Silicon-based negative electrode material, preparation method and application thereof, and battery

Abstract

The application discloses a silicon-based negative electrode material and a preparation method and application thereof, and a battery. The silicon-based negative electrode material is of a core-shell structure, the inner core of which comprises silicon grains, silicon oxide and metal silicate; the shell layer is a carbon coating layer; the metal silicate comprises first metal element silicate and second metal element silicate; the first metal element silicate and the second metal element silicate are uniformly distributed in the inner core; and in the XRD pattern of the silicon-based negative electrode material, a characteristic diffraction peak with an intensity of 1000-2000 appears between 25 degrees and 30 degrees. The silicon-based negative electrode material prepared by the application has uniform distribution of silicon, silicon oxide and metal silicate, and has high electrical conductivity, a first discharge capacity, a first coulomb efficiency and excellent cycle performance when applied to a lithium ion battery.

Description

TECHNICAL FIELD

[0001] The present application relates to a silicon-based negative electrode material and a preparation method and application thereof, and a battery. BACKGROUND

[0002] With the development of electric vehicles, portable power tools and household appliances, there is an increasing demand for lithium ion batteries with high initial coulombic efficiency, high energy density and high cycle performance. The theoretical specific capacity of traditional lithium ion battery negative electrode material graphite is only 372 mAh / g, which is difficult to meet the demand for high energy density of negative electrode.

[0003] Silicon-based negative electrode materials have a high theoretical lithium intercalation capacity of about 4200 mAh / g and a moderate lithium intercalation platform, so they have attracted widespread attention from researchers. Silicon oxide has a smaller capacity than silicon, but it has obvious advantages in relieving volume expansion and improving the cycle life of the battery. However, during the first week of lithium intercalation, lithium reacts with silicon oxide to form irreversible lithium oxide, resulting in a loss of lithium and a decrease in the initial coulombic efficiency to less than 75%. In addition, although the volume expansion phenomenon is improved compared to silicon, it is still relatively obvious and affects the cycle performance.

[0004] In order to improve the initial coulombic efficiency of the battery made of silicon-based negative electrode material and alleviate the volume expansion, pre-lithiation or doping other elements are often used to improve it, but it is difficult to achieve uniform distribution and the effect is not ideal. Currently, poor cycle performance is still the main reason restricting the industrialization of silicon-based negative electrode materials.

[0005] Therefore, it is urgent to develop a silicon-based negative electrode material with high initial coulombic efficiency and good cycle performance. SUMMARY

[0006] The technical problem to be solved by the present application is to overcome the defect that the prior art cannot simultaneously satisfy high initial coulombic efficiency and good cycle performance of the silicon-based negative electrode material, and to provide a silicon-based negative electrode material, a preparation method and application thereof, and a battery. The silicon-based negative electrode material prepared by the present application has uniform distribution of silicon, silicon oxide and metal silicate, and has high electrical conductivity, high initial discharge capacity, high initial coulombic efficiency and good cycle performance when applied to lithium ion batteries, and has high application value in the fields of electric vehicles, portable power tools and household appliances.

[0007] The present application solves the above technical problems by the following technical solutions.

[0008] The present application provides a silicon-based negative electrode material, which is a core-shell structure, wherein the inner core comprises silicon grains, silicon oxide and metal silicate; and the shell layer is a carbon coating layer.

[0009] The metal silicate comprises a first metal element silicate and a second metal element silicate; the first metal element silicate and the second metal element silicate are uniformly distributed in the core.

[0010] In the XRD pattern of the silicon-based negative electrode material, a characteristic diffraction peak with an intensity of 1000-2000 appears between 25° and 30°.

[0011] In the present application, the size of the silicon crystal grain can be 0-50 nm and not 0, preferably 0-30 nm and not 0, more preferably 3-13 nm, such as 4.2 nm, 4.7 nm, 6.5 nm, 6.8 nm, 8 nm, 8.3 nm, 8.8 nm, 9.2 nm, 10 nm, 10.5 nm, 11.5 nm, 12.5 nm or 13 nm. The size of the silicon crystal grain can be calculated according to the Debye-Scherrer formula.

[0012] In the present application, the content of the silicon oxide can be 65-99.8%, % means that the silicon oxide accounts for the mass percentage of the silicon-based negative electrode material.

[0013] In the present application, the molecular formula of the metal silicate can be M y SiO z , 0 < y < 10, 0 < z < 10, M represents a metal element.

[0014] In the present application, the first metal element in the first metal element silicate and the second metal element in the second metal element silicate can each independently be Li, Na, K, Rb, Be, Mg, Ca, Sr, Ba, Zn, Cd, Al, Ga, In, Ge, Sn, Pb, Ag, Tl, Sc, Cu, Hg, Ti, Cr, Fe, Co or Ni, preferably Li, Na, K, Be, Mg, Ca, Sr, Ba, Zn, Cd, Al, Ga, In, Sn, Pb, Ag, Fe, Co or Ni, such as Mg, Li, Al, Zn, Ag or Cd.

[0015] Preferably, the combination of the first metal element and the second metal element is “Mg and Li”, “Li and Mg”, “Mg and Al”, “Al and Mg”, “Al and Zn”, “Zn and Al”, “Mg and Zn”, “Zn and Mg”, “Zn and Ag”, “Ag and Zn”, “Cd and Zn” or “Zn and Cd”.

[0016] In the present application, the mass ratio of the first metal element silicate and the second metal element silicate, in terms of the mass of the metal element, can be 1:(0.1-1), such as 1:0.1, 1:0.2, 1:0.25, 1:0.4, 1:0.75 or 1:1.

[0017] Preferably, the combination of the first metal element and the second metal element is "Mg and Al" in a mass ratio of 1:(0.6-0.8), for example 1:0.75.

[0018] Preferably, the combination of the first metal element and the second metal element is "Al and Mg" in a mass ratio of 1:(0.6-0.8), for example 1:0.75.

[0019] Preferably, the combination of the first metal element and the second metal element is "Mg and Li" in a mass ratio of 1:(0.1-0.3), for example 1:0.2.

[0020] In the present application, the metal silicate can further comprise a third metal element silicate; the third metal element silicate is uniformly distributed in the inner core.

[0021] Preferably, the third metal element in the third metal element silicate is Li, Na, K, Rb, Be, Mg, Ca, Sr, Ba, Zn, Cd, Al, Ga, In, Ge, Sn, Pb, Ag, Tl, Sc, Cu, Hg, Ti, Cr, Fe, Co or Ni, more preferably Li, Na, K, Be, Mg, Ca, Sr, Ba, Zn, Cd, Al, Ga, In, Sn, Pb, Ag, Fe, Co or Ni, for example Mg, Li, Al, Zn, Ag or Cd. In the present application, the metal elements in the first metal element silicate, the second metal element silicate and the third metal element silicate are different.

[0022] When the third metal element silicate is included, the combination of the first metal element, the second metal element and the third metal element is preferably "Mg, Al and Li".

[0023] When the third metal element silicate is included, preferably, the mass of the third metal element silicate does not exceed 30% of the total mass of the three metal element silicates, in terms of the mass of the metal elements; preferably, the mass ratio of the first metal element silicate, the second metal element silicate and the third metal element silicate is 1:(0.1-1):(0.1-1), for example 1:0.25:0.25 or 1:0.25:0.125.

