WO2022062462A1 - 一种纳米硅复合材料及其制备方法、电极材料、电池 - Google Patents

一种纳米硅复合材料及其制备方法、电极材料、电池 Download PDF

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WO2022062462A1
WO2022062462A1 PCT/CN2021/097038 CN2021097038W WO2022062462A1 WO 2022062462 A1 WO2022062462 A1 WO 2022062462A1 CN 2021097038 W CN2021097038 W CN 2021097038W WO 2022062462 A1 WO2022062462 A1 WO 2022062462A1
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nano
silicon
composite material
silicon composite
cladding layer
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PCT/CN2021/097038
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English (en)
French (fr)
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苏航
沙玉静
夏圣安
谢封超
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华为技术有限公司
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Priority to EP21870849.3A priority Critical patent/EP4207388A1/en
Publication of WO2022062462A1 publication Critical patent/WO2022062462A1/zh
Priority to US18/189,268 priority patent/US20230231115A1/en

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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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • 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
    • H01M4/04—Processes of manufacture in general
    • H01M4/0471—Processes of manufacture in general involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • 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
    • 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
    • H01M4/587—Carbonaceous material, e.g. graphite-intercalation compounds or CFx for inserting or intercalating light metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • 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
    • H01M2004/021—Physical characteristics, e.g. porosity, surface area
    • 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 application relates to the technical field of battery anode materials, and in particular, to a nano-silicon composite material and a preparation method thereof, an electrode material, and a battery.
  • the positive and negative materials of lithium-ion batteries are the main part of the energy storage function and the most direct embodiment of the energy density, cycle performance and safety performance of the battery. Since the positive electrode material lithium cobaltate (LCO) has reached its highest limit (4.4V, compaction density 4.2g/cm 3 ), the capacity of the negative electrode is very important for the improvement of the energy density of the whole cell. important.
  • LCO lithium cobaltate
  • the actual gram capacity of the graphite anode for traditional lithium-ion batteries is 360mAh/g, which is close to its theoretical value (372mAh/g), so it is necessary to develop new high-capacity anode materials.
  • Silicon-based materials are currently one of the most studied anode materials that can replace graphite. According to different reaction depths, silicon and lithium can generate different products, such as Li 7 Si 3 , Li 13 Si 4 , Li 22 Si 5 , Li 12 Si 17 , and the like.
  • the Li 4.4 Si alloy formed by intercalating lithium into silicon has a theoretical gram capacity of 4200mAh/g, which is the anode material with the highest theoretical gram capacity.
  • the silicon-based material will undergo severe volume expansion (0-300%) and shrinkage during the lithium-deintercalation reaction, which will lead to structural damage and pulverization of the electrode material, and the silicon surface will continuously interact with the electrolyte.
  • a new SEI film solid electrolyte interface, solid electrolyte interface film
  • the embodiments of the present application provide a nano-silicon composite material and a preparation method thereof, an electrode material, and a battery, which are used to solve the problems of large volume expansion of the negative electrode material of the battery and serious side reactions with the electrolyte.
  • a nano-silicon composite material in a first aspect, includes an inner core, a first cladding layer and a second cladding layer.
  • the inner core includes nanosilicon crystals.
  • the first cladding layer coats the surface of the inner core; the first cladding layer has a porous structure, and the material of the first cladding layer includes metasilicate and deoxidized silicon oxide; the second cladding layer coats the first cladding layer
  • the surface of the cladding layer; the material of the second cladding layer includes silica in a deoxidized state.
  • the chemical formula of deoxidized silicon oxide is SiO 1-m , 0 ⁇ m ⁇ 1; the chemical formula of deoxidized silicon dioxide is SiO n , 1 ⁇ n ⁇ 2.
  • the ratio of silicon atoms to oxygen atoms in the molecular structure of silicon oxide (SiO, also known as silicon monoxide or silicon (II) oxide) is 1:1, and the deoxidized silicon oxide has less oxygen atoms, so The ratio of silicon atoms to oxygen atoms in the molecular structure of deoxidized silicon oxide is 1:m, 0 ⁇ m ⁇ 1.
  • the ratio of silicon atoms to oxygen atoms in the molecular structure of silicon dioxide (SiO 2 ) is 1:2.
  • the molecular structure of deoxidized silica has silicon atoms and oxygen atoms.
  • the ratio of oxygen atoms is 1:n, 1 ⁇ n ⁇ 2. Since the core of the nano-silicon composite material includes nano-silicon crystals, and the size of the nano-silicon crystals is small, the volume expansion can be effectively reduced during the charging and discharging process of the battery, that is, the de-intercalation reaction of metal ions (such as lithium ions). , thereby reducing the mechanical fatigue of the material and prolonging the cycle life.
  • the first cladding layer has a porous structure
  • the first cladding layer can play a buffering role when the inner core expands and contracts, relieve the internal stress of the inner core, maintain the stability of the structure and the integrity of the second cladding layer sex.
  • the second cladding layer can act as a barrier to the electrolyte It can reduce or eliminate the side reaction between the electrolyte and silicon.
  • the particle size of the nano-silicon composite material is 10 nm to 150 nm.
  • the particle size of the inner core ranges from 10 nm to 130 nm.
  • the thickness of the first cladding layer is 0.1 nm ⁇ 10 nm.
  • the thickness of the second cladding layer is 0.1 nm ⁇ 10 nm.
  • the mass of the nano-silicon crystals accounts for 70%-85% of the mass of the nano-silicon composite material.
  • the ratio a of the mass of the metasilicate to the mass of the nano-silicon composite material is 0 ⁇ a ⁇ 7.5%.
  • the ratio b of the mass of silicon oxide to the mass of the nano-silicon composite material is 0 ⁇ b ⁇ 7.5%.
  • the ratio c of the mass of silicon dioxide to the mass of the nano-silicon composite material is 0 ⁇ c ⁇ 15%.
  • the metasilicate comprises lithium metasilicate.
  • the metasilicate includes lithium metasilicate, the above-mentioned nano-silicon composite material can be applied to a lithium ion battery.
  • an electrode material in a second aspect, includes the aforementioned mixture of nano-silicon composite material, graphite and carbon.
  • the electrode material has the same technical effect as the foregoing embodiments, and details are not repeated here.
  • the mass of the nano-silicon composite material accounts for 3% to 60% of the mass of the electrode material.
  • a battery including a cell, a corresponding communication accessory and a circuit, the cell includes a positive electrode, a negative electrode, an electrolyte, and a separator, and the negative electrode includes the aforementioned electrode material.
  • the battery has the same technical effect as the foregoing embodiment, which will not be repeated here.
  • a method for preparing a nano-silicon composite material includes the following steps: firstly, treating the silicon oxide and a metal source to obtain a mixture of nano-silicon, metasilicate and deoxidized silicon oxide; then, treating the nano-silicon, meta-silicon The mixture of acid salt and deoxidized silicon oxide is pickled and ground to obtain a nano-silicon composite material; the nano-silicon composite material includes an inner core, a first cladding layer covering the surface of the inner core, and a surface covering the first cladding layer.
  • the inner core includes nano-silicon crystals
  • the first cladding layer is a porous structure, and the material of the first cladding layer includes metasilicate and deoxidized silicon oxide; the material of the second cladding layer includes Deoxidized silica. Since the inner core of the prepared nano-silicon composite material includes nano-silicon crystals, and the size of nano-silicon crystals is small, it can effectively reduce the size of the nano-silicon crystal during the charging and discharging process of the battery, that is, the de-intercalation reaction of metal ions (such as lithium ions). Reduced volumetric expansion, thereby reducing mechanical fatigue of the material and extending cycle life.
  • metal ions such as lithium ions
  • the first cladding layer has a porous structure
  • the first cladding layer can play a buffering role when the inner core expands and contracts, relieve the internal stress of the inner core, maintain the stability of the structure and the integrity of the second cladding layer sex.
  • the second cladding layer can act as a barrier to the electrolyte It can reduce or eliminate the side reaction between the electrolyte and silicon.
  • the processing of the silicon oxide and the metal source includes: mixing the silicon oxide and the solid metal source uniformly according to a preset ratio or passing the metal source steam into the oxidizer according to a preset ratio It is calcined in a high temperature furnace in an inert atmosphere or a reducing atmosphere.
  • This method can be used to treat the silicon oxide and the metal source when the metal source is in a solid or gaseous state.
  • the calcination temperature is 300°C to 900°C.
  • the metal source is an organic solvent containing metal ions
  • the processing of the silicon oxide and the metal source includes: mixing the silicon oxide and the organic solvent containing metal ions according to a preset ratio, and The reaction is carried out under an inert atmosphere or a reducing atmosphere; the reaction product is washed and dried.
  • This method can be used to treat the silicon oxide and the metal source when the metal source is in a liquid state.
  • reaction temperature is less than 200°C.
  • the preset ratio is that the molar ratio of the metal element in the metal source to the silicon element in the silicon oxide is 0.1-1.0.
  • the metal source includes a lithium source; the lithium source includes metallic lithium or a lithium salt. Since the lithium source includes metal lithium or lithium salt, the prepared nano-silicon composite material can be used in lithium ion batteries.
  • the metal ion-containing organic solvent includes a lithium ion-containing organic solvent. Since the organic solvent containing metal ions includes the organic solvent containing lithium ions, the prepared nano-silicon composite material can be applied to lithium ion batteries.
  • FIG. 1 is a schematic structural diagram of a silicon-based material deintercalation reaction of lithium provided by the prior art
  • FIG. 2 is a schematic structural diagram of a battery according to an embodiment of the present application.
  • FIG. 3 is a schematic structural diagram of a nano-silicon charge-discharge process provided by the related art
  • FIG. 4 is a schematic diagram of a nano-silicon surface provided by the related art with a coating layer and reacting with an electrolyte;
  • FIG. 5 is a schematic structural diagram of a nano-silicon composite material provided by an embodiment of the present application.
