WO2020211848A1 - Matériau d'électrode négative nanocomposite, procédé de préparation s'y rapportant et utilisation correspondante - Google Patents

Matériau d'électrode négative nanocomposite, procédé de préparation s'y rapportant et utilisation correspondante 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 .

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Abstract

La présente invention concerne un matériau d'électrode négative nanocomposite, un procédé de préparation s'y rapportant et l'utilisation correspondante, le procédé comprenant les étapes consistant : (S10) à fournir des nanoparticules avec une activité d'intercalation d'ions lithium ; (S20) à mélanger les nanoparticules avec de l'asphaltène dans un solvant, à entraîner l'asphaltène à être adsorbé sur la surface des nanoparticules et former une couche de revêtement au moyen de la sélection et de la commande des propriétés du solvant de façon à obtenir un précurseur de matériau composite ; et (S30) à soumettre le précurseur de matériau composite à un traitement de chauffage sous atmosphère inerte de façon à préparer le matériau d'électrode négative nanocomposite. Le procédé de préparation destiné au matériau d'électrode négative nanocomposite présente les avantages des sources de matières premières qui sont étendues, une voie de synthèse simple, une échelle de synthèse évolutive, etc. Le matériau d'électrode négative composite consiste en la couche de revêtement formée par adsorption de l'asphaltène sur la surface des nanoparticules et la couche de revêtement présente les avantages d'une résistance mécanique élevée, d'une bonne conductivité ionique, etc., après un traitement à haute température. Le matériau d'électrode négative nanocomposite présente une série de performances requises pour des électrodes négatives de batterie au lithium à haut rendement, telles qu'une densité d'énergie élevée, une bonne stabilité de cycle, etc.
PCT/CN2020/085389 2019-04-18 2020-04-17 Matériau d'électrode négative nanocomposite, procédé de préparation s'y rapportant et utilisation correspondante WO2020211848A1 (fr)

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