Negative electrode material, preparation method thereof, and battery

Abstract

The application relates to the technical field of batteries, in particular to a negative electrode material and a preparation method thereof and a battery, wherein the negative electrode material comprises a silicon-based active substance and a carbon material, the carbon material is located on at least part of the surface of the silicon-based active substance; the negative electrode material contains hydrogen elements, halogen elements, nitrogen elements and sulfur elements, wherein the mass content of the hydrogen elements is m H , the mass content of the halogen elements is m X , the mass content of the sulfur elements is m S , the mass content of the nitrogen elements is m N , and the following relationships are met: 0.02 <= m X / m H <= 5.00, 0.02 <= m N / m H <= 20.00, and 0.05 <= m S / m H <= 5.00. The technical scheme of the application can effectively inhibit the volume expansion of the negative electrode material by adjusting the content of the hydrogen elements, the nitrogen elements, the sulfur elements and the halogen elements within a proper range, and the capacity, the first coulomb efficiency, the powder conductivity, the cycle performance and the rate performance of the negative electrode material are all improved.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to negative electrode materials and their preparation methods, and batteries. Background Technology

[0002] In recent years, lithium-ion batteries have been widely used in electric vehicles and consumer electronics due to their advantages such as high energy density, high output power, long cycle life, and low environmental pollution. Silicon-based anode materials are one of the most critical materials for high-energy-density lithium-ion batteries. However, existing silicon-based anode materials suffer from problems such as large volume expansion and poor rate capability, which affect their widespread application in lithium batteries.

[0003] To mitigate the volume expansion of silicon materials, silicon is typically combined with carbon materials. However, a simple carbon coating layer is insufficient to effectively isolate the interfacial side reactions between the electrolyte and the anode material. During the preparation of anode slurry using silicon anode materials, severe gas generation occurs, and the volume expansion of the material during charge-discharge cycles also affects the performance of the anode material.

[0004] Therefore, how to improve the contact interface between the negative electrode material and the electrolyte and alleviate the volume expansion of the negative electrode material remains a technical problem that needs to be solved. Summary of the Invention

[0005] This application provides a negative electrode material, its preparation method, and a battery, which helps to improve the stability of the solid-liquid contact interface of the negative electrode material, alleviate the volume expansion of the negative electrode material, and improve the first-efficiency and cycle performance.

[0006] In a first aspect, embodiments of this application provide a negative electrode material, comprising a silicon-based active material and a carbon material, wherein the carbon material is located on at least a portion of the surface of the silicon-based active material;

[0007] The negative electrode material contains hydrogen, halogen, nitrogen, and sulfur, wherein the mass content of hydrogen is m. H The mass content of halogen elements is m X The mass content of sulfur is m S The mass content of nitrogen is m N And satisfy the following relationship: 0.02≤m X / m H ≤5.00, 0.02≤m N / m H ≤20.00, 0.05≤m S / m H ≤5.00.

[0008] In some embodiments, the negative electrode material contains pores.

[0009] In some embodiments, the pore volume distribution curve of the negative electrode material has characteristic peaks in the ranges of 240 Å to 280 Å, 290 Å to 320 Å, 340 Å to 390 Å, and 410 Å to 460 Å.

[0010] In some embodiments, in the negative electrode material, 50 mg / kg ≤ m X ≤1500mg / kg.

[0011] In some embodiments, in the negative electrode material, 100 mg / kg ≤ m N ≤4000mg / kg.

[0012] In some embodiments, in the negative electrode material, 10 mg / kg ≤ m S ≤200mg / kg.

[0013] In some embodiments, the median particle size of the negative electrode material is 2.0 µm to 12.0 µm.

[0014] In some embodiments, the silicon-based active material includes at least one of elemental silicon, silicon oxide, silicon alloy, and silicate.

[0015] In some embodiments, the silicon-based active 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.

[0016] In some embodiments, the general formula for silicon oxide is SiOx, where 0.5 ≤ x < 2.

[0017] In some embodiments, the mass content of metal M in the negative electrode material is 0 wt% to 15 wt%, excluding 0 wt%.

[0018] In some embodiments, the carbon content in the negative electrode material is 0.5wt% to 15wt%.

[0019] In some embodiments, the carbon material includes at least one of graphite, graphene, amorphous carbon, diamond-like carbon, carbon nanotubes, and carbon fibers.

[0020] In some embodiments, a carbon material located on the surface of the silicon-based active material forms a carbon layer, the thickness of which is 20 nm to 1000 nm.

[0021] In some embodiments, the tap density of the negative electrode material is 0.75 g / cm³. 3 ~ 1.35 g / cm 3 .

[0022] In some embodiments, the powder conductivity of the negative electrode material at a pressure of 20 kN is 0.01 S / cm to 100.00 S / cm.

[0023] In some embodiments, the specific surface area of ​​the negative electrode material is 0.50 m². 2 / g ~ 10.00m 2 / g.

[0024] In some embodiments, the water content in the negative electrode material is 0.01 wt% to 0.80 wt%.

[0025] In some embodiments, the pH of the negative electrode material is 6.00 to 12.00.

[0026] Secondly, embodiments of this application also provide a method for preparing a negative electrode material, comprising the following steps:

[0027] A precursor is prepared, wherein the precursor comprises a silicon-based active material and a carbon material;

[0028] In a modified gas source environment, the precursor is surface-modified using plasma-enhanced chemical vapor deposition to obtain a negative electrode material. The modified gas source includes hydrogen, sulfur, nitrogen, and halogen elements; the mass content of hydrogen in the negative electrode material is m. H The mass content of halogen elements is m X The mass content of sulfur is m S The mass content of nitrogen is m N And satisfy the following relationship: 0.02≤m X / m H ≤5.00, 0.02≤m N / m H ≤20.00, 0.05≤m S / m H ≤5.00.

[0029] In some embodiments, the specific steps of preparing the precursor include mixing a carbon material with a silicon-based active material such that at least a portion of the surface of the silicon-based active material is coated with the carbon material.

[0030] In some embodiments, the carbon material includes at least one of graphite, graphene, amorphous carbon, diamond-like carbon, carbon nanotubes, and carbon fibers.

[0031] In some embodiments, the silicon-based active material includes at least one of elemental silicon, silicon oxide, silicon alloy, and silicate.

[0032] In some embodiments, the silicon-based active 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.

[0033] In some embodiments, the preparation method further includes purifying the precursor before surface modification of the precursor using plasma-enhanced chemical vapor deposition.

[0034] In some embodiments, the purification process includes sequentially washing and drying the precursor.

[0035] In some embodiments, the detergent used in the washing process is deionized water.

[0036] In some embodiments, the drying temperature of the drying process is 45°C to 80°C, and the drying time is 3h to 48h.

[0037] In some embodiments, the step of surface modification of the precursor using plasma-enhanced chemical vapor deposition includes: evacuating the vacuum, placing the precursor under the modified vapor source, and performing plasma-enhanced chemical vapor deposition on the precursor under the action of a bias voltage.

[0038] In some implementations, the bias voltage is -500V to 0V, excluding 0V.

[0039] In some embodiments, the pressure of the vacuum is less than 1.0 Torr.

[0040] In some embodiments, the operating pressure of the plasma-enhanced chemical vapor deposition is 500 Pa to 5000 Pa.

[0041] In some embodiments, the deposition temperature of the plasma-enhanced chemical vapor deposition is 200°C to 800°C.

[0042] In some embodiments, the flow rate of the modified gas source is 200 ml / min to 5000 ml / min.

[0043] In some embodiments, the modified gaseous source includes a reaction gas, which may include hydrogen, nitrogen-containing gas, sulfur-containing gas, or halogen source gas.

[0044] In some embodiments, the nitrogen-containing gas includes one or more of nitrogen and ammonia, and / or the sulfur-containing gas includes hydrogen sulfide, and / or the halogen source gas includes one or more of fluorine, chlorine, bromine, iodine, hydrogen bromide, hydrogen iodide, and carbon tetrafluoride.

[0045] In some embodiments, the modified gas source further includes a protective gas, which includes one or more of argon, krypton, nitrogen, neon, and helium.

[0046] In some embodiments, the volume ratio of hydrogen to the protective gas is 1:(0.1-5), the volume ratio of hydrogen to the nitrogen-containing gas is 1:(0-1.2), the volume ratio of hydrogen to the sulfur-containing gas is 1:(0-0.2), and the volume ratio of hydrogen to the halogen source gas is 1:(0-0.05).

[0047] In some embodiments, the negative electrode material contains pores.

[0048] In some embodiments, the pore volume distribution curve of the negative electrode material has characteristic peaks in the ranges of 240 Å to 280 Å, 290 Å to 320 Å, 340 Å to 390 Å, and 410 Å to 460 Å.

[0049] In some embodiments, in the negative electrode material, 50 mg / kg ≤ m X ≤1500mg / kg.

[0050] In some embodiments, in the negative electrode material, 100 mg / kg ≤ m N ≤4000mg / kg.

[0051] In some embodiments, in the negative electrode material, 10 mg / kg ≤ m S ≤200mg / kg.

[0052] In some embodiments, the powder conductivity of the precursor at a pressure of 20 kN is 0.001 S / cm to 0.1 S / cm, and the powder conductivity of the negative electrode material at a pressure of 20 kN is 0.1 S / cm to 100.0 S / cm.

[0053] Thirdly, embodiments of this application also provide a battery, including the negative electrode material as described above, or including the negative electrode material prepared by the preparation method described above.

