Anode materials and batteries

Abstract

The present disclosure provides an anode material and a battery, the anode material comprising an active material, the active material comprising a carbon matrix and a silicon material, the anode material containing oxygen and nitrogen, the mass content of the oxygen being A%, the mass content of the nitrogen being B%, the powder conductivity of the anode material being PS / m and satisfying the relationship (A+B) / P≦3. The anode material provided by the present disclosure is advantageous in reducing the gassing phenomenon of the anode material while maintaining relatively high electronic conductivity.

Description

[Technical Field]

[0001] This disclosure claims priority to Chinese Patent Application No. 202311720241.9, filed December 13, 2023, and Chinese Patent Application No. 202410388496.8, filed March 29, 2024. This disclosure incorporates the entire text of the above Chinese patent applications by reference.

[0002] The present disclosure relates to the field of anode materials, and more particularly to anode materials and batteries. [Background technology]

[0003] Lithium-ion batteries have advantages such as high energy density, long cycle life, minimal environmental pollution, and no memory effect, making them widely used in electric vehicles and consumer electronics. In recent years, the rapid development of electric vehicles has led to an increasing demand for lithium-ion batteries with higher energy densities, prompting researchers to explore battery materials with higher energy densities and better cycle performance. Cathode and anode materials are the core of a battery and determine its operating efficiency. Currently, the most commercially available anode material is graphite, whose capacity is already close to its theoretical upper limit and has limited room for further improvement. Therefore, the development of a new generation of high-energy-density anode materials is highly desired. Silicon anode materials are generally considered to be the next-generation battery anode material, boasting advantages such as high capacity, abundant sources, and relative safety.

[0004] Silicon anodes are generally considered the next generation of battery anode materials, boasting advantages such as high capacity, abundant resources, and relative safety. However, silicon anodes experience a severe volume expansion effect during cycling, which can lead to material pulverization and shattering, resulting in rapid cycling decay. Silicon-carbon composites are typically used to suppress the volume expansion of silicon, but silicon-carbon anode materials suffer from gas generation issues during the sheet manufacturing process, posing security risks and limiting their application.

[0005] Therefore, how to improve the conductive performance of the negative electrode material and reduce the gas generation value of the negative electrode material is currently an urgent issue. Summary of the Invention [Problem to be solved by the invention]

[0006] The present disclosure provides a negative electrode material and a battery that are advantageous in reducing the gassing phenomenon of the negative electrode material while maintaining relatively high electronic conductivity. [Means for solving the problem]

[0007] The present disclosure provides a negative electrode material, the negative electrode material comprising an active material, the active material comprising a carbon matrix and a silicon material, the negative electrode material containing oxygen and nitrogen, the mass content of the oxygen being A%, the mass content of the nitrogen being B%, the powder conductivity of the negative electrode material being PS / m, and satisfying the relationship (A+B) / P≦3. [Effects of the Invention]

[0008] The technical solution of the present disclosure has at least the following beneficial effects:

[0009] The negative electrode material provided by the present disclosure includes an active material, which includes a carbon matrix and a silicon material, and is useful for improving the capacity of the negative electrode material. Furthermore, the negative electrode material contains small amounts of oxygen and nitrogen. The small amounts of nitrogen and oxygen can provide lone pairs of electrons, which can participate in the π-π conjugated system of the carbon matrix, thereby forming a larger p-π conjugated system and further increasing the electronic conductivity of the negative electrode material. However, the presence of oxygen and nitrogen easily reacts with solvent molecules or hydrogen radicals in the electrolyte to produce several gases (e.g., CO2, CO, NH2, etc.), and gassing can affect the safety performance of the battery. Therefore, the present disclosure controls (A+B) / P≦3 within this range to control the relationship between the mass content of oxygen and nitrogen and the electronic conductivity of the negative electrode material, which is advantageous for reducing the gassing phenomenon of the negative electrode material while maintaining relatively high electronic conductivity. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a process flow chart of a method for producing a negative electrode material provided by the present disclosure. [Figure 2] FIG. 1 is an XRD diagram of the negative electrode material prepared in Example 1 of the present disclosure. [Figure 3] FIG. 2 is a schematic diagram of the initial charge-discharge curve of the negative electrode material prepared in Example 1 of the present disclosure. [Figure 4] FIG. 1 is a schematic diagram of the cycle performance curve of the negative electrode material prepared in Example 1 of the present disclosure. [Figure 5] FIG. 10 is an XRD diagram of the negative electrode material prepared in Example 10 of the present disclosure. [Figure 6] 10 is an initial charge-discharge curve of the negative electrode material prepared in Example 10 of the present disclosure. [Figure 7] 10 is a cycle performance curve of the negative electrode material prepared in Example 10 of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] In order to better explain the present disclosure and facilitate understanding of the technical solutions of the present disclosure, the present disclosure will be described in more detail below. However, the following examples are merely simple examples of the present disclosure, and do not represent or limit the scope of the claims of the present disclosure, and the protection scope of the present disclosure shall be governed by the scope of the claims.

[0012] In a first aspect, the present disclosure provides a negative electrode material, the negative electrode material including an active material, the active material including a carbon matrix and a silicon material, the negative electrode material containing an oxygen element and a nitrogen element, the mass content of the oxygen element being A%, the mass content of the nitrogen element being B%, the powder conductivity of the negative electrode material being PS / m, and satisfying the relationship (A+B) / P≦3.

[0013] The negative electrode material provided by the present disclosure includes an active material, the active material including a carbon matrix and a silicon material, and the negative electrode material contains oxygen and nitrogen elements, and the nitrogen and oxygen elements can provide lone pairs of electrons, which can participate in the π-π conjugated system of the carbon matrix, thereby forming a larger p-π conjugated system and further increasing the electronic conductivity of the negative electrode material. However, the presence of oxygen and nitrogen elements is likely to react with solvent molecules or hydrogen radicals in the electrolyte to produce several gases (e.g., CO2, CO, NH2, etc.), and the gassing phenomenon affects the safety performance of the battery. Therefore, the mass content of oxygen and nitrogen elements in the negative electrode material disclosed herein and the electronic conductivity of the negative electrode material satisfy the relationship (A + B) / P≦3, which is advantageous for reducing the gassing phenomenon of the negative electrode material while maintaining a relatively high electronic conductivity.

[0014] In some embodiments, the silicon material comprises silicon particles.

[0015] In some embodiments, the silicon material comprises silicon particles and a silicon oxide layer located on the surface of the silicon particles. The silicon oxide layer comprises silicon oxide, which has the general formula SiO x where 0.5≦x<2. Specifically, SiO x Specifically, SiO 0.5, SiO 0.7 , SiO 0.9 , SiO, SiO 1.2 , SiO 1.5 , SiO 1.8 , SiO 1.9 etc., and are not limited thereto.

[0016] In some embodiments, the silicon material includes silicon particles and a silicon oxide layer located on the surface of the silicon particles. When the mass of the silicon material is calculated as 100%, the mass percentage of the oxygen element in the silicon material is 1% to 18%. Specifically, the mass percentage of the oxygen element in the silicon material may be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, or 18%, etc., but is not limited thereto. Controlling the mass percentage of the oxygen element in the silicon material within the above range is beneficial to forming a stable silicon oxide layer on the surface of the silicon particles, reducing direct contact between the silicon particles and the electrolyte and further reducing side reactions between the silicon material and the electrolyte, improving the cycling stability of the anode material, ensuring stable activity of the silicon material, and improving the specific capacity of the anode material.

[0017] In some embodiments, the silicon particles include at least one of elemental silicon, silicon oxide, silicon alloy, and silicon carbon composite. Specifically, the elemental silicon may be, but is not limited to, amorphous silicon, crystalline silicon, or a composite of crystalline silicon and amorphous silicon. The silicon alloy may be, but is not limited to, a silicon-lithium alloy, a silicon-magnesium alloy, a silicon-nickel alloy, and the like.

[0018] In some embodiments, the silicon particles have an average particle size of 0.1 nm to 500 nm, specifically 1 nm, 5 nm, 10 nm, 50 nm, 100 nm, 150 nm, 200 nm, 300 nm, 350 nm, 400 nm, or 500 nm, and may have other values ​​within the above range, without limitation. Silicon particles of an appropriate size can improve the uniformity of the distribution of the silicon particles and the carbon matrix, reduce the segregation of silicon particles, and improve the cycle performance of the negative electrode material. Preferably, the average particle size of the silicon particles is 1 nm to 10 nm, and more preferably, the average particle size of the silicon particles is 1 nm to 5 nm.

[0019] In some embodiments, the mass content of elemental silicon in the silicon particles is ≧99%, which is advantageous for improving the purity of the silicon particles and reducing impurities.

[0020] In some embodiments, the shape of the silicon particles includes at least one of dots, spheres, ellipses, and sheets, and the shape of the silicon particles can be selected according to actual needs and is not limited thereto.

[0021] In some embodiments, the active material includes a carbon matrix and silicon particles, the carbon matrix having pores, and at least some of the silicon particles distributed within the pores of the carbon matrix.

[0022] The negative electrode material provided by the present disclosure contains an active material, the active material contains a carbon matrix and silicon particles, the carbon matrix has pores, and at least some of the silicon particles are distributed in the pores of the carbon matrix, which can improve the capacity of the negative electrode material. Moreover, the negative electrode material contains oxygen elements and nitrogen elements. The doping of nitrogen elements and oxygen elements can provide lone pairs of electrons, and the lone pairs of electrons can participate in the π-π conjugation system of the carbon matrix, thereby forming a larger p-π conjugation system and further increasing the electronic conductivity of the negative electrode material. However, the presence of oxygen elements and nitrogen elements is likely to react with solvent molecules or hydrogen radicals in the electrolyte to generate some gases (such as CO2, CO, NH2, etc.), and the gas generation phenomenon affects the safety performance of the battery. Therefore, the mass content of oxygen elements and nitrogen elements in the negative electrode material of the present disclosure and the electronic conductivity of the negative electrode material satisfy (A + B) / P ≤ 3. Controlling the relationship between the mass content of oxygen elements and nitrogen elements and the electronic conductivity of the negative electrode material is advantageous for reducing the gas generation phenomenon of the negative electrode material on the premise of maintaining a relatively high electronic conductivity. The pores present in the carbon matrix and the distribution of silicon particles in the pores of the carbon matrix are advantageous for alleviating the volume expansion of silicon particles in the cycle process of the negative electrode material, maintaining the structural stability of the negative electrode material, reducing the collapse of the material structure due to volume expansion in the process of lithium release of the negative electrode material, and the pores of the carbon matrix in the negative electrode material can also adsorb a small amount of gas, further reducing the gas generation phenomenon of the negative electrode material, and further improving the cycle performance of the negative electrode material.

[0023] In some embodiments, in the negative electrode material, the mass content of oxygen elements is A%, 0 < A ≤ 3, and the possible values of A may specifically be 0.1, 0.2, 0.4, 0.5, 0.8, 1, 1.2, 1.5, 1.8, 2.0, 2.2, 2.5, 2.8 or 3, etc., and are not limited herein. Preferably, the mass content of oxygen elements is 0 < A% ≤ 1.5%.

[0024] In some embodiments, in the negative electrode material, the mass content of nitrogen element is B%, where 0 < B ≤ 3. The possible values of B may specifically be 0.1, 0.2, 0.4, 0.5, 0.8, 1, 1.2, 1.5, 1.8, 2.0, 2.2, 2.5, 2.8 or 3, etc., and are not limited herein. Controlling the content of nitrogen element in the negative electrode material within the above range can improve the specific capacity of the carbon matrix. Preferably, the mass content of nitrogen element is 0.1% ≤ B% ≤ 0.5%.

[0025] In some embodiments, the carbon matrix includes at least one of hard carbon, soft carbon, graphite, mesocarbon microbeads, activated carbon, porous carbon, mesoporous carbon and carbon gel.

[0026] In some embodiments, the carbon matrix has functional groups on its surface and / or inside the pores, and the functional groups include at least one of hydroxyl group, carboxyl group, carbonyl group, ester group, cyclic ester group and amino group.

[0027] In some embodiments, nitrogen element and oxygen element exist on the surface and / or inside the pores of the carbon matrix in the form of atomic doping. Specifically, it may be at the defects inside and / or on the surface of the carbon matrix.

[0028] In some embodiments, the total pore volume of the carbon matrix is ≥ 0.4 cm 3 / g, specifically 0.4 cm 3 / g, 0.5 cm 3 / g, 0.8 cm 3 / g, 1 cm 3 / g, 1.1 cm 3 / g, 1.3 cm 3 / g, 1.5 cm 3 / g or 1.8 cm 3 / g, etc., and of course other values within the above range are also possible and are not limited herein. Preferably, the total pore volume of the carbon matrix is ≥ 0.5 cm 3 / g, and more preferably, the total pore volume of the carbon matrix is ≥ 0.7 cm3 / g.

