Pre-lithiated negative electrode material and preparation method thereof, negative electrode and lithium-containing battery

Abstract

The invention relates to a pre-lithiated negative electrode material and a preparation method thereof, a negative electrode and a lithium-containing battery. Comprising the following steps: S1, contacting a first silicon-containing substrate with an organic carbon source, and carrying out carbon coating treatment to obtain a carbon-coated silicon-containing substrate; s2, enabling metal lithium to be in contact with a second silicon-containing substrate, and carrying out first ball milling treatment to obtain a pre-lithium precursor; s3, mixing the pre-lithium precursor with a first organic solvent, and carrying out second ball milling treatment to obtain a pre-lithium solution; and S4, enabling a pre-lithiation solution to be in contact with the carbon-coated silicon-containing substrate obtained in the step S1, and carrying out pre-lithiation treatment. The pre-lithiation is relatively uniform, the loss of active silicon and the loss of gram volume are reduced, and the first-effect improvement is remarkable on the premise of ensuring relatively high gram volume.

Description

Technical Field

[0001] The present disclosure relates to the technical field of lithium-ion batteries, and in particular to a pre-lithiation negative electrode material and a preparation method thereof, a negative electrode, and a lithium-containing battery. Background Art

[0002] In recent years, the rapid development of new energy vehicles, smart grids, and distributed energy storage has put forward higher requirements for the energy density and cycle life of batteries. At present, commercial lithium-ion batteries mainly use graphite-based negative electrode materials, but its theoretical specific capacity is only 372mAh / g, which cannot meet the future demand for high energy density of lithium-ion batteries. The theoretical capacity of Si is as high as 4200mAh / g, but its expansion is as high as 300%, which affects the cycle performance and restricts its market promotion and application. The corresponding silicon oxide material has better cycle performance, but the first efficiency is low. During the first charge, 20% to 50% of the lithium is consumed for SEI film formation, which greatly reduces the first coulomb efficiency.

[0003] Pre-lithiation is an effective method to improve the first coulombic efficiency of silicon-oxygen negative electrodes. At present, the commonly used negative electrode pre-lithiation reagents are mainly lithium powder and lithium ribbons. Among them, lithium ribbons are difficult to process, and the degree of pre-lithiation is difficult to control. Researchers at FMC Corporation in the United States first proposed that adding lithium powder to lithium-ion batteries can effectively offset the above-mentioned irreversible capacity. Lithium powder dissolves and releases lithium ions during the operation of the battery to make up for the lithium ions consumed in the formation of the SEI film. The addition of lithium powder effectively offsets the loss of lithium ions, improves the first charge and discharge efficiency of the battery, and thus increases the specific energy of the battery (the battery capacity is increased by 10-20%). These conclusions have been proven in the research of Shin-Etsu Chemical in Japan, SKC Power Tech in South Korea, and others.

[0004] However, current lithium powder particles are relatively large, leading to uneven pre-lithiation during pre-lithiation applications. This can lead to over-lithiation in some areas of the material, loss of active silicon, and significant loss of specific capacity. Insufficient pre-lithiation in other areas can also limit initial efficiency gains, resulting in poor overall performance of the pre-lithiation material. Furthermore, uneven pre-lithiation of silicon-oxygen materials can also lead to excessively high pH and gassing in the pre-lithiation material, resulting in reduced battery capacity and "bulging" issues. Summary of the Invention

[0005] The purpose of the present disclosure is to provide a pre-lithiation negative electrode material and a preparation method thereof, a negative electrode and a lithium-containing battery, wherein the pre-lithiation is relatively uniform, the loss of active silicon and gram capacity loss are reduced, and the first efficiency is significantly improved under the premise of ensuring a higher gram capacity.

[0006] In order to achieve the above-mentioned objectives, the first aspect of the present disclosure provides a method for preparing a pre-lithiation negative electrode material, comprising the following steps: S1, contacting a first silicon-containing matrix with an organic carbon source, performing a carbon coating treatment, and obtaining a carbon-coated silicon-containing matrix; S2, contacting metallic lithium with a second silicon-containing matrix, performing a first ball milling treatment, and obtaining a pre-lithiation precursor; S3, mixing the pre-lithiation precursor with a first organic solvent, performing a second ball milling treatment, and obtaining a pre-lithiation solution; S4, contacting the pre-lithiation solution with the carbon-coated silicon-containing matrix obtained in step S1, and performing a pre-lithiation treatment.

[0007] Optionally, in step S1, the first silicon-containing matrix is ​​selected from one or more of SiOx and silicon, 0.5≤x<2;

[0008] The organic carbon source includes a solid organic carbon source or a gaseous organic carbon source;

[0009] Optionally, the solid organic carbon source is selected from one or more of a polymer carbon source, a petroleum carbon source, a sugar carbon source, a graphite carbon source and other carbon sources;

[0010] Preferably, the polymer carbon source comprises one or more of phenolic resin, epoxy resin, polyvinyl pyrrolidone and polyvinyl alcohol;

[0011] Preferably, the petroleum carbon source includes one or more of asphalt, petroleum coke and needle coke;

[0012] Preferably, the carbohydrate carbon source includes one or more of glucose, sucrose and fructose;

[0013] Preferably, the other carbon source is selected from one or more of sodium carboxymethyl cellulose, polyvinyl alcohol and carboxy styrene butadiene latex;

[0014] Optionally, the gaseous organic carbon source is selected from one or more gaseous hydrocarbons, preferably, the gaseous organic carbon source is selected from one or more of methane, acetylene and ethylene;

[0015] Preferably, the weight ratio of the first silicon-containing matrix to the solid organic carbon source is 1:0.01-1, preferably 1:0.05-0.2; or, relative to 1g of the first silicon-containing matrix, the volume of the gaseous organic carbon source is 0.02-2L.

[0016] Optionally, in step S1, for a solid organic carbon source, the carbon coating process is selected from a solid phase coating process or a liquid phase coating process; for a gaseous organic carbon source, the carbon coating process includes a gas phase CVD deposition process;

[0017] Optionally, the solid phase coating process includes: mixing and coating the first silicon-containing matrix and the solid organic carbon source through a third ball milling process or a melt coating process, and then performing a carbon coating process through a first calcination carbonization process; Optionally, the conditions of the melt coating process in the solid phase coating process include: a temperature of 200 to 1000° C. and a time of 2 to 72 hours; Optionally, the conditions of the first calcination carbonization process in the solid phase coating process include: a calcination temperature of 500 to 1500° C., a calcination time of 2 to 72 hours, and a calcination atmosphere of argon and / or nitrogen; Preferably, the calcination temperature is 700 to 1200° C. and the calcination time is 2 to 5 hours;

[0018] Optionally, the liquid phase coating process includes: mixing a solid organic carbon source and an organic solvent to obtain a slurry; mixing the slurry with the first silicon-containing matrix through a fourth ball milling process or a homogenization process; then drying by spray drying or rotary evaporation, and then performing a carbon coating process by a second roasting and carbonization process; optionally, the homogenization process includes: a homogenization speed of 100 to 2000 r / min and a homogenization time of 1 to 72 h; optionally, the spray drying process includes an inlet temperature of 100 to 300 ° C and an outlet temperature of 50 to 200 ° C. The carrier gas flow rate is 10 to 100 L / min and the pressure is -0.10 to -0.05 MPa; optionally, the conditions of the second calcination carbonization treatment include: a calcination temperature of 500 to 1500° C., a calcination time of 2 to 72 hours, and a calcination atmosphere of one or more inert gases selected from argon or nitrogen; preferably, the calcination temperature is 700 to 1200° C., and the calcination time is 2 to 5 hours; optionally, the organic solvent is selected from one or more of ethanol, hexane, tetrahydrofuran and benzene. Preferably, the amount of the organic solvent is 1 to 150 g relative to 1 g of the organic carbon source;

[0019] Optionally, the vapor phase CVD deposition process includes: placing the first silicon-containing substrate in an atmosphere furnace, introducing a gaseous organic carbon source to perform carbon coating treatment by pyrolysis deposition; Optionally, the pyrolysis deposition conditions include: pyrolysis temperature of 300-1200° C., time of 0.5-72 h, and pressure of 0.01-0.5 MPa;

[0020] Preferably, the carbon coating layer of the carbon-coated silicon-containing matrix prepared in step S1 has a thickness of 1 to 5000 nm, preferably 10 to 500 nm.

