CN106328909B - Nano silicon dioxide-silicon-based composite material, preparation method and lithium ion battery containing composite material - Google Patents

Nano silicon dioxide-silicon-based composite material, preparation method and lithium ion battery containing composite material Download PDF

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CN106328909B
CN106328909B CN201611031476.7A CN201611031476A CN106328909B CN 106328909 B CN106328909 B CN 106328909B CN 201611031476 A CN201611031476 A CN 201611031476A CN 106328909 B CN106328909 B CN 106328909B
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composite material
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CN106328909A (en
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肖称茂
何鹏
任建国
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BTR New Material Group Co Ltd
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Shenzhen BTR New Energy Materials Co Ltd
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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
    • H01M4/364—Composites as mixtures
    • 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
    • H01M4/62—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

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Abstract

The invention relates to a nano silicon dioxide-silicon-based composite material, a preparation method thereof and a lithium ion battery containing the composite material. The nano silicon dioxide-silicon-based composite material comprises a carbon matrix and composite particles uniformly dispersed in the carbon matrix, wherein the composite particles comprise nano silicon dioxide-silicon particles with a core-shell structure and a conductive carbon layer coated on the surface of the nano silicon dioxide-silicon particles. The method of the invention comprises the following steps: preparing nano silicon dioxide-silicon particles with a core-shell structure by controlling parameters such as the dosage of a reducing agent and an additive, coating a conductive carbon layer on the surfaces of the particles in situ by a homogeneous coating technology, and dispersing composite particles obtained by carbon coating in a carbon matrix by a fusion technology to obtain the nano silicon dioxide-silicon based composite material. The composite material disclosed by the invention is used as a negative electrode material to prepare a battery, and has the characteristics of higher specific capacity (930.5 mAh/g), long cycle life (the retention rate of the 100-time cycle capacity is more than 93.8%) and high conductivity.

Description

Nano silicon dioxide-silicon-based composite material, preparation method and lithium ion battery containing composite material
Technical Field
The invention belongs to the field of electrochemistry and the field of application of lithium ion battery cathode materials, relates to a composite material, a preparation method and a lithium ion battery containing the composite material, and particularly relates to a nano silicon dioxide-silicon based composite material, a preparation method and a lithium ion battery containing the composite material as a cathode material.
Background
The lithium ion battery is the most concerned energy storage device at present, and is mainly applied to the 3C field, and in recent years, with the continuous development of the new energy automobile market, the application of the lithium ion battery in the power automobile is also continuously expanded. With the rapid development of the market, the energy density of the battery is required to be higher and higher. The performance of the electrode material in the battery is the key to determine the energy density of the lithium ion battery. Currently commercialized lithium batteries generally use a carbon material as a negative electrode and lithium cobaltate as a positive electrode. But carbon materialThe theoretical specific energy of the material is only 372mAh g-1And the demand of the next generation of lithium ion battery can not be met.
Among various novel anode materials, silicon materials are widely considered as one of the next-generation candidate materials due to advantages of high energy density, low voltage plateau, and abundant sources. However, silicon as a negative electrode material has a fatal defect: the material is easy to be pulverized and broken due to huge volume expansion change and stress generated in the circulating process, and finally the circulating performance is seriously degraded.
In order to solve the problem of silicon volume expansion, two technical routes of silicon carbon and silicon oxygen are developed in the market with pertinence. Wherein, the silicon oxygen adopts the characteristic that silicon is dispersed in a silicon oxide network structure to effectively inhibit the volume expansion of the silicon. Oxygen affects silicon primarily in two ways: on one hand, the introduction of oxygen can cause the first efficiency and specific capacity of the material to be reduced, and meanwhile, the self performance of the material can be worsened due to the lower conductivity of silicon oxide; on the other hand, since the silicon-oxygen bond energy is stronger than the silicon-silicon bond energy, the formed silicon oxide is more stable, and lithium ion intercalation forms irreversible Li2O and Li2SiO4The buffer layer can effectively relieve volume expansion and enhance the circulation stability of the material. The silicon material with proper oxygen is introduced, certain efficiency and specific capacity are sacrificed, and more beneficial cycle performance is obtained, which is a trend of the development of the silicon-based material at present, but the specific introduction of oxygen in any form can make the oxygen-containing silicon-based composite material with any structure have better cycle performance.
Disclosure of Invention
In view of the above problems in the prior art, an object of the present invention is to provide a nano silica-silicon based composite material, a method for preparing the same, and a lithium ion battery comprising the same. The nano silicon dioxide-silicon-based composite material disclosed by the invention is stable in structure, and shows excellent cycle performance when being applied to a lithium ion battery as a negative electrode material, the first reversible capacity is more than 930.5mAh/g, the first coulombic efficiency is more than 83.2%, and the cycle capacity retention rate is more than 93.8% after 100 times.
In a first aspect, the present invention provides a nano-silica-silicon based composite material, which comprises a carbon matrix and composite particles uniformly dispersed in the carbon matrix, wherein the composite particles comprise nano-silica-silicon particles with a core-shell structure and a conductive carbon layer coated on the surfaces of the nano-silica-silicon particles.
Preferably, the median particle diameter of the nano silica-silicon based composite material is 1 to 45 μm, such as 2 μm, 4 μm, 10 μm, 11 μm, 14 μm, 17 μm, 22 μm, 24 μm, 32 μm, 36 μm, 40 μm, 43 μm or 45 μm, etc., preferably 3 to 35 μm, more preferably 5 to 25 μm, and particularly preferably 5 to 15 μm.
Preferably, the specific surface area of the nano silicon dioxide-silicon-based composite material is 1-55 m2In g, e.g. 3m2/g、5m2/g、10m2/g、15m2/g、16m2/g、19m2/g、24m2/g、28m2/g、32m2/g、36m2/g、40m2/g、45m2/g、50m2/g、52m2(iv)/g or 55m2G, etc., preferably 2 to 20m2(ii)/g, more preferably 3 to 15m2/g。
Preferably, the powder compaction density of the nano silicon dioxide-silicon-based composite material is 0.4-2.6 g/cm3E.g. 0.4g/cm3、0.8g/cm3、1.2/cm3、1.5g/cm3、2g/cm3Or 2.6g/cm3Etc., preferably 0.5 to 2.2g/cm3More preferably 0.9 to 2g/cm3Preferably 0.7 to 1.8g/cm3。
Preferably, the mass percentage of the carbon matrix in the composite material is 10 to 60 wt%, such as 10 wt%, 15 wt%, 21 wt%, 25 wt%, 30 wt%, 32 wt%, 35 wt%, 40 wt%, 44 wt%, 47 wt%, 52 wt%, 58 wt%, etc., preferably 20 to 60 wt%, based on 100% of the total mass of the composite material.
