WO2022016951A1 - Matériau d'électrode négative à base de silicium, électrode négative, batterie ion-lithium, et procédé de préparation s'y rapportant - Google Patents

Matériau d'électrode négative à base de silicium, électrode négative, batterie ion-lithium, et procédé de préparation s'y rapportant Download PDF

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WO2022016951A1
WO2022016951A1 PCT/CN2021/091857 CN2021091857W WO2022016951A1 WO 2022016951 A1 WO2022016951 A1 WO 2022016951A1 CN 2021091857 W CN2021091857 W CN 2021091857W WO 2022016951 A1 WO2022016951 A1 WO 2022016951A1
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silicon
negative electrode
sio
preparing
electrode material
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PCT/CN2021/091857
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Chinese (zh)
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庞春雷
石晓太
汪静伟
任建国
贺雪琴
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贝特瑞新材料集团股份有限公司
惠州市鼎元新能源科技有限公司
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • 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
    • H01M4/48—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
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/5825—Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
    • H01M4/624—Electric conductive fillers
    • H01M4/625—Carbon or graphite
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the present disclosure belongs to the field of energy storage materials and electrochemistry, and in particular relates to a silicon-based negative electrode material, a negative electrode, a lithium ion battery and a preparation method thereof.
  • lithium-ion batteries With the expansion of the application field of lithium-ion batteries, lithium-ion batteries have become a hot spot of research work. As an important part of lithium-ion batteries, anode materials affect the specific energy and cycle life of lithium-ion batteries, and have always been the focus of lithium-ion battery research.
  • the traditional graphite-based negative electrode material has a low capacity for storing lithium ions (theoretically 372mAh/g), which leads to the problem that the overall capacity of the battery made with it is not high.
  • the global automobile industry is transforming from internal combustion engines to electric vehicles, so the requirements for battery energy density are getting higher and higher, so lithium-ion batteries made of traditional graphite anode materials can no longer meet the needs of electric vehicles.
  • the development of new energy lithium-ion battery anode materials with high energy density and high power density is imminent.
  • Silicon has the highest theoretical specific capacity (4200mAh/g) and lower discharge potential, and is the most promising anode material for next-generation lithium-ion batteries.
  • the large volume expansion (up to 300%) of silicon during charge and discharge cycles can lead to anode cracking and pulverization, which limits its commercial application.
  • silicon oxide is a negative electrode material with higher specific capacity, and its volume change is smaller during charge and discharge than silicon. In addition, it also has the advantages of low working voltage and wide source of raw materials.
  • silicon oxide can alleviate its own volume expansion, due to the generation of irreversible Li 2 O during the first cycle, the consumption of Li in the cathode material is increased, and the irreversible capacity is increased, resulting in a low first Coulomb efficiency.
  • the commonly used method is to introduce a lithium source into the silicon oxide.
  • the preparation process of the material and the electrode has a greater risk, resulting in Its practical application is difficult.
  • due to the complex process, high cost, and the use of highly corrosive and highly toxic raw materials its industrial application is hindered.
  • the present disclosure provides a silicon-based negative electrode material, and the silicon-based negative electrode material includes:
  • Core said core comprising a silicate of silicon, silicon oxide and M; and the formula of the silicon oxide is SiO x, 0 ⁇ x ⁇ 2 , M is a metal; and
  • a carbon coating, the carbon coating is formed on the surface of the inner core, and the thickness of the carbon coating is 50 nm-200 nm.
  • the thickness of the carbon coating is 100 nm-200 nm.
  • the M includes, but is not limited to, any one or a combination of at least two of Li, Mg, Al, Zn, Ca, Na, and Ti.
  • the M further includes Fe or a combination of Fe and any one or at least two of Li, Mg, Al, Zn, Ca, Na, and Ti.
  • the mass fraction of the M element is between 1-30%.
  • the average particle size D50 of the silicon-based negative electrode material is 0.5 ⁇ m-40 ⁇ m.
  • the silicon-based negative electrode material has a specific surface area of 0.5 m 2 /g to 40 m 2 /g.
  • the present disclosure provides a preparation method of the silicon-based negative electrode material, and the method includes the following steps:
  • Carbon coating treatment is performed on the silicon composite to form a carbon film with a thickness of 50 nm to 200 nm on the surface of the silicon composite to obtain a silicon-based negative electrode material.
  • the present disclosure provides a method for preparing the silicon-based negative electrode material, and the method includes the following steps:
  • Carbon coating treatment is performed on the silicon composite to form a carbon film with a thickness of 50 nm to 200 nm on the surface of the silicon composite to obtain a silicon-based negative electrode material.
  • the preparation method of the SiO steam and the M elemental steam includes the following steps: regulating and controlling the raw materials containing SiO and/or preparing the SiO and the M element and/or the raw material for preparing the M element.
  • the temperature and pressure of the reaction environment are used to obtain the SiO vapor and the M elemental vapor.
  • the raw materials for preparing SiO include a mixture of Si and SiO 2 in a mass ratio of 1:1.5-1:2.5.
  • the raw materials for preparing the elemental M include a mixture of the materials used for preparing the elemental M.
  • the reaction environment is a vacuum environment.
  • the specific operation of the reaction environment for forming the SiO-containing and/or SiO-preparing raw materials and the M elemental substance and/or the M elemental-preparing raw materials is: placing the SiO and/or the SiO-preparing raw materials in a vacuum in the furnace.
  • the step of placing the SiO and/or the raw material for preparing SiO and the M element and/or the raw material for preparing M in the reactor includes: placing the SiO and/or the raw material for preparing SiO in a vacuum furnace Close to one end of the furnace tail, place the M element and/or the raw material for preparing M element in the end of the vacuum furnace close to the furnace mouth.
  • the step of placing the SiO and/or the raw material for preparing SiO and the M element and/or the raw material for preparing M in the reactor includes: placing the SiO and/or the raw material for preparing SiO in a vacuum furnace close to the furnace mouth At one end, the M element and/or the raw material for preparing M element is placed at the end of the vacuum furnace close to the furnace tail.
