WO2021120927A1 - 一种补锂材料及其制备方法、负极和锂离子电池 - Google Patents

一种补锂材料及其制备方法、负极和锂离子电池 Download PDF

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WO2021120927A1
WO2021120927A1 PCT/CN2020/128047 CN2020128047W WO2021120927A1 WO 2021120927 A1 WO2021120927 A1 WO 2021120927A1 CN 2020128047 W CN2020128047 W CN 2020128047W WO 2021120927 A1 WO2021120927 A1 WO 2021120927A1
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lithium
particles
dispersion liquid
carbon nanotubes
conductive material
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PCT/CN2020/128047
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English (en)
French (fr)
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梅日国
常晓雅
吴子文
潘仪
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比亚迪股份有限公司
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Priority to US17/785,871 priority Critical patent/US20230023215A1/en
Priority to EP20900881.2A priority patent/EP4080616A4/en
Priority to KR1020227023985A priority patent/KR20220114603A/ko
Priority to JP2022536819A priority patent/JP7425875B2/ja
Publication of WO2021120927A1 publication Critical patent/WO2021120927A1/zh

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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
    • 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
    • H01M4/36—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
    • H01M4/381—Alkaline or alkaline earth metals elements
    • H01M4/382—Lithium
    • 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
    • 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
    • H01M10/058—Construction or manufacture
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/44—Methods for charging or discharging
    • H01M10/446—Initial charging measures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0402—Methods of deposition of the material
    • H01M4/0404—Methods of deposition of the material by coating on electrode collectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0438—Processes of manufacture in general by electrochemical processing
    • H01M4/044—Activating, forming or electrochemical attack of the supporting material
    • H01M4/0445—Forming after manufacture of the electrode, e.g. first charge, cycling
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/04—Processes of manufacture in general
    • H01M4/0438—Processes of manufacture in general by electrochemical processing
    • H01M4/0459—Electrochemical doping, intercalation, occlusion or alloying
    • 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
    • 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
    • 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
    • H01M4/628—Inhibitors, e.g. gassing inhibitors, corrosion inhibitors
    • 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

  • the present disclosure relates to the field of lithium ion batteries, and in particular, to a lithium supplement material and a preparation method thereof, a negative electrode, and a lithium ion battery.
  • Lithium-ion batteries have the advantages of high specific energy and long cycle life, and have been widely used in various portable electronic devices such as notebook computers and mobile phones. With the increasing severity of energy and environmental issues, countries are increasingly demanding energy conservation and emission reduction. Traditional fuel vehicles not only consume oil, which has limited reserves of fossil energy, but also have serious exhaust pollution. Therefore, electric vehicles came into being. As the main energy storage unit of electric vehicles, lithium-ion power batteries have received more and more attention and have shown good development prospects. With the continuous improvement of people's requirements for cruising range and driving experience, it is particularly important to increase the energy density of power batteries, which can be achieved by optimizing the battery structure, using higher capacity electrode materials, and expanding the operating voltage of the battery.
  • the organic electrolyte is reduced and decomposed on the surface of the negative electrode such as graphite to form a solid electrolyte phase interface (SEI) film, which permanently consumes the lithium ions extracted from the positive electrode, causing irreversible capacity loss and reducing the initial charge.
  • SEI solid electrolyte phase interface
  • the theoretical specific capacity of traditional graphite anode material is 372mAh/g, and the first irreversible capacity loss is 5%-10%.
  • high-capacity anode materials, such as silicon and alloys the first irreversible capacity is higher.
  • prelithiation technology is used to offset the lithium ions consumed when the material is formed when the SEI film is formed to increase the total capacity of the battery.
  • the current prelithiation technology can be roughly divided into negative electrode lithium supplement, positive electrode lithium supplement, separator lithium supplement, and electrolyte lithium supplement.
  • Common negative electrode lithium supplements include lithium foil supplementation and lithium powder supplementation.
  • the potential of metallic lithium is the lowest among all electrode materials. Due to the existence of the potential difference, when the negative electrode material contacts the metallic lithium foil or lithium powder, electrons will spontaneously move to the negative electrode, allowing lithium ions to be inserted into the negative electrode.
  • the lithium supplementation material is pressed or coated on the surface of the negative electrode material, when the lithium metal and graphite are not in contact or the lithium supplementation layer closest to the negative electrode material is consumed, dead lithium is easily formed, which greatly reduces the efficiency of lithium supplementation, and may also form branches. Crystal, causing safety hazards.
  • the purpose of the present disclosure is to provide a lithium supplement material which has high lithium supplement efficiency and avoids the formation of dead lithium to cause dendrites.
  • the present disclosure provides a lithium supplement material
  • the lithium supplement material includes metallic lithium particles and a conductive material
  • the conductive material includes a built-in section embedded in the metallic lithium particles and located outside the metallic lithium particles The exposed section; the electronic conductivity of the conductive material is greater than 100s/cm.
  • the conductive material is a carbon material; the carbon material is selected from at least one of carbon nanotubes, carbon fibers, and graphene;
  • the carbon material is carbon nanotubes; the carbon nanotubes are single-walled carbon nanotubes and/or multi-walled carbon nanotubes, preferably multi-walled carbon nanotubes; and/or, the carbon nanotubes are
  • the tube diameter is 5nm-100nm, preferably 10nm-30nm, and the length is 10 ⁇ m-80 ⁇ m, preferably 30 ⁇ m-50 ⁇ m.
  • the content of the conductive material is 0.1-3 parts by weight, preferably 0.5-1 parts by weight.
  • the average particle size of the metallic lithium particles is 20 ⁇ m-40 ⁇ m; and/or,
  • the surface of the metal lithium particles has a passivation layer; the thickness of the passivation layer is 5 nm-100 nm; the passivation layer contains at least one of lithium carbonate, lithium fluoride, and paraffin wax.
  • a second aspect of the present disclosure provides a method for preparing a lithium supplement material, the method comprising:
  • the conductive material is a carbon material; the carbon material is selected from at least one of carbon nanotubes, carbon fibers, and graphene; preferably, the carbon material is single-walled carbon nanotubes and / Or multi-walled carbon nanotubes, preferably multi-walled carbon nanotubes; the diameter of the carbon nanotubes is 5nm-100nm, preferably 10nm-30nm, the length is 10 ⁇ m-80 ⁇ m, preferably 30 ⁇ m-50 ⁇ m; and/or ,
  • the first dispersion liquid also contains a surfactant;
  • the surfactant is selected from at least one of polyvinylpyrrolidone, sodium dodecylbenzene sulfonate and cetyltrimethylamine bromide, preferably Polyvinylpyrrolidone; the weight ratio of the metal lithium and the surfactant is 1: (0.002-0.05), preferably 1: (0.005-0.02); and/or,
  • the dispersion medium of the first dispersion liquid and the second dispersion liquid is an inert organic solvent, and the dispersion medium of the first dispersion liquid and the second dispersion liquid are each independently selected from the group consisting of hydrocarbons, esters, ethers, and silicone oils. At least one; and/or,
  • the volume ratio of the first dispersion to the second dispersion is 1: (0.1-10), preferably 1: (0.5-3); the weight ratio of the metallic lithium to the conductive material is 100: (0.1-3), preferably 100: (0.5-1).
  • the method further includes: in step S1, carbon dioxide is introduced after the first dispersion liquid and the second dispersion liquid are uniformly mixed.
  • the third aspect of the present disclosure provides a lithium supplement material prepared by the method provided in the second aspect of the present disclosure.
  • a fourth aspect of the present disclosure provides a lithium ion battery negative electrode, which includes a current collector, a negative electrode active material, and a lithium supplement material.
  • the lithium supplement material is described in any one of the first aspect of the present disclosure and the third aspect of the present disclosure. Lithium supplement material.
  • a fifth aspect of the present disclosure provides a lithium ion battery, which includes the lithium ion battery negative electrode provided in the fourth aspect of the present disclosure.
  • the lithium supplement material of the present disclosure can realize the electronic conduction between the lithium metal particles and the negative electrode active material through the conductive material, increase the electronic conduction channel, and at the same time facilitate the transmission of lithium ions, and realize the rapid insertion process of lithium ions.
  • the efficiency of replenishing lithium is significantly improved, thereby effectively inhibiting the formation of dead lithium and avoiding the formation of dendrites piercing the diaphragm and causing safety hazards.
  • FIG. 1 is a schematic diagram of the principle of lithium supplementation when the lithium supplement material of the present disclosure is applied to the negative electrode of a lithium ion battery.
  • a first aspect of the present disclosure provides a lithium supplement material.
  • the lithium supplement material includes metallic lithium particles and a conductive material.
  • the conductive material includes a built-in section embedded in the metallic lithium particles and an exposed portion outside the metallic lithium particles. Section;
  • the electronic conductivity of the conductive material is greater than 100s/cm.
  • the conductive material may be a one-dimensional material and/or a two-dimensional material with an electronic conductivity greater than 100 s/cm.
  • the conductive material includes a built-in section buried in the metal lithium particles and an exposed section located outside the metal lithium particles.
  • the conductive material may be inserted into the metal lithium particles.
  • the conductive material has a longer length. When it is larger than the particle size of the metal lithium particles, the conductive material may penetrate one or even several of the metal lithium particles.
  • the conductive material includes a plurality of built-in segments embedded in the metal lithium particles and a plurality of exposed segments located outside the metal lithium particles, and the conductive material can be bent; in another embodiment, The length of the conductive material is relatively short.
  • the conductive material may only partially embed the lithium metal particles.
  • the conductive material only includes one embedded in the lithium metal particles.