Preferably, the mass percentage of the nano silica-silica core-shell structured particles in the composite material is 5 to 80 wt%, such as 5 wt%, 14 wt%, 17 wt%, 22 wt%, 27 wt%, 29 wt%, 31 wt%, 44 wt%, 49 wt%, 53 wt%, 60 wt%, 71 wt%, or 80 wt%, etc., based on 100% of the total mass of the composite material.
Preferably, the mass percentage of the conductive carbon layer in the composite material is 1 to 40 wt%, such as 1 wt%, 4 wt%, 11 wt%, 15 wt%, 21 wt%, 25 wt%, 32 wt%, 35 wt%, 38 wt%, 40 wt%, etc., based on 100% of the total mass of the composite material.
Preferably, the structure of the nano silicon dioxide-silicon particles is a core-shell structure, the inner core of the nano silicon dioxide-silicon particles is nano silicon dioxide particles, and the shell of the nano silicon dioxide-silicon particles is a nano silicon layer.
Preferably, the particle size of the inner core nano silicon dioxide particle is 1-50 nm, such as 2nm, 4nm, 8nm, 13nm, 15nm, 20nm, 25nm, 30nm, 34nm, 40nm, 45nm, 48nm or 50 nm.
Preferably, the thickness of the shell nano silicon layer is 5-40 nm, such as 5nm, 10nm, 15nm, 20nm, 24nm, 28nm, 32nm, 35nm, 38nm or 40 nm.
Preferably, the nanosilica-silicon particles have an oxygen content of 8% to 40% by weight, such as 8%, 12%, 15%, 22%, 28%, 33%, 36%, or 40% by weight, and the like.
Preferably, the specific surface area of the nano silicon dioxide-silicon particles is 20-500 m2G, e.g. 20m2/g、35m2/g、50m2/g、70m2/g、80m2/g、120m2/g、140m2/g、160m2/g、200m2/g、240m2/g、260m2/g、285m2/g、300m2/g、330m2/g、360m2/g、400m2/g、450m2G or 500m2A concentration of 50 to 400m is preferred2/g。
In a second aspect, the present invention provides a method for preparing a nanosilica-silicon-based composite material as defined in the first aspect, the method comprising the steps of:
(1) mixing nano silicon oxide, a reducing agent and an additive according to the proportion of (0.5-1) to (1-12), performing homogeneous phase compounding, performing heat treatment, and performing water washing and acid treatment on a heat treatment product to obtain nano silicon dioxide-silicon particles with a core-shell structure;
(2) carrying out homogeneous in-situ carbon coating on the nano silicon dioxide-silicon particles in the step (1) to obtain composite particles consisting of the nano silicon dioxide-silicon particles and a conductive carbon layer, wherein the conductive carbon layer is coated on the surfaces of the nano silicon dioxide-silicon particles;
(3) and (3) uniformly compounding the composite particles obtained in the step (2) with a carbon source, performing fusion treatment, and performing heat treatment to obtain the nano silicon dioxide-silicon-based composite material.
Preferably, the mass ratio of the nano silicon oxide, the reducing agent and the additive in the step (1) is 1 (0.5-1): (1-12), such as 1:0.5:1, 1:0.6:4, 1:0.7:12, 1:0.8:8, 1:0.9:10, 1:0.3:11, 1:0.5:8, 1:0.6:12, 1:0.2:9 or 1:0.3: 10.
In the step (1), the additive is molten and absorbs heat, and the addition of a proper amount of additive can well absorb the heat released by the reduction reaction and control the reaction temperature, so that on one hand, the generation of impurities such as metal silicide and the like can be avoided, and the reaction conversion rate is improved; on the other hand, the growth of the nano silicon can be inhibited, and the nano silicon dioxide-silicon particles with the core-shell structure with low grain value can be formed by matching with a proper amount of reducing agent.
In the step (1), the ratio of the inner core nano silicon dioxide and the outer shell nano silicon layer in the core-shell structure can be controlled by controlling the addition of the reducing agent and the addition of the additive, so that nano silicon dioxide-silicon particles with the core-shell structure are formed, and the cycle life of the material is prolonged.
In order to better play a role of the additive in regulating and controlling heat and be more beneficial to preparing the nano silicon dioxide-silicon particles with the core-shell structure, the preferred mass ratio of the nano silicon oxide to the additive is 1 (8-12).
In order to achieve a better reduction effect to prepare the nano silicon dioxide-silicon particles with the core-shell structure, the nano silicon oxide is not completely reduced into the nano silicon, and the reduction degree is not insufficient, the preferable mass ratio of the nano silicon oxide to the reducing agent is 1 (0.5-0.8), the nano silicon dioxide-silicon particles obtained through reaction are in the core-shell structure, and the inner core and the outer shell of the nano silicon dioxide-silicon particles are respectively the nano silicon dioxide particles and the nano silicon layer.
As a preferable technical scheme of the preparation method of the silicon-based composite material, the method further comprises the steps of crushing, screening and demagnetizing the heat treatment product after the heat treatment in the step (3) is completed.
Preferably, the chemical composition of the nano silicon oxide in the step (1) is SiOxWherein, X is more than or equal to 1 and less than or equal to 2, for example, X is 1, 1.2, 1.5, 1.8 or 2, etc.
Preferably, the nano silicon oxide in the step (1) has a median particle diameter of 1 to 160nm, such as 1nm, 5nm, 10nm, 20nm, 30nm, 40nm, 45nm, 50nm, 60nm, 70nm, 85nm, 100nm, 115nm, 125nm, 140nm, 150nm, 160nm, and the like.
Preferably, the reducing agent in step (1) includes any one or a combination of at least two of the simple metals such as potassium, calcium, sodium, magnesium, aluminum, zinc, iron, copper and nickel, but is not limited to the above-mentioned metals, and other reducing agents that can perform the same function can also be used in the present invention.
Preferably, the median particle diameter of the reducing agent in the step (1) is 20-50 μm, such as 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 42 μm, 45 μm, 46 μm, 48 μm or 50 μm.
Preferably, the mass ratio of the nano silicon oxide to the reducing agent in the step (1) is 1 (0.5-0.8), such as 1:0.5, 1:0.6, 1:0.65, 1:0.7, 1:0.75 or 1: 0.8.
Preferably, the additive in step (1) comprises any one of potassium chloride, potassium carbonate, potassium nitrate, potassium sulfate, sodium chloride, sodium carbonate, sodium nitrate or sodium sulfate or a combination of at least two of the above.
The additive of the invention is not limited to the above additives, but can also be other additives capable of achieving the same effect, but the requirements that the melting point of the ① additive is 600-900 ℃ and is close to the reaction temperature (the difference between the melting point of the additive and the reaction temperature is 50-100 ℃), and the ② additive does not react with reactants (nano silicon oxide and reducing agent) are met.
Preferably, the median particle diameter of the additive in the step (1) is 100-200 meshes, such as 100 meshes, 120 meshes, 150 meshes or 200 meshes.
