Silicon-based negative electrode material, preparation method thereof and lithium ion battery

Abstract

This application relates to the field of secondary battery technology, and more particularly to a silicon-based anode material, its preparation method, and a lithium-ion battery. The peak coefficient A of the particle size distribution of the silicon-based anode material satisfies: 0 < A ≤ 3; where A = (D 95 -D5) / [2.5*(D 75 -D 25 )],D 95 D5, D 75 D 25 These represent the particle sizes of the silicon-based anode material when the volume percentage content on the cumulative curve reaches 95%, 5%, 75%, and 25%, respectively. The silicon-based anode material of this application has a suitable peak coefficient A, which can ensure the uniformity of the silicon-based anode material particles, thereby resulting in good uniformity of the coated electrode sheet, and thus high performance consistency of the battery, improving battery performance.

Description

[0001] This application claims priority to Chinese Patent Application No. 2022104270714, filed on April 21, 2022, entitled “Anode Material and Preparation Method Thereof and Lithium-ion Battery”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of secondary battery technology, and in particular to a silicon-based anode material, its preparation method, and a lithium-ion battery. Background Technology

[0003] As the application of lithium-ion batteries continues to expand and deepen, the requirements for their performance are also increasing, especially in terms of energy density. Traditional graphite-silicon-based anode materials, due to their relatively low theoretical specific capacity, are no longer sufficient to meet the growing market demand. As a high-specific-capacity silicon-based anode material, silicon-based materials have received considerable attention in recent years.

[0004] Silicon-based anode materials have a specific capacity exceeding 3000 mAh / g, but when applied to lithium-ion batteries, they exhibit poorer cycle stability and higher battery expansion rates compared to graphite materials, limiting their practical application. Therefore, developing a material with good cycle stability and low expansion rate is of great significance.

[0005] Improving the cycle expansion performance of lithium-ion batteries can be achieved by improving the chemical structure and conductivity of battery materials, or by adjusting the properties of battery materials and improving the characteristics of battery electrodes, such as the uniformity and consistency of particle distribution in the electrodes. However, existing technologies suffer from problems such as uneven particle distribution and poor consistency in the electrodes. Summary of the Invention

[0006] This application provides a silicon-based anode material, its preparation method, and a lithium-ion battery, to solve the problems of non-uniformity of material particles, poor conductivity, poor cycle stability, and poor rate performance of existing silicon-based materials in battery anode sheets.

[0007] In a first aspect, this application provides a silicon-based anode material, wherein the silicon-based anode material comprises an active material, and the peak coefficient A of the particle size distribution of the silicon-based anode material satisfies: 0 < A ≤ 3; where A = (D 95 -D5) / [2.5*(D 75 -D 25 )],D 95 D5, D 75 D 25 These represent the particle size of the silicon-based anode material when the volume percentage content reaches 95%, 5%, 75%, and 25% respectively on the cumulative curve;

[0008] The silicon-based anode material includes an active material, which includes SiO2. x SiO x / C、SiO x At least one of / M, Si, Si / C and Si / M, wherein 0 < x ≤ 2, and M includes at least one of metal, nonmetal, metal oxide and nonmetal oxide.

[0009] In the above scheme, by adjusting the particle size of the silicon-based anode material, a silicon-based anode material with a suitable particle size distribution is obtained, which can solve the problems of poor conductivity, poor cycle stability, and poor rate performance of existing silicon-based anode materials. By adjusting the peak coefficient A of the particle size distribution to satisfy: 0 < A ≤ 3, the particle size distribution at both ends of the silicon-based anode material can be more concentrated, and particles with excessively large differences from the median particle size will not appear. When A > 3, particles with large differences from the median particle size exist in the material, resulting in a large difference in particle size among the particles. After being coated into an electrode sheet, during battery cycling, some stress concentration occurs, causing the electrode sheet to pulverize or even fall off, leading to faster battery failure. By rationally selecting the peak coefficient A of the particle size, the consistency of each particle in the silicon-based anode material can be ensured. This improves the stability of the slurry during the coating process, resulting in better uniformity of the binder and conductive agent distribution on different particle surfaces. Consequently, the coated electrode exhibits good consistency. Good electrode consistency leads to high uniformity in the expansion and contraction of different particles during charge and discharge, preventing electrode damage, battery cycle performance degradation, and increased battery expansion caused by uneven expansion and contraction of local particles. Ultimately, this results in high battery performance consistency. Furthermore, by avoiding large differences in particle size, the conductive agent can adhere evenly and effectively to each particle, improving the battery's rate performance. Through specific constraints on the active materials in the silicon-based anode material, the prepared silicon-based anode material can achieve an ideal high specific capacity.

[0010] In conjunction with the first aspect, in one feasible implementation, the particle size distribution of the silicon-based anode material is: 0 < D5 ≤ 65 μm, 0 < D 25 ≤69μm, 0<D 75 ≤75μm, 0<D 95 ≤79μm.

[0011] In conjunction with the first aspect, in one feasible implementation, the sorting coefficient B of the particle size distribution of the silicon-based anode material satisfies: 0 < B ≤ 3, where B = (D 84 -D 16 ) / 4+(D 95 -D5) / 6.6, D 84 D 16 D 95D5 and D5 represent the particle size of the silicon-based anode material when the volume percentage content reaches 84%, 16%, 95%, and 5% respectively on the cumulative curve.

[0012] This scheme selects a sorting coefficient B for the particle size distribution of silicon-based anode materials that satisfies the condition: 0 < B ≤ 3. This ensures that the binder is evenly distributed when the silicon-based anode materials are combined with the binder to form an electrode sheet, thereby improving the peel strength of the electrode sheet and facilitating the construction of a stable and complete conductive network.

[0013] In conjunction with the first aspect, in one feasible implementation, the particle size distribution of the silicon-based anode material is: 0 < D5 ≤ 65 μm, 0 < D 16 ≤67μm, 0<D 84 ≤77μm, 0<D 95 ≤79μm.

[0014] In conjunction with the first aspect, in one feasible implementation, the sorting coefficient B and the peak coefficient A satisfy: 0 < B / A ≤ 5.

[0015] In conjunction with the first aspect, in one feasible implementation, the infrared spectroscopy of the silicon-based anode material is measured at a wavenumber of 3200 cm⁻¹. -1 -3600cm -1 There are peaks within the range.

[0016] In conjunction with the first aspect, in one feasible implementation, the Wadell sphericity of the silicon-based anode material is ≥0.6.

[0017] Understandably, when the Wadell sphericity of the silicon-based anode material is ≥0.6 and the peak coefficient A of its particle size distribution satisfies: 0<A≤3, the space reserved between the particles in the electrode made of the silicon-based material is used to buffer the volume expansion of the silicon-based material during charging and discharging, thereby improving the cycle performance of the material and reducing the expansion of the material.

[0018] In conjunction with the first aspect, in one feasible implementation, the silicon-based anode material further includes a coating layer located on the surface of the active material, the coating layer comprising at least one of a flexible polymer and a conductive material.

[0019] Understandably, when the peak coefficient A of the particle size distribution of the silicon-based anode material satisfies: 0 < A ≤ 3, the coating thickness of the flexible polymer on each particle is consistent, the flexible polymer has a better buffering effect on the volume change during the charging and discharging process, improves the cycle performance of the material, and reduces the expansion of the material.

[0020] In conjunction with the first aspect, in one feasible implementation, the conductive material includes flake graphite and nano-carbon materials.

[0021] In conjunction with the first aspect, in one feasible implementation, the flexible polymer includes natural flexible polymers and / or synthetic flexible polymers.

[0022] In conjunction with the first aspect, in one feasible embodiment, the flexible polymer includes at least one of polyolefins and their derivatives, polyvinyl alcohol and its derivatives, polyacrylic acid and its derivatives, polyamides and their derivatives, carboxymethyl cellulose and its derivatives, alginate and its derivatives, and polycarbonate and its derivatives.

[0023] In conjunction with the first aspect, in one feasible implementation, the weight-average molecular weight of the flexible polymer is 2,000-1,000,000.

[0024] In conjunction with the first aspect, in one feasible embodiment, the flexible polymer contains thermally crosslinked functional groups, including at least one selected from epoxy, carboxyl, hydroxyl, amino, double, and triple bonds.

[0025] In conjunction with the first aspect, in one feasible implementation, the flake graphite includes natural flake graphite and / or artificial flake graphite.

[0026] In conjunction with the first aspect, in one feasible implementation, the nano-carbon material includes at least one of conductive graphite, graphene, carbon nanotubes, and carbon nanofibers.

[0027] In conjunction with the first aspect, in one feasible implementation, the flexible polymer has a mass percentage of 0-10% based on the total mass of the silicon-based anode material being 100%, and does not include 0.

[0028] In conjunction with the first aspect, in one feasible implementation, the mass percentage of the flake graphite is 0-20% based on the total mass of the silicon-based anode material as 100%, and does not include 0.

[0029] In conjunction with the first aspect, in one feasible implementation, the mass percentage of the nano-carbon material is 0-5% based on the total mass of the silicon-based anode material as 100%, and does not include 0.