  • the inventors of the present disclosure have discovered that when a portion of the conductive material in the lithium supplement material is embedded with metal lithium particles, the lithium supplement material is rolled with the negative electrode sheet without lithium supplement, and the conductive material can be tightly connected with the negative electrode active material.
  • Forming a vertical three-dimensional conductive network not only can realize the electronic conduction between the lithium metal particles and the solid-phase interface of the negative electrode material, but also can realize the electronic conduction between the metal lithium particles and the negative electrode active material through the conductive material, increasing the electron conduction channel, and at the same time It helps the transmission of lithium ions, realizes the rapid insertion process of lithium ions, and significantly improves the efficiency of lithium supplementation, thereby effectively inhibiting the formation of dead lithium, and avoiding the formation of dendrites that pierce the diaphragm and cause safety hazards.
  • the conductive material may be a carbon material known in the art.
  • the carbon material may be selected from at least one of carbon nanotubes, carbon fibers, and graphene.
  • the carbon material may be carbon nanotubes.
  • the carbon nanotubes have a one-dimensional tubular structure through which electrons can conduct high-speed conduction and therefore have excellent electronic conductivity.
  • the metal lithium particles are relatively large in size and have a diameter of several tens of micrometers. , The bending and winding shape of carbon nanotubes is more conducive to interspersing to form a conductive network.
  • the carbon nanotubes are known in the art.
  • the carbon nanotubes are at least one of single-walled carbon nanotubes and/or multi-walled carbon nanotubes.
  • the carbon nanotubes may be multi-walled carbon nanotubes.
  • the diameter of the carbon nanotubes may be 5nm-100nm, preferably 10nm-30nm, and the length may be 10 ⁇ m-80 ⁇ m, preferably 30 ⁇ m-50 ⁇ m.
  • the content of the conductive material can be changed within a certain range.
  • a conductive network of an appropriate proportion is provided.
  • the content may be 0.1-3 parts by weight.
  • the content of the conductive material may be 0.5-1 parts by weight.
  • the average particle size of the metal lithium particles can be varied within a relatively large range, and preferably, the average particle size can be 20 ⁇ m-40 ⁇ m.
  • the average particle size of the metal lithium particles can be observed by scanning electron microscope to measure the particle size of any 100 metal lithium particles randomly, and the average particle size is the average particle size of the metal lithium particles.
  • the metallic lithium particles in order to effectively prevent the internal metallic lithium from further reacting in contact with oxygen, carbon dioxide and moisture in the air, the metallic lithium particles also have a passivation layer on the surface; the passivation layer may be chemically stable At least one of the lithium carbonate layer, the lithium fluoride layer and the paraffin wax layer, the thickness of the passivation layer can vary in a relatively large range, for example, the thickness of the passivation layer can be 5-100nm, preferably In an embodiment, the thickness of the passivation layer may be 10-30 nm.
  • a second aspect of the present disclosure provides a method for replenishing lithium materials, which specifically includes:
  • the conductive material may be a carbon material known in the art.
  • the carbon material may be selected from at least one of carbon nanotubes, carbon fibers, and graphene.
  • the carbon material may be carbon nanotubes.
  • the carbon nanotubes have a one-dimensional tubular structure through which electrons can conduct high-speed conduction. Therefore, they have excellent electronic conductivity.
  • the metal lithium particles have a relatively large volume and a diameter of several The ten micron level, therefore, the bending and winding shape of carbon nanotubes is more conducive to interspersing to form a conductive network.
  • the carbon nanotubes are known in the art.
  • the carbon nanotubes may be at least one of single-walled carbon nanotubes and/or multi-walled carbon nanotubes.
  • the carbon nanotubes may be multi-walled carbon nanotubes.
  • the diameter of the carbon nanotubes may be 5nm-100nm, preferably 10nm-30nm, and the length may be 10 ⁇ m-80 ⁇ m, preferably 30 ⁇ m-50 ⁇ m.
  • the first dispersion liquid may also contain a surfactant, which is known in the art, for example, the surfactant may be selected from polyvinylpyrrolidone, dodecyl One or more of sodium benzene sulfonate and cetyltrimethyl amine bromide.
  • the surfactant may be polyvinylpyrrolidone.
  • the weight ratio of the metal lithium and the surfactant can be changed within a certain range. For example, the weight ratio of the metal lithium and the surfactant can be 1:(0.002-0.05), preferably 1:( 0.005-0.02).
  • the dispersion medium of the first dispersion liquid and the second dispersion liquid are inert organic solvents commonly used in the art, and the dispersion medium of the first dispersion liquid and the second dispersion liquid can be independently selected from each other.
  • At least one of hydrocarbons, esters, ethers, and silicone oils can be selected from at least one of hydrocarbon oils, white oils and silicone oils commonly used in the art.
  • the dispersion medium of the first dispersion liquid and the second dispersion liquid may be silicone oil, such as common methyl silicone oil, ethyl silicone oil, and methyl ethoxy silicone oil. Go into details.
  • the volume ratio of the first dispersion liquid and the second dispersion liquid may be varied within a relatively large range, for example, the volume ratio of the first dispersion liquid and the second dispersion liquid may be 1: (0.1-10), preferably 1: (0.5-3).
  • the weight ratio of the metal lithium to the conductive material can be varied within a relatively large range.
  • the weight ratio of the metal lithium to the conductive material can be 100: (0.1-3), preferably 100: (0.5). -1).
  • the method may further include the step of introducing carbon dioxide to form a passivation layer.
  • a passivation layer For example, in step S1, after the first dispersion liquid and the second dispersion liquid are mixed, an inert gas containing carbon dioxide is introduced.
  • the gas may be high-purity carbon dioxide.
  • the third aspect of the present disclosure provides a lithium supplement material prepared by the method provided in the second aspect of the present disclosure.
  • a fourth aspect of the present disclosure provides a lithium ion battery negative electrode, which includes a current collector, a negative active material, and a lithium supplement material.
  • the lithium supplement material is the supplement provided in the first aspect of the present disclosure and/or the third aspect of the present disclosure. Lithium material.
  • the anode current collector may be a conventional anode current collector in a lithium ion battery, such as stamped metal, metal foil, mesh metal, and foam metal.
  • the negative active material may also include a binder, the type of which may be conventional in the art, and will not be repeated here.
  • the method for preparing the negative electrode of the lithium ion battery of the present disclosure has no special requirements and can be carried out with reference to the prior art.
  • the method for preparing the negative electrode of the lithium ion battery of the present disclosure may include: coating a negative electrode slurry containing a negative electrode active material and a binder. Coated and/or filled on the negative electrode current collector, and then dried and rolled.
  • the specific operation methods and conditions can be conventional in the field, and there are no special restrictions here.
  • Figure 1 is a schematic diagram of the principle of lithium supplementation when the lithium supplement material of the present disclosure is applied to the negative electrode of a lithium ion battery.
  • the conductive material 2 such as carbon nanotubes
  • the conductive material 2 can be wound through the metal Lithium particles 1, after rolling, the bent and wound conductive material 2 can be closely connected with the negative electrode active material 3 to form a vertical three-dimensional conductive network, which can not only realize the particle conduction of the solid phase interface between the metal lithium particles 1 and the negative electrode active material 3
  • the metal lithium particles 1 that are not in contact with the negative electrode active material 3 can also transfer the particles to the negative electrode active material 3 through the conductive material 2, and the metal lithium particles 1 can realize the electronic conduction process with the negative electrode active material 3 through the conductive material 2. It helps the transmission of lithium ions and realizes the rapid insertion process of lithium ions, thereby effectively inhibiting the formation of dead lithium, significantly improving the efficiency of replenishing lithium, and avoiding the formation of dendrites which may cause
  • a fifth aspect of the present disclosure provides a lithium ion battery, which includes the lithium ion battery negative electrode provided in the fourth aspect of the present disclosure.
  • a lithium ion battery may also include a positive electrode, a separator, and an electrolyte.
  • the present disclosure has no special restrictions on the positive electrode, separator, and electrolyte, and may be conventional types in the field.
  • the lithium ion battery may also use conventional methods in the field.
  • the positive electrode and the negative electrode of the present disclosure are wound and separated by a separator to form an electrode group, and the obtained electrode group and electrolyte are sealed in a battery case to obtain the lithium ion battery provided by the present disclosure.
  • the winding method of the separator between the positive electrode and the negative electrode is well known to those skilled in the art, and will not be repeated here.
  • Multi-walled carbon nanotubes purchased from Jiangsu Tiannai Technology Co., Ltd., have an electronic conductivity of >150s/cm.
  • Single-walled carbon nanotubes purchased from Jiangsu Tiannai Technology Co., Ltd., have an electronic conductivity> 150s/cm.
  • Carbon fiber purchased from Jiangsu Tiannai Technology Co., Ltd., has an electronic conductivity of >100s/cm.
  • Graphene purchased from Jiangsu Tiannai Technology Co., Ltd., has an electronic conductivity> 100s/cm.
  • a dispersion liquid take 0.05g of multi-walled carbon nanotubes with a diameter of 10nm and a length of 50 ⁇ m, add 25g of silicone oil, and stir at 200°C until the multi-walled carbon nanotubes are fully dispersed to obtain a second dispersion;
  • the second dispersion liquid is slowly added to the first dispersion liquid and mixed uniformly, carbon dioxide gas is introduced, stirring and heating are stopped, and the solid product is collected and dried after cooling to room temperature to obtain the lithium supplement material A1.
  • the lithium supplement material A1 of Example 1 includes metallic lithium particles, multi-walled carbon nanotubes, and a passivation layer (specifically a lithium carbonate layer).
