Negative electrode material, method for preparing the same, and lithium ion battery

Abstract

The present disclosure belongs to the technical field of secondary batteries, and particularly relates to a negative electrode material, a method for preparing the same, and a lithium ion battery. The peak coefficient A of the particle size distribution of the negative electrode material satisfies 0 < A ≤ 3, and A = (D 95 - D5) / [2.5×(D 75 - D 25 )], where D 95 , D5, D 75 , D 25 respectively represent the particle sizes of the negative electrode material when the volume content reaches 95%, 5%, 75%, and 25% in the cumulative curve. The negative electrode material according to the present disclosure has an appropriate peak coefficient A, can guarantee the consistency of the negative electrode material particles. Therefore, the consistency of the coated electrode plate is good, the performance consistency of the battery is high, and the performance of the battery is improved.

Description

Technical Field

[0001] The present disclosure belongs to the technical field of secondary batteries, and particularly relates to a negative electrode material, a method for preparing the same, and a lithium-ion battery.

[0002] Cross-reference to Related Applications The present disclosure claims priority based on a Chinese application filed with the Chinese Patent Office on April 21, 2022, with an application number of CN2022104270714 and a title of "Negative Electrode Material, Method for Preparing the Same, and Lithium-Ion Battery", and a Chinese application filed with the Chinese Patent Office on June 30, 2022, with an application number of CN2022107696009 and a title of "Silicon-Based Negative Electrode Material, Method for Preparing the Same, and Lithium-Ion Battery", and all of its content is incorporated herein by reference.

Background Art

[0003] With the expansion and deepening of the application of lithium-ion batteries, the requirements for the performance of lithium-ion batteries are also increasing. In particular, in terms of the energy density of the battery, the conventional graphite negative electrode material has a relatively low specific capacity per gram theoretically, so it cannot meet the increasing market requirements day by day. In recent years, as a negative electrode material with a high specific capacity, silicon-based materials have attracted attention.

[0004] The silicon-based negative electrode material has a specific capacity exceeding 3000 mAh / g, but when applied to a lithium-ion battery, compared with the graphite material, it has relatively poor cycle stability and a relatively high battery expansion rate, so its actual application is limited. Therefore, it is important to develop a material with good cycle stability and a low expansion rate.

[0005] Improving the cycle expansion performance of a lithium-ion battery may be achieved by improving the characteristics such as the chemical structure and conductivity of the battery materials, or by adjusting the characteristics of the battery materials to improve the characteristics of the battery electrode plate. For example, it can be achieved by improving the uniformity and consistency of the distribution of material particles in the electrode plate. However, conventionally, there has been a problem that the material particles in the electrode plate are unevenly distributed and have low consistency.

Summary of the Invention

[0006] The present disclosure provides a negative electrode material. The peak coefficient A of the particle size distribution of the negative electrode material satisfies 0 < A ≤ 3, and A = (D 95 - D5) / [2.5 * (D 75 - D 25 )], where D 95 , D5, D 75 , D 25 represent the particle sizes of the negative electrode material when the volume content reaches 95%, 5%, 75%, and 25% in the cumulative curve, respectively. The negative electrode material contains a silicon-based active material, and the silicon-based active material contains at least one of SiO x , SiO x / C, SiO x / M, Si, Si / C, and Si / M, where x satisfies 0 < x ≤ 2, and M contains at least one of a metal, a non-metal, a metal oxide, and a non-metal oxide.

[0007] Optionally, for the particle size distribution of the negative electrode material, 0 < D5 ≤ 65 μm, 0 < D 25 ≤ 69 μm, 0 < D 75 ≤ 75 μm, 0 < D 95 ≤ 79 μm are satisfied.

[0008] Optionally, in the infrared reflection spectrum measurement of the negative electrode material, a broad peak exists in the range of a wave number of 3200 cm -1 ~3600 cm -1 .

[0009] Optionally, the Wadell sphericity of the negative electrode material is 0.8 or more.

[0010] Optionally, the particle size D50 of the silicon-based active material is greater than 0 μm and less than or equal to 80 μm.

[0011] Optionally, the specific surface area of the silicon-based active material is 0 to 10 m 2 / g and is not 0.

[0012] Optionally, the tap density of the silicon-based active material is 0.5 g / m 3 ~2 g / m 3 is.

[0013] Optionally, the negative electrode material further includes a dopant doped in the silicon-based active material.

[0014] Optionally, the negative electrode material further includes a dopant doped in the silicon-based active material, and the dopant includes at least one of an alkali metal, an alkaline earth metal, an alkali metal oxide, and an alkaline earth metal oxide.

[0015] Optionally, the negative electrode material further includes a dopant doped in the silicon-based active material, and the weight percentage b of the dopant in the negative electrode material satisfies 0 < b ≤ 20%.

[0016] Optionally, the selection coefficient B of the particle size distribution of the negative electrode material satisfies 0 < B ≤ 3, and B = (D 84 - D 16 ) / 4 + (D 95 - D5) / 6.6, where D 84 , D 16 , D 95 , D5 represent the particle sizes of the negative electrode material when the volume content reaches 84%, 16%, 95%, and 5% in the cumulative curve, respectively.

[0017] Optionally, as the particle size distribution of the negative electrode material, 0 < D5 ≤ 65 μm, 0 < D 16 ≤ 67 μm, 0 < D 84 ≤ 77 μm, 0 < D 95 ≤ 79 μm are satisfied.

[0018] Optionally, the selection coefficient B of the particle size distribution of the negative electrode material and the peak coefficient A satisfy 0 < B / A ≤ 5.

[0019] Optionally, the negative electrode material further includes a coating layer formed on the surface of the silicon-based active material, and the coating layer includes at least one of a flexible polymer and a conductive material.

[0020] Optionally, the conductive material includes flaky graphite and a nanocarbon material.

[0021] Optionally, the flexible polymer includes at least one of a natural flexible polymer and an artificial flexible polymer.

[0022] Optionally, the flexible polymer includes at least one of polyolefin and its derivatives, polyvinyl alcohol and its derivatives, polyacrylic acid and its derivatives, polyamide and its derivatives, carboxymethyl cellulose and its derivatives, alginic acid and its derivatives, and polycarbonate and its derivatives.

[0023] Optionally, the weight average molecular weight of the flexible polymer is 2000 to 1000000.

[0024] Optionally, the flexible polymer contains a thermally crosslinkable functional group, and the thermally crosslinkable functional group includes at least one of an epoxy group, a carboxy group, a hydroxy group, an amino group, a double bond, and a triple bond.

[0025] Optionally, the flaky graphite includes at least one of natural flaky graphite and artificial flaky graphite.

[0026] Optionally, the nanocarbon material includes at least one of conductive graphite, graphene, carbon nanotubes, and nanocarbon fibers.

[0027] Optionally, when the total mass of the negative electrode material is 100%, the mass percentage content of the flexible polymer is 0 to 10% and 0 is not included.

[0028] Optionally, when the total mass of the negative electrode material is 100%, the mass percentage content of the flaky graphite is 0 to 20% and 0 is not included.

[0029] Optionally, when the total mass of the negative electrode material is 100%, the mass percentage content of the nanocarbon material is 0 to 5% and 0 is not included.

[0030] Optionally, the thickness of the coating layer is 10 nm to 5000 nm.

[0031] Optionally, the mass ratio of the coating layer in the negative electrode material is 0 to 20% and 0 is not included.

[0032] Optionally, the mass ratio of the coating layer in the negative electrode material is 2% to 10%.

[0033] The present disclosure further provides a method for preparing a negative electrode material. The preparation method includes a step of preparing a powdery negative electrode material, and a step of adjusting the particle size of the prepared powdery negative electrode material to obtain a negative electrode material. The peak coefficient A of the particle size distribution of the negative electrode material satisfies 0 < A ≤ 3, and A = (D 95 - D5) / [2.5*(D 75 - D 25 )], where D 95 , D5, D 75 , D 25 respectively represent the particle sizes of the negative electrode material when the volume content reaches 95%, 5%, 75%, and 25% in the cumulative curve. The negative electrode material contains a silicon-based active material, and the silicon-based active material includes at least one of SiO x , SiO x / C, SiO x / M, Si, Si / C, and Si / M. x satisfies 0 < x ≤ 2, and M includes at least one of a metal, a nonmetal, a metal oxide, and a nonmetal oxide.

[0034] Optionally, the selection coefficient B of the particle size distribution of the negative electrode material satisfies 0 < B ≤ 3, and B = (D 84 - D 16 ) / 4 + (D 95 - D5) / 6.6, where D 84 , D 16 , D 95 , D5 represent the particle sizes when the volume content reaches 84%, 16%, 95%, and 5% in the cumulative curve, respectively.

[0035] Optionally, the method for preparing the powdery negative electrode material includes the step of pulverizing the silicon-based active material to obtain the powdery negative electrode material.

[0036] Optionally, the pulverization method includes crushing and ball milling.

[0037] Optionally, the device used for the crushing includes a crusher, and the crushing power p of the crusher satisfies 0 < p ≤ 300 kW.

[0038] Optionally, the device used for the ball milling includes a ball mill, and the rotational speed v1 of the ball mill satisfies 0 < v1 ≤ 1500 rpm.

[0039] Optionally, the device used for the particle size adjustment includes a classifier, and the frequency f of the induced draft fan of the classifier satisfies 0 < f ≤ 100 Hz.

[0040] Optionally, the selection coefficient B and the peak coefficient A satisfy 0 < B / A ≤ 5.

[0041] Optionally, the median particle size D50 of the silicon-based active material is greater than 0 μm and less than or equal to 80 μm.

[0042] Optionally, the method for preparing the powdery negative electrode material further includes the step of carbon coating the pulverized silicon-based active material with a carbon material to obtain the powdery negative electrode material, and the weight percentage a of the carbon material in the negative electrode material satisfies 0 < a ≤ 15%.

[0043] Optionally, the method for preparing the powdery anode material further includes the step of obtaining the powdery anode material by performing polymer coating on the pulverized silicon-based active material or performing carbon coating on the pulverized silicon-based active material with a carbon material.

