Anode material and battery

Abstract

The present application relates to an anode material and a battery. The anode material comprises a silicon-based material, and graphite, wherein the surface of the silicon-based material and / or the surface of the graphite has a carbon material; the anode material is tested by means of Raman area scanning, and 200 Raman spectrum curves are randomly selected from a Raman area scanning spectrogram for analysis, so as to obtain i target spectrum curves in which there is no characteristic peak within a wavelength range of 500 cm-1-520 cm-1, and in the target spectrum curves, there is a first characteristic peak within a wavelength range of 1345 cm-1-1355 cm-1, there is a second characteristic peak within a wavelength range of 1570 cm-1-1610 cm-1, the intensity of the first characteristic peak is IBi, and the intensity of the second characteristic peak is IBi'; and the deviation degree of the surface topography of anode material particles is A, formula (I), where 0<A≤0.1, and 1<i<200. The anode material provided in the present application has a relatively high specific capacity, the rate capability of the anode material after a silicon-graphite composite can be improved, and a prepared anode electrode sheet has a relatively low resistivity.

Description

Anode materials and batteries Technical Field

[0001] This invention relates to the field of negative electrode materials technology, and more particularly to negative electrode materials and batteries. Background Technology

[0002] Lithium-ion batteries possess advantages such as high energy density, long cycle life, low environmental pollution, and no memory effect, making them widely used in electric vehicles and consumer electronics. The anode material is a crucial component of lithium-ion batteries, directly impacting key indicators such as energy density, cycle life, and safety performance. Currently, commercially available lithium-ion batteries primarily utilize graphite-based anode materials, but their theoretical specific capacity is only 372 mAh / g, insufficient to meet the demands of high-energy-density lithium-ion batteries. Silicon-based anode materials, with their high specific capacity, are among the candidate materials for next-generation high-energy-density lithium-ion batteries. However, simply adding silicon as a additive to a graphite system fails to effectively leverage its superior performance. Furthermore, the significant differences in particle surface morphology between silicon and graphite result in low conductivity of the manufactured electrodes, leading to poor rate performance of the batteries.

[0003] Therefore, how to improve the rate performance and conductivity of anode materials while increasing their specific capacity is a technical problem that still needs to be solved. Summary of the Invention

[0004] This application provides a negative electrode material and its preparation method, as well as a battery. The negative electrode material provided by this application has a high specific capacity and can improve the rate performance of the negative electrode material after silicon-based material and graphite composite. The prepared negative electrode sheet has a low resistivity.

[0005] This application provides a negative electrode material, comprising a silicon-based material and graphite, wherein the silicon-based material and / or the graphite have a carbon material on their surface; the negative electrode material is tested using Raman surface scanning, and 200 Raman spectra are randomly selected from the Raman surface scanning spectrum for analysis, obtaining i-th spectra at 500 cm⁻¹. -1 ~520cm -1 The target spectrum curve has no characteristic peaks within the wavelength range, and the target spectrum curve has peaks at 1345 cm⁻¹. -1 ~1355cm -1 The first characteristic peak exists within the wavelength range, at 1570 cm⁻¹. -1 ~1610cm -1 A second characteristic peak exists within the wavelength range, and the intensity of the first characteristic peak is I. Bi The intensity of the second characteristic peak is I Bi The surface morphology deviation of the negative electrode material particles is A. And 0 < A ≤ 0.1, 1 < i < 200. Compared with the prior art, the technical solution of this application has at least the following beneficial effects:

[0006] The negative electrode material particles provided in this application include silicon-based materials and graphite. The surface of the silicon-based materials and / or the graphite has carbon material. Combining graphite with silicon-based materials can leverage the synergistic effect between the silicon-based materials and graphite, improving the specific capacity of the negative electrode material while also enhancing its rate performance and conductivity. Furthermore, this application selects i parts of material with a density of 500 cm⁻¹. -1 ~520cm -1 The target spectrum curve, which has no characteristic peaks within the wavelength range, is at 1345 cm⁻¹. -1 ~1355cm -1 The intensity of the first characteristic peak within the range is I Bi At 1570cm -1 ~1610cm -1 The intensity of the second characteristic peak within the range is I' Bi In the Raman surface scan spectrum, the intensity ratio I of the first characteristic peak to the second characteristic peak is... Bi / I' Bi The degree of defects on the surface of the negative electrode material can be characterized. The higher the consistency of the defect degree, the higher the similarity of the surface morphology of the negative electrode material, that is, the lower the degree of morphology deviation. When the degree of surface defects of the negative electrode material deviates significantly, a thicker solid electrolyte film will form on part of the surface of the negative electrode material particles, consuming more active lithium ions, and the contact resistance between particles will also increase. Therefore, through extensive experiments, this application found that controlling the surface morphology deviation A value of the negative electrode material within the range of 0 to 0.1 results in a lower surface morphology deviation of the negative electrode material because most particles have similar morphologies. This is conducive to the rapid insertion and extraction of active lithium ions, and the particles have a high degree of isotropy. The concentration polarization generated by the negative electrode material particles during the lithium insertion and extraction process is small, the electrolyte wetting ability of the negative electrode material is improved, and the lithium ion diffusion ability of the negative electrode material is also improved. This significantly reduces the lithium deposition phenomenon on the particle surface during charging and discharging, and the prepared negative electrode sheet has high conductivity, further increasing the safety and durability of the electrode sheet. Attached Figure Description

[0007] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0008] Figure 1 is a schematic flowchart of the preparation method of the negative electrode material provided in the embodiment of this application.

[0009] Figure 2 is a schematic diagram of the battery discharge state according to an embodiment of this application.

[0010] Figure 3 shows the Raman spectrum of the negative electrode material prepared in Example 1.

[0011] Figure 4 shows the target spectrum curves selected from the Raman spectra of the negative electrode material prepared in Example 1. Detailed Implementation

[0012] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0013] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0014] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0015] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0016] In a first aspect, this application provides a negative electrode material, comprising a silicon-based material and graphite, wherein the surface of the silicon-based material and / or the graphite has a carbon material; the negative electrode material is tested using Raman surface scanning, and 200 Raman spectra are randomly selected from the Raman surface scanning spectrum for analysis, obtaining i-th spectra at 500 cm⁻¹. -1 ~520cm -1 The target spectrum curve has no characteristic peaks within the wavelength range, and the target spectrum curve has peaks at 1345 cm⁻¹. -1 ~1355cm -1 The first characteristic peak exists within the wavelength range, at 1570 cm⁻¹. -1 ~1610cm -1 A second characteristic peak exists within the wavelength range, and the intensity of the first characteristic peak is I. Bi The intensity of the second characteristic peak is I Bi The surface morphology deviation of the negative electrode material particles is A. Furthermore, 0 < A ≤ 0.1, and 1 < i < 200. The negative electrode material provided in this application includes silicon-based materials and graphite. The surface of the silicon-based materials and / or graphite has carbon materials. The composite of graphite and silicon-based materials can leverage the synergistic effect between silicon and graphite, improving the specific capacity of the negative electrode material while also enhancing its rate performance and conductivity. In this application, a characteristic peak refers to a significant peak value appearing within a certain wavelength range, and the peak intensity of a characteristic peak refers to the strongest peak value within the characteristic peak wavelength range.

[0017] Furthermore, the surface morphology deviation A represents the consistency of the degree of defects on the surface of multiple particles of the negative electrode material. This application selects a 500cm... -1 ~520cm -1 The target spectrum curve, which has no characteristic peaks within the wavelength range, is at 1345 cm⁻¹. -1 ~1355cm -1 The intensity of the first characteristic peak within the range is I Bi At 1570cm -1 ~1610cm -1 The intensity of the second characteristic peak within the range is I Bi In the Raman surface scan spectrum, the intensity ratio I of the first characteristic peak to the second characteristic peak is... Bi / I Bi The surface defect degree of the negative electrode material particles can be characterized. The higher the consistency of the defect degree between particles, the higher the similarity of the surface morphology of the negative electrode material particles, that is, the lower the degree of morphology deviation. When the surface defect degree between particles deviates greatly, a thicker solid electrolyte film will form on part of the surface of the negative electrode material particles, consuming more active lithium ions, and the contact resistance between particles will also increase. Therefore, through a large number of experiments, this application found that controlling the surface morphology deviation A value of the negative electrode material within the range of 0 to 0.1, at which point, since most particles have similar morphologies, the surface morphology deviation of the negative electrode material is low, which is conducive to the rapid insertion and extraction of active lithium ions. Moreover, the particles have a high degree of isotropy, the concentration polarization generated by the negative electrode material particles during the lithium insertion and extraction process is small, the electrolyte wetting ability of the negative electrode material is improved, the lithium ion diffusion ability of the negative electrode material is also improved, the lithium deposition phenomenon on the particle surface is greatly reduced, the conductivity of the prepared negative electrode sheet is high, and the safety and durability of the electrode sheet are further increased.

