Negative electrode material and battery

Abstract

A negative electrode material and a battery. The negative electrode material comprises a silicon-based material and a carbon material located on at least part of the surface of the silicon-based material. The negative electrode material has pores; the nitrogen adsorption specific surface area of all the pores in the negative electrode material is A1 m2 / g; the nitrogen adsorption specific surface area of the pores having a pore diameter of 2 nm or more is A2 m2 / g; and the negative electrode material satisfies: 1.5≤A1≤5.5, 1≤A2≤5, and 0.08:1≤(A1-A2) / A1≤0.6:1. The negative electrode material can have a high specific capacity, a high initial coulombic efficiency, and excellent cycle performance.

Description

Anode materials and batteries

[0001] This application claims priority to Chinese Patent Application No. 202411346793.2, filed with the Chinese Patent Office on September 25, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of negative electrode material technology, specifically to a negative electrode material and a battery. Background Technology

[0003] Electrified new energy vehicles represent the future development direction of the automotive market, and their core component is the lithium-ion battery. With market development, the demand for high-capacity batteries is increasing, and adopting novel high-specific-capacity positive and negative electrode materials is one of the important methods to improve battery energy density.

[0004] More and more new materials such as metals, oxides, and metal alloys are being used as active materials in anode materials to continuously explore various ways to improve battery energy density. Taking silicon-based anode materials as an example, silicon-based anode materials, as one of the aforementioned active materials, are widely considered to be the next generation of anode materials. They have an ultra-high theoretical specific capacity (4200 mAh / g) and a low delithiation potential (<0.5V). Replacing pure graphite anodes with silicon-based anode materials has become one of the effective ways to improve the specific capacity of anodes. However, the poor electronic conductivity of elemental silicon and the huge volume expansion during charge and discharge processes result in poor battery capacity and energy density, and low cycle life, hindering its commercial application.

[0005] Compared to elemental silicon, silicon suboxide exhibits significantly reduced volume expansion during lithium intercalation while maintaining a high theoretical specific capacity (>2000 mAh / g) and low manufacturing cost, making it a highly promising anode material. However, during lithium intercalation, silicon suboxide generates inactive products such as Li2O and Li4SiO4, causing some Li to lose its activity and resulting in low initial charge-discharge efficiency (<70%), which severely impacts its practical applications.

[0006] Therefore, it is of great significance to develop anode materials with high battery capacity and energy density, high initial charge-discharge efficiency, and high cycle life. Summary of the Invention

[0007] This application proposes an anode material and a battery, wherein the anode material can combine high specific capacity, high initial coulombic efficiency and excellent cycle performance.

[0008] In a first aspect, this application provides a negative electrode material, the negative electrode material comprising a silicon-based material and a carbon material located on at least a portion of the surface of the silicon-based material; the negative electrode material has pores, and the nitrogen adsorption specific surface area of ​​all pores in the negative electrode material is Al m. 2 / g, the nitrogen adsorption specific surface area of ​​pores with a pore size of 2nm or larger is A2 m 2 / g, the negative electrode material satisfies: 1.5≤A1≤5.5, 1≤A2≤5, and 0.08:1:1≤(A1-A2) / A1≤0.6:1.

[0009] In some embodiments, the total pore volume of the negative electrode material is 0.006 cm³. 3 / g~0.01cm 3 / g.

[0010] In some embodiments, the contact angle between the negative electrode material and the electrolyte with a lithium ion concentration of 1 mol / L is B1, and the contact angle between the negative electrode material and water is B2. The negative electrode material satisfies the following: 1:1 < B2 / B1 < 1.1:1. The electrolyte is formed by dissolving lithium hexafluorophosphate in an organic solvent, wherein the organic solvent is composed of ethyl methyl carbonate, ethylene carbonate, and dimethyl carbonate in a volume ratio of 1:1:1.

[0011] In some implementations, 145°≤B1≤155°; 150°≤B2≤160°.

[0012] In some implementations, 0.08:1 < [(A1-A2) / A1] / (B2 / B1) < 0.7:1.

[0013] In some embodiments, the silicon-based material includes at least one of amorphous silicon, crystalline silicon, and silicon oxide;

[0014] In some embodiments, the carbon material includes at least one of amorphous carbon, carbon nanoparticles, carbon nanotubes, and graphene;

[0015] In some embodiments, the silicon-based material includes silicon oxide, which includes silicon and oxygen elements, wherein the atomic ratio of silicon to oxygen is 0 to 2:1, excluding 0:1.

[0016] In some embodiments, the silicon-based material comprises silicon oxide, the silicon oxide having the general chemical formula SiO. x , where 0:1<x≤2:1.

[0017] In some embodiments, in the negative electrode material, micropores account for 6% to 9% of the total pore volume, and mesopores account for 80% to 90% of the total pore volume.

[0018] In some embodiments, the mass content of silicon in the negative electrode material is m. Si %, 53% ≤ m Si ≤64%;

[0019] In some embodiments, the mass content of oxygen in the negative electrode material is m. O %, 35% ≤ m O ≤37%;

[0020] In some embodiments, the mass content of carbon in the negative electrode material is m. C %, 1% ≤ m C ≤6%.

[0021] In some embodiments, the median particle size D of the negative electrode material 50 The size ranges from 1 μm to 10 μm.

[0022] In some embodiments, the specific surface area of ​​the negative electrode material is ≤20m². 2 / g;

[0023] In some embodiments, the compaction density of the negative electrode material is 1.28 g / cm³. 3 ~1.40g / cm 3 ;

[0024] In some embodiments, the true density of the negative electrode material is 2.20 g / cm³. 3 ~2.30g / cm 3 ;

[0025] In some embodiments, the powder conductivity of the negative electrode material at a pressure of 20 kN is 1 S / cm to 3 S / cm.

[0026] Secondly, this application provides a battery comprising a negative electrode material as described in the first aspect or a negative electrode material prepared by the preparation method described in the third aspect.

