Anode materials and batteries

Abstract

The present application provides a negative electrode material and a battery. The negative electrode material includes a carbon material and a silicon material, the silicon material being located inside and / or between the carbon materials, and the total volume of the carbon materials being V C The total volume of the silicon material is V Si Then, 0.9≦V C / V Si The cross section of the negative electrode material particle observed by SEM is determined to have an area of ​​A × B (where A × B = 10 4 nm 2 ), and the average distance between adjacent silicon material particles in any one unit area is d (nm), where d satisfies 3≦d≦50. The negative electrode material according to the present application can improve the dispersion uniformity of the silicon material, effectively suppress volume expansion of the negative electrode material, and improve the cycle characteristics of the battery.

Description

[Technical Field]

[0001] This application claims priority to Chinese patent application No. 202311842097.6, filed on December 29, 2023, with the State Intellectual Property Office of the People's Republic of China, entitled "Negative electrode material, manufacturing method thereof, and battery," and to Chinese patent application No. 202410365578.0, filed on March 27, 2024, with the State Intellectual Property Office of the People's Republic of China, entitled "Negative electrode material, manufacturing method thereof, and battery," the entire contents of which are incorporated herein by reference.

[0002] This application relates to the technical field of anode materials, and more particularly to anode materials and batteries. [Background technology]

[0003] Lithium-ion batteries have been widely used in electric vehicles and consumer electronics due to their advantages of high energy density, long cycle life, minimal environmental pollution, and no memory effect. In recent years, the rapid development of electric vehicles has led to an increasing demand for lithium-ion batteries with higher energy densities. Researchers are therefore seeking battery materials with higher energy densities and better cycle performance. Cathode and anode materials are the core components of a battery and determine its operating efficiency. Currently, the only commercially available anode material is graphite, whose capacity is already close to its theoretical limit, with limited room for further improvement. Therefore, the development of next-generation high-energy-density anode materials is urgently needed. Among these, silicon-based anode materials are generally considered to be the next-generation battery anode materials due to their advantages of high capacity, abundant supply, and relative safety.

[0004] Silicon-based anode materials are generally considered next-generation battery anode materials due to their advantages of high capacity, abundant supply sources, and relative safety. However, silicon-based anode materials experience rapid volume expansion during cycling, which can lead to material pulverization and shattering, resulting in rapid decay with cycling. Silicon-carbon composites are generally used to suppress the volume expansion of silicon, but conventional composites tend to cause agglomeration, which results in excessive local expansion stress in the anode material and affects the cycling stability of the anode material. Summary of the Invention [Problem to be solved by the invention]

[0005] The present application provides an anode material and a battery that can improve the dispersion uniformity of silicon material, effectively suppress volume expansion of the anode material, and improve the cycle characteristics of the battery. [Means for solving the problem]

[0006] In a first aspect, the present application provides an anode material comprising a carbon material and a silicon material, The silicon material is located inside and / or between the carbon material particles, and the total volume of the carbon material is V C The total volume of the silicon material is V Si Then, 0.9≦V C / V Si ≦2.3, The cross section of the negative electrode material particle observed by SEM is defined as an area A × B (where A × B = 10 4 nm 2 ), and the average value of the distance between adjacent silicon material particles in any one unit area is d nm, where d satisfies 3≦d≦50.

[0007] In a second aspect, the present application provides an anode material comprising a carbon material and a silicon material, The silicon material is located inside and / or between the carbon material particles, and the total volume of the carbon material is V C The total volume of the silicon material is V Si Then, 0.9≦V C / V Si ≦2.3, The cross section of the negative electrode material particle observed by SEM is defined as an area A × B (where A × B = 10 4 nm 2 ) and the number of silicon material particles in each unit area is N particles, N of the unit areas satisfies 1≦N≦30 in each case, thereby providing a negative electrode material.

[0008] In a third aspect, the present application provides a battery including the above-described negative electrode material. [Effects of the Invention]

[0009] The technical solution of the present application has at least the following beneficial effects:

[0010] According to the negative electrode material provided herein, the negative electrode material comprises a carbon material and a silicon material, and the silicon material is located within and / or between the carbon material particles. The average distance between adjacent silicon material particles within any one unit area, d nm, satisfies the relationship 3≦d≦50. This allows the silicon material to be uniformly dispersed within and between the carbon material particles, reducing excessive local stress in the negative electrode material due to aggregation of the silicon material and reducing crushing and pulverization of the negative electrode material particles. Furthermore, by controlling the volume ratio of the carbon material to the silicon material within the range of 0.9 to 2.3, the conductivity of the negative electrode material can be increased, the volume expansion effect of the silicon material during cycling can be effectively mitigated, the structural stability of the negative electrode material particles can be maintained, and the cycle performance of the negative electrode material can be improved.

[0011] According to the negative electrode material provided herein, the negative electrode material comprises a carbon material and a silicon material, the silicon material being located within and / or between the carbon material particles, and where N is the number of silicon material particles within a unit area, N satisfies the relationship 1≦N≦30 for each unit area. This allows the silicon material to be uniformly dispersed within and between the carbon material particles, reducing excessive local stress in the negative electrode material due to aggregation of the silicon material and reducing crushing and pulverization of the negative electrode material particles. Furthermore, by controlling the volume ratio of the carbon material to the silicon material within a range of 0.9 to 2.3, the conductivity of the negative electrode material can be increased, the volume expansion effect of the silicon material during cycling can be effectively mitigated, the structural stability of the negative electrode material particles can be maintained, and the cycle performance of the negative electrode material can be improved. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a process flow diagram of a method for producing a negative electrode material according to the present application. [Figure 2] 1 is a SEM photograph of the negative electrode material produced in Example 1 of the present invention. [Figure 3] FIG. 2 is a diagram showing an XRD (X-ray diffraction) pattern of the negative electrode material produced in Example 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0013] In order to better explain the present application and facilitate understanding of the technical solution of the present application, the present application will be described in more detail below. However, the following examples are merely simplified examples of the present application, and do not indicate or limit the scope of protection of the present application, which is governed by the claims.

[0014] In a first aspect, the present application provides an anode material as follows: The anode material comprises a carbon material and a silicon material, the silicon material being located inside and / or between carbon material particles, and the total volume of the carbon material being V C The total volume of the silicon material is V SiThen, 0.9≦V C / V Si Satisfies ≦2.3. The cross section of the negative electrode material particle observed by SEM is defined as an area A × B (where A × B = 10 4 nm 2 ), and the average distance between adjacent silicon material particles in any one unit area is d nm, where d satisfies 3≦d≦50. Specifically, the distance between adjacent silicon material particles is the distance between the centers of adjacent silicon material particles. Specifically, the cross section of the negative electrode material particle observed with an SEM is divided into a plurality of unit areas each having an area of ​​A×B (where A×B=100 nm×100 nm=10 4 nm 2 ) is divided into a plurality of unit areas. Five unit areas are randomly selected from the cross-sectional view observed by SEM, and within each of the selected unit areas, ten pairs of two adjacent silicon material particles are randomly selected. For each of the ten pairs, the distance between the centers of the two silicon material particles on the cross-sectional view observed by SEM is measured, and then converted to an actual distance d0 nm based on the scale, and the average value of 50 d0 is calculated as d.