  • FIG. 6 is a schematic flowchart of a method for preparing a nano-silicon composite material provided in an embodiment of the present application
  • FIG. 7 is a schematic structural diagram in the process of a preparation method of a nano-silicon composite material provided by an embodiment of the present application.
  • FIG. 8 is a schematic diagram showing the comparison of cell cycle performance between a lithium ion battery prepared with nano-silicon composite material and a lithium ion battery prepared with nano-silicon.
  • the embodiments of the present application provide a battery.
  • the battery may be a lithium-ion battery, a sodium-ion battery, a magnesium-ion battery, or the like.
  • the specific form of the above-mentioned battery is not particularly limited in the embodiments of the present application. For the convenience of description, the following description is given by taking a lithium-ion battery as an example.
  • the main structure of the above-mentioned battery 01 includes a battery cell, a corresponding communication accessory (such as a load) and a circuit.
  • the battery cell includes a positive electrode 1 , a negative electrode 2 , an electrolyte 3 and a separator 4 .
  • the positive electrode 1 includes a positive electrode current collector (also referred to as a positive electrode plate) 11 and a positive electrode slurry coated on the surface of the positive electrode current collector 11 .
  • the positive electrode slurry includes a positive electrode material 12 , a conductive agent and a binder.
  • the positive electrode current collector 11 may be, for example, an aluminum foil.
  • the positive electrode material 12 may be, for example, lithium cobalt oxide.
  • the conductive agent in the positive electrode slurry can be, for example, conductive carbon black (super P, SP).
  • the binder in the positive electrode slurry can be, for example, polyvinylidene fluoride (PVDF).
  • the negative electrode 2 includes a negative electrode current collector (also referred to as a negative electrode plate) 21 and a negative electrode slurry coated on the surface of the negative electrode current collector 21 .
  • the negative electrode slurry includes the negative electrode material 22, a conductive agent, a binder, and the like.
  • the negative electrode current collector 21 may be, for example, a copper foil.
  • the conductive agent in the negative electrode slurry can be, for example, conductive carbon black.
  • the binder in the negative electrode slurry can be, for example, carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR).
  • the above-mentioned positive electrode material 12 and negative electrode material 22 can deintercalate lithium ions to achieve energy storage and release.
  • the electrolyte 3 is a carrier for the transport of lithium ions between the positive electrode 1 and the negative electrode 2 .
  • the non-conductive separator 4 is permeable to lithium ions, but separates the positive electrode 1 and the negative electrode 2 to prevent short circuits.
  • the working principle of the lithium ion battery is: during charging, Li + in the positive electrode material 12 and Li + in the electrolyte 3 aggregate to the negative electrode 2 to obtain electrons, which are reduced to Li and embedded in the negative electrode material 22 of the negative electrode 2 .
  • Li embedded in the negative electrode material 22 of the negative electrode 2 loses electrons and enters the electrolyte 3 , and Li + in the electrolyte 3 moves to the positive electrode 1 .
  • the positive electrode material 12 and the negative electrode material 22 are the main parts of the energy storage function, and the most direct embodiment of the energy density, cycle performance and safety performance of the battery cell.
  • silicon-based materials are often used as negative electrode materials for batteries due to their high gram capacity.
  • silicon-based materials will undergo severe volume expansion and contraction during the lithium-deintercalation reaction, resulting in structural damage and powdery discharge of electrode materials.
  • the silicon surface will continuously generate new SEI film with the electrolyte, resulting in the exhaustion of the electrolyte and the rapid decay of the battery capacity.
  • the volume expansion effect of silicon is usually improved by means of nanometerization.
  • nanometerization also brings problems such as high specific surface area, easy agglomeration and difficult dispersion, large contact area with the electrolyte, serious side reactions, rapid deactivation of silicon materials, and rapid electrolyte consumption.
  • the silicon surface will react with the electrolyte to form a side reaction product 5. After multiple charging and discharging, the silicon surface will be covered by the formed side reaction product 5, so that lithium ions cannot be embedded in the silicon material.
  • the silicon material is deactivated, and the reaction of silicon with the electrolyte will lead to the rapid consumption of the electrolyte.
  • the nano-silicon in FIG. 3 is crystalline silicon before the first charge and discharge, and amorphous silicon (amorphous Si, a-Si) will be formed after the first charge and discharge.
  • a coating layer (such as a carbon (C) coating layer) is arranged on the surface of the nano-silicon (Si) negative electrode material.
  • C carbon
  • the carbon coating of its pores cannot really alleviate the side reaction between silicon and the electrolyte, and the latest research results show that due to its catalytic effect, it can accelerate the reaction between silicon and lithium hexafluorophosphate (LiPF 6 ) in the electrolyte, which will lead to the loss of active silicon and capacity decay.
  • the embodiments of the present application provide an electrode material, which can be used as the negative electrode material 22 in the negative electrode 2 of the above-mentioned battery 01 .
  • the electrode material includes a nano-silicon composite material, a mixture of graphite and carbon, and the electrode material can also be referred to as a nano-silicon/graphite/carbon composite material.
  • the ratio of the mass of the nano-silicon composite material to the mass of the electrode material in the above-mentioned electrode material is 3% to 60%.
  • the ratio of the mass of the nano-silicon composite material to the mass of the electrode material may be 3%, 20%, 40% or 60%.
  • the particle size of the above-mentioned nano-silicon composite material is 10 nm ⁇ 150 nm.
  • the particle size of the nano-silicon composite material may be 10 nm, 30 nm, 60 nm, 100 nm or 150 nm.
  • the structure of the nano-silicon composite material is introduced in detail below.
  • the above-mentioned nano-silicon composite material 02 includes an inner core 10 , a first cladding layer 20 and a second cladding layer 30 .
  • the inner core 10 includes a nano-silicon crystal (Si cluster), and the nano-silicon crystal includes a plurality of nano-silicon atoms.
  • the first cladding layer 20 coats the surface of the inner core 10, the first cladding layer 20 has a porous structure, and the material of the first cladding layer 20 includes metasilicate and deoxidized silicon oxide (SiO 1-m , 0 ⁇ m ⁇ 1).
  • the second cladding layer 30 coats the surface of the first cladding layer 20 ; the material of the second cladding layer 30 includes silicon dioxide in a deoxidized state (SiO n , 1 ⁇ n ⁇ 2).
  • the ratio of silicon atoms to oxygen atoms in the molecular structure of silicon oxide is 1:1. Part of the oxygen atoms, so the ratio of silicon atoms and oxygen atoms in the molecular structure of deoxidized silicon oxide is 1:m, 0 ⁇ m ⁇ 1.
  • the ratio of silicon atoms to oxygen atoms in the molecular structure of silicon dioxide (SiO 2 ) is 1:2. Because of the lack of oxygen atoms in deoxidized silica, the molecular structure of deoxidized silica has silicon atoms and oxygen atoms. The ratio of oxygen atoms is 1:n, 1 ⁇ n ⁇ 2.
  • the particle size of the inner core 10 is 10 nm ⁇ 130 nm.
  • the particle size of the inner core 10 may be 10 nm, 20 nm, 50 nm, 100 nm or 130 nm.
  • the shape of the inner core 10 may be spherical or quasi-spherical, for example.
  • the thickness of the first cladding layer 20 can be adjusted correspondingly according to the particle size of the inner core 10 .
  • the thickness of the first cladding layer 20 is 0.1 nm ⁇ 10 nm.
  • the thickness of the first cladding layer 20 may be 0.1 nm, 1 nm, 5 nm or 10 nm.
  • the thickness of the second cladding layer 30 can also be adjusted according to the particle size of the inner core 10 .
  • the thickness of the second cladding layer 30 it is necessary to ensure that the second cladding layer 30 can block the reaction between the electrolyte and silicon, and also ensure that the de-intercalation reaction of lithium ions in the core 10 during charging and discharging is not affected.
  • the thickness of the second cladding layer 20 is 0.1 nm ⁇ 10 nm.
  • the thickness of the second cladding layer 20 may be 0.1 nm, 1 nm, 5 nm or 10 nm.
  • the shape of the first cladding layer 20 and the shape of the second cladding layer 30 coats the surface of the first cladding layer 20, the shape of the first cladding layer 20 and the shape of the second cladding layer 30 The shape is related to the shape of the kernel 10 .
  • the shape of the inner core 10 is spherical, and the cross-sectional shape of the first cladding layer 20 and the sectional shape of the second cladding layer 30 are circular.
  • the mass of the nano-silicon crystals accounts for 70% to 85% of the mass of the nano-silicon composite material. That is, the ratio of the number of moles of nano-silicon crystals to the sum of the number of moles of metasilicate, deoxidized silicon oxide, and deoxidized silicon dioxide is 7:3 to 4:1.
  • the ratio of the mass of the nano-silicon crystal to the mass of the nano-silicon composite material may be 70%, 80% or 85%.
  • the ratio a of the mass of the metasilicate in the first cladding layer 20 to the mass of the nano-silicon composite material is 0 ⁇ a ⁇ 7.5%.
  • the proportion of the mass of the metasilicate to the mass of the nano-silicon composite material may be 2%, 5% or 7.5%.
  • the metasilicate includes lithium metasilicate (Li 2x Si y O x+2y , where x, y are positive integers).
  • the batteries provided in the embodiments of the present application are lithium ion batteries. Lithium-ion batteries have the advantages of high energy density, fast charging and discharging speed, long service life and small self-discharge.
  • the above-mentioned lithium metasilicate may be, for example, at least one of Li 2 SiO 3 , Li 2 Si 2 O 5 or Li 4 SiO 4 .