[0021] Optionally, in step S2, the weight ratio of the metallic lithium to the second silicon-containing matrix is ​​0.1 to 100:1, preferably 1 to 10:1;

[0022] Optionally, the second silicon-containing matrix is ​​selected from one or more of SiOy and silicon, 0.5≤y<2;

[0023] The metallic lithium is selected from one or more of lithium ingots, lithium wires, lithium powders or lithium sheets.

[0024] Optionally, in step S2, the conditions for the first ball milling treatment include: a rotation speed of 300 to 2000 r / min, a time of 6 to 72 h, and a ball-to-material ratio of 1 to 20:1. Preferably, the rotation speed is 500 to 800 r / min, the time is 12 to 24 h, and the ball-to-material ratio is 10 to 20:1.

[0025] Optionally, in step S3, the first organic solvent is selected from one or more of tetrahydrofuran, hexane, cyclohexane, benzene and naphthalene;

[0026] Preferably, the amount of the first organic solvent used is 1 to 100 mL, preferably 10 to 50 mL, relative to 1 g of the pre-lithium precursor.

[0027] Optionally, in step S3, the conditions of the second ball milling treatment include: a rotation speed of 200 to 1000 r / min, preferably 200 to 500 r / min; a time of 6 to 72 hours, preferably 10 to 20 hours; a ball to material ratio of 1 to 20:1, preferably 10 to 20:1;

[0028] Optionally, in step S3, the pre-lithium solution includes lithium-containing particles, and the particle size of the lithium-containing particles is 20 to 500 nm, preferably 50 to 200 nm.

[0029] Optionally, in step S4, the weight ratio of the pre-lithium solution to the carbon-coated silicon-containing matrix is ​​0.1 to 100:1, preferably 1 to 50:1.

[0030] Optionally, in step S4, the pre-lithiation treatment adopts a ball milling process;

[0031] Optionally, the conditions of the pre-lithiation treatment include: a rotation speed of 100 to 500 r / min, preferably 100 to 300 r / min; a time of 6 to 72 hours, preferably 12 to 36 hours, and a ball-to-material ratio of 1 to 20:1, preferably 5 to 20:1;

[0032] Optionally, the method further comprises: washing the product obtained from the pre-lithiation treatment in step S4 with a second organic solvent to perform stabilization treatment;

[0033] Optionally, the second organic solvent is selected from one or more of tetrahydrofuran, hexane, cyclohexane and benzene; preferably, the amount of the second organic solvent used is 0.1 to 100 mL, preferably 1 to 10 mL, relative to 1 g of the product obtained by pre-lithiation treatment.

[0034] A second aspect of the present disclosure provides a pre-lithiation negative electrode material prepared according to the method described in the first aspect of the present disclosure.

[0035] Optionally, the pre-lithiation negative electrode material comprises a lithium component, a silicon component and a carbon component; wherein, based on the total weight of the pre-lithiation negative electrode material, the content of the lithium component is 1 to 50 weight %, the content of the silicon component is 10 to 90 weight %, and the content of the carbon component is 1 to 50 weight %; preferably, the content of the lithium component is 1 to 10 weight %, the content of the silicon component is 50 to 90 weight %, and the content of the carbon component is 4 to 20 weight %;

[0036] Optionally, the average particle size of the pre-lithiation negative electrode material is 1 to 100 μm, and the BET specific surface area is 1 to 20 m 2 / g, total pore volume is 0.001~0.05cm 3 / g.

[0037] A third aspect of the present disclosure provides a negative electrode, which includes the pre-lithiation negative electrode material described in the second aspect of the present disclosure.

[0038] A fourth aspect of the present disclosure provides a lithium-containing battery, which includes the negative electrode described in the third aspect of the present disclosure.

[0039] Through the above technical scheme, the present disclosure provides a pre-lithiation negative electrode material and a preparation method thereof, a negative electrode and a lithium-containing battery. The present disclosure performs a carbon coating treatment on a first silicon-containing matrix and an organic carbon source to obtain a carbon-coated silicon-containing matrix for subsequent pre-lithiation treatment, and carbon is coated on the surface of the silicon-containing matrix, which can isolate the lithium silicate or lithium-silicon alloy formed by pre-lithiation from the outside world such as air and slurry, thereby improving the stability of the pre-lithiation material and thus facilitating the improvement of cycle stability. The present disclosure performs ball milling on metallic lithium and a second silicon-containing matrix to obtain a pre-lithiation precursor, and then performs liquid-phase ball milling with an organic solvent to obtain a pre-lithiation solution. The present disclosure uses the obtained pre-lithiation solution as a pre-lithiation agent to pre-lithiate the carbon-coated silicon-containing matrix. The particle size of the metallic lithium powder in the pre-lithiation solution is small, and the pre-lithiation is more uniform during pre-lithiation application, and it is easy to form a uniformly distributed lithium silicate, thereby improving the kinetics of lithium metal deintercalation and ion extraction during pre-lithiation, and having a better pre-lithiation effect. It can also reduce the loss of active silicon and gram capacity, and significantly improve the first efficiency while ensuring a high gram capacity. The present invention uses the pre-lithiation solution directly as the pre-lithiation agent for the silicon oxide material, which has a simple process, easy operation, environmentally friendly process, low cost, and is conducive to large-scale production.

[0040] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following detailed description, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0042] Figure 1 This is a scanning electron microscope photograph of a pre-lithiated silicon oxide negative electrode material prepared according to the method of disclosed Example 1;

[0043] Figure 2 This is a transmission electron microscope photograph of a pre-lithiated silicon oxide negative electrode material prepared according to the method of disclosed Example 1;

[0044] Figure 3 The Li 1s X-ray photoelectron high-resolution scanning energy spectrum of the pre-lithiated silicon oxide negative electrode material prepared according to the method of the disclosed embodiment 1;

[0045] Figure 4 The Li 1s X-ray photoelectron high-resolution scanning energy spectrum of the carbon-coated silicon-oxygen negative electrode material prepared according to the method disclosed in Preparation Example 1;

[0046] Figure 5 The C1s X-ray photoelectron high-resolution scanning spectrum of the pre-lithiated silicon-oxygen negative electrode material prepared according to the method disclosed in Example 1;

[0047] Figure 6 The C1s X-ray photoelectron high-resolution scanning spectrum of the carbon-coated silicon-oxygen negative electrode material prepared according to the method disclosed in Preparation Example 1;

[0048] Figure 7 The first charge-discharge curve of the pre-lithiated silicon oxide negative electrode material prepared according to the method of the disclosed embodiment 1 at a current density of 0.2C;

[0049] Figure 8 This is the first charge and discharge curve of the carbon-coated silicon oxide negative electrode material prepared according to the method of the disclosed preparation example 1 at a current density of 0.2C. DETAILED DESCRIPTION

[0050] The following describes the specific embodiments of the present disclosure in detail. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present disclosure and are not intended to limit the present disclosure.

