Negative electrode material, preparation method thereof, and lithium ion battery

Abstract

This application relates to a negative electrode material, a preparation method thereof, and a lithium-ion battery. It includes a core and a coating layer located on at least part of the surface of the core. The core includes a silicon-based material, and the coating layer includes a carbon material. The negative electrode material is prepared into a slurry, and a nano particle size and Zeta potential analyzer is used to test the Zeta potential of the slurry. In the Zeta potential test distribution diagram of the slurry, the maximum intensity in the Zeta potential range of -10 mV to 0 mV of the slurry is I1, the maximum intensity in the Zeta potential range of -20 mV to -10 mV is I2, and the maximum intensity in the Zeta potential range of -30 mV to -20 mV is I3. The relationship among I1, I2, and I3 satisfies: 0 ≤ I1 / I2 ≤ 1.0, 0 < I2 / I3 ≤ 2.0.

Description

Technical Field

[0001] The present invention relates to the technical field of anode materials, and particularly to anode materials, their preparation methods, and lithium-ion batteries. Background Art

[0002] Silicon-based anode materials are one of the most critical materials for high-energy-density lithium-ion batteries. However, existing silicon-based materials have problems such as large expansion and poor rate performance, which affect the wide application of silicon-based anode materials in lithium batteries. Therefore, how to suppress expansion and improve the cycle rate performance of silicon-based materials is a prerequisite for the wide application of silicon-based materials.

[0003] In the process of designing and improving silicon-based anode materials, a coating layer is usually provided on the surface of the silicon-based anode materials. Existing coating layers are mostly single carbon materials, which can improve the volume expansion and conductivity of silicon-based materials to a certain extent. However, the current coating layers still have many defects, resulting in limited improvement in the electrochemical performance of silicon-based materials.

[0004] Therefore, developing an anode material with excellent cycle performance, low volume expansion effect, and excellent rate performance and its preparation method is still a technical problem in the field. Summary of the Invention

[0005] The purpose of this application is to provide anode materials, their preparation methods, and lithium-ion batteries, which can reduce the volume expansion of the anode materials, improve the rate performance and cycle performance of the anode materials.

[0006] In a first aspect, an embodiment of this application provides an anode material, including a core and a coating layer located on at least a part of the surface of the core. The core includes a silicon-based material, and the coating layer includes a carbon material;

[0007] Prepare the anode material into a slurry, and use a nano particle size and Zeta potential analyzer to perform Zeta potential tests on the slurry. In the Zeta potential test distribution diagram of the slurry, the maximum intensity of the slurry in the Zeta potential range of -10 mV to 0 mV is I 1 , the maximum intensity of the slurry in the Zeta potential range of -20 mV to -10 mV is I 2 , the maximum intensity of the slurry in the Zeta potential range of -30 mV to -20 mV is I 3 , and the relationship among I 1 , I 2 , and I 3 satisfies: 0 ≤ I 1 / I 2 ≤ 1.0, 0 < I 2 / I 3 ≤ 2.0.

[0008] In some embodiments, the silicon-based material includes at least one of elemental silicon, silicon oxide material, and silicate.

[0009] In some embodiments, the silicon-based material includes silicon oxide material, and the silicon oxide material includes SiO x , where 0 ≤ x < 2.

[0010] In some embodiments, the silicon-based material includes silicate, and the silicate includes at least one of lithium silicate, magnesium silicate, aluminum silicate, magnesium aluminum silicate, lithium magnesium silicate, calcium silicate, magnesium calcium silicate, lithium calcium silicate, and lithium aluminum silicate.

[0011] In some embodiments, the negative electrode material further includes a doping element, and the doping element is distributed in the core.

[0012] In some embodiments, the negative electrode material further includes a doping element, and the doping element includes at least one of nitrogen element and sulfur element.

[0013] In some embodiments, the negative electrode material contains nitrogen element, and the content of the nitrogen element in the negative electrode material is 0 to 500 ppm.

[0014] In some embodiments, the negative electrode material contains sulfur element, and the content of the sulfur element in the negative electrode material is 50 ppm to 6000 ppm.

[0015] In some embodiments, the carbon material includes at least one of graphite, hard carbon, soft carbon, amorphous carbon, diamond-like carbon, carbon fiber, and carbide.

[0016] In some embodiments, the material of the coating layer further includes at least one of sulfide, nitride, metal oxide, phosphate, and silicate.

[0017] In some embodiments, the material of the coating layer further includes sulfide, and the sulfide includes at least one of carbon disulfide and organic sulfide.

[0018] In some embodiments, the material of the coating layer further includes nitride, and the nitride includes at least one of silicon nitride, pyrrole, and pyridine.

[0019] In some embodiments, the material of the coating layer further includes metal oxide, and the metal oxide includes at least one of titanium oxide, aluminum oxide, magnesium oxide, lithium oxide, zirconium oxide, cobalt oxide, and vanadium oxide.

[0020] In some embodiments, the material of the coating layer further includes phosphate, and the phosphate includes at least one of lithium phosphate, aluminum phosphate, lithium aluminum phosphate, lithium aluminum titanium phosphate, magnesium phosphate, lithium magnesium phosphate, calcium phosphate, lithium calcium phosphate, lithium dihydrogen phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, and ammonium phosphate.

[0021] In some embodiments, the material of the coating layer further includes silicate, and the silicate includes at least one of lithium silicate, magnesium silicate, aluminum silicate, magnesium aluminum silicate, lithium magnesium silicate, calcium silicate, magnesium calcium silicate, lithium calcium silicate, and lithium aluminum silicate.

[0022] In some embodiments, the pH of the slurry is 8.0 to 10.5.

[0023] In some embodiments, the median particle size of the core is 2.5 μm to 10.0 μm.

[0024] In some embodiments, the thickness of the coating layer is 20 nm to 700 nm.

[0025] In some embodiments, the median particle size of the negative electrode material is 3 μm to 10 μm.

[0026] In some embodiments, based on the mass of the negative electrode material being 100%, the mass proportion of the carbon material is 0.5 wt% to 10 wt%.

[0027] In some embodiments, the specific surface area of the negative electrode material is 1.0 m 2 / g to 5.0 m 2 / g.

[0028] In some embodiments, the pH of the negative electrode material is 6.5 to 10.5.

[0029] In some embodiments, the tap density of the negative electrode material is 0.5 g / cm 3 ~2.0 g / cm 3 。

[0030] In some embodiments, the mass proportion of water in the negative electrode material is 0.01% to 0.50%.

[0031] In a second aspect, an embodiment of the present application provides a method for preparing a negative electrode material, including the following steps:

[0032] Immerse the silicon raw material in an organic solvent for impregnation treatment, and dry the material obtained from the impregnation treatment to obtain a precursor;

[0033] The precursor is subjected to chemical vapor deposition using a gaseous carbon source. During the chemical vapor deposition process, the precursor is coated with a solid-phase coating agent and / or a liquid-phase coating agent to obtain a negative electrode material. The negative electrode material includes a core and a coating layer located on at least a part of the surface of the core. The core includes a silicon-based material, and the coating layer includes a carbon material deposited from the gaseous carbon source and a carbon material deposited from the solid-phase coating agent and / or the liquid-phase coating agent.

[0034] In some embodiments, before immersing the silicon raw material in the organic solvent, the method further includes: mixing the silicon raw material and a dopant and performing a first heat treatment.

[0035] In some embodiments, the silicon raw material includes at least one of silicon monoxide, elemental silicon, silicon dioxide, and silicate.

[0036] In some embodiments, the dopant includes at least one of magnesium, aluminum, lithium, titanium, phosphorus, copper, tin, gallium, germanium, indium, molybdenum, platinum, cerium, and rhodium.

[0037] In some embodiments, the mass ratio of the silicon raw material to the dopant is 1:(0.01 - 0.1).

[0038] In some embodiments, the temperature of the first heat treatment is 500°C - 1300°C.

[0039] In some embodiments, the heat preservation time of the first heat treatment is 2h - 24h.

[0040] In some embodiments, the first heat treatment is performed in an inert gas atmosphere, and the inert gas includes at least one of helium, neon, argon, krypton, and xenon.

[0041] In some embodiments, after the first heat treatment, the method further includes: classifying and purifying the material obtained from the first heat treatment.

[0042] In some embodiments, after the first heat treatment, the method further includes: classifying and purifying the material obtained from the first heat treatment, and the classification includes pneumatic classification.

[0043] In some embodiments, after the first heat treatment, the method further includes: classifying and purifying the material obtained from the first heat treatment, and the median particle size of the classified material is 2μm - 10μm.

[0044] In some embodiments, before subjecting the precursor to chemical vapor deposition using a gaseous carbon source, the method further includes: spray-drying a mixture containing the precursor, an auxiliary agent, and a solvent, and performing a second heat treatment on the material obtained from the spray-drying.

[0045] In some embodiments, the adjuvant includes at least one of carbon nanotubes, sucrose, pitch, conductive carbon black, nitrides, and sulfides.

[0046] In some embodiments, the adjuvant includes nitrides, and the nitrides include at least one of pyrrole, pyridine, amino acids, and amines.

[0047] In some embodiments, the adjuvant includes sulfides, and the sulfides include at least one of carbon disulfide and organic sulfides.

[0048] In some embodiments, the solvent includes at least one of deionized water and alcohol solvents.

[0049] In some embodiments, the mass ratio of the precursor to the adjuvant is 1:(0.005 - 0.1).

[0050] In some embodiments, the mass percentage of the precursor in the mixture containing the precursor, adjuvant, and solvent is 20% - 50%.

[0051] In some embodiments, the temperature of the secondary heat treatment is 400°C - 1000°C.

[0052] In some embodiments, the heat preservation time of the secondary heat treatment is 2h - 24h.

[0053] In some embodiments, the secondary heat treatment is carried out in a protective gas atmosphere, and the protective gas includes at least one of nitrogen, helium, argon, neon, and krypton.

[0054] In some embodiments, before spray - drying the mixture containing the precursor, adjuvant, and solvent, it further includes: stirring and ultrasonic - treating the mixture containing the precursor, adjuvant, and solvent.

[0055] In some embodiments, before spray - drying the mixture containing the precursor, adjuvant, and solvent, it further includes: stirring and ultrasonic - treating the mixture containing the precursor, adjuvant, and solvent, and the rotation speed of the stirring treatment is 2000 r / min - 3000r / min.

[0056] In some embodiments, before spray - drying the mixture containing the precursor, adjuvant, and solvent, it further includes: stirring and ultrasonic - treating the mixture containing the precursor, adjuvant, and solvent, and the time of the stirring treatment is 12h - 36h.

[0057] In some embodiments, the spray - drying includes vacuum spray - drying.

[0058] In some embodiments, the spray drying includes vacuum spray drying, and the pressure of the vacuum spray drying is 0.1 Pa to 1000 Pa.

[0059] In some embodiments, the temperature of the spray drying is 100 °C to 150 °C.

[0060] In some embodiments, the spray drying is carried out under stirring conditions.

[0061] In some embodiments, the spray drying is carried out under stirring conditions, and the rotation speed of the stirring conditions is 500 r / min to 1000 r / min.

[0062] In some embodiments, after the secondary heat treatment, it further includes: the step of screening the material obtained by the secondary heat treatment.

[0063] In some embodiments, the organic solvent includes at least one of ethanol, acetone, N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, and ethylene glycol dimethyl ether.

[0064] In some embodiments, the time of the impregnation treatment is 2 h to 10 h.

[0065] In some embodiments, the drying treatment is carried out under vacuum conditions, and the pressure of the drying treatment is 0.1 Pa to 1000 Pa.

[0066] In some embodiments, the temperature of the drying treatment is 45 °C to 80 °C.

[0067] In some embodiments, the time of the drying treatment is 3 h to 48 h.

[0068] In some embodiments, before the vapor deposition of the precursor using a gaseous carbon source, it further includes: performing radio frequency plasma treatment on the precursor.

[0069] In some embodiments, before the vapor deposition of the precursor using a gaseous carbon source, it further includes: performing radio frequency plasma treatment on the precursor, and the time of the radio frequency plasma treatment is 5 min to 30 min.

[0070] In some embodiments, the gaseous carbon source includes at least one of methane, ethane, ethylene, acetylene, propyne, propylene, propane, and formaldehyde.

[0071] In some embodiments, the flow rate of the gaseous carbon source is 200 mL / min to 5000 mL / min.

[0072] In some embodiments, the deposition temperature of the vapor deposition is 400 °C to 1200 °C.

[0073] In some embodiments, the deposition time of the chemical vapor deposition is 1 h to 24 h.

[0074] In some embodiments, the deposition pressure of the chemical vapor deposition is 10 kPa to 0.1 MPa.

[0075] In some embodiments, an auxiliary carrier gas is further added during the chemical vapor deposition process.

