WO2020211848A1 - Nano-composite negative electrode material, preparation method therefor and use thereof - Google Patents

Nano-composite negative electrode material, preparation method therefor and use thereof Download PDF

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WO2020211848A1
WO2020211848A1 PCT/CN2020/085389 CN2020085389W WO2020211848A1 WO 2020211848 A1 WO2020211848 A1 WO 2020211848A1 CN 2020085389 W CN2020085389 W CN 2020085389W WO 2020211848 A1 WO2020211848 A1 WO 2020211848A1
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negative electrode
nano
electrode material
composite
silicon
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徐政和
杨帆
易婷婷
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南方科技大学
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/362—Composites
    • H01M4/366—Composites as layered products
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/387—Tin or alloys based on tin
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
    • H01M4/483—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides for non-aqueous cells
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the invention relates to the field of batteries, in particular to a nano composite negative electrode material and a preparation method and application thereof.
  • Graphite anode materials have a series of excellent characteristics such as high thermal stability, good chemical stability, good conductivity, high efficiency of lithium ion insertion and extraction, and low cost.
  • its maximum theoretical capacity is only 372mAh ⁇ g -1 , which greatly limits the energy density of the single-component graphite anode battery.
  • some materials have a higher theoretical capacity than graphite. For example, the theoretical capacity of silicon oxide can reach 1600mAh ⁇ g -1 , and the theoretical energy density of silicon can reach 4200mAh ⁇ g -1 , which is much higher. The energy density of graphite.
  • the disadvantage of these materials as negative electrode materials is that they are often accompanied by huge volume expansion during the lithiation process. Taking silicon as an example, in the fully lithiated state, the expansion rate can reach nearly 400%. Such a high expansion rate causes huge stress on the internal structure of silicon. During multiple charge and discharge processes, the silicon material is prone to pulverization, which in turn causes the energy density of the negative electrode material to decrease significantly with the number of charge and discharge cycles. The solid electrolyte (SEI) on the active material interface will rupture during the expansion of the material. The newly exposed active surface will continue to react with the electrolyte, causing a large amount of electrolyte consumption. At the same time, the excessive growth of the SEI film will also cause lithium ion diffusion Influence, further aggravate the capacity reduction.
  • SEI solid electrolyte
  • Si-C composite materials as anode materials for lithium-ion batteries
  • silicon as an active material can provide high storage capacity
  • carbon as a coating phase or skeleton can effectively reduce the polymerization between silicon, and is In the process, the volume change of silicon is buffered, and the good conductivity of carbon can improve the electronic conductivity of silicon materials. Therefore, the prospect of using carbon-silicon composite materials as anode materials for lithium-ion batteries is attractive, which also makes the Si-C composite anode material system It has become a hot spot in current research on anode materials.
  • Niu et al. used a ball milling method to disperse silicon particles in a graphite sol (Graphite Gel), mixed the sol with PVDF (85wt%: 15wt%) and smeared it on a 20 ⁇ 20 micron copper sheet to prepare a lithium-ion battery anode material .
  • the charge-discharge cycle performance of the electrode material is better than that of the general silicon particle electrode. They attributed the improved cycle stability to the volume expansion buffer effect provided by the gel 3D structure during silicon charging and discharging [Electrochemical and Solid-State Letters, 2002.5(6): p.A107-A110].
  • Carbon-silicon composite material is a new type of material suitable as a negative electrode for lithium batteries.
  • most carbon-silicon composite materials still have unavoidable problems: 1) Most carbon-silicon composite electrodes with complex morphology The preparation process of the material is very complicated, the preparation cost is too high, and it is difficult to achieve scale-up production; 2) The bonding force between the silicon component and the carbon component in most carbon-silicon anode materials is not strong enough, as the charge and discharge process The volume change of silicon makes the silicon-carbon bond easy to peel off, resulting in material failure, resulting in unsatisfactory cycle stability of electrode materials; 3) At present, most new carbon-silicon composite anode materials only focus on improving the quality and energy density of the material, so they blindly pursue looseness The volume capacity density of such loose structure materials is very low, so it is also of great significance to increase the volume capacity density of the electrode.
  • nano-spherical silicon powder has the advantage of being cheaper and can be mass-produced compared with other silicon-based materials, it is more qualified for the application of commercial electrode materials.
  • Coating the carbon layer on the surface of the nano silicon ball can increase the conductivity of the silicon-based material and provide a good channel for the insertion and extraction of lithium ions.
  • low material costs due to its simple preparation process, low material costs, and retain most of the silicon volume as active Substances, and then get higher volume capacity than other morphology carbon-silicon composite materials.
  • the morphology of silicon-on-carbon is considered the most promising carbon-silicon anode material structure.
  • the carbon layer on the surface of the silicon active material is generally coated by gas or liquid phase, that is, the carbon source is deposited on the surface of the active material by passing the carbon source through a gas medium or a liquid medium.
  • the patent discloses a method for preparing a composite carbon layer on the surface of a silicon substrate. After the silicon powder is coated with carbon by a gas phase or thermal coating method, it is placed in a pitch solution and grown to obtain a carbon embedded with silicon particles. The microspheres are then carbonized to obtain a silicon-carbon composite material.
  • the material has a high capacity of 500-600mAh ⁇ g -1 , and has the advantages of high first-time Coulombic efficiency, stable cycle performance, high compaction density, and stable electrode structure.
  • the patent (CN105789576B) discloses a method for preparing a silicon-based negative electrode material, which is to prepare a slurry of carbon material, silicon material, binder and conductive agent, spray drying and granulation to form 5 ⁇ m ⁇ 35 ⁇ m particles, after sintering and carbonization, Disperse and reuse the asphalt as a binder for secondary granulation. After sintering, carbonization and dispersing, the negative electrode material is obtained by three granulation in the same way.
  • Its carbonization temperature is between 800-1000°C, and the prepared negative electrode material has a 0.1C reversible capacity of 650mAh ⁇ g -1 , an initial efficiency of 88%, a 10C reversible capacity of 542mAh ⁇ g -1 , and a capacity maintained at 0.1C of 83 %, 0.1C 100-week capacity retention rate is 96.5%.
  • the materials obtained by the above methods have good cycle stability, the capacity is generally low. This problem is mainly due to the thicker carbon layer used in the preparation. Due to the high carbonization temperature and high degree of carbonization used in the process, the carbon layer is too brittle, and a large thickness is required to maintain cycle stability. On the other hand, most of the components contained in the pitch do not have strong binding force to the silicon surface, and the silicon surface is hydrophilic due to its rich hydroxyl groups, so the above method requires carbon coating (hydrophobic) on the silicon surface in advance.
  • the silicon powder can be dispersed in the asphalt solution only after chemical treatment. While the process is complicated, it further reduces the proportion of active substances in the composite material and reduces the overall energy density.
  • the purpose of the present invention is to provide a nanocomposite material and its preparation method and application, aiming to solve the problems of low capacity and low cycle stability of existing silicon-based negative electrode materials.
  • a method for preparing a nano composite negative electrode material which comprises the following steps:
  • the composite material precursor is heated under an inert atmosphere to prepare the nano composite negative electrode material.
  • the method for preparing the nano composite negative electrode material is characterized in that the nano particles with lithium ion intercalation activity are one of nano silicon, nano silicon oxide or nano tin.
  • the asphaltene includes 3-11 rings of organic polycyclic molecules, and the hydrocarbon molar ratio of the asphaltene is 0.6-1.1.
  • the method for preparing the nanocomposite negative electrode material wherein the nanoparticles and asphaltenes are mixed in a solvent for 0.1-24 hours, and the asphaltenes are driven to adsorb on the surface of the nanoparticles and form a coating layer by selecting and controlling the characteristics of the solvent.
  • the composite precursor is obtained.
  • the method for preparing the nanocomposite negative electrode material wherein the concentration of the asphaltene in the solvent is 0.01-100 g/L.
  • the thickness of the coating layer formed by the asphaltene adsorbed on the surface of the nano particles is 1-100 nm.
  • the method for preparing the nano-composite negative electrode material wherein, in the step of heating the composite material precursor under an inert atmosphere to prepare the nano-composite negative electrode material, the heating temperature is 250-1200°C, and the heating The time is 0.5-10h.
  • a nano composite negative electrode material which is prepared by the preparation method of the present invention.
  • nano-composite negative electrode material prepared by the preparation method of the present invention is used as a negative electrode sheet of a lithium ion battery.
  • the preparation method of the nano composite negative electrode material provided by the present invention has the advantages of wide source of raw materials, simple synthesis path, scalable synthesis scale, etc.
  • the composite negative electrode material includes a coating formed by adsorbing asphaltene on the surface of the nano particles. After high temperature treatment, the coating layer has the advantages of high mechanical strength and good ion conductivity.
  • the nano composite negative electrode material has high energy density, good cycle stability and a series of high-efficiency lithium battery negative electrodes. At a current density of 107.4mAh ⁇ g -1 (0.03C), the first charge-discharge efficiency of the nanocomposite anode material can reach 87.2%, and the energy density can reach 3195.12mAh ⁇ g -1 .
  • FIG. 1 is a flowchart of a preferred embodiment of a method for preparing a nanocomposite negative electrode material of the present invention.
  • Fig. 2 is a schematic diagram of the principle of preparing a nanocomposite negative electrode material by the solvent transition method of the present invention.
  • Example 3 is a schematic diagram of a scanning electron microscope of the nanocomposite anode material in Example 4 of the present invention.
  • Example 4 is a schematic diagram of a scanning electron microscope of the nanocomposite anode material in Example 5 of the present invention.
  • Fig. 5 shows the long cycle performance of a lithium-ion battery made from the silicon-carbon negative electrode sheet in Example 6 of the present invention, where the abscissa is the number of cycles, and the ordinate is the specific discharge capacity.
  • Example 6 is an atomic force microscope microscopic morphology diagram of the carbon layer material in the silicon carbon anode material prepared in Example 6 of the present invention.
  • Example 7 is a diagram showing the mechanical characteristics of the carbon layer material in the silicon-carbon anode material prepared in Example 6 of the present invention.
  • the present invention provides a nano-composite negative electrode material and a preparation method and application thereof.
  • a nano-composite negative electrode material and a preparation method and application thereof.
  • the present invention will be described in further detail below. It should be understood that the specific embodiments described here are only used to explain the present invention, but not to limit the present invention.
  • FIG. 1 is a flowchart of a preferred embodiment of a method for preparing a nanocomposite negative electrode material in the present invention, as shown in the figure, which includes the following steps:
  • the processing residue asphaltene in the petroleum industry is used as the polycyclic organic carbon source, and the solvent transition method is used to regulate the adsorption and self-assembly behavior of the asphaltene on the surface of the nanoparticle with lithium ion intercalation activity.
  • the asphaltene assembly to form a coating layer can optimize the mechanical properties of the composite carbon shell and the charge and discharge characteristics of the overall nanocomposite negative electrode material.
  • Asphaltene is essentially different from asphalt. Asphaltene is the most important component in asphalt. It is rich in functional groups with heteroatoms such as N, O and S. These functional groups can easily interact with surface hydroxyl groups provided by nanoparticles to form molecules. , which makes asphaltenes irreversibly adsorbed on the surface of nanoparticles. At the same time, the asphaltenes contain more polycyclic organic molecular components than asphalt. These polycyclic organic molecular components can occur with each other based on ⁇ bond superposition. Interaction to form a denser coating than asphalt.
  • asphaltene molecules are usually deposited at the bottom of heavy oil industrial distillation towers.
  • Asphaltenes as a broad class of compounds defined by solubility (only soluble in aromatic solvents but not in alkane solvents), have a wide variety of molecules and have a graphene-like structure.
  • the asphaltenes include 3-11 rings of organic polycyclic molecules, and the edges of the rings are connected with branches, and the hydrocarbon molar ratio of the asphaltenes is 0.6-1.1.
  • the assembly (solubility) of each component of asphaltene molecules is very sensitive to solvent properties.
  • the multi-layer 3D network assembly structure has higher stability, for example, it can effectively prevent the collapse of the layers or the re-stacking and agglomeration of the carbon layers during the retracting process.
  • the structure of the final product carbon coating layer is related to the single molecular structure contained in the asphaltene, the adsorption and assembly behavior of the asphaltene under different solvent environments, and the carbonization process conditions (temperature, heating gradient, atmosphere, atmosphere flow rate, carbonization time, etc.) .
  • the inset in Figure 2 is a simplified schematic diagram of the solution phase assembly of polycyclic organic molecules. Asphaltene molecules have a lamellar structure, and the black dots are simplified polymer interactions, such as hydrogen bonds. The direction of the black arrow is the direction of the change of the solvent characteristics, and the upper right corner is the indication of the silicon expansion and the slip of the carbonized layer during the charging process.
  • the present invention uses industrial waste (asphaltene) with a graphene-like structure as a precursor to obtain a graphene-like coated nanocomposite negative electrode material, which has great advantages over other carbon sources in terms of economy and practicability, and can reduce The valuable industrial waste is turned into a new high-value carbon material, achieving the purpose of turning waste into treasure.
  • the outer coating layer of the nano-composite negative electrode material prepared by the method described in the present invention has excellent mechanical properties and better protects the stability of the silicon core during charge and discharge cycles, so that the negative electrode material has high capacity while achieving stability The benefits of long loops.
  • the nanoparticles with lithium ion intercalation activity are one of nano silicon, nano silicon oxide, or nano tin, but it is not limited thereto.
  • the nano particles with lithium ion intercalation activity can be prepared by microwave method, hydrothermal solvothermal method, co-precipitation method, magnesium thermal reduction method, ball milling method or vapor deposition method. Taking the preparation of nano-silicon as an example, nano-silicon dioxide can be used as a raw material, magnesium powder is used as a reducing agent, and acid and alkali are used to wash the reduced by-products and unreduced products after the nano-silicon powder is generated.