[0024] More preferably, the combination of the first metal element, the second metal element and the third metal element is "Mg, Al and Li" in a mass ratio of 1:(0.1-0.3):(0.1-0.3), for example 1:0.25:0.25 or 1:0.25:0.125.

[0025] In the present application, the content of the metal silicate can be 0.1-40%, preferably 0.1-30%, more preferably 0.1-20%, for example 8%, 9.2%, 9.7%, 10.7%, 11.2% or 17.7%, % refers to the mass percentage of the metal silicate in the silicon-based negative electrode material.

[0026] In the present application, the uniform distribution is generally understood by those skilled in the art as having substantially no concentration gradient from the surface of the core to the center. The uniform distribution of the present application is different from the prior art, which has a large concentration difference between the outer layer and the inner layer, for example, there is almost no doping in the center of the core, and the concentration increases from the center of the core to the surface. The uniform distribution can reduce internal stress and more effectively alleviate the swelling phenomenon.

[0027] In the present application, preferably, in the XRD pattern of the silicon-based negative electrode material, a characteristic diffraction peak with an intensity of 620 appears between 45° and 50°, and a characteristic diffraction peak with an intensity of 460 appears between 56° and 60°.

[0028] In the present application, the core can be a porous structure. The porous structure can alleviate the swelling phenomenon and enhance the ability of lithium ion intercalation and deintercalation.

[0029] In the present application, the shell layer can be a lamellar structure; preferably, the lamellar structure is a porous lamellar structure.

[0030] In the present application, the content of the carbon coating layer can be 0.1-15%, preferably 0.1-10%, more preferably 3-7%, for example 3.4%, 3.7%, 3.9%, 4.8%, 5.2%, 5.3%, 5.6%, 5.8% or 6.2%, % refers to the mass percentage of the carbon coating layer in the silicon-based negative electrode material.

[0031] In the present application, the thickness of the carbon coating layer can be 1 nm-1 μm, for example 500 nm.

[0032] In the present application, the particle size D50 of the silicon-based negative electrode material can be 0.1-40 μm, preferably 4-8 μm, more preferably 5.1-5.7 μm, for example 5.1 μm, 5.2 μm, 5.3 μm, 5.5 μm, 5.6 μm or 5.7 μm.

[0033] In the present application, the specific surface area of the silicon-based negative electrode material can be 0.72-13 m 2 / g, preferably 5.9-9.2 m 2 / g, for example 5.9 m 2 / g, 6.61 m 2 / g, 6.4 m 2 / g, 6.5 m 2 / g, 7 m 2 / g, 7.3 m2 / g, 8.1 m 2 / g, 8.2 m 2 / g, 8.6 m 2 / g or 9.2 m 2 / g.

[0034] The application also provides a preparation method of the silicon-based negative electrode material, comprising the following steps:

[0035] (1) uniformly mixing silicon element, silicon oxide and metal element to obtain material A; the metal element comprises first metal element and second metal element;

[0036] (2) subjecting the material A to heat treatment and deposition to obtain material B;

[0037] (3) subjecting the material B to carbon coating.

[0038] In step (1), the silicon element can be in powder form.

[0039] In step (1), the particle size of the silicon element can be 10-80 μm.

[0040] In step (1), the molecular formula of the silicon oxide can be SiO x , 0 < x ≤ 2; preferably, the range of x is 0.5 ≤ x ≤ 2, more preferably 0.7 ≤ x ≤ 2. The larger the value of x, the higher the percentage content of oxygen element, the more stable the prepared silicon-based negative electrode material, and the better the cycle performance of the secondary battery, but the specific capacity and the first coulomb efficiency of the secondary battery are lower; the smaller the value of x, the lower the percentage content of oxygen element, the higher the specific capacity and the first coulomb efficiency of the prepared secondary battery, but the cycle performance of the secondary battery is reduced due to the reduced stability of the silicon-based negative electrode material. Preferably, the molecular formula of the silicon oxide is SiO2.

[0041] In step (1), the silicon oxide can be in powder form.

[0042] In step (1), the particle size of the silicon oxide can be 10-50 μm.

[0043] In step (1), the molar ratio of the silicon element to the silicon oxide can be 1: (0.5-2), for example, 1:1.

[0044] In step (1), the metal element can be in powder form.

[0045] In step (1), the particle size of the metal element can be 50-200 μm.

[0046] In step (1), the first and second metal elements can each independently be Li, Na, K, Rb, Be, Mg, Ca, Sr, Ba, Zn, Cd, Al, Ga, In, Ge, Sn, Pb, Ag, Tl, Sc, Cu, Hg, Ti, Cr, Fe, Co or Ni, preferably Li, Na, K, Be, Mg, Ca, Sr, Ba, Zn, Cd, Al, Ga, In, Sn, Pb, Ag, Fe, Co or Ni, for example Mg, Li, Al, Zn, Ag or Cd.

[0047] Preferably, the combination of the first and second metal elements is "Mg and Li", "Li and Mg", "Mg and Al", "Al and Mg", "Al and Zn", "Zn and Al", "Mg and Zn", "Zn and Mg", "Zn and Ag", "Ag and Zn", "Cd and Zn" or "Zn and Cd".

[0048] In step (1), the mass ratio of the first and second metal elements can be 1:(0.1-1), for example 1:0.1, 1:0.2, 1:0.25, 1:0.4, 1:0.75 or 1:1.

[0049] Preferably, the combination of the first and second metal elements is "Mg and Al" and the mass ratio is 1:(0.6-0.8), for example 1:0.75.

[0050] Preferably, the combination of the first and second metal elements is "Al and Mg" and the mass ratio is 1:(0.6-0.8), for example 1:0.75.

[0051] Preferably, the combination of the first and second metal elements is "Mg and Li" and the mass ratio is 1:(0.1-0.3), for example 1:0.2.

[0052] In step (1), the metal elements can further comprise a third metal element.

[0053] Preferably, the combination of the first and second metal elements is "Mg and Al" and the mass ratio is 1:(0.6-0.8), for example 1:0.75.

[0054] When a third metal element is included, the combination of the first metal element, the second metal element and the third metal element is preferably "Mg, Al and Li".

[0055] When a third metal element is included, preferably the mass of the third metal element is no more than 30% of the total mass of the three metal elements; preferably, the mass ratio of the first metal element, the second metal element and the third metal element is 1:(0.1-1):(0.1-1), for example 1:0.25:0.25 or 1:0.25:0.125.

[0056] More preferably, the combination of the first metal element, the second metal element and the third metal element is "Mg, Al and Li", and the mass ratio is 1:(0.1-0.3):(0.1-0.3), for example 1:0.25:0.25 or 1:0.25:0.125.

[0057] In step (1), the content of the metal element is 5-30%, % refers to the mass percentage of the metal element in material A, for example 9.9%.

[0058] In step (1), the mixing method can be ball milling, mechanical mixing or liquid dispersion, preferably mechanical mixing.

[0059] In step (2), the temperature of the heat treatment can be 900-2000℃, preferably 1000-1400℃, more preferably 1200-1400℃.

