2.
TABLE 4-1
Figure BDA0002273783730000211
TABLE 4-2
Figure BDA0002273783730000212
The compositions of the anode active materials in examples 22 to 24 and comparative example 3 are shown in tables 4 to 3.
Tables 4 to 3
Figure BDA0002273783730000221
Performance parameters of lithium ion batteries prepared from the negative active materials in examples 22 to 24 and comparative example 3 are shown in tables 4 to 4.
Tables 4 to 4
Figure BDA0002273783730000222
As can be seen from the test results of examples 22 to 24 and comparative example 3, under the condition that the silicon oxide satisfies 0.1. ltoreq. Dn10/Dv 50. ltoreq.0.6, 0 is further selected<I2/I1The silicon oxide with the thickness less than or equal to 1 is used for coating a metal oxide layer and a polymer layer, so that the cycle performance and the rate capability of the lithium ion battery can be further improved.
5. Negative active materials of examples 25 to 27 and comparative example 4 were prepared by the following methods.
The preparation methods of the anode active materials of examples 25 to 27 and comparative example 4 are similar to those of examples 22 to 24 and comparative example 3, respectively, except that the preparation methods of examples 25 to 27 and comparative example 4 do not include step (7). That is, the negative active materials of examples 25 to 27 and comparative example 4 had only a metal oxide coating layer and no polymer coating layer.
Table 5-1 shows the compositions of the anode active materials of examples 25-27 and comparative example 4.
TABLE 5-1
Figure BDA0002273783730000231
Tables 5-2 show the performance test results of the anode active materials of examples 25-27 and comparative example 4.
TABLE 5-2
Figure BDA0002273783730000232
As can be seen from the test results of examples 25 to 27 and comparative example 4, under the condition that the silicon oxide satisfies 0.1. ltoreq. Dn10/Dv 50. ltoreq.0.6, 0 is further selected<I2/I1The cycle performance and the rate capability of the lithium ion battery can be further improved by coating the metal oxide layer with the silicon oxide less than or equal to 1.
Reference throughout this specification to "some embodiments," "one embodiment," "another example," "an example," "a specific example," or "some examples" means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. Thus, throughout the specification, descriptions appear, for example: "in some embodiments," "in an embodiment," "in one embodiment," "in another example," "in one example," "in a particular example," or "by example," which do not necessarily refer to the same embodiment or example in this application. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.
Although illustrative embodiments have been illustrated and described, it will be appreciated by those skilled in the art that the above embodiments are not to be construed as limiting the application and that changes, substitutions and alterations can be made to the embodiments without departing from the spirit, principles and scope of the application.

Claims (20)

1. An anode material comprising a silicon composite matrix, D of the silicon composite matrixV50 is in the range of 2.5 μm to 15 μm, and the particle size distribution of the silicon composite matrix satisfies: dn10/Dv50 is more than or equal to 0.1 and less than or equal to 0.6.
2. The anode material of claim 1, wherein the silicon composite matrix comprises SiOxAnd x is more than or equal to 0.6 and less than or equal to 1.5.
3. The anode material of claim 1, wherein the silicon composite matrix comprises nano-Si grains, SiO2Or any combination thereof.
4. The anode material of claim 3, wherein the nano-Si grains are less than 100nm in size.
5. The anode material of claim 1, further comprising an oxide MeOyLayer of said oxide MeOyA layer coating at least a portion of the silicon composite matrix, wherein Me comprises at least one of Al, Si, Ti, Mn, V, Cr, Co, or Zr, wherein y is 0.5 to 3; and wherein the oxide MeOyThe layer comprises a carbon material.
6. The anode material of claim 5, wherein the oxide MeOyThe thickness of the layer is 1nm to 1000 nm.
7. The anode material of claim 5, wherein the weight percentage of Me element is 0.01 wt% to 1 wt% based on the total weight of the anode material.
8. The anode material of claim 5, wherein the oxide MeO is based on the total weight of the anode materialyThe weight percentage of carbon in the layer is 0.05 wt% to 1 wt%.
9. The anode material of claim 5, further comprising a polymer layer encapsulating the oxide MeOyAt least a portion of a layer, and the polymer layer comprises a carbon material.
10. The negative electrode material of claim 9, wherein the polymer layer comprises polyvinylidene fluoride and derivatives thereof, carboxymethylcellulose and derivatives thereof, sodium carboxymethylcellulose and derivatives thereof, polyvinylpyrrolidone and derivatives thereof, polyacrylic acid and derivatives thereof, poly styrene butadiene rubber, polyacrylamide, polyimide, polyamideimide, or any combination thereof.
11. The anode material of claim 5 or 9, wherein the carbon material comprises carbon nanotubes, carbon nanoparticles, carbon fibers, graphene, or any combination thereof.
12. The anode material of claim 9, wherein the weight percentage of the polymer layer is 0.1-10 wt% based on the total weight of the anode material.
13. The anode material of claim 9, wherein the polymer layer has a thickness of 2nm to 100 nm.
14. The negative electrode material as claimed in claim 5, which has a maximum intensity value of I in the range of 27.0 ° to 30.0 ° in terms of 2 θ in the X-ray diffraction pattern2The highest intensity value in the range of 20.0-22.0 is I1Wherein 0 is<I2/I1≤1。
15. The negative electrode material of claim 9, having a maximum intensity value, I, in an X-ray diffraction pattern, 2 Θ, falling within the range of 27.0 ° -30.0 °2The highest intensity value in the range of 20.0-22.0 is I1Wherein 0 is<I2/I1≤1。
16. The negative electrode material according to claim 1, having a specific surface area of 1 to 50m2/g。
17. A negative electrode comprising the negative electrode material of any one of claims 1-16.
18. An electrochemical device comprising the anode of claim 18.
19. The electrochemical device of claim 18, which is a lithium ion battery.
20. An electronic device comprising the electrochemical device of claim 18.
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