[0076] In some embodiments, an auxiliary carrier gas is further added during the chemical vapor deposition process, and the auxiliary carrier gas includes H 2 , CO 2 , SO 2 , NH 3 and at least one of Ar.

[0077] In some embodiments, an auxiliary carrier gas is further added during the chemical vapor deposition process, and the flow rate of the auxiliary carrier gas is 500 mL / min to 5000 mL / min.

[0078] In some embodiments, an auxiliary carrier gas is further added during the chemical vapor deposition process, and the flow rate ratio of the gaseous carbon source to the auxiliary carrier gas is (3 to 95):(5 to 70).

[0079] In some embodiments, the chemical vapor deposition is carried out in a deposition chamber of a chemical vapor deposition apparatus, and the rotation speed of the deposition chamber is 0.1 r / min to 10 r / min.

[0080] In some embodiments, the solid-phase coating agent includes at least one of tetracarboxylic anhydride, copper phthalocyanine, perylene tetracarboxylic dianhydride, solid asphalt, and molybdenum disulfide.

[0081] In some embodiments, the liquid-phase coating agent includes at least one of toluene, methanol, acetonitrile, chloroform, cyclohexane, dichloromethane, tetrahydrofuran, n-butanol, n-propanol, isopropanol, acetone, carbon tetrachloride, and n-hexane.

[0082] In some embodiments, the method further includes: classifying and drying the product of the chemical vapor deposition.

[0083] In some embodiments, the temperature of the drying treatment is 50 °C to 120 °C.

[0084] In some embodiments, the time of the drying treatment is 6 h to 48 h.

[0085] In a third aspect, the present application provides a lithium-ion battery, and the lithium-ion battery includes the negative electrode material described in the first aspect or the negative electrode material prepared by the preparation method of the negative electrode material described in the second aspect.

[0086] Compared with the prior art, the technical solution of the present application has at least the following beneficial effects:

[0087] The negative electrode material provided by the present application includes a core and a coating layer located on the surface of the core. The core includes a silicon-based material, and the coating layer includes a carbon material. The coating layer can effectively isolate the exposure of the core in the electrolyte, reduce the loss of active silicon in the core, and improve the cycling performance of the negative electrode material; after the negative electrode material is made into a slurry, a nano particle size and Zeta potential analyzer is used to test the Zeta potential of the slurry. In the Zeta potential test distribution map of the slurry, I 1 、I 2 and I 3 respectively represent the quantity distributions of the negative electrode material in three different Zeta potential ranges, indicating that the negative electrode material has three major types of charge density states on the surface, reflecting three different types of surface interface structures of the negative electrode material. Among them, the Zeta potential corresponding to I 1 is smaller, indicating that the surface interface charge density of the negative electrode material in this potential region is smaller, and the Zeta potential corresponding to I 3 is larger, indicating that the surface interface charge density of the negative electrode material in this potential region is larger. The Zeta potential corresponding to I 2 is between the Zeta potential corresponding to I 1 and the Zeta potential corresponding to I 3 , indicating that the surface interface charge density of the negative electrode material in this potential region is medium. By controlling the relationship among I 1 , I 2 , and I 3 in the present application to satisfy: 0 ≤ I 1 / I 2 ≤ 1.0, 0 < I 2 / I 3 ≤ 2.0, the surface interface potential distribution of the negative electrode material is reasonable, the charge density is appropriate, which can improve the interfacial reaction of the negative electrode material, improve the ion-electron mass transfer efficiency of the negative electrode material, improve the rate performance of the negative electrode material, reduce the loss of active silicon and the loss of active lithium in the negative electrode material during charge and discharge. Moreover, during the process of preparing the slurry of the negative electrode material, the material particles in the three different Zeta potential regions of the negative electrode material repel each other, regulating the surface interface stability of the negative electrode material, reducing the agglomeration of the negative electrode material, thereby improving the dispersibility of the slurry and reducing gas generation. In addition, by controlling the relationship among I 1 , I 2 , and I 3 of the negative electrode material, the solid-liquid reaction between the surface of the negative electrode material and the electrolyte can be controlled to form a stable SEI interface, reduce the degradation of the electrolyte, inhibit swelling, and thus improve the cycling performance of the negative electrode material. Description of the Drawings

[0088] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0089] Figure 1 Process flow chart of the preparation method of the negative electrode material provided in the embodiment of the present application;

[0090] Figure 2 Zeta potential test distribution diagram of the negative electrode material provided in Embodiment 1 of the present application;

[0091] Figure 3 Zeta potential test distribution diagram of the negative electrode material provided in Embodiment 3 of the present application;

[0092] Figure 4 Zeta potential test distribution diagram of the negative electrode material provided in Embodiment 2 of the present application;

[0093] Figure 5 Zeta potential test distribution diagram of the negative electrode material provided in Embodiment 4 of the present application;

[0094] Figure 6 Zeta potential test distribution diagram of the negative electrode material provided in Embodiment 5 of the present application. Specific embodiments

[0095] In order to better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

[0096] It should be clear that the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work fall within the scope of protection of the present invention.

[0097] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms of "a", "the" and "said" used in the embodiments of the present invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0098] It should be understood that the term " / and" used herein is only a description of the associated relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0099] In a first aspect, the embodiment of the present application provides a negative electrode material, which includes a core and a coating layer located on at least part of the surface of the core. The core includes a silicon-based material, and the coating layer includes a carbon material;

[0100] Prepare the negative electrode material into a slurry, and use a nano particle size and Zeta potential analyzer to measure the Zeta potential of the slurry. In the Zeta potential test distribution diagram of the slurry, the maximum intensity of the slurry in the Zeta potential range of -10 mV to 0 mV is I 1 , and the maximum intensity in the Zeta potential range of -20 mV to -10 mV is I 2 , and the maximum intensity in the Zeta potential range of -30 mV to -20 mV is I 3 , and I 1 、I 2 、I 3 satisfy the following relationship: 0 ≤ I 1 / I 2 ≤ 1.0, 0 < I 2 / I 3 ≤ 2.0.

[0101] In the above solution, the negative electrode material provided by the present application includes a core and a coating layer located on the surface of the core. The core includes a silicon-based material, and the coating layer includes a carbon material. The coating layer can effectively isolate the exposure of the core in the electrolyte, reduce the loss of active silicon in the core, and improve the cycling performance of the negative electrode material; after the negative electrode material is made into a slurry, use a nano particle size and Zeta potential analyzer to measure the Zeta potential of the slurry. In the Zeta potential test distribution diagram of the slurry, I 1 、I 2 and I 3 respectively represent the quantity distributions of the negative electrode material in three different Zeta potential ranges, indicating that the negative electrode material has three major types of charge density states on the surface, reflecting three different types of surface interface structures of the negative electrode material. Among them, the Zeta potential corresponding to I 1 is smaller, indicating that the surface interface charge density of the negative electrode material in this potential region is smaller. The Zeta potential corresponding to I 3 is larger, indicating that the surface interface charge density of the negative electrode material in this potential region is larger. The Zeta potential corresponding to I 2 is between the Zeta potential corresponding to I 1 and the Zeta potential corresponding to I 3 , indicating that the surface interface charge density of the negative electrode material in this potential region is medium. The present application controls the relationship between I 1 、I 2 、I 3 to satisfy: 0 ≤ I 1 / I 2 ≤ 1.0, 0 < I 2 / I 3≤2.0, the surface and interface potential distribution of the negative electrode material is reasonable, the charge density is appropriate, which can improve the interfacial reaction of the negative electrode material, enhance the ion and electron mass transfer efficiency of the negative electrode material, improve the rate performance of the negative electrode material, reduce the loss of active silicon and the loss of active lithium in the negative electrode material during charge and discharge. Moreover, during the process of preparing the slurry of the negative electrode material, the material particles in the three different Zeta potential regions in the negative electrode material repel each other, regulate the surface and interface stability of the negative electrode material, reduce the agglomeration of the negative electrode material, and then improve the dispersibility of the slurry and reduce gas generation. In addition, in this application, by controlling the negative electrode material I 1 、I 2 、I 3 The relationship between them can control the solid-liquid reaction between the surface of the negative electrode material and the electrolyte, form a stable SEI interface, reduce the degradation of the electrolyte, inhibit swelling, and thus improve the cycle performance of the negative electrode material.

[0102] In this application, the surface and interface of the negative electrode material refers to the solid-liquid interface where the solid phase surface of the negative electrode material contacts the solvent in the slurry preparation and the electrolyte in the battery electrochemical reaction. By controlling the surface and interface of the negative electrode material, the dispersibility of the negative electrode material in the preparation of the slurry and the degradation reaction of the negative electrode material with the electrolyte during the electrochemical reaction process can be controlled, thereby affecting the performance of the negative electrode material.

[0103] Specifically, I 1 / I 2 represents the ratio of the negative electrode material with a smaller surface and interface charge density to the negative electrode material with a medium surface and interface charge density. I 1 / I 2 For example, it can be 0, 0.1, 0.3, 0.5, 0.7, 0.8, 0.9 or 1.0, etc., which is not limited here. Within the above-defined range, the surface and interface potential distribution of the negative electrode material can be made reasonable, and the surface and interface of the negative electrode material have diversified characteristics. On the one hand, it can realize solid-liquid regulation during the slurry preparation process of the negative electrode material, inhibit gas generation, and improve the dispersibility of the slurry; on the other hand, in the electrochemical reaction, it can regulate the degradation reaction and deposition mode of the negative electrode material with the electrolyte, stabilize the SEI interface, relieve the volume expansion of the negative electrode material, improve the cycle performance of the negative electrode material, and maximize the electrochemical performance of the negative electrode material. In addition, by controlling the ratio of I 1 / I 2 , the regulation of the surface composition of the negative electrode material can be realized. By regulating the surface of the negative electrode material, a fast ion and electron transport channel can be established, the conductivity of the negative electrode material can be improved, the rate performance of the material can be enhanced, and the loss of active silicon can be reduced. If I 1If the proportion of the corresponding negative electrode material is too large, the rationality of the surface charge ion distribution of the negative electrode material decreases. Then, the proportion of the negative electrode material with a smaller surface interface density in the total negative electrode material is relatively large, and the difference in the surface interface charge density between the negative electrode materials is large, exacerbating the performance difference between the negative electrode material particles and leading to the deterioration of the overall performance of the negative electrode material. It should be noted that when I 1 is 0, it means that there is no zeta potential distribution between -10 mV and 0 mV, that is, there is no corresponding specific surface interface structure in the negative electrode material.

[0104] I 2 / I 3 represents the ratio of the negative electrode material with a medium surface interface charge density to the negative electrode material with a larger surface interface charge density. I 2 / I 3 Specifically, it can be 0.1, 0.3, 0.5, 0.8, 1.0, 1.2, 1.5, 1.8 or 2.0, etc., which is not limited here. Within the above-defined range, the surface interface potential distribution of the negative electrode material can be made reasonable, making the surface interface of the negative electrode material have diversified characteristics. On the one hand, it can achieve solid-liquid regulation during the slurry mixing process of the negative electrode material, inhibit gas generation, and improve the dispersibility of the slurry; on the other hand, in the electrochemical reaction, it can regulate the degradation reaction and deposition mode between the negative electrode material and the electrolyte, stabilize the SEI interface, relieve the volume expansion of the negative electrode material, and improve the cycle performance of the negative electrode material, maximizing the electrochemical performance of the negative electrode material. In addition, by controlling the ratio of I 2 / I 3 , the surface composition of the negative electrode material can be regulated. By establishing a fast ion and electron transport channel through the surface regulation of the negative electrode material, the conductivity of the negative electrode material can be improved, the rate performance of the negative electrode material can be enhanced, and the loss of active silicon can be reduced. If the proportion of the negative electrode material corresponding to I 2 is too large, the surface interface of the negative electrode material tends to be in the low Zeta potential range, resulting in a decrease in the overall surface charge density of the negative electrode material particles, and the negative electrode material tends to settle during the slurry mixing process, which is not conducive to improving the dispersibility of the slurry.

[0105] In some embodiments, the negative electrode material is prepared into a slurry. Specifically, the negative electrode material can be dissolved in deionized water to make the pH of the slurry 8.0 - 10.5, or the negative electrode material and an alkaline substance can be dissolved in deionized water to make the pH of the slurry 8.0 - 10.5 to meet the requirements of zeta potential testing. The alkaline substance can be, for example, lithium hydroxide. The pH of the slurry can specifically be 8.0, 8.5, 9, 9.5, 10 or 10.5, etc., which is not limited here. Preferably, the negative electrode material is dissolved in deionized water to make the pH of the slurry 8.7 - 9.7.

[0106] In some embodiments, the silicon-based material includes at least one of silicon, silicon oxide, and silicate.