Preferably, the homogeneous phase in step (1) is: and (3) uniformly mixing the nano silicon oxide, the additive and the reducing agent to obtain a homogeneous mixture.
Preferably, the methods employed for homogeneous mixing include a dry mixing method and a wet mixing method, preferably a dry mixing method.
Preferably, the dry mixing method is a dry ball milling method or a method of mixing in a VC mixer.
Preferably, the ball mill used in the dry ball milling method is any one of a planetary ball mill, a high-speed stirring mill, a tube mill, a cone mill, a rod mill and a sand mill.
Preferably, the method for mixing in the VC mixer is as follows: and (2) placing the nano silicon oxide, the reducing agent and the additive in the step (1) into a VC mixer, and mixing to obtain a homogeneous mixture.
Preferably, the heat treatment of step (1) is: the homogeneous mixture is placed in a closed container and heat treated under a non-oxidizing atmosphere.
Preferably, during the heat treatment in step (1), the non-oxidizing atmosphere is any one of a nitrogen atmosphere, a hydrogen atmosphere, a helium atmosphere, an argon atmosphere, or a neon atmosphere, or a combination of at least two of them.
Preferably, the temperature of the heat treatment in step (1) is 600 to 950 ℃, such as 600 ℃, 620 ℃, 630 ℃, 640 ℃, 660 ℃, 680 ℃, 710 ℃, 750 ℃, 780 ℃, 805 ℃, 825 ℃, 850 ℃, 880 ℃, 910 ℃ or 950 ℃.
Preferably, the time of the heat treatment in the step (1) is 1 to 6 hours, such as 1 hour, 1.3 hours, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.2 hours, 4.4 hours, 4.6 hours, 5 hours, 5.5 hours or 6 hours.
Preferably, the acid treatment of step (1) is: and (4) placing the heat treatment product in a container, and adding acid for treatment.
Preferably, in the acid treatment process in the step (1), the treatment is soaking, or soaking with stirring.
Preferably, in the acid treatment process in the step (1), the treatment time is 1-8 h, such as 1h, 2h, 3h, 4h, 4.5h, 5h, 6h, 7h or 8h, and preferably 1-4 h.
Preferably, in the acid treatment of step (1), the acid is selected from an oxide (K) capable of forming with a reducing agent metal (M ═ K, Ca, Na, Mg, Al, Zn, Fe, Cu, or Ni)2O、CaO、Na2O、MgO、Al2O3、ZnO、Fe2O3CuO, NiO, etc.) is preferably any one or a combination of at least two of hydrochloric acid, nitric acid, nitrous acid, sulfuric acid, sulfurous acid, carbonic acid, boric acid, phosphoric acid, hydrocyanic acid, perchloric acid, acetic acid, benzoic acid, or selenic acid. The invention avoids using hydrofluoric acid with strong toxicity in the acid treatment process, and the preparation process is environment-friendly.
Preferably, in the acid treatment process in the step (1), the concentration of the acid is 0.1-10 mol/L, such as 0.1mol/L, 0.5mol/L, 1mol/L, 2mol/L, 3mol/L, 3.5mol/L, 4mol/L, 4.5mol/L, 5mol/L, 6mol/L, 7mol/L, 8mol/L, 9mol/L or 10 mol/L.
Preferably, the method further comprises the steps of centrifuging, suction filtering and drying after the acid treatment in the step (1) is completed.
Preferably, the homogeneous in-situ carbon coating in the step (2) is performed by any one of a gas phase coating method, a liquid phase coating method or a solid phase coating method, and preferably by a gas phase coating method.
Preferably, the homogeneous in-situ carbon coating is performed by a gas phase coating method, wherein the gas phase coating method comprises the following steps: and introducing a gas-phase carbon source into the reaction furnace filled with the nano silicon dioxide-silicon particles, and carrying out in-situ deposition coating under the condition of rotation of the reaction furnace to obtain composite particles consisting of the nano silicon dioxide-silicon particles and a conductive carbon layer, wherein the conductive carbon layer is coated on the surfaces of the nano silicon dioxide-silicon particles.
Preferably, in the gas phase coating method, the gas phase carbon source is any one or a combination of at least two of methane, ethane, propane, ethylene, acetylene, propylene, gaseous benzene, gaseous toluene, gaseous xylene, gaseous ethanol, or gaseous acetone, and is preferably a combination of methane, acetylene, and gaseous toluene.
Preferably, in the vapor phase coating method, the rotation speed of the reaction furnace is 0.2 to 8rpm, for example, 0.2rpm, 0.8rpm, 1rpm, 1.3rpm, 1.8rpm, 2.2rpm, 3rpm, 4rpm, 5rpm, 6rpm, 7rpm, 8rpm, or the like.
Preferably, in the gas phase coating method, the flow rate of the gas phase carbon source is 0.1-1.2L/min, such as 0.1L/min, 0.5L/min, 0.8L/min, 1L/min or 1.2L/min.
Preferably, in the vapor phase coating method, the temperature of the in-situ deposition coating is 600 to 1000 ℃, such as 600 ℃, 700 ℃, 750 ℃, 800 ℃, 850 ℃, 900 ℃ or 1000 ℃, and the like, and preferably 800 to 1000 ℃.
Preferably, in the vapor phase coating method, the in-situ deposition coating time is 3-6 h, such as 3h, 3.5h, 4h, 4.2h, 4.5h, 5h, 5.2h, 5.4h, 5.6h or 6 h.
According to the invention, homogeneous in-situ carbon coating is carried out on the nano silicon dioxide-silicon particles with the core-shell structure through vapor deposition, so that the conductivity of the particles is improved, and the rate capability of the material is favorably improved; in addition, the carbon coating layer on the surface of the nano-particles can inhibit side reactions between the active substance nano-silicon dioxide-silicon particles and electrolyte, and is beneficial to improving the stability of the material.
Preferably, the homogeneous phase composite in step (3) adopts any one of a solid phase coating method, a liquid phase coating method or a gas phase coating method, and preferably adopts a solid phase coating method.
Preferably, the fusing process of step (3) includes: and (3) uniformly mixing the composite particles obtained in the step (2) with a carbon source, and adding the mixture into a fusion machine for fusion.
Preferably, during the fusion treatment, the rotation speed of the fusion machine is 600 to 3000rpm, such as 600rpm, 800rpm, 1000rpm, 1300rpm, 1500rpm, 1700rpm, 2000rpm, 2400rpm, 2700rpm or 3000rpm, and preferably 300 to 2000 rpm.
Preferably, during the fusion treatment, the cutter gap of the fusion machine is 0.01-1 cm, such as 0.05cm, 0.1cm, 0.2cm, 0.3cm, 0.4cm, 0.5cm, 0.6cm, 0.7cm, 0.8cm or 1cm, preferably 0.1-0.3 cm.