  • the diameter of the nanoparticles with lithium ion intercalation activity is 1-150 nm.
  • the thickness of the coating layer formed by adsorbing the asphaltene on the surface of the nanoparticle is 1-100 nm.
  • the nanoparticles and asphaltenes are mixed in a solvent, and the asphaltenes are driven to adsorb on the surface of the nanoparticles and form a coating layer by selecting and controlling the characteristics of the solvent to obtain a composite material precursor.
  • the adsorption of the asphaltenes on the surface of the nanoparticles is completed in a solvent.
  • the solvent can be a single-component oil phase or a multi-component oil phase mixture.
  • the adsorption behavior of the asphaltenes is determined by the The structure of polycyclic aromatic molecules, the type of functional groups contained and their solubility in solvents are determined.
  • the adsorption of asphaltenes on the surface of the silicon substrate is caused by different types of asphaltene mixtures. Determined by molecular size, molecular weight and functional groups, the adsorption layer is mainly composed of asphaltenes with high surface activity.
  • the agglomeration effect based on ⁇ bond interactions between asphaltene molecules is strengthened in the weak solvent environment, which will make
  • the formation method of the adsorption layer is mainly the accumulation of aggregates. Therefore, in addition to the thicker asphaltene adsorption layer in a weak solvent, the ⁇ - ⁇ superposition effect in the adsorption layer is also more obvious than that in a good solvent.
  • coating layers with different thicknesses and different molecular interaction characteristics can be obtained. The thickness of these coating layers and internal molecular interaction behavior will affect their carbonization characteristics under high temperature conditions.
  • the adsorption layer rich in ⁇ - ⁇ stack is easier to form a structural carbonized layer than the supramolecular assembly adsorption layer.
  • coating layers with different structures and mechanical properties can be obtained by adjusting the adsorption behavior of asphaltenes, and then by adjusting the properties of the coating layers to optimize the charge and discharge performance of the negative electrode of the nanocomposite lithium ion battery, such as
  • the increase in porosity can make the coating layer elastic and deform without breaking when subjected to a certain stress.
  • the increase in the distance between the ⁇ - ⁇ layers will facilitate the insertion and diffusion of lithium ions and make the interlayer sliding effect obvious.
  • the multi-layer 3D network assembly structure has higher stability, which can effectively prevent the collapse of the layers or the re-stacking and agglomeration of the carbon layers during the retracting process.
  • the nanoparticles and asphaltenes are mixed in a solvent for 0.1-24 h, so that the asphaltenes are adsorbed on the surface of the nanoparticles and form a coating layer to obtain a composite material precursor.
  • the concentration of the asphaltene in the solvent is 0.01-100 g/L.
  • the composite material precursor in order to ensure that the asphalt forms a stable coating layer on the surface of the nanoparticles, the composite material precursor is heated under an inert atmosphere, the heating temperature is 250-1200°C, and the heating time is 0.5-10h, The nano composite negative electrode material is prepared.
  • a nano composite negative electrode material is also provided, which is prepared by the preparation method of the present invention.
  • an application of the nanocomposite negative electrode material is also provided, and the nanocomposite negative electrode material prepared by the preparation method of the present invention is used as the negative electrode sheet of a lithium ion battery.
  • a preparation method and test of silicon carbon anode material including the following steps:
  • the first step, adsorption add 50mg of silicon particles with a diameter of 100nm to 50-200ml of toluene solution and stir for 24h.
  • the second step drying: centrifuge at 8000rpm/min-10000rpm/min and put in a vacuum oven at 50°C for 12h to remove the solvent.
  • the third step, high-temperature treatment put the silicon powder obtained in the second step in a heating device, and first heat it up to 100°C at 5°C per minute under the protection of inert gas, and then heat it up at 5°C/min after holding it for 10 minutes
  • the temperature is increased at a rate of 800° C., the temperature is kept for 1 hour, and then cooled to room temperature to obtain high-temperature treated nano silicon.
  • the fifth step, battery assembly and electrochemical characteristic test the obtained silicon-carbon negative pole piece is assembled into a half-cell, and its electrochemical performance is tested.
  • the test conditions are: 0.01V-1.5V, 0.03C current cycle is activated for the first time, followed by 200 cycles of charge and discharge cycles at 0.2C current density.
  • a preparation method and test of silicon carbon anode material including the following steps:
  • the first step, asphaltene adsorption add 50mg of silicon powder with a diameter of 100nm to 100ml of 1.0g/L asphaltene molecules in toluene solution, and mechanically stir for 12h to drive the asphaltene molecules to the surface of the core material.
  • the second step drying: After centrifugation at 8000 rpm/min, the supernatant liquid is removed, and the remaining silicon sludge in the tube is dried in a vacuum oven at 50°C for 12 hours to remove the solvent.
  • the third step, high temperature treatment place the obtained asphaltene-coated silicon powder in a heated quartz tube, and heat it up to 100°C at 5°C per minute under the protection of inert gas, and then heat it for 10 minutes at 5°C/min.
  • the temperature increase rate is increased to 800 DEG C, kept for 1 hour, and cooled to room temperature to obtain the high-temperature treated asphaltene adsorption layer coated silicon composite negative electrode material (HTE-Asp-Si-1).
  • the fourth step, ball milling and coating ball milling HTE-Asp-Si, sodium alginate and carbon nanotubes according to the weight ratio (6:2:2) to prepare slurry, and then coating the slurry on the metal foil On the material, after drying, the silicon carbon negative electrode sheet is obtained, and the loading amount is about 0.8 mg/cm 2 .
  • the fifth step, battery assembly and electrochemical characteristic test the obtained silicon-carbon negative pole piece is assembled into a half-cell, and its electrochemical performance is tested.
  • the test conditions are: 0.01V-1.5V, 0.03C current cycle is activated for the first time, followed by 200 cycles of charge and discharge cycles at 0.2C current density.
  • a preparation method and test of silicon carbon anode material including the following steps:
  • the first step, solvent transition method add 50mg of silicon powder with an average diameter of 100nm to the toluene solution of 1.0g/l asphaltene molecules, and slowly drop a certain amount of methanol solution so that the final volume ratio of toluene and methanol is 8:2 , Stirring for 12 hours, drive the first layer of asphaltene molecules to the surface of the core material. After 12 hours, a certain amount of heptane was slowly dropped to make the final volume ratio of the mixed solution of heptane to toluene and methanol 8:2, driving the second layer of asphaltene molecules to the surface of the first layer of asphaltene molecular layer.
  • the second step drying: After centrifugation at 8000 rpm/min, the supernatant liquid is removed, and the remaining silicon sludge in the tube is dried in a vacuum oven at 50°C for 12 hours to remove the solvent.
  • the third step, high temperature treatment place the obtained asphaltene-coated silicon powder in a heated quartz tube, and heat it up to 100°C at 5°C per minute under the protection of inert gas, and then heat it for 10 minutes at 5°C/min.
  • the temperature rise rate is increased to 800° C., kept for 1 hour, and cooled to room temperature to obtain the high-temperature treated asphaltene adsorption layer coated silicon composite negative electrode material (HTE-Asp-Si-2).
  • the fourth step, ball milling and coating ball milling HTE-Asp-Si-2, sodium alginate and carbon nanotubes according to the weight ratio (6:2:2) to obtain slurry, and then coating the slurry on On the metal foil, the silicon carbon negative electrode sheet is obtained after drying, and the loading amount is about 0.8 mg/cm 2 .
  • the fifth step, battery assembly and electrochemical characteristic test the obtained silicon-carbon negative pole piece is assembled into a half-cell, and its electrochemical performance is tested.
  • the test conditions are: 0.01V-1.5V, 0.03C current cycle is activated for the first time, followed by 200 cycles of charge and discharge cycles at 0.2C current density.
  • a preparation method and test of silicon carbon anode material including the following steps:
  • the first step, asphaltene adsorption add 50mg of 100nm diameter silicon powder to 100ml of 1.0g/L asphaltene molecule toluene solution, stir for 12h, drive the asphaltene molecule to the surface of the core material.
  • the second step drying: After centrifugation at 8000 rpm/min, the supernatant liquid is removed, and the remaining silicon sludge in the tube is dried in a vacuum oven at 50°C for 12 hours to remove the solvent.
  • the third step, high temperature treatment place the obtained asphaltene-coated silicon powder in a heated quartz tube, and heat it up to 100°C at 5°C per minute under the protection of inert gas, and then heat it for 10 minutes at 5°C/min.
  • the temperature increase rate is raised to 600°C, kept for 1 hour, and cooled to room temperature to obtain the high-temperature treated asphaltene adsorption layer coated silicon composite negative electrode material (HTE-Asp-Si-3).
  • the fourth step, ball milling and coating ball milling HTE-Asp-Si-3, sodium alginate and carbon nanotubes according to the weight ratio (6:2:2) to obtain slurry, and then coating the slurry on On the metal foil, the silicon-carbon negative electrode sheet is obtained after drying, and the load is about 0.8 mg/cm 2 .
  • the fifth step, battery assembly and electrochemical characteristic test the obtained silicon-carbon negative pole piece is assembled into a half-cell, and its electrochemical performance is tested.
  • the test conditions are: 0.01V-1.5V, 0.03C current cycle is activated for the first time, followed by 200 cycles of charge and discharge cycles at 0.2C current density.
  • a preparation method and test of silicon carbon anode material including the following steps:
  • the first step is the preparation of a water-saturated toluene solution: 20 ml of deionized water is injected into 200 ml of toluene solvent, and after standing for 1 week, the upper layer of toluene solvent is taken out and sealed for use.
  • the second step, asphaltene adsorption dissolve asphaltene in the above water-saturated toluene solution to prepare a 1.0g/L toluene solution, and add 50mg of 50nm diameter silicon powder to 100ml of this asphaltene toluene solution, stir for 12h, A layer of asphaltene molecules drive to the surface of the core material.
  • the third step drying: After centrifugation at 8000 rpm/min, the supernatant liquid is removed, and the remaining silicon sludge in the tube is dried in a vacuum oven at 50°C for 12 hours to remove the solvent.
  • the fourth step, high temperature treatment Put the obtained asphaltene-coated silicon powder in a heated quartz tube, and heat it up to 100°C at 5°C per minute under the protection of inert gas, and then heat it at 5°C/min for 10 minutes.
  • the temperature increase rate is increased to 600° C., held for 1 hour, and cooled to room temperature to obtain a high-temperature treated asphaltene adsorption layer coated silicon composite negative electrode material (HTE-Asp-Si-4).
  • HTE-Asp-Si-4, sodium alginate and carbon nanotubes are ball milled according to the weight ratio (6:2:2) to obtain a slurry, and then the slurry is coated Covered on metal foil and dried to obtain a silicon carbon negative electrode sheet with a load of about 0.8 mg/cm 2 .
  • the sixth step, battery assembly and electrochemical characteristics test the obtained silicon carbon negative pole piece is assembled into a half-cell, and its electrochemical performance is tested.
  • the test conditions are: 0.01V-1.5V, 0.03C current cycle is activated for the first time, followed by 200 cycles of charge and discharge cycles at 0.2C current density.
  • the scanning electron micrograph of the silicon-carbon composite nanomaterial prepared in this example is shown in Figure 3.
  • the carbon layer formed on the surface of the silicon particles is evenly and tightly coated on the surface of the particles and forms a three-dimensional agglomerated network.
  • This structure is beneficial to strengthen the entire material
  • the loose structure is also conducive to stress release during the expansion process and is conducive to enhancing cycle stability.
  • a preparation method and test of silicon carbon anode material including the following steps:
  • the water-saturated toluene solution is prepared: 20 ml of deionized water is injected into 200 ml of toluene solvent, and after standing for 1 week, the upper layer of toluene solvent is taken out and sealed.
  • the second step, asphaltene adsorption dissolve asphaltene in the above water-saturated toluene solution to prepare a 1.5g/L asphaltene toluene solution, and add 50mg of 50nm diameter silicon powder to 100ml of this asphaltene toluene solution and stir for 2h, Drive the first layer of asphaltene molecules to the surface of the core material. Then add a certain amount of heptane solution to make the ratio of toluene and heptane 8:2, and stir for 12 hours to drive the second layer of asphaltene molecules to the surface of the core material.
  • the third step drying: After centrifugation at 8000 rpm/min, the supernatant liquid is removed, and the remaining silicon sludge in the tube is dried in a vacuum oven at 50°C for 12 hours to remove the solvent.
  • the fourth step, high temperature treatment Put the obtained asphaltene-coated silicon powder in a heated quartz tube, and heat it up to 100°C at 5°C per minute under the protection of inert gas, and then heat it at 5°C/min for 10 minutes.
  • the temperature increase rate is raised to 600° C., kept for 1 hour, and cooled to room temperature to obtain the high-temperature treated asphaltene adsorption layer coated silicon composite negative electrode material (HTE-Asp-Si-5).
  • HTE-Asp-Si-5, sodium alginate and carbon nanotubes are ball milled according to the weight ratio (6:2:2) to obtain a slurry, and then the slurry is coated Covered on metal foil and dried to obtain a silicon carbon negative electrode sheet with a load of about 0.8 mg/cm 2 .
  • the sixth step, battery assembly and electrochemical characteristics test the obtained silicon carbon negative pole piece is assembled into a half-cell, and its electrochemical performance is tested.
  • the test conditions are: 0.01V-1.5V, 0.03C current cycle is activated for the first time, followed by 200 cycles of charge and discharge cycles at 0.2C current density.
  • the capacity retention rate after 200 cycles was 90%, and the capacity was 1400 mAh ⁇ g -1 .
  • the scanning electron micrograph of the silicon-carbon composite nanomaterial prepared in this example is shown in FIG. 4.