  • the step of placing SiO and/or the raw material for preparing SiO and the M element and/or the raw material for preparing M in the reactor includes: placing the SiO and/or the raw material for preparing SiO with the M element and/or The raw materials for preparing M elemental substance are mixed and placed in a vacuum furnace.
  • the temperature in the step of regulating the temperature and pressure of the reaction environment containing SiO and/or the raw material for preparing SiO and the M element and/or the raw material for preparing M is 1200°C-1600°C, and the pressure It is 0.1Pa-500Pa.
  • the method further includes performing the following step after the step of obtaining the silicon composite and before the carbon coating treatment step on the silicon composite: At least one of crushing, classifying and firing the composite.
  • the method further includes performing the following steps after the step of obtaining the silicon composite to condense into a solid phase material, and before the carbon coating treatment step on the silicon composite solid phase material: the step is according to the scheme Any one of I, Scheme II or Scheme III is carried out.
  • the scheme I is: pulverizing, classifying and firing the silicon composite in sequence
  • the scheme II is: pulverizing, sintering and classifying the silicon composite in sequence
  • the scheme III is: firing, pulverizing and classifying the silicon composite in sequence.
  • the carbon coating method in the step of carbon coating treatment on the silicon composite includes: any one of gas phase coating, liquid phase coating and solid phase coating or at least combination of the two.
  • the carbon coating in the step of carbon coating treatment on the silicon composite is performed by gas-phase coating. composite anode material.
  • the carbon coating in the step of carbon coating treatment on the silicon composite is performed by means of solid phase coating or liquid phase coating, by controlling the mass and firing temperature of the carbon-containing material mixed in The thickness of the carbon coating is controlled to obtain a composite negative electrode material.
  • the method includes the following steps:
  • the M steam and the SiO steam are uniformly mixed in a mixing device placed in a vacuum furnace, and then cooled and condensed to obtain a solid-phase M and SiO mixed silicon composite;
  • the powder material is coated with carbon, so that the thickness of the carbon film on the surface of the silicon composite is between 50 nm and 200 nm to obtain a silicon-based negative electrode material.
  • the present disclosure provides a negative electrode comprising the silicon-based negative electrode material.
  • the present disclosure provides a lithium ion secondary battery including the silicon-based negative electrode material.
  • Fig. 1 is the electron microscope photograph of the particle cross section of silicon composite negative electrode material in embodiment 1;
  • Fig. 2 is the electron microscope photograph of the particle cross section of silicon composite negative electrode material among the embodiment 2;
  • Fig. 3 is the electron microscope photograph of the particle cross section of silicon composite negative electrode material in Comparative Example 1;
  • Fig. 4 is the electron microscope photograph of the particle cross section of silicon composite negative electrode material in Comparative Example 2;
  • Fig. 5 is the electron microscope photograph of the particle cross section of silicon composite negative electrode material in Comparative Example 3;
  • Fig. 6 is the electron microscope photograph of the particle cross section of silicon composite negative electrode material in Comparative Example 4.
  • FIG. 7 is a schematic structural diagram of a silicon-based negative electrode material provided by some embodiments of the present disclosure.
  • FIG. 8 is a schematic diagram of a cathode structure provided by some embodiments of the present disclosure.
  • FIG. 9 is a schematic diagram of a battery provided by some embodiments of the present disclosure.
  • An embodiment provides a silicon-based negative electrode material, a preparation method thereof, and a lithium ion secondary battery.
  • the preparation process is simple and the cost is low, and the obtained silicon-based negative electrode material has the advantages of high initial charge-discharge efficiency and good cycle performance when applied to a lithium ion secondary battery.
  • some embodiments provide a silicon-based negative electrode material 100 , and the silicon-based negative electrode material 100 includes:
  • Core 120, the core 120 silicates include silicon, silicon oxide and M; and the chemical formula of the silicon oxide is SiO x, 0 ⁇ x ⁇ 2 , M is a metal; and a carbon film 140, the The carbon coating 140 is formed on the surface of the inner core 120, and the thickness of the carbon coating 140 is 50 nm-200 nm.
  • the chemical formula of the silicon oxide SiO x, x is equal to 2, that is, when silica, which is a lower electrode active; X is greater than 2, and the other was a mixture of silica compound, an electrode active Also lower.
  • the thickness of the carbon coating 140 is, for example, 50 nm, 60 nm, 80 nm, 90 nm, 100 nm, 110 nm, 125 nm, 135 nm, 150 nm, 170 nm, 180 nm, or 200 nm, etc.
  • x is, for example, 0.3, 0.5, 1 , 1.2, 1.5, 1.7, 1.9, etc.
  • the thickness of the carbon coating 140 is 50 nm-100 nm, 100 nm-130 nm, 130 nm-160 nm, or 100 nm-200 nm.
  • silicon, silicon oxide and silicate are uniformly distributed in the inner core 120, and the surface of the inner core 120 is uniformly covered with a carbon film 140 with a thickness between 50 nm and 200 nm, In at least some embodiments, the thickness of the carbon coating 140 is between 100 nm-200 nm for better electrochemical performance.
  • a silicon-based negative electrode material with a carbon coating thickness between 50 nm and 200 nm is obtained.
  • M element doped silicon composites can be prepared by mixing SiO vapor and M vapor and cooling the resulting deposit in a vacuum environment. Through steam mixing, atomic-level homogeneous mixing of SiO and M elements can be achieved. However, the conductivity of the composite is extremely poor, and its capacity cannot be effectively exerted when it is directly used as a negative electrode material.
  • the solution adopted by the public is to cover a layer of carbon film 140 on the surface of the material, to improve the conductivity of the silicon composite to ensure the performance of the capacity, and through a large number of experiments, it is found that the thickness of the carbon layer is between 50nm-200nm silicon-based negative electrode When the material is 100, defect-free coating on the surface of the composite can be effectively achieved, and the capacity efficiency and cycle performance of the electrode material are optimal.
  • the thickness of the carbon layer is less than 50 nm, the surface of the silicon composite particles cannot be completely covered by the carbon layer, and there are still many exposed parts.