  • the nano-silicon composite material it needs to be mixed with graphite and carbon to form an electrode material, and the electrode material is mixed with a conductive agent, a binder, etc. to form a slurry to be coated on the negative electrode current collector 21, while Li 2 SiO 3 It is poorly soluble in water and is not affected by the aqueous pulping process in the process of making the slurry, so in some examples, the lithium metasilicate is Li 2 SiO 3 .
  • the ratio b of the mass of silicon oxide in the first cladding layer 20 to the mass of the nano-silicon composite material is 0 ⁇ b ⁇ 7.5%.
  • the proportion of the mass of silicon oxide to the mass of the nano-silicon composite material may be 2%, 5% or 7.5%.
  • the ratio of the mass of metasilicate to the mass of the nano-silicon composite material and the ratio of the mass of silicon oxide to the mass of the nano-silicon composite material may or may not be the same.
  • the ratio c of the mass of silicon dioxide to the mass of the nano-silicon composite material is 0 ⁇ c ⁇ 15%.
  • the proportion of the mass of silicon dioxide to the mass of the nano-silicon composite material may be 1%, 5%, 10% or 15%.
  • the embodiment of the present application provides a nano-silicon composite material 02 , and the nano-silicon composite material 02 includes an inner core 10 , a first cladding layer 20 and a second cladding layer 30 .
  • the inner core 10 includes nano-silicon crystals
  • the first cladding layer 20 coats the surface of the inner core 10
  • the first cladding layer 20 has a porous structure
  • the material of the first cladding layer 20 includes metasilicate and deoxidized silicon oxide
  • the second cladding layer 30 coats the surface of the first cladding layer 20 ;
  • the material of the second cladding layer 30 includes silicon dioxide in a deoxidized state.
  • the core 10 of the nano-silicon composite material 02 includes nano-silicon crystals, and the size of the nano-silicon crystals is relatively small, during the charging and discharging process of the battery, that is, the de-intercalation reaction of metal ions (such as lithium ions), it can effectively reduce The volume expands, thereby reducing the mechanical fatigue of the material and extending the cycle life.
  • the first cladding layer 20 has a porous structure, the first cladding layer 20 can play a buffering role when the inner core 10 expands and contracts, relieves the internal stress of the inner core 10, maintains the stability of the structure and the second cladding Integrity of the cladding 30.
  • the second cladding layer 30 can To block the role of the electrolyte, reduce or eliminate side reactions between the electrolyte and silicon.
  • the embodiments of the present application further provide a method for preparing the nano-silicon composite material 02, which can be used for preparing the above-mentioned nano-silicon composite material 02.
  • the preparation method of the nano-silicon composite material 02 includes:
  • the silicon oxide and the metal source may be treated according to the form of the metal source.
  • the following exemplarily provides three ways to treat the silicon oxide and the metal source.
  • the pair of silicon oxide and the metal source can be treated in a manner.
  • the first method is as follows: the silicon oxide and the solid metal source are uniformly mixed according to a preset ratio, and calcined in a high-temperature furnace in an inert atmosphere or a reducing atmosphere.
  • the silicon oxide and the solid metal source can be uniformly mixed according to a preset ratio and then transferred to a saggar, and then the saggar can be transferred to a high temperature furnace with an inert atmosphere or a reducing atmosphere for calcination.
  • the silicon oxide and the metal source can be treated in two ways. Specifically, the second method is as follows: the metal source steam is introduced into the silicon oxide according to a preset ratio, and the calcination is carried out in a high-temperature furnace in an inert atmosphere or a reducing atmosphere.
  • the calcination temperature is 300°C to 900°C.
  • the firing temperature may be, for example, 300°C, 500°C, 700°C or 900°C.
  • the high-temperature furnace used in the first and second methods described above may be, for example, a vacuum furnace, a box furnace, a rotary furnace, or a tube furnace.
  • the metal source is a metal element or a salt containing metal ions.
  • the metal source includes lithium source; the lithium source includes metal lithium or lithium salt.
  • the lithium salt includes one or more of LiH, LiAlH 4 , Li 2 CO 3 , LiNO 3 , LiAc, and LiOH.
  • the metal source When the metal source is in liquid state, the metal source is an organic solvent containing metal ions, and the silicon oxide and the metal source can be treated according to the third method.
  • the third method is: mixing silicon oxide and an organic solvent containing metal ions according to a preset ratio, and reacting in an inert atmosphere or a reducing atmosphere; after that, cleaning and drying the reaction product.
  • the reaction temperature is less than 200°C.
  • the reaction temperature may be 20°C, 50°C, 100°C, or 150°C.
  • the above-mentioned organic solvent may be, for example, at least one of alcohol, ether, or ketone.
  • reaction product can be washed with deionized water, and the purpose of washing is to remove the organic solvent.
  • the above-mentioned metal ion-containing organic solvent includes a lithium ion-containing organic solvent.
  • the inert atmosphere in the above-mentioned mode one, mode two and mode three can be, for example, argon (Ar gas), helium (He gas), neon (Ne gas), nitrogen (N gas) or xenon gas (Xe gas). at least one.
  • the reducing atmosphere may be, for example, at least one of hydrogen (H2), ethylene (C2H4) or methane (CH4).
  • the preset ratios in the first, second, and third modes are that the molar ratio of the metal element in the metal source to the silicon element in the silicon oxide is 0.1-1.0, that is, 0.1 ⁇ nX/nSi ⁇ 1.0, X represents a metal element.
  • the molar ratio of the lithium element in the lithium source to the silicon element in the silicon oxide is 0.1 to 1.0, that is, 0.1 ⁇ nLi/nSi ⁇ 1.0.
  • the products formed by the reaction can be controlled by controlling the reaction conditions (for example, the ratio of the metal element in the metal source and the silicon element in the silicon oxide, the reaction temperature, etc.).
  • the structure of the silicon oxide can be adjusted to convert the silicon oxide into a silicon-oxygen compound (eg, lithiated silicon-oxygen compound Li 2 SiO 3 ) of a specific composition containing metal ions.
  • the type of lithium metasilicate (or metalithium silicate) can be adjusted by controlling the ratio of lithium element in the lithium source and the silicon element in silicon oxide, and the reaction temperature. Among them, Li-rich and low-temperature reactions are favorable for the formation of Li 2 SiO 3 .
  • the nano-silicon composite material 02 includes an inner core 10 , a first cladding layer 20 covering the surface of the inner core 10 , and a second cladding layer 30 covering the surface of the first cladding layer 20 .
  • the inner core 10 includes nano-silicon crystals; the first cladding layer 20 is a porous structure, and the material of the first cladding layer 20 includes metasilicate and deoxidized silicon oxide; the material of the second cladding layer 30 includes deoxidized state Silica.
  • the pickling solution selected during pickling can be, for example, one or more of sulfuric acid, hydrochloric acid, nitric acid and hydrofluoric acid.
  • the purpose of pickling is to remove specific phases in the metasilicate to form pores.
  • the selected pickling solution should have strong corrosiveness and strong oxidizing property, and can react with the material in a directional manner.
  • the metasilicate obtained in step S100 includes Li 2 SiO 3 or Li 2 Si 2 O 5 and the like, and the Li 2 Si 2 O 5 can be removed directionally by pickling to form pores and make the remaining metasilicic acid
  • the salt is mainly Li 2 SiO 3 .
  • the acid-washed precursor when the acid-washed precursor is ground, the acid-washed precursor can be sent into the grinding tank of the grinding machine, and an appropriate amount of grinding media, such as glass beads, can be filled in the grinding tank.
  • the grinding medium collides with the acid-washed precursor, so as to achieve the effect of dispersion and further reduce the particle size of the acid-washed precursor. Grinding can not only reduce the particle size of the acid-washed precursor, but also form deoxidized silica on the surface of the nano-silicon composite material, that is, to form the second coating layer 30 .
  • a separation method can be used to separate and discharge the reaction product and the grinding media.
  • the separation method may be, for example, at least one of a precipitation separation method, a centrifugal separation method, or a solvent separation method.
  • the thickness of the first cladding layer 20, and the thickness of the second cladding layer 30 in the nano-silicon composite material 02 reference may be made to the above-mentioned embodiments, which will not be repeated here.
  • the mass ratio of nano-silicon crystals, metasilicate, silicon oxide and silicon dioxide reference may be made to the above-mentioned embodiments, which will not be repeated here.
  • the embodiment of the present application provides a method for preparing a nano-silicon composite material 02 , since the prepared nano-silicon composite material 02 includes an inner core 10 , a first cladding layer 20 and a second cladding layer 30 .
  • the inner core 10 includes nano-silicon crystals
  • the first cladding layer 20 coats the surface of the inner core 10
  • the first cladding layer 20 has a porous structure
  • the material of the first cladding layer 20 includes metasilicate and deoxidized silicon oxide
  • the second cladding layer 30 coats the surface of the first cladding layer 20 ;
  • the material of the second cladding layer 30 includes silicon dioxide in a deoxidized state.
  • the core 10 of the nano-silicon composite material 02 includes nano-silicon crystals, and the size of the nano-silicon crystals is relatively small, during the charging and discharging process of the battery, that is, the de-intercalation reaction of metal ions (such as lithium ions), it can effectively reduce Volume expansion, thereby reducing the mechanical fatigue of the material and extending the cycle life.
  • the first cladding layer 20 has a porous structure, the first cladding layer 20 can play a buffering role when the inner core 10 expands and contracts, relieves the internal stress of the inner core 10, maintains the stability of the structure and the second cladding Integrity of the cladding 30.
  • the second cladding layer 30 can To block the role of the electrolyte, reduce or eliminate side reactions between the electrolyte and silicon.
  • An embodiment of the present application further provides a method for preparing an electrode material, which includes: mixing the nano-silicon composite material 02 prepared in steps S100 and S101 with graphite and carbon to obtain an electrode material.