[0018] In some implementations, the value of A can specifically be 0.001, 0.003, 0.005, 0.008, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, or 0.1, etc., or other values ​​within the above range, which are not limited here. Understandably, the closer the value of A is to 0, the lower the deviation of the surface morphology of the negative electrode material particles, that is, the higher the particle morphology similarity. However, since the morphology of particles is rarely completely identical during actual preparation, it is difficult to achieve a value of 0. This application controls the A value within the aforementioned range, ensuring the surface morphology deviation of the negative electrode material particles is within a suitable range. Most negative electrode material particles exhibit similar morphologies, which is beneficial for the rapid insertion and extraction of active lithium ions. Furthermore, the high isotropy of the particles results in minimal concentration polarization during lithium insertion and extraction, improved electrolyte wetting ability, and enhanced lithium-ion diffusion capacity of the negative electrode material. This significantly reduces lithium deposition on the particle surface, leading to high conductivity of the negative electrode sheet prepared from the negative electrode material. When the surface morphology deviation A value of the negative electrode material particles exceeds 0.1, the surface morphology of the negative electrode material becomes disordered, hindering the insertion and extraction of active lithium ions. During the charging and discharging process of the battery prepared from the negative electrode material, lithium deposition may occur on the surface of the negative electrode material particles, posing a safety risk. Among these factors, the I value of the graphite before composite formation... D / I G The average value is within 0.1. After graphite is combined with silicon-based materials, I D / I G The peak intensity ratio will deviate to a certain extent, with an average deviation of about 0.48. The surface morphology difference of the negative electrode material particles is evaluated by calculating the relationship between the peak intensity ratio at each position on the surface of the negative electrode material particles and the average deviation of the above deviation.

[0019] In some implementations, the intensities of the first characteristic peak and the second characteristic peak in the i-th target spectrum curve satisfy the following relationship:

[0020] Specifically, the B value can be 0.2, 0.19, 0.15, 0.13, 0.12, 0.1, 0.09, 0.08, 0.07, 0.06, 0.05, 0.03, 0.01, etc., or other values ​​within the above range, which are not limited here. In this application, controlling the B value within the above range indicates that the surface morphology differences between the negative electrode material particles are small, the isomorphism is high, and the electrode resistivity is high. The negative electrode material generates less concentration polarization during lithium insertion / extraction, exhibiting good lithium-ion diffusion capability. When the B value is greater than 0.2, it indicates that the surface morphology of the negative electrode material particles is diverse, the degree of defects varies greatly, the isomorphism is low, and some surfaces of the negative electrode material particles are prone to forming a thick solid electrolyte film, which is not conducive to lithium-ion diffusion and transport during lithium insertion / extraction, and is not conducive to improving the rate performance and capacity of the negative electrode material.

[0021] In some embodiments, the powder compaction density of the negative electrode material under a pressure of 1T is 0.5 g / cm³. 3 ~2.5g / cm 3 Specifically, it can be 0.5g / cm 3 0.7g / cm 3 0.9g / cm 3 1.0g / cm 3 1.2g / cm 3 1.5g / cm 3 1.8g / cm 3 2.0g / cm 3 Or 2.5g / cm 3 Of course, other values ​​within the above range are also possible and are not limited here. Controlling the powder compaction density of the negative electrode material within the above range is beneficial to improving the energy density and rate performance of the negative electrode material.

[0022] In some embodiments, the silicon-based material includes at least one of amorphous silicon, crystalline silicon, silicon oxide, and silicate.

[0023] In some embodiments, the silicon-based material includes silicon oxide, which includes silicon and oxygen elements in an atomic ratio of 0 to 2, excluding 0.

[0024] In some embodiments, the silicon-based material includes silicon oxide, the general chemical formula of which is SiO. xWhere 0 < x ≤ 2, and x can take values ​​of 0.1, 0.3, 0.5, 0.8, 1.0, 1.2, 1.5, 1.8, 1.95, 2, or any value between them. Preferably, 0 < x < 1. The silicon oxide can be a material formed by dispersing silicon particles in SiO2, or it can be a material with tetrahedral structural units, where silicon atoms are located at the center of the tetrahedral structural units, and silicon atoms and / or oxygen atoms are located at the four vertices of the tetrahedral structural units.

[0025] In some embodiments, silicon oxide comprises silicon and oxygen, wherein the atomic ratio of silicon to oxygen is 0 to 2, excluding 0. Specifically, the atomic ratio of silicon to oxygen 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, and 2, etc., and is not limited herein. Preferably, the atomic ratio of silicon to oxygen is 0 to 1, excluding 0.

[0026] In some embodiments, the median particle size of the silicon-based material is 1 nm to 10 μm, specifically 1 nm, 10 nm, 50 nm, 100 nm, 1 μm, 1.8 μm, 2 μm, 2.5 μm, 3 μm, 3.6 μm, 5 μm, 6 μm, 6.5 μm, 7 μm, 7.8 μm, 8.5 μm, 9 μm, 9.8 μm, or 10 μm, etc., and of course, other values ​​within the above range are also possible, without limitation. Specifically, the silicon-based material particles are observed using a field emission scanning electron microscope or a transmission electron microscope, and the particle size of 5-10 silicon-based material particles is directly measured using a scale bar, and the average particle size is taken as the median particle size of the silicon-based material.

[0027] In some embodiments, the silicon-based material further includes a doped metal M, where M is selected from at least one of Li, Mg, Al, Fe, La, Zn, Ti, Cu, and Mn. Understandably, a small amount of the doped metal can be doped into a carbon material or into the silicon-based core. The doped metal can improve the conductivity of the anode material and enhance its structural strength. Preferably, M is Mg and / or Li.

[0028] In some embodiments, the silicon content in the negative electrode material is 1% to 80% by mass. Specifically, the silicon content can be 1%, 2%, 8%, 10%, 12%, 15%, 30%, 50%, 55%, 58%, 60%, 65%, 69%, 70%, or 80%, or other values ​​within the above range, which are not limited here. If the silicon content is too low, for example, less than 1%, its contribution to the specific capacity of the negative electrode material is almost zero, failing to improve the specific capacity and thus hindering further improvement in battery energy density. If the silicon content is too high, for example, above 80%, it easily leads to increased volume expansion, making it difficult to improve battery energy density. By selecting the silicon content within the above-mentioned range, it is beneficial to improve the battery energy density.

[0029] In some implementations, silicon-based materials and graphite are dispersed in the form of particles in the negative electrode material.

[0030] In some embodiments, graphite includes at least one of natural graphite, artificial graphite, expanded graphite, and graphite oxide. Graphite is a material with high conductivity, low volume expansion, high initial efficiency, and stable cycle performance. By combining graphite with silicon-based materials, the conductivity of the negative electrode material can be comprehensively improved and expansion reduced.

[0031] In some embodiments, the carbon material includes at least one of amorphous carbon and graphitized carbon. The carbon material can be located on the surface of silicon-based material particles, or on the surface of graphite particles, or it can be formed by secondary granulation and coating of graphite particles and silicon-based material particles; this is not limited here. It should be noted that the graphitized carbon can be partially graphitized carbon material formed during the high-temperature carbonization process of the carbon material, or it can be a small amount of graphite particles not covered by the amorphous carbon material; this is not limited here.

[0032] In some embodiments, a carbon layer is formed on the surface of the silicon-based material and / or the graphite, with the carbon material forming the carbon layer. The thickness of the carbon layer ranges from 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, 1000 nm, etc., and is not limited thereto. Controlling the carbon layer thickness within the above range can increase the conductivity of the negative electrode material, which is beneficial for obtaining a negative electrode material with high specific capacity; and the carbon layer can effectively alleviate the volume expansion of the core, improving the long-cycle performance 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.

[0033] In some embodiments, the carbon content in the negative electrode material is 20% to 99% by mass. Specifically, the carbon content can be 20%, 30%, 40%, 50%, 55%, 58%, 60%, 65%, 69%, 70%, 80%, or 90%, or other values ​​within the aforementioned range. The mass ratio of silicon to carbon in the negative electrode material can be adjusted according to the required specific capacity of the negative electrode material, and is not limited here.

[0034] In some embodiments, the powder conductivity of the negative electrode material is >10 S / cm, specifically it can be 11 S / cm, 12 S / cm, 14 S / cm, 15 S / cm, 16 S / cm, 18 S / cm, 20 S / cm, 25 S / cm, or 40 S / cm, etc., and is not limited here. Controlling the powder conductivity of the negative electrode material within the above range is beneficial to improving the conductivity of the negative electrode material and reducing the resistivity of the negative electrode sheet.

[0035] In some embodiments, the median particle size D of the negative electrode material 50 The median particle size of the anode material ranges from 2μm to 20μm, specifically including 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 5μm, 6μm, 8μm, 9μm, 10μm, 12μm, 15μm, 16μm, 18μm, or 20μm, etc., without limitation. Controlling the median particle size of the anode material within this range is beneficial for shortening the lithium-ion migration path, improving lithium-ion migration efficiency, promoting lithium-ion diffusion within the particles, and improving the rate performance of the anode material. It should be noted that D50 represents the particle size corresponding to a cumulative particle size distribution percentage of 50%.

[0036] In some embodiments, the tap density of the negative electrode material is 1.0 g / cm³. 3 ~5.0g / cm 3 The tap density of the negative electrode material can specifically be 1.0 g / cm³. 3 1.05g / cm 3 1.1g / cm 3 1.13 g / cm 3 1.18 g / cm 3 1.2g / cm 3 1.25g / cm 3 1.3g / cm 3 1.5g / cm 3 1.8g / cm 3 2.0g / cm 3 2.5g / cm 3 Or 5.0g / cm 3 Etc., etc., are not limited here. Controlling the tap density of the negative electrode material within the above range is beneficial to improving the energy density and rate performance of the negative electrode material.

