Process for preparing silicon-carbon negative electrode material by emulsification method and silicon-carbon negative electrode material

Abstract

The application discloses a process for preparing a silicon-carbon negative electrode material by an emulsification method and the silicon-carbon negative electrode material, and belongs to the technical field of lithium batteries. In order to solve the problems of pulverization and peeling caused by volume expansion of a silicon-based negative electrode material, the application provides a process for preparing a silicon-carbon negative electrode material by an emulsification method, which comprises the following steps: dispersing mesophase pitch in a heat-stable medium, adding nano-silicon and an additive, preparing a low-viscosity emulsion under the conditions of 300-450 DEG C and 0.5-2.0 MPa, obtaining a silicon-carbon material precursor through centrifugal separation, cleaning and drying, and finally obtaining the silicon-carbon negative electrode material through high-temperature carbonization, crushing and screening. In the application, the mesophase pitch is subjected to three-dimensional stress extrusion in a high-temperature medium and the action of carbonaceous particle additives, the growth and fusion of carbon microspheres are inhibited, more carbon microspheres and nano-silicon particles are combined, the conductivity is increased, the volume expansion of the nano-silicon is relieved through the elastic structure of the carbon material, and the silicon-carbon material has the advantages of long cycle and high stability.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery technology, specifically relating to a process for preparing silicon-carbon anode material using an emulsification method, the prepared silicon-carbon anode material, and a lithium-ion battery using the silicon-carbon anode material as the anode. Background Technology

[0002] In the field of lithium-ion batteries, carbon-based materials have advantages such as good thermal stability, high equilibrium potential, and high initial efficiency. However, due to insufficient theoretical capacity, they cannot meet the needs of more new energy electrical appliances. Silicon-based anode materials have attracted widespread attention due to their high specific capacity (up to 4200 mAh / g), low voltage, and abundant reserves, and are considered the most promising anode materials for next-generation rechargeable batteries. However, silicon-based anode materials also suffer from problems such as huge volume expansion (~300%) of silicon material during charge and discharge, leading to material pulverization and detachment. Therefore, it is necessary to modify and coat the material to suppress its volume expansion and avoid direct contact between the active material and the electrolyte, thereby fully utilizing the electrochemical performance of the active material, reducing the initial irreversible capacity, and improving cycle stability. This is a scientific and engineering challenge that urgently needs to be solved.

[0003] CN202011589174 discloses a method for preparing emulsified asphalt-coated silicon-carbon anode material, comprising the following steps: S1, heating and melting asphalt, controlling the temperature at 130-150℃, adding polyisobutylene succinic anhydride derivative to the asphalt, stirring evenly, dissolving a surfactant in water at 80-90℃, and then pouring the asphalt solution into the water, forming emulsified asphalt under stirring; S2, mixing the emulsified asphalt, nano-silicon powder, and graphite in a colloid mill for 6-8 hours to obtain a mixture, and then spray-drying the mixture to obtain a mixed powder; S3, sintering the mixed powder at 800-1200℃, and cooling to form the emulsified asphalt-coated silicon-carbon anode material. However, this method uses aqueous emulsification, dispersing micron-sized asphalt particles in an emulsifier solution to form a suspension, which does not affect the components in the asphalt, and the addition of a surfactant.

[0004] CN202211580546 discloses a method for preparing modified silicon-carbon anode material, including the following steps: (1) mixing modifier 2 with asphalt and stirring evenly, then carbonizing, cooling, crushing and sieving to obtain modified asphalt A; dynamically adding modified asphalt A into a solution containing modifier 1, dispersing it by high-speed shearing in an emulsifier, heating and drying, and crushing to obtain modified asphalt B; (2) mixing silicon source with substrate carbon material to obtain composite material C, and fully mixing composite material C with modified asphalt B at room temperature to obtain silicon-carbon coated precursor material; (3) calcining the silicon-carbon coated precursor material under an inert atmosphere to obtain Si / Gr@C composite material, and after crushing and sieving, obtaining modified silicon-carbon anode material. Summary of the Invention

[0005] The purpose of this invention is to propose a method for preparing silicon-carbon anode materials by emulsification. It utilizes the principle that dispersing mesophase pitch in a high-temperature medium can increase the content of mesophase carbon microspheres. Nano-silicon, additives and mesophase carbon microspheres are intercalated to form a material. The large-area flow domain structure of the carbon microspheres increases the conductivity of the silicon-based material. The elastic structure of the carbon material alleviates the volume expansion of the nano-silicon, so that the silicon-carbon composite material has the advantages of long cycle life and high stability.