[0029] In some embodiments, the pores in the carbon matrix include micropores with a pore size of less than 2 nm, and the micropore percentage is ≥ 80%. Specifically, the micropore percentage may be 80%, 82%, 85%, 88%, 90%, 92%, 93%, 95%, 98%, or 99%, etc., without limitation. It is understood that the size of the silicon particles deposited in the pores of the carbon matrix is ​​determined by the size of the pores. The higher the percentage of micropores, the smaller the average pore size of the pores in the carbon matrix and the smaller the particle size of the silicon particles deposited in the pores of the carbon matrix. A smaller particle size of the silicon particles deposited in the carbon matrix pores reduces the volume expansion of the negative electrode material during cycling, which is advantageous for improving the cycling performance of the negative electrode material. Preferably, the micropore percentage is ≥ 90%, and more preferably, the micropore percentage is ≥ 95%.

[0030] In some embodiments, the average pore size of the pores in the carbon matrix is ​​≦5 nm, and may be, for example, 0.1 nm, 0.5 nm, 1 nm, 1.5 nm, 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm, 4.5 nm, or 5 nm, and may of course be other values ​​within the above range, without limitation. As will be understood, the average pore size of the pores in the carbon matrix affects the grain size of the silicon particles located therein, and controlling the average pore size of the pores in the carbon matrix can adjust the grain size of the silicon particles and reduce the phenomenon of excessive expansion stress caused by localized silicon particle deposition. Preferably, the average pore size of the pores in the carbon matrix is ​​≦2 nm, and more preferably, the average pore size of the pores in the carbon matrix is ​​≦1.8 nm.

[0031] In some embodiments, the porosity of the carbon matrix is ​​40% to 60%, and may be, for example, 40%, 41%, 43%, 45%, 48%, 50%, 52%, 54%, 56%, 58%, or 60%, and of course, may be other values ​​within the above range and are not limited thereto.

[0032] In some embodiments, 150 mL of a 20% mass fraction HF acid solution is added dropwise to 10 g of anode material while stirring to produce SiF and H gas, releasing heat. The supernatant acid solution is centrifuged until no more gas is produced. Another 150 mL of a 20% mass fraction HF acid solution is added to the anode material. After stirring for 12 hours, the supernatant acid solution is centrifuged again. The anode material is then washed with pure water until neutral and dried, yielding a silicon particle-removed anode material, i.e., a carbon matrix.

[0033] In some embodiments, the negative electrode material further comprises a carbon material located on at least a portion of the surface of the active material. As can be understood, the carbon material can act as a buffer layer to reduce the volume expansion effect of the negative electrode material to a certain extent and improve the electrical conductivity of the negative electrode material. The carbon material can also reduce direct contact between the active material and the electrolyte, inhibit excessive growth of the SEI film on the surface of the negative electrode material, stabilize the interface of the negative electrode material, and improve the Coulomb efficiency of the negative electrode material.

[0034] In some embodiments, the carbon material comprises at least one of graphitic carbon and amorphous carbon. The presence of the carbon material on the surface of the active material can improve the electrical conductivity of the anode material, stabilize the interface of the anode material, reduce direct contact between the silicon particles and the electrolyte, reduce the occurrence of side reactions, and improve the rate and cycle performance of the anode material.

[0035] In some embodiments, the median diameter D of the negative electrode material 50The range of ≦10 μm may be, for example, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm, and may also be other values ​​within the range, and is not limited thereto. As will be understood, controlling the median diameter of the negative electrode material within the range described above is advantageous in improving the cycle performance of the negative electrode material.

[0036] In some embodiments, the specific surface area of ​​the negative electrode material is ≦5 m 2 / g, specifically 0.1m 2 / g, 0.5m 2 / g, 1m 2 / g, 1.5m 2 / g, 2m 2 / g, 2.5m 2 / g, 3m 2 / g, 3.5m 2 / g, 4m 2 / g, 4.5m 2 / g or 5m 2 / g, etc., and of course, other values ​​within the above range are also possible, and are not limited thereto. Controlling the specific surface area of ​​the negative electrode material within the above range is advantageous in improving the initial efficiency and cycle performance of a lithium battery manufactured using the negative electrode material.

[0037] In some embodiments, the gas generation rate of the negative electrode material over 6 days is M mL / g, where M≦0.2. The gas generation rate of the negative electrode material may be, for example, 0.2 mL / g, 0.18 mL / g, 0.15 mL / g, 0.12 mL / g, 0.10 mL / g, 0.08 mL / g, 0.05 mL / g, or 0.01 mL / g, and may be other values ​​within the above range, without limitation. Controlling the gas generation rate of the negative electrode material within the above range can improve the cycle stability and safety of the negative electrode material.

[0038] The gas generation rate of the negative electrode material was tested by adding 20 g of the negative electrode material to 50 g of styrene-butadiene rubber solution to obtain a mixed solution, which was then packaged in an aluminum plastic film and placed in a 2000 mL sealed container and stored at 45°C. The gas generation rate of the negative electrode material after 6 days was M mL / g.

[0039] In some embodiments, the powder conductivity of the negative electrode material is PS / m, where P≧0.01 S / m. The powder conductivity may be specifically 0.01 S / m, 0.02 S / m, 0.03 S / m, 0.05 S / m, 0.08 S / m, 0.1 S / m, 0.2 S / m, or 1 S / m, etc., and of course, other values ​​within the above ranges may also be used and are not limited thereto.

[0040] In some embodiments, the negative electrode material further comprises elemental sulfur, and the content of elemental sulfur in the negative electrode material is S ppm, where 0 <S≦20ppmである。

[0041] First, the above negative electrode material contains a small amount of oxygen element and nitrogen element. The small amount of nitrogen element and oxygen element can provide lone pairs of electrons, and the lone pairs of electrons can participate in the π-π conjugate system of the carbon matrix. Thereby, a larger p-π conjugate system can be formed to further increase the electronic conductivity of the negative electrode material. However, due to the presence of oxygen element and nitrogen element, the battery manufactured with the negative electrode material is likely to react with solvent molecules or hydrogen radicals in the electrolyte to generate some gases (such as CO2, CO, NH2, etc.). The gas generation phenomenon affects the safety performance of the battery. Therefore, the negative electrode material is doped with nitrogen and oxygen and sulfur element, and the content of sulfur element in the negative electrode material is 0 < S ≤ 20 ppm. Since sulfur element has a relatively large atomic radius, it can form a C-S bond with carbon element in the negative electrode material that has lithium storage activity, and can further expand the distance between carbon layers of the carbon matrix after doping with nitrogen and oxygen elements. The conductivity of the carbon matrix is higher. Also, sulfur element combines with oxygen element to form an inactive S-O bond, which can reduce the problem of gas generation due to the reaction between the battery manufactured with the negative electrode material and the electrolyte. Moreover, after doping with sulfur element, the relationship between the content A% of oxygen element, the content B% of nitrogen element and the powder conductivity P satisfies (A + B) / P ≤ 3. The doping of nitrogen, oxygen and sulfur improves the powder conductivity of the negative electrode material and alleviates the problem that too high content of nitrogen and oxygen leads to more gas generation due to the reaction between the battery manufactured with the negative electrode material and the electrolyte, so that the negative electrode material has excellent conductivity and cycle performance.

[0042] In some embodiments, the sulfur content of the negative electrode material is 0 < S ≤ 20 ppm. Optionally, the sulfur content of the negative electrode material may specifically be 20 ppm, 17 ppm, 14 ppm, 11 ppm, 9 ppm, 6 ppm, etc., or other values within the range, and can be selected according to actual requirements, which is not limited here. As understood, the sulfur content of the negative electrode material is within the above range, which can improve the conductivity of the negative electrode material and reduce the gas generation value due to the reaction between the battery manufactured with the negative electrode material and the electrolyte, and the sulfur doping amount is not too much to affect the structural stability of the carbon matrix.

[0043] In some embodiments, the mass content of oxygen element is A%≦3%, and optionally, the mass content of oxygen element may be specifically 3%, 2.5%, 2%, 1.5%, 1%, 0.5%, 0.3%, etc., or other values ​​within the range, which can be selected according to actual needs and are not limited thereto. It is understood that the mass content of oxygen element within the above range can reduce the amount of gas generated by reaction with the electrolyte during the charge and discharge process of a battery manufactured using the negative electrode material, thereby improving the cycle performance of the battery manufactured using the negative electrode material. Preferably, the mass content of oxygen element is ≦1%, and more preferably, the mass content of oxygen element is ≦0.5%.

[0044] In some embodiments, the mass content of nitrogen element is B%≦3%, and optionally, the mass content of nitrogen element may be specifically 3%, 2.5%, 2%, 1.5%, 1%, 0.5%, 0.3%, etc., or other values ​​within the range, which can be selected according to actual needs and are not limited thereto. The mass content of nitrogen element in the present disclosure is within the above range, and the nitrogen doping content improves the conductivity and electrocatalytic activity of the negative electrode material. Preferably, the mass content of nitrogen element is ≦1%, and more preferably, the mass content of nitrogen element is ≦0.5%.

[0045] In some embodiments, the powder conductivity P of the negative electrode material is 10 -1 S / cm≦10 4 S / cm, and optionally, the powder conductivity of the negative electrode material is specifically 10 -1 S / cm, 10S / cm, 10 2 S / cm, 10 3 S / cm and 10 4S / cm, or other values ​​within the range, which can be selected according to actual needs and are not limited thereto. As can be understood, when the powder conductivity P of the negative electrode material is within the above range, the negative electrode material can more efficiently transmit lithium ions, and during the initial charge / discharge process of a battery manufactured using the negative electrode material, more lithium ions can participate in the reversible charge / discharge reaction, reducing irreversible capacity loss and thereby improving the initial coulombic efficiency of the battery manufactured using the negative electrode material.

[0046] In some embodiments, the pores in the negative electrode material include micropores, i.e., pores with a pore size of less than 2 nm, and wherein the volume of the micropores in the negative electrode material accounts for ≦20% of the total pore volume of the negative electrode material.

[0047] In some embodiments, the proportion of the micropore volume of the negative electrode material to the total pore volume of the negative electrode material is ≦5%. Optionally, the proportion of the micropore volume to the total pore volume of the negative electrode material may be, for example, 5%, 4%, 3%, 2%, 1%, etc., or other values ​​within the range, which can be selected according to actual needs and are not limited thereto. It is understood that a micropore volume proportion of the negative electrode material within the above range can improve the specific surface area of ​​the negative electrode material, provide more active sites for lithium ion absorption and desorption, and thereby improve the reversible capacity of the negative electrode material.

[0048] In some embodiments, the pores in the negative electrode material include mesopores, i.e., pores with a pore size of 2 nm to 50 nm, where the volume of the mesopores in the negative electrode material accounts for 87% to 97% of the total pore volume of the negative electrode material. Optionally, the volume of the mesopores in the negative electrode material may be 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, etc., or other values ​​within the range, which can be selected according to actual needs and are not limited thereto. It can be understood that a volume of the mesopores in the negative electrode material within the above range is favorable for rapid diffusion of lithium ions and provides sufficient space for silicon particles to accommodate volume changes occurring during the charge and discharge process, thereby improving the cycle stability of the negative electrode material.

[0049] In some embodiments, the pores in the negative electrode material include macropores, i.e., pores with a pore diameter greater than 50 nm, wherein the volume of the macropores in the negative electrode material accounts for ≦10% of the total pore volume of the negative electrode material. Optionally, the volume of the macropores in the negative electrode material may be specifically 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, etc., or may be other values ​​within the range, which can be selected according to actual needs and are not limited thereto. As will be understood, when the volume of the macropores in the negative electrode material accounts for the total pore volume of the negative electrode material within the above range, the diffusion rate of lithium ions can be improved.

[0050] In some embodiments, the average pore size of the pores in the negative electrode material is 0.5 nm to 20 nm. Optionally, the average pore size of the pores in the negative electrode material may be specifically 0.5 nm, 2 nm, 4 nm, 6 nm, 8 nm, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm, 20 nm, etc., or other values ​​within the range, which can be selected according to actual requirements and are not limited herein.

[0051] In some embodiments, the total pore volume of the negative electrode material is less than or equal to 0.001 cm 3 / g~0.1cm 3 / g, and optionally, the total pore volume of the negative electrode material is specifically 0.001 cm 3 / g, 0.01cm 3 / g, 0.02cm 3 / g, 0.03cm 3 / g, 0.04cm 3 / g, 0.05cm 3 / g, 0.06cm 3 / g, 0.07cm 3 / g, 0.08cm 3 / g, 0.09cm 3 / g and 0.1cm 3 / g, or may be any other value within the range, which can be selected according to actual needs and is not limited thereto. As can be understood, the total pore volume of the negative electrode material within the above range not only improves the specific capacity of the negative electrode material, but also retains an appropriate amount of voids in the negative electrode material to mitigate the volume expansion caused by the active material during the lithium release process, which is advantageous for improving the cycle performance of the negative electrode material.

[0052] In some embodiments, the pores in the negative electrode material after silicon particle removal include micropores, and the proportion of the micropores in the negative electrode material after silicon particle removal to the total pore volume of the negative electrode material after silicon particle removal is ≥ 80%. Optionally, the proportion of the micropores in the negative electrode material after silicon particle removal to the total pore volume of the negative electrode material after silicon particle removal may be specifically 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 96%, 98%, etc., or may be other values ​​within the range, which can be selected according to actual requirements and is not limited herein.