  • the proportion of the mass of the nano-silicon composite material 02 to the sum of the mass of the nano-silicon composite material 02, graphite and carbon is 3% to 60%.
  • the embodiments of the present application also provide a method for preparing electrode slurry, which includes: dispersing the electrode material, conductive agent and binder prepared above in deionized water, and stirring evenly to obtain electrode slurry.
  • the conductive agent may be SP, for example.
  • the binders can be, for example, SBR and CMC.
  • the embodiments of the present application also provide a method for preparing a negative electrode, which includes: coating the electrode slurry prepared above on the surface of a negative electrode current collector, and drying to obtain a negative electrode (also referred to as a negative electrode sheet).
  • the negative electrode current collector may be, for example, copper foil.
  • pre-lithiated silicon oxide can be obtained, that is, nano-silicon, lithium metasilicate (Li 2 SiO 3 ) and deoxidized silicon oxide (SiO 1-m , 0 ⁇ m ⁇ 1) can be obtained. mixture.
  • Step S200 may also be referred to as a pre-lithiation process.
  • the inner core 10 of the nano-silicon composite material 02 includes nano-silicon crystals
  • the first cladding layer 20 coats the surface of the inner core 10
  • the material of the first cladding layer 20 includes lithium metasilicate (Li 2 SiO 3 ) and deoxidized oxide Sub-silicon (SiO 1-m , 0 ⁇ m ⁇ 1)
  • the second cladding layer 30 coats the surface of the first cladding layer 20 ;
  • the material of the second cladding layer 30 includes deoxidized silicon dioxide (SiO n , 1 ⁇ n ⁇ 2).
  • Step S201 may also be referred to as a pickling and grinding process.
  • the performance of the nano-silicon composite material 02 prepared above is tested, and the gram capacity of the nano-silicon composite material 02 is 2000-3500 mAh/g, and the first Coulomb efficiency is 80%-90%. It can be seen that the nano-silicon composite material 02 prepared in the examples of the present application has a higher gram capacity and a higher first Coulomb efficiency.
  • nano-silicon composite material 02 prepared by using S200 and S201 is compared with the existing nano-silicon (nano-silicon refers to crystalline silicon particles with a diameter of nanometers, such as crystalline silicon particles with a diameter less than 5nm), and the comparison results are shown in the table. 1 shown.
  • the nano-silicon composite material 02 prepared in the examples of the present application has advantages in gram capacity and efficiency.
  • S300, the nano-silicon composite material 02, graphite, and carbon prepared by using S200 and S201 are mixed according to a mass ratio of 40%: 50%: 10% to obtain an electrode material, which can be used as a negative electrode material.
  • the electrode material prepared by using S300, the conductive agent SP, the binder SBR, and the binder CMC are dispersed in deionized water in a mass ratio of 95:0.3:3.2:1.5, and stirred evenly to obtain electrode slurry.
  • the electrode slurry was coated on the surface of the copper foil, and dried at 85° C. to obtain a negative electrode (ie, a negative electrode sheet) 2 .
  • the prepared negative electrode 2 is matched with the lithium cobalt oxide positive electrode (that is, the positive electrode sheet), and the electrolyte is selected to be 1 mol/L LiPF 6 /EC (ethylene carbonate, ethylene carbonate), PC (polycarbonate, polycarbonate), DEC ( A mixture of diethyl carbonate, ethyl carbonate and EMC (ethyl methyl carbonate), the volume ratio of LiPF 6 /EC, PC, DEC, and EMC is 1:0.3:1:1, using a three-layer diaphragm , the material of the middle layer is PE (polyethylene, polyethylene), the material of the two side layers is PP (polypropylene, polypropylene), the thickness of the three-layer diaphragm is 10 ⁇ m, and the soft pack battery of about 3.7Ah is made.
  • LiPF 6 /EC ethylene carbonate, ethylene carbonate
  • PC polycarbonate, polycarbonate
  • DEC A mixture of diethyl carbonate, e
  • the prepared negative electrode 2 is matched with the lithium cobalt oxide positive electrode, and the electrolyte is selected to be a mixture of 1 mol/L LiPF 6 /EC, PC, DEC and EMC, and the volume ratio of LiPF 6 /EC, PC, DEC, and EMC is 1: 0.3:1:1, using three-layer diaphragm, the material of the middle layer is PE, the material of both sides is PP, the thickness of the three-layer diaphragm is 10 ⁇ m, and the soft pack battery of about 3.7Ah is made. After that, the cell cycle performance of the soft pack battery of about 3.7Ah made of the above nano-silicon composite material 02 and the pouch battery of about 3.7Ah made of nano-silicon were tested.
