WO2025189643A1 - 硅碳材料及其制备方法与二次电池及用电装置 - Google Patents

硅碳材料及其制备方法与二次电池及用电装置

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Publication number
WO2025189643A1
WO2025189643A1 PCT/CN2024/108434 CN2024108434W WO2025189643A1 WO 2025189643 A1 WO2025189643 A1 WO 2025189643A1 CN 2024108434 W CN2024108434 W CN 2024108434W WO 2025189643 A1 WO2025189643 A1 WO 2025189643A1
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WO
WIPO (PCT)
Prior art keywords
silicon
carbon
carbon material
porous carbon
nano
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/CN2024/108434
Other languages
English (en)
French (fr)
Inventor
刘良彬
王家政
苏颖薇
谢率
邓静娴
吕子建
陈文强
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Contemporary Amperex Technology Co Ltd
Original Assignee
Contemporary Amperex Technology Co Ltd
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Filing date
Publication date
Application filed by Contemporary Amperex Technology Co Ltd filed Critical Contemporary Amperex Technology Co Ltd
Publication of WO2025189643A1 publication Critical patent/WO2025189643A1/zh
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/05—Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • C01B33/021—Preparation
    • C01B33/027—Preparation by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • C01B33/021—Preparation
    • C01B33/027—Preparation by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material
    • C01B33/029—Preparation by decomposition or reduction of gaseous or vaporised silicon compounds other than silica or silica-containing material by decomposition of monosilane
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/58—Selection of substances as active materials, active masses, active liquids of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates
    • H01M4/583—Carbonaceous material, e.g. graphite-intercalation compounds or CFx
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—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
    • 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
    • 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 field of batteries, and in particular to a silicon-carbon material and a preparation method thereof, a secondary battery, and an electrical device.
  • Silicon has the highest specific capacity of all known anode materials, reaching 4200 mAh/g.
  • the silicon-lithium alloy formed during the charging process of pure silicon in lithium-ion batteries causes the anode material to expand dramatically, with an expansion rate of up to 300%. This causes the anode material to collapse and pulverize, impairing the battery's cycling performance.
  • Silicon-carbon composites can effectively reduce the volume effect of the anode material.
  • the cycling performance of existing silicon-carbon anode materials has improved somewhat, but further optimization is still needed to meet the needs of power batteries.
  • the present application provides a silicon-carbon material and a preparation method thereof, a secondary battery and an electrical device, which are beneficial to improving the cyclability of the battery.
  • the present application provides a silicon-carbon material, including: silicon-carbon composite particles, the silicon-carbon composite particles including:
  • Porous carbon material has through pores
  • Nano-silicon grains located in the through-holes; the grain size of the nano-silicon grains is not less than the average pore size of the porous carbon material;
  • the silicon carbide material layer is at least partially located on the wall of the through hole.
  • the silicon-carbon material provided by the present application includes silicon-carbon composite particles, which include porous carbon material.
  • the porous carbon material has through holes, where the through holes include macropores, mesopores and micropores for depositing silicon material.
  • the silicon material is deposited in the through holes of the porous carbon material.
  • the through holes can limit the expansion of the silicon material.
  • the through holes because the through holes are connected to the closed holes, they have a certain degree of physical isolation from the electrolyte, which can also reduce the probability of side reactions caused by direct contact between the silicon material and the electrolyte.
  • the present application chooses to form nano-silicon grains with a certain suitable particle size in the through holes.
  • the nano-silicon grains of the suitable particle size are stacked to form nano-silicon particles.
  • the nano-silicon particles are further stacked along the inner wall of the through hole to form a layered or sheet-like film.
  • a silicon carbide material layer is generated where the layered or sheet-like film is in direct contact with the inner wall of the through hole. This arrangement can not only reduce the probability of it reacting with the electrolyte, but also control the expansion rate of the silicon material. This is because the expansion of the silicon material is not only restricted by the through holes, but also by the silicon carbide material layer.
  • the silicon-carbon material provided in this application has multiple aspects, such as the shape By forming nano-silicon grains with a certain appropriate particle size, physical isolation, physical restriction, etc., the probability of side reactions between silicon materials and electrolytes is reduced while controlling the degree of expansion of silicon materials during the process of lithium ion insertion and extraction, thereby improving the battery's cyclability to a certain extent.
  • the grain size of the nano-silicon grains is d1
  • the grain size of the nano-silicon grains is d1
  • the grain size of the nano-silicon grains is d1, d1 ⁇ 5 nm;
  • the average pore diameter of the porous carbon material is d2, and d2 is 1.0 nm to 5.0 nm.
  • the grain size of the nano-silicon grains is d1, and d1 is 5 nm to 20 nm;
  • the average pore diameter of the porous carbon material is d2, and d2 is 1.5 nm to 5.0 nm.
  • the silicon-carbon composite particles include closed pores, and the pore volume of the closed pores is smaller than the pore volume of the through pores.
  • the pore volume of the closed pores is V1, and V1 is 0.04 cm 3 /g to 0.16 cm 3 /g;
  • the pore volume of the through-pores is V2, and V2 is 0.3 cm 3 /g to 1.5 cm 3 /g.
  • the through pores include micropores, mesopores and macropores, and based on the total volume of the through pores, the volume ratio between the micropores, mesopores and macropores is (40% to 95%): (5% to 50%): (0 to 15%).
  • the silicon carbide material layer is located between the through hole and the nano-silicon grains, wherein one side of the silicon carbide material layer is connected to the inner wall of the through hole, and the other side is connected to the nano-silicon grains.
  • the thickness of the silicon carbide material layer is less than 0.7 nm.
  • the silicon-carbon material further includes a carbon coating layer disposed along the outer surface of the porous carbon material.
  • This carbon coating layer can reduce the probability of the nano-silicon grains being oxidized by contact with the outside air and can also reduce the probability of the nano-silicon grains reacting with the electrolyte.
  • the porous carbon material comprises porous carbon particles, and the porous carbon particles meet the following conditions:
  • the volume distribution particle size of the porous carbon particles satisfies the following requirements: Dv50 is 3.0 ⁇ m to 6.5 ⁇ m; Dv90 is 13.5 ⁇ m to 18.5 ⁇ m; and Dv10 is 0.9 ⁇ m to 2.5 ⁇ m.
  • the specific surface area of the porous carbon particles is 900 m 2 /g to 1550 m 2 /g;
  • the tap density of the porous carbon particles is 0.22 g/cm 3 to 0.48 g/cm 3 ;
  • the porous carbon material comprises porous carbon particles, and the porous carbon particles satisfy at least one of the following conditions:
  • the volume distribution particle size of the porous carbon particles satisfies the following requirements: Dv50 is 3.5 ⁇ m to 6.0 ⁇ m; Dv90 is 14.0 ⁇ m to 18.0 ⁇ m; and Dv10 is 1.0 ⁇ m to 2.0 ⁇ m.
  • the specific surface area of the porous carbon particles is 1000 m 2 /g to 1500 m 2 /g;
  • the tap density of the porous carbon particles is 0.25 g/cm 3 to 0.45 g/cm 3 ;
  • the mass percentage content of the silicon element in the silicon-carbon material is w silicon , which satisfies: w silicon is 38.0% to 48.0%.
  • the silicon-carbon composite particles meet the following conditions:
  • the volume distribution particle size of the silicon-carbon composite particles satisfies the following requirements: (Dv90-Dv10)/Dv50 is 1.2 to 2.8;
  • the specific surface area of the silicon-carbon composite particles is 3.0 m 2 /g to 12.0 m 2 /g;
  • the tap density of the silicon-carbon composite particles is 0.5 g/cm 3 to 1.0 g/cm 3 ;
  • the compacted density of 5 tons of silicon-carbon composite particles is 0.80 g/cm 3 to 1.1 g/cm 3 .
  • the silicon-carbon composite particles satisfy at least one of the following:
  • the volume distribution particle size of the silicon-carbon composite particles satisfies the following requirements: Dv50 is 3.5 ⁇ m to 9.0 ⁇ m; Dv90 is 14.0 ⁇ m to 21.0 ⁇ m; and Dv10 is 0.9 ⁇ m to 3.0 ⁇ m.
  • the specific surface area of the silicon-carbon composite particles is 5.0 m 2 /g to 10.0 m 2 /g;
  • the tap density of the silicon-carbon composite particles is 0.6 g/cm 3 to 0.8 g/cm 3 ;
  • the properties of the silicon-carbon composite particles meet the following requirements:
  • the powder resistivity of silicon-carbon composite particles at 4 MPa is 1.30 ⁇ cm to 3.80 ⁇ cm;
  • the lithium removal capacity of the silicon-carbon composite particles is 1300mAh/g to 1500mAh/g, and the first coulombic efficiency is 77% to 81%;
  • I 1 is the peak intensity near 0.3V to 0.35V
  • I 2 is the peak intensity near 0.43V to 0.50V
  • I 1 /I 2 1.4 to 1.8.
  • the dQ/dV curve of the silicon-carbon composite particles includes a CR2430 button cell assembled with the silicon-carbon composite particles as the positive electrode active material and a metal lithium sheet as the counter electrode, at 25°C, with a charge and discharge voltage of 0.005V to 2.0V, and is obtained by differentially processing the charge and discharge capacity and the working electrode potential.
  • the second aspect of the present application is to provide a method for preparing the silicon-carbon negative electrode material according to the first aspect, comprising:
  • a carbon source is introduced into the porous carbon material containing nano-silicon grains and a silicon carbide material layer to generate a silicon-carbon material containing a carbon coating layer.
  • reaction conditions for generating a porous carbon material comprising nano-silicon grains and a silicon carbide material layer are as follows:
  • reaction temperature is 500°C to 700°C, and the silicon source is introduced for 3 hours to 42 hours;
  • the silicon source comprises a silicon source gas and a diluent gas, wherein the volume fraction of the silicon source gas is 15% to 95%; the silicon source gas comprises either or both of monosilane and disilane;
  • the ventilation volume of the silicon source is 0.2L/min to 1.5L/min.
  • the porous carbon substrate comprises carbon, oxygen, and nitrogen, and the mass ratio of carbon to oxygen and nitrogen is (94% to 97%): (2% to 4%): (1% to 2%);
  • the ash content of the porous carbon substrate is ⁇ 0.5%.
  • the third aspect of the present application is to provide a secondary battery, which includes a negative electrode plate, and the negative electrode plate includes the silicon-carbon material described in the first aspect or the silicon-carbon material prepared by the preparation method described in the second aspect.
  • a fourth aspect of the present application is to provide an electrical device, which includes the secondary battery described in the third aspect.
  • FIG1 is a schematic diagram of a battery structure according to some embodiments of the present application.
  • FIG2 is a schematic diagram of the exploded structure of batteries according to some embodiments of the present application.
  • FIG3 is a schematic diagram of a vehicle structure according to some embodiments of the present application.
  • FIG4 is a schematic structural diagram of a battery pack according to some embodiments of the present application.
  • FIG5 is an electron microscope image of silicon-carbon materials prepared in some embodiments of the present application.
  • FIG6 is a schematic structural diagram of silicon-carbon materials prepared in some embodiments of the present application.
  • FIG7 is an X-ray photoelectron spectroscopy analysis graph of silicon-carbon materials prepared in some embodiments of the present application.
  • FIG8 is a further magnified electron microscope image of the silicon-carbon material obtained in some embodiments of the present application.
  • FIG9 is a transmission electron microscope image of a carbon coating layer of a silicon-carbon material obtained in some embodiments of the present application.
  • FIG10 is an X-ray diffraction pattern of silicon-carbon materials obtained in some embodiments of the present application.
  • FIG. 11 is a dQ/dV graph of discharge curves of silicon-carbon materials obtained in some embodiments of the present application.
  • ranges are defined in terms of lower and upper limits, where a given range is defined by selecting a lower limit and an upper limit, and the selected lower and upper limits define the boundaries of the particular range. Ranges defined in this manner can be inclusive or exclusive and can be combined arbitrarily, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if minimum range values of 1 and 2 are listed, and if maximum range values of 3, 4, and 5 are listed, the following ranges are all contemplated: 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5.
  • the numerical range "a to b" is a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers.
  • a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations.
  • a parameter is expressed as an integer ⁇ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
  • the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially.
  • the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.
  • the term "or” is used in this application to be inclusive.
  • the phrase “A or B” means “A, B, or both A and B.” More specifically, the condition “A or B” is satisfied if any of the following conditions are met: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).
  • multiple refers to more than two (including two).
  • multiple groups refers to more than two groups (including two groups), and “multiple pieces” refers to more than two pieces (including two pieces).
  • orientations or positional relationships indicated by technical terms such as “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, and “circumferential” are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limiting the embodiments of the present application.
  • silicon-carbon composites can effectively reduce the volume effect of negative electrode materials. Specifically, silicon-carbon composites involve mixing nano-silicon with carbon materials. By reducing the particle size of silicon-based materials to the nanometer level, more voids can be obtained to buffer the stress and deformation generated by silicon during the process of lithium ion insertion and extraction. However, as the particle size of silicon-based materials decreases, they are more likely to react with the electrolyte that slowly penetrates into the surface of the silicon-based material, thereby accelerating the cycle attenuation.
  • the prior art discloses methods including developing new electrolytes or forming physical isolation on the surface of silicon-based materials to reduce the probability of side reactions.
  • these improvements are not ideal.
  • the particle size of the silicon-based material can be increased to a certain extent, but not to an unlimited extent, and the probability of side reactions between the silicon-based material and the electrolyte can be reduced while controlling the degree of expansion of the silicon-based material during the deintercalation and extraction of lithium ions, the battery's cyclability can be improved to a certain extent.
  • the present application discloses a silicon-carbon material, which includes silicon-carbon composite particles, and the silicon-carbon composite particles include porous carbon material, nano-silicon grains, a silicon carbide material layer and a carbon coating layer.
  • the porous carbon material has through holes, the nano-silicon grains are located in the through holes, and the silicon carbide material layer is located between the through holes and the nano-silicon grains; the grain size of the nano-silicon grains is not less than the average pore size of the porous carbon material; and the carbon coating layer is arranged along the outer surface of the porous carbon material.
  • the silicon-carbon material provided by the present application includes silicon-carbon composite particles, which include porous carbon material.
  • the porous carbon material has through-holes, where the through-holes include macropores, mesopores and micropores for depositing silicon material.
  • the silicon material is deposited in the through-holes of the porous carbon material.
  • the through-holes can limit the expansion of the silicon material.
  • due to the physical isolation of the through-holes to a certain extent from the electrolyte the probability of side reactions caused by direct contact between the silicon material and the electrolyte can be reduced.
  • the present application chooses to form nano-silicon grains with a certain suitable particle size in the through-holes.
  • the nano-silicon grains of the suitable particle size are stacked to form nano-silicon particles.
  • the nano-silicon particles are further stacked along the inner wall of the through-hole to form a layered or sheet-like film.
  • a silicon carbide material layer is generated in the area where the layered or sheet-like film is in direct contact with the inner wall of the through-hole. This arrangement can not only reduce the probability of its reaction with the electrolyte, but also control the expansion rate of the silicon material. This is because the expansion of the silicon material is not only restricted by the through-holes, but also by the silicon carbide material layer.
  • a carbon coating is formed on the outside of the porous carbon material.
  • This carbon coating can reduce the probability of the nano-silicon grains coming into contact with the outside air and thus being oxidized, and can also reduce the probability of the nano-silicon grains reacting with the electrolyte. Therefore, the silicon-carbon material provided by this application reduces the probability of side reactions between the silicon material and the electrolyte while controlling the expansion degree of the silicon material during the process of lithium ion insertion and extraction, thereby improving the cyclability of the battery to a certain extent.
  • the silicon-carbon material provided in this application is used to make negative electrode sheets and is used in batteries, thereby improving the performance of the battery, such as improving the cyclability at a certain capacity, thereby enhancing the user experience.
  • the battery may include an outer packaging.
  • the outer packaging can be used to encapsulate the above-mentioned electrode assembly and electrolyte.
  • the outer packaging of the battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc.
  • the outer packaging of the battery can also be a soft package, such as a bag-type soft package.
  • the material of the soft package can be plastic. As plastic, polypropylene, polybutylene terephthalate, and polybutylene succinate can be listed.
  • FIG1 shows a secondary battery 10 with a square structure as an example.
  • the outer package may include a shell 101 and a cover 103 .
  • the shell 101 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity.
  • the shell 101 has an opening connected to the receiving cavity, and the cover plate 103 can be covered on the opening to close the receiving cavity.
  • the positive electrode sheet, the negative electrode sheet and the separator can form an electrode assembly 102 through a winding process or a lamination process.
  • the electrode assembly 102 is encapsulated in the receiving cavity.
  • the electrolyte is infiltrated in the electrode assembly 102.
  • the number of electrode assemblies 102 contained in the secondary battery 10 can be one or more, and those skilled in the art can select according to specific actual needs.
  • the electrode assembly provided in the present application is applied to batteries to improve battery performance.
  • the battery can be used as a power source for an electrical device or as an energy storage unit for an electrical device.
  • the electrical device is applied to the power field, such as mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but not limited to the above-mentioned fields.
  • the vehicle 10000 can be a fuel vehicle, a gas vehicle or a new energy vehicle.
  • the new energy vehicle can be a pure electric vehicle, a hybrid vehicle or an extended-range vehicle, etc.
  • a battery 1000 is provided inside the vehicle 10000, and the battery 1000 can be provided at the bottom, head or tail of the vehicle 10000.
  • the battery 1000 can be used to power the vehicle 10000.
  • the battery 1000 can serve as an operating power source for the vehicle 10000.
  • the vehicle 10000 may also include a controller 2000 and a motor 3000.
  • the controller 2000 is used to control the battery 1000 to power the motor 3000, for example, for starting, navigating and driving the vehicle 10000.
  • the battery 1000 can serve not only as an operating power source for the vehicle 10000, but also as a driving power source for the vehicle 10000, replacing or partially replacing fuel or natural gas to provide driving power for the vehicle 10000.
  • Battery 1000 includes a housing 200 and a battery cell 100.
  • Conventional battery cells include primary or secondary batteries, but this application specifically protects secondary batteries.
  • Battery cell 100 is housed within housing 200.
  • Housing 200 is used to accommodate battery cell 100 and can adopt a variety of structures.
  • the housing 200 may include a first portion 210 and a second portion 220.
  • the first portion 210 and the second portion 220 overlap each other, and together define a storage space for accommodating the secondary battery 100.
  • the second portion 220 may be a hollow structure with one end open, and the first portion 210 may be a plate-like structure.
  • the first portion 210 overlaps the open side of the second portion 220, so that the first portion 210 and the second portion 220 together define the storage space.
  • the first portion 210 and the second portion 220 may also each be a hollow structure with one end open, with the open side of the first portion 210 overlapping the open side of the second portion 220.
  • the housing 200 formed by the first portion 210 and the second portion 220 may have various shapes, such as a cylinder, a rectangular parallelepiped, etc.
  • the battery 1000 there may be multiple battery cells 100, and the multiple battery cells 100 may be connected in series or Parallel or hybrid connection, hybrid connection refers to multiple battery cells 100 being connected both in series and in parallel. Multiple battery cells 100 can be directly connected in series, in parallel, or in hybrid connection, and then the entire battery 100 can be housed in the housing 200.
  • the battery 1000 can also be in the form of multiple battery cells 100 connected in series, in parallel, or in hybrid connection to form a battery 1000 module, and then multiple battery modules 1000 are connected in series, in parallel, or in hybrid connection to form a complete battery 1000, and then housed in the housing 200.
  • the battery 1000 may also include other structures, for example, the battery 1000 may also include a busbar component for achieving electrical connection between the multiple battery cells 100.
  • the present application discloses a silicon-carbon material, which includes silicon-carbon composite particles, which include porous carbon material, nano-silicon grains, a silicon carbide material layer and a carbon coating layer.
  • the porous carbon material has through holes, the nano-silicon grains are located in the through holes, and the silicon carbide material layer is located on the through hole walls; the grain size of the nano-silicon grains is not less than the average pore size of the porous carbon material.
  • the silicon-carbon composite particles in this application include particles mainly composed of silicon and carbon elements.
  • the composite method here includes any conventional composite form in the art.
  • the nano-silicon grains in the present application include silicon grains with a particle size of nanometer level, and the formation methods of the nano-silicon grains include but are not limited to chemical vapor deposition, physical vapor deposition or atomic layer deposition.
  • the through holes in this application include through holes that are connected to the outside world, such as macropores, mesopores and micropores used to deposit silicon materials. Nano-silicon grains are distributed along the inner wall of the through holes and stacked to form silicon materials with layered or sheet-like films.
  • the grain size of the nano-silicon grains in the present application is not less than the average pore size of the porous carbon material.
  • the average pore size of the porous carbon material in the present application includes measurements made by any conventional method in the art. For example, the distribution of each pore is tested using a conventional test instrument in the art and the number of each pore is obtained by statistics, and then the average pore size is calculated by a mathematical function.
  • the pore volume and specific surface area of the porous carbon material can also be obtained by using adsorption and desorption isotherms.
  • the pore volume is divided by the specific surface area and multiplied by the model coefficient to obtain the average pore size;
  • the test instrument used is ASAP2460-physical adsorption analyzer, and the porous carbon material sample after drying and degassing is placed in liquid nitrogen, and different test pressures are adjusted to measure the adsorption amount of nitrogen respectively, and the adsorption and desorption isotherms are drawn. Then, the pore volume and specific surface area of the porous carbon material are obtained according to the adsorption and desorption isotherms, and then the average pore size of the porous carbon material is calculated.
