WO2021128200A1 - 负极材料及包含其的电化学装置和电子装置 - Google Patents

负极材料及包含其的电化学装置和电子装置 Download PDF

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WO2021128200A1
WO2021128200A1 PCT/CN2019/128837 CN2019128837W WO2021128200A1 WO 2021128200 A1 WO2021128200 A1 WO 2021128200A1 CN 2019128837 W CN2019128837 W CN 2019128837W WO 2021128200 A1 WO2021128200 A1 WO 2021128200A1
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silicon
negative electrode
electrode material
based particles
amorphous carbon
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PCT/CN2019/128837
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English (en)
French (fr)
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章婷
陈志焕
姜道义
崔航
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宁德新能源科技有限公司
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Priority to EP19897566.6A priority Critical patent/EP4109595A4/en
Priority to PCT/CN2019/128837 priority patent/WO2021128200A1/zh
Priority to JP2021540531A priority patent/JP7203990B2/ja
Publication of WO2021128200A1 publication Critical patent/WO2021128200A1/zh
Priority to US17/690,148 priority patent/US20220199985A1/en

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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
    • H01M4/48—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
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/131—Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • 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
    • 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
    • H01M4/621—Binders
    • H01M4/622—Binders being polymers
    • H01M4/623—Binders being polymers fluorinated 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
    • 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
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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

Definitions

  • This application relates to the field of energy storage, in particular to a negative electrode material and electrochemical devices and electronic devices containing the same, especially lithium ion batteries.
  • Lithium-ion batteries have occupied the mainstream position in the market by virtue of their outstanding advantages such as high energy density, high safety, no memory effect and long working life.
  • the embodiments of the present application provide a negative electrode material in an attempt to at least to some extent solve at least one problem existing in the related field.
  • the embodiments of the present application also provide a negative electrode, an electrochemical device, and an electronic device using the negative electrode material.
  • the present application provides a negative electrode material
  • the negative electrode material includes silicon-based particles
  • the silicon-based particles include a silicon-containing matrix
  • at least a part of the surface of the silicon-containing matrix has:
  • the polymer layer or the amorphous carbon layer contains carbon nanotubes
  • the silicon-based particles include a metal element, and the metal element includes Fe, Cu, Zn, Ni, Co, or any combination thereof; wherein, based on the total weight of the silicon-based particles, selected from Fe, Cu, Zn, Ni, Co The content of metal elements or any combination thereof is less than about 2500 ppm.
  • the present application provides a negative electrode, which includes the negative electrode material according to the embodiment of the present application.
  • the present application provides an electrochemical device, which includes the negative electrode according to the embodiment of the present application.
  • the present application provides an electronic device, which includes the electrochemical device according to the embodiment of the present application.
  • the lithium ion battery prepared from the negative electrode active material of the present application has reduced impedance and K value, as well as improved first-time efficiency and cycle performance.
  • FIG. 1 shows a schematic diagram of the structure of a silicon-based negative electrode active material according to an embodiment of the present application.
  • FIG. 2 shows an SEM image of the surface of the silicon-based negative electrode active material in Example 4 of the present application.
  • FIG. 3 shows the mapping spectrum of Fe element of the silicon-based negative electrode active material in Example 4 of the present application.
  • the term "about” is used to describe and illustrate small changes.
  • the term can refer to an example in which the event or situation occurs precisely and an example in which the event or situation occurs very closely.
  • the term can refer to a range of variation less than or equal to ⁇ 10% of the stated 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%.
  • a list of items connected by the terms “one of”, “one of”, “one of” or other similar terms can mean any of the listed items.
  • Project A can contain a single element or multiple elements.
  • Project B can contain a single element or multiple elements.
  • Project C can contain a single element or multiple elements.
  • a list of items connected by the terms “at least one of”, “at least one of”, “at least one of” or other similar terms may mean the listed items Any combination of. For example, if items A and B are listed, then the phrase “at least one of A and B” means only A; only B; or A and B. In another example, if items A, B, and C are listed, then the phrase "at least one of A, B, and C” means only A; or only B; only C; A and B (excluding C); A and C (exclude B); B and C (exclude A); or all of A, B, and C.
  • Project A can contain a single element or multiple elements.
  • Project B can contain a single element or multiple elements.
  • Project C can contain a single element or multiple elements.
  • the present application provides an anode material, wherein the anode material includes silicon-based particles, the silicon-based particles include a silicon-containing matrix, and at least a portion of the surface of the silicon-containing matrix has:
  • the polymer layer or the amorphous carbon layer contains carbon nanotubes
  • the silicon-based particles include a metal element, and the metal element includes Fe, Cu, Zn, Ni, Co, or any combination thereof; wherein, based on the total weight of the silicon-based particles, selected from Fe, Cu, Zn, Ni, Co
  • the content of metal elements or any combination thereof is less than about 2500 ppm.
  • the entire surface of the silicon-containing substrate has: (i) a polymer layer, and/or (ii) an amorphous carbon layer.
  • the content of a metal element selected from Fe, Cu, Zn, Ni, Co, or any combination thereof is less than about 2200 ppm. In some embodiments, based on the total weight of the silicon-based particles, the content of a metal element selected from Fe, Cu, Zn, Ni, Co, or any combination thereof is about 2000 ppm, about 1800 ppm, about 1500 ppm, about 1200 ppm, about 1000 ppm, about 800 ppm, about 500 ppm, about 200 ppm, about 100 ppm, or a range composed of any two of these values.
  • the average particle size of the silicon-based particles is about 500 nm-30 ⁇ m. In some embodiments, the average particle size of the silicon-based particles is about 1 ⁇ m-25 ⁇ m. In some embodiments, the average particle size of the silicon-based particles is about 5 ⁇ m, about 10 ⁇ m, about 15 ⁇ m, about 20 ⁇ m, or a range composed of any two of these values.
  • the silicon-containing matrix includes SiO x , and 0.6 ⁇ x ⁇ 1.5.
  • the silicon-containing matrix includes Si, SiO, SiO 2 , SiC, or any combination thereof.
  • the particle size of the Si is less than about 100 nm. In some embodiments, the particle size of the Si is less than about 50 nm. In some embodiments, the particle size of the Si is less than about 20 nm. In some embodiments, the particle size of the Si is less than about 5 nm. In some embodiments, the particle size of the Si is less than about 2 nm. In some embodiments, the particle size of the Si is less than about 0.5 nm.
  • the Si particle size is about 10 nm, about 20 nm, about 30 nm, about 40 nm, about 50 nm, about 60 nm, about 70 nm, about 80 nm, about 90 nm, or a range of any two of these values.
  • the polymer layer includes the following polymers: carboxymethyl cellulose, polyacrylic acid, polyacrylonitrile, polyvinyl alcohol, polyvinylpyrrolidone, polyaniline, polyimide, polyamideimide Amine, polysiloxane, polystyrene butadiene rubber, epoxy resin, polyester resin, polyurethane resin, polyfluorene or any combination thereof.
  • the amorphous carbon in the amorphous carbon layer is obtained by sintering the following polymers: carboxymethyl cellulose, polyacrylic acid, polyacrylonitrile, polyvinyl alcohol, polyvinylpyrrolidone, polyaniline , Polyimide, polyamideimide, polysiloxane, polystyrene butadiene rubber, epoxy resin, polyester resin, polyurethane resin, polyfluorene or any combination thereof.
  • the content of the polymer layer or the amorphous carbon layer is about 0.05-15 wt%. In some embodiments, based on the total weight of the silicon-based particles, the content of the polymer layer or the amorphous carbon layer is about 1-10 wt%.
  • the content of the polymer layer or the amorphous carbon layer is about 2wt%, about 3wt%, about 4wt%, about 5wt%, about 6wt% , About 7% by weight, about 8% by weight, about 9% by weight, about 10% by weight, about 11% by weight, about 12% by weight, about 13% by weight, about 14% by weight, about 14% by weight, or a range of any two of these values.
  • the thickness of the polymer layer or the amorphous carbon layer is about 2 nm-200 nm. In some embodiments, the thickness of the polymer layer or the amorphous carbon layer is about 10 nm-150 nm. In some embodiments, the thickness of the polymer layer or the amorphous carbon layer is about 50 nm-100 nm.
  • the thickness of the polymer layer or the amorphous carbon layer is about 5nm, about 10nm, about 20nm, about 30nm, about 40nm, about 50nm, about 60nm, about 70nm, about 80nm, about 90nm , About 100nm, about 110nm, about 120nm, about 130nm, about 140nm, about 150nm, about 160nm, about 170nm, about 180nm, about 190nm, about 200nm, or a range composed of any two of these values.
  • the carbon nanotubes include single-walled carbon nanotubes, multi-walled carbon nanotubes, or a combination thereof.
  • the diameter of the carbon nanotubes is about 1-30 nm. In some embodiments, the diameter of the carbon nanotubes is about 5-20 nm. In some embodiments, the diameter of the carbon nanotubes is about 10 nm, about 15 nm, about 20 nm, about 25 nm, about 30 nm, or a range composed of any two of these values.
  • the aspect ratio of the carbon nanotubes is about 50-30000. In some embodiments, the aspect ratio of the carbon nanotubes is about 100-20000. In some embodiments, the aspect ratio of the carbon nanotubes is about 500, about 2000, about 5000, about 10000, about 15000, about 2000, about 25000, about 30,000, or a range composed of any two of these values.