[0015] In some embodiments, when the distance between adjacent silicon material particles in a unit area is d0 (nm), at least one d0 satisfies 3≦d0≦50. When the silicon material particles are uniformly distributed, the distance d0 between any two adjacent silicon material particles is the same, and in this case, the average value d of the distances between adjacent silicon material particles is the distance d0.

[0016] The negative electrode material provided herein includes a carbon material and a silicon material, wherein the silicon material is located within and / or between carbon material particles, and the average distance between adjacent silicon material particles within any one unit area, d nm, satisfies the relationship 3≦d≦50. This allows the silicon material particles to be uniformly dispersed within and / or between the carbon material, reducing excessive local stress in the negative electrode material due to aggregation of the silicon material and reducing crushing and pulverization of the negative electrode material particles. Furthermore, by controlling the volume ratio of the carbon material to the silicon material within a range of 0.9 to 2.3, the conductivity of the negative electrode material can be increased, the volume expansion effect of the silicon material during cycling can be effectively mitigated, the structural stability of the negative electrode material particles can be maintained, and the cycle performance of the negative electrode material can be improved.

[0017] In some embodiments, the cross section of the negative electrode material particle observed by SEM is measured to have an area of ​​A×B (where A×B=10 4 nm 2 ), and the number of silicon material particles in each unit area is N, N for each unit area satisfies 1≦N≦30. Specifically, the cross section of the negative electrode material particle observed by SEM is divided into a plurality of unit areas each having an area of ​​A×B (where A×B=100nm×100nm=10 4 nm 2 ), five unit areas are randomly selected, and the number N of silicon material particles in each selected unit area is calculated.

[0018] In the above technical proposal, the negative electrode material includes a carbon material and a silicon material, and the silicon material is located within and / or between the carbon material particles. The number of silicon material particles within a unit area is N, and N for each unit area satisfies 1≦N≦30. This allows the silicon material to be uniformly dispersed within and between the carbon material particles, reducing excessive local stress in the negative electrode material due to aggregation of the silicon material and reducing particle crushing and pulverization of the negative electrode material. Furthermore, controlling the volume ratio of the silicon material to the carbon material within the range of 0.9 to 2.3 increases the conductivity of the negative electrode material, effectively mitigating the volume expansion effect of the silicon material during cycling, maintaining the structural stability of the negative electrode material particles, and ultimately improving the cycling performance of the negative electrode material.

[0019] In some embodiments, the silicon material comprises at least one of crystalline silicon, amorphous silicon, and a silicon alloy.

[0020] The silicon alloy may be a silicon-lithium alloy, a silicon-magnesium alloy, etc. In some cases, the silicon material includes amorphous silicon and a silicon alloy. Preferably, the silicon material includes amorphous silicon. Amorphous silicon expands isotropically during the lithium absorption process, thereby reducing the collapse of the pore structure in the negative electrode material, suppressing the rapid decay of the specific capacity of the negative electrode material, and improving the lithium absorption cycle characteristics of the negative electrode material.

[0021] In some embodiments, the average particle size of the silicon material is 1 nm to 50 nm, and specifically may be 1 nm, 2 nm, 5 nm, 8 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, or 50 nm, etc., but is not limited thereto. A silicon material of an appropriate size can improve the uniformity of distribution between the silicon material and the carbon matrix, reduce the uneven distribution of the silicon material, and improve the cycle characteristics of the negative electrode material. Preferably, the average particle size of the silicon material is 1 nm to 10 nm, and more preferably, the average particle size of the silicon material is 1 nm to 5 nm.

[0022] In some embodiments, the mass content of silicon element in the silicon material is 99% or more. Having the mass content of silicon element in the silicon material within the above range is advantageous for improving the purity of the silicon material and reducing impurities in the silicon material.

[0023] In some embodiments, the silicon material comprises silicon particles.The shape of silicon particles comprises at least one of dot-like, spherical, oval-spherical and sheet-like, and the shape of silicon particles can be selected according to actual needs, and is not limited thereto.

[0024] 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 has the general formula SiO x (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 is not limited thereto.

[0025] In some embodiments, the silicon material comprises silicon particles and a silicon oxide layer located on the surface of the silicon particles, and the mass content of the oxygen atoms in the silicon material is 1% to 18%, where the mass of the silicon material is 100%. Specifically, the mass content of the oxygen atoms 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 content of the oxygen atoms in the silicon material within the above range is advantageous for forming a stable silicon oxide layer on the surface of the silicon particles, reducing direct contact between the silicon particles and the electrolyte, thereby reducing side reactions between the silicon material and the electrolyte, improving the cycle stability of the negative electrode material, ensuring stable activity of the silicon material, and increasing the specific capacity of the negative electrode material.

[0026] In some embodiments, the carbon material comprises at least one of amorphous carbon, crystalline carbon, graphite fibers, carbon nanotubes, carbon fibers, and mesocarbon microbeads. The carbon material can reduce the volume expansion effect of the negative electrode material to some extent and increase the conductivity of the negative electrode material. The carbon material can also reduce direct contact between the silicon 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.

[0027] In some embodiments, the carbon material has pores, and the silicon material is at least partially located within the pores of the carbon material. The pore structure of the carbon material provides space for the volume expansion of the silicon material, effectively mitigating the volume expansion effect of the silicon material and improving the cycle characteristics of the negative electrode material.

[0028] In some embodiments, the median diameter of the negative electrode material is 5 μm to 15 μm, and specifically may be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 12 μm, 13 μm, 14 μm, or 15 μm, or may be other values ​​within the above range, and is not limited thereto. Controlling the median diameter of the negative electrode material within the above range is advantageous in improving the cycle characteristics of the negative electrode material.

[0029] In some embodiments, the specific surface area of ​​the negative electrode material is less than 1 m 2 / g~20m 2 / g, specifically, 1m 2 / g, 1.5m 2 / g, 2m 2 / g, 3m 2 / g, 5m 2 / g, 8m 2 / g, 10m 2 / g, 15m 2 / g or 20m 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 for improving the initial coulombic efficiency and cycle characteristics of a lithium battery manufactured using the negative electrode material.

[0030] In some embodiments, the mass content of carbon element in the negative electrode material is 30% to 75%, and specifically may be 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, or 75%, etc., but is not limited thereto.

[0031] In some embodiments, the mass content of silicon element in the negative electrode material is 25% to 65%, and specifically may be 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, or 65%, etc., but is not limited thereto.