[0006] This invention first provides a process for preparing silicon-carbon anode materials by emulsification, which includes the following steps:

[0007] A. Mix the mesophase asphalt and the thermally stabilized medium at a mass ratio of 1:3 to 9, and disperse them by ultrasonic stirring under inert gas protection to obtain a mixture of mesophase asphalt and thermally stabilized medium.

[0008] B. Mix nano-silicon with the mixture obtained in step A at a mass ratio of 1:6 to 10, add additives, heat to 300 to 450°C and 0.5 to 2.0 MPa under inert gas protection, and maintain the temperature for reaction. After the reaction is complete, cool to obtain a low-viscosity emulsion. The low-viscosity emulsion is centrifuged, washed and vacuum dried to obtain a silicon-carbon material precursor.

[0009] C. The silicon-carbon material precursor obtained in step B is carbonized under inert gas protection, and then cooled, crushed and sieved to obtain the silicon-carbon anode material.

[0010] In step A, the thermally stabilizing medium is silicone oil;

[0011] In step B, the additive is at least one of carbon black, graphene, and ceramics.

[0012] In the process of preparing silicon-carbon anode materials by the above emulsification method, in step A, the mesophase pitch is at least one of petroleum-based mesophase pitch, coal tar-based mesophase pitch, and naphthalene-based mesophase pitch.

[0013] In the process of preparing silicon-carbon anode materials by the above emulsification method, in step A, the particle size of the mesophase pitch is -200 mesh.

[0014] In the process of preparing silicon-carbon anode materials by the above emulsification method, in step A, the thermally stable medium is at least one of methyl silicone oil, dimethyl silicone oil, ethyl silicone oil, phenyl silicone oil, methyl ethoxy silicone oil, methyl vinyl silicone oil, and methyl hydroxy silicone oil.

[0015] In the process of preparing silicon-carbon anode materials by the above emulsification method, the ultrasonic stirring and dispersion time in step A is 1 to 3 hours.

[0016] In the process of preparing silicon-carbon anode materials by the above emulsification method, in step B, the median particle size of the nano-silicon is 40-150 nm.

[0017] In the process of preparing silicon-carbon anode materials by the above emulsification method, in step B, the amount of additive added is 0.5 to 3% wt of the mesophase pitch.

[0018] In the process of preparing silicon-carbon anode materials by the above emulsification method, in step B, the rotation speed of the heat preservation reaction is 50-150 rpm.

[0019] In the process of preparing silicon-carbon anode materials by the above emulsification method, the heat preservation reaction time in step B is 1 to 10 hours.

[0020] In the process of preparing silicon-carbon anode materials by the above emulsification method, in step B, the viscosity of the low-viscosity emulsion liquid is 500-1500 cps.

[0021] In the process of preparing silicon-carbon anode materials by the above emulsification method, step B involves washing with benzene or acetone 3 to 5 times.

[0022] In the process of preparing silicon-carbon anode materials by the above emulsification method, the temperature of vacuum drying in step B is 60-100℃.

[0023] In the process of preparing silicon-carbon anode materials by the above emulsification method, the vacuum drying time in step B is 8 to 12 hours.

[0024] In the process of preparing silicon-carbon anode materials by the above emulsification method, the carbonization temperature in step C is 900-1200℃.

[0025] In the process of preparing silicon-carbon anode materials by the above emulsification method, the carbonization time in step C is 1 to 10 hours.

[0026] In the process of preparing silicon-carbon anode materials by the above emulsification method, in step C, the sieving is performed by passing the material through a 325-mesh sieve and taking the material that passes through the sieve.

[0027] Based on the above process, the present invention also provides a silicon-carbon anode material, which is prepared by an emulsification method for preparing silicon-carbon anode materials.