Preferably, during the fusion treatment, the fusion time is at least 0.25h, such as 0.25h, 1h, 2.5h, 4h, 6h, 8h, 15h, 16h, 24h, 28h, 36h, 40h, 48h or 52h, etc., preferably 0.25-8 h, and particularly preferably 0.5-4 h.
Preferably, the carbon source in step (3) is any one or a combination of at least two of coal pitch, petroleum pitch, mesophase pitch, coal tar, petroleum industry heavy oil, heavy aromatic hydrocarbon, epoxy resin, phenolic resin, furfural resin, urea resin, polyvinyl alcohol, polyvinyl chloride, polyethylene glycol, polyethylene oxide, polyvinylidene fluoride, acrylic resin or polyacrylonitrile.
Preferably, the carbon source in step (3) has a particle size of 2-5 μm, such as 2 μm, 2.5 μm, 3 μm, 3.2 μm, 3.6 μm, 4 μm, 4.3 μm, 4.5 μm, or 5 μm.
Preferably, a shielding gas is introduced during the heat treatment in the step (3), and the shielding gas is any one or a combination of at least two of nitrogen, helium, neon, argon or krypton.
Preferably, the temperature of the heat treatment in the step (3) is 700 to 1000 ℃, such as 700 ℃, 720 ℃, 750 ℃, 775 ℃, 800 ℃, 820 ℃, 850 ℃, 900 ℃, 950 ℃ or 1000 ℃, etc
Preferably, the time of the heat treatment in the step (3) is 2-6 h, such as 2h, 2.5h, 3h, 4h, 4.3h, 4.6h, 5h, 5.5h or 6 h.
In the invention, the fusion and solid phase, gas phase and liquid phase coating technology is introduced in the step (3) to uniformly coat the outer layer of the particles, and a compact coating layer is formed on the outer layer.
In a third aspect, the present invention provides an anode material, wherein the anode material is the nano silica-silicon based composite material according to the first aspect.
In a fourth aspect, the present invention provides a lithium ion battery, wherein the lithium ion battery comprises the nano silica-silicon based composite material according to the first aspect as a negative electrode material in the lithium ion battery.
Compared with the prior art, the invention has the following beneficial effects:
(1) the method comprises the steps of adopting metal to reduce silicon oxide, regulating and controlling reduction degree, reaction temperature and nano-silicon particle size by controlling reduction reaction parameters such as the dosage of a reducing agent and an additive, inhibiting impurity generation, preparing nano-silica-silicon particles with a core-shell structure, coating a conductive carbon layer on the surfaces of the nano-silica-silicon particles in situ by a homogeneous coating technology to obtain composite particles, and uniformly dispersing the composite particles in a carbon matrix by a fusion technology to obtain the nano-silica-silicon based composite material. The method has the advantages of good processing performance, simple process, environmental friendliness, no pollution and great application potential.
(2) The nano silicon dioxide-silicon-based composite material comprises a carbon matrix and composite particles dispersed in the carbon matrix, wherein the composite particles are composed of nano silicon dioxide-silicon particles with low grain values and core-shell structures and conductive carbon layers coated on the surfaces of the nano silicon dioxide-silicon particles, and the core-shell structures and the multiple carbon layers cooperate to reduce the volume expansion of the material in the charging and discharging processes. In the nano silicon dioxide-silicon particles with the core-shell structure, the expansion rate of nano silicon is low, and irreversible Li formed by the nano silicon dioxide in the lithium intercalation process2O，Li2SiO4The volume expansion is inhibited, and the proportion of the silicon and oxygen of the particles with the core-shell structure is controllable, so that the expansion rate is lower, and the cycle performance of the material is improved; the coating of the conductive carbon layer and the coating of the carbon substrate are beneficial to improving the conductivity of the material, improving the electron mobility and the rate capability, reducing the side reaction of the active substance nano silicon dioxide-silicon particles and the electrolyte and improving the stability of the material.
(3) In the composite material, the combined action of the oxygen and the carbon reduces the volume expansion of silicon, and improves the cycle performance and rate capability of the material. The prepared battery has high specific capacity, high first coulombic efficiency and good cycle performance, the first reversible capacity is more than 930.5mAh/g, the first coulombic efficiency is more than 83.2 percent, and the cycle capacity retention rate is more than 93.8 percent after 100 times by using the composite material as the negative electrode material of the battery.
Drawings
Fig. 1a is a schematic structural diagram of a nano silica-silicon based composite anode material of the present invention, wherein 1 represents a carbon matrix; 2 represents a composite particle;
FIG. 1b is a schematic diagram of the structure of the composite particle shown in FIG. 1a, wherein 3 represents a nano-silica particle, 4 represents a nano-silicon layer, and 5 represents a conductive carbon layer;
FIG. 2 is a Scanning Electron Microscope (SEM) picture of the core-shell structured nano-silica-silicon particles prepared in step (1) of example 1 of the present invention;
fig. 3 is an SEM image of the nano silica-silicon based composite anode material prepared in example 1 of the present invention;
fig. 4 is an XRD spectrum of the nano silica-silicon based composite anode material prepared in example 1 of the present invention;
fig. 5 is a first charge-discharge curve obtained by testing electrochemical performance of a battery made of the nano-silica-silicon-based composite anode material prepared in example 1 of the present invention;
fig. 6 is a cycle performance curve obtained by testing electrochemical performance of a battery made of the nano-silica-silicon-based composite anode material prepared in example 1 of the present invention.
Detailed Description
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.
The composite materials prepared in examples 1 to 5 and comparative example 1 were used as negative electrode materials to prepare batteries under the same conditions, and electrochemical properties such as cycle performance and the like were tested, and the specific battery preparation method was as follows: dissolving a negative electrode material, a conductive agent carbon black SP and a binder sodium carboxymethyl cellulose CMC (carboxymethyl cellulose) in a solvent deionized water according to a mass percentage of 94:1:5, mixing, controlling the solid content to be 50%, coating the mixture on a copper foil current collector, and really coating the mixture on the copper foil current collectorDrying in air to obtain a negative pole piece, wherein a metal lithium piece and 1.2mol/L LiPF are used as a counter electrode6And the button cell of the model LIR2016 is assembled by adopting/EC + DMC + EMC (v/v is 1:1:1) electrolyte and Celgard2400 diaphragm.
The charge and discharge test of the button cell is carried out on a LAND cell test system of Wuhanjinnuo electronic Limited company, and the charge and discharge voltage is limited to 0.005-1.5V at the constant current charge and discharge of 0.1C under the normal temperature condition.