[0051] A first aspect of the present disclosure provides a method for preparing a pre-lithiation negative electrode material, comprising the following steps:

[0052] S1, contacting a first silicon-containing matrix with an organic carbon source and performing a carbon coating treatment to obtain a carbon-coated silicon-containing matrix;

[0053] S2, contacting metallic lithium with a second silicon-containing matrix and performing a first ball milling process to obtain a pre-lithium precursor;

[0054] S3, mixing the pre-lithium precursor with a first organic solvent, and performing a second ball milling process to obtain a pre-lithium solution;

[0055] S4, contacting the pre-lithiation solution with the carbon-coated silicon-containing matrix obtained in step S1 to perform a pre-lithiation treatment.

[0056] The present disclosure provides a preparation method for a pre-lithiation negative electrode material, wherein a first silicon-containing matrix and an organic carbon source are subjected to carbon coating treatment to obtain a carbon-coated silicon-containing matrix for subsequent pre-lithiation treatment, and carbon is coated on the surface of the silicon-containing matrix, which can isolate the lithium silicate or lithium silicon alloy formed by pre-lithiation from the outside world such as air and slurry, thereby improving the stability of the pre-lithiation material and thus facilitating the improvement of cycle stability; the present disclosure ball-mills metallic lithium and a second silicon-containing matrix to obtain a pre-lithiation precursor, and then liquid-phase ball-mills are performed with an organic solvent to obtain a pre-lithiation solution; the present disclosure uses the obtained pre-lithiation solution as a pre-lithiation agent to pre-lithiate the carbon-coated silicon-containing matrix; the metallic lithium powder in the pre-lithiation solution has a small particle size, and the pre-lithiation is relatively uniform during pre-lithiation application, and it is easy to form uniformly distributed lithium silicate, thereby improving the kinetics of lithium metal deintercalation and ion extraction during pre-lithiation, and achieving a better pre-lithiation effect; the loss of active silicon and gram capacity can also be reduced, and the first efficiency is significantly improved while ensuring a high gram capacity. The present invention uses the pre-lithiation solution directly as the pre-lithiation agent for the silicon oxide material, which has a simple process, easy operation, environmentally friendly process, low cost, and is conducive to large-scale production.

[0057] In the present disclosure, step S2 is performed under protective atmosphere conditions, wherein the protective atmosphere comprises one or more of nitrogen, helium, neon, argon, krypton, and xenon; the protective atmosphere has a water content of less than 0.1% by weight and an oxygen content of less than 0.1% by weight. In the above embodiment, the use of the preferred protective atmosphere can further prevent the reaction of lithium with oxygen and water in the environment, thereby making the material structure more stable.

[0058] In one embodiment, the first silicon-containing matrix is ​​selected from one or more of SiOx and silicon, and 0.5≤x<2.

[0059] In one embodiment, silicon is in the form of powder, the average particle size of the silicon powder is 0.1 to 20 μm, and the BET specific surface area is 1 to 20 m 2 / g; the SiOx is a powder, the average particle size of the SiOx powder is 0.1 to 20 μm; the BET specific surface area is 1 to 20 m 2 / g.

[0060] In one embodiment, the organic carbon source comprises a solid organic carbon source or a gaseous organic carbon source;

[0061] Optionally, the solid organic carbon source is selected from one or more of a polymer carbon source, a petroleum carbon source, a sugar carbon source, a graphite carbon source and other carbon sources;

[0062] Preferably, the polymer carbon source comprises one or more of phenolic resin, epoxy resin, polyvinyl pyrrolidone and polyvinyl alcohol;

[0063] Preferably, the petroleum carbon source includes one or more of asphalt, petroleum coke and needle coke;

[0064] Preferably, the carbohydrate carbon source includes one or more of glucose, sucrose and fructose;

[0065] Preferably, the other carbon source is selected from one or more of sodium carboxymethyl cellulose, polyvinyl alcohol and carboxy styrene butadiene latex;

[0066] Optionally, the gaseous organic carbon source is selected from one or more gaseous hydrocarbons. Preferably, the gaseous organic carbon source is selected from one or more methane, acetylene and ethylene.

[0067] In one embodiment, the weight ratio of the first silicon-containing matrix to the solid organic carbon source is 1:0.01-1, preferably 1:0.05-0.2; carbon coating treatment according to the preferred weight ratio in this embodiment can obtain a carbon-coated silicon-containing matrix with better carbon coating effect.

[0068] In one embodiment, the carbon coating process in step S1 is selected from a solid phase coating process, a liquid phase coating process and a vapor phase CVD deposition process.

[0069] The solid-phase coating process, liquid-phase coating process and vapor-phase CVD deposition process in the present disclosure are operations well known to those skilled in the art.

[0070] In a specific embodiment, the solid phase coating process includes: mixing and coating the first silicon-containing matrix and the solid organic carbon source through a third ball milling process or a melt coating process, and then performing a carbon coating process through a first roasting carbonization process; optionally, the conditions of the third ball milling process include: a rotation speed of 100 to 1000 r / min, a time of 2 to 72 h, a ball-to-material ratio of 1 to 50:1, preferably, a rotation speed of 200 to 500 r / min, a time of 5 to 24 h, and a ball-to-material ratio of 1 to 50:1. The material ratio is 10 to 30:1; optionally, the conditions of the melt cladding treatment include: a temperature of 200 to 1000°C, a time of 2 to 72 hours, preferably, a temperature of 200 to 500°C, and a time of 2 to 5 hours; optionally, the conditions of the first calcination carbonization treatment include: a temperature of 500 to 1500°C, a time of 2 to 72 hours, and a calcination atmosphere of one or more inert gases such as argon or nitrogen; preferably, a temperature of 700 to 1200°C, and a time of 2 to 5 hours;

[0071] Optionally, the liquid phase coating process includes: mixing a solid organic carbon source and an organic solvent to obtain a slurry; mixing the slurry with the first silicon-containing matrix through a fourth ball milling treatment or a homogenization treatment; then drying by spray drying or rotary evaporation, and then performing a carbon coating treatment by a second calcination carbonization treatment; optionally, the conditions of the fourth ball milling treatment include: a rotation speed of 50 to 1000 r / min, a time of 1 to 72 h, a ball-to-material ratio of 1 to 30:1, preferably, a rotation speed of 100 to 300 r / min, a time of 2 to 5 h, and a ball-to-material ratio of 10 to 20:1; optionally, the conditions of the homogenization treatment include a rotation speed of 100 to 2000 r / min, a time of 1 to 72 h; optionally, the conditions of the spray drying treatment include The inlet temperature is 100-300°C, the outlet temperature is 50-200°C, the carrier gas flow rate is 10-100 L / min, and the pressure is -0.10 to -0.05 MPa; optionally, the conditions of the rotary evaporation treatment include a rotary evaporation temperature of 50-200°C and a rotation speed of 10-100 r / min; optionally, the conditions of the second calcination carbonization treatment include: a temperature of 500-1500°C, a time of 2-72h, and a calcination atmosphere of one or more inert gases such as argon or nitrogen; preferably, the temperature is 700-1200°C and the time is 2-5h; optionally, the organic solvent is selected from one or more of ethanol, hexane, tetrahydrofuran and benzene. Preferably, the amount of the organic solvent is 150g relative to 1g of the organic carbon source;

[0072] Optionally, the vapor phase CVD deposition process includes: placing the first silicon-containing substrate in an atmosphere furnace, introducing a gaseous organic carbon source to perform carbon coating treatment through cracking and deposition; optionally, the cracking and deposition conditions include a cracking temperature of 300 to 1200°C, a time of 0.5 to 72 hours, and a pressure of 0.01 to 0.5 MPa.