[0054] Compared with the prior art, the technical solution of this application has at least the following technical effects:

[0055] In the anode material of this application, by exploring the content relationships of hydrogen, nitrogen, sulfur, and halogen elements, the mass ratios of hydrogen to nitrogen, sulfur, and halogen elements in the anode material are controlled within an appropriate range, thereby comprehensively improving the powder conductivity, first-time efficiency, and cycle performance of the material. The anode material of this application contains an appropriate amount of carbon-hydrogen bonds formed by the combination of hydrogen and carbon atoms. An appropriate carbon-hydrogen saturation helps to adjust the hydrophilicity of the material, improve the wettability of the electrolyte to the material, and make the lithium-ion conduction interface between the anode material and the electrolyte smoother. This improves the mass transfer / charge transfer efficiency of the anode material, thereby enhancing its low-temperature performance and powder conductivity. In this application, the negative electrode material also contains appropriate amounts of halogens, nitrogen (N) elements, and sulfur (S) elements. On the one hand, appropriate amounts of halogens, nitrogen (N), and sulfur elements play a role in regulating hydrocarbon saturation: halogens compete with hydrogen (H) for saturation, and their presence occupies H sites, thereby regulating hydrocarbon saturation. Nitrogen and sulfur elements may combine with hydrogen to form local functional groups such as amino groups, which also play a role in regulating hydrocarbon saturation. On the other hand, halogens can also participate in the formation of a more stable solid electrolyte interphase (SEI) film when the electrolyte comes into contact with the negative electrode material, which can enhance the bonding strength between the negative electrode material and the solid electrolyte film. This helps maintain the stability of the solid-liquid interface on the surface of the negative electrode material during cyclic charging and discharging, and can better suppress the expansion of the negative electrode material. Nitrogen and sulfur elements also help to further improve the conductivity of the negative electrode material powder, thereby improving the rate performance of the negative electrode material. When the content ratios of hydrogen, nitrogen, sulfur, and halogen elements in the negative electrode material satisfy the ratios described above in this application, the wetting performance between the negative electrode material and the electrolyte can be improved. This enables solid-liquid regulation during the slurry preparation process, improves slurry dispersibility, reduces slurry sedimentation or agglomeration, suppresses gas generation during slurry preparation, and helps maintain slurry stability. Therefore, the negative electrode material provided in this application possesses advantages such as high initial efficiency, high powder conductivity, high cycle stability, and low volume expansion rate.

[0056] The method for preparing the anode material provided in this application utilizes plasma-enhanced chemical vapor deposition (PECVD) in a modified gas source environment to perform surface modification treatment on precursors containing silicon-based active materials and carbon materials. This method efficiently and uniformly dops multiple elements, achieving high deposition efficiency and controllability. After surface modification, the carbon materials on the surface of the silicon-based active material can combine with hydrogen elements to form carbon-hydrogen bonds, increasing the hydrogen saturation of carbon atoms in the carbon materials. This allows for adjustment of the hydrophilicity of the carbon materials and the wettability of the electrolyte on the anode material, resulting in a smoother lithium-ion conduction interface between the anode material and the electrolyte. This improves the mass / charge transfer efficiency of the anode material, thereby enhancing its low-temperature performance and powder conductivity. The appropriate incorporation of halogens and nitrogen (N) and sulfur (S) elements serves two main purposes. Firstly, it regulates hydrocarbon saturation: halogens compete with hydrogen for saturation, occupying H sites and thus controlling saturation. Nitrogen and sulfur, on the other hand, can combine with hydrogen to form local functional groups like amino groups, further regulating saturation. Secondly, halogens participate in the formation of a more stable solid electrolyte interphase (SEI) film when the electrolyte and anode material are in contact, enhancing the bonding strength between them. This helps maintain the stability of the solid-liquid interface on the anode material surface during cyclic charging and discharging, while also better suppressing anode material expansion. Nitrogen and sulfur elements further improve the conductivity of the anode material powder, thereby enhancing its rate performance. Therefore, modifying the surface of the anode material using a modified gas-phase source can suppress volume expansion and comprehensively improve its electrochemical performance, including initial efficiency, powder conductivity, and cycle performance. Attached Figure Description

[0057] The present application will be further described below with reference to the accompanying drawings and embodiments:

[0058] Figure 1 A schematic flowchart illustrating the preparation method of the negative electrode material provided in the embodiments of this application;

[0059] Figure 2 This is a schematic diagram of the pore volume distribution of the negative electrode material provided in Embodiment 1 of this application. Detailed Implementation

[0060] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0061] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0062] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0063] 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, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0064] Silicon-based anode materials are one of the most critical materials for high-energy-density lithium-ion batteries. However, existing silicon-based anode materials suffer from problems such as large expansion and poor rate performance, which limit their widespread application in lithium-ion batteries.

[0065] In existing related studies, most of the research focuses on the G and D peaks of the carbon layer structure on the surface of silicon-based anode materials in order to improve the surface physicochemical properties of silicon-based anode materials. However, it is still difficult to comprehensively improve the volume expansion and electrochemical performance of silicon-based anode materials.

[0066] To address the aforementioned problems, in a first aspect, this application provides a negative electrode material comprising a silicon-based active material and a carbon material, wherein the carbon material is located on at least a portion of the surface of the silicon-based active material;

[0067] The negative electrode material contains hydrogen, halogens, nitrogen, and sulfur, with the mass content of hydrogen being m. H The mass content of halogen elements is m X (When the negative electrode material contains multiple halogen elements, m) X (The total mass content of various halogen elements), the mass content of sulfur is m. S The mass content of nitrogen is m N And satisfy the following relationship: 0.02≤m X / m H ≤5.00, 0.02≤m N / m H ≤20.00, 0.05≤m S / m H ≤5.00. In anode materials, hydrogen and halogen elements mainly serve as terminal elements of carbon materials, which can modify the interface and structure of anode materials. Nitrogen and sulfur elements are mainly doped into carbon materials, which is beneficial to improving the rate performance, powder conductivity and early cycle stability of anode materials and other electrochemical properties.

[0068] In some implementations, mX / m H The value of can be 0.02, 0.05, 0.1, 0.5, 0.8, 1, 2, 3, 4, or 5, or other values ​​within the above range, without limitation. The presence of an appropriate amount of halogen helps improve the conductivity of the negative electrode material and can participate in the formation of the solid electrolyte interphase (SEI) film on the surface of the negative electrode material, enhancing the stability of the SEI film, thereby suppressing the expansion of the negative electrode material and improving its cycle performance. Controlling the mass ratio of halogen to hydrogen within the above range can improve the capacity, initial coulombic efficiency, and rate performance of the negative electrode material. However, excessive halogen not only leads to an overly porous carbon material layer but also increases the specific surface area of ​​the negative electrode material, and simultaneously causes a decrease in the electrochemical performance of the negative electrode material, including capacity, initial coulombic efficiency, and rate performance.

[0069] In some implementations, m N / m H The value of m can be 0.02, 0.05, 0.1, 0.5, 0.8, 1, 2, 4, 8, 12, 16, or 20, or other values ​​within the above range; no limitation is made here. S / m H The value of can be 0.05, 0.1, 0.5, 0.8, 1, 1, 2, 3, 4, or 5, or other values ​​within the above range, which are not limited here. The appropriate control of the ratio of nitrogen and sulfur to hydrogen can enhance the binding ability of the anode material with lithium ions, which is beneficial for the desolvation of lithium ions at the interface, making it easier for lithium ions to enter the interior of the anode material, thereby further improving the rate performance of the anode material. In addition, the presence of nitrogen and sulfur can significantly improve the powder conductivity of the anode material, which is beneficial for improving the early cycle stability of the anode material.

[0070] In the anode material of this application, by exploring the content relationships of hydrogen, nitrogen, sulfur, and halogen elements, the mass ratios of hydrogen to nitrogen, sulfur, and halogen elements in the anode material are controlled within an appropriate range, thereby comprehensively improving the powder conductivity, first-time efficiency, and cycle performance of the material. The anode material of this application contains an appropriate amount of carbon-hydrogen bonds formed by the combination of hydrogen and carbon atoms. An appropriate carbon-hydrogen saturation helps to adjust the hydrophilicity of the material, improve the wettability of the electrolyte to the material, and make the lithium-ion conduction interface between the anode material and the electrolyte smoother. This improves the mass transfer / charge transfer efficiency of the anode material, thereby enhancing its low-temperature performance and powder conductivity. In this application, the negative electrode material also contains appropriate amounts of halogens, nitrogen (N) elements, and sulfur (S) elements. On the one hand, appropriate amounts of halogens, nitrogen (N), and sulfur elements play a role in regulating hydrocarbon saturation: halogens compete with hydrogen (H) for saturation, and their presence occupies H sites, thereby regulating hydrocarbon saturation. Nitrogen and sulfur elements may combine with hydrogen to form local functional groups such as amino groups, which also play a role in regulating hydrocarbon saturation. On the other hand, halogens can also participate in the formation of a more stable solid electrolyte interphase (SEI) film when the electrolyte comes into contact with the negative electrode material, which can enhance the bonding strength between the negative electrode material and the solid electrolyte film. This helps maintain the stability of the solid-liquid interface on the surface of the negative electrode material during cyclic charging and discharging, and can better suppress the expansion of the negative electrode material. Nitrogen and sulfur elements also help to further improve the conductivity of the negative electrode material powder, thereby improving the rate performance of the negative electrode material. When the content ratios of hydrogen, nitrogen, sulfur, and halogen elements in the negative electrode material satisfy the ratios described above in this application, the wetting performance between the negative electrode material and the electrolyte can be improved. This enables solid-liquid regulation during the slurry preparation process, improves slurry dispersibility, reduces slurry sedimentation or agglomeration, suppresses gas generation during slurry preparation, and helps maintain slurry stability. Therefore, the negative electrode material provided in this application possesses advantages such as high initial efficiency, high powder conductivity, high cycle stability, and low volume expansion rate.

[0071] In some embodiments, in the negative electrode material, 50 mg / kg ≤ m X The content of halogen elements in the negative electrode material is ≤1500mg / kg, meaning that the mass of halogen elements contained in each kilogram of negative electrode material can be 50mg, 150mg, 300mg, 600mg, 900mg, 1200mg, or 1500mg, or other values ​​within the above range, which are not limited here. By controlling the content of halogen elements in the negative electrode material, the initial capacity efficiency, rate performance, and cycle performance of the negative electrode material can be further improved, as well as the expansion of the negative electrode material can be further suppressed.

[0072] In some embodiments, in the negative electrode material, 100 mg / kg ≤ m NThe nitrogen content is ≤4000 mg / kg, meaning that the mass of nitrogen in each kilogram of anode material can be 100 mg, 500 mg, 1000 mg, 2000 mg, or 4000 mg, or other values ​​within the above range, which are not limited here. By controlling the nitrogen content in the anode material, the initial capacity efficiency, rate performance, and cycle performance of the anode material can be further improved, as well as the expansion of the anode material can be further suppressed.

[0073] In some embodiments, in the negative electrode material, 10 mg / kg ≤ m S The sulfur content is ≤200 mg / kg, meaning that the mass of sulfur in each kilogram of anode material can be 10 mg, 30 mg, 50 mg, 80 mg, 100 mg, 120 mg, 150 mg, 180 mg, or 200 mg, or other values ​​within the above range, which are not limited here. By controlling the sulfur content in the anode material, the capacity, first-efficiency, and rate performance of the anode material can be improved.