[0060] In step (2), the pressure of the heat treatment can be 0.01-5Pa, preferably 0.01-1Pa.

[0061] In step (2), the time of the heat treatment can be 25-35h, for example 30h.

[0062] In step (2), the temperature of the deposition can be 700-800℃. By adjusting the temperature of the deposition, the deposition rate is controlled, the lower the deposition temperature, the faster the deposition rate and the larger the pore size, the higher the deposition temperature, the slower the deposition rate and the smaller the pore size. In the temperature range of the present application, a suitable porous structure can be formed.

[0063] In step (2), under the condition of vacuum and high temperature, the silicate generated by the reaction of the material after vaporization is evaporated, and then the material is deposited. The process of material deposition is controlled by temperature to adjust the structure of the product. After evaporation and reaction, the molecules are arranged again, and the material is deposited after secondary arrangement to form a porous structure.

[0064] In step (2), the deposition can further include a crushing operation. The crushing can include coarse crushing and fine crushing.

[0065] Preferably, a crusher is used for the coarse crushing of the material.

[0066] Preferably, the fine crushing method is one or more of high-energy ball milling, grinding, jet milling and mechanical milling, for example high-energy ball milling. The fine crushing operation can expand the inherent or newly generated cracks on the particle surface, thereby causing the particle to break or to be plastically deformed and crushed, and obtaining the material B of the desired size with less internal cracks and stable structure.

[0067] When high-energy ball milling is used, the rotation speed of the ball mill can be 1000-1400 r / min, for example 1200 r / min.

[0068] When high-energy ball milling is used, the ball milling time can be 4-8 h, for example 6 h.

[0069] When high-energy ball milling is used, the ball milling is preferably carried out in an inert atmosphere. The inert atmosphere generally refers to an atmosphere formed by a gas that does not participate in the reaction of the system, and is not limited to inert gas, but can also be nitrogen. For example, the gas in the inert atmosphere can be one or more of nitrogen, helium, argon and helium, and for example nitrogen.

[0070] In step (3), the median particle size of the material B can be 1-99 μm, preferably 1-20 μm, for example 4.5 μm.

[0071] In step (3), the carbon coating can be carried out by one or more of gas phase coating, liquid phase coating and solid phase coating, for example by gas phase coating.

[0072] When gas phase coating is used, the coating is preferably carried out under the protection of an inert atmosphere. The inert atmosphere generally refers to an atmosphere formed by a gas that does not participate in the reaction of the system, and is not limited to inert gas, but can also be nitrogen. For example, the gas in the inert atmosphere can be one or more of nitrogen, helium, argon and helium, and for example nitrogen.

[0073] When gas phase coating is used, the temperature can be 700-1100 °C, for example 950 °C.

[0074] Preferably, the temperature is programmed to rise to the carbon coating temperature, and the rate of temperature rise is 2-5 °C / min, for example 3 °C / min. The programmed temperature rise can adapt to the temperature requirements of different types of carbon sources.

[0075] When gas phase coating is used, the time can be 6-10 h, for example 8 h.

[0076] When gas phase coating is used, the carbon source is introduced after the temperature is raised to the carbon coating temperature.

[0077] The carbon source can be any two of ethylene, propylene, acetylene, propyne, methane, ethanol, propanol and isopropanol, for example, ethanol and propanol.

[0078] The gas flow of the carbon source can be 0.1-10 L / min, preferably 0.5 L / min.

[0079] In step (3), by adjusting the type and gas flow of the carbon source, the coating structure of the material surface is realized, which can buffer the volume change of the silicon negative electrode in the charging and discharging process, improve the conductivity of the silicon material, and avoid the agglomeration of silicon particles in the charging and discharging cycle.

[0080] In step (3), the carbon coating can be carried out in a rotary furnace.

[0081] In step (3), after the carbon coating, cooling and sieving operations can be further included.

[0082] The mesh size of the sieving can be 200-400 mesh, for example, 300 mesh.

[0083] The application also provides a silicon-based negative electrode material prepared by the above preparation method.

[0084] The application also provides the application of the above silicon-based negative electrode material in a lithium ion battery.

[0085] The application also provides a lithium ion battery comprising the above silicon-based negative electrode material.

[0086] On the basis of common sense in the art, the above preferred conditions can be combined arbitrarily, i.e., to obtain each preferred example of the application.

[0087] The reagents and raw materials used in the application are commercially available.

[0088] The positive progress of the application is that:

[0089] The application adopts a simple preparation process to construct defects generated by multiple metals, improve the intrinsic ion transport capacity of the silicon-based negative electrode material, reduce the consumption of lithium ions in the first charging and discharging process, improve the energy density of the lithium ion battery, and combine carbon coating to realize high electrical conductivity, first discharge capacity (which can reach 1423-1481 mAh / g) and first coulomb efficiency (which can reach 86.7-93.5%).

[0090] The silicon, silicon oxide and metal silicate in the silicon-based negative electrode material prepared by the application are uniformly distributed, compared with the doping technology of core concentration gradient, the application has a buffering effect, reduces the internal stress of the particles in the charging and discharging process, and thus greatly reduces the swelling phenomenon, improves the cycle performance (which can realize a 50-week capacity retention rate of 94-99%). Attached Figure Description

[0091] Figure 1 This is a schematic diagram of the structure of the silicon-based anode material prepared in Example 4.

[0092] Figure 2 This is a cross-sectional FESEM image of the silicon-based anode material prepared in Example 4.

[0093] Figure 3 Here is a line scan distribution of metal elements in the silicon-based anode material prepared in Example 4; where, Figure 3 (a) is the elemental distribution diagram of Al; Figure 3 (b) is the elemental distribution diagram of Mg.

[0094] Figure 4 The image shows the Raman spectrum of the silicon-based anode material prepared in Comparative Example 1.

[0095] Figure 5 The graphs show the 50-cycle capacity retention of the silicon-based anode materials prepared in Example 1 and Comparative Example 1.

[0096] Figure reference numerals: 1-Silicon oxide; 2-Silicon; 3-Metal silicate-1; 4-Metal silicate-2; 5-Carbon coating. Detailed Implementation

[0097] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.

[0098] Example 1

[0099] Silicon powder and silica powder were mechanically mixed at a 1:1 molar ratio to obtain 10 kg of mixed powder. 1 kg of magnesium powder and 100 g of lithium hydride powder were added, and the mixture was heated for 30 h under vacuum conditions below 1 Pa and at a temperature of 1200-1400 °C to induce a gas-phase reaction, generating a magnesium-lithium doped silicon-oxygen anode. The material was then deposited at 700-800 °C. The magnesium-lithium doped silicon-oxygen anode was crushed in a crusher and then fed into a ball mill. It was ball-milled for 6 h at 1200 r / min under nitrogen protection until the median particle size of silicon suboxide was 4.5 μm. The ground silicon suboxide was put into a rotary furnace and coated with gas at a rate of 3°C / min under nitrogen protection. The temperature was increased to 950°C, and then a mixture of ethanol and propanol was introduced at a flow rate of 0.5 L / min for both gases. The temperature was maintained for 8 hours and then cooled. The mixture was then passed through a 300-mesh sieve to obtain a multi-metal-doped silicon-oxygen anode material.

