WO2019227598A1 - Negative electrode material, negative electrode and preparation method therefor - Google Patents

Negative electrode material, negative electrode and preparation method therefor Download PDF

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WO2019227598A1
WO2019227598A1 PCT/CN2018/094755 CN2018094755W WO2019227598A1 WO 2019227598 A1 WO2019227598 A1 WO 2019227598A1 CN 2018094755 W CN2018094755 W CN 2018094755W WO 2019227598 A1 WO2019227598 A1 WO 2019227598A1
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porous carbon
negative electrode
tin dioxide
tin
nitrogen
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PCT/CN2018/094755
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French (fr)
Chinese (zh)
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洪晔
胡倩倩
毛文峰
长世勇
董海勇
吴春宇
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广州汽车集团股份有限公司
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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
    • H01M4/13—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
    • H01M4/133—Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1391—Processes of manufacture of 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
    • H01M4/139—Processes of manufacture
    • H01M4/1393—Processes of manufacture of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • 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
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • 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
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/96—Carbon-based 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
    • 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
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the invention relates to the technical field of batteries, in particular to a negative electrode material, a negative electrode and a method for preparing the negative electrode.
  • Lithium-ion battery as a secondary battery, mainly works by moving lithium ions between the positive and negative electrodes. It has been widely used in energy storage due to its advantages such as high energy, long life, low cost, strong adaptability, and environmental protection. Power systems, power tools, portable appliances, military equipment, aerospace and other fields.
  • Lithium-ion battery negative electrode is an important part of lithium-ion battery. Its structure and performance directly affect the capacity and cycle performance of lithium-ion battery.
  • graphite-based materials are commonly used as anodes in existing lithium-ion batteries.
  • the theoretical specific capacity of graphite-based materials is only 372 mAh / g, it is difficult to meet the development needs of high-specific-energy lithium-ion batteries, so it is urgent to develop a new High specific capacity lithium ion battery anode material.
  • tin dioxide SnO 2
  • the source is wide, the cost is low, and the safety is good. Therefore, the use of tin dioxide as a negative electrode material for lithium ion batteries has obvious advantages.
  • tin dioxide is accompanied by a huge volume expansion during the cycle (its volume expansion is greater than> 300%), it is easy to cause the electrode to be powdered and peeled off, resulting in lower actual capacity of the lithium-ion battery and better cycle stability. difference.
  • the object of the present invention is to provide a negative electrode material, a negative electrode, and a method for preparing a negative electrode, so as to solve the technical problems of low specific capacity and poor cycle stability of the existing lithium ion battery, thereby improving the specific capacity and cycle stability of the lithium ion battery.
  • the present invention provides a negative electrode material including a nitrogen-doped carbon coating layer, porous carbon, and tin dioxide, the tin dioxide is attached to the porous carbon, and the nitrogen-doped carbon package
  • the coating layer covers the tin dioxide and the porous carbon.
  • the thickness of the nitrogen-doped carbon coating layer is 1 to 5 nm.
  • the particle diameter of the tin dioxide is 2-6 nm.
  • the nitrogen-doped carbon coating layer is formed by carbonizing polyacrylonitrile.
  • the present invention further provides a negative electrode including a copper foil and the above-mentioned negative electrode material, wherein the negative electrode material is attached to the copper foil.
  • the porous carbon matrix can provide a three-dimensional support carrier for tin dioxide nanoparticles, thereby alleviating the volume expansion accompanying tin dioxide during the charge and discharge process, thereby improving lithium The cycling stability of the ion battery; at the same time, the surface of the anode material has a nitrogen-doped carbon coating layer, which suppresses side reactions between tin dioxide and the electrolyte, and improves the overall conductivity of the electrode, thereby improving the lithium ion battery's Specific capacity.
  • the present invention also provides a method for preparing a negative electrode, including steps:
  • porous carbon is subjected to a hydrolysis reaction with a tin-containing chloride salt to obtain a tin dioxide / porous carbon composite powder;
  • the pole pieces after the drying treatment are subjected to carbonization heat treatment under preset carbonization heat treatment conditions to obtain a nitrogen-doped carbon / tin dioxide / porous carbon composite anode, thereby completing the preparation of the anode.
  • the step of hydrolyzing a porous carbon with a tin-containing chloride salt to obtain a tin dioxide / porous carbon composite powder includes the following steps:
  • the tin dioxide / porous carbon solution is subjected to suction filtration, washing, and drying treatment to obtain a tin dioxide / porous carbon composite powder.
  • the volume ratio of the organic solvent and water is 1: 3 to 3: 1.
  • the organic solvent is any one of absolute ethanol, ethylene glycol, methanol, and propanol.
  • a mass ratio of the porous carbon and the tin-containing chloride salt is 1:10 to 1:20.
  • the tin-containing chloride salt is tin dichloride monohydrate.
  • the preset reaction conditions specifically include: a reaction temperature of 70 to 90 ° C. and a reaction time of 0.5 to 2 h.
  • the mixing the tin dioxide / porous carbon composite powder with polyacrylonitrile to obtain a slurry is specifically:
  • the tin dioxide / porous carbon composite powder and the polyacrylonitrile powder are mixed with a dimethylformamide solvent under stirring to obtain the slurry.
  • a mass ratio of the tin dioxide / porous carbon composite powder and the polyacrylonitrile is 4: 1 to 9: 1.
  • the inert gas is nitrogen or argon.
  • the preset carbonization heat treatment conditions specifically include: a heating rate of 2 to 10 ° C./min, a heat treatment temperature of 200 to 500 ° C., and a holding time of 0.5 to 1 h.
  • the invention provides a method for preparing a negative electrode.
  • the tin-containing chloride salt By performing a hydrolysis reaction between a porous carbon and a tin-containing chloride salt, the tin-containing chloride salt generates in-situ uniformly distributed tin dioxide nanoparticles on the porous carbon substrate to obtain tin dioxide / Porous carbon composite powder, so as to realize the organic combination of tin dioxide and porous carbon.
  • the nano-sized tin dioxide produced is conducive to the electrochemical activity, and the porous carbon has a unique multi-stage pore structure, which is the tin dioxide in the cycle.
  • the volume expansion during the process provides a buffer space, thereby improving the cycle stability; then, the obtained tin dioxide / porous carbon composite powder is mixed with polyacrylonitrile to obtain a slurry; and then the slurry is obtained Coated on copper foil to obtain pole pieces; finally, in an inert gas atmosphere, the pole pieces after the drying treatment were subjected to carbonization heat treatment under preset carbonization heat treatment conditions to obtain nitrogen-doped carbon / tin dioxide / porous carbon
  • the composite negative electrode is used to complete the preparation of the negative electrode; carbonized polyacrylonitrile is carbonized to form a nitrogen-doped carbon coating layer by performing carbonization heat treatment on the pole piece after drying.
  • the cladding layer forms a protective layer on the surface of tin dioxide, which suppresses the side reaction between tin dioxide and the electrolyte, and because the nitrogen-doped carbon cladding layer itself has high conductivity, it accelerates the rapid transport of electrons, thereby effectively
  • the conductivity of the negative electrode is improved, so when the negative electrode prepared by the above method is used as the negative electrode of a lithium ion battery, the specific capacity and cycle stability of the lithium ion battery can be improved.
  • the preparation of the negative electrode is combined with the preparation of the composite material, so that the polyacrylonitrile is used as an organic carbon source of the nitrogen-doped carbon coating layer and also as a binder, so , Simplifying the preparation process of the negative electrode.
  • FIG. 1 is a transmission electron microscope photograph of a negative electrode material in an embodiment of the present invention.
  • FIG. 2 is a flowchart of a method for preparing a negative electrode in an embodiment of the present invention
  • FIG. 3 is a flowchart of a method for preparing a tin dioxide / porous carbon composite powder according to an embodiment of the present invention
  • Example 4 is an X-ray diffraction pattern of a nitrogen-doped carbon / tin dioxide / porous carbon composite powder in Example 1 of the present invention
  • FIG. 5 is a cycle performance diagram of a nitrogen-doped carbon / tin dioxide / porous carbon composite anode under different current densities in Embodiment 1 of the present invention
  • Example 6 is a cycle performance diagram of a nitrogen-doped carbon / tin dioxide / porous carbon composite anode at a current density of 1A / g in Example 1 of the present invention
  • FIG. 7 is a cycle performance diagram of the nitrogen-doped carbon / tin dioxide / porous carbon composite negative electrode in Example 1 of the present invention and Comparative Examples 7-9 at a current density of 0.1 A / g.
  • a negative electrode material includes a nitrogen-doped carbon coating layer, porous carbon, and tin dioxide.
  • the tin dioxide is attached to the porous carbon, and the nitrogen is doped.
  • the heterocarbon coating layer encapsulates the tin dioxide and the porous carbon.
  • the nitrogen-doped carbon coating layer is formed by carbonizing polyacrylonitrile.
  • the thickness of the nitrogen-doped carbon coating layer is 1 to 5 nm, and the particle diameter of the tin dioxide is 2 to 6 nm.
  • particle size can be used to characterize the size of the particles.
  • the porous carbon material includes micropores, mesopores, and macropores, wherein the pore diameter of the micropores is 1 to 2 nm, the pore diameter of the mesopores is 2 to 5 nm, and the macropores
  • the pore diameter is 20-100 nm; the specific surface area of the porous carbon is 820 m 2 / g, and the pore volume is 0.75 cm 3 / g.
  • the porous carbon matrix when the negative electrode material is used as a negative electrode of a lithium ion battery, can provide a three-dimensional support carrier for tin dioxide nanoparticles, thereby alleviating the volume expansion accompanying tin dioxide during the charge and discharge process. , which further improves the cycle stability of lithium ion batteries; at the same time, the surface of the anode material has a nitrogen-doped carbon coating layer, which suppresses side reactions between tin dioxide and the electrolyte, and improves the overall conductivity of the electrode, thereby improving The specific capacity of the lithium-ion battery.
  • the present invention further provides a negative electrode including a copper foil and the above-mentioned negative electrode material, wherein the negative electrode material is attached to the copper foil.
  • the foregoing negative electrode may be prepared according to the preparation method shown in FIG. 2, including steps:
  • the slurry is coated on a copper foil to obtain a pole piece;
  • step S1 the porous carbon is subjected to a hydrolysis reaction with a tin-containing chloride salt to obtain a tin dioxide / porous carbon composite powder, including the steps:
  • the tin dioxide / porous carbon solution is subjected to suction filtration, washing, and drying treatment to obtain a tin dioxide / porous carbon composite powder.
  • step S11 the porous carbon powder is dispersed in a mixed solution of an organic solvent and water by ultrasonic action; wherein the mixed solution of the organic solvent and water is 300-500 ml; the organic solvent used may be absolute ethanol, Any one of ethylene glycol, methanol, and propanol, and the volume ratio of the organic solvent and water is 1: 3 to 3: 1.
  • step S12 1 to 2 ml of concentrated hydrochloric acid is added to the dispersion liquid of the porous carbon powder obtained in step S11, and the mixture is stirred and mixed.
  • step S13 while vigorously stirring the dispersion of the porous carbon powder and concentrated hydrochloric acid, a tin-containing chloride salt is added, and a hydrolysis reaction is performed under preset reaction conditions to obtain a tin dioxide / porous carbon solution;
  • the vigorous stirring is to make the porous carbon in the dispersion of the porous carbon powder fully contact the tin-containing chloride salt, which is beneficial to the uniform adhesion of tin dioxide to the porous carbon;
  • the mass ratio of the tin chloride salt is 1:10 to 1:20, and the tin chloride salt is tin dichloride monohydrate;
  • the preset reaction conditions include: a reaction temperature of 70 to 90 ° C and a reaction time of 0.5 ⁇ 2h.
  • step S14 after the temperature of the tin dioxide / porous carbon solution obtained in step S13 is reduced to room temperature, the tin dioxide / porous carbon solution is suction filtered, washed thoroughly with deionized water, and then dried. After the treatment, a tin dioxide / porous carbon composite powder was obtained.
  • the porous carbon is subjected to a hydrolysis reaction with the tin-containing chloride salt, so that the tin-containing chloride salt generates in-situ tin dioxide nanoparticles with uniform distribution on the porous carbon substrate, thereby obtaining tin dioxide / porous carbon.
  • Composite powder Compared with the traditional two-phase physical mixing (such as stirring or ball milling), the in-situ chemical method adopted in the embodiments of the present invention is more conducive to the organic combination of tin dioxide and porous carbon to ensure the dioxide. Tin can evenly adhere to porous carbon; in addition, since the hydrolysis reaction process does not involve harsh reaction conditions such as high temperature and pressure, the operation is simpler and easier to popularize.