[0074] In some embodiments, the negative electrode material contains pores. The presence of pores in the negative electrode material can reserve buffer space for the volume expansion of silicon-based active materials, which can reduce the particle crushing and breakage caused by volume expansion and improve the cycle stability of the negative electrode material.

[0075] In some embodiments, the pore volume distribution curve of the negative electrode material has characteristic peaks in the range of 240 Å to 280 Å, 290 Å to 320 Å, 340 Å to 390 Å, or 410 Å to 460 Å in the pore volume distribution curve of the negative electrode material; that is, in the pore volume distribution curve of the negative electrode material, characteristic peaks in the pore volume distribution curve are present at any value of 240 Å, 250 Å, 260 Å, 270 Å, 280 Å or between therewith; at any value of 290 Å, 300 Å, 310 Å, 320 Å or between therewith; at any value of 340 Å, 350 Å, 360 Å, 370 Å, 380 Å, 390 Å or between therewith; and at any value of 410 Å, 420 Å, 430 Å, 440 Å, 450 Å, 460 Å or between therewith. Differences in elemental composition and carbon-hydrogen saturation in materials can affect their morphology. This application achieves this by adjusting the mass ratio of hydrogen to nitrogen, sulfur and halogen elements in the negative electrode material to an appropriate range, thereby enabling the local structure to grow longitudinally and forming the aforementioned unique mesoporous structure.

[0076] In some embodiments, the median particle size of the negative electrode material is 2.0µm to 12.0µm, specifically 2.0µm, 4.0µm, 6.0µm, 8.0µm, 10.0µm or 12.0µm, etc., and of course other values ​​within the above range are also possible, which are not limited here.

[0077] In some embodiments, the silicon-based active material includes at least one of elemental silicon, silicon oxide, silicon alloy, and silicate; that is, the silicon-based active material can be composed of any one of elemental silicon, silicon oxide, silicon alloy, or silicate alone, or it can be composed of a mixture of two or more of elemental silicon, silicon oxide, silicon metal, or silicate.

[0078] In the above embodiments, the general formula for silicon oxide is SiO. x 0 < x ≤ 2. More commonly, silicon oxide can be a mixture of various silicon oxides, such as a mixture of silicon oxide and silicon suboxide.

[0079] In some embodiments, the silicon-based active material includes a doped metal M, where M is selected from at least one of Li, Mg, Al, Fe, La, Zn, Ti, Cu, and Mn; specifically, the doped metal M can be present in a silicon alloy or silicate. The silicate can be a monobasic silicate (containing one metal ion), such as lithium silicate, magnesium silicate, aluminum silicate, iron silicate, etc., or a binary silicate (containing two metal ions), such as lithium magnesium silicate, lithium aluminum silicate, lithium zinc silicate, etc., or a ternary silicate (containing three metal ions), such as lithium aluminum titanium silicate, lithium magnesium aluminum silicate, etc., without limitation. In a specific embodiment, the silicon-based active material includes doped metal Mg and / or doped metal Li.

[0080] In some embodiments, the mass content of metal M in the negative electrode material is 0 wt% to 15 wt%, excluding 0 wt%, and can be 0.000001 wt%, 1 wt%, 5 wt%, 10 wt% or 15 wt%, etc. Of course, it can also be other values ​​within the above range, which are not limited here.

[0081] In some embodiments, the carbon content in the negative electrode material is 0.5wt% to 15wt%, specifically 0.5wt%, 1wt%, 5wt%, or 10wt% or 15wt%, etc., or other values ​​within the above range, which are not limited here.

[0082] In some embodiments, the carbon material includes at least one of graphite, graphene, amorphous carbon, diamond-like carbon, carbon nanotubes, and carbon fibers.

[0083] In some embodiments, carbon material located on the surface of silicon-based active material forms a carbon layer with a thickness of 20 nm to 1000 nm, specifically 20 nm, 100 nm, 200 nm, 400 nm, 800 nm or 1000 nm, etc., or other values ​​within the above range, which are not limited here.

[0084] In some embodiments, the tap density of the negative electrode material is 0.75 g / cm³. 3 ~ 1.35 g / cm 3 Specifically, it is 0.75 g / cm³. 3 0.95g / cm 3 1.05 g / cm 3 1.35 g / cm 3 Or any value between them; of course, the tap density of the negative electrode material can also be higher than 1.35 g / cm³. 3 Higher tap density is more conducive to improving the energy density of materials, but this application does not make any special limitation on this.

[0085] In some embodiments, the powder conductivity of the negative electrode material under a pressure of 20 kN is 0.01 S / cm to 100.00 S / cm, specifically 0.01 S / cm, 10.00 S / cm, 40.00 S / cm, 60.00 S / cm, 80.00 S / cm, 100.00 S / cm or any value between them. Of course, the powder conductivity of the negative electrode material can also be higher than 100.00 S / cm. The higher the powder conductivity, the more beneficial it is to improve the electrochemical performance of the material. This application does not make any special limitation in this regard.

[0086] In some implementations, the specific surface area of ​​the negative electrode material is 0.50 m². 2 / g ~ 10.00m 2 / g, specifically 0.80m 2 / g, 1.00m 2 / g, 1.50m 2 / g, 2.00m 2 / g, 3.00m 2 / g, 4.00m 2 / g, 5.00m 2 / g、8.00m 2 / g or 10.00m 2 / g, etc., can also be other values ​​within the above range, and are not limited here. Controlling the specific surface area of ​​the negative electrode material within the above range can slow down the volume expansion of the negative electrode material, which is beneficial to improving the cycle performance of the negative electrode material.

[0087] In some embodiments, the water content in the negative electrode material is less than or equal to 0.80%, specifically 0.01%, 0.10%, 0.40%, 0.60%, 0.80%, or any value between them. The lower the water content in the negative electrode material, the better it is for improving the electrochemical performance of the material. This application does not make any special limitation in this regard.

[0088] In some embodiments, the pH range of the negative electrode material is 6.00 to 12.00, specifically 6.00, 8.00, 9.00, 10.00, 11.00, or 12.00, etc., or other values ​​within the above range, which are not limited here. Preferably, the pH range of the negative electrode material is 7 to 10.

[0089] Secondly, this application provides a method for preparing the aforementioned negative electrode material, such as... Figure 1 As shown, it includes the following steps:

[0090] S100, preparation of precursors, the precursors include silicon-based active materials and carbon materials;

[0091] In S200, under a modified gas phase source environment, plasma-enhanced chemical vapor deposition is used to perform surface modification treatment on the precursor to obtain the anode material. The modified gas phase source includes hydrogen, sulfur, nitrogen, and halogen elements; the mass content of hydrogen in the anode material is m. H The mass content of halogen elements is m X The mass content of sulfur is m S The mass content of nitrogen is m N And satisfy the following relationship: 0.02≤m X / m H ≤5.00, 0.02≤m N / m H ≤20.00, 0.05≤m S / m H ≤5.00.

[0092] The method for preparing the anode material provided in this application utilizes plasma-enhanced chemical vapor deposition (PECVD) in a modified gas source environment to perform surface modification treatment on precursors containing silicon-based active materials and carbon materials. This method efficiently and uniformly dops multiple elements, achieving high deposition efficiency and controllability. After surface modification, the carbon materials on the surface of the silicon-based active material can combine with hydrogen elements to form carbon-hydrogen bonds, increasing the hydrogen saturation of carbon atoms in the carbon materials. This allows for adjustment of the hydrophilicity of the carbon materials and the wettability of the electrolyte on the anode material, resulting in a smoother lithium-ion conduction interface between the anode material and the electrolyte. This improves the mass / charge transfer efficiency of the anode material, thereby enhancing its low-temperature performance and powder conductivity. The appropriate incorporation of halogens and nitrogen (N) and sulfur (S) elements serves two main purposes. Firstly, it regulates hydrocarbon saturation: halogens compete with hydrogen for saturation, occupying H sites and thus controlling saturation. Nitrogen and sulfur, on the other hand, can combine with hydrogen to form local functional groups like amino groups, further regulating saturation. Secondly, halogens participate in the formation of a more stable solid electrolyte interphase (SEI) film when the electrolyte and anode material are in contact, enhancing the bonding strength between them. This helps maintain the stability of the solid-liquid interface on the anode material surface during cyclic charging and discharging, while also better suppressing anode material expansion. Nitrogen and sulfur elements further improve the conductivity of the anode material powder, thereby enhancing its rate performance. Therefore, modifying the surface of the anode material using a modified gas-phase source can suppress volume expansion and comprehensively improve its electrochemical performance, including initial efficiency, powder conductivity, and cycle performance.

[0093] The preparation method of this application is described in detail below with reference to the embodiments:

[0094] S100, prepare precursors, which include silicon-based active materials and carbon materials.

[0095] In some embodiments, the specific steps of preparing the precursor include coating at least a portion of the surface of the silicon-based active material with a carbon material.

[0096] In some embodiments, the specific preparation steps of the precursor include: solid-phase coating treatment of silicon-based active material and carbon material.

[0097] In some embodiments, the carbon material includes at least one of graphite, graphene, amorphous carbon, diamond-like carbon, carbon nanotubes, and carbon fibers.

[0098] In some embodiments, the step of solid-phase coating of silicon-based active material with carbon material includes: ball milling and mixing silicon-based material with solid carbon source (such as pitch), followed by high-temperature treatment to achieve coating of silicon-based active material by carbon material.

[0099] In some embodiments, the specific preparation steps of the precursor include: gas-phase carbon coating of silicon-based active materials under a gas-phase carbon source.

[0100] In some embodiments, the gaseous carbon source includes at least one of methane, ethane, ethylene, propane, and propylene.

[0101] In some embodiments, the temperature for gas-phase carbon coating is 600~1000℃ and the holding time is 1h~48h; those skilled in the art can adjust the specific reaction time according to the type of carbon source gas, flow rate, deposition temperature and target carbon content.

[0102] In some embodiments, the carbon material content in the precursor is between 1 wt% and 10 wt%, preferably between 2 wt% and 7 wt%.

[0103] In some embodiments, the silicon-based active material includes at least one of elemental silicon, silicon oxide, silicon alloy, and silicate.

[0104] In some embodiments, the silicon-based active material includes a doped metal M, where M is selected from at least one of Li, Mg, Al, Fe, La, Zn, Ti, Cu, and Mn.