  • the exposed parts will In direct contact with the electrolyte 260, an unstable SEI film is repeatedly generated, resulting in excessive consumption of the electrolyte 260, resulting in decreased cycle performance; on the other hand, the exposed part has extremely poor conductivity, and the active material in this part cannot be effectively embedded. The delithiation reaction will cause a decrease in capacity.
  • the carbon layer on the surface of the silicon composite particle is too thick.
  • the thick carbon layer is easily cracked by the internal stress of the particle during repeated charge and discharge processes. , resulting in the direct contact of the silicon composite with the electrolyte 260 and the deactivation of the exposed site due to loss of electrical contact, resulting in a reduction in material performance.
  • the carbon layer thickness of the silicon composite negative electrode material is limited to between 50 nm and 200 nm, and the silicon-based negative electrode material 100 with the carbon layer thickness within this range, wherein the surface of the silicon composite particles can be completely covered, and The thickness is controlled within the optimum range, which can effectively buffer the volume expansion of the composite during charging and discharging.
  • a carbon layer of suitable thickness also has a positive effect on the volume control of the material. Therefore, the capacity efficiency and cycle performance of the silicon composite can be significantly improved.
  • the silicon-based anode material 100 with a carbon layer thickness of 100 nm has a reversible capacity close to 1400 mAh/g, a first-week Coulombic efficiency of 90%, and a 50-cycle cycle retention rate of more than 90%.
  • the M includes, but is not limited to, any one or a combination of at least two of Li, Mg, Al, Zn, Ca, Na, and Ti.
  • the M further includes Fe or a combination of Fe and any one or at least two of Li, Mg, Al, Zn, Ca, Na, and Ti.
  • the mass fraction of the M element ranges from 1-30%, 1-7%, 6%-8%, 8%- 12%, 12%-20% or between 20%-30%, e.g. 1%, 3%, 5%, 6%, 8%, 10%, 13%, 16%, 20%, 22.5%, 25% , 28% or 30%, etc.
  • the mass fraction of M element within the above range can avoid huge volume expansion during the charge-discharge cycle, thereby preventing capacity loss and performance degradation; at the same time, it can effectively further improve the first-week Coulomb efficiency of the composite material.
  • the mass fraction of M element is greater than 30%, M will react violently with SiO vapor after cooling and deposition, and generate Si particles with larger size. The surface peels off, resulting in capacity loss and performance degradation; when the mass fraction of M element is less than 1%, too little M reacts with SiO, and the amount of Si generated is correspondingly small, which cannot effectively improve the first week Coulomb efficiency of the composite material , has no practical significance.
  • the average particle size D50 of the silicon-based negative electrode material 100 is 0.5 ⁇ m-40 ⁇ m, such as 0.5 ⁇ m, 1 ⁇ m, 3 ⁇ m, 5 ⁇ m, 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, 30 ⁇ m, 35 ⁇ m, or 40 ⁇ m.
  • the utilization rate of the electrolyte 260 in the battery can be improved, and the cycle performance of the battery can be further improved in conjunction with the above technical features.
  • the average particle size of the silicon-based negative electrode material is too large, it is not conducive to the manufacture of the electrode material process. If the particle size is too small, the specific surface area is too large. During the charging and discharging process, a side reaction will occur with the electrolyte 260, which will further consume the electrolysis. Liquid 260, which reduces the cycle performance of the electrode and affects the battery life.
  • the specific surface area of the silicon-based negative electrode material 100 is 0.5m 2 /g-40m 2 /g, such as 0.5m 2 /g, 2m 2 /g, 5m 2 /g, 8m 2 /g, 12m 2 /g, 15m 2 /g, 20m 2 /g, 25m 2 /g, 30m 2 /g, 35m 2 /g or 40m 2 /g, etc.
  • An embodiment provides the preparation method of the silicon-based negative electrode material 100, and the method includes the following steps:
  • a carbon coating treatment is performed on the silicon composite to form a carbon coating 140 with a thickness of 50 nm-200 nm on the surface of the silicon composite to obtain a silicon-based negative electrode material 100 .
  • the method includes the steps of:
  • a carbon coating treatment is performed on the silicon composite to form a carbon coating 140 with a thickness of 50 nm-200 nm on the surface of the silicon composite to obtain a silicon-based negative electrode material 100 .
  • the silicon-based negative electrode material 100 with the thickness of the carbon coating 140 between 50 nm and 200 nm is obtained.
  • the preparation method of the SiO steam and the M elemental steam includes the following steps: regulating and controlling the raw materials containing SiO and/or preparing the SiO and the M element and/or the raw material for preparing the M element.
  • the temperature and pressure of the reaction environment are used to obtain the SiO vapor and the M elemental vapor.
  • the raw materials for preparing SiO include a mixture of Si and SiO 2 mixed in a mass ratio of 1:1.5-1:2.5, for example, a mass ratio of 1:1.5, 1:1.7, 1:1.9, 1:2.0, 1:2.2, 1:2.3, 1:2.4, 1:2.5.
  • the raw material for preparing M elemental substance includes a mixture after the substances used for preparing M elemental substance are mixed.
  • the reaction environment is a vacuum environment.
  • the specific operation of the reaction environment for forming the SiO-containing and/or SiO-preparing raw materials and the M elemental substance and/or the M elemental-preparing raw materials is: placing the SiO and/or the SiO-preparing raw materials in a vacuum in the furnace.
  • the elemental M and/or the raw materials for preparing the elemental M are placed in a vacuum furnace.
  • each raw material is mixed according to a stoichiometric ratio to completely generate the product silicon-based negative electrode material 100 .
  • the condensation can be achieved by the following methods: a mixing device and a condensing device are arranged at one end of the reactor, the SiO steam and the M steam are uniformly mixed when passing through the mixing device, and then the condensing device is Condensed into a solid phase material.
  • the step of placing the SiO and/or the raw material for preparing SiO and the M element and/or the raw material for preparing M in the reactor includes: placing the SiO and/or the raw material for preparing SiO in a vacuum furnace Close to one end of the furnace tail, place the M element and/or the raw material for preparing M element in the end of the vacuum furnace close to the furnace mouth.