  • a preparation method and test of silicon carbon anode material including the following steps:
  • the water-saturated toluene solution is prepared: 20 ml of deionized water is injected into 200 ml of toluene solvent, and after standing for 1 week, the upper layer of toluene solvent is taken out and sealed.
  • the second step, asphaltene adsorption dissolve asphaltene in the above water-saturated toluene solution to prepare a 1.5g/L asphaltene toluene solution, and add 50mg of 50nm diameter silicon powder to 100ml of this asphaltene toluene solution and stir for 2h, Drive the first layer of asphaltene molecules to the surface of the core material. Then add a certain amount of heptane solution to make the ratio of toluene and heptane 8:2, and stir for 12 hours to drive the second layer of asphaltene molecules to the surface of the core material.
  • the third step drying: After centrifugation at 8000 rpm/min, the supernatant is removed, and the remaining silicon mud in the tube is dried in a vacuum oven at 50°C for 12 hours to remove the solvent.
  • the fourth step, high temperature treatment Put the obtained asphaltene-coated silicon powder in a heated quartz tube, and heat it up to 100°C at 5°C per minute under the protection of inert gas, and then heat it at 5°C/min for 10 minutes.
  • the temperature rise rate is raised to 380° C., kept for 1 hour, and cooled to room temperature to obtain the high-temperature treated asphaltene adsorption layer coated silicon composite negative electrode material (HTE-Asp-Si-6).
  • HTE-Asp-Si-6, sodium alginate and carbon nanotubes are ball milled according to the weight ratio (6:2:2) to obtain a slurry, and then the slurry is coated Covered on metal foil and dried to obtain a silicon carbon negative electrode sheet with a load of about 0.8 mg/cm 2 .
  • the sixth step, battery assembly and electrochemical characteristics test the obtained silicon carbon negative pole piece is assembled into a half-cell, and its electrochemical performance is tested.
  • the test conditions are: 0.01V-1.5V, 0.03C current cycle is activated for the first time, followed by 400 cycles of charge and discharge at a current density of 0.2C.
  • the long-cycle performance test results in this example are shown in Figure 5.
  • the composite silicon-carbon anode material has excellent cycle stability, and its coulombic efficiency is 87% under the condition of the first charge-discharge cycle with a current density of 0.03C. After the current reaches 0.2C, the reversible capacity is about 1560mAh ⁇ g -1 . After 400 cycles of charge and discharge, the remaining capacity is 1450m mAh ⁇ g -1. The retention rate is about 92.9%, and the average charge and discharge cycle capacity loss is ten thousand minutes. Below bis.
  • the first step is the preparation of a water-saturated toluene solution: 20 ml of deionized water is injected into 200 ml of toluene solvent, and after standing for 1 week, the upper layer of toluene solvent is taken out and sealed for use.
  • the second step, asphaltene adsorption dissolve asphaltene in the above water-saturated toluene solution to prepare a 1.5g/L asphaltene toluene solution, and place 1cm*1cm silicon wafers coated with silica layer vertically on 1.0g/l asphalt
  • the first layer of asphaltene molecules will be driven to the surface of the silicon wafer by letting it stand for 2h in the solution of the quality molecules.
  • add a certain amount of heptane solution to make the ratio of toluene and heptane 8:2, and let it stand for 12 hours to drive the second layer of asphaltene molecules to the surface of the silicon wafer.
  • the third step, high-temperature treatment place the silicon wafers treated with the asphaltene solution in a heating device and heat it under an inert atmosphere, first raise the temperature at 5°C/min to 100°C, hold for 10 minutes, and then heat it at 5°C/min The rate is increased to 600°C, kept for 1 hour, and cooled to room temperature to obtain a silicon wafer coated with a carbon-based adsorption layer on the surface.
  • the fourth step, atomic force microscope test use the PFQNM mode of the Bruker Multimode 8 instrument to test, the probe model is TAP-525, the scanning rate is 0.5Hz, and the carbon-based adsorption layer material is tested.
  • the thickness of the coating layer formed under this system is about 6 nm, and the coating layer presents a network structure. Different sites in the network structure have different elastic modulus (the maximum modulus is 20 GPa). The high modulus region provides the strength of the outer coating layer required for long-cycle stability, while the low modulus region makes the outer coating The cladding has high flexibility in deformation. The test results explain the excellent cycle stability of the silicon carbon anode material synthesized by this method from the side.
  • the preparation method of the nano composite anode material provided by the present invention has the advantages of wide source of raw materials, simple synthesis path, and scalable synthesis scale.
  • the composite anode material includes asphaltene adsorbed on the surface of the nanoparticles.
  • the coating layer has the advantages of high mechanical strength and good ion conductivity after high temperature treatment.
  • the nano composite negative electrode material has high energy density, good cycle stability and a series of high-efficiency lithium battery negative electrodes. At a current density of 107.4mAh ⁇ g -1 (0.03C), the first charge-discharge efficiency of the nanocomposite anode material can reach 87.2%, and the energy density can reach 3195.12mAh ⁇ g -1 .

Abstract

Disclosed are a nano-composite negative electrode material, a preparation method therefor and the use thereof, wherein the method comprises the steps of: (S10) providing nano-particles with lithium ion intercalation activity; (S20) mixing the nano-particles with asphaltene in a solvent, driving the asphaltene to be adsorbed on the surface of the nano-particles and form a coating layer by means of selecting and controlling the properties of the solvent so as to obtain a composite material precursor; and (S30) subjecting the composite material precursor to heating treatment under an inert atmosphere so as to prepare the nano-composite negative electrode material. The preparation method for the nano-composite negative electrode material has the advantages of the raw materials sources being extensive, a simple synthesis path, a scalable synthesis scale, etc. The composite negative electrode material comprises the coating layer formed by adsorbing the asphaltene on the surface of the nano-particles, and the coating layer has the advantages of a high mechanical strength, a good ion conductivity, etc. after high-temperature treatment. The nano-composite negative electrode material has a series of performances required for high-efficiency lithium battery negative electrodes, such as a high energy density, a good cycle stability, etc.

Description

一种纳米复合负极材料及其制备方法与应用Nano composite anode material and preparation method and application thereof 技术领域Technical field
本发明涉及电池领域，尤其涉及一种纳米复合负极材料及其制备方法与应用。The invention relates to the field of batteries, in particular to a nano composite negative electrode material and a preparation method and application thereof.
背景技术Background technique
随着世界各国逐年严格的碳排放标准，新能源汽车的普及已是不可逆转的趋势。新能源汽车对于续航、充放电速率、电池寿命和安全性等性能指标要求日益提高，而目前的锂离子电池的性能还远远满足不了未来需求。未来锂离子电池负电极材料需要具备更快的电子传输性能，更大的锂离子储存容量，更高效的锂离子扩散率，以及更好的充放电循环稳定性。具有这类性质的新型材料对于下一代新型电池的研发和广泛应用至关重要。As countries around the world have strict carbon emission standards year by year, the popularization of new energy vehicles has become an irreversible trend. New energy vehicles have increasingly higher requirements for performance indicators such as battery life, charge and discharge rate, battery life and safety, and the current performance of lithium-ion batteries is far from meeting future needs. In the future, negative electrode materials for lithium-ion batteries need to have faster electron transport performance, greater lithium ion storage capacity, more efficient lithium ion diffusivity, and better charge-discharge cycle stability. New materials with such properties are essential for the development and wide application of next-generation new batteries.
目前主流的商业化锂离子电池常采用锂化过渡金属氧化物作为正极，石墨作为电池负极。石墨负极材料具有热稳定性高、化学稳定性好、导电性好、锂离子入嵌和脱嵌效率高、成本低廉等一系列卓越的特性。然而，其最大理论容量仅为372mAh·g -1，极大限制了单组份石墨负极电池的能量密度。在所有研究过的负极材料中，一些材料具备比石墨更高的理论容量，如氧化亚硅的理论容量可达到1600mAh·g -1，硅的理论能量密度可达4200mAh·g -1，远高于石墨的能量密度。但是这些材料作为负极材料的劣势在于其在锂化过程中常伴随着巨大的体积膨胀。以硅为例，在完全锂化状态下，该膨胀率可以达到近400％。如此高的膨胀率对于硅的内部结构产生巨大的应力，在多次充放电过程中，硅材料容易发生粉化，进而造成负极材料的能量密度随着充放电循环次数大幅降低。活性材料界面上的固体电解质(SEI)会在材料膨胀过程中发生破裂，新暴露的活性表面会与电解液持续反应，造成电解液大量消耗，同时SEI膜过度生长，也会使得锂离子扩散受到影响，进一步加剧容量降低。 At present, mainstream commercial lithium-ion batteries often use lithiated transition metal oxide as the positive electrode and graphite as the battery negative electrode. Graphite anode materials have a series of excellent characteristics such as high thermal stability, good chemical stability, good conductivity, high efficiency of lithium ion insertion and extraction, and low cost. However, its maximum theoretical capacity is only 372mAh·g -1 , which greatly limits the energy density of the single-component graphite anode battery. Among all the anode materials studied, some materials have a higher theoretical capacity than graphite. For example, the theoretical capacity of silicon oxide can reach 1600mAh·g -1 , and the theoretical energy density of silicon can reach 4200mAh·g -1 , which is much higher. The energy density of graphite. However, the disadvantage of these materials as negative electrode materials is that they are often accompanied by huge volume expansion during the lithiation process. Taking silicon as an example, in the fully lithiated state, the expansion rate can reach nearly 400%. Such a high expansion rate causes huge stress on the internal structure of silicon. During multiple charge and discharge processes, the silicon material is prone to pulverization, which in turn causes the energy density of the negative electrode material to decrease significantly with the number of charge and discharge cycles. The solid electrolyte (SEI) on the active material interface will rupture during the expansion of the material. The newly exposed active surface will continue to react with the electrolyte, causing a large amount of electrolyte consumption. At the same time, the excessive growth of the SEI film will also cause lithium ion diffusion Influence, further aggravate the capacity reduction.
研究发现，用Si-C复合材料做锂离子电池负极材料，硅作为活性物质可提供高的储电容量，而碳作为包覆相或者骨架可以有效地减少硅之间的聚合，并在充放电过程中 缓冲硅的体积变化，同时碳的良好导电性可以改善硅材料的电子传导性能，因此将碳-硅复合材料作为锂离子电池负极材料前景诱人，这也使得Si-C复合负极材料体系成为当前负极材料研究的热点。Studies have found that using Si-C composite materials as anode materials for lithium-ion batteries, silicon as an active material can provide high storage capacity, and carbon as a coating phase or skeleton can effectively reduce the polymerization between silicon, and is In the process, the volume change of silicon is buffered, and the good conductivity of carbon can improve the electronic conductivity of silicon materials. Therefore, the prospect of using carbon-silicon composite materials as anode materials for lithium-ion batteries is attractive, which also makes the Si-C composite anode material system It has become a hot spot in current research on anode materials.
Niu等人采用球磨法将硅颗粒分散在石墨溶胶(Graphite Gel)中，并将该溶胶与PVDF(85wt％:15wt％)混合并涂抹于20×20微米的铜片上制备成锂离子电池负极材料。该电极材料的充放电循环性能好于一般的硅颗粒电极。他们将提升的循环稳定性归功于凝胶3D结构在硅充放电过程中提供的体积膨胀缓冲效应【Electrochemical and Solid-State Letters,2002.5(6):p.A107-A110】。Wang等人利用一种简单的两步化学沉积法将纳米硅点沉积于碳纳米管表面，制备出的碳-硅复合材料负极达到了2000mAh·g -1的高容量，并且在多次循环后发现每次循环的容量损失仅为0.15％【ACS Nano,2010.4(4):p.2233-2241】。Liu等人报道了一种用于锂离子电池负极的新型硅纳米线-碳织物复合材料【Scientific reports,2013.3；p.1622】。研究发现将CVD法制备的硅纳米线均匀的涂抹于3D的碳织物骨架上并在惰性气体中加热到300℃可以提高硅与碳的结合力，由此制备出的复合材料有优良的容量(2950mAh·g -1，0.2C)，好的循环稳定性(200次充放电循环后剩余900mAh·g -1)以及好的温度、湿度和形变稳定性。其中碳织物骨架为负极材料提供了优良的电子传输通道，也缓冲了硅体积变化产生的应力。与此同时由于硅颗粒与碳骨架紧密结合，并被禁锢于碳基材之中，使得硅与硅之间的相互作用也大大减弱，达到减缓硅粒聚合的目的。 Niu et al. used a ball milling method to disperse silicon particles in a graphite sol (Graphite Gel), mixed the sol with PVDF (85wt%: 15wt%) and smeared it on a 20×20 micron copper sheet to prepare a lithium-ion battery anode material . The charge-discharge cycle performance of the electrode material is better than that of the general silicon particle electrode. They attributed the improved cycle stability to the volume expansion buffer effect provided by the gel 3D structure during silicon charging and discharging [Electrochemical and Solid-State Letters, 2002.5(6): p.A107-A110]. Wang et al. used a simple two-step chemical deposition method to deposit nano-silicon dots on the surface of carbon nanotubes, and the prepared carbon-silicon composite anode reached a high capacity of 2000mAh·g -1 , and after many cycles It is found that the capacity loss per cycle is only 0.15% [ACS Nano, 2010.4(4): p. 2233-2241]. Liu et al. reported a new type of silicon nanowire-carbon fabric composite material for the anode of lithium-ion batteries [Scientific reports, 2013.3; p.1622]. Research has found that evenly spreading silicon nanowires prepared by CVD method on the 3D carbon fabric skeleton and heating to 300°C in an inert gas can increase the bonding force between silicon and carbon, and the composite material prepared thereby has excellent capacity ( 2950mAh·g -1 , 0.2C), good cycle stability (900mAh·g -1 remaining after 200 charge and discharge cycles) and good temperature, humidity and deformation stability. Among them, the carbon fabric skeleton provides an excellent electron transmission channel for the negative electrode material, and also buffers the stress caused by the volume change of silicon. At the same time, because the silicon particles are closely combined with the carbon skeleton and are imprisoned in the carbon substrate, the interaction between silicon and silicon is also greatly weakened, so as to achieve the purpose of slowing down the polymerization of silicon particles.