  • step S2 the step of mixing the tin dioxide / porous carbon composite powder with polyacrylonitrile to obtain a slurry is specifically: mixing the tin dioxide / porous carbon composite powder and polyacrylonitrile powder.
  • the body and the dimethylformamide solvent were stirred and mixed to obtain a slurry.
  • the mass ratio of the tin dioxide / porous carbon composite powder and the polyacrylonitrile is 4: 1 to 9: 1.
  • step S3 applying the slurry on a copper foil to obtain a pole piece is specifically: applying the slurry on the copper foil by casting to form a uniform thin layer, Thereby, pole pieces were obtained.
  • step S4 the pole piece is dried at 60 to 100 ° C.
  • step S5 the pole pieces after the drying treatment are cut into small discs with a diameter of 12 mm, put into a tube furnace, and subjected to carbonization heat treatment under a preset carbonization heat treatment condition in an inert gas atmosphere to obtain
  • the nitrogen-doped carbon / tin dioxide / porous carbon composite anode completes the preparation of the anode.
  • the inert gas atmosphere is any one of nitrogen or argon;
  • the preset carbonization heat treatment conditions include: a heating rate of 2 to 10 ° C / min, a heat treatment temperature of 200 to 500 ° C, and a holding time of 0.5. ⁇ 1h.
  • the heat treatment temperature is 300 to 400 ° C.
  • a single substance of tin, a variety of tin-containing oxides, and tin-copper alloys may be formed during the carbonization heat treatment process.
  • the embodiment of the present invention controls the heat treatment temperature.
  • the crystallinity of tin dioxide after carbonization heat treatment is appropriately increased, which is conducive to the development of its electrochemical performance; however, when the heat treatment temperature is further increased, the obtained anode may have a heterogeneous phase and the carbonization heat treatment
  • the method for preparing the porous carbon powder specifically includes the following steps:
  • step S103 In a nitrogen atmosphere, raise the product obtained in step S102 to 800 ° C at a rate of 2 ° C / min, and maintain the temperature for 2 hours, and then naturally lower the temperature to room temperature;
  • step S104 Soak the product obtained in step S103 with a 1 mol / L hydrochloric acid solution for 36 hours, and after filtering treatment, dry at 60 ° C for 36 hours; and then continue drying at 150 ° C for 8 hours to obtain a porous carbon material.
  • the related TEM photos show that the obtained porous carbon material exhibits a porous structure.
  • a BET test is performed on the obtained porous carbon, and the results of the BET test indicate that the porous carbon material includes micropores, mesopores, and macropores, wherein the pore diameter of the micropores is 1 to 2 nm, and the pore diameter of the mesopores It is 2 to 5 nm, and the pores have a pore diameter of 20 to 100 nm.
  • the specific surface area of the porous carbon is 820 m 2 / g, and the pore volume is 0.75 cm 3 / g.
  • the method for preparing the negative electrode is performed by subjecting porous carbon to a tin-containing chloride salt to hydrolyze the tin-containing salt on the porous carbon substrate to generate tin dioxide nanoparticles with uniform distribution in situ.
  • Tin dioxide / porous carbon composite powder so as to realize the organic combination of tin dioxide and porous carbon, the nano-sized tin dioxide generated is conducive to the electrochemical activity, and the porous carbon has a unique multi-stage pore structure, which is two
  • the volume expansion of tin oxide during the cycle provides a buffer space, thereby improving the cycle stability; then, the obtained tin dioxide / porous carbon composite powder is mixed with polyacrylonitrile to obtain a slurry; and then the slurry is obtained;
  • the slurry is coated on a copper foil to obtain a pole piece; finally, the pole piece after the drying treatment is subjected to carbonization heat treatment under a preset carbonization heat treatment condition in an inert gas atmosphere to obtain nitrogen-doped carbon / dioxide
  • the tin / porous carbon composite negative electrode completes the preparation of the negative electrode; the carbonized polyacrylonitrile is formed into a nitrogen-doped carbon coating layer by performing carbonization heat treatment on the dried electrode sheet.
  • the nitrogen-doped carbon coating layer forms a protective layer on the surface of tin dioxide, which suppresses the side reaction between tin dioxide and the electrolyte, and because the nitrogen-doped carbon coating layer itself has high conductivity, it speeds up the rapid transport of electrons. Therefore, the conductivity of the negative electrode is effectively improved. Therefore, when the negative electrode prepared by the above method is used as a negative electrode of a lithium ion battery, the specific capacity and cycle stability of the lithium ion battery can be improved. In addition, during the preparation of the negative electrode, the preparation of the negative electrode is combined with the preparation of the composite material, so that the polyacrylonitrile is used as an organic carbon source of the nitrogen-doped carbon coating layer and also as a binder. , Simplifying the preparation process of the negative electrode.
  • porous carbon powder 100 mg was dispersed in a mixed solution of 200 ml of anhydrous ethanol and 200 ml of water by ultrasonication to obtain a dispersion of the porous carbon powder; and 1.5 ml of concentrated hydrochloric acid was added to the dispersion of the porous carbon powder and stirred. Homogeneous; then, under vigorous stirring, 1.2 g of tin dichloride monohydrate was added to the dispersion of the porous carbon powder and concentrated hydrochloric acid, and the temperature was raised to 80 ° C for a hydrolysis reaction for 1 hour. After the reaction was completed, tin dioxide was obtained.
  • the tin dioxide / porous carbon solution after the temperature of the tin dioxide / porous carbon solution drops to room temperature, the tin dioxide / porous carbon solution is subjected to suction filtration, and fully washed with deionized water, and then dried to obtain Tin dioxide / porous carbon composite powder; according to the mass ratio of the tin dioxide / porous carbon composite powder to polyacrylonitrile powder is 90:10, weigh the tin dioxide / porous carbon composite powder and The polyacrylonitrile powder was added to the dimethylformamide solvent and stirred to prepare a slurry with good fluidity; the slurry was coated on the copper foil by casting to form a thickness of 100 ⁇ m uniform thin layer Drying the pole pieces at 70 ° C; subsequently, performing carbonization heat treatment on the pole pieces after drying: cutting the pole pieces into small discs with a diameter of 12 mm and putting them into a tube type In the furnace, the temperature was raised to 400 ° C.
  • Example 2 in order to analyze the structure and morphology of the nitrogen-doped carbon / tin dioxide / porous carbon composite anode in Example 1, the slurry obtained in Example 1 was coated on glass. After being dried on the plate, a polyacrylonitrile / tin dioxide / porous carbon composite powder was obtained, and the polyacrylonitrile / tin dioxide / porous carbon composite powder was subjected to the same carbonization heat treatment process as in Example 1. Then, a nitrogen-doped carbon / tin dioxide / porous carbon composite powder was obtained. The obtained nitrogen-doped carbon / tin dioxide / porous carbon composite powder was characterized, and the results are shown in FIGS. 1 and 4.
  • FIG. 4 is an X-ray diffraction pattern of the nitrogen-doped carbon / tin dioxide / porous carbon composite powder in Example 1 of the present invention.
  • the nitrogen-doped carbon / dioxide The tin / porous carbon composite powder contains X-ray diffraction (X-ray diffraction) of SnO 2 crystals (tin dioxide crystals), and the diffraction peaks are broad, so the SnO 2 grain size is small;
  • Figure 1 is According to a transmission electron microscope photograph of the negative electrode material in the embodiment of the present invention, it can be seen from the transmission electron microscope photograph that the outer surface of the porous carbon substrate is uniformly adhered with tin dioxide particles having a diameter of 3-4 nm, and the nitrogen A highly graphitized carbon-coated thin layer with a thickness of about 3 nm was observed on the outer layer of the doped carbon / tin dioxide / porous carbon composite powder.
  • FIG. 5 is a cycle performance diagram of the nitrogen-doped carbon / tin dioxide / porous carbon composite anode at different current densities in Example 1 of the present invention.
  • the nitrogen-doped carbon / two When the tin oxide / porous carbon composite anode is cycled under different current densities, it can provide a higher specific capacity, and it can still be tested stably after charging and discharging at a large current;
  • Figure 6 shows nitrogen doping in Example 1 of the present invention.
  • the specific capacity is as high as 767mAh / g, and in addition to the first few cycles, the Coulomb efficiency is close to 100% throughout the cycle, showing excellent cycle stability.
  • FIG. 7 is a cycle performance diagram of the nitrogen-doped carbon / tin dioxide / porous carbon composite anode at a current density of 0.1 A / g in Example 1 of the present invention and Comparative Examples 7-9.
  • the specific capacities of the first and second discharges of the nitrogen-doped carbon / tin dioxide / porous carbon composite anode obtained in Example 1 at a current density of 0.1 A / g were 1439 mAh / g and 1067 mAh / g, respectively, after 100 times. After cycling, the specific capacity was stable at 1117 mAh / g. Therefore, when the nitrogen-doped carbon / tin dioxide / porous carbon composite negative electrode obtained in this embodiment is applied to a lithium ion battery, the specific capacity and cycle stability of the lithium ion battery can be improved.
  • Example 1 The difference between this embodiment and Example 1 is that in the mixed solution of anhydrous ethanol and water, the anhydrous ethanol is 100 ml, and the water is 300 ml; and added to the dispersion of the porous carbon powder.
  • the concentrated hydrochloric acid is 1 ml; 2 g of tin dichloride monohydrate is added to the dispersion of the porous carbon powder and the concentrated hydrochloric acid, and the temperature is increased to 90 ° C for hydrolysis reaction; The temperature was increased to 400 ° C at a temperature increase rate of 10 ° C / min in a gas atmosphere, and the temperature was maintained for 1 hour.
  • the other processes and steps of this embodiment are the same as those of Embodiment 1, and will not be described in detail here.
  • Example 1 The difference between this embodiment and Example 1 is that in the mixed solution of anhydrous ethanol and water, the anhydrous ethanol is 200 ml, and the water is 300 ml; and added to the dispersion of the porous carbon powder.
  • the concentrated hydrochloric acid is 2 ml; 1 g of tin dichloride monohydrate is added to the dispersion of the porous carbon powder and concentrated hydrochloric acid; and the weighed tin dioxide / porous carbon composite powder and polyacrylonitrile powder are weighed.
  • the mass ratio of the body was 80:20; during the carbonization heat treatment, the temperature was increased to 400 ° C at a temperature increase rate of 3 ° C / min in a nitrogen atmosphere, and the temperature was maintained for 0.5 hours.
  • the other processes and steps of this embodiment are the same as those of Embodiment 1, and will not be described in detail here.
  • Embodiment 1 The difference between this embodiment and Embodiment 1 is that during the carbonization heat treatment, the heat treatment temperature is 200 ° C.
  • the other processes and steps of this embodiment are the same as those of Embodiment 1, and will not be described in detail here.
  • Embodiment 1 The difference between this embodiment and Embodiment 1 is that during the carbonization heat treatment, the heat treatment temperature is 300 ° C.
  • the other processes and steps of this embodiment are the same as those of Embodiment 1, and will not be described in detail here.
  • Embodiment 1 The difference between this embodiment and Embodiment 1 is that during the carbonization heat treatment, the heat treatment temperature is 500 ° C.
  • the other processes and steps of this embodiment are the same as those of Embodiment 1, and will not be described in detail here.
  • the obtained negative electrode was characterized; it can be seen from the X-ray diffraction pattern that the diffraction peak of tin dioxide is weak, which indicates that the tin dioxide has poor crystallinity. It can be observed through a transmission electron microscope photograph that the amorphous carbon coating layer on the surface of tin dioxide, which does not have a high graphitization feature, thus indicating that its conductivity is poor.
  • the cycle performance of the obtained final negative electrode at a current density of 0.1 A / g is shown in FIG. 7. As can be seen from FIG.
  • This comparative example differs from Example 1 in that during the carbonization heat treatment, the heat treatment temperature is 600 ° C.
  • the other processes and steps of this comparative example are the same as those of Embodiment 1, and will not be described in detail here.
  • the obtained nitrogen-doped carbon / tin dioxide / porous carbon composite negative electrode was characterized; according to the X-ray diffraction pattern, it can be seen that the diffraction peak of tin dioxide is high and strong, which indicates that the grain size of tin dioxide is large In addition, there are some miscellaneous peaks attributed to copper-tin alloys.
  • the cycle performance of the obtained nitrogen-doped carbon / tin dioxide / porous carbon composite anode at a current density of 0.1 A / g is shown in FIG. 7. As can be seen from FIG.