[0044] Optionally, the polymer coating method includes the steps of dissolving a flexible polymer in a solvent to obtain a flexible polymer solution, adding a conductive material containing the flaky graphite and the nanocarbon material to the flexible polymer solution while stirring to obtain a mixed coating solution, adding a poor solvent to the mixed coating solution, stirring to obtain a supersaturated mixed coating solution, adding a silicon-based active material to the supersaturated mixed coating solution while stirring, stirring and separating to obtain a precursor of the anode material, and performing heat treatment on the precursor of the anode material to obtain the powdery anode material.

[0045] Optionally, the flexible polymer contains a thermally crosslinkable functional group, and the thermally crosslinkable functional group includes at least one of an epoxy group, a carboxy group, a hydroxy group, an amino group, a double bond, and a triple bond.

[0046] Optionally, the solvent includes at least one of water, methanol, ethanol, polypyrrolidone, isopropanol, acetone, petroleum ether, tetrahydrofuran, ethyl acetate, N,N-dimethylacetamide, N,N-dimethylformamide, n-hexane, and halogenated hydrocarbons.

[0047] Optionally, the poor solvent includes a poor solvent for the flexible polymer.

[0048] Optionally, the poor solvent includes at least one of methanol, ethanol, polypyrrolidone, isopropanol, acetone, petroleum ether, tetrahydrofuran, ethyl acetate, N,N-dimethylacetamide, N,N-dimethylformamide, n-hexane, and halogenated hydrocarbons.

[0049] Optionally, the temperature of the heat treatment is 100°C to 400°C.

[0050] Optionally, the time of the heat treatment is 2 h to 12 h.

[0051] Optionally, the method for preparing the powdery anode material further includes doping a dopant into the powdered silicon-based active material to obtain the powdery anode material.

[0052] Optionally, the dopant includes at least one of an alkali metal, an alkaline earth metal, an alkali metal oxide, and an alkaline earth metal oxide.

[0053] Optionally, the weight percentage b of the dopant in the anode material satisfies 0 < b ≤ 20%.

[0054] The present disclosure further provides a lithium-ion battery. The lithium-ion battery includes the anode material according to any one of the above items or the anode material prepared by the preparation method according to any one of the above items.

Brief Description of the Drawings

[0055]

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Modes for Carrying Out the Invention

[0056] The following are exemplary embodiments of the present disclosure. Those skilled in the art can make some improvements and modifications on the premise of not departing from the principles of the embodiments of the present disclosure, and such improvements and modifications also belong to the protection scope of the embodiments of the present disclosure.

[0057] Definition of Terms The term "particle size" used in this specification can be used interchangeably with the term "particle diameter" and refers to the size of particles. The particle size of spherical particles is represented by the diameter. For irregular particles, the diameter of a sphere having the same physical properties as the particle is defined as the equivalent diameter of the particle.

[0058] The term "cumulative curve" used in this specification is also called "cumulative frequency curve" and is a method of graphically representing the cumulative frequency of sediment (gravel).

[0059] The term "wadell sphericity" used in this specification represents how close the shape of a particle is to a sphere and is usually defined as the ratio of the surface area of a sphere having the same volume as the measured particle to the surface area of the measured particle. As an equation, sphericity = surface area of a sphere having the same volume as the particle obtained by calculation / specific surface area of the particle measured by a specific surface area measuring device.

[0060] One embodiment of the present disclosure provides a negative electrode material (silicon-based negative electrode material). The peak coefficient A of the particle size distribution of the negative electrode material satisfies 0 < A ≤ 3, and A = (D 95 - D5) / [2.5*(D 75 - D 25 )], where D 95 , D5, D 75 , D 25 represent the particle sizes when the volume content reaches 95%, 5%, 75%, and 25% in the cumulative curve, respectively.

[0061] The negative electrode material includes a silicon-based active material (active material), and the silicon-based active material includes at least one of SiO x , SiO x / C, SiO x / M, Si, Si / C, and Si / M, where 0 < x ≤ 2 and M includes at least one of metal, non-metal, metal oxide, and non-metal oxide.

[0062] In some embodiments, SiO x may be a single compound, such as SiO2, or a multiphase compound, such as a material composed of one or more of SiO2, SiO 1.5 , SiO, SiO 0.5 , etc., or a composite material including Si and SiO2.

[0063] In some embodiments, SiO x / C is a SiO x material containing carbon.

[0064] In some embodiments, SiO x / M may be a composite material including SiO x and M, or a composite material including a material containing Si and a material containing three elements or components of M, Si, and O.

[0065] In some embodiments, Si / M is a composite material containing two elements or components of Si and M. In the above solution, by adjusting the particle size (grain size) of the anode material to obtain an anode material with an appropriate particle size distribution, problems such as relatively poor conductivity performance, cycle performance, and rate performance of the conventional anode material can be solved. In this case, if the peak coefficient A of the particle size of the anode material is adjusted to satisfy 0 < A ≤ 3, the distribution is more concentrated at both ends of the particle size (grain size) distribution curve (i.e., particle size distribution) of the anode material, and there are no particles with a grain size significantly different from the median diameter. Optionally, the peak coefficient A is, for example, 0.5, 1, 1.2, 1.5, 1.8, 2, 2.5, 2.8, or 3, or is a range defined by any two of the above values, but it may also be other values within the above range and is not limited here. By reasonably selecting the peak coefficient A of the particle size distribution, the consistency of each particle of the anode material is guaranteed, thereby improving the stability of the slurry when preparing and coating the anode material slurry. The better the distribution consistency of the adhesive and conductive agent on the surfaces of different particles of the anode material, the better the consistency of the coated electrode plate, and the higher the consistency of the expansion and contraction of different particles during the charge and discharge process. Therefore, the electrode plate is not easily damaged due to uneven expansion and contraction of particles locally, the cycle performance of the battery does not deteriorate, and the expansion of the battery does not increase. Therefore, the consistency of the battery performance is improved. And to prevent large variations in the particle size of the material particles, the conductive agent adheres uniformly and effectively to each material particle, improving the rate performance of the battery. By specifying the silicon-based active material in the anode material, the prepared anode material can have an ideal high specific capacity. When A is greater than 3, there are particles in the material with a grain size significantly different from the median diameter, so the difference in the particle size of each particle of the material is relatively large. After forming the electrode plate by coating, during the cycle process of the battery, stress is concentrated locally, the electrode plate becomes powdered and then falls off, and the battery immediately fails to function.

[0066] Hereinafter, this case will be described in detail. In some embodiments, as the particle size distribution of the anode material, 0 < D5 ≤ 65 μm, 0 < D 25 ≤ 69 μm, 0 < D 75≤ 75 μm, 0 < D 95 satisfies ≤ 79 μm.

[0067] In some embodiments, the sorting coefficient B of the particle size distribution of the negative electrode material satisfies 0 < B ≤ 3, and B = (D 84 - D 16 ) / 4 + (D 95 - D5) / 6.6, where D 84 , D 16 , D 95 , and D5 represent the particle sizes of the negative electrode material when the volume content reaches 84%, 16%, 95%, and 5% respectively in the cumulative curve.

[0068] In this case, by selecting the sorting coefficient B of the particle size distribution of the negative electrode material to satisfy 0 < B ≤ 3, it can be ensured that the particle size of the negative electrode material is more concentrated in the middle part (between both sides) of the particle size distribution curve. Thereby, when manufacturing the electrode plate with the negative electrode material and the adhesive, the adhesive can be evenly distributed, improving the peel strength of the electrode plate and contributing to the construction of a stable and complete conductive network by the electrode plate.

[0069] By selecting the sorting coefficient B of the particle size, the particle size distribution of the negative electrode material can be concentrated. Optionally, the sorting coefficient B is, for example, 0.5, 1, 1.2, 1.5, 1.8, 2, 2.5, 2.8, or 3, or a range defined by any two of the above values, but other values within the above range are also possible and are not limited herein.

[0070] In some embodiments, as the particle size distribution of the negative electrode material, 0 < D5 ≤ 65 μm, 0 < D 16 ≤ 67 μm, 0 < D 84 ≤ 77 μm, 0 < D 95 ≤ 79 μm are satisfied.

[0071] In some embodiments, the sorting coefficient B and the peak coefficient A satisfy 0 < B / A ≤ 5.

[0072] Optionally, the ratio B / A of the selection coefficient B to the peak coefficient A is 0.5, 0.8, 1, 1.2, 1.5, 1.8, 2, 2.5, 2.8, 3, 3.2, 3.5, 3.8, 4, 4.2, 4.5, 4.8 or 5, etc., or is a range defined by any two of the above values, but may also be other values within the above range and is not limited herein. Although not bound by theory, by specifying the ratio B / A of the selection coefficient B to the peak coefficient A, agglomeration of the silicon-based active material particles can be effectively prevented, and high performance of the battery can be effectively exerted. When B / A exceeds 5, agglomeration of the silicon-based active material particles occurs during the preparation and coating of the negative electrode material slurry, impairing the performance of the battery.

[0073] In some embodiments, by infrared reflection spectrum measurement of the negative electrode material, there is a broad peak within the range of a wave number of 3200 cm -1 ~3600 cm -1 . As can be seen from this, the negative electrode material according to the present disclosure has a polar group such as an -OH group and can contribute to the bonding between the negative electrode material and the adhesive.

[0074] In some embodiments, the Wadell sphericity of the negative electrode material is 0.6 or more. The higher the sphericity, the more significantly the consistency of the electrode plate is improved.

[0075] In some embodiments, the Wadell sphericity of the negative electrode material is 0.8 or more. Optionally, the Wadell sphericity of the negative electrode material is 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, etc., or is a range defined by any two of the above values.

[0076] In some embodiments, the negative electrode material further includes a coating layer formed on the surface of the silicon-based active material, and the coating layer includes at least one of a flexible polymer and a conductive material. In some embodiments, the conductive material includes at least one of flaky graphite or a nanocarbon material.

[0077] In some embodiments, the flexible polymer comprises at least one of a natural flexible polymer and a synthetic flexible polymer.

[0078] In some embodiments, the flexible polymer comprises at least one of polyolefin and its derivatives, polyvinyl alcohol and its derivatives, polyacrylic acid and its derivatives, polyamide and its derivatives, carboxymethyl cellulose and its derivatives, alginic acid and its derivatives, and polycarbonate and its derivatives.