[0037] Secondly, this application provides a negative electrode material, which includes a first particle and a second particle, wherein the first particle contains a silicon-based material, the second particle contains graphite, and the surface of the first particle has a carbon material.

[0038] The negative electrode material was subjected to Raman surface scanning spectroscopy, and 200 Raman spectra were randomly selected from the Raman surface scanning spectrum for analysis. The results of the i-th spectrum at 500 cm⁻¹ were obtained. -1 ~520cm -1 The target spectrum curve has no characteristic peaks within the wavelength range, and the target spectrum curve has peaks at 1345 cm⁻¹. -1 ~1355cm -1 The first characteristic peak exists within the wavelength range, at 1570 cm⁻¹. -1 ~1610cm -1 A second characteristic peak exists within the wavelength range, and the intensity of the first characteristic peak is I. Bi The intensity of the second characteristic peak is I Bi ';

[0039] The surface morphology deviation of the negative electrode material is A. Furthermore, 0 < A ≤ 0.1, 1 < i < 200. The negative electrode material provided in this application includes silicon-based materials and graphite. The surface of the silicon-based material and / or the graphite has carbon material. The composite of graphite and silicon-based materials can leverage the synergistic effect between silicon and graphite, improving the specific capacity of the negative electrode material while also enhancing its rate performance and conductivity. In this application, a characteristic peak refers to a significant peak value appearing within a certain wavelength range, and the peak intensity of a characteristic peak refers to the strongest peak value within the characteristic peak wavelength range.

[0040] Furthermore, the surface morphology deviation A represents the consistency of the degree of defects on the surface of multiple particles of the negative electrode material. This application selects a 500cm... -1 ~520cm -1 The target spectrum curve, which has no characteristic peaks within the wavelength range, is at 1345 cm⁻¹. -1 ~1355cm -1 The intensity of the first characteristic peak within the range is I Bi At 1570cm -1 ~1610cm -1 The intensity of the second characteristic peak within the range is I Bi In the Raman surface scan spectrum, the intensity ratio I of the first characteristic peak to the second characteristic peak is... Bi / I BiThe surface defect degree of the negative electrode material particles can be characterized. The higher the consistency of the defect degree between particles, the higher the similarity of the surface morphology of the negative electrode material particles, that is, the lower the degree of morphology deviation. When the surface defect degree between particles deviates greatly, a thicker solid electrolyte film will form on part of the surface of the negative electrode material particles, consuming more active lithium ions, and the contact resistance between particles will also increase. Therefore, through a large number of experiments, this application found that controlling the surface morphology deviation A value of the negative electrode material within the range of 0 to 0.1, at which point, since most particles have similar morphologies, the surface morphology deviation of the negative electrode material is low, which is conducive to the rapid insertion and extraction of active lithium ions. Moreover, the particles have a high degree of isotropy, the concentration polarization generated by the negative electrode material particles during the lithium insertion and extraction process is small, the electrolyte wetting ability of the negative electrode material is improved, the lithium ion diffusion ability of the negative electrode material is also improved, the lithium deposition phenomenon on the particle surface is greatly reduced, the conductivity of the prepared negative electrode sheet is high, and the safety and durability of the electrode sheet are further increased.

[0041] In some implementations, the value of A can specifically be 0.001, 0.003, 0.005, 0.008, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, or 0.1, etc., or other values ​​within the above range, which are not limited here. Understandably, the closer the value of A is to 0, the lower the deviation of the surface morphology of the negative electrode material particles, that is, the higher the particle morphology similarity. However, since the morphology of particles is rarely completely identical during actual preparation, it is difficult to achieve a value of 0. This application controls the A value within the aforementioned range, ensuring the surface morphology deviation of the negative electrode material particles is within a suitable range. Most negative electrode material particles exhibit similar morphologies, which is beneficial for the rapid insertion and extraction of active lithium ions. Furthermore, the high isotropy of the particles results in minimal concentration polarization during lithium insertion and extraction, improved electrolyte wetting ability, and enhanced lithium-ion diffusion capacity of the negative electrode material. This significantly reduces lithium deposition on the particle surface, leading to high conductivity of the negative electrode sheet prepared from the negative electrode material. When the surface morphology deviation A value of the negative electrode material particles exceeds 0.1, the surface morphology of the negative electrode material becomes disordered, hindering the insertion and extraction of active lithium ions. During the charging and discharging process of the battery prepared from the negative electrode material, lithium deposition may occur on the surface of the negative electrode material particles, posing a safety risk. Among these factors, the I value of the graphite before composite formation... D / I G The average value is within 0.1. After graphite is combined with silicon-based materials, I D / I G The peak intensity ratio will deviate to a certain extent, with an average deviation of about 0.48. The surface morphology difference of the negative electrode material particles is evaluated by calculating the relationship between the peak intensity ratio at each position on the surface of the negative electrode material particles and the average deviation of the above deviation.

[0042] In some implementations, the intensities of the first characteristic peak and the second characteristic peak in the i-th target spectrum curve satisfy the following relationship:

[0043] Specifically, the B value can be 0.2, 0.19, 0.15, 0.13, 0.12, 0.1, 0.09, 0.08, 0.07, 0.06, 0.05, 0.03, 0.01, etc., or other values ​​within the above range, which are not limited here. In this application, controlling the B value within the above range indicates that the surface morphology differences between the negative electrode material particles are small, the isomorphism is high, and the electrode resistivity is high. The negative electrode material generates less concentration polarization during lithium insertion / extraction, exhibiting good lithium-ion diffusion capability. When the B value is greater than 0.2, it indicates that the surface morphology of the negative electrode material particles is diverse, the degree of defects varies greatly, the isomorphism is low, and some surfaces of the negative electrode material particles are prone to forming a thick solid electrolyte film, which is not conducive to lithium-ion diffusion and transport during lithium insertion / extraction, and is not conducive to improving the rate performance and capacity of the negative electrode material.

[0044] In some embodiments, the powder compaction density of the negative electrode material under a pressure of 1T is 0.5 g / cm³. 3 ~2.5g / cm 3 Specifically, it can be 0.5g / cm 3 0.7g / cm 3 0.9g / cm 3 1.0g / cm 3 1.2g / cm 3 1.5g / cm 3 1.8g / cm 3 2.0g / cm 3 Or 2.5g / cm 3 Of course, other values ​​within the above range are also possible and are not limited here. Controlling the powder compaction density of the negative electrode material within the above range is beneficial to improving the energy density and rate performance of the negative electrode material.

[0045] In some embodiments, the silicon-based material includes at least one of amorphous silicon, crystalline silicon, silicon oxide, and silicate.

[0046] In some embodiments, the silicon-based material includes silicon oxide, which includes silicon and oxygen elements in an atomic ratio of 0 to 2, excluding 0.

[0047] In some embodiments, the silicon-based material includes silicon oxide, the general chemical formula of which is SiO. xWhere 0 < x ≤ 2, and x can take values ​​of 0.1, 0.3, 0.5, 0.8, 1.0, 1.2, 1.5, 1.8, 1.95, 2, or any value between them. Preferably, 0 < x < 1. The silicon oxide can be a material formed by dispersing silicon particles in SiO2, or it can be a material with tetrahedral structural units, where silicon atoms are located at the center of the tetrahedral structural units, and silicon atoms and / or oxygen atoms are located at the four vertices of the tetrahedral structural units.

[0048] In some embodiments, silicon oxide comprises silicon and oxygen, wherein the atomic ratio of silicon to oxygen is 0 to 2, excluding 0. Specifically, the atomic ratio of silicon to oxygen 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, and 2, etc., and is not limited herein. Preferably, the atomic ratio of silicon to oxygen is 0 to 1, excluding 0.

[0049] In some embodiments, the median particle size of the silicon-based material is 1 nm to 10 μm, specifically 1 nm, 10 nm, 50 nm, 100 nm, 1 μm, 1.8 μm, 2 μm, 2.5 μm, 3 μm, 3.6 μm, 5 μm, 6 μm, 6.5 μm, 7 μm, 7.8 μm, 8.5 μm, 9 μm, 9.8 μm, or 10 μm, etc., and of course, other values ​​within the above range are also possible, without limitation. Specifically, the silicon-based material particles are observed using a field emission scanning electron microscope or a transmission electron microscope, and the particle size of 5-10 silicon-based material particles is directly measured using a scale bar, and the average particle size is taken as the median particle size of the silicon-based material.

[0050] In some embodiments, the silicon-based material further includes a doped metal M, where M is selected from at least one of Li, Mg, Al, Fe, La, Zn, Ti, Cu, and Mn. Understandably, a small amount of the doped metal can be doped into a carbon material or into the silicon-based core. The doped metal can improve the conductivity of the anode material and enhance its structural strength. Preferably, M is Mg and / or Li.

[0051] In some embodiments, the silicon content in the negative electrode material is 1% to 80% by mass. Specifically, the silicon content can be 1%, 2%, 8%, 10%, 12%, 15%, 30%, 50%, 55%, 58%, 60%, 65%, 69%, 70%, or 80%, or other values ​​within the above range, which are not limited here. If the silicon content is too low, for example, less than 1%, its contribution to the specific capacity of the negative electrode material is almost zero, failing to improve the specific capacity and thus hindering further improvement in battery energy density. If the silicon content is too high, for example, above 80%, it easily leads to increased volume expansion, making it difficult to improve battery energy density. By selecting the silicon content within the above-mentioned range, it is beneficial to improve the battery energy density.