  • the multi-walled carbon nanotubes are partially embedded in the metallic lithium particles, and the multi-walled carbon nanotubes can be It includes a built-in section buried in the lithium metal particles and an exposed section located outside the lithium metal particles; the lithium carbonate layer is located on the surface of the lithium metal particles. It was found that the average particle size of the metal lithium particles was 27.8 ⁇ m, and the thickness of the lithium carbonate layer was 21 nm.
  • the ingot is completely dissolved to obtain the first dispersion; take 0.05 g of multi-walled carbon nanotubes with a diameter of 10 nm and a length of 50 ⁇ m, add 25 g of silicone oil, and stir at 200°C until the multi-walled carbon nanotubes are fully dispersed to obtain a second dispersion; Under stirring conditions, the second dispersion is slowly added to the first dispersion and mixed uniformly, carbon dioxide gas is introduced, stirring and heating are stopped, and the solid product is collected and dried after cooling to room temperature to obtain lithium supplement material A2.
  • the lithium supplement material A2 of Example 2 includes metallic lithium particles, multi-walled carbon nanotubes, and a passivation layer (specifically a lithium carbonate layer).
  • the multi-walled carbon nanotubes include built-in sections embedded in metallic lithium particles and located in metallic lithium particles. The exposed section outside the particles; the lithium carbonate layer is located on the surface of the lithium metal particles. The test found that the average particle size of the lithium metal particles was 42.2 ⁇ m, and the thickness of the lithium carbonate layer was 27 nm.
  • the lithium supplement material A3 of Example 3 includes metallic lithium particles, multi-walled carbon nanotubes, and a passivation layer (specifically a lithium carbonate layer).
  • the multi-walled carbon nanotubes include built-in sections embedded in metallic lithium particles and located in metallic lithium particles. The exposed section outside the particles; the lithium carbonate layer is located on the surface of the lithium metal particles. It was found that the average particle size of the metal lithium particles was 45.4 ⁇ m, and the thickness of the lithium carbonate layer was 35 nm.
  • a dispersion liquid take 0.05g of multi-walled carbon nanotubes with a diameter of 20nm and a length of 30 ⁇ m, add 25g of silicone oil, and stir at 200°C until the multi-walled carbon nanotubes are fully dispersed to obtain a second dispersion;
  • the second dispersion liquid is slowly added to the first dispersion liquid and mixed uniformly, carbon dioxide gas is introduced, stirring and heating are stopped, and the solid product is collected and dried after cooling to room temperature to obtain lithium supplement material A4.
  • the lithium supplement material A4 of Example 4 includes metallic lithium particles, multi-walled carbon nanotubes and a passivation layer (specifically a lithium carbonate layer).
  • the multi-walled carbon nanotubes include built-in sections embedded in metallic lithium particles and located in metallic lithium particles. The exposed section outside the particles; the lithium carbonate layer is located on the surface of the lithium metal particles. It was found that the average particle size of the metal lithium particles was 26.2 ⁇ m, and the thickness of the lithium carbonate layer was 27 nm.
  • a dispersion liquid Take 0.05g of multi-walled carbon nanotubes with a diameter of 40nm and a length of 20 ⁇ m, add 25g of silicone oil, and stir at 200°C until the multi-walled carbon nanotubes are fully dispersed to obtain a second dispersion; The second dispersion liquid is slowly added to the first dispersion liquid and mixed uniformly, carbon dioxide gas is introduced, stirring and heating are stopped, and the solid product is collected and dried after cooling to room temperature to obtain lithium supplement material A5.
  • the lithium supplement material A5 of Example 5 includes metallic lithium particles, multi-walled carbon nanotubes, and a passivation layer (specifically a lithium carbonate layer).
  • the multi-walled carbon nanotubes include built-in sections embedded in metallic lithium particles and located in metallic lithium particles. The exposed section outside the particles; the lithium carbonate layer is located on the surface of the lithium metal particles. It was found that the average particle size of the metal lithium particles was 29.2 ⁇ m, and the thickness of the lithium carbonate layer was 20 nm.
  • a dispersion liquid take 0.05g of multi-walled carbon nanotubes with a tube diameter of 60nm and a length of 20 ⁇ m, add 25g of silicone oil, and stir at 200°C until the multi-walled carbon nanotubes are fully dispersed to obtain a second dispersion;
  • the second dispersion liquid is slowly added to the first dispersion liquid and mixed uniformly, carbon dioxide gas is introduced, stirring and heating are stopped, and the solid product is collected and dried after cooling to room temperature to obtain lithium supplement material A6.
  • the lithium supplement material A6 of Example 6 includes metallic lithium particles, multi-walled carbon nanotubes, and a passivation layer (specifically, a lithium carbonate layer).
  • the multi-walled carbon nanotubes include built-in sections embedded in metallic lithium particles and located in metallic lithium particles. The exposed section outside the particles; the lithium carbonate layer is located on the surface of the lithium metal particles. It was found that the average particle size of the metallic lithium particles was 39.6 ⁇ m, and the thickness of the lithium carbonate layer was 23 nm.
  • a dispersion liquid Take 0.08g of multi-walled carbon nanotubes with a diameter of 20nm and a length of 30 ⁇ m, add 25g of silicone oil, and stir at 200°C until the multi-walled carbon nanotubes are fully dispersed to obtain a second dispersion; The second dispersion liquid is slowly added to the first dispersion liquid and mixed uniformly, carbon dioxide gas is introduced, stirring and heating are stopped, and the solid product is collected and dried after cooling to room temperature to obtain lithium supplement material A7.
  • the lithium supplement material A7 of Example 7 includes metallic lithium particles, multi-walled carbon nanotubes, and a passivation layer (specifically a lithium carbonate layer).
  • the multi-walled carbon nanotubes include built-in sections embedded in metallic lithium particles and located in metallic lithium particles. The exposed section outside the particles; the lithium carbonate layer is located on the surface of the lithium metal particles. The test found that the average particle size of the metal lithium particles was 25.0 ⁇ m, and the thickness of the lithium carbonate layer was 22 nm.
  • a dispersion liquid take 0.1 g of multi-walled carbon nanotubes with a diameter of 20 nm and a length of 30 ⁇ m, add 25 g of silicone oil, and stir at 200 °C until the multi-walled carbon nanotubes are fully dispersed to obtain a second dispersion;
  • the second dispersion liquid is slowly added to the first dispersion liquid and mixed uniformly, carbon dioxide gas is introduced, stirring and heating are stopped, and the solid product is collected and dried after cooling to room temperature to obtain lithium supplement material A8.
  • the lithium supplement material A8 of Example 8 includes metallic lithium particles, multi-walled carbon nanotubes, and a passivation layer (specifically a lithium carbonate layer).
  • the multi-walled carbon nanotubes include built-in sections embedded in metallic lithium particles and located in metallic lithium particles. The exposed section outside the particles; the lithium carbonate layer is located on the surface of the lithium metal particles. It was found that the average particle size of the metal lithium particles was 26.4 ⁇ m, and the thickness of the lithium carbonate layer was 26 nm.
  • a dispersion liquid take 0.2 g of multi-walled carbon nanotubes with a diameter of 20 nm and a length of 30 ⁇ m, add 25 g of silicone oil, and stir at 200 °C until the multi-walled carbon nanotubes are fully dispersed to obtain a second dispersion;
  • the second dispersion liquid is slowly added to the first dispersion liquid and mixed uniformly, carbon dioxide gas is introduced, stirring and heating are stopped, and the solid product is collected and dried after cooling to room temperature to obtain lithium supplement material A9.
  • the lithium supplement material A9 of Example 9 includes metallic lithium particles, multi-walled carbon nanotubes, and a passivation layer (specifically a lithium carbonate layer).
  • the multi-walled carbon nanotubes include built-in sections embedded in metallic lithium particles and located in metallic lithium particles. The exposed section outside the particles; the lithium carbonate layer is located on the surface of the lithium metal particles. It was found that the average particle size of the metal lithium particles was 27.6 ⁇ m, and the thickness of the lithium carbonate layer was 22 nm.
  • a dispersion solution Take 0.05g of single-walled carbon nanotubes with a diameter of 2nm and a length of 30 ⁇ m, add 25g of silicone oil, and stir at 200°C until the single-walled carbon nanotubes are fully dispersed to obtain a second dispersion; under high-speed stirring conditions, The second dispersion liquid is slowly added to the first dispersion liquid and mixed uniformly, carbon dioxide gas is introduced, stirring and heating are stopped, and the solid product is collected and dried after cooling to room temperature to obtain lithium supplement material A10.
  • the lithium supplement material A10 of Example 10 includes metallic lithium particles, single-walled carbon nanotubes, and a passivation layer (specifically, a lithium carbonate layer).
  • the single-walled carbon nanotubes include built-in sections embedded in metallic lithium particles and located in the metallic lithium particles. The exposed section outside the particles; the lithium carbonate layer is located on the surface of the lithium metal particles. It was found that the average particle size of the metal lithium particles was 28.2 ⁇ m, and the thickness of the lithium carbonate layer was 18 nm.
  • a dispersion Take 0.05g of carbon fiber with a diameter of 180nm and a length of 20 ⁇ m, add 25g of silicone oil, and stir at 200°C until the carbon fibers are fully dispersed to obtain a second dispersion; under high-speed stirring, slowly add the second dispersion to the first A dispersion liquid is mixed uniformly, carbon dioxide gas is introduced, stirring and heating are stopped, and the solid product is collected and dried after cooling to room temperature to obtain lithium supplement material A11.
  • the lithium supplement material A11 of Example 11 includes metallic lithium particles, carbon fibers, and a passivation layer (specifically, a lithium carbonate layer).