碳-硅复合材料是一种适合作为锂电池负极的新型材料，然而到目前为止，大多数碳-硅复合材料仍具有不可回避的问题：1)大部分具有复杂形貌的碳-硅复合电极材料的制备工艺非常复杂，制备成本过高，很难实现放大化生产；2)大多数碳-硅负极材料中硅组分与碳组分之间的结合力不够强，随着充放电过程中硅的体积变化，硅碳结合容易剥落，造成材料失效，导致电极材料循环稳定性不理想；3)目前大多数新型碳-硅复合负极材料仅着力于提高材料的质量能量密度，因而一味追求疏松型结构，而这类疏松结构材料的体积容量密度非常低，因此提高电极的体积容量密度也具有重要意义。Carbon-silicon composite material is a new type of material suitable as a negative electrode for lithium batteries. However, so far, most carbon-silicon composite materials still have unavoidable problems: 1) Most carbon-silicon composite electrodes with complex morphology The preparation process of the material is very complicated, the preparation cost is too high, and it is difficult to achieve scale-up production; 2) The bonding force between the silicon component and the carbon component in most carbon-silicon anode materials is not strong enough, as the charge and discharge process The volume change of silicon makes the silicon-carbon bond easy to peel off, resulting in material failure, resulting in unsatisfactory cycle stability of electrode materials; 3) At present, most new carbon-silicon composite anode materials only focus on improving the quality and energy density of the material, so they blindly pursue looseness The volume capacity density of such loose structure materials is very low, so it is also of great significance to increase the volume capacity density of the electrode.
从规模化应用的层面考虑，由于纳米球形硅粉较之于其他形貌的硅基材料具有价格便宜且可以大规模生产的优势，更能胜任商业化电极材料的应用。在纳米硅球表面包覆碳层可以增加硅基材料的导电性，为锂离子的嵌入和脱出提供良好的通道，同时由于其制备工艺简单，材料成本低，且保留了大部分硅体积作为活性物质，进而得到比其它形貌碳-硅复合材料更高的体容量。碳包硅的形态被认为是最有希望的碳-硅负极材料结构。硅活性材料表面的碳层一般由气相或者液相包覆来完成，即利用将碳源通过气体介质或者液体介质使之在活性物质表面沉积。From the perspective of large-scale application, because nano-spherical silicon powder has the advantage of being cheaper and can be mass-produced compared with other silicon-based materials, it is more qualified for the application of commercial electrode materials. Coating the carbon layer on the surface of the nano silicon ball can increase the conductivity of the silicon-based material and provide a good channel for the insertion and extraction of lithium ions. At the same time, due to its simple preparation process, low material costs, and retain most of the silicon volume as active Substances, and then get higher volume capacity than other morphology carbon-silicon composite materials. The morphology of silicon-on-carbon is considered the most promising carbon-silicon anode material structure. The carbon layer on the surface of the silicon active material is generally coated by gas or liquid phase, that is, the carbon source is deposited on the surface of the active material by passing the carbon source through a gas medium or a liquid medium.
专利(CN107221673A)公开了一种硅基材表面复合碳层的制备方法，利用气相或者热包覆法对硅粉进行碳包覆后，将其放入沥青溶液中生长得到有硅颗粒嵌入的碳微球，之后再碳化得到硅碳复合材料。该材料具有500-600mAh·g -1的高容量，且具有首次库仑效率高、循环性能稳定、压实密度高、电极结构稳定等优点。 The patent (CN107221673A) discloses a method for preparing a composite carbon layer on the surface of a silicon substrate. After the silicon powder is coated with carbon by a gas phase or thermal coating method, it is placed in a pitch solution and grown to obtain a carbon embedded with silicon particles. The microspheres are then carbonized to obtain a silicon-carbon composite material. The material has a high capacity of 500-600mAh·g -1 , and has the advantages of high first-time Coulombic efficiency, stable cycle performance, high compaction density, and stable electrode structure.
专利(CN105789576B)公开了一种硅基负极材料的制备方法，即将碳材料、硅材料、粘结剂和导电剂制备成浆料后，喷雾干燥造粒形成5μm～35μm的颗粒，烧结碳化后，打散再利用沥青作为粘结剂二次造粒，烧结碳化打撒后在用同样的方法三次造粒得到负极材料。其碳化温度在800-1000℃之间，制备得到的负极材料0.1C可逆容量为650mAh·g -1,初始效率88％，10C的可逆容量为542mAh·g -1，容量保持为0.1C的83％，0.1C 100周容量保持率为96.5％。 The patent (CN105789576B) discloses a method for preparing a silicon-based negative electrode material, which is to prepare a slurry of carbon material, silicon material, binder and conductive agent, spray drying and granulation to form 5μm～35μm particles, after sintering and carbonization, Disperse and reuse the asphalt as a binder for secondary granulation. After sintering, carbonization and dispersing, the negative electrode material is obtained by three granulation in the same way. Its carbonization temperature is between 800-1000℃, and the prepared negative electrode material has a 0.1C reversible capacity of 650mAh·g -1 , an initial efficiency of 88%, a 10C reversible capacity of 542mAh·g -1 , and a capacity maintained at 0.1C of 83 %, 0.1C 100-week capacity retention rate is 96.5%.
以上方法得到的材料虽循环稳定性较好，但容量普遍偏低，这一问题主要是由于制备中采用了较厚的碳层。由于工艺中采用的碳化温度高，碳化程度大，使得碳层过脆，需要采用较大厚度才可保持循环稳定性。另一方面，沥青中所含大部分组份与硅表面的结合力并不强，且硅表面由于富含羟基基团呈亲水特性，故上述方法需要事先对硅表面进行碳包覆(疏水化)处理后才可将硅粉在沥青溶液中分散，工序繁杂的同时，进一步减少活性物质在复合材料中的占比，降低整体能量密度。Although the materials obtained by the above methods have good cycle stability, the capacity is generally low. This problem is mainly due to the thicker carbon layer used in the preparation. Due to the high carbonization temperature and high degree of carbonization used in the process, the carbon layer is too brittle, and a large thickness is required to maintain cycle stability. On the other hand, most of the components contained in the pitch do not have strong binding force to the silicon surface, and the silicon surface is hydrophilic due to its rich hydroxyl groups, so the above method requires carbon coating (hydrophobic) on the silicon surface in advance. The silicon powder can be dispersed in the asphalt solution only after chemical treatment. While the process is complicated, it further reduces the proportion of active substances in the composite material and reduces the overall energy density.
因此，现有技术还有待于改进和发展。Therefore, the existing technology needs to be improved and developed.
发明内容Summary of the invention
鉴于上述现有技术的不足，本发明的目的在于提供一种纳米复合材料及其制备方法与应用，旨在解决现有硅基负极材料容量低、循环稳定性不高的问题。In view of the foregoing shortcomings of the prior art, the purpose of the present invention is to provide a nanocomposite material and its preparation method and application, aiming to solve the problems of low capacity and low cycle stability of existing silicon-based negative electrode materials.
本发明的技术方案如下：The technical scheme of the present invention is as follows:
一种纳米复合负极材料的制备方法，其中，包括步骤：A method for preparing a nano composite negative electrode material, which comprises the following steps:
提供一种具有锂离子插嵌活性的纳米颗粒；Provide a nanoparticle with lithium ion intercalation activity;
将所述纳米颗粒与沥青质在溶剂中混合，通过选择和控制溶剂特性驱动沥青质在所述纳米颗粒表面吸附并形成包覆层，得到复合材料前驱体；Mixing the nanoparticles and asphaltenes in a solvent, and driving the asphaltenes to adsorb on the surface of the nanoparticles and forming a coating layer by selecting and controlling the characteristics of the solvent to obtain a composite material precursor;
在惰性气氛下对所述复合材料前驱体进行加热处理，制得所述纳米复合负极材料。The composite material precursor is heated under an inert atmosphere to prepare the nano composite negative electrode material.
所述纳米复合负极材料的制备方法，其特征在于，所述具有锂离子插嵌活性的纳米颗粒为纳米硅、纳米亚氧化硅或纳米锡中的一种。The method for preparing the nano composite negative electrode material is characterized in that the nano particles with lithium ion intercalation activity are one of nano silicon, nano silicon oxide or nano tin.
所述纳米复合负极材料的制备方法，其中，所述具有锂离子插嵌活性的纳米颗粒的直径为1-150nm。The method for preparing the nano composite negative electrode material, wherein the diameter of the nano particles with lithium ion intercalation activity is 1-150 nm.
所述纳米复合负极材料的制备方法，其中，所述沥青质包括3-11个环的有机多环分子，所述沥青质的碳氢摩尔比为0.6-1.1。In the preparation method of the nanocomposite negative electrode material, the asphaltene includes 3-11 rings of organic polycyclic molecules, and the hydrocarbon molar ratio of the asphaltene is 0.6-1.1.
所述纳米复合负极材料的制备方法，其中，将所述纳米颗粒与沥青质在溶剂中混合0.1-24h，通过选择和控制溶剂特性驱动沥青质在所述纳米颗粒表面吸附并形成包覆层，得到复合材料前驱体。The method for preparing the nanocomposite negative electrode material, wherein the nanoparticles and asphaltenes are mixed in a solvent for 0.1-24 hours, and the asphaltenes are driven to adsorb on the surface of the nanoparticles and form a coating layer by selecting and controlling the characteristics of the solvent. The composite precursor is obtained.
所述纳米复合负极材料的制备方法，其中，所述沥青质在溶剂中的浓度为0.01-100g/L。The method for preparing the nanocomposite negative electrode material, wherein the concentration of the asphaltene in the solvent is 0.01-100 g/L.
所述纳米复合负极材料的制备方法，其中，所述沥青质吸附在纳米颗粒表面形成的包覆层的厚度为1-100nm。In the preparation method of the nano composite negative electrode material, the thickness of the coating layer formed by the asphaltene adsorbed on the surface of the nano particles is 1-100 nm.
所述纳米复合负极材料的制备方法，其中，所述在惰性气氛下对所述复合材料前驱体进行加热处理，制得所述纳米复合负极材料的步骤中，加热温度为250-1200℃，加热时间为0.5-10h。The method for preparing the nano-composite negative electrode material, wherein, in the step of heating the composite material precursor under an inert atmosphere to prepare the nano-composite negative electrode material, the heating temperature is 250-1200°C, and the heating The time is 0.5-10h.
一种纳米复合负极材料，其中，采用本发明制备方法制备得到。A nano composite negative electrode material, which is prepared by the preparation method of the present invention.
一种纳米复合负极材料的应用，其中，将本发明制备方法制得的纳米复合负极材料 用作锂离子电池负极片。An application of a nano-composite negative electrode material, wherein the nano-composite negative electrode material prepared by the preparation method of the present invention is used as a negative electrode sheet of a lithium ion battery.
有益效果：本发明提供的纳米复合负极材料的制备方法具有原料来源广、合成路径简单、合成规模可放大等优点，所述复合负极材料包括由沥青质吸附在所述纳米颗粒表面形成的包覆层，所述包覆层经高温处理后具有机械强度高、离子传导性能好等优点，该纳米复合负极材料具有能量密度高，循环稳定性好等一系列高效锂电池负极所需性能。在107.4mAh·g -1(0.03C)的电流密度下，该纳米复合负极材料首次充放电效率可达87.2％，能量密度达到3195.12mAh·g -1。在稳定性测试的后续循环过程中，当采用电流密度为715.8mAh·g -1(0.2C)时，其可逆容量约为1565.11mAh·g -1，且在连续充放电400次后，剩余能量密度约为1441.48mAh·g -1，其容量保持率为92.96％，平均每次充放电能量密度损失在万分之二以下。 Beneficial effects: The preparation method of the nano composite negative electrode material provided by the present invention has the advantages of wide source of raw materials, simple synthesis path, scalable synthesis scale, etc. The composite negative electrode material includes a coating formed by adsorbing asphaltene on the surface of the nano particles. After high temperature treatment, the coating layer has the advantages of high mechanical strength and good ion conductivity. The nano composite negative electrode material has high energy density, good cycle stability and a series of high-efficiency lithium battery negative electrodes. At a current density of 107.4mAh·g -1 (0.03C), the first charge-discharge efficiency of the nanocomposite anode material can reach 87.2%, and the energy density can reach 3195.12mAh·g -1 . In the subsequent cycles of the stability test, when the current density is 715.8mAh·g -1 (0.2C), its reversible capacity is about 1565.11mAh·g -1 , and after 400 continuous charging and discharging, the remaining energy The density is about 1441.48mAh·g -1 , its capacity retention rate is 92.96%, and the average energy density loss per charge and discharge is less than two ten thousandths.
附图说明Description of the drawings
图1为本发明一种纳米复合负极材料的制备方法中较佳实施例的流程图。FIG. 1 is a flowchart of a preferred embodiment of a method for preparing a nanocomposite negative electrode material of the present invention.
图2为本发明溶剂过渡法制备纳米复合负极材料的原理示意图。Fig. 2 is a schematic diagram of the principle of preparing a nanocomposite negative electrode material by the solvent transition method of the present invention.
图3为本发明实施例4中的纳米复合负极材料的扫描电镜示意图。3 is a schematic diagram of a scanning electron microscope of the nanocomposite anode material in Example 4 of the present invention.
图4为本发明实施例5中的纳米复合负极材料的扫描电镜示意图。4 is a schematic diagram of a scanning electron microscope of the nanocomposite anode material in Example 5 of the present invention.