[0107] In some embodiments, the silicon-oxygen material includes SiO x (0≤x<2), where x represents the molar ratio of oxygen atoms to silicon atoms is 0 to 2 (excluding 2). Specifically, x can be 0, 0.3, 0.5, 0.8, 1, 1.3, 1.5, or 1.8, etc., which is not limited herein. SiO x can represent a material formed by silicon particles dispersed in SiO 2 or can represent a material having a tetrahedral structural unit, with silicon atoms located at the center of the tetrahedral structural unit and oxygen atoms located at the four vertices of the tetrahedral structural unit.

[0108] In some embodiments, the silicate includes at least one of lithium silicate, magnesium silicate, aluminum silicate, magnesium aluminum silicate, lithium magnesium silicate, calcium silicate, magnesium calcium silicate, lithium calcium silicate, and lithium aluminum silicate.

[0109] In some embodiments, the negative electrode material further includes a doping element, and the doping element is distributed in the inner core.

[0110] In some embodiments, the doping element includes at least one of nitrogen element and sulfur element. On the one hand, the nitrogen element and sulfur element are distributed in the inner core to form doping, improving the conductivity of the negative electrode material; on the other hand, the nitrogen element and sulfur element can modify the surface interface of the inner core, improving the ion-electron mass transfer efficiency of the negative electrode material, improving the rate performance of the negative electrode material, and reducing the loss of active silicon.

[0111] In some embodiments, the content of nitrogen element in the negative electrode material is 0~500ppm. Specifically, it can be 0ppm, 10ppm, 50 ppm, 100 ppm, 200 ppm, 300 ppm, 400 ppm, or 500 ppm, etc. Of course, it can also be other values within the above range, which is not limited herein.

[0112] In some embodiments, the content of sulfur element in the negative electrode material is 50ppm~6000ppm. Specifically, it can be 50ppm, 100 ppm, 1000 ppm, 2000 ppm, 3000 ppm, 4000ppm, 5000 ppm, or 6000 ppm, etc. Of course, it can also be other values within the above range, which is not limited herein.

[0113] In some embodiments, the carbon material includes at least one of graphite, amorphous carbon, diamond-like carbon, carbon fiber, and carbide. It can be understood that diamond-like carbon is a hydrogen-containing amorphous carbon film, and the atomic structure of diamond-like carbon is between H (hydrogen atom) and SP 3Between (diamonds), its properties are similar to those of natural diamonds, with ultra-high hardness, excellent corrosion resistance and anti-wear performance.

[0114] In some embodiments, the amorphous carbon includes soft carbon and hard carbon.

[0115] In some embodiments, the material of the coating layer further includes at least one of sulfides, nitrides, metal oxides, phosphates and silicates.

[0116] In some embodiments, the sulfide includes at least one of carbon disulfide and organic sulfides. The organic sulfide can be, for example, sulfur-containing amino acids, thioethers, thiophenols, thiols, thioaldehydes, thiocarboxylic acids and disulfides, etc.

[0117] In some embodiments, the nitride includes at least one of silicon nitride, pyrrole and pyridine.

[0118] In some embodiments, the metal oxide includes at least one of titanium oxide, aluminum oxide, magnesium oxide, lithium oxide, zirconium oxide, cobalt oxide and vanadium oxide.

[0119] In some embodiments, the phosphate includes at least one of lithium phosphate, aluminum phosphate, lithium aluminum phosphate, lithium aluminum titanium phosphate, magnesium phosphate, lithium magnesium phosphate, calcium phosphate, lithium calcium phosphate, lithium dihydrogen phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate and ammonium phosphate.

[0120] In some embodiments, the silicate includes at least one of lithium silicate, magnesium silicate, aluminum silicate, magnesium aluminum silicate, lithium magnesium silicate, calcium silicate, magnesium calcium silicate, lithium calcium silicate and lithium aluminum silicate.

[0121] In some embodiments, the median particle size of the inner core is 2.5 μm to 10.0 μm, specifically it can be 2.5 μm, 3.0 μm, 4.0 μm, 5.0 μm, 6.0 μm, 7.0 μm, 8.0 μm, 9.0 μm or 10.0 μm, etc. Of course, it can also be other values within the above range, which is not limited here.

[0122] In some embodiments, the thickness of the coating layer is 20 nm to 700 nm, specifically it can be 20 nm, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm or 700 nm, etc. Of course, it can also be other values within the above range, which is not limited here. If the coating layer is too thick, the lithium ion transmission efficiency will decrease, which is not conducive to the high-rate charge and discharge of the negative electrode material and reduces the comprehensive performance of the negative electrode material. If the coating layer is too thin, it is not conducive to increasing the conductivity of the negative electrode material and has a weak performance in suppressing the volume expansion of the negative electrode material, resulting in poor long-cycle performance.

[0123] In some embodiments, the median particle size of the negative electrode material is 3 μm to 10 μm. Specifically, it can be 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc., which is not limited herein. Within the above range, it is beneficial to improve the cycling performance of the negative electrode material.

[0124] In some embodiments, based on the mass of the negative electrode material being 100%, the mass ratio of the carbon material is 0.5 wt% to 10 wt%. Specifically, it can be 0.5 wt%, 1 wt%, 1.5 wt%, 2.5 wt%, 5 wt%, 6.5 wt%, 8 wt%, 10 wt%, etc. Of course, it can also be other values within the above range, which is not limited herein. Preferably, the mass ratio of the carbon material is 2.5 wt% to 8 wt%.

[0125] In some embodiments, the specific surface area of the negative electrode material is 1.0 m 2 / g to 5.0 m 2 / g. Specifically, it can be 1.0 m 2 / g, 2.0 m 2 / g, 3.0 m 2 / g, 4.0 m 2 / g or 5.0 m 2 / g. Of course, it can also be other values within the above range, which is not limited herein. Within the above-defined range, the negative electrode material has an appropriate specific surface area, which is beneficial to improving the capacity and cycling performance of the negative electrode material.

[0126] In some embodiments, the pH of the negative electrode material is 6.5 to 10.5. Specifically, it can be 6.5, 6.8, 7.5, 8.3, 8.6, 9.2, 9.7, 10.0, 10.5, etc. Of course, it can also be other values within the above range, which is not limited herein.

[0127] In some embodiments, the tap density of the negative electrode material is 0.5 g / cm 3 to 2.0 g / cm 3 . Specifically, it can be 0.5 g / cm 3 、1.0 g / cm 3 、1.5 g / cm 3 or 2.0 g / cm 3 etc. Of course, it can also be other values within the above range, which is not limited herein. When the tap density of the negative electrode material is within the above range, it is beneficial to improve the energy density of the lithium-ion battery made of the negative electrode material.

[0128] In some embodiments, the mass percentage of water in the anode material is 0.01% to 0.50%, specifically, it can be 0.01%, 0.05%, 0.10%, 0.20%, 0.30%, 0.40% or 0.50%, etc. Of course, it can also be other values within the above range, which is not limited herein.

[0129] In a second aspect, an embodiment of the present application provides a method for preparing an anode material, as Figure 1 shown, including the following steps:

[0130] Place the silicon raw material in an organic solvent for impregnation treatment, and dry the material obtained from the impregnation treatment to obtain a precursor;

[0131] Perform chemical vapor deposition on the precursor using a gaseous carbon source. During the chemical vapor deposition process, coat the precursor with a solid-phase coating agent and / or a liquid-phase coating agent to obtain an anode material, wherein it includes a core and a coating layer located on at least part of the surface of the core. The core includes a silicon-based material, and the coating layer includes a carbon material deposited from the gaseous carbon source and a carbon material deposited from the solid-phase coating agent and / or the liquid-phase coating agent.

[0132] The method for preparing the anode material provided by the present application pre-places the silicon raw material in an organic solvent for impregnation treatment, and dries the material obtained from the impregnation treatment to obtain a precursor, so that a differentiated adsorption interface is formed on the surface of the precursor. Then, perform chemical vapor deposition on the silicon raw material using a gaseous carbon source. During the chemical vapor deposition process, coat the precursor with a solid-phase coating agent and / or a liquid-phase coating agent to obtain an anode material. During the chemical vapor deposition process, on the one hand, due to the different dissociation efficiencies of different carbon sources at the same temperature and different deposition efficiencies on the surface of the precursor, different types of carbon sources are deposited on the surface of the precursor successively, so that a differentiated deposition can be formed on the surface of the precursor. The carbon material formed by the dissociation of the gaseous carbon source is deposited on the surface of the precursor. At the same time, the carbon material formed by the dissociation of the solid-phase coating agent and / or the liquid-phase coating agent will also be deposited on the surface of the precursor, further enriching the surface and interface of the anode material. Moreover, using the above-mentioned various different carbon materials to deposit on the precursor, the pores formed by the pyrolysis of the carbon material during the deposition process can further enrich the surface and interface of the anode material, realizing the regulation of the surface and interface of the anode material; on the other hand, the surface of the precursor has a differentiated adsorption interface, which makes the deposition efficiency of the carbon source on the precursor different, and can also enrich the surface and interface of the anode material, so that the anode material satisfies: 0 ≤ I 1 / I 2 ≤ 1.0, 0 < I 2 / I 3 ≤ 2.0, which is beneficial to controlling the surface and interface reaction of the anode material and improving the processing performance, rate performance and cycling performance of the anode material.

[0133] The preparation method provided by this solution is introduced in detail below:

[0134] Step S100: Immerse the silicon raw material in an organic solvent, and dry the material obtained from the immersion treatment to obtain a precursor.

[0135] In some embodiments, before immersing the silicon raw material in the organic solvent for impregnation treatment, it further includes: mixing the silicon raw material and a dopant and then performing a first heat treatment.

[0136] By adding a dopant to the silicon raw material to dope the silicon raw material, it can enrich the outer surface of the silicon raw material, which is beneficial to realizing the regulation of the surface and interface of the negative electrode material. At the same time, the presence of the dopant is beneficial to improving the conductivity of the negative electrode material and enhancing the first efficiency of the negative electrode material.

[0137] In some embodiments, the silicon raw material includes at least one of silicon monoxide, elemental silicon, silicon dioxide, and silicate. Exemplarily, the silicate includes at least one of lithium silicate, magnesium silicate, aluminum silicate, magnesium aluminum silicate, lithium magnesium silicate, calcium silicate, magnesium calcium silicate, lithium calcium silicate, and lithium aluminum silicate.

[0138] In some embodiments, the dopant includes at least one of magnesium, aluminum, lithium, titanium, phosphorus, copper, tin, gallium, germanium, indium, molybdenum, platinum, rhodium, and ruthenium. It can be understood that the dopant can be a simple substance formed by the above elements or a compound formed by at least two elements, or a mixture of the above simple substances and compounds. This application does not make any restrictions here.

[0139] In some embodiments, the mass ratio of the silicon raw material to the dopant is 1:(0.01~0.1). Specifically, it can be 1:0.01, 1:0.03, 1:0.05, 1:0.08, or 1:0.1, etc. Of course, it can also be other values within the above range, and no limitation is made here.

[0140] In some embodiments, the temperature of the first heat treatment is 500°C~1300°C. Specifically, it can be 500°C, 600°C, 700°C, 800°C, 900°C, 1100°C, 1200°C, or 1300°C, etc. Of course, it can also be other values within the above range, and no limitation is made here.

[0141] In some embodiments, the heat preservation time of the first heat treatment is 2h~24h. Specifically, it can be 2h, 3h, 5h, 8h, 10h, 12h, 15h, 18h, 20h, or 24h, etc. Of course, it can also be other values within the above range, and no limitation is made here.

[0142] In some embodiments, the first heat treatment is carried out in a protective gas atmosphere, and the protective gas includes at least one of helium, neon, argon, krypton, and xenon.

[0143] In some embodiments, before the first heat treatment of the silicon raw material and the dopant, it further includes ball milling the mixture of the silicon raw material and the dopant so that the silicon raw material and the dopant are fully mixed.

[0144] In some embodiments, the ball milling time is 6 h to 24 h, specifically it can be 6 h, 8 h, 10 h, 12 h, 15 h, 18 h, 20 h or 24 h, etc. Of course, it can also be other values within the above range, which are not limited herein.

[0145] In some embodiments, after the first heat treatment, it further includes: classifying and purifying the material obtained from the first heat treatment. It can be understood that classifying the material obtained from the first heat treatment can control the particle size range of the silicon raw material. By controlling the particle size of the silicon raw material, the specific surface area and the outer surface of the silicon raw material can be effectively regulated, which is beneficial to controlling the deposition efficiency of subsequent chemical vapor deposition on the silicon raw material and is beneficial to constructing a diversified surface of the negative electrode material; then performing purification treatment to form a differential adsorption interface on the outer surface of the silicon raw material, which is beneficial to forming differential deposition of subsequent chemical vapor deposition on the silicon raw material, thereby regulating the surface and interface of the negative electrode material.