[0027] The technical solution of this application has at least the following beneficial effects:

[0028] The negative electrode material provided in this application, by controlling the specific surface area range of all pores and mesopores in the negative electrode material, is beneficial to improving the porosity of the negative electrode material. Here, A1-A2 can represent the specific surface area of ​​pores with a diameter of 2 nm or less among all pores in the negative electrode material. When (A1-A2) / A1 > 0.6:1, the specific surface area of ​​pores with a diameter of less than 2 nm in the negative electrode material is too large. After the battery is fabricated, the side reactions between the negative electrode material and the electrolyte are aggravated during charge-discharge cycles, and the initial coulombic efficiency of the negative electrode material decreases. When (A1-A2) / A1 < 0.08:1, the specific surface area of ​​pores with a diameter of less than 2 nm in the negative electrode material is too small, making it difficult for the electrolyte to quickly enter the negative electrode material, reducing the lithium-ion transport efficiency, decreasing the specific capacity and initial coulombic efficiency of the negative electrode material, and thus affecting the energy density and charging rate of the battery. This application controls 1.5≤A1≤5.5, 1≤A2≤5, and (A1-A2) / A1 within the range of 0.08~0.6:1, so that the specific surface area of ​​the pores in the negative electrode material is within a suitable range. This ensures that the negative electrode material can be effectively wetted by the electrolyte, improving the lithium ion transport efficiency, while also reducing side reactions between the negative electrode material and the electrolyte, improving the specific capacity and initial coulombic efficiency of the negative electrode material, and enhancing the cycle stability of the negative electrode material. The battery prepared from the negative electrode material can also have a faster charge and discharge rate. Attached Figure Description

[0029] Figure 1 is a schematic diagram of the discharge state of the battery provided in an embodiment of this application. Detailed Implementation

[0030] The following are preferred embodiments of the present application. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principles of the embodiments of the present application, and these improvements and modifications are also considered to be within the protection scope of the embodiments of the present application.

[0031] In a first aspect, this application provides a negative electrode material, the negative electrode material comprising a silicon-based material and a carbon material located on at least a portion of the surface of the silicon-based material; the negative electrode material has pores, the pores including micropores and mesopores, wherein the nitrogen adsorption specific surface area of ​​all pores in the negative electrode material is Al m. 2 / g, the nitrogen adsorption specific surface area of ​​pores with a pore size of 2nm or larger is A2 m 2 / g, the negative electrode material satisfies: 1.5≤A1≤5.5, 1≤A2≤5, and 0.08:1:1≤(A1-A2) / A1≤0.6:1.

[0032] The negative electrode material provided in this application controls the specific surface area of ​​all pores and the specific surface area of ​​mesopores in the negative electrode material. Here, A1-A2 can represent the specific surface area of ​​pores with a diameter of 2 nm or less in the negative electrode material. When (A1-A2) / A1 > 0.6:1, the specific surface area of ​​pores with a diameter of less than 2 nm in the negative electrode material is too large. After the battery is fabricated, the side reactions between the negative electrode material and the electrolyte are aggravated during charge-discharge cycles, and the initial coulombic efficiency of the negative electrode material decreases. When (A1-A2) / A1 < 0.08:1, the specific surface area of ​​pores with a diameter of less than 2 nm in the negative electrode material is too small, making it difficult for the electrolyte to quickly enter the negative electrode material, reducing the lithium-ion transport efficiency, decreasing the specific capacity and initial coulombic efficiency of the negative electrode material, and thus affecting the energy density and charging rate of the battery. This application controls 1.5≤A1≤5.5, 1≤A2≤5, and (A1-A2) / A1 within the range of 0.08 to 0.6:1, where A1>A2. This ensures that the specific surface area of ​​the pores in the negative electrode material is within a suitable range. This not only ensures that the negative electrode material can be effectively wetted by the electrolyte, improving the lithium-ion transport efficiency, but also reduces side reactions between the negative electrode material and the electrolyte, thereby increasing the specific capacity and initial coulombic efficiency of the negative electrode material, improving the cycle stability of the negative electrode material, and enabling the battery prepared from the negative electrode material to have a faster charge and discharge rate.

[0033] In some implementations, (A1-A2) / A1 can specifically be 0.08:1, 0.081:1, 0.085:1, 0.09:1, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.59:1, or 0.6:1, etc., or of course, other values ​​within the above range.

[0034] In some embodiments, the specific surface area of ​​all pores in the negative electrode material is A1 m. 2 / g, 1.5≤A1≤5.5, specifically A1 can be 1.5, 1.8, 2.0, 2.5, 2.8, 3.0, 3.5, 4.0, 4.5, 4.8 or 5.5, etc., or of course, other values ​​within the above range, which are not limited here.

[0035] In some embodiments, the specific surface area of ​​the pores with a diameter of 2 nm or larger in the negative electrode material is A² m. 2 / g, 1≤A2≤5, specifically A2 can be 1, 1.1, 1.2, 1.5, 2.0, 2.8, 3.0, 3.5, 4.0, 4.5, 4.8 or 5.0, etc., or other values ​​within the above range, which are not limited here.

[0036] In some embodiments, the total pore volume of the negative electrode material is 0.006 cm³. 3 / g~0.01cm3 / g, specifically 0.006cm 3 / g, 0.0065cm 3 / g, 0.007cm 3 / g, 0.0075cm 3 / g, 0.008cm 3 / g, 0.0085cm 3 / g, 0.009cm 3 / g, 0.0095cm 3 / g or 0.01cm 3 / g, etc., can also be other values ​​within the above range, and are not limited here. The presence of an appropriate amount of porosity in the negative electrode material can alleviate the volume expansion of the silicon-based material, which is conducive to the effective wetting of the negative electrode material and the electrolyte, and improves the lithium-ion transport efficiency.

[0037] In some embodiments, the contact angle between the negative electrode material and the electrolyte with a lithium ion concentration of 1 mol / L is B1, and the contact angle between the negative electrode material and water is B2. The negative electrode material satisfies the following ratio: 1:1 < B2 / B1 < 1.1:1. Specifically, B2 / B1 can be 1.01:1, 1.05:1, 1.06:1, 1.07:1, 1.08:1, 1.09:1, or 1.095:1, etc., or other values ​​within the above range, which are not limited here. The electrolyte is formed by dissolving lithium hexafluorophosphate in an organic solvent, wherein the organic solvent is composed of ethyl methyl carbonate, ethylene carbonate, and dimethyl carbonate in a volume ratio of 1:1:1.

[0038] This application controls the specific surface area of ​​the pores in the negative electrode material, while also controlling the ratio of the contact angle between the negative electrode material and the electrolyte to the contact angle between the negative electrode material and water. When the B2 / B1 ratio is within the above range, the electrolyte can quickly wet the negative electrode material without affecting its coating and dispersion state. The rapid penetration of the electrolyte into the negative electrode material can improve the specific capacity, initial coulombic efficiency, and charging rate of the negative electrode material. It can also reduce the interfacial impedance between the electrolyte and the negative electrode material, thereby improving the cycle stability of the negative electrode material.