[0105] In some embodiments, the specific preparation steps of the precursor for gas-phase carbon coating of silicon-based active materials also include: pulverizing and sieving the coating product.

[0106] In some embodiments, after S100, the method further includes purifying the precursor to remove impurities from the precursor.

[0107] In some embodiments, the purification process includes washing and drying the precursor.

[0108] In some embodiments, the washing process may include rinsing, soaking, and centrifugation; specifically, the precursor is first rinsed with deionized water to remove impurities from the surface of the precursor, and then the precursor is soaked and centrifuged to remove impurities from the interior or pores of the precursor. This helps to ensure that the hydrogen (sulfur, nitrogen, or halogen) reaction rate between precursor particles is consistent, resulting in small differences in hydrogen content (nitrogen content, sulfur content, and halogen content) between different particles.

[0109] In some implementations, deionized water is used for rinsing to consider cost and rinsing effectiveness. Of course, other suitable detergents can also be used for rinsing.

[0110] In some embodiments, for cost and soaking effect considerations, the soaking is carried out in deionized water. Of course, other suitable soaking solutions can also be selected to soak the silicon-based active material coated with carbon material. In this embodiment, preferably, the mass ratio of material to solution during the soaking process is (0.5-1.5):(1.5-2.5). If the ratio is too large, the soaking effect will be unsatisfactory, and if the ratio is too small, the soaking solution (deionized water) will be wasted.

[0111] In some implementations, drying is performed under vacuum to minimize the drying temperature. Using low-temperature vacuum drying can effectively control the degree of surface oxidation of the material, which is beneficial to improving the efficiency of hydrogen (sulfur, nitrogen, or halogen) adsorption reaction of the precursor.

[0112] In some implementations, the centrifugation time is 30 min to 360 min, specifically 30 min, 90 min, 150 min, 200 min, 250 min, 300 min or 360 min, etc. Of course, other values ​​within the above range are also possible, and no limitation is made here.

[0113] In some embodiments, the drying temperature is 45℃~80℃, specifically 45℃, 50℃, 60℃, 70℃ or 80℃, etc., and of course, other values ​​within the above range are also possible, which are not limited here; the drying time is 3h~48h, specifically 3h, 10h, 20h, 30h, 40h or 48h, etc., and of course, other values ​​within the above range are also possible, which are not limited here.

[0114] In S200, under a modified gas phase source environment, plasma-enhanced chemical vapor deposition is used to surface modify the precursor to obtain the anode material. The modified gas phase source includes hydrogen, sulfur, nitrogen, and halogen elements. The anode material contains hydrogen, halogen, nitrogen, and sulfur elements, with a hydrogen content of m. H The mass content of halogen elements is m X The mass content of sulfur is m S The mass content of nitrogen is m N And satisfy the following relationship: 0.02≤m X / m H ≤5.00, 0.02≤m N / m H ≤20.00, 0.05≤m S / m H ≤5.00.

[0115] In some embodiments, the powder conductivity of the precursor under 20 kN pressure is 0.001 S / cm to 0.1 S / cm, specifically 0.001 S / cm, 0.005 S / cm, 0.01 S / cm, 0.05 S / cm, or 0.1 S / cm, etc., and other values ​​within the above range are also possible, without limitation here; the powder conductivity of the negative electrode material under 20 kN pressure is 0.1 S / cm to 100.0 S / cm, specifically 0.1 S / cm, 1 S / cm, 10 S / cm, 50 S / cm, or 100 S / cm, etc., and other values ​​within the above range are also possible, without limitation here.

[0116] In some embodiments, the pore volume distribution curve of the negative electrode material has characteristic peaks in the range of 240 Å to 280 Å, 290 Å to 320 Å, 340 Å to 390 Å, or 410 Å to 460 Å in the pore volume distribution curve of the negative electrode material; that is, in the pore volume distribution curve of the negative electrode material, characteristic peaks in the pore volume distribution curve are present at any value of 240 Å, 250 Å, 260 Å, 270 Å, 280 Å or between therewith; at any value of 290 Å, 300 Å, 310 Å, 320 Å or between therewith; at any value of 340 Å, 350 Å, 360 Å, 370 Å, 380 Å, 390 Å or between therewith; and at any value of 410 Å, 420 Å, 430 Å, 440 Å, 450 Å, 460 Å or between therewith. The compositional differences of the modified gas source, the deposition method, and the deposition rate during the deposition process all affect the morphology of the material. This application adjusts the mass ratio of hydrogen, nitrogen, sulfur, and halogen elements in the modified gas source to an appropriate range, and controls the deposition rate and other deposition conditions to an appropriate range, so that the surface of the material is based on carbon elements, and the local structure grows vertically to form the above-mentioned unique mesoporous structure.

[0117] In some embodiments, the specific steps of S200 are as follows: evacuation, placing the precursor under a modified gas source, and performing plasma-enhanced chemical vapor deposition on the precursor under a bias voltage condition. By adjusting the modified gas source with different gas compositions and introducing a bias voltage, the deposition efficiency of hydrogen, halogens, nitrogen, and sulfur on the precursor can be effectively controlled, thereby controlling the morphology, powder conductivity, rate performance, cycle performance, initial capacity efficiency, and low-temperature performance of the final anode material.

[0118] In some implementations, the bias voltage is -500V to 0V, excluding 0V, specifically -500V, -400V, -300V, -200V, -100V, -50V or 0.1V, etc. Of course, it can also be other values ​​within the above range, which are not limited here.

[0119] In some embodiments, the pressure of the vacuum is less than 1.0 Torr prior to plasma-enhanced chemical vapor deposition.

[0120] In some embodiments, the working pressure of plasma-enhanced chemical vapor deposition is 500 Pa to 5000 Pa, specifically 500 Pa, 1000 Pa, 2000 Pa, 3000 Pa, 4000 Pa or 5000 Pa, etc. Of course, other values ​​within the above range are also possible, and are not limited here.

[0121] In some embodiments, the deposition temperature of plasma-enhanced chemical vapor deposition is 200–800°C, specifically 200°C, 300°C, 400°C, 500°C, 600°C, 700°C, or 800°C, etc. Of course, other values ​​within the above range are also possible and are not limited here.

[0122] In some embodiments, the flow rate of the modified gas source is 200 ml / min to 5000 ml / min, specifically 200 ml / min, 300 ml / min, 400 ml / min or 5000 ml / min, etc. Of course, other values ​​within the above range are also possible, and are not limited here.

[0123] In some embodiments, the modified gaseous source includes a reactant gas, which may include hydrogen, a nitrogen-containing gas, a sulfur-containing gas, or a halogen source gas. Specifically, the nitrogen-containing gas may be one or more of nitrogen and ammonia, the sulfur-containing gas may be hydrogen sulfide, and the halogen source gas may be one or more of fluorine, chlorine, bromine, iodine, hydrogen bromide, hydrogen iodide, and carbon tetrafluoride. When the modified gaseous source includes iodine, the added iodine raw material may be gaseous or solid. Preferably, the added iodine raw material is solid iodine to facilitate control of the amount of iodine added. Solid iodine is easily sublimated into a gaseous state and mixed with other gaseous components in the modified gaseous source. Of course, those skilled in the art may also choose other types of nitrogen-containing gases, sulfur-containing gases, and halogen source gases, as long as it is convenient to deposit nitrogen, sulfur, and halogen elements on the precursor.

[0124] In some embodiments, the modified gas source further includes a protective gas, which includes one or more of argon, krypton, nitrogen, neon, and helium.

[0125] In some specific embodiments, the volume ratio of hydrogen to protective gas is 1:(0.1 to 5), specifically 1:0.1, 1:1, 1:2, 1:3, 1:4, 1:5 or other values ​​within the above range;

[0126] The volume ratio of hydrogen to nitrogen-containing gas is 1:(0 to 1.2), specifically 1:0.05, 1:0.1, 1:0.3 or other values ​​within the above range;

[0127] The volume ratio of hydrogen to sulfur-containing gas is 1:(0~0.2), specifically 1:0.01, 1:0.03, 1:0.05, 1:0.15, 1:0.20 or other values ​​within the above range;

[0128] The volume ratio of hydrogen to halogen source gas is 1:(0 to 0.05), specifically 1:0.015, 1:0.01, 1:0.03, 1:0.05 or other values ​​within the above range.

[0129] In some embodiments, after step S200, the preparation method further includes sieving the modified product to obtain a negative electrode material product with the target particle size.

[0130] Thirdly, this application provides a battery comprising the above-described negative electrode material or a negative electrode material prepared by the above-described preparation method.

[0131] Those skilled in the art will understand that the above-described methods for preparing the negative electrode material and battery are merely examples. Other methods commonly used in the art can be employed without departing from the disclosure of this application.

[0132] The embodiments of this application will be further described below with reference to several examples. However, the embodiments of this application are not limited to the specific embodiments described below. Appropriate modifications can be made within the scope of the main claims.

[0133] Test method:

[0134] 1. Particle Size: Particle size was measured using Mastersizer 3000 laser diffraction technology. Particle size was measured by measuring the intensity of the scattered light as the laser beam passed through the dispersed particle sample. The data was then used to analyze and calculate the particle size distribution that formed the scattered spectrum. D50: The particle size corresponding to a cumulative particle size distribution percentage of 50% for a sample. Physically, it means that 50% of the particles are larger than D50, and 50% are smaller. D50 is also called the median particle size. D90, D50, and D10 particle sizes are the equivalent diameters (average particle sizes) of the largest particles when the cumulative distribution is 90%, 50%, and 10% respectively in the distribution curve.

[0135] 2. Specific surface area: The specific surface area was measured using a Microt TriStar3000 specific surface area and pore size analyzer.

[0136] 3. Tap density: Using Baxter's tapping method, a certain amount of sample is weighed and vibrated 3000 times at 300 times / min to test the tap density.

[0137] 4. Coating layer (carbon layer) thickness: The average thickness of the coating layer is obtained by cross-sectioning the material using FIB-SEM equipment and measuring it in SEM.

[0138] 5. Powder conductivity: The volume resistivity of the negative electrode material powder was tested using the four-probe method. The resistance of the powder was measured at five pressure points: 4KN, 8KN, 12KN, 16KN, and 20KN. The conductivity and resistivity of the negative electrode material powder were then automatically calculated by the computer.

[0139] 6. Testing of water content in negative electrode materials: The gravimetric method is used. The material is placed in a vacuum oven at 250℃ and dried for 48 hours. The weight reduction before and after drying is observed and converted into moisture content.