图5为本发明实施例6中的硅碳负极片做成锂离子电池的长循环性能，其中横坐标为循环次数，纵坐标为放电比容量。Fig. 5 shows the long cycle performance of a lithium-ion battery made from the silicon-carbon negative electrode sheet in Example 6 of the present invention, where the abscissa is the number of cycles, and the ordinate is the specific discharge capacity.
图6为本发明实施例6中制备的硅碳负极材料中碳层材料的原子力显微镜微观形貌图。6 is an atomic force microscope microscopic morphology diagram of the carbon layer material in the silicon carbon anode material prepared in Example 6 of the present invention.
图7为本发明实施例6中制备的硅碳负极材料中碳层材料的力学特性表征图。7 is a diagram showing the mechanical characteristics of the carbon layer material in the silicon-carbon anode material prepared in Example 6 of the present invention.
具体实施方式detailed description
本发明提供一种纳米复合负极材料及其制备方法与应用，为使本发明的目的、技术方案及效果更加清楚、明确，以下对本发明进一步详细说明。应当理解，此处所描述的具体实施例仅仅用以解释本发明，并不用于限定本发明。The present invention provides a nano-composite negative electrode material and a preparation method and application thereof. In order to make the purpose, technical scheme and effect of the present invention clearer and clearer, the present invention will be described in further detail below. It should be understood that the specific embodiments described here are only used to explain the present invention, but not to limit the present invention.
请参阅图1，图1为本发明中一种纳米复合负极材料的制备方法中的较佳实施例的流程图，如图所示，其中，包括以下步骤：Please refer to FIG. 1. FIG. 1 is a flowchart of a preferred embodiment of a method for preparing a nanocomposite negative electrode material in the present invention, as shown in the figure, which includes the following steps:
S10、提供一种具有锂离子插嵌活性的纳米颗粒；S10. Provide a nanoparticle with lithium ion intercalation activity;
S20、将所述纳米颗粒与沥青质在溶剂中混合，使所述沥青质吸附在所述纳米颗粒表面并形成包覆层，得到复合材料前驱体；S20. Mix the nanoparticles and asphaltenes in a solvent, so that the asphaltenes are adsorbed on the surface of the nanoparticles and form a coating layer to obtain a composite material precursor;
S30、在惰性气氛下对所述复合材料前驱体进行加热处理，制得所述纳米复合负极材料。S30, heating the composite material precursor under an inert atmosphere to prepare the nano composite negative electrode material.
本实施方式通过采用石油工业中的加工残渣沥青质作为多环有机碳源，利用溶剂过渡法调控所述沥青质在所述具有锂离子插嵌活性的纳米颗粒表面的吸附、自组装行为，所述沥青质组装形成包覆层可优化复合碳壳的力学性能以及整体纳米复合负极材料的充放电特性。In this embodiment, the processing residue asphaltene in the petroleum industry is used as the polycyclic organic carbon source, and the solvent transition method is used to regulate the adsorption and self-assembly behavior of the asphaltene on the surface of the nanoparticle with lithium ion intercalation activity. The asphaltene assembly to form a coating layer can optimize the mechanical properties of the composite carbon shell and the charge and discharge characteristics of the overall nanocomposite negative electrode material.
沥青质与沥青具有本质上的不同，沥青质是沥青中最主要的组份，其富含具有N、O、S等杂原子的官能团，这些官能团极易与纳米颗粒提供的表面羟基形成分子交互，使沥青质在纳米颗粒表面发生不可逆吸附，同时沥青质内部含有的多环有机分子组份远比沥青中的多，这些多环有机分子组份可以相互发生以π键叠加作为基础的分子间相互作用，形成较沥青更为致密的包覆层。Asphaltene is essentially different from asphalt. Asphaltene is the most important component in asphalt. It is rich in functional groups with heteroatoms such as N, O and S. These functional groups can easily interact with surface hydroxyl groups provided by nanoparticles to form molecules. , Which makes asphaltenes irreversibly adsorbed on the surface of nanoparticles. At the same time, the asphaltenes contain more polycyclic organic molecular components than asphalt. These polycyclic organic molecular components can occur with each other based on π bond superposition. Interaction to form a denser coating than asphalt.
作为石油炼制的废弃产物，沥青质分子通常沉积于重油工业蒸馏塔底部，作为碳源，具有来源广、价值低等优势。沥青质作为由溶解度(仅溶于芳香类溶剂而不溶于烷烃类溶剂)界定的大类化合物，其分子种类繁多，具有类石墨烯结构。本实施例优选所述沥青质包括3-11个环的有机多环分子，且环的边缘接有支链，所述沥青质的碳氢摩尔比为0.6-1.1。沥青质各组分分子的组装(溶解度)对溶剂性质十分敏感，当多组分沥青质溶解入溶剂中并通过一定速率改变溶剂特性时，由于不同结构的类沥青质分子对溶剂特征变化的响应不同，会得到由溶剂性质变化决定的不同吸附层结构。这些吸附层的结构会对碳包纳米颗粒材料作为锂电池负极的性能产生重要影响，比方说包覆层内的空隙度可以使得包覆层具有弹性，受到一定应力时可发生形变而不破裂，而层间距离的加大会对锂离子的嵌入和扩散提供便利，并且使得层间滑动效应明显，从而更好应对硅基材充 放电过程中的体积变化，优化纳米负极复合材料在充放电过程中的循环稳定性。同时多层3D网状组装结构拥有更高的稳定性，比如说可以有效的防止层间的坍塌或者碳层在收放过程中的重新堆叠团聚。最终产物碳包覆层的结构与沥青质中包含的单分子结构、不同溶剂环境下沥青质的吸附组装行为，和碳化过程条件(温度、升温梯度、气氛、气氛流速、碳化时间等因素)相关。图2中插图为简化多环有机分子溶液体相组装示意图，沥青质分子为片层结构，黑点为简化的聚合体间的相互作用，如氢键等。黑色箭头方向为溶剂特性变化方向的方向，右上角为充电过程硅膨胀与碳化层滑移示意。As a waste product of petroleum refining, asphaltene molecules are usually deposited at the bottom of heavy oil industrial distillation towers. As a carbon source, it has the advantages of wide sources and low value. Asphaltenes, as a broad class of compounds defined by solubility (only soluble in aromatic solvents but not in alkane solvents), have a wide variety of molecules and have a graphene-like structure. In this embodiment, it is preferable that the asphaltenes include 3-11 rings of organic polycyclic molecules, and the edges of the rings are connected with branches, and the hydrocarbon molar ratio of the asphaltenes is 0.6-1.1. The assembly (solubility) of each component of asphaltene molecules is very sensitive to solvent properties. When multi-component asphaltenes dissolve into the solvent and change the solvent properties at a certain rate, the response of asphaltene-like molecules with different structures to changes in solvent characteristics Different, will get different adsorption layer structure determined by the change of solvent properties. The structure of these adsorption layers will have an important impact on the performance of carbon-coated nanoparticle materials as the negative electrode of lithium batteries. For example, the porosity in the coating layer can make the coating layer elastic, and it can deform without breaking under certain stress. The increase of the interlayer distance will facilitate the insertion and diffusion of lithium ions, and make the interlayer sliding effect obvious, so as to better cope with the volume change of the silicon substrate during the charge and discharge process, and optimize the nano-anode composite material in the charge and discharge process的cyclic stability. At the same time, the multi-layer 3D network assembly structure has higher stability, for example, it can effectively prevent the collapse of the layers or the re-stacking and agglomeration of the carbon layers during the retracting process. The structure of the final product carbon coating layer is related to the single molecular structure contained in the asphaltene, the adsorption and assembly behavior of the asphaltene under different solvent environments, and the carbonization process conditions (temperature, heating gradient, atmosphere, atmosphere flow rate, carbonization time, etc.) . The inset in Figure 2 is a simplified schematic diagram of the solution phase assembly of polycyclic organic molecules. Asphaltene molecules have a lamellar structure, and the black dots are simplified polymer interactions, such as hydrogen bonds. The direction of the black arrow is the direction of the change of the solvent characteristics, and the upper right corner is the indication of the silicon expansion and the slip of the carbonized layer during the charging process.
本发明使用具有类石墨烯结构的工业废渣(沥青质)作为前驱物获得具有类石墨烯包覆的纳米复合负极材料，在经济性，实用性上较其他碳源具有很大优势，可将低价值的工业废料变为高价值的新型碳材料，达到变废为宝的目的。利用本发明描述的方法制备的纳米复合负极材料的外包覆层具有优良的力学特性，较好的保护硅内核在充放电循环中的稳定性，使得该负极材料具有高容量的同时，达到稳定长循环的裨益。The present invention uses industrial waste (asphaltene) with a graphene-like structure as a precursor to obtain a graphene-like coated nanocomposite negative electrode material, which has great advantages over other carbon sources in terms of economy and practicability, and can reduce The valuable industrial waste is turned into a new high-value carbon material, achieving the purpose of turning waste into treasure. The outer coating layer of the nano-composite negative electrode material prepared by the method described in the present invention has excellent mechanical properties and better protects the stability of the silicon core during charge and discharge cycles, so that the negative electrode material has high capacity while achieving stability The benefits of long loops.
在一些实施方式中，所述具有锂离子插嵌活性的纳米颗粒为纳米硅、纳米氧化亚硅或纳米锡中的一种，但不限于此。所述具有锂离子插嵌活性的纳米颗粒可采用微波法、水热溶剂热法、共沉淀法、镁热还原法、球磨法或气相沉积法制备得到。以制备纳米硅为例，可利用纳米二氧化硅为原料，镁粉为还原剂，生成纳米硅粉后利用酸和碱洗去还原副产物和未还原产物。In some embodiments, the nanoparticles with lithium ion intercalation activity are one of nano silicon, nano silicon oxide, or nano tin, but it is not limited thereto. The nano particles with lithium ion intercalation activity can be prepared by microwave method, hydrothermal solvothermal method, co-precipitation method, magnesium thermal reduction method, ball milling method or vapor deposition method. Taking the preparation of nano-silicon as an example, nano-silicon dioxide can be used as a raw material, magnesium powder is used as a reducing agent, and acid and alkali are used to wash the reduced by-products and unreduced products after the nano-silicon powder is generated.
在一些实施方式中，所述具有锂离子插嵌活性的纳米颗粒的直径为1-150nm。In some embodiments, the diameter of the nanoparticles with lithium ion intercalation activity is 1-150 nm.
在一些实施方式中，所述沥青质吸附在纳米颗粒表面形成的包覆层的厚度为1-100nm。In some embodiments, the thickness of the coating layer formed by adsorbing the asphaltene on the surface of the nanoparticle is 1-100 nm.
在一些实施方式中，所述将所述纳米颗粒与沥青质在溶剂中混合，通过选择和控制溶剂特性驱动沥青质在所述纳米颗粒表面吸附并形成包覆层，得到复合材料前驱体。本实施方式中，所述沥青质在纳米颗粒表面的吸附在溶剂中完成，所述溶剂可以是单组份油相或多组分油相混合物，所述沥青质的吸附行为由其所包含的多环芳香分子结构、所含官能团类型及其在溶剂中的溶解度决定。具体来讲，在良溶剂环境中(如苯，甲苯等芳香烃类化合物可使沥青质分子处于高分散状态的溶剂中)，沥青质在硅基材表面的 吸附由沥青质混合物中不同类型的分子大小、分子量和官能团决定，吸附层主要由具有高表面活性的沥青质组成。在弱溶剂中(如长链烷烃、醇等使沥青质分子处于较低分散状态的溶剂中)，由于沥青质分子间以π键相互作用为基础的团聚效应在弱溶剂环境中加强，将使得吸附层的形成方式以团聚体堆积为主，因此在弱溶剂中的沥青质吸附层除了厚度更大以外，吸附层内的π-π叠加效应也较良溶剂中更为明显。通过调节溶剂的特性和先后加入次序可得到不同厚度且内部具有不同分子交互特性的包覆层。这些包覆层的厚薄和内部分子相互作用行为又会影响其在高温条件下的碳化特性，如富含π-π叠加的吸附层较超分子组装吸附层更容易形成结构型碳化层。藉由上述规律可通过调控沥青质的吸附行为得到具有不同结构和力学特性的包覆层，进而通过包覆层特性调节来优化纳米复合锂离子电池负极的充放电性能，如包覆层内的空隙度增加可以使得包覆层具有弹性，受到一定应力时可发生形变而不破裂，而π-π层间距离的加大会对锂离子的嵌入和扩散提供便利，并且使得层间滑动效应明显，从而更好应对硅基材充放电过程中的体积变化，优化纳米负极复合材料在充放电过程中的循环稳定性。同时多层3D网状组装结构拥有更高的稳定性，可有效的防止层间的坍塌或者碳层在收放过程中的重新堆叠团聚。In some embodiments, the nanoparticles and asphaltenes are mixed in a solvent, and the asphaltenes are driven to adsorb on the surface of the nanoparticles and form a coating layer by selecting and controlling the characteristics of the solvent to obtain a composite material precursor. In this embodiment, the adsorption of the asphaltenes on the surface of the nanoparticles is completed in a solvent. The solvent can be a single-component oil phase or a multi-component oil phase mixture. The adsorption behavior of the asphaltenes is determined by the The structure of polycyclic aromatic molecules, the type of functional groups contained and their solubility in solvents are determined. Specifically, in a good solvent environment (such as benzene, toluene and other aromatic hydrocarbon compounds can make the asphaltene molecules in a highly dispersed solvent), the adsorption of asphaltenes on the surface of the silicon substrate is caused by different types of asphaltene mixtures. Determined by molecular size, molecular weight and functional groups, the adsorption layer is mainly composed of asphaltenes with high surface activity. In weak solvents (such as long-chain alkanes, alcohols and other solvents that make asphaltene molecules in a lower dispersion state), the agglomeration effect based on π bond interactions between asphaltene molecules is strengthened in the weak solvent environment, which will make The formation method of the adsorption layer is mainly the accumulation of aggregates. Therefore, in addition to the thicker asphaltene adsorption layer in a weak solvent, the π-π superposition effect in the adsorption layer is also more obvious than that in a good solvent. By adjusting the characteristics of the solvent and the sequential addition order, coating layers with different thicknesses and different molecular interaction characteristics can be obtained. The thickness of these coating layers and internal molecular interaction behavior will affect their carbonization characteristics under high temperature conditions. For example, the adsorption layer rich in π-π stack is easier to form a structural carbonized layer than the supramolecular assembly adsorption layer. According to the above rules, coating layers with different structures and mechanical properties can be obtained by adjusting the adsorption behavior of asphaltenes, and then by adjusting the properties of the coating layers to optimize the charge and discharge performance of the negative electrode of the nanocomposite lithium ion battery, such as The increase in porosity can make the coating layer elastic and deform without breaking when subjected to a certain stress. The increase in the distance between the π-π layers will facilitate the insertion and diffusion of lithium ions and make the interlayer sliding effect obvious. Thereby, it can better deal with the volume change of the silicon substrate during the charge and discharge process, and optimize the cycle stability of the nano anode composite material during the charge and discharge process. At the same time, the multi-layer 3D network assembly structure has higher stability, which can effectively prevent the collapse of the layers or the re-stacking and agglomeration of the carbon layers during the retracting process.