[0146] In some embodiments, the classification includes air classification treatment.

[0147] In some embodiments, the median particle size of the classified material is 2 μm to 10 μm, specifically it can be 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, etc. Of course, it can also be other values within the above range, which are not limited herein. Within the above limited range, by classifying the material obtained from the first heat treatment, the particle size of the silicon raw material is regulated, thereby regulating the specific surface area of the silicon raw material and improving the deposition efficiency of the negative electrode material.

[0148] In some embodiments, the organic solvent includes at least one of ethanol, acetone, N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide and ethylene glycol dimethyl ether;

[0149] In some embodiments, the impregnation treatment time is 2 h to 10 h, specifically it can be 2 h, 3 h, 5 h, 7 h, 9 h or 10 h, etc. Of course, it can also be other values within the above range, which are not limited herein.

[0150] In some embodiments, the drying treatment is carried out under vacuum conditions, and the pressure of the drying treatment is 0.1 Pa to 1000 Pa, specifically it can be 0.1 Pa, 0.5 Pa, 1 Pa, 10 Pa, 50 Pa, 100 Pa, 300 Pa, 500 Pa, 800 Pa or 1000 Pa, etc. Of course, it can also be other values within the above range, which are not limited herein.

[0151] In some embodiments, the temperature of the drying treatment is 45°C to 80°C, specifically, it can be 45°C, 50°C, 55°C, 60°C, 68°C, 70°C, 73°C, 78°C, 80°C, etc. Of course, it can also be other values within the above range, which are not limited herein.

[0152] In some embodiments, the time of the drying treatment is 3h to 48h, specifically, it can be 3h, 8h, 15h, 20h, 25h, 30h, 38h, 42h, 48h, etc. Of course, it can also be other values within the above range, which are not limited herein.

[0153] Step S200: Perform chemical vapor deposition on the precursor using a gaseous carbon source. During the chemical vapor deposition process, coat the precursor with a solid-phase coating agent and / or a liquid-phase coating agent to obtain a negative electrode material, wherein the negative electrode material includes a core and a coating layer located on at least a part of the surface of the core. The core includes a silicon-based material, and the coating layer includes a carbon material deposited from the gaseous carbon source and a carbon material deposited from the solid-phase coating agent and / or the liquid-phase coating agent.

[0154] In some embodiments, before performing chemical vapor deposition on the precursor using a gaseous carbon source, it further includes: spray-drying a mixture containing the precursor, an auxiliary agent, and a solvent, and subjecting the material obtained by spray-drying to a secondary heat treatment.

[0155] In some embodiments, the precursor, the auxiliary agent, and the solvent are mixed to obtain a mixture containing the precursor, the auxiliary agent, and the solvent. In the present application, the liquid-phase method is used to mix the precursor and the auxiliary agent and perform spray-drying, which can make the auxiliary agent and the precursor fully and uniformly mixed. After spray-drying, a secondary heat treatment is performed. On the one hand, the auxiliary agent is fixed on the surface of the precursor, and during the subsequent chemical vapor deposition process, a conductive network can be formed, which can improve the conductivity of the negative electrode material; on the other hand, through the secondary heat treatment, the auxiliary agent forms a preliminary coating on the surface of the precursor, regulating the deposition interface of the precursor, which is beneficial to improving the deposition efficiency of the subsequent gaseous carbon source, and further enriching the surface and interface of the negative electrode material.

[0156] In some embodiments, the auxiliary agent includes at least one of carbon nanotubes, sucrose, pitch, conductive carbon black, nitrides, and sulfides. The addition of the above auxiliary agent can, on the one hand, improve the conductivity of the negative electrode material, and on the other hand, the addition of the auxiliary agent to the precursor can enrich the surface and interface of the precursor, realizing the regulation of the surface and interface of the negative electrode material, and improving the rate performance and cycle performance of the negative electrode material.

[0157] In some embodiments, the nitrides include at least one of pyrrole, pyridine, amino acids, and amine substances. Exemplarily, the amine substances include proteins and nucleic acids, etc.

[0158] In some embodiments, the sulfide includes at least one of carbon sulfide and organic sulfide. The organic sulfide can be, for example, sulfur-containing amino acids, thioethers, thiophenols, thiols, thioaldehydes, thiocarboxylic acids, and disulfides, etc.

[0159] In some embodiments, the solvent includes at least one of deionized water and alcohol solvents. Exemplarily, the alcohol solvent can be, for example, methanol, ethanol, and propanol, etc.

[0160] In some embodiments, the mass ratio of the precursor to the auxiliary agent is 1:(0.005~0.1), specifically, it can be 1:0.005, 1:0.01, 1:0.03, 1:0.05, 1:0.08, or 1:0.1, etc. Of course, it can also be other values within the above range, which are not limited herein.

[0161] In some embodiments, the mass percentage of the precursor in the mixture containing the precursor, the auxiliary agent, and the solvent is 20%~50%, specifically, it can be 20%, 25%, 30%, 35%, 40%, 45%, or 50%, etc. Of course, it can also be other values within the above range, which are not limited herein.

[0162] In some embodiments, the temperature of the secondary heat treatment is 400°C~1000°C, specifically, it can be 400°C, 500°C, 600°C, 700°C, 800°C, 900°C, or 1000°C, etc. Of course, it can also be other values within the above range, which are not limited herein.

[0163] In some embodiments, the heat preservation time of the secondary heat treatment is 2h~24h, specifically, it can be 2h, 3h, 5h, 8h, 10h, 12h, 15h, 18h, 20h, or 24h, etc. Of course, it can also be other values within the above range, which are not limited herein.

[0164] In some embodiments, before spray-drying the mixture containing the precursor, the auxiliary agent, and the solvent, it further includes: stirring and ultrasonic treating the mixture containing the precursor, the auxiliary agent, and the solvent, so that the precursor and the auxiliary agent are fully mixed, which is beneficial to forming a rich surface and interface.

[0165] In some embodiments, the rotation speed of the stirring treatment is 2000r / min~3000r / min, specifically, it can be 2000r / min, 2100 r / min, 2200 r / min, 2300 r / min, 2400 r / min, 2500 r / min, 2600 r / min, 2700r / min, 2800 r / min, 2900 r / min, or 3000 r / min, etc. Of course, it can also be other values within the above range, which are not limited herein.

[0166] In some embodiments, the stirring treatment time is 12 h to 36 h, specifically it can be 12 h, 18 h, 20 h, 25 h, 28 h, 32 h, 34 h or 36 h, etc. Of course, it can also be other values within the above range, which are not limited herein.

[0167] In some embodiments, spray drying includes vacuum spray drying.

[0168] In some embodiments, the pressure of vacuum spray drying is 0.1 Pa to 1000 Pa, specifically it can be 0.1 Pa, 1 Pa, 10 Pa, 50 Pa, 100 Pa, 300 Pa, 500 Pa, 800 Pa or 1000 Pa, etc. Of course, it can also be other values within the above range, which are not limited herein.

[0169] In some embodiments, the temperature of spray drying is 100 °C to 150 °C, specifically it can be 100 °C, 107 °C, 115 °C, 125 °C, 130 °C, 135 °C, 140 °C, 145 °C or 150 °C, etc. Of course, it can also be other values within the above range, which are not limited herein.

[0170] In some embodiments, spray drying is carried out under stirring conditions.

[0171] In some embodiments, the rotation speed of the stirring conditions is 500 r / min to 1000 r / min, specifically it can be 500 r / min, 600 r / min, 700 r / min, 800 r / min, 900 r / min or 1000 r / min, etc. Of course, it can also be other values within the above range, which are not limited herein.

[0172] In some embodiments, the secondary heat treatment is carried out in a protective gas atmosphere, and the protective gas includes at least one of nitrogen, helium, argon, neon and krypton;

[0173] In some embodiments, after the secondary heat treatment, it further includes: the step of screening the material obtained from the secondary heat treatment.

[0174] In some embodiments, before the vapor deposition of the precursor using a gaseous carbon source, it further includes: performing radio frequency plasma (RF) treatment on the precursor to clean the precursor, reduce the specific surface area of the precursor, which is beneficial to improving the deposition efficiency of subsequent vapor deposition, and improving the expansion performance and cycle performance of the anode material.

[0175] In some embodiments, the time of radio frequency plasma treatment is 5 min to 30 min. Specifically, it can be 5 min, 10 min, 15 min, 20 min, 25 min or 30 min, etc. Of course, it can also be other values within the above range, which are not limited herein. Within the above range, the impurities on the surface of the precursor can be removed, the specific surface area of the precursor can be reduced, and at the same time, the precursor can have a rich surface and interface.

[0176] In some embodiments, the raw materials of the gaseous carbon source include at least one of methane, ethane, ethylene, acetylene, propyne, propylene, propane and formaldehyde. Preferably, the raw materials of the gaseous carbon source include two, three or four of methane, ethane, ethylene, acetylene, propyne, propylene, propane and formaldehyde. Different gaseous carbon sources can have different dissociation efficiencies and deposition efficiencies under the action of the same temperature of chemical vapor deposition, which is beneficial to enrich the surface and interface of the negative electrode material and realize the regulation of the surface and interface of the negative electrode material.

[0177] In some embodiments, the flow rate of the gaseous carbon source is 200 mL / min to 5000 mL / min. Specifically, it can be 200 L / min, 500 L / min, 1000 L / min, 2000 L / min, 3000 L / min, 4000 L / min or 5000 L / min, etc. Of course, it can also be other values within the above range, which are not limited herein.

[0178] In some embodiments, the deposition temperature of chemical vapor deposition is 400 °C to 1200 °C. Specifically, it can be 400 °C, 500 °C, 600 °C, 700 °C, 800 °C, 900 °C, 1000 °C, 1100 °C or 1200 °C, etc. Of course, it can also be other values within the above range, which are not limited herein. Controlling the deposition temperature within the above range can control the cracking efficiency of the gaseous carbon source, thereby regulating the deposition efficiency of the gaseous carbon source on the surface of the negative electrode active material; at the same time, it can also control the volatilization efficiency of the solid-phase coating agent and the liquid-phase coating agent. Moreover, controlling the deposition temperature within this temperature range can ensure that the size of the silicon grains is controlled within a certain range, and at the same time, it can also ensure the carbonization degree of the negative electrode material, reduce the proportion of C-H bonds in the negative electrode material, and improve the conductivity of the carbon coating layer, thereby improving the conductivity of the negative electrode material.

[0179] In some embodiments, the deposition time of chemical vapor deposition is 1 h to 24 h. Specifically, the deposition time of chemical vapor deposition can be 1 h, 3 h, 5 h, 8 h, 10 h, 12 h, 15 h, 18 h, 20 h or 24 h, etc., which are not limited herein. It can be understood that if the deposition time of chemical vapor deposition is too long, it is easy to cause the coating layer to be too thick; if the deposition time of chemical vapor deposition is too short, it is easy to cause the coating layer to be too thin. Controlling the deposition time within the above range can control the thickness of the coating layer, which is beneficial to controlling the thickness of the coating layer within an ideal range.

[0180] In some embodiments, the deposition pressure of chemical vapor deposition is 10 KPa to 0.1 MPa, specifically, it can be 10 KPa, 20 KPa, 30 KPa, 40 KPa, 50 KPa, 60 KPa, 70 KPa, 80 KPa, 90 KPa or 0.1 MPa, etc., which is not limited herein. Controlling the deposition pressure within the above range can control the densification of the coating layer, so that the coating layer has good densification, improve the stability of the negative electrode material, and thus enhance the cycling performance of the negative electrode material.

[0181] In some embodiments, an auxiliary carrier gas is further added during the chemical vapor deposition process. It can be understood that the auxiliary carrier gas can bring the gaseous carbon source into the chemical vapor deposition furnace for chemical vapor deposition. At the same time, the solid-phase coating agent and / or the liquid-phase coating agent can be deposited into the coating layer during the deposition process to perform surface modification on the coating layer of the negative electrode material, so as to achieve surface interface optimization, further enrich the surface and interface of the negative electrode material, and realize the regulation of the material surface and interface; at the same time, the auxiliary carrier gas can also accelerate the cracking of the gaseous carbon source and improve the cracking rate of the gaseous carbon source and the deposition rate of chemical vapor deposition; moreover, by means of the auxiliary carrier gas, the carbon chain terminal structure can be increased, so that different types of carbon materials are deposited on the surface of the negative electrode material to optimize the pore environment of the negative electrode material.

[0182] In some embodiments, the auxiliary carrier gas includes H 2 , SO 2 , CO 2 , NH 3 and at least one of Ar.

[0183] In some embodiments, the flow rate of the auxiliary carrier gas is 500 mL / min to 5000 mL / min, specifically, it can be 500 L / min, 1000 L / min, 2000 L / min, 3000 L / min, 4000 L / min or 5000 L / min, etc. Of course, it can also be other values within the above range, which is not limited herein.