[0073] In a preferred embodiment, the carbon coating layer of the carbon-coated silicon-containing substrate prepared in step S1 has a thickness of 1 to 5000 nm, preferably 10 to 500 nm. In the present disclosure, the thickness of the carbon coating layer of the carbon-coated silicon-containing substrate is measured by transmission electron microscopy.

[0074] In one embodiment, in step S2, the weight ratio of the lithium metal to the second silicon-containing matrix is ​​0.1 to 100:1, preferably 1 to 10:1. The present disclosure ball-mills the lithium metal and the second silicon-containing matrix to obtain a pre-lithiation particle precursor with a smaller and more uniform particle size. During pre-lithiation applications, pre-lithiation is uniform, avoiding excessive pre-lithiation in some areas of the material, loss of active silicon, and loss of gram capacity. Processing according to the optimized weight ratio of lithium metal to the second silicon-containing matrix in this embodiment can achieve better pre-lithiation effects.

[0075] In one embodiment, the second silicon-containing matrix is ​​selected from one or more of SiOy and silicon, 0.5≤y<2;

[0076] The metallic lithium is selected from one or more of lithium ingots, lithium wires, lithium powders or lithium sheets.

[0077] In one embodiment, in step S2, the conditions of the first ball milling treatment include: a rotation speed of 300 to 2000 r / min, a time of 6 to 72 hours, and a ball-to-material ratio of 1 to 20:1. Preferably, the rotation speed is 500 to 800 r / min, the time is 12 to 24 hours, and the ball-to-material ratio is 10 to 20:1.

[0078] In one embodiment, in step S3, the first organic solvent is selected from one or more of tetrahydrofuran, hexane, cyclohexane, benzene, and naphthalene; preferably, the amount of the first organic solvent used is 1 to 100 mL, preferably 10 to 50 mL, relative to 1 g of the pre-lithiation precursor. The present disclosure wet-ball mills the pre-lithiation precursor with the first organic solvent to obtain a uniform pre-lithiation slurry, thereby avoiding excessive pre-lithiation in some regions of the material, loss of active silicon, and loss of gram capacity.

[0079] In one embodiment, in step S3, the conditions of the second ball milling treatment include: a rotation speed of 200 to 1000 r / min, preferably 200 to 500 r / min; a time of 6 to 72 hours, preferably 10 to 20 hours; and a ball-to-material ratio of 1 to 20:1, preferably 10 to 20:1.

[0080] In a preferred embodiment, the pre-lithium solution includes lithium-containing particles, and the particle size of the lithium-containing particles is 20 to 500 nm, preferably 50 to 200 nm.

[0081] In one embodiment, in step S4, the weight ratio of the pre-lithiation solution to the carbon-coated silicon-containing matrix is ​​0.1 to 100:1, preferably 1 to 50:1. The present disclosure performs a pre-lithiation and stabilization treatment on the pre-lithiation solution and the carbon-coated silicon-containing matrix, so that the metallic lithium in the pre-lithiation solution reacts with the oxygen in the carbon-coated silicon-containing matrix to form lithium silicate, thereby reacting the irreversible lithium-consuming phase in the silicon-oxygen material in advance.

[0082] In a specific embodiment, in step S4, the pre-lithiation treatment adopts a ball milling process;

[0083] Optionally, the conditions of the pre-lithiation treatment include: a rotation speed of 100 to 500 r / min, preferably 100 to 300 r / min; a time of 6 to 72 h, preferably 12 to 36 h, and a ball-to-material ratio of 1 to 20:1, preferably 5 to 20:1.

[0084] In a preferred embodiment, the method further comprises: washing the product obtained from the pre-lithiation treatment in step S4 with a second organic solvent to perform stabilization treatment;

[0085] Optionally, the second organic solvent is selected from one or more of tetrahydrofuran, hexane, cyclohexane and benzene; preferably, the amount of the second organic solvent used is 0.1 to 100 mL, preferably 1 to 10 mL, relative to 1 g of the product obtained by the pre-lithiation treatment. The present disclosure uses a second organic solvent for stabilization treatment, which has the effect of removing incompletely reacted active lithium in the pre-lithiation product, improving the stability of the pre-lithiation product, and avoiding gas production problems caused by excessively high pH when the pre-lithiation material is slurried.

[0086] A second aspect of the present disclosure provides a pre-lithiation negative electrode material prepared according to the method described in the first aspect of the present disclosure.

[0087] In one embodiment, the pre-lithiation negative electrode material has the following structure: the pre-lithiation negative electrode material has a core-shell structure of a core and an outer shell; wherein the core contains silicon or silicon oxide and a lithium element component, and the lithium element component is selected from one or two of lithium silicates and silicon-lithium alloys; the surface of the core has an outer shell formed of a carbon coating film.

[0088] In one embodiment, the pre-lithiation negative electrode material comprises lithium, silicon, and carbon; wherein, based on the total weight of the pre-lithiation negative electrode material, the lithium content is 1-50% by weight, the silicon content is 10-90% by weight, and the carbon content is 1-50% by weight; preferably, the lithium content is 1-10% by weight, the silicon content is 50-90% by weight, and the carbon content is 4-20% by weight. In the present disclosure, the content of each element in the pre-lithiation negative electrode material is determined by the ICP test method.

[0089] In one embodiment, the average particle size of the pre-lithiation negative electrode material is 1 to 100 μm, the average pore size is 1 to 50 nm, and the BET specific surface area is 1 to 20 m 2 / g, total pore volume is 0.001~0.05cm 3 / g; Preferably, the average particle size of the pre-lithiation negative electrode material is 1 to 10 μm, the average pore size is 1 to 10 nm, and the BET specific surface area is 2 to 10 m 2 / g, total pore volume of 0.01~0.03cm 3 / g.

[0090] A third aspect of the present disclosure provides a negative electrode, comprising the pre-lithiation negative electrode material described in the second aspect of the present disclosure.

[0091] According to the present disclosure, the negative electrode of the lithium-ion battery can be prepared using methods known in the art. For example, the negative electrode can be prepared by slurry coating, wherein the slurry includes the negative electrode material provided in the present disclosure, a conductive agent, a binder, etc. The conductive agent and binder are conventionally selected in the art.

[0092] A fourth aspect of the present disclosure provides a lithium-containing battery, comprising the negative electrode described in the third aspect of the present disclosure.

[0093] According to the present disclosure, lithium-containing batteries can be assembled using methods known in the art.

[0094] The present disclosure is further illustrated below by way of examples, but the present disclosure is not limited thereby.

[0095] In the following examples, unless otherwise specified, the raw materials used are commercially available products.

[0096] In the following examples, the specific testing methods are as follows:

[0097] In the material, the contents of lithium and silicon oxide are calculated based on the preparation addition amounts; the carbon content is obtained by testing with a thermogravimetric analyzer.

[0098] The average particle size of the material is measured using an optical particle size analyzer, using the Mastersizer 3000 as the instrument model.

[0099] The BET specific surface area, average pore size and pore volume of the material were tested using a surface area and pore size analyzer JW-BK100;

[0100] The SEM test method is scanning electron microscopy, and the instrument model is S4800 from Hitachi, Japan;

[0101] The XPS test method is X-ray photoelectron spectrometer, the instrument model is VG ESCALAB;

[0102] The electrochemical cycling performance was tested using the Blue Electric test system, with the instrument model being CT3001A.

[0103] The following preparation examples are used to illustrate the preparation of carbon-coated silicon-containing substrates.