  • the step of placing the SiO and/or the raw material for preparing SiO and the M element and/or the raw material for preparing M in the reactor includes: placing the SiO and/or the raw material for preparing SiO in a vacuum furnace close to the furnace mouth At one end, the M element and/or the raw material for preparing M element is placed at the end of the vacuum furnace close to the furnace tail.
  • the step of placing the SiO and/or the raw material for preparing SiO and the M element and/or the raw material for preparing M in the reactor includes: placing the SiO and/or the raw material for preparing SiO with the M element and/or The raw materials for preparing M elemental substance are mixed and placed in a vacuum furnace.
  • the raw materials for preparing the elemental M include a mixture of the materials used for preparing the elemental M.
  • M is Ca
  • the raw material of M can be a mixture of dolomite powder and ferrosilicon powder.
  • M is Ca
  • the raw material of M is a mixture of limestone powder and aluminum powder.
  • M is Ca
  • the raw material of M is metallic calcium bulk.
  • M is Mg
  • the raw material of M is magnesium powder
  • the temperature in the step of regulating the temperature and pressure of the reaction environment containing SiO and/or the raw material for preparing SiO and the M element and/or the raw material for preparing M is 1200°C-1600°C, such as 1200°C , 1250°C, 1300°C, 1400°C, 1450°C, 1500°C or 1600°C, etc.
  • the pressure is 0.1Pa-500Pa, such as 0.1Pa, 0.5Pa, 3Pa, 10Pa, 20Pa, 35Pa, 60Pa, 80Pa, 100Pa, 150Pa, 200Pa, 250Pa, 300Pa, 350Pa, 400Pa or 500Pa, etc.
  • the silicon oxide and the dopant M element can be made to generate a uniform compound at the atomic level in a relatively stable manner. If the temperature is too low, it is easy to evaporate only a single component. If the temperature is too high, there will be problems of uneven evaporation and mismatch of the mixing amount of elements.
  • the method further includes performing the following step after the step of obtaining the silicon composite and before the carbon coating treatment step on the silicon composite: At least one of crushing, classifying and firing the composite.
  • the method further includes performing the following steps after the step of obtaining the silicon composite to condense into a solid phase material, and before the carbon coating treatment step on the silicon composite solid phase material: the step is according to the scheme Any one of I, Scheme II or Scheme III is carried out.
  • the scheme I is: pulverizing, classifying and firing the silicon composite in sequence
  • the scheme II is: pulverizing, sintering and classifying the silicon composite in sequence
  • the scheme III is: firing, pulverizing and classifying the silicon composite in sequence.
  • the carbon coating method in the step of carbon coating treatment on the silicon composite includes: any one of gas phase coating, liquid phase coating and solid phase coating or at least combination of the two.
  • the carbon coating in the step of carbon coating treatment on the silicon composite is performed by gas-phase coating, and the thickness of the carbon coating 140 is controlled by controlling the flow rate and passage time of the carbon-containing gas, A composite negative electrode material is obtained.
  • the specific method of control is the existing technology, and those skilled in the art can operate with reference to the existing technology. It is not a conventional choice to control the thickness of the carbon layer between 50nm and 200nm by controlling the above parameters, and it has achieved an unexpected improvement cycle. performance and other electrochemical properties.
  • the carbon coating in the step of carbon coating treatment on the silicon composite is performed by means of solid phase coating or liquid phase coating, by controlling the mass and firing temperature of the carbon-containing material mixed in The thickness of the carbon coating 140 is controlled to obtain a composite negative electrode material.
  • the specific method of control is the existing technology, and those skilled in the art can operate with reference to the existing technology. It is not a conventional choice to control the thickness of the carbon layer between 50nm and 200nm by controlling the above parameters, and it has achieved an unexpected improvement cycle. performance and other electrochemical properties.
  • the method includes the following steps:
  • M steam and SiO steam are generated in the environment of 1200°C-1600°C and 0.5Pa-500Pa;
  • the M steam and the SiO steam are uniformly mixed in a mixing device placed in a vacuum furnace, and then cooled and condensed to obtain a solid-phase M and SiO mixed silicon composite;
  • the powder material is coated with carbon, so that the thickness of the carbon film 140 on the surface of the silicon composite is between 50 nm and 200 nm to obtain the silicon-based negative electrode material 100 .
  • the silicon-based negative electrode material 100 may be used as a negative electrode active material, such as a negative electrode active material in the lithium ion battery 200 .
  • An embodiment provides a negative electrode material, and the negative electrode material includes the above-mentioned silicon-based negative electrode material 100 .
  • the negative electrode material includes a silicon-based negative electrode material 100, a conductive agent, and a binder.
  • the negative electrode material further comprises graphite.
  • the mass ratio of the silicon-based negative electrode material 100 to graphite is 1:(6-12).
  • An embodiment provides a method for preparing a negative electrode material, including: mixing a silicon-based negative electrode material 100 with a conductive agent and a binder.
  • an embodiment provides a negative electrode 240 including a silicon-based negative electrode material 100 .
  • the negative electrode includes: a negative electrode current collector 242 and a negative electrode material layer 244 on the negative electrode current collector 242 , wherein the negative electrode material layer 244 includes the above-mentioned negative electrode material.
  • An embodiment provides a method for preparing the negative electrode 240 , including: coating a slurry including a negative electrode material on the negative electrode current collector 242 .
  • a negative electrode comprising: a negative electrode current collector 242 and a negative electrode active material layer 244 on the negative electrode current collector 242, wherein the negative electrode active material layer 244 comprises the above-described silicon-based negative electrode material 100.
  • the anode active material layer 244 further includes a conductive agent and a binder.
  • the anode active material layer 244 further includes graphite.
  • the mass ratio of the silicon-based negative electrode material 100, the conductive agent and the binder is (70-95):(2-15):(4-10). In some embodiments, the mass ratio of silicon-based anode material 100 to graphite is 1:(6-12).