  • the carbon fiber includes a built-in section embedded in the metallic lithium particles and an exposed section located outside the metallic lithium particles; lithium carbonate The layer is located on the surface of the metallic lithium particles. It was found that the average particle size of the metal lithium particles was 37.8 ⁇ m, and the thickness of the lithium carbonate layer was 25 nm.
  • a dispersion Take 0.05g of graphene with a thickness of 10nm and a length of 8 ⁇ m, add 25g of silicone oil, and stir at 200°C until the graphene is fully dispersed to obtain a second dispersion; under high-speed stirring, slowly add the second dispersion The first dispersion liquid is mixed uniformly, carbon dioxide gas is introduced, stirring and heating are stopped, and the solid product is collected and dried after cooling to room temperature to obtain lithium supplement material A12.
  • the lithium supplement material A12 of Embodiment 12 includes metallic lithium particles, graphene, and a passivation layer (specifically, a lithium carbonate layer), and the graphene includes a built-in section embedded in the metallic lithium particles and an exposed section located outside the metallic lithium particles;
  • the lithium carbonate layer is located on the surface of the metallic lithium particles. It was found that the average particle size of the metal lithium particles was 41.0 ⁇ m, and the thickness of the lithium carbonate layer was 24 nm.
  • a dispersion liquid take 0.05g of multi-walled carbon nanotubes with a diameter of 10nm and a length of 50 ⁇ m, add 25g of silicone oil, and stir at 200°C until the multi-walled carbon nanotubes are fully dispersed to obtain a second dispersion;
  • the second dispersion liquid is slowly added to the first dispersion liquid and mixed uniformly, the stirring and heating are stopped, and the solid product is collected and dried after cooling to room temperature to obtain the lithium supplement material A13.
  • the lithium supplement material A13 of Embodiment 13 includes metallic lithium particles and multi-walled carbon nanotubes, the multi-walled carbon nanotubes are partially embedded in the metallic lithium particles, and the multi-walled carbon nanotubes may include built-in segments embedded in the metallic lithium particles and The exposed section located outside the lithium metal particles. It was found that the average particle size of the metal lithium particles was 27.7 ⁇ m.
  • a dispersion liquid take 0.05g of multi-walled carbon nanotubes with a diameter of 10nm and a length of 50 ⁇ m, add 25g of silicone oil, and stir at 200°C until the multi-walled carbon nanotubes are fully dispersed to obtain a second dispersion;
  • the second dispersion liquid is slowly added to the first dispersion liquid and mixed uniformly, the inert gas containing fluorine gas is introduced, the stirring and heating are stopped, and the solid product is collected and dried after cooling to room temperature to obtain the lithium supplement material A14.
  • the lithium supplement material A14 of Example 14 includes metallic lithium particles, multi-walled carbon nanotubes, and a passivation layer (specifically, a lithium fluoride layer), the multi-walled carbon nanotubes are partially embedded in the metallic lithium particles, and the multi-walled carbon nanotubes It may include a built-in section buried in the lithium metal particles and an exposed section located outside the lithium metal particles; the passivation layer is located on the surface of the lithium metal particles. It was found that the average particle size of the metal lithium particles was 28 ⁇ m, and the thickness of the passivation layer was 34 nm.
  • the lithium supplement material D1 includes lithium metal particles and a lithium carbonate passivation layer on the surface of the lithium metal particles, wherein the average particle size of the lithium metal particles is 24.8 ⁇ m, and the thickness of the lithium carbonate layer is 19 nm.
  • the lithium material D1 of Comparative Example 1 was used as a raw material, and it was physically mixed with carbon nanotubes in a weight ratio of 1:0.008.
  • the carbon nanotubes were multi-walled carbon nanotubes with a diameter of 20 nm and a length of 30 ⁇ m, which were obtained as a comparison
  • the lithium supplement material D2 of Comparative Example 2 includes the aforementioned lithium material D1 and multi-wall carbon nanotubes. Among them, the multi-wall carbon nanotubes and the lithium material D1 are only a simple physical mixing relationship, and the multi-wall carbon nanotubes are not partially embedded in the lithium material D1. in.
  • the first dispersion add 0.05g of acetylene black with an electronic conductivity of ⁇ 100s/cm to 25g of silicone oil, stir and fully disperse at 200°C to obtain the second dispersion; under the condition of high-speed stirring, the second dispersion
  • the first dispersion liquid was slowly added and mixed uniformly, carbon dioxide gas was introduced, the stirring and heating were stopped, and the solid product was collected and dried after cooling to room temperature to obtain the lithium supplement material D3 as a comparison.
  • the lithium supplement materials A1 to A14 obtained in Examples 1 to 14 and the lithium supplement materials D1, D2, D3 obtained in Comparative Examples 1 to 3 were respectively prepared into lithium ion batteries, and the preparation methods were as follows:
  • the lithium-ion battery obtained above was allowed to stand for 12 hours and then subjected to a lithium supplement efficiency test.
  • the lithium supplement efficiency test conditions were: under normal temperature conditions, the blue power test system produced by Wuhan Landian Electronics Co., Ltd. was used to constantly charge to 3V with a current of 0.01C. And calculate the actual lithium replenishment efficiency according to the charging capacity.
  • the test results are listed in Table 1.
  • Example 5 1.214 70.4
  • Example 6 1.185 68.7
  • Example 7 1.383 80.2
  • Example 8 1.361 78.9
  • Example 9 1.285 74.5
  • Example 10 1.251 72.5
  • Example 11 1.211 70.2
  • Example 12 1.066 61.8
  • Example 13 1.175 68.1
  • Example 14 1.199 69.5 Comparative example 1 0.818 47.4 Comparative example 2 0.857 49.7 Comparative example 3 0.836 48.5
  • the lithium supplement material of the embodiment of the present disclosure has excellent lithium supplement efficiency
  • the lithium supplement material (Comparative Example 1) that is not doped with conductive material and the supplement made by simply mixing the conductive material and metal lithium particles Compared with the lithium material (Comparative Example 2), the lithium ion battery containing the lithium supplement material of the embodiment of the present disclosure has higher charging capacity and higher lithium supplement efficiency.
  • the conductive material in the lithium supplement material prepared by the method of the present disclosure is buried in the metal lithium particles, and after the lithium supplement material and the non-lithium negative electrode sheet are rolled, the conductive material therein can be It is closely connected with the negative electrode active material to form a vertical three-dimensional conductive network, which can not only realize the electronic conduction between the lithium metal particles and the solid phase interface of the negative electrode material, but also realize the electronic conduction between the metal lithium particles and the negative electrode active material through the conductive material.
  • the electron conduction channel is also helpful for the transmission of lithium ions, and the rapid insertion process of lithium ions is realized, so that the efficiency of replenishing lithium is significantly improved, thereby effectively inhibiting the formation of dead lithium.
  • Example 1 Compared the data of Example 1 and Examples 11-12 in Table 1, it can be found that when the conductive material is carbon nanotubes, the button battery has a higher charge capacity and lithium replenishment efficiency. Comparing the data of Example 1 and Examples 4-6 in Table 1, it can be found that when the diameter of the multi-walled carbon nanotubes in the lithium supplement material is 10-30nm and the length is 30-50 ⁇ m, the button cell has higher performance. The charging capacity and the efficiency of replenishing lithium.
  • Example 13 Comparing the data of Example 1 and Example 13 in Table 1, it can be found that when the lithium supplement material does not have a passivation layer (Example 13), because metal lithium easily reacts with oxygen, carbon dioxide, and moisture in the air, it will A part of the active lithium is consumed, resulting in a decrease in the efficiency of replenishing lithium of the battery.