  • the nano-silicon grains in the present application include silicon grains with a particle size of nanometer level, and the crystal form of the nano-level silicon grains includes the conventional crystal structure in the art.
  • the grain size of the nano-silicon grains includes the particle size distribution measured by a testing instrument such as an X-ray diffractometer and then obtained statistically, or the grain size is characterized by a transmission electron microscope and then obtained statistically.
  • the grain size of the nano-silicon grains of the present application is not less than the average pore size of the porous carbon material.
  • the grain size of the nano-silicon grains is d1
  • the average pore size of the porous carbon material is d2, satisfying d1 ⁇ d2. This is because the nano-silicon grains are distributed and stacked along the through-holes of the porous carbon material. Therefore, the average pore size of the porous carbon material does not affect the stacking process of the nano-silicon grains, but it can limit the result of the nano-silicon grain stacking.
  • This approach limits the expansion of the silicon material.
  • This approach selects nano-silicon grains of a suitable size and distributes them within the through-pores of the porous carbon material. This reduces the likelihood of side reactions between the silicon material and the electrolyte while controlling the silicon material's expansion during lithium ion insertion and extraction, and improves the battery's cyclability to a certain extent.
  • the formation of the silicon carbide material layer of the present application is affected by the preparation conditions. For example, during the growth of silicon grains, the silicon grains close to the inner wall of the through hole are easy to contact the wall and react to form a silicon carbide material layer.
  • the hardness of the silicon carbide material layer is greater than that of the silicon material, and it can limit the degree of outward expansion when the silicon material expands. Therefore, the silicon-carbon material provided by the present application reduces the probability of side reactions between the silicon material and the electrolyte while controlling the expansion degree of the silicon material during the deintercalation and extraction of lithium ions, thereby improving the cyclability of the battery to a certain extent.
  • the grain size d1 of the nano-silicon grains provided in this application cannot be indefinitely larger than the average pore size d2 of the porous carbon material. Otherwise, it will not only hinder the formation of the nano-silicon grains, but may also affect the performance of the battery. For example, lithium ions need to complete the deintercalation process from the relatively large silicon material, thereby affecting the battery's rate capability.
  • the grain size d1 of the nano-silicon grains is ⁇ 5 nm.
  • the grain size d1 of the nano-silicon grains is 5 nm to 20 nm.
  • the grain size d1 of the nano-silicon grains is 5 nm to 15 nm.
  • the nano-silicon grains herein include silicon grains having a size of nanometers, and the crystal form of the nano-silicon grains includes a conventional crystal structure in the art.
  • the grain size of the nano-silicon grains includes the grain size calculated using the Scherrer formula using an X-ray diffraction pattern known in the art, and the silicon grain size is a statistical size.
  • the present application selects a grain size of nano silicon grains ⁇ 5nm, because the grain size of silicon grains cannot be too small, otherwise it will easily increase the probability of side reactions. Silicon grains with this size are convenient and efficient to form in the through-holes, while also reducing the probability of their reaction with the electrolyte. At the same time, the grain size of nano silicon grains cannot be increased indefinitely. On the one hand, it is limited by the preparation process. On the other hand, nano silicon grains with larger grain sizes increase the degree and probability of expansion of silicon materials during the process of lithium ion insertion and removal, and are not conducive to the diffusion of lithium ions during the process of lithium ion insertion and removal.
  • the present application selects the grain size d1 of nano silicon grains to be 5nm to 20nm.
  • the present application discloses in these embodiments that the grain size d1 of nano silicon grains includes but is not limited to 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, Any one of 11nm, 12nm, 13nm, 14nm, 15nm, 16nm, 17nm, 18nm, 19nm, 20nm or any one of the values satisfying the above range.
  • the average pore diameter d2 of the porous carbon material is 1.0 nm to 5.0 nm.
  • the average pore diameter d2 of the porous carbon material is 1.5 nm to 5.0 nm.
  • the present application selects a porous carbon material with an average pore size of 1.0 nm to 5.0 nm, which facilitates the efficient formation of silicon material in the through-holes and also facilitates the subsequent restriction of silicon material expansion.
  • the average pore diameter of the porous carbon material is any one of 1.0 nm, 1.5 nm, 2.0 nm, 3.0 nm, 4.0 nm, 4.5 nm, and 5.0 nm, or any one of the values within the above ranges.
  • the silicon-carbon composite particles include closed pores, and the pore volume of the closed pores is smaller than the pore volume of the through pores.
  • the closed pores of the present application include pores in the silicon-carbon composite particles that are not connected to the outside world.
  • the closed pores include the closed pores possessed by the porous carbon material itself, and also include a certain number of closed pores formed in the through holes after the nano-silicon grains are formed in the through holes. These closed pores can further provide a slow-release space for the expansion of the silicon material on the basis of the above-mentioned through holes and the silicon carbide material layer to limit the expansion of the silicon material, thereby alleviating the expansion of the silicon-carbon material.
  • the pore volume of the closed pores is V1
  • the pore volume of the through pores is V2, satisfying V1 ⁇ V2.
  • ⁇ true is the test true density of the silicon-carbon material
  • wsilicon is the mass percentage content of silicon in the silicon-carbon material
  • wcarbon is the mass percentage content of carbon in the silicon-carbon material
  • ⁇ silicon is the theoretical true density of silicon
  • ⁇ carbon is the theoretical true density of carbon.
  • wsilicon includes the mass percentage content of silicon element based on the total mass of the silicon-carbon material
  • wcarbon includes the mass percentage content of carbon element based on the total mass of the silicon-carbon material.
  • ⁇ silicon is the theoretical true density of silicon, and its specific value is 2.34g/ cm3
  • ⁇ carbon is the theoretical true density of carbon, and its specific value is 2.26g/ cm3 .
  • ⁇ true is the test true density of the silicon-carbon material, which can be obtained by testing with reference to GB/T24586-2009.
  • the pore volume of the through pores of the porous carbon material of the present application can also be the pore volume of the porous carbon material, that is, the pore volume of the porous carbon material, which can be measured using instruments and methods known in the art, for example, it can be tested with reference to GB/T21650.2-2008.
  • the testing instrument can be a TRISTAR II 3020 Surface Area and Porosity Analyzer from Micromeritics, USA.
  • the through-holes in this application are primarily used to deposit silicon material, while the closed pores provide a slow-release space for silicon material expansion.
  • the closed pores occupy a certain pore volume to reduce the amount of nano-silicon grains formed within the porous carbon material, while not affecting the amount of nano-silicon grains used as the negative electrode active material. Therefore, the pore volume V1 of the closed pores is selected to be smaller than the pore volume V2 of the through-holes in this application.
  • the present application further provides specific values of the closed pore volume, V1, which is 0.05 cm 3 /g to 0.15 cm 3 /g.
  • the closed pore volume V1 selected in this application is 0.04 cm 3 /g to 0.16 cm 3 /g, which can occupy a certain pore volume and thus limit the amount of silicon material formed inside the porous carbon material, and can also buffer a part of the silicon material expansion caused by the expansion of the silicon material during the lithium insertion and extraction process.
  • the present application provides closed pore volume V1 including but not limited to any one of 0.04 cm 3 /g, 0.05 cm 3 /g, 0.06 cm 3 / g, 0.07 cm 3 /g, 0.08 cm 3 /g, 0.09 cm 3 /g, 0.1 cm 3 /g, 0.11 cm 3 /g, 0.12 cm 3 /g, 0.13 cm 3 /g, 0.14 cm 3 /g, 0.15 cm 3 /g, and 0.16 cm 3 /g, or any value within the above range.
  • the pore volume V2 of the through pores is 0.3 cm 3 /g to 1.5 cm 3 /g.
  • the pore volume of the through hole affects the compressive strength of the silicon-carbon material, and also affects the amount of silicon material formed and the size of silicon grains. Therefore, in this application, the pore volume V2 of the through hole is selected to be 0.3 cm 3 /g to 1.5 cm 3 /g.
  • the pore volume V2 of the through pores is further 0.6 cm 3 /g to 1.2 cm 3 /g.
  • the pore volume V2 of the through pores selected in this application includes but is not limited to any one of 0.3 cm 3 /g, 0.4 cm 3 /g, 0.5 cm 3 / g, 0.6 cm 3 /g, 0.7 cm 3 /g, 0.8 cm 3 /g, 0.9 cm 3 /g, 1.0 cm 3 /g, 1.1 cm 3 /g, 1.2 cm 3 /g, 1.3 cm 3 /g, 1.4 cm 3 /g, and 1.5 cm 3 /g, or any one within the above ranges.
  • the through pores include micropores, mesopores and macropores. Based on the total volume of the through pores, the volume ratio between the micropores, mesopores and macropores is (40% to 95%): (5% to 50%): (0 to 15%), preferably (45% to 95%): (5% to 45%): (0 to 10%).
  • micropores, mesopores and macropores in this application include the conventional meanings in this field, such as the pore size of micropores is less than 2nm, the pore size of mesopores is also called mesopores, which is 2nm to 50nm, and the pore size of macropores is greater than 50nm.
  • This application includes the use of conventional testing instruments in this field to test the distribution of each pore, such as the use of the testing instrument ASAP2460-physical adsorption analyzer to dry and degas the porous carbon material sample (porous carbon substrate) Place the sample in liquid nitrogen and adjust the test pressure to different levels. The nitrogen adsorption capacity is measured and the adsorption and desorption isotherms are plotted.
  • the pore shape is determined based on the hysteresis loop shape.
  • the pore distribution is calculated using different pore models.
  • the BJH model is used to fit the pore size distribution curves for mesopores and macropores, while the DFT model is used to fit the pore size distribution curve for micropores.
  • the volume ratio of micropores, mesopores and macropores is selected as (40% to 95%): (5% to 50%): (0 to 15%).
  • the volume percentage of macropores includes but is not limited to any one of 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15% or any one of the above range values. In some embodiments, the present application also discloses that no macropores are included.
  • the volume percentage of micropores includes but is not limited to any one of 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or any one of the above range values.
  • the volume percentage of mesopores includes but is not limited to any one of 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50% or any one of the values satisfying the above range.
  • the silicon-carbon material further includes a silicon carbide material layer, which is formed on at least a portion of the inner wall of the through-hole, with one side of the silicon carbide material layer connected to the inner wall of the through-hole and the other side connected to the nano-silicon grains.
  • the thickness of the silicon carbide material layer is less than 0.7 nm, and more preferably less than 0.4 nm.
  • the formation of the silicon carbide material layer of the present application is affected by the preparation conditions. For example, during the growth of silicon grains, the silicon grains near the inner wall of the through hole are prone to contact with the wall and react to form a silicon carbide material layer.
  • the hardness of the silicon carbide material layer is greater than that of the silicon material, which can limit the degree of outward expansion when the silicon material expands.
  • the thickness of the silicon carbide material layer is not easy to be too thick, because the thickness of the silicon carbide material layer affects the conductivity of the silicon-carbon material.
  • the thickness of the silicon carbide material layer in the present application is mainly obtained with the help of the relevant X-ray related maps.
  • a silicon carbide material layer is formed on the interface of the inner wall of the through hole where the nano-silicon grains are in contact with the porous carbon material.
  • the silicon carbide material layer is located between the through hole and the nano-silicon grains.
  • One side of the silicon carbide material layer is connected to the inner wall of the through hole of the porous carbon material, and the other side is connected to the nano-silicon to form a silicon carbide interface layer.
  • the silicon carbide interface layer is arranged adjacent to the nano-silicon grains to limit the degree of outward expansion of the nano-silicon grains during lithium insertion and extraction.
  • the silicon-carbon material further includes a carbon coating layer, and the carbon coating layer is disposed along the outer surface of the porous carbon material.
  • the carbon coating layer in the present application includes a carbon material layer arranged along the outer surface of the porous carbon material to form an outer shell layer that wraps the porous carbon material.
  • the outer shell layer can reduce the probability of nano-silicon contacting with the outside air and thus being oxidized, and on the other hand, it can reduce the probability of nano-silicon grains contacting and reacting with the electrolyte.
  • the carbon coating layer is amorphous carbon, such as soft carbon or hard carbon obtained by cracking during the preparation process.
  • the present application discloses that the thickness of the carbon coating layer is 5nm to 50nm, preferably 10nm to 30nm.
  • the carbon coating layer of suitable thickness will not affect the insertion of lithium ions and the capacity of the silicon-carbon material, but can also effectively protect the internal silicon particles to reduce the probability of side reactions.
  • the thickness of the carbon coating layer in the present application can also be obtained by means of the relevant X-ray correlation spectrum.
  • the silicon-carbon material contains silicon element. Based on the total mass of the silicon-carbon material, the mass percentage content of the silicon element is w silicon , which satisfies: w silicon is 38.0% to 48.0%.
  • wSi is 40.0% to 45.0%.
  • the silicon-carbon material contains carbon element. Based on the total mass of the silicon-carbon material, the mass percentage content of the carbon element is w carbon , which satisfies: w carbon is 50.0% to 55.0%.
  • the amount of silicon material formed in the through-hole affects the probability of its reaction with the electrolyte. Generally speaking, the more the amount formed, the greater its own expansion in the lithium insertion and extraction cycle, and the greater the probability of reacting with the electrolyte.
  • the content of the silicon material also affects the capacity of the battery.
  • the present application chooses to control w silicon to 38.0% to 48.0%.
  • w silicon includes but is not limited to any one of 38.0%, 40.0%, 42.0%, 43.0%, 44.0%, 45.0%, 48.0% or any one of the values in the above range.
  • the silicon-carbon material in the present application mainly includes silicon and carbon elements. In addition, it also includes other elements that are not necessary in the porous carbon material.
  • the silicon content and carbon content can be measured with the help of relevant standards.
  • the silicon content can refer to GB/T 20975.5-2020
  • the carbon content can refer to GB/T 20123-2006/ISO 15350:2000.
  • the porous carbon material comprises porous carbon material particles, and the particle size of the porous carbon material particles meets the following requirements: Dv50 is 3.0 ⁇ m to 6.5 ⁇ m; Dv90 is 13.5 ⁇ m to 18.5 ⁇ m; and Dv10 is 0.9 ⁇ m to 2.5 ⁇ m.
  • the present application discloses that the particle size of the porous carbon material particles meets the following requirements: Dv50 is 3.5 ⁇ m to 6.0 ⁇ m; Dv90 is 14.0 ⁇ m to 18.0 ⁇ m; and Dv10 is 1.0 ⁇ m to 2.0 ⁇ m.
  • Dv90 includes 90% of the volume of particles with a diameter smaller than it
  • Dv10 includes 10% of the volume of particles with a diameter smaller than it
  • Dv50 includes 50% of the volume of particles with a diameter larger than it, and 50% of the volume of particles smaller than it. It is also called the median diameter and is usually used to represent the average particle size of the particles.
  • conventional measurement methods in the art can be used, such as using a particle size analyzer to measure the particle size distribution and then obtain it statistically.
  • this application chooses to refer to the laser diffraction particle size analysis method for determination, specifically referring to the standard GB/T19077-2016 to obtain a particle size distribution diagram, and then obtains it by calculation.
  • the present application controls the particle size of the porous carbon material particles to meet the following requirements: Dv50 is 3.0 ⁇ m to 6.5 ⁇ m; Dv90 is 13.5 ⁇ m to 18.5 ⁇ m; and Dv10 is 0.9 ⁇ m to 2.5 ⁇ m. This allows the efficient formation of nano-silicon grains within the through-pores of the porous carbon material.
  • Dv50 is any one of 3.0 ⁇ m, 3.3 ⁇ m, 3.5 ⁇ m, 3.8 ⁇ m, 4.0 ⁇ m, 4.2 ⁇ m, 4.5 ⁇ m, 4.8 ⁇ m, 5.0 ⁇ m, 5.2 ⁇ m, 5.5 ⁇ m, 5.8 ⁇ m, 6.0 ⁇ m, and 6.5 ⁇ m, or any value within this range.
  • Dv90 includes but is not limited to any one of 13.5 ⁇ m, 14.0 ⁇ m, 14.5 ⁇ m, 15.0 ⁇ m, 15.5 ⁇ m, 16.0 ⁇ m, 16.5 ⁇ m, 17.0 ⁇ m, 17.5 ⁇ m, 18.0 ⁇ m, 18.5 ⁇ m, or any one of the above ranges.
  • Dv10 includes but is not limited to any one of 0.9 ⁇ m, 1.0 ⁇ m, 1.2 ⁇ m, 1.5 ⁇ m, 1.8 ⁇ m, 2.0 ⁇ m, 2.2 ⁇ m, 2.5 ⁇ m, or any one of the above ranges.
  • the specific surface area of the porous carbon material particles is 900 m 2 /g to 1550 m 2 /g.
  • the specific surface area of the porous carbon material particles is 1000 m 2 /g to 1500 m 2 /g.
  • the specific surface area in this application includes any conventional concept in the art, which can be obtained by testing using instruments or methods known in the art, such as using a gas adsorption method to test the specific surface area, specifically referring to the standard test of GB/T19587-2017.
  • the present application controls the specific surface area of the porous carbon material particles to be 900 m 2 /g to 1550 m 2 /g to facilitate the efficient formation of nano-silicon particles in the through-pores of the porous carbon material.
  • the present application also discloses that the specific surface area of the porous carbon material particles includes but is not limited to any one of 900 m 2 /g, 990 m 2 /g, 1000 m 2 /g, 1050 m 2 /g, 1100 m 2 /g, 1150 m 2 /g, 1200 m 2 /g, 1250 m 2 /g, 1300 m 2 /g, 1350 m 2 /g, 1400 m 2 /g, 1450 m 2 /g, 1500 m 2 /g, and 1550 m 2 /g, or any one of the values within the above ranges.
  • the tap density of the porous carbon material particles is 0.22 g/cm 3 to 0.48 g/cm 3 .
  • the tap density of the porous carbon material particles is 0.25 g/cm 3 to 0.45 g/cm 3 .
  • the tap density of the porous carbon material particles includes but is not limited to any one of 0.22 g/cm 3 , 0.25 g/cm 3 , 0.30 g/cm 3 , 0.35 g/cm 3 , 0.40 g/cm 3 , 0.45 g/cm 3 , 0.48 g/cm 3 , or any value within the above range.
  • the 5-ton powder compaction density of the porous carbon material particles is 0.45 g/cm 3 to 0.80 g/cm 3 .
  • the 5-ton powder compaction density of the porous carbon material particles is 0.50 g/cm 3 to 0.75 g/cm 3 .
  • the compaction density in this application includes any conventional concept in the field, which can be obtained by testing using instruments or methods known in the field, such as limiting the cold pressing pressure to 5 tons and referring to the calculation method of GB/T 24533-2009. For example, it is measured using an electronic pressure tester (such as UTM7305). Specifically, a specific amount M of the powder sample to be tested is placed on a special pressing die (the bottom area is S 0 ) and different pressures are set. Each pressure is maintained for 30 seconds and then released. After 10 seconds, the thickness H 0 of the powder pressed under the pressure is read on the device. The compaction density under the pressure is obtained by calculation, and the compaction density of the negative plate material under the pressure is equal to M/(H 0 ⁇ S 0 ).
  • the present application selects to control the compaction density of the porous carbon material particles at a cold pressing pressure of 5 tons to be 0.50 g/cm 3 -0.75 g/cm 3 , so as to effectively form nano-silicon grains while ensuring that the porous carbon material has the above-mentioned particle size, specific surface area and tap density.
  • the compacted density of the porous carbon material particles at 5 tons includes but is not limited to any one of 0.45 g/cm 3 , 0.50 g/cm 3 , 0.55 g/cm 3 , 0.60 g/cm 3 , 0.65 g/cm 3 , 0.70 g/cm 3 , 0.75 g/cm 3 , 0.80 g/cm 3 , or any value within the above ranges.
  • the particle size of the silicon-carbon composite particles satisfies the following relationship: (Dv90-Dv10)/Dv50 is 1.2-2.8.
  • the particle size of the silicon-carbon composite particles satisfies the following relationship: (Dv90-Dv10)/Dv50 is 1.3-2.5.
  • Dv90 includes 90% of the volume of particles with a diameter smaller than it
  • Dv10 includes 10% of the volume of particles with a diameter smaller than it
  • Dv50 includes 50% of the volume of particles with a diameter larger than it, and 50% of the volume of particles smaller than it. It is also called the median diameter and is usually used to represent the average particle size of the particles.
  • conventional measurement methods in the art can be used, such as using a particle size analyzer to measure the particle size distribution and then obtain it statistically.
  • this application chooses to refer to the laser diffraction particle size analysis method for determination, specifically referring to the standard GB/T19077-2016 to obtain a particle size distribution diagram, and then obtains it by calculation.
  • the particle size of the silicon-carbon composite particles selected in this application satisfies the following conditions: (Dv90-Dv10)/Dv50 is 1.2 to 2.8, so that the silicon-carbon composite particles of different sizes are properly matched to improve the volume energy density of the battery while minimizing the expansion of the silicon-carbon material during the lithium insertion and extraction process.
  • the present application provides (Dv90-Dv10)/Dv50 including but not limited to 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8 or any one of the values satisfying the range.
  • Some embodiments of the present application set specific numerical limits on the particle sizes of the silicon-carbon composite particles, such as Dv50 of 3.5 ⁇ m to 9.0 ⁇ m, Dv90 of 14.0 ⁇ m to 21.0 ⁇ m, and Dv10 of 0.9 ⁇ m to 3.0 ⁇ m.