[0104] Preparation Example 1

[0105] This preparation example is used to illustrate the preparation of carbon-coated silicon oxide negative electrode material powder, specifically comprising: dispersing 20 g of silicon oxide, 0.5 g of phenolic resin and 0.5 g of asphalt (the weight ratio of the first silicon-containing matrix to the organic carbon source is 1:0.05) in 150 g of anhydrous ethanol, stirring at a speed of 500 r / min for 1 hour, and then spray granulating. The conditions of the spray granulation include: an inlet temperature of 300°C, an outlet temperature of 200°C, a carrier gas (argon) flow rate of 45 L / min, a pressure of -0.05 MPa, and calcining at 900°C for 3 hours to obtain a carbon-coated silicon oxide negative electrode material, recorded as SiO@C-1, with a carbon coating layer thickness of 5 to 10 nm. The thickness of the carbon coating layer can be obtained by Figure 2 get.

[0106] Preparation Example 2

[0107] This preparation example is used to illustrate the preparation of carbon-coated silicon oxide negative electrode material powder, specifically comprising: dispersing 20 g of silicon oxide, 1 g of phenolic resin, and 1 g of asphalt (the weight ratio of the first silicon-containing matrix to the organic carbon source is 1:0.1) in 150 g of anhydrous ethanol, stirring at a speed of 500 r / min for 1 hour, and then spray granulating. The spray granulation conditions include: an inlet temperature of 250°C, an outlet temperature of 180°C, a carrier gas (argon) flow rate of 30 L / min, a pressure of -0.05 MPa, and calcining at 800°C for 3 hours to obtain a carbon-coated silicon oxide negative electrode material, recorded as SiO@C-2, with a carbon coating layer thickness of 20 to 30 nm.

[0108] Preparation Example 3

[0109] This preparation example is used to illustrate the preparation of carbon-coated silicon oxide negative electrode material powder, specifically comprising: placing 20 g of silicon oxide in a tube furnace, raising the temperature to 800°C, and introducing acetylene gas for 30 minutes, wherein the weight volume ratio of the first silicon-containing matrix to the gaseous organic carbon source is 2L gaseous organic carbon source / 1g first silicon-containing matrix, the pressure is 0.1 MPa, and the duration is 30 minutes. After cooling, a carbon-coated silicon oxide negative electrode material is obtained, which is recorded as SiO@C-3, and the thickness of the carbon coating layer is 10 to 20 nm.

[0110] Preparation Example 4

[0111] This preparation example is used to illustrate the preparation of carbon-coated silicon oxide negative electrode material powder, specifically comprising: dispersing 20 g of silicon oxide, 20 g of phenolic resin and 20 g of asphalt (the weight ratio of the first silicon-containing matrix to the organic carbon source is 1:2) in 150 g of anhydrous ethanol, stirring at a speed of 500 r / min for 1 hour, and then spray granulating. The spray granulation conditions include: an inlet temperature of 200°C, an outlet temperature of 150°C, a carrier gas (argon) flow rate of 50 L / min, a pressure of -0.05 MPa, and calcining at 900°C for 3 hours to obtain a carbon-coated silicon oxide negative electrode material, recorded as SiO@C-4, with a carbon coating layer thickness of approximately 6000 nm.

[0112] Preparation Example 5

[0113] This preparation example is used to illustrate the preparation of carbon-coated silicon oxide negative electrode material powder, specifically including:

[0114] 20 g of silicon oxide, 0.5 g of phenolic resin and 0.5 g of asphalt (the weight ratio of the first silicon-containing matrix to the organic carbon source is 1:0.05) are melt-coated. The melt-coating conditions are: temperature 350°C, time 3 h, and then calcined at 900°C for 3 h to obtain a carbon-coated silicon oxygen negative electrode material, denoted as SiO@C-1, with a carbon coating layer thickness of 5 to 10 nm, and denoted as SiO@C-5, with a carbon coating layer thickness of approximately 10 nm.

[0115] Example 1

[0116] Under an argon atmosphere, 2g of metallic lithium ingot and 0.2g of silicon dioxide (average particle size of 2-10μm) were weighed and placed in a zirconia ball mill (the weight ratio of metallic lithium to the second silicon-containing matrix was 10:1). After sealing, the mixture was transferred to a planetary ball mill for ball milling. The ball-to-material ratio was 20:1, the zirconium balls had diameters of 5.5mm, 3.0mm, and 2.0mm, and the ratio was 2:5:3. The ball milling speed was 500 rpm and the ball milling time was 12 hours to obtain a pre-lithium precursor. Cyclohexane was then added at a ratio of 14mL of the first organic solvent to 1g of the pre-lithium precursor and the ball milling speed was 300 rpm. After 10 hours of ball milling, a pre-lithium solution was obtained. The particle size of the lithium-containing particles in the pre-lithium solution was 50-200nm. The SiO@C-1 powder prepared in Preparation Example 1 was added to the pre-lithiation solution, the weight ratio of the pre-lithiation solution to SiO@C-1 was 1.5:1, and the ball milling pre-lithiation treatment was continued at a ball milling speed of 100 rpm. After ball milling for 12 hours, the pre-lithiation silicon oxide negative electrode material was obtained by centrifugation washing (the washing solvent was tetrahydrofuran, and the amount of tetrahydrofuran was 10 mL relative to 1 g of the product obtained by the pre-lithiation treatment) and drying (drying temperature was 80°C and drying time was 12 h).

[0117] Figure 1The SEM image of the pre-lithiated silicon oxide negative electrode material prepared according to the method of Example 1. Figure 1 It can be seen that the pre-lithiated silicon oxide negative electrode material prepared in this embodiment is in a granular form, and the average particle size after statistics is 8.52 μm.

[0118] Figure 2 TEM image of the pre-lithiated silicon oxide negative electrode material prepared according to the method of Example 1. Figure 2 It can be seen that the edge of the material has a layered structure, which is the carbon coating layer wrapped outside; and Figure 2 This indicates that lithium silicate is distributed in various parts of the silicon matrix and is not limited to pre-lithiation on the silicon surface. The pre-lithiation is relatively uniform, which can avoid the occurrence of bubbles during slurry preparation.

[0119] Figure 3 The Li 1s X-ray photoelectron high-resolution scanning spectrum of the pre-lithiated silicon oxide negative electrode material prepared according to Example 1 is compared. Figure 4 The carbon-coated silicon oxide material SiO@C-1 obtained in Example 1 was prepared. The pre-lithiated silicon oxide negative electrode material prepared in this example had obvious characteristic peaks of Li, indicating that lithium was successfully introduced into the silicon oxide negative electrode material.

[0120] Figure 5 The C1s X-ray photoelectron high-resolution scanning spectrum of the pre-lithiated silicon oxide negative electrode material prepared according to the method of Example 1 is compared. Figure 6 The carbon-coated silicon oxide material SiO@C-1 obtained in Example 1 was prepared. In addition to the diffraction peak of carbon in the pre-lithiated silicon oxide negative electrode material, the pre-lithiated silicon oxide negative electrode material prepared in this example also showed an obvious characteristic peak of Li2CO3 (at a binding energy of 289.2 eV), further indicating that lithium was successfully introduced into the silicon oxide negative electrode material.

[0121] Comparative Example 1

[0122] This comparative example refers to the preparation method in Example 1, and differs from Example 1 in that the added SiO@C-1 is replaced with pure silicon 2 oxide. The rest of the process is the same as that in Example 1 to prepare a pre-lithiated silicon oxide negative electrode material.

[0123] Comparative Example 2

[0124] This comparative example refers to the preparation method in Example 1, but differs from Example 1 in that metallic lithium is not added. The remaining processes are the same as those in Example 1, and a negative electrode material free of lithium is prepared.