[0100] The particle size D50 of the silicon-based negative electrode material prepared in Example 1 is 5.2 μm, and the specific surface area is 8.2 m 2 / g, and the silicon grain size is 10 nm calculated according to XRD. The molecular formula of the metal silicate is Mg y SiO z , Li y SiO z , wherein 0 < y < 10 and 0 < z < 10; the content of the metal magnesium silicate is 9.3% determined by XRF element quantitative test, and the mass ratio of the metal magnesium silicate to the metal lithium silicate is 1:(0.1-1); the thickness of the carbon coating layer is about 500 nm, and the content of the carbon coating layer is 5.3% determined by a carbon-sulfur analyzer.

[0101] Example 2

[0102] Compared with Example 1, the difference is that 1 kg of metal magnesium powder and 200 g of lithium hydride powder are added, and other operations and conditions are the same as those in Example 1.

[0103] The particle size D50 of the silicon-based negative electrode material prepared in Example 2 is 5.5 μm, and the specific surface area is 6.1 m 2 / g, and the silicon grain size is 6.8 nm calculated according to XRD. The molecular formula of the metal silicate is Mg y SiO z , Li y SiO z , wherein 0 < y < 10 and 0 < z < 10; the content of the metal magnesium silicate is 9.5% determined by XRF element quantitative test, and the mass ratio of the metal magnesium silicate to the metal lithium silicate is 1:(0.1-1); the thickness of the carbon coating layer is about 500 nm, and the content of the carbon coating layer is 4.8%.

[0104] Example 3

[0105] Compared with Example 1, the difference is that 1 kg of metal magnesium powder and 400 g of metal aluminum powder are added, and other operations and conditions are the same as those in Example 1.

[0106] The particle size D50 of the silicon-based negative electrode material prepared in Example 3 is 5.3 μm, and the specific surface area is 9.2 m 2 / g, and the silicon grain size is 6.5 nm calculated according to XRD. The molecular formula of the metal silicate is Mg y SiO z , Al y SiO z, 0 < z < 10; the content of the two metal silicates is 9.2% as determined by XRF element quantitative test, the mass ratio of the metal magnesium silicate and the metal aluminum silicate is 1: (0.1-1); the thickness of the carbon coating layer is about 500 nm, and the content of the carbon coating layer is 3.9%.

[0107] Example 4

[0108] Compared with Example 1, the difference is that 800 g of metal aluminum powder and 600 g of metal magnesium powder are added, and other operations and conditions are the same as those in Example 1.

[0109] The particle size D50 of the silicon-based negative electrode material prepared in Example 4 is 5.1 μm, the specific surface area is 7 m 2 / g, and the silicon grain size is 8.8 nm as calculated according to XRD. The molecular formula of the metal silicate is Al y SiO z , Mg y SiO z , 0 < z < 10; the content of the two metal silicates is 10.7% as determined by XRF element quantitative test, the mass ratio of the metal aluminum silicate and the metal magnesium silicate is 1: (0.1-1); the thickness of the carbon coating layer is about 500 nm, and the content of the carbon coating layer is 5.6%.

[0110] Example 5

[0111] Compared with Example 1, the difference is that 800 g of metal magnesium powder and 600 g of metal aluminum powder are added, and other operations and conditions are the same as those in Example 1.

[0112] The particle size D50 of the silicon-based negative electrode material prepared in Example 5 is 5.6 μm, the specific surface area is 8.1 m 2 / g, and the silicon grain size is 9.2 nm as calculated according to XRD. The molecular formula of the metal silicate is Mg y SiO z , Al y SiO z , 0 < z < 10; the content of the two metal silicates is 11.2% as determined by XRF element quantitative test, the mass ratio of the metal magnesium silicate and the metal aluminum silicate is 1: (0.1-1); the thickness of the carbon coating layer is about 500 nm, and the content of the carbon coating layer is 5.2%.

[0113] Example 6

[0114] Compared with Example 1, the difference is that 800 g of metal magnesium powder, 200 g of metal aluminum powder and 200 g of lithium hydride powder are added, and other operations and conditions are the same as those in Example 1.

[0115] The D50 of the silicon-based anode material prepared in Example 6 is 5.5 μm, and the specific surface area is 6.4 m 2 / g. According to XRD calculation, the silicon grain size is 8.8 nm. The molecular formula of the metal silicate is Mg y SiO z 、Al y SiO z 、Li y SiO z , where 0 < y < 10, 0 < z < 10; the total content of metal magnesium silicate and metal aluminum silicate determined by XRF elemental quantitative test is 8.7%, and the mass ratio of metal magnesium silicate, metal aluminum silicate and metal lithium silicate is 1:(0.1 - 1):(0.1 - 1); the thickness of the carbon coating layer is about 500 nm, and the content of the carbon coating layer is 3.4%.

[0116] Example 7

[0117] Compared with Example 1, the difference is that 800 g of metal magnesium powder, 200 g of metal aluminum powder, and 100 g of lithium hydride powder are added, and other operations and conditions are the same as those in Example 1.

[0118] The D50 of the silicon-based anode material prepared in Example 7 is 5.7 μm, and the specific surface area is 5.9 m 2 / g. According to XRD calculation, the silicon grain size is 8.3 nm. The molecular formula of the metal silicate is Mg y SiO z 、Al y SiO z 、Li y SiO z , where 0 < y < 10, 0 < z < 10; the total content of metal magnesium silicate and metal aluminum silicate determined by XRF elemental quantitative test is 9.1%, and the mass ratio of metal magnesium silicate, metal aluminum silicate and metal lithium silicate is 1:(0.1 - 1):(0.1 - 1); the thickness of the carbon coating layer is about 500 nm, and the content of the carbon coating layer is 5.8%.

[0119] Example 8

[0120] Compared with Example 1, the difference is that 700 g of metal aluminum powder and 700 g of metal zinc powder are added, and other operations and conditions are the same as those in Example 1.

[0121] The D5 of the silicon-based anode material prepared in Example 8 is 5.6 μm, and the specific surface area is 6.5 m 2 / g. According to XRD calculation, the silicon grain size is 11.5 nm. The molecular formula of the metal silicate is Al y SiO z [[ID=y SiO z , wherein 0 < y < 10, 0 < z < 10; the content of the two metal silicates is 17.7% as determined by XRF elemental quantitative test, and the mass ratio of the metal aluminum silicate and the metal zinc silicate is 1 : (0.1-1); the thickness of the carbon coating layer is about 500 nm, and the content of the carbon coating layer is 3.7%.

[0122] Example 9

[0123] Compared with Example 1, the difference is that 700 g of metal magnesium powder and 700 g of metal zinc powder are added, and other operations and conditions are the same as those in Example 1.

[0124] The particle size D50 of the silicon-based negative electrode material prepared in Example 9 is 5.3 pm, and the specific surface area is 6 m 2 / g. The silicon grain size is 4.2 nm according to XRD calculation. The molecular formula of the metal silicate is Mg y SiO z , Zn y SiO z , wherein 0 < y < 10, 0 < z < 10; the content of the two metal silicates is 9.7% as determined by XRF elemental quantitative test, and the mass ratio of the metal magnesium silicate and the metal zinc silicate is 1 : (0.1-1); the thickness of the carbon coating layer is about 500 nm, and the content of the carbon coating layer is 5.6%.