在一些实施方式中，将所述纳米颗粒与沥青质在溶剂中混合0.1-24h，使所述沥青质吸附在所述纳米颗粒表面并形成包覆层，得到复合材料前驱体。In some embodiments, the nanoparticles and asphaltenes are mixed in a solvent for 0.1-24 h, so that the asphaltenes are adsorbed on the surface of the nanoparticles and form a coating layer to obtain a composite material precursor.
在一些具体的实施方式中，所述沥青质在溶剂中的浓度为0.01-100g/L。In some specific embodiments, the concentration of the asphaltene in the solvent is 0.01-100 g/L.
在一些实施方式中，为保证沥青在纳米颗粒表面形成稳定的包覆层，在惰性气氛下对所述复合材料前驱体进行加热处理，加热温度为250-1200℃，加热时间为0.5-10h，制得所述纳米复合负极材料。In some embodiments, in order to ensure that the asphalt forms a stable coating layer on the surface of the nanoparticles, the composite material precursor is heated under an inert atmosphere, the heating temperature is 250-1200°C, and the heating time is 0.5-10h, The nano composite negative electrode material is prepared.
在一些实施方式中，还提供一种纳米复合负极材料，采用本发明制备方法制备得到。In some embodiments, a nano composite negative electrode material is also provided, which is prepared by the preparation method of the present invention.
在一些实施方式中，还提供一种纳米复合负极材料的应用，将本发明制备方法制得的纳米复合负极材料用作锂离子电池负极片。In some embodiments, an application of the nanocomposite negative electrode material is also provided, and the nanocomposite negative electrode material prepared by the preparation method of the present invention is used as the negative electrode sheet of a lithium ion battery.
下面通过具体实施例对本发明一种纳米复合负极材料的制备方法及其性能测试做进一步的解释说明：The preparation method and performance test of a nano-composite negative electrode material of the present invention are further explained by specific examples below:
对照组Control group
一种硅碳负极材料的制备方法及测试，包括以下步骤：A preparation method and test of silicon carbon anode material, including the following steps:
第一步，吸附：将50mg直径100nm的硅颗粒加入到50-200ml的甲苯溶液中，搅拌24h。The first step, adsorption: add 50mg of silicon particles with a diameter of 100nm to 50-200ml of toluene solution and stir for 24h.
第二步，干燥：8000rpm/min-10000rpm/min离心并放入50℃真空烘箱12h除去溶剂。The second step, drying: centrifuge at 8000rpm/min-10000rpm/min and put in a vacuum oven at 50°C for 12h to remove the solvent.
第三步，高温处理：将第二步中得到的硅粉置于加热装置中，在惰性气体保护下先以5℃每分钟升温至100℃，保温10min后，再以5℃/min的升温速率升温800℃，保温1h，冷却至室温，得到高温处理的纳米硅。The third step, high-temperature treatment: put the silicon powder obtained in the second step in a heating device, and first heat it up to 100°C at 5°C per minute under the protection of inert gas, and then heat it up at 5°C/min after holding it for 10 minutes The temperature is increased at a rate of 800° C., the temperature is kept for 1 hour, and then cooled to room temperature to obtain high-temperature treated nano silicon.
第四步，球磨、涂覆：将Si、粘结剂(海藻酸钠)和碳纳米管按照(6：2：2)进行球磨，制得浆料，再将浆料涂覆在金属箔材上，干燥后得到硅碳负极片，负载量为0.8mg/cm 2。 The fourth step, ball milling and coating: Si, binder (sodium alginate) and carbon nanotubes are ball milled according to (6:2:2) to obtain slurry, and then the slurry is coated on the metal foil After drying, the silicon-carbon negative electrode sheet is obtained, with a load of 0.8 mg/cm 2 .
第五步，电池组装和电化学特性测试：将所得到的硅碳负极极片组装成半电池，并测试其电化学性能。半电池以所制极片为正极，隔膜为celgard2400，电解液选用1mol/L的LiPF6为导电盐，DMC：DEC：EC(wt％)＝1：1：1的混合溶剂为导电液。测试条件为：0.01V-1.5V，0.03C电流首次循环活化，后续在0.2C电流密度下充放电循环200圈。The fifth step, battery assembly and electrochemical characteristic test: the obtained silicon-carbon negative pole piece is assembled into a half-cell, and its electrochemical performance is tested. The half-cell uses the prepared pole piece as the positive electrode, the separator is celgard 2400, the electrolyte uses 1 mol/L LiPF6 as the conductive salt, and the mixed solvent of DMC: DEC: EC (wt%) = 1: 1: 1 is the conductive liquid. The test conditions are: 0.01V-1.5V, 0.03C current cycle is activated for the first time, followed by 200 cycles of charge and discharge cycles at 0.2C current density.
实施例1Example 1
一种硅碳负极材料的制备方法及其测试，包括以下步骤：A preparation method and test of silicon carbon anode material, including the following steps:
第一步，沥青质吸附：将50mg直径100nm硅粉加入到100ml的1.0g/L沥青质分子的甲苯溶液中，机械搅拌12h，将沥青质分子驱动到内核材料表面。The first step, asphaltene adsorption: add 50mg of silicon powder with a diameter of 100nm to 100ml of 1.0g/L asphaltene molecules in toluene solution, and mechanically stir for 12h to drive the asphaltene molecules to the surface of the core material.
第二步，干燥：8000rpm/min离心后移去上层清液，管内剩下的硅泥利用50℃真空烘箱干燥12h除去溶剂。The second step, drying: After centrifugation at 8000 rpm/min, the supernatant liquid is removed, and the remaining silicon sludge in the tube is dried in a vacuum oven at 50°C for 12 hours to remove the solvent.
第三步，高温处理：将得到的包覆沥青质的硅粉置于加热石英管中，在惰性气体保护下先以5℃每分钟升温至100℃，保温10min后，再以5℃/min的升温速率升温至800℃，保温1h，冷却至室温，得到高温处理后的沥青质吸附层包覆硅复合负极材料(HTE-Asp-Si-1)。The third step, high temperature treatment: place the obtained asphaltene-coated silicon powder in a heated quartz tube, and heat it up to 100°C at 5°C per minute under the protection of inert gas, and then heat it for 10 minutes at 5°C/min. The temperature increase rate is increased to 800 DEG C, kept for 1 hour, and cooled to room temperature to obtain the high-temperature treated asphaltene adsorption layer coated silicon composite negative electrode material (HTE-Asp-Si-1).
第四步，球磨、涂覆：将HTE-Asp-Si、海藻酸钠和碳纳米管按照重量比(6：2：2)进行球磨，制得浆料，再将浆料涂覆在金属箔材上，干燥后得到硅碳负极片，其负载量约为0.8mg/cm 2。 The fourth step, ball milling and coating: ball milling HTE-Asp-Si, sodium alginate and carbon nanotubes according to the weight ratio (6:2:2) to prepare slurry, and then coating the slurry on the metal foil On the material, after drying, the silicon carbon negative electrode sheet is obtained, and the loading amount is about 0.8 mg/cm 2 .
第五步，电池组装和电化学特性测试：将所得到的硅碳负极极片组装成半电池，并测试其电化学性能。半电池以所制极片为正极，隔膜为celgard2400，电解液选用1mol/L的LiPF6为导电盐，DMC：DEC：EC(wt％)＝1：1：1的混合溶剂为导电液。测试条件为：0.01V-1.5V，0.03C电流首次循环活化，后续在0.2C电流密度下充放电循环200圈。The fifth step, battery assembly and electrochemical characteristic test: the obtained silicon-carbon negative pole piece is assembled into a half-cell, and its electrochemical performance is tested. The half-cell uses the prepared pole piece as the positive electrode, the separator is celgard 2400, the electrolyte uses 1 mol/L LiPF6 as the conductive salt, and the mixed solvent of DMC: DEC: EC (wt%) = 1: 1: 1 is the conductive liquid. The test conditions are: 0.01V-1.5V, 0.03C current cycle is activated for the first time, followed by 200 cycles of charge and discharge cycles at 0.2C current density.
实施例2Example 2
一种硅碳负极材料的制备方法及其测试，包括以下步骤：A preparation method and test of silicon carbon anode material, including the following steps:
第一步，溶剂过渡法：将50mg平均直径100nm硅粉加入到1.0g/l沥青质分子的甲苯溶液中，并缓慢滴入一定量的甲醇溶液，使甲苯和甲醇最终体积比为8：2，搅拌12h，将首层沥青质分子驱动到内核材料表面。12h后在缓慢滴入一定量的庚烷，使最终庚烷与甲苯和甲醇的混合溶液的体积比为8：2,将第二层沥青质分子驱动到第一层沥青质分子层表面。The first step, solvent transition method: add 50mg of silicon powder with an average diameter of 100nm to the toluene solution of 1.0g/l asphaltene molecules, and slowly drop a certain amount of methanol solution so that the final volume ratio of toluene and methanol is 8:2 , Stirring for 12 hours, drive the first layer of asphaltene molecules to the surface of the core material. After 12 hours, a certain amount of heptane was slowly dropped to make the final volume ratio of the mixed solution of heptane to toluene and methanol 8:2, driving the second layer of asphaltene molecules to the surface of the first layer of asphaltene molecular layer.
第二步，干燥：8000rpm/min离心后移去上层清液，管内剩下的硅泥利用50℃真空烘箱干燥12h除去溶剂。The second step, drying: After centrifugation at 8000 rpm/min, the supernatant liquid is removed, and the remaining silicon sludge in the tube is dried in a vacuum oven at 50°C for 12 hours to remove the solvent.
第三步，高温处理：将得到的包覆沥青质的硅粉置于加热石英管中，在惰性气体保护下先以5℃每分钟升温至100℃，保温10min后，再以5℃/min的升温速率升温至 800℃，保温1h，冷却至室温，得到高温处理后的沥青质吸附层包覆硅复合负极材料(HTE-Asp-Si-2)。The third step, high temperature treatment: place the obtained asphaltene-coated silicon powder in a heated quartz tube, and heat it up to 100°C at 5°C per minute under the protection of inert gas, and then heat it for 10 minutes at 5°C/min. The temperature rise rate is increased to 800° C., kept for 1 hour, and cooled to room temperature to obtain the high-temperature treated asphaltene adsorption layer coated silicon composite negative electrode material (HTE-Asp-Si-2).
第四步，球磨、涂覆：将HTE-Asp-Si-2、海藻酸钠和碳纳米管按照重量比(6：2：2)进行球磨，制得浆料，再将浆料涂覆在金属箔材上，干燥后得到硅碳负极片，其负载量约为0.8mg/cm 2。 The fourth step, ball milling and coating: ball milling HTE-Asp-Si-2, sodium alginate and carbon nanotubes according to the weight ratio (6:2:2) to obtain slurry, and then coating the slurry on On the metal foil, the silicon carbon negative electrode sheet is obtained after drying, and the loading amount is about 0.8 mg/cm 2 .
第五步，电池组装和电化学特性测试：将所得到的硅碳负极极片组装成半电池，并测试其电化学性能。半电池以所制极片为正极，隔膜为celgard2400，电解液选用1mol/L的LiPF6为导电盐，DMC：DEC：EC(wt％)＝1：1：1的混合溶剂为导电液。测试条件为：0.01V-1.5V，0.03C电流首次循环活化，后续在0.2C电流密度下充放电循环200圈。The fifth step, battery assembly and electrochemical characteristic test: the obtained silicon-carbon negative pole piece is assembled into a half-cell, and its electrochemical performance is tested. The half-cell uses the prepared pole piece as the positive electrode, the separator is celgard 2400, the electrolyte uses 1 mol/L LiPF6 as the conductive salt, and the mixed solvent of DMC: DEC: EC (wt%) = 1: 1: 1 is the conductive liquid. The test conditions are: 0.01V-1.5V, 0.03C current cycle is activated for the first time, followed by 200 cycles of charge and discharge cycles at 0.2C current density.
实施例3Example 3
一种硅碳负极材料的制备方法及其测试，包括以下步骤：A preparation method and test of silicon carbon anode material, including the following steps:
第一步，沥青质吸附：将50mg直径100nm硅粉加入到100ml的1.0g/L沥青质分子的甲苯溶液中，搅拌12h，将沥青质分子驱动到内核材料表面。The first step, asphaltene adsorption: add 50mg of 100nm diameter silicon powder to 100ml of 1.0g/L asphaltene molecule toluene solution, stir for 12h, drive the asphaltene molecule to the surface of the core material.