  • the nitrogen-doped carbon / tin dioxide / The specific capacity of the porous carbon composite negative electrode for initial discharge is much lower than the nitrogen-doped carbon / tin dioxide / porous carbon composite negative electrode prepared in Example 1; the reason is that increasing the heat treatment temperature results in the formation of an inactive copper-tin alloy
  • the impurity phase makes the structure of the negative electrode loose, which causes the active material to easily fall off the copper foil.
  • the larger size of the tin dioxide particles exacerbates the volume expansion of tin dioxide during the charge and discharge process. Lower specific capacity.
  • This comparative example differs from Example 1 in that the comparative example uses a simple mechanical stirring method instead of the in-situ chemical method to mix porous carbon and tin dioxide.
  • the other processes and steps of this comparative example are the same as those of Embodiment 1, and will not be described in detail here.
  • This comparative example uses a simple mechanical stirring method to mix porous carbon and tin dioxide. Specifically, the mass ratio of nano-sized tin dioxide powder, porous carbon powder, and polyacrylonitrile powder is 60:30:10. Weigh the nano-sized tin dioxide powder, the porous carbon powder, and the polyacrylonitrile powder, and use a mechanical stirring method to mix the porous carbon and tin dioxide. The other process steps of this comparative example are the same as in Example 1.
  • the cycling performance of the nitrogen-doped carbon / tin dioxide / porous carbon composite anode of this comparative example at a current density of 0.1 A / g is shown in FIG. 7.
  • the nitrogen-doped carbon / tin dioxide / The initial discharge specific capacity of the porous carbon composite negative electrode is high, but its specific capacity decays significantly with the increase of the number of cycles; the reason is that it is difficult to make the tin dioxide particles adhere to the surface of the porous carbon substrate uniformly using a simple mechanical mixing method As the number of cycles increases, the tin dioxide particles tend to accumulate and agglomerate, and it is difficult to fully exert the buffering effect of the structure of porous carbon on the volume expansion of tin dioxide. Therefore, the nitrogen doped carbon / tin dioxide / porous carbon The specific capacity of the composite anode increases with the number of cycles.
  • the nitrogen-doped carbon / tin dioxide / porous carbon composite anodes prepared in Examples 2 to 6 and Comparative Examples 7 to 9 of the present invention were applied to lithium ion batteries using the same process conditions as in Example 1, and lithium ions were tested.
  • the cycling performance of the battery at a current density of 0.1 A / g is shown in Table 1.
  • Table 1 shows the cycle performance of the composite negative electrodes prepared in Examples 1 to 6 and Comparative Examples 7 to 9 at a current density of 0.1 A / g.
  • the nitrogen-doped carbon / tin dioxide / porous carbon composite anode prepared in Examples 1 to 6 of the present invention can achieve high specific capacity and good cycle stability. Sex, which is inseparable from its unique composite structure.
  • the porous carbon matrix can provide a three-dimensional support carrier for tin dioxide nanoparticles, which is beneficial to alleviate the volume expansion accompanying tin dioxide during the charge and discharge process, and improves the lithium ion battery.
  • Cycle performance and because a thin layer of nitrogen-doped carbon coating is attached to the surface of the anode material, it is beneficial to suppress the side reaction between tin dioxide and the electrolyte, thereby improving the overall conductivity of the electrode, and thus improving lithium ions.
  • the specific capacity of the battery by controlling the appropriate heat treatment temperature, the size of the tin dioxide particles in the anode material is small, and it is a single crystal phase in the anode material, thereby ensuring that the prepared anode can exhibit higher performance.
  • the present invention provides a negative electrode material, a negative electrode, and a method for preparing a negative electrode.
  • a porous carbon substrate can provide a three-dimensional support carrier for tin dioxide nanoparticles, thereby alleviating the problem. It increases the volume expansion of tin dioxide during charging and discharging, which improves the cycle stability of lithium-ion batteries.
  • the surface of the anode material has a nitrogen-doped carbon coating layer, which suppresses the relationship between tin dioxide and the electrolyte. Side reactions and improve the overall conductivity of the electrode, thereby increasing the specific capacity of the lithium-ion battery.

Abstract

The present invention relates to the technical field of lithium ion batteries, and discloses a negative electrode material, a negative electrode and a preparation method therefor, wherein the negative electrode material comprises a nitrogen-doped carbon coating layer, porous carbon and stannic dioxide, with the stannic dioxide being attached to the porous carbon; and the nitrogen-doped carbon coating layer wraps the stannic dioxide and the porous carbon. By attaching stannic dioxide to the porous carbon, the porous carbon can provide a three-dimensional support carrier for stannic dioxide nano particles, thereby alleviating the volume expansion, accompanying the charging-discharging process, of stannic dioxide, and further improving the cycle stability of the lithium ion battery; in addition, the surface of the negative electrode material is provided with a nitrogen-doped carbon coating layer, which inhibits side reactions between stannic dioxide and an electrolyte and improves the whole conductivity of the electrode, thereby improving the specific capacity of the lithium ion battery.

Description

一种负极材料、负极及负极的制备方法Negative electrode material, negative electrode and preparation method of negative electrode 技术领域Technical field
本发明涉及电池技术领域，特别是涉及一种负极材料、负极及负极的制备方法。The invention relates to the technical field of batteries, in particular to a negative electrode material, a negative electrode and a method for preparing the negative electrode.
背景技术Background technique
锂离子电池作为一种二次电池，主要依靠锂离子在正极和负极之间移动来工作，其由于具有高能量、长寿命、低成本、适应性强以及环保等优点而被广泛应用于储能电源***、电动工具、便携式电器、军事装备、航天航空等领域。Lithium-ion battery, as a secondary battery, mainly works by moving lithium ions between the positive and negative electrodes. It has been widely used in energy storage due to its advantages such as high energy, long life, low cost, strong adaptability, and environmental protection. Power systems, power tools, portable appliances, military equipment, aerospace and other fields.
锂离子电池负极作为锂离子电池的重要组成部分，其结构和性能直接影响到锂离子电池的容量和循环性能。目前，现有锂离子电池普遍采用石墨类材料作为负极，但是，由于石墨类材料的理论比容量仅为372mAh/g，难以满足高比能锂离子电池的开发需求，因此急需开发一种新的高比容量的锂离子电池负极材料。Lithium-ion battery negative electrode is an important part of lithium-ion battery. Its structure and performance directly affect the capacity and cycle performance of lithium-ion battery. At present, graphite-based materials are commonly used as anodes in existing lithium-ion batteries. However, since the theoretical specific capacity of graphite-based materials is only 372 mAh / g, it is difficult to meet the development needs of high-specific-energy lithium-ion batteries, so it is urgent to develop a new High specific capacity lithium ion battery anode material.
二氧化锡(SnO 2)的理论比容量高达1494mAh/g，并且来源广泛、成本低、安全性好，因此，采用二氧化锡作为锂离子电池负极材料具有明显的优势。但是，由于二氧化锡在循环过程中会伴随有巨大的体积膨胀(其体积膨胀大于>300％)，因此容易导致电极粉化脱落，从而导致锂离子电池的实际容量较低且循环稳定性较差。 The theoretical specific capacity of tin dioxide (SnO 2 ) is as high as 1494mAh / g, and the source is wide, the cost is low, and the safety is good. Therefore, the use of tin dioxide as a negative electrode material for lithium ion batteries has obvious advantages. However, since tin dioxide is accompanied by a huge volume expansion during the cycle (its volume expansion is greater than> 300%), it is easy to cause the electrode to be powdered and peeled off, resulting in lower actual capacity of the lithium-ion battery and better cycle stability. difference.
发明内容Summary of the Invention
本发明的目的是提供一种负极材料、负极及负极的制备方法，以解决现有锂离子电池的比容量低且循环稳定性差的技术问题，从而提高锂离子电池的比容量和循环稳定性。The object of the present invention is to provide a negative electrode material, a negative electrode, and a method for preparing a negative electrode, so as to solve the technical problems of low specific capacity and poor cycle stability of the existing lithium ion battery, thereby improving the specific capacity and cycle stability of the lithium ion battery.
为了解决上述技术问题，本发明提供一种负极材料，包括氮掺杂碳包覆层、多孔碳以及二氧化锡，所述二氧化锡附着于所述多孔碳上，所述氮掺杂碳包覆层包裹所述二氧化锡和所述多孔碳。In order to solve the above technical problem, the present invention provides a negative electrode material including a nitrogen-doped carbon coating layer, porous carbon, and tin dioxide, the tin dioxide is attached to the porous carbon, and the nitrogen-doped carbon package The coating layer covers the tin dioxide and the porous carbon.
作为优选方案，所述氮掺杂碳包覆层的厚度为1～5nm。As a preferred solution, the thickness of the nitrogen-doped carbon coating layer is 1 to 5 nm.
作为优选方案，所述二氧化锡的粒径为2～6nm。As a preferred solution, the particle diameter of the tin dioxide is 2-6 nm.
作为优选方案，所述氮掺杂碳包覆层由聚丙烯腈碳化形成。As a preferred solution, the nitrogen-doped carbon coating layer is formed by carbonizing polyacrylonitrile.
为了解决相同的技术问题，本发明还提供一种负极，包括铜箔以及上述的负极材料，所述负极材料附于所述铜箔上。In order to solve the same technical problem, the present invention further provides a negative electrode including a copper foil and the above-mentioned negative electrode material, wherein the negative electrode material is attached to the copper foil.
本发明提供的负极材料在用作锂离子电池负极时，多孔碳基体能够为二氧化锡纳米颗粒提供三维支撑载体，从而缓解了二氧化锡在充放电过程中伴随的体积膨胀，进而提升了锂离子电池的循环稳定性；同时，负极材料的表面具有氮掺杂碳包覆层，抑制了二氧化锡与电解液间的副反应，并提高了电极整体导电性，从而提高了锂离子电池的比容量。When the negative electrode material provided by the present invention is used as a negative electrode of a lithium ion battery, the porous carbon matrix can provide a three-dimensional support carrier for tin dioxide nanoparticles, thereby alleviating the volume expansion accompanying tin dioxide during the charge and discharge process, thereby improving lithium The cycling stability of the ion battery; at the same time, the surface of the anode material has a nitrogen-doped carbon coating layer, which suppresses side reactions between tin dioxide and the electrolyte, and improves the overall conductivity of the electrode, thereby improving the lithium ion battery's Specific capacity.
为了解决相同的技术问题，本发明还提供一种负极的制备方法，包括步骤：In order to solve the same technical problem, the present invention also provides a method for preparing a negative electrode, including steps:
将多孔碳与含锡氯盐进行水解反应，得到二氧化锡/多孔碳复合粉体；The porous carbon is subjected to a hydrolysis reaction with a tin-containing chloride salt to obtain a tin dioxide / porous carbon composite powder;
将所述二氧化锡/多孔碳复合粉体与聚丙烯腈进行混合，得到浆料；Mixing the tin dioxide / porous carbon composite powder with polyacrylonitrile to obtain a slurry;
将所述浆料涂覆在铜箔上，得到极片；Coating the slurry on a copper foil to obtain a pole piece;
将所述极片进行干燥处理；Drying the pole piece;
在惰性气体气氛中，将干燥处理后的所述极片以预设的碳化热处理条件进行碳化热处理，得到氮掺杂碳/二氧化锡/多孔碳复合负极，完成负极的制备。In an inert gas atmosphere, the pole pieces after the drying treatment are subjected to carbonization heat treatment under preset carbonization heat treatment conditions to obtain a nitrogen-doped carbon / tin dioxide / porous carbon composite anode, thereby completing the preparation of the anode.
作为优选方案，所述将多孔碳与含锡氯盐进行水解反应，得到二氧化锡/多孔碳复合粉体，包括步骤：As a preferred solution, the step of hydrolyzing a porous carbon with a tin-containing chloride salt to obtain a tin dioxide / porous carbon composite powder includes the following steps:
将多孔碳粉体分散在有机溶剂和水的混合溶液中，得到多孔碳粉体的分散液；Dispersing the porous carbon powder in a mixed solution of an organic solvent and water to obtain a dispersion liquid of the porous carbon powder;
将所述多孔碳粉体的分散液与浓盐酸进行搅拌混合；Stirring and mixing the dispersion of the porous carbon powder with concentrated hydrochloric acid;
将搅拌混合后的所述多孔碳粉体的分散液和浓盐酸与含锡氯盐以预设的反应条件进行水解反应，得到二氧化锡/多孔碳溶液；Performing the hydrolysis reaction of the porous carbon powder dispersion and concentrated hydrochloric acid and the tin-containing chloride salt after the mixing and mixing under a preset reaction condition to obtain a tin dioxide / porous carbon solution;
将所述二氧化锡/多孔碳溶液进行抽滤、洗涤、干燥处理，得到二氧化锡/多孔碳复合粉体。The tin dioxide / porous carbon solution is subjected to suction filtration, washing, and drying treatment to obtain a tin dioxide / porous carbon composite powder.