[0079] In some embodiments, the weight-average molecular weight of the flexible polymer is from 2,000 to 1,000,000. Without being bound by theory, if the weight-average molecular weight of the flexible polymer is within the above range, the aggregation phenomenon of the negative electrode material can be effectively prevented, and the buffering effect of the flexible polymer on the negative electrode material can be better exerted.

[0080] Optionally, the weight-average molecular weight of the flexible polymer is, for example, from 5,000 to 500,000, from 10,000 to 100,000 or from 50,000 to 90,000, and is, for example, 2,000, 3,000, 4,000, 5,000, 6,000, 7,000, 8,000, 9,000, 10,000, 20,000, 30,000, 50,000, 80,000, 100,000, 200,000, 300,000, 500,000, 800,000 or 1,000,000, etc., or is a range defined by any two of the above values, but may also be other values within the above range and is not limited herein.

[0081] In some embodiments, the flexible polymer contains a thermally crosslinkable functional group, and the thermally crosslinkable functional group comprises at least one of an epoxy group, a carboxyl group, a hydroxyl group, an amino group, a double bond and a triple bond.

[0082] In some embodiments, the flaky graphite comprises at least one of natural flaky graphite and synthetic flaky graphite.

[0083] In some embodiments, the nanocarbon material includes at least one of conductive graphite, graphene, carbon nanotubes, and nanocarbon fibers.

[0084] In some embodiments, when the total mass of the anode material is 100%, the mass percentage content of the flexible polymer is 0 to 10% and 0 is not included. Without being bound by theory, if the mass percentage content of the flexible polymer is within the above range, the aggregation phenomenon of the anode material can be effectively prevented, and the buffering effect of the flexible polymer on the anode material can be effectively exerted, without impairing the ideal high specific capacity of the anode material according to the present disclosure.

[0085] Optionally, when the total mass of the anode material is 100%, the mass percentage content of the flexible polymer is, for example, 0.1% to 8.5%, 1% to 7.5%, or 2.5% to 5%, and is, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%, etc., or is a range defined by any two of the above values, but may also be other values within the above range and is not limited herein.

[0086] In some embodiments, when the total mass of the anode material is 100%, the mass percentage content of flake graphite is 0 to 20% and 0 is not included. Without being bound by theory, if the mass percentage content of flake graphite is within the above range, the aggregation phenomenon of the material in the combination process can be prevented, and the conductivity of flake graphite can be effectively exerted, without impairing the ideal high specific capacity of the anode material according to the present disclosure. Optionally, when the total mass of the anode material is 100%, the mass percentage content of flake graphite is, for example, 0.1% to 16%, 1% to 14%, or 5% to 8%, and is, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%, etc., or is a range defined by any two of the above values, but may also be other values within the above range and is not limited herein.

[0087] In some embodiments, when the total mass of the negative electrode material is 100%, the mass percentage content of the nanocarbon material is 0 to 5% and 0 is not included. Without being bound by theory, if the mass percentage content of the nanocarbon material is within the above range, the aggregation phenomenon of the materials in the combination process can be prevented, the conductive characteristics of the nanocarbon material can be effectively exerted, and the high specific capacity of the negative electrode material according to the present disclosure will not be impaired.

[0088] Optionally, when the total mass of the negative electrode material is 100%, the mass percentage content of the nanocarbon material is, for example, 0.1% to 4.6%, 0.9% to 4.1% or 1.9% to 2.1%, and is, for example, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5% or 5%, etc., or is a range defined by any two of the above values, but may also be other values within the above range and is not limited herein.

[0089] In some embodiments, the thickness of the coating layer is 10 nm to 5000 nm.

[0090] Optionally, the thickness of the coating layer is, for example, 50 nm to 1000 nm, 100 nm to 800 nm or 300 nm to 500 nm, and is, for example, 10 nm, 50 nm, 100 nm, 200 nm, 500 nm, 800 nm, 1000 nm, 2000 nm, 3000 nm, 4000 nm or 5000 nm, etc., or is a range defined by any two of the above values, but may also be other values within the above range and is not limited herein.

[0091] In some embodiments, the mass ratio of the coating layer in the negative electrode material is 0 to 20% and 0 is not included.

[0092] Optionally, the mass ratio of the coating layer in the anode material is, for example, 2% to 18%, 4% to 15% or 6% to 12%, and for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%, etc., or a range defined by any two values, but other values within the above range may also be used and are not limited herein.

[0093] In some embodiments, the mass ratio of the coating layer in the anode material is 2% to 10%.

[0094] Without being bound by theory, if the thickness and ratio of the coating layer of the anode material are within the above ranges according to the present disclosure, the buffering effect on the anode material can be effectively exerted, the conductivity of the anode material can be effectively guaranteed, and the high specific capacity of the anode material according to the present disclosure will not be impaired.

[0095] In some embodiments, the particle size D50 of the silicon-based active material is greater than 0 μm and less than or equal to 80 μm, and the measurement method of the particle size includes the laser light scattering method. Optionally, the particle size D50 of the silicon-based active material is, for example, 10 μm to 70 μm, 20 μm to 60 μm or 30 μm to 50 μm, and for example, 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm or 80 μm, etc., or a range defined by any two values, but other values within the above range may also be used and are not limited herein. Without being bound by theory, by reasonably selecting the particle size of the silicon-based active material, the cycle performance, expansion performance, etc. of the battery manufactured from the lithium-ion battery anode material can be guaranteed. When the particle size D50 of the silicon-based active material exceeds 80 μm, the cycle performance and expansion performance of the battery are impaired.

[0096] In some embodiments, the specific surface area of the silicon-based active material is 0 to 10 m 2 / g and is not 0. Optionally, the specific surface area of the silicon-based active material is, for example, 1 m 2 / g to 9 m 2 / g, 2m 2 / g to 8m 2 / g or 3m 2 / g to 7m 2 / g, for example 1m 2 / g, 2m 2 / g, 3m 2 / g, 4m 2 / g, 5m 2 / g, 6m 2 / g, 7m 2 / g, 8m 2 / g, 9m 2 / g or 10m 2 / g etc., or a range defined by any two values, but may also be other values within the above range and is not limited here. Without being bound by theory, if the specific surface area of the silicon-based active material is within the above range, the high specific capacity and high initial Coulomb efficiency of the negative electrode material according to the present disclosure can be guaranteed.

[0097] In some embodiments, the tap density of the silicon-based active material is 0.5 g / m 3 to 2 g / m 3 Optionally, the tap density of the silicon-based active material is 0.7 g / m 3 to 1.8 g / m 3 , 0.9 g / m 3 to 1.6 g / m 3 or 1.0 g / m 3 to 1.4 g / m 3 For example 0.5 g / m 3 , 0.6 g / m 3 , 0.8 g / m 3 , 1.0 g / m 3 , 1.2 g / m 3 , 1.5 g / m 3 , 1.8 g / m 3 or 2 g / m 3 etc., or a range defined by any two values, but may also be other values within the above range and is not limited here. Without being bound by theory, if the tap density of the silicon-based active material is within the above range, the high specific capacity and high initial Coulomb efficiency of the negative electrode material according to the present disclosure can be guaranteed.

[0098] In some embodiments, the negative electrode material further includes a dopant doped in the silicon-based active material, and the dopant includes at least one of an alkali metal, an alkaline earth metal, an alkali metal oxide, and an alkaline earth metal oxide.

[0099] In some embodiments, the weight percentage b of the dopant in the negative electrode material satisfies 0 < b ≤ 20%.

[0100] Optionally, the alkali metal is one selected from lithium, sodium, and potassium. The alkaline earth metal is selected from magnesium, calcium, strontium, and barium. The alkali metal oxide is selected from lithium oxide, sodium oxide, and potassium oxide. The alkaline earth metal oxide is selected from magnesium oxide, calcium oxide, strontium oxide, and barium oxide. The weight percentage b of the dopant in the negative electrode material is, for example, 1%, 3%, 5%, 8%, 10%, 12%, 15%, 18%, or 20%, or a range defined by any two values, but may also be other values within the above range and is not limited herein. Without being bound by theory, doping the silicon-based active material with a metal material can increase the intrinsic conductivity of the silicon-based active material, and further, by selecting the type and content of the dopant, the conductivity of the silicon-based active material can be increased more effectively.

[0101] The negative electrode materials according to the above embodiments can be arbitrarily combined as long as there is no contradiction. For example, the particle size of the silicon-based active material and the specific surface area of the silicon-based active material may be limited together.

[0102] One embodiment of the present disclosure further provides a method for preparing a negative electrode material. The preparation method includes the following steps. Step S100: Prepare a powdery negative electrode material. Step S200: Adjust the particle size of the prepared powdery negative electrode material to obtain a negative electrode material. The peak coefficient A of the particle size distribution of the negative electrode material satisfies 0 < A ≤ 3, and A = (D95 -(D5) / [2.5*(D 75 -D 25 )], where D 95 , D5, D 75 , D 25 represent the particle sizes of the negative electrode material when the volume content reaches 95%, 5%, 75%, and 25% respectively in the cumulative curve. The negative electrode material contains a silicon-based active material, and the silicon-based active material includes at least one of SiO x , SiO x / C, SiO x / M, Si, Si / C, and Si / M, where 0 < x ≤ 2 is satisfied, and M includes at least one of a metal, a non-metal, a metal oxide, and a non-metal oxide.

[0103] In some embodiments, the selection coefficient B of the particle size distribution of the negative electrode material satisfies 0 < B ≤ 3, and B = (D 84 -D 16 ) / 4 + (D 95 -D5) / 6.6, where D 84 , D 16 , D 95 , D5 represent the particle sizes when the volume content reaches 84%, 16%, 95%, and 5% respectively in the cumulative curve.

[0104] In some embodiments, the method for preparing the powdery negative electrode material further includes a step of pulverizing the silicon-based active material to obtain the powdery negative electrode material.

[0105] In the above solution, in the method for preparing the powdery negative electrode material, first, the silicon-based active material is pulverized to obtain a powdery negative electrode material with an appropriate particle size, and then by reasonably selecting the peak coefficient A of the particle size of the powdery negative electrode material, a silicon-based negative electrode material with an appropriate particle size distribution can be obtained. Thereby, problems such as low initial Coulomb efficiency, relatively poor conductivity, and relatively poor cycle performance and rate performance when using the conventional silicon-based active material as the negative electrode material can be solved.