[0030] In conjunction with the first aspect, in one feasible implementation, the thickness of the coating layer is 10 nm to 5000 nm.

[0031] In conjunction with the first aspect, in one feasible implementation, the coating layer accounts for 0-20% of the mass of the silicon-based anode material, and does not include 0.

[0032] In conjunction with the first aspect, in one feasible implementation, the coating layer accounts for 2% to 10% of the mass of the silicon-based anode material.

[0033] In conjunction with the first aspect, in one feasible implementation, the particle size D50 of the active material is greater than 0 μm and less than or equal to 80 μm.

[0034] In conjunction with the first aspect, in one feasible implementation, the specific surface area of ​​the active material is 0-10 m². 2 / g, and not 0.

[0035] In conjunction with the first aspect, in one feasible implementation, the tap density of the active material is 0.5 g / m³. 3 ~2g / m 3 .

[0036] In conjunction with the first aspect, in one feasible implementation, the silicon-based anode material further includes a dopant material doped into the active material, the dopant material satisfying at least one of the following characteristics:

[0037] (1) The doped material includes at least one of alkali metal, alkaline earth metal, alkali metal oxide or alkaline earth metal oxide;

[0038] (2) The weight percentage b of the doped material in the silicon-based anode material satisfies: 0 < b ≤ 20%.

[0039] Secondly, this application also provides a method for preparing a silicon-based anode material, the method comprising the following steps:

[0040] Preparation of powdered silicon-based anode materials;

[0041] The particle size of the prepared powdered silicon-based anode material is adjusted to obtain a silicon-based anode material; the peak value coefficient A of the particle size distribution of the silicon-based anode material satisfies: 0 < A ≤ 3; where A = (D 95 -D5) / [2.5*(D 75 -D 25 )],D 95 D5, D 75 D 25 These represent the particle size of the silicon-based anode material when the volume percentage content reaches 95%, 5%, 75%, and 25% respectively on the cumulative curve;

[0042] The silicon-based anode material includes an active material, which includes SiO2. x SiO x / C、SiO x At least one of / M, Si, Si / C and Si / M, wherein 0 < x ≤ 2, and M includes at least one of metal, nonmetal, metal oxide and nonmetal oxide.

[0043] In conjunction with the second aspect, in one feasible implementation, the sorting coefficient B of the particle size distribution of the silicon-based anode material satisfies: 0 < B ≤ 3, where B = (D 84 -D 16 ) / 4+(D 95 -D5) / 6.6, D 84 D 16 D 95 D5 and D5 represent the particle size at which the volume percentage content reaches 84%, 16%, 95%, and 5% on the cumulative curve, respectively.

[0044] In conjunction with the second aspect, in one feasible implementation, the method for preparing the powdered silicon-based anode material further includes: pulverizing the active material to obtain the powdered silicon-based anode material.

[0045] In conjunction with the second aspect, in one feasible implementation, the powdering method includes crushing and ball milling.

[0046] In conjunction with the second aspect, in one feasible implementation, the crushing device includes a crusher, and the crushing power p of the crusher satisfies: 0 < p ≤ 300 kW.

[0047] In conjunction with the second aspect, in one feasible implementation, the ball milling apparatus includes a ball mill with a rotational speed v1 satisfying: 0 < v1 ≤ 1500 rpm.

[0048] In conjunction with the second aspect, in one feasible implementation, the device used for particle size adjustment includes a classifier; the frequency f of the classifier's induced draft fan satisfies: 0 < f ≤ 100 Hz.

[0049] In conjunction with the second aspect, in one feasible implementation, the sorting coefficient B and the peak coefficient A satisfy: 0 < B / A ≤ 5.

[0050] In conjunction with the second aspect, in one feasible implementation, the particle size D50 of the active material is greater than 0 μm and less than or equal to 80 μm.

[0051] In conjunction with the second aspect, in one feasible implementation, the method for preparing the powdered silicon-based anode material further includes: coating the powdered active material with carbon material to obtain the powdered silicon-based anode material; wherein the weight percentage 'a' of the carbon material in the silicon-based anode material satisfies: 0 < a ≤ 15%.

[0052] In conjunction with the second aspect, in one feasible embodiment, the method for preparing the powdered silicon-based anode material further includes: polymer coating the powdered active material or carbon coating the powdered active material with carbon material and then polymer coating it to obtain the powdered silicon-based anode material.

[0053] In conjunction with the second aspect, in one feasible implementation, the polymer coating method includes the following steps:

[0054] The flexible polymer is dissolved in a solvent to obtain a flexible polymer solution;

[0055] Under stirring conditions, a conductive material comprising flake graphite and nano-carbon materials is added to the flexible polymer solution to obtain a mixed coating solution.

[0056] Add an antisolvent to the mixed coating solution and stir to obtain a supersaturated mixed coating solution;

[0057] Under stirring conditions, a silicon-based active material is added to the supersaturated mixed coating solution, stirred, and separated to obtain the negative electrode material precursor; and

[0058] The precursor of the anode material is subjected to heat treatment to obtain the powdered silicon-based anode material.

[0059] In conjunction with the second aspect, the flexible polymer contains thermally crosslinked functional groups, including at least one of epoxy, carboxyl, hydroxyl, amino, double, and triple bonds.

[0060] In conjunction with the second aspect, in one feasible embodiment, the solvent includes at least one selected from water, methanol, ethanol, polypyrrolidone, isopropanol, acetone, petroleum ether, tetrahydrofuran, ethyl acetate, N,N-dimethylacetamide, N,N-dimethylformamide, n-hexane, and halogenated hydrocarbons.

[0061] In conjunction with the second aspect, in one feasible implementation, the antisolvent comprises a poor solvent for the flexible polymer.

[0062] In conjunction with the second aspect, in one feasible embodiment, the antisolvent includes at least one selected from methanol, ethanol, polypyrrolidone, isopropanol, acetone, petroleum ether, tetrahydrofuran, ethyl acetate, N,N-dimethylacetamide, N,N-dimethylformamide, n-hexane, and halogenated hydrocarbons.

[0063] In conjunction with the second aspect, in one feasible implementation, the heat treatment temperature is 100℃-400℃, and the heat treatment time is 2h-12h.

[0064] In conjunction with the second aspect, in one feasible implementation, the method for preparing the powdered silicon-based anode material further includes: doping the powdered active material with a doping material to obtain the powdered silicon-based anode material.

[0065] In conjunction with the second aspect, in one feasible implementation, the doping material includes at least one of alkali metals, alkaline earth metals, alkali metal oxides, and alkaline earth metal oxides.

[0066] In conjunction with the second aspect, in one feasible implementation, the weight percentage b of the doped material in the silicon-based anode material satisfies: 0 < b ≤ 20%.

[0067] Thirdly, this application also provides a lithium-ion battery, the lithium-ion battery comprising the silicon-based anode material described above or the silicon-based anode material prepared by the preparation method described above.

[0068] The technical solution of this application has at least the following beneficial effects:

[0069] This application provides a silicon-based anode material where the peak coefficient A of the particle size distribution satisfies the condition 0 < A ≤ 3. This allows for a more concentrated distribution of particle size at both ends, preventing particles with excessively large differences from the median particle size. By rationally selecting the peak coefficient A, the consistency of each particle in the silicon-based anode material is ensured. This improves the stability of the slurry during coating, resulting in better uniformity of the binder and conductive agent distribution on different particle surfaces. Consequently, the coated electrode exhibits good consistency. Good electrode consistency leads to high uniformity in the expansion and contraction of different particles during charge and discharge, preventing electrode damage, battery cycle performance degradation, and increased battery expansion due to uneven expansion and contraction of local particles. Ultimately, this results in high battery performance consistency. Furthermore, by avoiding large differences in particle size, the conductive agent can adhere uniformly and effectively to each particle, improving the battery's rate performance. Through specific constraints on the active materials in the silicon-based anode material, an ideal high specific capacity can be achieved.

[0070] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0071] Figure 1 This is a flowchart of the preparation method of the silicon-based anode material of this application;

[0072] Figure 2 This is a particle size distribution diagram of the silicon-based anode material for lithium-ion batteries obtained in Example 1 of this application;

[0073] Figure 3 This is a particle size distribution diagram of the silicon-based anode material for lithium-ion batteries obtained in Comparative Example 1 of this application;

[0074] Figure 4 This is a SEM image of the silicon-based anode material for lithium-ion batteries obtained in Example 1 of this application;

[0075] Figure 5 This is a SEM image of the silicon-based anode material for lithium-ion batteries obtained in Comparative Example 1 of this application.

[0076] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. Detailed Implementation

[0077] The following are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the embodiments of the present invention, and these improvements and modifications are also considered to be within the protection scope of the embodiments of the present invention.

[0078] Firstly, this application provides a silicon-based anode material, wherein the peak value coefficient A of the particle size distribution of the silicon-based anode material satisfies: 0 < A ≤ 3; where A = (D 95 -D5) / [2.5*(D 75 -D 25 )],D 95 D5, D 75 D 25 These represent the particle sizes at which the volume percentage content on the cumulative curves reaches 95%, 5%, 75%, and 25%, respectively.