  • FIG. 8 shows a plurality of sampling points obtained by testing two lithium-ion soft-pack batteries prepared by using the above nano-silicon composite material 02 and a plurality of sampling points obtained by testing two lithium-ion soft-pack batteries prepared by using nano-silicon Sampling point.
  • the horizontal axis in FIG. 8 represents the number of cycles of charging and discharging, for example, a cycle number of 500 means that the battery is charged and discharged 500 times.
  • the vertical axis represents the capacity retention rate of the cell.
  • the cycle performance can be expressed by the number of charge-discharge cycles and the capacity retention rate of the cell. Under the same number of cycles, the higher the capacity retention rate of the cell, the better the cell cycle performance of the lithium-ion battery.
  • the lithium-ion battery prepared by using the above nano-silicon composite material 02 has excellent performance in the cycle performance of the cell.
  • the capacity retention rate of the cell is 80%.
  • the capacity retention rate of the cells has decayed to 80% when the number of cycles is 200 cycles.
  • the cell expansion rates of the lithium-ion battery prepared with the above nano-silicon composite material 02 and the lithium-ion battery prepared with nano-silicon are 6% and 13%, respectively.
  • the lithium ion battery prepared by using the above nano-silicon composite material 02 is beneficial to the improvement of the cycle performance of the battery cell and the reduction of the expansion rate.
  • the inner core 10 of the nano-silicon composite material 02 includes nano-silicon crystals, and the size of the nano-silicon crystals is small, so that the volume expansion can be reduced.
  • the first cladding layer 20 of the nano-silicon composite material 02 has a porous structure, which can play a buffer role when the inner core 10 expands and contracts, maintains the stability of the structure, reduces the volume expansion, and improves the cycle performance of the cell.
  • the second coating layer 30 of the nano-silicon composite material 02 can block the electrolyte, reduce or eliminate side reactions between the electrolyte and silicon, and can also improve the cycle performance of the cell.

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Abstract

本申请实施例提供一种纳米硅复合材料及其制备方法、电极材料、电池，涉及电池负极材料技术领域，用于解决电池负极材料体积膨胀大以及与电解液副反应严重的问题。该纳米硅复合材料包括内核、第一包覆层和第二包覆层。所述内核包括纳米硅晶。第一包覆层包覆所述内核的表面；所述第一包覆层为多孔结构，所述第一包覆层的材料包括偏硅酸盐和脱氧态的氧化亚硅；第二包覆层包覆所述第一包覆层的表面；所述第二包覆层的材料包括脱氧态的二氧化硅。

Description

一种纳米硅复合材料及其制备方法、电极材料、电池
本申请要求于2020年09月27日提交中国专利局、申请号为202011034975.8发明名称为“一种纳米硅复合材料及其制备方法、电极材料、电池”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及电池负极材料技术领域，尤其涉及一种纳米硅复合材料及其制备方法、电极材料、电池。
背景技术
以锂离子电池为例，锂离子电池的正负极材料是发挥储能功用的主体部分，是电芯的能量密度、循环性能及安全性能最直接的体现者。由于正极材料钴酸锂(lithium cobaltate，简称LCO)已达到其使用的最高极限(4.4V，压实密度4.2g/cm 3)，因而负极的容量发挥对于整个电芯的能量密度的提升显得至关重要。
然而，传统的锂离子电池石墨负极实际使用克容量为360mAh/g，已接近其理论值(372mAh/g)，因而有必要开发新型高容量负极材料。硅基材料是目前研究最多的，可替代石墨的负极材料之一。根据不同的反应深度，硅与锂可生成不同的产物，如Li 7Si 3、Li 13Si 4、Li 22Si 5、Li 12Si 17等。其中锂嵌入硅形成的Li 4.4Si合金，理论克容量为4200mAh/g，是理论克容量最高的负极材料。但是如图1所示硅基材料在脱嵌锂反应过程中会发生剧烈的体积膨胀(0～300％)和收缩，从而导致电极材料的结构破坏与粉化，并且硅表面会与电解液不断产生新的SEI膜(solid electrolyte interface，固体电解质界面膜)，从而导致电解液消耗殆尽，电池容量迅速衰减。
发明内容
本申请实施例提供一种纳米硅复合材料及其制备方法、电极材料、电池，用于解决电池负极材料体积膨胀大以及与电解液副反应严重的问题。
为达到上述目的，本申请采用如下技术方案：
第一方面，提供一种纳米硅复合材料。该纳米硅复合材料包括内核、第一包覆层和第二包覆层。内核包括纳米硅晶。第一包覆层包覆内核的表面；第一包覆层为多孔结构，第一包覆层的材料包括偏硅酸盐和脱氧态的氧化亚硅；第二包覆层包覆第一包覆层的表面；第二包覆层的材料包括脱氧态的二氧化硅。示例性的，脱氧态的氧化亚硅的化学式SiO 1-m，0＜m＜1；脱氧态的二氧化硅的化学式为SiO n，1＜n＜2。氧化亚硅(SiO，也可以称为一氧化硅或氧化硅(II))的分子结构中硅原子和氧原子的比例是1:1，脱氧态的氧化亚硅由于少了部分氧原子，因此脱氧态的氧化亚硅的分子结构中硅原子和氧原子的比例是1:m，0＜m＜1。二氧化硅(SiO 2)的分子结构中硅原子和氧原子的比例是1:2，脱氧态的二氧化硅由于少了部分氧原子，因此脱氧态的二氧化硅的分子结构中硅原子和氧原子的比例是1：n，1＜n＜2。由于纳米硅复合材料的内核包括纳米硅晶，而纳米硅晶的尺寸较小，因而在电池的充放电过程中，即金属离子(例如锂离子)的脱嵌反应中，能够有效地降低体积膨胀，从而降低了材料的机械疲劳，延长了循环寿命。此外，由于第一包覆层为多孔结构，因而第一包覆层能 够在内核膨胀和收缩时，起到缓冲作用，缓解内核的内应力，维持结构的稳定性以及第二包覆层的完整性。在此基础上，由于第一包覆层的表面包覆有第二包覆层，且第二包覆层的材料包括脱氧态的二氧化硅，因而第二包覆层能够起到阻挡电解液的作用，降低或消除电解液与硅的副反应。
在一种可能的实施方式中，纳米硅复合材料的粒径为10nm～150nm。
在一种可能的实施方式中，内核的粒径为10nm～130nm。
在一种可能的实施方式中，第一包覆层的厚度为0.1nm～10nm。
在一种可能的实施方式中，第二包覆层的厚度为0.1nm～10nm。
在一种可能的实施方式中，纳米硅晶的质量占纳米硅复合材料的质量的比例为70％～85％。
在一种可能的实施方式中，偏硅酸盐的质量占纳米硅复合材料的质量的比例a为0＜a≤7.5％。
在一种可能的实施方式中，氧化亚硅的质量占纳米硅复合材料的质量的比例b为0＜b≤7.5％。
在一种可能的实施方式中，二氧化硅的质量占纳米硅复合材料的质量的比例c为0＜c≤15％。
在一种可能的实施方式中，偏硅酸盐包括偏硅酸锂。此处，由于偏硅酸盐包括偏硅酸锂，因此上述纳米硅复合材料可以应用于锂离子电池中。
第二方面，提供一种电极材料，该电极材料包括前述的纳米硅复合材料、石墨以及碳的混合物。该电极材料具有与前述实施例相同的技术效果，此处不再赘述。
在一种可能的实施方式中，纳米硅复合材料的质量占电极材料的质量的比例为3％～60％。
第三方面，提供一种电池，包括电芯、相应的连通辅件和回路，电芯包括正极、负极、电解液以及隔膜，负极包括前述的电极材料。该电池具有与前述实施例相同的技术效果，此处不再赘述。