[0052] In some implementations, a plurality of first particles and a plurality of second particles are dispersed among each other.

[0053] In some implementations, silicon-based materials and graphite are dispersed in the form of particles in the negative electrode material.

[0054] In some embodiments, graphite includes at least one of natural graphite, artificial graphite, expanded graphite, and graphite oxide. Graphite is a material with high conductivity, low volume expansion, high initial efficiency, and stable cycle performance. By combining graphite with silicon-based materials, the conductivity of the negative electrode material can be comprehensively improved and expansion reduced.

[0055] In some embodiments, the carbon material includes at least one of amorphous carbon and graphitized carbon, forming a carbon layer on the surface of the silicon-based material. The carbon material may also be located on the surface of graphite particles, or the graphite particles may be secondary-granulated and coated with silicon-based material particles to form secondary particles; this is not limited here. It should be noted that the graphitized carbon may be partially graphitized carbon material formed during the high-temperature carbonization process of the carbon material, or it may be a small amount of graphite particles not covered by the amorphous carbon material; this is not limited here.

[0056] In some embodiments, the thickness of the carbon layer ranges from 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, 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; furthermore, the carbon layer can effectively alleviate the volume expansion of the core 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.

[0057] In some embodiments, the carbon content in the negative electrode material is 20% to 99% by mass. Specifically, the carbon content can be 20%, 30%, 40%, 50%, 55%, 58%, 60%, 65%, 69%, 70%, 80%, or 90%, or other values ​​within the aforementioned range. The mass ratio of silicon to carbon in the negative electrode material can be adjusted according to the required specific capacity of the negative electrode material, and is not limited here.

[0058] In some embodiments, the powder conductivity of the negative electrode material is >10 S / cm, specifically it can be 11 S / cm, 12 S / cm, 14 S / cm, 15 S / cm, 16 S / cm, 18 S / cm, 20 S / cm, 25 S / cm, or 40 S / cm, etc., and is not limited here. Controlling the powder conductivity of the negative electrode material within the above range is beneficial to improving the conductivity of the negative electrode material and reducing the resistivity of the negative electrode sheet.

[0059] In some embodiments, the median particle size D of the negative electrode material 50 The median particle size of the anode material ranges from 2μm to 20μm, specifically including 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 5μm, 6μm, 8μm, 9μm, 10μm, 12μm, 15μm, 16μm, 18μm, or 20μm, etc., without limitation. Controlling the median particle size of the anode material within this range is beneficial for shortening the lithium-ion migration path, improving lithium-ion migration efficiency, promoting lithium-ion diffusion within the particles, and improving the rate performance of the anode material. It should be noted that D50 represents the particle size corresponding to a cumulative particle size distribution percentage of 50%.

[0060] In some embodiments, the tap density of the negative electrode material is 1.0 g / cm³. 3 ~5.0g / cm 3 The tap density of the negative electrode material can specifically be 1.0 g / cm³. 3 1.05g / cm 3 1.1g / cm 3 1.13 g / cm 3 1.18 g / cm 3 1.2g / cm 3 1.25g / cm 3 1.3g / cm 3 1.5g / cm 3 1.8g / cm 3 2.0g / cm 3 2.5g / cm 3 Or 5.0g / cm 3Etc., etc., are not limited here. Controlling the tap density of the negative electrode material within the above range is beneficial to improving the energy density and rate performance of the negative electrode material.

[0061] Thirdly, this application provides a method for preparing a negative electrode material, as shown in Figure 1, including the following steps:

[0062] Step S100: Graphite particles are subjected to plasma surface modification treatment using a non-polymerizable gas to obtain modified graphite.

[0063] Step S200: The dispersion of silicon-based material is mixed with modified graphite, and solid-liquid separation is performed to obtain a mixture of silicon-based material and modified graphite.

[0064] Step S300: The mixture is subjected to carbon coating treatment to obtain the negative electrode material.

[0065] The method for preparing the negative electrode material provided in this application involves firstly, using a non-polymerizable gas to perform plasma surface modification treatment on graphite particles, which can improve the defect degree of graphite and increase the conductivity of the negative electrode material; then, mixing the dispersion of silicon-based material with the modified graphite can achieve uniform mixing of silicon-based material and graphite, reducing the segregation phenomenon of silicon-based material; finally, carbon coating the mixture of the above two can effectively reduce the defect degree of graphite surface, adjust the surface morphology deviation of the negative electrode material particles, and control the surface morphology deviation A value of the negative electrode material particles within the range of 0 to 0.1. At this time, since most particles have similar morphologies, the surface morphology deviation between negative electrode material particles is low, which is conducive to the rapid insertion and extraction of active lithium ions. Moreover, the particles have a high degree of isotropy, and the concentration polarization generated by the negative electrode material particles during the lithium insertion and extraction process is small, improving the electrolyte wetting ability and the lithium ion diffusion ability of the negative electrode material. This significantly reduces the lithium deposition phenomenon on the particle surface, resulting in a negative electrode sheet with high conductivity, further increasing the safety and durability of the electrode sheet. In addition, the anode material uses an active material formed by combining graphite and silicon-based materials, which can give full play to the synergistic effect between silicon and graphite, improve the specific capacity of the anode material, and enhance the rate performance and conductivity of the anode material.

[0066] The following is a detailed introduction to this plan:

[0067] Step S100: Graphite particles are subjected to plasma surface modification treatment using a non-polymerizable gas to obtain modified graphite.

[0068] In some embodiments, the median particle size of the graphite particles is 6 μm to 20 μm, specifically 6 μm, 7 μm, 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, or 20 μm, etc., and is not limited here. Controlling the particle size of graphite is beneficial for controlling the particle size of the final anode material and improving the particle structure stability of the anode material.

[0069] In some embodiments, graphite includes at least one of natural graphite, artificial graphite, expanded graphite, and graphite oxide. Graphite is a material with high conductivity, low volume expansion, high initial efficiency, and stable cycle performance. By combining graphite with silicon-based materials, the conductivity of the negative electrode material can be comprehensively improved and expansion reduced.

[0070] In some embodiments, the modification process includes placing graphite in a low-temperature plasma device, evacuating it to a pressure less than 0.2 MPa, and then introducing a non-polymerizable gas to perform plasma modification treatment on the surface of the graphite particles.

[0071] Understandably, placing graphite particles in a plasma device for modification treatment results in higher surface morphology regularity and better consistency, reducing the occurrence of disordered morphology. This helps to uniformly deposit carbon materials on the surface of graphite particles in subsequent processes. It also helps to control the deposition rate and thickness of carbon materials on the surfaces of graphite and silicon-based materials, further adjusting the surface morphology consistency between anode material particles, and further improving the conductivity of the electrode sheet prepared from the anode material.

[0072] In some embodiments, the plasma modification treatment temperature is 30℃ to 180℃, specifically 30℃, 50℃, 80℃, 90℃, 100℃, 110℃, 130℃, 150℃, or 180℃, or other values ​​within the above range, which are not limited here. Selecting this range facilitates modification. If the temperature is too low, surface morphology modification cannot be achieved; if the temperature is too high, over-modification may occur, failing to achieve the desired surface modification effect.

[0073] Preferably, the temperature for plasma modification treatment is 80℃~150℃.

[0074] In some embodiments, the pressure range for plasma modification treatment is 50 Pa to 150 Pa, specifically 50 Pa, 60 Pa, 70 Pa, 80 Pa, 90 Pa, 100 Pa, 120 Pa, 130 Pa, 140 Pa, or 150 Pa, etc., or other values ​​within the above range, which are not limited here. Selecting this range facilitates the achievement of modification. If the pressure is too low, modification cannot be achieved; if the pressure is too high, the modification depth may be too deep, failing to achieve the desired modification effect.

[0075] In some embodiments, the plasma modification treatment time is 10s to 150s, specifically 10s, 30s, 50s, 70s, 80s, 100s, 120s, 130s, 140s, or 150s, etc., or other values ​​within the above range, which are not limited here. Selecting the above range facilitates modification. If the time is too short, the modification effect is poor, and the surface morphology cannot be adjusted. If the time is too long, it is easy to cause over-modification, failing to achieve the expected morphology adjustment, resulting in a non-uniform anode material, further affecting the rate performance of the material.

[0076] In some embodiments, the non-polymerizable gas includes at least one of hydrogen, argon, helium, nitrogen, krypton, and neon. By selecting the above-mentioned non-polymerizable gases, on the one hand, the carrier gas can be prevented from reacting during the modification process, and on the other hand, the reaction of the deposited gas can be ensured to proceed according to the expected reaction, thereby promoting the smooth progress of the modification process as designed.

[0077] In this application, the surface modification treatment of graphite particles by non-polymerizing gas can adjust the degree of surface defects of graphite, thereby improving the ability of carbon materials to adhere more uniformly to the surface of graphite particles or the surface of graphite and silicon-based composite particles during the subsequent carbon coating process. This makes the composite of graphite particles with silicon-based materials and carbon materials more uniform and sufficient, and can thus adjust the degree of defects of carbon materials on the surface of anode material particles.

[0078] In step S200, the dispersion of silicon-based material is mixed with modified graphite, and solid-liquid separation is performed to obtain a mixture of silicon-based material and modified graphite.

[0079] In some embodiments, the silicon-based material includes at least one of amorphous silicon, crystalline silicon, silicon oxide, and silicate.