[0140] 7. pH test of negative electrode material: Mix 5g of material with 45g of deionized water, sonicate for 30min, and then test using an electronic pH meter.

[0141] 8. Pore volume: Tested using a BET micropore ratio meter and pore size analyzer, in accordance with the corresponding test guidelines for the equipment.

[0142] 9. Elemental content: Halogen elements are tested using an ion chromatograph, hydrogen and nitrogen content are tested using an oxygen, nitrogen and hydrogen elemental analyzer, and sulfur content is tested using an infrared carbon and sulfur analyzer. Specific testing procedures are performed in accordance with the corresponding test guidelines for each equipment.

[0143] 10. Electrical performance testing:

[0144] Assemble the button cell according to BTRTC / ZY / 01-020 "Mesh Cell Method Work Instruction"; the electrode is a lithium metal sheet, the separator is a PP-PE-PP composite membrane with a diameter of 19.2 mm; the electrolyte composition ratio is EC / EMC / DMC=1 / 1 / 1, and the lithium salt (LiPF6) concentration is 1.05 mol / L.

[0145] Capacity testing: The negative electrode materials prepared in the examples and comparative examples were used to prepare batteries and tested using a coin cell battery charge and discharge equipment. The batteries were charged at a constant current of 0.1C to 10mV, then charged at a constant current of 0.02C to 5mV, and discharged at a constant current of 0.1C to 1.5V.

[0146] Half-cell 50-cycle cycle test: The negative electrode materials prepared in the examples and comparative examples were used to prepare batteries, which were tested using a coin cell charge-discharge device. In the first week, the batteries were discharged at 0.1C to 0.01V, then discharged at 0.01C with decreasing arithmetic progression to 0.01V, discharged at 0.01C to 0.005V, and charged at 0.1C to 1.5V. In the second week, the batteries were discharged at 0.2C to 0.01V, then discharged at 0.02C with decreasing arithmetic progression to 0.01V, discharged at 0.02C to 0.005V, and charged at 0.2C to 1.5V. Week 3: Discharge at 0.5C to 0.01V, then discharge at 0.05C with arithmetic progression to 0.01V, then discharge at 0.05C to 0.005V, and then charge at 0.5C to 1.5V; Weeks 4 to 50: Discharge at 1C to 0.01V, then discharge at 0.1C with arithmetic progression to 0.01V, then discharge at 0.1C to 0.005V, and then charge at 1C to 1.5V; Week 51: Discharge at 0.1C to 0.01V, then discharge at 0.01C with arithmetic progression to 0.01V, and then discharge at 0.01C to 0.005V.

[0147] Full battery performance test: The full battery performance was tested using 18650 small cylindrical batteries. Silicon-based materials and graphite were combined at a capacity of 450mAh / g, and the relevant performance tests were completed according to the methods specified in the national standard GB / T 31486-2015.

[0148] Example 1

[0149] A method for preparing a negative electrode material includes the following steps:

[0150] (1) Graphite was used to coat silicon suboxide to obtain 1000g of precursor (carbon content of 5wt%). The precursor was rinsed with deionized water for 30min and then vacuum dried for 12h at 75℃. Then it was sieved to obtain the precursor with the target particle size.

[0151] (2) The precursor is placed on the bias voltage stage in the plasma reaction chamber and evacuated to below 0.1 Pa. Then, a modified gas source is introduced at a flow rate of 3000 ml / min. The modified gas source is a mixture of hydrogen, argon, ammonia, hydrogen sulfide and chlorine in a volume ratio of 1:1:0.2:0.03:0.01. After controlling the pressure in the reaction chamber to 2000 Pa with a vacuum pump, the plasma is turned on to generate plasma light. At the same time, a bias voltage of -200 V is introduced into the reaction platform in the reaction chamber. After the plasma stabilizes, the pressure in the reaction chamber is further adjusted to maintain it at 2000 Pa. The reaction is then started and the reaction time is 24 h. The reaction temperature is controlled between 450 °C and 500 °C to obtain the modified product.

[0152] (3) The modified product is sieved and then vacuum dried at 75°C for 12 hours to obtain the finished negative electrode material.

[0153] The specific electrochemical properties of the anode material products prepared in Example 1 are shown in Table 2.

[0154] The anode material prepared in Example 1 includes a silicon-based active material and a carbon material. The carbon material is located on at least part of the surface of the silicon-based active material. The anode material contains hydrogen, halogen, nitrogen and sulfur elements. The specific test data are shown in Table 1.

[0155] In addition, the anode material obtained in Example 1 has the following characteristics: median particle size of 5.3 µm, carbon content of 4.95 wt%, and tap density of 0.98 g / cm³. 3 It has a moisture content of 0.21%, a pH of 9.63, and a specific surface area of ​​1.88 m². 2 / g.

[0156] Furthermore, the anode material prepared in Example 1 exhibits a pore volume characteristic peak in each of the pore size ranges of 240Å–280Å, 290Å–320Å, 340Å–390Å, and 410Å–460Å, as detailed in the figure. Figure 2 .

[0157] Example 2

[0158] A method for preparing a negative electrode material includes the following steps:

[0159] (1) Graphene was used to coat lithium-doped silicon suboxide to obtain 1000g of precursor (carbon content of 5wt%). The precursor was centrifuged and washed with deionized water for 2h, and then vacuum dried at 80℃ for 24h. The precursor was then sieved to obtain the target particle size.

[0160] (2) The precursor is placed on the bias voltage stage in the plasma reaction chamber and evacuated to below 0.1 Pa. Then, a modified gas source is introduced at a flow rate of 3000 ml / min. The modified gas source is a mixture of hydrogen, argon, ammonia, hydrogen sulfide and carbon tetrafluoride in a volume ratio of 1:1:0.1:0.05:0.05. After controlling the pressure in the reaction chamber to 2000 Pa by the vacuum pump, the plasma is turned on to generate plasma light. At the same time, a bias voltage of -200 V is introduced into the reaction platform in the reaction chamber. After the plasma stabilizes, the pressure in the reaction chamber is further adjusted to maintain it at 2000 Pa. The reaction time is 24 h and the reaction temperature is controlled between 450 °C and 500 °C to obtain the modified product.

[0161] (3) The modified product is sieved and then vacuum dried for 12 hours at a temperature of 75°C to obtain the finished negative electrode material.

[0162] The specific electrochemical properties of the anode material products prepared in Example 2 are shown in Table 2.

[0163] The anode material prepared in Example 2 includes a silicon-based active material and a carbon material. The carbon material is located on at least part of the surface of the silicon-based active material. The anode material contains hydrogen, halogen, nitrogen and sulfur elements. The specific test data are shown in Table 1.

[0164] The anode material obtained in Example 2 has the following characteristics: median particle size of 5.62 µm, carbon content of 5.01 wt%, and tap density of 0.98 g / cm³. 3 It has a moisture content of 0.17%, a pH of 10.47, and a specific surface area of ​​1.92 m². 2 / g.

[0165] In addition, the finished negative electrode material obtained in Example 2 has one pore volume characteristic peak in the pore size ranges of 240Å~280Å, 290Å~320Å, 340Å~390Å and 410Å~460Å respectively.

[0166] Example 3

[0167] A method for preparing a negative electrode material includes the following steps:

[0168] (1) Graphite was used to coat silicon suboxide to obtain 1000g of precursor (carbon content of 5wt%). The precursor was rinsed with deionized water for 30min and then vacuum dried for 12h at 75℃. Then it was sieved to obtain the precursor with the target particle size.

[0169] (2) The precursor is placed on the bias voltage stage in the reaction chamber and evacuated to below 0.1 Pa. Then, a modified gas source is introduced at a flow rate of 3000 ml / min. The modified gas source is a mixture of hydrogen, argon, ammonia, hydrogen sulfide and hydrogen bromide in a volume ratio of 1:1:0.15:0.03:0.03. After the pressure in the reaction chamber is controlled to 3000 Pa by the vacuum pump, the plasma is turned on to generate plasma light. At the same time, a bias voltage of -200 V is introduced into the reaction platform in the reaction chamber. After the plasma stabilizes, the pressure in the reaction chamber is further adjusted to maintain it at 3000 Pa. The reaction time is then started. The reaction time is 24 h and the reaction temperature is controlled between 650 and 700 °C to obtain the modified product.

[0170] (3) The modified product is sieved and then vacuum dried for 12 hours at a temperature of 75°C to form the finished negative electrode material.

[0171] The specific electrochemical properties of the anode material products prepared in Example 3 are shown in Table 2.

[0172] The negative electrode material prepared in Example 3 includes a silicon-based active material and a carbon material. The carbon material is located on at least part of the surface of the silicon-based active material. The negative electrode material contains hydrogen, halogen, nitrogen and sulfur elements. The specific test data are shown in Table 1.

[0173] The anode material obtained in Example 3 has the following characteristics: median particle size of 5.12 µm, carbon content of 4.95 wt%, and tap density of 0.98 g / cm³. 3 It has a moisture content of 0.07%, a pH of 9.51, and a specific surface area of ​​2.49 m². 2 / g.

[0174] In addition, the finished negative electrode material prepared in Example 3 has one pore volume characteristic peak in the pore size ranges of 240Å~280Å, 290Å~320Å, 340Å~390Å and 410Å~460Å respectively.

[0175] Example 4

[0176] A method for preparing a negative electrode material includes the following steps:

[0177] (1) 1000g of precursor (carbon content of 5wt%) was obtained by coating lithium-doped silicon suboxide with graphite. The precursor was centrifuged and washed with deionized water for 2h, and then vacuum dried at 80℃ for 24h. The precursor was then sieved to obtain the target particle size.

[0178] (2) The precursor is placed on the bias voltage stage in the reaction chamber and evacuated to below 0.1 Pa. Then, a modified gas source is introduced at a flow rate of 3000 ml / min. The modified gas source is a mixture of hydrogen, argon, ammonia, hydrogen sulfide and hydrogen iodide in a volume ratio of 1:1.5:0.05:0.01:0.01. After controlling the pressure in the reaction chamber to 3000 Pa by the vacuum pump, the plasma is turned on to generate plasma light. At the same time, a bias voltage of -200 V is introduced into the reaction platform in the reaction chamber. After the plasma stabilizes, the pressure in the reaction chamber is further adjusted to maintain it at 3000 Pa. The reaction time is then started. The reaction time is 24 h and the reaction temperature is controlled between 700 and 750 °C to obtain the modified product.

