Negative electrode material and battery

Abstract

Provided are a negative electrode material and a battery. The negative electrode material comprises a carbon material and a silicon material, wherein the silicon material is located inside the carbon material and / or between the carbon materials. The total volume of the carbon material is VC, the total volume of the silicon material is VSi, and 0.9≤VC / VSi≤2.3. An SEM section of a negative electrode material particle is divided into a plurality of unit regions having an area of A×B, wherein A×B=104 nm2, and the average distance between adjacent silicon material particles in any unit region is d nm, where 3≤d≤50. The provided negative electrode material can improve the dispersion uniformity of the silicon material, and can effectively inhibit the volume expansion of the negative electrode material and improve the cycle performance of a battery.

Description

Anode materials and batteries

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on December 29, 2023, with application number 202311842097.6 and application name “Negative electrode material, preparation method thereof, and battery”, and claims priority to the Chinese patent application filed with the State Intellectual Property Office on March 27, 2024, with application number 202410365578.0 and application name “Negative electrode material, preparation method thereof, and battery”, all contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of negative electrode materials, and in particular, to negative electrode materials and batteries. Background Art

[0003] Lithium-ion batteries are widely used in electric vehicles and consumer electronics due to their high energy density, long cycle life, low environmental pollution, and lack of memory effect. The rapid development of electric vehicles in recent years has led to a growing demand for lithium-ion batteries with higher energy density, prompting researchers to search for battery materials with higher energy density and better cycle performance. Positive and negative electrode materials are the core of the battery and determine its operating efficiency. Currently, the commercialized negative electrode material is graphite, whose capacity is close to its theoretical upper limit, with limited potential for further improvement. Therefore, there is an urgent need to develop a new generation of high-energy-density negative electrode materials. Silicon-based negative electrode materials are widely considered to be the next generation of battery negative electrode materials, offering advantages such as high capacity, abundant sources, and relative safety.

[0004] Silicon anodes are widely considered the next generation of battery negative electrode materials, offering advantages such as high capacity, abundant resources, and relative safety. However, silicon anodes experience significant volume expansion during cycling, leading to material pulverization and fragmentation, and rapid cyclic degradation. Silicon-carbon composites are commonly used to suppress silicon's volume expansion, but current composites easily aggregate silicon materials, resulting in excessive localized expansion stress in the anode material, which compromises its cyclic stability. Summary of the Invention

[0005] The present application provides a negative electrode material and a battery, which can improve the dispersion uniformity of silicon materials, effectively inhibit the volume expansion of negative electrode materials, and improve battery cycle performance.

[0006] In a first aspect, the present application provides a negative electrode material, the negative electrode material comprising a carbon material and a silicon material, the silicon material being located inside the carbon material and / or between the carbon materials; the total volume of the carbon material being V C , the total volume of the silicon material is V Si , where 0.9≤V C / VSi ≤2.3;

[0007] The SEM section of the negative electrode material particles is divided into a plurality of unit areas with an area of ​​A×B, wherein A×B=10 4 nm 2 , the average spacing between adjacent silicon materials in any unit area is d nm, 3≤d≤50.

[0008] In a second aspect, the present application provides a negative electrode material, the negative electrode material comprising a carbon material and a silicon material, the silicon material being located inside the carbon material and / or between the carbon materials; the total volume of the carbon material being V C , the total volume of the silicon material is V Si , where 0.9≤V C / V Si ≤2.3;

[0009] The SEM section of the negative electrode material particles is divided into a plurality of unit areas with an area of ​​A×B, wherein A×B=10 4 nm 2 , the number of silicon materials in any unit area is N, 1≤N≤30.

[0010] In a third aspect, the present application provides a battery comprising the above-mentioned negative electrode material.

[0011] The technical solution of this application has at least the following beneficial effects:

[0012] The negative electrode material provided in the present application includes a carbon material and a silicon material, wherein the silicon material is located within and / or between the carbon materials; the average spacing between adjacent silicon materials within any unit area is d nm, 3≤d≤50, and the silicon material can be uniformly dispersed within and between the particles of the carbon material, thereby reducing the excessive local stress of the negative electrode material caused by the agglomeration of the silicon material and reducing the particle breakage or pulverization of the negative electrode material. In addition, controlling the volume ratio of the carbon material to the silicon material within the range of 0.9 to 2.3 can improve the conductivity of the negative electrode material, effectively alleviate the volume expansion effect of the silicon material during the cycle, maintain the structural stability of the negative electrode material particles, and thus improve the cycle performance of the negative electrode material.

[0013] The negative electrode material provided in the present application includes carbon material particles and silicon material, wherein the silicon material is located inside the carbon material and / or between the carbon materials; the number of silicon materials in any unit area is N, 1≤N≤30, and the silicon material can be evenly dispersed within the carbon material particles and between the carbon material particles, thereby reducing the excessive local stress of the negative electrode material caused by the agglomeration of the silicon material and reducing the particle breakage or pulverization of the negative electrode material. In addition, controlling the volume ratio of the carbon material to the silicon material within the range of 0.9 to 2.3 can improve the conductivity of the negative electrode material, effectively alleviate the volume expansion effect of the silicon material during the cycle, maintain the structural stability of the negative electrode material particles, and thus improve the cycle performance of the negative electrode material. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG1 is a process flow chart of the method for preparing the negative electrode material provided in this application.

[0015] FIG2 is an electron mirror image of the negative electrode material prepared in Example 1 of the present invention.

[0016] FIG3 is a schematic diagram of XRD (X-ray diffraction) of the negative electrode material prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0017] To better illustrate the present application and facilitate understanding of the technical solution of the present application, the present application is further described below. However, the following embodiments are merely simplified examples of the present application and do not represent or limit the scope of protection of the present application. The scope of protection of the present application shall be subject to the claims.

[0018] In a first aspect, the present application provides a negative electrode material, the negative electrode material includes a carbon material and a silicon material, the silicon material is located inside the carbon material and / or between the carbon materials; the total volume of the carbon material is V C , the total volume of silicon material is V Si , where 0.9≤V C / V Si ≤2.3;

[0019] The SEM section of the negative electrode material particles is divided into a plurality of unit areas with an area of ​​A×B, wherein A×B=10 4 nm 2 The average spacing between adjacent silicon material particles in any unit area is d nm, 3≤d≤50. Specifically, the spacing between adjacent silicon material particles is the distance between the centers of adjacent silicon material particles. Specifically, the SEM section of the negative electrode material particles is divided into multiple unit areas of area A×B, where A×B=100nm*100nm=10 4 nm 2Randomly select 5 unit areas in the SEM cross-section image, randomly measure the distance between the centers of 10 groups of two adjacent silicon material particles in each selected unit area, and then convert it into the actual spacing d0 nm according to the ruler. Calculate the average value of 50 d0 as d.