[0106] In some embodiments, the pulverization method includes crushing and ball milling.

[0107] In some embodiments, the device used for crushing includes a crusher, and the crushing power p of the crusher satisfies 0 < p ≤ 300 kW.

[0108] In some embodiments, the device used for ball milling includes a ball mill, and the rotational speed v1 of the ball mill satisfies 0 < v1 ≤ 1500 rpm.

[0109] In some embodiments, the device used for particle size adjustment includes a classifier, and the frequency f of the induced draft fan of the classifier satisfies 0 < f ≤ 100 Hz.

[0110] In some embodiments, the separation coefficient B and the peak coefficient A satisfy 0 < B / A ≤ 5.

[0111] In some embodiments, the particle size D50 of the silicon-based active material is greater than 0 μm and less than or equal to 80 μm.

[0112] Optionally, the crushing power p of the crusher is, for example, 40 kW to 260 kW, 80 kW to 210 kW or 120 kW to 180 kW, and is, for example, 5 kW, 10 kW, 20 kW, 50 kW, 100 kW, 150 kW, 200 kW, 250 kW or 300 kW, etc., or is a range defined by any two values. The rotational speed v1 of the ball mill is, for example, 50 rpm to 1400 rpm, 300 rpm to 1200 rpm or 500 rpm to 900 rpm, and is, for example, 200 rpm, 400 rpm, 600 rpm, 800 rpm, 1000 rpm, 1200 rpm or 1500 rpm, etc., or is a range defined by any two values, but may be other values within the above ranges and is not limited herein. Without being bound by theory, by reasonably selecting the crushing power p of the crusher and the rotational speed v1 of the ball mill used in the pulverization process, a silicon-based active material with an appropriate particle size can be obtained, which can contribute to subsequent particle size adjustment.

[0113] Optionally, the frequency f of the induced draft fan of the classifier is, for example, 6 Hz to 95 Hz, 25 Hz to 75 Hz or 35 Hz to 65 Hz, such as 1 Hz, 5 Hz, 10 Hz, 20 Hz, 30 Hz, 50 Hz, 70 Hz, 90 Hz or 100 Hz, etc., or a range defined by any two values, but other values within the above ranges may also be used and are not limited herein. Although not restricted by theory, by reasonably selecting the frequency f of the induced draft fan of the classifier, the sorting coefficient B and the peak coefficient A of the particle size distribution of the negative electrode material will satisfy 0 < B ≤ 3 and 0 < A ≤ 3, respectively.

[0114] Optionally, the D50 particle size of the silicon-based active material is, for example, 4 μm to 80 μm, 25 μm to 75 μm or 45 μm to 65 μm, such as 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm or 80 μm, etc., or a range defined by any two values, but other values within the above ranges may also be used and are not limited herein. Although not restricted by theory, by reasonably selecting the particle size of the silicon-based active material, the cycle performance, swelling performance, etc. of the battery manufactured with the lithium-ion battery negative electrode material can be guaranteed. When the D50 particle size of the silicon-based active material exceeds 80 μm, the cycle performance and swelling performance of the battery will be impaired.

[0115] In some embodiments, the method for preparing the powdery negative electrode material further includes the step of carbon coating the powdered silicon-based active material with a carbon material to obtain the powdery negative electrode material, and the weight percentage a of the carbon material in the negative electrode material satisfies 0 < a ≤ 15%.

[0116] Optionally, the weight percentage a of the carbon material in the negative electrode material is 2.5% - 14.5%, 4.5% - 10.5% or 6.5% - 8.5%, for example 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%, etc., or a range defined by any two values, but other values within the above range are also possible and are not limited herein. Without being bound by theory, by adding a carbon material to the negative electrode material and coating the surface of the silicon-based active material with the carbon material, the volume change and conductivity problems of the silicon-based lithium-ion battery negative electrode material in the lithium-ion insertion / desorption process can be effectively solved.

[0117] In some embodiments, the carbon coating method includes the step of mixing a third raw material including a calcined product and an organic carbon source and performing heat treatment in a protective atmosphere or a vacuum environment.

[0118] The above carbon coating method includes the step of mixing a third raw material including the above calcined product and an organic carbon source and performing heat treatment in a protective atmosphere or a vacuum environment.

[0119] Specifically, as the above carbon coating, at least one of vapor-phase carbon coating and solid-phase carbon coating is included.

[0120] In some embodiments, the carbon coating according to the present disclosure adopts a vapor-phase carbon coating method. The specific method is to heat the above calcined product to 600°C - 1000°C in a protective atmosphere, introduce an organic carbon source gas, keep it warm for 0.5 h (hours) - 10 h (hours), and then cool it. The organic carbon source gas can be a hydrocarbon-based (such as alkanes, naphthenic hydrocarbons, olefins, alkynes, and aromatic hydrocarbons, etc.), for example, at least one of methane, ethylene, acetylene, and benzene.

[0121] Optionally, in the gas-phase carbon coating method, the heat treatment temperature is specifically, for example, 650°C to 950°C, 750°C to 850°C or 780°C to 820°C, such as 600°C, 700°C, 800°C, 900°C, 1000°C, etc. The heat treatment holding time is specifically, for example, 1.0 h to 9.0 h, 3.0 h to 7.0 h or 5.0 h to 6.0 h, such as 0.5 h, 1.5 h, 2.5 h, 3.5 h, 4.5 h, 5.5 h, 6.5 h, 7.5 h, 8.5 h, 9.5 h, 10 h, etc., or a range defined by any two values, not limited here. Optionally, the heat treatment temperature is 700°C to 900°C, and the heat treatment holding time is 3 h to 9 h.

[0122] In some embodiments, the carbon coating according to the present disclosure adopts a solid-phase carbon coating method. The specific method includes fusing the above-mentioned fired product and carbon source for 0.5 h or more, carbonizing the obtained carbon mixture at 600°C to 1000°C for 2 h to 6 h, and cooling. The carbon source is at least one selected from polyolefins, resins, rubbers, saccharides (such as glucose, sucrose, starch and cellulose), organic acids and pitch.

[0123] Optionally, in the solid-phase carbon coating method, the heat treatment temperature is specifically, for example, 650°C to 950°C, 710°C to 880°C or 750°C to 810°C, such as 600°C, 700°C, 800°C, 900°C, 1000°C, etc. The heat treatment holding time is specifically 2 h, 3 h, 4 h, 5 h, 6 h, etc., or a range defined by any two values, not limited here. Optionally, the heat treatment temperature is 700°C to 900°C, and the heat treatment holding time is 3 h to 5 h.

[0124] In the above solution, optionally, the fusion is carried out by a fusion machine, and the rotation speed of the fusion machine is 500 r / min to 3000 r / min.

[0125] Optionally, the rotation speed of the mixer is specifically, for example, 900 r / min to 2600 r / min, 1100 r / min to 2200 r / min or 1400 r / min to 1800 r / min, and for example, 500 r / min, 800 r / min, 1000 r / min, 1500 r / min, 2000 r / min, 2500 r / min, 3000 r / min, etc., or a range defined by any two values, and is not limited here. Optionally, the rotation speed of the mixer is 1000 r / min to 3000 r / min.

[0126] The width of the cutter gap of the mixer can be selected as needed, for example, 0.5 cm.

[0127] In the above carbon coating method, the protective atmosphere is at least one selected from helium gas, neon gas, argon gas and nitrogen gas.

[0128] In some embodiments, the method for preparing the powdery anode material includes the steps of performing a polymer coating on the pulverized silicon-based active material, or performing a carbon coating on the pulverized silicon-based active material with a carbon material and then further performing a polymer coating to obtain the powdery anode material.

[0129] In some embodiments, the polymer coating method includes the steps of dissolving a flexible polymer in a solvent to obtain a flexible polymer solution, adding a conductive material including flaky graphite and a nanocarbon material to the flexible polymer solution while stirring to obtain a mixed coating solution, adding a poor solvent to the mixed coating solution, stirring to obtain a supersaturated mixed coating solution, adding the silicon-based active material to the supersaturated mixed coating solution while stirring, stirring and separating to obtain a precursor of the anode material, and performing a heat treatment on the precursor of the anode material to obtain the powdery anode material.

[0130] In some embodiments, the flexible polymer contains thermally crosslinkable functional groups, and the thermally crosslinkable functional groups include at least one of epoxy groups, carboxy groups, hydroxy groups, amino groups, double bonds and triple bonds.

[0131] In some embodiments, the solvent includes at least one of water, methanol, ethanol, polyvinylpyrrolidone, isopropanol, acetone, petroleum ether, tetrahydrofuran, ethyl acetate, N,N-dimethylacetamide, N,N-dimethylformamide, n-hexane and halogenated hydrocarbons.

[0132] In some embodiments, the poor solvent includes a poor solvent for the flexible polymer.

[0133] In some embodiments, the poor solvent includes at least one of methanol, ethanol, polyvinylpyrrolidone, isopropanol, acetone, petroleum ether, tetrahydrofuran, ethyl acetate, N,N-dimethylacetamide, N,N-dimethylformamide, n-hexane and halogenated hydrocarbons.

[0134] In some embodiments, the temperature of the heat treatment is 100°C to 400°C, and the time of the heat treatment is 2 h to 12 h.

[0135] Optionally, the temperature of the heat treatment is, for example, 140°C to 360°C, 180°C to 280°C or 220°C to 260°C, and is, for example, 100°C, 120°C, 150°C, 180°C, 200°C, 220°C, 250°C, 280°C, 300°C, 320°C, 350°C, 380°C or 400°C, etc., or is a range defined by any two values, but may be other values within the above range and is not limited herein. The time of the heat treatment is, for example, 4.5 h to 10.5 h, 6.5 h to 9.5 h or 7.5 h to 8.5 h, and is, for example, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h or 12 h, etc., or is a range defined by any two values, but may be other values within the above range and is not limited herein.

[0136] In some embodiments, the method for preparing the powdery anode material further includes doping a dopant into the powdered silicon-based active material to obtain the powdery anode material.

[0137] In some embodiments, the dopant includes at least one of an alkali metal, an alkaline earth metal, an alkali metal oxide, and an alkaline earth metal oxide.