[0079] Silicon-based anode materials include active materials, such as SiO₂. x SiO x / C、SiO x At least one of / M, Si, Si / C and Si / M, wherein 0 < x ≤ 2, and M includes at least one of metal, nonmetal, metal oxide and nonmetal oxide.

[0080] In the above scheme, by adjusting the particle size of the silicon-based anode material, a silicon-based anode material with a suitable particle size distribution is obtained, which can solve the problems of poor conductivity, poor cycle and rate performance of existing silicon-based anode materials. This scheme adjusts the peak coefficient A of the silicon-based anode material particle size to satisfy: 0 < A ≤ 3. This makes the particle size distribution at both ends of the silicon-based anode material more concentrated, preventing particles with excessively large differences from the median particle size. When A > 3, particles with large differences from the median particle size exist in the material, resulting in a large difference in particle size among the particles. After being coated into an electrode sheet, stress concentration occurs in certain areas during battery cycling, causing the electrode sheet to pulverize or even detach, leading to faster battery failure. Optionally, the peak coefficient A can be 0.5, 1, 1.2, 1.5, 1.8, 2, 2.5, 2.8, or 3, etc., or other values ​​within the above range, which are not limited here. By rationally selecting the peak coefficient A of the particle size distribution, the consistency of each particle in the silicon-based anode material can be ensured. This improves the stability of the slurry during the coating process, resulting in better uniformity of the binder and conductive agent distribution on the surfaces of different particles. Consequently, the coated electrode exhibits better consistency. Good electrode consistency leads to higher uniformity in the expansion and contraction of different particles during charge and discharge, preventing electrode damage, battery cycle performance degradation, and increased battery expansion caused by uneven expansion and contraction of local particles. Ultimately, this results in high battery performance consistency. Furthermore, by avoiding large differences in particle size, the conductive agent can adhere evenly and effectively to each particle, improving the battery's rate performance. Through specific constraints on the active materials in the silicon-based anode material, the prepared silicon-based anode material can achieve an ideal high specific capacity.

[0081] The following is a detailed introduction to this plan:

[0082] In some embodiments, the particle size distribution of the silicon-based anode material is: 0 < D5 ≤ 65 μm, 0 < D 25 ≤69μm, 0<D 75 ≤75μm, 0<D 95 ≤79μm.

[0083] In some embodiments, the sorting factor B of the particle size distribution of the silicon-based anode material satisfies: 0 < B ≤ 3, where B = (D 84 -D 16 ) / 4+(D 95 -D5) / 6.6, D 84 D 16 D 95 D5 and D5 represent the particle size of the silicon-based anode material when the volume percentage content reaches 84%, 16%, 95%, and 5% respectively on the cumulative curve.

[0084] By selecting the sorting coefficient B for particle size, the particle size distribution of silicon-based anode materials can be ensured to be concentrated. Optionally, the sorting coefficient B can be 0.5, 1, 1.2, 1.5, 1.8, 2, 2.5, 2.8 or 3, etc., or other values ​​within the above range, which are not limited here.

[0085] In some embodiments, the particle size distribution of the silicon-based anode material is: 0 < D5 ≤ 65 μm, 0 < D 16 ≤67μm, 0<D 84 ≤77μm, 0<D 95 ≤79μm.

[0086] In some implementations, the sorting coefficient B and the peak coefficient A satisfy: 0 < B / A ≤ 5.

[0087] Optionally, the ratio B / A of the sorting coefficient B and the peak coefficient A can be 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, or other values ​​within the above range, which are not limited here. Understandably, by specifically limiting the ratio B / A of the sorting coefficient B and the peak coefficient A, the agglomeration of active material particles can be more effectively avoided. When B / A > 5, it will lead to the agglomeration of active material particles after the silicon-based anode material slurry is coated, affecting battery performance.

[0088] In some embodiments, the infrared spectroscopy of the silicon-based anode material is measured at a wavenumber of 3200 cm⁻¹. -1 -3600cm -1 There are peaks within the range.

[0089] In some implementations, the Wadell sphericity of the silicon-based anode material is ≥0.6. Higher sphericity significantly improves the uniformity of the electrode.

[0090] Optionally, the Wadell sphericity of the silicon-based anode material can be 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, etc.

[0091] In some embodiments, the silicon-based anode material further includes a coating layer located on the surface of the active material, the coating layer comprising at least one of a flexible polymer and a conductive material.

[0092] In some implementations, the conductive material includes flake graphite and nano-carbon materials.

[0093] In some embodiments, the flexible polymer includes natural flexible polymers and / or synthetic flexible polymers.

[0094] In some embodiments, the flexible polymer includes at least one of polyolefins and their derivatives, polyvinyl alcohol and its derivatives, polyacrylic acid and its derivatives, polyamides and their derivatives, carboxymethyl cellulose and its derivatives, alginate and its derivatives, and polycarbonate and its derivatives.

[0095] In some embodiments, the weight-average molecular weight of the flexible polymer is 2,000-1,000,000.

[0096] Optionally, the weight-average molecular weight of the flexible polymer can be 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 20000, 30000, 50000, 80000, 100000, 200000, 300000, 500000, 80000, or 1000000, etc., or other values ​​within the above range, which are not limited here.

[0097] In some embodiments, the flexible polymer contains thermally crosslinked functional groups, including at least one of epoxy, carboxyl, hydroxyl, amino, double, and triple bonds.

[0098] In some embodiments, flake graphite includes natural flake graphite and / or artificial flake graphite.

[0099] In some embodiments, the carbon nanomaterials include at least one of conductive graphite, graphene, carbon nanotubes, and carbon nanofibers.

[0100] In some embodiments, the flexible polymer is 0-10% of the total mass of the silicon-based anode material, excluding 0.

[0101] Optionally, based on the total mass of the silicon-based anode material as 100%, the mass percentage of the flexible polymer can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%, etc., or other values ​​within the above range, which are not limited here.

[0102] In some embodiments, the mass percentage of flake graphite is 0-20% based on the total mass of the silicon-based anode material as 100%, and does not include 0.

[0103] Optionally, based on the total mass of the silicon-based anode material as 100%, the mass percentage of flake graphite can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%, etc., or other values ​​within the above range, which are not limited here.

[0104] In some implementations, the mass percentage of nano-carbon materials is 0-5% based on the total mass of silicon-based anode materials as 100%, excluding 0.

[0105] Optionally, based on the total mass of silicon-based anode materials as 100%, the mass percentage of nano-carbon materials can be 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, or 5%, etc., or other values ​​within the above range, which are not limited here.

[0106] In some embodiments, the thickness of the coating layer is 10 nm to 5000 nm.

[0107] Optionally, the thickness of the coating layer can be 10nm, 50nm, 100nm, 200nm, 500nm, 800nm, 1000nm, 2000nm, 3000nm, 4000nm or 5000nm, etc., or other values ​​within the above range, which are not limited here.

[0108] In some embodiments, the coating layer accounts for 0-20% of the mass of the silicon-based anode material, but does not include 0.

[0109] Optionally, the mass percentage of the coating layer in the silicon-based anode material can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%, etc., or other values ​​within the above range, which are not limited here.

[0110] In some embodiments, the coating layer accounts for 2% to 10% of the mass of the silicon-based anode material.

[0111] In some embodiments, the particle size D50 of the active material is greater than 0 μm and less than or equal to 80 μm, and the particle size is tested using methods including laser scattering. Optionally, the particle size D50 of the active material can be 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, or 80 μm, or other values ​​within the above range, which are not limited here. Understandably, by appropriately selecting the particle size of the active material, the cycle performance and battery expansion performance of the lithium-ion battery made from silicon-based anode materials can be guaranteed. If the particle size D50 of the active material is greater than 80 μm, it will negatively affect the battery's cycle performance and battery expansion performance.

[0112] In some embodiments, the specific surface area of ​​the active material is 0-10 m². 2 / g, and not 0. Optionally, the specific surface area of ​​the active material can be 1m².2 / 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., can also be other values ​​within the above range, and are not limited here.

[0113] In some embodiments, the tap density of the active material is 0.5 g / m³. 3 ~2g / m 3 Optionally, the tap density of the active material can be 0.5 g / m³. 3 0.6g / m 3 0.8g / m 3 1.0g / m 3 1.2g / m 3 1.5g / m 3 1.8g / m 3 or 2g / m 3 "etc." can also be other values ​​within the above range, and no restrictions are imposed here.

[0114] In some embodiments, the silicon-based anode material further includes a dopant material doped into the active material, the dopant material including at least one of alkali metal, alkaline earth metal, alkali metal oxide and alkaline earth metal oxide;

[0115] In some implementations, the weight percentage b of the doped material in the silicon-based anode material satisfies: 0 < b ≤ 20%.