[0039] In some embodiments, the contact angle between the negative electrode material and the electrolyte with a lithium-ion concentration of 1 mol / L is B1°, where 145° ≤ B1 ≤ 155°. Specifically, it can be 145°, 147°, 148°, 150°, 152°, 153°, or 155°, or other values ​​within the above range, which are not limited here. When B1 is too small, the electrolyte can easily penetrate into the interior of the negative electrode material, exacerbating the side reactions between the negative electrode material and the electrolyte, increasing the irreversible consumption of active lithium ions, decreasing the specific capacity of the negative electrode material, and reducing the cycle retention rate. When B1 is too large, the electrolyte has difficulty penetrating into the interior of the negative electrode material. Although the side reactions are reduced, the impedance of the interface between the negative electrode material and the electrolyte increases, making it difficult to effectively utilize the specific capacity of the negative electrode material, and reducing the battery energy density.

[0040] In some embodiments, the contact angle between the negative electrode material and water is B2°, 150°≤B2≤160°, specifically 150°, 152°, 155°, 156°, 158°, 159° or 160°, etc., and of course, other values ​​within the above range are also possible, which are not limited here.

[0041] In some implementations, 0.08:1 < [(A1-A2) / A1] / (B2 / B1) < 0.7:1, and the specific ratio can be 0.082:1, 0.09:1, 0.1:1, 0.15:1, 0.2:1, 0.25:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, or 0.65:1, etc. Of course, it can also be other values ​​within the above range, which are not limited here. When the ratio of [(A1-A2) / A1] / (B2 / B1) is too small, it may be because (A1-A2) / A1 is too small, resulting in a small specific surface area of ​​the pores in the negative electrode material, fewer pores, and an aggravated expansion effect of the negative electrode material, thus reducing its cycle performance. Alternatively, it may be because B2 / B1 is too large, resulting in an excessively large contact angle between the negative electrode material and water, which will affect the dispersion state of the negative electrode material during the coating process, leading to increased local expansion of the negative electrode sheet during charging and discharging, thus affecting the cycle performance of the battery. When the ratio [(A1-A2) / A1] / (B2 / B1) is too large, it may be because an excessively large (A1-A2) / A1 ratio allows the electrolyte to easily enter the pores of the negative electrode material, leading to increased side reactions and a decrease in the initial coulombic efficiency of the negative electrode material. Alternatively, an excessively small B2 / B1 ratio results in an excessively large contact angle between the negative electrode material and the electrolyte, making it difficult for the electrolyte to penetrate into the interior of the negative electrode material particles. This increases the impedance of the interface between the negative electrode material and the electrolyte, hindering the effective utilization of the specific capacity of the negative electrode material. This application controls [(A1-A2) / A1] / (B2 / B1) within the aforementioned range, synergistically controlling both the electrolyte contact angle and the specific surface area of ​​the negative electrode material pores. This reduces side reactions between the electrolyte and the negative electrode material, improves the expansion effect of the negative electrode material, and facilitates the acquisition of a negative electrode material with high specific capacity, good cycle performance, and initial coulombic efficiency. Preferably, 0.08:1 < [(A1-A2) / A1] / (B2 / B1) < 0.365:1.

[0042] In some embodiments, the silicon-based material includes at least one of amorphous silicon, crystalline silicon, and silicon oxide.

[0043] In some embodiments, the silicon oxide includes silicon and oxygen elements, and the atomic ratio of silicon to oxygen is 0 to 2:1, excluding 0:1. Specifically, the atomic ratio of silicon to oxygen can be 0.05:1, 0.11:1, 0.21:1, 0.26:1, 0.31:1, 0.41:1, 0.51:1, 0.59:1, 0.61:1, 0.69:1, 0.71:1, 0.74:1, 0.76:1, 0.79:1, 0.89:1, 0.99:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, etc., which are not limited herein. Preferably, the atomic ratio of silicon to oxygen is 0 to 1:1, excluding 0:1.

[0044] In some embodiments, the general chemical formula of the silicon oxide is SiO x , where 0 < x ≤ 2. Specifically, x can be 0.05, 0.11, 0.21, 0.26, 0.31, 0.41, 0.51, 0.59, 0.61, 0.69, 0.71, 0.74, 0.76, 0.79, 0.89, 0.99, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, etc., which are not limited herein. Preferably, 0 < x < 1. The silicon-oxygen material can be a material formed by silicon particles dispersed in SiO2, or a material with a tetrahedral structural unit, where silicon atoms are located at the center of the tetrahedral structural unit, and oxygen atoms and / or silicon atoms are located at the four vertices of the tetrahedral structural unit.

[0045] In some embodiments, the carbon material includes at least one of amorphous carbon, carbon nanoparticles, carbon nanotubes, and graphene. Preferably, the carbon material includes amorphous carbon. Combining amorphous carbon and the silicon-based material can comprehensively improve the conductivity of the anode material and reduce swelling.

[0046] In some embodiments, the silicon-based material is dispersed in the carbon material, and the carbon material constructs a conductive network for the silicon-based material, overcoming the disadvantage of poor conductivity of the silicon-based material (such as the silicon oxide SiO x ), which is beneficial to the capacity performance and cycle stability of the silicon-based material.

[0047] In some embodiments, in the anode material, the volume ratio of micropores in the total pore volume of all pores is 6% to 9%, and the volume ratio of mesopores in the total pore volume of all pores is 80% to 90%. Micropores are defined according to the International Union of Pure and Applied Chemistry (IUPAC) as pores with a pore diameter less than 2 nm; macropores are pores with a pore diameter greater than 50 nm; mesopores (or middle pores) are pores with a pore diameter between 2 - 50 nm.

[0048] Specifically, the volume percentage of micropores can be 6%, 6.5%, 6.8%, 7%, 7.2%, 7.5%, 8%, 8.5%, 8.8%, or 9%, etc., and is not limited here. The volume percentage of mesopores can be 80%, 85%, 88%, 89%, or 90%, etc., and is not limited here.

[0049] In some embodiments, the median particle size D of the negative electrode material 50 The value ranges from 1μm to 10μm; specifically, it can be 1μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 5μm, 6μm, 8μm, 9μm or 10μm, etc., and is not limited here.