  • the content of the carbon nanotubes is about 0.01-10 wt% based on the total weight of the silicon-based particles. In some embodiments, the content of the carbon nanotubes is about 1-8 wt% based on the total weight of the silicon-based particles. In some embodiments, based on the total weight of the silicon-based particles, the content of the carbon nanotubes is about 0.02% by weight, about 0.05% by weight, about 0.1% by weight, about 0.5% by weight, about 1% by weight, about 1.5% by weight.
  • the weight ratio of the polymer in the polymer layer or the amorphous carbon in the amorphous carbon layer to the carbon nanotubes is about 1:5-10:1. In some embodiments, the weight ratio of the polymer in the polymer layer or the amorphous carbon in the amorphous carbon layer to the carbon nanotubes is about 1:5, about 1:3, or about 1: 1. About 3:1, about 5:1, about 7:1, about 8:1, about 10:1, or a range composed of any two of these values.
  • the specific surface area of the silicon-based particles is about 2.5-15 m 2 /g. In some embodiments, the specific surface area of the silicon-based particles is about 5-10 m 2 /g. In some embodiments, the specific surface area of the silicon-based particles is about 3m 2 /g, about 4m 2 /g, about 6m 2 /g, about 8m 2 /g, about 10m 2 /g, about 12m 2 /g , About 14m 2 /g or the range of any two of these values.
  • any of the foregoing negative electrode materials further includes graphite particles.
  • the weight ratio of the graphite particles to the silicon-based particles is about 3:1-20:1. In some embodiments, the weight ratio of the graphite particles to the silicon-based particles is about 3:1, about 5:1, about 6:1, about 7:1, about 10:1, about 12:1, Approximately 15:1, approximately 18:1, approximately 20:1, or a range composed of any two of these values.
  • the embodiment of the present application provides a method for preparing any of the foregoing negative electrode materials, and the method includes:
  • the method further includes the step of mixing the aforementioned silicon-based particles with graphite particles.
  • the weight ratio of the graphite particles to the silicon-based particles is about 3:1, about 5:1, about 6:1, about 7:1, about 10:1, about 12:1, Approximately 15:1, approximately 18:1, approximately 20:1, or a range composed of any two of these values.
  • the definitions of the silicon-containing matrix, the carbon nanotubes, and the polymer are as described above, respectively.
  • the weight ratio of the polymer to the carbon nanotube powder is about 1:10-10:1. In some embodiments, the weight ratio of the polymer to the carbon nanotube powder is about 1:8, about 1:5, about 1:3, about 1:1, about 3:1, about 5:1 , About 7:1, about 10:1, or a range of any two of these values.
  • the weight ratio of silicon-containing matrix to polymer is about 200:1 to 5:1. In some embodiments, the weight ratio of silicon-containing matrix to polymer is about 150:1 to 5:1. In some embodiments, the weight ratio of the silicon-containing matrix to the polymer is about 200:1, about 150:1, about 100:1, about 50:1, about 10:1, about 1:1, and about 5:1. Or a range composed of any two of these values.
  • the solvent includes water, ethanol, methanol, n-hexane, N,N-dimethylformamide, pyrrolidone, acetone, toluene, isopropanol, or any combination thereof.
  • the dispersion time in step (1) is about 1 h, about 5 h, about 10 h, about 15 h, about 20 h, about 24 h, or a range composed of any two of these values.
  • the dispersion time in step (2) is about 2h, about 2.5h, about 3h, about 3.5h, about 4, or a range composed of any two of these values.
  • the method for removing the solvent in step (3) includes rotary evaporation, spray drying, filtration, freeze drying, or any combination thereof.
  • a sintering step is further included between step (3) and step (4).
  • the sintering temperature is about 250-900°C. In some embodiments, the sintering temperature is about 300-850°C. In some embodiments, the sintering temperature is about 350-650°C. In some embodiments, the sintering temperature is about 400°C, about 500°C, about 600°C, or about 700°C, or a range of any two of these values.
  • the sintering time is about 1-25h. In some embodiments, the sintering time is about 1-19h. In some embodiments, the sintering time is about 1-14h. In some embodiments, the sintering time is about 1h, about 1.5h, about 2h, about 2.5h, about 3h, about 5h, about 8h, about 10h, about 15h, about 20h, or a range composed of any two of these values .
  • sintering is performed under the protection of inert gas.
  • the inert gas includes nitrogen, argon, or a combination thereof.
  • the sieving in step (4) is sieved through 400 mesh.
  • FIG. 1 shows a schematic diagram of the structure of a silicon-based negative electrode active material according to an embodiment of the present application.
  • the inner layer 1 is a silicon-containing matrix
  • the outer layer 2 is a polymer layer containing carbon nanotubes.
  • the polymer layer containing carbon nanotubes (CNT) is distributed on the surface of the silicon-containing matrix.
  • the polymer can be used to bind the CNT on the surface of the silicon-based negative electrode active material, which is beneficial to improve the interface stability of the CNT on the surface of the negative electrode active material, thereby improving Its cycle performance.
  • the silicon-based anode material has a high gram capacity of 1500-4200mAh/g and is the most promising next-generation lithium-ion battery anode material.
  • the volume expansion of silicon during charging and discharging is about 300%, and the unstable solid electrolyte interface membrane (SEI) formed on the surface greatly affects the performance of the battery.
  • methods to improve the cycle stability and rate performance of silicon-based materials include: designing porous silicon-based materials, reducing the size of silicon-oxygen materials, using polymer coating, oxide coating, and carbon coating.
  • commonly used coatings include carbon coatings.
  • the carbon coating layer is liable to be broken during the cycle, thereby causing a sharp decrease in conductivity and poor cycle performance.
  • the polymer coating can form a good bond with the surface of the silicon material, but its conductivity is usually poor, so the impedance is relatively large.
  • Carbon nanotubes (CNT) have high mechanical properties and excellent electrical conductivity, so they can be used as coating materials on the surface of silicon materials.
  • the highly conductive CNT has a weak bonding force with the surface of the silicon material and is difficult to disperse, so it is difficult to form a uniform coating layer on the surface of the silicon material.
  • the present application first prepared silicon-based particles having a polymer layer or an amorphous carbon layer on at least a part of the surface of a silicon-containing substrate, and the polymer layer or the amorphous carbon layer contained carbon nanotubes (CNT ).
  • CNT carbon nanotubes
  • a polymer layer containing carbon nanotubes or an amorphous carbon layer is coated on the surface of the silicon-based negative electrode active material.
  • the polymer or amorphous carbon can be used to bind the CNT on the surface of the negative electrode active material, which is beneficial to improve the activity of CNT in the negative electrode.
  • the interface stability of the material surface while suppressing the volume expansion of the silicon-based material to improve its cycle stability.
  • metal catalysts such as nickel-based (Ni), cobalt-based (Co), iron-based (Fe), vanadium-based (V), and magnesium-based catalysts are usually used in the preparation of carbon nanotubes.
  • Ni nickel-based
  • Co cobalt-based
  • Fe iron-based
  • V vanadium-based
  • magnesium-based catalysts are usually used in the preparation of carbon nanotubes.
  • Mg copper-based
  • Cu copper-based
  • Zn zinc-based
  • these metal elements usually remain on the manufactured carbon nanotubes, so they will inevitably be introduced into the carbon nanotubes and polymerized Or amorphous carbon composite layer on the silicon-based negative electrode active material.
  • metal elements are also introduced due to processes such as pulverization and classification. The reduction potential of these metal elements is lower than that of lithium ions.
  • the inventor of the present application found that when the content of a metal element selected from Fe, Cu, Zn, Ni, Co or any combination thereof in the silicon-based negative electrode active material is less than about 2500 ppm, the K value and impedance of the lithium ion battery prepared therefrom It is significantly lower than the above-mentioned lithium ion battery with a metal element content greater than about 2500 ppm, and the first-time efficiency and cycle performance are significantly better than the above-mentioned lithium ion battery with a metal element content greater than about 2500 ppm.
  • the embodiment of the present application provides a negative electrode.
  • the negative electrode includes a current collector and a negative active material layer on the current collector.
  • the anode active material layer includes the anode material according to an embodiment of the present application.
  • the negative active material layer includes a binder.
  • the binder includes, but is not limited to: polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyfluoro Ethylene, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene butadiene rubber, acrylic (ester) styrene butadiene Rubber, epoxy or nylon.
  • the negative active material layer includes a conductive material.
  • 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.
  • the current collector includes, but is not limited to: copper foil, nickel foil, stainless steel foil, titanium foil, foamed nickel, foamed copper, or a polymer substrate coated with conductive metal.
  • the negative electrode may be obtained by mixing the active material, the conductive material, and the binder in a solvent to prepare an active material composition, and coating the active material composition on a current collector.
  • the solvent may include, but is not limited to: deionized water, N-methylpyrrolidone.
  • the material, composition, and manufacturing method of the positive electrode that can be used in the embodiments of the present application include any technology disclosed in the prior art.
  • the positive electrode is the one described in the US patent application US9812739B, which is incorporated into this application by reference in its entirety.
  • the positive electrode includes a current collector and a positive electrode active material layer on the current collector.
