Silicon-carbon negative electrode material, negative electrode sheet and preparation method and application thereof

Abstract

This invention provides a silicon-carbon anode material, anode sheet, its preparation method, and its applications, relating to the field of anode material technology. The silicon-carbon anode material of this invention includes a conductive agent, a binder, and a silicon-carbon anode active material. The Dv50 of the silicon-carbon anode active material is 3-5 μm, the micropore ratio A in the carbon matrix of the silicon-carbon anode active material is 90-99%, and the particle concentration Y of the silicon-carbon anode active material is ≥1.5. This invention, from the perspective of optimizing the particle size of the silicon-carbon anode material, improves fast charging time and cycle life through special settings of the micropore ratio of the carbon matrix and the particle parameters of the silicon-carbon anode material. It solves the current problems of fast charging and cycle life under high silicon content and can be widely used in the preparation of anode sheets, cells, battery modules, battery packs, and electrical devices.

Description

Technical Field

[0001] This invention relates to the field of anode material technology, and in particular to a silicon-carbon anode material, anode sheet, its preparation method and application. Background Technology

[0002] The market demand for battery cell energy density is further increasing, and the anode material is one of the key factors in improving battery cell energy density. CVD (Chemical Vapor Deposition) silicon-carbon is widely used to improve battery cell energy density due to its high specific capacity. However, because CVD silicon-carbon has a relatively low initial efficiency (84%@0.8V), when a high amount of graphite is added, it will lead to a significant deterioration in fast charging capability and lifespan.

[0003] Existing technology CN119786577A discloses a silicon-carbon-graphite anode active material, an anode material, and its applications, aiming to improve the long-cycle performance and fast-charging performance of the anode material. The silicon-carbon-graphite anode active material comprises spherical silicon-carbon material and fast-charging artificial graphite, wherein the D50 particle size of the spherical silicon-carbon material is 9–10 μm. The technical solution mainly uses a special morphology—spherical silicon-carbon material—and fast-charging artificial graphite to form the silicon-carbon-graphite anode active material. However, this still suffers from the aforementioned compounding problem and does not fundamentally improve the supercharging performance and long-cycle performance of the CVD silicon-carbon anode material itself. Summary of the Invention

[0004] This invention addresses the shortcomings and deficiencies of current CVD silicon-carbon anode materials in terms of fast charging and lifespan performance by providing a silicon-carbon anode material that improves fast charging capability and cycle performance through specific size and structure control.

[0005] Another object of the present invention is to provide a negative electrode sheet.

[0006] Another object of the present invention is to provide a battery cell.

[0007] Another object of the present invention is to provide a battery module.

[0008] Another object of the present invention is to provide a battery pack.

[0009] Another object of the present invention is to provide an electrical device.

[0010] In a first aspect, the present invention protects a silicon-carbon anode material, comprising a conductive agent and a binder, and further comprising a silicon-carbon anode active material, wherein the Dv50 of the silicon-carbon anode active material is 3~5μm, the micropore ratio A in the carbon matrix of the silicon-carbon anode active material is 90~99%, and the particle concentration Y of the silicon-carbon anode active material is ≥1.5.

[0011] According to the silicon-carbon anode material protected by the present invention, preferably, the Dv50 of the silicon-carbon anode active material and the micropore ratio A in the carbon matrix of the silicon-carbon anode active material satisfy the following relationship: Z = -(Dv50 - 4). 2 - (100A-93) 2 +32, Z≥27.

[0012] In the silicon-carbon anode material protected by the present invention, preferably, Z is 28~32.

[0013] According to the silicon-carbon anode material protected by the present invention, preferably, the micropore ratio A in the carbon matrix of the silicon-carbon anode active material is 93-97%.

[0014] According to the silicon-carbon anode material protected by the present invention, preferably, the particle concentration Y of the silicon-carbon anode active material is 1.5 to 2.0.

[0015] According to the silicon-carbon anode material protected by the present invention, preferably, the silicon-carbon anode active material satisfies at least one of the following characteristics: (1) The silicon content of the silicon-carbon anode active material is 42~52 wt%; (2) The silicon-carbon anode active material is spherical, hemispherical or blocky; (3) The carbon coating thickness of the silicon-carbon anode active material is 1~10 nm; (4) The compaction density of the silicon-carbon anode active material is 1.35~1.70 g / cm³. 3 .