[0053] In some embodiments, the method for preparing the anode material after removing the silicon particles includes the steps of adding a 1 M nitric acid solution to the anode material and immersing it for 1 hour, then adding a 20% mass fraction HF acid solution dropwise onto the anode material until yellow smoke is generated and the solution no longer generates yellow smoke, and repeating the steps multiple times; and finally decomposing the residue with a 1 M nitric acid solution, followed by washing and drying to obtain the anode material after removing the silicon particles, i.e., the carbon matrix.

[0054] In some embodiments, a method for producing the anode material after silicon particle removal includes adding 150 mL of a 20% mass fraction HF acid solution dropwise to 10 g of the anode material while stirring to produce SiF and H gases, releasing heat, and centrifuging the supernatant acid solution until no more gas is produced. Another 150 mL of the 20% mass fraction HF acid solution is added to the anode material, and after stirring for 12 hours, the supernatant acid solution is again centrifuged. Subsequently, the anode material is washed with pure water until neutral and dried, thereby obtaining the anode material after silicon particle removal, i.e., the carbon matrix.

[0055] As can be seen, the particle size of the silicon particles deposited in the pores of the carbon matrix is ​​affected by the size of the pores; the higher the proportion of micropores, the smaller the average pore size of the carbon matrix pores and the smaller the particle size of the silicon particles deposited in the pores of the carbon matrix. Smaller particle sizes of silicon particles deposited in the pores of the carbon matrix result in less volume expansion of the negative electrode material during cycling, which is advantageous for improving the cycling performance of the negative electrode material. Preferably, the proportion of micropores is ≥ 90%, and more preferably, the proportion of micropores is ≥ 95%.

[0056] In some embodiments, in the negative electrode material after silicon particle removal, the proportion of pores with a pore size in the range of 2 nm to 5 nm to the total pore volume of the negative electrode material after silicon particle removal is 0% to 10%. Optionally, the proportion of pores with a pore size in the range of 2 nm to 5 nm to the total pore volume of the negative electrode material after silicon particle removal may be 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, etc., or may be other values ​​within the range, and may be selected according to actual needs and is not limited herein.

[0057] In some embodiments, the average pore size of the negative electrode material after removing the silicon particles is ≦5 nm. Optionally, the average pore size of the negative electrode material after removing the silicon particles may be specifically 5 nm, 4 nm, 3 nm, 2 nm, 1 nm, etc., or other values ​​within the range, which can be selected according to actual needs and are not limited herein.

[0058] In some embodiments, the total pore volume of the negative electrode material after removal of the silicon particles is less than or equal to 0.2 cm 3 / g~2cm 3 / g, and optionally, the total pore volume of the negative electrode material after removal of the silicon particles is specifically 0.2 cm 3 / g, 0.4cm 3 / g, 0.6cm 3 / g, 0.8cm 3 / g, 1cm 3 / g, 1.2cm 3 / g, 1.4cm 3 / g, 1.6cm 3 / g, 1.8cm 3 / g and 2cm 3 / g, or other values ​​within the range, which can be selected according to actual needs and are not limited thereto. As can be understood, the negative electrode material after removing the silicon particles is a carbon matrix, and controlling the total pore volume of the carbon matrix within the above range can not only ensure the structural strength of the carbon matrix, but also reserve sufficient voids to be used for filling the silicon particles, and the negative electrode material after combining the carbon matrix and the silicon particles can have excellent rate performance and cycle performance.

[0059] In some embodiments, the particle size of the negative electrode material is 2 μm≦D 50 ≦20μm, 0.9≦(D 90 -D 10 ) / D 50 ≦5, where the particle size D of the negative electrode material 50 Specifically, (D 90 -D 10 ) / D 50 Specifically, (D) may be 0.9, 1, 2, 3, 4, 5, etc., or may be other values ​​within the range, which can be selected according to actual requirements and are not limited thereto. 90 -D 10 ) / D 50reflects the particle size distribution span of the negative electrode material. If the particle size distribution span is too small, the selection and production costs of the negative electrode material will be high. If the particle size distribution span is too large, the particle size distribution of the negative electrode material will be broad, causing uneven volume changes in the cycling process of batteries made with the negative electrode material.

[0060] In some embodiments, the specific surface area of ​​the negative electrode material is 1 m 2 / g~10m 2 / g, and optionally, the specific surface area of ​​the negative electrode material is specifically 1 m 2 / g, 2m 2 / g, 3m 2 / g, 4m 2 / g, 5m 2 / g, 6m 2 / g, 7m 2 / g, 8m 2 / g, 9m 2 / g and 10m 2 / g, or other values ​​within the range, which can be selected according to actual needs and are not limited thereto. As can be understood, the specific surface area of ​​the negative electrode material within the above range can provide more absorption sites for lithium ions to improve the capacity of the lithium ion battery, and can also reduce the contact area between the battery manufactured with the negative electrode material and the electrolyte, thereby further reducing the occurrence of side reactions and improving the cycle performance of the battery manufactured with the negative electrode material.

[0061] In some embodiments, the green density of the negative electrode material is 0.80 cm 3 / g~1.30cm 3 / g, and optionally, the green density of the negative electrode material is specifically 0.80 cm 3 / g, 0.90cm 3 / g, 1cm 3 / g, 1.1cm 3 / g, 1.2cm 3 / g and 1.3cm 3 / g, or other values ​​within the range, which can be selected according to actual needs and are not limited thereto. As can be understood, when the green density of the negative electrode material is within the above range, a unit volume of the negative electrode sheet can accommodate more negative electrode material, which helps to improve the volumetric energy density of the battery.

[0062] In some embodiments, the tap density of the negative electrode material is 0.5 cm 3 / g~1.5cm 3 / g, and optionally the tap density of the negative electrode material is specifically 0.5 cm 3 / g, 0.7cm 3 / g, 0.9cm 3 / g, 1.1cm 3 / g, 1.3cm 3 / g and 1.5cm 3 / g, or other values ​​within the range, which can be selected according to actual requirements and are not limited herein.

[0063] In some embodiments, the mass content of carbon element in the negative electrode material is 40% to 60%. Optionally, the mass content of carbon element in the negative electrode material may be specifically 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, etc., or may be other values ​​within the range, which can be selected according to actual requirements and is not limited herein.

[0064] In some embodiments, the mass content of silicon element in the negative electrode material is 35% to 55%. Optionally, the mass content of silicon element in the negative electrode material may be specifically 35%, 37%, 39%, 41%, 43%, 45%, 47%, 49%, 51%, 53%, 55%, etc., or other values ​​within the range, which can be selected according to actual requirements and are not limited herein.

[0065] In some embodiments, the carbon matrix has pores, and at least some of the silicon particles are distributed within the pores of the carbon matrix. The silicon particle active material is packed into the pores of the carbon material, ensuring a uniform distribution of the silicon particle active material and the carbon matrix, improving the specific capacity of the anode material. Meanwhile, the carbon material has fewer voids after being packed with the silicon particle active material, improving the density of the anode material, effectively reducing side reactions between the electrolyte and a battery manufactured with the anode material, and further improving the cycle performance of a battery manufactured with the anode material.

[0066] In some embodiments, the carbon matrix comprises at least one of amorphous carbon, graphitized carbon, mesocarbon microbeads, and carbon gel, where the amorphous carbon comprises at least one of hard carbon, soft carbon, and activated carbon, and the graphitized carbon comprises at least one of graphite and graphitized carbon nanotubes. The type of carbon matrix can be selected according to actual requirements and is not limited thereto.

[0067] In some embodiments, the carbon matrix contains functional groups at at least one of the surface, the carbon-carbon skeleton, the interstices between the carbon layers, and the lattice defects, and the functional groups contain at least one of oxygen, nitrogen, and sulfur, where the functional groups include at least one of hydroxyl, carboxyl, carbonyl, ester, endocyclic ester, amino, mercapto, sulfate, sulfite, thioether, and sulfonic acid groups. The type of functional group can be selected according to actual needs and is not limited thereto.

[0068] In some embodiments, the surface of the negative electrode material has a coating layer, and the material of the coating layer includes at least one of carbon material, titanium nitride, boron nitride, silicon nitride, silicon oxide, magnesium oxide, aluminum oxide, silicon carbide, and polyaniline. The type of material for the coating layer can be selected according to actual requirements and is not limited thereto.

[0069] In a second aspect, the present disclosure provides a method for producing a negative electrode material, the method including: subjecting a mixture containing a carbon source and a modifier to a primary carbonization treatment to obtain a precursor, where the modifier contains oxygen and nitrogen elements; subjecting the precursor to a secondary carbonization treatment to obtain a carbon matrix; and combining the carbon matrix with silicon particles or a silicon material to obtain the negative electrode material.

[0070] The method for producing a negative electrode material provided by the present disclosure uses a mixture of a carbon source and a modifier containing oxygen and nitrogen elements to carry out primary and secondary carbonization processes to improve the graphitization degree of the carbon matrix. During the secondary carbonization process, more oxygen- or nitrogen-containing groups are volatilized, allowing the mass content of nitrogen and oxygen in the carbon matrix to be controlled. The doping of small amounts of nitrogen and oxygen elements can provide lone electrons that can participate in the π-π conjugated system of the carbon matrix, thereby forming a larger p-π conjugated system and further increasing the electronic conductivity of the negative electrode material. Finally, the carbon matrix can be composited with silicon particles or a silicon material to improve the capacity of the negative electrode material.

[0071] In some embodiments, a method for manufacturing a negative electrode material is provided, as shown in FIG. Step S10 of subjecting a mixture containing a carbon source and a modifying substance to a primary carbonization treatment to obtain a precursor, the modifying substance including a nitrogen-containing compound and an oxygen-containing compound; Step S20 of subjecting the precursor to a secondary carbonization treatment to obtain a carbon matrix, the temperature of the secondary carbonization treatment being higher than the temperature of the primary carbonization treatment; and Step S30 of combining a porous carbon matrix with silicon particles or silicon material to obtain a negative electrode material, wherein at least some of the silicon particles or silicon material are distributed within the pores of the carbon matrix.

[0072] The method for producing the above-mentioned negative electrode material includes a primary carbonization process using a mixture of a carbon source and a modifier, doping the modifier into the carbon matrix, and then a secondary carbonization process. The secondary carbonization temperature is controlled to be higher than the primary carbonization temperature, and the high temperature can improve the graphitization degree of the carbon matrix and the electronic conductivity of the carbon matrix itself. In addition, in the secondary carbonization process, more oxygen-containing groups or nitrogen-containing groups are volatilized, and the mass content of nitrogen and oxygen in the carbon matrix can be controlled. The doping of a small amount of nitrogen and oxygen elements can provide lone pairs of electrons, which can participate in the π-π conjugated system of the carbon matrix, thereby forming a larger p-π conjugated system and further increasing the electronic conductivity of the negative electrode material. Finally, the carbon matrix can be combined with silicon particles or silicon material to improve the capacity of the negative electrode material. The pores in the carbon matrix can mitigate the volume expansion of the silicon particles or silicon material during the cycling process of the negative electrode material, maintain structural stability, reduce the collapse of the material structure due to volume expansion during the lithium release process of the negative electrode material, effectively reduce the occurrence of side reactions between the negative electrode material and the electrolyte, and further improve the cycling performance of the negative electrode material.

[0073] The manufacturing method will be described in detail below with reference to specific examples.

[0074] In step S10, the mixture containing the carbon source and the modifying material is subjected to a primary carbonization process to obtain a precursor, where the modifying material includes a nitrogen-containing compound and an oxygen-containing compound.

[0075] In some embodiments, the carbon source comprises at least one of bamboo charcoal, fruit shells, starch, coir, rice husks, peanut shells, coal, lignin, sugars, resins, and the like.

[0076] In some embodiments, the temperature of the primary carbonization treatment is 600°C to 900°C, and specifically may be 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, or 900°C, etc., and is not limited thereto, and the time of the carbonization treatment is 1 hour to 15 hours, and specifically may be 1 hour, 3 hours, 5 hours, 8 hours, 10 hours, 12 hours, 13 hours, 14 hours, or 15 hours, and is not limited thereto.

[0077] In some embodiments, the nitrogen-containing compound includes at least one of urea, ammonium acetate, methanolamine, ammonium chloride, ammonium nitrate, and N,N-dimethylformamide. As will be understood, the urea-based nitrogen-containing compound itself contains oxygen and nitrogen elements, thereby achieving doping modification of the carbon source. Even if a compound such as ammonium chloride does not contain oxygen, oxygen in the atmosphere can participate in doping modification together with the nitrogen element in the modifying material during the primary carbonization process.

[0078] In some embodiments, the mass ratio of the carbon source to the nitrogen-containing compound is 100:(0.5 to 100), and specifically may be 100:0.5, 100:1, 100:5, 100:10, 100:20, 100:30, 100:50, 100:60, 100:80, 100:90, or 100:100, etc., and of course may be other values ​​within the above range and are not limited thereto.

[0079] In some embodiments, the method further comprises the step of activating the primary carbonization product by placing it in a mixture of nitrogen and water vapor, which will be appreciated as being beneficial in a subsequent silicon deposition process, as it allows silicon particles or silicon material to be deposited directionally into the pores of the carbon matrix, reducing the deposition of silicon particles or silicon material on the surface of the carbon matrix.

[0080] The activation method includes at least one of physical activation and chemical activation. Specifically, the chemical activation may be performed by treating the primary carbonization product with an alkaline solution as an activator. The physical activation may be performed by using at least two of water vapor, oxygen, and air.