  • the positive active material includes, but is not limited to: lithium cobalt oxide (LiCoO 2 ), lithium nickel cobalt manganese (NCM) ternary material, lithium iron phosphate (LiFePO 4 ), or lithium manganate (LiMn 2 O 4 ).
  • the positive active material layer further includes a binder, and optionally a conductive material.
  • the binder improves the bonding of the positive electrode active material particles to each other, and also improves the bonding of the positive electrode active material to the current collector.
  • the binder includes, but is not limited to: polyvinyl alcohol, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene-containing Oxygen polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene butadiene rubber, acrylic (ester) styrene butadiene rubber, epoxy resin or Nylon etc.
  • conductive materials include, but are not limited to: carbon-based materials, metal-based materials, conductive polymers, and mixtures thereof.
  • the carbon-based material is selected from natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, or any combination thereof.
  • the metal-based material is selected from metal powder, metal fiber, copper, nickel, aluminum, or silver.
  • the conductive polymer is a polyphenylene derivative.
  • the current collector may include, but is not limited to: aluminum.
  • the positive electrode can be prepared by a preparation method known in the art.
  • the positive electrode can be obtained by mixing an active material, a conductive material, and a binder in a solvent to prepare an active material composition, and coating the active material composition on a current collector.
  • the solvent may include, but is not limited to: N-methylpyrrolidone.
  • the electrolyte that can be used in the embodiments of the present application may be an electrolyte known in the prior art.
  • the electrolyte includes an organic solvent, a lithium salt, and additives.
  • the organic solvent of the electrolytic solution according to the present application may be any organic solvent known in the prior art that can be used as a solvent of the electrolytic solution.
  • the electrolyte used in the electrolyte solution according to the present application is not limited, and it may be any electrolyte known in the prior art.
  • the additive of the electrolyte according to the present application can be any additive known in the prior art that can be used as an additive of the electrolyte.
  • 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.
  • the lithium salt includes at least one of an organic lithium salt or an inorganic lithium salt.
  • the lithium salt includes, but is not limited to: lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ), lithium difluorophosphate (LiPO 2 F 2 ), bistrifluoromethanesulfonimide Lithium LiN(CF 3 SO 2 ) 2 (LiTFSI), Lithium bis(fluorosulfonyl)imide Li(N(SO 2 F) 2 )(LiFSI), Lithium bisoxalate borate LiB(C 2 O 4 ) 2 (LiBOB ) Or LiBF 2 (C 2 O 4 ) (LiDFOB).
  • LiPF 6 lithium hexafluorophosphate
  • LiBF 4 lithium difluorophosphate
  • LiPO 2 F 2 lithium difluorophosphate
  • LiTFSI bistrifluoromethanesulfonimide Lithium LiN(CF 3 SO 2 ) 2
  • LiFSI Lithium bis(flu
  • the concentration of the lithium salt in the electrolyte is about 0.5-3 mol/L, about 0.5-2 mol/L, or about 0.8-1.5 mol/L.
  • a separator is provided between the positive electrode and the negative electrode to prevent short circuits.
  • the material and shape of the isolation film that can be used in the embodiments of the present application are not particularly limited, and they can be any technology disclosed in the prior art.
  • the isolation membrane includes a polymer or an inorganic substance formed of a material that is stable to the electrolyte of the present application.
  • the isolation film may include a substrate layer and a surface treatment layer.
  • the substrate layer is a non-woven fabric, film or composite film with a porous structure, and the material of the substrate layer is selected from at least one of polyethylene, polypropylene, polyethylene terephthalate and polyimide.
  • a polypropylene porous film, a polyethylene porous film, a polypropylene non-woven fabric, a polyethylene non-woven fabric, or a polypropylene-polyethylene-polypropylene porous composite film can be selected.
  • a surface treatment layer is provided on at least one surface of the substrate layer.
  • the surface treatment layer may be a polymer layer or an inorganic substance layer, or a layer formed by a mixed polymer and an inorganic substance.
  • the inorganic layer includes inorganic particles and a binder.
  • the inorganic particles are selected from alumina, silica, magnesium oxide, titanium oxide, hafnium dioxide, tin oxide, ceria, nickel oxide, zinc oxide, calcium oxide, zirconium oxide, One or a combination of yttrium oxide, silicon carbide, boehmite, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, and barium sulfate.
  • the binder is selected from polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, polyamide, polyacrylonitrile, polyacrylate, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, One or a combination of polymethyl methacrylate, polytetrafluoroethylene and polyhexafluoropropylene.
  • the polymer layer contains a polymer, and the material of the polymer is selected from polyamide, polyacrylonitrile, acrylate polymer, polyacrylic acid, polyacrylate, polyvinylpyrrolidone, polyvinyl ether, polyvinylidene fluoride or polyvinylidene fluoride. At least one of (vinylidene fluoride-hexafluoropropylene).
  • the embodiment of the present application provides an electrochemical device, which includes any device that undergoes an electrochemical reaction.
  • 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 placed between the positive electrode and the negative electrode membrane.
  • the electrochemical device of the present application includes, but is not limited to: all kinds of primary batteries, secondary batteries, fuel cells, solar cells, or capacitors.
  • the electrochemical device is a lithium secondary battery.
  • 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.
  • the electronic device of the present application may be any device that uses the electrochemical device according to the embodiment of the present application.
  • the electronic device includes, but is not limited to: notebook computers, pen-input computers, mobile computers, e-book players, portable phones, portable fax machines, portable copiers, portable printers, and stereo headsets , Video recorders, LCD TVs, portable cleaners, portable CD players, mini discs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, assisted bicycles, bicycles , Lighting equipment, toys, game consoles, clocks, electric tools, flashlights, cameras, large household storage batteries or lithium-ion capacitors, etc.
  • Powder electronic conductivity test The four-wire two-terminal method is used to determine the resistance by measuring the voltage and current flowing through the resistance to be measured, and calculate the conductivity by combining the height and bottom area of the resistance to be measured. Take a certain amount of powder and add it to the test mold, shake it gently, then place the gasket on the mold on the sample; after the sample is loaded, place the mold on the worktable of the electronic pressure testing machine at a rate of 5mm/min Raise to 500kg (159Mpa), constant pressure for 60s, and then release the pressure to 0; when the sample constant pressure reaches 5000 ⁇ 2kg (15-25s after the pressure rises to 5000kg), record the sample pressure, read the deformation height of the sample, and record this time If the resistance tester shows the value, the formula can be used to calculate the electronic conductivity.
  • Powder Weigh 0.2g of the silicon-based negative electrode active material in each example and comparative example, and place it in a polytetrafluoroethylene (PTFE) beaker. After the digital balance is stable, record the weight of the sample to the nearest 0.0001g. Slowly add 10 mL of concentrated HNO 3 and 2 mL of HF to the sample, place it on a flat heater at 220°C, and heat to digest until almost evaporated to dryness. Slowly add 10 mL of nitric acid and continue heating and digestion for 15 minutes to fully dissolve the sample. Place the dissolved sample in a fume hood and cool to room temperature.
  • PTFE polytetrafluoroethylene
  • Negative electrode After scraping off the negative electrode surface active material obtained in each example and comparative example, heat treatment at 600°C for 2h, then weigh the above heat-treated active material, and use the same test method as the powder sample to determine the metal element content .
  • SEM test The SEM characterization was recorded by PhilipsXL-30 field emission scanning electron microscope, and the test was performed under the conditions of 10kV, 10mA.
  • TEM test Jeol JEM2100F is used for test and characterization.
  • EDS Energy spectrometer
  • Mapping Both EDS test and Mapping are characterized by OXFORD-EDS, and the voltage is 20kV.
  • LiPF 6 In a dry argon atmosphere, add LiPF 6 to a solvent mixed with propylene carbonate (PC), ethylene carbonate (EC), and diethyl carbonate (DEC) (weight ratio 1:1:1), and mix Uniform, where the concentration of LiPF 6 is 1.15 mol/L, and after adding about 7.5 wt% of fluoroethylene carbonate (FEC), mixing uniformly to obtain an electrolyte.
  • PC propylene carbonate
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • the silicon-based negative electrode active material, conductive acetylene black and binder PAA (modified polyacrylic acid, PAA) obtained in the examples and comparative examples were added to deionized water at a weight ratio of 80:10:10, and stirred to form a slurry.
  • the doctor blade is applied to form a coating with a thickness of 100 ⁇ m, and it is dried in a vacuum drying oven at 85°C for 12 hours. In a dry environment, it is cut into a disc with a diameter of 1cm by a punching machine.
  • the metal lithium sheet is used as a pair in a glove box.
  • Electrode, isolation membrane choose ceglard composite membrane, add electrolyte to assemble button cell. Charge and discharge the battery with LAND series battery test.
  • the first calculation method of efficiency is the capacity when the lithium insertion cut-off voltage is 0.8V/the capacity corresponding to the lithium delithiation voltage cut-off to 0.005V.
  • High-temperature cycle performance test the test temperature is 45°C, the constant current is 0.7C to 4.4V, the constant voltage is charged to 0.025C, and after standing for 5 minutes, it is discharged to 3.0V at 0.5C.
  • the capacity obtained in this step is the initial capacity, and the 0.7C charge/0.5C discharge is performed for the cycle test.