[0138] In some embodiments, the weight percentage b of the dopant in the anode material satisfies 0 < b ≤ 20%.

[0139] Optionally, the alkali metal is at least one selected from lithium, sodium, or potassium. The alkaline earth metal is at least one selected from magnesium, calcium, strontium, or barium. The alkali metal oxide is at least one selected from lithium oxide, sodium oxide, or potassium oxide. The alkaline earth metal oxide is at least one selected from magnesium oxide, calcium oxide, strontium oxide, or barium oxide. The weight percentage b of the dopant in the anode material is, for example, 1%, 3%, 5%, 8%, 10%, 12%, 15%, 18%, or 20%, etc., but may also be other values within the above range and is not limited herein. Without being bound by theory, doping a metal material into the anode material can increase the intrinsic conductivity of the silicon-based active material, and further, by selecting the type and content of the dopant, the conductivity of the silicon-based active material can be increased more effectively. Doping the dopant into the powdered silicon-based active material may be performed before carbon coating or after carbon coating.

[0140] One embodiment of the present disclosure further provides a lithium-ion battery. The lithium-ion battery includes the above anode material or a lithium-ion battery anode material prepared by the above preparation method.

[0141] The present disclosure provides a negative electrode material, a method for preparing the same, and a lithium-ion battery, and can solve problems such as non-uniform particles, relatively poor conductive performance, cycle stability, and rate performance when conventional silicon-based materials are applied to the negative electrode plate of the battery.

[0142] Regarding the negative electrode material according to the present disclosure, if the peak coefficient A of the particle size distribution of the negative electrode material is adjusted to satisfy 0 < A ≤ 3, the distribution is more concentrated at both ends of the particle size distribution curve of the negative electrode material, and there are no particles with a particle size significantly different from the median diameter. By reasonably selecting the peak coefficient A of the particle size distribution, the consistency of each particle of the negative electrode material is ensured, thereby improving the stability of the slurry when preparing and coating the negative electrode material slurry. The better the distribution consistency of the adhesive and conductive agent on the surfaces of different particles, the better the consistency of the coated electrode plate, and the higher the consistency of the expansion and contraction of different particles during the charge and discharge process. Therefore, the electrode plate is not easily damaged due to non-uniform expansion and contraction of particles locally on the electrode plate, the cycle performance of the battery does not deteriorate, and the expansion of the battery does not increase. Therefore, the consistency of the battery performance is improved. And to prevent large variations in the particle size of the material particles, the conductive agent adheres uniformly and effectively to each material particle, improving the rate performance of the battery. By specifying the silicon-based active material in the negative electrode material, the prepared negative electrode material can have an ideal high specific capacity.

[0143] Also, when the negative electrode material includes a coating layer, if the peak coefficient A of the particle size distribution of the negative electrode material is made to satisfy 0 < A ≤ 3, for the coating layer included in the negative electrode material, for example, the thickness consistency of the coating layer of each particle formed by a flexible polymer is improved. Thereby, the buffering effect on the volume change of the material during the charge and discharge process of the material by the flexible polymer can be made better, the cycle performance of the material can be improved, and the expansion of the material can be reduced.

[0144] In addition, the present disclosure can ensure that the particle size of the negative electrode material is concentrated in the middle part (between both sides) of the particle size distribution curve by selecting the selection coefficient B of the particle size distribution of the negative electrode material so that 0 < B ≤ 3 is satisfied. Thereby, when manufacturing an electrode plate with the negative electrode material and an adhesive, the adhesive can be uniformly distributed, improving the peel strength of the electrode plate and contributing to the construction of a stable and complete conductive network by the electrode plate.

[0145] In addition, the present disclosure can effectively prevent the aggregation of silicon-based active material particles and effectively exhibit the high performance of the battery by the negative electrode material by specifying the ratio B / A of the selection coefficient B to the peak coefficient A.

[0146] The above general description and the following detailed description are merely exemplary and do not limit the present disclosure.

[0147] Examples Hereinafter, the examples of the present disclosure will be further described with a plurality of examples. The examples of the present disclosure are not limited to the following specific examples. Within the protection scope, it can be implemented with modifications.

[0148] Example 1 The method for preparing a lithium-ion battery negative electrode material includes the following steps S10 to S30 as shown in FIG. 1. Step S10: Take 1 kg of SiO bulk material, pulverize the bulk material using a crusher and a ball mill, make the D50 of the SiO powder about 5 μm, the crushing power p of the crusher is 100 kW, and the rotation speed v1 of the ball mill is 800 rpm. Step S20: Perform carbon coating on the SiO powder obtained in Step S10 with a carbon material, and the weight percentage a of the carbon material in the negative electrode material is 7%. Step S30: The particle size of the powder obtained in Step S20 was adjusted using an air classifier to obtain the final negative electrode material. The frequency f of the induced draft fan of the classifier was 55 Hz. The particle size distribution of the negative electrode material had a selection coefficient B of 2.00, a peak coefficient A of 1.80, and B / A = 1.11.

[0149] Example 2 The method for preparing a lithium-ion battery negative electrode material includes the following Steps S10 to S30. Step S10: 1 kg of Si bulk material was taken, and pulverization was performed on the bulk material using a crusher and a ball mill to make the D50 of the Si powder about 5 μm. The crushing power p of the crusher was 100 kW, and the rotation speed v1 of the ball mill was 800 rpm. Step S20: The Si powder obtained in Step S10 was carbon-coated with a carbon material, and the weight percentage a of the carbon material in the negative electrode material was 6.7%. Step S30: The particle size of the powder obtained in Step S20 was adjusted using an air classifier to obtain the final negative electrode material. The frequency f of the induced draft fan of the classifier was 65 Hz. The particle size distribution of the negative electrode material had a selection coefficient B of 1.50, a peak coefficient A of 1.50, and B / A = 1.00.

[0150] Example 3 The method for preparing a lithium-ion battery negative electrode material includes the following Steps S10 to S30. Step S10: 1 kg of SiO bulk material was taken, and pulverization was performed on the bulk material using a crusher and a ball mill to make the D50 of the SiO powder about 5 μm. The crushing power p of the crusher was 100 kW, and the rotation speed v1 of the ball mill was 800 rpm. Step S20: The SiO powder obtained in Step S10 was carbon-coated with a carbon material, and the weight percentage a of the carbon material in the negative electrode material was 6.8%. Step S30: Particle size adjustment was performed on the powder obtained in Step S20 using an air classifier to obtain the final negative electrode material. The frequency f of the induced draft fan of the classifier was 35 Hz. The particle size distribution of the negative electrode material had a selection coefficient B of 3.00, a peak coefficient A of 1.50, and B / A = 2.00.

[0151] Example 4 The method for preparing a lithium-ion battery negative electrode material includes the following steps S10 to S30. Step S10: Take 1 kg of SiO bulk material, pulverize the bulk material using a crusher and a ball mill to make the D50 of the SiO powder about 5 μm. The crushing power p of the crusher was 70 kW, and the rotational speed v1 of the ball mill was 1100 rpm. Step S20: Carbon coating was performed on the SiO powder obtained in Step S10 using a carbon material. The weight percentage a of the carbon material in the negative electrode material was 7.1%. Step S30: Particle size adjustment was performed on the powder obtained in Step S20 using an air classifier to obtain the final negative electrode material. The frequency f of the induced draft fan of the classifier was 70 Hz. The particle size distribution of the negative electrode material had a selection coefficient B of 1.20, a peak coefficient A of 3.01, and B / A = 0.40.

[0152] Example 5 The method for preparing a lithium-ion battery negative electrode material includes the following steps S10 to S30. Step S10: Take 1 kg of SiO bulk material, pulverize the bulk material using a crusher and a ball mill to make the D50 of the SiO powder about 5 μm. The crushing power p of the crusher was 150 kW, and the rotational speed v1 of the ball mill was 600 rpm. Step S20: Carbon coating was performed on the SiO powder obtained in Step S10 using a carbon material. The weight percentage a of the carbon material in the negative electrode material was 7.1%. Step S30: The particle size of the powder obtained in Step S20 was adjusted using an air classifier to obtain the final negative electrode material. The frequency f of the induced draft fan of the classifier was 40 Hz. The particle size distribution of the negative electrode material had a separation coefficient B of 2.50, a peak coefficient A of 0.50, and B / A = 5.00.

[0153] Example 6 The method for preparing a lithium-ion battery negative electrode material includes the following Steps S10 to S30. Step S10: Take 1 kg of SiO bulk material and pulverize the bulk material using a crusher and a ball mill to make the D50 of the SiO powder about 5 μm. The crushing power p of the crusher was 150 kW, and the rotation speed v1 of the ball mill was 650 rpm. Step S20: The SiO powder obtained in Step S10 was carbon-coated with a carbon material, and the weight percentage a of the carbon material in the negative electrode material was 7.3%. Step S30: The particle size of the powder obtained in Step S20 was adjusted using an air classifier to obtain the final negative electrode material. The frequency f of the induced draft fan of the classifier was 46 Hz. The particle size distribution of the negative electrode material had a separation coefficient B of 2.10, a peak coefficient A of 0.70, and B / A = 3.00.

[0154] Example 7 The method for preparing a lithium-ion battery negative electrode material includes the following Steps S10 to S30. Step S10: Take 1 kg of SiO bulk material and pulverize the bulk material using a crusher and a ball mill to make the D50 of the SiO powder about 5 μm. The crushing power p of the crusher was 110 kW, and the rotation speed v1 of the ball mill was 750 rpm. Step S20: The SiO powder obtained in Step S10 was carbon-coated with a carbon material, and the weight percentage a of the carbon material in the negative electrode material was 7%. Step S30: The particle size of the powder obtained in step S20 was adjusted using an air classifier to obtain the final negative electrode material. The frequency f of the induced draft fan of the classifier was 75 Hz. The particle size distribution of the negative electrode material had a selection coefficient B of 1.01, a peak coefficient A of 1.20, and B / A = 0.84.