[0081] In some embodiments, the primary carbonization product is activated by placing it in a mixture of nitrogen and water vapor.

[0082] In some embodiments, the volume concentration of water vapor is 0.1% to 30%, and specifically may be 0.1%, 1%, 2%, 3%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 25%, or 30%, etc., but is not limited thereto.

[0083] In some embodiments, the activation temperature is 380°C to 2000°C, and the activation time is 0.5 hours to 30 hours. Specifically, the activation temperature may be 380°C, 400°C, 500°C, 800°C, 1000°C, 1200°C, 1500°C, 1800°C, or 2000°C, and is not limited thereto. Specifically, the activation time may be 0.5 hours, 1 hour, 3 hours, 5 hours, 8 hours, 10 hours, 12 hours, 15 hours, 18 hours, 24 hours, or 30 hours, and is not limited thereto.

[0084] In the present disclosure, by controlling the volume concentration of water vapor, the temperature and time of the activation treatment, the activation efficiency of the primary carbonization product can be improved, and the carbon matrix can have an abundant pore structure. After the activation treatment, the carbon matrix can contain oxygen-containing functional groups (e.g., carboxyl groups, carbonyl groups, etc.) on the surface and / or in the pores, or can be present in the carbon matrix skeleton, skeletal gaps, defects, etc. in the form of atomic doping. A small amount of oxygen-containing functional groups can provide lone electron pairs after the subsequent carbonization treatment, and the lone electron pairs can participate in the π-π conjugated system of the carbon matrix, thereby forming a larger p-π conjugated system and further increasing the electronic conductivity of the negative electrode material.

[0085] In some embodiments, the carbon matrix comprises at least one of hard carbon, soft carbon, graphite, mesocarbon microbeads, activated carbon, porous carbon, mesoporous carbon, and carbon gel.

[0086] In some embodiments, the total pore volume of the carbon matrix is ​​≥ 0.4 cm 3 / g, specifically 0.4cm 3 / g, 0.5cm 3 / g, 0.8cm 3 / g, 1cm 3 / g, 1.1cm 3 / g, 1.3cm 3 / g, 1.5cm 3 / g or 1.8cm 3 / g, etc., and of course other values ​​within the above range are also possible and are not limited thereto. Preferably, the total pore volume of the carbon matrix is ​​≥ 0.5 cm 3 / g, and more preferably the total pore volume of the carbon matrix is ​​≥ 0.7 cm 3 / g.

[0087] In some embodiments, the pores of the carbon matrix include micropores with a pore size of less than 2 nm, and the micropore percentage is ≥ 80%. Specifically, the micropore percentage may be, but is not limited to, 80%, 82%, 85%, 88%, 90%, 92%, 93%, 95%, 98%, or 99%. Preferably, the micropore percentage is ≥ 90%, and more preferably, the micropore percentage is ≥ 95%.

[0088] In some embodiments, the porosity of the carbon matrix is ​​40% to 60%, and may be, for example, 40%, 41%, 43%, 45%, 48%, 50%, 52%, 54%, 56%, 58%, or 60%, and of course, may be other values ​​within the above range and are not limited thereto.

[0089] In some embodiments, the average particle size of the carbon matrix is ​​1 μm to 15 μm, and specifically may be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, or 15 μm, etc., and of course may be other values ​​within the above range, and are not limited thereto.

[0090] In some embodiments, the average pore size of the carbon matrix is ​​0.1 nm to 5 nm, specifically, the average pore size of the carbon matrix is ​​0.1 nm, 0.5 nm, 1 nm, 2 nm, 3 nm, 4 nm, or 5 nm, etc., but is not limited thereto.

[0091] In step S20, the precursor is subjected to a secondary carbonization treatment to obtain a carbon matrix, where the temperature of the secondary carbonization treatment is higher than that of the primary carbonization treatment.

[0092] In some embodiments, the secondary carbonization temperature is 900°C to 2000°C, and may be, but is not limited to, 900°C, 1000°C, 1050°C, 1200°C, 1300°C, 1400°C, 1500°C, 1800°C, or 2000°C. Preferably, the secondary carbonization temperature is 900°C to 1800°C, and more preferably 900°C to 1300°C.

[0093] In some embodiments, the time for the secondary carbonization treatment is 1 hour to 30 hours, and specifically may be 1 hour, 3 hours, 5 hours, 8 hours, 10 hours, 12 hours, 15 hours, 18 hours, 24 hours, or 30 hours, etc., but is not limited thereto.

[0094] In step S30, the porous carbon matrix and the silicon particles or silicon material are combined to obtain a negative electrode material, where at least some of the silicon particles or silicon material are distributed within the pores of the carbon matrix.

[0095] In some embodiments, combining the porous carbon matrix with silicon particles or silicon material comprises vapor-depositing the porous carbon matrix with a silicon source gas to obtain the active material.

[0096] In some embodiments, the silicon source gas comprises at least one of monosilane, disilane, monochlorosilicon, and dichlorosilicon.

[0097] In some embodiments, the volume concentration of the silicon source gas is 1% to 90%, and the volume concentration of the silicon source gas may be specifically 1%, 5%, 10%, 15%, 20%, 30%, 50%, 60%, 70%, 80%, or 90%, but is not limited to the recited values, and other unrecited values ​​within the range also apply.

[0098] In some embodiments, the deposition time of the vapor deposition is 0.1 hours to 15 hours, and the deposition time may be specifically 0.1 hours, 0.5 hours, 1 hour, 3 hours, 5 hours, 6 hours, 8 hours, 10 hours, 12 hours, or 15 hours, etc., and is not limited thereto.

[0099] In some embodiments, the deposition temperature for vapor deposition is 300°C to 800°C, and the deposition temperature may be, for example, 300°C, 350°C, 400°C, 500°C, 600°C, 650°C, 700°C, or 800°C, and may be other values ​​within the above range, without limitation. As can be understood, controlling the vapor deposition temperature within the above range is advantageous for controlling the crystal type of silicon particles, reducing the crystallinity of silicon particles, reducing the conversion of amorphous silicon to crystalline silicon, and further reducing the volume expansion of the negative electrode material, thereby improving the cycle performance of the negative electrode material.

[0100] In some embodiments, the method further includes subjecting the active material to a carbon coating process to obtain the negative electrode material, the carbon coating process including at least one of a solid-phase carbon coating, a liquid-phase carbon coating, and a vapor-phase carbon coating.

[0101] As can be seen, performing a carbon coating treatment on an active material and forming a carbon material on at least a portion of the surface of the active material can reduce direct contact between the negative electrode material and the electrolyte, reduce the occurrence of side reactions between the negative electrode material and the electrolyte, and further improve the electrochemical performance of the negative electrode material, while also alleviating mechanical stress caused by volume expansion of the negative electrode material, improving the structural stability of the negative electrode material, improving the interface stability, and further improving the cycle performance of the negative electrode material.

[0102] In some embodiments, the carbon coating step specifically includes heating the active material, flowing a protective gas and a carbon source gas, and pyrolyzing the carbon source gas to obtain a negative electrode material having a carbon material on the surface.

[0103] In some embodiments, the carbon coating step specifically includes heating the active material, then flowing a protective gas and a carbon source gas, and pyrolyzing the carbon source gas to obtain the negative electrode material, wherein the carbon source gas is an alkane.

[0104] In some embodiments, the carbon source gas comprises at least one of methane, ethylene, acetylene, propyne, propylene, propane, toluene, benzene, styrene, and phenol.

[0105] In some embodiments, the pyrolysis temperature is 600° C. to 1000° C., and the pyrolysis time is 30 minutes to 24 hours.

[0106] Specifically, the pyrolysis temperature may be, but is not limited to, 600°C, 620°C, 650°C, 680°C, 700°C, 760°C, 870°C, 900°C, 920°C, 950°C, 980°C, or 1000°C.Specifically, the pyrolysis time may be, but is not limited to, 30 min, 1 h, 3 h, 5 h, 8 h, 12 h, 15 h, 18 h, 20 h, 22 h, or 24 h.

[0107] In some embodiments, the carbon coating step specifically includes a step of mixing the active material with a solid-phase carbon source and carbonizing the resulting mixture to obtain a negative electrode material.

[0108] In some embodiments, the carbonization temperature is 500° C. to 1000° C., and the carbonization time is 30 minutes to 24 hours.

[0109] Specifically, the carbonization temperature may be, but is not limited to, 500°C, 540°C, 580°C, 600°C, 620°C, 650°C, 680°C, 700°C, 760°C, 870°C, 900°C, 920°C, 950°C, 980°C, or 1000°C.Specifically, the carbonization time may be, but is not limited to, 30 min, 1 h, 3 h, 5 h, 8 h, 12 h, 15 h, 18 h, 20 h, 22 h, or 24 h.

[0110] In some embodiments, the solid phase carbon source comprises at least one of sugars, esters, alkanes, organic acids, and high molecular weight polymers.

[0111] In some embodiments, the solid phase carbon source comprises at least one of polyvinyl chloride, polyvinyl butyral, polyacrylonitrile, polyacrylic acid, polyethylene glycol, polypyrrole, polyaniline, sucrose, glucose, maltose, citric acid, asphalt, furfural resin, epoxy resin, and phenolic resin.

[0112] In some embodiments, the mass ratio of the solid-phase carbon source to the negative electrode material is (1 to 200):100, and specifically may be 1:100, 2:100, 5:100, 10:100, 50:100, 100:100, 150:100, 180:100, or 200:100, etc., and is not limited thereto.

[0113] In some embodiments, the carbon coating step specifically includes a step of mixing the active material with a liquid-phase carbon source and carbonizing the resulting mixture to obtain the negative electrode material.

[0114] In some embodiments, the mass ratio of the liquid-phase carbon source to the negative electrode material is (1 to 200):100, and specifically may be 1:100, 2:100, 5:100, 10:100, 50:100, 100:100, 150:100, 180:100, or 200:100, etc., and is not limited thereto.

[0115] In some embodiments, the liquid phase carbon source comprises at least one of n-hexane, toluene, benzene, xylene, methanol, ethanol, propanol, butanol, pentanol, acetone, methyl ethyl ketone, 2-pentanone, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, and amyl acetate.

[0116] In some embodiments, the carbonization temperature is 600° C. to 1200° C., and the carbonization time is 2 hours to 20 hours.

[0117] Specifically, the carbonization temperature may be, but is not limited to, 600°C, 620°C, 650°C, 680°C, 700°C, 760°C, 870°C, 900°C, 920°C, 950°C, 980°C, 1000°C, 1020°C, 1080°C, 1100°C, 1160°C, or 1200°C. The carbonization time may be, but is not limited to, 2 hours, 3 hours, 5 hours, 8 hours, 12 hours, 15 hours, 18 hours, 20 hours, 22 hours, 24 hours, 25 hours, 26 hours, 28 hours, or 30 hours.

[0118] In some embodiments, the carbon coating process is carried out under a protective atmosphere comprising at least one of nitrogen, helium, neon, argon, and krypton.

[0119] In some embodiments, the method further includes shaping, sieving, and grading the carbon-coated product to obtain an anode material having a carbon material on a surface thereof, wherein the shaping includes at least one of crushing, grinding, ball milling, and gas milling.

[0120] In some embodiments, a method for producing an anode material is provided, the method including: step S10 of carbonizing a mixture containing a carbon source and a doping material to obtain a precursor, where the doping material contains oxygen, nitrogen, and sulfur; step S20 of subjecting the precursor to a high-temperature treatment and a third activation treatment to obtain a carbon matrix; and step S30 of combining the carbon matrix with silicon particles to obtain the anode material.

[0121] The method for producing the anode material provided by the above solution involves doping the oxygen, nitrogen, and sulfur elements of the doping material into a carbon source in the precursor production process to obtain a carbon matrix, which is used to produce the anode material with excellent conductivity and cycle performance disclosed herein.

[0122] The above manufacturing method will be specifically explained below with reference to examples.

[0123] In step S10, the mixture containing the carbon source and the modifying substance is subjected to a carbonization process to obtain a precursor, where the modifying substance contains oxygen, nitrogen, and sulfur elements; In some embodiments, the carbon source includes at least one of resin-based polymer, lignin, coir, fruit shells, peanut shells, rice husks, and coal-based biomass, and the type of carbon source can be selected according to actual needs and is not limited thereto.

[0124] In some embodiments, the modifying substance includes a nitrogen-containing doping material and a sulfur-containing doping material, the nitrogen-containing doping material including at least one of urea, ammonium acetate, ethanolamine, methanolamine, ammonium chloride, amine nitrate, and N,N-dimethylformamide, and the sulfur-containing doping material including at least one of thiol, ammonium hydrogen sulfate, thiophenol, thioether, and disulfide, and the types of the nitrogen-containing doping material and the sulfur-containing doping material can be selected according to actual needs and are not limited thereto.