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Abstract

一种补锂材料及其制备方法和锂离子电池，该补锂材料包括金属锂颗粒（1）和导电材料（2），所述导电材料（2）包括埋入所述金属锂颗粒（1）中的内置段和位于所述金属锂颗粒（1）外部的外露段；所述导电材料（2）的电子导电率大于100s/cm。所述补锂材料可以通过导电材料（2）实现锂金属颗粒（1）与负极活性材料（3）的电子传导，增加了电子传导的通道，同时有助于锂离子的传输，实现锂离子的快速嵌入过程，使补锂效率显著提升，从而有效地抑制死锂的形成，避免形成枝晶刺穿电池隔膜而造成安全隐患。

Description

一种补锂材料及其制备方法、负极和锂离子电池
本申请要求于2019年12月16日提交中国专利局、申请号为201911296454.7、发明名称为“一种补锂材料及其制备方法、负极和锂离子电池”的中国专利申请的优先权，上述在先申请的内容以引入的方式并入本文本中。
技术领域
本公开涉及锂离子电池领域，具体地，涉及一种补锂材料及其制备方法、负极和锂离子电池。
背景技术
锂离子电池具有比能量高、循环寿命长等优点，已被广泛应用于笔记本电脑、手机等各种便携式电子设备领域。随着能源问题与环境问题的日益严峻，各国对节能减排的要求越来越高。传统燃油车不仅消耗石油这种储量有限的化石能源而且尾气污染严重，因此电动车应运而生。锂离子动力电池作为电动车的主要储能单元受到越来越广泛的关注，展现出良好的发展前景。随着人们对续航里程以及驾车体验要求的不断提升，提高动力电池能量密度就显得尤为重要，可通过优化电池结构、采用容量更高的电极材料以及拓展电池的工作电压等手段实现。
在锂离子电池首次充电过程中，有机电解液在石墨等负极表面还原分解，形成固体电解质相界面(SEI)膜，永久地消耗从正极脱出的锂离子，造成不 可逆容量的损失，降低了首次充放电库伦效率与能量密度。传统的负极材料石墨理论比容量为372mAh/g，首次不可逆容量损失为5％～10％，对于高容量的负极材料，例如硅、合金等，首次不可逆容量更高。为了解决这个问题，研究者们提出了预锂化技术。通过预锂化抵消材料形成SEI膜时所消耗的锂离子以提高电池的总容量。
目前的预锂化技术大致可以分为负极补锂、正极补锂、隔膜补锂以及电解液补锂等。常见的负极补锂包括锂箔补锂、锂粉补锂。金属锂的电位是所有电极材料中最低的，由于电势差的存在，当负极材料与金属锂箔或锂粉接触时，电子会自发地向负极移动，使得锂离子嵌入负极。但将补锂材料压按或涂覆于负极材料表面，当锂金属与石墨不接触或最接近负极材料的补锂层消耗掉之后，容易形成死锂大大降低补锂效率，还有可能形成枝晶，造成安全隐患。
发明内容
本公开的目的是提供一种补锂材料，该补锂材料补锂效率高，且避免了形成死锂而造成枝晶现象。
为了实现上述目的，本公开提供一种补锂材料，该补锂材料包括金属锂颗粒和导电材料，所述导电材料包括埋入所述金属锂颗粒中的内置段和位于所述金属锂颗粒外部的外露段；所述导电材料的电子导电率大于100s/cm。
可选地，所述导电材料为碳材料；所述碳材料选自碳纳米管、碳纤维和石墨烯中的至少一种；
优选地，所述碳材料为碳纳米管；所述碳纳米管为单壁碳纳米管和/或多壁碳纳米管，优选为多壁碳纳米管；和/或，所述碳纳米管的管径为5nm-100nm， 优选为10nm-30nm，长度为10μm-80μm，优选为30μm-50μm。
可选地，相对于100重量份的所述金属锂颗粒，所述导电材料的含量为0.1-3重量份，优选为0.5-1重量份。
可选地，所述金属锂颗粒的平均粒径为20μm-40μm；和/或，
所述金属锂颗粒的表面具有钝化层；所述钝化层的厚度为5nm-100nm；所述钝化层含有碳酸锂、氟化锂和石蜡中的至少一种。
本公开第二方面提供一种制备补锂材料的方法，该方法包括：
S1、在金属锂熔融的温度下，将含有熔融金属锂的第一分散液与含有导电材料的第二分散液混合，并充分搅拌得到混合后的物料；所述导电材料的电子导电率大于100s/cm；
S2、将所述混合后的物料冷却至金属锂凝固，并进行固液分离。
可选地，步骤S1中，所述导电材料为碳材料；所述碳材料选自碳纳米管、碳纤维和石墨烯中的至少一种；优选地，所述碳材料为单壁碳纳米管和/或多壁碳纳米管，优选为多壁碳纳米管；所述碳纳米管的管径为5nm-100nm，优选为10nm-30nm，长度为10μm-80μm，优选为30μm-50μm；和/或，
所述第一分散液中还含有表面活性剂；所述表面活性剂选自聚乙烯吡咯烷酮、十二烷基苯磺酸钠和十六烷基三甲基溴化胺的至少一种，优选为聚乙烯吡咯烷酮；所述金属锂和所述表面活性剂的重量比为1：(0.002-0.05)，优选为1：(0.005-0.02)；和/或，
所述第一分散液和所述第二分散液的分散介质为惰性有机溶剂，所述第一分散液和所述第二分散液的分散介质各自独立地选自烃、酯、醚和硅油的至少一种；和/或，
所述第一分散液和所述第二分散液的体积比为1：(0.1-10)，优选为1：(0.5-3)；所述金属锂与所述导电材料的重量比为100：(0.1-3)，优选为100：(0.5-1)。
可选地，该方法还包括：步骤S1中，待所述第一分散液和所述第二分散液混合均匀后通入二氧化碳。
本公开第三方面提供一种由本公开第二方面所提供的方法所制备的补锂材料。
本公开第四方面提供一种锂离子电池负极，该负极包括集流体、负极活性材料和补锂材料，所述补锂材料为本公开第一方面和本公开第三方面任意一项所述的补锂材料。
本公开第五方面提供一种锂离子电池，该电池包括本公开第四方面所提供的锂离子电池负极。
通过上述技术方案，本公开的补锂材料可以通过导电材料实现锂金属颗粒与负极活性材料的电子传导，增加了电子传导的通道，同时有助于锂离子的传输，实现锂离子的快速嵌入过程，使补锂效率显著提升，从而有效地抑制死锂的形成，避免形成枝晶刺穿隔膜而造成安全隐患。
本公开的其他特征和优点将在随后的具体实施方式部分予以详细说明。
附图说明
附图是用来提供对本公开的进一步理解，并且构成说明书的一部分，与下面的具体实施方式一起用于解释本公开，但并不构成对本公开的限制。在附图中：
图1是本公开的补锂材料应用于锂离子电池负极时的补锂原理示意图。
附图标记说明：
1金属锂颗粒 2导电材料 3负极活性材料
具体实施方式
以下结合附图对本公开的具体实施方式进行详细说明。应当理解的是，此处所描述的具体实施方式仅用于说明和解释本公开，并不用于限制本公开。
本公开第一方面提供一种补锂材料，该补锂材料包括金属锂颗粒和导电材料，所述导电材料包括埋入所述金属锂颗粒中的内置段和位于所述金属锂颗粒外部的外露段；所述导电材料的电子导电率大于100s/cm。在一种具体的实施方式中，所述导电材料可以为电子导电率大于100s/cm的一维材料和/或二维材料。
根据本公开，所述导电材料包括埋入所述金属锂颗粒中的内置段和位于所述金属锂颗粒外部的外露段，可以有多种实现方式，例如，所述导电材料可以穿插于所述金属锂颗粒，在一种实施方式中，所述导电材料长度较长，当其大于所述金属锂颗粒的粒径时，所述导电材料可能会贯穿一个甚至若干个所述金属锂颗粒，此时，所述导电材料包括多个埋入所述金属锂颗粒中的内置段和多个位于所述金属锂颗粒外部的外露段，而且所述导电材料可以弯曲；在另一种实施方式中，所述导电材料长度较短，当其小于所述金属锂颗粒的粒径时，所述导电材料可能仅仅部分埋入所述金属锂颗粒，此时，所述导电材料仅包括一个埋入所述金属锂颗粒中的内置段和一个位于所述金属锂颗粒外部的外露段。所述金属锂颗粒埋入所述导电材料的所述内置段的数目没有特别限制。
本公开的发明人发现，当补锂材料中的导电材料的部分埋入金属锂颗粒时，将所述补锂材料与未补锂的负极片辊压，导电材料可与负极活性材料实现紧密连接，形成垂直的三维导电网络，不仅可以实现锂金属颗粒与负极材料固相界面的电子传导，还可以通过导电材料实现金属锂颗粒内部与负极活性材料的电子传导，增加了电子传导的通道，同时有助于锂离子的传输，实现锂离子的快速嵌入过程，使补锂效率显著提升，从而有效地抑制死锂的形成，避免形成枝晶刺穿隔膜而造成安全隐患。
根据本公开，所述导电材料可以为本领域已知的碳材料，例如，所述碳材料可以选自碳纳米管、碳纤维和石墨烯中的至少一种，在一种优选的实施方式中，所述碳材料可以为碳纳米管，碳纳米管具有一维管状结构，电子可以通过其进行高速传导，因此具有优异的电子导电率；金属锂颗粒体积较大，直径在几十微米级别，因而，碳纳米管弯曲缠绕的形状更有利于穿插形成导电网络。