[0032] In a second aspect, the present application provides a method for producing a negative electrode material, as shown in FIG. 1, comprising the following steps: Step S10: preparing a mixed solution containing a silicon material and a dispersant, adding a coagulating liquid to the mixed solution and performing a mixing treatment, and then performing solid-liquid separation to obtain a precursor; Step S20: Mixing the precursor and the carbon source precursor, and then preheating to obtain a composite; Step S30: The composite is carbonized to obtain a negative electrode material.

[0033] The method for producing a negative electrode material according to the present invention includes first dispersing a silicon material in a mixed solution containing a dispersant to thoroughly disperse the silicon material, then adding a coagulant to simultaneously coagulate and precipitate the silicon material and the dispersant, followed by solid-liquid separation to obtain a composite. The presence of the dispersant on the surface of the silicon material reduces the coagulation of the silicon material. Next, the precursor and a carbon source are mixed. In a single heat treatment process, the carbon source melts and penetrates to replace the dispersant located on the surface of the silicon material, maintaining the silicon material dispersed in the carbon source precursor. Finally, a preheating treatment and a carbonization treatment are performed to obtain a negative electrode material. The silicon material in the negative electrode material is dispersed inside and between the carbon material particles, improving the conductivity of the negative electrode material. This effectively mitigates the volume expansion effect of the silicon material during cycling, maintains the structural stability of the negative electrode material particles, and ultimately improves the cycle performance of the negative electrode material.

[0034] The technical solution of the present application will be described in detail below.

[0035] Step S10: A mixed liquid containing a silicon material and a dispersant is prepared, and the aggregating liquid is added to the mixed liquid to perform a mixing treatment, followed by solid-liquid separation to obtain a precursor.

[0036] In some embodiments, the silicon material comprises at least one of crystalline silicon, amorphous silicon, and a silicon alloy.

[0037] The silicon alloy may be a silicon-lithium alloy, a silicon-magnesium alloy, etc. In some cases, the silicon material includes amorphous silicon and a silicon alloy. Preferably, the silicon material includes amorphous silicon. Amorphous silicon expands isotropically during the lithium absorption process, reducing the collapse of the pore structure, suppressing the rapid decay of the specific capacity, and improving the lithium absorption cycle characteristics.

[0038] In some embodiments, the average particle size of the silicon material is 1 nm to 50 nm, and specifically may be 1 nm, 2 nm, 5 nm, 8 nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, or 50 nm, etc., but is not limited thereto.

[0039] In some embodiments, the dispersing agent comprises at least one of stearic acid, sodium stearate, zinc stearate, magnesium stearate, calcium stearate, polyvinylpyrrolidone, carboxymethylcellulose, and polyacrylic acid.

[0040] In some embodiments, the mass ratio of the silicon material to the dispersant is 100: (20-100), specifically, 100:20, 100:30, 100:40, 100:50, 100:60, 100:70, 100:80, 100:90, or 100:100, etc., and of course, other values ​​within the above range may also be used, and are not limited thereto. An appropriate amount of dispersant can improve the degree of dispersion of the silicon material in the mixed liquid, reduce the aggregation of the silicon material, and thus improve the degree of dispersion of the silicon material in the precursor.

[0041] In some embodiments, the mixture further comprises a solvent, the solvent comprising at least one of water, methanol, ethanol, ethylene glycol, propanol, isopropanol, glycerin, n-butanol, isobutanol, pentanol, and ethyl acetate.

[0042] In some embodiments, the mixing is carried out under stirring.

[0043] In some embodiments, the mixing time is 0.5 hours to 3 hours, and specifically may be 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, or 3 hours, etc., and of course may be other values ​​within the above range and is not limited thereto.

[0044] In some embodiments, the solid-liquid separation step includes filtering the mixture after adding the flocculating liquid and freeze-drying it to obtain the precursor.

[0045] In some embodiments, the mass ratio of silicon material to flocculating liquid is 1:(1-1.3), specifically can be 1:1, 1:1.05, 1:1.08, 1:1.1, 1:1.2, 1:1.25 or 1:1.3, etc., and of course can be other values ​​within the above range, and is not limited here.

[0046] In some embodiments, the solid content of the flocculation liquid is 0.1% to 0.5%, and specifically may be 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%, etc., and of course may be other values ​​within the above range, and is not limited thereto.

[0047] In some embodiments, the flocculating liquid comprises a flocculant, the flocculant comprising at least one of an inorganic flocculant and an organic flocculant.

[0048] In some embodiments, the inorganic flocculant comprises at least one of aluminum sulfate, aluminum chloride, iron sulfate, and iron chloride.

[0049] In some embodiments, the organic flocculant comprises at least one of polyaluminum chloride, polyaluminum sulfate, and polyacrylamide.

[0050] In the present invention, the dispersed silicon material of nano-order can be precipitated in an aggregated state by adding the aggregating liquid to the mixed liquid. In addition, since the dispersant is contained on the surface of the silicon material, the silicon material in the aggregated product still maintains a dispersed state independent from each other.

[0051] In some embodiments, the freeze-drying temperature is -20°C to -30°C, and specifically may be -20°C, -22°C, -24°C, -25°C, -27°C, -28°C, or -30°C, etc., but is not limited thereto.

[0052] In some embodiments, the freeze-drying time is 10 to 24 hours, and specifically may be 10, 12, 15, 18, 20, 22, or 24 hours, etc., but is not limited thereto. The freeze-drying process allows the nano-order silicon material to be uniformly dispersed in the dispersant.

[0053] Step S20: After mixing the precursor and the carbon source precursor, a preheating treatment is carried out to obtain a composite.

[0054] In some embodiments, the carbon source precursor comprises at least one of sucrose, glucose, polyethylene, polyvinyl alcohol, polyethylene glycol, polyaniline, epoxy resin, phenolic resin, furfural resin, acrylic resin, polyethylene oxide, polyvinylidene fluoride, polyacrylonitrile, polyvinyl chloride, and asphalt.

[0055] In some embodiments, the mass ratio of the silicon material to the carbon source precursor is 100: (100-250), specifically, 100:100, 100:115, 100:130, 100:150, 100:180, 100:200, 100:220, 100:230, or 100:250, etc., and of course, other values ​​within the above range may also be used, and are not limited thereto.

[0056] In some embodiments, the temperature of the preheating treatment is 150°C to 350°C, and the temperature may be 150°C, 200°C, 250°C, 280°C, 300°C, 320°C, or 350°C, etc., but is not limited thereto.

[0057] In some embodiments, the preheating time is 2 to 15 hours, and specifically may be 2 hours, 3 hours, 5 hours, 8 hours, 10 hours, 12 hours, or 15 hours, etc., but is not limited thereto.

[0058] In some embodiments, the heat treatment is carried out under agitation.