[0125] Comparative Example 3

[0126] This comparative example refers to the preparation method in Example 1, and differs from Example 1 in that the wet ball milling process of mixing the pre-lithiation precursor with the first organic solvent is replaced by dry ball milling, that is, no organic solvent is added. The rest of the process is the same as Example 1 to prepare a pre-lithiation silicon oxide negative electrode material.

[0127] Example 2

[0128] Under an argon atmosphere, 2g of metallic lithium ingot and 0.2g of silicon (average particle size of 0.5-5μm) were weighed and placed in a zirconia ball mill (the weight ratio of metallic lithium to the second silicon-containing matrix was 10:1). After sealing, the mixture was transferred to a planetary ball mill for ball milling. The ball-to-material ratio was 20:1, the zirconium balls had diameters of 5.5mm, 3.0mm, and 2.0mm, and the ratio was 2:5:3. The ball milling speed was 500 rpm and the ball milling time was 12 hours to obtain a pre-lithium precursor. Tetrahydrofuran was then added at a ratio of 23mL of the first organic solvent to 1g of the pre-lithium precursor and the ball milling speed was 300 rpm. After 24 hours of ball milling, a pre-lithium solution was obtained. The particle size of the lithium-containing particles in the pre-lithium solution was 50-150nm. The SiO@C-1 powder prepared in Preparation Example 1 was added to the pre-lithiation solution, the weight ratio of the pre-lithiation solution to SiO@C-1 was 2.5:1, and the ball milling pre-lithiation treatment was continued at a ball milling speed of 100 rpm. After ball milling for 12 hours, the pre-lithiation silicon oxide negative electrode material was obtained by centrifugation washing (the washing solvent was cyclohexane) and drying.

[0129] Example 3

[0130] Under an argon atmosphere, 2g of metallic lithium ingot and 0.2g of silicon dioxide (average particle size of 2-10μm) were weighed and placed in a zirconia ball mill (the weight ratio of metallic lithium to the second silicon-containing matrix was 10:1). After sealing, the mixture was transferred to a planetary ball mill for ball milling. The ball-to-material ratio was 20:1, the zirconium balls had diameters of 5.5mm, 3.0mm, and 2.0mm, and the ratio was 2:5:3. The ball milling speed was 300 rpm and the ball milling time was 24 hours to obtain a pre-lithium precursor. Hexane was then added at a ratio of 55mL of the first organic solvent to 1g of the pre-lithium precursor and the ball milling speed was 300 rpm. After 24 hours of ball milling, a pre-lithium solution was obtained. The particle size of the lithium-containing particles in the pre-lithium solution was 50-100nm. The SiO@C-2 powder prepared in Preparation Example 2 was added to the pre-lithiation solution, the weight ratio of the pre-lithiation solution to SiO@C-2 was 3:1, and the ball milling pre-lithiation treatment was continued at a ball milling speed of 300 rpm. After ball milling for 12 hours, the pre-lithiation silicon oxide negative electrode material was obtained by centrifugal washing (the washing solvent was hexane) and drying.

[0131] Example 4

[0132] Under an argon atmosphere, 2g of metallic lithium ingot and 0.2g of silicon dioxide (average particle size of 2-10μm) were weighed and placed in a zirconia ball mill (the weight ratio of metallic lithium to the second silicon-containing matrix was 10:1). After sealing, the mixture was transferred to a planetary ball mill for ball milling. The ball-to-material ratio was 20:1, the zirconium balls had diameters of 5.5mm, 3.0mm, and 2.0mm, and the ratio was 2:5:3. The ball milling speed was 500 rpm and the ball milling time was 12 hours to obtain a pre-lithium precursor. 220mL of cyclohexane was then added at a ratio of 100mL of the first organic solvent to 1g of the pre-lithium precursor and the ball milling speed was 300 rpm. After 10 hours of ball milling, a pre-lithium solution was obtained. The particle size of the lithium-containing particles in the pre-lithium solution was 50-200nm. The SiO@C-3 powder prepared in Preparation Example 1 was added to the pre-lithiation solution, the weight ratio of the pre-lithiation solution to SiO@C-3 was 11:1, and the ball milling pre-lithiation treatment was continued at a ball milling speed of 100 rpm. After ball milling for 12 hours, the pre-lithiation silicon oxide negative electrode material was obtained by centrifugation washing (the washing solvent was tetrahydrofuran) and drying.

[0133] Example 5

[0134] This embodiment refers to the preparation method in Example 1, and differs from Example 1 in that the added SiO@C-1 is replaced by SiO@C-4 prepared in Preparation Example 4, and the rest of the process is the same as in Example 1 to prepare a pre-lithiated silicon oxide negative electrode material.

[0135] Example 6

[0136] This embodiment refers to the preparation method in Example 1, and differs from Example 1 in that the added SiO@C-1 is replaced with SiO@C-5 prepared in Preparation Example 5, and the rest of the process is the same as in Example 1 to prepare a pre-lithiated silicon oxide negative electrode material.

[0137] Example 7

[0138] This embodiment refers to the method in Example 1, and the difference from Example 1 is that the raw material ratio is changed, specifically including:

[0139] Under an argon environment, 2g of metallic lithium ingot and 0.1g of silicon dioxide (average particle size of 2-10μm) were weighed and placed in a zirconia ball mill (the weight ratio of metallic lithium to the second silicon-containing matrix was 20:1). After sealing, the mixture was transferred to a planetary ball mill for ball milling to obtain a pre-lithium precursor. 200mL of cyclohexane was then added at a ratio of 100mL of the first organic solvent to 1g of the pre-lithium precursor and ball milling was continued. After ball milling, the particle size of the lithium-containing particles in the pre-lithium solution was 20-150nm. The SiO@C-1 powder prepared in Preparation Example 1 was added to the pre-lithium solution. The weight ratio of the pre-lithium solution to SiO@C-1 was 80:1. The pre-lithiation treatment was continued by ball milling (the cleaning solvent was tetrahydrofuran, and the amount of tetrahydrofuran used was 20mL relative to 1g of the product obtained by the pre-lithiation treatment). After drying, the pre-lithiation silicon oxide negative electrode material was obtained.

[0140] Example 8

[0141] This embodiment refers to the method in Example 1, and the difference from Example 1 is that the raw material ratio is changed, specifically including:

[0142] Under an argon atmosphere, 1g of metallic lithium ingot and 20g of silicon dioxide (average particle size of 2-10μm) were weighed and placed in a zirconia ball mill (the weight ratio of metallic lithium to the second silicon-containing matrix was 0.05:1). After sealing, the mixture was transferred to a planetary ball mill for ball milling to obtain a pre-lithium precursor. 10mL of cyclohexane was then added at a ratio of 0.5mL of the first organic solvent to 1g of the pre-lithium precursor and ball milling was continued. The particle size of the lithium-containing particles in the pre-lithium solution was 500-1000nm. The SiO@C-1 powder prepared in Preparation Example 1 was added to the pre-lithium solution, with a weight ratio of the pre-lithium solution to SiO@C-1 of 0.06:1. The pre-lithiation treatment was continued by ball milling (the cleaning solvent was tetrahydrofuran, and the amount of tetrahydrofuran used was 10mL relative to 1g of the pre-lithiation product). After drying, the pre-lithiated silicon oxide negative electrode material was obtained.