[0016] Secondly, the present invention also specifically protects a negative electrode sheet, including a negative electrode current collector and a negative electrode material layer at least partially covering the surface of the negative electrode current collector, wherein the negative electrode material layer contains the silicon-carbon negative electrode material.

[0017] According to the negative electrode sheet protected by the present invention, preferably, the areal density of the negative electrode material layer in the negative electrode sheet is 80~160 mg / cm³. 2 The compacted density is 1.35~1.7 mg / cm³. 3 .

[0018] According to the negative electrode sheet protected by the present invention, preferably, the areal density of the negative electrode material layer in the negative electrode sheet is 110~140 mg / cm³. 2 The compacted density is 1.4~1.5 g / cm³. 3 .

[0019] Thirdly, the present invention also specifically protects a method for preparing a negative electrode sheet, comprising the following steps: The silicon-carbon anode material is added to the anode solvent and stirred and soaked at a speed of 15-35 rpm / min for 0.5-1.5 h. Then, the anode solvent is added and dispersed at a speed of 1500-2500 rpm / min to obtain the anode slurry.

[0020] Fourthly, the present invention also specifically protects a battery cell, including the positive electrode plate.

[0021] Fifthly, the present invention also specifically protects a battery module, including the negative electrode sheet or the battery cell.

[0022] Sixthly, the present invention also specifically protects a battery pack, including the negative electrode sheet, the battery cell, or the battery module.

[0023] Seventhly, the present invention also specifically protects an electrical device, wherein the electrical device includes the negative electrode sheet, the battery cell, the battery module, or the battery pack.

[0024] According to the electrical appliance protected by the present invention, preferably, the electrical appliance includes a vehicle.

[0025] Beneficial effects: This invention provides a silicon-carbon anode material. The silicon-carbon anode active material in the anode material has a Dv50 of 3~5μm, the micropore ratio A in the carbon matrix is ​​90~99%, and the particle concentration Y≥1.5. The synergistic control of Dv50 value and particle concentration can result in a short diffusion distance of lithium ions from the interface to the bulk phase, low charge transfer impedance, low polarization under high current, and excellent fast charging performance. At the same time, it can effectively buffer the volume expansion during lithium intercalation and improve cycle life. Combined with the limitation of the micropore ratio A, the silicon grain size is further reduced, the expansion is reduced, and the cycle life is improved, achieving a comprehensive improvement in fast charging capability and cycle life. Under a high-rate charging of about 6C, the capacity retention rate can reach 80% after 1700~2200 basic cycles.

[0026] The silicon-carbon anode material of the present invention improves fast charging time and cycle life from the perspective of optimizing the particle size of silicon-carbon anode material. By specially setting the micropore ratio of carbon matrix and the particle parameters of silicon-carbon anode material, it solves the problems of fast charging and cycle life under high silicon content. It can be widely used in the preparation of anode sheets, cells, battery modules, battery packs and electrical devices. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 This is a scanning electron microscope (SEM) image of the silicon-carbon anode active material of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0030] In a specific embodiment, the present invention provides a silicon-carbon anode material, including a silicon-carbon anode active material, wherein the Dv50 of the silicon-carbon anode active material is 3~5μm, the micropore ratio A in the carbon matrix of the silicon-carbon anode active material is 90~99%, and the particle concentration Y of the silicon-carbon anode active material is ≥1.5.

[0031] It should be noted that: The Dv50 mentioned in this invention refers to the particle size when the cumulative volume distribution of particles reaches 50%.

[0032] Dv10 is the particle size corresponding to a cumulative volume distribution of 10%.

[0033] Dv90 is the particle size corresponding to a cumulative volume distribution of 90%.

[0034] Silicon-carbon anode material is a black powder material composed of a carbon matrix and nano-silicon. The nano-silicon is dispersed in the carbon matrix, and the pore size of the micropores in the carbon matrix is ​​less than 2 nm.