[0059] By controlling the preheating temperature, preheating time and preheating conditions, the dispersant reaches its boiling point and volatilizes, and the carbon source precursor is melted and softened by sufficient preheating, and penetrates into the silicon material, replacing the dispersant located on the surface of the silicon material.

[0060] Step S30: The composite is carbonized to obtain a negative electrode material.

[0061] In some embodiments, the temperature of the carbonization treatment is 700°C to 1000°C, and the temperature may be specifically 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 980°C, or 1000°C, etc., and of course, may be other values ​​within the above range and is not limited thereto.

[0062] In some embodiments, the carbonization time is 1 hour to 10 hours, and specifically may be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 8 hours, 9 hours, or 10 hours, etc., but is not limited thereto.

[0063] In some embodiments, the temperature rise rate in the carbonization treatment is 2°C / min to 10°C / min, and specifically may be 2°C / min, 4°C / min, 5°C / min, 6°C / min, 8°C / min, 9°C / min, or 10°C / min, etc., but is not limited thereto.

[0064] In some embodiments, the carbonization process is carried out under a protective gas atmosphere.

[0065] In some embodiments, the carbonization process is carried out under a protective gas atmosphere, and the protective gas comprises at least one of nitrogen gas, helium gas, neon gas, argon gas, and krypton gas.

[0066] In some embodiments, the method further includes subjecting the carbonized product to shaping, including at least one of crushing, grinding, ball milling, and airflow milling, sieving, and classifying to obtain a negative electrode material.

[0067] In a third aspect, the present application provides a battery comprising an anode material as in the first aspect or an anode material produced by the method for producing an anode material as in the second aspect. The battery may be a lithium ion battery, a sodium ion battery, etc.

[0068] The above is merely a preferred embodiment of the present invention and is not intended to limit the present invention, and various changes, substitutions, and improvements are possible without departing from the gist of the invention. [Example]

[0069] Example 1 The method for producing the negative electrode material of this example includes the following steps. (1) 1 kg of nanosilicon particles was weighed and dispersed in an aqueous solution, then 500 g of polyvinylpyrrolidone was added and the mixture was stirred and dispersed for 1 hour. 1 kg of polyacrylamide solution with a solid content of 0.5% was then added, stirred for 10 minutes, and allowed to stand for 5 minutes. The solution was then centrifuged, and the centrifuged sample was freeze-dried at -30°C for 24 hours to obtain a precursor. (2) The precursor was placed in a VC mixer and heater, and asphalt was added at a mass ratio of nanosilicon to asphalt of 100:120. The equipment temperature was raised to 300°C under stirring conditions, and after mixing for 2 hours, the material was removed to obtain a composite. (3) The composite was placed in a box furnace, nitrogen gas was introduced, and the temperature was raised to 800°C at a heating rate of 3°C / min. The temperature was maintained for 3 hours, and then the mixture was allowed to cool naturally. The product was pulverized in a mechanical pulverizer and passed through a 325 mesh sieve to obtain the negative electrode material.

[0070] FIG. 2 is an SEM photograph of the negative electrode material prepared in Example 1 of the present invention. FIG. 3 is a diagram showing the XRD pattern of the negative electrode material prepared in Example 1 of the present invention. As shown in FIGS. 2 and 3, the negative electrode material prepared in the present example contains a carbon material and a silicon material, and the silicon material is located inside the carbon material particles and between the carbon material particles. The cross section of the negative electrode material particle prepared in Example 1 observed by SEM is divided into two parts with an area of ​​A×B (where A×B=100 nm×100 nm=10 4 nm 2 ) into multiple unit areas. Five unit areas are randomly selected from the cross-section observed by SEM. Within each of the selected unit areas, 10 pairs of two adjacent silicon material particles are randomly selected. For each of the 10 pairs, the distance between the centers of the two silicon material particles on the cross-section is measured and converted to the actual distance d0 nm based on the scale. The range of d0 for all five unit areas is within 5 to 50. Furthermore, five unit areas are randomly selected from the cross-section observed by SEM, and the number N of silicon material particles within each selected unit area is calculated. N is found to be 20, 10, 13, 18, and 29, respectively.

[0071] Example 2 (1) 1 kg of nanosilicon particles was weighed and dispersed in an aqueous solution, then 500 g of polyvinylpyrrolidone was added and the mixture was stirred and dispersed for 1 hour. 1 kg of polyacrylamide solution with a solid content of 0.5% was then added, stirred for 10 minutes, and allowed to stand for 5 minutes. The solution was then centrifuged, and the centrifuged sample was freeze-dried at -30°C for 24 hours to obtain a precursor. (2) The precursor was placed in a VC mixer and heater, and asphalt was added at a mass ratio of nanosilicon to asphalt of 100:140. The equipment temperature was increased to 300°C under stirring conditions, and after mixing for 2 hours, the material was removed to obtain a composite. (3) The composite was placed in a box furnace, nitrogen gas was introduced, and the temperature was raised to 800°C at a heating rate of 3°C / min. The temperature was maintained for 3 hours, and then the mixture was allowed to cool naturally. The product was pulverized in a mechanical pulverizer and passed through a 325 mesh sieve to obtain the negative electrode material.

[0072] The negative electrode material prepared in the examples of the present application contains a carbon material and a silicon material, and the silicon material is located inside the carbon material particles and between the carbon material particles. The cross section of the negative electrode material particle prepared in Example 2 observed by SEM was divided into 2 sections with an area of ​​A × B (where A × B = 100 nm × 100 nm = 10 4 nm 2 ) into multiple unit areas. Five unit areas are randomly selected from the cross-section observed by SEM. Within each of the selected unit areas, 10 pairs of adjacent silicon material particles are randomly selected. For each of the 10 pairs, the distance between the centers of the two silicon material particles on the cross-section is measured and converted to the actual distance d0 nm based on the scale. The range of d0 for all five unit areas is within 5 to 50. Furthermore, five unit areas are randomly selected from the cross-section observed by SEM, and the number N of silicon material particles within each of the selected unit areas is calculated. N is 12, 15, 23, 28, and 28, respectively.

[0073] Example 3 The only differences from the first embodiment are as follows. (2) The precursor was placed in a VC mixer and heater, and asphalt was added at a mass ratio of nanosilicon to asphalt of 100:180. The equipment temperature was increased to 300°C under stirring conditions, and after mixing for 2 hours, the material was removed to obtain a composite.

[0074] The negative electrode material prepared in the present example includes a carbon material and a silicon material, and the silicon material is located inside and between the carbon material particles.