Example 1
A preparation method of a nano silicon dioxide-silicon-based composite negative electrode material for a lithium ion battery comprises the following steps:
(1) SiO with the median particle diameter of 50nm 250 mu m of magnesium metal powder and 100-mesh potassium chloride are mixed according to the mass ratio of 1:0.85:12, and are put into a VC machine, the frequency is set to be 30HZ, and the time is set to be 40 min. And then placing the fully and uniformly mixed materials in a reaction crucible, introducing argon, heating to 950 ℃, reacting for 1h, soaking the reacted product in 1mol/L HCl solution for 4h, centrifuging, performing suction filtration, washing for 3 times by using water, and drying in a vacuum drying oven at 80 ℃ to obtain the nano silicon dioxide-silicon particles with the core-shell structure.
(2) And (2) placing the nano silicon dioxide-silicon particles in a rotary furnace, introducing methane gas with the flow rate of 0.1L/min, controlling the rotating speed of the rotary furnace to be 0.8rpm, then heating to 1000 ℃, and preserving heat for 3 hours to obtain composite particles consisting of the nano silicon dioxide-silicon particles and a conductive carbon layer, wherein the conductive carbon layer is coated on the surfaces of the nano silicon dioxide-silicon particles.
(3) Scattering the composite particles, mixing the composite particles with phenolic resin with the particle size of 5 mu m according to the mass ratio of 80:20, uniformly mixing, then placing the mixture in a fusion machine, adjusting the rotating speed to 2000rpm, enabling the width of a cutter gap to be 0.5cm, fusing for 1h to obtain a fusion product, then adding the fusion product into a high-temperature box-type furnace, introducing nitrogen protection gas, heating to 900 ℃, and preserving heat for 5h to obtain the nano silicon dioxide-silicon based composite negative electrode material.
Fig. 2 is a Scanning Electron Microscope (SEM) picture of the core-shell structured nano silica-silicon particles prepared in step (1) of example 1 of the present invention, from which it can be observed that the nano silica-silicon is in a granular form, and the average particle size thereof is less than 50 nm.
Fig. 3 is an SEM image of the nano silica-silicon based composite anode material prepared in example 1 of the present invention, and it can be observed that the composite anode material particles are in a sphere-like shape and uniformly dispersed in a single particle.
Fig. 4 is an XRD spectrum of the nano silica-silicon based composite anode material prepared in example 1 of the present invention, from which it can be observed that there is only a diffraction peak of nano silicon and there is almost no diffraction peak of carbon, mainly because the conductive carbon layer and the carbon matrix are amorphous cracked carbon. In addition, the diffraction bag is weaker in 20-30 degrees, which corresponds to the existence of amorphous silicon dioxide in the material.
Fig. 5 is a first charge-discharge curve obtained by testing electrochemical performance of a battery made of the nano-silica-silicon-based composite negative electrode material prepared in example 1 of the present invention, and it can be seen from the figure that the first charge-discharge capacity of the composite negative electrode material is higher, which is 1250.0mAh/g, and the first coulombic efficiency is 86%.
Fig. 6 is a cycle performance curve obtained by testing electrochemical performance of a battery made of the nano-silica-silicon-based composite anode material prepared in example 1 of the present invention, and it can be seen from the figure that the material has excellent cycle performance, and the capacity retention rate is 94.2% after 100 cycles.
The data of the powder compaction density and the specific surface area of the negative electrode material of the present example are shown in table 1.
The electrochemical performance data obtained from the test of the battery made from the negative electrode material of this example are shown in table 1.
Example 2
A preparation method of a nano silicon dioxide-silicon-based composite negative electrode material for a lithium ion battery comprises the following steps:
(1) SiO with the median particle diameter of 160nm 220 mu m of metal sodium powder and 200 meshes of NaCl are mixed according to the mass ratio of 1:0.5:8, and the mixture is loaded into a VC machine, the frequency is set to be 20HZ, and the time is 1 h. Then placing the mixed material in a heat treatment furnace, introducing argon, heating to 750 ℃, reacting for 3 hours, and dissolving the product after the reaction with 1mol/L HClSoaking the solution for 2h, centrifuging, filtering, and drying in a vacuum drying oven at 80 ℃ to obtain the core-shell structure nano silicon dioxide-silicon particles.
(2) Placing the nano silicon dioxide-silicon particles in a rotary furnace, introducing acetylene gas with the flow rate of 0.3L/min, controlling the rotating speed of the rotary furnace to be 0.8rpm, then heating to 800 ℃, and preserving heat for 3 hours to obtain composite particles consisting of the nano silicon dioxide-silicon particles and a conductive carbon layer, wherein the conductive carbon layer is coated on the surfaces of the nano silicon dioxide-silicon particles.
(3) Scattering the composite particles, mixing the composite particles with asphalt powder with the particle size of 3 mu m according to the mass ratio of 80:20, uniformly mixing the composite particles and the asphalt powder, putting the mixture into a fusion machine, adjusting the frequency to 3000rpm and the width of a cutter gap to 1.0cm, mixing the mixture for 0.5h to obtain a fusion product, adding the fusion product into a high-temperature box-type furnace, introducing nitrogen protection gas, heating to 1000 ℃, and preserving the heat for 6h to obtain the nano silicon dioxide-silicon based composite negative electrode material.
The data of the powder compaction density and the specific surface area of the negative electrode material of the present example are shown in table 1.
The electrochemical performance data obtained from the test of the battery made from the negative electrode material of this example are shown in table 1.
Example 3
A preparation method of a nano silicon dioxide-silicon-based composite negative electrode material for a lithium ion battery comprises the following steps:
(1) SiO with the median particle diameter of 20nm 250 mu m of metal magnesium powder and 200 meshes of KCl are mixed according to the mass ratio of 1:1:8 and are put into a VC machine, the frequency is set to be 20HZ, and the time is 1 h. And then placing the mixed material in a heat treatment furnace, introducing argon, heating to 600 ℃, reacting for 6 hours, soaking the reacted product in 0.5mol/L HCl solution for 2 hours, centrifuging, filtering, and drying in a vacuum drying oven at 80 ℃ to obtain the nano silicon dioxide-silicon particles with the core-shell structure.
(2) And (2) placing the nano silicon dioxide-silicon particles in a rotary furnace, introducing acetylene gas at the flow rate of 1L/min, controlling the rotating speed of the rotary furnace to be 0.8rpm/min, heating to 900 ℃, and preserving heat for 6 hours to obtain composite particles consisting of the nano silicon dioxide-silicon particles and a conductive carbon layer, wherein the conductive carbon layer is coated on the surfaces of the nano silicon dioxide-silicon particles.
(3) Scattering the composite particles, mixing the composite particles with asphalt powder with the particle size of 5 mu m according to the mass ratio of 80:20, uniformly mixing, then placing the mixture in a fusion machine, adjusting the frequency to 500rpm, adjusting the width of a cutter gap to 0.01cm, mixing for 0.25h to obtain a fusion product, then adding the fusion product into a high-temperature box furnace, introducing nitrogen protection gas, heating to 1000 ℃, and preserving heat for 6h to obtain the nano silicon dioxide-silicon based composite negative electrode material.