[0028] Based on the above, the present invention also provides a lithium-ion battery negative electrode, which is prepared by using the silicon-carbon negative electrode material prepared by the above-mentioned emulsification method, or the above-mentioned silicon-carbon negative electrode material.

[0029] Based on the above, the present invention also provides a lithium-ion battery, which uses the above-mentioned lithium-ion battery negative electrode as the negative electrode.

[0030] The beneficial effects of this invention are:

[0031] Unlike the traditional simple physical mixing of mesophase pitch and nano-silicon particles, this invention utilizes the surrounding stress and carbonaceous particle additives in a high-temperature medium to inhibit the growth and fusion of carbon microspheres, tending to form a greater number of carbon microspheres and nano-silicon particles to form a silicon-mesophase pitch composite material. After high-temperature carbonization, the large-area flow-shaped structure of the carbon microsphere carbon material increases the conductivity of the silicon-based material, and the elastic structure of the carbon material alleviates the volume expansion of nano-silicon, giving the silicon-carbon composite material the advantages of long cycle life and high stability. Attached Figure Description

[0032] Figure 1 This is a scanning electron microscope image of the silicon-carbon anode material obtained in Example 1. Detailed Implementation

[0033] Specifically, the process for preparing silicon-carbon anode materials using the emulsification method includes the following steps:

[0034] A. Mix the mesophase asphalt and the thermally stabilized medium at a mass ratio of 1:3 to 9, and disperse them by ultrasonic stirring under inert gas protection to obtain a mixture of mesophase asphalt and thermally stabilized medium.

[0035] B. Mix nano-silicon with the mixture obtained in step A at a mass ratio of 1:6 to 10, add additives, heat to 300 to 450°C and 0.5 to 2.0 MPa under inert gas protection, and maintain the temperature for reaction. After the reaction is complete, cool to obtain a low-viscosity emulsion. The low-viscosity emulsion is centrifuged, washed and vacuum dried to obtain a silicon-carbon material precursor.

[0036] C. The silicon-carbon material precursor obtained in step B is carbonized under inert gas protection, and then cooled, crushed and sieved to obtain the silicon-carbon anode material.

[0037] In step A, the thermally stabilizing medium is silicone oil;

[0038] In step B, the additive is at least one of carbon black, graphene, and ceramics.

[0039] In step A of this invention, the mesophase pitch is at least one of petroleum-based mesophase pitch, coal tar-based mesophase pitch, and naphthalene-based mesophase pitch. At room temperature, pitch is in a solid state and does not meet the conditions for forming mesophase carbon microspheres. Only at suitable high temperatures will MCMB be formed. To facilitate the formation of mesophase carbon microspheres, the mesophase pitch is pulverized and sieved to a particle size of -200 mesh in this invention.

[0040] In step A of this invention, the heat-stabilizing medium is at least one of methyl silicone oil, dimethyl silicone oil, ethyl silicone oil, phenyl silicone oil, methylethoxy silicone oil, methyl vinyl silicone oil, and methyl hydroxy silicone oil. The purpose of adding silicone oil as a heat-stabilizing medium is to act as a dispersion medium for the asphalt. Without it, the asphalt will undergo accelerated decomposition and condensation reactions at high temperatures, and the proportion of mesophase carbon microspheres formed will be greatly reduced. Too little heat-stabilizing medium will result in high material viscosity during initial mixing and a decreased yield of mesophase carbon microspheres; obtaining a high-viscosity liquid is also detrimental to the dispersion of the various components. Too much, on the other hand, will lead to wasted costs.

[0041] In step A of this invention, the asphalt and the heat-stabilizing medium are mixed in advance and dispersed by ultrasonic stirring for 1 to 3 hours to ensure uniform dispersion, thus avoiding the inability of the mesophase asphalt and silica to disperse well due to one-time addition.

[0042] In step B of this invention, the median particle size of the nano-silicon is 40-150 nm; the amount of the additive added is 0.5-3% wt of the mesophase pitch.