[0020] In some embodiments, the spacing between adjacent silicon material particles in at least one unit area is d0 nm, where 3≤d0≤50. It is understood that when the silicon material particles are uniformly distributed, the spacing d0 between any two adjacent silicon material particles is the same, and in this case, the average spacing d between adjacent silicon material particles is the spacing d0.

[0021] The negative electrode material provided in the present application includes a carbon material and a silicon material, wherein the silicon material is located within the carbon material and / or between the carbon materials; the average spacing between adjacent silicon material particles within any unit area is d nm, 3≤d≤50, and the silicon material particles can be uniformly dispersed within the carbon material and / or between the carbon materials, thereby reducing the excessive local stress of the negative electrode material caused by the agglomeration of the silicon material and reducing the particle breakage or pulverization of the negative electrode material. In addition, controlling the volume ratio of the carbon material to the silicon material within the range of 0.9 to 2.3 can improve the conductivity of the negative electrode material, effectively alleviate the volume expansion effect of the silicon material during the cycle, maintain the structural stability of the negative electrode material particles, and thus improve the cycle performance of the negative electrode material.

[0022] In some embodiments, the SEM section of the negative electrode material particles is divided into a plurality of unit regions with an area of ​​A×B, wherein A×B=10 4 nm 2 , the number of silicon material particles in any unit area is N, 1≤N≤30. Specifically, the SEM section of the negative electrode material particles is divided into multiple unit areas of area A×B, where A×B=100nm*100nm=10 4 nm 2 , randomly select 5 unit areas, and count the number N of silicon material particles in each selected unit area.

[0023] In the above scheme, the negative electrode material includes a carbon material and a silicon material, with the silicon material located within and / or between the carbon materials. The number of silicon material particles within any unit area is N, with 1≤N≤30. The silicon material can be evenly dispersed within and between the carbon materials, reducing excessive local stress in the negative electrode material caused by silicon material agglomeration and reducing particle breakage or pulverization of the negative electrode material. In addition, controlling the volume ratio of the carbon material to the silicon material within the range of 0.9 to 2.3 can improve the conductivity of the negative electrode material, effectively mitigate the volume expansion effect of the silicon material during cycling, maintain the structural stability of the negative electrode material particles, and thus improve the cycling performance of the negative electrode material.

[0024] In some embodiments, the silicon material includes at least one of crystalline silicon, amorphous silicon, and a silicon alloy.

[0025] The silicon alloy may be a silicon-lithium alloy, a silicon-magnesium alloy, or the like. 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 lithium insertion, which can reduce the collapse of the pore structure in the negative electrode material, inhibit the rapid attenuation of the specific capacity of the negative electrode material, and improve the lithium insertion cycle performance of the negative electrode material.

[0026] In some embodiments, the average particle size of the silicon material is 1 nm to 50 nm, and specifically can 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., without limitation herein. Silicon material of appropriate size can improve the uniformity of the distribution of the silicon material and the carbon matrix, reduce silicon material segregation, and improve the cycle performance of the negative electrode material. Preferably, the average particle size of the silicon material is 1 nm to 10 nm; more preferably, the average particle size of the silicon material is 1 nm to 5 nm.

[0027] In some embodiments, the mass percentage of silicon in the silicon material is ≥99%. The mass percentage of silicon in the silicon material within the above range is beneficial to improving the purity of the silicon material and reducing impurities.

[0028] In some embodiments, the silicon material includes silicon particles. The morphology of the silicon particles includes at least one of a dot-like shape, a sphere, an ellipsoidal shape, and a flake-like shape. The morphology of the silicon particles can be selected according to actual needs and is not limited here.

[0029] In some embodiments, 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 silicon oxide is SiO x , wherein 0.5≤x<2. Specifically, SiOx can be SiO 0.5 、SiO 0.7 、SiO 0.9、SiO、SiO 1.2 、SiO 1.5 、SiO 1.8 、SiO 1.9 etc., not limited here.

[0030] In some embodiments, the silicon material includes silicon particles and a silicon oxide layer located on the surface of the silicon particles. The mass percentage of oxygen in the silicon material is 1% to 18%, based on the mass of the silicon material being 100%. Specifically, the mass percentage of oxygen atoms in the silicon material can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, or 18%, etc., without limitation herein. Controlling the mass percentage of oxygen in the silicon material within the above range is conducive to forming a stable silicon oxide layer on the surface of the silicon particles, which can reduce direct contact between the silicon particles and the electrolyte, thereby reducing side reactions between the silicon material and the electrolyte, and improving the cycle stability of the negative electrode material. It can also ensure that the silicon material has stable activity and increase the specific capacity of the negative electrode material.

[0031] In some embodiments, the carbon material includes at least one of amorphous carbon, crystalline carbon, graphite fiber, carbon nanotube, carbon fiber, and mesocarbon microbeads. It is understood that the carbon material can mitigate the volume expansion effect of the negative electrode material to a certain extent while enhancing 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 Coulombic efficiency of the negative electrode material.

[0032] In some embodiments, the carbon material has pores, and at least a portion of the silicon material is located within the pores of the carbon material. It is understood that the pore structure of the carbon material can provide space for the volume expansion of the silicon material, effectively alleviating the volume expansion effect of the silicon material and improving the cycle performance of the negative electrode material.

[0033] In some embodiments, the median particle size of the negative electrode material is 5 μm to 15 μm; specifically, it can be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 12 μm, 13 μm, 14 μm, or 15 μm, etc., and of course, other values ​​within the above range are also possible and are not limited here. It can be understood that controlling the median particle size of the negative electrode material within the above range is beneficial to improving the cycle performance of the negative electrode material.

[0034] In some embodiments, the specific surface area of ​​the negative electrode material is 1 m 2 / g~20m 2 / g; specifically can be 1m 2 / g, 1.5m 2 / g, 2m 2 / g、3m2 / 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 here. Controlling the specific surface area of ​​the negative electrode material within the above range is beneficial to improving the initial efficiency and cycle performance of the lithium battery made from the negative electrode material.