[0080] In some embodiments, the silicon-based material includes silicon oxide, which includes silicon and oxygen elements in an atomic ratio of 0 to 2, excluding 0.

[0081] In some embodiments, the silicon-based material includes silicon oxide, the chemical formula of which is SiO. x Where 0 < x ≤ 2, and x can take values ​​of 0.1, 0.3, 0.5, 0.8, 1.0, 1.2, 1.5, 1.8, 1.95, 2, or any value between them. Preferably, 0 < x < 1. The silicon oxide can be a material formed by dispersing silicon particles in SiO2, or it can be a material with tetrahedral structural units, where silicon atoms are located at the center of the tetrahedral structural units, and silicon atoms and / or oxygen atoms are located at the four vertices of the tetrahedral structural units.

[0082] In some embodiments, the silicon oxide comprises silicon and oxygen, with an atomic ratio of silicon to oxygen of 0 to 2, excluding 0. The atomic ratio of silicon to oxygen can specifically 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, and 2, etc., and is not limited thereto. Preferably, the atomic ratio of silicon to oxygen is 0 to 1, excluding 0.

[0083] In some embodiments, the silicon-based material further includes a doped metal M, where M is selected from at least one of Li, Mg, Al, Fe, La, Zn, Ti, Cu, and Mn. Understandably, a small amount of the doped metal can be doped into a carbon material or into the silicon-based core. The doped metal can improve the conductivity of the anode material and enhance its structural strength. Preferably, M is Mg and / or Li.

[0084] In some embodiments, the median particle size of the silicon-based material is 2 μm to 15 μm, specifically 2 μm, 3 μm, 5 μm, 6 μm, 8.5 μm, 9 μm, 9.8 μm, 10 μm, 12 μm, 13.5 μm, or 15 μm, etc., and of course, other values ​​within the above range are also possible, and are not limited here. In this application, controlling the particle size of the silicon-based material within the above range is beneficial to the uniform composite of the silicon-based material and graphite particles, reducing the excessive consumption of active lithium ions caused by a large number of small-diameter silicon-based materials, and improving the uniformity of the composite particles.

[0085] In some embodiments, the solvent in the dispersion includes at least one selected from deionized water, ethanol, propanol, isopropanol, dimethylformamide, and acetone. These selected solvents have suitable surface tension to uniformly disperse the mixed particles and prevent particle aggregation; furthermore, these solvents are readily available, have low environmental impact, and are recyclable.

[0086] In some embodiments, the silicon-based material is uniformly dispersed in a solvent, and then modified graphite particles are gradually added. After stirring and dispersing for 1 to 4 hours, solid-liquid separation is performed to obtain a mixture of particles. Understandably, using a liquid-phase dispersion method, first dispersing the silicon-based material in a solvent, and then adding the modified graphite particles, can reduce the agglomeration of the silicon-based material and effectively improve the dispersion uniformity of graphite and silicon-based materials.

[0087] In some embodiments, the silicon-based material and graphite in the mixture are dispersed in the form of particles.

[0088] In some embodiments, the mass content of silicon-based material in the mixture is 1% to 80%, and the mass content of graphite is 20% to 99%. The specific mass content of silicon-based material can be 1%, 2%, 8%, 10%, 12%, 15%, 30%, 50%, 55%, 58%, 60%, 65%, 69%, 70%, or 80%, or other values ​​within the above range, which are not limited here. The specific mass content of graphite can be 20%, 30%, 40%, 50%, 55%, 58%, 60%, 65%, 69%, 70%, 80%, or 90%, or other values ​​within the above range, which are also possible. The mass ratio of silicon-based material to graphite in the mixture can be adjusted according to the specific capacity required for the negative electrode material, which is not limited here.

[0089] In some implementations, the solid-liquid separation method includes one or a combination of two or more of the following: centrifugation, filtration, stirring and drying, evaporation, mechanical sieving, and chemical precipitation.

[0090] Step S300: The mixture is subjected to carbon coating treatment to obtain the negative electrode material.

[0091] In some embodiments, the carbon coating process includes one or more combinations of liquid phase coating, solid phase coating, and gas phase coating.

[0092] In some embodiments, the carbon coating process specifically includes uniformly mixing the carbon source and the mixture particles, followed by heat treatment.

[0093] 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.

[0094] In some embodiments, the heat treatment method includes at least one of roller kiln, pusher kiln, box furnace, tube furnace, CVD furnace, and fluidized bed.

[0095] In some embodiments, the carbon source includes at least one of pitch-based, coal-based, petroleum-based, biomass, alkanes, alkenes, alkynes, polyesters, ethers, phenols, sucrose, and citric acid.

[0096] In some embodiments, the carbon coating treatment temperature is 300℃ to 1000℃, specifically 300℃, 500℃, 600℃, 700℃, 800℃, 900℃, 950℃, or 1000℃, or other values ​​within the above range, which are not limited here. If the carbon coating treatment temperature is too low, the degree of carbon source decomposition is low, the organic content of the remaining carbon layer is high, and the hydrophilicity is weak, which is not conducive to the processing of the material in later applications; if the carbon coating treatment temperature is too high, it will affect the crystal structure change of the material core and change the electrochemical performance of the entire material.

[0097] In some embodiments, the carbon coating treatment time is 2h to 10h, specifically 2h, 4h, 5h, 6h, 8h, 9h or 10h, etc., and of course other values ​​within the above range are also possible, which are not limited here.

[0098] In some embodiments, the carbon coating process is carried out in an oxygen-free atmosphere.

[0099] In some embodiments, the non-oxygen atmosphere includes at least one of vacuum, hydrogen, argon, helium, nitrogen, krypton, and neon.

[0100] In some embodiments, the carbon material formed after heat treatment forms a carbon layer on the surface of the silicon-based material and / or graphite. The carbon material can be located on the surface of the silicon-based material particles, or on the surface of the graphite particles, or the graphite particles and silicon-based material particles can be secondary granulated and coated to form secondary particles, which is not limited here.

[0101] 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, 1000 nm, etc., and is not limited herein. Controlling the carbon layer thickness within the above range can increase the conductivity of the negative electrode material, which is beneficial for obtaining a negative electrode material with high specific capacity; furthermore, the carbon layer can effectively alleviate the volume expansion of the core and improve the long-cycle performance 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.

[0102] In some embodiments, the carbon coating process includes sieving, specifically using a 200-400 mesh sieve. The primary function of sieving is to remove foreign matter, eliminating the risk of its introduction, and secondly, to control the particle size distribution of the resulting negative electrode material. Additionally, the carbon coating process may cause some particles to agglomerate; sieving can remove these agglomerated particles.

[0103] Fourthly, one embodiment of this application provides a battery (such as a lithium-ion battery, sodium-ion battery, etc.) including a casing, an electrode assembly, and an electrolyte / electrolyte. Both the electrode assembly and the electrolyte / electrolyte are located within the casing.

[0104] The outer casing can be a packaging bag sealed with an encapsulating film (such as aluminum-plastic film), for example, if the battery is a pouch battery. In other embodiments, the battery can also be a steel-cased battery, an aluminum-cased battery, etc.

[0105] Figure 2 shows a schematic diagram of the battery in a discharged state, i.e., during operation. As shown in Figure 3, the electrode assembly includes a positive electrode 110, a negative electrode 120, and a separator 130, with the separator disposed between the positive and negative electrode sheets. The electrode assembly can be a stacked structure, formed by alternating layers of the positive electrode, separator, and negative electrode. In other embodiments, the electrode assembly can also be a wound structure, formed by winding the positive electrode, separator, and negative electrode after they have been stacked in sequence.

[0106] Positive electrode film

[0107] The positive electrode 110 includes a positive current collector 111 and a positive active layer 112 disposed on at least one surface of the positive current collector. The positive current collector can be 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 and polymer substrate. The positive active layer contains a positive active material, which includes compounds capable of reversibly intercalating and deintercalating metal ions. In some embodiments, the positive 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.

[0108] 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), lithium manganese oxide (LiMn2O4), and lithium nickel manganese oxide (LiNi). 0.5 Mn 1.5 At least one of lithium iron phosphate (LiFePO4) or lithium iron phosphate (LiFePO4).

[0109] negative electrode sheet

[0110] The negative electrode 120 includes a negative electrode current collector 121 and a negative electrode active material layer 122 disposed on at least one surface of the negative electrode current collector. The negative electrode current collector can be at least one of copper foil, nickel foil, stainless steel foil, titanium foil, or carbon-based current collectors, 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 includes a negative electrode material.

[0111] During battery operation, i.e. when the battery is in a discharge state, metal ions 140 (e.g., lithium ions) in the negative electrode are released from the lattice of the negative electrode material, pass through the electrolyte / electrolyte through the separator 130, and are embedded in the lattice of the positive electrode material.

[0112] Conversely, when the battery is charged by applying an external circuit, the oxidation of the positive electrode material causes metal ions (such as lithium ions) in the positive electrode to be released from the lattice of the positive electrode material, pass through the electrolyte / electrolyte through the separator, and move to the negative electrode; at the same time, the negative electrode material undergoes a reduction reaction, causing metal ions to be embedded in the lattice of the negative electrode material.

[0113] As metal ions move back and forth between the positive and negative electrodes, the battery can achieve the discharge and charge process in thousands of cycles.