[0075] The negative electrode material prepared in the present example contains an active material, the active material contains a carbon matrix and a silicon material, the carbon matrix has pores, and the silicon material is at least partially distributed in the pores of the carbon matrix. The cross section of the negative electrode material particle prepared in Example 3 observed by SEM was divided into areas A × B (where A × B = 100 nm × 100 nm = 10 4 nm 2 ) into a plurality of unit areas. Five unit areas are randomly selected from the cross-sectional view observed by SEM, and 10 pairs of two adjacent silicon material particles are randomly selected from each of the selected unit areas. For each of the 10 pairs, the distance between the centers of the two silicon material particles on the cross-sectional view is measured and converted to the actual distance d0 nm based on the scale. The range of d0 for all five unit areas is within 5 to 50. Furthermore, five unit areas are randomly selected from the cross-sectional view observed by SEM, and the number N of silicon material particles within each of the selected unit areas is calculated. N is 12, 13, 21, 27, and 28, respectively.

[0076] Example 4 The only differences from the first embodiment are as follows. (2) The precursor was placed in a VC mixer and heater, and asphalt was added at a mass ratio of nanosilicon to asphalt of 100:100. The equipment temperature was raised to 300°C under stirring conditions, and after mixing for 2 hours, the material was removed to obtain a composite. The cross section of the negative electrode material particles produced in Example 4 observed by SEM was divided into areas A×B (where A×B=100 nm×100 nm=10 4 nm 2) into multiple unit areas. Five unit areas are randomly selected from the cross-section observed by SEM. Within each of the selected unit areas, 10 pairs of adjacent silicon material particles are randomly selected. For each of the 10 pairs, the distance between the centers of the two silicon material particles on the cross-section is measured and converted to the actual distance d0 nm based on the scale. The range of d0 for all five unit areas is within 5 to 50. Furthermore, five unit areas are randomly selected from the cross-section observed by SEM, and the number N of silicon material particles within each of the selected unit areas is calculated. N is 21, 23, 11, 27, and 28, respectively.

[0077] Example 5 The only differences from the first embodiment are as follows. (2) The precursor was placed in a VC mixer and heater, and asphalt was added at a mass ratio of nanosilicon to asphalt of 100:250. The equipment temperature was increased to 300°C under stirring conditions, and after mixing for 2 hours, the material was removed to obtain a composite. The cross section of the negative electrode material particles produced in Example 5 observed by SEM was divided into areas A×B (where A×B=100 nm×100 nm=10 4 nm 2 ) into multiple unit areas. Five unit areas are randomly selected from the cross-section observed by SEM. Within each of the selected unit areas, 10 pairs of two adjacent silicon material particles are randomly selected. For each of the 10 pairs, the distance between the centers of the two silicon material particles on the cross-section is measured and converted to the actual distance d0 nm based on the scale. The range of d0 for all five unit areas is within 5 to 50. Furthermore, five unit areas are randomly selected from the cross-section observed by SEM, and the number N of silicon material particles within each of the selected unit areas is calculated. N is found to be 20, 20, 13, 17, and 18, respectively.

[0078] Example 6 The only differences from the second embodiment are as follows. (1) 1 kg of nanosilicon particles was weighed and dispersed in an ethylene glycol solution, then 200 g of polyvinylpyrrolidone was added and the mixture was stirred and dispersed for 1 hour. 1 kg of a polyacrylamide solution with a solid content of 0.5% was then added, stirred for 10 minutes, and allowed to stand for 5 minutes. The solution after standing was then centrifuged, and the centrifuged sample was freeze-dried at -20°C for 16 hours to obtain a precursor. The cross section of the negative electrode material particles produced in Example 6 observed by SEM was divided into areas A×B (where A×B=100 nm×100 nm=10 4 nm 2 ) into multiple unit areas. Five unit areas are randomly selected from the cross-section observed by SEM. Within each of the selected unit areas, 10 pairs of adjacent silicon material particles are randomly selected. For each of the 10 pairs, the distance between the centers of the two silicon material particles on the cross-section is measured and converted to the actual distance d0 nm based on the scale. The range of d0 for all five unit areas is within 5 to 50. Furthermore, five unit areas are randomly selected from the cross-section observed by SEM, and the number N of silicon material particles within each selected unit area is calculated. N is 30, 10, 13, 27, and 28, respectively.

[0079] Example 7 The only differences from the second embodiment are as follows. (1) 1 kg of nanosilicon particles was weighed and dispersed in an aqueous solution, then 800 g of polyvinylpyrrolidone was added and the mixture was stirred and dispersed for 1 hour. 1 kg of polyacrylamide solution with a solid content of 0.5% was then added, stirred for 10 minutes, and allowed to stand for 5 minutes. The solution after standing was centrifuged, and the centrifuged sample was freeze-dried at -20°C for 24 hours to obtain a precursor. The cross section of the negative electrode material particles produced in Example 7 observed by SEM was divided into areas A×B (where A×B=100 nm×100 nm=10 4 nm 2) into multiple unit areas. Five unit areas are randomly selected from the cross-section observed by SEM. Within each of the selected unit areas, 10 pairs of adjacent silicon material particles are randomly selected. For each of the 10 pairs, the distance between the centers of the two silicon material particles on the cross-section is measured and converted to the actual distance d0 nm based on the scale. The range of d0 for all five unit areas is within 5 to 50. Furthermore, five unit areas are randomly selected from the cross-section observed by SEM, and the number N of silicon material particles within each selected unit area is calculated. N is 10, 20, 23, 17, and 26, respectively.

[0080] Example 8 The only differences from the second embodiment are as follows. (1) 1 kg of nanosilicon particles was weighed and dispersed in an aqueous solution, then 350 g of polyacrylic acid was added and the mixture was stirred and dispersed for 1 hour. 1 kg of polyacrylamide solution with a solid content of 0.5% was then added, stirred for 10 minutes, and allowed to stand for 5 minutes. The solution was then centrifuged, and the centrifuged sample was freeze-dried at -20°C for 20 hours to obtain a precursor. The cross section of the negative electrode material particles produced in Example 8 observed by SEM was divided into areas A×B (where A×B=100 nm×100 nm=10 4 nm 2 ) into multiple unit areas. Five unit areas are randomly selected from the cross-section observed by SEM. Within each of the selected unit areas, 10 pairs of adjacent silicon material particles are randomly selected. For each of the 10 pairs, the distance between the centers of the two silicon material particles on the cross-section is measured and converted to the actual distance d0 nm based on the scale. The range of d0 for all five unit areas is within 5 to 50. Furthermore, five unit areas are randomly selected from the cross-section observed by SEM, and the number N of silicon material particles within each selected unit area is calculated. N is 25, 20, 23, 17, and 18, respectively.