[0050] In some implementations, the specific surface area of ​​the negative electrode material is ≤20m². 2 / g; specifically, it can be 1.0m 2 / g, 1.5m 2 / g, 1.8m 2 / g, 2.0m 2 / g, 2.5m 2 / g, 3.0m 2 / g, 3.6m 2 / g, 4.0m 2 / g、5m 2 / g, 5.5m 2 / g, 6.0m 2 / g, 7.0m 2 / g, 8.0m 2 / g, 8.5m 2 / g, 10.0m 2 / g, 12.0m 2 / g, 15.0m 2 / g, 18.0m 2 / g or 20.0m 2 / g, but not limited to the listed values; other unlisted values ​​within this range also apply. Controlling the specific surface area of ​​the anode material within the above range is beneficial for improving its initial coulombic efficiency. When the specific surface area of ​​the anode material is too large, side reactions between the anode material and the electrolyte increase, consuming more active lithium ions and reducing the initial coulombic efficiency of the anode material. Preferably, the specific surface area of ​​the anode material is ≤10m². 2 / g.

[0051] In some embodiments, the compaction density of the negative electrode material is 1.28 g / cm³. 3 ~1.40g / cm 3 Specifically, it could be 1.28 g / cm³. 3 1.30g / cm 3 1.31 g / cm3 1.32g / cm 3 1.33g / cm 3 1.35g / cm 3 1.38g / cm 3 1.39 g / cm 3 Or 1.40g / cm 3 etc. are not specified here.

[0052] In some embodiments, the true density of the negative electrode material is 2.20 g / cm³. 3 ~2.30g / cm 3 Specifically, it could be 2.20 g / cm³. 3 2.22 g / cm 3 2.23 g / cm 3 2.24 g / cm 3 2.25g / cm 3 2.26 g / cm 3 2.28g / cm 3 Or 2.30 g / cm 3 etc. are not specified here.

[0053] In some embodiments, the powder conductivity of the negative electrode material at a pressure of 20 kN is 1 S / cm to 3 S / cm, specifically 1.0 S / cm, 1.1 S / cm, 1.3 S / cm, 1.5 S / cm, 1.8 S / cm, 2.0 S / cm, 2.5 S / cm, or 3 S / cm, etc., or other values ​​within the above range, which are not limited here. Good powder conductivity of the negative electrode material is beneficial to improving its cycle performance. When the powder conductivity of the negative electrode material is too low, the structure of the negative electrode material is more porous or the conductive network is worse, resulting in decreased cycle stability.

[0054] In some embodiments, the mass content of silicon in the negative electrode material is m. Si %, 53% ≤ m Si ≤64%; specifically, it can be 53%, 56%, 58%, 60%, 62%, 63%, or 64%, etc., and of course, it can also be other values ​​within the above range, which are not limited here.

[0055] In some embodiments, the mass content of oxygen in the negative electrode material is m. O %, 35% ≤ m O ≤37%; specifically, it can be 35%, 35.5%, 35.8%, 36%, 36.2%, 36.4%, 36.5%, 36.8%, or 37%, etc. Of course, it can also be other values ​​within the above range, which are not limited here.

[0056] In some embodiments, the mass content of carbon in the negative electrode material is m. C %, 1% ≤ m C ≤6%, the specific mass content of carbon element can be 1%, 2%, 3%, 4%, 4.5%, 5%, 5.5% or 6%, etc., and of course it can also be other values ​​within the above range, which are not limited here.

[0057] In some implementations, carbon material forms a carbon layer on the surface of the silicon-based material.

[0058] In some embodiments, the thickness of the carbon layer is 1 nm to 1000 nm, specifically 1 nm, 5 nm, 10 nm, 15 nm, 20 nm, 50 nm, 80 nm, 100 nm, 150 nm, 200 nm, 400 nm, 500 nm, 700 nm, 800 nm, 900 nm, or 1000 nm, etc., and is not limited herein. If the carbon layer is too thick, the carbon content is too high, which is not conducive to obtaining a negative electrode material with high specific capacity; if the carbon layer is too thin, it is not conducive to increasing the conductivity of the negative electrode material and has weak performance in suppressing volume expansion, resulting in poor long-cycle performance. Controlling the carbon layer thickness within the above range is beneficial to improving the conductivity and cycle stability of the negative electrode material. Preferably, the thickness of the carbon layer is 50 nm to 800 nm; more preferably, the thickness of the carbon layer is 100 nm to 500 nm.

[0059] Secondly, this application provides a method for preparing a negative electrode material, comprising the following steps:

[0060] Step S10: The silicon powder is placed in a mixed acid solution containing hydrofluoric acid and copper nitrate for a first acid wash, and then placed in a nitric acid solution for a second acid wash. Solid-liquid separation is performed to obtain silicon powder after the second acid wash.

[0061] Step S20: The undried silicon powder after secondary acid washing is subjected to surface plasma treatment to obtain a precursor, wherein the precursor includes silicon suboxide.

[0062] Step S30: Carbon coating treatment is performed on the precursor to obtain the anode material.

[0063] In the above scheme, silicon powder is placed in a mixed acid solution for a first acid wash. Hydrofluoric acid can etch the surface of the silicon powder. During the second acid wash, the etching extends from the particle surface to the interior, forming fine etched pores in the silicon powder. Then, the silicon powder is subjected to surface plasma treatment. The plasma bombards the interior of the silicon particles along the etched pores on the surface of the silicon powder, and the etched pores continue to extend into the particle interior, increasing the total pore volume of the anode material. At the same time, the plasma oxidizes the silicon particles, so that at least part of the silicon is oxidized to silicon suboxide. Finally, carbon coating treatment is used to form a carbon layer on the surface of the precursor. The presence of the carbon layer can reduce the side reactions between the active material and the electrolyte, improve the specific capacity and initial coulombic efficiency of the anode material, and improve the cycle stability of the anode material.

[0064] Step S10: The silicon powder is placed in a mixed acid solution containing hydrofluoric acid and copper nitrate for a first acid wash, and then placed in a nitric acid solution for a second acid wash. Solid-liquid separation is performed to obtain silicon powder after the second acid wash.

[0065] In some embodiments, the concentration of hydrofluoric acid is 4 mol / L to 10 mol / L, specifically 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L or 10 mol / L, etc., and is not limited here.

[0066] In some embodiments, the amount of copper nitrate added to the mixed acid solution is 30 mmol to 40 mmol, specifically 30 mmol, 32 mmol, 34 mmol, 35 mmol, 36 mmol, 38 mmol or 40 mmol, etc., which is not limited here.

[0067] In some embodiments, silicon powder is added to the mixed acid solution in multiple batches, and acid washing is performed by stirring for 2 to 4 hours.

[0068] In some embodiments, the stirring time for a single pickling process can be 2 hours, 2.5 hours, 3 hours, 3.5 hours, or 4 hours, etc., and is not limited here.