  • a method of preparing a negative electrode 240 comprising: applying a slurry including a silicon-based negative electrode material 100 on the negative electrode current collector 242 , so that the negative electrode current collector 242 is forming a negative electrode active material layer 244 thereon; and drying the negative electrode active material layer 244 .
  • drying may be vacuum drying.
  • the total solids content of the slurry is between 30% and 60%. In some embodiments, the total solid content of the silicon-based negative electrode material 100, the conductive agent and the binder in the slurry is 30%-60%. In some embodiments, the total solid content of the silicon-based negative electrode material 100, the conductive agent, the binder and the graphite in the slurry is 30%-60%.
  • each component in the negative electrode active material layer 244 eg, the silicon-based negative electrode material 100, the conductive agent and the binder
  • is mixed and optionally graphite
  • the anode current collector 242 may be a metal.
  • the negative electrode current collector 242 includes, but is not limited to, one of a copper foil current collector and an aluminum foil current collector.
  • the slurry may contain solvent.
  • the solvent includes, but is not limited to, water.
  • the binder can improve the bonding properties of the anode active material particles with each other and with the current collector 242 .
  • the binder includes at least one of a non-aqueous binder or an aqueous binder.
  • Non-aqueous binders include, but are not limited to, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride, polyvinylidene fluoride, polyvinylidene At least one of ethylene, polypropylene, polyamideimide, or polyimide.
  • Aqueous binders include, but are not limited to, at least one of rubber-based binders or polymeric resin binders.
  • Conductive agents can improve the conductivity of electrodes.
  • Conductive agents include but are not limited to high conductivity materials such as gold, copper, nickel, aluminum, silver, and/or similar metal powders or metal fibers and/or similar metal-based materials; or natural graphite, artificial graphite , carbon black, acetylene black, Ketjen black, carbon fiber and/or similar carbon-based materials; or polyphenylene derivatives and/or similar conductive polymers; and/or mixtures thereof.
  • One embodiment provides a lithium-ion battery 200 including the above-described silicon-based negative electrode material 100 .
  • lithium-ion battery 200 includes:
  • the negative electrode 240 includes a negative electrode current collector 242 and a negative electrode active material layer 244 disposed on the negative electrode current collector 242 , and the negative electrode active material layer 244 includes the silicon-based negative electrode material 100 .
  • the lithium-ion battery 200 may include a separator 280 disposed between the positive electrode 220 and the negative electrode 240 .
  • the membrane 280 may be a polymeric microporous membrane, such as a polypropylene microporous membrane. Septum 280 may be commercially available.
  • the lithium-ion battery 200 may include a housing 290 .
  • the positive electrode 220 , the negative electrode 240 , the separator 280 , and the electrolyte 260 may be accommodated in the case 290 .
  • the lithium ion battery may be a cylindrical battery, a prismatic battery, or a coin cell battery.
  • Lithium-ion batteries can be rigid case batteries or pouch batteries.
  • the positive electrode 220 may include a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector.
  • the positive electrode active material layer includes a positive electrode active material capable of reversibly intercalating and deintercalating lithium ions, and examples of the positive electrode active material include, but are not limited to, one of LiCoO 2 , LiNiO 2 , LiMnO 2 , LiMn 2 O 4 , and lithium-transition metal oxides. kind.
  • the electrolyte 260 includes, but is not limited to, a non-aqueous organic solvent, such as at least one of carbonates, esters, ethers, or ketones.
  • carbonates include, but are not limited to, dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methylpropyl carbonate (MPC), ethylpropyl carbonate (EPC) , at least one of methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC) or butylene carbonate (BC).
  • Esters include but are not limited to butyrolactone (BL), decanolide, valerolactone (BL), mevalonolactone, caprolactone (BC), methyl acetate, ethyl acetate or n-propyl acetate at least one of.
  • Ethers include, but are not limited to, may include dibutyl ether.
  • Ketones include, but are not limited to, polymethyl vinyl ketone.
  • a silicon-based negative electrode material 100 with a carbon film 140 having a thickness of 50 nm-200 nm is obtained, so as to improve the conductivity of the silicon composite, and a carbon film 140 with a suitable thickness coats the silicon composite It can significantly improve the capacity efficiency and cycle performance of the silicon composite.
  • the other methods only disclose the method of carbon coating the composite and control the degree of carbon coating by controlling the mass fraction of the contained carbon element.
  • the appropriate coating amount and the mass fraction of carbon are different. For example, for a material with a relatively large area, covering the surface of the material uniformly and completely with a carbon layer requires a lot of carbon. At this time, only the mass fraction of carbon is controlled, which will inevitably lead to some particles or particles. Some locations cannot be covered by the carbon layer or the carbon layer is too thick.
  • the degree of carbon coating is controlled by controlling the thickness of the carbon coating layer, which can effectively achieve defect-free coating on the surface of the composite, and the capacity efficiency and cycle performance of the electrode material are more excellent.
  • the preparation of the embodiment is not only simple in process and low in cost, but also has the advantages of high initial charge-discharge efficiency and good cycle performance when the obtained silicon-based negative electrode material 100 is applied to the lithium ion secondary battery 200 .
  • This embodiment provides a silicon-based negative electrode material 100 and a preparation method thereof.
  • the silicon-based negative electrode material 100 includes an inner core 120 and a carbon coating 140 covering the surface of the inner core 120 , and the inner core 120 includes silicon, silicon oxide and silicon.
  • Magnesium oxide, the thickness of the carbon film 140 is 100 nm, and the mass fraction of Mg element is 15% based on the total mass of the negative electrode material as 100%.
  • the silicon-based negative electrode material 100 is prepared by the following method:
  • a collection device is installed in the condensation chamber, heated to 1300 ° C under vacuum conditions to generate SiO vapor and Mg vapor in the furnace, and the uniformly mixed gaseous mixture after passing through the mixing device is cooled in the condensation chamber to obtain a silicon composite (including Si , SiO and magnesium silicate), after the reaction, the equipment was cooled and 11 kg of product was collected.
  • the obtained material is placed in a roller kiln at 960° C. for high temperature carbonization to obtain a stable silicon composite negative electrode material.