[0125] Example 10

[0126] Compared with Example 1, the difference is that 700 g of metal zinc powder and 700 g of metal silver powder are added, and other operations and conditions are the same as those in Example 1.

[0127] The particle size D50 of the silicon-based negative electrode material prepared in Example 10 is 5.2 pm, and the specific surface area is 8.6 m 2 / g, and the silicon grain size is 4.7 nm according to XRD calculation. The molecular formula of the metal silicate is Zn y SiO z , Ag y SiO z , wherein 0 < y < 10, 0 < z < 10; the content of the two metal silicates is 8% as determined by XRF elemental quantitative test, and the mass ratio of the metal zinc silicate and the metal silver silicate is 1 : (0.1-1); the thickness of the carbon coating layer is about 500 nm, and the content of the carbon coating layer is 3.7%.

[0128] Example 11

[0129] Compared with Example 1, the difference is that 700 g of metal zinc powder and 700 g of metal cadmium powder are added, and other operations and conditions are the same as those in Example 1.

[0130] The particle size D50 of the silicon-based negative electrode material prepared in Example 11 was 5.7 μm, and the specific surface area was 7.3 m 2 / g, and the silicon grain size was 9.2 nm according to XRD calculation. The molecular formula of the metal silicate was Zn y SiO z , Cd y SiO z , wherein 0 < y < 10, 0 < z < 10; the content of the two metal silicates was 10.7% as determined by XRF element quantitative test, and the mass ratio of the metal zinc silicate and the metal cadmium silicate was 1:(0.1-1); the thickness of the carbon coating layer was about 500 nm, and the content of the carbon coating layer was 6.2%.

[0131] Comparative Example 1

[0132] Compared with Example 1, the difference was that no metal powder was added, and other operations and conditions were the same as those in Example 1.

[0133] The particle size D50 of the silicon-based negative electrode material prepared in Comparative Example 1 was 5.3 μm, and the specific surface area was 4.4 m 2 / g, and the silicon grain size was 1 nm according to XRD calculation. The thickness of the carbon coating layer was about 500 nm, and the content of the carbon coating layer was 5.6%.

[0134] Comparative Example 2

[0135] Compared with Example 1, the difference was that only 1 kg of metal magnesium powder was added, and other operations and conditions were the same as those in Example 1.

[0136] The particle size D50 of the silicon-based negative electrode material prepared in Comparative Example 2 was 5.1 μm, and the specific surface area was 4.1 m 2 / g, and the silicon grain size was 9 nm according to XRD calculation. The molecular formula of the metal silicate was Mg y SiO z , wherein 0 < y < 10, 0 < z < 10; the content of the metal magnesium silicate was 8.8% as determined by XRF element quantitative test; the thickness of the carbon coating layer was about 500 nm, and the content of the carbon coating layer was 5.8%.

[0137] Comparative Example 3

[0138] The silicon powder and the silicon dioxide powder are mechanically mixed uniformly at a molar ratio of 1:1 to obtain 10 kg of mixed powder, 1 kg of magnesium powder and 100 g of lithium hydride powder are added, and heating is performed under high-temperature vacuum conditions (0.01-5 Pa, 1000-1400 °C) to generate a silicon-oxygen negative electrode by gas-phase reaction, and the silicon-oxygen negative electrode is cooled and precipitated at a temperature of 1000-1050 °C. After the silicon-oxygen negative electrode is broken in a crusher, it is put into a ball mill under the condition of inert gas protection at 1200 r / min, and ball milling is performed for 6 h, so that the median particle size of the silicon monoxide is 4.5 μm. After the ground silicon monoxide is put into a rotary furnace, gas-phase coating is performed under the condition of nitrogen protection, the temperature is raised to 950 °C at a speed of 3 °C / min, and then ethanol and propyl alcohol mixed gas is started to be passed, the gas flow rate of the ethanol gas is 0.5 L / min, and the gas flow rate of the propyl alcohol gas is 0.5 L / min, and the temperature is kept constant for 8 h. Cooling obtains a total mass percentage of carbon of 5%; and a silicon-oxygen negative electrode material is prepared by passing through a 300-mesh sieve.

[0139] The particle size D50 of the silicon-based negative electrode material prepared in Comparative Example 3 is 5.3 μm, the specific surface area is 4.1 m 2 / g, and the silicon grain size is 17.3 nm calculated according to XRD. The molecular formula of the metal silicate is Mg y SiO z , wherein 0 < y < 10 and 0 < z < 10; the content of the magnesium silicate is 7% determined by XRF element quantitative test; the thickness of the carbon coating layer is about 500 nm, and the content of the carbon coating layer is 5.2%.

[0140] Morphology and structure of Example 1

[0141] Figure 1 The schematic diagram of the core-shell structure of the silicon-based negative electrode material prepared in Example 4 and the components in the core is not representative of the actual distribution of the components in the core.

[0142] The silicon-based negative electrode material prepared in Example 4 is characterized by FESEM sectioning using Zeiss Sigma 300. Figure 2 The cross-sectional view of the silicon-based negative electrode material is an inner structure, and the multiple pores are a porous structure.

[0143] The metal element line scanning distribution test of the silicon-based negative electrode material prepared in Example 4 is performed by using Thermo Elemental Analyzer. Figure 3 (a) and Figure 3 (b) can be observed. The concentration distribution of Al and Mg elements is relatively uniform.

[0144] The Raman spectrum analysis of the silicon-based negative electrode material prepared in Comparative Example 1 without doping metal is performed by using Renishaw Microscopic Confocal Spectrometer. Figure 42300 cm-1 is the characteristic absorption peak of nitrogen, indicating that nitrogen has been coated in the pore structure, i.e. the coating layer of the silicon-based negative electrode material prepared in Comparative Example 1 is a porous structure, which can exclude the influence of the porous structure on the performance of the product.

[0145] Effect Example 2 Electrochemical performance

[0146] The silicon-based negative electrode materials prepared in Examples 1-10 and Comparative Examples 1-2 were mixed with carbon black (SP) and sodium carboxymethyl cellulose (CMC) in a ratio of 7:2:1 to prepare negative electrode slurry, and after coating and drying, negative electrode sheets were prepared. With metal Li as the counter electrode, a button cell was assembled in a glove box and subjected to charge-discharge testing. The 50-week capacity retention test chart of the silicon-based negative electrode materials prepared in Example 1 and Comparative Example 1 is shown in FIG. 1. The battery test results are shown in Table 1. Figure 5

[0147] Table 1

[0148] Serial number Initial discharge capacity (mAh / g) Initial coulombic efficiency (%) 50-week capacity retention (%) Example 1 1480 91.1 99 Example 2 1468 93.2 98 Example 3 1450 89.3 97 Example 4 1450 86.7 99 Example 5 1470 87.1 98 Example 6 1478 93.1 99 Example 7 1481 93.5 98 Example 8 1423 87.1 95 Example 9 1430 87 97 Example 10 1428 87.0 94 Example 11 1430 87 94 Comparative Example 1 1600 75 78 Comparative Example 2 1475 82.8 88 Comparative Example 3 1450 80 85

[0149] According to Examples 1-2 and 5-7, when the metal elements include metal Mg and metal Li, or the metal elements are metal Mg and metal Al and the mass ratio of the two is 1:0.75, the initial discharge capacity can be above 1460 mAh / g.