[0114] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0115] Example

[0116] Example 1

[0117] (1) Take 300g of artificial graphite particles (D50=8μm) and place them in the material chamber of the low-temperature plasma equipment. Evacuate the chamber to an internal pressure of 0.05MPa, raise the temperature to 140℃, and then apply the plasma at a rate of 10cm. 3 Hydrogen gas was introduced at a rate of / min, and after 50s of treatment, the temperature was lowered to 25℃ to obtain modified graphite particles.

[0118] (2) Take 30g of silicon oxide particles (SiO, D50=5μm) and put them into isopropanol solvent. Disperse them at 200rpm for 1h. Then add 250g of modified graphite particles and continue to stir and disperse for 1h. Remove the solvent by centrifuge and then bake them in an oven at 80℃ for 10h to obtain mixed particles of silicon-based materials and modified graphite.

[0119] (3) Take 300g of mixed particles of silicon-based material and modified graphite and 15g of medium-temperature asphalt and place them in a triple-eccentric device. Mix at 300rpm for 30min, then transfer to a graphite crucible and calcine at 800℃ for 4h in a box furnace under a nitrogen atmosphere. Cool to room temperature and discharge. After breaking up the VC, pass it through a 300-mesh sieve to obtain the negative electrode material. The negative electrode material prepared in this embodiment contains silicon oxide particles (SiO) and graphite particles. The surfaces of the silicon oxide particles and graphite particles are respectively covered with uniform carbon layers. By modifying the graphite particles, the growth degree and density of the carbon layer can be controlled, and the morphological differences between the silicon oxide particles and graphite particles can be adjusted. The surface morphology deviation of the prepared negative electrode material is low.

[0120] Figure 3 shows the Raman spectrum of the negative electrode material prepared in Example 1. Figure 4 shows 200 randomly selected spectra from Figure 3, with the 500-520 cm⁻¹ values ​​as the sample size. -1 The Raman spectrum is a compilation of 18 Raman spectra without peaks. Other parameters of the anode material are detailed in Table 1.

[0121] Example 2

[0122] The difference from Example 1 is:

[0123] (1) Take 300g of artificial graphite particles (D50=8μm) and place them in the material chamber of the low-temperature plasma equipment. Evacuate the chamber to an internal pressure of 0.05MPa, raise the temperature to 140℃, and then apply the plasma at a rate of 10cm. 3 Hydrogen gas was introduced at a rate of / min, and after treatment for 30 seconds, the temperature was lowered to 25°C to obtain modified graphite particles. The anode material prepared in this embodiment contains silicon-oxygen particles and graphite particles, and the surfaces of the silicon-oxygen particles and graphite particles are respectively covered with uniform carbon layers. By modifying the graphite particles, the growth degree and density of the carbon layers can be controlled, and the morphological differences between silicon-oxygen particles and graphite particles can be adjusted, resulting in a low surface morphology deviation of the prepared anode material.

[0124] Other parameters of the negative electrode material are detailed in Table 1.

[0125] Example 3

[0126] The difference from Example 1 is:

[0127] (1) Take 300g of artificial graphite particles (D50=8μm) and place them in the material chamber of the low-temperature plasma equipment. Evacuate the chamber to an internal pressure of 0.05MPa, raise the temperature to 140℃, and then apply the plasma at a rate of 10cm. 3 Hydrogen gas was introduced at a rate of / min, and after treatment for 100s, the temperature was lowered to 25°C to obtain modified graphite particles. The anode material prepared in this embodiment contains silicon-oxygen particles and graphite particles, and the surfaces of the silicon-oxygen particles and graphite particles are respectively covered with uniform carbon layers. By modifying the graphite particles, the growth degree and density of the carbon layers can be controlled, and the morphological differences between silicon-oxygen particles and graphite particles can be adjusted, resulting in a low surface morphology deviation of the prepared anode material.

[0128] Other parameters of the negative electrode material are detailed in Table 1.

[0129] Example 4

[0130] The difference from Example 1 is:

[0131] (1) Take 300g of natural graphite particles (D50=8μm) and place them in the material chamber of the low-temperature plasma equipment. Evacuate the chamber to an internal pressure of 0.05MPa, raise the temperature to 140℃, and then apply the plasma at a 10cm depth. 3Hydrogen gas was introduced at a rate of / min, and after treatment for 50 seconds, the temperature was lowered to 25°C to obtain modified graphite particles. The anode material prepared in this embodiment contains silicon-oxygen particles and graphite particles, and the surfaces of the silicon-oxygen particles and graphite particles are respectively covered with uniform carbon layers. By modifying the graphite particles, the growth degree and density of the carbon layers can be controlled, and the morphological differences between silicon-oxygen particles and graphite particles can be adjusted, resulting in a low surface morphology deviation of the prepared anode material.

[0132] Other parameters of the negative electrode material are detailed in Table 1.

[0133] Example 5

[0134] The difference from Example 1 is:

[0135] (2) 30g of amorphous silicon particles (D50 = 3μm) were added to isopropanol solvent and dispersed at 200rpm for 1h. Then, 250g of modified graphite particles were added and the mixture was stirred and dispersed for another 1h. The solvent was removed by centrifugation, and the mixture was then baked in an oven at 80℃ for 10h to obtain a mixture of silicon-based material and modified graphite particles. The anode material prepared in this embodiment contains silicon-oxygen particles and graphite particles, and the surfaces of the silicon-oxygen particles and graphite particles are respectively covered with uniform carbon layers. By modifying the graphite particles, the growth degree and density of the carbon layer can be controlled, and the morphological differences between the silicon-oxygen particles and graphite particles can be adjusted, resulting in a low surface morphology deviation of the prepared anode material.

[0136] Example 6

[0137] The difference from Example 1 is:

[0138] (2) Take 30g of SiO particles containing lithium silicate (D50 = 5μm), add them to isopropanol solvent, disperse at 200rpm for 1h, then add 250g of modified graphite particles and continue stirring and dispersing for 1h. Remove the solvent by centrifugation, then bake in an oven at 80℃ for 10h to obtain mixed particles of silicon-based material and modified graphite. The anode material prepared in this embodiment contains SiO particles containing lithium silicate and graphite particles. The surfaces of the silicon-oxygen particles and graphite particles are respectively covered with uniform carbon layers. By modifying the graphite particles, the growth degree and density of the carbon layer can be controlled, and the morphological difference between the silicon-oxygen particles and graphite particles can be adjusted, resulting in a low surface morphology deviation of the prepared anode material.

[0139] Example 7

[0140] Unlike Example 1:

[0141] (1) Take 300g of artificial graphite particles (D50=8μm) and place them in the material chamber of the low-temperature plasma equipment. Evacuate the chamber to an internal pressure of 0.05MPa, raise the temperature to 180℃, and then apply the plasma at a rate of 10cm.3 Hydrogen gas was introduced at a rate of / min, and after 10 seconds of treatment, the temperature was lowered to 25°C to obtain modified graphite particles. The anode material prepared in this embodiment comprises silicon-oxygen particles and graphite particles, each with a uniform carbon layer on its surface. By modifying the graphite particles, the growth degree and density of the carbon layer can be controlled, and the morphological differences between the silicon-oxygen particles and graphite particles can be adjusted, resulting in a anode material with low surface morphology deviation.

[0142] Example 8

[0143] The difference from Example 1 is:

[0144] (3) 300g of a mixture of silicon-based material and modified graphite particles was placed in a CVD rotary furnace. After purging with nitrogen for 8 hours, the temperature was raised to 850℃, and acetylene was introduced for 6 hours. The acetylene flow rate was set to 2L / min. The mixture was then cooled to room temperature and discharged. The VC particles were dispersed and passed through a 300-mesh sieve to obtain the negative electrode material. The negative electrode material prepared in this embodiment contains silicon-oxygen particles and graphite particles. The surfaces of the silicon-oxygen particles and graphite particles are covered with uniform carbon layers. By modifying the graphite particles, the growth degree and density of the carbon layers can be controlled, and the morphological differences between the silicon-oxygen particles and graphite particles can be adjusted. The surface morphology deviation of the prepared negative electrode material is relatively low.

[0145] Example 9

[0146] The difference from Example 1 is:

[0147] (1) Take 300g of artificial graphite particles (D50=8μm) and place them in the material chamber of the low-temperature plasma equipment. Evacuate the chamber to an internal pressure of 0.2MPa, raise the temperature to 180℃, and then pressurize the plasma at a depth of 10cm. 3 Hydrogen gas was introduced at a rate of / min, and after treatment for 50 seconds, the temperature was lowered to 25°C to obtain modified graphite particles. The anode material prepared in this embodiment contains silicon-oxygen particles and graphite particles, and the surfaces of the silicon-oxygen particles and graphite particles are respectively covered with uniform carbon layers. By modifying the graphite particles, the growth degree and density of the carbon layers can be controlled, and the morphological differences between silicon-oxygen particles and graphite particles can be adjusted, resulting in a low surface morphology deviation of the prepared anode material.

[0148] Example 10

[0149] Unlike Example 1, the weight of both the silicon oxide particles and the modified graphite particles was adjusted to 140g. The anode material prepared in this example comprises silicon oxide particles and graphite particles, with uniform carbon layers on the surfaces of both particles. By modifying the graphite particles, the growth degree and density of the carbon layers can be controlled, and the morphological differences between the silicon oxide particles and graphite particles can be adjusted, resulting in a lower surface morphology deviation in the prepared anode material.