The data of the powder compaction density and the specific surface area of the negative electrode material of the present example are shown in table 1.
The electrochemical performance data obtained from the test of the battery made from the negative electrode material of this example are shown in table 1.
Example 4
A preparation method of a nano silicon dioxide-silicon-based composite negative electrode material for a lithium ion battery comprises the following steps:
(1) SiO with the median particle diameter of 20nm 230 mu m of metal aluminum powder and 200 meshes of NaCl are mixed according to the mass ratio of 1:1:9 and are put into a VC machine, the frequency is set to be 20HZ, and the time is 1 h. And then placing the mixed material in a heat treatment furnace, introducing argon, heating to 950 ℃, reacting for 2 hours, soaking the reacted product in 0.5mol/L HCl solution for 2 hours, centrifuging, filtering, and drying in a vacuum drying oven at 80 ℃ to obtain the nano silicon dioxide-silicon particles with the core-shell structure.
(2) And (2) placing the nano silicon dioxide-silicon particles in a rotary furnace, introducing acetylene gas with the flow rate of 0.3L/min, controlling the rotating speed of the rotary furnace to be 0.8rpm/min, then heating to 900 ℃, and preserving heat for 3 hours to obtain composite particles consisting of the nano silicon dioxide-silicon particles and a conductive carbon layer, wherein the conductive carbon layer is coated on the surfaces of the nano silicon dioxide-silicon particles.
(3) Scattering the composite particles, mixing the composite particles with epoxy resin powder with the particle size of 2 mu m according to a mass ratio of 80:20, uniformly mixing the composite particles and the epoxy resin powder, putting the mixture into a fusion machine, adjusting the frequency to 1000rpm and the tool pitch to 0.5cm, mixing the mixture for 2.0h to obtain a fusion product, adding the fusion product into a high-temperature box-type furnace, introducing nitrogen protection gas, heating to 700 ℃, and preserving the temperature for 2h to obtain the nano silicon dioxide-silicon based composite negative electrode material.
The data of the powder compaction density and the specific surface area of the negative electrode material of the present example are shown in table 1.
The electrochemical performance data obtained from the test of the battery made from the negative electrode material of this example are shown in table 1.
Example 5
A preparation method of a nano silicon dioxide-silicon-based composite negative electrode material for a lithium ion battery comprises the following steps:
(1) SiO with the median particle diameter of 30nm 230 mu m of magnesium metal powder and 150-mesh potassium chloride are mixed according to the mass ratio of 1:0.5:11, and are put into a VC machine, the frequency is set to be 25HZ, and the time is 1 h. And then placing the fully and uniformly mixed materials in a reaction crucible, introducing helium, heating to 850 ℃, reacting for 0.5h, soaking the reacted product in 5mol/L HCl solution for 2h, centrifuging, performing suction filtration, washing for 3 times by using water, and drying in a vacuum drying oven at 90 ℃ to obtain the nano silicon dioxide-silicon particles with the core-shell structure.
(2) And (2) placing the nano silicon dioxide-silicon particles in a rotary furnace, introducing a mixed gas of methane and acetylene at a flow rate of 0.8L/min, controlling the rotating speed of the rotary furnace to be 3rpm, heating to 950 ℃, and preserving heat for 4.5 hours to obtain composite particles consisting of the nano silicon dioxide-silicon particles and a conductive carbon layer, wherein the conductive carbon layer is coated on the surfaces of the nano silicon dioxide-silicon particles.
(3) Scattering the composite particles, mixing the composite particles with phenolic resin with the particle size of 3 mu m according to the mass ratio of 80:20, uniformly mixing, then placing the mixture in a fusion machine, adjusting the rotating speed to 2500rpm, enabling the width of a cutter gap to be 1cm, fusing for 5 hours to obtain a fusion product, then adding the fusion product into a high-temperature box-type furnace, introducing nitrogen protection gas, heating to 800 ℃, and preserving heat for 4 hours to obtain the nano silicon dioxide-silicon based composite negative electrode material.
The data of the powder compaction density and the specific surface area of the negative electrode material of the present example are shown in table 1.
The electrochemical performance data obtained from the test of the battery made from the negative electrode material of this example are shown in table 1.
Comparative example 1
The preparation method and conditions were the same as in example 1, except that the step (1) was not performed, and commercial nano-silicon particles (particle size of 120nm) were directly used instead of the nano-silica-silicon particles in the step (2).
The powder compaction density and specific surface area data for the composite of this comparative example are shown in table 1.
The composite material of the comparative example was used as a negative electrode to prepare a battery, and the electrochemical performance data obtained by the test are shown in table 1.
TABLE 1
Figure BDA0001156495430000171
The applicant states that the present invention is illustrated in detail by the above examples, but the present invention is not limited to the above detailed methods, i.e. it is not meant that the present invention must rely on the above detailed methods for its implementation. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

Claims (67)

1. The nano silicon dioxide-silicon-based composite material is characterized by comprising a carbon matrix and composite particles uniformly dispersed in the carbon matrix, wherein the composite particles comprise nano silicon dioxide-silicon particles with a core-shell structure and a conductive carbon layer coated on the surfaces of the nano silicon dioxide-silicon particles;
the nano silicon dioxide-silicon particles are of a core-shell structure, and the inner core and the shell of each nano silicon dioxide-silicon particle are respectively a nano silicon dioxide particle and a nano silicon layer;
the nano silicon dioxide-silicon-based composite material is prepared by the following method, and the preparation method comprises the following steps:
(1) mixing nano silicon oxide, a reducing agent and an additive according to the proportion of (0.5-0.8) to (8-12) of 1, carrying out homogeneous phase compounding, then carrying out heat treatment, and carrying out water washing and acid treatment on a heat treatment product to obtain nano silicon dioxide-silicon particles with a core-shell structure;
(2) carrying out homogeneous in-situ carbon coating on the nano silicon dioxide-silicon particles in the step (1) to obtain composite particles consisting of the nano silicon dioxide-silicon particles and a conductive carbon layer, wherein the conductive carbon layer is coated on the surfaces of the nano silicon dioxide-silicon particles;
(3) uniformly compounding the composite particles obtained in the step (2) with a carbon source, performing fusion treatment, and performing heat treatment to obtain a nano silicon dioxide-silicon based composite material;
wherein, the reducing agent in the step (1) comprises any one or the combination of at least two of potassium, calcium, sodium, magnesium, aluminum, zinc, iron, copper or nickel; the additive in the step (1) comprises any one or the combination of at least two of potassium chloride, potassium carbonate, potassium nitrate, potassium sulfate, sodium chloride, sodium carbonate, sodium nitrate or sodium sulfate; the temperature of the heat treatment in the step (1) is 600-950 ℃;
the homogeneous phase compounding method in the step (3) is a solid phase coating method, and the particle size of the carbon source in the step (3) is 2-5 mu m.