[0116] Optionally, the alkali metal can be selected from lithium, sodium, and potassium; the alkaline earth metal can be selected from magnesium, calcium, strontium, and barium; the alkali metal oxide can be selected from lithium oxide, sodium oxide, and potassium oxide; and the alkaline earth metal oxide can be selected from magnesium oxide, calcium oxide, strontium oxide, and barium oxide. The weight percentage b of the doped material in the silicon-based anode material can be 1%, 3%, 5%, 8%, 10%, 12%, 15%, 18%, or 20%, or other values ​​within the above range, and is not limited here. Understandably, by doping the silicon-based anode material with metal materials, the intrinsic conductivity of the active material can be improved. Furthermore, by selecting the type and content of the doped material, the conductivity of the active material can be improved more effectively.

[0117] It should be noted that the silicon-based anode materials in the above embodiments can be combined arbitrarily without contradicting each other, such as by combining and limiting the particle size and specific surface area of ​​the active materials.

[0118] Secondly, embodiments of this application also provide a method for preparing a silicon-based anode material, the method comprising the following steps:

[0119] Step S100: Prepare powdered silicon-based anode material;

[0120] Step S200: Adjust the particle size of the prepared powdered silicon-based anode material to obtain a silicon-based anode material; the peak coefficient A of the particle size distribution of the silicon-based anode material satisfies: 0 < A ≤ 3; where A = (D 95 -D5) / [2.5*(D 75 -D 25 )],D 95 D5, D 75 D 25 These represent the particle size of the silicon-based anode material when the volume percentage content reaches 95%, 5%, 75%, and 25% respectively on the cumulative curve;

[0121] Silicon-based anode materials include active materials, such as SiO₂. x SiO x / C、SiO x At least one of / M, Si, Si / C and Si / M, wherein 0 < x ≤ 2, and M includes at least one of metal, nonmetal, metal oxide and nonmetal oxide.

[0122] In some embodiments, the sorting factor B of the particle size distribution of the silicon-based anode material satisfies: 0 < B ≤ 3, where B = (D 84 -D 16 ) / 4+(D 95 -D5) / 6.6, D 84 D 16 D 95 D5 and D5 represent the particle size at which the volume percentage content reaches 84%, 16%, 95%, and 5% on the cumulative curve, respectively.

[0123] In some embodiments, the method for preparing powdered silicon-based anode materials further includes: pulverizing active materials to obtain powdered silicon-based anode materials.

[0124] In the above scheme, the active material is first powdered to obtain a powdered silicon-based anode material with a suitable particle size. Then, the peak coefficient A of the particle size of the powdered silicon-based anode material is reasonably selected to obtain a silicon-based anode material with a suitable particle size distribution. This can solve the problems of low initial coulombic efficiency, poor conductivity, and poor cycle and rate performance of existing active materials as silicon-based anode materials.

[0125] In some implementations, the powdering methods include crushing and ball milling.

[0126] In some implementations, the crushing device includes a crusher with a crushing power p satisfying: 0 < p ≤ 300 kW.

[0127] In some embodiments, the ball milling apparatus includes a ball mill with a rotational speed v1 satisfying: 0 < v1 ≤ 1500 rpm.

[0128] In some embodiments, the device used for particle size adjustment includes a classifier; the frequency f of the classifier's fan satisfies: 0 < f ≤ 100 Hz.

[0129] In some implementations, the sorting coefficient B and the peak coefficient A satisfy: 0 < B / A ≤ 5.

[0130] In some embodiments, the particle size D50 of the active material is greater than 0 μm and less than or equal to 80 μm.

[0131] Optionally, the crushing power p of the crusher can be 5kW, 10kW, 20kW, 50kW, 100kW, 150kW, 200kW, 250kW, or 300kW, etc., and the rotational speed v1 of the ball mill can be 200rpm, 400rpm, 600rpm, 800rpm, 1000rpm, 1200rpm, or 1500rpm, etc., or other values ​​within the above range, which are not limited here. Understandably, by rationally selecting the crushing power p and the rotational speed v1 of the ball mill used in the powdering process, active materials with suitable particle size can be obtained, which is beneficial for subsequent particle size adjustment.

[0132] Optionally, the frequency f of the classifier's induced draft fan can be 1Hz, 5Hz, 10Hz, 20Hz, 30Hz, 50Hz, 70Hz, 90Hz, or 100Hz, or other values ​​within the above range, without limitation. Understandably, by appropriately selecting the frequency f of the classifier's induced draft fan, the sorting coefficient B and peak value A of the silicon-based anode material's particle size distribution can satisfy: 0 < B ≤ 3, 0 < A ≤ 3.

[0133] Optionally, the particle size D50 of the active material can be 1μm, 5μm, 10μm, 15μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, or 80μm, or other values ​​within the above range, without limitation. Understandably, by appropriately selecting the particle size of the active material, the cycle performance and battery expansion performance of the lithium-ion battery made from silicon-based anode materials can be guaranteed. If the particle size D50 of the active material is greater than 80μm, it will negatively impact the battery's cycle performance and battery expansion performance.

[0134] In some embodiments, the method for preparing powdered silicon-based anode materials further includes: coating the powdered active material with carbon material to obtain powdered silicon-based anode materials; the weight percentage 'a' of carbon material in the silicon-based anode material satisfies: 0 < a ≤ 15%.

[0135] Optionally, the weight percentage 'a' of carbon material in the silicon-based anode material can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%, etc., or other values ​​within the above range, without limitation. Understandably, by adding carbon material to the silicon-based anode material, allowing the carbon material to coat the surface of the active material, the problems of volume change and conductivity of silicon-based anode materials in silicon-based lithium-ion batteries during lithium insertion / extraction processes can be effectively solved.

[0136] In some embodiments, the carbon coating method includes mixing and heat-treating a third raw material comprising a calcined material and an organic carbon source in a protective atmosphere or vacuum environment.

[0137] The above-mentioned carbon coating method includes: mixing a third raw material, including the above-mentioned calcined material and an organic carbon source, and heat-treating it in a protective atmosphere or vacuum environment.

[0138] Specifically, the aforementioned carbon coating can be categorized as gas-phase carbon coating and / or solid-phase carbon coating.

[0139] In some embodiments, the carbon coating of this application adopts a gas-phase carbon coating method, specifically including: heating the above-mentioned calcined material to 600℃-1000℃ under a protective atmosphere, introducing an organic carbon source gas, holding at this temperature for 0.5h-10h, and then cooling. The organic carbon source gas can be selected from hydrocarbons (such as alkanes, cycloalkanes, alkenes, alkynes, and aromatic hydrocarbons), specifically at least one of methane, ethylene, acetylene, and benzene.

[0140] Optionally, the heat treatment temperature in the vapor-phase carbon coating method can be 600℃, 700℃, 800℃, 900℃, 1000℃, etc., and the holding time can be 0.5h, 1.5h, 2.5h, 3.5h, 4.5h, 5.5h, 6.5h, 7.5h, 8.5h, 9.5h, 10h, etc., and is not limited here. Preferably, the heat treatment temperature can be 700-900℃, and the holding time can be 3-9h.

[0141] In some embodiments, the carbon coating of this application adopts a solid-phase carbon coating method. Specifically, the method includes: fusing the above-mentioned calcined material with a carbon source for at least 0.5 hours, then carbonizing the resulting carbon mixture at 600℃-1000℃ for 2-6 hours, followed by cooling. The carbon source may be selected from at least one of polyolefins, resins, rubbers, sugars (such as glucose, sucrose, starch, and cellulose), organic acids, and asphalt.

[0142] Optionally, the heat treatment temperature in the solid-phase carbon coating method can be 600℃, 700℃, 800℃, 900℃, 1000℃, etc., and the heat treatment holding time can be 2h, 3h, 4h, 5h, 6h, etc., without limitation. Preferably, the heat treatment temperature can be 700℃-900℃, and the heat treatment holding time can be 3h-5h.

[0143] In the above scheme, the fusion is preferably carried out in a fusion machine with a rotation speed of 500 r / min-3000 r / min.

[0144] Optionally, the specific rotational speed of the fusion machine can be 500 r / min, 800 r / min, 1000 r / min, 1500 r / min, 2000 r / min, 2500 r / min, 3000 r / min, etc., and is not limited here. Preferably, the rotational speed of the fusion machine can be 1000-3000 r / min.

[0145] The tool gap width of the fusion machine can be selected as needed, for example, 0.5cm.

[0146] The protective atmosphere in the above carbon coating method can be at least one of helium, neon, argon and nitrogen.

[0147] In some embodiments, the method for preparing powdered silicon-based anode materials further includes: polymer coating the powdered active material, or carbon coating the powdered active material with carbon material and then polymer coating it to obtain powdered silicon-based anode materials.

[0148] In some embodiments, the polymer coating method includes the following steps:

[0149] The flexible polymer is dissolved in a solvent to obtain a flexible polymer solution;

[0150] Under stirring conditions, a conductive material comprising flake graphite and nano-carbon materials is added to a flexible polymer solution to obtain a mixed coating solution.