[0179] (3) The modified product is sieved and then vacuum dried for 12 hours at a temperature of 75°C to form the finished negative electrode material.

[0180] The specific electrochemical properties of the anode material products prepared in Example 4 are shown in Table 2.

[0181] The negative electrode material prepared in Example 4 includes a silicon-based active material and a carbon material. The carbon material is located on at least part of the surface of the silicon-based active material. The negative electrode material contains hydrogen, halogen, nitrogen and sulfur elements. The specific test data are shown in Table 1.

[0182] The anode material obtained in Example 4 has the following characteristics: median particle size of 5.35 µm, carbon content of 4.95 wt%, and tap density of 0.98 g / cm³. 3 It has a moisture content of 0.17%, a pH of 10.47, and a specific surface area of ​​1.92 m². 2 / g.

[0183] In addition, the finished negative electrode material prepared in Example 4 has one pore volume characteristic peak in the pore size ranges of 240Å~280Å, 290Å~320Å, 340Å~390Å and 410Å~460Å respectively.

[0184] Example 5

[0185] A method for preparing a negative electrode material includes the following steps:

[0186] (1) Graphite was used to coat silicon suboxide to obtain 1000g of precursor. The precursor was rinsed with deionized water for 30min and then vacuum dried for 12h at a temperature of 75℃. Then it was sieved to obtain the precursor with the target particle size.

[0187] (2) The precursor is placed on the bias voltage stage in the reaction chamber and evacuated to below 0.1 Pa. Then, a modified gas source is introduced at a flow rate of 3000 ml / min. The modified gas source is a mixture of hydrogen, argon, ammonia, hydrogen sulfide and chlorine in a volume ratio of 1:1:0.05:0.015:0.05. After the vacuum pump controls the pressure in the reaction chamber to 3000 Pa, the plasma is turned on to generate plasma light and a bias voltage of -200 V is introduced into the reaction platform in the reaction chamber. After the plasma stabilizes, the pressure in the reaction chamber is further adjusted to maintain it at 3000 Pa. The reaction time is then started and the reaction duration is 24 h. The reaction temperature is controlled between 650 and 700 °C to obtain the modified product.

[0188] (3) The modified product is sieved and then vacuum dried for 12 hours at a temperature of 75°C to form the finished negative electrode material.

[0189] The specific electrochemical properties of the anode material products prepared in Example 5 are shown in Table 2.

[0190] The negative electrode material prepared in Example 5 includes a silicon-based active material and a carbon material. The carbon material is located on at least part of the surface of the silicon-based active material. The negative electrode material contains hydrogen, halogen, nitrogen and sulfur elements. The specific test data are shown in Table 1.

[0191] The anode material obtained in Example 5 has the following characteristics: median particle size of 5.08 µm, carbon content of 5.32 wt%, and tap density of 0.98 g / cm³. 3 It has a moisture content of 0.05%, a pH of 9.45, and a specific surface area of ​​2.23 m². 2 / g.

[0192] In addition, the anode material prepared in Example 5 has one pore volume characteristic peak in the pore size ranges of 240Å~280Å, 290Å~320Å, 340Å~390Å and 410Å~460Å respectively.

[0193] Example 6

[0194] A method for preparing a negative electrode material includes the following steps:

[0195] (1) A mixture of graphite and graphene was used to coat a mixture of silicon suboxide and lithium silicate to obtain 1000g of precursor (carbon content of 5wt%). The precursor was rinsed with deionized water for 30min and then vacuum dried for 10h at 80℃. The precursor was then sieved to obtain the precursor with the target particle size.

[0196] (2) The precursor is placed on the bias voltage stage in the reaction chamber and evacuated to below 0.1 Pa. Then, a modified gas source is introduced at a flow rate of 5000 ml / min. The modified gas source is a mixture of hydrogen, argon, ammonia, hydrogen sulfide, and chlorine in a volume ratio of 1:5:0.3:0.015:0.01. The pressure in the reaction chamber is controlled to 2000 Pa by a vacuum pump. Then, plasma is turned on to generate plasma light, and a bias voltage of -200 V is simultaneously introduced into the reaction platform in the reaction chamber. After the plasma stabilizes, the pressure in the reaction chamber is further adjusted to maintain 2000 Pa. The reaction is then started and the reaction time is 24 h. The reaction temperature is controlled between 450 °C and 500 °C to obtain the modified product.

[0197] (3) The modified product is sieved and then vacuum dried for 12 hours at a temperature of 75°C to form the finished negative electrode material.

[0198] The specific electrochemical properties of the anode material products prepared in Example 6 are shown in Table 2.

[0199] The negative electrode material prepared in Example 6 includes a silicon-based active material and a carbon material. The carbon material is located on at least part of the surface of the silicon-based active material. The negative electrode material contains hydrogen, halogen, nitrogen and sulfur elements. The specific test data are shown in Table 1.

[0200] The anode material obtained in Example 6 has the following characteristics: median particle size of 8.4 µm, carbon content of 4.89 wt%, and tap density of 0.95 g / cm³. 3 It has a moisture content of 0.08%, a pH of 9.55, and a specific surface area of ​​1.54 m². 2 / g.

[0201] In addition, the anode material prepared in Example 6 has one pore volume characteristic peak in the pore size ranges of 240Å~280Å, 290Å~320Å, 340Å~390Å and 410Å~460Å respectively.

[0202] Example 7

[0203] A method for preparing a negative electrode material includes the following steps:

[0204] (1) Amorphous carbon was used to coat silicon suboxide to obtain 1000g of precursor (carbon content of 5wt%). The precursor was rinsed with deionized water for 30min and then vacuum dried for 12h at 75℃. Then it was sieved to obtain the precursor with the target particle size.

[0205] (2) The precursor is placed on the bias voltage stage in the reaction chamber and evacuated to below 0.1 Pa. Then, a modified gas source is introduced at a flow rate of 3000 ml / min. The modified gas source is a mixture of hydrogen, argon, nitrogen, hydrogen sulfide and iodine in a volume ratio of 1:5:0.05:0.2:0.1. After controlling the pressure in the reaction chamber to 5000 Pa by the vacuum pump, the plasma is turned on to generate plasma light. At the same time, a bias voltage of -200 V is introduced into the reaction platform in the reaction chamber. After the plasma stabilizes, the pressure in the reaction chamber is further adjusted to maintain it at 3000 Pa. The reaction is then started and the reaction time is 24 h. The reaction temperature is controlled between 500 °C and 800 °C to obtain the modified product.

[0206] (3) The modified product is sieved and then vacuum dried for 12 hours at a temperature of 75°C to form the finished negative electrode material.

[0207] The specific electrochemical properties of the anode material products prepared in Example 7 are shown in Table 2.

[0208] The negative electrode material prepared in Example 7 includes a silicon-based active material and a carbon material. The carbon material is located on at least part of the surface of the silicon-based active material. The negative electrode material contains hydrogen, halogen, nitrogen and sulfur elements. The specific test data are shown in Table 1.

[0209] The anode material obtained in Example 7 has the following characteristics: median particle size of 5.5 µm, carbon content of 6.54 wt%, and tap density of 0.98 g / cm³. 3 The moisture content is 0.21%, the powder conductivity (at 20 kN) is 4.39 S / cm, the pH is 9.63, and the specific surface area is 1.88 m². 2 / g.

[0210] In addition, the finished negative electrode material prepared in Example 7 has one pore volume characteristic peak in the pore size ranges of 240Å~280Å, 290Å~320Å, 340Å~390Å and 410Å~460Å respectively.

[0211] Example 8

[0212] A method for preparing a negative electrode material includes the following steps:

[0213] (1) Graphite was used to coat magnesium-doped silicon suboxide to obtain 1000g of precursor (carbon content of 5wt%). The precursor was rinsed with deionized water for 30min and then vacuum dried for 12h at 75℃. Then it was sieved to obtain the precursor with the target particle size.

[0214] (2) The precursor is placed on the bias voltage stage in the reaction chamber and evacuated to below 0.1 Pa. Then, a modified gas source is introduced at a flow rate of 3000 ml / min. The modified gas source is a mixture of hydrogen, argon, nitrogen, hydrogen sulfide and chlorine in a volume ratio of 1:1:0.15:0.01:0.015. After controlling the pressure in the reaction chamber to 2000 Pa by the vacuum pump, the plasma is turned on to generate plasma light. At the same time, a bias voltage of -200 V is introduced into the reaction platform in the reaction chamber. After the plasma stabilizes, the pressure in the reaction chamber is further adjusted to maintain it at 2000 Pa. The reaction is then started and the reaction time is 24 h. The reaction temperature is controlled between 450 °C and 500 °C to obtain the modified product.

[0215] (3) The modified product is sieved and then vacuum dried for 12 hours at a temperature of 75°C to form the finished negative electrode material.

[0216] The specific electrochemical properties of the anode material products prepared in Example 8 are shown in Table 2.

[0217] The negative electrode material prepared in Example 8 includes a silicon-based active material and a carbon material. The carbon material is located on at least part of the surface of the silicon-based active material. The negative electrode material contains hydrogen, halogen, nitrogen and sulfur elements. The specific test data are shown in Table 1.

[0218] The anode material obtained in Example 8 has the following characteristics: median particle size of 5.13 µm, carbon content of 4.98 wt%, and tap density of 0.98 g / cm³. 3 It has a moisture content of 0.22%, a pH of 9.61, and a specific surface area of ​​1.85 m². 2 / g.

[0219] In addition, the finished negative electrode material obtained in Example 8 has one pore volume characteristic peak in the pore size ranges of 240Å~280Å, 290Å~320Å, 340Å~390Å and 410Å~460Å respectively.

[0220] Example 9

[0221] A method for preparing a negative electrode material includes the following steps:

[0222] (1) The lithium aluminum doped silicon suboxide mixture was coated with graphite to obtain 1000g of precursor (carbon content of 5wt%). The precursor was rinsed with deionized water for 30min and then vacuum dried for 12h at 75℃. Then it was sieved to obtain the precursor with the target particle size.