2. The nanosilica-silicon-based composite material of claim 1, wherein the composite material has a median particle size of 1 to 45 μm.
3. The nanosilica-silicon-based composite material of claim 2, wherein the composite material has a median particle size of 3 to 35 μm.
4. The nanosilica-silicon-based composite material of claim 3, wherein the composite material has a median particle size of 5 to 25 μm.
5. The nanosilica-silicon-based composite material of claim 4, wherein the composite material has a median particle size of 5 to 15 μm.
6. The nano silica-based composite material according to claim 1, wherein the specific surface area of the composite material is 1-55 m2/g。
7. The nano-silica-based composite material according to claim 6, wherein the specific surface area of the composite material is 2-20 m2/g。
8. The nano silica-based composite material according to claim 7, wherein the specific surface area of the composite material is 3-15 m2/g。
9. The nano silicon dioxide-silicon-based composite material as claimed in claim 1, wherein the powder compaction density of the composite material is 0.4-2.6 g/cm3。
10. The nano silicon dioxide-silicon-based composite material as claimed in claim 9, wherein the powder compaction density of the composite material is 0.5-2.2 g/cm3。
11. The nano-silica-based composite material according to claim 10, wherein the powder compaction density of the composite material is 0.9-2 g/cm3。
12. The nano silicon dioxide-silicon-based composite material as claimed in claim 11, wherein the powder compaction density of the composite material is 0.7-1.8 g/cm3。
13. The nanosilica-silicon-based composite material according to claim 1, wherein the mass percentage of the carbon matrix in the composite material is 10 to 60 wt% based on 100% of the total mass of the composite material.
14. The nanosilica-silicon-based composite material according to claim 13, wherein the mass percentage of the carbon matrix in the composite material is 20-60 wt% based on 100% of the total mass of the composite material.
15. The nano silica-silicon-based composite material according to claim 1, wherein the mass percentage of the nano silica-silicon core-shell structure particles in the composite material is 5 to 80 wt% based on 100% of the total mass of the composite material.
16. The nano silica-silicon based composite material according to claim 1, wherein the conductive carbon layer is present in the composite material in an amount of 1 to 40 wt% based on 100% by mass of the composite material.
17. The nano-silica-based composite material according to claim 1, wherein the particle size of the inner core nano-silica particles is 1 to 50 nm.
18. The nano silicon dioxide-silicon based composite material as claimed in claim 1, wherein the thickness of the nano silicon layer of the shell is 5 to 40 nm.
19. The nano silica-silicon based composite material according to claim 1, wherein the nano silica-silicon particles have an oxygen content of 8 to 40 wt%.
20. The nano silica-based composite material according to claim 1, wherein the nano silica-silica particles have a specific surface area of 20 to 500m2/g。
21. The nano silica-based composite material according to claim 20, wherein the nano silica-silica particles have a specific surface area of 50 to 400m2/g。
22. Method for the preparation of nanosilica-silicon based composite material according to any of claims 1 to 21, comprising the steps of:
(1) mixing nano silicon oxide, a reducing agent and an additive according to the proportion of (0.5-0.8) to (8-12) of 1, carrying out homogeneous phase compounding, then carrying out heat treatment, and carrying out water washing and acid treatment on a heat treatment product to obtain nano silicon dioxide-silicon particles with a core-shell structure;
(2) carrying out homogeneous in-situ carbon coating on the nano silicon dioxide-silicon particles in the step (1) to obtain composite particles consisting of the nano silicon dioxide-silicon particles and a conductive carbon layer, wherein the conductive carbon layer is coated on the surfaces of the nano silicon dioxide-silicon particles;
(3) uniformly compounding the composite particles obtained in the step (2) with a carbon source, performing fusion treatment, and performing heat treatment to obtain a nano silicon dioxide-silicon based composite material;
wherein, the reducing agent in the step (1) comprises any one or the combination of at least two of potassium, calcium, sodium, magnesium, aluminum, zinc, iron, copper or nickel; the additive in the step (1) comprises any one or the combination of at least two of potassium chloride, potassium carbonate, potassium nitrate, potassium sulfate, sodium chloride, sodium carbonate, sodium nitrate or sodium sulfate; the temperature of the heat treatment in the step (1) is 600-950 ℃;
the homogeneous phase compounding method in the step (3) is a solid phase coating method, and the particle size of the carbon source in the step (3) is 2-5 mu m.
23. The method for preparing nano silica-silicon based composite material according to claim 22, further comprising the steps of pulverizing, sieving and demagnetizing the heat-treated product after the heat treatment of step (3) is completed.
24. The method for preparing nano silica-based composite material according to claim 22, wherein the chemical composition of the nano silica-silica of step (1) is SiOxWherein X is more than or equal to 1 and less than or equal to 2.
25. The method for preparing nano silicon dioxide-silicon based composite material according to claim 22, wherein the nano silicon oxide in the step (1) has a median particle size of 1-160 nm.
26. The method for preparing nano silica-silicon based composite material according to claim 22, wherein the median particle diameter of the reducing agent in the step (1) is 20 to 50 μm.
27. The method for preparing nano silica-based composite material according to claim 22, wherein the additive in the step (1) is screened by a screen of 100-200 meshes before being used.
28. The method for preparing nano silica-silicon based composite material according to claim 22, wherein the homogeneous phase in the step (1) is: and (3) uniformly mixing the nano silicon oxide, the additive and the reducing agent to obtain a homogeneous mixture.
29. The method for preparing nano silica-silicon based composite material according to claim 28, wherein the method for homogeneous mixing comprises a dry mixing method and a wet mixing method.
30. The method for preparing nano silica-based composite material according to claim 29, wherein the method for homogeneous mixing is a dry mixing method.
31. The method for preparing a nano silica-silicon based composite material according to claim 29, wherein the dry mixing method is a dry ball milling method or a method of mixing by placing in a VC mixer.
32. The method for preparing a nano silica-silicon based composite material according to claim 31, wherein the ball mill used in the dry ball milling method is any one of a planetary ball mill, a high speed stirring mill, a tube mill, a cone mill, a rod mill and a sand mill.
33. The method for preparing nano silica-silicon based composite material according to claim 31, wherein the method for mixing in a VC mixer is as follows: and (2) placing the nano silicon oxide, the reducing agent and the additive in the step (1) into a VC mixer, and mixing to obtain a homogeneous mixture.
34. The method for preparing nano silica-silicon based composite material according to claim 22, wherein the heat treatment of step (1) is: the homogeneous mixture is placed in a closed container and heat treated under a non-oxidizing atmosphere.
35. The method for preparing nano silica-silicon based composite material according to claim 34, wherein the non-oxidizing atmosphere during the heat treatment of step (1) is any one or a combination of at least two of nitrogen atmosphere, hydrogen atmosphere, helium atmosphere, argon atmosphere or neon atmosphere.