[0151] Add antisolvent to the mixed coating solution and stir to obtain a supersaturated mixed coating solution;

[0152] Under stirring conditions, silicon-based active material is added to the supersaturated mixed coating solution, stirred, and separated to obtain the precursor of the negative electrode material; and

[0153] The precursor of the anode material is heat-treated to obtain powdered silicon-based anode material.

[0154] In some embodiments, the flexible polymer contains thermally crosslinked functional groups, including at least one of epoxy, carboxyl, hydroxyl, amino, double, and triple bonds.

[0155] In some embodiments, the solvent includes at least one selected from water, methanol, ethanol, polypyrrolidone, isopropanol, acetone, petroleum ether, tetrahydrofuran, ethyl acetate, N,N-dimethylacetamide, N,N-dimethylformamide, n-hexane, and halogenated hydrocarbons.

[0156] In some implementations, the antisolvent includes a poor solvent for the flexible polymer.

[0157] In some embodiments, the antisolvent includes at least one selected from methanol, ethanol, polypyrrolidone, isopropanol, acetone, petroleum ether, tetrahydrofuran, ethyl acetate, N,N-dimethylacetamide, N,N-dimethylformamide, n-hexane, and halogenated hydrocarbons.

[0158] In some embodiments, the heat treatment temperature is 100℃-400℃ and the heat treatment time is 2h-12h.

[0159] Optionally, the heat treatment temperature can be 100℃, 120℃, 150℃, 180℃, 200℃, 220℃, 250℃, 280℃, 300℃, 320℃, 350℃, 380℃, or 400℃, or other values ​​within the above range, which are not limited here. The heat treatment time can be 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, or 12h, or other values ​​within the above range, which are not limited here.

[0160] In some embodiments, the method for preparing powdered silicon-based anode materials further includes: doping the powdered active material with a doping material to obtain the powdered silicon-based anode material.

[0161] In some embodiments, the doping material includes at least one of alkali metals, alkaline earth metals, alkali metal oxides, and alkaline earth metal oxides.

[0162] In some implementations, the weight percentage b of the doped material in the silicon-based anode material satisfies: 0 < b ≤ 20%.

[0163] Optionally, the alkali metal can be selected from lithium, sodium, and potassium; the alkaline earth metal can be selected from magnesium, calcium, strontium, and barium; the alkali metal oxide can be selected from lithium oxide, sodium oxide, and potassium oxide; and the alkaline earth metal oxide can be selected from magnesium oxide, calcium oxide, strontium oxide, and barium oxide. The weight percentage b of the doped material in the silicon-based anode material can be 1%, 3%, 5%, 8%, 10%, 12%, 15%, 18%, or 20%, or other values ​​within the above range, and is not limited here. Understandably, by doping the silicon-based anode material with metal materials, the intrinsic conductivity of the active material can be improved. Furthermore, by selecting the type and content of the doped material, the conductivity of the active material can be improved more effectively. It should be noted that the doping of the powdered active material with doped materials can be performed before or after carbon coating.

[0164] Thirdly, embodiments of this application also provide a lithium-ion battery, which includes: a positive electrode, a negative electrode, a separator, and an electrolyte; the negative electrode includes the aforementioned lithium-ion battery silicon-based negative electrode material or the lithium-ion battery silicon-based negative electrode material prepared by the aforementioned preparation method.

[0165] The embodiments of this application will be further described below with reference to several examples. However, the embodiments of this application are not limited to the specific embodiments described below. Within the scope of protection, appropriate modifications and implementations can be made.

[0166] Example 1

[0167] A method for preparing silicon-based anode material for lithium-ion batteries, as follows: Figure 1 As shown, the process includes the following steps S10 to S30:

[0168] Step S10: Take 1 kg of SiO bulk material for later use. Use a crusher and ball mill to pulverize the bulk material and adjust the D50 of the SiO powder to 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.

[0169] Step S20: The SiO powder obtained in step S10 is coated with carbon material; the weight percentage a of the carbon material in the silicon-based anode material is 7%.

[0170] In step S30, the powder obtained in step S20 is adjusted for particle size using an air classifier. The fan frequency f of the classifier is 55Hz, resulting in the final silicon-based anode material. The sorting coefficient B of the silicon-based anode material particle size distribution is 2.00, the peak coefficient A is 1.80, and B / A = 1.11.

[0171] Example 2

[0172] A method for preparing a silicon-based anode material for lithium-ion batteries includes the following steps S10 to S30:

[0173] Step S10: Take 1 kg of Si bulk material for later use. Use a crusher and ball mill to pulverize the bulk material and adjust the D50 of the Si powder to 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.

[0174] Step S20: The Si powder obtained in step S10 is coated with carbon material; the weight percentage a of the carbon material in the silicon-based anode material is 6.7%.

[0175] In step S30, the powder obtained in step S20 is adjusted for particle size using an air classifier. The fan frequency f of the classifier is 65Hz, resulting in the final silicon-based anode material. The sorting coefficient B of the silicon-based anode material particle size distribution is 1.50, the peak coefficient A is 1.50, and B / A = 1.00.

[0176] Example 3

[0177] A method for preparing a silicon-based anode material for lithium-ion batteries includes the following steps S10 to S30:

[0178] Step S10: Take 1 kg of SiO bulk material for later use. Use a crusher and ball mill to pulverize the bulk material and adjust the D50 of the SiO powder to 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.

[0179] Step S20: The SiO powder obtained in step S10 is coated with carbon material; the weight percentage a of the carbon material in the silicon-based anode material is 6.8%.

[0180] In step S30, the powder obtained in step S20 is adjusted for particle size using an air classifier. The fan frequency f of the classifier is 35Hz, resulting in the final silicon-based anode material. The sorting coefficient B of the silicon-based anode material particle size distribution is 3.00, the peak coefficient A is 1.50, and B / A = 2.00.

[0181] Example 4

[0182] A method for preparing a silicon-based anode material for lithium-ion batteries includes the following steps S10 to S30:

[0183] Step S10: Take 1 kg of SiO bulk material for later use. Use a crusher and ball mill to pulverize the bulk material and adjust the D50 of the SiO powder to about 5 μm. The crushing power p of the crusher is 70 kW and the rotation speed v1 of the ball mill is 1100 rpm.

[0184] Step S20: The SiO powder obtained in step S10 is coated with carbon material; the weight percentage a of the carbon material in the silicon-based anode material is 7.1%.

[0185] In step S30, the powder obtained in step S20 is adjusted for particle size using an air classifier. The fan frequency f of the classifier is 70Hz, resulting in the final silicon-based anode material. The sorting coefficient B of the silicon-based anode material particle size distribution is 1.20, the peak coefficient A is 3.01, and B / A = 0.40.

[0186] Example 5

[0187] A method for preparing a silicon-based anode material for lithium-ion batteries includes the following steps S10 to S30:

[0188] Step S10: Take 1 kg of SiO bulk material for later use. Use a crusher and ball mill to pulverize the bulk material and adjust the D50 of the SiO powder to about 5 μm. The crushing power p of the crusher is 150 kW and the rotation speed v1 of the ball mill is 600 rpm.

[0189] Step S20: The SiO powder obtained in step S10 is coated with carbon material; the weight percentage a of the carbon material in the silicon-based anode material is 7.1%.

[0190] In step S30, the powder obtained in step S20 is processed using an air classifier to adjust its particle size. The fan frequency f of the classifier is 40Hz, resulting in the final silicon-based anode material. The sorting coefficient B of the silicon-based anode material's particle size distribution is 2.50, the peak coefficient A is 0.50, and B / A = 5.00.

[0191] Example 6

[0192] A method for preparing a silicon-based anode material for lithium-ion batteries includes the following steps S10 to S30:

[0193] Step S10: Take 1 kg of SiO bulk material for later use. Use a crusher and ball mill to pulverize the bulk material and adjust the D50 of the SiO powder to about 5 μm. The crushing power p of the crusher is 150 kW and the rotation speed v1 of the ball mill is 650 rpm.

[0194] Step S20: The SiO powder obtained in step S10 is coated with carbon material; the weight percentage a of the carbon material in the silicon-based anode material is 7.3%.

[0195] In step S30, the powder obtained in step S20 is adjusted for particle size using an air classifier. The fan frequency f of the classifier is 46Hz, resulting in the final silicon-based anode material. The sorting coefficient B of the silicon-based anode material particle size distribution is 2.10, the peak coefficient A is 0.70, and B / A = 3.00.

[0196] Example 7

[0197] A method for preparing a silicon-based anode material for lithium-ion batteries includes the following steps S10 to S30:

[0198] Step S10: Take 1 kg of SiO bulk material for later use. Use a crusher and ball mill to pulverize the bulk material and adjust the D50 of the SiO powder to 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.

[0199] Step S20: The SiO powder obtained in step S10 is coated with carbon material; the weight percentage a of the carbon material in the silicon-based anode material is 7%.

[0200] In step S30, the powder obtained in step S20 is adjusted for particle size using an air classifier. The fan frequency f of the classifier is 75Hz, resulting in the final silicon-based anode material. The sorting coefficient B of the silicon-based anode material particle size distribution is 1.01, the peak coefficient A is 1.20, and B / A = 0.84.