[0035] The particle concentration Y of the present invention is (Dv90-Dv10) / Dv50.

[0036] The high silicon content in silicon-carbon anode materials significantly increases the energy density of battery cells. However, due to the expansion of silicon itself, the SEI (Solid Electrolyte Interphase) film can break down and reassemble during cycling, continuously consuming active lithium and leading to cycle degradation. Furthermore, the high silicon capacity restricts lithium-ion diffusion channels, resulting in poor fast-charging performance. To improve cycle performance with high silicon content, this invention enhances fast-charging performance by reducing the Dv50 of the silicon-carbon anode active material and increasing particle density, and improves cycle performance by increasing the proportion of micropores.

[0037] This invention controls the Dv50 value of the silicon-carbon anode active material to shorten the diffusion distance of lithium ions from the interface to the bulk phase, reduce charge transfer resistance, lower polarization under high current, and improve fast-charging performance. Simultaneously, particle size concentration can influence stress distribution, buffering volume expansion during lithium intercalation and improving cycle life. A higher micropore ratio (A) can reduce silicon grain size, decrease expansion, and improve cycle life; however, an excessively high micropore ratio (A) increases the diffusion resistance of lithium ions in the bulk phase, degrading fast-charging performance.

[0038] In some specific embodiments, in order to further enhance the synergistic effect of the particle structure parameters of the above-mentioned silicon-carbon anode material and achieve better fast charging and cycle performance, the Dv50 of the silicon-carbon anode active material and the micropore ratio A in the carbon matrix of the silicon-carbon anode active material mentioned in this invention satisfy the following relationship: Z = -(Dv50 - 4). 2 - (100A-93) 2 +32, Z≥27.

[0039] In some specific embodiments, Z mentioned in this invention can be a point value such as 16, 18, 20, 27, 28, 30, 32 or any range of values, preferably Z is 28~32.

[0040] In some specific embodiments, in order to achieve a better balance and improvement in fast charging cycle performance, the micropore ratio A in the carbon matrix of the silicon-carbon anode active material mentioned in this invention is 93~97%, for example, it can be a point value of 93%, 94%, 95%, 96%, 97% or any range of values.

[0041] In some specific embodiments, in order to further optimize cycle performance and processing performance, the particle concentration Y of the silicon-carbon anode active material mentioned in this invention is 1.5~2.0, for example, it can be a point value of 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 or any range of values.

[0042] In some specific exemplary embodiments, in order to have better fast charging and cycle performance, the silicon-carbon anode material mentioned in this invention preferably has any one of the following characteristics: (1) The silicon content of the silicon-carbon anode active material is 42~52wt%, for example, it can be 42wt%, 45wt%, 48wt%, 50wt%, 52wt% or any range of values; (2) The silicon-carbon anode active material is spherical, hemispherical or blocky; (3) The carbon coating thickness of the silicon-carbon anode active material is 1~10nm, for example, it can be a point value of 1nm, 3nm, 5nm, 7nm, 10nm or any range of values. (4) The compaction density of the silicon-carbon anode active material is 1.35~1.70 g / cm³. 3 .

[0043] The silicon content of silicon-carbon anode active materials affects particle expansion. A certain range of high silicon content can further improve the interface coating performance, which is more conducive to preventing electrolyte penetration and optimizing cycle performance.

[0044] In some specific exemplary embodiments, the above-mentioned features of the silicon-carbon anode material mentioned in this invention can be controlled individually or in combination according to actual improvement needs.

[0045] In specific embodiments, the silicon-carbon anode material mentioned in this invention can be prepared using conventional CVD (Chemical Vapor Deposition) methods, as detailed below: A carbon matrix with a micropore content of 90-99% is placed in a fluidized bed apparatus and deposited with silane gas at 450-600℃ for 6-48 hours. After carbon coating treatment for 6-24 hours, silicon-carbon anode material is obtained.

[0046] In some specific embodiments, the silicon-carbon anode material mentioned in this invention may also contain graphite, conductive agent and binder.

[0047] The proportion of silicon-carbon anode active material in silicon-carbon anode materials is 10~20wt%.