[0150] According to Examples 2 and 6-7, when the three different metal elements are contained, or the metal elements are metal Mg and metal Li and the amount of the two is 1:0.2, the initial coulombic efficiency can be above 93%.

[0151] According to Examples 1, 4 and 6, when the metal elements are metal Mg and metal Li and the amount of the two is 1:0.1, or when the metal elements are metal Al and metal Mg and the amount of the two is 1:0.75, or when the three different metal elements are contained and the amount of the three is 1:0.25:0.25, the 50-week capacity retention rate can reach 99%.

[0152] According to Example 6, when the metal elements are metal Mg, metal Al and metal LiH and the amount of the three is 1:0.25:0.25, the initial discharge capacity, the initial coulombic efficiency and the comprehensive performance of the cycle performance can be the best.​

Claims

1. A silicon-based anode material, characterized in that, It is a core-shell structure, wherein the inner core comprises silicon grains, silicon oxide and metal silicate; the shell layer is a carbon coating layer; The metal silicate comprises a first metal element silicate and a second metal element silicate; the first metal element silicate and the second metal element silicate are uniformly distributed in the inner core; the combination of the first metal element and the second metal element is "Mg and Li", "Li and Mg", "Mg and Al" or "Al and Mg"; the thickness of the carbon coating layer is 500 nm-1 μm; The content of the silicon oxide is 65-99.8%, which refers to the mass percentage of silicon oxide in the silicon-based negative electrode material; the content of the metal silicate is 0.1-40%, which refers to the mass percentage of metal silicate in the silicon-based negative electrode material; In the XRD spectrum of the silicon-based negative electrode material, a characteristic diffraction peak with an intensity of 1000-2000 appears between 25° and 30°.

2. The silicon-based anode material of claim 1, wherein, The size of the silicon grains is 0-50 nm and not 0.

3. The silicon-based anode material of claim 2, wherein, The size of the silicon grains is 0-30 nm and not 0.

4. The silicon-based anode material of claim 3, wherein, The size of the silicon grains is 3-13 nm.

5. The silicon-based anode material of claim 4, wherein the silicon-based anode material has a capacity of at least 1000 mAh / g. The size of the silicon grains is 4.2 nm, 4.7 nm, 6.5 nm, 6.8 nm, 8 nm, 8.3 nm, 8.8 nm, 9.2 nm, 10 nm, 10.5 nm, 11.5 nm, 12.5 nm or 13 nm.

6. The silicon-based anode material of claim 1, wherein, The molecular formula of the metal silicate is M y SiO z , 0 < y < 10, 0 < z < 10, M represents a metal element.

7. The silicon-based anode material of claim 1, wherein, The mass ratio of the first metal element silicate to the second metal element silicate is 1:(0.1-1) in terms of the mass of metal elements.

8. The silicon-based anode material of claim 7, wherein, The mass ratio of the first metal element silicate to the second metal element silicate is 1:0.1, 1:0.2, 1:0.25, 1:0.4, 1:0.75 or 1:1 in terms of the mass of metal elements.

9. The silicon-based anode material of claim 8, wherein, The combination of the first metal element and the second metal element is "Mg and Al", and the mass ratio is 1:(0.6-0.8); or the combination of the first metal element and the second metal element is "Al and Mg", and the mass ratio is 1:(0.6-0.8); or the combination of the first metal element and the second metal element is "Mg and Li", and the mass ratio is 1:(0.1-0.3).

10. The silicon-based anode material of claim 9, wherein, The combination of the first metal element and the second metal element is "Mg and Al", and the mass ratio is 1:0.75; or the combination of the first metal element and the second metal element is "Al and Mg", and the mass ratio is 1:0.75; or the combination of the first metal element and the second metal element is "Mg and Li", and the mass ratio is 1:0.

2.

11. The silicon-based anode material of claim 1, wherein, The content of the metal silicate is 0.1-30%.

12. The silicon-based anode material of claim 11, wherein, The content of the metal silicate is 0.1-20%.

13. The silicon-based anode material of claim 12, wherein, The content of the metal silicate is 8%, 9.2%, 9.7%, 10.7%, 11.2% or 17.7%.

14. The silicon-based anode material of claim 1, wherein, The metal silicate further comprises a third metal element silicate, which is uniformly distributed in the inner core.

15. The silicon-based anode material of claim 14, wherein, The third metal element in the third metal element silicate is Li, Na, K, Rb, Be, Mg, Ca, Sr, Ba, Zn, Cd, Al, Ga, In, Ge, Sn, Pb, Ag, Tl, Sc, Cu, Hg, Ti, Cr, Fe, Co or Ni.

16. The silicon-based anode material of claim 15, wherein, The third metal element in the third metal element silicate is Li, Na, K, Be, Mg, Ca, Sr, Ba, Zn, Cd, Al, Ga, In, Sn, Pb, Ag, Fe, Co or Ni.

17. The silicon-based anode material of claim 16, wherein, The third metal element in the third metal element silicate is Mg, Li, Al, Zn, Ag or Cd.

18. The silicon-based anode material of claim 14, wherein, The mass of the third metal element silicate is not more than 30% of the total mass of the three metal element silicates.

19. The silicon-based anode material of claim 14, wherein, The mass ratio of the first metal element silicate, the second metal element silicate and the third metal element silicate is 1:(0.1-1):(0.1-1).

20. The silicon-based anode material of claim 19, wherein, The mass ratio of the first metal element silicate, the second metal element silicate and the third metal element silicate is 1:0.25:0.25 or 1:0.25:0.

125.

21. The silicon-based anode material of claim 14, wherein, The combination of the first metal element, the second metal element and the third metal element is "Mg, Al and Li".

22. The silicon-based anode material of claim 21, wherein, The combination of the first metal element, the second metal element and the third metal element is "Mg, Al and Li", and the mass ratio is 1:(0.1-0.3):(0.1-0.3).

23. The silicon-based anode material of claim 22, wherein, The combination of the first metal element, the second metal element and the third metal element is "Mg, Al and Li", and the mass ratio is 1:0.25:0.25 or 1:0.25:0.

125.

24. The silicon-based anode material of claim 1, wherein, In the XRD pattern of the silicon-based negative electrode material, a characteristic diffraction peak with an intensity of 620 appears between 45° and 50°, and a characteristic diffraction peak with an intensity of 460 appears between 56° and 60°.

25. The silicon-based anode material of claim 1, wherein, The core is a porous structure.

26. The silicon-based anode material of claim 1, wherein, The shell layer is a lamellar structure.

27. The silicon-based anode material of claim 26, wherein, The lamellar structure is a porous lamellar structure.

28. The silicon-based anode material of claim 1, wherein, The content of the carbon coating layer is 0.1-15%, which refers to the mass percentage of the carbon coating layer in the silicon-based negative electrode material.