[0201] Example 8

[0202] A method for preparing a silicon-based anode material for lithium-ion batteries includes the following steps S10 to S30:

[0203] Step S10: Take 1 kg of SiO bulk material for later use. Use a crusher and ball mill to pulverize the bulk material and adjust the D50 of the SiO powder to about 5 μm. The crushing power p of the crusher is 120 kW and the rotation speed v1 of the ball mill is 700 rpm.

[0204] Step S20: The SiO powder obtained in step S10 is coated with carbon material; the weight percentage a of the carbon material in the silicon-based anode material is 7.2%.

[0205] In step S30, the powder obtained in step S20 is adjusted for particle size using an air classifier. The fan frequency f of the classifier is 60Hz, resulting in the final silicon-based anode material. The sorting coefficient B of the silicon-based anode material particle size distribution is 1.60, the peak coefficient A is 1.00, and B / A = 1.60.

[0206] Example 9

[0207] A method for preparing a silicon-based anode material for lithium-ion batteries includes the following steps S10 to S30:

[0208] Step S10: Take 1 kg of SiO bulk material for later use. Use a crusher and ball mill to pulverize the bulk material and adjust the D50 of the SiO powder to about 20 μm. The crushing power p of the crusher is 90 kW and the rotation speed v1 of the ball mill is 400 rpm.

[0209] Step S20: The SiO powder obtained in step S10 is coated with carbon material; the weight percentage a of the carbon material in the silicon-based anode material is 6.9%.

[0210] In step S30, the powder obtained in step S20 is adjusted for particle size using an air classifier. The fan frequency f of the classifier is 58Hz, resulting in the final silicon-based anode material. The sorting coefficient B of the silicon-based anode material particle size distribution is 1.80, the peak coefficient A is 0.80, and B / A = 2.24.

[0211] Example 10

[0212] A method for preparing a silicon-based anode material for lithium-ion batteries includes the following steps S10 to S40:

[0213] Step S10: Take 1 kg of SiO bulk material for later use. Use a crusher and ball mill to pulverize the bulk material and adjust the D50 of the SiO powder to about 20 μm. The crushing power p of the crusher is 90 kW and the rotation speed v1 of the ball mill is 600 rpm.

[0214] Step S20: The SiO powder obtained in step S10 is coated with carbon material; the weight percentage a of the carbon material in the silicon-based anode material is 7.1%.

[0215] Step S30: The SiO powder that has been carbon-coated in step S20 is doped with a doping material; the doping material is MgO, and the weight percentage b of the doping material in the silicon-based anode material is 5%.

[0216] In step S40, the powder obtained in step S30 is adjusted for particle size using an air classifier. The frequency f of the induced draft fan in the classifier is 56 Hz, resulting in the final silicon-based anode material. The sorting coefficient B of the silicon-based anode material particle size distribution is 1.91, the peak coefficient A is 1.00, and B / A = 1.91.

[0217] Example 11

[0218] Step S10: Take 1 kg of SiO bulk material for later use. Use a crusher and ball mill to pulverize the bulk material and adjust the D50 of the SiO powder to 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.

[0219] In step S20, the powder obtained in step S10 is adjusted for particle size using an air classifier. The fan frequency f of the classifier is 58 Hz, resulting in the final silicon-based anode material. The sorting coefficient B of the silicon-based anode material particle size distribution is 2.20, the peak coefficient A is 1.89, and B / A = 1.16.

[0220] Example 12

[0221] Step S10: Take 1 kg of SiO bulk material for later use. Use a crusher and ball mill to pulverize the bulk material and adjust the D50 of the SiO powder to about 20 μm. The crushing power p of the crusher is 90 kW and the rotation speed v1 of the ball mill is 600 rpm.

[0222] Step S20: The SiO powder obtained in step S10 is doped with a doping material; the doping material is MgO, and the weight percentage b of the doping material in the silicon-based anode material is 5%.

[0223] In step S30, the powder obtained in step S20 is adjusted for particle size using an air classifier. The frequency f of the induced draft fan in the classifier is 55 Hz, resulting in the final silicon-based anode material. The sorting coefficient B of the silicon-based anode material particle size distribution is 1.76, the peak coefficient A is 1.22, and B / A = 1.44.

[0224] Example 13

[0225] Step S10: Take 1 kg of SiO bulk material for later use. Use a crusher and ball mill to pulverize the bulk material and adjust the D50 of the SiO powder to about 20 μm. The crushing power p of the crusher is 90 kW and the rotation speed v1 of the ball mill is 600 rpm.

[0226] Step S20: The SiO powder obtained in step S10 is doped with a doping material; the doping material is MgO, and the weight percentage b of the doping material in the silicon-based anode material is 5%.

[0227] Step S30: The powder obtained in step S20 is coated with carbon material; the weight percentage a of the carbon material in the silicon-based anode material is 7.3%.

[0228] In step S40, the powder obtained in step S20 is adjusted for particle size using an air classifier. The fan frequency f of the classifier is 56Hz, resulting in the final silicon-based anode material. The sorting coefficient B of the silicon-based anode material particle size distribution is 2.17, the peak coefficient A is 1.22, and B / A = 1.78.

[0229] Example 14

[0230] Step S10: Take 1 kg of SiO bulk material for later use. Use a crusher and ball mill to pulverize the bulk material and adjust the D50 of the SiO powder to 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.

[0231] Step S20: The SiO powder obtained in step S10 is processed using a fusion machine at a speed of 1000 r / min for 2 hours.

[0232] Step S30: The SiO powder obtained in step S20 is coated with carbon material; the weight percentage a of the carbon material in the silicon-based anode material is 7.1%.

[0233] In step S40, the powder obtained in step S30 is adjusted for particle size using an air classifier. The fan frequency f of the classifier is 55Hz, resulting in the final silicon-based anode material. The particle size distribution of the silicon-based anode material has a sorting coefficient B of 1.96, a peak value coefficient A of 1.77, a B / A ratio of 1.11, and a sphericity of 0.52.

[0234] Example 15

[0235] Step S10: Take 1 kg of SiO bulk material for later use. Use a crusher and ball mill to pulverize the bulk material and adjust the D50 of the SiO powder to 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.

[0236] Step S20: The SiO powder obtained in step S10 is processed using a fusion machine with a rotation speed of 1000 r / min and a processing time of 4 h.

[0237] Step S30: The SiO powder obtained in step S20 is coated with carbon material; the weight percentage a of the carbon material in the silicon-based anode material is 6.8%.

[0238] In step S40, the powder obtained in step S30 is adjusted for particle size using an air classifier. The fan frequency f of the classifier is 55Hz, resulting in the final silicon-based anode material. The particle size distribution of the silicon-based anode material has a sorting coefficient B of 1.92, a peak value coefficient A of 1.66, a B / A ratio of 1.15, and a sphericity of 0.61.

[0239] Example 16

[0240] Step S10: Take 1 kg of SiO bulk material for later use. Use a crusher and ball mill to pulverize the bulk material and adjust the D50 of the SiO powder to 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.

[0241] Step S20: The SiO powder obtained in step S10 is processed using a fusion machine with a rotation speed of 2500 r / min and a processing time of 6 h.

[0242] In step S30, the SiO powder obtained in step S20 is coated with carbon material; the weight percentage a of the carbon material in the silicon-based anode material is 7.2%.

[0243] In step S40, the powder obtained in step S30 is adjusted for particle size using an air classifier. The fan frequency f of the classifier is 55Hz, resulting in the final silicon-based anode material. The particle size distribution of the silicon-based anode material has a sorting coefficient B of 1.91, a peak value coefficient A of 1.64, a B / A ratio of 1.16, and a sphericity of 0.79.

[0244] Example 17

[0245] Step S10: Take 1 kg of SiO bulk material for later use. Use a crusher and ball mill to pulverize the bulk material and adjust the D50 of the SiO powder to 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.

[0246] Step S20: The SiO powder obtained in step S10 is coated with carbon material; the weight percentage a of the carbon material in the silicon-based anode material is 7%.

[0247] In step S30, the powder obtained in step S20 is adjusted in particle size using an air classifier. The frequency f of the classifier's induced draft fan is 55Hz, resulting in silicon-based anode material with adjusted particle size.

[0248] In step S40, 4g of polyacrylic acid was dissolved in 100g of distilled water. After dissolving completely at 40°C, 1g of carbon nanofibers was added under stirring. After stirring for 2 hours, 200g of ethanol was added and stirring was continued for 0.5 hours. Then, 90g of the material obtained in step S30 was added under stirring. After stirring at 60°C for 2 hours, the mixture was cooled to room temperature. The material was separated by filtration and then placed in a drying oven at 180°C for heat treatment for 4 hours. After cooling, the SiOx anode material coated with polyacrylic acid and carbon nanofibers was obtained. The sorting coefficient B of the obtained silicon-based anode material was 2.00, the peak coefficient A was 1.78, and B / A = 1.12.