  • the capacity of each step is used as the ratio of the initial capacity to obtain the capacity attenuation curve (the capacity attenuation curve takes the number of cycles as the X axis, and the capacity The retention rate is on the Y axis). The number of cycles up to the capacity retention rate of 80% from the 45°C cycle was recorded to compare the high temperature cycle performance of the battery.
  • Discharge rate test at 25°C, discharge to 3.0V at 0.2C, let stand for 5min, charge at 0.5C to 4.4V, charge to 0.05C at constant voltage, then stand for 5 minutes, adjust the discharge rate to 0.2 C, 0.5C, 1C, 1.5C, 2.0C discharge test, respectively obtain the discharge capacity, the capacity obtained under each rate is compared with the capacity obtained at 0.2C to obtain the ratio, and the rate performance is compared by comparing the ratio.
  • DC resistance (DCR) test Use a Maccor machine to test the actual capacity of the battery at 25°C (0.7C constant current charge to 4.4V, constant voltage charge to 0.025C, stand for 10 minutes, discharge to 3.0V at 0.1C, Let it stand for 5 minutes) Discharge at 0.1C under a certain state of charge (SOC), test the 1s discharge with 5ms for sampling points, and calculate the DCR value under different SOCs.
  • SOC state of charge
  • LiCoO 2 , conductive carbon black and polyvinylidene fluoride (PVDF) are fully stirred and mixed uniformly in an N-methylpyrrolidone solvent system in a weight ratio of 96.7%:1.7%:1.6% to prepare a positive electrode slurry.
  • the prepared positive electrode slurry is coated on the positive electrode current collector aluminum foil, dried, and cold pressed to obtain a positive electrode.
  • the graphite and the silicon-based negative electrode active material in the examples were mixed in a weight ratio of 89:11 to obtain a mixed negative electrode active material with a gram capacity of 500mAh/g.
  • the mixed negative electrode active material, conductive agent acetylene black, and PAA were mixed in a weight ratio of 95 : 1.2:3.8 Fully stir in deionization, after mixing uniformly, coating on Cu foil, drying and cold pressing, to obtain negative pole piece.
  • LiPF 6 In a dry argon environment, add LiPF 6 to a solvent mixed with propylene carbonate (PC), ethylene carbonate (EC), and diethyl carbonate (DEC) (weight ratio 1:1:1) and mix well , The concentration of LiPF 6 is 1 mol/L, and 10 wt% of fluoroethylene carbonate (FEC) is added and mixed uniformly to obtain an electrolyte.
  • PC propylene carbonate
  • EC ethylene carbonate
  • DEC diethyl carbonate
  • the PE porous polymer film is used as the isolation membrane.
  • the positive electrode, the separator film, and the negative electrode are stacked in order, so that the separator film is located between the positive electrode and the negative electrode for isolation, and the electric core is obtained by winding.
  • Put the cell in the outer package inject the electrolyte, and encapsulate it. After forming, degassing, trimming and other technological processes, a lithium ion battery is obtained.
  • the silicon-based negative electrode active materials in Examples 1-9 and Comparative Examples 1-6 were prepared by the following method:
  • step (1) Add SiO (Dv50 is 3 ⁇ m) to the uniformly mixed slurry in step (1), and stir for about 4 hours to obtain a uniformly mixed dispersion;
  • the silicon-based negative electrode active materials in Examples 10-12 and Comparative Example 7 were prepared by the following methods:
  • the preparation methods of the silicon-based negative electrode active materials in Examples 10-12 and Comparative Example 7 are similar to those in Examples 1-9 and Comparative Examples 1-6. Including a sintering step, the sintering condition is under the protection of nitrogen, the temperature is raised to 600°C at 3°C/min, and the temperature is kept for 2h.
  • Table 1 shows the types and amounts of various substances used in the preparation methods of the silicon-based negative electrode active materials in Examples 1-12 and Comparative Examples 1-7.
  • Table 2 shows the types and contents of metal elements in the silicon-based anode active materials in Examples 1-12 and Comparative Examples 1-7, and the foregoing contents are all calculated based on the total weight of the silicon-based anode active material.