  • Dv50 is given as 4.0 ⁇ m to 6.5 ⁇ m; Dv90 is given as 15.0 ⁇ m to 20.0 ⁇ m; and Dv10 is given as 1.0 ⁇ m to 2.5 ⁇ m.
  • this application controls the silicon-carbon composite particles to have a suitable particle size under the premise that the average particle size of the above-mentioned silicon grains is ⁇ 5nm to balance the overall performance of the silicon-carbon material.
  • this application discloses that the Dv50 of the silicon-carbon composite particles is any one of 3.5 ⁇ m, 3.8 ⁇ m, 4.0 ⁇ m, 4.2 ⁇ m, 4.5 ⁇ m, 5.0 ⁇ m, 5.5 ⁇ m, 5.8 ⁇ m, 6.0 ⁇ m, 6.2 ⁇ m, 6.5 ⁇ m, 6.7 ⁇ m, 7.0 ⁇ m, 7.5 ⁇ m, 8.0 ⁇ m, 8.5 ⁇ m, 9.0 ⁇ m or any one of the above ranges.
  • the Dv90 of the silicon-carbon composite particles is 14.0 ⁇ m, 14.5 ⁇ m, 15.0 ⁇ m, 15.2 ⁇ m, 15.5 ⁇ m, 15.8 ⁇ m, 16.0 ⁇ m, 16.5 ⁇ m, 17.0 ⁇ m, 17.5 ⁇ m, 18.0 ⁇ m, 18.5 ⁇ m, 19.0 ⁇ m, 19.5 ⁇ m, 20.0 ⁇ m, 20.5 ⁇ m, 21 ⁇ m or any one of the above ranges.
  • Dv10 is any one of 0.9 ⁇ m, 1.0 ⁇ m, 1.5 ⁇ m, 2.0 ⁇ m, 2.2 ⁇ m, 2.5 ⁇ m, 2.8 ⁇ m, 3.0 ⁇ m or any one of the above ranges.
  • the specific surface area of the silicon-carbon composite particles is 3.0 m 2 /g to 12.0 m 2 /g.
  • the specific surface area of the silicon-carbon composite particles is 5.0 m 2 /g to 10.0 m 2 /g.
  • the specific surface area in this application includes any conventional concept in the art, which can be obtained by testing using instruments or methods known in the art, such as using a gas adsorption method to test the specific surface area, specifically referring to the standard test of GB/T19587-2017.
  • the present application selects a specific surface area of 3.0 m 2 /g to 12.0 m 2 /g for the silicon-carbon composite particles so as to provide the silicon-carbon material with suitable lithium insertion and extraction sites, thereby improving the capacity and cyclability of the battery.
  • the tap density of the silicon-carbon composite particles is 0.5 g/cm 3 to 1.0 g/cm 3 .
  • the tap density of the silicon-carbon composite particles is 0.6 g/cm 3 to 0.8 g/cm 3 .
  • the tap density in this application includes any conventional concept in the art, which can be obtained by testing using instruments or methods known in the art, such as by testing with reference to standard GB/T5162-2006.
  • the present application selects a tap density of the silicon-carbon composite particles of 0.5 g/cm 3 to 1.0 g/cm 3 , which effectively improves the volume energy density of the battery while ensuring that the silicon-carbon composite particles have the above-mentioned particle size and specific surface area.
  • the tap density of the silicon-carbon composite particles includes but is not limited to any one of 0.5 g/cm 3 , 0.6 g/cm 3 , 0.7 g/cm 3 , 0.8 g/cm 3 , 0.9 g/cm 3 , 1.0 g/cm 3 or any value within the above range.
  • the compacted density of 5 tons of silicon-carbon composite particles is 0.80 g/cm 3 to 1.1 g/cm 3 .
  • the compacted density of 5 tons of silicon-carbon composite particles is 0.90 g/cm 3 to 1.05 g/cm 3 .
  • the compaction density in this application includes any conventional concept in the art, which can be obtained by testing using instruments or methods known in the art, such as limiting the cold pressing pressure to 5 tons and referring to the calculation method of GB/T 24533-2009. For example, it is measured using an electronic pressure tester (such as UTM7305). Specifically, a specific amount M of the powder sample to be tested is placed on a special pressing die (with a bottom area of S 0 ) and different pressures are set. Each pressure is maintained for 30 seconds and then released. After 10 seconds, the thickness H 0 of the powder pressed under the pressure is read on the device. The compaction density under the pressure is obtained by calculation, and the compaction density of the negative plate material under the pressure is equal to M/(H 0 ⁇ S 0 ).
  • the present application selects a 5-ton powder compaction density of 0.80 g/cm 3 to 1.1 g/cm 3 of silicon-carbon composite particles to effectively improve the capacity of the battery and enhance its practicality.
  • the compacted density of the silicon-carbon composite particles at 5 tons is any one of 0.80 g/cm 3 , 0.90 g/cm 3 , 1.0 g/cm 3 , and 1.1 g/cm 3 , or any value within the aforementioned range.
  • the powder resistivity of the silicon-carbon composite particles at 4 MPa is 1.30 ⁇ cm to 3.80 ⁇ cm.
  • the powder resistivity of the silicon-carbon composite particles in this application is different from the resistivity of the electrode. It is used to characterize the conductivity of the silicon-carbon material itself.
  • the powder resistivity in this application includes any conventional concept in the field, such as placing an appropriate amount of silicon-carbon material in the feeding cup of a resistivity tester, applying pressure, manually collecting data, recording the powder resistivity test results at different pressure points, and then taking the average value.
  • the test pressure is 4 MPa.
  • the powder resistivity of the silicon-carbon composite particles of the present application at 4 MPa is 1.30 ⁇ cm to 3.80 ⁇ cm. This indicates that the amount of silicon crystals formed in the silicon material particles of the present application is appropriate and effective. This is because, among the silicon-carbon materials, the porous carbon material has good conductivity, while the silicon material has weak conductivity.
  • the powder resistivity of the carbon composite particles selected in the present application at 4 MPa is 1.30 ⁇ cm to 3.80 ⁇ cm, which is beneficial for improving the capacity and cyclability of the battery.
  • the lithium-free capacity of the silicon-carbon composite particles is 1300mAh/g to 1500mAh/g, and the first coulombic efficiency is 77% to 81%.
  • the silicon-carbon composite particles are used as the positive electrode active material, the metal lithium sheet is used as the counter electrode, and a CR2430 button battery is assembled.
  • the charge and discharge voltage is 0.005 to 2.0V
  • the measured lithium-free capacity is 1300mAh/g to 1500mAh/g
  • the first coulombic efficiency is 77% to 81%.
  • the lithium-free capacity obtained in the test of this application is 1300mAh/g to 1500mAh/g, which matches the silicon content in the silicon-carbon material and the positional relationship of the silicon material.
  • I 1 is the peak intensity near 0.3V to 0.35V
  • I 2 is the peak intensity near 0.43V to 0.50V
  • I 1 /I 2 1.4 to 1.8.
  • the dQ/dV curve of the silicon-carbon composite particles comprises a CR2430 button cell assembled with the silicon-carbon composite particles as the positive electrode active material and a metal lithium sheet as the counter electrode, at 25°C, with a charge and discharge voltage of 0.005V to 2.0V, and is obtained by differentiating the charge and discharge capacity and the working electrode potential.
  • the differential capacity/voltage curve of the charge and discharge curve of the silicon-carbon material provided in this application under certain conditions gives peaks with certain intensities at a certain voltage.
  • the ratio between the peaks is used to indicate that the amount of silicon material particles formed in the through-holes is appropriate, and the appropriate formation amount is conducive to improving the cyclability of the battery.
  • the present application provides a silicon-carbon material, which comprises silicon-carbon composite particles with a certain particle size, specific surface area, tap density and compacted density, the silicon-carbon composite particles comprise a porous carbon material with a certain pore size, the porous carbon material comprises a certain number and pore volume of through holes, the silicon-carbon composite particles further comprise a certain number and pore volume of closed pores, nano-silicon grains are distributed along the inner wall of the through hole of the porous carbon material and form a suitable particle size, the nano-silicon grains with a suitable particle size are further stacked along the inner wall of the through hole to form a layered or sheet-like film, and the layered or sheet-like film generates a silicon carbide material layer in the area in direct contact with the inner wall of the through hole.
  • This arrangement can not only reduce the probability of its reaction with the electrolyte, but also control the expansion rate of the silicon material, because the expansion of the silicon material is not only limited by the through hole, but also by the silicon carbide material layer.
  • a carbon coating layer is formed on the outside of the porous carbon material, which can reduce the contact between the nano-silicon grains and the external air on the one hand. On the other hand, it can reduce the probability of nano-silicon grains coming into contact with the electrolyte and being oxidized.
  • the silicon-carbon material provided by this application reduces the probability of side reactions between the silicon material and the electrolyte from multiple aspects, such as forming nano-silicon grains with a certain appropriate particle size, physical isolation, and physical confinement, while controlling the expansion degree of the silicon material during the lithium ion insertion and extraction process. This reduces the probability of side reactions between the silicon material and the electrolyte, thereby improving the cyclability of the battery to a certain extent.
  • the present application provides a method for preparing a silicon-carbon material, including the following preparation process:
  • a carbon source is introduced into a porous carbon material comprising nano-silicon grains and a silicon carbide material layer to generate a silicon-carbon negative electrode material comprising a carbon coating layer.
  • the porous carbon substrate comprises carbon, oxygen, and nitrogen, and the mass ratio of carbon to oxygen and nitrogen is (94% to 97%): (2% to 4%): (1% to 2%).
  • the ash content of the porous carbon substrate is ⁇ 0.5%.
  • the porous carbon substrate of the present application is made from conventional carbon material precursors in the art.
  • the types of carbon material precursors are not particularly limited and may include, but are not limited to, asphalt-based carbon material precursors, asphaltene-based carbon material precursors, coal-based carbon material precursors, coke-based carbon material precursors, biochar-based carbon material precursors, carbon black-based carbon material precursors, oil product-based carbon material precursors, tar-based carbon material precursors, polymer-based carbon material precursors, protein-based carbon material precursors, carbohydrate-based carbon material precursors, cotton-based carbon material precursors, fat-based carbon material precursors, waste-based carbon material precursors, graphite-based carbon material precursors, melamine-based carbon material precursors, wood-based carbon material precursors, porous graphene, porous graphene oxide, activated carbon and combinations thereof.
  • Carbon material precursors of this type are easy to prepare porous carbon materials that meet the above-mentioned particle size, specific surface area, tap density and compacted density.
  • the present application discloses a method for preparing a porous carbon substrate in these embodiments, such as high-temperature sintering of the carbon material precursor to remove impurities, and then forming pores to obtain a porous carbon material.
  • the pore forming in this application includes chemical methods such as strong alkali corrosion.
  • the measurement method of the carbon element, oxygen element and nitrogen element in the porous carbon substrate of the present application includes any conventional method in the art, such as measurement according to relevant test standards.
  • the mass percentage of the carbon element in the porous carbon substrate includes any one of 94%, 95%, 96%, 97% or any one of the above-mentioned range values.
  • the mass percentage of the oxygen element in the porous carbon substrate includes any one of 2%, 3%, 4% or any one of the above-mentioned range values.
  • the mass percentage of the nitrogen element in the porous carbon substrate includes any one of 1% and 2% or any one of the above-mentioned range values.
  • the ash content in this application includes inorganic matter remaining after the porous carbon substrate is calcined at high temperature.
  • the ash content measurement method can refer to GB/T 1429-2009.
  • reaction conditions for generating a porous carbon material comprising nano-silicon grains and a silicon carbide material layer include one or more of the following:
  • the reaction temperature is 500°C to 700°C, and the silicon source is introduced for 3 hours to 42 hours; preferably, the reaction temperature is 650°C to 700°C; and the silicon source is introduced for 5 hours to 40 hours;
  • the silicon source comprises a silicon source gas and a diluent gas, wherein the volume percentage of the silicon source gas is 15% to 95%; preferably, the volume percentage of the silicon source gas is 20% to 50%; preferably, the silicon source gas comprises either or both of monosilane and disilane;
  • the ventilation volume of the silicon source is 0.3L/min to 1.4L/min.
  • the reaction temperature for generating a porous carbon material comprising nano-silicon grains and a silicon carbide material layer comprises any one of 500°C, 600°C, 650°C, 680°C, and 700°C or satisfies any one of the above-mentioned ranges.
  • the time for introducing a silicon source comprises any one of 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, 20h, 21h, 22h, 23h, 24h, 25h, 26h, 27h, 28h, 29h, 30h, 31h, 32h, 33h, 34h, 35h, 36h, 37h, 38h, 39h, 40h, 41h, and 42h or satisfies any one of the above-mentioned ranges.
  • the present application selects a reaction temperature of 500°C to 700°C and a silicon source introduction time of 3h to 42h; this facilitates the growth of silicon grains with a grain size d1 ⁇ 5nm in the through-holes, and the silicon grains are stacked along the inner wall of the through-holes to form a layered or sheet-like film.
  • the layered or sheet-like film is also prone to generate a silicon carbide material layer in the area that is in direct contact with the inner wall of the through-hole within the above-mentioned reaction temperature, and the silicon carbide material layer and the through-holes of the porous carbon material restrict the growth of the silicon grains, and finally generate nano-silicon grains with a certain suitable particle size.
  • a silicon source for forming silicon grains includes a silicon source gas and a dilution gas, wherein the silicon source gas includes, but is not limited to, monosilane, disilane, etc., and the dilution gas includes an inert gas, which includes conventional inert gases in the art, including, but not limited to, rare gases corresponding to Group 0 of the periodic table.
  • the present application discloses that the volume fraction of the silicon source gas in the silicon source includes any one of 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and 95%, or any value within the aforementioned ranges.
  • the present application discloses in some embodiments that in the process of generating a porous carbon material comprising nano-silicon grains and a silicon carbide material layer, it is also necessary to control the ventilation volume of the silicon source.
  • the ventilation volume of the silicon source can be measured using conventional measurement methods in the art, such as by setting a flow valve in the reaction equipment.
  • the ventilation volume of the silicon source includes any one of 0.3L/min, 0.4L/min, 0.5L/min, 0.6L/min, 0.7L/min, 0.8L/min, 0.9L/min, 1.0L/min, 1.1L/min, 1.2L/min, 1.3L/min, 1.4L/min or any one of the above range values.
  • the present application controls the volume percentage and ventilation volume of each component in the silicon source to control the growth rate of the silicon grains, thereby affecting the grain size of the silicon grains and the formation and thickness of the silicon carbide material layer.
  • reaction conditions for generating a silicon-carbon negative electrode material including a carbon coating layer include the following:
  • the reaction temperature is 600°C ⁇ 750°C, and the time of adding carbon source is 0.5h ⁇ 5h.
  • the preferred reaction temperature is The temperature is 650-700°C; preferably, the carbon source is introduced for 1-4 hours;
  • the carbon source comprises a carbon source gas and a diluent gas, wherein the volume fraction of the carbon source gas is 15% to 95%; preferably, the volume fraction of the carbon source gas is 20% to 40%; preferably, the carbon source gas comprises any one of methane, ethylene, acetylene, and propylene, or a combination of two or more thereof;
  • the aeration rate of the carbon source is 1.0 L/min to 3.0 L/min, preferably 1.5 L/min to 2.5 L/min.
  • the reaction temperature of the carbon coating layer of the present application includes any one of 600°C, 650°C, 700°C, 750°C or any one of the above range values.
  • the time for introducing the carbon source in the present application includes any one of 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h or any one of the above range values.
  • the carbon coating layer is formed along the outer surface of the porous carbon material and has a certain thickness. And under the reaction conditions, the silicon material with a layered or sheet-like film stacked along the inner wall of the through hole may continue to generate a silicon carbide material layer in the area directly in contact with the inner wall of the through hole.
  • the carbon source for forming the carbon coating layer includes a carbon source gas and a dilution gas.
  • the dilution gas includes an inert gas
  • the inert gas includes an inert gas conventional in the art, including but not limited to the noble gases corresponding to Group 0 of the periodic table.
  • the carbon source gas includes but is not limited to methane, ethylene, acetylene, propylene, etc.
  • the volume percentage of the carbon source gas includes but is not limited to any one of 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or any one of the above range values.
  • the ventilation rate of the carbon source includes but is not limited to any one of 1.0 L/min, 2.0 L/min, 3.0 L/min or any one of the above range values.
  • the present application generates a carbon coating layer with a thickness of 5 nm to 50 nm and a silicon carbide material layer with a thickness of less than 0.7 nm under the reaction conditions of controlling the volume percentage of the carbon source gas and the ventilation rate of the carbon source.
  • Some embodiments of the present application disclose a negative electrode sheet comprising a negative electrode current collector and a negative electrode film layer located on at least one surface of the negative electrode current collector.
  • the negative electrode film layer comprises a silicon-carbon material as a negative electrode active material, and further comprises other negative electrode active materials, such as carbonaceous materials, specifically including but not limited to one or a combination of two or more of artificial graphite, natural graphite, soft carbon, and hard carbon.
  • Artificial graphite, natural graphite, soft carbon, hard carbon, etc. include any form of material conventional in the art and include any manufacturer and model conventional in the art.
  • the negative electrode film layer also includes a conductive agent, a thickener, a binder, etc.
  • the conductive agent includes but is not limited to one or a combination of two of graphite, superconducting carbon, carbon black (such as acetylene black, Ketjen black, Super P, etc.), carbon dots, carbon nanotubes, graphene and carbon nanofibers
  • the thickener includes cellulose and its sodium salt, and cellulose includes methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, etc.
  • the binder includes but is not limited to polyvinyl alcohol, polyethylene glycol, sodium carboxymethyl cellulose, polyethylene oxide, polyacrylic acid, polyacrylamide, sodium alginate, styrene-butadiene rubber (SBR), etc.
  • the negative electrode current collector of the present application can be a metal foil or a composite current collector.
  • the metal foil can be a copper foil.
  • the composite current collector can include a polymer material base and a gold layer formed on at least one surface of the polymer material base.
  • the composite current collector can be formed by forming a metal material such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy on a polymer material substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE) and the like.
  • PP polypropylene
  • PET polyethylene terephthalate
  • PBT polybutylene terephthalate
  • PS polystyrene
  • PE polyethylene
  • the present application discloses the mass ratios of silicon-carbon materials, carbonaceous materials, conductive agents, thickeners and binders in the negative electrode film layer: (10% to 50%): (45% to 95%): (0.2% to 2.0%): (0.2% to 2.0%): (1.2% to 2.2%).
  • a positive electrode sheet which includes a positive electrode current collector and a positive electrode film layer located on at least one side of the positive electrode current collector.
  • the positive electrode film layer in the present application includes positive electrode active particles, a positive electrode conductive agent, a positive electrode binder, etc.
  • the present application does not specifically limit the specific types of the positive electrode active particles.
  • the positive electrode active particles include but are not limited to LiCoO 2 , LiNiO 2 , LiMnO 2 , LiMn 2 O 4 , LiNi 1/3 Co 1/3 Mn 1/3 O 2 (NCM111), LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523), LiNi 0.6 CO 0.2 Mn 0.2 O 2 (NCM622), LiNi 0.8 CO 0.1 Mn 0.1 O 2 (NCM811), LiNi 0.85 CO 0.15
  • the positive electrode active particles include, but are not limited to, at least one of a sodium transition metal oxide, a polyanionic compound, and a Prussian blue compound .
  • the transition metal in the sodium transition metal oxide may be one or more of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce.
  • the sodium transition metal oxide is NaxMO2 , where M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr, and Cu , and 0 ⁇ x ⁇ 1.
  • the polyanionic compound includes one or more of sodium vanadium trifluorophosphate (Na3V2(PO4)2F3 ) , sodium vanadium fluorophosphate (NaVPO4F), sodium vanadium phosphate ( Na3V2 ( PO4 ) 3 ) , Na4Fe3 ( PO4 ) 2P2O7 , and NaFePO4.
  • the Prussian blue compound is Na x M 1 M 2 (CN) 6 , wherein M 1 and M 2 are one or more of Fe, Mn, Co, Ni, Cu, Zn, Cr, Ti, V, Zr, and Ce, and wherein 0 ⁇ x ⁇ 2.
  • Positive electrode conductive agents include, but are not limited to, one or a combination of two or more of graphite, superconducting carbon, carbon black (such as acetylene black, Ketjen black, Super P, etc.), carbon dots, carbon nanotubes, graphene, and carbon nanofibers.
  • Positive electrode binders include, but are not limited to, one or a combination of two or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, styrene-butadiene rubber, polyacrylic acid, sodium polyacrylate, polyacrylamide, polyvinyl alcohol, sodium alginate, polymethacrylic acid, carboxymethyl chitosan, and the like.
  • PVDF polyvinylidene fluoride
  • PTFE polytetrafluoroethylene
  • PTFE polytetrafluoroethylene
  • the positive electrode current collector in the present application can be a metal foil or a composite current collector, wherein the metal foil can be an aluminum foil, and the composite current collector can include a polymer material base and a metal layer formed on at least one surface of the polymer material base.
  • the composite current collector can be formed by forming a metal material such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy on a polymer material substrate such as polypropylene (PP), polyethylene terephthalate (PET) or the like. It is formed on a substrate such as polyester (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.
  • an electrolyte which includes a sodium salt or a lithium salt and an organic solvent
  • the organic solvent can be an organic solvent commonly used in the art for electrolytes.
  • the organic solvent can be selected from at least one or a combination of two of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB),
  • EC ethylene carbonate
  • PC propy
  • the battery not only includes a negative electrode sheet, a positive electrode sheet and an electrolyte, but also includes a separator stacked together.