根据本公开，所述碳纳米管为本领域已知，例如，所述碳纳米管为单壁碳纳米管和/或多壁碳纳米管的至少一种，为了提高其导电性能，在一种优选的实施方式中，所述碳纳米管可以为多壁碳纳米管。所述碳纳米管在尺寸上没有特殊要求，在一种具体的实施方式中，所述碳纳米管的管径可以为5nm-100nm，优选为10nm-30nm，长度可以为10μm-80μm，优选为30μm-50μm。
根据本公开，相对于100重量份的所述金属锂颗粒，所述导电材料的含量可以在一定范围内变化，为了发挥导电材料的最佳性能，提供适宜比例的导电网络，所述导电材料的含量可以为0.1-3重量份，在一种优选的实施方式中，所述导电材料的含量可以为0.5-1重量份。
根据本公开，所述金属锂颗粒的平均粒径可以在较大范围内变化，优选地， 平均粒径可以为20μm-40μm。其中，所述金属锂颗粒的平均粒径可以通过扫描电镜观察随机任意100个金属锂颗粒分别量取粒径值，粒径的平均值即为金属锂颗粒的平均粒径。
根据本公开，为了有效阻止内部的金属锂与空气中的氧气、二氧化碳与水分等接触进一步反应，所述金属锂颗粒表面还具有一层钝化层；所述钝化层可以为具有化学稳定性的碳酸锂层、氟化锂层和石蜡层中的至少一种，所述钝化层的厚度可以在较大范围变化，例如，所述钝化层的厚度可以为5-100nm，在优选的实施方式中，所述钝化层的厚度可以为10-30nm。
本公开第二方面提供一种补锂材料的方法，该方法具体包括：
S1、在金属锂熔融的温度下，将含有熔融金属锂的第一分散液与含有导电材料的第二分散液混合，并充分搅拌得到混合后的物料；所述导电材料的电子导电率大于100s/cm；
S2、将所述混合后的物料冷却至金属锂凝固，并进行固液分离。
根据本公开，步骤S1中，所述导电材料可以为本领域已知的碳材料，例如，所述碳材料可以选自碳纳米管、碳纤维和石墨烯中的至少一种，在一种优选的实施方式中，所述碳材料可以为碳纳米管，碳纳米管具有一维管状结构，电子可以通过其进行高速传导，因此具有优异的电子导电率；金属锂颗粒的体积较大，直径在几十微米级别，因而，碳纳米管弯曲缠绕的形状更有利于穿插形成导电网络。
根据本公开，所述碳纳米管为本领域已知，例如，所述碳纳米管可以为单壁碳纳米管和/或多壁碳纳米管的至少一种，为了提高其导电性能，在一种优选的实施方式中，所述碳纳米管可以为多壁碳纳米管。所述碳纳米管在尺寸上 没有特殊要求，在一种具体的实施方式中，所述碳纳米管的管径可以为5nm-100nm，优选为10nm-30nm，长度可以为10μm-80μm，优选为30μm-50μm。
根据本公开，步骤S1中，所述第一分散液还可以含有表面活性剂，所述表面活性剂为本领域已知，例如，所述表面活性剂可以选自聚乙烯吡咯烷酮、十二烷基苯磺酸钠和十六烷基三甲基溴化胺的一种或几种，在一种优选的实施方式中，所述表面活性剂可以为聚乙烯吡咯烷酮。所述金属锂和所述表面活性剂的重量比可以在一定范围内变化，例如，所述金属锂和所述表面活性剂的重量比可以为1：(0.002-0.05)，优选为1：(0.005-0.02)。
根据本公开，所述第一分散液和所述第二分散液的分散介质为本领域常见的惰性有机溶剂，所述第一分散液和所述第二分散液的分散介质可以各自独立地选自烃、酯、醚和硅油的至少一种，例如，所述第一分散液和所述第二分散液的分散介质可以选自本领域常用的烃油、白油和硅油的至少一种，在一种优选的方式中，所述第一分散液和所述第二分散液的分散介质可以为硅油，比如常见的甲基硅油、乙基硅油、甲基乙氧基硅油，在此不再赘述。
根据本公开，所述第一分散液和所述第二分散液的体积比可以在较大范围内变化，例如，所述第一分散液和所述第二分散液的体积比可以为1：(0.1-10)，优选为1：(0.5-3)。所述金属锂与所述导电材料的重量比可以在较大范围内变化，例如，所述金属锂与所述导电材料的重量比可以为100：(0.1-3)，优选为100：(0.5-1)。
根据本公开，该方法还可以包括通入二氧化碳以形成钝化层的步骤，例如，步骤S1中，待所述第一分散液和所述第二分散液混合后通入含有二氧化碳的惰性气体。为了得到均匀致密的钝化层，在优选的实施方式中，所述气体可以 为高纯度二氧化碳。
本公开第三方面提供一种由本公开第二方面所提供的的方法所制备的补锂材料。
本公开第四方面提供一种锂离子电池负极，该负极包括集流体、负极活性材料和补锂材料，所述补锂材料为本公开第一方面和/或本公开第三方面所提供的补锂材料。
根据本公开，负极集流体可以为锂离子电池中常规的负极集流体，如冲压金属，金属箔，网状金属，泡沫状金属。负极活性材料还可以包括粘结剂，其种类可以为本领域常规的，此处不再赘述。
本公开的锂离子电池负极的制备方法无特殊要求，可以参照现有技术进行，例如，本公开的锂离子电池负极的制备方法可以包括：将含有负极活性材料和粘结剂的负极浆料涂覆和/或填充在负极集流体上，再经干燥、辊压。具体的操作方法和条件可以为本领域常规的，此处无特殊限制。
图1为将本公开的补锂材料应用于锂离子电池负极时的补锂原理示意图，当导电材料2，例如碳纳米管等的部分埋入金属锂颗粒1时，导电材料2可以缠绕贯穿金属锂颗粒1，经过辊压后，弯曲缠绕的导电材料2可与负极活性材料3紧密连接，形成垂直的三维导电网络，从而不仅可以实现金属锂颗粒1与负极活性材料3固相界面的粒子传导，而且未与负极活性材料3接触的金属锂颗粒1也可以通过导电材料2将粒子传递到负极活性材料3，金属锂颗粒1可以通过导电材料2实现与负极活性材料3的电子传导过程，同时有助于锂离子的传输，实现锂离子的快速嵌入过程，从而有效地抑制死锂的形成，补锂效率显著提升，避免形成枝晶而造成安全隐患。
本公开第五方面提供一种锂离子电池，该电池包括本公开第四方面所提供的锂离子电池负极。
根据本公开，锂离子电池还可以包括正极、隔膜和电解液，本公开对正极、隔膜和电解液没有特殊限制，可以为本领域的常规种类，该锂离子电池也可采用本领域常规的方法制备，例如，通过隔膜将正极和本公开的上述负极缠绕隔开形成电极组，将得到的电极组和电解液密封在电池壳中，即可得到本公开提供的锂离子电池。位于正极与负极之间的隔膜的卷绕方法为本领域技术人员所公知，在此不再赘述。
下面通过实施例进一步说明本公开，但是本公开并不因此而受到任何限制。
实施例和对比例中所用原料性质如下：
多壁碳纳米管，购自江苏天奈科技股份公司，其电子导电率＞150s/cm。
单壁碳纳米管，购自江苏天奈科技股份公司，其电子导电率＞150s/cm。
碳纤维，购自江苏天奈科技股份公司，其电子导电率＞100s/cm。
石墨烯，购自江苏天奈科技股份公司，其电子导电率＞100s/cm。
其余原料未经进一步说明的，均为市售品。
实施例1
在-60℃的干燥环境下，将金属锂锭10g加入25g二甲基硅油中并升温至200℃，待金属锂锭完全熔融后加入聚乙烯吡咯烷酮0.1g，搅拌至金属锂锭完全溶解得到第一分散液；取0.05g管径为10nm、长度为50μm的多壁碳纳米管加入25g硅油，200℃下搅拌至多壁碳纳米管充分分散，得到第二分散液；在高速搅拌条件下，将第二分散液缓慢加入第一分散液并混合均匀，通入二氧化 碳气体，停止搅拌与加热，待冷却至室温后收集固体产物并干燥，得到补锂材料A1。
实施例1的补锂材料A1包括金属锂颗粒、多壁碳纳米管和钝化层(具体为碳酸锂层)，该多壁碳纳米管部分嵌入金属锂颗粒中，该多壁碳纳米管可以包括埋入金属锂颗粒中的内置段和位于金属锂颗粒外部的外露段；碳酸锂层位于金属锂颗粒的表面。检测发现，金属锂颗粒的平均粒径为27.8μm，碳酸锂层的厚度为21nm。
实施例2
在-60℃的干燥环境下，将金属锂锭10g加入25g二甲基硅油中并升温至200℃，待金属锂锭完全熔融后加入十二烷基苯磺酸钠0.1g，搅拌至金属锂锭完全溶解得到第一分散液；取0.05g管径为10nm、长度为50μm的多壁碳纳米管加入25g硅油，200℃下搅拌至多壁碳纳米管充分分散，得到第二分散液；在高速搅拌条件下，将第二分散液缓慢加入第一分散液并混合均匀，通入二氧化碳气体，停止搅拌与加热，待冷却至室温后收集固体产物并干燥，得到补锂材料A2。
实施例2的补锂材料A2包括金属锂颗粒、多壁碳纳米管和钝化层(具体为碳酸锂层)，该多壁碳纳米管包括埋入金属锂颗粒中的内置段和位于金属锂颗粒外部的外露段；碳酸锂层位于金属锂颗粒的表面。检测发现，金属锂颗粒的平均粒径为42.2μm，碳酸锂层的厚度为27nm。
实施例3
在-60℃的干燥环境下，将金属锂锭10g加入25g二甲基硅油中并升温至200℃，待金属锂锭完全熔融后加入十六烷基三甲基溴化胺0.1g，搅拌至金属 锂锭完全溶解得到第一分散液；取0.05g管径为10nm、长度为50μm的多壁碳纳米管加入25g硅油，200℃下搅拌至多壁碳纳米管充分分散，得到第二分散液；在高速搅拌条件下，将第二分散液缓慢加入第一分散液并混合均匀，通入二氧化碳气体，停止搅拌与加热，待冷却至室温后收集固体产物并干燥，得到补锂材料A3。