36. The method for preparing nano silica-silicon based composite material according to claim 22, wherein the time of the heat treatment in the step (1) is 0.5-1 h.
37. The method for preparing nano silica-silicon based composite material according to claim 22, wherein the acid treatment of the step (1) is: and (4) placing the heat treatment product in a container, and adding acid for treatment.
38. The method for preparing nano silica-silicon based composite material according to claim 22, wherein the acid treatment in the step (1) is soaking, or soaking with stirring.
39. The method for preparing nano silica-silicon based composite material according to claim 22, wherein in the acid treatment process of step (1), the treatment time is 1-8 h.
40. The method for preparing the nano silicon dioxide-silicon based composite material according to claim 39, wherein in the acid treatment process in the step (1), the treatment time is 1-4 h.
41. The method of claim 22, wherein in the acid treatment of step (1), the acid is selected from one or a combination of at least two of hydrochloric acid, nitric acid, nitrous acid, sulfuric acid, sulfurous acid, carbonic acid, boric acid, phosphoric acid, hydrocyanic acid, perchloric acid, acetic acid, benzoic acid, and selenic acid.
42. The method for preparing nano silica-based composite material according to claim 22, wherein in the acid treatment process of step (1), the concentration of the acid is 0.1-10 mol/L.
43. The method for preparing nano silica-silicon based composite material according to claim 22, further comprising the steps of centrifuging, suction filtering and drying after the acid treatment in step (1) is completed.
44. The method for preparing nano silica-silicon based composite material according to claim 22, wherein the homogeneous in-situ carbon coating in step (2) is performed by any one of a vapor phase coating method, a liquid phase coating method or a solid phase coating method.
45. The method for preparing nano silica-silicon based composite material according to claim 44, wherein the homogeneous in-situ carbon coating in step (2) is a vapor phase coating method.
46. The method for preparing nano silica-silicon based composite material according to claim 44, wherein the homogeneous in-situ carbon coating is performed by a vapor phase coating method, wherein the vapor phase coating method comprises the following steps: and introducing a gas-phase carbon source into the reaction furnace filled with the nano silicon dioxide-silicon particles, and carrying out in-situ deposition coating under the condition of rotation of the reaction furnace to obtain composite particles consisting of the nano silicon dioxide-silicon particles and a conductive carbon layer, wherein the conductive carbon layer is coated on the surfaces of the nano silicon dioxide-silicon particles.
47. The method for preparing nano silica-silicon based composite material according to claim 46, wherein in the vapor phase coating method, the vapor phase carbon source is any one or a combination of at least two of methane, ethane, propane, ethylene, acetylene, propylene, gaseous benzene, gaseous toluene, gaseous xylene, gaseous ethanol, or gaseous acetone.
48. The method of claim 47, wherein the gas phase coating method comprises a combination of methane, acetylene and gaseous toluene as the gas phase carbon source.
49. The method for preparing nano silica-silicon based composite material according to claim 46, wherein in the vapor phase coating method, the rotation speed of the reaction furnace is 0.2-8 rpm.
50. The method for preparing the nano silica-silicon based composite material according to claim 46, wherein in the vapor phase coating method, the introduction flow rate of the vapor phase carbon source is 0.1-1.2L/min.
51. The method for preparing nano silica-silicon based composite material according to claim 46, wherein the temperature of the in-situ deposition coating in the vapor phase coating method is 600-1000 ℃.
52. The method for preparing the nano silicon dioxide-silicon based composite material according to claim 51, wherein in the vapor phase coating method, the temperature of the in-situ deposition coating is 800-1000 ℃.
53. The method for preparing nano silica-silicon based composite material according to claim 46, wherein in the vapor phase coating method, the in-situ deposition coating time is 3-6 h.
54. The method for preparing a nano silica-silicon based composite material according to claim 22, wherein the fusing treatment of the step (3) comprises: and (3) uniformly mixing the composite particles obtained in the step (2) with a carbon source, and adding the mixture into a fusion machine for fusion.
55. The method for preparing nano silica-silicon based composite material according to claim 54, wherein the rotation speed of the fusion machine during the fusion treatment is 600-3000 rpm.
56. The method for preparing nano silicon dioxide-silicon based composite material according to claim 55, wherein the rotation speed of the fusion machine is 600-2000 rpm during the fusion treatment.
57. The method for preparing nano silica-silicon based composite material according to claim 54, wherein the cutter gap of the fusion machine is 0.01-1 cm during the fusion process.
58. The method for preparing nano silica-based composite material according to claim 57, wherein the tool gap of the fusion machine is 0.1-0.3 cm during the fusion process.
59. The method of claim 54, wherein the fusing time is at least 0.25h during the fusing process.
60. The method for preparing the nano silica-silicon based composite material according to claim 59, wherein the fusing time is 0.25-8 h during the fusing treatment.
61. The method for preparing the nano silica-silicon based composite material according to claim 60, wherein the fusing time is 0.5-4 h during the fusing treatment.
62. The method for preparing nano silica-silicon based composite material according to claim 22, wherein the carbon source in step (3) is any one or a combination of at least two of coal pitch, petroleum pitch, mesophase pitch, coal tar, petroleum industry heavy oil, heavy aromatic hydrocarbon, epoxy resin, phenolic resin, furfural resin, urea resin, polyvinyl alcohol, polyvinyl chloride, polyethylene glycol, polyethylene oxide, polyvinylidene fluoride, acrylic resin or polyacrylonitrile.
63. The method for preparing nano silica-silicon based composite material according to claim 22, wherein the heat treatment in step (3) is conducted with a shielding gas, and the shielding gas is any one or a combination of at least two of nitrogen, helium, neon, argon or krypton.
64. The method for preparing nano silica-silicon based composite material according to claim 22, wherein the temperature of the heat treatment in the step (3) is 700-1000 ℃.
65. The method for preparing nano silica-silicon based composite material according to claim 22, wherein the time of the heat treatment in the step (3) is 2-6 h.
66. An anode material, wherein the anode material is the nano silica-silicon based composite material according to any one of claims 1 to 21.
67. A lithium ion battery, wherein the lithium ion battery comprises the nanosilica-silicon-based composite material according to any one of claims 1 to 21 as a negative electrode material of the lithium ion battery.
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CN111755684B (en) * 2020-07-06 2022-05-24 马鞍山科达普锐能源科技有限公司 Silicon-carbon negative electrode material for lithium ion battery and preparation method thereof
CN112563502A (en) * 2020-12-07 2021-03-26 广东凯金新能源科技股份有限公司 High-first-efficiency multi-element coated silicon-based composite material, and preparation method and application thereof
CN113097487B (en) * 2021-04-01 2022-11-22 广东凯金新能源科技股份有限公司 Silicon-carbon composite material with highly compact structure, and preparation method and application thereof
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