  • the stacking method includes but is not limited to conventional winding or lamination in the art.
  • the material, size, etc. of the separator include but are not limited to any conventional form in the art.
  • the material, size, etc. of the positive electrode sheet include but are not limited to any conventional form in the art.
  • the separator is arranged between the positive electrode sheet and the negative electrode sheet to play an isolating role.
  • the separator includes a substrate and also includes a functional coating provided on at least one surface of the substrate. The functional coating can be used to improve the heat resistance, mechanical strength, etc. of the separator.
  • the functional coating may also include other functional materials (such as ceramic particles, other polymers, etc.).
  • Ceramic particles include, but are not limited to, boehmite, aluminum oxide, zinc oxide, silicon oxide, titanium oxide, zirconium oxide, barium oxide, calcium oxide, magnesium oxide, nickel oxide, tin oxide, cerium oxide, yttrium oxide, hafnium oxide, aluminum hydroxide, magnesium hydroxide, silicon carbide, boron carbide, aluminum nitride, silicon nitride, boron nitride, magnesium fluoride, calcium fluoride, barium fluoride, barium sulfate, magnesium aluminum silicate, lithium magnesium silicate, sodium magnesium silicate, bentonite, hectorite, zirconium titanate, barium titanate, and the like.
  • the present application does not particularly limit the type of separator substrate; any known substrate suitable for secondary battery separators may be selected.
  • the separator substrate includes, but is not limited to, a single-layer film or a multi-layer composite film of one or more of glass fiber, non-woven fabric, polyethylene, and polypropylene.
  • This application discloses, in some embodiments, a method for preparing a silicon-carbon material, comprising the following preparation steps:
  • porous carbon substrate comprises carbon, oxygen, and nitrogen, wherein the mass ratio of carbon to oxygen and nitrogen is (94% to 97%):(2% to 4%):(1% to 2%), and the ash content of the porous carbon substrate is ⁇ 0.5%;
  • the porous carbon substrate comprises porous carbon material particles, and the pore volume, average pore diameter, number and distribution of through pores, particle size, specific surface area and tap density of the porous carbon material particles meet the following requirements:
  • Average pore diameter is 1.0nm ⁇ 5.0nm
  • volume percentage of macropores is ⁇ 15%, and the volume ratio of micropores to hollows is (40-95%):(5-50%);
  • Dv50 is 3.0 ⁇ m to 6.5 ⁇ m;
  • Dv90 is 13.5 ⁇ m to 18.5 ⁇ m;
  • Dv10 is 0.9 ⁇ m to 2.5 ⁇ m;
  • Tap density is 0.22g/cm 3 to 0.48g/cm 3 ;
  • Compacted density is 0.45g/cm 3 to 0.80g/cm 3 ;
  • the porous carbon substrate of S1 in a CVI device, introducing a silicon source for 3 hours to 42 hours, and performing a chemical vapor deposition reaction at 500° C. to 700° C. to generate a porous carbon material containing nano-silicon grains, wherein the CVI device comprises a fluidized bed and any one of a rotary kiln, a pusher furnace, or a tubular furnace; the silicon source has a ventilation rate of 0.2 L/min to 1.5 L/min, and the silicon source comprises a silicon source gas and a dilution gas, and the volume fraction of the silicon source gas is 15% to 95%; the silicon source gas comprises any one or both of monosilane and disilane;
  • a carbon source is introduced into the porous carbon material containing nano-silicon grains in S2 for 0.5h to 5h, and the reaction is carried out at 600°C to 750°C to obtain a silicon-carbon negative electrode material containing a carbon coating layer.
  • the carbon source has a ventilation rate of 1.0L/min to 3.0L/min, and the carbon source contains carbon source gas and dilution gas.
  • the volume fraction of the carbon source gas is 15% to 95%; the carbon source gas contains any one of methane, ethylene, acetylene, and propylene, or a combination of two or more.
  • Examples 1 to 16 are silicon-carbon materials obtained according to the raw materials listed in Tables 1, 2, and 3 and the process parameters listed in Table 4, and the particle size, specific surface area, etc. of the silicon-carbon materials are shown in Table 5.
  • Figure 5 is an electron micrograph of the silicon-carbon material obtained in Example 8, which was tested using a field emission scanning electron microscope (Zeiss Gemini 360) in accordance with the JY/T010-1996 standard. As shown in Figure 5 , the silicon-carbon material is composed of irregularly shaped particles of varying sizes.
  • FIG. 6 is a schematic structural diagram of the silicon-carbon composite particles of the present application.
  • the silicon-carbon composite particles 1 include a porous carbon material 1a, which has through holes, and nano-silicon grains 1b are distributed along the inner wall of the through holes of the porous carbon material 1a, while leaving some remaining closed holes 1c; a silicon carbide material layer 1d is formed inside the through holes, and one side of the silicon carbide material layer 1d is connected to the inner wall of the through hole, and the other side is connected to the nano-silicon grains 1b.
  • the remaining closed holes 1c formed on the inner wall of the through hole of the present application can be used to alleviate the partial expansion of the nano-silicon material when lithium is inserted, thereby alleviating the expansion of the silicon-carbon composite particles.
  • the silicon carbide material layer can be used to limit the degree of outward expansion of the nano-silicon particles during the process of lithium insertion and removal to reduce the effect of the reaction between the nano-silicon particles and the electrolyte.
  • Figure 7 shows that a certain amount of silicon carbide material layer has indeed formed within the silicon-carbon material.
  • Figure 7 shows an X-ray photoelectron spectroscopy analysis of the silicon-carbon material obtained in Example 8. The thickness of the silicon carbide material layer was calculated to be less than 0.7 nm.
  • FIG8 is an electron microscope image of nano-silicon grains 1b obtained by magnifying the silicon-carbon material obtained in Example 8. As shown in FIG8 , the nano-silicon grains are stacked along the inner wall of the through hole to form a layered or sheet-like film.
  • FIG9 is a transmission electron microscope image of the silicon-carbon material obtained in Example 8. It can be seen from FIG9 that a carbon coating layer is formed on the outer surface of the porous carbon material, and the thickness of the carbon coating layer is 18.4 nm.
  • a silicon-carbon material is provided.
  • the carbon substrate used to generate the silicon-carbon material is different from that of the present application.
  • the silicon grains are generated at a low temperature of 450°C.
  • the average particle size of the obtained nano-silicon grains is smaller than the average pore size of the porous carbon material and no silicon carbide material layer is generated. See Tables 1 to 5 for details.
  • a silicon-carbon material is provided.
  • the carbon substrate for generating the silicon-carbon material remains the same as that of the present application.
  • a low temperature of 450°C is used in the process of generating silicon grains, and a reaction temperature of 500°C is used in the carbon coating process, resulting in no generation of a silicon carbide material layer. See Tables 1 to 5 for details.
  • Obtain a volume particle size distribution curve for porous carbon particles or silicon-carbon composite particles Take the particle size corresponding to 50% of the cumulative volume distribution percentage as the average particle size Dv50, the particle size corresponding to 90% of the cumulative volume distribution percentage as the average particle size Dv90, and the particle size corresponding to 10% of the cumulative volume distribution percentage as the average particle size Dv10.
  • the testing instrument can be a Mastersizer 3000 laser particle size analyzer from Malvern Instruments Ltd., UK.
  • porous carbon particles or silicon-carbon composite particles were tested using nitrogen adsorption surface area analysis according to GB/T 19587-2017, and the specific surface area was calculated using the BET (Brunauer Emmett Teller) method.
  • the test instrument used was a Micromeritics TRISTAR II 3020 Surface Area and Porosity Analyzer.
  • the porous carbon particles were tested according to the GB/T 21650.2-2008 test method.
  • the test instrument can be a TRISTAR II 3020 surface area and porosity analyzer from Micromeritics, Inc., USA.
  • the dried and degassed carbon particle samples were placed in liquid nitrogen.
  • the nitrogen adsorption was measured at various test pressures, and adsorption and desorption isotherms were plotted.
  • the pore shape was determined based on the hysteresis loop, and the pore distribution was calculated using different pore models.
  • the pore size distribution curves for mesopores were fitted using the BJH model, and the pore size distribution curves for micropores were fitted using the DFT model. Statistical calculations were then performed to obtain the pore size distribution curves.
  • the pore size distribution curve of each pore is obtained, the specific surface area is obtained in 2, and the pore volume is obtained in 3.
  • the average pore size is obtained by dividing the pore volume by the specific surface area and multiplying by the model coefficient.
  • the test pressure is 4 MPa.
  • the silicon-carbon composite material, conductive carbon black, and binder polyacrylic acid prepared above were mixed in a mass ratio of 8:1:1, and deionized water was added and stirred thoroughly to form a negative electrode slurry; the negative electrode slurry was evenly coated on one surface of the negative electrode current collector copper foil, and after drying and cold pressing, a negative electrode sheet was obtained.
  • Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 20:20:60, and LiPF6 was uniformly dissolved in the above solution.
  • Fluorinated ethylene carbonate (FEC) was added as an additive to obtain an electrolyte.
  • the concentration of LiPF6 in the electrolyte was 1 mol/L, and the mass proportion of FEC in the electrolyte was 5%.