[0125] In some embodiments, the mass ratio of the carbon source, the nitrogen-containing doping material, and the sulfur-containing doping material is 100:(0.01-10):(0.01-5), and optionally, the mass ratio of the carbon source, the nitrogen-containing doping material, and the sulfur-containing doping material may be, for example, 100:0.4:0.2, 100:1:0.3, 100:2:0.2, 100:4:4.2, 100:5:0.1, and 100:9:5, or other values ​​within the range, which can be selected according to actual needs and are not limited herein. It is understood that the mass ratio of the carbon source, the nitrogen-containing doping material, and the sulfur-containing doping material within the above range can improve the conductive performance of the carbon matrix and ensure the structural stability of the carbon matrix.

[0126] In some embodiments, the primary carbonization temperature is 600°C to 900°C, and the carbonization time is 1 hour to 30 hours. Optionally, the primary carbonization temperature may be 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, etc., and the primary carbonization time may be 1 hour, 5 hours, 10 hours, 14 hours, 21 hours, 25 hours, 28 hours, 30 hours, etc., or other values ​​within the range, which can be selected according to actual needs and are not limited herein. It will be understood that the primary carbonization temperature and time within the above ranges will result in a better carbon content in the resulting carbon matrix and better electrical conductivity of the carbon matrix.

[0127] In step S20, the precursor undergoes a secondary carbonization treatment and a third activation treatment to obtain a carbon matrix.

[0128] In some embodiments, the secondary carbonization temperature is 900°C to 2500°C, and the secondary carbonization time is 1 hour to 40 hours. Optionally, the secondary carbonization temperature may be 900°C, 1000°C, 1100°C, 1200°C, 1300°C, 1400°C, 1500°C, 1600°C, 1700°C, 1800°C, 1900°C, 2000°C, 2100°C, 2200°C, 2300°C, 2400°C, and 2500°C, and the secondary carbonization time may be 1 hour, 4 hours, 8 hours, 12 hours, 19 hours, 22 hours, 28 hours, 33 hours, 35 hours, and 40 hours, or other values ​​within the ranges, which can be selected according to actual requirements and are not limited thereto. As can be seen, the temperature and time of the high-temperature treatment within the above ranges can adjust the contents of doped nitrogen, oxygen and sulfur elements in the carbon matrix, thereby improving the electrochemical performance and structural stability of the negative electrode material.

[0129] In some embodiments, the third activation treatment includes physical activation and / or chemical activation, where the physical activation includes at least one of steam activation, nitrogen activation, oxygen activation, and air activation, and the chemical activation includes alkaline activation. The type of activation treatment can be selected according to actual needs and is not limited thereto.

[0130] In some embodiments, the third activation process includes at least a primary activation process, that is, the activation process may include only a primary activation process, or a secondary activation process after the primary activation process, or multiple activation processes. The number of activation processes can be selected according to actual requirements and is not limited herein.

[0131] As can be seen, the activation treatment of the precursor allows the carbon matrix to have a rich pore structure, which is advantageous for the silicon particles to be directionally deposited into the pores of the carbon matrix in the subsequent silicon deposition process, thereby reducing the deposition of silicon particles on the surface of the carbon matrix.

[0132] Preferably, the activation treatment of the present disclosure includes a primary activation process and a secondary activation process, and as will be understood, the secondary activation process can form many and uniformly distributed activation pores in the carbon matrix, which is advantageous for subsequent filling of silicon particles into the activation pores.

[0133] In some embodiments, the temperature of the primary activation process is 400°C to 1000°C, and the time of the primary activation process is 1 hour to 30 hours. Optionally, the temperature of the primary activation process may be 400°C, 500°C, 600°C, 700°C, 800°C, 850°C, 900°C, 1000°C, etc., and the time of the primary activation process may be 1 hour, 4 hours, 8 hours, 12 hours, 19 hours, 22 hours, 28 hours, 30 hours, etc., or other values ​​within the range, which can be selected according to actual needs and are not limited herein.

[0134] In some embodiments, the temperature of the secondary activation process is 500°C to 900°C, and the time of the secondary activation process is 1 hour to 30 hours. Optionally, the temperature of the secondary activation process may be 500°C, 600°C, 700°C, 800°C, 850°C, 900°C, etc., and the time of the secondary activation process may be 1 hour, 4 hours, 8 hours, 12 hours, 19 hours, 22 hours, 28 hours, 30 hours, etc., or other values ​​within the range, which can be selected according to actual requirements and are not limited herein.

[0135] In step S30, the porous carbon matrix and silicon particles are combined to obtain a negative electrode material.

[0136] In some embodiments, the method further comprises coating the composite of the carbon matrix and silicon particles.

[0137] In some embodiments, the coating material includes at least one of a carbon source, titanium nitride, boron nitride, silicon nitride, silicon oxide, magnesium oxide, aluminum oxide, silicon carbide, and polyaniline, and the type of coating material can be selected according to actual requirements and is not limited thereto.

[0138] In some embodiments, the mass ratio of the carbon matrix to the coating material is (10-100):(0.1-10), and optionally, the mass ratio of the carbon matrix to the coating material may be specifically 10:0.1, 20:0.5, 40:1, 50:0.1, 70:10, 100:10, etc., or other values ​​within the range, which can be selected according to actual needs and are not limited herein. It will be understood that when the mass ratio of the carbon matrix to the coating material is within the above range, the resulting coating layer can provide good coating protection for the carbon matrix and will not affect the diffusion of lithium ions during the charge and discharge process, further ensuring the cycle performance of the lithium-ion battery.

[0139] In a fourth aspect, the present disclosure provides a battery including the anode material of the first aspect or the anode material produced by the method for producing the anode material of the second aspect. The battery may be, but is not limited to, a lithium-ion battery or a sodium-ion battery.

[0140] The above are merely preferred embodiments of the present disclosure, and do not limit the present disclosure. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present disclosure should be included within the protection scope of the present disclosure.

[0141] Example 1 The method for manufacturing the negative electrode material of this example includes the following steps.

[0142] (1) Bamboo charcoal and urea were mixed in a mass ratio of 100:1, and the mixture was subjected to primary carbonization at 750°C and kept at this temperature for 5 hours. The primary carbonization product was then placed in steam and nitrogen for primary activation at a steam:nitrogen ratio of 0.1:90 (volume ratio), a primary activation temperature of 650°C, and a primary activation time of 4 hours to obtain a primary activation product. The primary activation product was then placed in a heat treatment furnace for secondary activation at 950°C and a secondary activation time of 3 hours to obtain a precursor.

[0143] (2) The precursor was placed in a heat treatment furnace and subjected to secondary carbonization treatment. The temperature of the secondary carbonization treatment was 900°C, and the temperature was maintained for 10 hours to obtain a carbon matrix with an average pore size of 1.8 nm. The carbon matrix had pores.

[0144] (3) The carbon matrix was placed in a chemical vapor deposition (CVD) system, and silane was then introduced into the CVD system. The silane volume concentration was controlled to 40%, and the temperature was raised to 600°C. The gas-phase deposition reaction was carried out for 4 hours to obtain the composite.

[0145] (4) The composite and asphalt were mixed in a mass ratio of 50:15. The mixed material was then placed in a high-temperature box furnace, nitrogen was flowed, and solid-phase carbon coating treatment was carried out at 520°C. The temperature was maintained for 2 hours, and the carbon-coated product was crushed, sieved, and then graded to obtain the negative electrode material.

[0146] The negative electrode material prepared in the embodiments of the present disclosure includes an active material and a carbon material located on the surface of the active material, the active material including a carbon matrix and silicon particles, the carbon matrix having pores, and at least some of the silicon particles distributed within the pores of the carbon matrix.

[0147] FIG. 2 is an XRD diagram of the negative electrode material prepared in Example 1 of the present disclosure. As shown in FIG. 2, the active material in the negative electrode material is amorphous. FIG. 3 is a schematic diagram of the initial charge / discharge curve of the negative electrode material prepared in Example 1 of the present disclosure. As shown in FIG. 3, the initial charge / discharge capacity of the negative electrode material is 1938 mAh / g, and the initial coulombic efficiency is 93.1%, demonstrating excellent electrochemical performance. FIG. 4 is a schematic diagram of the cycle performance curve of the negative electrode material prepared in Example 1 of the present disclosure. As shown in FIG. 4, the capacity retention rate after 50 cycles of the battery prepared with the negative electrode material is 93.1%, demonstrating excellent cycle performance.

[0148] Example 2 The method for manufacturing the negative electrode material of this example includes the following steps.

[0149] (1) Commercialized porous carbon and ethanolamine were mixed in a mass ratio of 100:1.5, and the mixture was subjected to primary carbonization treatment. The primary carbonization temperature was 850°C, and the temperature was kept for 8 hours to obtain a precursor.

[0150] (2) The precursor was placed in a heat treatment furnace and subjected to secondary carbonization treatment. The temperature of the secondary carbonization treatment was 1900°C, and the temperature was maintained for 12 hours to obtain a carbon matrix with an average pore size of 3.9 nm. The carbon matrix had pores.

[0151] (3) The carbon matrix was placed in a chemical vapor deposition (CVD) system, and silane was then introduced into the CVD system. The silane volume concentration was controlled to 20%, and the temperature was raised to 550°C. The vapor deposition reaction was carried out for 4 hours to obtain the composite.

[0152] (4) Methane was continuously flowed into the gas-phase chemical deposition equipment, and the methane volume concentration was controlled to 29%. The temperature was raised to 650°C to perform gas-phase carbon coating treatment, and the temperature was maintained for 4 hours. The carbon coating treatment product was then crushed, sieved, and graded to obtain the negative electrode material.

[0153] Example 3

[0154] (1) Coir and ammonium chloride were mixed in a mass ratio of 100:0.5, and the mixture was subjected to a primary carbonization treatment at a primary carbonization temperature of 700°C and kept at that temperature for 15 hours. The primary carbonization product was then placed in steam and nitrogen to undergo a primary activation treatment at a steam:nitrogen ratio of 0.5:90 (volume ratio), a primary activation temperature of 750°C, and a primary activation time of 4 hours to obtain a primary activation product. The primary activation product was then placed in a heat treatment furnace to undergo secondary activation at a secondary activation temperature of 850°C and a secondary activation time of 5 hours to obtain a precursor.

[0155] (2) The precursor was placed in a heat treatment furnace and subjected to secondary carbonization treatment. The temperature of the secondary carbonization treatment was 1000°C, and the temperature was maintained for 6 hours to obtain a carbon matrix with an average pore size of 1.7 nm. The carbon matrix had pores.

[0156] (3) The carbon matrix was placed in a chemical vapor deposition (CVD) system, and silane was then introduced into the CVD system. The silane volume concentration was controlled to 31%, and the temperature was raised to 500°C. The gas-phase deposition reaction was carried out for 4 hours to obtain the composite.

[0157] (4) Acetylene was continuously flowed into the gas-phase chemical deposition equipment, and the acetylene volume concentration was controlled at 45%. The temperature was raised to 650°C to carry out the gas-phase carbon coating treatment, and the temperature was maintained for 4 hours. The carbon coating treatment product was then crushed, sieved, and graded to obtain the negative electrode material.

[0158] The negative electrode material prepared according to the embodiments of the present disclosure includes an active material, the active material including a carbon matrix and silicon particles, the carbon matrix having pores, and at least some of the silicon particles distributed within the pores of the carbon matrix.

[0159] Example 4

[0160] (1) Fruit shells and ammonium bicarbonate were mixed in a mass ratio of 100:3.3, and the mixture was subjected to primary carbonization at a temperature of 710°C and kept at that temperature for 6 hours. The primary carbonized product was then placed in steam and nitrogen for primary activation at a volume ratio of steam:nitrogen of 0.9:90, a primary activation temperature of 550°C, and a primary activation time of 5 hours to obtain a primary activated product. The primary activated product was then placed in a heat treatment furnace for secondary activation at a temperature of 880°C and a secondary activation time of 5 hours to obtain a precursor.

[0161] (2) The precursor was placed in a heat treatment furnace and subjected to secondary carbonization treatment. The temperature of the secondary carbonization treatment was 1200°C, and the temperature was maintained for 16 hours to obtain a carbon matrix with an average pore size of 2.1 nm. The carbon matrix had pores.

[0162] (3) The carbon matrix was placed in a chemical vapor deposition (CVD) system, and silane was then introduced into the CVD system. The silane volume concentration was controlled to 11%, and the temperature was raised to 560°C. The vapor deposition reaction was carried out for 4 hours to obtain the composite.

[0163] (4) Propylene was continuously flowed into the gas-phase chemical deposition equipment, and the propylene volume concentration was controlled to 45%. The temperature was raised to 690°C to carry out the gas-phase carbon coating treatment, and the temperature was maintained for 4 hours. The carbon coating treatment product was then crushed, sieved, and graded to obtain the negative electrode material.

[0164] Example 5

[0165] (1) Bamboo charcoal and urea were mixed in a mass ratio of 100:1, and the mixture was subjected to primary carbonization at 750°C for 5 hours. The primary carbonization product was then placed in steam and nitrogen for activation at a volume ratio of 0.1:90 (steam:nitrogen), at 550°C for 24 hours, to obtain a precursor.

[0166] (2) The precursor was placed in a heat treatment furnace and subjected to secondary carbonization treatment. The temperature of the secondary carbonization treatment was 1500°C, and the temperature was maintained for 10 hours to obtain a carbon matrix with an average pore size of 2.1 nm. The carbon matrix had pores.