  • Table 3 shows the relevant performance parameters of the silicon-based negative electrode active materials in Examples 1-12 and Comparative Examples 1-7.
  • the first calculation method of efficiency is the capacity when the lithium insertion cut-off voltage is 0.8V / the capacity corresponding to the delithiation voltage cut-off to 0.005V
  • Figure 2 shows the SEM image of the surface of the silicon-based negative electrode active material in Example 4 of the present application, in which the dotted frame is mainly a polymer layer containing CNT; and Figure 3 shows the active material of the silicon-based negative electrode in Example 4 of the present application. Mapping map of material Fe element.
  • Figures 2-3 illustrate the surface morphology and the Mapping spectrum of Fe element on the surface of Example 4.
  • references to “some embodiments”, “partial embodiments”, “one embodiment”, “another example”, “examples”, “specific examples” or “partial examples” throughout the specification mean At least one embodiment or example in this application includes the specific feature, structure, material, or characteristic described in the embodiment or example. Therefore, descriptions appearing in various places throughout the specification, such as: “in some embodiments”, “in embodiments”, “in one embodiment”, “in another example”, “in an example “In”, “in a specific example” or “exemplified”, which are not necessarily quoting the same embodiment or example in this application.
  • the specific features, structures, materials, or characteristics herein can be combined in one or more embodiments or examples in any suitable manner.

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Abstract

一种负极材料及包含其的电化学装置和电子装置。该负极材料包括硅基颗粒，所述硅基颗粒包括含硅基体，所述含硅基体的至少一部分表面具有：(i)聚合物层，和/或(ii)无定形碳层形，并且所述聚合物层或无定形碳层包含碳纳米管，所述硅基颗粒包含金属元素，所述金属元素包含Fe、Cu、Zn、Ni、Co或其任意组合；其中基于所述硅基颗粒的总重量，选自Fe、Cu、Zn、Ni、Co或其任意组合的金属元素的含量小于约2500ppm。该负极材料制备的锂离子电池具有降低的阻抗和K值，以及提升的首次效率和循环性能。

Description

负极材料及包含其的电化学装置和电子装置 技术领域
本申请涉及储能领域，具体涉及一种负极材料及包含其的电化学装置和电子装置，特别是锂离子电池。
背景技术
随着消费电子类的产品如笔记本电脑、手机、平板电脑、移动电源和无人机等的普及，对其中的电化学装置的要求越来越严格。例如，不仅要求电池轻便，而且还要求电池拥有高容量和较长的工作寿命。锂离子电池凭借其具有能量密度高、安全性高、无记忆效应和工作寿命长等突出的优点已经在市场上占据主流地位。
发明内容
本申请实施例提供了一种负极材料，以试图在至少某种程度上解决至少一种存在于相关领域中的问题。本申请实施例还提供了使用该负极材料的负极、电化学装置以及电子装置。
在一个实施例中，本申请提供了一种负极材料，所述负极材料包括硅基颗粒，所述硅基颗粒包括含硅基体，所述含硅基体的至少一部分表面具有：
(i)聚合物层，和/或
(ii)无定形碳层，
并且所述聚合物层或无定形碳层包含碳纳米管，
所述硅基颗粒包含金属元素，所述金属元素包含Fe、Cu、Zn、Ni、Co或其任意组合；其中基于所述硅基颗粒的总重量，选自Fe、Cu、Zn、Ni、Co或其任意组合的金属元素的含量小于约2500ppm。
在另一个实施例中，本申请提供一种负极，其包括根据本申请的实施例所述的负极材料。
在另一个实施例中，本申请提供一种电化学装置，其包括根据本申请的实施例所述 的负极。
在另一个实施例中，本申请提供一种电子装置，其包括根据本申请的实施例所述的电化学装置。
由本申请负极活性材料制备的锂离子电池具有降低的阻抗和K值，以及提升的首次效率和循环性能。
本申请实施例的额外层面及优点将部分地在后续说明中描述和显示，或是经由本申请实施例的实施而阐释。
附图说明
在下文中将简要地说明为了描述本申请实施例或现有技术所必要的附图以便于描述本申请的实施例。显而易见地，下文描述中的附图仅只是本申请中的部分实施例。对本领域技术人员而言，在不需要创造性劳动的前提下，依然可以根据这些附图中所例示的结构来获得其他实施例的附图。
图1示出了本申请一个实施例的硅基负极活性材料的结构示意图。
图2示出了本申请实施例4中硅基负极活性材料表面的SEM图片。
图3示出了本申请实施例4中硅基负极活性材料Fe元素的Mapping图谱。
具体实施方式
本申请的实施例将会被详细的描示在下文中。本申请的实施例不应该被解释为对本申请的限制。
如本申请中所使用，术语“约”用以描述及说明小的变化。当与事件或情形结合使用时，所述术语可指代其中事件或情形精确发生的例子以及其中事件或情形极近似地发生的例子。举例来说，当结合数值使用时，术语可指代小于或等于所述数值的±10％的变化范围，例如小于或等于±5％、小于或等于±4％、小于或等于±3％、小于或等于±2％、小于或等于±1％、小于或等于±0.5％、小于或等于±0.1％、或小于或等于±0.05％。
另外，有时在本文中以范围格式呈现量、比率和其它数值。应理解，此类范围格式是用于便利及简洁起见，且应灵活地理解，不仅包含明确地指定为范围限制的数值，而 且包含涵盖于所述范围内的所有个别数值或子范围，如同明确地指定每一数值及子范围一般。
在具体实施方式及权利要求书中，由术语“中的一者”、“中的一个”、“中的一种”或其他相似术语所连接的项目的列表可意味着所列项目中的任一者。例如，如果列出项目A及B，那么短语“A及B中的一者”意味着仅A或仅B。在另一实例中，如果列出项目A、B及C，那么短语“A、B及C中的一者”意味着仅A；仅B；或仅C。项目A可包含单个元件或多个元件。项目B可包含单个元件或多个元件。项目C可包含单个元件或多个元件。
在具体实施方式及权利要求书中，由术语“中的至少一者”、“中的至少一个”、“中的至少一种”或其他相似术语所连接的项目的列表可意味着所列项目的任何组合。例如，如果列出项目A及B，那么短语“A及B中的至少一者”意味着仅A；仅B；或A及B。在另一实例中，如果列出项目A、B及C，那么短语“A、B及C中的至少一者”意味着仅A；或仅B；仅C；A及B(排除C)；A及C(排除B)；B及C(排除A)；或A、B及C的全部。项目A可包含单个元件或多个元件。项目B可包含单个元件或多个元件。项目C可包含单个元件或多个元件。
一、负极材料
在一些实施例中，本申请提供了一种负极材料，其中所述负极材料包括硅基颗粒，所述硅基颗粒包括含硅基体，所述含硅基体的至少一部分表面具有：
(i)聚合物层，和/或
(ii)无定形碳层，
并且所述聚合物层或无定形碳层包含碳纳米管，
所述硅基颗粒包含金属元素，所述金属元素包含Fe、Cu、Zn、Ni、Co或其任意组合；其中基于所述硅基颗粒的总重量，选自Fe、Cu、Zn、Ni、Co或其任意组合的金属元素的含量小于约2500ppm。在另一些实施例中，所述含硅基体的全部表面具有：(i)聚合物层，和/或(ii)无定形碳层。
在一些实施例中，基于所述硅基颗粒的总重量，选自Fe、Cu、Zn、Ni、Co或其任意组合的金属元素的含量小于约2200ppm。在一些实施例中，基于所述硅基颗粒的总重量，选自 Fe、Cu、Zn、Ni、Co或其任意组合的金属元素的含量为约2000ppm、约1800ppm、约1500ppm、约1200ppm、约1000ppm、约800ppm、约500ppm、约200ppm、约100ppm或者这些数值中任意两者组成的范围。