  • This embodiment provides a silicon-based negative electrode material 100 and a preparation method thereof.
  • the silicon-based negative electrode material 100 includes an inner core 120 and a carbon coating 140 covering the surface of the inner core 120 , and the inner core 120 includes silicon, silicon oxide and silicon.
  • Magnesium oxide, the thickness of the carbon coating 140 is 200 nm, and the mass fraction of Mg element is 15% based on the total mass of the negative electrode material as 100%.
  • the silicon-based negative electrode material 100 is prepared by the following method:
  • a collection device is installed in the condensation chamber, heated to 1300 ° C under vacuum conditions to generate SiO vapor and Mg vapor in the furnace, and the uniformly mixed gaseous mixture after passing through the mixing device is cooled in the condensation chamber to obtain a silicon composite (including Si , SiO and magnesium silicate), after the reaction, the equipment was cooled and 11 kg of product was collected.
  • the obtained material is placed in a roller kiln at 960° C. for high temperature carbonization to obtain a stable silicon composite negative electrode material.
  • This embodiment provides a silicon-based negative electrode material 100 and a preparation method thereof.
  • the silicon-based negative electrode material 100 includes an inner core 120 and a carbon coating 140 covering the surface of the inner core 120 , and the inner core 120 includes silicon, silicon oxide and silicon.
  • Magnesium oxide, the thickness of the carbon coating 140 is 200 nm, and the mass fraction of Mg element is 9.5% based on the total mass of the negative electrode material as 100%.
  • the silicon-based negative electrode material 100 is prepared by the following method:
  • a collection device is installed in the condensation chamber, heated to 1300 ° C under vacuum conditions to generate SiO vapor and Mg vapor in the furnace, and the uniformly mixed gaseous mixture after passing through the mixing device is cooled in the condensation chamber to obtain a silicon composite (including Si , SiO and magnesium silicate), after the reaction, the equipment was cooled and 10kg of product was collected.
  • the obtained material is placed in a roller kiln at 960° C. for high temperature carbonization to obtain a stable silicon composite negative electrode material.
  • This embodiment provides a silicon-based negative electrode material 100 and a preparation method thereof.
  • the silicon-based negative electrode material 100 includes an inner core 120 and a carbon coating 140 covering the surface of the inner core 120 , and the inner core 120 includes silicon, silicon oxide and silicon.
  • calcium acid, the thickness of the carbon coating 140 is 160 nm, and the mass fraction of Ca element is 8% based on the total mass of the negative electrode material as 100%.
  • the silicon-based negative electrode material 100 is prepared by the following method:
  • a collection device is installed in the condensation chamber, heated to 1300 ° C under vacuum conditions to generate SiO vapor and Ca vapor in the furnace, and the uniformly mixed gaseous mixture after passing through the mixing device is cooled in the condensation chamber to obtain a silicon composite (including Si , SiO and calcium silicate), after the reaction, the equipment was cooled and 8.8kg of product was collected.
  • the obtained material is placed in a roller kiln at 960° C. for high temperature carbonization to obtain a stable silicon composite negative electrode material.
  • This embodiment provides a silicon-based negative electrode material 100 and a preparation method thereof.
  • the silicon-based negative electrode material 100 includes an inner core 120 and a carbon coating 140 covering the surface of the inner core 120 , and the inner core 120 includes silicon, silicon oxide and silicon. Calcium acid, the thickness of the carbon coating 140 is 130 nm, and the mass fraction of Ca element is 9% based on the total mass of the negative electrode material as 100%.
  • the silicon-based negative electrode material 100 is prepared by the following method:
  • a collection device is installed in the condensation chamber, heated to 1350 ° C under vacuum conditions to generate SiO vapor and Ca vapor in the furnace, and the uniformly mixed gaseous mixture after passing through the mixing device is cooled in the condensation chamber to obtain a silicon composite (including Si , SiO and calcium silicate), after the reaction, the equipment was cooled and 9.6kg of product was collected.
  • the obtained material is placed in a roller kiln at 960° C. for high temperature carbonization to obtain a stable silicon composite negative electrode material.
  • This embodiment provides a silicon-based negative electrode material 100 and a preparation method thereof.
  • the silicon-based negative electrode material 100 includes an inner core 120 and a carbon coating 140 covering the surface of the inner core 120 , and the inner core 120 includes silicon, silicon oxide and silicon.
  • Magnesium oxide, the thickness of the carbon coating 140 is 50 nm, and the mass fraction of Mg element is 15% based on the total mass of the negative electrode material as 100%.
  • the silicon-based negative material 100 is prepared by the following method:
  • a collection device is installed in the condensation chamber, heated to 1300 ° C under vacuum conditions to generate SiO vapor and Mg vapor in the furnace, and the uniformly mixed gaseous mixture after passing through the mixing device is cooled in the condensation chamber to obtain a silicon composite (including Si , SiO and magnesium silicate), after the reaction, the equipment was cooled and 11 kg of product was collected.
  • silicon compound Except in the synthesis of silicon compound, (1) take 5kg silicon powder (its chemical composition is Si), 10kg silicon micropowder (its chemical composition is SiO 2 ), use a VC mixer to mix for 30min to obtain SiO raw materials, put into vacuum One end of the furnace reaction chamber close to the furnace mouth;
  • a collection device is installed in the condensation chamber, heated to 1300 ° C under vacuum conditions to generate SiO vapor and Mg vapor in the furnace, and the uniformly mixed gaseous mixture after passing through the mixing device is cooled in the condensation chamber to obtain a silicon composite, and the reaction is completed. The equipment was then cooled and 11 kg of product was collected.
  • a collection device is installed in the condensation chamber, heated to 1300 ° C under vacuum conditions to generate SiO vapor and Mg vapor in the furnace, and the uniformly mixed gaseous mixture after passing through the mixing device is cooled in the condensation chamber to obtain a silicon composite, and the reaction is completed. The equipment was then cooled and 11 kg of product was collected.
  • the obtained material is placed in a roller kiln at 960° C. for high temperature carbonization to obtain a stable silicon composite negative electrode material.