[0081] Example 9 The only differences from the second embodiment are as follows. (1) 1 kg of nanosilicon particles was weighed and dispersed in an aqueous solution, then 600 g of sodium stearate was added and the mixture was stirred and dispersed for 1 hour. 1 kg of a 0.2% solids content aluminum sulfate solution was then added, stirred for 10 minutes, and allowed to stand for 5 minutes. The solution was then centrifuged, and the centrifuged sample was freeze-dried at -20°C for 16 hours to obtain a precursor. The cross section of the negative electrode material particles produced in Example 9 observed by SEM was divided into areas A×B (where A×B=100 nm×100 nm=10 4 nm 2 ) into multiple unit areas. Five unit areas are randomly selected from the cross-section observed by SEM. Within each of the selected unit areas, 10 pairs of two adjacent silicon material particles are randomly selected. For each of the 10 pairs, the distance between the centers of the two silicon material particles on the cross-section is measured and converted to the actual distance d0 nm based on the scale. The range of d0 for all five unit areas is within 5 to 50. Furthermore, five unit areas are randomly selected from the cross-section observed by SEM, and the number N of silicon material particles within each of the selected unit areas is calculated. N is 20, 20, 23, 25, and 8, respectively.

[0082] Example 10 The only differences from the second embodiment are as follows. (1) 1 kg of nanosilicon particles was weighed and dispersed in an aqueous solution, then 200 g of carboxymethyl cellulose was added and the mixture was stirred and dispersed for 1 hour. After that, 1 kg of iron chloride solution with a solid content of 0.2% was added, stirred for 10 minutes, and allowed to stand for 5 minutes. After standing, the solution was centrifuged, and the centrifuged sample was freeze-dried at -30°C for 24 hours to obtain a precursor. The cross section of the negative electrode material particles produced in Example 10 observed by SEM was divided into areas A×B (where A×B=100 nm×100 nm=10 4 nm 2) into multiple unit areas. Five unit areas are randomly selected from the cross-section observed by SEM. Within each of the selected unit areas, 10 pairs of adjacent silicon material particles are randomly selected. For each of the 10 pairs, the distance between the centers of the two silicon material particles on the cross-section is measured and converted to the actual distance d0 nm based on the scale. The range of d0 for all five unit areas is within 3 to 50. Furthermore, five unit areas are randomly selected from the cross-section observed by SEM, and the number N of silicon material particles within each selected unit area is calculated. N is 23, 10, 13, 27, and 28, respectively.

[0083] Example 11 The only differences from the second embodiment are as follows. (1) 1 kg of nanosilicon particles was weighed and dispersed in an aqueous solution, then 150 g of carboxymethyl cellulose was added and the mixture was stirred and dispersed for 1 hour. After that, 1 kg of polyacrylamide solution with a solid content of 0.5% was added, stirred for 10 minutes, and then allowed to stand for 5 minutes. After standing, the solution was centrifuged, and the centrifuged sample was freeze-dried at -20°C for 16 hours to obtain a precursor. The cross section of the negative electrode material particles produced in Example 11 observed by SEM was divided into areas A×B (where A×B=100 nm×100 nm=10 4 nm 2 ) into multiple unit areas. Five unit areas are randomly selected from the cross-section observed by SEM. Within each of the selected unit areas, 10 pairs of two adjacent silicon material particles are randomly selected. For each of the 10 pairs, the distance between the centers of the two silicon material particles on the cross-section is measured and converted to the actual distance d0 nm based on the scale. The range of d0 for all five unit areas is within 3 to 20. Furthermore, five unit areas are randomly selected from the cross-section observed by SEM, and the number N of silicon material particles within each of the selected unit areas is calculated. N is 30, 1, 3, 27, and 31, respectively.

[0084] Example 12 The only differences from the second embodiment are as follows. (1) 1 kg of nanosilicon particles was weighed and dispersed in an aqueous solution, then 200 g of carboxymethyl cellulose was added and the mixture was stirred and dispersed for 1 hour. 0.8 kg of a polyacrylamide solution with a solid content of 0.1% was then added, stirred for 10 minutes, and allowed to stand for 5 minutes. The solution was then centrifuged, and the centrifuged sample was freeze-dried at -20°C for 16 hours to obtain a precursor. The cross section of the negative electrode material particles produced in Example 12 observed by SEM was divided into areas A×B (where A×B=100 nm×100 nm=10 4 nm 2 ) into multiple unit areas. Five unit areas are randomly selected from the cross-section observed by SEM. Within each of the selected unit areas, 10 pairs of two adjacent silicon material particles are randomly selected. For each of the 10 pairs, the distance between the centers of the two silicon material particles on the cross-section is measured and converted to the actual distance d0 nm based on the scale. The range of d0 for all five unit areas is within 3 to 30. Furthermore, five unit areas are randomly selected from the cross-section observed by SEM, and the number N of silicon material particles within each selected unit area is calculated. N is 30, 10, 13, 30, and 28, respectively.

[0085] Example 13 The only differences from the first embodiment are as follows. (1) 1 kg of nanosilicon particles was weighed and dispersed in an aqueous solution, then 50 g of polyvinylpyrrolidone was added and the mixture was stirred and dispersed for 1 hour. 1 kg of polyacrylamide solution with a solid content of 0.5% was then added, stirred for 10 minutes, and allowed to stand for 5 minutes. The solution was then centrifuged, and the centrifuged sample was freeze-dried at -30°C for 24 hours to obtain a precursor.

[0086] The cross section of the negative electrode material particles produced in Example 13 observed by SEM was divided into areas A×B (where A×B=100 nm×100 nm=10 4 nm 2) into a plurality of unit areas. Five unit areas are randomly selected from the cross-sectional view observed by SEM. Within each of the selected unit areas, ten pairs of two adjacent silicon material particles are randomly selected. For each of the ten pairs, the distance between the centers of the two silicon material particles on the cross-sectional view is measured and converted to an actual distance d0 nm based on the scale. The d0 range for the two unit areas is all between 3 and 20, and the d0 for all three unit areas is less than 3. Furthermore, five unit areas are randomly selected from the cross-sectional view observed by SEM, and the number N of silicon material particles within each of the selected unit areas is calculated. N is 30, 30, 13, 27, and 28, respectively.

[0087] Example 14 The only differences from the second embodiment are as follows. (1) 1 kg of nanosilicon particles was weighed and dispersed in an aqueous solution, then 500 g of polyvinylpyrrolidone was added and the mixture was stirred and dispersed for 1 hour. 1 kg of polyacrylamide solution with a solid content of 0.1% was then added, stirred for 10 minutes, and allowed to stand for 5 minutes. The solution after standing was centrifuged, and the centrifuged sample was freeze-dried at -30°C for 24 hours to obtain a precursor.

[0088] The cross section of the negative electrode material particles produced in Example 14 observed by SEM was divided into areas A×B (where A×B=100 nm×100 nm=10 4 nm 2) into a plurality of unit areas. Five unit areas are randomly selected from the cross-sectional view observed by SEM. Within each of the selected unit areas, ten pairs of two adjacent silicon material particles are randomly selected. For each of the ten pairs, the distance between the centers of the two silicon material particles on the cross-sectional view is measured and converted to an actual distance d0 nm based on the scale. The d0 range for all three unit areas is between 3 and 20, and the d0 for all two unit areas is less than 3. Furthermore, five unit areas are randomly selected from the cross-sectional view observed by SEM, and the number N of silicon material particles within each of the selected unit areas is calculated. N is 30, 10, 13, 27, and 28, respectively.