[0048] The conductive agent mentioned in this invention can be a conventional conductive agent in the art, preferably a single-walled carbon nanotube, with a content of 0.02~2wt% (based on the total amount of silicon-carbon anode material).

[0049] The binder mentioned in this invention can be a conventional binder in the art, preferably polyacrylic acid, with a content of 1.5~5wt% (based on the total amount of silicon-carbon anode material).

[0050] In a specific embodiment, the present invention also provides a negative electrode sheet, the negative electrode sheet comprising a negative electrode current collector and a negative electrode material layer covering the surface of the negative electrode current collector, the negative electrode material layer being composed of the silicon-carbon negative electrode material.

[0051] In some specific embodiments, in order to comprehensively improve the energy density and fast charging performance of the negative electrode sheet, the areal density of the negative electrode material layer in the negative electrode sheet provided by the present invention is 80~160 mg / cm³. 2 For example, it can be 80mg / cm³ 2 100 mg / cm 2 120 mg / cm 2 140 mg / cm 2 160 mg / cm 2 Equal point values ​​or arbitrarily formed range values; compacted density of 1.35~1.7 g / cm³. 3 For example, it can be 1.4 g / cm³ 3 1.5 g / cm 3 1.6 g / cm 3 1.7 g / cm 3 Equal point values ​​or arbitrarily formed range values. More preferably, the areal density of the negative electrode material layer in the negative electrode sheet is 110~140 mg / cm³. 2 The compacted density is 1.4~1.5 g / cm³. 3 .

[0052] In a specific embodiment, the present invention also provides a method for preparing a negative electrode sheet, comprising the following steps: The silicon-carbon anode material is added to the anode solvent and stirred and soaked at a speed of 15-35 rpm / min for 0.5-1.5 h. Then, the anode solvent is added and dispersed at a speed of 1500-2500 rpm / min to obtain the anode slurry.

[0053] In the preparation method mentioned in this invention, thorough stirring and wetting can ensure that the solvent fully coats the particle surface, eliminates air and agglomeration between particles, and subsequent high-speed stirring can form a more uniform and stable negative electrode slurry, which is more conducive to forming a uniform and stable negative electrode material layer on the surface of the electrode current collector.

[0054] The negative electrode slurry is coated onto the negative electrode current collector, and then rolled and dried to obtain the negative electrode sheet.

[0055] In some specific exemplary embodiments, the negative electrode solvent mentioned in this invention can be a conventional negative electrode solvent, such as N-methylpyrrolidone, ethanol, isopropanol, etc. Preferably, the mass ratio of silicon-carbon negative electrode material in the negative electrode slurry is 10~20%, for example 15%.

[0056] In a specific embodiment, the present invention also provides a battery cell, including the negative electrode sheet provided by the present invention.

[0057] The battery cell mentioned in this invention includes a positive electrode, a negative electrode, a separator, and an electrolyte.

[0058] The preparation method for the positive electrode sheet can refer to the conventional positive electrode sheet preparation method, for example as follows: The positive electrode includes a positive current collector and a positive electrode material. The positive current collector is aluminum foil (12μm), and the positive electrode material includes the following components by weight: positive electrode active material LiNi 0.5 Co 0.3 Mn 0.2 97.6 parts of O2, 1.4 parts of conductive carbon black as positive electrode conductive agent, 1 part of polyvinylidene fluoride as positive electrode binder, and 24 parts of N-methyl-2-pyrrolidone as positive electrode solvent.

[0059] The diaphragm is a polypropylene diaphragm. The electrolyte is a 1 mol / L LiPF6 solution, in which the solvent is a mixed solvent of ethylene carbonate, dimethyl carbonate, and diethyl carbonate (3:4~5:2~3), and the additives are fluoroethylene carbonate and vinylene carbonate (mass ratio of 0.3:0.3:0.3:0.07:0.03).

[0060] In some specific embodiments, the battery cell mentioned in this invention can be prepared by referring to the following method: (1) Preparation of positive electrode sheet: The above-mentioned positive active material, positive conductive agent, positive binder and positive solvent are mixed in the formula amount to obtain positive slurry, which is then coated, dried, rolled and cut to obtain positive electrode sheet.