[0184] In some embodiments, the flow rate ratio of the gaseous carbon source to the auxiliary carrier gas is (3 to 95):(5 to 70), specifically, it can be 3:5, 10:20, 30:25, 40:10, 50:35, 60:50, 80:62 or 95:70, etc. Of course, it can also be other values within the above range, which is not limited herein.

[0185] In some embodiments, the vapor deposition is carried out in the deposition chamber of a vapor deposition apparatus. The rotation speed of the deposition chamber is 0.1 r / min to 10 r / min, specifically, it can be 0.1 r / min, 0.5 r / min, 1 r / min, 2 r / min, 3 r / min, 4 r / min, 5 r / min, 6 r / min, 7 r / min, 8 r / min, 9 r / min or 10 r / min, etc. Of course, it can also be other values within the above range, which are not limited herein. Controlling the rotation speed of the deposition chamber within the above range is beneficial to improving the uniformity of deposition coating between the negative electrode material particles.

[0186] In some embodiments, the solid-phase coating agent includes at least one of tetracarboxylic anhydride, copper phthalocyanine, perylene tetracarboxylic dianhydride, solid asphalt, and molybdenum disulfide. It can be understood that the solid-phase coating agent can be placed in the front end of the vapor deposition apparatus in advance, and then vapor deposition is carried out. During the vapor deposition process, the solid-phase coating agent is carbonized and coated on the surface of the precursor by using a gaseous carbon source and an optional auxiliary carrier gas.

[0187] In some embodiments, the liquid-phase coating agent includes at least one of toluene, methanol, acetonitrile, chloroform, cyclohexane, dichloromethane, tetrahydrofuran, n-butanol, n-propanol, isopropanol, acetone, carbon tetrachloride, and n-hexane. It can be understood that the liquid-phase coating agent and the precursor can be mixed in advance, and the mixture obtained is placed inside the vapor deposition apparatus, and then vapor deposition is carried out. During the vapor deposition process, the liquid-phase coating agent is carbonized and coated on the surface of the precursor.

[0188] In some embodiments, the method for preparing the negative electrode material further includes classifying and drying the reaction product of the vapor deposition.

[0189] It can be understood that classifying the reaction product of the vapor deposition can reduce the agglomeration of the negative electrode material powder, and at the same time is beneficial to controlling the median particle size of the negative electrode material within the preferred range. Drying the reaction product of the vapor deposition can remove the moisture in the negative electrode material, thereby being beneficial to improving the electrochemical performance of the negative electrode material.

[0190] In some embodiments, the temperature of the drying treatment is 50°C to 120°C, specifically, it can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 110°C or 120°C, etc. Of course, it can also be other values within the above range, which are not limited herein.

[0191] In some embodiments, the time of the drying treatment is 6 h to 48 h, specifically, it can be 6 h, 12 h, 15 h, 18 h, 20 h, 24 h, 30 h, 36 h, 40 h, 45 h or 48 h, etc. Of course, it can also be other values within the above range, which are not limited herein.

[0192] In a third aspect, the present application provides a lithium-ion battery, which includes the negative electrode material described in the first aspect or the negative electrode material prepared by the preparation method of the negative electrode material described in the second aspect.

[0193] The embodiments of the present application will be further described below by way of multiple examples. Among them, the embodiments of the present application are not limited to the following specific examples. Within the scope of the unchanged main rights, appropriate changes can be made for implementation.

[0194] Example 1

[0195] (1) 1000 g of silicon monoxide (median particle size is 5.0 μm) was rinsed with deionized water for 30 min, then infiltrated with ethanol for 3 h, and then placed in a vacuum drying oven. When the pressure in the oven dropped to 500 Pa, heating and drying were started. The drying temperature was 100 °C and the drying time was 24 h.

[0196] (2) 1000 g of the material obtained in step (1), 10 g of carbon nanotubes and 50 g of sucrose were mixed and dissolved in 5000 ml of deionized water, and at the same time, stirring and ultrasonic treatment were carried out for 6 h, and the stirring speed was 3000 r / min. The obtained material was spray-dried at 120 °C, and a stirrer with a speed of 1000 r / min was used for stirring during the spray-drying process. The spray-dried material was heat-treated under argon, the heat-treatment temperature was 1000 °C, and the treatment time was 18 h.

[0197] (3) After the material obtained in step (2) was simply broken up, it was first subjected to radio frequency plasma treatment for 15 min in an Ar gas atmosphere. Then the sample was placed in the deposition chamber of a chemical vapor deposition furnace. With the chamber rotation speed of 5 r / min, methane, acetylene and ethylene gases with a volume ratio of 1:1:1 were passed into the deposition chamber as the gas-phase carbon source. Perylene tetracarboxylic dianhydride (PTCDA) was placed at the front end of the chemical vapor deposition furnace as the solid-phase coating agent. The pressure in the deposition chamber was regulated through a pressure valve. After the vacuum in the reaction chamber was evacuated, Ar was introduced at a rate of 1000 mL / min as the auxiliary carrier gas, and then chemical vapor deposition was carried out at 450 °C for 10 h. Among them, the flow ratio of the gas-phase carbon source to Ar was 1:1, and the deposition pressure was 0.05 MPa.

[0198] (4) The sample obtained in step (3) was classified, vacuum-dried at 100 °C for 24 h, and then the negative electrode material was obtained.

[0199] The negative electrode material prepared in this example includes a core and a carbon coating layer located on at least part of the surface of the core. The core includes elemental silicon, silicon oxide and silicate.

[0200] Dissolve 20 mg of the anode material in 10 ml of deionized water to form a slurry. The pH of the slurry is 9.20. Use a nano particle size and Zeta potential analyzer to test the Zeta potential of the slurry. In the Zeta potential test distribution diagram of the slurry, as Figure 2 shown, the maximum intensity of the slurry in the Zeta potential range of -10 mV to 0 mV is I 1 = 6071.98, the maximum intensity in the Zeta potential range of -20 mV to -10 mV is I 2 = 45457.20, the maximum intensity in the Zeta potential range of -30 mV to -20 mV is I 3 = 52291.32, and I 1 / I 2 = 0.13, I 2 / I 3 = 0.87.

[0201] The median particle size of the anode material is 5.27 μm, the sulfur content m S = 27 ppm of the anode material, the nitrogen content m N = 4587 ppm of the anode material, the tapped density is 0.98 g / cm 3 , the mass content of carbon element in the anode material is 5.27%, and the mass content of water is 0.07%.

[0202] Example 2

[0203] (1) Rinse 1000 g of silicon monoxide (median particle size is 5.0 μm) with deionized water for 30 min, then soak it with ethanol for 24 h, and then put it into a vacuum drying oven. When the pressure in the oven drops to 500 Pa, start heating and drying. The drying temperature is 80 °C and the drying time is 24 h.

[0204] (2) Mix and dissolve 1000 g of the material obtained in step (1), 10 g of carbon nanotubes and 50 g of sucrose in 5000 ml of deionized water, and at the same time carry out stirring and ultrasonic treatment for 6 h. The stirring speed is 3000 r / min. Spray dry the obtained material at 120 °C. During the spray drying process, use a stirrer with a speed of 1000 r / min for stirring. Heat-treat the spray-dried material under argon at a heat treatment temperature of 1000 °C for 18 h.

[0205] (3) After simply dispersing the material obtained in step (2), under an Ar atmosphere, first perform radio frequency plasma treatment for 15 min. Then place the sample into the deposition chamber of the chemical vapor deposition furnace. With the chamber rotation speed of 5 r / min, introduce methane gas into the deposition chamber as the gas-phase carbon source. Place copper phthalocyanine as the solid-phase coating agent at the front end of the chemical vapor deposition furnace. Regulate the air pressure in the deposition chamber through the pressure valve. After evacuating the vacuum degree in the reaction chamber, introduce a mixed gas of Ar and NH 3 with a volume ratio of 5:1 as the auxiliary carrier gas at a rate of 1000 mL / min, and then perform chemical vapor deposition at 450 °C for 10 h. Among them, the flow ratio of the gas-phase carbon source to Ar is 1:1, and the deposition pressure is 0.05 MPa.

[0206] (4) Classify the sample obtained in step (3), use vacuum drying at 100 °C for 24 h, and then obtain the anode material.

[0207] The anode material prepared in this example includes a core and a carbon coating layer located on at least part of the surface of the core. The core includes elemental silicon, silicon oxide, and silicate.

[0208] Dissolve 20 mg of the anode material in 10 ml of deionized water to form a slurry. The pH of the slurry is 9.73. Use a nano particle size and Zeta potential analyzer to test the Zeta potential of the slurry. In the Zeta potential test distribution diagram of the slurry, as Figure 4 shown, the maximum intensity in the Zeta potential range of -10 mV to 0 mV of the slurry is I 1 = 41858.71, the maximum intensity in the Zeta potential range of -20 mV to -10 mV is I 2 = 130217.2, the maximum intensity in the Zeta potential range of -30 mV to -20 mV is I 3 = 122137.6, and I 1 / I 2 = 0.32, I 2 / I 3 = 1.07.

[0209] The median particle size of the anode material is 5.52 μm, the sulfur content m S = 33 ppm of the anode material, the nitrogen content m N = 4211 ppm of the anode material, the tapped density is 1.07 g / cm 3 , the mass content of carbon element in the anode material is 5.22%, and the mass content of water is 0.07%.

[0210] Example 3

[0211] (1) Mix 1000 g of silicon monoxide (median particle size of 5.0 μm) and 100 g of magnesium powder, and use high-energy ball milling for 24 h under argon protection. After the ball milling treatment is completed, also under argon protection, treat at a temperature of 1000 °C for 24 h to form magnesium-doped silicon monoxide. Perform air classification on the magnesium-doped silicon monoxide to obtain a material with a D50 of 5.2 μm. Rinse the above material with deionized water for 30 min, then infiltrate it with N,N-dimethylformamide for 1 h, and then place it in a vacuum drying oven. When the pressure in the oven drops to 500 Pa, start heating and drying. The drying temperature is 100 °C and the drying time is 24 h.

[0212] (2) Mix 1000 g of the material obtained in step (1), 10 g of carbon nanotubes, and 50 g of sucrose and dissolve them in 5000 ml of deionized water, while stirring and performing ultrasonic treatment for 6 h at a stirring speed of 3000 r / min. Spray-dry the obtained material at 120 °C. During the spray-drying process, use a stirrer with a speed of 1000 r / min for stirring. Heat-treat the spray-dried material under argon at a heat-treatment temperature of 800 °C for 24 h.

[0213] (3) After simply dispersing the material obtained in step (2), under an Ar atmosphere, first perform radio frequency plasma treatment for 30 min. Then mix the sample and the liquid-phase coating agent toluene evenly, and then place the obtained material into the deposition chamber of a chemical vapor deposition furnace. With the chamber rotation speed of 5 r / min, introduce methane, acetylene, ethylene, and propane gases with a volume ratio of 1:1:1:3 into the deposition chamber as the gas-phase carbon source. Regulate the pressure in the deposition chamber through a pressure valve. After evacuating the vacuum in the reaction chamber, introduce a mixed gas of Ar and NH 3 with a volume ratio of 5:1 as the auxiliary carrier gas at a rate of 1000 mL / min, and then perform chemical vapor deposition at 800 °C for 8 h. Among them, the flow ratio of the gas-phase carbon source to Ar is 1:1, and the deposition pressure is atmospheric pressure.

[0214] (4) Classify the sample obtained in step (3), and after vacuum drying at 100 °C for 24 h, obtain the negative electrode material.

[0215] The negative electrode material prepared in this example includes a core and a carbon coating layer located on at least part of the surface of the core. The core includes elemental silicon, silicon oxide, and silicate.

[0216] Dissolve 20 mg of the negative electrode material in 10 ml of deionized water to form a slurry. The pH of the slurry is 9.17. Use a nano particle size and Zeta potential analyzer to measure the Zeta potential of the slurry. In the Zeta potential test distribution diagram of the slurry, as Figure 3 shown, the maximum intensity in the Zeta potential range of -10 mV to 0 mV of the slurry is I 1= 2648.99, the maximum intensity in the Zeta potential range of -20 mV to -10 mV is I 2 = 58240.4, the maximum intensity in the Zeta potential range of -30 mV to -20 mV is I 3 = 63242.4, and I 1 / I 2 = 0.05, I 2 / I 3 = 0.92.

[0217] The median particle size of the negative electrode material is 5.12 μm, the sulfur content m of the negative electrode material S = 19 ppm, the nitrogen content m of the negative electrode material N = 5329 ppm, the tapped density is 1.01 g / cm 3 , the mass content of carbon element in the negative electrode material is 4.96%, the mass content of water is 0.10%, and the mass content of magnesium element in the negative electrode material is 87812 ppm.