[0069] In some embodiments, the median particle size of the silicon powder is 1μm to 5μm, specifically 1μm, 2μm, 3μm, 4μm or 5μm, etc., which are not limited here.

[0070] In some embodiments, the product after a single acid wash is placed in a plastic centrifuge tube, and the centrifugation speed is adjusted to 1000 r / min to 4000 r / min to separate the solid and liquid and obtain silicon powder. Specifically, the centrifugation speed can be 1000 r / min, 1500 r / min, 2000 r / min, 2500 r / min, 3000 r / min, 3500 r / min or 4000 r / min, etc., and is not limited here.

[0071] Understandably, when silicon powder is added to a mixed acid solution, hydrofluoric acid can etch the surface of the silicon powder. Under centrifugal stirring, the etching extends from the surface of the particles inward, resulting in fine etched holes in the silicon powder.

[0072] In some embodiments, an H3NO3 solution with a concentration of 15 mol / L to 30 mol / L is prepared, and then 15% (v / v) of ethanol is added and stirred for 2 to 4 hours to obtain a secondary acid washing solution. Specifically, the concentration of the H3NO3 solution can be 15 mol / L, 16 mol / L, 18 mol / L, 20 mol / L, 22 mol / L, 24 mol / L, 26 mol / L, 28 mol / L, or 30 mol / L, etc., and is not limited here. The stirring time after adding 15% (v / v) of ethanol can be 2 hours, 2.5 hours, 3 hours, 3.5 hours, or 4 hours, etc., and is not limited here.

[0073] In some embodiments, the silicon powder after the first pickling treatment is placed in a second pickling solution and stirred for 2 to 6 hours. Then, the solution is filtered using a vacuum filter to obtain silicon powder. Specifically, the stirring time can be 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, or 6 hours, etc., and is not limited here.

[0074] Step S20: The undried silicon powder after secondary acid washing is subjected to surface plasma treatment to obtain a precursor, wherein the precursor includes silicon suboxide.

[0075] In some implementations, the output current of the plasma furnace is 130A to 160A, and the output voltage is 5V. Specifically, the output current can be 130A, 135A, 140A, 145A, 150A, 155A, or 160A, etc., and is not limited here.

[0076] In some embodiments, the heating temperature during plasma treatment is 400°C to 600°C, specifically 400°C, 450°C, 500°C, 550°C, 580°C, or 600°C, etc., and is not limited here.

[0077] In some implementations, the plasma treatment time is 3h to 6h, specifically 3h, 3.5h, 4h, 4.5h, 5h, 5.5h or 6h, etc., and is not limited here.

[0078] In some embodiments, the cooling water temperature of the plasma furnace is 30°C to 60°C, and the cooling water header pressure is 0.3MPa to 0.6MPa. Specifically, the cooling water temperature can be 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, or 60°C, and the cooling water header pressure can be 0.3MPa, 0.35MPa, 0.4MPa, 0.45MPa, 0.5MPa, or 0.6MPa, etc., and is not limited here.

[0079] In some implementations, oxygen is introduced during the plasma treatment process, wherein the oxygen concentration is >99%.

[0080] Step S30: Carbon coating treatment is performed on the precursor to obtain the anode material.

[0081] In some embodiments, the carbon coating process includes one or more combinations of liquid phase coating, solid phase coating, and gas phase coating.

[0082] In some embodiments, the carbon coating process specifically includes mixing a liquid carbon source and a precursor to obtain a mixture.

[0083] In some implementations, the mixing method includes at least one of VC mixing, fusion, triple-eccentric mixing, hand mixing, kneading, spiral mixing, and ball milling.

[0084] In some embodiments, the liquid-phase carbon source includes at least one selected from bitumen, coal-based carbon, petroleum-based carbon, biomass, alkanes, olefins, and alkynes. Specifically, bitumen includes at least one selected from coal tar pitch, petroleum bitumen, and natural bitumen.

[0085] In some embodiments, the carbon coating process further includes: heating the mixture, then introducing a protective gas and a carbon source gas, and thermally decomposing the carbon source gas to obtain the carbon-coated product.

[0086] In some embodiments, the carbon source gas used for gas-phase carbon coating includes hydrocarbons.

[0087] In some embodiments, the carbon source gas includes at least one selected from methane, acetylene, ethylene, ethane, propane, propylene, propyne, acetone, and benzene.

[0088] In some embodiments, the chemical vapor deposition apparatus includes at least one of a rotary chemical vapor deposition reactor, a plasma-enhanced chemical vapor deposition reactor, a chemical vapor deposition tube furnace, and a fluidized bed. Specifically, the chemical vapor deposition apparatus is at least one of a rotary furnace and a box furnace.

[0089] In some embodiments, the thermal decomposition temperature is 300℃ to 1000℃, specifically 300℃, 500℃, 600℃, 700℃, 800℃, 900℃, 950℃ or 1000℃, etc., and of course other values ​​within the above range are also possible, which are not limited here.

[0090] In some embodiments, the thermal decomposition time is 2h to 10h. The specific thermal decomposition time can be 2h, 4h, 5h, 6h, 8h, 9h or 10h, etc., or other values ​​within the above range, which are not limited here.

[0091] In some implementations, a carbon source gas is introduced under a protective gas atmosphere.

[0092] In some embodiments, the protective gas includes at least one of nitrogen, helium, neon, argon, krypton, and xenon.

[0093] In some embodiments, the thickness of the carbon layer is 1 nm to 1000 nm, specifically 1 nm, 5 nm, 10 nm, 15 nm, 20 nm, 50 nm, 80 nm, 100 nm, 150 nm, 200 nm, 400 nm, 500 nm, 700 nm, 800 nm, 900 nm, or 1000 nm, etc., and is not limited thereto. Controlling the carbon layer thickness within the above range can increase the conductivity of the anode material, which is beneficial for obtaining anode materials with high specific capacity; and the carbon layer can effectively alleviate the volume expansion of silicon-based materials and improve the long-cycle performance of the anode material. Preferably, the thickness of the carbon layer is 50 nm to 800 nm; more preferably, the thickness of the carbon layer is 100 nm to 500 nm.

[0094] Furthermore, the above method also includes: screening and demagnetizing the carbon-coated material to obtain the negative electrode material.

[0095] In some embodiments, the screening method is any one of a fixed screen, drum screen, resonant screen, roller screen, vibrating screen, and chain screen, and the screening mesh is 100 mesh to 500 mesh. Specifically, the screening mesh can be 100 mesh, 200 mesh, 250 mesh, 325 mesh, 400 mesh, or 500 mesh, etc. Preferably, the screening mesh is 250 mesh. Controlling the particle size of the negative electrode material within the above range is beneficial to improving the processing performance of the negative electrode material.