[0223] (2) The precursor is placed on the bias voltage stage in the reaction chamber and evacuated to below 0.1 Pa. Then, a modified gas source is introduced at a flow rate of 3000 ml / min. The modified gas source is a mixture of hydrogen, argon, nitrogen, ammonia, hydrogen sulfide, chlorine and iodine in a volume ratio of 1:1:0.005:0.005:0.04:0.005:0.005. After controlling the pressure in the reaction chamber to 2000 Pa by the vacuum pump, the plasma is turned on to generate plasma light, and a bias voltage of -200 V is simultaneously introduced into the reaction platform in the reaction chamber. After the plasma stabilizes, the pressure in the reaction chamber is further adjusted to maintain it at 2000 Pa. The reaction is then started and the reaction time is 24 h. The reaction temperature is controlled between 450 °C and 500 °C to obtain the modified product.

[0224] (3) The modified product is sieved and then vacuum dried for 12 hours at a temperature of 75°C to form the finished negative electrode material.

[0225] The specific electrochemical properties of the anode material products prepared in Example 9 are shown in Table 2.

[0226] The negative electrode material prepared in Example 9 includes a silicon-based active material and a carbon material. The carbon material is located on at least part of the surface of the silicon-based active material. The negative electrode material contains hydrogen, halogen, nitrogen and sulfur elements. The specific test data are shown in Table 1.

[0227] The negative electrode material prepared in Example 9 also has the following characteristics: median particle size of 5.18 µm, carbon content of 4.99 wt%, and tap density of 0.98 g / cm³. 3 It has a moisture content of 0.15%, a pH of 9.83, and a specific surface area of ​​1.98 m². 2 / g.

[0228] In addition, the finished negative electrode material obtained in Example 9 has one pore volume characteristic peak in the pore size ranges of 240Å~280Å, 290Å~320Å, 340Å~390Å and 410Å~460Å respectively.

[0229] Comparative Example 1

[0230] Unlike Example 1, no plasma treatment was performed.

[0231] The negative electrode material prepared in Comparative Example 1 also has the following characteristics: median particle size of 5.21 µm, carbon content of 4.98 wt%, and tap density of 0.98 g / cm³. 3 It has a moisture content of 0.25%, a pH of 9.69, and a specific surface area of ​​1.81 m². 2 / g.

[0232] Furthermore, the anode material prepared in Comparative Example 1 exhibits a large broad peak within the pore size range of 240 Å to 460 Å.

[0233] Comparative Example 2

[0234] A method for preparing a negative electrode material includes the following steps:

[0235] The difference from Example 2 is:

[0236] (2) The precursor is placed on the bias voltage stage in the reaction chamber and evacuated to below 0.1 Pa. Then, a modified gas source is introduced at a flow rate of 3000 ml / min. The modified gas source is a mixture of hydrogen, argon, ammonia and hydrogen sulfide in a volume ratio of 0.5:1:1:1. After controlling the pressure in the reaction chamber to 4000 Pa by the vacuum pump, the plasma is turned on to generate plasma light. At the same time, a bias voltage of -500 V is introduced into the reaction platform in the reaction chamber. After the plasma stabilizes, the pressure in the reaction chamber is further adjusted to maintain it at 2000 Pa. The reaction is then started and the reaction time is 24 h. The reaction temperature is measured between 450 °C and 500 °C to obtain the modified product.

[0237] The negative electrode material prepared in Comparative Example 2 has the following characteristics: median particle size of 5.38 µm, carbon content of 5.05 wt%, and tap density of 0.98 g / cm³. 3 It has a moisture content of 0.13%, a pH of 10.47, and a specific surface area of ​​1.92 m². 2 / g.

[0238] In addition, the anode material prepared in Comparative Example 2 has one pore volume characteristic peak in the pore size ranges of 290Å~320Å, 340Å~390Å and 410Å~460Å respectively.

[0239] Comparative Example 3

[0240] A method for preparing a negative electrode material includes the following steps:

[0241] The difference from Example 2 is:

[0242] (2) The precursor is placed on the bias voltage stage in the plasma reaction chamber and evacuated to below 0.1 Pa. Then, a modified gas source is introduced at a flow rate of 2000 ml / min. The modified gas source is a mixture of hydrogen, argon, ammonia and carbon tetrafluoride in a volume ratio of 1:1:0.1:0.03. After controlling the pressure in the reaction chamber to 1500 Pa by the vacuum pump, the plasma is turned on to generate plasma light. At the same time, a bias voltage of -200 V is introduced into the reaction platform in the reaction chamber. After the plasma stabilizes, the pressure in the reaction chamber is further adjusted to maintain it at 1500 Pa. The reaction time is then started. The reaction time is 24 h and the reaction temperature is controlled between 400 °C and 450 °C to obtain the modified product.

[0243] The negative electrode material prepared in Comparative Example 3 has the following characteristics: median particle size of 5.36 µm, carbon content of 4.96 wt%, and tap density of 0.97 g / cm³. 3 It has a moisture content of 0.09%, a pH of 9.53, and a specific surface area of ​​1.99 m².2 / g.

[0244] In addition, the anode material prepared in Comparative Example 3 has one pore volume characteristic peak in the pore size ranges of 290Å~320Å, 340Å~390Å and 410Å~460Å respectively.

[0245] Comparative Example 4

[0246] A method for preparing a negative electrode material includes the following steps:

[0247] The difference from Example 2 is:

[0248] (2) The precursor is placed on the bias voltage stage in the plasma reaction chamber and evacuated to below 0.1 Pa. Then, a modified gas source is introduced at a flow rate of 2000 ml / min. The modified gas source is a mixture of hydrogen, argon and ammonia in a volume ratio of 1:1:0.03. After the pressure in the reaction chamber is controlled to 1500 Pa by the vacuum pump, the plasma is turned on to generate plasma light. At the same time, a bias voltage of -200 V is introduced into the reaction platform in the reaction chamber. After the plasma stabilizes, the pressure in the reaction chamber is further adjusted to maintain it at 1500 Pa. The reaction time is then started. The reaction time is 24 h and the reaction temperature is controlled between 400 °C and 450 °C to obtain the modified product.

[0249] The negative electrode material prepared in Comparative Example 3 has the following characteristics: median particle size of 5.03 µm, carbon content of 5.55 wt%, and tap density of 0.98 g / cm³. 3 It has a moisture content of 0.20%, a pH of 9.38, and a specific surface area of ​​1.79 m². 2 / g.

[0250] In addition, the anode material prepared in Comparative Example 4 has one pore volume characteristic peak in the pore size ranges of 290Å~320Å, 340Å~390Å and 410Å~460Å respectively.

[0251] Comparative Example 5

[0252] A method for preparing a negative electrode material includes the following steps:

[0253] The difference from Example 2 is:

[0254] (2) The precursor is placed on the bias voltage stage in the plasma reaction chamber and evacuated to below 0.1 Pa. Then, a modified gas source is introduced at a flow rate of 2000 ml / min. The modified gas source is a mixture of hydrogen, argon, ammonia, hydrogen sulfide and carbon tetrafluoride in a volume ratio of 1:1:0.01:0.03:0.01. After controlling the pressure in the reaction chamber to 2000 Pa by the vacuum pump, the plasma is turned on to generate plasma light. At the same time, a bias voltage of -200 V is introduced into the reaction platform in the reaction chamber. After the plasma stabilizes, the pressure in the reaction chamber is further adjusted to maintain it at 2000 Pa. The reaction time is 24 h and the reaction temperature is controlled between 400 °C and 450 °C to obtain the modified product.

[0255] The negative electrode material prepared in Comparative Example 3 has the following characteristics: median particle size of 5.58 µm, carbon content of 5.65 wt%, and tap density of 0.98 g / cm³. 3 It has a moisture content of 0.18%, a pH of 9.7, and a specific surface area of ​​2.18 m². 2 / g.

[0256] In addition, the anode material prepared in Comparative Example 5 has one pore volume characteristic peak in the pore size ranges of 240Å~280Å, 290Å~320Å, 340Å~390Å, and 410Å~460Å.

[0257] Comparative Example 6

[0258] A method for preparing a negative electrode material includes the following steps:

[0259] The difference from Example 2 is:

[0260] (2) The precursor is placed on the bias voltage stage in the plasma reaction chamber and evacuated to below 0.1 Pa. Then, a modified gas source is introduced at a flow rate of 4000 ml / min. The modified gas source is a mixture of hydrogen, argon, ammonia and carbon tetrafluoride in a volume ratio of 1:1:0.05:0.02. After controlling the pressure in the reaction chamber to 3000 Pa by the vacuum pump, the plasma is turned on to generate plasma light. At the same time, a bias voltage of -200 V is introduced into the reaction platform in the reaction chamber. After the plasma stabilizes, the pressure in the reaction chamber is further adjusted to maintain it at 3000 Pa. The reaction time is then started. The reaction time is 24 h and the reaction temperature is controlled between 450 °C and 500 °C to obtain the modified product.

[0261] The negative electrode material prepared in Comparative Example 3 has the following characteristics: median particle size of 5.6 µm, carbon content of 4.96 wt%, and tap density of 0.98 g / cm³. 3It has a moisture content of 0.22%, a pH of 9.83, and a specific surface area of ​​1.90 m². 2 / g.

[0262] In addition, the anode material prepared in Comparative Example 6 has one pore volume characteristic peak in the pore size ranges of 290Å~320Å, 340Å~390Å and 410Å~460Å respectively.

[0263] Comparative Example 7

[0264] A method for preparing a negative electrode material includes the following steps:

[0265] The difference from Example 2 is:

[0266] (2) The precursor is placed on the bias voltage stage in the plasma reaction chamber and evacuated to below 0.1 Pa. Then, a modified gas source is introduced at a flow rate of 1500 ml / min. The modified gas source is a mixture of hydrogen, argon, hydrogen sulfide and carbon tetrafluoride in a volume ratio of 1:1:0.05:0.01. After controlling the pressure in the reaction chamber to 1000 Pa by the vacuum pump, the plasma is turned on to generate plasma light. At the same time, a bias voltage of -200 V is introduced into the reaction platform in the reaction chamber. After the plasma stabilizes, the pressure in the reaction chamber is further adjusted to maintain it at 1000 Pa. The reaction time is then started. The reaction time is 24 h and the reaction temperature is controlled between 250 °C and 300 °C to obtain the modified product.

[0267] The negative electrode material prepared in Comparative Example 3 has the following characteristics: median particle size of 5.14 µm, carbon content of 4.75 wt%, and tap density of 0.98 g / cm³. 3 It has a moisture content of 0.09%, a pH of 9.43, and a specific surface area of ​​1.68 m². 2 / g.

[0268] Furthermore, the anode material prepared in Comparative Example 7 exhibits a large broad peak within the pore size range of 240 Å to 460 Å.