  • a collection device is installed in the condensation chamber, heated to 1300 ° C under vacuum conditions to generate SiO vapor and Mg vapor in the furnace, and the uniformly mixed gaseous mixture after passing through the mixing device is cooled in the condensation chamber to obtain a silicon composite, and the reaction is completed. The equipment was then cooled and 11 kg of product was collected.
  • the obtained material is placed in a roller kiln at 960° C. for high temperature carbonization to obtain a stable silicon composite negative electrode material.
  • a collection device is installed in the condensation chamber, heated to 1300 ° C under vacuum conditions to generate SiO vapor and Mg vapor in the furnace, and the uniformly mixed gaseous mixture after passing through the mixing device is cooled in the condensation chamber to obtain a silicon composite, and the reaction is completed. The equipment was then cooled and 11 kg of product was collected.
  • the obtained material is placed in a roller kiln at 960° C. for high temperature carbonization to obtain a stable silicon composite negative electrode material.
  • the silicon-based negative electrode material in this comparative example includes an inner core 120 and a carbon film covering the surface of the inner core 120.
  • the inner core 120 includes silicon, silicon oxide and magnesium silicate, the thickness of the carbon film is 100 nm, and the total mass of the negative electrode material is 100 nm. %, the mass fraction of Mg element is 0.5%.
  • a collection device is installed in the condensation chamber, heated to 1300 ° C under vacuum conditions to generate SiO vapor and Mg vapor in the furnace, and the uniformly mixed gaseous mixture after passing through the mixing device is cooled in the condensation chamber to obtain a silicon composite, and the reaction is completed. The equipment was then cooled and 9.8 kg of product were collected.
  • the obtained material is placed in a roller kiln at 960° C. for high temperature carbonization to obtain a stable silicon composite negative electrode material.
  • the silicon-based negative electrode material in this comparative example includes an inner core and a carbon film covering the surface of the inner core.
  • the inner core contains silicon, silicon oxide and magnesium silicate, and the thickness of the carbon film is 100 nm.
  • the mass fraction of Mg element is 35%.
  • a collection device is installed in the condensation chamber, heated to 1300 ° C under vacuum conditions to generate SiO vapor and Mg vapor in the furnace, and the uniformly mixed gaseous mixture after passing through the mixing device is cooled in the condensation chamber to obtain a silicon composite, and the reaction is completed. The equipment was then cooled and 15 kg of product was collected.
  • the obtained material is placed in a roller kiln at 960° C. for high temperature carbonization to obtain a stable silicon composite negative electrode material.
  • the prepared silicon composite anode material particles were cut with a Hitachi E-3500 ion mill, and the morphology and structure of the cross-section were observed on a Hitachi S-4800 cold field emission scanning electron microscope. The results are shown in Figures 1 to 6.
  • FIG. 1 is an electron microscope photograph of the cross section of the silicon composite negative electrode material particle in Example 1.
  • FIG. 1 It can be seen from FIG. 1 that the inner core 120 of the material forms a uniform homogeneous structure with a uniform texture, which can illustrate the silicon, silicon oxide and M silicate three in Example 1 of the embodiment. The former is a homogeneous state, and the three are mixed and uniformly distributed. At the same time, it can be seen that the outer dark part is a carbon coating.
  • FIG. 2 is an electron microscope photograph of the cross section of the silicon composite negative electrode material particle in Example 2.
  • FIG. 2 It can be seen from FIG. 2 that the core 120 of the material is also uniform in texture, so that the silicon, silicon oxide and silicate of M in Example 2 also show a state of uniform mixing.
  • the outer dark part is a carbon coating.
  • FIG. 3 is an electron microscope photograph of the cross section of the silicon composite negative electrode material particle in Comparative Example 1.
  • FIG. 3 It can be seen from FIG. 3 that the thickness of the carbon cladding layer is thinner than that of Examples 1 and 2.
  • FIG. 4 is an electron microscope photograph of the cross section of the silicon composite negative electrode material particle in Comparative Example 2.
  • FIG. 4 It can be seen from FIG. 4 that the thickness of the carbon cladding layer is thicker than that of Examples 1 and 2.
  • FIG. 5 is an electron microscope photograph of the cross section of the silicon composite negative electrode material particle in Comparative Example 3.
  • FIG. 5 It can be seen from FIG. 5 that the thickness of the carbon cladding layer is thinner than that of Examples 1 and 2.
  • FIG. 6 is an electron microscope photograph of the cross section of the silicon composite negative electrode material particle in Comparative Example 4.
  • FIG. 6 It can be seen from FIG. 6 that the thickness of the carbon cladding layer is thicker than that of Examples 1 and 2.
  • the inner core presents a number of small particle-like forms. It can be seen that when the M content in the distributed composite is higher than 30%, the excess M will rapidly react with SiO and release a large amount of heat, resulting in the generation of Si The crystal grains are very large, so it shows the appearance of uneven distribution of the inner
  • Q 1(dis) first discharge specific capacity when charging and discharging at 0.1C rate current, (mAh/g);
  • C 1(dis) the first discharge capacity when charging and discharging at 0.1C rate current, (mAh);
  • the first lithium insertion specific capacity test (mAh/g) (ie Q l(cha) ):
  • Q 1(cha) first charge specific capacity when charging and discharging at 0.1C rate current, (mAh/g);
  • the above electrochemical performance is based on the LAND battery test system of Wuhan Jinnuo Electronics Co., Ltd., under normal temperature conditions, 0.1C constant current charge and discharge, and the charge and discharge voltage is limited to 0.005 ⁇ 1.5V.
  • the first coulombic efficiencies of the experimental button cells made from the materials of Examples 1-6 and Comparative Examples 1-6 were tested at room temperature. The test results are shown in Table 1.
  • the silicon composite negative electrode material prepared by each example and the comparative example is mixed with graphite in a ratio of 10:90, and then mixed with sodium carboxymethyl cellulose CMC (as a binder) and a binder styrene-butadiene rubber SBR (as a binder).
  • Binder), conductive agent Super-P, and conductive agent KS-6 are mixed in a mass ratio of 92:2:2:2 to form a slurry, which is coated on the copper foil negative current collector 242 to control the total amount of the slurry.