[0043] For mesophase pitch, the formation temperature of mesophase carbon microspheres is 300–450℃. Excessive temperature will lead to coke formation, essentially solidifying the material structure and hindering the formation of low-viscosity emulsions. Simultaneously, applying a certain positive pressure increases the stress exerted by the thermally stable medium on the components in the mesophase pitch, promoting the formation of microsphere structures by carbon planar molecules (increasing the orderliness of structural orientation). At normal pressure, the effect is less pronounced. Therefore, in step B of this invention, the system is heated to 300–450℃ at a pressure of 0.5–2.0 MPa for a heat-holding reaction. The rotation speed is 50–150 rpm, and the heat-holding reaction typically lasts 1–10 hours.

[0044] In step B of this invention, the viscosity of the low-viscosity emulsion is 500–1500 cps. The obtained low-viscosity emulsion is centrifuged to remove the thermally stable medium, then washed 3–5 times with benzene or acetone, and vacuum dried at 60–100°C for 8–12 hours to obtain the silicon-carbon material precursor required by this invention.

[0045] In step C of this invention, the carbonization temperature is controlled to be 900–1200°C, and the carbonization time is 1–10 h.

[0046] In step C of this invention, the sieving process involves passing the material through a 325-mesh sieve and collecting the material that passes through the sieve.

[0047] Based on the above process, we also provide a silicon-carbon anode material, which is prepared by the emulsification method.

[0048] Based on the above, the present invention also provides a lithium-ion battery negative electrode, which is prepared by using the silicon-carbon negative electrode material obtained by the above-mentioned emulsification method for preparing silicon-carbon negative electrode material, or the above-mentioned silicon-carbon negative electrode material; and the present invention also provides a lithium-ion battery, which uses the aforementioned negative electrode as the negative electrode.

[0049] In this invention, the inert gas can be nitrogen or argon.

[0050] The present invention will be further described in detail below through embodiments, but the scope of protection of the present invention is not limited to the embodiments described herein.

[0051] Example 1

[0052] Take 5g of petroleum mesophase pitch that has passed through a 200-mesh sieve and add it to 30g of phenyl silicone oil. Disperse the mixture by ultrasonic stirring under N2 purging for 2 hours to obtain a mixture of mesophase pitch and silicone oil.

[0053] 5g of nano-silicon and 0.05g of carbon black were added to 35g of the obtained mixture of asphalt and silicone oil. The mixture was heated to 380℃ under N2 purging, the pressure of the reactor was 0.5MPa, the stirring speed was 75rpm and the temperature was maintained for 10h. After cooling, a low-viscosity emulsion was obtained. The viscosity of the liquid was measured to be 989cps by a rotational viscometer. After centrifugation to remove the dispersion medium, the mixture was washed three times with benzene or acetone and vacuum dried at 60℃ for 12h to obtain the silicon-carbon material precursor.

[0054] The precursor was heated to 1200℃ in a tube furnace under N2 atmosphere protection at a rate of 2℃ / min and held for 1 hour. After carbonization, it was crushed and sieved through a 325-mesh sieve to obtain silicon-carbon anode material, and its electrochemical performance was tested.

[0055] Electrochemical performance test results show that it exhibits a discharge specific capacity of 1820 mAh / g at a current density of 0.1C, an initial charge-discharge efficiency of 84.2%, and a discharge specific capacity of 936 mAh / g after 100 cycles at a current density of 0.3C.

[0056] Example 2

[0057] Take 5g of naphthalene-based mesophase pitch that has passed through a 200-mesh sieve and add it to 30g of phenyl silicone oil. Disperse the mixture by ultrasonic stirring under N2 purging for 2h to obtain a mixture of mesophase pitch and silicone oil.

[0058] 5g of nano-silicon and 0.05g of carbon black were added to 35g of the obtained mixture of asphalt and silicone oil. The mixture was heated to 300℃ under N2 purging, the pressure of the reactor was 1MPa, the stirring speed was 50rpm and the temperature was maintained for 5h. After cooling, a low-viscosity emulsion was obtained. The viscosity of the liquid was measured to be 1215cps by a rotational viscometer. After centrifugation to remove the dispersion medium, the mixture was washed three times with benzene or acetone and vacuum dried at 60℃ for 12h to obtain the silicon-carbon material precursor.

[0059] The precursor was heated to 1200℃ in a tube furnace under N2 atmosphere protection at a rate of 2℃ / min and held for 1 hour. After carbonization, it was crushed and sieved through a 325-mesh sieve to obtain silicon-carbon anode material, and its electrochemical performance was tested.