[0096] In some implementations, the demagnetizing equipment is any one of a permanent magnet drum magnetic separator, an electromagnetic iron remover, and a pulsed high-gradient magnetic separator. Demagnetization is to ultimately control the magnetic content of the negative electrode material, thereby avoiding the impact of magnetic materials on the discharge effect of the lithium-ion battery and the safety of the battery during use.

[0097] This invention also provides a battery. Figure 1 is a schematic diagram of the discharge state of the battery provided in this embodiment. As shown in Figure 1, the battery includes a casing and an electrode assembly. The electrode assembly includes a positive electrode 1, a negative electrode 2, and a separator 3, with the separator 3 disposed between the positive electrode 1 and the negative electrode 2. The electrode assembly can be a stacked structure, formed by alternately stacking the positive electrode 1, the separator 3, and the negative electrode 2. In other embodiments, the electrode assembly can also be a wound structure, formed by sequentially stacking and winding the positive electrode 1, the separator 3, and the negative electrode 2.

[0098] In some embodiments, the positive electrode 1 includes a positive current collector 101 and a positive active layer 102 disposed on at least one surface of the positive current collector 101.

[0099] In some embodiments, the positive current collector 101 may be made of aluminum foil or nickel foil, or any composite current collector disclosed in the prior art, such as, but not limited to, current collectors formed by combining the aforementioned conductive foil (aluminum foil or nickel foil, etc.) with a polymer substrate. The positive active layer 102 comprises a positive active material, which includes compounds that reversibly insert and deintercalate metal ions.

[0100] In some embodiments, the positive electrode active material may include lithium transition metal composite oxides, sodium transition metal composite oxides, etc. The lithium transition metal composite oxide contains lithium and at least one element selected from cobalt, manganese, and nickel.

[0101] In some embodiments, the positive electrode active material may include, but is not limited to, lithium cobalt oxide (LiCoO2), lithium nickel manganese cobalt ternary materials (NCM), and lithium manganese oxide (LiMn2O3). 4) Lithium nickel manganese oxide (LiNi) 0.5 Mn 1.5 At least one of O4 and lithium iron phosphate (LiFePO4).

[0102] In some embodiments, the negative electrode 2 includes a negative electrode current collector 201 and a negative electrode active material layer 202 disposed on at least one surface of the negative electrode current collector 201.

[0103] In some embodiments, the negative electrode current collector 201 may be at least one of copper foil, nickel foil, stainless steel foil, titanium foil, or carbon-based current collector, or any composite current collector disclosed in the prior art, such as, but not limited to, current collectors formed by combining the aforementioned conductive foil and polymer substrate. The negative electrode active material layer 202 includes a negative electrode material, which is the negative electrode material described in the first aspect or the negative electrode material prepared by the aforementioned preparation method.

[0104] The battery provided in this application has the advantages of high capacity, high initial efficiency, long cycle life, excellent rate performance, and low expansion. The battery can be a lithium-ion battery, a sodium-ion battery, a solid-state electrolyte battery, etc., and is not limited thereto.

[0105] The embodiments of the present invention will be further described below with reference to several examples. The following examples are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. Where there is no conflict, the embodiments and features of the embodiments of the present application can be combined with each other. Many specific details are set forth in the following description to provide a thorough understanding of the present application; the described embodiments are only a part of the embodiments of the present application, and not all of them.

[0106] The embodiments of this application will be further described below through multiple examples.

[0107] Example 1

[0108] A method for preparing a negative electrode material includes the following steps:

[0109] (1) 3g of silicon powder with D50 = 3μm was added in three portions (1g each time) to a mixed acid solution of 40mmol Cu(NO3)2 and 4.6mol / LHF for a first acid treatment. After stirring for 3h, the solution was placed in a plastic centrifuge tube and centrifuged at 4000r / min. After removing the solution from the centrifuge, silicon powder was obtained. 15mol / L H3NO3 and 15% ethanol were added again and stirred for 2h. The centrifuged silicon powder was then added again and stirred for another 2h for a second acid treatment. The solution was then filtered using a vacuum filter to obtain the acid-treated silicon powder.

[0110] (2) Place the undried silicon powder after acid treatment into a plasma furnace, control the output current of the plasma furnace to be 150A and the output voltage to be 5V, introduce oxygen into the plasma furnace with an oxygen concentration of >99%, heat the silicon powder to 400℃ and hold for 3h, during the plasma process, control the cooling water temperature in the plasma furnace to be 40℃ and the main pipe pressure of the cooling water to be 0.6MPa, after the holding is completed, turn off the current and voltage, and cool to obtain the precursor, the precursor including silicon suboxide.

[0111] (3) The precursor was mixed in liquid asphalt at a mass ratio of 100:5 for 2 hours. The mixture was placed in an atmosphere furnace, and acetylene was introduced under nitrogen protection. The temperature was raised to 300°C and kept at that temperature for 4 hours before being taken out to obtain the negative electrode material.

[0112] Following the preparation steps of Example 1, Examples 2 through 10 were prepared. The specific process parameters for each example are shown in Table 1.

[0113] Table 1. Summary of process parameters for negative electrode materials

[0114] Comparative Example 1

[0115] A method for preparing a negative electrode material includes the following steps:

[0116] (1) Place 1.5 kg of silicon and 1.5 kg of silicon dioxide into a vacuum furnace with a vacuum degree of 100 Pa, heat to 1600 °C and hold for 6 h to obtain silicon suboxide.

[0117] (2) After cooling to 1100℃, acetylene is introduced to carbon-coat the surface of silicon suboxide. The carbon content of the carbon-containing gas is ≈30%, and the carbon coating amount is <3%, thus obtaining the negative electrode material.

[0118] Comparative Example 2

[0119] Unlike Example 1, step (2) was not performed.

[0120] The performance of the anode materials prepared in the examples and comparative examples was tested, and the results of the performance tests are shown in Tables 2 and 3:

[0121] Test method:

[0122] 1) Particle size of the negative electrode material:

[0123] The particle size testing method refers to GB / T 19077-2016. The cumulative particle size distribution based on volume is determined by laser diffraction. D10 represents the particle size corresponding to 10% of the cumulative particle size distribution, D50 represents the particle size corresponding to 50% of the cumulative particle size distribution, and D90 represents the particle size corresponding to 90% of the cumulative particle size distribution.