实施例3的补锂材料A3包括金属锂颗粒、多壁碳纳米管和钝化层(具体为碳酸锂层)，该多壁碳纳米管包括埋入金属锂颗粒中的内置段和位于金属锂颗粒外部的外露段；碳酸锂层位于金属锂颗粒的表面。检测发现，金属锂颗粒的平均粒径为45.4μm，碳酸锂层的厚度为35nm。
实施例4
在-60℃的干燥环境下，将金属锂锭10g加入25g二甲基硅油中并升温至200℃，待金属锂锭完全熔融后加入聚乙烯吡咯烷酮0.1g，搅拌至金属锂锭完全溶解得到第一分散液；取0.05g管径为20nm、长度为30μm的多壁碳纳米管加入25g硅油，200℃下搅拌至多壁碳纳米管充分分散，得到第二分散液；在高速搅拌条件下，将第二分散液缓慢加入第一分散液并混合均匀，通入二氧化碳气体，停止搅拌与加热，待冷却至室温后收集固体产物并干燥，得到补锂材料A4。
实施例4的补锂材料A4包括金属锂颗粒、多壁碳纳米管和钝化层(具体为碳酸锂层)，该多壁碳纳米管包括埋入金属锂颗粒中的内置段和位于金属锂颗粒外部的外露段；碳酸锂层位于金属锂颗粒的表面。检测发现，金属锂颗粒的平均粒径为26.2μm，碳酸锂层的厚度为27nm。
实施例5
在-60℃的干燥环境下，将金属锂锭10g加入25g二甲基硅油中并升温至200℃，待金属锂锭完全熔融后加入聚乙烯吡咯烷酮0.1g，搅拌至金属锂锭完全溶解得到第一分散液；取0.05g管径为40nm、长度为20μm的多壁碳纳米管加入25g硅油，200℃下搅拌至多壁碳纳米管充分分散，得到第二分散液；在高速搅拌条件下，将第二分散液缓慢加入第一分散液并混合均匀，通入二氧化碳气体，停止搅拌与加热，待冷却至室温后收集固体产物并干燥，得到补锂材料A5。
实施例5的补锂材料A5包括金属锂颗粒、多壁碳纳米管和钝化层(具体为碳酸锂层)，该多壁碳纳米管包括埋入金属锂颗粒中的内置段和位于金属锂颗粒外部的外露段；碳酸锂层位于金属锂颗粒的表面。检测发现，金属锂颗粒的平均粒径为29.2μm，碳酸锂层的厚度为20nm。
实施例6
在-60℃的干燥环境下，将金属锂锭10g加入25g二甲基硅油中并升温至200℃，待金属锂锭完全熔融后加入聚乙烯吡咯烷酮0.1g，搅拌至金属锂锭完全溶解得到第一分散液；取0.05g管径为60nm、长度为20μm的多壁碳纳米管加入25g硅油，200℃下搅拌至多壁碳纳米管充分分散，得到第二分散液；在高速搅拌条件下，将第二分散液缓慢加入第一分散液并混合均匀，通入二氧化碳气体，停止搅拌与加热，待冷却至室温后收集固体产物并干燥，得到补锂材料A6。
实施例6的补锂材料A6包括金属锂颗粒、多壁碳纳米管和钝化层(具体为碳酸锂层)，该多壁碳纳米管包括埋入金属锂颗粒中的内置段和位于金属锂颗粒外部的外露段；碳酸锂层位于金属锂颗粒的表面。检测发现，金属锂颗粒 的平均粒径为39.6μm，碳酸锂层的厚度为23nm。
实施例7
在-60℃的干燥环境下，将金属锂锭10g加入25g二甲基硅油中并升温至200℃，待金属锂锭完全熔融后加入聚乙烯吡咯烷酮0.1g，搅拌至金属锂锭完全溶解得到第一分散液；取0.08g管径为20nm、长度为30μm的多壁碳纳米管加入25g硅油，200℃下搅拌至多壁碳纳米管充分分散，得到第二分散液；在高速搅拌条件下，将第二分散液缓慢加入第一分散液并混合均匀，通入二氧化碳气体，停止搅拌与加热，待冷却至室温后收集固体产物并干燥，得到补锂材料A7。
实施例7的补锂材料A7包括金属锂颗粒、多壁碳纳米管和钝化层(具体为碳酸锂层)，该多壁碳纳米管包括埋入金属锂颗粒中的内置段和位于金属锂颗粒外部的外露段；碳酸锂层位于金属锂颗粒的表面。检测发现，金属锂颗粒的平均粒径为25.0μm，碳酸锂层的厚度为22nm。
实施例8
在-60℃的干燥环境下，将金属锂锭10g加入25g二甲基硅油中并升温至200℃，待金属锂锭完全熔融后加入聚乙烯吡咯烷酮0.1g，搅拌至金属锂锭完全溶解得到第一分散液；取0.1g管径为20nm、长度为30μm的多壁碳纳米管加入25g硅油，200℃下搅拌至多壁碳纳米管充分分散，得到第二分散液；在高速搅拌条件下，将第二分散液缓慢加入第一分散液并混合均匀，通入二氧化碳气体，停止搅拌与加热，待冷却至室温后收集固体产物并干燥，得到补锂材料A8。
实施例8的补锂材料A8包括金属锂颗粒、多壁碳纳米管和钝化层(具体 为碳酸锂层)，该多壁碳纳米管包括埋入金属锂颗粒中的内置段和位于金属锂颗粒外部的外露段；碳酸锂层位于金属锂颗粒的表面。检测发现，金属锂颗粒的平均粒径为26.4μm，碳酸锂层的厚度为26nm。
实施例9
在-60℃的干燥环境下，将金属锂锭10g加入25g二甲基硅油中并升温至200℃，待金属锂锭完全熔融后加入聚乙烯吡咯烷酮0.1g，搅拌至金属锂锭完全溶解得到第一分散液；取0.2g管径为20nm、长度为30μm的多壁碳纳米管加入25g硅油，200℃下搅拌至多壁碳纳米管充分分散，得到第二分散液；在高速搅拌条件下，将第二分散液缓慢加入第一分散液并混合均匀，通入二氧化碳气体，停止搅拌与加热，待冷却至室温后收集固体产物并干燥，得到补锂材料A9。
实施例9的补锂材料A9包括金属锂颗粒、多壁碳纳米管和钝化层(具体为碳酸锂层)，该多壁碳纳米管包括埋入金属锂颗粒中的内置段和位于金属锂颗粒外部的外露段；碳酸锂层位于金属锂颗粒的表面。检测发现，金属锂颗粒的平均粒径为27.6μm，碳酸锂层的厚度为22nm。
实施例10
在-60℃的干燥环境下，将金属锂锭10g加入25g二甲基硅油中并升温至200℃，待金属锂锭完全熔融后加入聚乙烯吡咯烷酮0.1g，搅拌至金属锂锭完全溶解得到第一分散液；取0.05g管径为2nm、长度为30μm的单壁碳纳米管加入25g硅油，200℃下搅拌至单壁碳纳米管充分分散，得到第二分散液；在高速搅拌条件下，将第二分散液缓慢加入第一分散液并混合均匀，通入二氧化碳气体，停止搅拌与加热，待冷却至室温后收集固体产物并干燥，得到补锂材 料A10。
实施例10的补锂材料A10包括金属锂颗粒、单壁碳纳米管和钝化层(具体为碳酸锂层)，该单壁碳纳米管包括埋入金属锂颗粒中的内置段和位于金属锂颗粒外部的外露段；碳酸锂层位于金属锂颗粒的表面。检测发现，金属锂颗粒的平均粒径为28.2μm，碳酸锂层的厚度为18nm。
实施例11
在-60℃的干燥环境下，将金属锂锭10g加入25g二甲基硅油中并升温至200℃，待金属锂锭完全熔融后加入聚乙烯吡咯烷酮0.1g，搅拌至金属锂锭完全溶解得到第一分散液；取0.05g管径为180nm、长度为20μm的碳纤维加入25g硅油，200℃下搅拌至碳纤维充分分散，得到第二分散液；在高速搅拌条件下，将第二分散液缓慢加入第一分散液并混合均匀，通入二氧化碳气体，停止搅拌与加热，待冷却至室温后收集固体产物并干燥，得到补锂材料A11。
实施例11的补锂材料A11包括金属锂颗粒、碳纤维和钝化层(具体为碳酸锂层)，该碳纤维包括埋入金属锂颗粒中的内置段和位于金属锂颗粒外部的外露段；碳酸锂层位于金属锂颗粒的表面。检测发现，金属锂颗粒的平均粒径为37.8μm，碳酸锂层的厚度为25nm。
实施例12
在-60℃的干燥环境下，将金属锂锭10g加入25g二甲基硅油中并升温至200℃，待金属锂锭完全熔融后加入聚乙烯吡咯烷酮0.1g，搅拌至金属锂锭完全溶解得到第一分散液；取0.05g厚度为10nm、长度为8μm的石墨烯加入25g硅油，200℃下搅拌至石墨烯充分分散，得到第二分散液；在高速搅拌条件下，将第二分散液缓慢加入第一分散液并混合均匀，通入二氧化碳气体，停止搅拌 与加热，待冷却至室温后收集固体产物并干燥，得到补锂材料A12。
实施例12的补锂材料A12包括金属锂颗粒、石墨烯和钝化层(具体为碳酸锂层)，该石墨烯包括埋入金属锂颗粒中的内置段和位于金属锂颗粒外部的外露段；碳酸锂层位于金属锂颗粒的表面。检测发现金属锂颗粒的平均粒径为41.0μm，碳酸锂层的厚度为24nm。
实施例13
在-60℃的干燥环境下，将金属锂锭10g加入25g二甲基硅油中并升温至200℃，待金属锂锭完全熔融后加入聚乙烯吡咯烷酮0.1g，搅拌至金属锂锭完全溶解得到第一分散液；取0.05g管径为10nm、长度为50μm的多壁碳纳米管加入25g硅油，200℃下搅拌至多壁碳纳米管充分分散，得到第二分散液；在高速搅拌条件下，将第二分散液缓慢加入第一分散液并混合均匀，停止搅拌与加热，待冷却至室温后收集固体产物并干燥，得到补锂材料A13。
实施例13的补锂材料A13包括金属锂颗粒和多壁碳纳米管，该多壁碳纳米管部分嵌入金属锂颗粒中，该多壁碳纳米管可以包括埋入金属锂颗粒中的内置段和位于金属锂颗粒外部的外露段。检测发现，金属锂颗粒的平均粒径为27.7μm。
实施例14