  • Polyethylene film is used as the isolation film.
  • the above-mentioned negative electrode sheet is used as the working electrode and the metallic lithium is used as the counter electrode; the negative electrode sheet, the isolation membrane and the metallic lithium are stacked in order so that the isolation membrane is between the working electrode and the counter electrode, the above-mentioned electrolyte is injected, and a CR2430 button battery is assembled.
  • the CR2430 button cell was subjected to the first charge and discharge test. At 25°C, the cell was discharged to 5 mV using a constant current of 0.05C, allowed to stand for 10 minutes, and then charged to 2.0 V using 0.1C to obtain the first discharge capacity and the first charge capacity.
  • First delithiation specific capacity first delithiation capacity/mass of active material; wherein, the first delithiation capacity is also the first discharge capacity.
  • First coulombic efficiency first discharge capacity/first charge capacity ⁇ 100%.
  • a charge and discharge curve test of the above-mentioned CR2430 button battery was plotted. At 25°C, the charge and discharge voltage was 0.005 ⁇ 2.0V, and the charge and discharge capacity and the working electrode potential were differentiated to obtain a dQ/dV curve. Specifically, a constant current of 0.05C was used to discharge to 5mV, a constant current of 50 ⁇ A was used to discharge to 5mV, and the battery was allowed to stand for 10 minutes. The battery was then charged to 2.0V at 0.1C. A curve graph showing the relationship between the differential value dQ/dV obtained by differentiating the charge and discharge capacity Q with the working electrode potential V and the working electrode potential V was plotted.
  • I1 is the peak intensity around 0.3V to 0.35V; I2 is around 0.43V to 0.50V. Peak intensity of
  • the silicon-carbon materials prepared in Examples 1 to 16 and Comparative Examples 1 and 2 were mixed with artificial graphite, a binder of styrene-butadiene rubber (SBR), a binder of polyacrylic acid (PAA), a dispersant (CMC-Na), a conductive carbon black (Super-P, SP), and carbon nanotubes (CNT) in a mass ratio of 20%:75%:2%:1%:1%:0.7%:0.3% in deionized water to form a uniform slurry.
  • the slurry was defoamed and then uniformly coated on a negative electrode current collector copper foil at a coating speed of 50 m/min and a coating weight of 130 mg/1540.25 mm 2 .
  • the temperatures of the nine-stage oven were set as 100° C./100° C./95° C./85° C./85° C./80° C./80° C./80° C./60° C.
  • the negative electrode sheet was compacted to a certain density using a cold press to obtain a negative electrode sheet.
  • the positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811)
  • the conductive agent acetylene black are stirred and dispersed in N-methylpyrrolidone in a mass ratio of 97%:1.5%:1.5% to make a positive electrode slurry, which is then coated on the positive electrode current collector aluminum foil and compacted by a cold press to obtain a positive electrode sheet.
  • a polyethylene porous membrane with a thickness of 12 ⁇ m was selected.
  • Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1, and LiPF 6 was uniformly dissolved in the above solution to obtain an electrolyte solution.
  • the concentration of LiPF 6 in the electrolyte solution was 1 mol/L.
  • the prepared negative electrode sheet, the isolation membrane, and the positive electrode sheet are stacked in order, so that the isolation membrane is placed between the positive and negative electrode sheets to play an isolation role, and are wound to obtain a bare battery cell, which is then inserted into a battery casing. After baking, liquid injection, standing, packaging, formation, and capacity division, a lithium-ion secondary battery is obtained.
  • the prepared secondary battery was charged at a constant current rate of 1C to a voltage of 4.25V at a constant temperature of 45°C. Then, it was charged at a constant voltage at 4.25V to a current of less than or equal to 0.05mA. After that, it was allowed to rest for 5 minutes. Then, it was discharged at a constant current rate of 1C to a voltage of 2.5V and allowed to rest for 5 minutes. This constituted one cycle of charge and discharge. The discharge capacity of this cycle was recorded as the discharge capacity of the secondary battery in the first cycle.
  • the secondary battery was subjected to cyclic charge and discharge tests according to the above method until the cycle capacity retention rate reached 80%, which was recorded as the cycle life CL (45°C).
  • the thickness of the negative electrode sheet of the secondary battery after the cold pressing process is recorded as h0.
  • the secondary battery is cycled 300 times. The battery is charged at a constant current rate of 1C to a voltage of 4.25V, then charged at a constant voltage of 4.25V to a current of less than or equal to 0.05mA, and then allowed to rest for 5 minutes. The cycled battery cell is disassembled in a dry room. The thickness of the negative electrode sheet after 300 cycles is recorded as h300. The expansion rate of the secondary battery sheet after 300 cycles at 45°C is ⁇ h300.
  • Comparative Example 1 Comparative Example 2
  • the presence of the silicon carbide material layer can significantly limit the expansion of the silicon material.
  • this application controls the size of nano-silicon grains to an appropriate level and reasonably matches them with the through holes, and on the other hand, limits the expansion size of silicon grains (such as setting closed holes, such as designing a silicon carbide material layer) to improve the cycle performance of the battery.

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Abstract

一种硅碳材料及其制备方法与二次电池及用电装置。硅碳材料包含硅碳复合颗粒物，该硅碳复合颗粒物包含多孔碳材料、纳米硅晶粒及碳化硅材料层，该多孔碳材料具备贯通孔，纳米硅晶粒位于贯通孔内，碳化硅材料层部分位于贯通孔壁；纳米硅晶粒的晶粒尺寸不小于多孔碳材料的平均孔径。硅碳材料用作负极极片的活性材料，有利于改善电池的循环性。

Description

硅碳材料及其制备方法与二次电池及用电装置
相关申请的交叉引用
本申请要求享有于2024年03月15日提交的名称为“硅碳材料及其制备方法与二次电池及用电装置”的中国专利申请202410302266.5的优先权，该申请的全部内容通过引用并入文本中。
技术领域
本申请涉及电池领域，具体涉及一种硅碳材料及其制备方法与二次电池及用电装置。
背景技术
硅的比容量是目前所有已知的负极材料中最高的，达到4200mAh/g，但是由于纯硅在锂离子电池中充电过程中所形成硅锂合金会让负极材料产生巨大的体积膨胀，膨胀率达到300％，从而使负极材料坍塌粉化，破坏了电池的循环性能，而硅碳复合可以有效的降低负极材料的体积效应。当前，现有的硅碳负极材料的循环性能得到一定改善，但仍需进一步优化，以满足动力电池的需求。
发明内容
鉴于上述问题，本申请提供一种硅碳材料及其制备方法与二次电池及用电装置，其有利于改善电池的循环性。
第一方面，本申请提供了一种硅碳材料，包括：硅碳复合颗粒物，硅碳复合颗粒物包括：
多孔碳材料：具备贯通孔；
纳米硅晶粒：位于贯通孔内；纳米硅晶粒的晶粒尺寸不小于多孔碳材料的平均孔径；
碳化硅材料层：至少部分位于贯通孔壁。
本申请提供的硅碳材料包含硅碳复合颗粒物，该硅碳复合颗粒物包含多孔碳材料，该多孔碳材料具备贯通孔，这里的贯通孔包含用于沉积硅材料的大孔、中孔和微孔等，硅材料沉积在多孔碳材料的贯通孔内，一方面贯通孔能够限制硅材料膨胀，另一方面，由于贯通孔连接着封闭孔，对电解液具备一定程度的物理隔绝，也能降低硅材料与电解液直接接触发生副反应的概率。本申请选择在贯通孔内形成有具备一定适宜粒径的纳米硅晶粒，该适宜粒径的纳米硅晶粒堆叠形成纳米硅颗粒，该纳米硅颗粒进一步沿贯通孔内壁面堆叠形成层状或片状膜，该层状或片状膜与贯通孔内壁直接接触的地方生成有碳化硅材料层。该布置方式既能够降低其与电解液发生反应的概率，还能控制硅材料的膨胀率，这是因为，硅材料的膨胀不仅受到贯通孔的限制，还受到碳化硅材料层的限制。故本申请提供的硅碳材料从多个层面，如形 成具备一定适宜粒径的纳米硅晶粒、物理隔绝、物理限制等方式，在控制硅材料脱嵌锂离子过程中膨胀程度前提下，降低硅材料与电解液之间发生副反应的概率，在一定程度上改善了电池的循环性。
在本申请的一些实施方式中，纳米硅晶粒的晶粒尺寸为d1，多孔碳材料的平均孔径为d2，满足：d1/d2＝1～15。
在本申请的一些实施方式中，纳米硅晶粒的晶粒尺寸为d1，多孔碳材料的平均孔径为d2，满足：d1/d2＝2～10。
在本申请的一些实施方式中，纳米硅晶粒的晶粒尺寸为d1，d1≥5nm；
和/或；
多孔碳材料的平均孔径为d2，d2为1.0nm～5.0nm。
在本申请的一些实施方式中，纳米硅晶粒的晶粒尺寸为d1，d1为5nm～20nm；
和/或；
多孔碳材料的平均孔径为d2，d2为1.5nm～5.0nm。
在本申请的一些实施方式中，硅碳复合颗粒物包括封闭孔，封闭孔的孔容小于贯通孔的孔容。
在本申请的一些实施方式中，硅碳复合颗粒物包括封闭孔，封闭孔的孔容为V1，贯通孔的孔容为V2，满足：V2/V1＝5～24。
在本申请的一些实施方式中，硅碳复合颗粒物包括封闭孔，封闭孔的孔容为V1，贯通孔的孔容为V2，满足：V2/V1＝7～16。
在本申请的一些实施方式中，封闭孔的孔容为V1，V1为0.04cm3/g～0.16cm3/g；
和/或；
贯通孔的孔容为V2，V2为0.3cm3/g～1.5cm3/g。
在本申请的一些实施方式中，贯通孔包含微孔、中孔和大孔，基于贯通孔的总体积，微孔、中孔和大孔之间的体积比为(40％～95％):(5％～50％):(0～15％)。
在本申请的一些实施方式中，碳化硅材料层位于贯通孔与纳米硅晶粒之间，其中，碳化硅材料层的一侧连接贯通孔内壁，另一侧连接纳米硅晶粒。
在本申请的一些实施方式中，碳化硅材料层的厚度＜0.7nm。
在本申请的一些实施方式中，硅碳材料还包括碳包覆层，所述碳包覆层沿所述多孔碳材料的外侧表面设置。该碳包覆层一方面可减少纳米硅晶粒与外界空气接触进而被氧化的概率，另一方面可降低纳米硅晶粒与电解液接触反应的概率。
在本申请的一些实施方式中，多孔碳材料包含多孔碳颗粒物，多孔碳颗粒物满足如下条件：
(1.1)多孔碳颗粒物的体积分布粒径满足：Dv50为3.0μm～6.5μm；Dv90为13.5μm～18.5μm；Dv10为0.9μm～2.5μm；
(1.2)多孔碳颗粒物的比表面积为900m2/g～1550m2/g；
(1.3)多孔碳颗粒物的振实密度为0.22g/cm3～0.48g/cm3；
(1.4)多孔碳颗粒物的5吨粉体压实密度为0.45g/cm3～0.80g/cm3。
在本申请的一些实施方式中，多孔碳材料包含多孔碳颗粒物，多孔碳颗粒物满足如下至少一种：
(2.1)多孔碳颗粒物的体积分布粒径满足：Dv50为3.5μm～6.0μm；Dv90为14.0μm～18.0μm；Dv10为1.0μm～2.0μm；
(2.2)多孔碳颗粒物的比表面积为1000m2/g～1500m2/g；
(2.3)多孔碳颗粒物的振实密度为0.25g/cm3～0.45g/cm3；
(2.4)多孔碳颗粒物的5吨粉体压实密度为0.50g/cm3～0.75g/cm3。
在本申请的一些实施方式中，基于硅碳材料的总质量，硅碳材料中硅元素的质量百分比含量为w硅，满足：w硅为38.0％～48.0％。
在本申请的一些实施方式中，硅碳复合颗粒物满足如下条件：
(3.1)硅碳复合颗粒物的体积分布粒径满足：(Dv90-Dv10)/Dv50为1.2～2.8；
(3.2)硅碳复合颗粒物的比表面积为3.0m2/g～12.0m2/g；
(3.3)硅碳复合颗粒物的振实密度为0.5g/cm3～1.0g/cm3；
(3.4)硅碳复合颗粒物的5吨粉体压实密度为0.80g/cm3～1.1g/cm3。
在本申请的一些实施方式中，硅碳复合颗粒物满足如下至少一种：
(4.1)硅碳复合颗粒物的体积分布粒径满足：Dv50为3.5μm～9.0μm；Dv90为14.0μm～21.0μm；Dv10为0.9μm～3.0μm；
(4.2)硅碳复合颗粒物的比表面积为5.0m2/g～10.0m2/g；
(4.3)硅碳复合颗粒物的振实密度为0.6g/cm3～0.8g/cm3；
(4.4)硅碳复合颗粒物的5吨粉体压实密度为0.90g/cm3～1.05g/cm3。
在本申请的一些实施方式中，硅碳复合颗粒物的性能满足如下：
硅碳复合颗粒物在4Mpa下的粉末电阻率为1.30Ω·cm～3.80Ω·cm；
和/或；
硅碳复合颗粒物的脱锂比容量为1300mAh/g～1500mAh/g，首次库伦效率为77％～81％；
和/或；
硅碳复合颗粒物的dQ/dV曲线中，I1为0.3V～0.35V附近的峰强度；I2为0.43V～0.50V附近的峰强度；满足：I1/I2＝1.4～1.8；硅碳复合颗粒物的dQ/dV曲线包含以硅碳复合颗粒物为正极活性材料，金属锂片为对电极，组装形成CR2430型扣式电池，25℃下，充放电电压为0.005V～2.0V，对充放电容量，工作电极电势进行微分处理得到。
本申请的第二方面是提供一种第一方面所述的硅碳负极材料的制备方法，包括：
提供多孔碳基材；
向多孔碳基材中通入硅源，生成包含纳米硅晶粒及碳化硅材料层的多孔碳材料；
向包含纳米硅晶粒及碳化硅材料层的多孔碳材料中通入碳源，生成包含碳包覆层的硅碳材料。
在本申请的一些实施方式中，生成包含纳米硅晶粒及碳化硅材料层的多孔碳材料的反应条件如下：
(5.1)反应温度为500℃～700℃，通入硅源时间为3h～42h；
(5.2)硅源包含硅源气体与稀释气体，硅源气体的体积分数为15％～95％；硅源气体包含甲硅烷，乙硅烷中的任一种或两种；
(5.3)硅源的通气量为0.2L/min～1.5L/min。
在本申请的一些实施方式中，多孔碳基材包含碳元素、氧元素及氮元素，碳元素与氧元素及氮元素的质量比为(94％～97％):(2％～4％):(1％～2％)；
和/或；多孔碳基材的灰分≤0.5％。
本申请的第三方面是提供一种二次电池，该二次电池包含负极极片，该负极极片包含第一方面所述的硅碳材料或第二方面所述的制备方法制得的硅碳材料。
本申请的第四方面是提供一种用电装置，该用电装置包含第三方面所述的二次电池。
上述说明仅是本申请技术方案的概述，为了能够更清楚了解本申请的技术手段，而可依照说明书的内容予以实施，并且为了让本申请的上述和其它目的、特征和优点能够更明显易懂，以下特举本申请的具体实施方式。
附图说明
通过阅读下文优选实施方式的详细描述，各种其他的优点和益处对于本领域普通技术人员将变得清楚明了。附图仅用于示出优选实施方式的目的，而并不认为是对本申请的限制。而且在整个附图中，用相同的附图标记表示相同的部件。在附图中：
图1为本申请一些实施例的电池结构示意图；
图2为本申请一些实施例电池的分解结构示意图；
图3为本申请一些实施例的车辆结构示意图；
图4为本申请一些实施例的电池包的结构示意图；
图5为本申请一些实施例制得硅碳材料的电镜图；
图6为本申请一些实施例制得硅碳材料的结构示意图；
图7为本申请一些实施例制得硅碳材料的X射线光电子能谱分析图谱。
图8为本申请一些实施例制得硅碳材料的进一步放大电镜图。
图9为本申请一些实施例制得硅碳材料碳包覆层的透射电镜图。
图10为本申请一些实施例制得硅碳材料的X射线衍射图谱；
图11为本申请一些实施例制得硅碳材料的放电曲线的dQ/dV曲线图。
具体实施方式中的附图标号如下：
10000、车辆；
1000、电池；2000、控制器；3000、马达；
100、电池单体；
200、箱体；210、第一部分；220、第二部分；
10、二次电池；
101、壳体；102、电极组件；103、盖板；
1、硅碳复合颗粒物；1a、多孔碳材料；1b、纳米硅晶粒；1c、剩余封闭孔；
1d、碳化硅材料层。
具体实施方式
以下，适当地参照附图详细说明具体公开了本申请的硅碳材料及其制备方法与二次电池及用电装置的实施方式。但是会有省略不必要的详细说明的情况。例如，有省略对已众所周知的事项的详细说明、实际相同结构的重复说明的情况。这是为了避免以下的说明不必要地变得冗长，便于本领域技术人员的理解。此外，附图及以下说明是为了本领域技术人员充分理解本申请而提供的，并不旨在限定权利要求书所记载的主题。