[0035] In some embodiments, the mass percentage of carbon element in the negative electrode material is 30% to 75%; specifically, it can be 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70% or 75%, etc., which is not limited here.

[0036] In some embodiments, the mass percentage of silicon element in the negative electrode material is 25% to 65%; specifically, it can be 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60% or 65%, etc., which is not limited here.

[0037] In a second aspect, the present application provides a method for preparing a negative electrode material, as shown in FIG1 , the method comprises the following steps:

[0038] Step S10, preparing a mixed solution of silicon-containing material and dispersant, adding flocculation liquid to the mixed solution for mixing, and performing solid-liquid separation to obtain a precursor;

[0039] Step S20, mixing the precursor and the carbon source precursor and then preheating to obtain a composite;

[0040] Step S30 , carbonizing the composite to obtain a negative electrode material.

[0041] The preparation method of the negative electrode material provided by the present application is as follows: first, by dispersing the silicon material in a mixed liquid containing a dispersant, the silicon material can be fully dispersed; then, a flocculant is added to cause the silicon material and the dispersant to flocculate and precipitate simultaneously, and a composite is obtained after solid-liquid separation. Since the dispersant exists on the surface of the silicon material, the agglomeration of the silicon material can be reduced. Then, the precursor is mixed with a carbon source, and during a heat treatment process, the carbon source is able to replace the dispersant located on the surface of the silicon material by melting and infiltration, and the silicon material remains 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 can be dispersed inside and between the carbon materials, which can improve the conductivity of the negative electrode material. During the cycle, the volume expansion effect of the silicon material can be effectively alleviated, the structural stability of the negative electrode material particles can be maintained, and the cycle performance of the negative electrode material can be improved.

[0042] The technical solution of this application is described in detail below:

[0043] Step S10: preparing a mixed solution of silicon-containing material and dispersant, adding flocculation liquid to the mixed solution for mixing, and performing solid-liquid separation to obtain a precursor.

[0044] In some embodiments, the silicon material includes at least one of crystalline silicon, amorphous silicon, and a silicon alloy.

[0045] The silicon alloy may be a silicon-lithium alloy, a silicon-magnesium alloy, or the like. In some cases, the silicon material includes amorphous silicon and a silicon alloy. Preferably, the silicon material includes amorphous silicon, which expands isotropically during lithium insertion, thereby reducing pore structure collapse, inhibiting rapid capacity decay, and improving lithium insertion cycle performance.

[0046] In some embodiments, the average particle size of the silicon material is 1 nm to 50 nm, and can 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., which is not limited here.

[0047] In some embodiments, the dispersant includes at least one of stearic acid, sodium stearate, zinc stearate, magnesium stearate, calcium stearate, polyvinyl pyrrolidone, carboxymethyl cellulose, and polyacrylic acid.

[0048] In some embodiments, the mass ratio of the silicon material to the dispersant is 100:(20-100), and specifically can be 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 are also possible, and are not limited here. It can be understood that an appropriate dispersant can improve the dispersion of the silicon material in the mixed solution, reduce the agglomeration of the silicon material, and thereby improve the dispersion of the silicon material in the precursor.

[0049] In some embodiments, the mixed solution further comprises a solvent, and the solvent comprises at least one of water, methanol, ethanol, ethylene glycol, propanol, isopropanol, glycerol, n-butanol, isobutanol, pentanol, and ethyl acetate.

[0050] In some embodiments, the mixing process is performed under stirring.

[0051] In some embodiments, the mixing treatment time is 0.5 h to 3 h, specifically 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h or 3 h, etc. Of course, it can also be other values ​​within the above range, which is not limited here.

[0052] In some embodiments, the solid-liquid separation step includes filtering the mixed solution after adding the flocculation solution, and freeze-drying to obtain a precursor.

[0053] In some embodiments, the mass ratio of silicon material to flocculant is 1:(1-1.3), specifically 1:1, 1:1.05, 1:1.08, 1:1.1, 1:1.2, 1.25 or 1:1.3, etc. Of course, it can also be other values ​​within the above range, which is not limited here.

[0054] In some embodiments, the solid content of the flocculant is 0.1% to 0.5%, specifically 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45% or 0.5%, etc. Of course, it can also be other values ​​within the above range, which is not limited here.

[0055] In some embodiments, the flocculation liquid includes a flocculant, and the flocculant includes at least one of an inorganic flocculant and an organic flocculant.

[0056] In some embodiments, the inorganic flocculant includes at least one of aluminum sulfate, aluminum chloride, ferric sulfate, and ferric chloride.

[0057] In some embodiments, the organic flocculant includes at least one of polyaluminum chloride, polyaluminum sulfate, and polyacrylamide.

[0058] In the present application, the addition of flocculation liquid to the mixed solution can cause the dispersed nano-scale silicon material to precipitate in a flocculated state. However, since the surface of the silicon material contains a dispersant, the silicon materials in the flocculated product remain in an independently dispersed state.

[0059] In some embodiments, the freeze-drying temperature is -20°C to -30°C, specifically -20°C, -22°C, -24°C, -25°C, -27°C, -28°C or -30°C, etc., which is not limited here.

[0060] In some embodiments, the freeze-drying time is 10 hours to 24 hours, specifically 10 hours, 12 hours, 15 hours, 18 hours, 20 hours, 22 hours or 24 hours, etc., which are not limited here. The freeze-drying process can make the nano-scale silicon material uniformly dispersed in the dispersant.

[0061] Step S20 , mixing the precursor and the carbon source precursor and then performing a preheating treatment to obtain a composite.

[0062] In some embodiments, the carbon source precursor includes 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.

[0063] In some embodiments, the mass ratio of silicon material to 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. Of course, it can also be other values ​​within the above range, which is not limited here.

[0064] In some embodiments, the temperature of the preheat treatment is 150°C to 350°C, and the temperature can be 150°C, 200°C, 250°C, 280°C, 300°C, 320°C or 350°C, etc., which is not limited here.

[0065] In some embodiments, the preheating time is 2 hours to 15 hours, specifically 2 hours, 3 hours, 5 hours, 8 hours, 10 hours, 12 hours or 15 hours, etc., which is not limited here.

[0066] In some embodiments, the preheating treatment is performed under stirring.

[0067] By controlling the preheating temperature, preheating time and preheating state, the dispersant reaches the boiling point and volatilizes, and the carbon source precursor can be fully preheated, melted, softened and infiltrated to replace the dispersant on the surface of the silicon material.