作为优选方案，所述有机溶剂和水的体积比为1:3～3:1。As a preferred solution, the volume ratio of the organic solvent and water is 1: 3 to 3: 1.
作为优选方案，所述有机溶剂为无水乙醇、乙二醇、甲醇、丙醇中的任一种。As a preferred solution, the organic solvent is any one of absolute ethanol, ethylene glycol, methanol, and propanol.
作为优选方案，所述多孔碳和所述含锡氯盐的质量比为1:10～1:20。As a preferred solution, a mass ratio of the porous carbon and the tin-containing chloride salt is 1:10 to 1:20.
作为优选方案，所述含锡氯盐为一水合二氯化锡。As a preferred solution, the tin-containing chloride salt is tin dichloride monohydrate.
作为优选方案，所述预设的反应条件具体包括：反应温度为70～90℃，反应时间为0.5～2h。As a preferred solution, the preset reaction conditions specifically include: a reaction temperature of 70 to 90 ° C. and a reaction time of 0.5 to 2 h.
作为优选方案，所述将所述二氧化锡/多孔碳复合粉体与聚丙烯腈进行混合，得到浆料，具体为：As a preferred solution, the mixing the tin dioxide / porous carbon composite powder with polyacrylonitrile to obtain a slurry is specifically:
将所述二氧化锡/多孔碳复合粉体和聚丙烯腈粉体与二甲基甲酰胺溶剂进行搅拌混合，得到所述浆料。The tin dioxide / porous carbon composite powder and the polyacrylonitrile powder are mixed with a dimethylformamide solvent under stirring to obtain the slurry.
作为优选方案，所述二氧化锡/多孔碳复合粉体和所述聚丙烯腈的质量比为4:1～9:1。As a preferred solution, a mass ratio of the tin dioxide / porous carbon composite powder and the polyacrylonitrile is 4: 1 to 9: 1.
作为优选方案，所述惰性气体为氮气或氩气。As a preferred solution, the inert gas is nitrogen or argon.
作为优选方案，所述预设的碳化热处理条件具体包括：升温速率为2～10℃/min，热处理温度为200～500℃，保温时间为0.5～1h。As a preferred solution, the preset carbonization heat treatment conditions specifically include: a heating rate of 2 to 10 ° C./min, a heat treatment temperature of 200 to 500 ° C., and a holding time of 0.5 to 1 h.
本发明提供一种负极的制备方法，通过将多孔碳与含锡氯盐进行水解反应，使得含锡氯盐在多孔碳基体上原位生成分布均匀的二氧化锡纳米颗粒，得到二氧化锡/多孔碳复合粉体，从而实现了二氧化锡和多孔碳的有机结合，生成的纳米级二氧化锡有利于发挥电化学活性，且多孔碳具有独特的多级孔结构，为二氧化锡在循环过程中的体积膨胀提供了缓冲空间，从而改善了循环稳定性；然后通过将得到的所述二氧化锡/多孔碳复合粉体与聚丙烯腈进行混合，得到浆料；再将所述浆料涂覆在铜箔上，得到极片；最后在惰性气体气氛中，将干燥处理后的所述极片以预设的碳化热处理条件进行碳化热处理，得到氮掺杂碳/二氧化锡/多孔碳复合负极，完成负极的制备；通过对干燥后的所述极片进行碳化热处理，使得聚丙烯腈碳化形成氮掺杂碳包覆层，所述氮掺杂碳包覆层在二氧化锡表面形成保护层，抑制了二氧化锡与电解液间的副反应，且由于氮掺杂碳包覆层自身具有高导电性，加快了电子的快速传输，从而有效地提高了负极的导电性，因此当将采用上述方法制备的负极用作锂离子电池的负极时，能够提高锂离子电池的比容量和循环稳定性。此外，在负极制备的过程中，将负极的制备与复合材料的制备结合起来，使得聚丙烯腈在用作氮掺杂碳包覆层的有机碳源的同时，也用作粘结剂，因此， 简化了负极的制备工序。The invention provides a method for preparing a negative electrode. By performing a hydrolysis reaction between a porous carbon and a tin-containing chloride salt, the tin-containing chloride salt generates in-situ uniformly distributed tin dioxide nanoparticles on the porous carbon substrate to obtain tin dioxide / Porous carbon composite powder, so as to realize the organic combination of tin dioxide and porous carbon. The nano-sized tin dioxide produced is conducive to the electrochemical activity, and the porous carbon has a unique multi-stage pore structure, which is the tin dioxide in the cycle. The volume expansion during the process provides a buffer space, thereby improving the cycle stability; then, the obtained tin dioxide / porous carbon composite powder is mixed with polyacrylonitrile to obtain a slurry; and then the slurry is obtained Coated on copper foil to obtain pole pieces; finally, in an inert gas atmosphere, the pole pieces after the drying treatment were subjected to carbonization heat treatment under preset carbonization heat treatment conditions to obtain nitrogen-doped carbon / tin dioxide / porous carbon The composite negative electrode is used to complete the preparation of the negative electrode; carbonized polyacrylonitrile is carbonized to form a nitrogen-doped carbon coating layer by performing carbonization heat treatment on the pole piece after drying. The cladding layer forms a protective layer on the surface of tin dioxide, which suppresses the side reaction between tin dioxide and the electrolyte, and because the nitrogen-doped carbon cladding layer itself has high conductivity, it accelerates the rapid transport of electrons, thereby effectively The conductivity of the negative electrode is improved, so when the negative electrode prepared by the above method is used as the negative electrode of a lithium ion battery, the specific capacity and cycle stability of the lithium ion battery can be improved. In addition, during the preparation of the negative electrode, the preparation of the negative electrode is combined with the preparation of the composite material, so that the polyacrylonitrile is used as an organic carbon source of the nitrogen-doped carbon coating layer and also as a binder, so , Simplifying the preparation process of the negative electrode.
附图说明BRIEF DESCRIPTION OF THE DRAWINGS
图1是本发明实施例中的负极材料的透射电子显微镜照片；1 is a transmission electron microscope photograph of a negative electrode material in an embodiment of the present invention;
图2是本发明实施例中的负极的制备方法的流程图；2 is a flowchart of a method for preparing a negative electrode in an embodiment of the present invention;
图3是本发明实施例中的二氧化锡/多孔碳复合粉体的制备方法的流程图；3 is a flowchart of a method for preparing a tin dioxide / porous carbon composite powder according to an embodiment of the present invention;
图4是本发明实施例1中的氮掺杂碳/二氧化锡/多孔碳复合粉体的X射线衍射图谱；4 is an X-ray diffraction pattern of a nitrogen-doped carbon / tin dioxide / porous carbon composite powder in Example 1 of the present invention;
图5是本发明实施例1中的氮掺杂碳/二氧化锡/多孔碳复合负极在不同电流密度下的循环性能图；5 is a cycle performance diagram of a nitrogen-doped carbon / tin dioxide / porous carbon composite anode under different current densities in Embodiment 1 of the present invention;
图6是本发明实施例1中的氮掺杂碳/二氧化锡/多孔碳复合负极在1A/g电流密度下的循环性能图；6 is a cycle performance diagram of a nitrogen-doped carbon / tin dioxide / porous carbon composite anode at a current density of 1A / g in Example 1 of the present invention;
图7是本发明实施例1以及对比例7～9中的氮掺杂碳/二氧化锡/多孔碳复合负极在0.1A/g电流密度下的循环性能图。FIG. 7 is a cycle performance diagram of the nitrogen-doped carbon / tin dioxide / porous carbon composite negative electrode in Example 1 of the present invention and Comparative Examples 7-9 at a current density of 0.1 A / g.
具体实施方式Detailed ways
下面结合附图和实施例，对本发明的具体实施方式作进一步详细描述。以下实施例用于说明本发明，但不用来限制本发明的范围。The specific embodiments of the present invention are described in further detail below with reference to the drawings and embodiments. The following examples are used to illustrate the present invention, but not to limit the scope of the present invention.
如图1所示，本发明优选实施例的一种负极材料，包括氮掺杂碳包覆层、多孔碳以及二氧化锡，所述二氧化锡附着于所述多孔碳上，所述氮掺杂碳包覆层包裹所述二氧化锡和所述多孔碳。其中，所述氮掺杂碳包覆层由聚丙烯腈碳化形成。As shown in FIG. 1, a negative electrode material according to a preferred embodiment of the present invention includes a nitrogen-doped carbon coating layer, porous carbon, and tin dioxide. The tin dioxide is attached to the porous carbon, and the nitrogen is doped. The heterocarbon coating layer encapsulates the tin dioxide and the porous carbon. Wherein, the nitrogen-doped carbon coating layer is formed by carbonizing polyacrylonitrile.
在本发明实施例中，所述氮掺杂碳包覆层的厚度为1～5nm；所述二氧化锡的粒径为2～6nm。如本领域技术人员所知道的，“粒径”可用来表征颗粒的大小。In the embodiment of the present invention, the thickness of the nitrogen-doped carbon coating layer is 1 to 5 nm, and the particle diameter of the tin dioxide is 2 to 6 nm. As known to those skilled in the art, "particle size" can be used to characterize the size of the particles.
在本发明实施例中，所述多孔碳材料包括微孔、介孔和大孔，其中，所述微孔的孔径为1～2nm，所述介孔的孔径为2～5nm，所述大孔的孔径为20～100nm；所述多孔碳的比表面积为820m 2/g，孔体积为0.75cm 3/g。 In an embodiment of the present invention, the porous carbon material includes micropores, mesopores, and macropores, wherein the pore diameter of the micropores is 1 to 2 nm, the pore diameter of the mesopores is 2 to 5 nm, and the macropores The pore diameter is 20-100 nm; the specific surface area of the porous carbon is 820 m 2 / g, and the pore volume is 0.75 cm 3 / g.
在本发明实施例中，所述负极材料在用作锂离子电池负极时，多孔碳基体能够为二氧化锡纳米颗粒提供三维支撑载体，从而缓解了二氧化锡在充放电过程中伴随的体积膨胀，进而提升了锂离子电池的循环稳定性；同时，负极材料的表面 具有氮掺杂碳包覆层，抑制了二氧化锡与电解液间的副反应，并提高了电极整体导电性，从而提高了锂离子电池的比容量。In the embodiment of the present invention, when the negative electrode material is used as a negative electrode of a lithium ion battery, the porous carbon matrix can provide a three-dimensional support carrier for tin dioxide nanoparticles, thereby alleviating the volume expansion accompanying tin dioxide during the charge and discharge process. , Which further improves the cycle stability of lithium ion batteries; at the same time, the surface of the anode material has a nitrogen-doped carbon coating layer, which suppresses side reactions between tin dioxide and the electrolyte, and improves the overall conductivity of the electrode, thereby improving The specific capacity of the lithium-ion battery.
为了解决相同的技术问题，本发明还提供一种负极，包括铜箔以及上述的负极材料，所述负极材料附于所述铜箔上。In order to solve the same technical problem, the present invention further provides a negative electrode including a copper foil and the above-mentioned negative electrode material, wherein the negative electrode material is attached to the copper foil.
在本发明实施例中，可根据如图2所示的制备方法制备上述的负极，包括步骤：In the embodiment of the present invention, the foregoing negative electrode may be prepared according to the preparation method shown in FIG. 2, including steps:
S1、将多孔碳与含锡氯盐进行水解反应，得到二氧化锡/多孔碳复合粉体；S1. Hydrolyzing a porous carbon with a tin-containing chloride salt to obtain a tin dioxide / porous carbon composite powder;
S2、将所述二氧化锡/多孔碳复合粉体与聚丙烯腈进行混合，得到浆料；S2: mixing the tin dioxide / porous carbon composite powder with polyacrylonitrile to obtain a slurry;
S3、将所述浆料涂覆在铜箔上，得到极片；S3. The slurry is coated on a copper foil to obtain a pole piece;
S4、将所述极片进行干燥处理；S4. Dry the pole pieces;
S5、在惰性气体气氛中，将干燥处理后的所述极片以预设的碳化热处理条件进行碳化热处理，得到氮掺杂碳/二氧化锡/多孔碳复合负极，完成负极的制备。S5. Carry out a carbonization heat treatment of the pole pieces after the drying treatment in a preset carbonization heat treatment condition in an inert gas atmosphere to obtain a nitrogen-doped carbon / tin dioxide / porous carbon composite anode to complete the preparation of the anode.