[0155] Example 8 The method for preparing a lithium-ion battery negative electrode material includes the following steps S10 to S30. Step S10: Take 1 kg of SiO bulk material, pulverize the bulk material using a crusher and a ball mill, and make the D50 of the SiO powder about 5 μm. The crushing power p of the crusher was 120 kW, and the rotation speed v1 of the ball mill was 700 rpm. Step S20: The SiO powder obtained in step S10 was carbon-coated with a carbon material, and the weight percentage a of the carbon material in the negative electrode material was 7.2%. Step S30: The particle size of the powder obtained in step S20 was adjusted using an air classifier to obtain the final negative electrode material. The frequency f of the induced draft fan of the classifier was 60 Hz. The particle size distribution of the negative electrode material had a selection coefficient B of 1.60, a peak coefficient A of 1.00, and B / A = 1.60.

[0156] Example 9 The method for preparing a lithium-ion battery negative electrode material includes the following steps S10 to S30. Step S10: Take 1 kg of SiO bulk material, pulverize the bulk material using a crusher and a ball mill, and make the D50 of the SiO powder about 20 μm. The crushing power p of the crusher was 90 kW, and the rotation speed v1 of the ball mill was 400 rpm. Step S20: The SiO powder obtained in step S10 was carbon-coated with a carbon material, and the weight percentage a of the carbon material in the negative electrode material was 6.9%. Step S30: The particle size of the powder obtained in Step S20 was adjusted using an air classifier to obtain the final negative electrode material. The frequency f of the induced draft fan of the classifier was 58 Hz. The particle size distribution of the negative electrode material had a selection coefficient B of 1.80, a peak coefficient A of 0.80, and B / A = 2.24.

[0157] Example 10 The method for preparing a negative electrode material for a lithium-ion battery includes the following Steps S10 to S40. Step S10: Take 1 kg of SiO bulk material and pulverize the bulk material using a crusher and a ball mill to make the D50 of the SiO powder about 20 μm. The crushing power p of the crusher was 90 kW, and the rotational speed v1 of the ball mill was 600 rpm. Step S20: The SiO powder obtained in Step S10 was carbon-coated with a carbon material, and the weight percentage a of the carbon material in the negative electrode material was 7.1%. Step S30: The SiO powder carbon-coated in Step S20 was doped with a dopant, the dopant was MgO, and the weight percentage b of the dopant in the negative electrode material was 5%. Step S40: The particle size of the powder obtained in Step S30 was adjusted using an air classifier to obtain the final negative electrode material. The frequency f of the induced draft fan of the classifier was 56 Hz. The particle size distribution of the negative electrode material had a selection coefficient B of 1.91, a peak coefficient A of 1.00, and B / A = 1.91.

[0158] Example 11 Step S10: Take 1 kg of SiO bulk material and pulverize the bulk material using a crusher and a ball mill to make the D50 of the SiO powder about 5 μm. The crushing power p of the crusher was 100 kW, and the rotational speed v1 of the ball mill was 800 rpm. Step S20: The particle size of the powder obtained in Step S10 was adjusted using an air classifier to obtain the final negative electrode material. The frequency f of the induced draft fan of the classifier was 58 Hz. The particle size distribution of the negative electrode material had a selection coefficient B of 2.20, a peak coefficient A of 1.89, and B / A = 1.16.

[0159] Example 12 Step S10: Take 1 kg of SiO bulk material, pulverize the bulk material using a crusher and a ball mill to make the D50 of the SiO powder about 20 μm. The crushing power p of the crusher was 90 kW, and the rotational speed v1 of the ball mill was 600 rpm. Step S20: The SiO powder obtained in Step S10 was doped with a dopant. The dopant was MgO, and the weight percentage b of the dopant in the negative electrode material was 5%. Step S30: The particle size of the powder obtained in Step S20 was adjusted using an air classifier to obtain the final negative electrode material. The frequency f of the induced draft fan of the classifier was 55 Hz. The particle size distribution of the negative electrode material had a selection coefficient B of 1.76, a peak coefficient A of 1.22, and B / A = 1.44.

[0160] Example 13 Step S10: Take 1 kg of SiO bulk material, pulverize the bulk material using a crusher and a ball mill to make the D50 of the SiO powder about 20 μm. The crushing power p of the crusher was 90 kW, and the rotational speed v1 of the ball mill was 600 rpm. Step S20: The SiO powder obtained in Step S10 was doped with a dopant. The dopant was MgO, and the weight percentage b of the dopant in the negative electrode material was 5%. Step S30: The powder obtained in Step S20 was carbon-coated with a carbon material. The weight percentage a of the carbon material in the negative electrode material was 7.3%. Step S40: The particle size of the powder obtained in step S30 was adjusted using an air classifier to obtain the final negative electrode material. The frequency f of the induced draft fan of the classifier was 56 Hz. The particle size distribution of the negative electrode material had a selection coefficient B of 2.17, a peak coefficient A of 1.22, and B / A = 1.78.

[0161] Example 14 Step S10: Take 1 kg of SiO bulk material, pulverize the bulk material using a crusher and a ball mill, and make the D50 of the SiO powder about 5 μm. The crushing power p of the crusher was 100 kW, and the rotational speed v1 of the ball mill was 800 rpm. Step S20: The SiO powder obtained in step S10 was processed using a fusion machine. The rotational speed of the fusion machine was 1000 r / min, and the processing time was 6 h. Step S30: The SiO powder obtained in step S20 was carbon-coated with a carbon material, and the weight percentage a of the carbon material in the negative electrode material was 6.9%. Step S40: The particle size of the powder obtained in step S30 was adjusted using an air classifier to obtain the final negative electrode material. The frequency f of the induced draft fan of the classifier was 55 Hz. The particle size distribution of the negative electrode material had a selection coefficient B of 1.95, a peak coefficient A of 1.75, B / A = 1.11, and a sphericity of 0.79.

[0162] Example 15 Step S10: Take 1 kg of SiO bulk material, pulverize the bulk material using a crusher and a ball mill, and make the D50 of the SiO powder about 5 μm. The crushing power p of the crusher was 100 kW, and the rotational speed v1 of the ball mill was 800 rpm. Step S20: The SiO powder obtained in step S10 was processed using a fusion machine. The rotational speed of the fusion machine was 1000 r / min, and the processing time was 6.2 h. Step S30: The SiO powder obtained in step S20 was carbon-coated with a carbon material, and the weight percentage a of the carbon material in the negative electrode material was 7.0%. Step S40: The particle size of the powder obtained in step S30 was adjusted using an air classifier to obtain the final negative electrode material. The frequency f of the induced draft fan of the classifier was 55 Hz. The particle size distribution of the negative electrode material had a selection coefficient B of 1.90, a peak coefficient A of 1.67, B / A = 1.14, and a sphericity of 0.82.

[0163] Example 16 Step S10: Take 1 kg of SiO bulk material and pulverize the bulk material using a crusher and a ball mill to make the D50 of the SiO powder about 5 μm. The crushing power p of the crusher was 100 kW, and the rotational speed v1 of the ball mill was 800 rpm. Step S20: The SiO powder obtained in step S10 was processed using a fusion machine. The rotational speed of the fusion machine was 2500 r / min, and the processing time was 8.5 h. Step S30: The SiO powder obtained in step S20 was carbon-coated with a carbon material, and the weight percentage a of the carbon material in the negative electrode material was 7.1%. Step S40: The particle size of the powder obtained in step S30 was adjusted using an air classifier to obtain the final negative electrode material. The frequency f of the induced draft fan of the classifier was 55 Hz. The particle size distribution of the negative electrode material had a selection coefficient B of 1.93, a peak coefficient A of 1.62, B / A = 1.19, and a sphericity of 0.91.

[0164] Example 17 Step S10: Take 1 kg of SiO bulk material and pulverize the bulk material using a crusher and a ball mill to make the D50 of the SiO powder about 5 μm. The crushing power p of the crusher was 100 kW, and the rotational speed v1 of the ball mill was 800 rpm. Step S20: The SiO powder obtained in step S10 was carbon-coated with a carbon material, and the weight percentage a of the carbon material in the negative electrode material was 7%. Step S30: Particle size adjustment was performed on the powder obtained in Step S20 using an air classifier to obtain a particle size-adjusted negative electrode material. The frequency f of the induced draft fan of the classifier was 55 Hz. Step S40: 4 g of polyacrylic acid was dissolved in 100 g of distilled water, and after being sufficiently dissolved at a temperature of 40°C, 1 g of carbon nanofibers was added while stirring. After stirring for 2 hours, 200 g of ethanol was added, and stirring was continued for another 0.5 hour. Then, 90 g of the negative electrode material obtained in Step S30 was added while stirring. After stirring at a temperature of 60°C for 2 hours, the temperature was lowered to room temperature, and the material was separated by suction filtration. It was placed in an oven at 180°C for heat treatment for 4 hours. After cooling, it was taken out to obtain SiO coated with polyacrylic acid and carbon nanofibers. x A negative electrode material was obtained. The particle size distribution of the obtained negative electrode material had a selection coefficient B of 2.00, a peak coefficient A of 1.78, and B / A = 1.12.

[0165] Example 18 Step S10: 1 kg of SiO bulk material was taken, pulverized using a crusher and a ball mill to make the D50 of the SiO powder about 5 μm. The crushing power p of the crusher was 110 kW, and the rotational speed v1 of the ball mill was 750 rpm. Step S20: Carbon coating was performed on the SiO powder obtained in Step S10 using a carbon material, and the weight percentage a of the carbon material in the negative electrode material was 7%. Step S30: Particle size adjustment was performed on the powder obtained in Step S20 using an air classifier to obtain a particle size-adjusted negative electrode material. The frequency f of the induced draft fan of the classifier was 20 Hz. Step S40: Dissolve 4 g of polyacrylic acid in 100 g of distilled water. After completely dissolving at a temperature of 40°C, add 1 g of carbon nanofibers while stirring. After stirring for 2 hours, add 200 g of ethanol and continue stirring for another 0.5 hour. Then, add 90 g of the negative electrode material obtained in Step S30 while stirring. After stirring at a temperature of 60°C for 2 hours, cool down to room temperature, separate the material by suction filtration, place it in an oven at 180°C for heat treatment for 4 hours, and after cooling, take it out to obtain SiO coated with polyacrylic acid and carbon nanofibers. x A negative electrode material was obtained. For the obtained negative electrode material, the sorting coefficient B was 2.88, the peak coefficient A was 1.27, and B / A = 2.27.