[0124] 2) Test methods for specific surface area and pore size of negative electrode materials:

[0125] After measuring the amount of gas adsorbed on the solid surface at different relative pressures under constant temperature and low temperature, the amount of monolayer adsorption of the sample is obtained based on the Brownnor-Etter-Taylor adsorption theory and its formula (BET formula), thereby calculating the specific surface area and total pore volume of the material.

[0126] Nitrogen adsorption specific surface area of ​​mesoporous (pore size greater than 2 nm): test relative pressure range: 0.05~0.30 Pa, pretreatment conditions: 300℃, 1h, nitrogen purging, sample weight: 1 / 2~2 / 3 of the volume of the bubble tube.

[0127] Nitrogen adsorption specific surface area of ​​all pores: Test relative pressure range: 0 Pa to 1 Pa, pretreatment conditions: 300℃, 2 h, vacuum. Sample weight: 0.15 ± 0.3 g.

[0128] 3) The proportion of pore volume of various types in the negative electrode material

[0129] Nitrogen adsorption technology was used to test the porosity and pore size distribution of the anode material. As pressure increased, nitrogen first condensed in the pores with the smallest diameter, and the pressure continued to rise until a saturation point was reached, at which point all pores were filled with liquid. The nitrogen pressure was then gradually decreased to allow the liquid to evaporate from the system. Analysis of the adsorption and desorption isotherms allowed for the determination of pore volume and pore size distribution, as well as the respective proportions of micropores, mesopores, and macropores in the total pore volume.

[0130] 4) Test method for the mass content of carbon in negative electrode materials:

[0131] The carbon content of the material was tested using an infrared carbon-sulfur analyzer (CSI, Eertek, Germany).

[0132] 5) Test method for the mass content of oxygen in negative electrode materials:

[0133] The oxygen content in the negative electrode material was tested using an oxygen, nitrogen, and hydrogen analyzer (Erther, Germany, ONH-2000).

[0134] 6) Test method for the mass content of silicon in anode materials:

[0135] Based on the measured mass content m of carbon in the negative electrode material C Mass content of oxygen element m O The mass content of silicon element, m, was calculated. Si =1-m C -m O .

[0136] 7) Test method for compaction density of negative electrode material:

[0137] The compaction density of the negative electrode material was tested according to GB / T 24533-2019, and the testing equipment was a compaction density meter (Shenzhen Sansi Zongheng Technology Co., Ltd., UTM7305).

[0138] 8) True density testing method for negative electrode materials:

[0139] True density test: The true density of the negative electrode material was tested in accordance with GB / T 24533-2019. The testing equipment used was a true density tester (Best Instruments Technology (Beijing) Co., Ltd., 3H-2000TD).

[0140] 9) Contact angle test between negative electrode material and electrolyte or water:

[0141] Contact angle: In-situ video contact angle measuring instrument was used.

[0142] Procedure: Compress and smooth the sample powder, drop a certain volume of liquid from a certain height directly above it, record the process of the liquid falling onto the sample plane, and measure the contact angle of the droplet when the droplet is in stable contact with the plane (circular method).

[0143] 10) Powder conductivity test of negative electrode material

[0144] The powder conductivity of the negative electrode material was tested according to the equipment and methods specified in BTRTC / ZY / 02-093 "Operating Instruction for Powder Conductivity Testing". The testing equipment was from Mitsubishi Chemical, Japan. Test parameters included: initial resistance on the order of -3 (selectable), voltage limit on the order of 10V (selectable), and sample quality ensuring a thickness of 3–5 mm under 20 kN pressure. Pressures were set at 4 kN, 8 kN, 12 kN, 16 kN, and 20 kN. The electrode radius was 0.7 mm, and the sample radius was 10 mm.

[0145] 11) Button cell battery test

[0146] The prepared negative electrode material, conductive carbon black, and polyacrylic acid binder were dissolved in a solvent at a mass ratio of 75:15:10 and mixed. The mixture was then coated onto a copper foil current collector and vacuum dried to obtain the negative electrode sheet. A lithium metal sheet was used as the counter electrode, and the cells were assembled into a coin cell in an argon-filled glove box. Charge-discharge tests were conducted at a current density of 0.1C, within a charge-discharge range of 0.01V to 1.5V.

[0147] 12) Electrochemical performance testing

[0148] The prepared negative electrode material was mixed with graphite at a ratio of 10:90, and then mixed with sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR) binder, Super-P conductive agent, and KS-6 conductive agent at a mass ratio of 92:2:2:2 to form a slurry. This slurry was coated onto copper foil and then vacuum dried and rolled to prepare the negative electrode sheet. Then, a ternary positive electrode sheet prepared using conventional mature processes, a 1 mol / L LiPF6 / ethylene carbonate + dimethyl carbonate + methyl ethyl carbonate (v / v = 1:1:1) electrolyte, a Celgard 2400 separator, and a casing were assembled into a CR2016 simulated battery using conventional production processes. Cycle performance testing was conducted using a constant current charge-discharge experiment at 30 mA, with the charge-discharge voltage limited to 0V–1.5V. The LAND battery testing system from Wuhan Jinno Electronics Co., Ltd. was used for testing. Charge-discharge tests were conducted at a current density of 0.1C, within a charge-discharge range of 0.005V–1.5V.

[0149] Initial Coulomb efficiency = First discharge capacity / First charge capacity.

[0150] Repeat the cycle 50 times. Use a micrometer to measure the thickness of the electrode at this time, which is H1. After 50 cycles, the expansion rate is (H1-H0) / H0×100%, where H0 is the initial thickness of the electrode.

[0151] Repeat the cycle 100 times and record the discharge capacity as the remaining capacity of the lithium-ion battery; capacity retention rate = remaining capacity / initial capacity * 100%.

[0152] Table 2. Summary of Performance Test Results of Anode Materials

[0153] Table 3. Performance test results of anode materials

[0154] Table 4. Summary of Electrochemical Performance Results of the Battery

[0155] According to the data in Tables 1 to 4, controlling (A1-A2) / A1 within the above range ensures that the microporous specific surface area of ​​the negative electrode material is within a suitable range. This not only ensures that the negative electrode material can be effectively wetted by the electrolyte, improving the lithium-ion transport efficiency, but also reduces side reactions between the negative electrode material and the electrolyte, thereby increasing the specific capacity and initial coulombic efficiency of the negative electrode material, improving the cycle stability of the negative electrode material, and enabling the battery prepared from the negative electrode material to have a faster charge and discharge rate.

[0156] According to the data from Examples 1 to 3, as the concentration of HF or HNO3 increases, the number of etched holes in the silicon-based material increases, the A1 of the negative electrode material increases, and the A2 also increases. The total pore volume of the negative electrode material increases, and the compaction density decreases slightly.