[0061] (2) Assembly: Assemble the positive electrode, separator, negative electrode, copper wire and electrolyte into a battery cell. After the battery cell is assembled, let it stand for 10~12 hours.

[0062] In a specific embodiment, the present invention also provides a battery module, including the negative electrode sheet or the battery cell.

[0063] A battery module is an "intermediate integrated unit" that combines multiple battery cells in series or parallel and is equipped with structural components, electrical connectors, and temperature control components to meet the voltage and capacity requirements of practical applications.

[0064] In a specific embodiment, the present invention also provides a battery pack, including the negative electrode sheet, the battery cell, or the battery module.

[0065] A battery pack is a complete energy storage system that integrates multiple battery modules, a battery management system, a cooling system, a high-voltage power distribution system, etc. into a casing, forming a system that can be directly installed in a vehicle or used to supply power.

[0066] In a specific embodiment, the present invention also provides an electrical device, including the negative electrode sheet, the battery cell, the battery module, or the battery pack.

[0067] The electrical device referred to in this invention is any device or system that uses the above-mentioned positive electrode sheet, the battery cell, the battery module, or the battery pack, including vehicles.

[0068] Examples 1-9 A silicon-carbon anode material includes a conductive agent (single-walled carbon nanotubes), a binder (polyacrylic acid), graphite, and a silicon-carbon anode active material (0.1%:4.9%:80%:15%). The Dv50 of the silicon-carbon anode active material, the micropore ratio A in the carbon matrix, and the particle concentration Y value (Y = (Dv90 - Dv10) / Dv50) satisfy the following relationship: Z = -(Dv50 - 4). 2 - (100A-93) 2 +32, see Table 1 for details.

[0069] In Examples 1-9, the silicon content of the silicon-carbon anode active material is 47 wt%, and the silicon-carbon anode active material is in block form (e.g., ...). Figure 1 As shown), the carbon coating thickness is 3 nm, and the compaction density is 1.4 g / cm³. 3 It can be prepared by depositing silane gas onto a carbon matrix in a fluidized bed.

[0070] Table 1. Parameters of silicon-carbon anode materials in each embodiment Serial Number D50 / um A / % Y Z Example 1 4 90 1.5 23 Example 2 4 95 1.5 28 Example 3 4 99 1.5 -4 Example 4 4 93 1.5 32 Example 5 4 97 1.5 16 Example 6 3 95 1.5 27 Example 7 5 95 1.5 27 Example 8 4 95 2 28 Example 9 4 95 1.75 28 Example 10 A negative electrode sheet includes a negative electrode current collector and a negative electrode material layer covering the surface of the negative electrode current collector. The negative electrode material layer is composed of the silicon-carbon negative electrode material described in Examples 1-9 above. The areal density of the negative electrode material layer in the negative electrode sheet is 130 mg / cm³. 2 The compacted density is 1.4 g / cm³. 3 .

[0071] This embodiment also specifically provides a method for preparing a negative electrode sheet, including the following steps: The silicon-carbon anode material was added to the anode solvent and stirred and soaked at 25 rpm / min for 1 hour. Then, the anode solvent was added and dispersed at 2500 rpm / min to obtain the anode slurry. The negative electrode slurry is coated onto the negative electrode current collector, then rolled and dried to obtain the negative electrode sheet.

[0072] Example 11 A negative electrode sheet includes a negative electrode current collector and a negative electrode material layer covering the surface of the negative electrode current collector. The negative electrode material layer is composed of the silicon-carbon negative electrode material of Example 2 above, and the areal density of the negative electrode material layer in the negative electrode sheet is 160 mg / cm³. 2 The compacted density is 1.8 g / cm³. 3 .

[0073] Example 12 This embodiment provides a battery cell, including the negative electrode sheet provided in embodiments 10 and 11. The battery cell includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte.