[0089] Comparative Example 1 The only differences from the first embodiment are as follows. (1) 1 kg of nanosilicon particles was weighed and dispersed in an aqueous solution. After stirring for 1 hour, 1 kg of polyacrylamide solution with a solid content of 0.5% was added, stirred for 10 minutes, and then allowed to stand for 5 minutes. After standing, the solution was centrifuged, and the centrifuged sample was freeze-dried at -30°C for 24 hours to obtain a precursor. The cross section of the negative electrode material particles produced in Comparative Example 1 observed by SEM was divided into areas A×B (where A×B=100 nm×100 nm=10 4 nm 2 ) into a plurality of unit areas. Five unit areas are randomly selected from the cross-sectional view observed with the SEM. Within each of the selected unit areas, ten pairs of two adjacent silicon material particles are randomly selected. For each of the ten pairs, the distance between the centers of the two silicon material particles on the cross-sectional view is measured and converted to an actual distance d0 nm based on the scale. d0 for all five unit areas is less than 3. Furthermore, five unit areas are randomly selected from the cross-sectional view observed with the SEM, and the number N of silicon material particles within each of the selected unit areas is calculated. N is found to be 32, 33, 0, 1, and 28, respectively.

[0090] Comparative Example 2 The only differences from the second embodiment are as follows. (1) 1 kg of nanosilicon particles was weighed and dispersed in an aqueous solution, after which 500 g of polyvinylpyrrolidone was added, and the mixture was stirred and dispersed for 1 hour, then allowed to stand for 5 minutes. After standing, the solution was centrifuged, and the centrifuged sample was freeze-dried at -30°C for 24 hours to obtain a precursor. The cross section of the negative electrode material particles produced in Comparative Example 2 observed by SEM was divided into areas A×B (where A×B=100 nm×100 nm=10 4 nm 2 ) into a plurality of unit areas. Five unit areas are randomly selected from the cross-sectional view observed with the SEM. Within each of the selected unit areas, ten pairs of two adjacent silicon material particles are randomly selected. For each of the ten pairs, the distance between the centers of the two silicon material particles on the cross-sectional view is measured and converted to an actual distance d0 nm based on the scale. d0 for all five unit areas is less than 3. Furthermore, five unit areas are randomly selected from the cross-sectional view observed with the SEM, and the number N of silicon material particles within each of the selected unit areas is calculated. N is found to be 33, 35, 34, 0, and 0, respectively.

[0091] Measurement method: (1) Method for measuring the specific surface area of ​​negative electrode materials The specific surface area is measured using a Tristar 3000 specific surface area and pore size analyzer from Mike, USA. (2) Method for measuring particle size of negative electrode material Using the Malvern Laser Particle Sizer MS3000, the intensity distribution of scattered light in each direction of a particle is determined based on the principle that it depends on the particle size: large particles have a small scattering angle, and small particles have a large scattering angle. The particle size distribution is then obtained using the scattered light intensity distribution of laser diffraction. The laser particle sizer is used to measure D50, which has a symmetrical distribution similar to a normal distribution. In this volume-based distribution, the diameter at 50% of the cumulative volume is D50. By analogy, the diameter at 90% of the cumulative volume is D90, and the diameter at 10% of the cumulative volume is D10. (3) SEM measurement method for negative electrode materials The surface morphology and particle size of the samples were observed using a S4800 scanning electron microscope (Hitachi). The cross section of the negative electrode material particle observed by SEM is defined as the area A × B (where A × B = 10 4 nm 2 ) into a plurality of unit areas. One unit area is randomly selected from the cross-section observed by SEM, and a pair of two adjacent silicon material particles is randomly selected. The distance between the centers of the two silicon material particles in the pair is measured in the cross-section, and then converted to an actual distance d0 nm based on a scale, and the average value is calculated as d. Specifically, the cross-section of the negative electrode material particles observed by SEM is divided into a plurality of unit areas each having an area of ​​A × B (where A × B = 100 nm × 100 nm = 10 4 nm 2 ) into multiple unit areas. Five unit areas are randomly selected from the cross-sectional view observed with the SEM. Within each of the selected unit areas, 10 pairs of two adjacent silicon material particles are randomly selected. For each of the 10 pairs, the distance between the centers of the two silicon material particles in the cross-sectional view is measured, and then converted to the actual distance d0 nm based on the scale. The average value of 50 d0 is calculated as d. The cross section of the negative electrode material particle observed by SEM is defined as the area A × B (where A × B = 10 4 nm 2 ), and the number of silicon material particles in any one unit area is defined as N. Specifically, the cross section of the negative electrode material particle observed by SEM is divided into a plurality of unit areas each having an area of ​​A × B (where A × B = 100 nm × 100 nm = 10 4 nm 2 ), five unit areas are randomly selected, and the number N of silicon material particles in each of the selected unit areas is counted. (4) Method for measuring particle size of silicon materials The nano silicon material particles are observed using a field emission scanning electron microscope or a transmission electron microscope, and the particle diameters of 5 to 10 nano silicon material particles are directly measured on a scale, and the average particle diameter is used as the particle diameter of the final silicon material particles. (5) Measurement of the mass content of silicon in the negative electrode material After drying overnight, the sample was placed in a corundum crucible and placed in a muffle furnace (SA2-9-17TP, manufactured by Nanyang Xinyu, China) at 1200°C for 480 minutes to complete the carbon combustion and oxidation reaction of silicon or silicon monoxide to silicon dioxide. During this process, the weight of the crucible (m0), the weight of the sample (m1), and the total weight of the crucible and product (m2) after combustion were recorded, and the silicon content was calculated using the following formula: Si% = (m2 - m0) / m1 × 28.09 / 60.09 × 100%. (6) Measurement of the mass content of carbon element in the negative electrode material Using a German Bruck / Germany Idea infrared carbon and sulfur analyzer G4 ICARUS HF / CS-i, the sample was combusted at high temperature under oxygen-rich conditions, and the carbon contained in the sample was oxidized to carbon dioxide, which entered the infrared detector along with the carrier gas. The carbon content was calculated by quantitatively analyzing the changes in the infrared absorption wavelength intensity of the carbon dioxide signal. (7) Measurement of electrochemical properties The negative electrode materials prepared in the examples and comparative examples were dissolved in N-methylpyrrolidone in a mass ratio of 80:10:10, with carboxymethyl cellulose and styrene-butadiene rubber at 50% solids. The resulting mixture was coated on a copper foil current collector and vacuum dried to produce a negative electrode sheet. A lithium metal sheet was used as the positive electrode, and a 1 mol / L lithium hexafluorophosphate (LiPF6) / (ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC)) (v / v = 1:1:1) electrolyte was used. A Celgard 2400 separator and housing were assembled into CR2016 button cells using standard manufacturing processes. The 1C capacity and initial coulombic efficiency were tested at 1C, and the retention rate and electrode piece swelling after 50 charge / discharge cycles were tested at 0.1C. After 50 cycles, the thickness of the pole piece of the lithium ion battery is measured using a micrometer as H1, and the expansion rate after 50 cycles is (H1-H0) / H0×100%. After repeating 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) x 100%. (8) V C / V Si How to calculate the ratio V C = Mass of carbon element in anode material / Density of carbon material V Si = mass of silicon element in anode material / density of silicon material Here, the density of the silicon material is 2.5 g / cm 3 and the density of the carbon material is 1.8 g / cm 3 is.