29. The silicon-based anode material of claim 28, wherein, The content of the carbon coating layer is 0.1-10%.

30. The silicon-based anode material of claim 29, wherein, The content of the carbon coating layer is 3-7%.

31. The silicon-based anode material of claim 30, wherein, The content of the carbon coating layer is 3.4%, 3.7%, 3.9%, 4.8%, 5.2%, 5.3%, 5.6%, 5.8% or 6.2%.

32. The silicon-based anode material of claim 1, wherein, The thickness of the carbon coating layer is 500 nm.

33. The silicon-based anode material of claim 1, wherein, The particle size D50 of the silicon-based negative electrode material is 0.1-40 μm.

34. The silicon-based anode material of claim 33, wherein, The particle size D50 of the silicon-based negative electrode material is 4-8 μm.

35. The silicon-based anode material of claim 34, wherein, The particle size D50 of the silicon-based negative electrode material is 5.1-5.7 μm.

36. The silicon-based anode material of claim 35, wherein, The particle size D50 of the silicon-based negative electrode material is 5.1 μm, 5.2 μm, 5.3 μm, 5.5 μm, 5.6 μm or 5.7 μm.

37. The silicon-based anode material of claim 1, wherein, The specific surface area of the silicon-based negative electrode material is 0.72-13 m 2 / g.

38. The silicon-based anode material of claim 37, wherein, The specific surface area of the silicon-based negative electrode material is 5.9-9.2 m 2 / g.

39. The silicon-based anode material of claim 38, wherein, The specific surface area of the silicon-based negative electrode material is 5.9 m 2 / g, 6.61 m 2 / g, 6.4 m 2 / g, 6.5 m 2 / g, 7 m 2 / g, 7.3 m 2 / g, 8.1 m 2 / g, 8.2 m 2 / g, 8.6 m 2 / g or 9.2 m 2 / g.

40. A method of producing a silicon-based anode material, characterized by, It comprises the following steps: (1) uniformly mixing silicon element, silicon oxide and metal element to obtain material A; the metal element comprises a first metal element and a second metal element; the combination of the first metal element and the second metal element is "Mg and Li", "Li and Mg", "Mg and Al" or "Al and Mg"; the molar ratio of the silicon element to the silicon oxide is 1:(0.5-2); the content of the metal element is 5-30%, which refers to the mass percentage of the metal element in the material A; (2) the material A is subjected to heat treatment and deposition to obtain material B; the temperature of the heat treatment is 900-2000 ℃; the temperature of the deposition is 700-800 ℃; (3) the material B is subjected to carbon coating to obtain a carbon coating layer with a thickness of 500 nm-1 μm.

41. The method for preparing the silicon-based anode material as described in claim 40, characterized in that, In step (1), the silicon element is in powder form.

42. The method for preparing the silicon-based anode material as described in claim 40, characterized in that, In step (1), the particle size of the silicon element is 10-80 μm.

43. The method for preparing the silicon-based anode material as described in claim 40, characterized in that, In step (1), the silicon oxide has a molecular formula of SiO x , 0 < x < 2.

44. The method of claim 43, wherein the silicon-based anode material is prepared by a process comprising: In step (1), in the silicon oxide, the range of x is 0.5≤x≤2.

45. The method for preparing the silicon-based anode material as described in claim 44, characterized in that, In step (1), in the silicon oxide, the range of x is 0.7≤x≤2.

46. The method of claim 45, wherein the silicon-based anode material is prepared by a process comprising: In step (1), the molecular formula of the silicon oxide is SiO2.

47. The method for preparing the silicon-based anode material as described in claim 40, characterized in that, In step (1), the silicon oxide is in powder form.

48. The method for preparing the silicon-based anode material as described in claim 40, characterized in that, In step (1), the particle size of the silicon oxide is 10-50 μm.

49. The method for preparing the silicon-based anode material as described in claim 40, characterized in that, In step (1), the molar ratio of the silicon element to the silicon oxide is 1:

1.

50. The method for preparing the silicon-based anode material as described in claim 40, characterized in that, In step (1), the metal element is in powder form.

51. The method for preparing the silicon-based anode material as described in claim 40, characterized in that, In step (1), the particle size of the metal element is 50-200 μm.

52. The method for preparing the silicon-based anode material as described in claim 40, characterized in that, In step (1), the mass ratio of the first metal element to the second metal element is 1:(0.1-1).

53. The method of claim 52, wherein the silicon-based anode material is prepared by a process comprising: In step (1), the mass ratio of the first metal element to the second metal element is 1:0.1, 1:0.2, 1:0.25, 1:0.4, 1:0.75 or 1:

1.

54. The method of claim 53, wherein the silicon-based anode material is prepared by a process comprising: In step (1), the combination of the first metal element and the second metal element is "Mg and Al", and the mass ratio is 1:(0.6-0.8); or the combination of the first metal element and the second metal element is "Al and Mg", and the mass ratio is 1:(0.6-0.8); or the combination of the first metal element and the second metal element is "Mg and Li", and the mass ratio is 1:(0.1-0.3).

55. The method of claim 54, wherein the silicon-based anode material is prepared by a process comprising: In step (1), the combination of the first metal element and the second metal element is "Mg and Al", and the mass ratio is 1:0.75; or the combination of the first metal element and the second metal element is "Al and Mg", and the mass ratio is 1:0.75; or the combination of the first metal element and the second metal element is "Mg and Li", and the mass ratio is 1:0.

2.

56. The method for preparing the silicon-based anode material as described in claim 40, characterized in that, In step (1), the metal element further comprises a third metal element.

57. The method of claim 56, wherein the silicon-based anode material is prepared by a process comprising: In step (1), the third metal element is Li, Na, K, Rb, Be, Mg, Ca, Sr, Ba, Zn, Cd, Al, Ga, In, Ge, Sn, Pb, Ag, Tl, Sc, Cu, Hg, Ti, Cr, Fe, Co or Ni.

58. The method of claim 57, wherein the silicon-based anode material is prepared by a process comprising: In step (1), the third metal element is Li, Na, K, Be, Mg, Ca, Sr, Ba, Zn, Cd, Al, Ga, In, Sn, Pb, Ag, Fe, Co or Ni.

59. The method of claim 58, wherein the silicon-based anode material is prepared by a process comprising: In step (1), the third metal element is Mg, Li, Al, Zn, Ag or Cd.

60. The method of claim 59, wherein the silicon-based anode material is prepared by a process comprising: In step (1), the combination of the first metal element, the second metal element and the third metal element is "Mg, Al and Li".

61. The method of producing a silicon-based anode material according to claim 60, wherein In step (1), the mass of the third metal element is not more than 30% of the total mass of the three metal elements.

62. The method of claim 61, wherein the silicon-based anode material is prepared by a process comprising: In step (1), the mass ratio of the first metal element, the second metal element and the third metal element is 1:(0.1-1):(0.1-1).

63. The method of claim 62, wherein the silicon-based anode material is prepared by a process comprising: In step (1), the mass ratio of the first metal element, the second metal element and the third metal element is 1:0.25:0.25 or 1:0.25:0.

125.