[0218] Example 4

[0219] Different from Example 1, the deposition temperature in step (3) is 600 °C.

[0220] The product obtained in this example includes a core and a carbon coating layer located on at least part of the surface of the core. The core includes elemental silicon, silicon oxide and silicate.

[0221] Dissolve 20 mg of the negative electrode material in 10 ml of deionized water to form a slurry. The pH of the slurry is 9.69. Use a nano particle size and Zeta potential analyzer to test the Zeta potential of the slurry. In the Zeta potential test distribution diagram of the slurry, as Figure 5 shown, the maximum intensity of the slurry in the Zeta potential range of -10 mV to 0 mV is I 1 = 3559.26, the maximum intensity in the Zeta potential range of -20 mV to -10 mV is I 2 = 13282.27, the maximum intensity in the Zeta potential range of -30 mV to -20 mV is I 3 = 40684.82, and I 1 / I 2 = 0.27, I 2 / I 3 = 0.33.

[0222] The median particle size of the negative electrode material is 5.21 μm, the tapped density is 1.02 g / cm 3 , the sulfur content m of the negative electrode material S = 33 ppm, the nitrogen content m of the negative electrode material N= 3981 ppm, the mass content of carbon element in the negative electrode material is 5.10%, and the mass content of water is 0.11%.

[0223] Example 5

[0224] Different from Example 1, the deposition temperature in step (3) is 900 °C.

[0225] The product obtained in this example includes a core and a carbon coating layer located on at least part of the surface of the core. The core includes elemental silicon, silicon oxide, and silicate.

[0226] Dissolve 20 mg of the negative electrode material in 10 ml of deionized water to form a slurry. The pH of the slurry is 10.10. Use a nano particle size and Zeta potential analyzer to measure the Zeta potential of the slurry. In the Zeta potential test distribution diagram of the slurry, as Figure 6 shown, the maximum intensity in the Zeta potential range of -10 mV to 0 mV of the slurry is I 1 = 6623.64, the maximum intensity in the Zeta potential range of -20 mV to -10 mV of the slurry is I 2 = 34631.99, the maximum intensity in the Zeta potential range of -30 mV to -20 mV of the slurry is I 3 = 33873.43, and I 1 / I 2 = 0.19, I 2 / I 3 = 1.02.

[0227] The median particle size of the negative electrode material is 5.35 μm, the sulfur content m S = 66 ppm of the negative electrode material, the nitrogen content m N = 5901 ppm of the negative electrode material, the tap density is 1.01 g / cm 3 , the mass content of carbon element in the negative electrode material is 5.08%, and the mass content of water is 0.06%.

[0228] Example 6

[0229] Different from Example 1, the median particle size of silicon suboxide in step (1) is 3.23 μm.

[0230] The product obtained in this example includes a core and a carbon coating layer located on at least part of the surface of the core. The core includes elemental silicon, silicon oxide, and silicate.

[0231] Dissolve 20 mg of the negative electrode material in 10 ml of deionized water to form a slurry. The pH of the slurry is 8.79. Use a nano particle size and Zeta potential analyzer to test the Zeta potential of the slurry. In the Zeta potential test distribution diagram of the slurry, the maximum intensity of the slurry in the Zeta potential range of -10 mV to 0 mV is I 1 = 3209.53, and the maximum intensity in the Zeta potential range of -20 mV to -10 mV is I 2 = 53799.87, and the maximum intensity in the Zeta potential range of -30 mV to -20 mV is I 3 = 71322.77, and I 1 / I 2 = 0.06, and I 2 / I 3 = 0.75.

[0232] The median particle size of the negative electrode material is 3.23 μm, the sulfur content m S = 52 ppm, the nitrogen content m N = 4792 ppm, the tapped density is 1.19 g / cm 3 , and the mass content of carbon element in the negative electrode material is 6.3%, and the mass content of water is 0.09%.

[0233] Example 7

[0234] Different from Example 1, the median particle size of silicon suboxide in step (1) is 7.8 μm.

[0235] The product prepared in this example includes a core and a carbon coating layer located on at least part of the surface of the core. The core includes elemental silicon, silicon oxides, and silicates.

[0236] Dissolve 20 mg of the negative electrode material in 10 ml of deionized water to form a slurry. The pH of the slurry is 9.13. Use a nano particle size and Zeta potential analyzer to test the Zeta potential of the slurry. In the Zeta potential test distribution diagram of the slurry, the maximum intensity of the slurry in the Zeta potential range of -10 mV to 0 mV is I 1 = 10249.66, and the maximum intensity in the Zeta potential range of -20 mV to -10 mV is I 2 = 49982.87, and the maximum intensity in the Zeta potential range of -30 mV to -20 mV is I 3 = 40297.92, and I 1 / I 2 = 0.21, and I 2 / I 3 = 1.24.

[0237] The median particle size of the negative electrode material is 7.81 μm, and the sulfur content m of the negative electrode material S = 19 ppm, and the nitrogen content m of the negative electrode material N = 3793 ppm. The tapped density is 0.99 g / cm 3 , the mass content of carbon element in the negative electrode material is 5.01%, and the mass content of water is 0.07%.

[0238] Example 8

[0239] Different from Example 3, step (1) includes: mixing 1000 g of silicon monoxide and 100 g of magnesium powder, and using high-energy ball milling treatment for 24 h under argon protection. After the ball milling treatment is completed, also under argon protection, it is treated at a temperature of 1000 °C for 24 h to form magnesium-doped silicon monoxide.

[0240] The product obtained in this example includes a core and a carbon coating layer located on at least part of the surface of the core. The core includes elemental silicon, silicon oxide, and silicate.

[0241] Dissolve 20 mg of the negative electrode material in 10 ml of deionized water to form a slurry. The pH of the slurry is 10.3. Use a nano particle size and Zeta potential analyzer to test the Zeta potential of the slurry. In the Zeta potential test distribution diagram of the slurry, the maximum intensity of the slurry in the Zeta potential range of -10 mV to 0 mV is I 1 = 108896.40, and the maximum intensity in the Zeta potential range of -20 mV to -10 mV is I 2 = 120669.00, and the maximum intensity in the Zeta potential range of -30 mV to -20 mV is I 3 = 64749.21, and I 1 / I 2 = 0.90, I 2 / I 3 = 1.86.

[0242] The median particle size of the negative electrode material is 5.0 μm, and the sulfur content m of the negative electrode material S = 34 ppm, and the nitrogen content m of the negative electrode material N = 3109 ppm. The tapped density is 0.95 g / cm 3 , the mass content of carbon element in the negative electrode material is 2.3%, and the mass content of water is 0.90%.

[0243] Example 9

[0244] Different from Example 1, (2) 1000 g of the material obtained in step (1) and 10 g of carbon nanotubes were mixed and dissolved in 5000 ml of deionized water, while stirring and ultrasonic treatment were carried out for 6 h, and the stirring speed was 3000 r / min. The obtained material was spray-dried at 120 °C, and a stirrer with a speed of 1000 r / min was used for stirring during the spray-drying process. The spray-dried material was subjected to high-temperature heat treatment under argon, the heat treatment temperature was 800 °C, and the treatment time was 24 h.

[0245] The product prepared in this example includes a core and a carbon coating layer located on at least part of the surface of the core. The core includes elemental silicon, silicon oxide and silicate.

[0246] 20 mg of the negative electrode material was dissolved in 10 ml of deionized water to form a slurry. The pH of the slurry was 9.51. A nano-particle size and Zeta potential analyzer was used to test the Zeta potential of the slurry. In the Zeta potential test distribution map of the slurry, the maximum intensity in the Zeta potential range of -10 mV to 0 mV was I 1 = 6109.98, and the maximum intensity in the Zeta potential range of -20 mV to -10 mV was I 2 = 47230.93, and the maximum intensity in the Zeta potential range of -30 mV to -20 mV was I 3 = 54399.58, and I 1 / I 2 = 0.13, I 2 / I 3 = 0.87.

[0247] The median particle size of the negative electrode material was 5.2 μm, the sulfur content m S = 47 ppm, the nitrogen content m N = 4259 ppm, the tapped density was 1.01 g / cm 3 , and the mass content of carbon element in the negative electrode material was 5.02%, and the mass content of water was 0.08%.

[0248] Example 10

[0249] Different from Example 1, (3) the radio frequency plasma treatment time was 60 min.

[0250] The product prepared in this example includes a core and a carbon coating layer located on at least part of the surface of the core. The core includes elemental silicon, silicon oxide and silicate.

[0251] Dissolve 20 mg of the anode material in 10 ml of deionized water to form a slurry. The pH of the slurry is 9.69. Use a nano particle size and Zeta potential analyzer to measure the Zeta potential of the slurry. In the Zeta potential test distribution diagram of the slurry, the maximum intensity in the Zeta potential range of -10 mV to 0 mV is I 1 = 0, and the maximum intensity in the Zeta potential range of -20 mV to -10 mV is I 2 = 87992.59, and the maximum intensity in the Zeta potential range of -30 mV to -20 mV is I 3 = 86337.20, and I 1 / I 2 = 0, I 2 / I 3 = 1.02.

[0252] The median particle size of the anode material is 4.89 μm, the sulfur content m S = 59 ppm, the nitrogen content m N = 3799 ppm, the tapped density is 1.10 g / cm 3 , and the mass content of carbon element in the anode material is 5.06%, and the mass content of water is 0.06%.

[0253] Comparative Example 1

[0254] (1) Rinse 1000 g of silicon monoxide (median particle size is 5.0 μm) with deionized water for 30 min, then soak it with ethanol for 3 h, and then put it into a vacuum drying oven. When the pressure in the oven drops to 500 Pa, start heating and drying. The drying temperature is 100 °C, and the drying time is 24 h to obtain the anode material.

[0255] The anode material prepared in this comparative example includes silicon monoxide.

[0256] Dissolve 20 mg of the anode material in 10 ml of deionized water to form a slurry. The pH of the slurry is 9.01. Use a nano particle size and Zeta potential analyzer to measure the Zeta potential of the slurry. In the Zeta potential test distribution diagram of the slurry, the maximum intensity in the Zeta potential range of -10 mV to 0 mV is I 1 = 50983.72, and the maximum intensity in the Zeta potential range of -20 mV to -10 mV is I 2 = 65654.72, and the maximum intensity in the Zeta potential range of -30 mV to -20 mV is I 3 = 10828.84, and I 1 / I 2 = 0.78, I 2 / I 3= 6.06.

[0257] The median particle size of the negative electrode material is 6.41 μm, and the tap density is 0.95 g / cm 3 , and the mass content of carbon element in the negative electrode material is 0.51%, and the mass content of water is 0.27%.

[0258] Comparative Example 2

[0259] (1) 1000 g of silicon monoxide (median particle size of 5.0 μm) and 100 g of magnesium powder were mixed and subjected to high-energy ball milling for 24 h under argon protection. After the ball milling was completed, it was also treated at 1000 °C for 24 h under argon protection to form magnesium-doped silicon monoxide. The magnesium-doped silicon monoxide was rinsed with deionized water for 30 min, then infiltrated with N,N-dimethylformamide for 1 h, and then placed in a vacuum drying oven. When the pressure in the oven dropped to 500 Pa, heating and drying were started. The drying temperature was 100 °C, and the drying time was 24 h.

[0260] (2) 1000 g of the material obtained in step (1), 10 g of carbon nanotubes, and 50 g of sucrose were mixed and dissolved in 5000 ml of deionized water, and at the same time, stirring and ultrasonic treatment were carried out for 6 h, and the stirring speed was 3000 r / min. The obtained material was spray-dried at 120 °C. During the spray-drying process, a stirrer with a speed of 1000 r / min was used for stirring. The spray-dried material was subjected to high-temperature heat treatment under argon, the heat treatment temperature was 1000 °C, and the treatment time was 18 h to obtain the negative electrode material.

[0261] The negative electrode material prepared in this comparative example includes a core and a carbon coating layer located on at least part of the surface of the core. The core includes elemental silicon, silicon oxide, and silicate.

[0262] 20 mg of the negative electrode material was dissolved in 10 ml of deionized water to form a slurry. The pH of the slurry was 9.31. A nano particle size and Zeta potential analyzer was used to measure the Zeta potential of the slurry. In the Zeta potential test distribution diagram of the slurry, the maximum intensity in the Zeta potential range of -10 mV to 0 mV of the slurry was I 1 = 120971.5, and the maximum intensity in the Zeta potential range of -20 mV to -10 mV of the slurry was I 2 = 121041.5, and the maximum intensity in the Zeta potential range of -30 mV to -20 mV of the slurry was I 3 = 45937.1, and I 1 / I 2 = 1.00, I 2 / I 3 = 2.63.

[0263] The median particle size of the negative electrode material is 4.86 μm, and the tap density is 0.93 g / cm 3 , the mass content of carbon element in the negative electrode material is 3.20%, the mass content of water is 0.69%, and the content of magnesium element in the negative electrode material is 87933 ppm.