[0166] Example 19 Step S10: Take 1 kg of SiO bulk material, pulverize the bulk material using a crusher and a ball mill to make the D50 of the SiO powder about 20 μm. The crushing power p of the crusher was 90 kW, and the rotation speed v1 of the ball mill was 600 rpm. Step S20: Dope the SiO powder coated with carbon in Step S10 with a dopant. The dopant was Li2O, and the weight percentage b of the dopant in the negative electrode material was 4.5%. Step S30: Coat the powder obtained in Step S20 with a carbon material. The weight percentage a of the carbon material in the negative electrode material was 7.2%. Step S40: Adjust the particle size of the powder obtained in Step S30 using an air classifier to obtain the final negative electrode material. The frequency f of the induced draft fan of the classifier was 56 Hz. For the particle size distribution of the negative electrode material, the sorting coefficient B was 2.19, the peak coefficient A was 1.19, and B / A = 1.84.

[0167] Example 20 Step S10: Take 1 kg of SiO bulk material, pulverize the bulk material using a crusher and a ball mill, make the D50 of the SiO powder about 5 μm, the crushing power p of the crusher is 110 kW, and the rotation speed v1 of the ball mill is 750 rpm. Step S20: Perform carbon coating on the SiO powder obtained in Step S10 with a carbon material, and the weight percentage a of the carbon material in the negative electrode material is 7%. Step S30: Use an air classifier to adjust the particle size of the powder obtained in Step S20 to obtain a negatively charged electrode material with adjusted particle size, and the frequency f of the induced draft fan of the classifier is 20 Hz. Step S40: Dissolve 4 g of sodium alginate (i.e., a derivative of alginic acid) in 100 g of distilled water, fully dissolve it at a temperature of 40 °C, then add 1 g of conductive graphite while stirring, stir for 2 hours, then add 200 g of ethanol, stir for another 0.5 hour, and then add 90 g of the negative electrode material obtained in Step S30 while stirring. After stirring at a temperature of 60 °C for 2 hours, cool it down to room temperature, separate the material by suction filtration, place it in an oven at 180 °C for heat treatment for 4 hours, cool it, take it out, and SiO coated with sodium alginate and conductive graphite x A negative electrode material was obtained. The particle size distribution of the obtained negative electrode material was such that the sorting coefficient B was 2.90, the peak coefficient A was 1.30, and B / A = 2.23.

[0168] Example 21 The method for preparing a lithium-ion battery negative electrode material includes the following steps S10 to S30. Step S10: Take 1 kg of SiO bulk material, pulverize the bulk material using a crusher and a ball mill, make the D50 of the SiO powder about 5 μm, the crushing power p of the crusher is 100 W, and the rotation speed v1 of the ball mill is 1000 rpm. Step S20: Perform carbon coating on the SiO powder obtained in Step S10 with a carbon material, and the weight percentage a of the carbon material in the negative electrode material is 6.9%. Step S30: The particle size of the powder obtained in Step S20 was adjusted using an air classifier to obtain the final negative electrode material. The frequency f of the induced draft fan of the classifier was 110 Hz. The particle size distribution of the negative electrode material had a separation coefficient B of 3.77, a peak coefficient A of 0.71, and B / A = 5.31.

[0169] Example 22 The method for preparing a negative electrode material for a lithium-ion battery includes the following Steps S10 to S30. Step S10: Take 1 kg of SiO bulk material, and pulverize the bulk material using a crusher and a ball mill to make the D50 of the SiO powder about 5 μm. The crushing power p of the crusher was 110 kW, and the rotational speed v1 of the ball mill was 750 rpm. Step S20: The SiO powder obtained in Step S10 was carbon-coated with a carbon material, and the weight percentage a of the carbon material in the negative electrode material was 7%. Step S30: The particle size of the powder obtained in Step S20 was adjusted using an air classifier to obtain the final negative electrode material. The frequency f of the induced draft fan of the classifier was 10 Hz. The particle size distribution of the negative electrode material had a separation coefficient B of 3.19, a peak coefficient A of 1.30, and B / A = 2.45.

[0170] Example 23 The method for preparing a negative electrode material for a lithium-ion battery includes the following Steps S10 to S30. Step S10: Take 1 kg of Si bulk material, and pulverize the bulk material using a crusher and a ball mill to make the D50 of the Si powder about 5 μm. The crushing power p of the crusher was 150 kW, and the rotational speed v1 of the ball mill was 550 rpm. Step S20: The Si powder obtained in Step S10 was carbon-coated with a carbon material, and the weight percentage a of the carbon material in the negative electrode material was 6.9%. Step S30: The particle size of the powder obtained in Step S20 was adjusted using an air classifier to obtain the final negative electrode material. The frequency f of the induced draft fan of the classifier was 53 Hz. The particle size distribution of the negative electrode material had a selection coefficient B of 2.42, a peak coefficient A of 0.46, and B / A = 5.24.

[0171] Comparative Example 1 The method for preparing a lithium-ion battery negative electrode material includes the following Steps S10 to S30. Step S10: Take 1 kg of SiO bulk material and pulverize the bulk material using a crusher and a ball mill to make the D50 of the SiO powder about 5 μm. The crushing power p of the crusher was 150 kW, and the rotation speed v1 of the ball mill was 550 rpm. Step S20: The SiO powder obtained in Step S10 was carbon-coated with a carbon material, and the weight percentage a of the carbon material in the negative electrode material was 7.1%. Step S30: The particle size of the powder obtained in Step S20 was adjusted using an air classifier to obtain the final negative electrode material. The frequency f of the induced draft fan was 65 Hz. The particle size distribution of the negative electrode material had a selection coefficient B of 1.63, a peak coefficient A of 3.04, and B / A = 0.54.

[0172] Analysis of Effects Performance measurements were carried out on the negative electrode materials obtained from each of the above Examples and Comparative Examples as follows.

[0173] (1) Measurement of Particle Size Distribution The particle size distribution of the material was measured using a Malvern 2000 particle size measuring device, with a refractive index of 2.42, a light obscuration of 8% - 20%, and water used as the dispersant.

[0174] (2) Measurement of Initial Coulombic Efficiency a. Fabrication of lithium-ion battery: The prepared anode material, conductive carbon black, CMC (carboxymethyl cellulose) / SBR (styrene-butadiene rubber) were coated on a copper foil at a ratio of 75:15:10 to fabricate an anode plate. A metal lithium sheet was used as the counter electrode, and PP / PE was used as the separator to fabricate a button battery. b. The electrochemical performance of the battery was evaluated using a 5V / 10mA battery evaluation device of LAND or NEWARE. The voltage was 1.5V, the current was 0.1C, and the initial Coulomb efficiency = initial charge specific capacity / initial discharge specific capacity.

[0175] (3) Measurement of cycle performance a. Fabrication of lithium-ion battery: The prepared anode material and graphite were mixed at a ratio of 15:85 to obtain an anode active material. The anode active material, conductive carbon black, CMC, and SBR were coated on a copper foil at a ratio of 92:4:2:2 to fabricate an anode plate. A metal lithium sheet was used as the counter electrode, and PP / PE was used as the separator to fabricate a button battery. b. The electrochemical performance of the battery was evaluated using a 5V / 10mA battery evaluation device of LAND or NEWARE. The voltage was 1.5V, the current was 0.1C, and the 50-cycle retention rate = discharge specific capacity at the 50th cycle / initial discharge specific capacity.

[0176] (4) Measurement of swelling performance a. Fabrication of lithium-ion battery: The prepared anode material and graphite were mixed at a ratio of 15:85 to obtain an anode active material. The anode active material, conductive carbon black, CMC, and SBR were coated on a copper foil at a ratio of 92:4:2:2 to fabricate an anode plate. The thickness of the anode plate was measured using a micrometer and recorded as L1. A metal lithium sheet was used as the counter electrode, and PP / PE was used as the separator to fabricate a button battery. b. The electrochemical performance of the battery was evaluated using a 5V / 10mA battery evaluation device of LAND or NEWARE. The voltage was 1.5V, the current was 0.1C. After 50 cycles, the battery was disassembled, and the thickness of the anode plate was measured using a micrometer and recorded as L2. The 50-cycle anode plate swelling rate = (L2 - copper foil thickness) / (L1 - copper foil thickness) * 100%.

[0177] (5) Battery consistency measurement (2) and (3) were used to manufacture 10 similar batteries, and the consistency of the 50-cycle capacity retention rate and the 50-cycle electrode plate expansion rate of the 10 batteries was compared. The consistency was represented by the relative standard deviation (RSD) of the 50-cycle capacity retention rate and the 50-cycle electrode plate expansion rate of 10 groups.

[0178] (6) Scanning electron microscope measurement The material was measured using an S4800 scanning electron microscope to observe the microscopic state of the particles.

[0179] (7) Wadell sphericity measurement The particle size distribution was measured by a laser particle size analyzer to obtain the volume equivalent diameter within each particle size range. The equivalent volume diameter was used as the particle size of all spheres within the minimum particle size distribution range. All particles within this range were considered equivalent to ideal spheres. The specific surface area within each particle size distribution range was calculated, weighted by the volume ratio %, and the specific surface area of a sphere with the same volume as all particles was determined. The sphericity of the spherical particles produced by plasma = the surface area of a sphere with the same volume as the particles obtained by calculation / the specific surface area of the particles measured by a specific surface area measuring device.

[0180] (8) Rate and peel strength measurement a. Manufacture of lithium-ion batteries: The composite materials prepared according to the above examples and comparative examples were each mixed with graphite at a mass ratio of 15:85 to obtain a negative electrode active material. The negative electrode active material, conductive carbon black, CMC, and SBR were uniformly mixed at a mass ratio of 92:4:2:2 and coated on a copper foil to manufacture a negative electrode plate. The peel strength of the negative electrode plate was measured using a cross-cut tester. b. Using the negative electrode plate, a metal lithium sheet as the positive electrode plate, and PP / PE as the separator, a button battery was manufactured. c. Measured using a LAND or NEWARE 5V / 10mA battery evaluation device, with the voltage being 1.5V and the currents being 0.1C and 3C respectively, and 3C / 0.1C = discharge specific capacity at 3C current / discharge specific capacity at 0.1C current.