在-60℃的干燥环境下，将金属锂锭10g加入25g二甲基硅油中并升温至200℃，待金属锂锭完全熔融后加入聚乙烯吡咯烷酮0.1g，搅拌至金属锂锭完全溶解得到第一分散液；取0.05g管径为10nm、长度为50μm的多壁碳纳米管加入25g硅油，200℃下搅拌至多壁碳纳米管充分分散，得到第二分散液；在高速搅拌条件下，将第二分散液缓慢加入第一分散液并混合均匀，通入含氟气 的惰性气体，停止搅拌与加热，待冷却至室温后收集固体产物并干燥，得到补锂材料A14。
实施例14的补锂材料A14包括金属锂颗粒、多壁碳纳米管和钝化层(具体为氟化锂层)，该多壁碳纳米管部分嵌入金属锂颗粒中，该多壁碳纳米管可以包括埋入金属锂颗粒中的内置段和位于金属锂颗粒外部的外露段；钝化层位于金属锂颗粒的表面。检测发现，金属锂颗粒的平均粒径为28μm，钝化层的厚度为34nm。
对比例1
在-60℃的干燥环境下，将金属锂锭10g加入25g二甲基硅油中并升温至200℃，待金属锂锭完全熔融后加入聚乙烯吡咯烷酮0.1g，搅拌至金属锂锭完全溶解，在高速搅拌条件下通入二氧化碳气体，然后停止搅拌与加热，待冷却至室温后收集固体产物并干燥，得到作为对比的补锂材料D1。
该补锂材料D1中，包括金属锂颗粒和位于金属锂颗粒表面的碳酸锂钝化层，其中，金属锂颗粒的平均粒径为24.8μm，碳酸锂层的厚度为19nm。
对比例2
采用对比例1的锂材料D1作为原料，将其与碳纳米管按照重量比1：0.008进行物理混合，所述碳纳米管管径为20nm、长度为30μm的多壁碳纳米管，得到作为对比的补锂材料D2。
对比例2的补锂材料D2包括前述锂材料D1和多壁碳纳米管，其中，多壁碳纳米管与锂材料D1只是简单的物理混合关系，多壁碳纳米管并没有部分嵌入锂材料D1中。
对比例3
在-60℃的干燥环境下，将金属锂锭10g加入25g二甲基硅油中并升温至200℃，待金属锂锭完全熔融后加入聚乙烯吡咯烷酮0.1g，搅拌至金属锂锭完全溶解，得到第一分散液；将0.05g的、电子导电率＜100s/cm的乙炔黑加入到25g硅油中，200℃下搅拌充分分散，得到第二分散液；在高速搅拌条件下，将第二分散液缓慢加入第一分散液并混合均匀，通入二氧化碳气体，停止搅拌与加热，待冷却至室温后收集固体产物并干燥，得到作为对比的补锂材料D3。
测试例
将实施例1～14得到的补锂材料A1～A14和对比例1～3所得补锂材料D1、D2、D3分别制备成锂离子电池，制备方法如下：
按重量比石墨：导电剂：粘结剂＝96：2：2混合得到负极浆料，将其涂覆于铜箔上并烘干，辊压后制备得到未补锂的极片；将上述补锂材料溶解于易挥发的NMP溶剂中，均匀印刷或涂覆在前述未补锂的负极片上，辊压至同一厚度，裁片称重作为扣式电池的正极，用锂片作为负极制备得到扣式电池AS1～AS14和作为对比的扣式电池DS1～DS3。
对上述得到的锂离子电池静置12h后进行补锂效率测试，补锂效率测试条件为：常温条件下用武汉蓝电电子有限公司生产的蓝电测试系统，利用0.01C电流恒定充电至3V，并根据充电容量计算实际补锂效率。测试结果列于表1。
表1
实施/对比例 充电容量(mAh) 补锂效率(％)
实施例1 1.270 73.6
实施例2 1.125 65.2
实施例3 1.116 64.7
实施例4 1.297 75.2
实施例5 1.214 70.4
实施例6 1.185 68.7
实施例7 1.383 80.2
实施例8 1.361 78.9
实施例9 1.285 74.5
实施例10 1.251 72.5
实施例11 1.211 70.2
实施例12 1.066 61.8
实施例13 1.175 68.1
实施例14 1.199 69.5
对比例1 0.818 47.4
对比例2 0.857 49.7
对比例3 0.836 48.5
由表1的数据可知，本公开实施例的补锂材料具有优异的补锂效率，与未掺杂导电材料的补锂材料(对比例1)及导电材料与金属锂颗粒简单混合制得的补锂材料(对比例2)相比，含有本公开实施例的补锂材料的锂离子电池的充电克容量、补锂效率均更高。这可能是因为，采用本公开的方法制备得到的补锂材料中的导电材料的部分埋于金属锂颗粒，将所述补锂材料与未补锂的负极片辊压后，其中的导电材料可与负极活性材料实现紧密连接，形成垂直的三维导电网络，不仅可以实现锂金属颗粒与负极材料固相界面的电子传导，还可以通过导电材料实现金属锂颗粒内部与负极活性材料的电子传导，增加了电子传导的通道，同时有助于锂离子的传输，实现锂离子的快速嵌入过程，使补锂效率显著提升，从而有效地抑制死锂的形成。此外，比较表1中本公开实施例1-14与对比例3的数据可以发现，当补锂材料中导电材料的电子导电率过小时，也会大大降低金属锂颗粒内部与负极活性材料之间的电子传导，进而降低 电池的补锂效率。
进一步地，比较表1中实施例1与实施例11-12的数据可以发现，在导电材料为碳纳米管时，扣式电池具有较高的充电容量和补锂效率。比较表1中实施例1与实施例4-6的数据可以发现，在补锂材料中的多壁碳纳米管的管径为10～30nm、长度为30～50μm时，扣式电池具有更高的充电容量和补锂效率。比较表1中实施例1与实施例13的数据可以发现，当补锂材料不具有钝化层时(实施例13)，因金属锂容易与空气中的氧气、二氧化碳、水分等发生反应，会消耗一部分活性锂，导致电池的补锂效率降低。
以上结合附图详细描述了本公开的优选实施方式，但是，本公开并不限于上述实施方式中的具体细节，在本公开的技术构思范围内，可以对本公开的技术方案进行多种简单变型，这些简单变型均属于本公开的保护范围。
另外需要说明的是，在上述具体实施方式中所描述的各个具体技术特征，在不矛盾的情况下，可以通过任何合适的方式进行组合。为了避免不必要的重复，本公开对各种可能的组合方式不再另行说明。
此外，本公开的各种不同的实施方式之间也可以进行任意组合，只要其不违背本公开的思想，其同样应当视为本公开所公开的内容。

Claims (15)

  1. 一种补锂材料，其特征在于，该补锂材料包括金属锂颗粒和导电材料，所述导电材料包括埋入所述金属锂颗粒中的内置段和位于所述金属锂颗粒外部的外露段；所述导电材料的电子导电率大于100s/cm。
  2. 根据权利要求1所述的补锂材料，其中，所述导电材料为碳材料；所述碳材料选自碳纳米管、碳纤维和石墨烯中的至少一种；优选地，所述碳材料为碳纳米管；所述碳纳米管为单壁碳纳米管和/或多壁碳纳米管，优选为多壁碳纳米管。
  3. 根据权利要求2所述的补锂材料，其中，所述碳纳米管的管径为5nm-100nm，优选为10nm-30nm；所述碳纳米管的长度为10μm-80μm，优选为30μm-50μm。
  4. 根据权利要求1所述的补锂材料，其中，相对于100重量份的所述金属锂颗粒，所述导电材料的含量为0.1-3重量份，优选为0.5-1重量份。
  5. 根据权利要求1所述的补锂材料，其中，所述金属锂颗粒的平均粒径为20μm-40μm。
  6. 根据权利要求1所述的补锂材料，其中，所述金属锂颗粒的表面具有钝化层；所述钝化层含有碳酸锂、氟化锂和石蜡中的至少一种。
  7. 根据权利要求6所述的补锂材料，其中，所述钝化层的厚度为5nm-100nm。
  8. 一种制备补锂材料的方法，其特征在于，该方法包括：
    S1、在金属锂熔融的温度下，将含有熔融金属锂的第一分散液与含有导电材料的第二分散液混合，得到混合后的物料；所述导电材料的电子导电率大于 100s/cm；
    S2、将所述混合后的物料冷却至金属锂凝固，并进行固液分离，得到补锂材料。
  9. 根据权利要求8的方法，其中，所述金属锂与所述导电材料的重量比为100：(0.1-3)，优选为100：(0.5-1)。
  10. 根据权利要求8的方法，其中，所述第一分散液中还含有表面活性剂；所述表面活性剂选自聚乙烯吡咯烷酮、十二烷基苯磺酸钠和十六烷基三甲基溴化胺的至少一种，优选为聚乙烯吡咯烷酮。
  11. 根据权利要求10的方法，其中，所述金属锂和所述表面活性剂的重量比为1：(0.002-0.05)，优选为1：(0.005-0.02)。
  12. 根据权利要求8的方法，其中，所述第一分散液和所述第二分散液的分散介质为惰性有机溶剂，所述第一分散液和所述第二分散液的分散介质各自独立地选自烃、酯、醚和硅油的至少一种。
  13. 根据权利要求8的方法，其中，所述第一分散液和所述第二分散液的体积比为1：(0.1-10)，优选为1：(0.5-3)。
  14. 根据权利要求8-13中任意一项所述的方法，其中，该方法还包括：步骤S1中，待所述第一分散液和所述第二分散液混合后通入二氧化碳。
  15. 一种锂离子电池，其特征在于，所述锂离子电池的负极包括集流体、负极活性材料和根据权利要求1-7中任意一项所述的补锂材料。
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