[0157] According to the test data of Examples 1, 4 and 5, as the heating temperature increases during plasma treatment, the oxidation reaction rate of silicon powder surface accelerates. Under the surface coating of silicon oxide, the bombardment of silicon particles by plasma treatment is reduced, the A1 and A2 of the negative electrode material decrease, the total pore volume of the negative electrode material decreases, and the compaction density increases slightly.

[0158] According to the test data of Examples 1 and 6 to 7, as the temperature of the cooling water in the plasma furnace increases, the bombardment of the silicon powder surface and interior by the plasma intensifies, the A1 and A2 of the negative electrode material both increase, the total pore volume of the negative electrode material increases, and the compaction density decreases slightly.

[0159] According to the test data of Examples 1 and 8 to 9, the pressure of the cooling water main pipe in the plasma furnace has little effect on plasma treatment, and the relevant properties of the negative electrode material are similar to those of Example 1.

[0160] According to the test data of Example 1 and Comparative Example 1, in Comparative Example 1, silicon and silicon dioxide were directly placed in a vacuum furnace to synthesize silicon suboxide at high temperature. During the high-temperature synthesis process, the negative electrode material formed more pores, and the A1 and A2 of the negative electrode material were too large, which led to the aggravation of the side reaction between the negative electrode material and the electrolyte, the decrease in the specific capacity of the negative electrode material, the significant decrease in the first efficiency, and the aggravation of expansion.

[0161] According to the test data of Example 1 and Comparative Example 2, Comparative Example 2 did not undergo plasma treatment. Plasma treatment reduced the bombardment of the silicon particles, significantly reduced A1 and A2 of the negative electrode material, decreased the total pore volume of the negative electrode material, made it difficult for the electrolyte to penetrate into the particles of the negative electrode material, increased the impedance of the interface between the negative electrode material and the electrolyte, made it difficult for the specific capacity of the negative electrode material to be effectively utilized, and intensified the expansion after charge-discharge cycles.

[0162] Although this application discloses preferred embodiments as described above, it is not intended to limit the claims. Any person skilled in the art can make several possible changes and modifications without departing from the concept of this application. Therefore, the scope of protection of this application should be determined by the scope defined in the claims of this application.

Claims

1. A negative electrode material, characterized in that, The negative electrode material comprises a silicon-based material and a carbon material located on at least a portion of the surface of the silicon-based material; the negative electrode material has pores, wherein the nitrogen adsorption specific surface area of ​​all pores in the negative electrode material is Al m. 2 / g, the nitrogen adsorption specific surface area of ​​pores with a pore size of 2nm or larger is A2 m 2 / g, the negative electrode material satisfies: 1.5≤A1≤5.5, 1≤A2≤5, and 0.08:1:1≤(A1-A2) / A1≤0.6:

1.

2. The negative electrode material according to claim 1, characterized in that, The total pore volume of the negative electrode material is 0.006 cm³. 3 / g~0.01cm 3 / g.

3. The negative electrode material according to claim 1, characterized in that, The contact angle between the negative electrode material and the electrolyte with a lithium ion concentration of 1 mol / L is B1, and the contact angle between the negative electrode material and water is B2. The negative electrode material satisfies the following: 1:1 < B2 / B1 < 1.1:

1. The electrolyte is formed by dissolving lithium hexafluorophosphate in an organic solvent, and the organic solvent is composed of ethyl methyl carbonate, ethylene carbonate, and dimethyl carbonate in a volume ratio of 1:1:

1.

4. The negative electrode material according to claim 3, characterized in that, 145°≤B1≤155°; 150°≤B2≤160°.

5. The negative electrode material according to claim 3, characterized in that, 0.08:1<[(A1-A2) / A1] / (B2 / B1)<0.7:

1.

6. The negative electrode material according to claim 5, characterized in that, 0.08:1<[(A1-A2) / A1] / (B2 / B1)<0.365:

1.

7. The negative electrode material according to any one of claims 1 to 6, characterized in that, The negative electrode material satisfies at least one of the following characteristics: (1) The silicon-based material includes at least one of amorphous silicon, crystalline silicon and silicon oxide; (2) The carbon material includes at least one of amorphous carbon, carbon nanoparticles, carbon nanotubes and graphene; (3) The silicon-based material includes silicon oxide, which includes silicon and oxygen elements, and the atomic ratio of silicon to oxygen is 0 to 2:1, excluding 0:1; (4) The silicon-based material includes silicon oxide, and the general chemical formula of the silicon oxide is SiO. x , where 0 < x ≤ 2.

8. The negative electrode material according to claim 7, characterized in that, The carbon material is amorphous carbon.

9. The negative electrode material according to any one of claims 1 to 6, characterized in that, In negative electrode materials, micropores account for 6% to 9% of the total pore volume, while mesopores account for 80% to 90% of the total pore volume.

10. The negative electrode material according to any one of claims 1 to 6, characterized in that, The negative electrode material satisfies at least one of the following characteristics: (1) The mass content of silicon in the negative electrode material is m Si %, 53% ≤ m Si ≤64%; (2) The mass content of oxygen in the negative electrode material is m O %, 35% ≤ m O ≤37%; (3) The mass content of carbon in the negative electrode material is m C %, 1% ≤ m C ≤6%.

11. The negative electrode material according to any one of claims 1 to 6, characterized in that, The negative electrode material satisfies at least one of the following characteristics: (1) The median particle size D of the negative electrode material 50 The size ranges from 1 μm to 10 μm. (2) The specific surface area of ​​the negative electrode material is ≤20m². 2 / g; (3) The compaction density of the negative electrode material is 1.28 g / cm³. 3 ~1.40g / cm 3 ; (4) The true density of the negative electrode material is 2.20 g / cm³. 3 ~2.30g / cm 3 ; (5) The powder conductivity of the negative electrode material under 20kN pressure is 1S / cm to 3S / cm.

12. The negative electrode material according to claim 11, characterized in that, The specific surface area of ​​the negative electrode material is ≤10m² 2 / g.

13. The negative electrode material according to any one of claims 1 to 6, characterized in that, The carbon material forms a carbon layer on the surface of the silicon-based material, and the thickness of the carbon layer is 1 nm to 1000 nm.

14. The negative electrode material according to claim 13, characterized in that, The thickness of the carbon layer is 50 nm to 800 nm.

15. A battery, characterized in that, Includes the negative electrode material as described in any one of claims 1 to 14.

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