本申请所公开的“范围”以下限和上限的形式来限定，给定范围是通过选定一个下限和一个上限进行限定的，选定的下限和上限限定了特别范围的边界。这种方式进行限定的范围可以是包括端值或不包括端值的，并且可以进行任意地组合，即任何下限可以与任何上限组合形成一个范围。例如，如果针对特定参数列出了60～120和80～110的范围，理解为60～110和80～120的范围也是预料到的。此外，如果列出的最小范围值1和2，和如果列出了最大范围值3，4和5，则下面的范围可全部预料到：1～3、1～4、1～5，2～3，2～4和2～5。在本申请中，除非有其他说明，数值范围“a～b”表示a到b之间的任意实数组合的缩略表示，其中a和b都是实数。例如数值范围“0～5”表示本文中已经全部列出了“0～5”之间的全部实数，“0～5”只是这些数值组合的缩略表示。另外，当表述某个参数为≥2的整数，则相当于公开了该参数为例如整数2、3、4、5、6、7、8、9、10、11、12等。
如果没有特别的说明，本申请的所有实施方式以及可选实施方式可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有技术特征以及可选技术特征可以相互组合形成新的技术方案。
如果没有特别的说明，本申请的所有步骤可以顺序进行，也可以随机进行，优选是顺序进行的。例如，所述方法包括步骤(a)和(b)，表示所述方法可包括顺序进行的步骤(a)和(b)，也可以包括顺序进行的步骤(b)和(a)。例如，所述提到所述方法还可包括步骤(c)，表示步骤(c)可以任意顺序加入到所述方法，例如，所述方法可以包括步骤(a)、(b)和(c)，也可包括步骤(a)、(c)和(b)，也可以包括步骤(c)、(a)和(b)等。
如果没有特别的说明，本申请所提到的“包括”和“包含”表示开放式，也可以是封闭式。例如，所述“包括”和“包含”可以表示还可以包括或包含没有列出的其他组分，也可以仅包括或包含列出的组分。
如果没有特别的说明，在本申请中，术语“或”是包括性的。举例来说，短语“A或B”表示“A，B，或A和B两者”。更具体地，以下任一条件均满足条件“A或B”：A为真(或存在)并且B为假(或不存在)；A为假(或不存在)而B为真(或存在)；或A和B都为真(或存在)。
如果没有特别的说明，在本申请中，术语“第一”“第二”等仅用于区别不同对象，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、特定顺序或主次关系。
如果没有特别的说明，在本申请中，术语“多个”指的是两个以上(包括两个)，同理，“多组”指的是两组以上(包括两组)，“多片”指的是两片以上(包括两片)。
如果没有特别的说明，技术术语“中心”“纵向”“横向”“长度”“宽度”“厚度”“上”“下”“前”“后”“左”“右”“竖直”“水平”“顶”“底”“内”“外”“顺时针”“逆时针”“轴向”“径向”“周向”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本申请实施例和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本申请实施例的限制。
硅的比容量是目前所有已知的负极材料中最高的，达到4200mAh/g，但是由于纯硅在锂离子电池中充电过程中所形成硅锂合金会让负极材料产生巨大的体积膨胀，膨胀率达到300％，从而使负极材料坍塌粉化，破坏了电池的安全性和循环性能，而硅碳复合可以有效的降低负极材料的体积效应。具体的，硅碳复合包含了将纳米硅与碳材料混合，通过降低硅基材料粒径至纳米级别，可以拥有更多的空隙，用于缓冲硅在脱嵌锂离子过程中产生的应力和形变。然而随着硅基材料粒径的减小，其更易与缓慢渗透至硅基材料表面的电解液发生副反应进而导致循环衰减加快。
为解决上述问题，现有技术公开了包括开发新的电解液，或在硅基材料表面形成物理隔绝等方式以降低发生副反应的概率，然而这些改进方式并不理想。
如果能够在一定程度上增加硅基材料的粒径，但又不至于无限制增大，在控制硅基材料脱嵌锂离子过程中膨胀程度前提下，降低硅基材料与电解液之间发生副反应的概率，则能在一定程度上改善电池的循环性。
基于以上考虑，为解决电池中由于硅基材料与电解液发生副反应进而导致循环衰减加快的技术问题，根据上述设计理念并进行相关的实验探究得到了一种硅碳材料及其制备方法与二次电池及用电装置。
首先，本申请公开了一种硅碳材料，该硅碳材料包含硅碳复合颗粒物，该硅碳复合颗粒物包含多孔碳材料、纳米硅晶粒、碳化硅材料层及碳包覆层，该多孔碳材料具备贯通孔，纳米硅晶粒位于贯通孔内，碳化硅材料层位于贯通孔与纳米硅晶粒之间；纳米硅晶粒的晶粒尺寸不小于多孔碳材料的平均孔径；碳包覆层沿多孔碳材料的外侧表面设置。
本申请提供的硅碳材料包含硅碳复合颗粒物，该硅碳复合颗粒物包含多孔碳材料，该多孔碳材料具备贯通孔，这里的贯通孔包含用于沉积硅材料的大孔、中孔和微孔等，硅材料沉积在多孔碳材料的贯通孔内，一方面贯通孔能够限制硅材料膨胀，另一方面，由于贯通孔对电解液一定程度的物理隔绝，也能降低硅材料与电解液直接接触发生副反应的概率。本申请选择在贯通孔内形成有具备一定适宜粒径的纳米硅晶粒，该适宜粒径的纳米硅晶粒堆叠形成纳米硅颗粒，该纳米硅颗粒进一步沿贯通孔内壁面堆叠形成层状或片状膜，该层状或片状膜与贯通孔内壁直接接触的区域生成有碳化硅材料层。该布置方式既能够降低其与电解液发生反应的概率，还能控制硅材料的膨胀率，这是因为，硅材料的膨胀不仅受到贯通孔的限制，还受到碳化硅材料层的限制。此外，在多孔碳材料外部形成有碳包覆层，该碳包覆层一方面可减少纳米硅晶粒与外界空气接触进而被氧化的概率，另一方面可降低纳米硅晶粒与电解液接触反应的概率。故本申请提供的硅碳材料从多个层面，如形成具备一定适宜粒径的纳米硅晶粒、物理隔绝、物理限制等方式，在控制硅材料脱嵌锂离子过程中膨胀程度前提下，降低硅材料与电解液之间发生副反应的概率，在一定程度上改善了电池的循环性。
本申请提供的硅碳材料用于制成负极极片并应用于电池中，通过改善电池的性能如在一定容量下提高循环性，进而增加用户体验。该电池可以包括外包装。该外包装可用于封装上述电极组件及电解液。电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。电池的外包装也可以是软包，例如袋式软包。软包的材质可以是塑料，作为塑料，可列举出聚丙烯、聚对苯二甲酸丁二醇酯以及聚丁二酸丁二醇酯等。
本申请对电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。例如，图1是作为一个示例的方形结构的二次电池10。
根据本申请的一些实施例中，参照图2，外包装可包括壳体101和盖板103。 其中，壳体101可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体101具有与容纳腔连通的开口，盖板103能够盖设于开口，以封闭容纳腔。正极极片、负极极片和隔离膜可经卷绕工艺或叠片工艺形成电极组件102。电极组件102封装于容纳腔内。电解液浸润于电极组件102中。二次电池10所含电极组件102的数量可以为一个或多个，本领域技术人员可根据具体实际需求进行选择。
本申请提供的电极组件应用于电池中有利于改善电池性能，该电池可以用作用电装置的电源，也可以用作用电装置的能量存储单元，该用电装置应用于动力领域，例如移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等，但不限于上述领域。
本申请的一些实施例为了方便说明，以用电装置为车辆为例进行说明。
请参照图3，图3为本申请一些实施例提供的车辆10000的结构示意图。车辆10000可以为燃油汽车、燃气汽车或新能源汽车，新能源汽车可以是纯电动汽车、混合动力汽车或增程式汽车等。车辆10000的内部设置有电池1000，电池1000可以设置在车辆10000的底部或头部或尾部。电池1000可以用于车辆10000的供电，例如，电池1000可以作为车辆10000的操作电源。车辆10000还可以包括控制器2000和马达3000，控制器2000用来控制电池1000为马达3000供电，例如，用于车辆10000的启动、导航和行驶时的工作用电需求。
在本申请一些实施例中，电池1000不仅可以作为车辆10000的操作电源，还可以作为车辆10000的驱动电源，代替或部分地代替燃油或天然气为车辆10000提供驱动动力。
请参照图4，图4为本申请一些实施例提供的电池1000的爆炸图。电池1000包括箱体200和电池单体100，常规的电池单体包含一次电池或二次电池，本申请具体保护了二次电池，电池单体100容纳于箱体200内。其中，箱体200用于为电池单体100提供容纳空间，箱体200可以采用多种结构。
在一些实施例中，箱体200可以包括第一部分210和第二部分220，第一部分210与第二部分220相互盖合，第一部分210和第二部分220共同限定出用于容纳二次电池100的容纳空间。第二部分220可以为一端开口的空心结构，第一部分210可以为板状结构，第一部分210盖合于第二部分220的开口侧，以使第一部分210与第二部分220共同限定出容纳空间；第一部分210和第二部分220也可以是均为一侧开口的空心结构，第一部分210的开口侧盖合于第二部分220的开口侧。当然，第一部分210和第二部分220形成的箱体200可以是多种形状，比如，圆柱体、长方体等。
在电池1000中，电池单体100可以是多个，多个电池单体100之间可串联或 并联或混联，混联是指多个电池单体100中既有串联又有并联。多个电池单体100之间可直接串联或并联或混联在一起，再将多个电池单体100构成的整体容纳于箱体200内；当然，电池1000也可以是多个电池单体100先串联或并联或混联组成电池1000模块形式，多个电池1000模块再串联或并联或混联形成一个整体，并容纳于箱体200内。电池1000还可以包括其他结构，例如，该电池1000还可以包括汇流部件，用于实现多个电池单体100之间的电连接。
硅碳材料
本申请在一些实施例中公开了硅碳材料，该硅碳材料包含硅碳复合颗粒物，该硅碳复合颗粒物包含多孔碳材料、纳米硅晶粒、碳化硅材料层及碳包覆层，该多孔碳材料具备贯通孔，纳米硅晶粒位于贯通孔内，碳化硅材料层位于贯通孔壁；纳米硅晶粒的晶粒尺寸不小于多孔碳材料的平均孔径。
本申请中的硅碳复合颗粒物包含了主要由硅元素与碳元素复合形成的颗粒物，这里的复合方式包含了本领域常规的任意复合形式
本申请中的纳米硅晶粒包含了粒径为纳米级别的硅晶粒，该纳米硅晶粒的形成方式包含但不限于化学气相沉积、物理气相沉积或原子层沉积等。
本申请中的贯通孔包含了与外界保持相通的通孔，比如用于沉积硅材料的大孔、中孔和微孔等，纳米硅晶粒沿该贯通孔的内壁面分布并堆叠形成具备层状或片状膜的硅材料。
本申请中纳米硅晶粒的晶粒尺寸不小于多孔碳材料的平均孔径。本申请多孔碳材料的平均孔径包含了采用本领域常规的任意方法测得。比如采用本领域常规的测试仪器测试各孔的分布情况并经统计得到各孔的数量，然后通过数学函数计算得到平均孔径。还可以采用吸附和脱附等温线得到多孔碳材料的孔容与比表面积，依据相关孔的模型，拿孔容除以比表面积乘以模型系数即为平均孔径；比如采用测试仪器为ASAP2460-物理吸附分析仪，将烘干脱气处理后的多孔碳材料样品置于液氮中，调节不同试验压力，分别测出对氮气的吸附量，并绘出吸附和脱附等温线，然后根据吸附和脱附等温线得到多孔碳材料的孔容与比表面积，进而计算出多孔碳材料的平均孔径。本申请的纳米硅晶粒包含了粒径为纳米级别的硅晶粒，且该纳米级别的硅晶粒的晶型包含了本领域常规的晶体结构。该纳米硅晶粒的晶粒尺寸包含了采用测试仪器如x射线衍射仪测定粒径分布然后经统计获得或通过透射电子显微镜进行表征然后经统计获得。
本申请纳米硅晶粒的晶粒尺寸不小于多孔碳材料的平均孔径，在本申请的一些实施例中，纳米硅晶粒的晶粒尺寸为d1，多孔碳材料的平均孔径为d2，满足d1≥d2。这是因为纳米硅晶粒沿多孔碳材料的贯通孔内部分布及堆叠，故多孔碳材料的平均孔径大小并不影响纳米硅晶粒的堆叠过程，但能限制纳米硅晶粒堆叠的结果， 即限制硅材料的膨胀。本申请选择具备一定适宜粒径的纳米硅晶粒分布于多孔碳材料的贯通孔内，在控制硅材料脱嵌锂离子过程中膨胀程度前提下，降低了硅材料与电解液之间发生副反应的概率，在一定程度上还改善了电池的循环性。
本申请碳化硅材料层的形成受制备条件影响，比如硅晶粒生长过程中，靠近贯通孔内壁的硅晶粒易与壁面接触并反应生成碳化硅材料层，该碳化硅材料层的硬度要大于硅材料，在硅材料发生膨胀时能够限制其向外膨胀的程度。故本申请提供的硅碳材料从多个层面，如形成具备一定适宜粒径的纳米硅晶粒、物理隔绝、物理限制等方式，在控制硅材料脱嵌锂离子过程中膨胀程度前提下，降低硅材料与电解液之间发生副反应的概率，在一定程度上改善了电池的循环性。
在本申请的一些实施例中，纳米硅晶粒的晶粒尺寸d1与多孔碳材料的平均孔径d2，满足：d1/d2＝1～15。
在本申请的一些实施例中，纳米硅晶粒的晶粒尺寸d1与多孔碳材料的平均孔径d2，满足：d1/d2＝2～10。
本申请提供的纳米硅晶粒的晶粒尺寸d1也不能无限制的比多孔碳材料的平均孔径d2大，否则既不利于纳米硅晶粒的形成，又可能影响电池的性能，如锂离子需要从具备相对较大尺寸的硅材料中完成脱嵌过程进而影响电池的倍率性等。本申请选择控制d1/d2＝1～15，一方面方便纳米硅晶粒在多孔碳材料的贯通孔内高效形成，另一方面又不影响电池的综合性能，比如循环性、倍率性等。本申请在这些实施例中给出了纳米硅晶粒的晶粒尺寸d1与多孔碳材料的平均孔径d2之间的关系满足包含但不限于d1/d2＝1，d1/d2＝2，d1/d2＝3，d1/d2＝4，d1/d2＝5，d1/d2＝6，d1/d2＝7，d1/d2＝8，d1/d2＝9，d1/d2＝10，d1/d2＝11，d1/d2＝12，d1/d2＝13，d1/d2＝14，d1/d2＝15。
在本申请的一些实施例中，纳米硅晶粒的晶粒尺寸d1≥5nm。
在本申请的一些实施例中，纳米硅晶粒的晶粒尺寸d1为5nm～20nm。
在本申请的一些实施例中，纳米硅晶粒的晶粒尺寸d1为5nm～15nm。
本申请中的纳米硅晶粒包含了硅晶粒的尺寸为纳米级别，且该纳米级别的硅晶粒的晶型包含了本领域常规的晶体结构。该纳米硅晶粒的晶粒尺寸包含了采用本领域公知的X射线衍射图谱，通过Scherrer公式计算获得，该硅晶粒尺寸为统计尺寸。
本申请选择纳米硅晶粒的晶粒尺寸≥5nm，这是因为硅晶粒的晶粒尺寸不能太小，否则容易增大副反应概率。具备该尺寸的硅晶粒既方便高效的形成于贯通孔内，同时还能减小其与电解液发生反应的概率。与此同时，纳米硅晶粒的晶粒尺寸也不能无限制增大，一方面受限于制备工艺，另一方面，具备较大晶粒尺寸的纳米硅晶粒既增大了硅材料脱嵌锂离子过程中膨胀程度及概率，又不利于锂离子脱嵌锂过程中的扩散。故本申请选择纳米硅晶粒的晶粒尺寸d1为5nm～20nm。本申请在这些实施例中公开了纳米硅晶粒的晶粒尺寸d1包含但不限于5nm、6nm、7nm、8nm、9nm、10nm、 11nm、12nm、13nm、14nm、15nm、16nm、17nm、18nm、19nm、20nm中的任一种或满足上述范围值中的任一种。
在本申请的一些实施例中，多孔碳材料的平均孔径d2为1.0nm～5.0nm。
在本申请的一些实施例中，多孔碳材料的平均孔径d2为1.5nm～5.0nm。
本申请选择平均孔径为1.0nm～5.0nm的多孔碳材料，方便硅材料在贯通孔内高效的形成，还方便后续对硅材料膨胀的限制。
本申请在这些实施例中公开了多孔碳材料的平均孔径为1.0nm、1.5nm、2.0nm、3.0nm、4.0nm、4.5nm、5.0nm中的任一种或满足上述范围值中的任一种。
在本申请的一些实施例中，硅碳复合颗粒物包括封闭孔，封闭孔的孔容小于贯通孔的孔容。
本申请的封闭孔包含了硅碳复合颗粒中不与外界保持相通的孔，该封闭孔包含多孔碳材料自身具备的封闭孔，还包含纳米硅晶粒形成于贯通孔内后在贯通孔内形成的一定数量的封闭孔隙，该部分封闭孔在上述贯通孔、碳化硅材料层对硅材料膨胀限制的基础上，可进一步为硅材料膨胀提供缓释空间，从而缓解硅碳材料的膨胀。
在本申请的一些实施例中，封闭孔的孔容为V1，贯通孔的孔容为V2，满足V1＜V2。
本申请的孔容又称为孔体积，其中，封闭孔的孔容V1可采用计算公式(I)并结合相关的测试结果得到：V1＝1/ρ真-1/(w硅×ρ硅+w碳×ρ碳)；公式(I)。
在公式(I)中，ρ真为硅碳材料的测试真密度，w硅为硅碳材料中硅的质量百分比含量，w碳为硅碳材料中碳的质量百分比含量，ρ硅为硅的理论真密度，ρ碳为碳的理论真密度。其中，w硅包含了基于硅碳材料的总质量，硅元素的质量百分比含量，而w碳包含了基于硅碳材料的总质量，碳元素的质量百分比含量。ρ硅为硅的理论真密度，其具体数值为2.34g/cm3，ρ碳为碳的理论真密度，其具体数值为2.26g/cm3。ρ真为硅碳材料的测试真密度，可以参照GB/T24586-2009进行测试得到。本申请多孔碳材料贯通孔的孔容也可以是多孔碳材料的孔容，即多孔碳材料的孔体积，其包含了可以采用本领域公知的仪器及方法进行测定，例如可以参照GB/T21650.2-2008进行测试。测试仪器可以为美国Micromeritics公司的TRISTAR II 3020型比表面积与孔隙度分析仪等。本申请的贯通孔主要用来沉积硅材料，而封闭孔用于提供硅材料膨胀时的缓释空间，使封闭孔占据一定孔体积以减少纳米硅晶粒在多孔碳材料内部的形成量，但又不至于影响纳米硅晶粒作为负极活性材料的使用量。故本申请选择封闭孔的孔容V1小于贯通孔的孔容V2。
在本申请的一些实施例中，封闭孔的孔容V1与贯通孔的孔容V2满足：
V2/V1＝5～24。
本申请通过选择V2/V1＝5～24以探究得到具备适宜尺寸及形成量的纳米硅晶 粒，在不影响电池容量等前提下，通过减少纳米硅晶粒与电解液之间的反应以改善电池的循环性。
在本申请的一些实施例中，封闭孔的孔容V1与贯通孔的孔容V2满足：
V2/V1＝7～16。
本申请通过选择V2/V1＝7～16以进一步改善电池的循环性。
本申请在一些实施例中还具体限定了V2/V1＝5、V2/V1＝6、V2/V1＝7、V2/V1＝8、V2/V1＝9、V2/V1＝10、V2/V1＝11、V2/V1＝12、V2/V1＝13、V2/V1＝14、V2/V1＝15、V2/V1＝16、V2/V1＝17、V2/V1＝18、V2/V1＝19、V2/V1＝20、V2/V1＝21、V2/V1＝22、V2/V1＝23、V2/V1＝24中的任一种或满足上述范围值中的任一种。
本申请在一些实施例中给出了封闭孔孔容的具体数值，V1为0.04cm3/g～0.16cm3/g。
本申请在一些实施例中还进一步给出了封闭孔孔容的具体数值，V1为0.05cm3/g～0.15cm3/g。
本申请选择封闭孔孔容V1为0.04cm3/g～0.16cm3/g，其既可以占据一定孔体积，进而限制硅材料在多孔碳材料内部的形成量，又能缓冲一部分因硅材料在脱嵌锂过程中的膨胀变大而导致的硅材料膨胀恶化。
本申请在这些实施例中给出了封闭孔孔容V1包含但不限于0.04cm3/g、0.05cm3/g、0.06cm3/g、0.07cm3/g、0.08cm3/g、0.09cm3/g、0.1cm3/g、0.11cm3/g、0.12cm3/g、0.13cm3/g、0.14cm3/g、0.15cm3/g、0.16cm3/g中的任一种或满足上述范围值中的任一种。
在本申请的一些实施例中，贯通孔的孔容V2为0.3cm3/g～1.5cm3/g。
本申请中贯通孔的孔容影响硅碳材料的抗压能力，还影响硅材料的形成量及硅晶粒尺寸，故本申请选择贯通孔的孔容V2为0.3cm3/g～1.5cm3/g。
在本申请的一些实施例中，贯通孔的孔容V2进一步为0.6cm3/g～1.2cm3/g。
本申请在这些实施例中选择贯通孔的孔容V2包含但不限于0.3cm3/g、0.4cm3/g、0.5cm3/g、0.6cm3/g、0.7cm3/g、0.8cm3/g、0.9cm3/g、1.0cm3/g、1.1cm3/g、1.2cm3/g、1.3cm3/g、1.4cm3/g、1.5cm3/g中的任一种或满足上述范围值中的任一种。
在本申请的一些实施例中，贯通孔包含微孔、中孔和大孔，基于贯通孔的总体积，微孔、中孔和大孔之间的体积比为(40％～95％):(5％～50％):(0～15％)，优选为(45％～95％):(5％～45％):(0～10％)。
本申请的微孔、中孔和大孔包含了本领域常规的含义，比如微孔的孔径小于2nm，中孔又称为介孔，其孔径为2nm～50nm，大孔的孔径大于50nm。本申请包含了采用本领域常规的测试仪器测试各孔的分布情况，比如采用测试仪器为ASAP2460-物理吸附分析仪，将烘干脱气处理后的多孔碳材料样品(多孔碳基材) 置于液氮中，调节不同试验压力，分别测出对氮气的吸附量，并绘出吸附和脱附等温线。根据滞后环的形状确定孔的形状，按不同的孔模型计算孔分布，使用BJH模型拟合中孔及大孔的孔径分布曲线，使用DFT模型拟合微孔的孔径分布曲线。
本申请中由于孔径影响形成的硅材料的粒径及形成量，故本申请选择微孔、中孔和大孔之间的体积比为(40％～95％):(5％～50％):(0～15％)。在这些实施例中，大孔的体积百分数包含但不限于1％、2％、3％、4％、5％、6％、7％、8％、9％、10％、15％中的任一种或满足上述范围值中的任一种。本申请在一些实施例中还公开了不包含大孔。微孔的体积百分数包含但不限于40％、45％、50％、55％、60％、65％、70％、75％、80％、85％、90％、95％中的任一种或满足上述范围值中的任一种。中孔的体积百分数包含但不限于5％、10％、15％、20％、25％、30％、35％、40％、45％、50％中的任一种或满足上述范围值中的任一种。
在本申请的一些实施例中，硅碳材料还包含碳化硅材料层，碳化硅材料层形成于至少部分贯通孔内壁上，碳化硅材料层的一侧连接贯通孔内壁，另一侧连接纳米硅晶粒。在这些实施例中，碳化硅材料层的厚度＜0.7nm。进一步优选＜0.4nm。
本申请碳化硅材料层的形成受制备条件影响，比如硅晶粒生长过程中，靠近贯通孔内壁的硅晶粒易与壁面接触并反应生成碳化硅材料层，该碳化硅材料层的硬度要大于硅材料，在硅材料发生膨胀时能够限制其向外膨胀的程度。且碳化硅材料层的厚度不易太厚，这是由于碳化硅材料层的厚度影响着硅碳材料的导电性。本申请中该碳化硅材料层的厚度主要借助于与其有关的X射线的相关图谱获得。
本申请在这些实施例中公开了，在纳米硅晶粒与多孔碳材料相接触的部分贯通孔内壁界面上形成有碳化硅材料层，碳化硅材料层位于贯通孔与纳米硅晶粒之间，该碳化硅材料层的一侧连接多孔碳材料的贯通孔内壁，另一侧连接纳米硅以形成碳化硅界面层，该碳化硅界面层与纳米硅晶粒相邻设置，用于限制脱嵌锂过程中，纳米硅晶粒向外膨胀的程度。
本申请在这些实施例中公开了，硅碳材料还包括碳包覆层，碳包覆层沿多孔碳材料的外侧表面设置。
此外，本申请中的碳包覆层包含了碳材料层沿多孔碳材料的外侧表面布置以形成包裹多孔碳材料的外壳层，该外壳层一方面可减少纳米硅与外界空气接触进而被氧化的概率，另一方面可降低纳米硅晶粒与电解液接触反应的概率。
在本申请的一些实施例中，碳包覆层为无定型碳，比如包含制备过程中裂解得到的软碳或硬碳等，本申请在这些实施例中公开了碳包覆层的厚度为5nm～50nm，优选为10nm～30nm，适宜厚度的碳包覆层既不会影响锂离子的嵌入和硅碳材料的容量，又能起到对内部硅颗粒的有效保护以降低副反应概率。本申请中碳包覆层的厚度也可以借助于与其有关的X射线的相关图谱获得。
在本申请的一些实施例中，硅碳材料包含硅元素，基于硅碳材料的总质量，硅元素的质量百分比含量为w硅，满足：w硅为38.0％～48.0％。
在本申请的一些实施例中，w硅为40.0％～45.0％。
在本申请的一些实施例中，硅碳材料包含碳元素，基于硅碳材料的总质量，碳元素的质量百分比含量为w碳，满足：w碳为50.0％～55.0％。
本申请中，硅材料在贯通孔内的形成量影响着其与电解液发生反应的概率，一般而言，形成量越多，自身在脱嵌锂循环中的膨胀性越大，与电解液发生反应的概率也越大，且硅材料的含量也影响着电池的容量。受限于贯通孔的孔容及封闭孔的孔容，本申请选择控制w硅为38.0％～48.0％。在这些实施例中，w硅包含但不限于38.0％、40.0％、42.0％、43.0％、44.0％、45.0％、48.0％中的任一种或满足上述范围值中的任一种。本申请中的硅碳材料主要包含硅元素与碳元素，此外，还包含其他在多孔碳材料中不必可少的元素。硅元素含量和碳元素的含量可借助相关标准测得，比如，硅元素的含量可参照GB/T 20975.5-2020，碳元素的含量可参照GB/T 20123-2006/ISO 15350:2000。
在本申请的一些实施例中，多孔碳材料包含多孔碳材料颗粒物，该多孔碳材料颗粒物的粒径满足：Dv50为3.0μm～6.5μm；Dv90为13.5μm～18.5μm；Dv10为0.9μm～2.5μm。