如图3所示，在步骤S1中，所述将多孔碳与含锡氯盐进行水解反应，得到二氧化锡/多孔碳复合粉体，包括步骤：As shown in FIG. 3, in step S1, the porous carbon is subjected to a hydrolysis reaction with a tin-containing chloride salt to obtain a tin dioxide / porous carbon composite powder, including the steps:
S11、将多孔碳粉体分散在有机溶剂和水的混合溶液中，得到多孔碳粉体的分散液；S11. Disperse the porous carbon powder in a mixed solution of an organic solvent and water to obtain a dispersion liquid of the porous carbon powder;
S12、将所述多孔碳粉体的分散液与浓盐酸进行搅拌混合；S12. Stir and mix the dispersion of the porous carbon powder with concentrated hydrochloric acid;
S13、将搅拌混合后的所述多孔碳粉体的分散液和浓盐酸与含锡氯盐以预设的反应条件进行水解反应，得到二氧化锡/多孔碳溶液；S13. The dispersion solution of the porous carbon powder and the concentrated hydrochloric acid and the tin-containing chloride salt are subjected to a hydrolysis reaction under predetermined reaction conditions after stirring and mixing to obtain a tin dioxide / porous carbon solution;
S14、将所述二氧化锡/多孔碳溶液进行抽滤、洗涤、干燥处理，得到二氧化锡/多孔碳复合粉体。S14. The tin dioxide / porous carbon solution is subjected to suction filtration, washing, and drying treatment to obtain a tin dioxide / porous carbon composite powder.
在步骤S11中，通过超声作用将多孔碳粉体分散在有机溶剂和水的混合溶液中；其中，所述机溶剂和水的混合溶液为300～500ml；使用的有机溶剂可以是无水乙醇、乙二醇、甲醇、丙醇中的任意一种，且所述有机溶剂和水的体积比为1:3～3:1。In step S11, the porous carbon powder is dispersed in a mixed solution of an organic solvent and water by ultrasonic action; wherein the mixed solution of the organic solvent and water is 300-500 ml; the organic solvent used may be absolute ethanol, Any one of ethylene glycol, methanol, and propanol, and the volume ratio of the organic solvent and water is 1: 3 to 3: 1.
在步骤S12中，在步骤S11获得的所述多孔碳粉体的分散液中，加入1～2ml浓盐酸进行搅拌混合。In step S12, 1 to 2 ml of concentrated hydrochloric acid is added to the dispersion liquid of the porous carbon powder obtained in step S11, and the mixture is stirred and mixed.
在步骤S13中，在剧烈搅拌所述多孔碳粉体的分散液和浓盐酸的情况下，加入含锡氯盐，并以预设的反应条件进行水解反应，得到二氧化锡/多孔碳溶液；其中，剧烈搅拌是为了使所述多孔碳粉体的分散液中的多孔碳与含锡氯盐充分接触，有利于二氧化锡均匀附着于多孔碳上；所述多孔碳粉体和所述含锡氯盐的质量比为1:10～1:20，所述含锡氯盐为一水合二氯化锡；所述预设的反应条件包括：反应温度为70～90℃，反应时间为0.5～2h。In step S13, while vigorously stirring the dispersion of the porous carbon powder and concentrated hydrochloric acid, a tin-containing chloride salt is added, and a hydrolysis reaction is performed under preset reaction conditions to obtain a tin dioxide / porous carbon solution; The vigorous stirring is to make the porous carbon in the dispersion of the porous carbon powder fully contact the tin-containing chloride salt, which is beneficial to the uniform adhesion of tin dioxide to the porous carbon; the porous carbon powder and the The mass ratio of the tin chloride salt is 1:10 to 1:20, and the tin chloride salt is tin dichloride monohydrate; the preset reaction conditions include: a reaction temperature of 70 to 90 ° C and a reaction time of 0.5 ~ 2h.
在步骤S14中，待步骤S13得到的所述二氧化锡/多孔碳溶液的温度降至室温后，将所述二氧化锡/多孔碳溶液进行抽滤，并用去离子水充分洗涤，再经干燥处理后，得到二氧化锡/多孔碳复合粉体。In step S14, after the temperature of the tin dioxide / porous carbon solution obtained in step S13 is reduced to room temperature, the tin dioxide / porous carbon solution is suction filtered, washed thoroughly with deionized water, and then dried. After the treatment, a tin dioxide / porous carbon composite powder was obtained.
在本发明实施例中，通过将多孔碳与含锡氯盐进行水解反应，使得含锡氯盐在多孔碳基体上原位生成分布均匀的二氧化锡纳米颗粒，从而得到二氧化锡/多孔碳复合粉体，这与传统的两相物理混合(如搅拌或球磨等)相比，本发明实施例采用的原位化学法更有利于实现二氧化锡和多孔碳的有机结合，以确保二氧化锡能够均匀地附着于多孔碳上；此外，由于水解反应的过程不涉及高温高压等苛刻的反应条件，操作更简便，且易推广。In the embodiment of the present invention, the porous carbon is subjected to a hydrolysis reaction with the tin-containing chloride salt, so that the tin-containing chloride salt generates in-situ tin dioxide nanoparticles with uniform distribution on the porous carbon substrate, thereby obtaining tin dioxide / porous carbon. Composite powder. Compared with the traditional two-phase physical mixing (such as stirring or ball milling), the in-situ chemical method adopted in the embodiments of the present invention is more conducive to the organic combination of tin dioxide and porous carbon to ensure the dioxide. Tin can evenly adhere to porous carbon; in addition, since the hydrolysis reaction process does not involve harsh reaction conditions such as high temperature and pressure, the operation is simpler and easier to popularize.
在步骤S2中，所述将所述二氧化锡/多孔碳复合粉体与聚丙烯腈进行混合，得到浆料，具体为：将所述二氧化锡/多孔碳复合粉体和聚丙烯腈粉体与二甲基甲酰胺溶剂进行搅拌混合，得到浆料。其中，所述二氧化锡/多孔碳复合粉体和所述聚丙烯腈的质量比为4:1～9:1。In step S2, the step of mixing the tin dioxide / porous carbon composite powder with polyacrylonitrile to obtain a slurry is specifically: mixing the tin dioxide / porous carbon composite powder and polyacrylonitrile powder. The body and the dimethylformamide solvent were stirred and mixed to obtain a slurry. Wherein, the mass ratio of the tin dioxide / porous carbon composite powder and the polyacrylonitrile is 4: 1 to 9: 1.
在步骤S3中，所述将所述浆料涂覆在铜箔上，得到极片，具体为：采用流延的方式将所述浆料涂覆在所述铜箔上，形成均匀薄层，从而得到极片。In step S3, applying the slurry on a copper foil to obtain a pole piece is specifically: applying the slurry on the copper foil by casting to form a uniform thin layer, Thereby, pole pieces were obtained.
在步骤S4中，将所述极片进行60～100℃的干燥处理。In step S4, the pole piece is dried at 60 to 100 ° C.
在步骤S5中，将干燥处理后的所述极片裁剪成直径为12mm的小圆片，放入管式炉中，并在惰性气体气氛中，以预设的碳化热处理条件进行碳化热处理，得到氮掺杂碳/二氧化锡/多孔碳复合负极，完成负极的制备。其中，所述惰性气体气氛为氮气或氩气中的任意一种；所述预设的碳化热处理条件包括：升温速率为2～10℃/min，热处理温度为200～500℃，保温时间为0.5～1h。优选地，所述热 处理温度为300～400℃。在本发明实施例中，由于锡元素价态多变，在碳化热处理过程中可能会形成锡单质、多种含锡氧化物及锡铜合金等物质，而本发明实施例将所述热处理温度控制在200～500℃范围内，经碳化热处理后的二氧化锡的结晶度得到适当提高，有利于发挥其电化学性能；然而，当进一步提高热处理温度时，获得的负极会出现杂相，碳化热处理前后的负极极片的二氧化锡的质量变化较大，从而导致获得的极片结构疏松，使得活性物质容易从铜箔上脱落，进而导致电化学性能下降。In step S5, the pole pieces after the drying treatment are cut into small discs with a diameter of 12 mm, put into a tube furnace, and subjected to carbonization heat treatment under a preset carbonization heat treatment condition in an inert gas atmosphere to obtain The nitrogen-doped carbon / tin dioxide / porous carbon composite anode completes the preparation of the anode. The inert gas atmosphere is any one of nitrogen or argon; the preset carbonization heat treatment conditions include: a heating rate of 2 to 10 ° C / min, a heat treatment temperature of 200 to 500 ° C, and a holding time of 0.5. ~ 1h. Preferably, the heat treatment temperature is 300 to 400 ° C. In the embodiment of the present invention, due to the change of the valence state of the element tin, a single substance of tin, a variety of tin-containing oxides, and tin-copper alloys may be formed during the carbonization heat treatment process. However, the embodiment of the present invention controls the heat treatment temperature. Within the range of 200 to 500 ° C, the crystallinity of tin dioxide after carbonization heat treatment is appropriately increased, which is conducive to the development of its electrochemical performance; however, when the heat treatment temperature is further increased, the obtained anode may have a heterogeneous phase and the carbonization heat treatment The mass of the tin dioxide of the negative electrode sheet before and after changes greatly, which results in a loosened electrode sheet structure, which makes the active material easily fall off from the copper foil, which in turn leads to a decrease in electrochemical performance.
在本发明实施例中，所述多孔碳粉体的制备方法，具体包括以下步骤：In the embodiment of the present invention, the method for preparing the porous carbon powder specifically includes the following steps:
S101、将50g预处理后的离子交换树脂加入到200ml氯化钴水溶液中，搅拌2小时后放入80℃水浴中进行搅拌蒸干，再经80℃干燥12小时后，得到第一混合物；将所述第一混合物粉碎，得到吸附钴离子的树脂；其中，所述氯化钴水溶液的浓度为0.2mol/L。S101. Add 50 g of the pre-treated ion exchange resin to 200 ml of a cobalt chloride aqueous solution, stir for 2 hours, and place in a 80 ° C water bath to stir and dry, and then dry at 80 ° C for 12 hours to obtain a first mixture. The first mixture is pulverized to obtain a resin that adsorbs cobalt ions; wherein the concentration of the aqueous cobalt chloride solution is 0.2 mol / L.
S102、将100g氢氧化钾溶于400ml无水乙醇中，得到氢氧化钾/乙醇溶液；将步骤S101中得到的所述吸附钴离子的树脂加入到所述氢氧化钾/乙醇溶液中进行搅拌混合，并将搅拌混合后的所述吸附钴离子的树脂和所述氢氧化钾/乙醇溶液放入80℃油浴中进行搅拌蒸发，得到呈浆糊状的浆料；将所述浆料进行80℃干燥后，再次粉碎；S102. Dissolve 100 g of potassium hydroxide in 400 ml of absolute ethanol to obtain a potassium hydroxide / ethanol solution; add the cobalt ion-adsorbing resin obtained in step S101 to the potassium hydroxide / ethanol solution and stir and mix. And putting the cobalt ion-adsorbing resin and the potassium hydroxide / ethanol solution after stirring and mixing into an 80 ° C. oil bath for stirring and evaporation to obtain a paste-like slurry; After drying at ℃, pulverize again;
S103、在氮气气氛中，将步骤S102所得产物以2℃/min的速率升至800℃，并保温2小时，然后自然降温至室温；S103. In a nitrogen atmosphere, raise the product obtained in step S102 to 800 ° C at a rate of 2 ° C / min, and maintain the temperature for 2 hours, and then naturally lower the temperature to room temperature;
S104、将步骤S103所得产物用1mol/L的盐酸溶液浸泡36小时，并经过滤处理后，在60℃下干燥36小时；然后继续在150℃下干燥8小时，得到多孔碳材料。由相关的TEM照片表明，得到的所述多孔碳材料呈现出多孔结构。对得到的所述多孔碳进行BET测试，BET测试结果表明，所述多孔碳材料包括微孔、介孔和大孔，其中，所述微孔的孔径为1～2nm，所述介孔的孔径为2～5nm，所述大孔的孔径为20～100nm；所述多孔碳的比表面积为820m 2/g，孔体积为0.75cm 3/g。 S104. Soak the product obtained in step S103 with a 1 mol / L hydrochloric acid solution for 36 hours, and after filtering treatment, dry at 60 ° C for 36 hours; and then continue drying at 150 ° C for 8 hours to obtain a porous carbon material. The related TEM photos show that the obtained porous carbon material exhibits a porous structure. A BET test is performed on the obtained porous carbon, and the results of the BET test indicate that the porous carbon material includes micropores, mesopores, and macropores, wherein the pore diameter of the micropores is 1 to 2 nm, and the pore diameter of the mesopores It is 2 to 5 nm, and the pores have a pore diameter of 20 to 100 nm. The specific surface area of the porous carbon is 820 m 2 / g, and the pore volume is 0.75 cm 3 / g.