第二步，干燥：8000rpm/min离心后移去上层清液，管内剩下的硅泥利用50℃真空烘箱干燥12h除去溶剂。The second step, drying: After centrifugation at 8000 rpm/min, the supernatant liquid is removed, and the remaining silicon sludge in the tube is dried in a vacuum oven at 50°C for 12 hours to remove the solvent.
第三步，高温处理：将得到的包覆沥青质的硅粉置于加热石英管中，在惰性气体保护下先以5℃每分钟升温至100℃，保温10min后，再以5℃/min的升温速率升温至600℃，保温1h，冷却至室温，得到高温处理后的沥青质吸附层包覆硅复合负极材料(HTE-Asp-Si-3)。The third step, high temperature treatment: place the obtained asphaltene-coated silicon powder in a heated quartz tube, and heat it up to 100°C at 5°C per minute under the protection of inert gas, and then heat it for 10 minutes at 5°C/min. The temperature increase rate is raised to 600°C, kept for 1 hour, and cooled to room temperature to obtain the high-temperature treated asphaltene adsorption layer coated silicon composite negative electrode material (HTE-Asp-Si-3).
第四步，球磨、涂覆：将HTE-Asp-Si-3、海藻酸钠和碳纳米管按照重量比(6：2：2)进行球磨，制得浆料，再将浆料涂覆在金属箔材上，干燥后得到硅碳负极片，其负载约为0.8mg/cm 2。 The fourth step, ball milling and coating: ball milling HTE-Asp-Si-3, sodium alginate and carbon nanotubes according to the weight ratio (6:2:2) to obtain slurry, and then coating the slurry on On the metal foil, the silicon-carbon negative electrode sheet is obtained after drying, and the load is about 0.8 mg/cm 2 .
第五步，电池组装和电化学特性测试：将所得到的硅碳负极极片组装成半电池，并测试其电化学性能。半电池以所制极片为正极，隔膜为celgard2400，电解液选用1mol/L的LiPF6为导电盐，DMC：DEC：EC(wt％)＝1：1：1的混合溶剂为导电液。测试条件为：0.01V-1.5V，0.03C电流首次循环活化，后续在0.2C电流密度下充放电循环200圈。The fifth step, battery assembly and electrochemical characteristic test: the obtained silicon-carbon negative pole piece is assembled into a half-cell, and its electrochemical performance is tested. The half-cell uses the prepared pole piece as the positive electrode, the separator is celgard 2400, the electrolyte uses 1 mol/L LiPF6 as the conductive salt, and the mixed solvent of DMC: DEC: EC (wt%) = 1: 1: 1 is the conductive liquid. The test conditions are: 0.01V-1.5V, 0.03C current cycle is activated for the first time, followed by 200 cycles of charge and discharge cycles at 0.2C current density.
实施例4Example 4
一种硅碳负极材料的制备方法及其测试，包括以下步骤：A preparation method and test of silicon carbon anode material, including the following steps:
第一步，水饱和甲苯溶液制备：在200ml甲苯溶剂中注入20ml去离子水，静置1周后，将上层甲苯溶剂取出，密封待用。The first step is the preparation of a water-saturated toluene solution: 20 ml of deionized water is injected into 200 ml of toluene solvent, and after standing for 1 week, the upper layer of toluene solvent is taken out and sealed for use.
第二步，沥青质吸附：将沥青质溶解于上述水饱和甲苯溶液制备1.0g/L的甲苯溶液，并将50mg直径50nm硅粉加入到100ml的该沥青质甲苯溶液中，搅拌12h，将第一层沥青质分子驱动到内核材料表面。The second step, asphaltene adsorption: dissolve asphaltene in the above water-saturated toluene solution to prepare a 1.0g/L toluene solution, and add 50mg of 50nm diameter silicon powder to 100ml of this asphaltene toluene solution, stir for 12h, A layer of asphaltene molecules drive to the surface of the core material.
第三步，干燥：8000rpm/min离心后移去上层清液，管内剩下的硅泥利用50℃真空烘箱干燥12h除去溶剂。The third step, drying: After centrifugation at 8000 rpm/min, the supernatant liquid is removed, and the remaining silicon sludge in the tube is dried in a vacuum oven at 50°C for 12 hours to remove the solvent.
第四步，高温处理：将得到的包覆沥青质的硅粉置于加热石英管中，在惰性气体保护下先以5℃每分钟升温至100℃，保温10min后，再以5℃/min的升温速率升温至600℃，保温1h，冷却至室温，得到高温处理后的沥青质吸附层包覆硅复合负极材料(HTE-Asp-Si-4)。The fourth step, high temperature treatment: Put the obtained asphaltene-coated silicon powder in a heated quartz tube, and heat it up to 100°C at 5°C per minute under the protection of inert gas, and then heat it at 5°C/min for 10 minutes. The temperature increase rate is increased to 600° C., held for 1 hour, and cooled to room temperature to obtain a high-temperature treated asphaltene adsorption layer coated silicon composite negative electrode material (HTE-Asp-Si-4).
第五步，球磨、涂覆：将HTE-Asp-Si-4、海藻酸钠和碳纳米管按照重量比(6：2：2)进行球磨进行球磨，制得浆料，再将浆料涂覆在金属箔材上，干燥后得到硅碳负极片，其负载约为0.8mg/cm 2。 The fifth step, ball milling and coating: HTE-Asp-Si-4, sodium alginate and carbon nanotubes are ball milled according to the weight ratio (6:2:2) to obtain a slurry, and then the slurry is coated Covered on metal foil and dried to obtain a silicon carbon negative electrode sheet with a load of about 0.8 mg/cm 2 .
第六步，电池组装和电化学特性测试：将所得到的硅碳负极极片组装成半电池，并测试其电化学性能。半电池以所制极片为正极，隔膜为celgard2400，电解液选用1mol/L的LiPF6为导电盐，DMC：DEC：EC(wt％)＝1：1：1的混合溶剂为导电液。测试条 件为：0.01V-1.5V，0.03C电流首次循环活化，后续在0.2C电流密度下充放电循环200圈。The sixth step, battery assembly and electrochemical characteristics test: the obtained silicon carbon negative pole piece is assembled into a half-cell, and its electrochemical performance is tested. The half-cell uses the prepared pole piece as the positive electrode, the separator is celgard 2400, the electrolyte uses 1 mol/L LiPF6 as the conductive salt, and the mixed solvent of DMC: DEC: EC (wt%) = 1: 1: 1 is the conductive liquid. The test conditions are: 0.01V-1.5V, 0.03C current cycle is activated for the first time, followed by 200 cycles of charge and discharge cycles at 0.2C current density.
该实例中制备的硅碳复合纳米材料的扫描电镜图显示于图3所示,硅颗粒表面生成的碳层均匀紧密包覆在颗粒表面，并形成三维团聚网络，这样的结构有利于增强整个材料的导电性，另外，疏松的结构也有利于膨胀过程当中的应力释放，有利于增强循环稳定性。The scanning electron micrograph of the silicon-carbon composite nanomaterial prepared in this example is shown in Figure 3. The carbon layer formed on the surface of the silicon particles is evenly and tightly coated on the surface of the particles and forms a three-dimensional agglomerated network. This structure is beneficial to strengthen the entire material In addition, the loose structure is also conducive to stress release during the expansion process and is conducive to enhancing cycle stability.
实施例5Example 5
一种硅碳负极材料的制备方法及其测试，包括以下步骤：A preparation method and test of silicon carbon anode material, including the following steps:
第一步，水饱和甲苯溶液制备：在200ml甲苯溶剂中注入20ml去离子水，静置1周后，将上层甲苯溶剂取出，密封。In the first step, the water-saturated toluene solution is prepared: 20 ml of deionized water is injected into 200 ml of toluene solvent, and after standing for 1 week, the upper layer of toluene solvent is taken out and sealed.
第二步，沥青质吸附：将沥青质溶解于上述水饱和甲苯溶液制备1.5g/L的沥青质甲苯溶液，并将50mg直径50nm硅粉加入到100ml的该沥青质甲苯溶液中，搅拌2h，将第一层沥青质分子驱动到内核材料表面。之后加入一定量的庚烷溶液，使甲苯和庚烷比例为8：2，搅拌12h，将第二层沥青质分子驱动到内核材料表面。The second step, asphaltene adsorption: dissolve asphaltene in the above water-saturated toluene solution to prepare a 1.5g/L asphaltene toluene solution, and add 50mg of 50nm diameter silicon powder to 100ml of this asphaltene toluene solution and stir for 2h, Drive the first layer of asphaltene molecules to the surface of the core material. Then add a certain amount of heptane solution to make the ratio of toluene and heptane 8:2, and stir for 12 hours to drive the second layer of asphaltene molecules to the surface of the core material.
第三步，干燥：8000rpm/min离心后移去上层清液，管内剩下的硅泥利用50℃真空烘箱干燥12h除去溶剂。The third step, drying: After centrifugation at 8000 rpm/min, the supernatant liquid is removed, and the remaining silicon sludge in the tube is dried in a vacuum oven at 50°C for 12 hours to remove the solvent.
第四步，高温处理：将得到的包覆沥青质的硅粉置于加热石英管中，在惰性气体保护下先以5℃每分钟升温至100℃，保温10min后，再以5℃/min的升温速率升温至600℃，保温1h，冷却至室温，得到高温处理后的沥青质吸附层包覆硅复合负极材料(HTE-Asp-Si-5)。The fourth step, high temperature treatment: Put the obtained asphaltene-coated silicon powder in a heated quartz tube, and heat it up to 100°C at 5°C per minute under the protection of inert gas, and then heat it at 5°C/min for 10 minutes. The temperature increase rate is raised to 600° C., kept for 1 hour, and cooled to room temperature to obtain the high-temperature treated asphaltene adsorption layer coated silicon composite negative electrode material (HTE-Asp-Si-5).
第五步，球磨、涂覆：将HTE-Asp-Si-5、海藻酸钠和碳纳米管按照重量比(6：2：2)进行球磨进行球磨，制得浆料，再将浆料涂覆在金属箔材上，干燥后得到硅碳负极片，其负载约为0.8mg/cm 2。 The fifth step, ball milling and coating: HTE-Asp-Si-5, sodium alginate and carbon nanotubes are ball milled according to the weight ratio (6:2:2) to obtain a slurry, and then the slurry is coated Covered on metal foil and dried to obtain a silicon carbon negative electrode sheet with a load of about 0.8 mg/cm 2 .
第六步，电池组装和电化学特性测试：将所得到的硅碳负极极片组装成半电池，并测试其电化学性能。半电池以所制极片为正极，隔膜为celgard2400，电解液选用1mol/L的LiPF6为导电盐，DMC：DEC：EC(wt％)＝1：1：1的混合溶剂为导电液。测试条件为：0.01V-1.5V，0.03C电流首次循环活化，后续在0.2C电流密度下充放电循环200圈。The sixth step, battery assembly and electrochemical characteristics test: the obtained silicon carbon negative pole piece is assembled into a half-cell, and its electrochemical performance is tested. The half-cell uses the prepared pole piece as the positive electrode, the separator is celgard 2400, the electrolyte uses 1 mol/L LiPF6 as the conductive salt, and the mixed solvent of DMC: DEC: EC (wt%) = 1: 1: 1 is the conductive liquid. The test conditions are: 0.01V-1.5V, 0.03C current cycle is activated for the first time, followed by 200 cycles of charge and discharge cycles at 0.2C current density.
在该实施例中，循环200圈之后的的容量保持率为90％，容量为1400mAh·g -1。该实例中制备的硅碳复合纳米材料的扫描电镜图显示于图4。 In this example, the capacity retention rate after 200 cycles was 90%, and the capacity was 1400 mAh·g -1 . The scanning electron micrograph of the silicon-carbon composite nanomaterial prepared in this example is shown in FIG. 4.
实施例6Example 6
一种硅碳负极材料的制备方法及其测试，包括以下步骤：A preparation method and test of silicon carbon anode material, including the following steps:
第一步，水饱和甲苯溶液制备：在200ml甲苯溶剂中注入20ml去离子水，静置1周后，将上层甲苯溶剂取出，密封。In the first step, the water-saturated toluene solution is prepared: 20 ml of deionized water is injected into 200 ml of toluene solvent, and after standing for 1 week, the upper layer of toluene solvent is taken out and sealed.
第二步，沥青质吸附：将沥青质溶解于上述水饱和甲苯溶液制备1.5g/L的沥青质甲苯溶液，并将50mg直径50nm硅粉加入到100ml的该沥青质甲苯溶液中，搅拌2h，将第一层沥青质分子驱动到内核材料表面。之后加入一定量的庚烷溶液，使甲苯和庚烷比例为8：2，搅拌12h，将第二层沥青质分子驱动到内核材料表面。The second step, asphaltene adsorption: dissolve asphaltene in the above water-saturated toluene solution to prepare a 1.5g/L asphaltene toluene solution, and add 50mg of 50nm diameter silicon powder to 100ml of this asphaltene toluene solution and stir for 2h, Drive the first layer of asphaltene molecules to the surface of the core material. Then add a certain amount of heptane solution to make the ratio of toluene and heptane 8:2, and stir for 12 hours to drive the second layer of asphaltene molecules to the surface of the core material.
第三步，干燥：8000rpm/min离心后移去上层清液，管内剩下硅泥利用50℃真空烘箱干燥12h除去溶剂。The third step, drying: After centrifugation at 8000 rpm/min, the supernatant is removed, and the remaining silicon mud in the tube is dried in a vacuum oven at 50°C for 12 hours to remove the solvent.