[0143] Example 9

[0144] This embodiment refers to the method in embodiment 1, and the difference from embodiment 1 is that the process conditions are changed, specifically including:

[0145] Under an argon atmosphere, 2g of metallic lithium ingot and 0.2g of silicon dioxide (average particle size of 2-10μm) were weighed and placed in a zirconia ball mill (the weight ratio of metallic lithium to the second silicon-containing matrix was 10:1). After sealing, the mixture was transferred to a planetary ball mill for ball milling. The ball-to-material ratio was 5:1, the zirconium balls had diameters of 5.5mm, 3.0mm, and 2.0mm, and the ratio was 2:5:3. The ball milling speed was 200 rpm and the ball milling time was 5 hours to obtain a pre-lithium precursor. 30mL of cyclohexane was then added at a ratio of 14mL of the first organic solvent to 1g of the pre-lithium precursor and the ball milling speed was 100 rpm. After 2 hours of ball milling, a pre-lithium solution was obtained. The particle size of the lithium-containing particles in the pre-lithium solution was 1000-5000nm. The SiO@C-1 powder prepared in Preparation Example 1 was added to the pre-lithiation solution, the weight ratio of the pre-lithiation solution to SiO@C-1 was 1.5:1, and the ball milling pre-lithiation treatment was continued at a ball milling speed of 100 rpm. After ball milling for 5 hours, the pre-lithiation silicon oxide negative electrode material was obtained by centrifugation washing (the washing solvent was tetrahydrofuran, and the amount of tetrahydrofuran was 10 mL relative to 1 g of the product obtained by the pre-lithiation treatment) and drying (drying temperature was 80°C and drying time was 10 h).

[0146] The test data of component contents and structural parameters of the pre-lithiated silicon oxide negative electrode materials prepared in the above examples and comparative examples are listed in Table 1 below.

[0147] Table 1

[0148]

[0149]

[0150] Test Case

[0151] This test example is used to illustrate the electrochemical performance of the products obtained in the examples and comparative examples when used as negative electrodes for lithium-ion batteries.

[0152] Batteries were assembled using the products obtained in the examples and comparative examples as negative electrodes, and their electrochemical performance was tested. The specific steps are as follows:

[0153] (1) Slurry preparation: The negative electrode material prepared in the examples and comparative examples, the conductive agent (carbon black, Tianjin Damao Chemical), and the binder (sodium carboxymethyl cellulose, Tianjin Damao Chemical) were weighed in a ratio of 8:1:1, and solvent water was added to adjust the slurry viscosity, and stirred for 3 to 5 hours.

[0154] (2) Coating: Use a doctor blade to coat the slurry on the copper foil current collector with a thickness of 120 μm.

[0155] (3) Drying: Dry in a vacuum drying oven at 120°C for 12 h.

[0156] (4) Cutting: Cut the negative electrode into round pieces with a diameter of 15 mm, weigh them and place them in a drying oven.

[0157] (5) Assembly: In a glove box, CR2025 button cells were assembled using lithium sheets as counter electrodes.

[0158] The electrolyte was a 1 M LiPF6 / EC:DMC (1:1, vol) mixture, and the separator was a Celgard 2300 polypropylene microporous membrane.

[0159] The sealed batteries were left to rest for 24 hours and then subjected to charge and discharge tests and cycle performance tests using a Land battery performance test system at a current density of 0.2 C. The test results are shown in Table 2.

[0160] Table 2

[0161]

[0162]

[0163] Figure 7 The electrochemical capacity-voltage test results of a lithium-ion battery assembled using the stable metallic lithium powder prepared according to the method of Example 1 as the pre-lithiation negative electrode material are as follows: the current density is 0.2C, the first charge specific capacity is 881.24 mAh / g, the first discharge specific capacity is 1011.85 mAh / g, and the first coulombic efficiency is 87.1%. Figure 8 The electrochemical capacity-voltage test results of a lithium-ion battery assembled with the carbon-coated silicon oxide material (not pre-lithiated) obtained by the method of Preparation Example 1 as the negative electrode material are as follows: the current density is 0.2C, the first charge specific capacity is 1367.54mAh / g, the first discharge specific capacity is 1900.89mAh / g, and the first coulombic efficiency is 72%. Figure 7 and Figure 8 The comparison shows that the pre-lithiation silicon oxide negative electrode material prepared by the method provided by the present invention can significantly improve the first coulombic efficiency of the electrode, which is of great significance for promoting the application of silicon oxide negative electrode materials in the field of power batteries.

[0164] From the data in Table 2 above, we can see that:

[0165] The test data of the negative electrode materials prepared by pre-lithiation of SiO@C-1 in Examples 1 to 2 and 7 to 9 were compared with the test data of SiO@C-1 obtained by preparing Example 1 alone. The negative electrode materials prepared in Examples 1 to 2 and 7 to 9 can obtain higher first coulombic efficiency and cycle capacity retention rate; similarly, the data of Example 3 using SiO@C-2, Example 4 using SiO@C-3, Example 5 using SiO@C-4 and Example 6 using SiO@C-5 were compared with the data of Examples 2 to 5 prepared alone without pre-lithiation. It can be seen that the negative electrode materials prepared in Examples 3 to 6 can obtain higher first coulombic efficiency and cycle capacity retention rate;

[0166] Comparing Examples 1 to 9 with Comparative Example 1 (replacing the carbon-coated silicon-containing matrix with pure silicon oxide) and Comparative Example 2 (not adding metallic lithium), the negative electrode materials prepared according to the method provided in Examples 1 to 9 achieved higher first coulombic efficiency and cycle capacity retention rates;

[0167] Comparing Example 1 with Comparative Example 3, in Example 1, the pre-lithium precursor and the organic solvent were wet-milled, and the negative electrode material prepared in Example 1 had better performance;

[0168] Comparing Example 1 with Example 5, the SiO@C-1 (Preparation Example 1) used in Example 1 was prepared using the process conditions provided in the present disclosure, while the preparation conditions of SiO@C-4 (Preparation Example 4) used in Example 5 were not within the scope provided in the present disclosure. The elemental composition content of the negative electrode material obtained in Example 1 was within the preferred range provided in the present disclosure (listed in Table 1), and the negative electrode material of Example 1 had higher first coulombic efficiency and cycle capacity retention rate, and the pH value of the slurry was lower.

[0169] Comparing Example 7 with Example 8, the raw material addition ratio used in Example 7 is within the range provided in the present disclosure, the element composition content of the negative electrode material obtained in Example 7 is within the range provided in the present disclosure (listed in Table 1), and the first coulombic efficiency and cycle capacity retention rate of the negative electrode material obtained in Example 7 are higher than those in Example 8;

[0170] Comparing Example 1 with Example 7, it can be seen that Example 1 adopts the preferred raw material addition ratio provided by the present disclosure to prepare the negative electrode material. Compared with Example 7, the first coulombic efficiency and cycle capacity retention rate of the negative electrode material obtained in Example 1 are higher, and the pH value of the slurry is lower;

[0171] Comparing Example 1 with Example 9, Example 1 prepared the negative electrode material according to the process conditions provided in the present disclosure. Compared with Example 9, the negative electrode material obtained in Example 1 had higher first coulombic efficiency and cycle capacity retention rate, and the pH value of the slurry was lower.

[0172] The preferred embodiments of the present disclosure are described in detail above. However, the present disclosure is not limited to the specific details of the above embodiments. Within the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the scope of protection of the present disclosure.

[0173] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0174] In addition, the various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A method for preparing a pre-lithiation negative electrode material, characterized in that: The following steps are involved: S1, contacting a first silicon-containing matrix with an organic carbon source and performing a carbon coating treatment to obtain a carbon-coated silicon-containing matrix; S2, contacting metallic lithium with a second silicon-containing matrix and performing a first ball milling process to obtain a pre-lithium precursor; S3, mixing the pre-lithium precursor with a first organic solvent, and performing a second ball milling process to obtain a pre-lithium solution; S4, contacting the pre-lithiation solution with the carbon-coated silicon-containing matrix obtained in step S1 to perform a pre-lithiation treatment.