在一些实施例中，所述硅基颗粒的平均粒径为约500nm-30μm。在一些实施例中，所述硅基颗粒的平均粒径为约1μm-25μm。在一些实施例中，所述硅基颗粒的平均粒径为约5μm、约10μm、约15μm、约20μm或者这些数值中任意两者组成的范围。
在一些实施例中，所述含硅基体包括SiO x，且0.6≤x≤1.5。
在一些实施例中，所述含硅基体包括Si、SiO、SiO 2、SiC或其任意组合。
在一些实施例中，所述Si的颗粒尺寸为小于约100nm。在一些实施例中，所述Si的颗粒尺寸为小于约50nm。在一些实施例中，所述Si的颗粒尺寸为小于约20nm。在一些实施例中，所述Si的颗粒尺寸为小于约5nm。在一些实施例中，所述Si的颗粒尺寸为小于约2nm。在一些实施例中，所述Si的颗粒尺寸为小于约0.5nm。在一些实施例中，所述Si的颗粒尺寸为约10nm、约20nm、约30nm、约40nm、约50nm、约60nm、约70nm、约80nm、约90nm或者这些数值中任意两者组成的范围。
在一些实施例中，所述聚合物层包含以下聚合物：羧甲基纤维素、聚丙烯酸、聚丙烯腈、聚乙烯醇、聚乙烯基吡咯烷酮、聚苯胺、聚酰亚胺、聚酰胺酰亚胺、聚硅氧烷、聚丁苯橡胶、环氧树脂、聚酯树脂、聚氨酯树脂、聚芴或其任意组合。
在一些实施例中，所述无定形碳层中的无定形碳为以下聚合物经烧结后得到：羧甲基纤维素、聚丙烯酸、聚丙烯腈、聚乙烯醇、聚乙烯基吡咯烷酮、聚苯胺、聚酰亚胺、聚酰胺酰亚胺、聚硅氧烷、聚丁苯橡胶、环氧树脂、聚酯树脂、聚氨酯树脂、聚芴或其任意组合。
在一些实施例中，基于所述硅基颗粒的总重量，所述聚合物层或所述无定形碳层的含量为约0.05-15wt％。在一些实施例中，基于所述硅基颗粒的总重量，所述聚合物层或所述无定形碳层的含量为约1-10wt％。在一些实施例中，基于所述硅基颗粒的总重量，所述聚合物层或所述无定形碳层的含量为约2wt％、约3wt％、约4wt％、约5wt％、约6wt％、约7wt％、约8wt％、约9wt％、约10wt％、约11wt％、约12wt％、约13wt％、约14wt％、约14wt％或者这些数值中任意两者组成的范围。
在一些实施例中，所述聚合物层或所述无定形碳层的厚度为约2nm-200nm。在一些实施例中，所述聚合物层或所述无定形碳层的厚度为约10nm-150nm。在一些实施例中，所述 聚合物层或所述无定形碳层的厚度为约50nm-100nm。在一些实施例中，所述聚合物层或所述无定形碳层的厚度为约5nm、约10nm、约20nm、约30nm、约40nm、约50nm、约60nm、约70nm、约80nm、约90nm、约100nm、约110nm、约120nm、约130nm、约140nm、约150nm、约160nm、约170nm、约180nm、约190nm、约200nm或者这些数值中任意两者组成的范围。
在一些实施例中，所述碳纳米管包含单壁碳纳米管、多壁碳纳米管或其组合。
在一些实施例中，所述碳纳米管的直径为约1-30nm。在一些实施例中，所述碳纳米管的直径为约5-20nm。在一些实施例中，所述碳纳米管的直径为约10nm、约15nm、约20nm、约25nm、约30nm或者这些数值中任意两者组成的范围。
在一些实施例中，所述碳纳米管的长径比为约50-30000。在一些实施例中，所述碳纳米管的长径比为约100-20000。在一些实施例中，所述碳纳米管的长径比为约500、约2000、约5000、约10000、约15000、约2000、约25000、约30000或者这些数值中任意两者组成的范围。
在一些实施例中，基于所述硅基颗粒的总重量，所述碳纳米管的含量为约0.01-10wt％。在一些实施例中，基于所述硅基颗粒的总重量，所述碳纳米管的含量为约1-8wt％。在一些实施例中，基于所述硅基颗粒的总重量，所述碳纳米管的含量为约0.02wt％、约0.05wt％、约0.1wt％、约0.5wt％、约1wt％、约1.5wt％、约2wt％、约2wt％、约3wt％、约4wt％、约5wt％、约6wt％、约7wt％、约8wt％、约9wt％、约10wt％或者这些数值中任意两者组成的范围。
在一些实施例中，所述聚合物层中的聚合物或所述无定形碳层中的无定形碳与所述碳纳米管的重量比为约1:5-10:1。在一些实施例中，所述聚合物层中的聚合物或所述无定形碳层中的无定形碳与所述碳纳米管的重量比为约1:5、约1:3、约1:1、约3:1、约5:1、约7:1、约8:1、约10:1或者这些数值中任意两者组成的范围。
在一些实施例中，所述硅基颗粒的比表面积为约2.5-15m 2/g。在一些实施例中，所述硅基颗粒的比表面积为约5-10m 2/g。在一些实施例中，所述硅基颗粒的比表面积为约3m 2/g、约4m 2/g、约6m 2/g、约8m 2/g、约10m 2/g、约12m 2/g、约14m 2/g或者这些数值中任意两者组成的范围。
在一些实施例中，上述任一种负极材料进一步包括石墨颗粒。在一些实施例中，所述石墨颗粒与所述硅基颗粒的重量比为约3:1-20:1。在一些实施例中，所述石墨颗粒与所述硅基 颗粒的重量比为约3:1、约5:1、约6:1、约7:1、约10:1、约12:1、约15:1、约18:1、约20:1或者这些数值中任意两者组成的范围。
二、负极材料的制备方法
本申请实施例提供了一种制备上述任一种负极材料的方法，所述方法包括：
(1)将碳纳米管粉末加入到含有聚合物的溶液中，分散约1-24h得到浆料；
(2)将含硅基体加入到上述浆料中，分散约2-4h得到混合浆料；
(3)去除所述混合浆料中的溶剂；和
(4)破碎和筛分，得到硅基颗粒。
在一些实施例中，所述方法还包括将上述硅基颗粒与石墨颗粒混合的步骤。在一些实施例中，所述石墨颗粒与所述硅基颗粒的重量比为约3:1、约5:1、约6:1、约7:1、约10:1、约12:1、约15:1、约18:1、约20:1或者这些数值中任意两者组成的范围。
在一些实施例中，含硅基体、碳纳米管和聚合物的定义分别如上所述。
在一些实施例中，所述聚合物与所述碳纳米管粉末的重量比为约1:10-10:1。在一些实施例中，所述聚合物与所述碳纳米管粉末的重量比为约1:8、约1:5、约1:3、约1:1、约3:1、约5:1、约7:1、约10:1或者这些数值中任意两者组成的范围。
在一些实施例中，含硅基体与聚合物的重量比为约200:1-5:1。在一些实施例中，含硅基体与聚合物的重量比为约150:1-5:1。在一些实施例中，含硅基体与聚合物的重量比为约200:1、约150:1、约100:1、约50:1、约10:1、约1:1、约5:1或者这些数值中任意两者组成的范围。
在一些实施例中，所述溶剂包含水、乙醇、甲醇、正己烷、N,N-二甲基甲酰胺、吡咯烷酮、丙酮、甲苯、异丙醇或其任意组合。
在一些实施例中，步骤(1)中的分散时间为约1h、约5h、约10h、约15h、约20h、约24h或者这些数值中任意两者组成的范围。
在一些实施例中，步骤(2)中的分散时间为约2h、约2.5h、约3h、约3.5h、约4或者这些数值中任意两者组成的范围。
在一些实施例中，步骤(3)中去除溶剂的方法包括旋转蒸发、喷雾干燥、过滤、冷冻干燥或其任意组合。
在一些实施例中，在步骤(3)和步骤(4)中间还包括烧结步骤。
在一些实施例中，烧结温度为约250-900℃。在一些实施例中，烧结温度为约300-850℃。在一些实施例中，烧结温度为约350-650℃。在一些实施例中，烧结温度为约400℃、约500℃、约600℃或约700℃或者这些数值中任意两者组成的范围。
在一些实施例中，烧结时间为约1-25h。在一些实施例中，烧结时间为约1-19h。在一些实施例中，烧结时间为约1-14h。在一些实施例中，烧结时间为约1h、约1.5h、约2h、约2.5h、约3h、约5h、约8h、约10h、约15h、约20h或者这些数值中任意两者组成的范围。
在一些实施例中，烧结是在惰性气体保护下进行。在一些实施例中，所述惰性气体包括氮气、氩气或其组合。
在一些实施例中，步骤(4)中的筛分为过400目筛分。
图1示出了本申请一个实施例的硅基负极活性材料的结构示意图。其中内层1为含硅基体，外层2为包含碳纳米管的聚合物层。含有碳纳米管(CNT)的聚合物层分布在含硅基体的表面，可以利用聚合物将CNT束缚在硅基负极活性材料表面，有利于提升CNT在负极活性材料表面的界面稳定性，从而提升其循环性能。
硅基负极材料具有1500-4200mAh/g的高克容量，是最具有应用前景的下一代锂离子电池负极材料。但硅在充放电过程中约300％的体积膨胀，以及其表面形成的不稳定的固体电解质界面膜(SEI)，都极大影响了电池性能的发挥。目前提升硅基材料的循环稳定性和倍率性能的方法有：设计多孔硅基材料、降低硅氧材料尺寸、采用聚合物包覆、氧化物包覆及碳包覆等手段。目前普遍使用的包覆包括碳包覆。但是碳包覆层易于在循环过程中破裂，从而使导电性急剧降低，循环性能变差。聚合物包覆能与硅材料表面形成良好的结合，但是其导电性通常较差，因此阻抗较大。碳纳米管(CNT)力学性能高，导电性能较优，因此可以作为硅材料表面的包覆材料。但是高导电的CNT与硅材料表面结合力较弱，且难以分散，因此较难在硅材料表面形成均匀的包覆层。
为了解决上述问题，本申请首先制备了在含硅基体的至少一部分表面上具有聚合物层或无定形碳层的硅基颗粒，并且该聚合物层或无定形碳层中包含碳纳米管(CNT)。CNT的存在提高了负极活性材料的导电性。此外，含有碳纳米管的聚合物层或无定形碳层包覆在硅基负极活性材料的表面，可以利用聚合物或无定形碳将CNT束缚在负极活性材料表面，有利于提升CNT在负极活性材料表面的界面稳定性，同时抑制硅基材料体积膨胀从而提升其循环稳定性。
另一面，本申请发明人意外地发现，由于碳纳米管的制备通常都会采用金属催化剂，如镍基(Ni)、钴基(Co)、铁基(Fe)、钒基(V)、镁基(Mg)、铜基(Cu)、锌基(Zn)化合物等，这些金属元素通常会在制成的碳纳米管上有所残留，因而不可避免地会将其引入到具有碳纳米管与聚合物或无定形碳复合层的硅基负极活性材料上。此外，在硅基体的制备过程中，由于粉碎、分级等工序也会引入金属元素。而这些金属元素的还原电位比锂离子低，在充电过程中，其会优先潜入负极上占据锂离子嵌入的位置，会减小电池的可逆容量。以铁(Fe)元素为例，当负极沉积的Fe逐渐积累，其金属枝晶会刺穿隔膜，发生微短路引起电池自放电。