[0167] (3) The carbon matrix was placed in a chemical vapor deposition (CVD) system, and silane was then introduced into the CVD system. The silane volume concentration was controlled to 40%, and the temperature was raised to 600°C. The gas-phase deposition reaction was carried out for 4 hours to obtain the composite.

[0168] (4) The composite and asphalt were mixed in a mass ratio of 50:15. The mixed material was then placed in a high-temperature box furnace, nitrogen was flowed, and solid-phase carbon coating treatment was carried out at 520°C. The temperature was maintained for 2 hours, and the carbon-coated product was crushed, sieved, and then graded to obtain the negative electrode material.

[0169] Example 6

[0170] (1) Commercialized porous carbon, ethanolamine, and urea were mixed in a mass ratio of 100:1.0:0.5, and the mixture was subjected to primary carbonization treatment at a primary carbonization temperature of 600°C. The mixture was kept at this temperature for 8 hours to obtain a precursor.

[0171] (2) The precursor was placed in a heat treatment furnace and subjected to secondary carbonization treatment. The temperature of the secondary carbonization treatment was 1300°C, and the temperature was maintained for 12 hours to obtain a carbon matrix with an average pore size of 2.2 nm. The carbon matrix had pores.

[0172] (3) The carbon matrix was placed in a chemical vapor deposition (CVD) system, and silane was then introduced into the CVD system. The silane volume concentration was controlled to 40%, and the temperature was raised to 550°C. The vapor deposition reaction was carried out for 4 hours to obtain the composite.

[0173] (4) Methane was continuously flowed into the gas-phase chemical deposition equipment, and the methane volume concentration was controlled to 35%. The temperature was raised to 800°C to perform gas-phase carbon coating treatment, and the temperature was maintained for 4 hours. The carbon coating treatment product was then crushed, sieved, and graded to obtain the negative electrode material.

[0174] Example 7 The differences from the first embodiment are as follows.

[0175] (2) The precursor was placed in a heat treatment furnace and subjected to secondary carbonization treatment. The temperature of the secondary carbonization treatment was 2100°C, and the temperature was maintained for 10 hours to obtain a carbon matrix with an average pore size of 5.8 nm. The carbon matrix had pores.

[0176] Example 8 The differences from the first embodiment are as follows.

[0177] (1) Bamboo charcoal and urea were mixed in a mass ratio of 100:1, and the mixture was subjected to primary carbonization at 750°C and kept at this temperature for 5 hours. The primary carbonization product was then placed in steam and nitrogen for primary activation at a steam:nitrogen ratio of 2:90 (volume ratio), a primary activation temperature of 650°C, and a primary activation time of 4 hours to obtain a primary activation product. The primary activation product was then placed in a heat treatment furnace for secondary activation at 950°C and a secondary activation time of 15 hours to obtain a precursor.

[0178] Example 9 The differences from the first embodiment are as follows.

[0179] (1) Bamboo charcoal and urea were mixed in a mass ratio of 100:2.3, and the mixture was subjected to primary carbonization at 750°C for 5 hours. The primary carbonization product was then placed in steam and nitrogen for primary activation at a steam:nitrogen ratio of 0.1:90 (volume ratio), a primary activation temperature of 650°C, and a primary activation time of 4 hours to obtain a primary activated product. The primary activated product was then placed in a heat treatment furnace for secondary activation at 950°C for 30 hours to obtain a precursor.

[0180] (Comparative Example 1) The difference from Example 1 is that step (2) was not performed.

[0181] (Comparative Example 2)

[0182] (1) Bamboo charcoal was used for primary carbonization at a temperature of 750°C for 5 hours. The primary carbonized product was then placed in steam and nitrogen for primary activation at a volume ratio of 0.1:90, at a primary activation temperature of 650°C, and for a primary activation time of 4 hours to obtain a precursor.

[0183] (2) The precursor was placed in a heat treatment furnace and subjected to secondary carbonization treatment. The temperature of the secondary carbonization treatment was 700°C, and the temperature was maintained for 10 hours to obtain a carbon matrix with an average pore size of 1.8 nm. The carbon matrix had pores.

[0184] (3) The carbon matrix was placed in a chemical vapor deposition (CVD) system, and silane was then introduced into the CVD system. The silane volume concentration was controlled to 40%, and the temperature was raised to 600°C. The gas-phase deposition reaction was carried out for 4 hours to obtain the composite.

[0185] (4) The composite and asphalt were mixed in a mass ratio of 50:15. The mixed material was then placed in a high-temperature box furnace, nitrogen was flowed, and solid-phase carbon coating treatment was carried out at 520°C. The temperature was maintained for 2 hours, and the carbon-coated product was crushed, sieved, and then graded to obtain the negative electrode material.

[0186] Example 10

[0187] (1) Bamboo charcoal, urea, and thiol were mixed in a ratio of 100:1:0.5 to obtain a mixture, which was then carbonized at 850°C for 5 hours to obtain a precursor.

[0188] (2) The precursor was placed in a heat treatment furnace and subjected to high-temperature treatment at 1580°C for 10 hours. After completion of the treatment, the product was pickled and dried. After that, a mixed gas of water vapor and nitrogen (volume ratio 100:0.4) was introduced and activated at 800°C for 15 hours. A carbon matrix with an average pore size of 1.8 nm was obtained. The volume ratio of micropores in the carbon matrix was 90%, and the total pore volume was 1.6 cm. 3 / g,

[0189] (3) The carbon matrix was placed in a CVD apparatus, and then silane was introduced into the CVD apparatus, the silane concentration was controlled to 42%, and the temperature was raised to 600°C. The reaction was carried out for 4 hours to obtain a silicon deposition product.

[0190] (4) The silicon deposition product and asphalt are mixed in a mass ratio of 50:15, and after mixing, the mixture is placed in a high-temperature box furnace, nitrogen is flowed, and the mixture is heat-treated at 700 ° C. and kept at that temperature for 2 hours to obtain a coated product.

[0191] (5) The coated product was crushed, sieved, and then graded to obtain the negative electrode material.

[0192] 5 shows the XRD pattern of the negative electrode material prepared in this example. As shown in FIG. 5, there is no silicon peak in the XRD pattern, indicating that the silicon particles present in the negative electrode material are amorphous, and the amorphous structure of amorphous silicon allows it to have a greater volume expansion tolerance. During the charge / discharge process, the silicon particles can more flexibly absorb and release lithium ions without experiencing significant volume changes like crystalline silicon. This reduces stress and the risk of explosion due to volume expansion of the negative electrode material and improves the mechanical and electrochemical stability of the negative electrode material.

[0193] FIG. 6 shows the initial charge-discharge curve of the negative electrode material prepared in this example. As shown in FIG. 6, the initial charge-discharge capacity of the negative electrode material of the present disclosure is 1908 mAh / g, the initial coulombic efficiency is 92.7%, and the negative electrode material has excellent conductivity.

[0194] FIG. 7 shows the cycle performance curve of the negative electrode material produced in this example. As shown in FIG. 7, the negative electrode material of the present disclosure has excellent cycle performance, with a capacity retention rate of 92.5% after 50 cycles.

[0195] Example 11 The differences from Example 10 are as follows.

[0196] Bamboo charcoal, urea and thiol were mixed in a ratio of 100:1:2.1 to obtain a mixture.

[0197] Example 12 The differences from Example 10 are as follows.

[0198] The precursor was placed in a heat treatment furnace and subjected to high-temperature treatment at a temperature of 900°C for a holding time of 5 hours.

[0199] Example 13 The differences from Example 10 are as follows.

[0200] The precursor was placed in a heat treatment furnace and subjected to high-temperature treatment at a temperature of 2500°C and a heat-retention time of 40 hours.

[0201] Example 14

[0202] (1) Porous carbon, ethanolamine, and ammonium hydrogen sulfate were mixed in a ratio of 100:1.5:1 to obtain a mixture, which was then carbonized at 850°C for 8 hours to obtain a precursor.

[0203] (2) The precursor was placed in a heat treatment furnace and subjected to high-temperature treatment. The temperature was 1300°C and the heat-holding time was 12 hours. After the heat-holding was completed, the heat-holding product was pickled. After the pickled product was dried, a mixed gas of water vapor and nitrogen (volume ratio 100:0.4) was introduced and activated at 850°C for 14.5 hours. A carbon matrix with an average pore size of 1.9 nm was obtained. The volume proportion of the micropores in the carbon matrix was 86%, and the total pore volume was 1.4 cm. 3 / g,

[0204] (3) The carbon matrix was placed in a CVD apparatus, and then silane was introduced into the CVD apparatus, the silane concentration was controlled to 26%, and the temperature was raised to 500°C. The reaction was carried out for 4 hours to obtain a silicon deposition product.

[0205] (4) The silicon deposition product is placed in a CVD apparatus, and then methane is flowed into the CVD apparatus, the methane concentration is controlled to 29%, and the temperature is raised to 680°C. The reaction is carried out for 4 hours to obtain a coating product.

[0206] (5) The coated product was crushed, sieved, and then graded to obtain the negative electrode material.

[0207] Example 15

[0208] (1) Mix coir, ammonium chloride, and ammonium sulfate in a ratio of 100:0.5:0.1 to obtain a mixture, which is then carbonized at 900°C for 15 hours to obtain a precursor.

[0209] (2) The precursor was placed in a heat treatment furnace and subjected to high-temperature treatment. The temperature was 2200°C, and the heat-holding time was 6 hours. After the heat-holding was completed, the heat-holding product was pickled. After the pickled product was dried, a mixed gas of water vapor and nitrogen (volume ratio 100:0.4) was introduced and activated at 800°C for 14 hours. A carbon matrix with an average pore size of 1.7 nm was obtained. The volume proportion of the micropores in the carbon matrix was 91%, and the total pore volume was 1.5 cm. 3 / g,

[0210] (3) The carbon matrix was placed in a CVD apparatus, and then silane was introduced into the CVD apparatus, the silane concentration was controlled to 37%, and the temperature was raised to 480°C. The reaction was carried out for 6 hours to obtain a silicon deposition product.

[0211] (4) The silicon deposition product is placed in a CVD apparatus, and then acetylene is introduced into the CVD apparatus, the acetylene concentration is controlled to 45%, and the temperature is raised to 690°C. The reaction is carried out for 3 hours to obtain a coated product.

[0212] (5) The coated product was crushed, sieved, and then graded to obtain the negative electrode material.

[0213] Example 16

[0214] (1) Fruit shell and (NH4)2SO4 are mixed in a ratio of 100:2.3, followed by the first step of carbonization treatment, the temperature is 790°C, and the heat treatment time is 6 hours;

[0215] (2) The precursor was placed in a heat treatment furnace and subjected to high-temperature treatment. The temperature was 2400°C, and the heat-holding time was 10 hours. After the heat-holding was completed, the heat-holding product was pickled. After the pickled product was dried, a mixed gas of water vapor and nitrogen (volume ratio 100:0.4) was introduced and activated at 800°C for 20 hours. A carbon matrix with an average pore size of 2.2 m was obtained. The volume proportion of micropores in the carbon matrix was 85%, and the total pore volume was 1.3 cm. 3 / g,

[0216] (3) The carbon matrix was placed in a CVD apparatus, and then silane was introduced into the CVD apparatus, the silane concentration was controlled to 17%, and the temperature was raised to 560°C. The reaction was carried out for 7 hours to obtain a silicon deposition product.

[0217] (4) The silicon deposition product is placed in a CVD apparatus, and then propylene is introduced into the CVD apparatus, the propylene concentration is controlled to 45%, and the temperature is raised to 690°C. The reaction is carried out for 4 hours to obtain a coated product.

[0218] (5) The coated product was crushed, sieved, and then graded to obtain the negative electrode material.

[0219] Example 17 The differences from Example 10 are as follows.

[0220] After drying the pickled product, a mixed gas of water vapor and nitrogen (volume ratio 100:0.4) was passed through it, and primary activation treatment was performed at 800°C for 15 hours, followed by secondary activation treatment at 700°C for 15 hours to obtain a carbon matrix with an average pore size of 1.8 nm.

[0221] Example 18 The differences from Example 10 are as follows.

[0222] Bamboo charcoal, urea, and thiol were mixed in a ratio of 100:1:6 to obtain a mixture.

[0223] Example 19 The differences from Example 10 are as follows.

[0224] Bamboo charcoal, urea, and thiol were mixed in a ratio of 100:15:1 to obtain a mixture.

[0225] Example 20

[0226] (1) Bamboo charcoal and urea were mixed in a ratio of 100:1 to obtain a mixture, which was then carbonized at 850°C for 5 hours to obtain a precursor.

[0227] (2) The precursor was placed in a heat treatment furnace and subjected to high-temperature treatment at 1580°C for 10 hours. After completion of the treatment, the product was pickled and dried. After that, a mixture of water vapor and nitrogen (volume ratio 100:0.4) was introduced and activated at 800°C for 15 hours. A carbon matrix with an average pore size of 1.9 nm was obtained. The volume ratio of micropores in the carbon matrix was 90%, and the total pore volume was 0.91 cm. 3 / g,

[0228] (3) The carbon matrix was placed in a CVD apparatus, and then silane was introduced into the CVD apparatus, the silane concentration was controlled to 42%, and the temperature was raised to 600°C. The reaction was carried out for 4 hours to obtain a silicon deposition product.