[0068] Step S30 , carbonizing the composite to obtain a negative electrode material.

[0069] In some embodiments, the temperature of the carbonization treatment is 700°C to 1000°C, and the specific temperature can be 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 980°C or 1000°C, etc. Of course, it can also be other values ​​within the above range, which is not limited here.

[0070] In some embodiments, the carbonization treatment time is 1 h to 10 h, specifically 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 8 h, 9 h or 10 h, etc., which is not limited here.

[0071] In some embodiments, the heating rate of the carbonization treatment is 2°C / min to 10°C / min, specifically 2°C / min, 4°C / min, 5°C / min, 6°C / min, 8°C / min, 9°C / min or 10°C / min, etc., which is not limited here.

[0072] In some embodiments, the carbonization process is performed under a protective gas.

[0073] In some embodiments, the carbonization treatment is performed under a protective gas, and the protective gas includes at least one of nitrogen, helium, neon, argon, and krypton.

[0074] In some embodiments, the method further comprises: shaping, screening and grading the carbonized product to obtain a negative electrode material, wherein the shaping comprises at least one of crushing, grinding, ball milling and gas crushing.

[0075] In a third aspect, the present application provides a battery comprising the negative electrode material of the first aspect or the negative electrode material prepared by the negative electrode material preparation method of the second aspect. The battery may be a lithium-ion battery, a sodium-ion battery, or the like.

[0076] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0077] Example 1

[0078] The method for preparing the negative electrode material of this embodiment includes the following steps:

[0079] (1) Take 1 kg of nano-silicon particles and disperse them in an aqueous solution. Then add 500 g of polyvinyl pyrrolidone and stir and disperse for 1 hour. Then add 1 kg of polyacrylamide solution with a solid content of 0.5% and stir for 10 minutes. After that, let it stand for 5 minutes. Centrifuge the solution after standing. The centrifuged sample is placed at -30 ° C and freeze-dried for 24 hours to obtain a precursor.

[0080] (2) The precursor was placed in a VC mixing and heating machine, and asphalt was added according to a mass ratio of nano-silicon to asphalt of 100:120. The temperature of the equipment was raised to 300°C under stirring conditions. After mixing for 2 hours, the material was taken out to obtain a composite.

[0081] (3) The composite was placed in a box furnace, and after nitrogen was introduced, the temperature was raised to 800°C at a heating rate of 3°C / min. After being kept at this temperature for 3 h, the temperature was naturally lowered. The product was crushed with a mechanical crusher and passed through a 325-mesh sieve to obtain the negative electrode material.

[0082] Figure 2 is an electron mirror image of the negative electrode material prepared in Example 1 of the present invention. Figure 3 is an XRD diagram of the negative electrode material prepared in Example 1 of the present invention. As shown in Figures 2 and 3, the negative electrode material prepared in this embodiment of the present application includes a carbon material and a silicon material, and the silicon material is located inside and between the carbon materials. The SEM section of the negative electrode material particles prepared in Example 1 is divided into multiple unit areas with an area of ​​A×B, where A×B=100nm*100nm=10 4 nm 2Five unit areas were randomly selected from the SEM cross-section image. Within each of the selected unit areas, the distances between the centers of 10 adjacent silicon material particles on the cross-section image were randomly measured. This distance was then converted to the actual spacing d0 nm using a ruler. The range of d0 for the five areas was 5 to 50. Five unit areas were randomly selected, and the number N of silicon material particles in each of the selected unit areas was counted, which were 20, 10, 13, 18, and 29, respectively.

[0083] Example 2

[0084] (1) Take 1 kg of nano-silicon particles and disperse them in an aqueous solution. Then add 500 g of polyvinyl pyrrolidone and stir and disperse for 1 hour. Then add 1 kg of polyacrylamide solution with a solid content of 0.5% and stir for 10 minutes. After that, let it stand for 5 minutes. Centrifuge the solution after standing. The centrifuged sample is placed at -30 ° C and freeze-dried for 24 hours to obtain a precursor.

[0085] (2) The precursor was placed in a VC mixing and heating machine, and asphalt was added according to a mass ratio of nano-silicon to asphalt of 100:140. The temperature of the equipment was raised to 300°C under stirring conditions. After mixing for 2 hours, the material was taken out to obtain a composite.

[0086] (3) The composite was placed in a box furnace, and after nitrogen was introduced, the temperature was raised to 800°C at a heating rate of 3°C / min. After being kept at this temperature for 3 h, the temperature was naturally lowered. The product was crushed with a mechanical crusher and passed through a 325-mesh sieve to obtain the negative electrode material.

[0087] The negative electrode material prepared in the embodiment of the present application includes carbon material and silicon material, and the silicon material is located inside and between the carbon material. The SEM section of the negative electrode material particles prepared in Example 2 is divided into multiple unit areas with an area of ​​A×B, where A×B=100nm*100nm=10 4 nm 2 Five unit areas were randomly selected from the SEM cross-section image. Within each of the selected unit areas, the distances between the centers of 10 adjacent silicon particles on the cross-section image were randomly measured. This distance was then converted to the actual spacing d0 nm using a ruler. The range of d0 for the five areas was 5 to 50 nm. Five unit areas were randomly selected, and the number N of silicon particles in each of the selected unit areas was counted, which were 12, 15, 23, 28, and 28, respectively.

[0088] Example 3

[0089] The difference from Example 1 is that:

[0090] (2) The precursor was placed in a VC mixing and heating machine, and asphalt was added according to a mass ratio of nano-silicon to asphalt of 100:180. The temperature of the equipment was raised to 300°C under stirring conditions. After mixing for 2 hours, the material was taken out to obtain a composite.

[0091] The negative electrode material prepared in the embodiment of the present application includes a carbon material and a silicon material, and the silicon material is located inside and between the carbon materials.

[0092] The negative electrode material prepared in the embodiment of the present application includes an active material, the active material includes a carbon matrix and a silicon material, the carbon matrix has pores, and at least part of the silicon material is distributed in the pores of the carbon matrix. The SEM section of the negative electrode material particles prepared in Example 3 is divided into multiple unit areas with an area of ​​A×B, where A×B=100nm*100nm=10 4 nm 2 Five unit areas were randomly selected from the SEM cross-section image. Within each of the selected unit areas, the distances between the centers of 10 adjacent silicon particles were randomly measured on the cross-section image. This distance was then converted to the actual spacing d0 nm using a ruler. The range of d0 for the five areas was 5 to 50 nm. Five unit areas were randomly selected, and the number of silicon particles N in each of the selected unit areas was counted, which were 12, 13, 21, 27, and 28, respectively.