本申请在一些实施例中公开了多孔碳材料颗粒物的粒径满足：Dv50为3.5μm～6.0μm；Dv90为14.0μm～18.0μm；Dv10为1.0μm～2.0μm。
本申请中的Dv90包含了粒径小于它的颗粒体积占90％，Dv10包含了粒径小于它的颗粒体积占10％，Dv50包含了粒径大于它的颗粒体积占50％，小于它的颗粒体积也占50％，又被称为中位径，通常用来表示颗粒的平均粒度。无论是Dv90，还是Dv10与Dv50，均可采用本领域常规的测量方法，比如采用粒度分析仪器测定粒径分布然后经统计获得。本申请在这些实施例中选择参照激光衍射粒度分析法测定，具体参照标准GB/T19077-2016得到粒径分布图，然后通过计算得到。
本申请通过控制多孔碳材料颗粒物的粒径满足：Dv50为3.0μm～6.5μm；Dv90为13.5μm～18.5μm；Dv10为0.9μm～2.5μm。以使纳米硅晶粒高效的形成于多孔碳材料的贯通孔内。本申请在这些实施例中公开了Dv50为3.0μm、3.3μm、3.5μm、3.8μm、4.0μm、4.2μm、4.5μm、4.8μm、5.0μm、5.2μm、5.5μm、5.8μm、6.0μm、6.5μm中的任一种或满足该范围值中的任一种。Dv90包含但不限于13.5μm、14.0μm、14.5μm、15.0μm、15.5μm、16.0μm、16.5μm、17.0μm、17.5μm、18.0μm、18.5μm中的任一种或满足上述范围值中的任一种。Dv10包含但不限于0.9μm、1.0μm、1.2μm、1.5μm、1.8μm、2.0μm、2.2μm、2.5μm中的任一种或满足上述范围值中的任一种。
本申请在一些实施例中公开了多孔碳材料颗粒物的比表面积为900m2/g～1550m2/g。
本申请在一些实施例中公开了多孔碳材料颗粒物的比表面积为1000m2/g～1500m2/g。
本申请中的比表面积包含了本领域常规的任意概念，其可以采用本领域公知的仪器或方法进行测试得到，比如采用气体吸附法测试比表面积，具体参照GB/T19587-2017的标准测试得到。
本申请在这些实施例中控制多孔碳材料颗粒物的比表面积为900m2/g～1550m2/g，以方便纳米硅晶粒高效的形成于多孔碳材料的贯通孔内。本申请在这些实施例中还公开了多孔碳材料颗粒物的比表面积包含但不限于900m2/g、990m2/g、1000m2/g、1050m2/g、1100m2/g、1150m2/g、1200m2/g、1250m2/g、1300m2/g、1350m2/g、1400m2/g、1450m2/g、1500m2/g、1550m2/g中的任一种或满足上述范围值中的任一种。
本申请在一些实施例中公开了多孔碳材料颗粒物的振实密度为0.22g/cm3～0.48g/cm3。
本申请在一些实施例中公开了多孔碳材料颗粒物的振实密度为0.25g/cm3～0.45g/cm3。
本申请中的振实密度含了本领域常规的任意概念，其可以采用本领域公知的仪器或方法进行测试得到，比如参照标准GB/T5162-2006进行测试得到。本申请在这些实施例中控制多孔碳材料颗粒物的振实密度为0.22g/cm3～0.48g/cm3。在保证多孔碳材料具备上述粒径、比表面积的前提下，有效形成纳米硅晶粒。
本申请在这些实施例中公开了多孔碳材料颗粒物的振实密度包含但不限于0.22g/cm3、0.25g/cm3、0.30g/cm3、0.35g/cm3、0.40g/cm3、0.45g/cm3、0.48g/cm3中的任一种或满足上述范围值中的任一种。
本申请在一些实施例中公开了多孔碳材料颗粒物的5吨粉体压实密度为0.45g/cm3～0.80g/cm3。
本申请在一些实施例中公开了多孔碳材料颗粒物的5吨粉体压实密度为0.50g/cm3～0.75g/cm3。
本申请中的压实密度含了本领域常规的任意概念，其可以采用本领域公知的仪器或方法进行测试得到，比如将冷压的压力限定为5吨，参照GB/T 24533-2009的计算方法得到。比如采用电子压力测试仪(例如UTM7305)测定的。具体而言，将特定量M的待测粉末样品放置在专用压模上(底面积为S0)，并设定不同的压力。每个压力保持30秒，然后释放，10秒后，在设备上读出该压力下压制的粉末的厚度H0。通过计算得到该压力下的压实密度，该压力下负极板材料的压实密度等于 M/(H0×S0)。
本申请选择控制多孔碳材料颗粒物在冷压的压力为5吨时的压实密度为0.50g/cm3～0.75g/cm3，以在保证多孔碳材料具备上述粒径、比表面积、振实密度的前提下，有效形成纳米硅晶粒。
本申请在这些实施例中公开了多孔碳材料颗粒物的在5吨下的压实密度包含但不限于0.45g/cm3、0.50g/cm3、0.55g/cm3、0.60g/cm3、0.65g/cm3、0.70g/cm3、0.75g/cm3、0.80g/cm3中的任一种或满足上述范围值中的任一种。
在本申请的一些实施例中，硅碳复合颗粒物的粒径满足：(Dv90-Dv10)/Dv50为1.2～2.8。
在本申请的一些实施例中，硅碳复合颗粒物的粒径满足：(Dv90-Dv10)/Dv50为1.3～2.5。
本申请中的Dv90包含了粒径小于它的颗粒体积占90％，Dv10包含了粒径小于它的颗粒体积占10％，Dv50包含了粒径大于它的颗粒体积占50％，小于它的颗粒体积也占50％，又被称为中位径，通常用来表示颗粒的平均粒度。无论是Dv90，还是Dv10与Dv50，均可采用本领域常规的测量方法，比如采用粒度分析仪器测定粒径分布然后经统计获得。本申请在这些实施例中选择参照激光衍射粒度分析法测定，具体参照标准GB/T19077-2016得到粒径分布图，然后通过计算得到。
本申请选择硅碳复合颗粒物的粒径满足：(Dv90-Dv10)/Dv50为1.2～2.8，使大小粒径的硅碳复合颗粒物搭配得当，以改善电池体积能量密度的前提下，尽量减小脱嵌锂过程中硅碳材料的膨胀。
本申请在这些实施例中给出了(Dv90-Dv10)/Dv50包含但不限于1.2、1.3、1.4、1.5、1.6、1.7、1.8、1.9、2.0、2.1、2.2、2.3、2.4、2.5、2.6、2.7、2.8中的任一种或满足该范围值中的任一种。
本申请的一些实施例对硅碳复合颗粒物的各粒径进行了具体数值的限定，如Dv50为3.5μm～9.0μm，又如Dv90为14.0μm～21.0μm，再如Dv10为0.9μm～3.0μm。
本申请在一些实施例中给出了Dv50为4.0μm～6.5μm；Dv90为15.0μm～20.0μm；Dv10为1.0μm～2.5μm。
本申请中由于硅晶粒的大小会影响锂离子扩散路径，本申请在上述硅晶粒的平均粒径≥5nm前提下，通过控制硅碳复合颗粒物具备合适的粒径，以平衡硅碳材料的整体性能。本申请在这些实施例中公开了硅碳复合颗粒物的Dv50为3.5μm、3.8μm、4.0μm、4.2μm、4.5μm、5.0μm、5.5μm、5.8μm、6.0μm、6.2μm、6.5μm、6.7μm、7.0μm、7.5μm、8.0μm、8.5μm、9.0μm中的任一种或满足上述范围值中的任一种。本申请在这些实施例中还公开了硅碳复合颗粒物的Dv90为14.0μm、14.5μm、15.0μm、15.2μm、15.5μm、15.8μm、16.0μm、16.5μm、17.0μm、17.5μm、 18.0μm、18.5μm、19.0μm、19.5μm、20.0μm、20.5μm、21μm中的任一种或满足上述范围值中的任一种。本申请在这些实施例中还给出了Dv10为0.9μm、1.0μm、1.5μm、2.0μm、2.2μm、2.5μm、2.8μm、3.0μm中的任一种或满足上述范围值中的任一种。
在本申请的一些实施例中，硅碳复合颗粒物的比表面积为3.0m2/g～12.0m2/g。
在本申请的一些实施例中，硅碳复合颗粒物的比表面积为5.0m2/g～10.0m2/g。
本申请中的比表面积包含了本领域常规的任意概念，其可以采用本领域公知的仪器或方法进行测试得到，比如采用气体吸附法测试比表面积，具体参照GB/T19587-2017的标准测试得到。
本申请通过选择硅碳复合颗粒物的比表面积为3.0m2/g～12.0m2/g，以使硅碳材料具备适宜的脱嵌锂位点，以改善电池的容量及循环性。
在本申请的一些实施例中，硅碳复合颗粒物的振实密度为0.5g/cm3～1.0g/cm3。
在本申请的一些实施例中，硅碳复合颗粒物的振实密度为0.6g/cm3～0.8g/cm3。
本申请中的振实密度含了本领域常规的任意概念，其可以采用本领域公知的仪器或方法进行测试得到，比如参照标准GB/T5162-2006进行测试得到。
本申请选择硅碳复合颗粒物的振实密度为0.5g/cm3～1.0g/cm3，在保证硅碳复合颗粒物具备上述粒径、比表面积的前提下，有效改善电池的体积能量密度。
本申请在这些实施例中公开了硅碳复合颗粒物的振实密度包含但不限于0.5g/cm3、0.6g/cm3、0.7g/cm3、0.8g/cm3、0.9g/cm3、1.0g/cm3中的任一种或满足上述范围值中的任一种。
在本申请的一些实施例中，硅碳复合颗粒物的5吨粉体压实密度为0.80g/cm3～1.1g/cm3。
在本申请的一些实施例中，硅碳复合颗粒物的5吨粉体压实密度为0.90g/cm3～1.05g/cm3。
本申请中的压实密度含了本领域常规的任意概念，其可以采用本领域公知的仪器或方法进行测试得到，比如将冷压的压力限定为5吨，参照GB/T 24533-2009的计算方法得到。比如采用电子压力测试仪(例如UTM7305)测定的。具体而言，将特定量M的待测粉末样品放置在专用压模上(底面积为S0)，并设定不同的压力。每个压力保持30秒，然后释放，10秒后，在设备上读出该压力下压制的粉末的厚度H0。通过计算得到该压力下的压实密度，该压力下负极板材料的压实密度等于M/(H0×S0)。
本申请选择硅碳复合颗粒物的5吨粉体压实密度为0.80g/cm3～1.1g/cm3以有效改善电池的容量并提高其实用性。
本申请在这些实施例中公开了硅碳复合颗粒物在5吨下的压实密度为0.80g/cm3、0.90g/cm3、1.0g/cm3、1.1g/cm3中的任一种或满足上述范围值中的任一种。
在本申请的一些实施例中，硅碳复合颗粒物在4Mpa下的粉末电阻率为1.30Ω·cm～3.80Ω·cm。
本申请中的硅碳复合颗粒物的粉末电阻率不同于极片的电阻率，其用来表征硅碳材料自身的导电性。本申请中的粉末电阻率包含了本领域常规的任意概念，比如将适量的硅碳材料置于电阻率测试仪的加料杯中，施加压力，手动采集数据，记录不同压力点的粉末电阻率测试结果然后取平均值，测试压力为4MPa。
本申请的硅碳复合颗粒物在4Mpa下的粉末电阻率为1.30Ω·cm～3.80Ω·cm。表明了本申请中硅材料颗粒物中的硅晶粒的形成量是适宜的且有效的，这是因为在硅碳材料中，多孔碳材料是具备良好导电性的，而硅材料的导电性较弱。本申请选择碳复合颗粒物在4Mpa下的粉末电阻率为1.30Ω·cm～3.80Ω·cm有利于改善电池的容量及循环性。
在本申请的一些实施例中，硅碳复合颗粒物的脱锂比容量为1300mAh/g～1500mAh/g，首次库伦效率为77％～81％。在这些实施例中，以硅碳复合颗粒物为正极活性材料，金属锂片为对电极，组装形成CR2430型扣式电池，25℃下，充放电电压为0.005～2.0V，测量得到脱锂比容量为1300mAh/g～1500mAh/g，首次库伦效率为77％～81％。本申请测试得到脱锂比容量为1300mAh/g～1500mAh/g，该数值与硅碳材料中的硅含量及硅材料的位置关系相匹配。
在本申请的一些实施例中，硅碳复合颗粒物的dQ/dV曲线中，I1为0.3V～0.35V附近的峰强度；I2为0.43V～0.50V附近的峰强度；满足：I1/I2＝1.4～1.8；硅碳复合颗粒物的dQ/dV曲线包含以硅碳复合颗粒物为正极活性材料，金属锂片为对电极，组装形成CR2430型扣式电池，25℃下，充放电电压为0.005V～2.0V，对充放电容量，工作电极电势进行微分处理得到。
本申请提供的硅碳材料在一定条件下的充放电曲线的微分容量/电压曲线中给出了一定电压下具备一定强度的峰值，峰值之间的比值用于说明硅材料颗粒物在贯通孔中形成量是适宜的，而适宜的形成量有利于改善电池的循环性。
综上所述，本申请提供了一种硅碳材料，该硅碳材料包含具备一定粒径、比表面积、振实密度及压实密度的硅碳复合颗粒物，该硅碳复合颗粒物包含具备一定孔径的多孔碳材料，该多孔碳材料包含一定数量及孔容的贯通孔，该硅碳复合颗粒物还包含一定数量及孔容的封闭孔，纳米硅晶粒沿多孔碳材料的贯通孔内壁分布并形成具备适宜粒径，该具备适宜粒径的纳米硅晶粒进一步沿贯通孔内壁面堆叠形成层状或片状膜，该层状或片状膜与贯通孔内壁直接接触的区域生成碳化硅材料层。该布置方式既能够降低其与电解液发生反应的概率，还能控制硅材料的膨胀率，这是因为，硅材料的膨胀不仅受到贯通孔的限制，还受到碳化硅材料层的限制。此外，在多孔碳材料外部形成有碳包覆层，该碳包覆层一方面可减少纳米硅晶粒与外界空 气接触进而被氧化的概率，另一方面可降低纳米硅晶粒与电解液接触反应的概率。故本申请提供的硅碳材料从多个层面，如形成具备一定适宜粒径的纳米硅晶粒、物理隔绝、物理限制等方式，在控制硅材料脱嵌锂离子过程中膨胀程度前提下，降低硅材料与电解液之间发生副反应的概率，在一定程度上改善了电池的循环性。
为更好的解释上述硅碳材料的结构及性能等，以下结合其制备方法进行详细说明。
硅碳材料的制备方法
本申请在一些实施例中提供了硅碳材料的制备方法，包括如下制备过程：
提供多孔碳基材；
向多孔碳基材中通入硅源，生成包含纳米硅晶粒及碳化硅材料层的多孔碳材料；
向包含纳米硅晶粒及碳化硅材料层的多孔碳材料中通入碳源，生成包含碳包覆层的硅碳负极材料。
在本申请的一些实施例中，多孔碳基材包含碳元素、氧元素及氮元素，碳元素与氧元素及氮元素的质量比为(94％～97％):(2％～4％):(1％～2％)；
优选地，多孔碳基材的灰分≤0.5％。
本申请的多孔碳基材包含采用本领域常规的碳材料前驱体制得，碳材料前驱体的种类不作特别限制，可包括但不限于，基于沥青的碳材料前驱体、基于沥青烯的碳材料前驱体、基于煤的碳材料前驱体、基于焦炭的碳材料前驱体、基于生物炭的碳材料前驱体、基于炭黑的碳材料前驱体、基于油产品的碳材料前驱体、基于焦油的碳材料前驱体、基于聚合物的碳材料前驱体、基于蛋白质的碳材料前驱体、基于碳水化合物的碳材料前驱体、基于棉花的碳材料前驱体、基于脂肪的碳材料前驱体、基于废弃物的碳材料前驱体、基于石墨的碳材料前驱体、基于蜜胺的碳材料前驱体、基于木材的碳材料前驱体、多孔石墨烯、多孔氧化石墨烯、活性炭以及它们的组合等。具备该种类的碳材料前驱体容易制得满足具备上述粒径、比表面积、振实密度及压实密度等的多孔碳材料。本申请在这些实施例中公开了多孔碳基材的制备方法，比如对碳材料前驱体进行高温烧结以去除杂质，然后进行造孔以得到多孔碳材料，本申请的造孔包含强碱腐蚀等化学方法。本申请多孔碳基材中的碳元素、氧元素及氮元素的测量方式包含本领域常规的任意方法，比如按照相关测试标准测得。本申请在这些实施例中公开了多孔碳基材中碳元素的质量百分比包含94％、95％、96％、97％中的任一种或满足上述范围值中的任一种。多孔碳基材中氧元素的质量百分比包含2％、3％、4％中的任一种或满足上述范围值中的任一种。多孔碳基材中氮元素的质量百分比包含1％、2％中的任一种或满足上述范围值中的任一种。
本申请中的灰分包含了多孔碳基材经高温灼烧后残留下的无机物，灰分的测量方法可参照GB/T 1429-2009。
在本申请的一些实施例中，生成包含纳米硅晶粒及碳化硅材料层的多孔碳材料的反应条件包含如下一种或两种以上：
(5.1)反应温度为500℃～700℃，通入硅源时间为3h～42h；优选反应温度为650℃～700℃；优选通入硅源时间为5h～40h；
(5.2)硅源包含硅源气体与稀释气体，硅源气体的体积百分数为15％～95％；优选硅源气体的体积百分数为20％～50％；优选硅源气体包含甲硅烷，乙硅烷中的任一种或两种；
(5.3)硅源的通气量为0.3L/min～1.4L/min。
本申请在一些实施例中公开了生成包含纳米硅晶粒及碳化硅材料层的多孔碳材料的反应温度包含500℃、600℃、650℃、680℃、700℃中的任一种或满足上述范围值中的任一种。本申请在这些实施例中公开了通入硅源时间包含3h、4h、5h、6h、7h、8h、9h、10h、11h、12h、13h、14h、15h、16h、17h、18h、19h、20h、21h、22h、23h、24h、25h、26h、27h、28h、29h、30h、31h、32h、33h、34h、35h、36h、37h、38h、39h、40h、41h、42h中的任一种或满足上述范围值中的任一种。本申请在这些实施例中选择反应温度为500℃～700℃，通入硅源时间为3h～42h；方便在贯通孔内生长晶粒尺寸d1≥5nm的硅晶粒，该硅晶粒沿贯通孔内壁面堆叠形成层状或片状膜，该层状或片状膜在不断生长的过程中在上述反应温度内还容易与贯通孔内壁直接接触的区域生成碳化硅材料层，而碳化硅材料层及多孔碳材料的贯通孔又限制硅晶粒的生长，最终生成具备一定适宜粒径的纳米硅晶粒。
本申请在一些实施例中公开了用于形成硅晶粒的硅源包含硅源气体与稀释气体，其中，硅源气体包含但不限于甲硅烷，乙硅烷等，稀释气体包含惰性气体，惰性气体包含采用本领域常规的惰性气体，包含但不限于元素周期表中零族对应的稀有气体等。本申请在这些实施例中公开了硅源气体在硅源中的体积分数包含15％、20％、30％、40％、50％、60％、70％、80％、90％、95％中的任一种或满足上述范围值中的任一种。
本申请在一些实施例中公开了生成包含纳米硅晶粒及碳化硅材料层的多孔碳材料过程中还需要控制硅源的通气量，硅源的通气量可以采用本领域常规的测量方法测得，比如在反应设备中设置流量阀等。本申请在这些实施例中公开了硅源的通气量包含0.3L/min、0.4L/min、0.5L/min、0.6L/min、0.7L/min、0.8L/min、0.9L/min、1.0L/min、1.1L/min、1.2L/min、1.3L/min、1.4L/min中的任一种或满足上述范围值中的任一种。本申请通过控制硅源中各成分的体积百分数及通气量用于控制硅晶粒的生长速度，进而影响硅晶粒的晶粒尺寸及碳化硅材料层的形成及厚度等。
在本申请的一些实施例中，生成包含碳包覆层的硅碳负极材料的反应条件包含如下：
(6.1)反应温度为600℃～750℃，通入碳源的时间为0.5h～5h，优选反应温度 为650℃～700℃；优选通入碳源时间为1h～4h；
(6.2)碳源包含碳源气体与稀释气体，碳源气体的体积分数为15％～95％；优选碳源气体的体积分数为20％～40％；优选碳源气体包含甲烷、乙烯、乙炔、丙烯中的任一种或两种以上组合；
(6.3)碳源的通气量为1.0L/min～3.0L/min，优选通气量为1.5L/min～2.5L/min。
本申请碳包覆层的反应温度包含600℃、650℃、700℃、750℃中的任一种或满足上述范围值中的任一种。本申请通入碳源的时间包含0.5h、1h、1.5h、2h、2.5h、3h、3.5h、4h、4.5h、5h中的任一种或满足上述范围值中的任一种，在本申请的反应温度和通入碳源的时间内，碳包覆层沿多孔碳材料的外侧表面形成并具备一定厚度。且在该反应条件下，沿贯通孔内壁面堆叠形成的具备层状或片状膜的硅材料可能继续与贯通孔内壁直接接触的区域生成碳化硅材料层。
本申请在一些实施例中公开了用于形成碳包覆层的碳源包含碳源气体与稀释气体，如上所述，稀释气体包含惰性气体，惰性气体包含采用本领域常规的惰性气体，包含但不限于元素周期表中零族对应的稀有气体等。碳源气体包含但不限于甲烷、乙烯、乙炔、丙烯等。本申请在这些实施例中还公开了碳源气体的体积百分数包含但不限于15％、20％、25％、30％、35％、40％、45％、50％、55％、60％、65％、70％、75％、80％、85％、90％、95％中的任一种或满足上述范围值中的任一种。碳源的通气量包含但不限于1.0L/min、2.0L/min、3.0L/min中的任一种或满足上述范围值中的任一种。本申请在该碳源气体的体积百分数及碳源的通气量的反应条件控制下，生成了厚度为5nm～50nm的碳包覆层，以及厚度＜0.7nm的碳化硅材料层。
负极极片
本申请的一些实施例中公开了负极极片，该负极极片包含负极集流体及位于负极集流体至少一侧表面的负极膜层，该负极膜层包含硅碳材料作为负极活性材料，还包含其他负极活性材料，比如碳质材料，具体包含但不限于人造石墨、天然石墨、软炭、硬炭中的一种或两种以上组合。其中，人造石墨、天然石墨、软炭、硬炭等包含本领域常规的任意形式的材料，且包含了本领域常规的任意厂家与型号。
本申请的一些实施例中公开了负极膜层还包含导电剂、增稠剂、粘结剂等，其中，导电剂包含但不限于石墨、超导碳、炭黑(如乙炔黑、科琴黑、Super P等)、碳点、碳纳米管、石墨烯和碳纳米纤维中的一种或两种组合；增稠剂包含纤维素及其钠盐，纤维素包括甲基纤维素、羧甲基纤维素、羟乙基纤维素等；粘结剂包含但不限于聚乙烯醇、聚乙二醇、羧甲基纤维素钠、聚氧化乙烯、聚丙烯酸、聚丙烯酰胺、海藻酸钠、丁苯橡胶(SBR)等。
本申请的负极集流体可以是金属箔片或复合集流体，金属箔片可以是铜箔片，复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金 属层。复合集流体可通过将金属材料，如铜、铜合金、镍、镍合金、钛、钛合金、银及银合金等形成在高分子材料基材如聚丙烯(PP)、聚对苯二甲酸乙二醇酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材上而形成。
本申请在一些实施例中公开了负极膜层中的硅碳材料、碳质材料：导电剂、增稠剂与粘结剂之间的质量比：(10％～50％)：(45％～95％)：(0.2％～2.0％)：(0.2％～2.0％)：(1.2％～2.2％)。
正极极片
本申请的一些实施例中公开了正极极片，该正极极片包含正极集流体及位于正极集流体至少一侧表面的正极膜层，本申请中的正极膜层包含正极活性颗粒、正极导电剂、正极粘结剂等，本申请对正极活性颗粒的具体种类不作具体限定，比如，正极极片应用于锂离子电池时，正极活性颗粒包含但不限于LiCoO2、LiNiO2、LiMnO2、LiMn2O4、LiNi1/3Co1/3Mn1/3O2(NCM111)、LiNi0.5Co0.2Mn0.3O2(NCM523)、LiNi0.6CO0.2Mn0.2O2(NCM622)、LiNi0.8CO0.1Mn0.1O2(NCM811)、LiNi0.85CO0.15Al0.05O2、LiFePO4(LFP)和LiMnPO4中的一种或两种以上。
又比如正极极片应用于钠离子电池时，正极活性颗粒包含但不限于钠过渡金属氧化物、聚阴离子型化合物、普鲁士蓝类化合物中至少一种。其中，钠过渡金属氧化物中，过渡金属可以是Mn、Fe、Ni、Co、Cr、Cu、Ti、Zn、V、Zr及Ce中的一种或两种以上，钠过渡金属氧化物例如为NaxMO2，其中M为Ti、V、Mn、Co、Ni、Fe、Cr及Cu中的一种或两种以上，0＜x≤1。聚阴离子型化合物包括三氟磷酸钒钠(Na3V2(PO4)2F3)、氟磷酸钒钠(NaVPO4F)、磷酸钒钠(Na3V2(PO4)3)、Na4Fe3(PO4)2P2O7、NaFePO4、中一种或两种以上。普鲁士蓝类化合物为NaxM1M2(CN)6，其中，M1、M2为Fe、Mn、Co、Ni、Cu、Zn、Cr、Ti、V、Zr、Ce中一种或两种以上，其中，0＜x≤2。
正极导电剂包含但不限于石墨、超导碳、炭黑(如乙炔黑、科琴黑、Super P等)、碳点、碳纳米管、石墨烯和碳纳米纤维中的一种或两种以上组合。正极粘结剂包含但不限于聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、偏氟乙烯-四氟乙烯-丙烯三元共聚物、偏氟乙烯-六氟丙烯-四氟乙烯三元共聚物、四氟乙烯-六氟丙烯共聚物、含氟丙烯酸酯树脂、丁苯橡胶、聚丙烯酸、聚丙烯酸钠、聚丙烯酰胺、聚乙烯醇、海藻酸钠、聚甲基丙烯酸、羧甲基壳聚糖等中的一种或两种以上组合。
本申请中的正极集流体可以是金属箔片或复合集流体，其中，金属箔片可以是铝箔片，复合集流体可包括高分子材料基层和形成于高分子材料基层至少一个表面上的金属层。复合集流体可通过将金属材料，如铝、铝合金、镍、镍合金、钛、钛合金、银及银合金等形成在高分子材料基材如聚丙烯(PP)、聚对苯二甲酸乙二醇 酯(PET)、聚对苯二甲酸丁二醇酯(PBT)、聚苯乙烯(PS)、聚乙烯(PE)等的基材上而形成。