[0229] (4) The silicon deposition product and asphalt are mixed in a mass ratio of 50:15, and after mixing, the mixture is placed in a high-temperature box furnace, nitrogen is flowed, and the mixture is heat-treated at 700°C and kept at that temperature for 2 hours to obtain a coated product.

[0230] (5) The coated product was crushed, sieved, and then graded to obtain the negative electrode material.

[0231] Example 21

[0232] (1) Bamboo charcoal, urea, and thiol are mixed in a ratio of 100:1:0.5 to obtain a mixture, which is then carbonized at 850°C for 5 hours. After the temperature is maintained, the heated product is pickled. After the pickled product is dried, a mixed gas of water vapor and nitrogen (volume ratio 100:0.4) is passed through the mixture and activated at 800°C for 15 hours to obtain a precursor.

[0233] (2) The precursor was placed in a heat treatment furnace and subjected to high-temperature treatment at 1580°C for 10 hours. A carbon matrix with an average pore size of 1.93 nm was obtained, and the volume ratio of micropores in the carbon matrix was 88%, with a total pore volume of 0.89 cm. 3 / g,

[0234] (3) The carbon matrix was placed in a CVD apparatus, and then silane was introduced into the CVD apparatus, the silane concentration was controlled to 42%, and the temperature was raised to 600°C. The reaction was carried out for 4 hours to obtain a silicon deposition product.

[0235] (4) The silicon deposition product and asphalt are mixed in a mass ratio of 50:15, and after mixing, the mixture is placed in a high-temperature box furnace, nitrogen is flowed, and the mixture is heat-treated at 700°C and kept at that temperature for 2 hours to obtain a coated product.

[0236] (5) The coated product was crushed, sieved, and then graded to obtain the negative electrode material.

[0237] (Comparative Example 3) The difference from Example 10 is that no high temperature treatment was performed.

[0238] Comparative Example 4 The difference from Example 10 is that no urea was added to the mixture.

[0239] Testing method:

[0240] (1) Test method for specific surface area of ​​negative electrode material: The specific surface area was measured using a TriStar 3000 specific surface area and pore size analyzer from Micromeritics, USA.

[0241] (2) Test method for total pore volume of negative electrode material after removing negative electrode material, carbon matrix or silicon particles: The test was carried out using an ASAP2460 instrument manufactured by Micromeritics, USA, and the pore volume V was calculated using the BJH Desorption cumulative volume of pores model within the pore diameter range of 17 Å to 3000 Å.

[0242] Micropore and mesopore analysis was performed using a Micromeretics ASAP 2460. At liquid nitrogen temperature, the equilibrium adsorption amount of nitrogen on the surface of an object is related to its pore size and other properties. The pore size was calculated by fitting multiple models based on the rules for how the adsorption amount changes with relative pressure during the adsorption process. The software generated reports that used density functional theory (DFT) to calculate the pore size distribution, total pore volume, and pore volume within a certain range.

[0243] (3) Pore size test method for the negative electrode material after removing the negative electrode material, carbon matrix, or silicon particles: A suitable amount of the sample particles was measured for pore size and porosity using a transmission electron microscope (TEM).

[0244] (4) Silicon particle size test method: The nanosilicon particles were observed using a field emission scanning electron microscope or a transmission electron microscope, and the particle sizes of 5 to 10 nanosilicon particles were directly measured depending on the scale, and the average particle size was used as the particle size of the final nanosilicon particles or the average particle size of the silicon particles.

[0245] (5) Test method for particle size of negative electrode material: Using a Malvern type laser particle size analyzer MS3000, based on the principle that the scattered light intensity distribution generated by particles in various directions depends on the particle size, large particles have a small scattering angle and small particles have a large scattering angle, and therefore the particle size distribution was obtained using the scattered light intensity distribution of laser diffraction.

[0246] (6) Gas generation value test of negative electrode material: The negative electrode materials prepared in Examples 1 to 9 and Comparative Examples 1 to 2 were added to 50 g of a styrene-butadiene rubber solution to obtain a mixed solution. The mixed solution was packaged using an aluminum plastic film, placed in a 2000 mL sealed container, and stored at 45°C. Testing revealed that the gas generation rate of the negative electrode materials over 6 days was M mL / g.

[0247] (7) Testing the mass content of oxygen atoms and nitrogen atoms in negative electrode materials: The N and O elements of the materials produced in Examples 1 to 9 and Comparative Examples 1 and 2 were measured using an oxygen, nitrogen, and hydrogen analyzer ONH2000 manufactured by Eltra in accordance with ISO 17053:2005.

[0248] (8) Test method for powder conductivity of negative electrode materials: Based on the international standard GBT 30835-2014, a resistivity tester (Suzhou Jingge Electronics ST-2255A) was used to apply a constant voltage of 8000 kg ± 2 kg to a 5 g powder sample in an electronic press, maintaining the voltage for 15-25 seconds. The sample was then placed between the electrodes of the tester. The sample height h (cm), voltage U across both ends, current I, and resistance R (KΩ) were calculated. The area of ​​the powder after pressing was S = 3.14 cm. 2 and the powder conductivity was calculated based on the formula δ=h / (S*R) / 1000, with the unit being S / m.

[0249] (9) Electrochemical performance test: The negative electrode materials prepared in the examples and comparative examples were dissolved in N-methylpyrrolidone in a 94:1:5 mass ratio of negative electrode material, carboxymethyl cellulose, and styrene-butadiene rubber to adjust the solids content to 50%. The resulting solution was coated on a copper foil current collector and vacuum-dried to produce a negative electrode sheet. The negative electrode sheet was then assembled into an 18650 cylindrical cell using a three-dimensional positive electrode sheet (NCM523), a 1 mol / L lithium hexafluorophosphate (LiPF6) / (ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC)) (v / v = 1:1:1) electrolyte, a Celgard 2400 separator, and a housing using standard manufacturing processes. Charge / discharge tests of the cylindrical cells were performed using a LAND battery test system at Wuhan King Nuo Electronics Co., Ltd., charging and discharging at a constant current of 0.2 C at room temperature, with the charge / discharge voltage limited to 2.75 to 4.2 V. The initial reversible capacity, initial charge capacity, and initial discharge capacity were measured. First coulomb efficiency = first discharge capacity / first charge capacity.

[0250] After 50 cycles, the discharge capacity was recorded as the remaining capacity of the lithium-ion battery, and the capacity retention rate was calculated as remaining capacity / initial capacity*100%.

[0251] (10) Etching process: The anode material was immersed in a 1M nitric acid solution for 1 hour. A 20% HF acid solution was then added dropwise to the anode material, repeatedly until yellow smoke emanated. The residue was decomposed with 1M nitric acid, followed by washing and drying to obtain a silicon-free anode material. Alternatively, 150 mL of 20% HF acid solution was added dropwise to 10 g of anode material while stirring, producing SiF and H gases. The heat was released and the supernatant was centrifuged until no more gas was produced. Another 150 mL of 20% HF acid solution was added to the anode material, stirred for 12 hours, and the supernatant was centrifuged again. The anode material was then washed with pure water until neutral and dried to obtain a silicon-free anode material, i.e., a carbon matrix.

[0252] (11) Measurement of hydrogen generation amount of negative electrode materials produced in Examples 10 to 21 and Comparative Examples 3 and 4: Carboxymethyl cellulose was used to make an adhesive with a 1.4% content. After uniform dispersion, 20g of adhesive was mixed with 25g of negative electrode material, and the mixture was placed in a 10cm x 10cm aluminum plastic film bag and sealed. The volume of the aluminum plastic film bag was tested every 24 hours by draining the water into a measuring cylinder.

[0253] (12) Test method for mass content of carbon element in negative electrode material: Using a G4ICARUSHF infrared carbon and sulfur analyzer from Bruker, Germany, the sample was burned under high-temperature, oxygen-enriched conditions, and the carbon and sulfur elements contained therein were oxidized to carbon dioxide and sulfur dioxide, respectively. The resulting gases entered the infrared detector along with the carrier gas, and the carbon and sulfur element contents were calculated by quantitatively analyzing the changes in the carbon dioxide and sulfur dioxide signals.

[0254] (13) Test method for mass content of silicon element in negative electrode material: The samples were fired in an oxygen atmosphere using a Nanyang Shinyu SA2-9-17TP box-type atmosphere furnace, and the silicon and silicon oxide in the samples reacted to form silica. After the carbon was burned, it became carbon dioxide and was emitted. The samples were then weighed to calculate the silicon content.

[0255] (14) Test method for tap density of negative electrode material: Using a Hyakutokusha tap density device, 100 g of sample was weighed and tested for tap density by vibrating 3000 times at 300 times / min.

[0256] (15) Particle size D of negative electrode material 10 , D 50 and D 90 Testing method: Using a laser particle sizer 50 The volume-based distribution was measured and showed a symmetric distribution similar to a normal distribution. In the volume-based distribution, the cumulative 50% diameter was D 50 By analogy, the cumulative 90% diameter is D 90 and the cumulative 10% diameter is D 10 It was.

[0257] (16) Test method for the mass contents of nitrogen, oxygen, and hydrogen elements in the negative electrode materials prepared in Examples 10 to 21 and Comparative Examples 3 and 4: Using an ONH2000 oxygen, nitrogen, and hydrogen elemental analyzer from Germany's Verder, the anode removal material was wrapped in flux and melted in an inert atmosphere, and the oxygen contained therein was reduced to carbon dioxide by the carbon in the graphite crucible. The carbon dioxide produced entered the infrared detector along with the carrier gas, and the oxygen content was calculated by quantitatively measuring the change in the carbon dioxide signal. The sample was wrapped in flux and melted in an inert atmosphere, and the nitrogen and hydrogen contained therein decomposed to form stable elemental nitrogen and hydrogen, respectively. The nitrogen and hydrogen produced entered the thermal conductivity detector along with the carrier gas, and the mass content of the nitrogen and hydrogen elements was calculated by quantitatively measuring the change in heat in the thermal conductivity pool.

[0258] (17) Resistivity test of negative electrode material powder: Using a Mitsubishi Chemical Corporation MCP-PD51 powder conductivity instrument from Japan, the system used a four-point probe method to measure the volume resistivity of the sample. The device was used to measure the resistance of the powder, and then the computer automatically calculated the powder conductivity and resistivity of the powder. The powder conductivity was tested at five pressure points: 4, 8, 12, 16, and 20 KN.

[0259] (18) Compaction density test of negative electrode materials: Using a CARVER4350.22 powder compact density apparatus manufactured by Microcro, USA, a sample with a predetermined mass m was placed in a mold, a pressure of 1.0 T was applied, and after holding the pressure for 30 s, the pressure was removed and the thickness was measured and calculated to obtain the green density.

[0260] The results of the above performance tests are as follows:

[0261] [Table 1] Performance parameters of the negative electrode materials prepared in Examples 1 to 9 and Comparative Examples 1 and 2

[0262] [Table 2] Performance parameters of the batteries of Examples 1 to 9 and Comparative Examples 1 and 2

[0263] As can be seen from the data in Tables 1 and 2, the mass content A of oxygen, mass content B of nitrogen, and powder conductivity P of the negative electrode materials prepared in Examples 1 to 9 all satisfied the relationship (A+B) / P≦3. A primary carbonization process can be performed using a mixture of a carbon source and a modifier to dope the modifier into the carbon matrix. A secondary carbonization process can be performed at a temperature higher than that of the primary carbonization process. The high temperature can improve the graphitization degree of the carbon matrix and the electronic conductivity of the carbon matrix itself. Furthermore, during the secondary carbonization process, more oxygen-containing or nitrogen-containing groups are volatilized, allowing the mass content of nitrogen and oxygen in the carbon matrix to be controlled. The doping of a small amount of nitrogen and oxygen can provide lone pairs of electrons, which can participate in the π-π conjugated system of the carbon matrix, thereby forming a larger p-π conjugated system and further increasing the electronic conductivity of the negative electrode material. Finally, the carbon matrix and silicon particles can be combined to improve the capacity of the negative electrode material. The pores in the carbon matrix are beneficial for mitigating the volume expansion of the silicon particles during cycling, maintaining structural stability, and reducing the collapse of the material structure due to volume expansion during the lithium release process of the negative electrode material. The pores in the carbon matrix can also adsorb a small amount of gas, further reducing the gas generation phenomenon of the negative electrode material and improving the cycling performance of the negative electrode material.

[0264] As can be seen from the test data of Examples 1 to 4, the initial reversible capacity of the negative electrode material tends to decrease as the mass content of nitrogen element decreases. Preferably, the mass content of the nitrogen element is 0.1% to 0.5%.

[0265] As can be seen from the test data of Examples 1 and 7 in Tables 1 and 2, the secondary carbonization temperature of Example 7 was too high. A carbonization temperature that was too high improved the graphitization degree of the carbon matrix and improved the powder conductivity of the negative electrode material. However, a carbonization temperature that was too high caused some of the pores in the carbon matrix to collapse, resulting in more silicon being deposited on the surface of the carbon matrix rather than in the pores. This also reduced the silicon content in the negative electrode material, and some silicon was deposited on the surface of the carbon matrix, resulting in severe volume expansion of the negative electrode material. As a result, the initial coulombic efficiency and cycle performance of the negative electrode material were lower than those of Example 1.