[0093] Example 4

[0094] The difference from Example 1 is that:

[0095] (2) The precursor was placed in a VC mixing and heating machine, and asphalt was added according to a mass ratio of nano-silicon to asphalt of 100:100. The temperature of the equipment was raised to 300°C under stirring conditions. After mixing for 2 hours, the material was taken out to obtain a composite. The SEM section of the negative electrode material particles prepared in Example 4 was divided into multiple unit areas with an area of ​​A×B, where A×B=100nm*100nm=10 4 nm 2 Five unit areas were randomly selected from the SEM cross-section image. Within each of the selected unit areas, the distances between the centers of 10 adjacent silicon particles were randomly measured on the cross-section image. This distance was then converted to the actual spacing d0 nm using a ruler. The range of d0 for the five areas was 5 to 50 nm. Five unit areas were randomly selected, and the number N of silicon particles in each of the selected unit areas was counted, which were 21, 23, 11, 27, and 28, respectively.

[0096] Example 5

[0097] The difference from Example 1 is that:

[0098] (2) The precursor was placed in a VC mixing and heating machine, and asphalt was added according to a mass ratio of nano-silicon to asphalt of 100:250. The temperature of the equipment was raised to 300°C under stirring conditions. After mixing for 2 hours, the material was taken out to obtain a composite. The SEM section of the negative electrode material particles prepared in Example 5 was divided into multiple unit areas with an area of ​​A×B, where A×B=100nm*100nm=10 4 nm 2 Five unit areas were randomly selected from the SEM cross-section image. Within each of the selected unit areas, the distances between the centers of 10 adjacent silicon particles were randomly measured on the cross-section image. This distance was then converted to the actual spacing d0 nm using a ruler. The range of d0 for the five areas was 5 to 50 nm. Five unit areas were randomly selected, and the number N of silicon particles in each of the selected unit areas was counted, which were 20, 20, 13, 17, and 18, respectively.

[0099] Example 6

[0100] The difference from Example 2 is that:

[0101] (1) 1 kg of nano-silicon particles were dispersed in an ethylene glycol solution, and then 200 g of polyvinyl pyrrolidone was added and stirred for 1 hour. Then, 1 kg of a polyacrylamide solution with a solid content of 0.5% was added, stirred for 10 minutes, and then allowed to stand for 5 minutes. The solution after standing was centrifuged, and the centrifuged sample was freeze-dried at -20°C for 16 hours to obtain a precursor. The SEM section of the negative electrode material particles prepared in Example 6 was divided into multiple unit areas with an area of ​​A×B, where A×B=100 nm*100 nm=10 4 nm 2 Five unit areas were randomly selected from the SEM cross-section image. Within each of the selected unit areas, the distances between the centers of 10 adjacent silicon particles were randomly measured on the cross-section image. This distance was then converted to the actual spacing d0 nm using a ruler. The range of d0 for the five areas was 5 to 50 nm. Five unit areas were randomly selected, and the number N of silicon particles in each of the selected unit areas was counted, which were 30, 10, 13, 27, and 28, respectively.

[0102] Example 7

[0103] The difference from Example 2 is that:

[0104] (1) Take 1 kg of nano-silicon particles and disperse them in an aqueous solution. Then add 800 g of polyvinyl pyrrolidone and stir and disperse for 1 hour. Then add 1 kg of polyacrylamide solution with a solid content of 0.5% and stir for 10 minutes. Then let it stand for 5 minutes. Centrifuge the solution after standing. The centrifuged sample is placed at -20 ° C and freeze-dried for 24 hours to obtain a precursor. The SEM section of the negative electrode material particles prepared in Example 7 is divided into multiple unit areas with an area of ​​A×B, where A×B=100 nm*100 nm=10 4 nm 2 Five unit areas were randomly selected from the SEM cross-section image. Within each of the selected unit areas, the distances between the centers of 10 adjacent silicon material particles on the cross-section image were randomly measured. This distance was then converted to the actual spacing d0 nm using a ruler. The range of d0 for the five areas was 5 to 50. Five unit areas were randomly selected, and the number N of silicon material particles in each of the selected unit areas was counted, which were 10, 20, 23, 17, and 26, respectively.

[0105] Example 8

[0106] The difference from Example 2 is that:

[0107] (1) Take 1 kg of nano-silicon particles and disperse them in an aqueous solution. Then add 350 g of polyacrylic acid and stir and disperse for 1 hour. Then add 1 kg of polyacrylamide solution with a solid content of 0.5% and stir for 10 minutes. Then let it stand for 5 minutes. Centrifuge the solution after standing. The centrifuged sample is placed at -20 ° C and freeze-dried for 20 hours to obtain a precursor. The SEM section of the negative electrode material particles prepared in Example 8 is divided into multiple unit areas with an area of ​​A×B, where A×B=100 nm*100 nm=10 4 nm 2 Five unit areas were randomly selected from the SEM cross-section image. Within each of the selected unit areas, the distances between the centers of 10 adjacent silicon particles on the cross-section image were randomly measured. This distance was then converted to the actual spacing d0 nm using a ruler. The range of d0 for the five areas was 5 to 50 nm. Five unit areas were randomly selected, and the number N of silicon particles in each of the selected unit areas was counted, which were 25, 20, 23, 17, and 18, respectively.

[0108] Example 9

[0109] The difference from Example 2 is that:

[0110] (1) Take 1 kg of nano-silicon particles and disperse them in an aqueous solution. Then add 600 g of sodium stearate and stir and disperse for 1 hour. Then add 1 kg of polyaluminum sulfate solution with a solid content of 0.2% and stir for 10 minutes. Then let it stand for 5 minutes. Centrifuge the solution after standing. The centrifuged sample is placed at 20 ° C and freeze-dried for 16 hours to obtain a precursor. The SEM section of the negative electrode material particles prepared in Example 9 is divided into multiple unit areas with an area of ​​A×B, where A×B=100 nm*100 nm=10 4 nm 2 Five unit areas were randomly selected from the SEM cross-section image. Within each of the selected unit areas, the distances between the centers of 10 adjacent silicon material particles on the cross-section image were randomly measured. This distance was then converted to the actual spacing d0 nm using a ruler. The range of d0 for the five areas was 5 to 50. Five unit areas were randomly selected, and the number N of silicon material particles in each of the selected unit areas was counted, which were 20, 20, 23, 25, and 8, respectively.