电解液
本申请的一些实施例中公开了电解液，该电解液包含钠盐或锂盐和有机溶剂，有机溶剂可以是本领域常用的用于电解液的有机溶剂。作为示例，有机溶剂可以选自碳酸亚乙酯(EC)、碳酸亚丙酯(PC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)、碳酸二甲酯(DMC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸亚丁酯(BC)、氟代碳酸亚乙酯(FEC)、甲酸甲酯(MF)、乙酸甲酯(MA)、乙酸乙酯(EA)、乙酸丙酯(PA)、丙酸甲酯(MP)、丙酸乙酯(EP)、丙酸丙酯(PP)、丁酸甲酯(MB)、丁酸乙酯(EB)、1,4－丁内酯(GBL)、环丁砜(SF)、二甲砜(MSM)、甲乙砜(EMS)及二乙砜(ESE)中的至少一种或两种组合。而钠盐或锂盐可以是本领域常用的用于电解液的钠盐或锂盐，比如六氟磷酸钠、六氟磷酸锂等。
隔离膜
根据本申请的一些实施例，电池不仅包含负极极片、正极极片及电解液，还包含叠置在一起的隔离膜，叠置方式包含但不限于本领域常规的卷绕或层叠，隔离膜的材质、尺寸等包含但不限于本领域常规的任意形式，同理，正极极片的材质、尺寸等包含但不限于本领域常规的任意形式。比如，隔离膜设置在正极极片和负极极片之间起到隔离的作用。隔离膜包括基材，还包括在基材的至少一个表面上设置功能涂层。功能涂层可用于改善隔离膜的耐热性能、机械强度等。比如功能涂层中还可包括其它功能材料(例如陶瓷颗粒、其它聚合物等)。陶瓷颗粒包含但不限于勃姆石、氧化铝、氧化锌、氧化硅、氧化钛、氧化锆、氧化钡、氧化钙、氧化镁、氧化镍、氧化锡、氧化铈、氧化钇、氧化铪、氢氧化铝、氢氧化镁、碳化硅、碳化硼、氮化铝、氮化硅、氮化硼、氟化镁、氟化钙、氟化钡、硫酸钡、硅酸镁铝、硅酸镁锂、硅酸镁钠、膨润土、水辉石、钛酸锆、钛酸钡等；本申请对隔离膜基材的种类没有特别的限制，可以选用任意公知的可用于二次电池隔离膜的基材。在一些实施例中，隔离膜基材包含但不限于玻璃纤维、无纺布、聚乙烯、聚丙烯中的一种或几种的单层薄膜或多层复合薄膜。
[制备硅碳材料]
本申请在一些实施例中公开了硅碳材料的制备方法，包括如下制备步骤：
S1、提供多孔碳基材，该多孔碳基材包含碳元素、氧元素及氮元素，碳元素与氧元素及氮元素的质量比为(94％～97％):(2％～4％):(1％～2％)，且该多孔碳基材的灰分≤0.5％；
与此同时，该多孔碳基材包含多孔碳材料颗粒物，该多孔碳材料颗粒物的孔容、平均孔径、贯通孔数量及分布情况、粒径、比表面积及振实密度等满足如下：
a、平均孔径为1.0nm～5.0nm；
b、大孔的体积百分含量≤15％，微空与中空的体积比为(40～95％):(5～50％)；
c、Dv50为3.0μm～6.5μm；Dv90为13.5μm～18.5μm；Dv10为0.9μm～2.5μm；
d、比表面积为900m2/g～1550m2/g；
e、振实密度为0.22g/cm3～0.48g/cm3；
f、压实密度为0.45g/cm3～0.80g/cm3；
S2、将S1的多孔碳基材置于CVI设备中，通入硅源3h～42h，在500℃～700℃下进行化学气相沉积反应生成包含纳米硅晶粒的多孔碳材料，该CVI设备包含流化床，还包含回转炉、推板炉或管式炉中的任一种；硅源的通气量为0.2L/min～1.5L/min，硅源包含硅源气体与稀释气体，硅源气体的体积分数为15％～95％；硅源气体包含甲硅烷，乙硅烷中的任一种或两种；
S3、向S2的包含纳米硅晶粒的多孔碳材料中通入碳源0.5h～5h，在600℃～750℃下进行反应得到生成包含碳包覆层的硅碳负极材料，碳源的通气量为1.0L/min～3.0L/min，碳源包含碳源气体与稀释气体，碳源气体的体积分数为15％～95％；碳源气体包含甲烷、乙烯、乙炔、丙烯中的任一种或两种以上组合。
其中实施例1至实施例16是按照表1、表2、表3列举的原料及表4列举的工艺参数得到的硅碳材料，且硅碳材料的粒径、比表面积等如表5示意。
其中，图5为实施例8制得硅碳材料的电镜图，使用场发射扫描电镜(蔡司Gemini360)按照JY/T010-1996标准进行测试。结合图5可知，硅碳材料由具备不同粒径的不规则形貌颗粒组成。
图6为本申请硅碳复合颗粒物的结构示意图，结合图6可知，该硅碳复合颗粒物1包含多孔碳材料1a，该多孔碳材料具备贯通孔，纳米硅晶粒1b沿多孔碳材料1a的贯通孔内壁分布，同时还会留出部分剩余封闭孔1c；在贯通孔内部上形成有碳化硅材料层1d，该碳化硅材料层1d的一侧连接贯通孔内壁，另一侧连接纳米硅晶粒1b。本申请在贯通孔内壁形成的剩余封闭孔1c可用于缓解纳米硅材料嵌锂时的部分膨胀，从而缓解硅碳复合颗粒的膨胀。而碳化硅材料层可用于限制纳米硅颗粒在脱嵌锂过程中向外膨胀的程度以降低纳米硅颗粒物与电解液反应的作用。
进一步结合图7可知，在硅碳材料内部确实形成了一定量碳化硅材料层。其中，图7为实施例8制得硅碳材料的X射线光电子能谱分析图谱。该碳化硅材料层的厚度通过计算得到其厚度小于0.7nm。
图8为对实施例8制得硅碳材料进行放大获得纳米硅晶粒1b的电镜图，结合图8可知，纳米硅晶粒沿贯通孔内壁堆叠形成层状或片状膜。
图9为实施例8制得硅碳材料的透射电镜图，结合图9可知，在多孔碳材料的外侧表面形成有碳包覆层，该碳包覆层的厚度为18.4nm。
图10为实施例8制得硅碳材料的X射线衍射图谱，其可以采用X射线衍射仪 以本领域公知的方法测试得到，作为示例，具体参考XRD测试一般规则JIS K 0131-1996，包括以下要求：(1)样品干燥；(2)样品粒径<10μm，若为极片刮粉或块状样品，需研磨过200目筛送样。结合图10可知，硅碳材料有较强的硅结晶峰，通过Scherrer公式计算获得硅碳材料的硅晶粒尺寸为7.2nm。
图11为实施例8制得硅碳材料的放电曲线的dQ/dV曲线图，结合图11可知，硅碳材料I1/I2＝1.45，说明硅材料颗粒物在贯通孔中形成量是适宜的，而适宜的形成量有利于改善电池的循环性。其中I1为0.3V～0.35V附近的峰强度；I2为0.43V～0.50V附近的峰强度。
对比例1
提供了一种硅碳材料，生成该硅碳材料的碳基材与本申请不同，并在生成硅晶粒过程中采用低温450℃下进行，得到纳米硅晶粒的平均粒径小于多孔碳材料的平均孔径且未生成碳化硅材料层，具体详见表1至表5。
对比例2
提供了一种硅碳材料，生成该硅碳材料的碳基材与本申请保持相同，其在生成硅晶粒过程中采用低温450℃，在碳包覆过程中反应温度为500℃，导致未生成碳化硅材料层，具体详见表1至表5。
其中，获取对比例1至对比例2制得的硅碳材料的透射电镜图及X射线光电子能谱分析图谱，分析其实际上并未生成碳化硅材料层。
[硅碳材料的性能测试]
①粒径测试：
参照标准GB/T19077-2016：得到多孔碳颗粒或硅碳复合颗粒的体积粒度分布曲线，取累计体积分布百分数达到50％时所对应的粒径作为平均粒径Dv50，取累计体积分布百分数达到90％时所对应的粒径作为平均粒径Dv90，取累计体积分布百分数达到10％时所对应的粒径作为平均粒径Dv10。测试仪器可以为英国马尔文仪器有限公司的Mastersizer3000型激光粒度分析仪。
②比表面积测试：
参照标准GB/T19587-2017：将得到的多孔碳颗粒或硅碳复合颗粒采用氮气吸附比表面积分析测试方法测试，并用BET(Brunauer Emmett Teller)法计算得出比表面积。测试仪器可为美国Micromeritics公司的TRISTAR II 3020型比表面积与孔隙度分析仪。
③贯通孔的孔容测试：
将得到的多孔碳颗粒参照GB/T21650.2-2008测试方法。测试仪器可以为美国Micromeritics公司的TRISTAR II 3020型比表面积与孔隙度分析仪。
④封闭孔的孔容测试：
参照GB/T24586-2009得到硅碳材料的测试真密度，参照GB/T 20975.5-2020得 到硅碳材料中硅元素含量，参照GB/T 20123-2006/ISO 15350:2000得到硅碳材料中碳元素含量。硅的理论真密度ρ硅为2.34g/cm3，碳的理论真密度ρ碳为2.26g/cm3。根据计算关系式：V1＝1/ρ真-1/(w硅×ρ硅+w碳×ρ碳)算得封闭孔的孔容V1。
⑤多孔结构数量测试：
采用测试仪器为ASAP2460-物理吸附分析仪，将烘干脱气处理后的碳颗粒样品置于液氮中，调节不同试验压力，分别测出对氮气的吸附量，并绘出吸附和脱附等温线。根据滞后环的形状确定孔的形状，按不同的孔模型计算孔分布，使用BJH模型拟合中孔的孔径分布曲线，使用DFT模型拟合微孔的孔径分布曲线。然后经统计计算获得。
⑥多孔结构的孔径测试：
在上述⑤关于多孔结构数量测试中，获取各孔的孔径分布曲线，在②中获得比表面积，在③中获得孔容，依据⑤中相关孔的模型，拿孔容除以比表面积乘以模型系数即为平均孔径。
⑦硅晶粒的尺寸测试：
获取硅碳材料的X射线衍射图谱，通过Scherrer公式计算获得。
⑧振实密度测试：
参照标准GB/T5162-2006。
⑨5吨下的压实密度测试：
参照标准GB/T 24533-2009：采用电子压力测试仪(例如UTM7305)测定的。具体而言，将特定量M的待测粉末样品放置在专用压模上(底面积为S0)，并设定不同的压力。每个压力保持30秒，然后释放，10秒后，在设备上读出该压力下(5吨)压制的粉末的厚度H0。通过计算得到该压力下的压实密度，该压力下负极板材料的压实密度等于M/(H0×S0)。
⑩4Mpa下的粉末电阻率测试：
将适量的硅碳材料置于电阻率测试仪的加料杯中，施加压力，手动采集数据，记录不同压力点的粉末电阻率测试结果然后取平均值，测试压力为4MPa。
表1多孔碳基材的性能列表(一)

表2多孔碳基材的性能列表(二)

表3纳米硅晶粒的晶粒尺寸d1与多孔碳材料的平均孔径d2之间比值列表(三)
表4工艺参数列表(四)

表5实施例及对比例的硅碳材料列表

[制备扣式电池]
1.负极极片：
将上述制备的硅碳复合材料、导电炭黑、粘结剂聚丙烯酸按照质量比8:1:1混合，加入去离子水充分搅拌混合，形成负极浆料；将负极浆料均匀涂覆在负极集流体铜箔的一个表面上，经干燥、冷压后，获得负极极片。
2.电解液：
将碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)按体积比20:20:60混合，然后将LiPF6均匀溶解在上述溶液中，并加入添加剂氟代碳酸乙烯酯(FEC)，得到电解液。该电解液中，LiPF6的浓度为1mol/L，FEC在电解液中的质量占比为5％。
3.隔离膜
采用聚乙烯薄膜作为隔离膜。
4.扣式电池的制备
以上述负极极片作为工作电极，以金属锂作为对电极；将负极极片、隔离膜以及金属锂按顺序叠好，使隔离膜处于工作电极和对电极之间，注入上述电解液，组装得到CR2430型扣式电池。
(1)首次脱锂比容量及首次库伦效率的测试：
将上述CR2430型扣式电池进行首次充放电测试，25℃下，采用0.05C恒流放电至5mV，静置10min，0.1C充电至2.0V，得到首次放电容量与首次充电容量。
首次脱锂比容量＝首次脱锂容量/活性物质的质量；其中，首次脱锂容量也就是首次放电容量。
首次库伦效率＝首次放电容量/首次充电容量×100％。
(2)充放电曲线测试：
绘制上述CR2430型扣式电池的充放电曲线测试，25℃下，充放电电压为0.005～2.0V，对充放电容量，工作电极电势进行微分处理，得到dQ/dV曲线；具体的，采用0.05C恒流放电至5mV，采用50μA放电至5mV，静置10min，采用0.1C充电至2.0V，；绘制工作电极电势V对充放电容量Q进行微分而得到的微分值dQ/dV与所述工作电极电势V之间的关系曲线图。
在该dQ/dV曲线中，I1为0.3V～0.35V附近的峰强度；I2为0.43V～0.50V附近 的峰强度；
满足：计算R＝I1/I2。
负极极片的性能测试结果如表6示意。
表6负极极片的性能列表
[制备负极极片]
将上述实施例1至实施例16，及对比例1与对比例2制备的硅碳材料与人造石墨、粘结剂丁苯橡胶(SBR)、粘结剂聚丙烯酸(PAA)、分散剂(CMC-Na)以及导电炭黑(Super-P，SP)、碳纳米管(CNT)按照质量比20％：75％：2％：1％：1％：0.7％：0.3％与去离子水混合形成搅拌均匀的浆料，对该浆料去泡处理，然后均匀涂覆负极集流体铜箔上，涂布速度为50m/min，涂布质量为130mg/1540.25mm2，九节烘箱温度设定依次为100℃/100℃/95℃/85℃/85℃/80℃/80℃/80℃/60℃；使用冷压机将负极极片压实到一定密度，得到负极极片。
[制备正极极片]
以锂离子电池为例，将正极活性材料LiNi0.8Co0.1Mn0.1O2(NCM811)、粘结剂聚偏氟乙烯(PVDF)、导电剂乙炔黑按照质量比为97％:1.5％:1.5％搅拌分散于N-甲基吡咯烷酮中制成正极浆料，涂覆在正极集流体铝箔上，经过冷压机压实后，得到正极极片。
[选择隔离膜]
选择厚度为12μm厚的聚乙烯多孔膜。
[选择电解液]
将碳酸亚乙酯(EC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)按体积比1:1:1混合，然后将LiPF6均匀溶解在上述溶液中，得到电解液。该电解液中，LiPF6的浓度为1mol/L。
[形成电池]
根据本申请的一些实施例，将制备的负极极片与隔离膜、正极极片按顺序叠好，使隔离膜处于正负极极片中间起到隔离的作用，并卷绕得到裸电芯，之后插入电池壳体，经烘烤、注液、静置、封装、化成、分容等工序得到锂离子二次电池。
[二次电池的性能测试]
(3)45℃下的循环性能测试：
将制作好的二次电池在45℃的恒温环境下，以1C倍率恒流充电至电压为4.25V，再在4.25V电压下恒压充电至电流小于等于0.05mA，之后静置5min，然后以1C倍率恒流放电至电压为2.5V，静置5min，此为一个循环充放电过程，此次的放电容量记为二次电池第1次循环的放电容量。将二次电池按照上述方法进行循环充放电测试，直至循环容量保持率为80％，记录为循环寿命CL(45℃)。
二次电池第n次循环的45℃循环容量保持率45℃(％)＝第n次循环的放电容量/第1次循环的放电容量×100％。具体测试结果详见表6。
(4)45℃下的极片循环膨胀性能测试：
将二次电池的负极极片完成冷压工序时的极片厚度记为h0，按上述电池在45℃下的循环性能测试方法，将二次电池循环300圈，以1C倍率恒流充电至电压为4.25V，再在4.25V电压下恒压充电至电流小于等于0.05mA，之后静置5min。在干燥房中拆解循环后的电芯，将300圈循环后的负极极片厚度记为h300，二次电池在45℃下的极片300圈循环膨胀率Δh300。
Δh300(％)＝(h300-h0)/h0×100％。具体测试结果详见表7。
表7电池性能列表

结合上述列表可知，结合实施例1至实施例16，满足本申请列表范围的各实施例的电池循环性能有了一定程度改善，这可能是源于本申请提供的硅碳材料从多个层面，如形成具备一定适宜粒径的纳米硅晶粒、物理隔绝、物理限制等方式，在控制硅材料脱嵌锂离子过程中膨胀程度前提下，降低硅材料与电解液之间发生副反应的概率，在一定程度上改善了电池的循环性。
结合对比例1可知，纳米硅晶粒的尺寸对电池影响较大，如果纳米硅晶粒的尺寸不能与贯通孔的孔径进行合理匹配，容易导致副反应增大，且材料膨胀恶化。
结合对比例1、对比例2及实施例可知，碳化硅材料层的存在对硅材料的膨胀能起到明显限制作用。
故本申请一方面采取控制纳米硅晶粒的尺寸至适宜程度并与贯通孔进行合理匹配，另一方面采取限制硅晶粒的膨胀尺寸(比如设置封闭孔，有比如设计碳化硅材料层)以改善电池的循环性能。
最后应说明的是：以上各实施例仅用以说明本申请的技术方案，而非对其限制；尽管 参照前述各实施例对本申请进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分或者全部技术特征进行等同替换；而这些修改或者替换，并不使相应技术方案的本质脱离本申请各实施例技术方案的范围，其均应涵盖在本申请的权利要求和说明书的范围当中。尤其是，只要不存在结构冲突，各个实施例中所提到的各项技术特征均可以任意方式组合起来。本申请并不局限于文中公开的特定实施例，而是包括落入权利要求的范围内的所有技术方案。

Claims (24)

  1. 一种硅碳材料，其特征在于：包括：硅碳复合颗粒物，所述硅碳复合颗粒物包括：
    多孔碳材料：具备贯通孔；
    纳米硅晶粒：位于所述贯通孔内；所述纳米硅晶粒的晶粒尺寸不小于所述多孔碳材料的平均孔径；
    碳化硅材料层：至少部分位于贯通孔壁。
  2. 根据权利要求1所述的硅碳材料，其特征在于：所述纳米硅晶粒的晶粒尺寸为d1，所述多孔碳材料的平均孔径为d2，满足：
    d1/d2＝1～15。
  3. 根据权利要求1～2中任一项所述的硅碳材料，其特征在于：所述纳米硅晶粒的晶粒尺寸为d1，所述多孔碳材料的平均孔径为d2，满足：
    d1/d2＝2～10。
  4. 根据权利要求1～3中任一项所述的硅碳材料，其特征在于：所述纳米硅晶粒的晶粒尺寸为d1，d1≥5nm；
    和/或；
    所述多孔碳材料的平均孔径为d2，d2为1.0nm～5.0nm。
  5. 根据权利要求1～4中任一项所述的硅碳材料，其特征在于：所述纳米硅晶粒的晶粒尺寸为d1，d1为5nm～20nm；
    和/或；
    所述多孔碳材料的平均孔径为d2，d2为1.5nm～5.0nm。
  6. 根据权利要求1～5中任一项所述的硅碳材料，其特征在于：所述硅碳复合颗粒物包括封闭孔，所述封闭孔的孔容小于所述贯通孔的孔容。
  7. 根据权利要求1～6中任一项所述的硅碳材料，其特征在于：所述硅碳复合颗粒物包含封闭孔，所述封闭孔的孔容为V1，所述贯通孔的孔容为V2，
    满足：V2/V1＝5～24。
  8. 根据权利要求1～7中任一项所述的硅碳材料，其特征在于：所述硅碳复合颗粒物包含封闭孔，所述封闭孔的孔容为V1，所述贯通孔的孔容为V2，满足：V2/V1＝7～16。
  9. 根据权利要求1～8中任一项所述的硅碳材料，其特征在于：所述封闭孔的孔容为V1，V1为0.04cm3/g～0.16cm3/g；
    和/或；
    所述贯通孔的孔容为V2，V2为0.3cm3/g～1.5cm3/g。
  10. 根据权利要求1～9中任一项所述的硅碳材料，其特征在于：所述贯通孔包含微孔、中孔和大孔，基于所述贯通孔的总体积，所述微孔、所述中孔和所述大孔之间的体积比为(40％～95％):(5％～50％):(0～15％)。
  11. 根据权利要求1～10中任一项所述的硅碳材料，其特征在于：所述碳化硅材料层位于所述贯通孔与所述纳米硅晶粒之间，其中，所述碳化硅材料层的一侧连接所述贯通孔内壁，另一侧连接所述纳米硅晶粒。
  12. 根据权利要求1～11中任一项所述的硅碳材料，其特征在于：所述碳化硅材料层的厚度＜0.7nm。
  13. 根据权利要求1～12中任一项所述的硅碳材料，其特征在于：所述硅碳材料还包括碳包覆层，所述碳包覆层沿所述多孔碳材料的外侧表面设置。
  14. 根据权利要求1～13中任一项所述的硅碳材料，其特征在于：所述多孔碳材料包含多孔碳颗粒物，所述多孔碳颗粒物满足如下条件：
    (1.1)所述多孔碳颗粒物的体积分布粒径满足：Dv50为3.0μm～6.5μm；Dv90为13.5μm～18.5μm；Dv10为0.9μm～2.5μm；
    (1.2)所述多孔碳颗粒物的比表面积为900m2/g～1550m2/g；
    (1.3)所述多孔碳颗粒物的振实密度为0.22g/cm3～0.48g/cm3；
    (1.4)所述多孔碳颗粒物的5吨粉体压实密度为0.45g/cm3～0.80g/cm3。
  15. 根据权利要求1～14中任一项所述的硅碳材料，其特征在于：所述多孔碳材料包含多孔碳颗粒物，所述多孔碳颗粒物满足如下至少一种：
    (2.1)所述多孔碳颗粒物的体积分布粒径满足：Dv50为3.5μm～6.0μm；Dv90为14.0μm～18.0μm；Dv10为1.0μm～2.0μm；
    (2.2)所述多孔碳颗粒物的比表面积为1000m2/g～1500m2/g；
    (2.3)所述多孔碳颗粒物的振实密度为0.25g/cm3～0.45g/cm3；
    (2.4)所述多孔碳颗粒物的5吨粉体压实密度为0.50g/cm3～0.75g/cm3。
  16. 根据权利要求1～15中任一项所述的硅碳材料，其特征在于：基于所述硅碳材料的总质量，所述硅碳材料中硅元素的质量百分比含量为w硅，满足：w硅为38.0％～48.0％。
  17. 根据权利要求1～16中任一项所述的硅碳材料，其特征在于：所述硅碳复合颗粒物满足如下条件：
    (3.1)所述硅碳复合颗粒物的体积分布粒径满足：(Dv90-Dv10)/Dv50为1.2～2.8；
    (3.2)所述硅碳复合颗粒物的比表面积为3.0m2/g～12.0m2/g；
    (3.3)所述硅碳复合颗粒物的振实密度为0.5g/cm3～1.0g/cm3；
    (3.4)所述硅碳复合颗粒物的5吨粉体压实密度为0.80g/cm3～1.1g/cm3。
  18. 根据权利要求1～17中任一项所述的硅碳材料，其特征在于：所述硅碳复合颗粒物满足如下至少一种：
    (4.1)所述硅碳复合颗粒物的体积分布粒径满足：Dv50为3.5μm～9.0μm；Dv90为14.0μm～21.0μm；Dv10为0.9μm～3.0μm；
    (4.2)所述硅碳复合颗粒物的比表面积为5.0m2/g～10.0m2/g；
    (4.3)所述硅碳复合颗粒物的振实密度为0.6g/cm3～0.8g/cm3；
    (4.4)所述硅碳复合颗粒物的5吨粉体压实密度为0.90g/cm3～1.05g/cm3。
  19. 根据权利要求1～18中任一项所述的硅碳材料，其特征在于：所述硅碳复合颗粒物的性能如下：
    所述硅碳复合颗粒物在4Mpa下的粉末电阻率为1.30Ω·cm～3.80Ω·cm；
    和/或；
    所述硅碳复合颗粒物的脱锂比容量为1300mAh/g～1500mAh/g，首次库伦效率为77％～81％；
    和/或；
    所述硅碳复合颗粒物的dQ/dV曲线中，I1为0.3V～0.35V附近的峰强度；I2为0.43V～0.50V附近的峰强度；满足：I1/I2＝1.4～1.8；所述硅碳复合颗粒物的dQ/dV曲线包含以所述硅碳复合颗粒物为正极活性材料，金属锂片为对电极，组装形成CR2430型扣式电池，25℃下，充放电电压为0.005V～2.0V，对充放电容量，工作电极电势进行微分处理得到。
  20. 一种权利要求1～19中任一项所述的硅碳材料的制备方法，其特征在于：包括：
    提供多孔碳基材；
    向所述多孔碳基材中通入硅源，生成包含纳米硅晶粒及碳化硅材料层的多孔碳材料；向所述包含纳米硅晶粒及碳化硅材料层的多孔碳材料中通入碳源，生成包含碳包覆层的硅碳材料。
  21. 根据权利要求20所述的硅碳材料的制备方法，其特征在于：所述生成包含纳米硅晶粒及碳化硅材料层的多孔碳材料的反应条件如下：
    (5.1)反应温度为500℃～700℃，通入硅源时间为3h～42h；
    (5.2)所述硅源包含硅源气体与稀释气体，所述硅源气体的体积百分数为15％～95％；所述硅源气体包含甲硅烷，乙硅烷中的任一种或两种；
    (5.3)所述硅源的通气量为0.2L/min～1.5L/min。
  22. 根据权利要求20～21中任一项所述的硅碳负极材料的制备方法，其特征在于：所述多孔碳基材包含碳元素、氧元素及氮元素，所述碳元素与所述氧元素及所述氮元素的质量比为(94％～97％):(2％～4％):(1％～2％)；
    和/或；所述多孔碳基材的灰分≤0.5％。
  23. 一种二次电池，包含负极极片，其特征在于：所述负极极片包含权利要求1～19中任一项所述的硅碳负极材料或权利要求20～22中任一项所述的制备方法制得的硅碳材料。
  24. 一种用电装置，其特征在于：包含权利要求23所述的二次电池。
PCT/CN2024/108434 2024-03-15 2024-07-30 硅碳材料及其制备方法与二次电池及用电装置 Pending WO2025189643A1 (zh)

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