[0074] The preparation method for the positive electrode sheet can refer to the conventional positive electrode sheet preparation method, for example as follows: The positive electrode includes a positive current collector and a positive electrode material. The positive current collector is aluminum foil (12μm), and the positive electrode material includes the following components by weight: positive electrode active material LiNi 0.5 Co 0.3 Mn 0.2 97.6 parts of O2, 1.4 parts of conductive carbon black as positive electrode conductive agent, 1 part of polyvinylidene fluoride as positive electrode binder, and 24 parts of N-methyl-2-pyrrolidone as positive electrode solvent.

[0075] The diaphragm is a polypropylene diaphragm. The electrolyte is a 1 mol / L LiPF6 solution, in which the solvent is a mixed solvent of ethylene carbonate, dimethyl carbonate, and diethyl carbonate (3:4:3), and the additives are fluoroethylene carbonate and vinylene carbonate (mass ratio 0.3:0.3:0.3:0.07:0.03).

[0076] In some specific embodiments, the battery cell mentioned in this invention can be prepared by referring to the following method: (1) Preparation of positive electrode sheet: The above-mentioned positive active material, positive conductive agent, positive binder and positive solvent are mixed in the formula amount to obtain positive slurry, which is then coated, dried, rolled and cut to obtain positive electrode sheet.

[0077] (2) Assembly: Assemble the positive electrode, separator, negative electrode, copper wire and electrolyte into a battery cell. After the battery cell is assembled, let it stand for 12 hours.

[0078] Comparative Examples 1-4 A silicon-carbon anode material, comprising a conductive agent (single-walled carbon nanotubes), a binder (polyacrylic acid), graphite, and a silicon-carbon anode active material (0.1%:4.9%:80%:15%), wherein the Dv50 of the silicon-carbon anode active material, the micropore ratio A in the carbon matrix, and the particle concentration Y value (Y=(Dv90-Dv10) / Dv50) satisfy the following relationship: Z=-(Dv50-4).2 - (100A-93) 2 +32, see Table 2 for details. Everything else is the same as in Example 1.

[0079] Table 2. Parameters of silicon-carbon anode materials for each comparative example Serial Number D50 / um A / % Y Z Comparative Example 1 7.5 95 1.5 15.75 Comparative Example 2 4 95 1 28 Comparative Example 3 4 85 1.5 -32 Comparative Example 4 2 95 1.5 24 The negative electrode sheet and battery cell were prepared using the same method as in Examples 10 and 12. Result detection The cells prepared in the above embodiments and comparative examples were subjected to cycle tests at room temperature according to 4C charging and 1C discharging, and the cycle data showed a capacity retention rate of 80%.

[0080] The test was conducted using a three-electrode testing system. With the negative parameter electrode at 0V as the cutoff potential, the charging was performed at 0.33C, 1C, 2C, and 3C. The charging rate data corresponding to 50% SOC was fitted to obtain the charging rate at each SOC state. The higher the charging rate value, the more capacity can be charged per unit time, and the stronger the fast charging capability.

[0081] The specific test results are shown in Table 3.

[0082] Table 3. Test Results Serial Number Cyclic capability / cls Fast charging capability / C Example 1 1720 6.1 Example 2 2135 6.0 Example 3 2206 4.5 Example 4 2128 6.3 Example 5 2145 5.2 Example 6 2085 6.5 Example 7 2210 5.8 Example 8 2147 5.9 Example 9 2140 5.95 Example 11 1657 4.1 Comparative Example 1 2215 4.0 Comparative Example 2 1823 6.2 Comparative Example 3 1323 5.9 Comparative Example 4 1274 7.2 As can be seen from the data in Table 3, the battery cell prepared by the silicon-carbon anode material of the present invention not only improves the high-rate fast charging capability, but also significantly improves its cycle stability performance, achieving the best comprehensive improvement effect in cycle performance and fast charging capability. According to the test, the capacity retention rate of the embodiment of the present invention can reach 80% after 1700 to 2200 basic cycles under a high-rate charging of about 6C.

[0083] In Example 11, the areal density of the negative electrode material layer is 160 mg / cm³. 2 The compacted density is 1.8 g / cm³. 3 While it helps to increase energy density, the overall improvement in cycle performance and fast charging capability is not good, and it cannot achieve the effect of other embodiments.