本申请发明人发现，当硅基负极活性材料中选自Fe、Cu、Zn、Ni、Co或其任意组合的金属元素的含量小于约2500ppm时，由其制备的锂离子电池的K值和阻抗明显低于上述金属元素含量大于约2500ppm的锂离子电池，且首次效率和循环性能明显优于上述金属元素含量大于约2500ppm的锂离子电池。
三、负极
本申请实施例提供了一种负极。所述负极包括集流体和位于该集流体上的负极活性材料层。所述负极活性材料层包括根据本申请实施例的负极材料。
在一些实施例中，负极活性材料层包括粘合剂。在一些实施例中，粘合剂包括，但不限于：聚乙烯醇、羧甲基纤维素、羟丙基纤维素、二乙酰基纤维素、聚氯乙烯、羧化的聚氯乙烯、聚氟乙烯、含亚乙基氧的聚合物、聚乙烯吡咯烷酮、聚氨酯、聚四氟乙烯、聚偏1,1-二氟乙烯、聚乙烯、聚丙烯、丁苯橡胶、丙烯酸(酯)化的丁苯橡胶、环氧树脂或尼龙。
在一些实施例中，负极活性材料层包括导电材料。在一些实施例中，导电材料包括，但不限于：天然石墨、人造石墨、碳黑、乙炔黑、科琴黑、碳纤维、金属粉、金属纤维、铜、镍、铝、银或聚亚苯基衍生物。
在一些实施例中，集流体包括，但不限于：铜箔、镍箔、不锈钢箔、钛箔、泡沫镍、泡沫铜或覆有导电金属的聚合物基底。
在一些实施例中，负极可以通过如下方法获得：在溶剂中将活性材料、导电材料和粘合剂混合，以制备活性材料组合物，并将该活性材料组合物涂覆在集流体上。
在一些实施例中，溶剂可以包括，但不限于：去离子水、N-甲基吡咯烷酮。
四、正极
可用于本申请的实施例中正极的材料、构成和其制造方法包括任何现有技术中公开的技术。在一些实施例中，正极为美国专利申请US9812739B中记载的正极，其以全文引用的方式并入本申请中。
在一些实施例中，正极包括集流体和位于该集流体上的正极活性材料层。
在一些实施例中，正极活性材料包括，但不限于：钴酸锂(LiCoO 2)、锂镍钴锰(NCM)三元材料、磷酸亚铁锂(LiFePO 4)或锰酸锂(LiMn 2O 4)。
在一些实施例中，正极活性材料层还包括粘合剂，并且可选地包括导电材料。粘合剂提高正极活性材料颗粒彼此间的结合，并且还提高正极活性材料与集流体的结合。
在一些实施例中，粘合剂包括，但不限于：聚乙烯醇、羟丙基纤维素、二乙酰基纤维素、聚氯乙烯、羧化的聚氯乙烯、聚氟乙烯、含亚乙基氧的聚合物、聚乙烯吡咯烷酮、聚氨酯、聚四氟乙烯、聚偏1,1-二氟乙烯、聚乙烯、聚丙烯、丁苯橡胶、丙烯酸(酯)化的丁苯橡胶、环氧树脂或尼龙等。
在一些实施例中，导电材料包括，但不限于：基于碳的材料、基于金属的材料、导电聚合物和它们的混合物。在一些实施例中，基于碳的材料选自天然石墨、人造石墨、碳黑、乙炔黑、科琴黑、碳纤维或其任意组合。在一些实施例中，基于金属的材料选自金属粉、金属纤维、铜、镍、铝或银。在一些实施例中，导电聚合物为聚亚苯基衍生物。
在一些实施例中，集流体可以包括，但不限于：铝。
正极可以通过本领域公知的制备方法制备。例如，正极可以通过如下方法获得：在溶剂中将活性材料、导电材料和粘合剂混合，以制备活性材料组合物，并将该活性材料组合物涂覆在集流体上。在一些实施例中，溶剂可以包括，但不限于：N-甲基吡咯烷酮。
五、电解液
可用于本申请实施例的电解液可以为现有技术中已知的电解液。
在一些实施例中，所述电解液包括有机溶剂、锂盐和添加剂。根据本申请的电解液的有机溶剂可为现有技术中已知的任何可作为电解液的溶剂的有机溶剂。根据本申请的电解液中使用的电解质没有限制，其可为现有技术中已知的任何电解质。根据本申请的电解液的添加 剂可为现有技术中已知的任何可作为电解液添加剂的添加剂。
在一些实施例中，所述有机溶剂包括，但不限于：碳酸乙烯酯(EC)、碳酸丙烯酯(PC)、碳酸二乙酯(DEC)、碳酸甲乙酯(EMC)、碳酸二甲酯(DMC)、碳酸亚丙酯或丙酸乙酯。
在一些实施例中，所述锂盐包括有机锂盐或无机锂盐中的至少一种。
在一些实施例中，所述锂盐包括，但不限于：六氟磷酸锂(LiPF 6)、四氟硼酸锂(LiBF 4)、二氟磷酸锂(LiPO 2F 2)、双三氟甲烷磺酰亚胺锂LiN(CF 3SO 2) 2(LiTFSI)、双(氟磺酰)亚胺锂Li(N(SO 2F) 2)(LiFSI)、双草酸硼酸锂LiB(C 2O 4) 2(LiBOB)或二氟草酸硼酸锂LiBF 2(C 2O 4)(LiDFOB)。
在一些实施例中，所述电解液中锂盐的浓度为：约0.5-3mol/L、约0.5-2mol/L或约0.8-1.5mol/L。
六、隔离膜
在一些实施例中，正极与负极之间设有隔离膜以防止短路。可用于本申请的实施例中使用的隔离膜的材料和形状没有特别限制，其可为任何现有技术中公开的技术。在一些实施例中，隔离膜包括由对本申请的电解液稳定的材料形成的聚合物或无机物等。
例如，隔离膜可包括基材层和表面处理层。基材层为具有多孔结构的无纺布、膜或复合膜，基材层的材料选自聚乙烯、聚丙烯、聚对苯二甲酸乙二醇酯和聚酰亚胺中的至少一种。具体的，可选用聚丙烯多孔膜、聚乙烯多孔膜、聚丙烯无纺布、聚乙烯无纺布或聚丙烯-聚乙烯-聚丙烯多孔复合膜。
基材层的至少一个表面上设置有表面处理层，表面处理层可以是聚合物层或无机物层，也可以是混合聚合物与无机物所形成的层。
无机物层包括无机颗粒和粘结剂，无机颗粒选自氧化铝、氧化硅、氧化镁、氧化钛、二氧化铪、氧化锡、二氧化铈、氧化镍、氧化锌、氧化钙、氧化锆、氧化钇、碳化硅、勃姆石、氢氧化铝、氢氧化镁、氢氧化钙和硫酸钡中的一种或几种的组合。粘结剂选自聚偏氟乙烯、偏氟乙烯-六氟丙烯的共聚物、聚酰胺、聚丙烯腈、聚丙烯酸酯、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚甲基丙烯酸甲酯、聚四氟乙烯和聚六氟丙烯中的一种或几种的组合。
聚合物层中包含聚合物，聚合物的材料选自聚酰胺、聚丙烯腈、丙烯酸酯聚合物、聚丙烯酸、聚丙烯酸盐、聚乙烯呲咯烷酮、聚乙烯醚、聚偏氟乙烯或聚(偏氟乙烯-六氟丙烯)中的 至少一种。
七、电化学装置
本申请的实施例提供了一种电化学装置，所述电化学装置包括发生电化学反应的任何装置。
在一些实施例中，本申请的电化学装置包括具有能够吸留、放出金属离子的正极活性物质的正极；根据本申请的实施例的负极；电解液；和置于正极和负极之间的隔离膜。
在一些实施例中，本申请的电化学装置包括，但不限于：所有种类的一次电池、二次电池、燃料电池、太阳能电池或电容。
在一些实施例中，所述电化学装置是锂二次电池。
在一些实施例中，锂二次电池包括，但不限于：锂金属二次电池、锂离子二次电池、锂聚合物二次电池或锂离子聚合物二次电池。
八、电子装置
本申请的电子装置可为任何使用根据本申请的实施例的电化学装置的装置。
在一些实施例中，所述电子装置包括，但不限于：笔记本电脑、笔输入型计算机、移动电脑、电子书播放器、便携式电话、便携式传真机、便携式复印机、便携式打印机、头戴式立体声耳机、录像机、液晶电视、手提式清洁器、便携CD机、迷你光盘、收发机、电子记事本、计算器、存储卡、便携式录音机、收音机、备用电源、电机、汽车、摩托车、助力自行车、自行车、照明器具、玩具、游戏机、钟表、电动工具、闪光灯、照相机、家庭用大型蓄电池或锂离子电容器等。
下面以锂离子电池为例并且结合具体的实施例说明锂离子电池的制备，本领域的技术人员将理解，本申请中描述的制备方法仅是实例，其他任何合适的制备方法均在本申请的范围内。
实施例
以下说明根据本申请的锂离子电池的实施例和对比例进行性能评估。
一、测试方法
粉末性质测试方法
1、比表面积测试：在恒温低温下，测定不同相对压力时的气体在固体表面的吸附量后，基于布朗诺尔-埃特-泰勒吸附理论及其公式(BET公式)求得试样单分子层吸附量，从而计算出固体的比表面积。
称取1.5-3.5g粉末样品装入TriStar II 3020的测试样品管中，200℃脱气120min后进行测试。
3、粉末电子电导率测试：采用四线两端子法，通过测量待测电阻两端电压和流经电流确定电阻，结合待测电阻的高度和底面积计算电导率。取一定量粉末加入到测试模具中，轻轻震平后，再将模具上的垫片放置在样品上；装样完毕后将模具置于电子压力试验机工作台面上，以5mm/min的速率升至500kg(159Mpa)，恒压60s，再卸压至0；当样品恒压至5000±2kg(升压到达5000kg后15～25s)时记录样品压力，并读取样品变形高度，记录此时的电阻测试仪显示数值，即可采用公式计算电子电导率。
4、金属元素含量的测定方法：
粉末：称取各实施例和对比例中的硅基负极活性材料0.2g，置于聚四氟乙烯(PTFE)材质的烧杯中，待数字天平测量值稳定后记录样品重量，精确到0.0001g。向样品中缓慢加入10mL浓HNO 3和2mL HF，置于220℃的平板加热器上，加热消解至几乎蒸干。缓慢加入10mL硝酸，继续加热消解15min，使样品充分溶解。将溶解的样品置于通风橱中，冷却至室温。将样品溶液摇匀，并缓慢倾入具有单层滤纸的漏斗中，并冲洗烧杯与滤渣3次。在20±5℃下定容至50mL，摇匀。利用电感耦合等离子体发射光谱仪(PE 7000)测试滤液的离子光谱强度，并根据标准曲线计算其离子浓度，从而计算样品中所含的元素含量。
负极：将各实施例和对比例得到的负极表面活性物质刮下后，进行2h的600℃热处理，之后称取上述热处理过的活性物质，采用与粉末样相同的测试方法进行金属元素含量的测定。
5、扫描电子显微镜(SEM)测试：扫描电镜表征由PhilipsXL-30型场发射扫描电子显微镜记录，在10kV,10mA条件下进行检测。
6、透射电子显微镜(TEM)测试：采用Jeol JEM2100F进行测试表征。
7、能谱仪(EDS)/Mapping测试方法：EDS测试和Mapping均采用OXFORD-EDS进行表征，电压为20kV。
扣式电池性能测试
在干燥氩气环境下，在碳酸丙烯酯(PC)，碳酸乙烯酯(EC)，碳酸二乙酯(DEC)(重量比1：1：1)混合而成的溶剂中，加入LiPF 6，混合均匀，其中LiPF 6的浓度为1.15mol/L，再加入约7.5wt％的氟代碳酸乙烯酯(FEC)后，混合均匀得到电解液。