第四方面，提供一种纳米硅复合材料的制备方法。该纳米硅复合材料的制备方法包括如下步骤：首先，对氧化亚硅和金属源进行处理，得到纳米硅、偏硅酸盐以及脱氧态的氧化亚硅的混合物；然后，对纳米硅、偏硅酸盐以及脱氧态的氧化亚硅的混合物进行酸洗，并研磨，得到纳米硅复合材料；纳米硅复合材料包括内核、包覆内核表面的第一包覆层以及包覆第一包覆层表面的第二包覆层；内核包括纳米硅晶；第一包覆层为多孔结构，第一包覆层的材料包括偏硅酸盐和脱氧态的氧化亚硅；第二包覆层的材料包括脱氧态的二氧化硅。由于制备得到的纳米硅复合材料的内核包括纳米硅晶，而纳米硅晶的尺寸较小，因而在电池的充放电过程中，即金属离子(例如锂离子)的脱嵌反应中，能够有效地降低体积膨胀，从而降低了材料的机械疲劳，延长了循环寿命。此外，由于第一包覆层为多孔结构，因而第一包覆层能够在内核膨胀和收缩时，起到缓冲作用，缓解内核的内应力，维持结构的稳定性以及第二包覆层的完整性。在此基础上，由于第一包覆层的表面包覆有第二包覆层，且第二包覆层的材料包括脱氧态的二氧化硅，因而第二包覆层能够起到阻挡电解液的作用，降低或消除电解液与硅的副反应。
在一种可能的实施方式中，对氧化亚硅和金属源进行处理，包括：将氧化亚硅和固态的金属源按照预设配比混合均匀或者将金属源蒸汽按照预设配比通入氧化亚硅中，并在惰性气氛或还原气氛的高温炉中进行焙烧。在金属源为固态或气态的情况下，可以采用该方法对氧化亚硅和金属源进行处理。
在一种可能的实施方式中，焙烧温度为300℃～900℃。
在一种可能的实施方式中，金属源为含金属离子的有机溶剂；对氧化亚硅和金属源进行处理，包括：将氧化亚硅和含金属离子的有机溶剂按照预设配比混合，并在惰性气氛或还原气氛下进行反应；对反应产物进行清洗和烘干。在金属源为液态的情况下，可以采用该方法对氧化亚硅和金属源进行处理。
在一种可能的实施方式中，反应温度小于200℃。
在一种可能的实施方式中，预设配比为金属源中的金属元素和氧化亚硅中的硅元素的摩尔比为0.1～1.0。
在一种可能的实施方式中，金属源包括锂源；锂源包括金属锂或锂盐。由于锂源包括金属锂或锂盐，因而制备得到的纳米硅复合材料可以应用于锂离子电池中。
在一种可能的实施方式中，含金属离子的有机溶剂包括含锂离子的有机溶剂。由于含金属离子的有机溶剂包括含锂离子的有机溶剂，因而制备得到的纳米硅复合材料可以应用于锂离子电池中。
附图说明
图1为现有技术提供的一种硅基材料脱嵌锂反应的结构示意图；
图2为本申请实施例提供的一种电池的结构示意图；
图3为相关技术提供的一种纳米硅充放电过程的结构示意图；
图4为相关技术提供的一种纳米硅表面设置包覆层，且与电解液反应的示意图；
图5为本申请实施例提供的一种纳米硅复合材料的结构示意图；
图6为本申请实施例提供的一种纳米硅复合材料的制备方法的流程示意图；
图7为本申请实施例提供的一种纳米硅复合材料的制备方法过程中的结构示意图；
图8为采用纳米硅复合材料制备的锂离子电池和采用纳米硅制备的锂离子电池的电芯循环性能对比示意图。
附图标记：
01-电池；02-纳米硅复合材料；1-正极；2-负极；3-电解液；4-隔膜；5-副反应产物；10-内核；11-正极集流体；12-正极材料；20-第一包覆层；30-第二包覆层；21-负极集流体；22-负极材料。
具体实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行描述，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。
以下，术语“第一”、“第二”等仅用于描述方便，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”等的特征可以明示或者隐含地包括一个或者更多个该特征。在本申请的描述中，除非另有说明，“多个”的含义是两个或两个以上。
本申请实施例提供一种电池。该电池可以为锂离子电池、钠离子电池或镁离子电池等。本申请实施例对上述电池的具体形式不做特殊限制。为了便于说明，以下以锂离子电池为例进行介绍。
如图2所示，上述电池01的主要结构包括电芯、相应的连通辅件(例如负载)和回路。电芯包括正极1、负极2、电解液3以及隔膜4。
其中，正极1包括正极集流体(也可以称为正极电极板)11以及涂布在正极集流体11表面的正极浆料，正极浆料包括正极材料12、导电剂和粘结剂等。正极集流体11例如可以为铝箔。正极材料12例如可以为钴酸锂。正极浆料中的导电剂例如可以为导电炭黑(super P，SP)。正极浆料中的粘结剂例如可以为聚偏氟氯乙烯(polyvinylidene fluoride，PVDF)。
负极2包括负极集流体(也可以称为负极电极板)21以及涂布在负极集流体21表面的负极浆料。负极浆料包括负极材料22、导电剂和粘结剂等。负极集流体21例如可以为铜箔。负极浆料中的导电剂例如可以为导电炭黑。负极浆料中的粘结剂例如可以为羧甲基纤维素(carboxymethyl cellulose，CMC)和丁苯橡胶(styrene-butadiene rubber，SBR)。
上述正极材料12和负极材料22可以脱嵌锂离子以实现能量的存储和释放。电解液3是锂离子在正极1和负极2之间传输的载体。不导电的隔膜4可透过锂离子，但能将正极1和负极2隔开防止短路。
锂离子电池的工作原理为：充电时正极材料12中的Li +和电解液3中的Li +向负极2聚集，得到电子，被还原成Li镶嵌在负极2的负极材料22中。放电时镶嵌在负极2的负极材料22中的Li失去电子，进入电解液3，电解液3内的Li +向正极1移动。基于上述锂离子电池的工作原理可知，正极材料12和负极材料22是发挥储能功用的主体部分，电芯的能量密度、循环性能及安全性能最直接的体现者。由于目前商用的正极材料12钴酸锂已达到其使用的最高极限，钴酸锂能达到的最大电压为4.4V，压实密度为4.2g/cm 3，因而负极材料22的容量发挥是整个电芯的能量密度的提升关键因素之一。
目前，由于硅基材料具有较高的克容量，因而常作为电池的负极材料，但是硅基材料在脱嵌锂反应过程中会发生剧烈的体积膨胀和收缩，从而导致电极材料的结构破坏与粉化，并且硅表面会与电解液不断产生新的SEI膜，从而导致电解液消耗殆尽，电池容量迅速衰减。
为了解决上述问题，相关技术中通常采用纳米化的方式来改善硅的体积膨胀效应。然而纳米化也带来了高比表面，易团聚难分散，与电解液接触面积大，副反应严重，硅材料失活快，电解液消耗速度快等问题。参考图3，纳米硅在充放电过程，硅表面会与电解液反应形成副反应产物5，经过多次充放电，硅表面会被形成的副反应产物5覆盖，从而导致锂离子不能嵌入硅材料中，硅材料失活，此外，硅与电解液反应还会导致电解液快速消耗。需要说明的是，附图3中纳米硅在第一次充放电前为晶体硅，经过首次充放电之后，就会形成非晶硅(amorphous Si，a-Si)。
为了进一步解决纳米化带来的问题，如图4所示，人们又在纳米硅(Si)负极材料表面设置包覆层(如碳(C)包覆层)。但碳包覆其孔隙无法真正缓解硅与电解液 的副反应，并且最新研究结果表明，由于其催化效应，能够加速硅与电解液中的六氟磷酸锂(LiPF 6)反应，从而会导致活性硅的损失和容量的衰减。
基于上述，本申请实施例提供一种电极材料，该电极材料可以作为上述电池01的负极2中的负极材料22使用。该电极材料包括纳米硅复合材料、石墨以及碳的混合物，该电极材料也可以称为纳米硅/石墨/碳复合材料。
在一些实施例中，上述电极材料中纳米硅复合材料的质量占电极材料的质量的比例为3％～60％。
示例的，纳米硅复合材料的质量占电极材料的质量的比例可以为3％、20％、40％或60％。
在一些实施例中，上述纳米硅复合材料的粒径为10nm～150nm。
示例的，纳米硅复合材料的粒径可以为10nm、30nm、60nm、100nm或150nm。
以下对纳米硅复合材料的结构进行具体介绍。
如图5所示，上述纳米硅复合材料02包括内核10、第一包覆层20以及第二包覆层30。内核10包括纳米硅晶(Si cluster)，纳米硅晶包括多个纳米硅原子。第一包覆层20包覆内核10的表面，第一包覆层20为多孔结构，第一包覆层20的材料包括偏硅酸盐和脱氧态的氧化亚硅(SiO 1-m，0＜m＜1)。第二包覆层30包覆第一包覆层20的表面；第二包覆层30的材料包括脱氧态的二氧化硅(SiO n，1＜n＜2)。
需要说明的是，氧化亚硅(SiO，也可以称为一氧化硅或氧化硅(II))的分子结构中硅原子和氧原子的比例是1:1，脱氧态的氧化亚硅由于少了部分氧原子，因此脱氧态的氧化亚硅的分子结构中硅原子和氧原子的比例是1:m，0＜m＜1。二氧化硅(SiO 2)的分子结构中硅原子和氧原子的比例是1:2，脱氧态的二氧化硅由于少了部分氧原子，因此脱氧态的二氧化硅的分子结构中硅原子和氧原子的比例是1：n，1＜n＜2。
此处，若内核10的尺寸太大，则在电池的充放电过程中，体积膨胀会较大；若内核10的尺寸太小，则会增加制备纳米硅复合材料02的工艺难度，导致成本增加。基于此，在一些实施例中，内核10的粒径为10nm～130nm。
示例的，内核10的粒径可以为10nm、20nm、50nm、100nm或130nm。
此外，内核10的形状例如可以为球形或类球形等。
在此基础上，第一包覆层20的厚度可以根据内核10的粒径进行相应调整。在设置第一包覆层20的厚度时，既要确保第一包覆层20能够起到缓冲作用，又要确保不能影响内核10在充放电过程中锂离子的脱嵌反应。基于此，在一些实施例中，第一包覆层20的厚度为0.1nm～10nm。
示例的，第一包覆层20的厚度可以为0.1nm、1nm、5nm或10nm。
另外，第二包覆层30的厚度也可以根据内核10的粒径进行相应调整。在设置第二包覆层30的厚度时，既要确保第二包覆层30能够阻挡电解液与硅反应，又要确保不能影响内核10在充放电过程中锂离子的脱嵌反应。基于此，在一些实施例中，第二包覆层20的厚度为0.1nm～10nm。
示例的，第二包覆层20的厚度可以为0.1nm、1nm、5nm或10nm。
应当理解到，由于第一包覆层20包覆内核10表面，第二包覆层30包覆第一包 覆层20表面，因而第一包覆层20的形状和第二包覆层30的形状与内核10的形状有关。示例的，内核10的形状为球形，第一包覆层20的截面形状和第二包覆层30的截面形状为圆形。
在本申请的一些实施例中，纳米硅晶的质量占纳米硅复合材料的质量的比例为70％～85％。即，纳米硅晶的摩尔数与偏硅酸盐、脱氧态的氧化亚硅和脱氧态的二氧化硅的摩尔数之和的比值为7:3～4:1。
示例的，纳米硅晶的质量占纳米硅复合材料的质量的比例可以为70％、80％或85％。
在本申请的一些实施例中，第一包覆层20中的偏硅酸盐的质量占纳米硅复合材料的质量的比例a为0＜a≤7.5％。
示例的，偏硅酸盐的质量占纳米硅复合材料的质量的比例可以为2％、5％或7.5％。
在一些示例中，偏硅酸盐包括偏硅酸锂(Li 2xSi yO x+2y，x，y为正整数)。在偏硅酸盐为偏硅酸锂的情况下，本申请实施例提供的电池为锂离子电池。锂离子电池具有能量密度高、充放电速度快、使用寿命长以及自放电小等优势。
需要说明的是，上述的偏硅酸锂例如可以为Li 2SiO 3、Li 2Si 2O 5或Li 4SiO 4中的至少一种。由于纳米硅复合材料在使用时，需要与石墨、碳混合制成电极材料，电极材料再与导电剂、粘结剂等混合制成浆料涂布在负极集流体21上，而Li 2SiO 3难溶于水，在制成浆料的过程中不受水性制浆工艺的影响，因此在一些示例中，偏硅酸锂为Li 2SiO 3。
在本申请的一些实施例中，第一包覆层20中的氧化亚硅的质量占纳米硅复合材料的质量的比例b为0＜b≤7.5％。