[0150] Comparative Example 1

[0151] (1) Take 300g of artificial graphite particles (D50=8μm) and place them in the material chamber of the low-temperature plasma equipment. Evacuate the chamber to an internal pressure of 0.05MPa, raise the temperature to 50℃, and then pressurize the plasma at a speed of 10cm. 3 Hydrogen gas was introduced at a rate of / min, and after 300 seconds of treatment, the temperature was lowered to 25°C to obtain modified graphite particles.

[0152] (2) Take 30g of silicon oxide particles (D50=5μm) and put them into isopropanol solvent. Disperse them at 200rpm for 1h. Then add 250g of modified graphite particles and continue to stir and disperse for 1h. Remove the solvent by centrifuge and then bake them in an oven at 80℃ for 10h to obtain mixed particles of silicon-based materials and modified graphite.

[0153] (3) Take 300g of mixed particles of silicon-based material and modified graphite and 15g of medium-temperature asphalt and place them in a triple-eccentric device. Mix at 300rpm for 30min, then transfer to a graphite crucible and place in a box furnace under a nitrogen atmosphere at 200℃ for 2h. After cooling to room temperature, discharge the material. After breaking up the VC, pass it through a 300-mesh sieve to obtain the negative electrode material. In this comparative example, due to excessive graphite modification, on the one hand, the carbon growth of the modified graphite particles and the carbon layer growth of the silicon-oxygen particles are very different. On the other hand, the density of the carbon layer is too high, and the fixed carbon content is insufficient to cover the surface of the modified graphite particles. That is, there is not enough carbon material to repair the surface of the modified graphite, resulting in a large difference in morphology. This leads to a large difference in morphology between silicon-oxygen particles and graphite particles, and the surface morphology deviation of the prepared negative electrode material is high.

[0154] Comparative Example 2

[0155] Unlike Example 1:

[0156] Step (1) is skipped, and step (2) is performed directly. In this comparative example, since the graphite particles were not modified, the adhesion and growth capabilities of the silicon-oxygen particles and graphite particles to the carbon material are different, resulting in a large difference in the morphology of the silicon-oxygen particles and graphite particles, which in turn leads to a high deviation in the surface morphology of the prepared negative electrode material. The parameters of the negative electrode material are detailed in Table 1.

[0157] Comparative Example 3

[0158] Unlike Example 1:

[0159] (1) Take 300g of artificial graphite particles (D50=8μm) and place them in the material chamber of the low-temperature plasma equipment. Evacuate the chamber to an internal pressure of 0.05MPa, raise the temperature to 200℃, and then pressurize the plasma at a depth of 6cm. 3Hydrogen gas was introduced at a rate of / min, and after treatment for 50 seconds, the temperature was lowered to 25°C to obtain modified graphite particles. In this comparative example, due to excessive graphite modification, on the one hand, the carbon growth of the modified graphite particles and the carbon layer growth of the silicon-oxygen particles differed greatly; on the other hand, the carbon layer was too dense, and the fixed carbon content was insufficient to cover the surface of the modified graphite particles. In other words, there was not enough carbon material to repair the surface of the modified graphite, resulting in a large difference in morphology. Consequently, there was a large difference in morphology between the silicon-oxygen particles and the graphite particles, and the surface morphology deviation of the prepared negative electrode material was high.

[0160] Test methods

[0161] (1) Method for testing the median particle size of negative electrode materials:

[0162] The particle size testing method refers to GB / T 19077-2016. It can be conveniently determined using a laser particle size analyzer, such as the Mastersizer 3000 laser particle size analyzer from Malvern Instruments Ltd., UK. The particle size distribution range of the negative electrode material is tested using a Malvern laser particle size analyzer (Mastersizer 3000). The cumulative particle size distribution based on volume is determined using laser diffraction. D05 represents the particle size corresponding to a cumulative particle size distribution percentage of 0.5%, D50 represents the particle size corresponding to a cumulative particle size distribution percentage of 50% (also known as the median particle size), and D80 represents the particle size corresponding to a cumulative particle size distribution percentage of 80%.

[0163] (2) Test method for tap density of negative electrode material:

[0164] Referring to GB / T 5162-2006 / ISO 3953:1993 "Determination of tap density of metal powders", the tap density was tested using a Canta DAT-4-220 tap density analyzer manufactured by Anton Paar (Shanghai) Trading Co., Ltd. The tap density T is the value after 1000 vibrations. The feed weight was 60g, and the unit is g / cm³. 3 .

[0165] (3) Test method for powder compaction density of negative electrode material:

[0166] The powder compaction density was tested according to the method specified in GB / T 24533. A Sansi Zongheng UTM7305 testing instrument was used. The diameter of the test mold was 12.83 mm, and the base area was 1.292 cm². 2 The mass of the test sample was controlled within 1g ± 0.005g, the pressurization and holding time was set to 30s, the depressurization and holding time was set to 10s, and the applied pressure was 1 ton.

[0167] (4) Powder conductivity test of negative electrode material:

[0168] The testing equipment was from Mitsubishi Chemical, Japan, model MCP-PD51. Test parameters included: initial resistance selectable to the order of -3, voltage limit selectable to 10V, sample thickness of 3–5 mm under 20 kN pressure, and pressure settings of 4, 8, 12, 16, and 20 kN. The electrode radius was 0.7 mm, and the sample radius was 10 mm.

[0169] (5) Raman testing of negative electrode materials:

[0170] The Raman spectra of the negative electrode material particles were measured using a Renishaw In Via microconfocal Raman spectrometer (Japan). Two hundred Raman spectra were randomly selected from the Raman surface scans for analysis. The test parameters were: laser wavelength 532 nm, test range 120 μm × 120 μm, and step size 4 μm. The test results were processed using the instrument's built-in software. During data processing, baseline removal was performed on all Raman spectra at all sampling points. Peak finding parameters were adjusted to achieve a peak at 500 cm⁻¹. -1 ~520cm -1 The peaks within the range are the target characteristic peaks, at 1345 cm⁻¹. -1 ~1355cm -1 The peak within the range is the first characteristic peak, at 1570 cm⁻¹. -1 ~1610cm -1 The peaks within the range are the second characteristic peaks. It should be noted that baseline removal is based on the standard that the processed baselines are all near 0; all other processing steps use the software's initial parameters. In the processed spectrum, when 500 cm⁻¹... -1 ~520cm -1 When the peak intensity of the highest peak within the range is less than or equal to 100, it is considered that there is no target characteristic peak.

[0171] (6) Test method for lithium-ion diffusion coefficient of negative electrode material

[0172] Electrode sheets were fabricated using the following composition: negative electrode: carboxymethyl cellulose (2200): styrene-butadiene rubber (104A): carbon black SP: single-walled carbon nanotubes = 95.77: 1.0: 2.0: 1.2: 0.03, and compacted to a density of 1.65 g / cm³. 3 Coin cell half-cells were then assembled, and the lithium-ion diffusion coefficient was tested using the PITT method. The test temperature was 25℃, and the test voltage range was 0.005-1.5V.

[0173] (7) Test method for the mass content of silicon in negative electrode materials

[0174] Silicon content was determined using the ignition method. Testing equipment: 1.0000g–1.2000g (denoted as m0) of sample was weighed into an alumina crucible, accurate to 0.1mg. Two parallel samples were weighed for each sample. The sample was then placed in a muffle furnace for heat treatment. The weight of the heat-treated product was recorded as m1. The silicon content was calculated using the following formula.

[0175] Muffle furnace model: Sigma (Shanghai) High Temperature Electric Furnace Co., Ltd., model: SGM110 / 14A. Heat treatment conditions: Starting from room temperature, raise the temperature to 400℃ in 30 minutes and hold at 400℃ for 60 minutes, then raise it to 900℃ in 60 minutes and hold at 900℃ for 120 minutes, then raise it to 1100℃ in 30 minutes and hold at 1100℃ for 480 minutes, before cooling to room temperature.

[0176] (8) Method for testing the mass content of carbon in negative electrode materials

[0177] Carbon content was tested using an infrared carbon-sulfur analyzer. The instrument was a Bruker G4 ICARUS HF from Germany. The test method involved weighing a certain amount of sample and placing it in a ceramic crucible. Flux was added, and the crucible was placed in a high-frequency furnace where high-purity oxygen was introduced for combustion to generate carbon dioxide. The carbon content in the gas was then directly measured using an infrared detector.

[0178] (9) Method for testing the conductivity of the negative electrode sheet

[0179] A negative electrode slurry was prepared according to the following ratio: sodium carboxymethyl cellulose (MAC350HC): conductive carbon black: styrene-butadiene rubber (451B) = 95.3:1.3:1.5:1.9. An 8µm thick copper foil was used to fabricate the electrode sheet. A rectangular block measuring 38cm × 45cm was taken, and the conductivity of nine points was randomly measured using an electrode resistance meter. The average value was taken as the measured electrode conductivity of the material. The electrode resistance meter was manufactured by Yuaneng Technology, model BER2500.

[0180] (10) Test methods for rate performance:

[0181] The prepared negative electrode material was mixed with sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR) binder, Super-P conductive agent, and KS-6 conductive agent in a mass ratio of 92:2:2:2:2 to form a slurry. The slurry was coated onto copper foil and then vacuum dried and rolled to prepare a negative electrode sheet. The counter electrode was a lithium sheet. A 1 mol / L LiPF6 / ethylene carbonate + dimethyl carbonate + methyl ethyl carbonate (v / v = 1:1:1) electrolyte and a Celgard 2400 separator were assembled into a coin cell.