[0084] However, the Dv50 of the silicon-carbon anode active material in Comparative Example 1 is too large and is not within the scope of protection of this invention. Although it can achieve a certain cycle performance, its fast charging energy is significantly degraded.

[0085] The particle concentration Y value of the silicon-carbon anode material in Comparative Example 2 is 1, which is relatively high and greatly increases the processing difficulty in production, making it difficult to industrialize. It also has a certain impact on cycle performance. Overall, it cannot achieve the comprehensive improvement effect of cycle performance and fast charging capability of Example 2.

[0086] The silicon-carbon anode material in Comparative Example 3 has too low a micropore ratio, resulting in a significant deterioration in the cycle life of the battery cell it prepared. Similarly, the silicon-carbon anode material in Comparative Example 4 has too low a Dv50, resulting in a significant deterioration in the cycle life of the battery cell it prepared. Neither of these materials can achieve the comprehensive improvement effect of cycle performance and fast charging capability of the present invention.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A silicon-carbon anode material, characterized in that, The active material includes a silicon-carbon anode material, wherein the Dv50 of the active material is 3~5μm, the micropore ratio A in the carbon matrix of the active material is 90~99%, and the particle concentration Y of the active material is ≥1.

5.

2. The silicon-carbon anode material according to claim 1, characterized in that, The Dv50 of the silicon-carbon anode active material and the micropore ratio A in the carbon matrix of the silicon-carbon anode active material satisfy the following relationship: Z = -(Dv50 - 4). 2 -(100A-93) 2 +32, Z≥27, preferably Z is 28~32.

3. The silicon-carbon anode material according to claim 1 or 2, characterized in that, The micropore ratio A in the carbon matrix of the silicon-carbon anode active material is 93-97%.

4. The silicon-carbon anode material according to any one of claims 1 to 3, characterized in that, The particle concentration Y of the silicon-carbon anode active material is 1.5~2.

0.

5. The silicon-carbon anode material according to any one of claims 1 to 4, characterized in that, The silicon-carbon anode active material must satisfy at least one of the following characteristics: (1) The silicon content of the silicon-carbon anode active material is 42~52 wt%; (2) The silicon-carbon anode active material is spherical, hemispherical or blocky; (3) The carbon coating thickness of the silicon-carbon anode active material is 1~10 nm; (4) The compaction density of the silicon-carbon anode active material is 1.35~1.70 g / cm³. 3 .

6. A negative electrode sheet, comprising a negative electrode current collector and a negative electrode material layer at least partially coated on the surface of the negative electrode current collector, characterized in that, The negative electrode material layer includes the silicon-carbon negative electrode material according to any one of claims 1 to 5.

7. The negative electrode sheet according to claim 6, characterized in that, The areal density of the negative electrode material layer in the negative electrode sheet is 80~160 mg / cm³. 2 The compacted density is 1.35~1.70 g / cm³. 3 ; The areal density of the negative electrode material layer in the preferred negative electrode sheet is 110~140 mg / cm³. 2 The compacted density is 1.4~1.5 g / cm³. 3 .

8. A method for preparing the negative electrode sheet according to claim 6 or 7, characterized in that, Includes the following steps: The silicon-carbon anode material is added to the anode solvent and stirred and soaked at a speed of 15-35 rpm / min for 0.5-1.5 h. Then, the anode solvent is added and dispersed at a speed of 1500-2500 rpm / min to obtain the anode slurry.

9. A battery cell, characterized in that, Includes the negative electrode sheet as described in claim 6 or 7.

10. A battery module, characterized in that, It includes the negative electrode sheet as described in claim 6 or 7 or the battery cell as described in claim 9.

11. A battery pack, characterized in that, It includes the negative electrode sheet as described in claim 6 or 7, the cell as described in claim 9, or the battery module as described in claim 10.

12. An electrical appliance, characterized in that, The electrical device includes the negative electrode sheet as described in claim 6 or 7, the battery cell as described in claim 9, the battery module as described in claim 10, or the battery pack as described in claim 11.

13. The electrical appliance according to claim 12, characterized in that, The electrical equipment includes vehicles.

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