[0111] Example 10

[0112] The difference from Example 2 is that:

[0113] (1) Take 1 kg of nano-silicon particles and disperse them in an aqueous solution. Then add 200 g of carboxymethyl cellulose and stir and disperse for 1 hour. Then add 1 kg of ferric chloride solution with a solid content of 0.2% and stir for 10 minutes. Then let it stand for 5 minutes. Centrifuge the solution after standing. The centrifuged sample is placed at -30 ° C and freeze-dried for 24 hours to obtain a precursor. The SEM section of the negative electrode material particles prepared in Example 10 is divided into multiple unit areas with an area of ​​A×B, where A×B=100 nm*100 nm=10 4 nm 2 Five unit areas were randomly selected from the SEM cross-section image. Within each of the selected unit areas, the distances between the centers of 10 adjacent silicon particles were randomly measured on the cross-section image. This distance was then converted to the actual spacing d0 nm using a ruler. The range of d0 for the five areas was 3 to 50 nm. Five unit areas were randomly selected, and the number N of silicon particles in each of the selected unit areas was counted, which were 23, 10, 13, 27, and 28, respectively.

[0114] Example 11

[0115] The difference from Example 2 is that:

[0116] (1) Take 1 kg of nano-silicon particles and disperse them in an aqueous solution. Then add 150 g of carboxymethyl cellulose and stir and disperse for 1 hour. Then add 1 kg of polyacrylamide solution with a solid content of 0.5% and stir for 10 minutes. After that, let it stand for 5 minutes. Centrifuge the solution after standing. The centrifuged sample is placed at -20 ° C and freeze-dried for 16 hours to obtain a precursor. The SEM section of the negative electrode material particles prepared in Example 11 is divided into multiple unit areas with an area of ​​A×B, where A×B=100 nm*100 nm=10 4 nm 2 Five unit areas were randomly selected from the SEM cross-section image. Within each of the selected unit areas, the distances between the centers of 10 adjacent silicon particles on the cross-section image were randomly measured. This distance was then converted to the actual spacing d0 nm using a ruler. The range of d0 for the five areas was 3 to 20 nm. Five unit areas were randomly selected, and the number N of silicon particles in each of the selected unit areas was counted, which were 30, 1, 3, 27, and 31, respectively.

[0117] Example 12

[0118] The difference from Example 2 is that:

[0119] (1) 1 kg of nano-silicon particles were dispersed in an aqueous solution, and then 200 g of carboxymethyl cellulose was added and stirred for 1 hour. Then, 0.8 kg of a polyacrylamide solution with a solid content of 0.1% was added, stirred for 10 minutes, and then allowed to stand for 5 minutes. The solution after standing was centrifuged, and the centrifuged sample was freeze-dried at -20°C for 16 hours to obtain a precursor. The SEM section of the negative electrode material particles prepared in Example 12 was divided into multiple unit areas with an area of ​​A×B, where A×B=100 nm*100 nm=10 4 nm 2 Five unit areas were randomly selected from the SEM cross-section image. Within each of the selected unit areas, the distances between the centers of 10 adjacent silicon material particles on the cross-section image were randomly measured. This distance was then converted to the actual spacing d0 nm using a ruler. The range of d0 for the five areas was 3 to 30. Five unit areas were randomly selected, and the number N of silicon material particles in each of the selected unit areas was counted, which were 30, 10, 13, 30, and 28, respectively.

[0120] Example 13

[0121] The difference from Example 1 is that:

[0122] (1) Take 1 kg of nano-silicon particles and disperse them in an aqueous solution. Then add 50 g of polyvinyl pyrrolidone and stir and disperse for 1 hour. Then add 1 kg of polyacrylamide solution with a solid content of 0.5% and stir for 10 minutes. After that, let it stand for 5 minutes. Centrifuge the solution after standing. The centrifuged sample is placed at -30 ° C for freeze drying for 24 hours to obtain a precursor.

[0123] The SEM section of the negative electrode material particles prepared in Example 13 was divided into a plurality of unit areas with an area of ​​A×B, where A×B=100nm*100nm=10 4 nm 2 Five unit areas were randomly selected from the SEM cross-section image. Within each selected unit area, the distances between the centers of 10 adjacent silicon material particles on the cross-section image were randomly measured. This distance was then converted to the actual spacing d0 nm using a ruler. The d0 values ​​for two areas ranged from 3 to 20, and for three areas, the d0 values ​​were all less than 3. Five unit areas were randomly selected, and the number N of silicon material particles in each selected unit area was counted: 30, 30, 13, 27, and 28, respectively.

[0124] Example 14

[0125] The difference from Example 2 is that:

[0126] (1) Take 1 kg of nano-silicon particles and disperse them in an aqueous solution. Then add 500 g of polyvinyl pyrrolidone and stir and disperse for 1 hour. Then add 1 kg of polyacrylamide solution with a solid content of 0.1% and stir for 10 minutes. After that, let it stand for 5 minutes. Centrifuge the solution after standing. The centrifuged sample is placed at -30 ° C and freeze-dried for 24 hours to obtain a precursor.

[0127] The SEM section of the negative electrode material particles prepared in Example 14 was divided into a plurality of unit areas with an area of ​​A×B, where A×B=100nm*100nm=10 4 nm 2 Five unit areas were randomly selected from the SEM cross-section image. The distances between the centers of 10 adjacent silicon particles were randomly measured within each unit area. The distances were then converted to the actual spacing d0 nm using a ruler. The d0 values ​​for the three areas ranged from 3 to 20, and the d0 values ​​for the two areas were less than 3. Five unit areas were randomly selected, and the number N of silicon particles within each area was counted, which were 30, 10, 13, 27, and 28, respectively.