[0249] Example 18

[0250] Step S10: Take 1 kg of SiO bulk material for later use. Use a crusher and ball mill to pulverize the bulk material and adjust the D50 of the SiO powder to 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.

[0251] Step S20: The SiO powder obtained in step S10 is coated with carbon material; the weight percentage a of the carbon material in the silicon-based anode material is 7%.

[0252] In step S30, the powder obtained in step S20 is adjusted in particle size using an air classifier. The frequency f of the classifier's induced draft fan is 20Hz, resulting in silicon-based anode material with adjusted particle size.

[0253] In step S40, 4g of polyacrylic acid was dissolved in 100g of distilled water. After dissolving completely at 40°C, 1g of carbon nanofibers was added under stirring. After stirring for 2 hours, 200g of ethanol was added and stirring was continued for 0.5 hours. Then, 90g of the material obtained in step S30 was added under stirring. After stirring at 60°C for 2 hours, the mixture was cooled to room temperature. The material was separated by filtration and then placed in a drying oven at 180°C for heat treatment for 4 hours. After cooling, the SiOx anode material coated with polyacrylic acid and carbon nanofibers was obtained. The sorting coefficient B of the obtained silicon-based anode material was 2.88, the peak coefficient A was 1.27, and B / A = 2.27.

[0254] Comparative Example 1

[0255] A method for preparing a silicon-based anode material for lithium-ion batteries includes the following steps S10 to S30:

[0256] Step S10: Take 1 kg of SiO bulk material for later use. Use a crusher and ball mill to pulverize the bulk material and adjust the D50 of the SiO powder to 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.

[0257] Step S20: The SiO powder obtained in step S10 is coated with carbon material; the weight percentage a of the carbon material in the silicon-based anode material is 7%.

[0258] In step S30, the powder obtained in step S20 is adjusted for particle size using an air classifier. The fan frequency f of the classifier is 10Hz, resulting in the final silicon-based anode material. The sorting coefficient B of the silicon-based anode material particle size distribution is 3.19, the peak coefficient A is 1.30, and B / A = 2.45.

[0259] Comparative Example 2

[0260] A method for preparing a silicon-based anode material for lithium-ion batteries includes the following steps S10 to S30:

[0261] Step S10: Take 1 kg of Si bulk material for later use. Use a crusher and ball mill to pulverize the bulk material and adjust the D50 of the Si powder to about 5 μm. The crushing power p of the crusher is 150 kW and the rotation speed v1 of the ball mill is 550 rpm.

[0262] Step S20: The Si powder obtained in step S10 is coated with carbon material; the weight percentage a of the carbon material in the silicon-based anode material is 6.9%.

[0263] In step S30, the powder obtained in step S20 is adjusted for particle size using an air classifier. The fan frequency f of the classifier is 53Hz, resulting in the final silicon-based anode material. The sorting coefficient B of the silicon-based anode material particle size distribution is 2.42, the peak coefficient A is 0.46, and B / A = 5.24.

[0264] Comparative Example 3

[0265] A method for preparing a silicon-based anode material for lithium-ion batteries includes the following steps S10 to S30:

[0266] Step S10: Take 1 kg of SiO bulk material for later use. Use a crusher and ball mill to pulverize the bulk material and adjust the D50 of the SiO powder to about 5 μm. The crushing power p of the crusher is 150 kW and the rotation speed v1 of the ball mill is 550 rpm.

[0267] Step S20: The SiO powder obtained in step S10 is coated with carbon material; the weight percentage a of the carbon material in the silicon-based anode material is 7.1%.

[0268] In step S30, the powder obtained in step S20 is adjusted for particle size using an air classifier with a blower frequency f of 65 Hz, resulting in the final silicon-based anode material. The sorting coefficient B of the silicon-based anode material particle size distribution is 1.63, the peak coefficient A is 3.04, and B / A = 0.54.

[0269] Comparative Example 4

[0270] A method for preparing a silicon-based anode material for lithium-ion batteries includes the following steps S10 to S30:

[0271] Step S10: Take 1 kg of SiO bulk material for later use. Use a crusher and ball mill to pulverize the bulk material and adjust the Dmax of the SiO powder to about 85 μm. The crushing power p of the crusher is 90 kW and the rotation speed v1 of the ball mill is 100 rpm.

[0272] Step S20: The SiO powder obtained in step S10 is coated with carbon material; the weight percentage a of the carbon material in the silicon-based anode material is 7.1%.

[0273] In step S30, the powder obtained in step S20 is adjusted for particle size using an air classifier. The fan frequency f of the classifier is 50Hz, resulting in the final silicon-based anode material. The sorting coefficient B of the silicon-based anode material particle size distribution is 1.31, the peak coefficient A is 0.99, and B / A = 1.33.

[0274] Effect Analysis

[0275] The silicon-based anode materials obtained in the above embodiments and comparative examples were subjected to the following performance tests:

[0276] (1) Particle size distribution test: The particle size distribution of the material was tested using a Malvern 2000 particle size analyzer, with the refractive index set to 2.42, the opacity to be 8%-20%, and the dispersant to be water;

[0277] (2) Initial capacity efficiency test: a. Preparation of lithium-ion battery: The prepared silicon-based negative electrode material: conductive carbon black: CMC / SBR = 75:15:10 was coated on copper foil to prepare a negative electrode sheet, lithium metal sheet as counter electrode, PP / PE as separator, and button battery was made; b. The electrochemical performance of the battery was tested using a Blue Electric 5V / 10mA battery tester, with a voltage of 1.5V and a current of 0.1C. Initial efficiency = initial charge specific capacity / initial discharge specific capacity.

[0278] (3) Cyclic performance test: a. Preparation of lithium-ion battery: The prepared silicon-based negative electrode material was mixed with graphite in a ratio of 15:85 to obtain active material. The active material was coated on copper foil in a ratio of active material: conductive carbon black: CMC: SBR = 92:4:2:2 to prepare a negative electrode sheet. The lithium metal sheet was used as the counter electrode and PP / PE was used as the separator to make a button battery; b. The electrochemical performance of the battery was tested using a Blue Electric 5V / 10mA battery tester. The voltage was 1.5V and the current was 0.1C. The 50-cycle retention rate = the specific capacity of the 50th discharge / the specific capacity of the first discharge.

[0279] (4) Expansion performance test: a. Preparation of lithium-ion battery: The prepared silicon-based negative electrode material was mixed with graphite in a ratio of 15:85 to obtain active material. The active material was coated on copper foil in a ratio of active material: conductive carbon black: CMC: SBR = 92:4:2:2 to prepare a negative electrode sheet. The thickness of the negative electrode sheet was measured with a micrometer and recorded as L1. A lithium metal sheet was used as the counter electrode, and PP / PE was used as the separator to make a button battery; b. The electrochemical performance of the battery was tested using a Blue Electric or Xinwei 5V / 10mA battery tester. The voltage was 1.5V and the current was 0.1C. After 50 cycles, the battery was disassembled, and the thickness of the negative electrode sheet was measured with a micrometer and recorded as L2. The electrode sheet expansion rate after 50 cycles = (L2 - copper foil thickness) / (L1 - copper foil thickness) * 100%.

[0280] (5) Battery consistency test: Ten identical batteries were prepared according to methods (2) and (3), and the consistency of the 50-week capacity retention rate and 50-week electrode expansion rate of the ten batteries was compared. The consistency was represented by the relative standard deviation (RSD) of the 50-week capacity retention rate and 50-week electrode expansion rate of the ten groups.

[0281] (6) Scanning electron microscopy test: The material was tested using an S4800 scanning electron microscope to observe the microscopic particle state.

[0282] (7) Wadell sphericity test: The particle size distribution is measured using a laser particle size analyzer to obtain the equivalent volume diameter within each particle size range. This equivalent volume diameter is used as the particle size of all spheres within the minimum particle size distribution range, and all particles within this range are considered as ideal spheres. The specific surface area within each particle size distribution range is calculated. Then, the specific surface area of ​​a sphere with the same volume as all particles is obtained by weighting using the volume ratio %. Thus, the sphericity of the plasma-prepared spherical particles is calculated as: Surface area of ​​a sphere with the same volume as the particle / Specific surface area of ​​the particles measured by the specific surface area analyzer.

[0283] (8) Ratio and peel strength test:

[0284] a. Preparation of lithium-ion batteries: The composite materials prepared in the above examples and comparative examples were mixed with graphite at a mass ratio of 15:85 to obtain negative electrode active materials. Then, the negative electrode active materials, conductive carbon black, CMC and SBR were mixed evenly at a mass ratio of 92:4:2:2 and coated on copper foil to prepare a negative electrode sheet. The peel strength of the negative electrode sheet was tested using the cross-cut test.

[0285] b. Take another negative electrode, use a lithium metal sheet as the positive electrode, and PP / PE as the separator to make a button cell.

[0286] c. The battery was tested using a Landon Newway 5V / 10mA battery tester. The voltage was 1.5V and the currents were 0.1C and 3C respectively. 3C / 0.1C = discharge capacity at 3C current / discharge capacity at 0.1C current.