示例的，氧化亚硅的质量占纳米硅复合材料的质量的比例可以为2％、5％或7.5％。
基于上述，偏硅酸盐的质量占纳米硅复合材料的质量的比例与氧化亚硅的质量占纳米硅复合材料的质量的比例可以相同，也可以不相同。
在本申请的一些实施例中，二氧化硅的质量占纳米硅复合材料的质量的比例c为0＜c≤15％。
示例的，二氧化硅的质量占纳米硅复合材料的质量的比例可以为1％、5％、10％或15％。
本申请实施例提供一种纳米硅复合材料02，纳米硅复合材料02包括内核10、第一包覆层20以及第二包覆层30。内核10包括纳米硅晶，第一包覆层20包覆内核10表面，第一包覆层20为多孔结构，第一包覆层20的材料包括偏硅酸盐和脱氧态的氧化亚硅，第二包覆层30包覆第一包覆层20的表面；第二包覆层30的材料包括脱氧态的二氧化硅。由于纳米硅复合材料02的内核10包括纳米硅晶，而纳米硅晶的尺寸较小，因而在电池的充放电过程中，即金属离子(例如锂离子)的脱嵌反应中，能够有效地降低体积膨胀，从而降低了材料的机械疲劳，延长了循环寿命。此外，由于第一包覆层20为多孔结构，因而第一包覆层20能够在内核10膨胀和收缩时，起到缓冲作用，缓解内核10的内应力，维持结构的稳定性以及第二包覆层30的完整性。在 此基础上，由于第一包覆层20的表面包覆有第二包覆层30，且第二包覆层30的材料包括脱氧态的二氧化硅，因而第二包覆层30能够起到阻挡电解液的作用，降低或消除电解液与硅的副反应。
本申请实施例还提供一种纳米硅复合材料02的制备方法，可以用于制备上述的纳米硅复合材料02。如图6所示，纳米硅复合材料02的制备方法包括：
S100、对氧化亚硅和金属源进行处理，得到纳米硅、偏硅酸盐以及脱氧态的氧化亚硅的混合物。
此处，可以根据金属源的形态对氧化亚硅和金属源进行处理。以下示例性地提供三种方式对氧化亚硅和金属源进行处理。
在金属源为固态的情况下，可以按照方式一对氧化亚硅和金属源进行处理。具体的，方式一为：将氧化亚硅和固态的金属源按照预设配比混合均匀，并在惰性气氛或还原气氛的高温炉中进行焙烧。
可以理解的是，可以先将氧化亚硅和固态的金属源按照预设配比混合均匀后转移到匣钵中，再将匣钵转移到惰性气氛或还原气氛的高温炉中进行焙烧。
在金属源为气态的情况下，可以按照方式二对氧化亚硅和金属源进行处理。具体的，方式二为：将金属源蒸汽按照预设配比通入氧化亚硅中，并在惰性气氛或还原气氛的高温炉中进行焙烧。
采用方式一或方式二对氧化亚硅和金属源进行处理时，在一些实施例中，焙烧温度为300℃～900℃。
示例的，焙烧温度例如可以为300℃、500℃、700℃或900℃。
此外，上述方式一和方式二中使用的高温炉例如可以为真空炉、箱式炉、回转炉或管式炉。
采用方式一或方式二对氧化亚硅和金属源进行处理时，在一些实施例中，金属源为金属单质或者含有金属离子的盐类。在纳米硅复合材料应用于锂离子电池的负极材料中的情况下，金属源包括锂源；锂源包括金属锂或锂盐。
示例的，锂盐包括LiH、LiAlH 4、Li 2CO 3、LiNO 3、LiAc以及LiOH中的一种或多种。
在金属源为液态的情况下，金属源为含金属离子的有机溶剂，可以按照方式三对氧化亚硅和金属源进行处理。具体的，方式三为：将氧化亚硅和含金属离子的有机溶剂按照预设配比混合，并在惰性气氛或还原气氛下进行反应；之后，对反应产物进行清洗和烘干。
在一些实施例中，反应温度小于200℃。
示例的，反应温度可以为20℃、50℃、100℃或150℃。
此处，上述有机溶剂例如可以为醇、醚或酮中的至少一种。
另外，可以利用去离子水对反应产物进行清洗，清洗的目的是为了去除有机溶剂。
在纳米硅复合材料应用于锂离子电池的负极材料中的情况下，上述含金属离子的有机溶剂包括含锂离子的有机溶剂。
上述方式一、方式二以及方式三中的惰性气氛例如可以为氩气(Ar气)、氦气 (He气)、氖气(Ne气)、氮气(N2气)或氙气(Xe气)中的至少一种。还原气氛例如可以为氢气(H2)、乙烯(C2H4)或甲烷(CH4)中的至少一种。
需要说明的是，在一些实施例中，上述方式一、方式二以及方式三中的预设配比为金属源中的金属元素和氧化硅中的硅元素的摩尔比为0.1～1.0，即，0.1≤nX/nSi≤1.0，X表示金属元素。例如，锂源中的锂元素与氧化硅中的硅元素的摩尔比为0.1～1.0，即0.1≤nLi/nSi≤1.0。
在此基础上，对氧化亚硅和金属源进行处理时，可以通过控制反应条件(例如金属源中的金属元素和氧化亚硅中的硅元素的配比、反应温度等)对反应形成的产物的结构进行调整，以将氧化亚硅转化成特定组成的含有金属离子的硅氧化合物(例如锂化硅氧化合物Li 2SiO 3)。示例的，可以通过控制锂源中的锂元素和氧化亚硅中的硅元素的配比、反应温度等调整偏硅酸锂(或偏锂硅酸盐)的类型。其中，富锂和低温反应有利于形成Li 2SiO 3。
S101、对纳米硅、偏硅酸盐以及脱氧态的氧化亚硅的混合物进行酸洗，并研磨，得到纳米硅复合材料02。纳米硅复合材料02包括内核10、包覆内核10表面的第一包覆层20以及包覆第一包覆层20表面的第二包覆层30。内核10包括纳米硅晶；第一包覆层20为多孔结构，第一包覆层20的材料包括偏硅酸盐和脱氧态的氧化亚硅；第二包覆层30的材料包括脱氧态的二氧化硅。
此处，酸洗时选取的酸洗液例如可以为硫酸、盐酸、硝酸和氢氟酸中的一种或多种。酸洗的目的是为了对偏硅酸盐中的特定相进行去除，以形成孔隙。基于酸洗的目的，选取的酸洗液应具有很强的腐蚀性，同时具有很强的氧化性，能够定向地和材料反应。例如，步骤S100中得到的偏硅酸盐包括Li 2SiO 3或Li 2Si 2O 5等，通过酸洗可以定向去除Li 2Si 2O 5，以形成孔隙，并使剩下的偏硅酸盐主要为Li 2SiO 3。
需要说明的是，对经过酸洗后的前驱体进行研磨时，可以将经过酸洗后的前驱体送入研磨机的研磨槽中，在研磨槽内填充适量的研磨媒体，例如玻璃珠，再通过研磨机中的分散叶片高速转动，使研磨媒体与酸洗后的前驱体撞击，从而达到分散的效果，以使酸洗后的前驱体的粒径进一步降低。研磨不仅可以使酸洗后的前驱体的粒径降低，还可以在纳米硅复合材料的表面形成脱氧态的二氧化硅，即形成第二包覆层30。
应当理解的是，研磨完后，可以采用分离的方法将反应产物和研磨媒体分离排出。此处，分离的方法例如可以为沉淀分离法、离心分离法或溶剂分离法中至少一种。
另外，对于纳米硅复合材料02中内核10的粒径、第一包覆层20的厚度、第二包覆层30的厚度可以参考上述实施例，此处不再赘述。再者，对于纳米硅晶、偏硅酸盐、氧化亚硅以及二氧化硅的质量比可以参考上述实施例，此处不再赘述。
本申请实施例提供一种纳米硅复合材料02的制备方法，由于制备得到的纳米硅复合材料02包括内核10、第一包覆层20以及第二包覆层30。内核10包括纳米硅晶，第一包覆层20包覆内核10表面，第一包覆层20为多孔结构，第一包覆层20的材料包括偏硅酸盐和脱氧态的氧化亚硅，第二包覆层30包覆第一包覆层20的表面；第二包覆层30的材料包括脱氧态的二氧化硅。由于纳米硅复合材料02的内核10包 括纳米硅晶，而纳米硅晶的尺寸较小，因而在电池的充放电过程中，即金属离子(例如锂离子)的脱嵌反应中，能够有效地降低体积膨胀，从而降低了材料的机械疲劳，延长了循环寿命。此外，由于第一包覆层20为多孔结构，因而第一包覆层20能够在内核10膨胀和收缩时，起到缓冲作用，缓解内核10的内应力，维持结构的稳定性以及第二包覆层30的完整性。在此基础上，由于第一包覆层20的表面包覆有第二包覆层30，且第二包覆层30的材料包括脱氧态的二氧化硅，因而第二包覆层30能够起到阻挡电解液的作用，降低或消除电解液与硅的副反应。
本申请实施例还提供一种电极材料的制备方法，包括：将通过步骤S100和步骤S101制备得到的纳米硅复合材料02与石墨、碳进行混合，以得到电极材料。
其中，纳米硅复合材料02的质量占纳米硅复合材料02、石墨以及碳的质量之和的比例为3％～60％。
本申请实施例还提供一种电极浆料的制备方法，包括：将上述制备得到的电极材料与导电剂、粘结剂分散于去离子水中，搅拌均匀，以得到电极浆料。
此处，导电剂例如可以为SP。粘结剂例如可以为SBR和CMC。
本申请实施例还提供一种负极的制备方法，包括：将上述制备得到的电极浆料涂布到负极集流体表面，烘干，即可得到负极(也可以称为负极电极片)。
其中，负极集流体例如可以为铜箔。
以下提供一个具体的实施例，详细说明纳米硅复合材料02、电极材料以及锂离子电池的制备过程。
参考图7，制备纳米硅复合材料02的具体步骤如下：
S200、称取氧化亚硅(SiO)和固态的锂源，锂源中锂元素和氧化亚硅中硅元素的摩尔比nLi/nSi＝0.1～1.0，将称取的氧化亚硅和固态的锂源在Ar气气氛或氢气(H 2)和Ar气的混合气氛的保护下充分混合均匀，之后将混合均匀的氧化亚硅和锂源转移到惰性气氛保护的高温炉中在500℃～900℃进行高温焙烧，反应时间为5h～48h。反应结束后，就可以得到预锂化的氧化亚硅，即得到纳米硅、偏硅酸锂(Li 2SiO 3)以及脱氧态的氧化亚硅(SiO 1-m，0＜m＜1)的混合物。步骤S200也可以称为预锂化过程。
S201、称取5g上述纳米硅、偏硅酸锂以及脱氧态的氧化亚硅的混合物，加入过量的1mol/L的盐酸进行搅拌，搅拌速度为200r/min，反应12h～24h，过滤、洗涤，在80℃下真空干燥6h～12h。将干燥后的产物转入研磨机中，在乙醇和Ar气的保护下，研磨24h～48h，过滤、洗涤、烘干得到纳米硅复合材料02。纳米硅复合材料02的内核10包括纳米硅晶，第一包覆层20包覆内核10的表面，第一包覆层20的材料包括偏硅酸锂(Li 2SiO 3)和脱氧态的氧化亚硅(SiO 1-m，0＜m＜1)，第二包覆层30包覆第一包覆层20的表面；第二包覆层30的材料包括脱氧态的二氧化硅(SiO n，1＜n＜2)。步骤S201也可以称为酸洗、研磨过程。
对上述制备的纳米硅复合材料02的性能进行检测，纳米硅复合材料02的克容量为2000～3500mAh/g，首次库伦效率为80％～90％。由此可见，本申请实施例制备的纳米硅复合材料02具有较高的克容量，且首次库伦效率较高。
将采用S200和S201制备得到的纳米硅复合材料02与现有的纳米硅(纳米硅指 的是直径为纳米级别的晶体硅颗粒，例如直径小于5nm的晶体硅颗粒)进行对比，对比结果如表1所示。
表1
Figure PCTCN2021097038-appb-000001
根据上表的结果可知，本申请实施例制备得到的纳米硅复合材料02在克容量和效率上具有优势。
制备电极材料的具体步骤如下：
S300、将采用S200和S201制备得到的纳米硅复合材料02、石墨、碳，按照质量比为40％：50％：10％进行混合，得到电极材料，该电极材料可以作为负极材料。
制备锂离子电池的具体步骤如下：