[0128] Comparative Example 1

[0129] The difference from Example 1 is that:

[0130] (1) Take 1 kg of nano-silicon particles and disperse them in an aqueous solution. Stir and disperse for 1 hour. Then add 1 kg of polyacrylamide solution with a solid content of 0.5% and stir for 10 minutes. Then let it stand for 5 minutes. Centrifuge the solution after standing. Place the centrifuged sample at -30°C for freeze drying for 24 hours to obtain a precursor. The SEM section of the negative electrode material particles prepared in Comparative Example 1 is divided into multiple unit areas with an area of ​​A×B, where A×B=100nm*100nm=10 4 nm 2 Five unit areas were randomly selected from the SEM cross-section image. The distances between the centers of 10 adjacent silicon material particles in each selected unit area were randomly measured on the cross-section image. The distances were then converted to the actual spacing d0 nm using a ruler. The d0 values ​​for all five areas were less than 3. Five unit areas were randomly selected, and the number N of silicon material particles in each selected unit area was counted, which were 32, 33, 0, 1, and 28, respectively.

[0131] Comparative Example 2

[0132] The difference from Example 2 is that:

[0133] (1) 1 kg of nano-silicon particles were dispersed in an aqueous solution, and then 500 g of polyvinyl pyrrolidone was added. The mixture was stirred and dispersed for 1 hour and then 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. The SEM section of the negative electrode material particles prepared in Comparative Example 2 was divided into multiple unit areas with an area of ​​A×B, where A×B=100 nm*100 nm=10 4 nm 2 Five unit areas were randomly selected from the SEM cross-section image. The distances between the centers of 10 adjacent silicon material particles in each selected unit area were randomly measured on the cross-section image. The distances were then converted to the actual spacing d0 nm using a ruler. The d0 values ​​for all five areas were less than 3. Five unit areas were randomly selected, and the number N of silicon material particles in each selected unit area was counted, which were 33, 35, 34, 0, and 0, respectively.

[0134] Test method:

[0135] (1) Test method for specific surface area of ​​negative electrode material:

[0136] The specific surface area was measured using a Micromeritics TriStar 3000 surface area and pore size analyzer.

[0137] (2) Testing method for negative electrode material particle size:

[0138] Using a Malvern MS3000 laser particle size analyzer, we determine the particle size distribution using the scattered light intensity distribution from laser diffraction, based on the principle that the intensity distribution of scattered light generated by particles in all directions depends on their size. Large particles have smaller scattering angles, while small particles have larger scattering angles. The D50 value, measured using the laser particle size analyzer, exhibits a symmetrical, normal-like distribution. In this volume-based distribution, the cumulative 50% diameter is the D50, and similarly, the cumulative 90% diameter is the D90, and the cumulative 10% diameter is the D10.

[0139] (3) SEM testing method of negative electrode materials:

[0140] The surface morphology and particle size of the samples were observed using a Hitachi S4800 scanning electron microscope.

[0141] The SEM section of the negative electrode material particles is divided into multiple unit areas with an area of ​​A×B, where A×B=10 4 nm 2 In the SEM cross-section, randomly select a unit area and measure the distance between the centers of any two adjacent silicon material particles. Then, convert it to the actual spacing d0 nm according to the ruler, and calculate the average value as d. Specifically, the SEM cross-section of the negative electrode material particles is divided into multiple unit areas of area A×B, where A×B=100nm*100nm=10 4 nm 2 Randomly select 5 unit areas in the SEM cross-section image, randomly measure the distance between the centers of 10 adjacent silicon material particles in each selected unit area, and then convert it into the actual spacing d0 nm according to the ruler. Calculate the average value of 100 d0 as d.

[0142] The SEM section of the negative electrode material particles is divided into multiple unit areas with an area of ​​A×B, where A×B=10 4 nm 2 , the number of silicon material particles in any unit area is N. Specifically, the SEM section of the negative electrode material particles is divided into multiple unit areas of area A×B, where A×B=100nm*100nm=10 4 nm 2 , randomly select 3 unit areas, and count the number N of silicon material particles in each selected unit area.

[0143] (4) Testing method of silicon material particle size:

[0144] The nano-silicon material particles are observed by a field emission scanning electron microscope or a transmission electron microscope, and the particle sizes of 5-10 nano-silicon material particles are directly measured by a scale, and the average value of the particle sizes is taken as the final particle size of the nano-silicon material particles.

[0145] (5) Test of the mass percentage of silicon in the negative electrode material:

[0146] After drying the sample overnight, place it in a corundum crucible, and then place the crucible in a muffle furnace (Nanyang Xinyu SA2-9-17TP) at 1200°C for 480 minutes to complete the combustion of carbon and the oxidation reaction of silicon or silicon oxide to silicon dioxide. During the process, the crucible weight m0, sample weight m1, and total weight of the crucible and product after calcination m2 were recorded, and the silicon content was calculated according to the following formula: Si% = (m2-m0) / m1×28.09 / 60.09×100%.

[0147] (6) Test of the mass percentage of carbon element in negative electrode material:

[0148] Using the German Bruker / German Airt infrared carbon and sulfur analyzer G4 ICARUS HF / CS-i, the sample is burned in a high-temperature, oxygen-rich state. The carbon element it contains is oxidized to carbon dioxide and enters the infrared detector with the carrier gas. The carbon content is calculated by quantitatively analyzing the changes in the infrared absorption wavelength intensity of the carbon dioxide signal.

[0149] (7) Electrochemical performance test

[0150] The negative electrode materials prepared in the examples and comparative examples were dissolved in N-methylpyrrolidone at a mass ratio of 80:10:10, carboxymethyl cellulose, and styrene-butadiene rubber, respectively, to control the solid content to 50%. The materials were coated on a copper foil current collector and vacuum dried to produce a negative electrode plate. A metal lithium plate was used as the positive electrode, and a 1 mol / L lithium hexafluorophosphate LiPF6 / (ethylene carbonate EC+dimethyl carbonate DMC+ethyl methyl carbonate EMC) (v / v=1:1:1) electrolyte, Celgard 2400 separator, and shell were assembled using conventional production processes to assemble a CR2016 button cell. The electrochemical performance test current density 1C was equal to 1000 mA h / g. Under 0.1C conditions, the 0.1C capacity and first efficiency were tested, under 1C conditions, the 1C capacity and first efficiency were tested, and under 0.1C conditions, the 50 charge and discharge cycle retention rate and plate expansion were tested.

[0151] Repeat the cycle for 50 times, and use a micrometer to measure the thickness of the lithium-ion battery electrode, which is H1. The expansion rate after 50 cycles = (H1-H0) / H0×100%.

[0152] Repeat the cycle for 50 cycles and record the discharge capacity as the remaining capacity of the lithium-ion battery; capacity retention rate = remaining capacity / initial capacity*100%.