[0181] The data recorded in the battery measurement and experiment process are shown in Table 1 below. The particle size distribution results of Examples 1, 13, 17, 22 and Comparative Example 1 are shown in Figures 2-5, 6 respectively. The scanning electron microscope results of Examples 1, 13, 17, 22 and Comparative Example 1 are shown in Figures 7-10, 11 respectively.

[0182]

Table 1

Table 2

Table 3

Table 4

[0183]

Table 5

[0184] As can be seen from the results of FIGS. 2 to 5, by adjusting the particle size of the silicon-based active material coated with the carbon layer, selecting the particle size selection coefficient B and the peak coefficient A, and obtaining a negative electrode material with an appropriate particle size distribution, the consistency of the negative electrode material particles can be guaranteed. As can be seen from Table 1 above, the lithium-ion battery prepared with the negative electrode material according to the present disclosure has excellent capacity efficiency, cycle performance, charge and discharge performance, and expansion performance, high peel strength, and effectively improved performance of the lithium-ion battery. As can be seen by comparing Examples 21 to 23 with Comparative Example 1, the present disclosure obtains a negative electrode material with a relatively appropriate particle size distribution by selecting the peak coefficient A of the particle size distribution, improves the performance of the negative electrode material, and particularly improves the rate performance of the negative electrode material. Further, as can be seen by comparing Examples 1 to 20 with Comparative Example 1, the present disclosure selects the peak coefficient A and the particle size selection coefficient B and selects B / A, so that the particle size distribution of the negative electrode material is more concentrated, the 50-cycle capacity retention rate, rate performance, and peel strength of the negative electrode material are further improved, and the expansion rate of the negative electrode material is further reduced.

[0185] The above are only selectable embodiments of the present disclosure and do not limit the present disclosure. For those skilled in the art, the present disclosure may have various modifications and changes. Any modifications, equivalent substitutions, improvements, etc. made without departing from the spirit and principle of the present application belong to the protection scope of the present disclosure.

[0186] Industrial Applicability The present disclosure provides a negative electrode material, a method for preparing the same, and a lithium-ion battery. The negative electrode material according to the present disclosure can guarantee the consistency of the negative electrode material particles by specifying the peak coefficient A of the particle size distribution of the negative electrode material. Therefore, the consistency of the coated electrode plate is good, the performance consistency of the battery is high, and the performance of the battery is improved. Further, by further specifying the selection coefficient B, the peak coefficient A, and the ratio B / A of the selection coefficient B, the negative electrode material has a good particle size distribution and the performance of the battery is higher. Therefore, the negative electrode material according to the present disclosure has excellent practicality and application prospects.

Claims

1. A negative electrode material, The peak coefficient A of the particle size distribution of the negative electrode material satisfies 0 < A ≤ 3, and A = (D ９５ - D ５ ) / [2.5 × (D ７５ - D ２５ ), where D ９５ , D ５ , D ７５ , D ２５ represent the particle sizes of the negative electrode material when the volume content reaches 95%, 5%, 75%, and 25% in the cumulative curve, respectively. The negative electrode material contains a silicon-based active material, and the silicon-based active material contains at least one of SiO ｘ , SiO ｘ / C, SiO ｘ / M, Si, Si / C, and Si / M, where x satisfies 0 < x ≤ 2, and M contains at least one of a metal, a non-metal, a metal oxide, and a non-metal oxide. As the particle size distribution of the negative electrode material, 0.55 ≤ D ５ ≤ 16.5 μm, 1.98 ≤ D ２５ ≤ 17.9 μm, 6.00 ≤ D ７５ ≤ 20.3 μm, 7.17 ≤ D ９５ satisfies ≤ 22.5 μm characterized by the following.

2. The negative electrode material according to Claim 1, wherein the Wadell sphericity of the negative electrode material is 0.8 or more.

3. The negative electrode material according to Claim 1, wherein the particle size D50 of the silicon-based active material is more than 0 μm and 80 μm or less.

4. The negative electrode material according to Claim 1, wherein the negative electrode material further contains a dopant doped into the silicon-based active material.

5. The negative electrode material according to Claim 4, wherein the dopant contains at least one of an alkali metal, an alkaline earth metal, an alkali metal oxide, and an alkaline earth metal oxide.

6. The negative electrode material according to Claim 4, wherein the weight percentage b of the dopant in the negative electrode material satisfies 0 < b ≤ 20%.

7. The sorting coefficient B of the particle size distribution of the negative electrode material satisfies 0 < B ≤ 3, and B = (D ８４ - D １６ ) / 4 + (D ９５ - D ５ ) / 6.6, where D ８４ , D １６ , D ９５ , D ５ represent the particle sizes of the negative electrode material when the volume content reaches 84%, 16%, 95%, and 5% in the cumulative curve, respectively. As the particle size distribution of the negative electrode material, 1.12 ≤ D １６ ≤ 17.3 μm, 6.56 ≤ D ８４ ≤ 21.3 μm is satisfied characterized by the following.

8. The negative electrode material according to Claim 7, wherein the selection coefficient B and the peak coefficient A of the particle size distribution of the negative electrode material satisfy 0 < B / A ≤ 5.

9. The negative electrode material further includes a coating layer formed on the surface of the silicon-based active material, and the coating layer contains at least one of a flexible polymer and a conductive material. characterized by the following.

10. The negative electrode material according to Claim 9, wherein the flexible polymer contains at least one of a natural flexible polymer and an artificial flexible polymer.

11. The negative electrode material according to Claim 9, wherein the flexible polymer contains at least one of a polyolefin and its derivatives, a polyvinyl alcohol and its derivatives, a polyacrylic acid and its derivatives, a polyamide and its derivatives, a carboxymethyl cellulose and its derivatives, an alginic acid and its derivatives, and a polycarbonate and its derivatives.

12. The negative electrode material according to Claim 9, wherein the flexible polymer contains a thermally crosslinkable functional group, and the thermally crosslinkable functional group contains at least one of an epoxy group, a carboxy group, a hydroxy group, an amino group, a double bond, and a triple bond.

13. A step of preparing a powdery negative electrode material, and a step of adjusting the particle size of the prepared powdery negative electrode material to obtain a negative electrode material. The peak coefficient A of the particle size distribution of the negative electrode material satisfies 0 < A ≤ 3, and A = (D ９５ − D ５ ) / [2.5 × (D ７５ − D ２５ ), where D ９５ , D ５ , D ７５ , D ２５ represent the particle sizes of the negative electrode material when the volume content reaches 95%, 5%, 75%, and 25% respectively in the cumulative curve. As the particle size distribution of the negative electrode material, 0.55 ≤ D ５ ≤ 16.5 μm, 1.98 ≤ D ２５ ≤ 17.9 μm, 6.00 ≤ D ７５ ≤ 20.3 μm, 7.17 ≤ D ９５ ≤ 22.5 μm are satisfied, The negative electrode material contains a silicon-based active material, and the silicon-based active material contains at least one of SiO ｘ , SiO ｘ / C, SiO ｘ / M, Si, Si / C, and Si / M, where x satisfies 0 < x ≤ 2, and M contains at least one of a metal, a non-metal, a metal oxide, and a non-metal oxide characterized by the following.

14. The selection coefficient B of the particle size distribution of the negative electrode material satisfies 0 < B ≤ 3, and B = (D ８４ - D １６ ) / 4 + (D ９５ - D ５ ) / 6.6, where D ８４ , D １６ , D ９５ , D ５ represent the particle sizes when the volume content reaches 84%, 16%, 95%, and 5% respectively in the cumulative curve. As the particle size distribution of the negative electrode material, 1.12 ≤ D １６ ≤ 17.3 μm, 6.56 ≤ D ８４ ≤ 21.3 μm is satisfied The method for preparing the negative electrode material according to claim 13, characterized in that...

15. The method for preparing the powdery negative electrode material includes the step of pulverizing the silicon-based active material to obtain the powdery negative electrode material. The preparation method according to claim 14, characterized in that...

16. The pulverization method includes crushing and ball milling, and the preparation method according to claim 15 is characterized in that...

17. The device used for the crushing includes a crusher, and the crushing power p of the crusher satisfies 0 < p ≤ 300 kW. The preparation method according to claim 16 is characterized in that...

18. The device used for the ball milling includes a ball mill, and the rotation speed v1 of the ball mill satisfies 0 < v1 ≤ 1500 rpm. The preparation method according to claim 16 is characterized in that...

19. The device used for the particle size adjustment includes a classifier, and the frequency f of the induced draft fan of the classifier satisfies 0 < f ≤ 100 Hz. The preparation method according to claim 13 is characterized in that...

20. The selection coefficient B and the peak coefficient A satisfy 0 < B / A ≤ 5. The preparation method according to claim 14 is characterized in that...

21. The method for preparing the powdery negative electrode material further includes the step of carbon coating the pulverized silicon-based active material with a carbon material to obtain the powdery negative electrode material, and the weight percentage a of the carbon material in the negative electrode material satisfies 0 < a ≤ 15%. The preparation method according to claim 15 is characterized in that...

22. The method for preparing the powdery negative electrode material further includes the step of performing polymer coating on the pulverized silicon-based active material, or performing carbon coating on the pulverized silicon-based active material with a carbon material and then obtaining the powdery negative electrode material. The preparation method according to claim 15 is characterized in that...

23. The polymer coating method includes: dissolving a flexible polymer in a solvent to obtain a flexible polymer solution; while stirring, adding a conductive material containing flaky graphite and a nanocarbon material to the flexible polymer solution to obtain a mixed coating solution; adding a poor solvent to the mixed coating solution, stirring to obtain a supersaturated mixed coating solution; while stirring, adding a silicon-based active material to the supersaturated mixed coating solution, stirring, separating to obtain a negative electrode material precursor. performing a heat treatment on the negative electrode material precursor to obtain the powdery negative electrode material, and The preparation method according to claim 22, characterized in that.

24. The method for preparing the powdery negative electrode material further includes doping a dopant into the powdered silicon-based active material to obtain the powdery negative electrode material The preparation method according to claim 15, characterized in that.

25. including the negative electrode material according to any one of claims 1 to 12 A lithium ion battery characterized by that.

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