2. The method according to claim 1, characterized in that In step S1, the first silicon-containing matrix is ​​selected from one or more of SiOx and silicon, 0.5≤x<2; The organic carbon source includes a solid organic carbon source or a gaseous organic carbon source; Optionally, the solid organic carbon source is selected from one or more of a polymer carbon source, a petroleum carbon source, a sugar carbon source, a graphite carbon source and other carbon sources; Preferably, the polymer carbon source comprises one or more of phenolic resin, epoxy resin, polyvinyl pyrrolidone and polyvinyl alcohol; Preferably, the petroleum carbon source includes one or more of asphalt, petroleum coke and needle coke; Preferably, the carbohydrate carbon source includes one or more of glucose, sucrose and fructose; Preferably, the other carbon source is selected from one or more of sodium carboxymethyl cellulose, polyvinyl alcohol and carboxy styrene butadiene latex; Optionally, the gaseous organic carbon source is selected from one or more gaseous hydrocarbons, preferably, the gaseous organic carbon source is selected from one or more of methane, acetylene and ethylene; Preferably, the weight ratio of the first silicon-containing matrix to the solid organic carbon source is 1:0.01-1, preferably 1:0.05-0.2; Alternatively, the volume of the gaseous organic carbon source is 0.02 to 2 L relative to 1 g of the first silicon-containing matrix.

3. The method according to claim 2, characterized in that In step S1, for the solid organic carbon source, the carbon coating process is selected from a solid phase coating process or a liquid phase coating process; For a gaseous organic carbon source, the carbon coating process includes a vapor phase CVD deposition process; Optionally, the solid phase coating process includes: mixing and coating the first silicon-containing matrix and the solid organic carbon source through a third ball milling process or a melt coating process, and then performing a carbon coating process through a first calcination carbonization process; Optionally, the conditions of the melt coating process in the solid phase coating process include: a temperature of 200 to 1000° C. and a time of 2 to 72 hours; Optionally, the conditions of the first calcination carbonization process in the solid phase coating process include: a calcination temperature of 500 to 1500° C., a calcination time of 2 to 72 hours, and a calcination atmosphere of argon and / or nitrogen; Preferably, the calcination temperature is 700 to 1200° C. and the calcination time is 2 to 5 hours; Optionally, the liquid phase coating process includes: mixing a solid organic carbon source and an organic solvent to obtain a slurry; mixing the slurry with the first silicon-containing matrix through a fourth ball milling process or a homogenization process; then drying by spray drying or rotary evaporation, and then performing a carbon coating process by a second roasting and carbonization process; optionally, the homogenization process includes: a homogenization speed of 100 to 2000 r / min and a homogenization time of 1 to 72 h; optionally, the spray drying process includes an inlet temperature of 100 to 300 ° C and an outlet temperature of 50 to 200 ° C. The carrier gas flow rate is 10 to 100 L / min and the pressure is -0.10 to -0.05 MPa; optionally, the conditions of the second calcination carbonization treatment include: a calcination temperature of 500 to 1500° C., a calcination time of 2 to 72 hours, and a calcination atmosphere of one or more inert gases selected from argon or nitrogen; preferably, the calcination temperature is 700 to 1200° C., and the calcination time is 2 to 5 hours; optionally, the organic solvent is selected from one or more of ethanol, hexane, tetrahydrofuran and benzene. Preferably, the amount of the organic solvent is 1 to 150 g relative to 1 g of the organic carbon source; Optionally, the vapor phase CVD deposition process includes: placing the first silicon-containing substrate in an atmosphere furnace, introducing a gaseous organic carbon source to perform carbon coating treatment by pyrolysis deposition; Optionally, the pyrolysis deposition conditions include: pyrolysis temperature of 300-1200° C., time of 0.5-72 h, and pressure of 0.01-0.5 MPa; Preferably, the carbon coating layer of the carbon-coated silicon-containing matrix prepared in step S1 has a thickness of 1 to 5000 nm, preferably 10 to 500 nm.

4. The method according to claim 1, wherein In step S2, the weight ratio of the metallic lithium to the second silicon-containing matrix is ​​0.1 to 100:1, preferably 1 to 10:1; Optionally, the second silicon-containing matrix is ​​selected from one or more of SiOy and silicon, 0.5≤y<2; The metallic lithium is selected from one or more of lithium ingots, lithium wires, lithium powders or lithium sheets.

5. The method according to claim 1, wherein In step S2, the conditions of the first ball milling treatment include: a rotation speed of 300-2000 r / min, a time of 6-72 h, and a ball-to-material ratio of 1-20:

1. Preferably, the rotation speed is 500-800 r / min, the time is 12-24 h, and the ball-to-material ratio is 10-20:

1.

6. The method according to claim 1, characterized in that In step S3, the first organic solvent is selected from one or more of tetrahydrofuran, hexane, cyclohexane, benzene and naphthalene; Preferably, the amount of the first organic solvent used is 1 to 100 mL, preferably 10 to 50 mL, relative to 1 g of the pre-lithium precursor.

7. The method according to claim 1, characterized in that In step S3, the conditions of the second ball milling treatment include: a rotation speed of 200 to 1000 r / min, preferably 200 to 500 r / min; a time of 6 to 72 hours, preferably 10 to 20 hours; a ball to material ratio of 1 to 20:1, preferably 10 to 20:1; Optionally, in step S3, the pre-lithium solution includes lithium-containing particles, and the particle size of the lithium-containing particles is 20 to 500 nm, preferably 50 to 200 nm.

8. The method according to claim 1, characterized in that In step S4, the weight ratio of the pre-lithium solution to the carbon-coated silicon-containing matrix is ​​0.1 to 100:1, preferably 1 to 50:

1.

9. The method according to claim 1, characterized in that In step S4, the pre-lithiation treatment adopts a ball milling process; Optionally, the conditions of the pre-lithiation treatment include: a rotation speed of 100 to 500 r / min, preferably 100 to 300 r / min; a time of 6 to 72 hours, preferably 12 to 36 hours, and a ball-to-material ratio of 1 to 20:1, preferably 5 to 20:1; Optionally, the method further comprises: washing the product obtained from the pre-lithiation treatment in step S4 with a second organic solvent to perform stabilization treatment; Optionally, the second organic solvent is selected from one or more of tetrahydrofuran, hexane, cyclohexane and benzene; preferably, the amount of the second organic solvent used is 0.1 to 100 mL, preferably 1 to 10 mL, relative to 1 g of the product obtained by pre-lithiation treatment.

10. The pre-lithiation negative electrode material prepared by the method according to any one of claims 1 to 9.

11. The pre-lithiation negative electrode material according to claim 10, characterized in that The pre-lithiation negative electrode material comprises lithium, silicon and carbon; wherein, based on the total weight of the pre-lithiation negative electrode material, the content of lithium is 1 to 50% by weight, the content of silicon is 10 to 90% by weight, and the content of carbon is 1 to 50% by weight; preferably, the content of lithium is 1 to 10% by weight, the content of silicon is 50 to 90% by weight, and the content of carbon is 4 to 20% by weight; Optionally, the average particle size of the pre-lithiation negative electrode material is 1 to 100 μm, and the BET specific surface area is 1 to 20 m 2 / g, total pore volume is 0.001~0.05cm 3 / g.

12. A negative electrode, characterized in that Including the pre-lithiation negative electrode material according to claim 10 or 11.

13. A lithium-containing battery, characterized in that: The negative electrode according to claim 12 is included.

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