[0182] The LAND battery testing system from Wuhan Jinno Electronics Co., Ltd. was used for testing. At room temperature, the coin cell battery was discharged to 0.01V at 0.1C, then discharged to 0.005V at 0.01C, and then charged to 1.5V at 0.1C. It was then cycled for two weeks at 0.2C and one week at 1C. The rate performance of the product was evaluated by dividing the 1C charging capacity by the capacity after the first week.

[0183] After the above tests, the negative electrode materials prepared in Examples 1-11 and Comparative Examples 1-3 are sample numbers S1-S11 and R1-R3, respectively; the relevant parameters of the negative electrode materials are shown in Table 1:

[0184] Table 1. Test results of negative electrode material performance

[0185] According to the data in Table 1, the A value of the negative electrode materials prepared in Examples 1 to 8 of this application is controlled within the range of 0 to 0.1. The surface morphology deviation between the negative electrode material particles is low, which is conducive to the rapid insertion and extraction of active lithium ions. The particles have a high degree of isotropy, and the concentration polarization generated by the negative electrode material particles during the lithium insertion and extraction process is small. The electrolyte wetting ability is improved, and the lithium ion diffusion ability of the negative electrode material is also improved, which greatly reduces the phenomenon of lithium deposition on the particle surface. The prepared negative electrode sheet has high conductivity, which further increases the safety and durability of the electrode sheet.

[0186] In Example 9, the plasma modification treatment temperature and pressure were too high during the preparation process of the negative electrode material. The surface modification effect of the graphite particles by non-polymerizing gas was lower than that in Example 1, resulting in the B value of the negative electrode material exceeding the ideal range, increased surface morphology differences of the negative electrode material particles, increased concentration polarization during lithium insertion / extraction, decreased lithium-ion diffusion coefficient of the negative electrode material compared to Example 1, and a slight decrease in electrode conductivity.

[0187] In Comparative Example 1, the carbon coating temperature during the preparation process was too low, causing the A value of the negative electrode material to deviate from the range of 0 to 0.1. The degree of surface defects between the negative electrode material particles deviated significantly, and a thicker solid electrolyte film was formed on part of the surface of the negative electrode material particles, consuming more active lithium ions. The contact resistance between particles also increased, the conductivity of the negative electrode decreased, the expansion rate increased, and the safety and durability of the electrode decreased.

[0188] In Comparative Example 2, the graphite was not modified during the preparation process. The A value of the negative electrode material increased compared to Example 1. The surface defect degree of the negative electrode material particles deviated too much. During the lithium insertion / extraction process of the negative electrode material, a large amount of active lithium ions were consumed. The thickness of the solid electrolyte film on the surface of the negative electrode material particles increased, the contact resistance between particles also increased, the lithium ion diffusion coefficient decreased, and the electrode conductivity also decreased significantly.

[0189] Compared with Example 1, the negative electrode material of Comparative Example 3 had an excessively high plasma modification treatment temperature and insufficient non-polymerizable gas introduction during preparation. The surface defect degree of graphite was increased compared with Example 1, the A value of the negative electrode material increased compared with Example 1, and the surface defect degree of the negative electrode material particles deviated too much. During the lithium insertion and extraction process of the negative electrode material, a large amount of active lithium ions were consumed, the thickness of the solid electrolyte film on the surface of the negative electrode material particles increased, the contact resistance between particles also increased, the lithium ion diffusion coefficient decreased, and the rate performance of the negative electrode sheet also decreased.

[0190] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A negative electrode material, characterized in that, The negative electrode material includes silicon-based material and graphite, wherein the surface of the silicon-based material and / or the graphite has carbon material; The negative electrode material was tested using Raman surface scanning, and 200 Raman spectra were randomly selected from the Raman surface scanning spectrum for analysis. The results of the i-th spectrum at 500 cm⁻¹ were obtained. -1 ~520cm -1 The target spectrum curve has no characteristic peaks within the wavelength range, and the target spectrum curve has peaks at 1345 cm⁻¹. -1 ~1355cm -1 The first characteristic peak exists within the wavelength range, at 1570 cm⁻¹. -1 ~1610cm -1 A second characteristic peak exists within the wavelength range, and the intensity of the first characteristic peak is I. Bi The intensity of the second characteristic peak is I Bi '; 2. The negative electrode material according to claim 1, characterized in that, In the i-th target spectral curve, the intensities of the first characteristic peak and the second characteristic peak satisfy the following relationship:

3. The negative electrode material according to claim 1, characterized in that, The compacted density of the negative electrode material under 1T pressure is 0.5 g / cm³. 3 ~2.5g / cm 3 .

4. The negative electrode material according to any one of claims 1 to 3, characterized in that, The silicon-based material includes at least one of amorphous silicon, crystalline silicon, silicon oxide, and silicates; and / or, the graphite includes at least one of natural graphite, artificial graphite, expanded graphite, and graphite oxide.

5. The negative electrode material according to any one of claims 1 to 3, characterized in that, The silicon-based material includes silicon oxide, which comprises silicon and oxygen elements, wherein the atomic ratio of silicon to oxygen is 0 to 2, excluding 0; or, the silicon-based material includes silicon oxide with the general chemical formula SiO. x , where 0 < x ≤ 2.

6. The negative electrode material according to any one of claims 1 to 3, characterized in that, The carbon material includes at least one of amorphous carbon and graphitized carbon.

7. The negative electrode material according to any one of claims 1 to 3, characterized in that, The negative electrode material includes at least one of the following features (1) to (5): (1) The median particle size of the negative electrode material is 2 μm to 20 μm; (2) The powder conductivity of the negative electrode material is >10 S / cm; (3) The tap density of the negative electrode material is 1.0 g / cm³. 3 ~5.0g / cm 3 ; (4) The mass content of silicon in the negative electrode material is 1%-80%; (5) The carbon content in the negative electrode material is 20%-99% by mass.

8. A negative electrode material, characterized in that, The negative electrode material comprises a first particle and a second particle. The first particle contains a silicon-based material, and the second particle contains graphite. The surface of the first particle has a carbon material. The negative electrode material was subjected to Raman surface scanning spectroscopy, and 200 Raman spectra were randomly selected from the Raman surface scanning spectrum for analysis. The results of the i-th spectrum at 500 cm⁻¹ were obtained. -1 ~520cm -1 The target spectrum curve has no characteristic peaks within the wavelength range, and the target spectrum curve has peaks at 1345 cm⁻¹. -1 ~1355cm -1 The first characteristic peak exists within the wavelength range, at 1570 cm⁻¹. -1 ~1610cm -1 A second characteristic peak exists within the wavelength range, and the intensity of the first characteristic peak is I. Bi The intensity of the second characteristic peak is I Bi '; 9. The negative electrode material according to claim 8, characterized in that, In the i-th target spectral curve, the intensities of the first characteristic peak and the second characteristic peak satisfy the following relationship:

10. The negative electrode material according to claim 8, characterized in that, The compacted density of the negative electrode material under 1T pressure is 0.5 g / cm³. 3 ~2.5g / cm 3 .

11. The negative electrode material according to any one of claims 8 to 10, characterized in that, The negative electrode material satisfies at least one of the following conditions. (1) The silicon-based material includes at least one of amorphous silicon, crystalline silicon, silicon oxide and silicate; (2) The silicon-based material includes silicon oxide, the chemical formula of which is SiO₂. x where 0 < x ≤ 2; (3) The silicon-based material includes silicon oxide, which includes silicon and oxygen elements, with an atomic ratio of silicon to oxygen of 0 to 2, excluding 0.

12. The negative electrode material according to any one of claims 8 to 10, characterized in that, The negative electrode material satisfies at least one of the following conditions. (1) The silicon-based material includes a doped metal M; (2) The silicon-based material includes a doped metal M, wherein M is selected from at least one of Li, Mg, Al, Fe, La, Zn, Ti, Cu and Mn.

13. The negative electrode material according to any one of claims 8 to 10, characterized in that, When the core comprises silicon-based material, the median particle size of the silicon-based material is 1 nm to 10 μm.

14. The negative electrode material according to any one of claims 8 to 10, characterized in that, The negative electrode material satisfies at least one of the following conditions. (1) The mass content of silicon in the negative electrode material is 1%-80%; (2) The carbon content in the negative electrode material is 20%-99% by mass.

15. The negative electrode material according to any one of claims 8 to 10, characterized in that, The first particles and the second particles are dispersed from each other.

16. The negative electrode material according to any one of claims 8 to 10, characterized in that, The graphite includes at least one of natural graphite, artificial graphite, expanded graphite, and graphite oxide.

17. The negative electrode material according to any one of claims 8 to 10, characterized in that, The negative electrode material satisfies at least one of the following conditions. (1) The carbon material includes at least one of amorphous carbon and graphitized carbon; (2) The carbon material forms a carbon layer on the surface of the silicon-based material, and the thickness of the carbon layer ranges from 1 nm to 1000 nm.

18. The negative electrode material according to any one of claims 8 to 10, characterized in that, The negative electrode material satisfies at least one of the following conditions. (1) The median particle size of the negative electrode material is 2 μm to 20 μm; (2) The powder conductivity of the negative electrode material is >10 S / cm; (3) The tap density of the negative electrode material is 1.0 g / cm³. 3 ~5.0g / cm 3 .

19. A battery, characterized in that, The battery comprises the negative electrode material as described in any one of claims 1 to 18.

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