将实施例和对比例中得到的硅基负极活性材料、导电乙炔黑与粘结剂PAA(改性聚丙烯酸，PAA)按照重量比80：10：10加入去离子水中，搅拌形成浆料，利用刮刀涂覆形成厚度为100μm的涂层，在真空干燥箱中在85℃烘干12小时，在干燥环境中用冲压机切成直径为1cm的圆片，在手套箱中以金属锂片作为对电极，隔离膜选择ceglard复合膜，加入电解液组装成扣式电池。用蓝电(LAND)系列电池测试对电池进行充放电测试，静置3h后，以0.05C放电至0.005V，再以50μA放电至0.005V；静置5min后，0.1C恒流充电至2V；静置5min后，重复两次上述步骤；测试并得到充放电容量曲线，其中首次效率计算方式为嵌锂截至电压为0.8V的容量/脱锂电压截至到0.005V对应的容量。
全电池性能测试
1、高温循环性能测试：测试温度为45℃，以0.7C恒流充电到4.4V，恒压充电到0.025C，静置5分钟后以0.5C放电到3.0V。以此步得到的容量为初始容量，进行0.7C充电/0.5C放电进行循环测试，以每一步的容量与初始容量做比值，得到容量衰减曲线(容量衰减曲线以循环圈数为X轴，容量保持率为Y轴)。记录45℃循环截至到容量保持率为80％的圈数，从而比较电池的高温循环性能。
2、放电倍率测试：在25℃下，以0.2C放电到3.0V，静置5min，以0.5C充电到4.4V，恒压充电到0.05C后静置5分钟，调整放电倍率，分别以0.2C、0.5C、1C、1.5C、2.0C进行放电测试，分别得到放电容量，以每个倍率下得到的容量与0.2C得到的容量对比，得到比值，通过比较该比值比较倍率性能。
3、直流电阻(DCR)测试：利用Maccor机在25℃测试电池的实际容量(0.7C恒流充电到4.4V，恒压充电到0.025C，静置10分钟，以0.1C放电到3.0V，静置5分钟)通过0.1C放电一定充电状态(state of charge,SOC)下，测试1s放电以5ms进行采点，计算出在不同SOC下的DCR值。
4、K值测试：测试电池测完容量后，将其在室温下静置48h，测量其电压为V1；再将上述电池再静置48h后，测量其电压V2；则K值根据以下公式算出：K＝(V1-V2)/48；单位mV/h。
二、锂离子电池的制备
正极的制备
将LiCoO 2、导电炭黑和聚偏二氟乙烯(PVDF)按照96.7％：1.7％：1.6％的重量比在N-甲基吡咯烷酮溶剂体系中充分搅拌混合均匀，制得正极浆料。将制得的正极浆料涂布在正极集流体铝箔上，烘干，冷压，得到正极。
负极的制备
将石墨与实施例中的硅基负极活性材料按照89：11的重量比混合，得到克容量为500mAh/g的混合负极活性材料，将混合负极活性材料、导电剂乙炔黑、PAA按照重量比95：1.2：3.8在去离子中充分搅拌，混合均匀后，涂覆于Cu箔上烘干、冷压，得到负极极片。
电解液的制备
在干燥氩气环境下，在碳酸丙烯酯(PC)、碳酸乙烯酯(EC)、碳酸二乙酯(DEC)(重量比1：1：1)混合而成的溶剂中，加入LiPF 6混合均匀，其中LiPF 6的浓度为1mol/L，再加入10wt％的氟代碳酸乙烯酯(FEC)后混合均匀得到电解液。
隔离膜的制备
以PE多孔聚合薄膜作为隔离膜。
锂离子电池的制备
将正极、隔离膜、负极按顺序叠好，使隔离膜处于正极和负极中间以起到隔离的作用，卷绕得到电芯。将电芯置于外包装中，注入电解液，封装。经过化成、脱气、切边等工艺流程得到锂离子电池。
三、硅基负极活性材料的制备
1、通过以下方法制备实施例1-9和对比例1-6中的硅基负极活性材料：
(1)将碳纳米管和聚合物在水中高速分散约12h得到均匀混合的浆料；
(2)将SiO(Dv50为3μm)加入步骤(1)中混合均匀的浆料中，搅拌约4小时后得到均匀混合的分散液；
(3)喷雾干燥(进口温度200℃，出口温度110℃)所述分散液得到粉末；和
(4)冷却后取出粉末样品，破碎、400目过筛得到硅基颗粒，作为硅基负极活性材 料。
2、通过以下方法制备实施例10-12和对比例7中的硅基负极活性材料：
实施例10-12和对比例7与实施例1-9和对比例1-6中的硅基负极活性材料的制备方法相似，区别在于实施例10-12和对比例7在喷雾干燥后，还包括烧结步骤，烧结条件为在氮气保护条件下，以3℃/min升温至600℃，保温2h。
表1示出了实施例1-12和对比例1-7中的硅基负极活性材料制备方法中使用的各物质种类和加入量。
表1
序号 含硅基体 CNT加入量 聚合物种类和加入量
实施例1 SiO/100g 0.5g 3g聚酰亚胺
实施例2 SiO/100g 0.5g 3g聚酰亚胺
实施例3 SiO/100g 0.5g 3g聚酰亚胺
实施例4 SiO/100g 1g 3g羧甲基纤维素
实施例5 SiO/100g 1g 3g羧甲基纤维素
实施例6 SiO/100g 1g 3g羧甲基纤维素
实施例7 SiO/100g 5g 10g羧甲基纤维素
实施例8 SiO/100g 5g 10g羧甲基纤维素
实施例9 SiO/100g 5g 10g羧甲基纤维素
实施例10 SiO/100g 1g 3g羧甲基纤维素
实施例11 SiO/100g 1g 3g羧甲基纤维素
实施例12 SiO/100g 1g 3g羧甲基纤维素
对比例1 SiO/100g 0.5g 3g聚酰亚胺
对比例2 SiO/100g 1g 3g羧甲基纤维素
对比例3 SiO/100g 5g 10g羧甲基纤维素
对比例4 SiO/100g 0.5g -
对比例5 SiO/100g 1g -
对比例6 SiO/100g 5g -
对比例7 SiO/100g 1g 3g羧甲基纤维素
“-”表示制备过程中未加入此物质。
表2示出了实施例1-12和对比例1-7中硅基负极活性材料中的金属元素种类和含量，上述含量均是基于硅基负极活性材料的总重量计算得到的。
表2
Figure PCTCN2019128837-appb-000001
Figure PCTCN2019128837-appb-000002
表3示出了实施例1-12和对比例1-7中的硅基负极活性材料的相关性能参数。
表3
Figure PCTCN2019128837-appb-000003
Figure PCTCN2019128837-appb-000004
*首次效率计算方式为嵌锂截至电压为0.8V的容量/脱锂电压截至到0.005V对应的容量
由实施例1-12和对比例1-7的测试结果可以看出，在硅基负极活性材料表面具有聚合物或无定形碳与CNT复合层的情况下，当硅基负极活性材料中选自Fe、Cu、Zn、Ni、Co或其任意组合的金属元素的含量小于约2500ppm时，由其制备的锂离子电池的K值和阻抗明显低于上述金属元素含量大于约2500ppm的锂离子电池，且首次效率和循环性能明显优于上述金属元素含量大于约2500ppm的锂离子电池。
图2示出了本申请实施例4中硅基负极活性材料表面的SEM图片，其中虚线框内主要为含有CNT的聚合物层；且图3示出了本申请实施例4中硅基负极活性材料Fe元素的Mapping图谱。
图2-3说明实施例4的表面形貌和表面分布的Fe元素的Mapping图谱。
整个说明书中对“一些实施例”、“部分实施例”、“一个实施例”、“另一举例”、“举例”、“具体举例”或“部分举例”的引用，其所代表的意思是在本申请中的至少一个实施例或举例包含了该实施例或举例中所描述的特定特征、结构、材料或特性。因此，在整个说明书中的各处所出现的描述，例如：“在一些实施例中”、“在实施例中”、“在一个实施例中”、“在另一个举例中”，“在一个举例中”、“在特定举例中”或“举例“，其不必然是引用本申请中的相同的实施例或示例。此外，本文中的特定特征、结构、材料或特性可以以任何合适的方式在一个或多个实施例或举例中结合。
尽管已经演示和描述了说明性实施例，本领域技术人员应该理解上述实施例不能被解释为对本申请的限制，并且可以在不脱离本申请的精神、原理及范围的情况下对实施例进行改变，替代和修改。

Claims (10)

  1. 一种负极材料，其包括硅基颗粒，所述硅基颗粒包括含硅基体，所述含硅基体的至少一部分表面具有：
    (i)聚合物层，和/或
    (ii)无定形碳层，
    并且所述聚合物层或无定形碳层包含碳纳米管，
    所述硅基颗粒包含金属元素，所述金属元素包含Fe、Cu、Zn、Ni、Co或其任意组合；其中基于所述硅基颗粒的总重量，选自Fe、Cu、Zn、Ni、Co或其任意组合的金属元素的含量小于约2500ppm。
  2. 根据权利要求1所述的负极材料，其中所述含硅基体包括SiO x，且0.6≤x≤1.5。
  3. 根据权利要求1所述的负极材料，其中所述含硅基体包括Si、SiO、SiO 2、SiC或其任意组合。
  4. 根据权利要求3所述的负极材料，其中所述Si的颗粒尺寸为小于约100nm。
  5. 根据权利要求1所述的负极材料，其中所述聚合物层包含以下聚合物：羧甲基纤维素、聚丙烯酸、聚丙烯腈、聚乙烯醇、聚乙烯基吡咯烷酮、聚苯胺、聚酰亚胺、聚酰胺酰亚胺、聚硅氧烷、聚丁苯橡胶、环氧树脂、聚酯树脂、聚氨酯树脂、聚芴或其任意组合；其中所述无定形碳层中的无定形碳为所述聚合物经烧结后得到。
  6. 根据权利要求1所述的负极材料，其中基于所述硅基颗粒的总重量，所述聚合物层或所述无定形碳层的含量为约0.05-15wt％；所述碳纳米管的含量为约0.01-10wt％；和/或所述聚合物层中的聚合物或所述无定形碳层中的无定形碳与所述碳纳米管的重量比为约1:5-10:1。
  7. 根据权利要求1所述的负极材料，其中所述聚合物层或所述无定形碳层的厚度为约2-200nm；所述硅基颗粒的平均粒径为约500nm-30μm；和/或所述硅基颗粒的比表面积为约0.5-50m 2/g。
  8. 一种负极，其包含如权利要求1-7中任一项所述的负极材料。
  9. 一种电化学装置，其包含如权利要求8所述的负极。
  10. 一种电子装置，其包含如权利要求9所述的电化学装置。
PCT/CN2019/128837 2019-12-26 2019-12-26 负极材料及包含其的电化学装置和电子装置 WO2021128200A1 (zh)

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