[0287] The battery testing and experimental data are shown in Table 1 below. The particle size distribution results of Example 1 and Comparative Example 1 are shown in Table 1 below. Figure 2 and Figure 3 As shown, the scanning electron microscope results of Example 1 and Comparative Example 1 are as follows: Figure 4 and Figure 5 As shown.

[0288] Table 1 Comparison of experimental data from the examples and comparative examples.

[0289]

[0290]

[0291] Table 2. Particle size distribution of silicon-based anode materials in the examples and comparative examples.

[0292]

[0293]

[0294] like Figure 2-5 The results show that by adjusting the particle size of the active material coated with a carbon layer and by rationally selecting the particle size sorting coefficient B and peak coefficient A, a silicon-based anode material with a suitable particle size distribution can be obtained, ensuring the consistency of the silicon-based anode material particles. As shown in Table 1 above, the lithium-ion battery prepared using the silicon-based anode material of this application exhibits excellent capacity efficiency, cycle performance, charge-discharge performance, and expansion performance, as well as high peel strength, effectively improving the performance of the lithium-ion battery.

[0295] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A silicon-based anode material, characterized in that, The peak value coefficient A of the particle size distribution of the silicon-based anode material satisfies: 0 < A ≤ 3; where, A = (D 95 -D5) / [2.5 (D) 75 -D 25 )],D 95 D5, D 75 D 25 These represent the particle sizes of the silicon-based anode material when the volume percentage content reaches 95%, 5%, 75%, and 25% on the cumulative curves, respectively, where 0 < D5 ≤ 65 μm, 0 < D 25 ≤69μm, 0<D 75 ≤75μm, 0<D 95 ≤79μm; The sorting coefficient B of the particle size distribution of the negative electrode material satisfies: 0 < B ≤ 3, where B = (D 84 -D 16 ) / 4+(D 95 -D5) / 6.6, D 84 D 16 D 95 D5 represents the particle size of the negative electrode material when the volume percentage content reaches 84%, 16%, 95%, and 5% on the cumulative curve, respectively, where 0 < D 16 ≤67μm, 0<D 84 ≤77μm; The sorting coefficient B and the peak coefficient A of the particle size distribution of the negative electrode material satisfy: 0 < B / A ≤ 5; The silicon-based anode material includes an active material, which includes SiO2. x SiO x / C、SiO x At least one of / M, Si, Si / C and Si / M, wherein 0 < x ≤ 2, and M includes at least one of metal, nonmetal, metal oxide and nonmetal oxide.

2. The silicon-based anode material according to claim 1, characterized in that, The silicon-based anode material includes at least one of the following features (1)-(8): (1) The infrared spectrum of the silicon-based anode material was measured at a wavenumber of 3200 cm⁻¹. -1 -3600cm -1 There is a peak within the range; (2) The Wadell sphericity of the silicon-based anode material is ≥0.6; (3) The particle size D50 of the active material is greater than 0 μm and less than or equal to 80 μm; (4) The specific surface area of ​​the active material is 0-10 m². 2 / g, and not 0; (5) The tap density of the active material is 0.5 g / cm³. 3 ~2g / cm 3 ; (6) The silicon-based anode material further includes doped materials doped into the active material; (7) The silicon-based anode material further includes a dopant material doped in the active material, wherein the dopant material includes at least one of alkali metal, alkaline earth metal, alkali metal oxide and alkaline earth metal oxide; (8) The silicon-based anode material further includes a dopant material doped in the active material, and the weight percentage b of the dopant material in the silicon-based anode material satisfies: 0 < b ≤ 20%.

3. The silicon-based anode material according to claim 1, characterized in that, The silicon-based anode material further includes a coating layer located on the surface of the active material, the coating layer comprising at least one of a flexible polymer and a conductive material.

4. The silicon-based anode material according to claim 3, characterized in that, The silicon-based anode material further includes at least one of the following features (1)-(9): (1) The conductive material includes flake graphite and nano-carbon materials, wherein the flake graphite includes natural flake graphite and / or artificial flake graphite, and the nano-carbon materials include at least one of conductive graphite, graphene, carbon nanotubes and carbon nanofibers. (2) The flexible polymer includes natural flexible polymers and / or synthetic flexible polymers; (3) The weight-average molecular weight of the flexible polymer is 2,000-1,000,000; (4) The flexible polymer contains thermally cross-linked functional groups, including at least one of epoxy, carboxyl, hydroxyl, amino, double bond and triple bond; (5) The mass percentage of the flexible polymer is 0-10% based on the total mass of the silicon-based anode material as 100%, and does not include 0; (6) The conductive material includes flake graphite and nano-carbon materials. Based on the total mass of the silicon-based anode material as 100%, the mass percentage of the flake graphite is 0-20%, and does not include 0. (7) The conductive material includes flake graphite and nano-carbon materials. Based on the total mass of the silicon-based anode material as 100%, the mass percentage of the nano-carbon materials is 0-5%, and does not include 0. (8) The thickness of the coating layer is 10 nm to 5000 nm; (9) The coating layer accounts for 0-20% of the mass of the silicon-based anode material, and does not include 0.

5. The silicon-based anode material according to claim 3, characterized in that, The flexible polymer includes at least one of polyolefins and their derivatives, polyvinyl alcohol and its derivatives, polyacrylic acid and its derivatives, polyamide and its derivatives, carboxymethyl cellulose and its derivatives, alginate and its derivatives, and polycarbonate and its derivatives.

6. The silicon-based anode material according to claim 3, characterized in that, The coating layer accounts for 2% to 10% of the mass of the silicon-based anode material.

7. A method for preparing the silicon-based anode material according to any one of claims 1 to 6, characterized in that, Includes the following steps: Preparation of powdered silicon-based anode materials; The particle size of the prepared powdered silicon-based anode material was adjusted to obtain a silicon-based anode material.

8. The preparation method according to claim 7, characterized in that, The method for preparing powdered silicon-based anode material includes: pulverizing an active material to obtain the powdered silicon-based anode material.

9. The preparation method according to claim 8, characterized in that, The preparation method shall satisfy at least one of the following features (1) to (3): (1) The powdering method includes crushing and ball milling. The crushing device includes a crusher, and the crushing power p of the crusher satisfies: 0 < p ≤ 300 kW. The ball milling device includes a ball mill, and the rotational speed v1 of the ball mill satisfies: 0 < v1 ≤ 1500 rpm. (2) The device used for particle size adjustment includes a classifier; the frequency f of the induced draft fan of the classifier satisfies: 0 < f ≤ 100 Hz; (3) The particle size D50 of the active material is greater than 0 μm and less than or equal to 80 μm.

10. The preparation method according to claim 9, characterized in that, The method for preparing powdered silicon-based anode material further includes: coating the powdered active material with carbon material to obtain the powdered silicon-based anode material; wherein the weight percentage 'a' of the carbon material in the silicon-based anode material satisfies: 0 < a ≤ 15%.

11. The preparation method according to claim 9 or 10, characterized in that, The method for preparing powdered silicon-based anode material further includes: polymer coating the powdered active material or carbon coating the powdered active material with carbon material, and then obtaining the powdered silicon-based anode material.

12. The preparation method according to claim 11, characterized in that, The polymer coating method includes the following steps: The flexible polymer is dissolved in a solvent to obtain a flexible polymer solution; Under stirring conditions, a conductive material comprising flake graphite and nano-carbon materials is added to the flexible polymer solution to obtain a mixed coating solution. Add an antisolvent to the mixed coating solution and stir to obtain a supersaturated mixed coating solution; Under stirring conditions, a silicon-based active material is added to the supersaturated mixed coating solution, stirred, and separated to obtain the negative electrode material precursor; and The precursor of the anode material is subjected to heat treatment to obtain the powdered silicon-based anode material.

13. The preparation method according to claim 12, characterized in that, The preparation method includes at least one of the following features (1) to (5): (1) The flexible polymer contains thermally crosslinked functional groups, which include at least one of epoxy, carboxyl, hydroxyl, amino, double bond and triple bond; (2) 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; (3) The antisolvent includes unsuitable solvents for flexible polymers; (4) The temperature of the heat treatment is 100℃-400℃; (5) The heat treatment time is 2h-12h.

14. The preparation method according to claim 12, characterized in that, The antisolvent 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.

15. The preparation method according to claim 9, characterized in that, The method for preparing powdered silicon-based anode material further includes: doping the powdered active material with a doping material to obtain the powdered silicon-based anode material. The preparation method shall satisfy at least one of the following characteristics: (1) The doped material includes at least one of alkali metal, alkaline earth metal, alkali metal oxide and alkaline earth metal oxide; (2) The weight percentage b of the doped material in the silicon-based anode material satisfies: 0 < b ≤ 20%.

16. A lithium-ion battery, characterized in that, Includes the silicon-based anode material according to any one of claims 1-6 or the silicon-based anode material prepared by the preparation method according to any one of claims 7-15.

Images