[0266] As can be seen from the test data of Example 1 and Comparative Example 1 in Tables 1 and 2, the mass content A of oxygen element, the mass content B of nitrogen element, and the powder conductivity P of the negative electrode material of Comparative Example 1 do not satisfy (A+B) / P≦3. The negative electrode material of Comparative Example 1 does not undergo secondary carbonization treatment in the production process, so more oxygen- or nitrogen-containing groups remain in the carbon matrix, resulting in a significant increase in the mass content of nitrogen and oxygen in the negative electrode material. However, the carbon matrix does not undergo secondary carbonization treatment, so the degree of graphitization is reduced and the conductivity of the carbon matrix itself is significantly reduced. Although doping oxygen- or nitrogen-containing groups with a small amount of nitrogen and oxygen can provide lone pairs of electrons, it does not significantly improve the electronic conductivity of the negative electrode material, resulting in a decrease in the capacity of the negative electrode material and a decrease in the initial coulombic efficiency and cycle performance.

[0267] As can be seen from the test data of Example 1 and Comparative Example 2 in Tables 1 and 2, the mass content A of oxygen element, the mass content B of nitrogen element, and the powder conductivity P of the negative electrode material of Comparative Example 2 do not satisfy (A+B) / P≦3. The negative electrode material of Comparative Example 2 does not add any modifier during the manufacturing process, and does not have sufficient amounts of nitrogen-containing groups and oxygen-containing groups to be able to combine with the carbon matrix to form carbon-carbon conjugates. In addition, the secondary carbonization temperature is lower than the primary carbonization temperature, which significantly reduces the conductivity of the carbon matrix and therefore significantly reduces the electronic conductivity of the negative electrode material, resulting in a decrease in the capacity of the negative electrode material and a decrease in the initial coulombic efficiency and cycle performance.

[0268] [Table 3] Performance parameter table of negative electrode materials of Examples 10 to 21 and Comparative Examples 3 and 4

[0269] [Table 4] Performance parameter table of negative electrode materials of Examples 10 to 21 and Comparative Examples 3 and 4

[0270] [Table 5] Battery performance parameter table for Examples 10 to 21 and Comparative Examples 3 and 4

[0271] As can be seen from the data in Tables 3 to 5, the negative electrode materials manufactured in Examples 10 to 17 contain oxygen and nitrogen elements. A small amount of nitrogen and oxygen elements can provide lone pairs of electrons, and the lone pairs of electrons can participate in the π-π conjugation system of the carbon matrix, thereby forming a larger p-π conjugation system and further increasing the electron conductivity of the negative electrode material. Furthermore, the negative electrode material is doped with sulfur element together with nitrogen and oxygen doping, and the sulfur content of the negative electrode material is 0 < S ≤ 20 ppm. Since the sulfur element has a relatively large atomic radius, it can form a C-S bond with carbon element and lithium storage activity in the negative electrode material, and further expand the distance between carbon layers of the carbon matrix after nitrogen and oxygen element doping, making the conductivity of the carbon matrix higher. Also, the sulfur element combines with the oxygen element to form an inactive S-O bond, which can reduce the problem of gas generation due to the reaction between the battery manufactured with the negative electrode material and the electrolyte. Moreover, after sulfur element doping, the relationship between the content of oxygen element, the content of nitrogen element and the powder conductivity satisfies (A + B) / P ≤ 3, that is, the mass content A of oxygen element, the mass content B of nitrogen element and the powder conductivity P are balanced, so that nitrogen and oxygen doping improves the powder conductivity of the negative electrode material and alleviates the problem of increased gas generation of the electrolyte due to too high content of nitrogen and oxygen, enabling the negative electrode material to have both excellent conductive performance and cycle performance.

[0272] Furthermore, in the manufacturing process of the negative electrode material, through steps such as high-temperature treatment, that is, secondary carbonization treatment, the high-temperature treatment improves the graphitization degree of the carbon material, forms more continuous conductive networks, and improves the conductivity of the negative electrode material. On the other hand, at high temperature, more O, N, S groups volatilize, and the contents of nitrogen, oxygen and sulfur elements can be effectively controlled, reducing the gas generation problem of the negative electrode material on the premise of maintaining a relatively high conductivity.

[0273] As can be seen from the test results of Examples 10 and 18, the doping amount of sulfur is high, and sulfur can combine with oxygen to form inactive SO bonds, which further reduces the gas generation value of the anode material. However, the carbon interlayer spacing of the carbon matrix after doping with sulfur is further increased, which slightly reduces the structural stability of the carbon matrix, and the cycle capacity retention rate of the anode material is slightly lower than that of Example 10.

[0274] As can be seen from the test results of Examples 10 and 19, the doping amounts of nitrogen and oxygen are relatively large, which increases the powder conductivity of the anode material and improves the initial coulombic efficiency of the anode material. However, the gas generation value of the anode material increases compared to Example 10 due to the decrease in the ability of sulfur to combine with oxygen to form inactive SO bonds.

[0275] As can be seen from the test results of Example 10 and Example 20, no thiol was added in the manufacturing process of Example 20, the sulfur element content of the negative electrode material was 0, and the initial Coulombic efficiency of the negative electrode material was equivalent to that of Example 10. However, due to the manufacturing method, the total pore volume and specific surface area of ​​the negative electrode material were too large, so the gas generation value of the negative electrode material was significantly higher than that of Example 10, and the cycle performance of the negative electrode material was reduced.

[0276] As can be seen from the test results of Examples 10 and 21, Example 21 is manufactured by first performing activation and then high-temperature treatment (i.e., secondary carbonization treatment), and the high-temperature treatment causes pore collapse, a decrease in pore volume, and uneven deposition, resulting in an increase in the gas generation value of the negative electrode material and a decrease in cycle performance.

[0277] As can be seen from the test results of Example 10 and Comparative Example 3, the negative electrode material without high temperature treatment in Comparative Example 3 has a sulfur doping amount that is significantly beyond the ideal range, and the nitrogen doping amount is also significantly higher than that of Example 10. This causes an imbalance between the oxygen mass content A, the nitrogen mass content B and the powder conductivity P, resulting in a significantly higher gas generation value of the negative electrode material. The excessive sulfur doping amount affects the structural stability of the carbon matrix, and reduces the cycle performance of the negative electrode material.

[0278] As can be seen from the test results of Example 10 and Comparative Example 4, the comparative example 4 does not use nitrogen and oxygen doping in the manufacturing process, which reduces the powder conductivity of the negative electrode material and obviously reduces the initial coulomb efficiency of the negative electrode material.

[0279] As the applicant expresses, the present disclosure uses the above examples to describe the detailed process equipment and process flow of the present disclosure, but the present disclosure is not limited to the above detailed process equipment and process flow, that is, it does not mean that the present disclosure cannot be implemented without relying on the above detailed process equipment and process flow. Those skilled in the art should clearly understand that any improvements to the present disclosure, equivalent substitutions and addition of auxiliary components for each raw material of the product of the present disclosure, selection of specific methods, etc. are all within the protection scope and disclosure scope of the present disclosure.

Claims

1. an active material, the active material including a carbon matrix and a silicon material; The negative electrode material contains oxygen and nitrogen, the mass content of the oxygen is A%, and the mass content of the nitrogen is B%, The negative electrode material has a powder conductivity of P S / m and satisfies the relationship (A+B) / P≦3.

2. (1) the silicon material includes silicon particles; (2) The silicon material includes silicon particles and a silicon oxide layer located on the surface of the silicon particles, the silicon oxide layer includes silicon oxide, and the general formula of the silicon oxide is SiO ｘ That is, (3) The anode material according to claim 1, wherein the silicon material comprises silicon particles and a silicon oxide layer located on the surface of the silicon particles, and when the mass of the silicon material is calculated as 100%, the mass percentage content of oxygen element in the silicon material is 1% to 18%.

3. 3. The negative electrode material according to claim 2, wherein the carbon matrix has pores, and at least some of the silicon particles are distributed within the pores of the carbon matrix.

4. The negative electrode material according to any one of claims 1 to 3, further containing a sulfur element, and the content of the sulfur element in the negative electrode material is S ppm, where 0 < S ≦ 20 ppm.

5. (1) In the negative electrode material, the mass content of the oxygen element is A%, and 0<A≦3%; (2) The negative electrode material according to any one of claims 1 to 4, characterized in that the mass content of the nitrogen element is B% and 0<B≦3% is satisfied.

6. (1) The silicon particles contain at least one of elemental silicon, silicon oxide, silicon alloy, and silicon carbon composite; (2) the average particle size of the silicon particles is 0.1 nm to 500 nm; (3) The negative electrode material according to any one of claims 2 to 5, characterized in that the mass content of silicon element in the silicon particles is ≧99%.

7. The negative electrode material is (1) Median diameter D of the negative electrode material ５０ ≦10 μm, (2) The specific surface area of ​​the negative electrode material is ≦5 m ２ / g, (3) The amount of gas generated from the negative electrode material over 6 days is M mL / g, and M≦0.2; (4) The negative electrode material according to any one of claims 1 to 6, characterized in that the powder conductivity of the negative electrode material is P S / m, and P≧0.01 S / m.

8. The negative electrode material has pores, and the negative electrode material (1) The pores in the negative electrode material include mesopores, and the volume of the mesopores in the negative electrode material accounts for 87% to 97% of the total pore volume of the negative electrode material; (2) The pores of the negative electrode material further include at least one of micropores and macropores; (3) The pores of the negative electrode material further include at least one of micropores and macropores, and the ratio of the volume of the micropores to the total pore volume of the negative electrode material is ≦20% and the ratio of the volume of the macropores to the total pore volume of the negative electrode material is ≦10%; (4) The pores of the negative electrode material further include at least one of micropores and macropores, and the ratio of the volume of the micropores to the total pore volume of the negative electrode material is ≦5% and the ratio of the volume of the macropores to the total pore volume of the negative electrode material is ≦10%; (5) the average pore size of the pores in the negative electrode material is 0.5 nm to 20 nm; (6) The total pore volume of the negative electrode material is 0.001 cm ３ / g to 0.1 cm ３ / g, (7) The powder conductivity of the negative electrode material is 10 －１ S / cm to 10 ４ 8. The negative electrode material according to claim 1, wherein the negative electrode material has at least one of the following properties: S / cm.

9. (1) The pores in the negative electrode material after the silicon particles have been removed include micropores, and the ratio of the volume of the micropores in the negative electrode material after the silicon particles have been removed to the total pore volume in the negative electrode material after the silicon particles have been removed is ≧80%; (2) the average pore size of the negative electrode material after removing the silicon particles is ≦5 nm; (3) The total pore volume of the negative electrode material after removing the silicon particles is 0.2 cm ３ / g to 2cm ３ / g, (4) The negative electrode material according to any one of claims 2 to 8, characterized in that the porosity of the negative electrode material after removing the silicon particles is 40% to 60%.

10. The negative electrode material is (1) The particle size of the negative electrode material is 2 μm≦D ５０ ≦20μm, 0.9≦(D ９０ -D １０ ) / D ５０ ≦5 is satisfied, (3) The specific surface area of ​​the negative electrode material is 1 m ２ / g to 10m ２ / g, (4) The green density of the negative electrode material is 0.80 cm ３ / g ~ 1.30 cm ３ / g, (5) The tap density of the negative electrode material is 0.50 cm ３ / g ~ 1.50 cm ３ The negative electrode material according to any one of claims 1 to 9, characterized in that it has at least one of the following properties: / g.

11. The negative electrode material is (1) The mass content of carbon element in the negative electrode material is 40% to 60%; (2) The negative electrode material according to any one of claims 1 to 10, characterized in that the mass content of silicon element in the negative electrode material is at least one of 35% to 55%.

12. The carbon matrix is (1) The carbon matrix contains at least one of hard carbon, soft carbon, graphite, mesocarbon microbeads, activated carbon, porous carbon, mesoporous carbon, and carbon gel; (2) The carbon matrix contains a functional group at at least one of the surface, the carbon-carbon skeleton, the carbon layer gaps, and the lattice defects, and the functional group contains at least one of oxygen, nitrogen, and sulfur elements; (3) The negative electrode material according to any one of claims 1 to 11, characterized in that the carbon matrix has functional groups on its surface and / or in its pores, the functional groups containing at least one of oxygen, nitrogen, and sulfur, and the functional groups contain at least one of hydroxyl, carboxyl, carbonyl, ester, endocyclic ester, amino, mercapto, sulfate, sulfite, thioether, and sulfonic acid groups.

13. The silicon particles are (1) The silicon particles contain at least one of amorphous silicon, crystalline silicon, silicon oxide, silicon alloy, and a composite of crystalline silicon and amorphous silicon; (2) The negative electrode material according to any one of claims 2 to 12, characterized in that the shape of the silicon particles includes at least one of dot-like, spherical, elliptical, and sheet-like shapes.

14. The negative electrode material according to any one of claims 1 to 13, characterized in that a coating layer is formed on at least a portion of the surface of the negative electrode material, and the material of the coating layer contains at least one of a carbon material, titanium nitride, boron nitride, silicon nitride, silicon oxide, magnesium oxide, aluminum oxide, silicon carbide, and polyaniline.

15. A battery comprising the negative electrode material according to any one of claims 1 to 14.

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