在本发明实施例中，所述负极的制备方法，通过将多孔碳与含锡氯盐进行水 解反应，使得含锡氯盐在多孔碳基体上原位生成分布均匀的二氧化锡纳米颗粒，得到二氧化锡/多孔碳复合粉体，从而实现了二氧化锡和多孔碳的有机结合，生成的纳米级二氧化锡有利于发挥电化学活性，且多孔碳具有独特的多级孔结构，为二氧化锡在循环过程中的体积膨胀提供了缓冲空间，从而改善了循环稳定性；然后通过将得到的所述二氧化锡/多孔碳复合粉体与聚丙烯腈进行混合，得到浆料；再将所述浆料涂覆在铜箔上，得到极片；最后在惰性气体气氛中，将干燥处理后的所述极片以预设的碳化热处理条件进行碳化热处理，得到氮掺杂碳/二氧化锡/多孔碳复合负极，完成负极的制备；通过对干燥后的所述极片进行碳化热处理，使得聚丙烯腈碳化形成氮掺杂碳包覆层，所述氮掺杂碳包覆层在二氧化锡表面形成保护层，抑制了二氧化锡与电解液间的副反应，且由于氮掺杂碳包覆层自身具有高导电性，加快了电子的快速传输，从而有效地提高了负极的导电性，因此当将采用上述方法制备的负极用作锂离子电池的负极时，能够提高锂离子电池的比容量和循环稳定性。此外，在负极制备的过程中，将负极的制备与复合材料的制备结合起来，使得聚丙烯腈在用作氮掺杂碳包覆层的有机碳源的同时，也用作粘结剂，因此，简化了负极的制备工序。In the embodiment of the present invention, the method for preparing the negative electrode is performed by subjecting porous carbon to a tin-containing chloride salt to hydrolyze the tin-containing salt on the porous carbon substrate to generate tin dioxide nanoparticles with uniform distribution in situ. Tin dioxide / porous carbon composite powder, so as to realize the organic combination of tin dioxide and porous carbon, the nano-sized tin dioxide generated is conducive to the electrochemical activity, and the porous carbon has a unique multi-stage pore structure, which is two The volume expansion of tin oxide during the cycle provides a buffer space, thereby improving the cycle stability; then, the obtained tin dioxide / porous carbon composite powder is mixed with polyacrylonitrile to obtain a slurry; and then the slurry is obtained; The slurry is coated on a copper foil to obtain a pole piece; finally, the pole piece after the drying treatment is subjected to carbonization heat treatment under a preset carbonization heat treatment condition in an inert gas atmosphere to obtain nitrogen-doped carbon / dioxide The tin / porous carbon composite negative electrode completes the preparation of the negative electrode; the carbonized polyacrylonitrile is formed into a nitrogen-doped carbon coating layer by performing carbonization heat treatment on the dried electrode sheet. The nitrogen-doped carbon coating layer forms a protective layer on the surface of tin dioxide, which suppresses the side reaction between tin dioxide and the electrolyte, and because the nitrogen-doped carbon coating layer itself has high conductivity, it speeds up the rapid transport of electrons. Therefore, the conductivity of the negative electrode is effectively improved. Therefore, when the negative electrode prepared by the above method is used as a negative electrode of a lithium ion battery, the specific capacity and cycle stability of the lithium ion battery can be improved. In addition, during the preparation of the negative electrode, the preparation of the negative electrode is combined with the preparation of the composite material, so that the polyacrylonitrile is used as an organic carbon source of the nitrogen-doped carbon coating layer and also as a binder. , Simplifying the preparation process of the negative electrode.
下述提供的实施例用于说明负极的制备方法，具体如下：The following examples are provided to illustrate the method for preparing the negative electrode, as follows:
实施例1Example 1
通过超声作用将100mg多孔碳粉体分散在200ml无水乙醇和200ml水的混合溶液中，得到多孔碳粉体的分散液；再在所述多孔碳粉体的分散液中加入1.5ml浓盐酸搅拌均匀；随后在剧烈搅拌下，在所述多孔碳粉体的分散液和浓盐酸中加入1.2g一水合二氯化锡，并升温至80℃水解反应1小时，反应结束后，得到二氧化锡/多孔碳溶液；待所述二氧化锡/多孔碳溶液的温度降至室温后，对所述二氧化锡/多孔碳溶液进行抽滤，并用去离子水充分洗涤，再经干燥处理后，得到二氧化锡/多孔碳复合粉体；按照所述二氧化锡/多孔碳复合粉体与聚丙烯腈粉体的质量比为90:10，称取所述二氧化锡/多孔碳复合粉体与聚丙烯腈粉体，并加入到二甲基甲酰胺溶剂中搅拌混合，配制成流动性良好的浆料；采用流延的方式将所述浆料涂覆在所述铜箔上，形成厚度为100μm的均匀薄层，从而得到极片；将 所述极片进行70℃的干燥处理；随后，对干燥后的所述极片进行碳化热处理：将干燥后的所述极片裁剪成直径为12mm的小圆片，放入管式炉中，在氩气气氛下以5℃/min的升温速率升温至400℃，并保温1小时，得到氮掺杂碳/二氧化锡/多孔碳复合负极，完成负极的制备。100 mg of porous carbon powder was dispersed in a mixed solution of 200 ml of anhydrous ethanol and 200 ml of water by ultrasonication to obtain a dispersion of the porous carbon powder; and 1.5 ml of concentrated hydrochloric acid was added to the dispersion of the porous carbon powder and stirred. Homogeneous; then, under vigorous stirring, 1.2 g of tin dichloride monohydrate was added to the dispersion of the porous carbon powder and concentrated hydrochloric acid, and the temperature was raised to 80 ° C for a hydrolysis reaction for 1 hour. After the reaction was completed, tin dioxide was obtained. / Porous carbon solution; after the temperature of the tin dioxide / porous carbon solution drops to room temperature, the tin dioxide / porous carbon solution is subjected to suction filtration, and fully washed with deionized water, and then dried to obtain Tin dioxide / porous carbon composite powder; according to the mass ratio of the tin dioxide / porous carbon composite powder to polyacrylonitrile powder is 90:10, weigh the tin dioxide / porous carbon composite powder and The polyacrylonitrile powder was added to the dimethylformamide solvent and stirred to prepare a slurry with good fluidity; the slurry was coated on the copper foil by casting to form a thickness of 100μm uniform thin layer Drying the pole pieces at 70 ° C; subsequently, performing carbonization heat treatment on the pole pieces after drying: cutting the pole pieces into small discs with a diameter of 12 mm and putting them into a tube type In the furnace, the temperature was raised to 400 ° C. at a heating rate of 5 ° C./min in an argon atmosphere, and the temperature was maintained for 1 hour to obtain a nitrogen-doped carbon / tin dioxide / porous carbon composite negative electrode, thereby completing the preparation of the negative electrode.
在本发明实施例中，为了对实施例1中的所述氮掺杂碳/二氧化锡/多孔碳复合负极进行结构和形貌的分析，将实施例1中得到的浆料涂覆在玻璃板上，并经干燥处理后，获得聚丙烯腈/二氧化锡/多孔碳复合粉体，将所述聚丙烯腈/二氧化锡/多孔碳复合粉体经过与实施例1相同的碳化热处理工艺后，得到氮掺杂碳/二氧化锡/多孔碳复合粉体。对得到的所述氮掺杂碳/二氧化锡/多孔碳复合粉体进行表征，结果如图1和4所示。其中，图4是本发明实施例1中的氮掺杂碳/二氧化锡/多孔碳复合粉体的X射线衍射图谱，由X射线衍射图谱可以看出，所述氮掺杂碳/二氧化锡/多孔碳复合粉体包含SnO 2晶体(二氧化锡晶体)的XRD峰(X-ray diffraction，X射线衍射)，且衍射峰较宽，因此说明SnO 2晶粒尺寸较小；图1是本发明实施例中的负极材料的透射电子显微镜照片，从透射电子显微镜照片可看出，所述多孔碳基体的外表面上均匀附着有直径为3-4nm的二氧化锡颗粒，并且所述氮掺杂碳/二氧化锡/多孔碳复合粉体的外层可观察到厚度约为3nm的高度石墨化的碳包覆薄层。进一步通过XPS对所述氮掺杂碳/二氧化锡/多孔碳复合粉体进行表征，确认了所述氮掺杂碳/二氧化锡/多孔碳复合粉体中存在由所述聚丙烯腈分解引入的氮，并且锡元素的价态为+4价。以上表征结果说明，纳米级二氧化锡成功附着在多孔碳基体上，且二氧化锡表层分布了高导电性的包覆层，所述包覆层由氮掺杂碳形成。 In the embodiment of the present invention, in order to analyze the structure and morphology of the nitrogen-doped carbon / tin dioxide / porous carbon composite anode in Example 1, the slurry obtained in Example 1 was coated on glass. After being dried on the plate, a polyacrylonitrile / tin dioxide / porous carbon composite powder was obtained, and the polyacrylonitrile / tin dioxide / porous carbon composite powder was subjected to the same carbonization heat treatment process as in Example 1. Then, a nitrogen-doped carbon / tin dioxide / porous carbon composite powder was obtained. The obtained nitrogen-doped carbon / tin dioxide / porous carbon composite powder was characterized, and the results are shown in FIGS. 1 and 4. 4 is an X-ray diffraction pattern of the nitrogen-doped carbon / tin dioxide / porous carbon composite powder in Example 1 of the present invention. As can be seen from the X-ray diffraction pattern, the nitrogen-doped carbon / dioxide The tin / porous carbon composite powder contains X-ray diffraction (X-ray diffraction) of SnO 2 crystals (tin dioxide crystals), and the diffraction peaks are broad, so the SnO 2 grain size is small; Figure 1 is According to a transmission electron microscope photograph of the negative electrode material in the embodiment of the present invention, it can be seen from the transmission electron microscope photograph that the outer surface of the porous carbon substrate is uniformly adhered with tin dioxide particles having a diameter of 3-4 nm, and the nitrogen A highly graphitized carbon-coated thin layer with a thickness of about 3 nm was observed on the outer layer of the doped carbon / tin dioxide / porous carbon composite powder. Further characterization of the nitrogen-doped carbon / tin dioxide / porous carbon composite powder by XPS confirmed that the nitrogen-doped carbon / tin dioxide / porous carbon composite powder was decomposed by the polyacrylonitrile The nitrogen is introduced, and the valence of the tin element is +4. The above characterization results show that the nano-sized tin dioxide is successfully attached to the porous carbon substrate, and a highly conductive coating layer is distributed on the surface of the tin dioxide layer, and the coating layer is formed of nitrogen-doped carbon.