  • the solid content is 50%, and through vacuum drying and rolling, the negative electrode active material layer 244 is formed, and the negative electrode 240 pole piece is prepared; the positive electrode 220 adopts a lithium piece, and uses 1mol/L LiPF
  • the three-component mixed solvent EC:DMC: EMC 1:1:1 (volume ratio)
  • the v/v solution is the electrolyte 260
  • the polypropylene microporous membrane is the separator 280 and the shell 290
  • the shell 290 is used to assemble a CR2016 simulated battery.
  • the first week discharge specific capacity (mAh/g) the first week discharge capacity/m
  • the 50th cycle discharge specific capacity (mAh/g) the 50th cycle discharge capacity/m (formula 4);
  • 50-cycle cycle retention rate (%) discharge specific capacity in the 50th cycle / discharge specific capacity in the first cycle ⁇ 100% (Formula 5);
  • the cycle performance test uses a current of 30mA for constant current charge-discharge experiments, and the charge-discharge voltage is limited to 0-1.5V.
  • the 50-cycle cycle retention rate of the experimental button battery made of the material of Example 1 was tested by using the LAND battery test system of Wuhan Jinnuo Electronics Co., Ltd.
  • the embodiment of the present disclosure limits the carbon layer thickness of the composite negative electrode material to 50nm-200nm In between, the composite negative electrode material with carbon layer thickness within this range, the surface of the composite particles can be completely covered, and the thickness is also controlled within the most suitable range, which can effectively buffer the composite during the charging and discharging process. volume expansion.
  • the thickness of the carbon layer also has a positive effect on the volume control of the material, so the capacity efficiency and cycle performance of the composite can be significantly improved.
  • Example 1 Comparative Examples 1 and 3 that when the coating thickness of the silicon composite surface is less than 50 nm, because the surface of the silicon composite particles prepared in the comparative example cannot be completely covered by the carbon layer, there are still many exposed If such a material is used in a battery, on the one hand, the exposed part will be in direct contact with the electrolyte 260, and an unstable SEI film will be formed repeatedly, resulting in excessive consumption of the electrolyte 260, resulting in decreased cycle performance.
  • Example 1 By comparing Example 1 with Comparative Examples 2 and 4, it can be seen that when the coating thickness on the surface of the silicon composite is greater than 200 nm, the carbon layer on the surface of the silicon composite particle is too thick. During the process, the thick carbon layer is easily cracked by the internal stress of the particles, resulting in the direct contact between the silicon composite and the electrolyte 260 and the deactivation of the exposed position due to loss of electrical contact, resulting in a decrease in material performance.
  • Example 1 Comparative Examples 5-6 that when the content of M in the composite is less than 1%, the amount of M that can react with SiO is very small, and Si is generated which is beneficial to improve the Coulombic efficiency of the material in the first week.
  • the amount of silicon-based anode material 100 and the silicate of M as a buffer substance in the charging and discharging process are also correspondingly small, so the first week Coulombic efficiency and cycle performance of the silicon-based negative electrode material 100 prepared with it are not significantly improved;
  • the M content is higher than 30%, the excess M will rapidly react with SiO and release a large amount of heat, resulting in extremely large Si grains, so as to prepare the silicon-based anode material 100.
  • the present disclosure illustrates the detailed process equipment and process flow of the present disclosure through the above-mentioned embodiments, but the present disclosure is not limited to the above-mentioned detailed process equipment and process flow, that is, it does not mean that the present disclosure must rely on the above-mentioned detailed process equipment and process flow. Process flow can be implemented. Those skilled in the art should understand that any improvement to the present disclosure, the equivalent replacement of each raw material of the disclosed product, the addition of auxiliary components, the selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present disclosure.
  • the present disclosure illustrates the detailed method of the present disclosure through the above-mentioned embodiments, but the present disclosure is not limited to the above-mentioned detailed method, that is, it does not mean that the present disclosure must rely on the above-mentioned detailed method to be implemented.
  • Those skilled in the art should understand that any improvement to the present disclosure, the equivalent replacement of each raw material of the disclosed product, the addition of auxiliary components, the selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present disclosure.
  • the present disclosure provides a silicon-based negative electrode material, a negative electrode, a lithium ion battery, and a preparation method thereof.
  • the silicon-based negative electrode material can improve the conductivity of the silicon composite, and can significantly improve the capacity efficiency and cycle performance of the silicon composite, and the prepared negative electrode and lithium ion battery have the characteristics of high capacity efficiency and cycle performance.

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Abstract

Matériau d'électrode négative à base de silicium (100), électrode négative (240) et batterie secondaire au lithium-Ion (200) et son procédé de préparation. Le matériau d'électrode négative à base de silicium (100) comprend : un noyau interne (120), le noyau interne (120) comprenant du silicium, un oxyde de silicium et un silicate de M, la formule chimique de l'oxyde de silicium étant SiOx, 0 < x < 2, et M étant un métal ; et un revêtement de carbone (140) formé sur une surface du noyau interne (120), l'épaisseur du revêtement de carbone (140) étant de 50 nm à 200 nm. Le procédé consiste à : réaliser un traitement de revêtement de carbone sur un composite de silicium pour former un revêtement de carbone (140) présentant une épaisseur de 50 nm à 200 nm sur une surface du composite de silicium, ce qui permet d'obtenir un matériau d'électrode négative à base de silicium (100). Le revêtement d'un composite de silicium avec un revêtement de carbone (140) présentant une épaisseur appropriée peut améliorer considérablement l'efficacité coulombienne et la performance de cyclage du composite de silicium, et ainsi une électrode négative (240) et une batterie secondaire au lithium-ion (200) préparée à l'aide de celle-ci présentent les avantages d'une efficacité coulombienne et d'une performance de cyclage élevées.
PCT/CN2021/091857 2020-07-22 2021-05-06 Matériau d'électrode négative à base de silicium, électrode négative, batterie ion-lithium, et procédé de préparation s'y rapportant WO2022016951A1 (fr)

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