64. The method of claim 63, wherein the silicon-based anode material is prepared by a process comprising: In step (1), the combination of the first metal element, the second metal element and the third metal element is "Mg, Al and Li", and the mass ratio is 1:(0.1-0.3):(0.1-0.3).

65. The method of claim 64, wherein the silicon-based anode material is prepared by a process comprising: In step (1), the combination of the first metal element, the second metal element and the third metal element is "Mg, Al and Li", and the mass ratio is 1:0.25:0.25 or 1:0.25:0.

125.

66. The method of claim 40, wherein the silicon-based anode material is prepared by a process comprising: In step (1), the content of the metal element is 9.9%.

67. The method of producing a silicon-based anode material of claim 40, wherein the silicon-based anode material is produced by the method of claim 66. In step (1), the mixing method is ball milling, mechanical mixing or liquid dispersion.

68. The method of claim 40, wherein the silicon-based anode material is prepared by a process comprising: In step (2), the temperature of the heat treatment is 1000-1400°C.

69. The method of claim 68, wherein the silicon-based anode material is prepared by a process comprising: In step (2), the temperature of the heat treatment is 1200-1400°C.

70. The method of claim 40, wherein the silicon-based anode material is prepared by a process comprising: In step (2), the pressure of the heat treatment is 0.01-5 Pa.

71. The method of claim 70, wherein the silicon-based anode material is prepared by a process comprising: In step (2), the pressure of the heat treatment is 0.01-1 Pa.

72. The method of claim 40, wherein the silicon-based anode material is prepared by a process comprising: In step (2), the time of the heat treatment is 25-35 h.

73. The method of claim 72, wherein the silicon-based anode material is prepared by a process comprising: In step (2), the time of the heat treatment is 30 h.

74. The method of producing a silicon-based anode material of claim 40, wherein the silicon-based anode material is produced by the method of claim 73. In step (2), the deposition further comprises a crushing operation.

75. The method of claim 74, wherein the silicon-based anode material is prepared by a process comprising: In step (2), the crushing comprises coarse crushing and fine crushing.

76. The method of claim 75, wherein the silicon-based anode material is prepared by a process comprising: In step (2), the coarse crushing is performed by a crusher.

77. The method of claim 75, wherein the silicon-based anode material is prepared by a process comprising: In step (2), the fine crushing is performed by one or more of high-energy ball milling, grinding, air-jet milling and mechanical milling.

78. The method of claim 77, wherein the silicon-based anode material is prepared by a process comprising: In step (2), the fine crushing is performed by high-energy ball milling, and the rotation speed of the ball mill is 1000-1400 r / min.

79. The method of claim 78, wherein the silicon-based anode material is prepared by a process comprising: In step (2), the fine crushing is performed by high-energy ball milling, and the rotation speed of the ball mill is 1200 r / min.

80. The method of claim 77, wherein the silicon-based anode material is prepared by a process comprising: In step (2), the fine crushing is performed by high-energy ball milling, and the time of the ball milling is 4-8 h.

81. The method of claim 80, wherein the silicon-based anode material is prepared by a process comprising: In step (2), the fine crushing is performed by high-energy ball milling, and the time of the ball milling is 6 h.

82. The method of claim 77, wherein the silicon-based anode material is prepared by a process comprising: In step (2), the fine grinding method is high-energy ball milling, and the ball milling is performed in an inert atmosphere.

83. The method of claim 82, wherein the silicon-based anode material is prepared by a process comprising: In step (2), in the high-energy ball milling, the inert atmosphere is one or more of nitrogen, helium, and argon.

84. The method of producing a silicon-based anode material of claim 40, wherein, In step (3), the median particle size of material B is 1-99 μm.

85. The method of claim 84, wherein the silicon-based anode material is prepared by a process comprising: In step (3), the median particle size of material B is 1-20 μm.

86. The method of claim 85, wherein the silicon-based anode material is prepared by a process comprising: In step (3), the median particle size of material B is 4.5 μm.

87. The method for preparing the silicon-based anode material as described in claim 40, characterized in that, In step (3), the carbon coating is performed by one or more of a gas-phase coating method, a liquid-phase coating method, and a solid-phase coating method.

88. The method of claim 87, wherein the silicon-based anode material is prepared by a process comprising: In step (3), the carbon coating is performed by a gas-phase coating method under the protection of an inert atmosphere.

89. The method of claim 88, wherein the silicon-based anode material is prepared by a process comprising: In step (3), in the carbon coating, the inert atmosphere is one or more of nitrogen, helium, and argon.

90. The method of claim 87, wherein the silicon-based anode material is prepared by a process comprising: In step (3), the carbon coating is performed by a gas-phase coating method at a temperature of 700-1100℃.

91. The method of claim 90, wherein the silicon-based anode material is prepared by a process comprising: In step (3), the carbon coating is performed by a gas-phase coating method at a temperature of 950℃.

92. The method of claim 91, wherein the silicon-based anode material is prepared by a process comprising: In step (3), in the carbon coating, the temperature is programmed to increase to the carbon coating temperature at a rate of 2-5 ℃ / min.

93. The method of claim 92, wherein the silicon-based anode material is prepared by a process comprising: In step (3), in the carbon coating, the temperature is programmed to increase to the carbon coating temperature at a rate of 3 ℃ / min.

94. The method of claim 87, wherein the silicon-based anode material is prepared by a process comprising: In step (3), the carbon coating is performed by a gas-phase coating method for 6-10 h.

95. The method of claim 94, wherein the silicon-based anode material is prepared by a process comprising: In step (3), the carbon coating is performed by a gas-phase coating method for 8 h.

96. The method of claim 87, wherein the silicon-based anode material is prepared by a process comprising: In step (3), the carbon coating is performed by a gas-phase coating method, in which the temperature is first increased to the carbon coating temperature and then the carbon source is introduced.

97. The method of claim 96, wherein the silicon-based anode material is prepared by a process comprising: In step (3), the carbon source is any two of ethylene, propylene, acetylene, propyne, methane, ethanol, propanol, and isopropanol.

98. The method of claim 97, wherein the silicon-based anode material is prepared by a process comprising: In step (3), the carbon source is "ethanol and propanol".

99. The method of claim 96, wherein the silicon-based anode material is prepared by a process comprising: In step (3), the gas flow rate of the carbon source is 0.1-10 L / min.

100. The method of claim 99, wherein the silicon-based anode material is prepared by a process comprising: In step (3), the gas flow rate of the carbon source is 0.5 L / min.

101. The method of claim 40, wherein the silicon-based anode material is prepared by a process comprising: In step (3), after the carbon coating, the material is further subjected to cooling and sieving.

102. The method of claim 101, wherein the silicon-based anode material is prepared by a process comprising: In step (3), the sieving is performed with a mesh size of 200-400 mesh.

103. The method of claim 102, wherein the silicon-based anode material is prepared by a process comprising: In step (3), the sieving is performed with a mesh size of 300 mesh.

104. A silicon-based anode material, characterized in that, It is prepared by the method of any one of claims 40-103.

105. Use of the silicon-based anode material of any one of claims 1-39 and 104 in a lithium-ion battery.

106. A lithium-ion battery, characterized in that, It comprises the silicon-based anode material of any one of claims 1-39 and 104.

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