S400、将采用S300制备得到的电极材料与导电剂SP、粘结剂SBR、粘结剂CMC，按照质量比为95:0.3:3.2:1.5分散于去离子水中，搅拌均匀，得到电极浆料。接下来，在铜箔表面涂布电极浆料，85℃烘干，得到负极(即负极电极片)2。将制备得到的负极2配合钴酸锂正极(即正极电极片)，选取电解液为1mol/L的LiPF 6/EC(碳酸乙烯酯，ethylene carbonate)、PC(聚碳酸酯，polycarbonate)、DEC(碳酸二乙酯，ethyl carbonate)以及EMC(碳酸甲乙酯，ethyl methyl carbonate)的混合液，LiPF 6/EC、PC、DEC、EMC的体积比为1:0.3:1:1，使用三层隔膜，中间层的材料为PE(聚乙烯，polyethylene)，两侧层的材料为PP(聚丙烯，polypropylene)，三层隔膜的厚度为10μm，制成3.7Ah左右的软包电池。
为了对采用本申请实施例提供的方法制备的纳米硅复合材料02制备得到的锂离子电池的性能和采用纳米硅制备得到的锂离子电池的性能进行对比。将纳米硅与石墨、碳，按照质量比为40％：50％：10％进行混合，得到电极材料，并将采用纳米硅制备得到的电极材料与导电剂SP、粘结剂SBR、粘结剂CMC，按照质量比为95:0.3:3.2:1.5分散于去离子水中，搅拌均匀，得到电极浆料。接下来，在铜箔表面涂布电极浆料，85℃烘干，得到负极2。将制备得到的负极2配合钴酸锂正极，选取电解液为1mol/L的LiPF 6/EC、PC、DEC以及EMC的混合液，LiPF 6/EC、PC、DEC、EMC的体积比为1:0.3:1:1，使用三层隔膜，中间层的材料为PE，两侧层的材料为PP，三层隔膜的厚度为10μm，制成3.7Ah左右的软包电池。之后，对采用上述纳米硅复合材料02制成的3.7Ah左右的软包电池和采用纳米硅制成的3.7Ah左右的软包电池的电芯循环性能进行测试，测试结果如图8所示。图8示出了对采用上述纳米硅复合材料02制备的两个锂离子软包电池进行测试得到的多个采样点以及对采用纳米硅制备的两个锂离子软包电池进行测试得到的多个采样点。附图8中横轴表示充放电的循环次数，例如循环次数为500周指的是电芯充放电500次。纵轴表示电芯的容量保持率。循环性能可以用充放电的循环次数和电芯的容量保持率来表示，在循环次数相同的情况下，电芯的容量保持率越高，则认为锂离子电池的电芯循环性能越好。
参考图8可以看出，采用上述纳米硅复合材料02制备的锂离子电池，在电芯的循环性能上表现优异，循环次数为500周时，电芯的容量保持率在80％，而采用纳米硅制备的锂离子电池，在循环次数为200周时，电芯的容量保持率已经衰减至80％。此外，在循环次数为200周时，经测试采用上述纳米硅复合材料02制备的锂离子电池和采用纳米硅制备的锂离子电池的电芯膨胀率分别为6％和13％。
根据上述测试可知，采用上述纳米硅复合材料02制备的锂离子电池有利于电芯循环性能的提升和膨胀率的降低。这主要是因为采用纳米硅复合材料02的内核10包括纳米硅晶，而纳米硅晶的尺寸较小，因而能够降低体积膨胀。此外，纳米硅复合材料02的第一包覆层20为多孔结构，可以在内核10膨胀和收缩时，起到缓冲作用，维持结构的稳定性，降低体积膨胀，提高电芯循环性能。在此基础上，纳米硅复合材料02的第二包覆层30能够阻挡电解液，降低或消除电解液与硅的副反应，也能提高电芯循环性能。
以上所述，仅为本发明的具体实施方式，但本发明的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本发明揭露的技术范围内，可轻易想到变化或替换，都应涵盖在本发明的保护范围之内。因此，本发明的保护范围应以所述权利要求的保护范围为准。

Claims (20)

  1. 一种纳米硅复合材料，其特征在于，包括：
    内核；所述内核包括纳米硅晶；
    包覆所述内核表面的第一包覆层，所述第一包覆层为多孔结构，所述第一包覆层的材料包括偏硅酸盐和脱氧态的氧化亚硅；
    包覆所述第一包覆层表面的第二包覆层；所述第二包覆层的材料包括脱氧态的二氧化硅。
  2. 根据权利要求1所述的纳米硅复合材料，其特征在于，所述纳米硅复合材料的粒径为10nm～150nm。
  3. 根据权利要求1所述的纳米硅复合材料，其特征在于，所述内核的粒径为10nm～130nm。
  4. 根据权利要求1所述的纳米硅复合材料，其特征在于，所述第一包覆层的厚度为0.1nm～10nm。
  5. 根据权利要求1所述的纳米硅复合材料，其特征在于，所述第二包覆层的厚度为0.1nm～10nm。
  6. 根据权利要求1所述的纳米硅复合材料，其特征在于，所述纳米硅晶的质量占所述纳米硅复合材料的质量的比例为70％～85％。
  7. 根据权利要求1所述的纳米硅复合材料，其特征在于，所述偏硅酸盐的质量占所述纳米硅复合材料的质量的比例a为0＜a≤7.5％。
  8. 根据权利要求1所述的纳米硅复合材料，其特征在于，所述氧化亚硅的质量占所述纳米硅复合材料的质量的比例b为0＜b≤7.5％。
  9. 根据权利要求1所述的纳米硅复合材料，其特征在于，所述二氧化硅的质量占所述纳米硅复合材料的质量的比例c为0＜c≤15％。
  10. 根据权利要求1～9任一项所述的纳米硅复合材料，其特征在于，所述偏硅酸盐包括偏硅酸锂。
  11. 一种电极材料，其特征在于，所述电极材料包括如权利要求1～10任一项所述的纳米硅复合材料、石墨以及碳的混合物。
  12. 根据权利要求11所述的电极材料，其特征在于，所述纳米硅复合材料的质量占所述电极材料的质量的比例为3％～60％。
  13. 一种电池，包括电芯、相应的连通辅件和回路，所述电芯包括正极、负极、电解液以及隔膜，其特征在于，所述负极包括如权利要求11或12所述的电极材料。
  14. 一种纳米硅复合材料的制备方法，其特征在于，包括：
    对氧化亚硅和金属源进行处理，得到纳米硅、偏硅酸盐以及脱氧态的氧化亚硅的混合物；
    对所述纳米硅、所述偏硅酸盐以及所述脱氧态的氧化亚硅的混合物进行酸洗，并研磨，得到纳米硅复合材料；所述纳米硅复合材料包括内核、包覆所述内核表面的第一包覆层以及包覆所述第一包覆层表面的第二包覆层；所述内核包括纳米硅晶；所述第一包覆层为多孔结构，所述第一包覆层的材料包括偏硅酸盐和脱氧态的氧化亚硅；所述第二包覆层的材料包括脱氧态的二氧化硅。
  15. 根据权利要求14所述的纳米硅复合材料的制备方法，其特征在于，所述对氧化亚硅和金属源进行处理，包括：
    将氧化亚硅和固态的金属源按照预设配比混合均匀或者将金属源蒸汽按照预设配比通入氧化亚硅中，并在惰性气氛或还原气氛的高温炉中进行焙烧。
  16. 根据权利要求15所述的纳米硅复合材料的制备方法，其特征在于，焙烧温度为300℃～900℃。
  17. 根据权利要求14所述的纳米硅复合材料的制备方法，其特征在于，所述金属源为含金属离子的有机溶剂；
    所述对氧化亚硅和金属源进行处理，包括：
    将氧化亚硅和含金属离子的有机溶剂按照预设配比混合，并在惰性气氛或还原气氛下进行反应，其中反应温度小于200℃；
    对反应产物进行清洗和烘干。
  18. 根据权利要求15～17任一项所述的纳米硅复合材料的制备方法，其特征在于，所述预设配比为所述金属源中的金属元素和所述氧化亚硅中的硅元素的摩尔比为0.1～1.0。
  19. 根据权利要求15所述的纳米硅复合材料的制备方法，其特征在于，所述金属源包括锂源；所述锂源包括金属锂或锂盐。
  20. 根据权利要求17所述的纳米硅复合材料的制备方法，其特征在于，所述含金属离子的有机溶剂包括含锂离子的有机溶剂。
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115092935A (zh) * 2022-07-19 2022-09-23 合肥国轩高科动力能源有限公司 硅基复合材料及其制备方法与其在二次电池中的应用

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114864909A (zh) * 2022-06-13 2022-08-05 珠海冠宇电池股份有限公司 一种负极材料及包括该负极材料的负极片和电池
CN115084479A (zh) * 2022-07-05 2022-09-20 浙江吉利控股集团有限公司 一种锂电池负极复合材料及制备方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014034069A1 (ja) * 2012-08-28 2014-03-06 株式会社豊田自動織機 非水電解質二次電池用負極材料、その製造方法、非水電解質二次電池用負極及び非水電解質二次電池
CN109119617A (zh) * 2018-08-30 2019-01-01 华为技术有限公司 一种硅基复合负极材料及其制备方法和储能器件
CN111430677A (zh) * 2019-09-30 2020-07-17 蜂巢能源科技有限公司 负极材料及其制备方法、负极和锂离子电池
CN111584848A (zh) * 2020-05-22 2020-08-25 贝特瑞新材料集团股份有限公司 硅氧复合负极材料、其制备方法和锂离子电池

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108269979A (zh) * 2017-12-28 2018-07-10 合肥国轩高科动力能源有限公司 一种氧化亚硅/硅/偏硅酸锂复合负极材料及其制备方法
CN110615423B (zh) * 2019-09-24 2020-12-25 中国科学院化学研究所 一种锂电池硅基复合负极材料的制备方法
CN111129455A (zh) * 2019-12-17 2020-05-08 苏州宇豪纳米材料有限公司 一种高首效硅基负极材料及其制备方法

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014034069A1 (ja) * 2012-08-28 2014-03-06 株式会社豊田自動織機 非水電解質二次電池用負極材料、その製造方法、非水電解質二次電池用負極及び非水電解質二次電池
CN109119617A (zh) * 2018-08-30 2019-01-01 华为技术有限公司 一种硅基复合负极材料及其制备方法和储能器件
CN111430677A (zh) * 2019-09-30 2020-07-17 蜂巢能源科技有限公司 负极材料及其制备方法、负极和锂离子电池
CN111584848A (zh) * 2020-05-22 2020-08-25 贝特瑞新材料集团股份有限公司 硅氧复合负极材料、其制备方法和锂离子电池

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115092935A (zh) * 2022-07-19 2022-09-23 合肥国轩高科动力能源有限公司 硅基复合材料及其制备方法与其在二次电池中的应用
CN115092935B (zh) * 2022-07-19 2024-03-26 合肥国轩高科动力能源有限公司 硅基复合材料及其制备方法与其在二次电池中的应用

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