[0092] Examples 1 to 14 of the present application are represented by S1 to S14, and Comparative Examples 1 and 2 are represented by D1 to D2. The results of performance measurements of the above samples are as follows:

[0093] [Table 1]

[0094] As can be seen from the data in Table 1, the negative electrode materials prepared in Examples 1 to 14 all had an average distance d between adjacent silicon material particles within any unit area that satisfied the range of 3≦d≦50. The silicon material in the negative electrode material can be dispersed within and between the carbon material, which can improve the conductivity of the negative electrode material, effectively alleviate the volume expansion effect of the silicon material during cycling, maintain the structural stability of the negative electrode material particles, and ultimately improve the cycling characteristics of the negative electrode material.

[0095] As can be seen from the measurement data of Example 11 and Example 2 in Table 1, the negative electrode material of Example 11 added a small amount of dispersant during the manufacturing process, which reduced the degree of dispersion of nano-silicon, and reduced the range of the distance between adjacent silicon material particles within any unit area. That is, the distribution of silicon material nano-primary particles was relatively concentrated, and the number of silicon material particles in at least one unit area was N>30, which slightly reduced the cycle and power consumption performance of the negative electrode material.

[0096] As can be seen from the measurement data of Example 12 and Example 2 in Table 1, the negative electrode material of Example 12 was manufactured using a small amount of flocculant, so that some of the dispersed nano-order silicon material may aggregate during the aggregation and precipitation process. In Example 12, the silicon material particles were more aggregated than the silicon material particles in Example 2, which slightly reduced the cycle and power consumption performance of the negative electrode material.

[0097] As can be seen from the measurement data of Example 1 and Comparative Example 1 in Table 1, the negative electrode material of Comparative Example 1 does not have a dispersant added during the manufacturing process, so the dispersibility of the nanosilicon material is poor. The average distance d between adjacent silicon material particles within any one unit area of ​​the negative electrode material does not satisfy 3≦d≦50. The number N of silicon material particles within at least one unit area is greater than 30, and there are no silicon material particles within at least one unit area. The carbon material cannot uniformly coat the nanosilicon material. The capacity and initial coulombic efficiency of the resulting negative electrode material are not significantly different from those of the Examples, but the cycle characteristics and multiplier performance of the negative electrode material are significantly reduced.

[0098] As can be seen from the measurement data of Example 1 and Comparative Example 2 in Table 1, the negative electrode material of Comparative Example 2 does not contain a flocculant during the manufacturing process, so the dispersant cannot uniformly coat the surface of the silicon material nanoparticles to form agglomerates. This results in serious aggregation between the silicon material nanoparticles. The average distance d between adjacent silicon material particles within any unit area of ​​the negative electrode material does not satisfy 3≦d≦50, the number N of silicon material particles within at least one unit area is greater than 30, and there are no silicon material particles within at least one unit area. As a result, the cycle characteristics and expansion performance of the negative electrode material after carbon coating are poor.

[0099] The present invention has been described in detail with reference to the above embodiments with respect to the process equipment and process flow, but the present invention is not limited to the above detailed process equipment and process flow, and the applicant declares that the present invention is not limited to the above detailed process equipment and process flow. As will be apparent to those skilled in the art, any modifications to the present invention, such as equivalent replacement of each raw material in the product of the present invention, addition of auxiliary components, and selection of specific methods, are all within the scope of the claims and disclosure of the present invention.

Claims

1. A negative electrode material comprising a carbon material and a silicon material, the silicon material is located within and / or between the carbon materials; The total volume of the carbon material is V C and the total volume of the silicon material is V Si Then, 0.9≦V C / V Si ≦2.3 is satisfied, The cross section of the particle of the negative electrode material observed by SEM is determined to have an area of ​​A × B (where A × B = 10 4 nm 2 ) and the average value of the distance between adjacent silicon material particles in any one unit area is d (nm), where d satisfies 3≦d≦50.

2. The distance between adjacent silicon material particles in a unit area is d 0 (nm), then d of at least one unit area 0 3≦d 0 2. The negative electrode material according to claim 1, wherein the negative electrode material satisfies a solubility of 50.

3. A negative electrode material comprising a carbon material and a silicon material, the silicon material is located within and / or between the carbon materials; The total volume of the carbon material is V C and the total volume of the silicon material is V Si Then, 0.9≦V C / V Si ≦2.3 is satisfied, The cross section of the negative electrode material particles observed by SEM is measured to have an area of ​​A×B (where A×B=10 4 nm 2 ) and the number of silicon material particles in each unit area is N, and N in each unit area satisfies 1≦N≦30.

4. 4. The negative electrode material according to claim 1, wherein the silicon material includes at least one of crystalline silicon, amorphous silicon, and a silicon alloy.

5. 5. The negative electrode material according to claim 1, wherein the silicon material has an average particle size of 1 nm to 50 nm.

6. 6. The negative electrode material according to claim 1, wherein the silicon material contains silicon particles.

7. 7. The negative electrode material of claim 6, further comprising a silicon oxide layer located on the surface of the silicon particles.

8. 8. The negative electrode material according to claim 7, wherein the mass content of the oxygen element in the silicon material is 1% to 18%, where the mass of the silicon material is 100%.

9. 9. The negative electrode material according to claim 1, wherein the carbon material comprises at least one of amorphous carbon, crystalline carbon, graphite fiber, carbon nanotube, carbon fiber, and mesocarbon microbeads.

10. 10. The negative electrode material according to claim 1, wherein the carbon material has pores, and at least a portion of the silicon material is located within the pores of the carbon material.

11. 11. The negative electrode material according to claim 1, wherein the median diameter is 5 μm to 15 μm.

12. Specific surface area is 1m 2 / g to 20m 2 The negative electrode material according to any one of claims 1 to 11, characterized in that it has a Cr content of 1 / g.

13. 13. The negative electrode material according to claim 1, wherein the mass content of carbon element is 30% to 75%.

14. 14. The negative electrode material according to claim 1, wherein the mass content of silicon element is 25% to 65%.

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

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