结合图5至图7所示，将实施例1所制备的氮掺杂碳/二氧化锡/多孔碳复合负极应用于锂离子电池中，表现出了优异的电化学性能。其中，图5是本发明实施例1中的氮掺杂碳/二氧化锡/多孔碳复合负极在不同电流密度下的循环性能图，由图5可以看出，所述氮掺杂碳/二氧化锡/多孔碳复合负极在不同的电流密度下循环时，均能提供较高的比容量，并且经过大电流充放之后仍能稳定测试；图6是本发明实施例1中的氮掺杂碳/二氧化锡/多孔碳复合负极在1A/g电流密度下的 循环性能图，由图6可看出，所述氮掺杂碳/二氧化锡/多孔碳复合负极在经过500次循环后，比容量高达767mAh/g，且除了开始的几次循环之外，在整个循环过程中，库伦效率接近100％，表现出优异的循环稳定性。图7是本发明实施例1以及对比例7～9中的氮掺杂碳/二氧化锡/多孔碳复合负极在0.1A/g电流密度下的循环性能图，由图7可以看出，实施例1得到的所述氮掺杂碳/二氧化锡/多孔碳复合负极在0.1A/g电流密度下，首次和第二次放电的比容量分别为1439mAh/g和1067mAh/g，经过100次循环后，比容量稳定在1117mAh/g。因此，当将本实施例得到的所述氮掺杂碳/二氧化锡/多孔碳复合负极应用于锂离子电池时，能够提高锂离子电池的比容量和循环稳定性。With reference to FIGS. 5 to 7, the nitrogen-doped carbon / tin dioxide / porous carbon composite anode prepared in Example 1 is applied to a lithium-ion battery, and exhibits excellent electrochemical performance. Among them, FIG. 5 is a cycle performance diagram of the nitrogen-doped carbon / tin dioxide / porous carbon composite anode at different current densities in Example 1 of the present invention. As can be seen from FIG. 5, the nitrogen-doped carbon / two When the tin oxide / porous carbon composite anode is cycled under different current densities, it can provide a higher specific capacity, and it can still be tested stably after charging and discharging at a large current; Figure 6 shows nitrogen doping in Example 1 of the present invention. The cycle performance diagram of the carbon / tin dioxide / porous carbon composite anode at a current density of 1A / g. As can be seen from FIG. 6, after 500 cycles of the nitrogen-doped carbon / tin dioxide / porous carbon composite anode The specific capacity is as high as 767mAh / g, and in addition to the first few cycles, the Coulomb efficiency is close to 100% throughout the cycle, showing excellent cycle stability. FIG. 7 is a cycle performance diagram of the nitrogen-doped carbon / tin dioxide / porous carbon composite anode at a current density of 0.1 A / g in Example 1 of the present invention and Comparative Examples 7-9. The specific capacities of the first and second discharges of the nitrogen-doped carbon / tin dioxide / porous carbon composite anode obtained in Example 1 at a current density of 0.1 A / g were 1439 mAh / g and 1067 mAh / g, respectively, after 100 times. After cycling, the specific capacity was stable at 1117 mAh / g. Therefore, when the nitrogen-doped carbon / tin dioxide / porous carbon composite negative electrode obtained in this embodiment is applied to a lithium ion battery, the specific capacity and cycle stability of the lithium ion battery can be improved.
实施例2Example 2
本实施例与实施例1的区别在于，在所述无水乙醇和水的混合溶液中，所述无水乙醇为100ml，所述水为300ml；在所述多孔碳粉体的分散液中加入的所述浓盐酸为1ml；在所述多孔碳粉体的分散液和浓盐酸中加入的一水合二氯化锡为2g，并升温至90℃进行水解反应；在碳化热处理过程中，在氩气气氛下以10℃/min的升温速率升温至400℃，并保温1小时。本实施例的其它工艺及步骤与实施例1相同，在此不做更多的赘述。The difference between this embodiment and Example 1 is that in the mixed solution of anhydrous ethanol and water, the anhydrous ethanol is 100 ml, and the water is 300 ml; and added to the dispersion of the porous carbon powder. The concentrated hydrochloric acid is 1 ml; 2 g of tin dichloride monohydrate is added to the dispersion of the porous carbon powder and the concentrated hydrochloric acid, and the temperature is increased to 90 ° C for hydrolysis reaction; The temperature was increased to 400 ° C at a temperature increase rate of 10 ° C / min in a gas atmosphere, and the temperature was maintained for 1 hour. The other processes and steps of this embodiment are the same as those of Embodiment 1, and will not be described in detail here.
实施例3Example 3
本实施例与实施例1的区别在于，在所述无水乙醇和水的混合溶液中，所述无水乙醇为200ml，所述水为300ml；在所述多孔碳粉体的分散液中加入的所述浓盐酸为2ml；在所述多孔碳粉体的分散液和浓盐酸中加入的一水合二氯化锡为1g；称取的二氧化锡/多孔碳复合粉体与聚丙烯腈粉体的质量比为80:20；在碳化热处理过程中，在氮气气氛下以3℃/min的升温速率升温至400℃，并保温0.5小时。本实施例的其它工艺及步骤与实施例1相同，在此不做更多的赘述。The difference between this embodiment and Example 1 is that in the mixed solution of anhydrous ethanol and water, the anhydrous ethanol is 200 ml, and the water is 300 ml; and added to the dispersion of the porous carbon powder. The concentrated hydrochloric acid is 2 ml; 1 g of tin dichloride monohydrate is added to the dispersion of the porous carbon powder and concentrated hydrochloric acid; and the weighed tin dioxide / porous carbon composite powder and polyacrylonitrile powder are weighed. The mass ratio of the body was 80:20; during the carbonization heat treatment, the temperature was increased to 400 ° C at a temperature increase rate of 3 ° C / min in a nitrogen atmosphere, and the temperature was maintained for 0.5 hours. The other processes and steps of this embodiment are the same as those of Embodiment 1, and will not be described in detail here.
实施例4Example 4
本实施例与实施例1的区别在于，在碳化热处理过程中，所述热处理温度为200℃。本实施例的其它工艺及步骤与实施例1相同，在此不做更多的赘述。The difference between this embodiment and Embodiment 1 is that during the carbonization heat treatment, the heat treatment temperature is 200 ° C. The other processes and steps of this embodiment are the same as those of Embodiment 1, and will not be described in detail here.
实施例5Example 5
本实施例与实施例1的区别在于，在碳化热处理过程中，所述热处理温度为300℃。本实施例的其它工艺及步骤与实施例1相同，在此不做更多的赘述。The difference between this embodiment and Embodiment 1 is that during the carbonization heat treatment, the heat treatment temperature is 300 ° C. The other processes and steps of this embodiment are the same as those of Embodiment 1, and will not be described in detail here.
实施例6Example 6
本实施例与实施例1的区别在于，在碳化热处理过程中，所述热处理温度为500℃。本实施例的其它工艺及步骤与实施例1相同，在此不做更多的赘述。The difference between this embodiment and Embodiment 1 is that during the carbonization heat treatment, the heat treatment temperature is 500 ° C. The other processes and steps of this embodiment are the same as those of Embodiment 1, and will not be described in detail here.
在负极制备的过程中，碳化热处理以及水解反应对于本发明的负极的制备方法是关键的，为此本发明进行了以下对比例7～9。In the process of preparing the negative electrode, the carbonization heat treatment and the hydrolysis reaction are critical to the method for preparing the negative electrode of the present invention. For this reason, the following comparative examples 7 to 9 were performed in the present invention.
对比例7Comparative Example 7
本对比例与实施例1的区别在于，未对干燥处理后的所述极片进行碳化热处理，即得到的最终负极为干燥后的所述极片。本对比例的其他工艺及步骤与实施例1相同，在此不做更多的赘述。The difference between this comparative example and Example 1 is that the electrode sheet after the drying process is not subjected to carbonization heat treatment, that is, the final negative electrode obtained is the electrode sheet after drying. The other processes and steps of this comparative example are the same as those of Embodiment 1, and will not be described in detail here.
对得到的负极进行表征；通过X射线衍射图谱可知，二氧化锡的衍射峰较弱，由此说明，二氧化锡结晶性较差。通过透射电子显微镜照片可观察到，二氧化锡表面的无定型碳包覆层，所述无定型碳包覆层不具有高度石墨化特征，由此说明，其导电性较差。得到的最终负极在0.1A/g电流密度下的循环性能如图7所示，由图7可知，该负极经过100次循环充放电之后，比容量衰减幅度较大；其原因在于，二氧化锡颗粒结晶性较差，导致其电化学活性较弱，且二氧化锡表面的碳包覆层的导电性较差，使得无法在充放电过程中，有效地加速电子迁移，因此，导致比容量衰减幅度较大。The obtained negative electrode was characterized; it can be seen from the X-ray diffraction pattern that the diffraction peak of tin dioxide is weak, which indicates that the tin dioxide has poor crystallinity. It can be observed through a transmission electron microscope photograph that the amorphous carbon coating layer on the surface of tin dioxide, which does not have a high graphitization feature, thus indicating that its conductivity is poor. The cycle performance of the obtained final negative electrode at a current density of 0.1 A / g is shown in FIG. 7. As can be seen from FIG. 7, after 100 cycles of charge and discharge, the specific capacity attenuation of the negative electrode is large; the reason is that tin dioxide The poor crystallinity of the particles results in weak electrochemical activity, and the poor electrical conductivity of the carbon coating on the surface of tin dioxide makes it impossible to effectively accelerate the electron migration during the charge and discharge process, thus causing the specific capacity to decay Larger.
对比例8Comparative Example 8
本对比例与实施例1的区别在于，在碳化热处理过程中，所述热处理温度为600℃。本对比例的其他工艺及步骤与实施例1相同，在此不做更多的赘述。This comparative example differs from Example 1 in that during the carbonization heat treatment, the heat treatment temperature is 600 ° C. The other processes and steps of this comparative example are the same as those of Embodiment 1, and will not be described in detail here.
对得到的所述氮掺杂碳/二氧化锡/多孔碳复合负极进行表征；通过X射线衍射图谱可知，二氧化锡的衍射峰高而强，由此说明，二氧化锡晶粒尺寸较大，此外，还出现了一些归属于铜锡合金的杂峰。得到的所述氮掺杂碳/二氧化锡/多孔碳复合负极在0.1A/g电流密度下的循环性能如图7所示，由图7可知，所述氮掺杂碳/二氧化锡/多孔碳复合负极初始放电的比容量远低于实施例1所制备的所述 氮掺杂碳/二氧化锡/多孔碳复合负极；其原因在于，提高热处理温度导致生成了非活性的铜锡合金杂质相，使得负极的结构变得疏松，从而导致活性物质容易从铜箔上脱落；此外，由于二氧化锡颗粒尺寸较大，加剧了充放电过程中，二氧化锡的体积膨胀，因此，导致比容量较低。The obtained nitrogen-doped carbon / tin dioxide / porous carbon composite negative electrode was characterized; according to the X-ray diffraction pattern, it can be seen that the diffraction peak of tin dioxide is high and strong, which indicates that the grain size of tin dioxide is large In addition, there are some miscellaneous peaks attributed to copper-tin alloys. The cycle performance of the obtained nitrogen-doped carbon / tin dioxide / porous carbon composite anode at a current density of 0.1 A / g is shown in FIG. 7. As can be seen from FIG. 7, the nitrogen-doped carbon / tin dioxide / The specific capacity of the porous carbon composite negative electrode for initial discharge is much lower than the nitrogen-doped carbon / tin dioxide / porous carbon composite negative electrode prepared in Example 1; the reason is that increasing the heat treatment temperature results in the formation of an inactive copper-tin alloy The impurity phase makes the structure of the negative electrode loose, which causes the active material to easily fall off the copper foil. In addition, the larger size of the tin dioxide particles exacerbates the volume expansion of tin dioxide during the charge and discharge process. Lower specific capacity.
对比例9Comparative Example 9
本对比例与实施例1的区别在于，本对比例采用简单的机械搅拌法代替原位化学法来混合多孔碳和二氧化锡。本对比例的其他工艺及步骤与实施例1相同，在此不做更多的赘述。This comparative example differs from Example 1 in that the comparative example uses a simple mechanical stirring method instead of the in-situ chemical method to mix porous carbon and tin dioxide. The other processes and steps of this comparative example are the same as those of Embodiment 1, and will not be described in detail here.
本对比例采用简单的机械搅拌法来混合多孔碳和二氧化锡，具体为：按照纳米级二氧化锡粉体、多孔碳粉体和聚丙烯腈粉体的质量比为60:30:10，称取所述纳米级二氧化锡粉体、所述多孔碳粉体和所述聚丙烯腈粉体，并采用机械搅拌方式来混合多孔碳和二氧化锡。本对比例的其他工艺步骤与实施例1相同。This comparative example uses a simple mechanical stirring method to mix porous carbon and tin dioxide. Specifically, the mass ratio of nano-sized tin dioxide powder, porous carbon powder, and polyacrylonitrile powder is 60:30:10. Weigh the nano-sized tin dioxide powder, the porous carbon powder, and the polyacrylonitrile powder, and use a mechanical stirring method to mix the porous carbon and tin dioxide. The other process steps of this comparative example are the same as in Example 1.