第四步，高温处理：将得到的包覆沥青质的硅粉置于加热石英管中，在惰性气体保护下先以5℃每分钟升温至100℃，保温10min后，再以5℃/min的升温速率升温至380℃，保温1h，冷却至室温，得到高温处理后的沥青质吸附层包覆硅复合负极材料(HTE-Asp-Si-6)。The fourth step, high temperature treatment: Put the obtained asphaltene-coated silicon powder in a heated quartz tube, and heat it up to 100°C at 5°C per minute under the protection of inert gas, and then heat it at 5°C/min for 10 minutes. The temperature rise rate is raised to 380° C., kept for 1 hour, and cooled to room temperature to obtain the high-temperature treated asphaltene adsorption layer coated silicon composite negative electrode material (HTE-Asp-Si-6).
第五步，球磨、涂覆：将HTE-Asp-Si-6、海藻酸钠和碳纳米管按照重量比(6：2：2)进行球磨进行球磨，制得浆料，再将浆料涂覆在金属箔材上，干燥后得到硅碳负极片，其负载约为0.8mg/cm 2。 The fifth step, ball milling and coating: HTE-Asp-Si-6, sodium alginate and carbon nanotubes are ball milled according to the weight ratio (6:2:2) to obtain a slurry, and then the slurry is coated Covered on metal foil and dried to obtain a silicon carbon negative electrode sheet with a load of about 0.8 mg/cm 2 .
第六步，电池组装和电化学特性测试：将所得到的硅碳负极极片组装成半电池，并测试其电化学性能。半电池以所制极片为正极，隔膜为elgard2400，电解液选用1mol/L的LiPF6为导电盐，DMC：DEC：EC(wt％)＝1：1：1的混合溶剂为导电液。测试条件为：0.01V-1.5V，0.03C电流首次循环活化，后续在0.2C电流密度下充放电循环400圈。The sixth step, battery assembly and electrochemical characteristics test: the obtained silicon carbon negative pole piece is assembled into a half-cell, and its electrochemical performance is tested. The half-cell uses the prepared pole piece as the positive electrode, the separator is elgard2400, the electrolyte uses 1mol/L LiPF6 as the conductive salt, and the mixed solvent of DMC:DEC:EC (wt%)=1:1:1 is the conductive liquid. The test conditions are: 0.01V-1.5V, 0.03C current cycle is activated for the first time, followed by 400 cycles of charge and discharge at a current density of 0.2C.
该实例中的长循环性能测试结果如图5所示，所述复合硅碳负极材料具有优异的循环稳定性，采用0.03C电流密度进行首次充放电循环条件下其库伦效率为87％，增大电流至0.2C之后，可逆容量约为1560mAh·g -1，经400圈充放电循环后，其剩余容量为1450m mAh·g -1保持率约为92.9％，平均充放电循环容量损失在万分之二以下。 The long-cycle performance test results in this example are shown in Figure 5. The composite silicon-carbon anode material has excellent cycle stability, and its coulombic efficiency is 87% under the condition of the first charge-discharge cycle with a current density of 0.03C. After the current reaches 0.2C, the reversible capacity is about 1560mAh·g -1 . After 400 cycles of charge and discharge, the remaining capacity is 1450m mAh·g -1. The retention rate is about 92.9%, and the average charge and discharge cycle capacity loss is ten thousand minutes. Below bis.
所述对照组和实施例1-实施例6制备的半电池的性能结果如表1所示：The performance results of the control group and the half-cells prepared in Example 1 to Example 6 are shown in Table 1:
表1半电池的电化学性能结果Table 1 Electrochemical performance results of half-cell
Figure PCTCN2020085389-appb-000001
Figure PCTCN2020085389-appb-000001
Figure PCTCN2020085389-appb-000002
Figure PCTCN2020085389-appb-000002
实施例7Example 7
沥青质吸附层微观形貌和微观力学特性表征：Characterization of microscopic morphology and micromechanical properties of asphaltene adsorption layer:
第一步，水饱和甲苯溶液制备：在200ml甲苯溶剂中注入20ml去离子水，静置1周后，将上层甲苯溶剂取出，密封待用。The first step is the preparation of a water-saturated toluene solution: 20 ml of deionized water is injected into 200 ml of toluene solvent, and after standing for 1 week, the upper layer of toluene solvent is taken out and sealed for use.
第二步，沥青质吸附：将沥青质溶解于上述水饱和甲苯溶液制备1.5g/L的沥青质甲苯溶液，将1cm*1cm的镀二氧化硅层的硅片垂直置于1.0g/l沥青质分子的溶液中，静置2h，将第一层沥青质分子驱动到硅片表面。之后加入一定量的庚烷溶液，使甲苯和庚烷比例为8：2，静置12h，将第二层沥青质分子驱动到硅片表面。The second step, asphaltene adsorption: dissolve asphaltene in the above water-saturated toluene solution to prepare a 1.5g/L asphaltene toluene solution, and place 1cm*1cm silicon wafers coated with silica layer vertically on 1.0g/l asphalt The first layer of asphaltene molecules will be driven to the surface of the silicon wafer by letting it stand for 2h in the solution of the quality molecules. Then add a certain amount of heptane solution to make the ratio of toluene and heptane 8:2, and let it stand for 12 hours to drive the second layer of asphaltene molecules to the surface of the silicon wafer.
第三步，高温处理：将沥青质溶液处理过的硅片置于加热装置中，惰性气氛下加热，先以5℃/min升温至100℃，保温10min后，再以5℃/min的升温速率升温至600℃，保温1h，冷却至室温，得到表面镀有碳基吸附层的硅片。The third step, high-temperature treatment: place the silicon wafers treated with the asphaltene solution in a heating device and heat it under an inert atmosphere, first raise the temperature at 5°C/min to 100°C, hold for 10 minutes, and then heat it at 5°C/min The rate is increased to 600°C, kept for 1 hour, and cooled to room temperature to obtain a silicon wafer coated with a carbon-based adsorption layer on the surface.
第四步，原子力显微镜测试：利用Bruker Multimode 8仪器的PFQNM模式进行测试，探针型号为TAP-525，扫描速率0.5Hz，对碳基吸附层材料进行测试。The fourth step, atomic force microscope test: use the PFQNM mode of the Bruker Multimode 8 instrument to test, the probe model is TAP-525, the scanning rate is 0.5Hz, and the carbon-based adsorption layer material is tested.
图6和图7分别显示利用实施例6中条件制备的硅碳负极材料的碳层材料的原子力显微镜微观形貌和力学特性表征。该体系下形成的包覆层厚度约为6nm，且该包覆层呈现出网络状结构。该网络状结构中不同的位点具备不同的弹性模量(最大模量为20GPa)， 其中高模量区域提供长循环稳定性所需的外包覆层强度，而低模量区域使得外包覆层形变灵活度高。该测试结果从侧面解释了此法合成的硅碳负极材料优异的循环稳定性。6 and 7 respectively show the atomic force microscope microscopic morphology and mechanical characteristics of the carbon layer material of the silicon-carbon anode material prepared under the conditions in Example 6. The thickness of the coating layer formed under this system is about 6 nm, and the coating layer presents a network structure. Different sites in the network structure have different elastic modulus (the maximum modulus is 20 GPa). The high modulus region provides the strength of the outer coating layer required for long-cycle stability, while the low modulus region makes the outer coating The cladding has high flexibility in deformation. The test results explain the excellent cycle stability of the silicon carbon anode material synthesized by this method from the side.
综上所述，本发明提供的纳米复合负极材料的制备方法具有原料来源广、合成路径简单、合成规模可放大等优点，所述复合负极材料包括由沥青质吸附在所述纳米颗粒表面形成的包覆层，所述包覆层经高温处理后具有机械强度高、离子传导性能好等优点，该纳米复合负极材料具有能量密度高，循环稳定性好等一系列高效锂电池负极所需性能。在107.4mAh·g -1(0.03C)的电流密度下，该纳米复合负极材料首次充放电效率可达87.2％，能量密度达到3195.12mAh·g -1。在稳定性测试的后续循环过程中，当采用电流密度为715.8mAh·g -1(0.2C)，其可逆容量约为1565.11mAh·g -1，且在连续充放电400次后，剩余能量密度约为1441.48mAh·g -1，其容量保持率为92.96％，平均每次充放电能量密度损失在万分之二以下。 In summary, the preparation method of the nano composite anode material provided by the present invention has the advantages of wide source of raw materials, simple synthesis path, and scalable synthesis scale. The composite anode material includes asphaltene adsorbed on the surface of the nanoparticles. The coating layer has the advantages of high mechanical strength and good ion conductivity after high temperature treatment. The nano composite negative electrode material has high energy density, good cycle stability and a series of high-efficiency lithium battery negative electrodes. At a current density of 107.4mAh·g -1 (0.03C), the first charge-discharge efficiency of the nanocomposite anode material can reach 87.2%, and the energy density can reach 3195.12mAh·g -1 . In the subsequent cycles of the stability test, when the current density is 715.8mAh·g -1 (0.2C), its reversible capacity is about 1565.11mAh·g -1 , and after 400 continuous charge and discharge, the remaining energy density It is about 1441.48mAh·g -1 , its capacity retention rate is 92.96%, and the average energy density loss per charge and discharge is less than 2/10 thousand.
应当理解的是，本发明的应用不限于上述的举例，对本领域普通技术人员来说，可以根据上述说明加以改进或变换，所有这些改进和变换都应属于本发明所附权利要求的保护范围。It should be understood that the application of the present invention is not limited to the above examples. For those of ordinary skill in the art, improvements or changes can be made based on the above description, and all these improvements and changes should fall within the protection scope of the appended claims of the present invention.

Claims (10)

  1. 一种纳米复合负极材料的制备方法，其特征在于，包括步骤：A method for preparing a nano composite negative electrode material is characterized in that it comprises the following steps:
    提供一种具有锂离子插嵌活性的纳米颗粒；Provide a nanoparticle with lithium ion intercalation activity;
    将所述纳米颗粒与沥青质在溶剂中混合，通过选择和控制溶剂特性驱动沥青质在所述纳米颗粒表面吸附并形成包覆层，得到复合材料前驱体；Mixing the nanoparticles and asphaltenes in a solvent, and driving the asphaltenes to adsorb on the surface of the nanoparticles and forming a coating layer by selecting and controlling the characteristics of the solvent to obtain a composite material precursor;
    在惰性气氛下对所述复合材料前驱体进行加热处理，制得所述纳米复合负极材料。The composite material precursor is heated under an inert atmosphere to prepare the nano composite negative electrode material.
  2. 根据权利要求1所述纳米复合负极材料的制备方法，其特征在于，所述具有锂离子插嵌活性的纳米颗粒为纳米硅、纳米亚氧化硅或纳米锡中的一种。The method for preparing the nano composite negative electrode material according to claim 1, wherein the nano particles with lithium ion intercalation activity are one of nano silicon, nano silicon oxide, or nano tin.
  3. 根据权利要求1所述纳米复合负极材料的制备方法，其特征在于，所述具有锂离子插嵌活性的纳米颗粒的直径为1-150nm。The method for preparing the nanocomposite negative electrode material according to claim 1, wherein the diameter of the nano particles with lithium ion intercalation activity is 1-150 nm.
  4. 根据权利要求1所述纳米复合负极材料的制备方法，其特征在于，所述沥青质包括3-11个环的有机多环分子，所述沥青质的碳氢摩尔比为0.6-1.1。The method for preparing the nanocomposite negative electrode material according to claim 1, wherein the asphaltenes comprise 3-11 rings of organic polycyclic molecules, and the hydrocarbon molar ratio of the asphaltenes is 0.6-1.1.
  5. 根据权利要求1所述纳米复合负极材料的制备方法，其特征在于，将所述纳米颗粒与沥青质在溶剂中混合0.1-24h，使所述沥青质吸附在所述纳米颗粒表面并形成包覆层，得到复合材料前驱体。The method for preparing the nanocomposite negative electrode material according to claim 1, wherein the nanoparticles and asphaltenes are mixed in a solvent for 0.1-24 h, so that the asphaltenes are adsorbed on the surface of the nanoparticles and form a coating Layer to obtain a composite precursor.
  6. 根据权利要求1所述纳米复合负极材料的制备方法，其特征在于，所述沥青质在溶剂中的浓度为0.01-100g/L。The method for preparing the nanocomposite negative electrode material according to claim 1, wherein the concentration of the asphaltene in the solvent is 0.01-100 g/L.
  7. 根据权利要求1所述纳米复合负极材料的制备方法，其特征在于，所述沥青质吸附在纳米颗粒表面形成的包覆层的厚度为1-100nm。The method for preparing the nanocomposite negative electrode material according to claim 1, wherein the thickness of the coating layer formed by adsorbing the asphaltene on the surface of the nanoparticle is 1-100 nm.
  8. 根据权利要求1所述纳米复合负极材料的制备方法，其特征在于，所述在惰性气氛下对所述复合材料前驱体进行加热处理，制得所述纳米复合负极材料的步骤中，加热温度为250-1200℃，加热时间为0.5-10h。The method for preparing the nanocomposite negative electrode material according to claim 1, wherein in the step of heating the composite material precursor under an inert atmosphere to prepare the nanocomposite negative electrode material, the heating temperature is 250-1200℃, heating time is 0.5-10h.
  9. 一种纳米复合负极材料，其特征在于，采用权利要求1-8任一制备方法制备得到。A nano composite negative electrode material, characterized in that it is prepared by any one of the preparation methods of claims 1-8.
  10. 一种纳米复合负极材料的应用，其特征在于，将权利要求1-8任一制备方法制得的纳米复合负极材料用作锂离子电池负极片。An application of a nano-composite negative electrode material, characterized in that the nano-composite negative electrode material prepared by any one of the preparation methods of claims 1-8 is used as a lithium-ion battery negative electrode sheet.
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