[0153] (8)V C / V Si The ratio calculation method is:

[0154] V C = mass of carbon element in negative electrode material / density of carbon material; V Si = mass of silicon in the negative electrode material / density of silicon material; the density of silicon material is 2.5g / cm 3 The density of carbon material is 1.8g / cm 3 .

[0155] Examples 1 to 12 of the present application are represented by S1 to S12, and Comparative Examples 1 to 2 are represented by D1 to D2. The performance test results of the above samples are as follows:

[0156] Table 1. Performance parameters of negative electrode materials and batteries prepared in various examples and comparative examples.

[0157] According to the data in Table 1, the average spacing d between adjacent silicon material particles within any unit area of ​​the negative electrode materials prepared in Examples 1 to 14 satisfies 3≤d≤50. The silicon material in the negative electrode material can be dispersed within and between the carbon materials, which can improve the conductivity of the negative electrode material. During the cycle, it can effectively alleviate the volume expansion effect of the silicon material, maintain the structural stability of the negative electrode material particles, and thus improve the cycle performance of the negative electrode material.

[0158] According to the test data of Example 11 and Example 2 in Table 1, it can be seen that the amount of dispersant added during the preparation process of the negative electrode material of Example 11 is relatively small, the dispersion degree of nano-silicon decreases, and the spacing range between adjacent silicon material particles in any unit area is reduced, that is, the distribution of silicon material nano primary particles is relatively concentrated, and the number N of silicon material particles in at least one unit area is greater than 30, resulting in a slight decrease in the cycle and rate performance of the negative electrode material.

[0159] According to the test data of Example 12 and Example 2 in Table 1, it can be seen that the amount of flocculant added during the preparation process of the negative electrode material of Example 12 is relatively small, and the dispersed nano-scale silicon material may be partially agglomerated during the flocculation and precipitation process. The silicon material particles in Example 12 are more agglomerated than the silicon material particles in Example 2, resulting in a slight decrease in the cycle and rate performance of the negative electrode material.

[0160] According to the test data of Example 1 and Comparative Example 1 in Table 1, no dispersant was added to the negative electrode material of Comparative Example 1 during the preparation process, the dispersibility of the nano-silicon material was poor, the average spacing d between adjacent silicon material particles in any unit area in the negative electrode material did not satisfy 3≤d≤50, the number N of silicon material particles in at least one unit area was greater than 30, and there were no silicon material particles in at least one unit area. The carbon material could not uniformly coat the nano-silicon material. Although the capacity and first effect of the obtained negative electrode material were not much different from those of the embodiment, the cycle and rate performance of the negative electrode material were significantly reduced.

[0161] According to the test data of Example 1 and Comparative Example 2 in Table 1, no flocculant was added during the preparation process of the negative electrode material of Comparative Example 2, and the dispersant could not evenly coat and aggregate on the surface of the silicon material nanoparticles, resulting in serious agglomeration between the silicon material nanoparticles. The average spacing d between adjacent silicon material particles in any unit area in the negative electrode material does not satisfy 3≤d≤50, the number N of silicon material particles in at least one unit area is greater than 30, and there are no silicon material particles in at least one unit area. The cycle performance and expansion performance of the carbon-coated negative electrode material are poor.

[0162] The applicant declares that the present invention uses the above-described embodiments to illustrate the detailed process equipment and process flow of the present invention. However, the present invention is not limited to the above-described detailed process equipment and process flow, and does not necessarily rely on the above-described detailed process equipment and process flow in order to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for the raw materials of the present invention's products, additions of auxiliary ingredients, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A negative electrode material, characterized in that, The negative electrode material includes a carbon material and a silicon material, and the silicon material is located inside and / or between the carbon materials; the total volume of the carbon materials is V C , the total volume of the silicon material is V Si , where 0.9 ≤ V C / V Si ≤ 2.3; Divide the SEM cross-section of the negative electrode material particles into multiple unit areas with an area of A×B, where A×B = 10 4 nm 2 , and the average distance between adjacent silicon material particles in any unit area is d nm, where 3 ≤ d ≤ 50.

2. The negative electrode material according to claim 1, characterized in that, The spacing between adjacent silicon material particles within at least one unit region is d0 nm, where 3 ≤ d0 ≤ 50.

3. A negative electrode material, characterized in that, The negative electrode material includes a carbon material and a silicon material, and the silicon material is located inside 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 , where 0.9 ≤ V C / V Si ≤ 2.3; Divide the SEM cross-section of the negative electrode material particles into multiple unit areas with an area of A×B, where A×B = 10 4 nm 2 , and the number of silicon material particles in any one unit area is N, where 1 ≤ N ≤ 30.

4. The negative electrode material according to any one of claims 1 to 3, characterized in that, The silicon material includes at least one of crystalline silicon, amorphous silicon, and silicon alloy.

5. The negative electrode material according to any one of claims 1 to 4, characterized in that, The average particle size of the silicon material is 1 nm to 50 nm.

6. The negative electrode material according to any one of claims 1 to 5, characterized in that, The silicon material includes silicon particles.

7. The negative electrode material according to claim 6, wherein, The negative electrode material further includes a silicon oxide layer on the surface of the silicon particles.

8. The negative electrode material according to claim 7, characterized in that, Based on the mass of the silicon material being 100%, the mass percentage of oxygen element in the silicon material is 1% to 18%.

9. The negative electrode material according to any one of claims 1 to 8, characterized in that, The carbon material includes at least one of amorphous carbon, crystalline carbon, graphite fiber, carbon nanotube, carbon fiber, and mesophase carbon microsphere.

10. The negative electrode material according to any one of claims 1 to 9, characterized in that, The carbon material has pores, and at least part of the silicon material is located within the pores of the carbon material.

11. The negative electrode material according to any one of claims 1 to 10, characterized in that, The median particle size of the negative electrode material is 5 μm to 15 μm.

12. The negative electrode material according to any one of claims 1 to 11, characterized in that, The specific surface area of the negative electrode material is 1 m 2 / g to 20 m 2 / g.

13. The negative electrode material according to any one of claims 1 to 12, characterized in that, The mass percentage of carbon element in the negative electrode material is 30% to 75%.

14. The negative electrode material according to any one of claims 1 to 13, characterized in that, The mass percentage of silicon element in the negative electrode material is 25% to 65%.

15. A battery, characterized in that, The battery includes the negative electrode material according to any one of claims 1 to 14.

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