本对比例的氮掺杂碳/二氧化锡/多孔碳复合负极在0.1A/g电流密度下的循环性能如图7所示，由图7可知，所述氮掺杂碳/二氧化锡/多孔碳复合负极的初始放电比容量较高，但其比容量随循环次数的增加衰减十分明显；其原因在于，采用简单的机械混合方法，难以使二氧化锡颗粒均匀附着在多孔碳基体的表面，导致随着循环次数的增加，二氧化锡颗粒容易堆积团聚，难以充分发挥多孔碳的结构对二氧化锡体积膨胀的缓冲作用，因此，使得所述氮掺杂碳/二氧化锡/多孔碳复合负极的比容量随着循环次数的增加而加剧衰减。The cycling performance of the nitrogen-doped carbon / tin dioxide / porous carbon composite anode of this comparative example at a current density of 0.1 A / g is shown in FIG. 7. As can be seen from FIG. 7, the nitrogen-doped carbon / tin dioxide / The initial discharge specific capacity of the porous carbon composite negative electrode is high, but its specific capacity decays significantly with the increase of the number of cycles; the reason is that it is difficult to make the tin dioxide particles adhere to the surface of the porous carbon substrate uniformly using a simple mechanical mixing method As the number of cycles increases, the tin dioxide particles tend to accumulate and agglomerate, and it is difficult to fully exert the buffering effect of the structure of porous carbon on the volume expansion of tin dioxide. Therefore, the nitrogen doped carbon / tin dioxide / porous carbon The specific capacity of the composite anode increases with the number of cycles.
对本发明实施例2～6以及对比例7～9所制备的氮掺杂碳/二氧化锡/多孔碳复合负极均采用与实施例1相同的工艺条件应用于锂离子电池中，并测试锂离子电池在0.1A/g电流密度下的循环性能，测试结果如表1所示。表1是实施例1～6及对比例7～9所制备的复合负极在0.1A/g电流密度下的循环性能。The nitrogen-doped carbon / tin dioxide / porous carbon composite anodes prepared in Examples 2 to 6 and Comparative Examples 7 to 9 of the present invention were applied to lithium ion batteries using the same process conditions as in Example 1, and lithium ions were tested. The cycling performance of the battery at a current density of 0.1 A / g is shown in Table 1. Table 1 shows the cycle performance of the composite negative electrodes prepared in Examples 1 to 6 and Comparative Examples 7 to 9 at a current density of 0.1 A / g.
表1Table 1
Figure PCTCN2018094755-appb-000001
Figure PCTCN2018094755-appb-000001
Figure PCTCN2018094755-appb-000002
Figure PCTCN2018094755-appb-000002
由表1可以看出，相对于对比例7～9，本发明实施例1～6所制备的氮掺杂碳/二氧化锡/多孔碳复合负极均可实现高比容量和较好的循环稳定性，这与其独特的复合结构密不可分。具体地，采用所述制备方法得到的负极，其中的多孔碳基体能够为二氧化锡纳米颗粒提供三维支撑载体，有利于缓解二氧化锡在充放电过程中伴随的体积膨胀，提升了锂离子电池的循环性能；且由于负极材料的表面附着有氮掺杂碳包覆薄层，其有利于抑制二氧化锡与电解液间的副反应，从而提高了电极的整体导电性，因此提高了锂离子电池的比容量。此外，通过控制适宜的热处理温度，使得负极材料中的二氧化锡颗粒尺寸较小，且其是负极材料中的单一晶相，从而确保了制备的负极能够发挥较高的性能。It can be seen from Table 1 that compared to Comparative Examples 7-9, the nitrogen-doped carbon / tin dioxide / porous carbon composite anode prepared in Examples 1 to 6 of the present invention can achieve high specific capacity and good cycle stability. Sex, which is inseparable from its unique composite structure. Specifically, in the negative electrode obtained by the preparation method, the porous carbon matrix can provide a three-dimensional support carrier for tin dioxide nanoparticles, which is beneficial to alleviate the volume expansion accompanying tin dioxide during the charge and discharge process, and improves the lithium ion battery. Cycle performance; and because a thin layer of nitrogen-doped carbon coating is attached to the surface of the anode material, it is beneficial to suppress the side reaction between tin dioxide and the electrolyte, thereby improving the overall conductivity of the electrode, and thus improving lithium ions. The specific capacity of the battery. In addition, by controlling the appropriate heat treatment temperature, the size of the tin dioxide particles in the anode material is small, and it is a single crystal phase in the anode material, thereby ensuring that the prepared anode can exhibit higher performance.
综上，本发明提供一种负极材料、负极及负极的制备方法，当将所述负极材料在用作锂离子电池负极时，多孔碳基体能够为二氧化锡纳米颗粒提供三维支撑载体，从而缓解了二氧化锡在充放电过程中伴随的体积膨胀，进而提升了锂离子电池的循环稳定性；同时，负极材料的表面具有氮掺杂碳包覆层，抑制了二氧化锡与电解液间的副反应，并提高了电极整体导电性，从而提高了锂离子电池锂离子电池的比容量。In summary, the present invention provides a negative electrode material, a negative electrode, and a method for preparing a negative electrode. When the negative electrode material is used as a negative electrode of a lithium ion battery, a porous carbon substrate can provide a three-dimensional support carrier for tin dioxide nanoparticles, thereby alleviating the problem. It increases the volume expansion of tin dioxide during charging and discharging, which improves the cycle stability of lithium-ion batteries. At the same time, the surface of the anode material has a nitrogen-doped carbon coating layer, which suppresses the relationship between tin dioxide and the electrolyte. Side reactions and improve the overall conductivity of the electrode, thereby increasing the specific capacity of the lithium-ion battery.
以上所述仅是本发明的优选实施方式，应当指出，对于本技术领域的普通技术人员来说，在不脱离本发明技术原理的前提下，还可以做出若干改进和替换，这些改进和替换也应视为本发明的保护范围。The above is only a preferred embodiment of the present invention. It should be noted that, for those of ordinary skill in the art, without departing from the technical principles of the present invention, several improvements and replacements can be made. These improvements and replacements It should also be regarded as the protection scope of the present invention.

Claims (16)

  1. 一种负极材料，其特征在于，包括氮掺杂碳包覆层、多孔碳以及二氧化锡，所述二氧化锡附着于所述多孔碳上，所述氮掺杂碳包覆层包裹所述二氧化锡和所述多孔碳。A negative electrode material, characterized in that it includes a nitrogen-doped carbon coating layer, porous carbon, and tin dioxide, the tin dioxide is attached to the porous carbon, and the nitrogen-doped carbon coating layer covers the Tin dioxide and the porous carbon.
  2. 如权利要求1所述的负极材料，其特征在于，所述氮掺杂碳包覆层的厚度为1～5nm。The negative electrode material according to claim 1, wherein a thickness of the nitrogen-doped carbon coating layer is 1 to 5 nm.
  3. 如权利要求1所述的负极材料，其特征在于，所述二氧化锡的粒径为2～6nm。The negative electrode material according to claim 1, wherein a particle diameter of the tin dioxide is 2 to 6 nm.
  4. 如权利要求1所述的负极材料，其特征在于，所述氮掺杂碳包覆层由聚丙烯腈碳化形成。The negative electrode material according to claim 1, wherein the nitrogen-doped carbon coating layer is formed by carbonizing polyacrylonitrile.
  5. 一种负极，其特征在于，包括铜箔以及如权利要求1-4任一项所述的负极材料，所述负极材料附于所述铜箔上。A negative electrode, comprising a copper foil and the negative electrode material according to claim 1, wherein the negative electrode material is attached to the copper foil.
  6. 一种负极的制备方法，其特征在于，包括步骤：A method for preparing a negative electrode, comprising the steps of:
    将多孔碳与含锡氯盐进行水解反应，得到二氧化锡/多孔碳复合粉体；The porous carbon is subjected to a hydrolysis reaction with a tin-containing chloride salt to obtain a tin dioxide / porous carbon composite powder;
    将所述二氧化锡/多孔碳复合粉体与聚丙烯腈进行混合，得到浆料；Mixing the tin dioxide / porous carbon composite powder with polyacrylonitrile to obtain a slurry;
    将所述浆料涂覆在铜箔上，得到极片；Coating the slurry on a copper foil to obtain a pole piece;
    将所述极片进行干燥处理；Drying the pole piece;
    在惰性气体气氛中，将干燥处理后的所述极片以预设的碳化热处理条件进行碳化热处理，得到氮掺杂碳/二氧化锡/多孔碳复合负极，完成负极的制备。In an inert gas atmosphere, the pole pieces after the drying treatment are subjected to carbonization heat treatment under preset carbonization heat treatment conditions to obtain a nitrogen-doped carbon / tin dioxide / porous carbon composite anode, thereby completing the preparation of the anode.
  7. 如权利要求6所述的负极的制备方法，其特征在于，所述将多孔碳与含锡氯盐进行水解反应，得到二氧化锡/多孔碳复合粉体，包括步骤：The method for preparing a negative electrode according to claim 6, wherein the step of hydrolyzing the porous carbon with the tin-containing chloride salt to obtain a tin dioxide / porous carbon composite powder comprises the steps of:
    将多孔碳粉体分散在有机溶剂和水形成的混合溶液中，得到多孔碳粉体的分散液；Dispersing the porous carbon powder in a mixed solution of an organic solvent and water to obtain a dispersion liquid of the porous carbon powder;
    将所述多孔碳粉体的分散液与浓盐酸进行搅拌混合；Stirring and mixing the dispersion of the porous carbon powder with concentrated hydrochloric acid;
    将搅拌混合后的所述多孔碳粉体的分散液和浓盐酸与含锡氯盐以预设的反应条件进行水解反应，得到二氧化锡/多孔碳溶液；Performing the hydrolysis reaction of the porous carbon powder dispersion and concentrated hydrochloric acid and the tin-containing chloride salt after the mixing and mixing under a preset reaction condition to obtain a tin dioxide / porous carbon solution;
    将所述二氧化锡/多孔碳溶液进行抽滤、洗涤、干燥处理，得到二氧化锡/多 孔碳复合粉体。The tin dioxide / porous carbon solution was subjected to suction filtration, washing, and drying to obtain a tin dioxide / porous carbon composite powder.
  8. 如权利要求7所述的负极的制备方法，其特征在于，所述有机溶剂和水的体积比为1:3～3:1。The method of claim 7, wherein the volume ratio of the organic solvent to water is 1: 3 to 3: 1.
  9. 如权利要求7所述的负极的制备方法，其特征在于，所述有机溶剂为无水乙醇、乙二醇、甲醇、丙醇中的任一种。The method for preparing a negative electrode according to claim 7, wherein the organic solvent is any one of anhydrous ethanol, ethylene glycol, methanol, and propanol.
  10. 如权利要求6或7所述的负极的制备方法，其特征在于，所述多孔碳和所述含锡氯盐的质量比为1:10～1:20。The method for preparing a negative electrode according to claim 6 or 7, wherein a mass ratio of the porous carbon and the tin-containing chloride salt is 1:10 to 1:20.
  11. 如权利要求6或7所述的负极的制备方法，其特征在于，所述含锡氯盐为一水合二氯化锡。The method for preparing a negative electrode according to claim 6 or 7, wherein the tin-containing chloride salt is tin dichloride monohydrate.
  12. 如权利要求7所述的负极的制备方法，其特征在于，所述预设的反应条件包括：反应温度为70～90℃，反应时间为0.5～2h。The method of claim 7, wherein the preset reaction conditions include: a reaction temperature of 70 to 90 ° C. and a reaction time of 0.5 to 2 h.
  13. 如权利要求6所述的负极的制备方法，其特征在于，所述将所述二氧化锡/多孔碳复合粉体与聚丙烯腈进行混合，得到浆料，具体为：The method for preparing a negative electrode according to claim 6, wherein the mixing the tin dioxide / porous carbon composite powder with polyacrylonitrile to obtain a slurry is specifically:
    将所述二氧化锡/多孔碳复合粉体和聚丙烯腈粉体与二甲基甲酰胺溶剂进行搅拌混合，得到所述浆料。The tin dioxide / porous carbon composite powder and the polyacrylonitrile powder are mixed with a dimethylformamide solvent under stirring to obtain the slurry.
  14. 如权利要求6或13所述的负极的制备方法，其特征在于，所述二氧化锡/多孔碳复合粉体和所述聚丙烯腈的质量比为4:1～9:1。The method for preparing a negative electrode according to claim 6 or 13, wherein a mass ratio of the tin dioxide / porous carbon composite powder and the polyacrylonitrile is 4: 1 to 9: 1.
  15. 如权利要求6所述的负极的制备方法，其特征在于，所述惰性气体为氮气或氩气。The method of claim 6, wherein the inert gas is nitrogen or argon.
  16. 如权利要求6所述的负极的制备方法，其特征在于，所述预设的碳化热处理条件包括：升温速率为2～10℃/min，热处理温度为200～500℃，保温时间为0.5～1h。The method of claim 6, wherein the preset carbonization heat treatment conditions include: a heating rate of 2-10 ° C./min, a heat treatment temperature of 200-500 ° C., and a holding time of 0.5-1 h .
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