[0264] Comparative Example 3

[0265] (1) 1000 g of silicon suboxide (median particle size is 5.0 μm) was rinsed with deionized water for 30 min, then infiltrated with ethanol for 3 h, and then placed in a vacuum drying oven. When the pressure in the oven dropped to 500 Pa, heating and drying were started. The drying temperature was 100 °C and the drying time was 24 h. Then the obtained material was rinsed with deionized water for 30 min and dried in a vacuum drying oven at 100 °C for 24 h.

[0266] (2) 1000 g of the material obtained in step (1), 10 g of carbon nanotubes and 50 g of sucrose were mixed and dissolved in 5000 ml of deionized water, and at the same time, stirring and ultrasonic treatment were carried out for 6 h, and the stirring speed was 3000 r / min. The obtained material was spray-dried at 120 °C. During the spray-drying process, a stirrer with a speed of 1000 r / min was used for stirring. The spray-dried material was subjected to high-temperature heat treatment under argon. The heat treatment temperature was 1000 °C and the treatment time was 18 h.

[0267] (3) The sample obtained in step (2) was placed in the deposition chamber of a chemical vapor deposition furnace, and methane gas was introduced into the deposition chamber as a gaseous carbon source, and then chemical vapor deposition was carried out at 900 °C for 4 h. Among them, the rotation speed of the deposition chamber was 5 r / min and the deposition pressure was 0.05 MPa.

[0268] (4) After the chemical vapor deposition product was classified, it was dried in a vacuum drying oven at 100 °C for 24 h to obtain the negative electrode material.

[0269] The negative electrode material prepared in this comparative example includes a core and a carbon coating layer located on at least part of the surface of the core. The core includes elemental silicon, silicon oxide and silicate.

[0270] 20 mg of the negative electrode material was dissolved in 10 ml of deionized water to form a slurry. The pH of the slurry was 8.71. A nano-particle size and Zeta potential analyzer was used to measure the Zeta potential of the slurry. In the Zeta potential test distribution diagram of the slurry, the maximum intensity in the Zeta potential range of -10 mV to 0 mV of the slurry was I 1 = 62377.1, and the maximum intensity in the Zeta potential range of -20 mV to -10 mV of the slurry was I 2 = 53209.88, and the maximum intensity in the Zeta potential range of -30 mV to -20 mV of the slurry was I 3= 8140.92, and I 1 / I 2 = 1.17, I 2 / I 3 = 6.54.

[0271] The median particle size of the anode material is 5.20 μm, and the tap density is 1.01 g / cm 3 , and the mass content of carbon element in the anode material is 3.50%, and the mass content of water is 0.69%.

[0272] Comparative Example 4

[0273] (1) 1000 g of silicon monoxide (median particle size is 5.0 μm) and 100 g of magnesium powder were mixed, and high-energy ball milling was carried out for 24 h under argon protection. After the ball milling was completed, it was also treated at 1000 °C for 24 h under argon protection to form magnesium-doped silicon monoxide. The magnesium-doped silicon monoxide was rinsed with deionized water for 30 min, then infiltrated with N,N-dimethylformamide for 1 h, and then placed in a vacuum drying oven. When the pressure in the oven dropped to 500 Pa, heating and drying were started. The drying temperature was 100 °C, and the drying time was 24 h.

[0274] (2) The sample obtained in step (1) was placed in the deposition chamber of a chemical vapor deposition furnace, methane gas was introduced into the deposition chamber as a gaseous carbon source, and then chemical vapor deposition was carried out at 1200 °C for 4 h. Among them, the rotation speed of the deposition chamber was 5 r / min, and the deposition pressure was 0.05 MPa.

[0275] The product prepared in this comparative example includes a core and a carbon coating layer located on at least part of the surface of the core. The core includes elemental silicon, silicon oxide and silicate.

[0276] Dissolve 20 mg of the anode material in 10 ml of deionized water to form a slurry. The pH of the slurry is 10.22. Use a nano particle size and Zeta potential analyzer to measure the Zeta potential of the slurry. In the Zeta potential test distribution diagram of the slurry, the maximum intensity of the slurry in the Zeta potential range of -10 mV to 0 mV is I 1 = 85232.1, and the maximum intensity of the slurry in the Zeta potential range of -20 mV to -10 mV is I 2 = 75921.9, and the maximum intensity of the slurry in the Zeta potential range of -30 mV to -20 mV is I 3 = 54229.7, and I 1 / I 2 = 1.12, I 2 / I 3 = 1.40.

[0277] The median particle size of the negative electrode material is 5.23 μm, and the tapped density is 1.02 g / cm 3 , the mass content of carbon element in the negative electrode material is 5.00%, the mass content of water is 0.77%, and the content of magnesium element in the negative electrode material is 85219 ppm.

[0278] Test method

[0279] (1) Test method for the particle size of the negative electrode material:

[0280] The particle size of the negative electrode material was tested using a Malvern Mastersizer 2000 laser particle size analyzer to obtain the median particle size.

[0281] (2) Test method for the tapped density of the negative electrode material:

[0282] A tapped density tester (produced by Dandong BET Instrument Co., Ltd.) was used. A certain amount of sample was weighed and placed in the tapped density tester, and the tapped density was tested by vibrating 3000 times at 300 times / min.

[0283] (3) Test method for the mass content of water in the negative electrode material:

[0284] The mass content of water in the negative electrode material was tested using thermogravimetry. At 250 °C, the proportion of the mass lost by the negative electrode material in the total weight is the mass content of water in the negative electrode material.

[0285] (4) Test method for the mass content of carbon material in the negative electrode material:

[0286] The mass content of carbon material in the negative electrode material was tested using thermogravimetric analysis.

[0287] (5) Test method for the pH value and Zeta potential of the negative electrode material:

[0288] Weigh 20 mg of the negative electrode material and dissolve it in deionized water to form a slurry, and test the pH value of the negative electrode material; adjust the pH of the slurry to 8.0 - 10.5. If the pH of the slurry formed by dissolving the negative electrode material in deionized water is not within the above range, the pH value can be adjusted by adding LiOH or HCl. Use a nano particle size and Zeta potential analyzer (DLS, model Malvern Zetasizer NanoZS90) to test the Zeta potential of the slurry. The ultrasonic dispersion time for each sample needs to be at least 10 min or more, and each sample is tested multiple times until the difference in Zeta potential values for 3 times is within 1 mV, and then the data analysis of the median value of the three times is selected. For example, a certain sample was tested 3 times, and the Zeta potential each time is V 1 , V 2 , V 3 , where the size order is V1 <V 2 <V 3 , which meets the following requirements, , , then select the set of data with the Zeta potential of V 2 for Zeta potential distribution analysis.

[0289] (6) Electrochemical performance test:

[0290] According to the equipment and methods in BETRAY's BTRTC / ZY / 01-020 "Operation Instruction Manual for Button Cell Method": Assemble the negative electrode materials prepared in Examples 1 to 10 and Comparative Examples 1 to 4 into button cells for testing. Among them, the counter electrode uses a lithium metal sheet, the separator is a PP-PE-PP composite membrane with a diameter of 19.2 mm, the component ratio of the electrolyte is EC / EMC / DMC = 1:1:1, and the concentration of the lithium salt (LiPF6) is 1.05 mol / L.

[0291] Test of the specific capacity of the negative electrode material: Use a button cell charge and discharge device to charge at a constant current of 0.1C to 10mV and then switch to a constant current of 0.02C to charge to 5mV, and discharge at a constant current of 0.1C until cutoff at 1.5V;

[0292] 50-week cycle test of the half cell: Use a button cell charge and discharge device. In the first week, discharge at 0.1C to 0.01V, discharge at an arithmetic progression of 0.01C to 0.01V, discharge at 0.01C to 0.005V, and charge at 0.1C to 1.5V; In the second week, discharge at 0.2C to 0.01V, discharge at an arithmetic progression of 0.02C to 0.01V, discharge at 0.02C to 0.005V, and charge at 0.2C to 1.5V; In the third week, discharge at 0.5C to 0.01V, discharge at an arithmetic progression of 0.05C to 0.01V, discharge at 0.05C to 0.005V, and charge at 0.5C to 1.5V; From the fourth week to the 50th week, discharge at 1C to 0.01V, discharge at an arithmetic progression of 0.1C to 0.01V, discharge at 0.1C to 0.005V, and charge at 1C to 1.5V; In the 51st week, discharge at 0.1C to 0.01V, discharge at an arithmetic progression of 0.01C to 0.01V, discharge at 0.01C to 0.005V.

[0293] Test of the performance of the full cell: Mix the negative electrode material with graphite to make the capacity of the negative electrode material reach the standard of 450 mAh / g, and test the capacity retention rate of the material at 60°C, test 0.2C charge and discharge, (2.75 - 4.2V).

[0294] Table 1 Test results of the performance of the negative electrode material

[0295] Sample Capacity mAh / g Initial efficiency pH <![CDATA[Zeta potential I 1 / I 2 > <![CDATA[Zeta potential I 2 / I 3 > Capacity retention rate after 50 cycles of discharging Electrode swelling rate after discharging cycles Charge rate 1C / 0.5C Charge rate 2C / 0.5C Charge rate 3C / 0.5C Example 1 1702.0 79.4% 9.2 0.13 0.87 90.02% 31.27% 88.11% 75.77% 57.32% Example 2 1693.7 80.1% 9.17 0.32 1.07 89.40% 32.70% 89.21% 77.31% 56.19% Example 3 1431.9 83.3% 9.73 0.05 0.92 88.32% 32.34% 87.68% 75.06% 55.89% Example 4 1688.5 80.0% 9.69 0.27 0.33 85.98% 32.38% 88.08% 75.74% 57.29% Example 5 1673.6 80.8% 10.10 0.19 1.02 87.29% 32.52% 88.95% 75.80% 56.76% Example 6 1721.2 79.5% 8.79 0.06 0.75 87.09% 31.92% 88.91% 76.02% 57.19% Example 7 1687.5 78.9% 9.13 0.21 1.24 86.55% 32.58% 88.47% 75.83% 57.22% Example 8 1429.7 82.6% 10.30 0.90 1.86 85.31% 32.79% 87.77% 74.75% 55.60% Example 9 1662.1 77.4% 9.51 0.13 0.87 87.20% 33.85% 88.11% 75.36% 56.92% Example 10 1634.22 76.1% 9.69 0 1.02 86.87% 34.01 % 87.78% 75.22% 53.10% Comparative example 1 1533.9 75.2% 9.01 0.78 6.06 50.21% 57.32% 70.19% 43.27% 15.09% Comparative example 2 1389.2 82.0% 9.31 1.00 2.63 51.07% 58.23% 75.33% 50.27% 20.39% Comparative example 3 1590.2 72.0% 8.71 1.17 6.54 62.09% 55.39% 72.06% 45.22% 17.98% Comparative example 4 1357.9 81.3% 10.22 1.12 1.40 55.79% 54.20% 76.98% 53.20% 22.10%

[0296] As shown in Table 1, in the negative electrode materials prepared in Examples 1 to 10, the core surface of the silicon-based material has a coating layer, which can effectively isolate the exposure of the silicon-based material in the electrolyte, reduce the loss of active silicon in the silicon-based material, improve the cycle performance of the negative electrode material. The Zeta potential of the negative electrode material was tested, and the intensity I of the characteristic peak was obtained. 1 、I 2 、I 3 The relationship among the three satisfies 0 ≤ I 1 / I 2 ≤ 1.0, 0 < I 2 / I 3 ≤ 2.0. The surface interface of the negative electrode material has a variety of different surface combinations (that is, the surface interface of the negative electrode material is differentiated and diversified). The interfacial reaction of the negative electrode material is good, which can build a high-speed mass and charge transfer interface between the negative electrode material and the electrolyte, improve the mass and charge conduction efficiency, thereby improving the rate performance of the negative electrode material, control the solid-liquid reaction between the surface of the negative electrode material and the electrolyte, form a stable SEI interface, reduce the degradation of the electrolyte, inhibit swelling, and thus improve the cycle performance of the negative electrode material.

[0297] In Comparative Example 1, the negative electrode active material was not coated, resulting in serious loss of the negative electrode active material during the cycling process, and the cycle performance of the negative electrode material decreased significantly; the ratio of I 2 / I 3 increased significantly, making the surface interface of the negative electrode material single. During the electrochemical reaction process, it is difficult for the negative electrode material to control the degradation reaction of the electrolyte. The electrolyte degrades and deposits excessively, causing the electrode sheet to swell, and the swelling rate of the electrode sheet increases significantly, which in turn leads to a significant reduction in the cycle performance of the negative electrode material; at the same time, the excessive degradation of the electrolyte is not conducive to the rapid transmission of lithium ions, increases the lithium ion transmission path, and reduces the lithium ion transmission efficiency, thereby significantly reducing the rate performance of the negative electrode material.