[0269] Comparative Example 8

[0270] A method for preparing a negative electrode material includes the following steps:

[0271] The difference from Example 2 is:

[0272] (2) The precursor is placed on the bias voltage stage in the plasma reaction chamber and evacuated to below 0.1 Pa. Then, a modified gas source is introduced at a flow rate of 3000 ml / min. The modified gas source is a mixture of hydrogen, argon and hydrogen sulfide in a volume ratio of 1:1:0.05. After the pressure in the reaction chamber is controlled to 2000 Pa by the vacuum pump, the plasma is turned on to generate plasma light. At the same time, a bias voltage of -200 V is introduced into the reaction platform in the reaction chamber. After the plasma stabilizes, the pressure in the reaction chamber is further adjusted to maintain it at 2000 Pa. The reaction time is 24 h and the reaction temperature is controlled between 350 °C and 450 °C to obtain the modified product.

[0273] The negative electrode material prepared in Comparative Example 3 has the following characteristics: median particle size of 5.37 µm, carbon content of 4.96 wt%, and tap density of 0.98 g / cm³. 3 It has a moisture content of 0.20%, a pH of 9.61, and a specific surface area of ​​1.93 m². 2 / g.

[0274] Furthermore, the anode material prepared in Comparative Example 8 exhibits a large broad peak within the pore size range of 240 Å to 460 Å.

[0275] Table 1: Content and proportion of non-metallic elements in the negative electrode materials corresponding to Examples 1-9 and Comparative Examples 1-8

[0276]

[0277] Table 2: Electrochemical performance characterization of the anode materials prepared in Examples 1-9 and Comparative Examples 1-8

[0278]

[0279] By combining Tables 1 and 2, and comparing Examples 1-9 with Comparative Examples 1-8, it can be concluded that: by using plasma-enhanced chemical vapor deposition to modify the surface of the anode material and adjusting the mass ratio of hydrogen, nitrogen, sulfur and halogen elements in the anode material, the capacity, initial coulombic efficiency, powder conductivity, cycle performance and rate performance of the anode material can be improved.

[0280] Specifically, by comparing Example 1 with Comparative Example 1, it can be concluded that: by using plasma-enhanced chemical vapor deposition to modify the surface of the anode material and controlling the mass ratio of hydrogen, nitrogen, sulfur and halogen elements in the anode material, the capacity, initial coulombic efficiency, powder conductivity, cycle performance and rate performance of the anode material can be comprehensively improved.

[0281] By comparing Comparative Examples 2-8 with Example 2, it can be concluded that in order to significantly improve the capacity, initial coulombic efficiency, powder conductivity, cycle performance, and rate performance of the anode material, the mass ratio of hydrogen to nitrogen, sulfur, and halogen elements in the anode material needs to be adjusted to an appropriate range.

[0282] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A negative electrode material, characterized in that, The anode material comprises a silicon-based active material and a carbon material, wherein the carbon material is located on at least a portion of the surface of the silicon-based active material, and the mass content of carbon in the anode material is 0.5 wt% to 15 wt%. The negative electrode material contains hydrogen, halogen, nitrogen, and sulfur elements. At least a portion of the hydrogen elements are bonded to the carbon elements to form carbon-hydrogen bonds, wherein the mass content of the hydrogen elements is m. H The mass content of the halogen element is m X The mass content of the sulfur element is m S The mass content of nitrogen element is m N And satisfy the following relationship: 0.02≤m X / m H ≤5.00, 0.69≤m N / m H ≤20.00, 0.05≤m S / m H ≤5.00; where, 50mg / kg≤m X ≤1500mg / kg, 100mg / kg≤m N ≤4000mg / kg, and 10mg / kg≤m S ≤200mg / kg; The negative electrode material contains pores; In the pore volume distribution curve of the negative electrode material, the pore size has characteristic peaks in the ranges of 240Å~280Å, 290Å~320Å, 340Å~390Å and 410Å~460Å.

2. The negative electrode material according to claim 1, characterized in that, The median particle size of the negative electrode material is 2.0 μm to 12.0 μm.

3. The negative electrode material according to claim 1, characterized in that, The silicon-based active material includes at least one of elemental silicon, silicon oxide, silicon alloy, and silicate.

4. The negative electrode material according to claim 3, characterized in that, The general formula of the silicon oxide is SiO x , 0 < x ≤ 2.

5. The negative electrode material according to claim 3, characterized in that, The silicon-based active material also includes a doped metal M, which is selected from at least one of Li, Mg, Al, Fe, La, Zn, Ti, Cu and Mn.

6. The negative electrode material according to claim 5, characterized in that, The mass content of metal M in the negative electrode material is 0wt% to 15wt%, excluding 0wt%.

7. The negative electrode material according to claim 1, characterized in that, The carbon material includes at least one of graphite, graphene, amorphous carbon, diamond-like carbon, carbon nanotubes, and carbon fibers.

8. The negative electrode material according to claim 1, characterized in that, A carbon material located on the surface of the silicon-based active material forms a carbon layer, the thickness of which is 20nm-1000nm.

9. The negative electrode material according to claim 1, characterized in that, The tap density of the negative electrode material is 0.75 g / cm³. 3 ~1.35g / cm 3 .

10. The negative electrode material according to claim 1, characterized in that, The powder conductivity of the negative electrode material under a pressure of 20 kN is 0.01 S / cm to 100.00 S / cm.

11. The negative electrode material according to claim 1, characterized in that, The specific surface area of ​​the negative electrode material is 0.50 m². 2 / g~10.00m 2 / g.

12. The negative electrode material according to claim 1, characterized in that, The water content in the negative electrode material is 0.01wt%~0.80wt%.

13. The negative electrode material according to claim 1, characterized in that, The pH of the negative electrode material is 6.00~12.

00.

14. A method for preparing a negative electrode material, characterized in that, Includes the following steps: A precursor is prepared, wherein the precursor comprises a silicon-based active material and a carbon material; In a modified gaseous source environment, the precursor is surface-modified using plasma-enhanced chemical vapor deposition to obtain the anode material; wherein... The modified gas phase source includes a reactant gas and a protective gas. The reactant gas includes hydrogen, a nitrogen-containing gas, a sulfur-containing gas, and a halogen source gas. In the modified gas phase source, the volume ratio of hydrogen to the protective gas is 1:(0.1-5), the volume ratio of hydrogen to the nitrogen-containing gas is 1:(0-1.2), the volume ratio of hydrogen to the sulfur-containing gas is 1:(0-0.2), and the volume ratio of hydrogen to the halogen source gas is 1:(0-0.05). The carbon content in the negative electrode material is 0.5 wt% to 15 wt%, and the hydrogen content in the negative electrode material is m. H The mass content of halogen elements is m X The mass content of sulfur is m S The mass content of nitrogen is m N And satisfy the following relationship: 0.02≤m X / m H ≤5.00, 0.69≤m N / m H ≤20.00, 0.05≤m S / m H ≤5.00; where, 50mg / kg≤m X ≤1500mg / kg, 100mg / kg≤m N ≤4000mg / kg, and 10mg / kg≤m S ≤200mg / kg; The negative electrode material contains pores; In the pore volume distribution curve of the negative electrode material, the pore size has characteristic peaks in the ranges of 240Å~280Å, 290Å~320Å, 340Å~390Å and 410Å~460Å.

15. The preparation method according to claim 14, characterized in that, The specific steps for preparing the precursor include mixing carbon material with silicon-based active material, such that at least a portion of the surface of the silicon-based active material is coated with carbon material.

16. The preparation method according to claim 15, characterized in that, The carbon material includes at least one of graphite, graphene, amorphous carbon, diamond-like carbon, carbon nanotubes, and carbon fibers.

17. The preparation method according to claim 15, characterized in that, The silicon-based active material includes at least one of elemental silicon, silicon oxide, silicon alloy, and silicate.

18. The preparation method according to claim 15, characterized in that, The silicon-based active material includes a doped metal M, where M is selected from at least one of Li, Mg, Al, Fe, La, Zn, Ti, Cu, and Mn.

19. The preparation method according to claim 14, characterized in that, Before performing surface modification treatment on the precursor using plasma-enhanced chemical vapor deposition, the preparation method further includes purifying the precursor.

20. The preparation method according to claim 19, characterized in that, The specific steps of the purification process include washing and drying the precursor sequentially.

21. The preparation method according to claim 20, characterized in that, The detergent used in the washing process is deionized water.

22. The preparation method according to claim 20, characterized in that, The drying temperature for the drying process is 45℃~80℃, and the drying time is 3h~48h.

23. The preparation method according to claim 14, characterized in that, In a modified gas source environment, the steps of surface modification treatment of the precursor by plasma-enhanced chemical vapor deposition include: evacuating the vacuum, placing the precursor under the modified gas source, and performing plasma-enhanced chemical vapor deposition on the precursor under the action of a bias voltage.

24. The preparation method according to claim 23, characterized in that, The bias voltage ranges from -500V to 0V, excluding 0V.

25. The preparation method according to claim 23, characterized in that, The pressure of the vacuum is less than 1.0 Torr.

26. The preparation method according to claim 23, characterized in that, The working pressure for the plasma-enhanced chemical vapor deposition is 500 Pa to 5000 Pa.

27. The preparation method according to claim 23, characterized in that, The deposition temperature of the plasma-enhanced chemical vapor deposition is 200℃~800℃.

28. The preparation method according to claim 23, characterized in that, The flow rate of the modified gas source is 200 ml / min to 5000 ml / min.

29. The preparation method according to claim 14, characterized in that, The nitrogen-containing gas includes one or more of nitrogen and ammonia, and / or the sulfur-containing gas includes hydrogen sulfide, and / or the halogen source gas includes one or more of fluorine, chlorine, bromine, iodine, hydrogen bromide, hydrogen iodide, and carbon tetrafluoride.

30. The preparation method according to claim 14, characterized in that, The protective gas includes one or more of argon, krypton, nitrogen, neon, and helium.

31. The preparation method according to claim 14, characterized in that, The powder conductivity of the precursor under 20KN pressure is 0.001S / cm to 0.1S / cm, and the powder conductivity of the negative electrode material under 20KN pressure is 0.1S / cm to 100.0S / cm.

32. A battery, characterized in that, It includes the negative electrode material as described in any one of claims 1-13, or the negative electrode material prepared by the preparation method as described in any one of claims 14-31.

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