[0298] In Comparative Example 2, only steps (1) and (2) were carried out. The carbon coating layer on the surface of the negative electrode material prepared in Comparative Example 2 was incomplete, and the surface interface of the negative electrode material was relatively single. The carbon coating layer had limited modification on the surface interface of the negative electrode material, resulting in an increase in the ratio of I 2 / I 3 of the negative electrode material, leading to excessive contact between the active material in the negative electrode material and the electrolyte, an increase in side reactions, and thus a significant decrease in the cycle performance of the negative electrode material.

[0299] In Comparative Example 3, in step (3), only a single gaseous carbon source was coated, and in step (1), no organic solvent impregnation treatment was carried out, so that the surface interface of the negative electrode material could not be modified, resulting in a large difference in the surface charge density of the negative electrode material, I 1 / I 2 and I2 / I 3 The ratios of all increase, the surface and interface stability of the negative electrode material decreases, the negative electrode material is prone to agglomeration during the slurry mixing process, and the dispersion stability is poor, resulting in poor cycling performance and swelling performance of the negative electrode material.

[0300] In Comparative Example 4, in Step 3, only a single gaseous carbon source was used for coating, resulting in limited surface and interface modification of the negative electrode material, large differences in the surface and interface charge density of the negative electrode material, and I 1 / I 2 The ratio increases, the surface and interface stability of the negative electrode material decreases, the negative electrode material is prone to agglomeration during the slurry mixing process, and the dispersion stability is poor, resulting in poor cycling performance and swelling performance of the negative electrode material.

[0301] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A negative electrode material, characterized in that: The invention comprises a core and a coating layer located on at least a part of the surface of the core, wherein the core comprises a silicon-based material and the coating layer comprises a carbon material; the negative electrode material is prepared into a slurry, and a nano-particle size and Zeta potential analyzer is used to perform a Zeta potential test on the slurry, wherein in a Zeta potential test distribution diagram of the slurry, the maximum intensity of the slurry in the Zeta potential interval of -10mV to 0mV is I1, the maximum intensity in the Zeta potential interval of -20mV to -10mV is I2, and the maximum intensity in the Zeta potential interval of -30mV to -20mV is I3, and the relationship among I1, I2 and I3 satisfies: 0≤I1 / I2≤1.0, 0<I2 / I3≤2.0; Wherein, the negative electrode material further includes a doping element, and the doping element includes at least one of nitrogen and sulfur; The step of preparing the negative electrode material into the slurry includes: dissolving the negative electrode material in deionized water so that the pH of the slurry is 8.0-10.5, or dissolving the negative electrode material and an alkaline substance in deionized water so that the pH of the slurry is 8.0-10.

5.

2. The negative electrode material according to claim 1, characterized in that The negative electrode material includes at least one of the following features (1) to (8): (1) The silicon-based material includes at least one of silicon, silicon-oxygen material and silicate; (2) The silicon-based material includes a silicon-oxygen material, and the silicon-oxygen material includes SiO x , where 0<x<2; (3) The silicon-based material includes a silicate, and the silicate includes at least one of lithium silicate, magnesium silicate, aluminum silicate, magnesium aluminum silicate, lithium magnesium silicate, calcium silicate, magnesium calcium silicate, lithium calcium silicate and lithium aluminum silicate; (4) the doping element is distributed in the core; (5) The negative electrode material contains nitrogen, and the content of the nitrogen in the negative electrode material is 0 to 500 ppm and does not include 0 ppm; (6) The negative electrode material contains sulfur, and the content of sulfur in the negative electrode material is 50ppm~6000ppm; (7) The carbon material includes at least one of graphite, hard carbon, soft carbon, amorphous carbon, diamond-like carbon, carbon fiber and carbide; (8) The material of the coating layer further includes at least one of sulfide, nitride, metal oxide, phosphate and silicate.

3. The negative electrode material according to claim 1 or 2, characterized in that: The negative electrode material includes at least one of the following features (1) to (5): (1) The material of the coating layer further includes sulfide, and the sulfide includes at least one of carbon disulfide and organic sulfide; (2) The material of the coating layer further includes nitride, and the nitride includes at least one of silicon nitride, pyrrole and pyridine; (3) The material of the coating layer further comprises a metal oxide, and the metal oxide comprises at least one of titanium oxide, aluminum oxide, magnesium oxide, lithium oxide, zirconium oxide, cobalt oxide and vanadium oxide; (4) The material of the coating layer further includes phosphate, and the phosphate includes at least one of lithium phosphate, aluminum phosphate, lithium aluminum phosphate, lithium titanium aluminum phosphate, magnesium phosphate, lithium magnesium phosphate, calcium phosphate, lithium calcium phosphate, lithium dihydrogen phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate and triammonium phosphate; (5) The material of the coating layer further comprises silicate, and the silicate comprises at least one of lithium silicate, magnesium silicate, aluminum silicate, magnesium aluminum silicate, lithium magnesium silicate, calcium silicate, magnesium calcium silicate, lithium calcium silicate and lithium aluminum silicate.

4. The negative electrode material according to claim 1, characterized in that The negative electrode material includes at least one of the following features (1) to (9): (1) The pH of the slurry is 8.0-10.5; (2) The median particle size of the core is 2.5 μm to 10.0 μm; (3) The thickness of the coating layer is 20nm~700nm; (4) The median particle size of the negative electrode material is 3 μm to 10 μm; (5) Based on the mass of the negative electrode material being 100%, the mass of the carbon material accounts for 0.5wt% to 10wt%; (6) The specific surface area of ​​the negative electrode material is 1.0 m 2 / g~5.0m 2 / g; (7) The pH of the negative electrode material is 6.5 to 10.5; (8) The tap density of the negative electrode material is 0.5 g / cm 3 ~2.0g / cm 3 ; (9) The mass proportion of water in the negative electrode material is 0.01%~0.50%.

5. A method for preparing the negative electrode material according to any one of claims 1 to 4, characterized in that: The following steps are involved: The silicon raw material and the dopant are mixed and subjected to a heat treatment, and then placed in an organic solvent for immersion treatment, and the material obtained by the immersion treatment is dried to obtain a precursor; The mixed material containing the precursor, the auxiliary agent and the solvent is spray-dried, and the spray-dried material is subjected to secondary heat treatment, and then subjected to radio frequency plasma treatment, and then the precursor is subjected to vapor deposition using a gaseous carbon source, and during the vapor deposition process, an auxiliary carrier gas is added, and the precursor is coated with a solid-phase coating agent and / or a liquid-phase coating agent to obtain a negative electrode material, wherein the negative electrode material includes a core and a coating layer located on at least a portion of the surface of the core, the core includes a silicon-based material, and the coating layer includes a carbon material deposited by a gaseous carbon source, and a carbon material formed by deposition of the solid-phase coating agent and / or the liquid-phase coating agent; The dopant includes at least one of magnesium, aluminum, lithium, titanium, phosphorus, copper, tin, gallium, germanium, indium, molybdenum, platinum and rhodium; the temperature of the primary heat treatment is 500° C. to 1300° C.; the holding time of the primary heat treatment is 2 h to 24 h; The auxiliary agent includes at least one of carbon nanotubes, sucrose, asphalt, conductive carbon black, nitride and sulfide; the temperature of the secondary heat treatment is 400°C to 1000°C; and the insulation time of the secondary heat treatment is 2h to 24h.

6. The preparation method according to claim 5, characterized in that: The method comprises at least one of the following features (1) to (4): (1) The silicon raw material includes at least one of silicon monoxide, elemental silicon, silicon dioxide and silicate; (2) The mass ratio of the silicon raw material to the dopant is 1:(0.01~0.1); (3) The primary heat treatment is performed in a protective gas atmosphere, wherein the protective gas comprises at least one of helium, neon, argon, krypton and xenon; (4) After the primary heat treatment, the method further includes: grading and purifying the material obtained from the primary heat treatment.

7. The preparation method according to claim 6, characterized in that: The method comprises at least one of the following features (1) to (2): (1) After the primary heat treatment, the method further comprises: subjecting the material obtained from the primary heat treatment to classification and purification, wherein the classification comprises airflow classification; (2) After the primary heat treatment, the method further comprises: grading and purifying the material obtained from the primary heat treatment, wherein the median particle size of the material obtained from the grading is 2 μm to 10 μm.

8. The preparation method according to claim 5, characterized in that: The preparation method comprises at least one of the following features (1) to (11): (1) The auxiliary agent includes a nitride, and the nitride includes at least one of pyrrole, pyridine, amino acid and amine substances; (2) The auxiliary agent includes a sulfide, and the sulfide includes at least one of carbonized sulfur and an organic sulfide; (3) The solvent includes at least one of deionized water and an alcohol solvent; (4) The mass ratio of the precursor to the auxiliary agent is 1:(0.005~0.1); (5) The mass proportion of the precursor in the mixture containing the precursor, auxiliary agent and solvent is 20% to 50%; (6) The secondary heat treatment is performed in a protective gas atmosphere, wherein the protective gas comprises at least one of nitrogen, helium, argon, neon and krypton; (7) Before spray drying the mixture containing the precursor, the auxiliary agent and the solvent, the method further comprises: stirring and ultrasonically treating the mixture containing the precursor, the auxiliary agent and the solvent; (8) The spray drying includes vacuum spray drying; (9) The spray drying temperature is 100°C to 150°C; (10) The spray drying is carried out under stirring conditions; (11) After the secondary heat treatment, the method further includes the step of screening the material obtained from the secondary heat treatment.

9. The preparation method according to claim 8, characterized in that: The preparation method comprises at least one of the following features (1) to (4): (1) before spray drying the mixture containing the precursor, the auxiliary agent and the solvent, the method further comprises: stirring the mixture containing the precursor, the auxiliary agent and the solvent and subjecting the mixture to ultrasonic treatment, wherein the stirring speed is 2000 r / min to 3000 r / min; (2) before spray drying the mixture containing the precursor, the auxiliary agent and the solvent, the method further comprises: stirring the mixture containing the precursor, the auxiliary agent and the solvent and subjecting the mixture to ultrasonic treatment, wherein the stirring treatment time is 12 hours to 36 hours; (3) The spray drying includes vacuum spray drying, and the pressure of the vacuum spray drying is 0.1Pa~1000Pa; (4) The spray drying is carried out under stirring conditions, and the rotation speed of the stirring conditions is 500r / min to 1000r / min.

10. The preparation method according to claim 5, characterized in that: The method comprises at least one of the following features (1) to (17): (1) The organic solvent includes at least one of ethanol, acetone, N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide and ethylene glycol dimethyl ether; (2) The immersion treatment time is 2h~10h; (3) The drying process is carried out under vacuum conditions, and the pressure of the drying process is 0.1 Pa to 1000 Pa; (4) The drying temperature is 45°C to 80°C; (5) The drying time is 3h~48h; (6) The RF plasma treatment time is 5 min to 30 min; (7) The gaseous carbon source comprises at least one of methane, ethane, ethylene, acetylene, propyne, propylene, propane and formaldehyde; (8) The flow rate of the gas phase carbon source is 200 mL / min~5000 mL / min; (9) The deposition temperature of the vapor deposition is 400°C to 1200°C; (10) The deposition time of the vapor deposition is 1 h to 24 h; (11) The deposition pressure of the vapor deposition is 10KPa~0.1MPa; (12) The auxiliary carrier gas includes at least one of H2, CO2, SO2, NH3 and Ar; (13) The flow rate of the auxiliary carrier gas is 500 mL / min~5000 mL / min; (14) The flow ratio of the gas phase carbon source to the auxiliary carrier gas is (3-95): (5-70); (15) The vapor deposition is carried out in a deposition chamber of a vapor deposition device, and the rotation speed of the deposition chamber is 0.1 r / min to 10 r / min; (16) The solid phase coating agent includes at least one of tetracarboxylic anhydride, copper phthalocyanine, perylenetetracarboxylic dianhydride, solid asphalt and molybdenum disulfide; (17) The liquid coating agent includes at least one of toluene, methanol, acetonitrile, chloroform, cyclohexane, dichloromethane, tetrahydrofuran, n-butanol, n-propanol, isopropanol, acetone, carbon tetrachloride and n-hexane.

11. The preparation method according to claim 5, characterized in that: The method further comprises: classifying and drying the vapor-deposited product. The preparation method comprises at least one of the following features (1) to (2): (1) The drying temperature is 50°C to 120°C; (2) The drying time is 6 hours to 48 hours.

12. A lithium ion battery, characterized in that: The lithium-ion battery comprises the negative electrode material according to any one of claims 1 to 4 or the negative electrode material prepared by the method for preparing the negative electrode material according to any one of claims 5 to 11.

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