[0060] Electrochemical performance test results show that it exhibits a discharge specific capacity of 1729 mAh / g at a current density of 0.1C, an initial charge-discharge efficiency of 85.9%, and a discharge specific capacity of 1002 mAh / g after 100 cycles at a current density of 0.3C.

[0061] Example 3

[0062] Take 10g of petroleum-based mesophase pitch that has passed through a 200-mesh sieve and add it to 30g of methyl vinyl silicone oil. Disperse the mixture by ultrasonic stirring under N2 purging for 2 hours to obtain a mixture of mesophase pitch and silicone oil.

[0063] 5g of nano-silicon and 0.05g of ceramic were added to 40g of the obtained mixture of asphalt and silicone oil. The mixture was heated to 300℃ under N2 purging, the pressure of the reactor was 0.5MPa, the stirring speed was 50rpm and the temperature was maintained for 5h. After cooling, a low-viscosity emulsion was obtained. The viscosity of the liquid was measured to be 1052cps by a rotational viscometer. After centrifugation to remove the dispersion medium, the mixture was washed three times with benzene or acetone and vacuum dried at 60℃ for 12h to obtain the silicon-carbon material precursor.

[0064] The precursor was heated to 1200℃ in a tube furnace under N2 atmosphere protection at a rate of 2℃ / min and held for 1 hour. After carbonization, it was crushed and sieved through a 325-mesh sieve to obtain silicon-carbon anode material, and its electrochemical performance was tested.

[0065] Electrochemical performance test results show that it exhibits a discharge specific capacity of 1692 mAh / g at a current density of 0.1C, an initial charge-discharge efficiency of 85.5%, and still has a discharge specific capacity of 1052 mAh / g after 100 cycles at a current density of 0.3C.

[0066] Example 4

[0067] Take 10g of petroleum-based mesophase pitch that has passed through a 200-mesh sieve and add it to 30g of methyl hydroxy silicone oil. Disperse the mixture by ultrasonic stirring under N2 purging for 2 hours to obtain a mixture of mesophase pitch and silicone oil.

[0068] 5g of nano-silicon and 0.05g of ceramic were added to 40g of the obtained asphalt and silicone oil mixture. The mixture was heated to 400℃ under N2 purging, the pressure of the reactor was 0.5MPa, the stirring speed was 50rpm and the temperature was maintained for 5h. After cooling, a low-viscosity emulsion was obtained. The viscosity of the liquid was measured to be 956cps by a rotational viscometer. After centrifugation to remove the dispersion medium, the mixture was washed three times with benzene or acetone and vacuum dried at 60℃ for 12h to obtain the silicon-carbon material precursor.

[0069] The precursor was heated to 900℃ in a tube furnace under N2 atmosphere protection at a rate of 2℃ / min and held for 3 hours. After carbonization, it was crushed and sieved through a 325-mesh sieve to obtain silicon-carbon anode material, and its electrochemical performance was tested.

[0070] Electrochemical performance test results show that it exhibits a discharge specific capacity of 1722 mAh / g at a current density of 0.1C, an initial charge-discharge efficiency of 84.9%, and still has a discharge specific capacity of 1028 mAh / g after 100 cycles at a current density of 0.3C.

[0071] Comparative Example 1

[0072] Take 5g of petroleum mesophase pitch that has passed through a 200-mesh sieve and add it to 30g of phenyl silicone oil. Disperse the mixture by ultrasonic stirring under N2 purging for 2 hours to obtain a mixture of mesophase pitch and silicone oil.

[0073] 5g of nano-silicon and 0.05g of carbon black were added to 35g of the obtained mixture of asphalt and silicone oil. The mixture was heated to 150℃ under N2 purging, the pressure of the reactor was 0.5MPa, the stirring speed was 75rpm and the temperature was maintained for 10h. After cooling, a low-viscosity emulsion was obtained. The viscosity of the liquid was measured to be 560cps by a rotational viscometer. After centrifugation to remove the dispersion medium, the mixture was washed three times with benzene or acetone and vacuum dried at 60℃ for 12h to obtain the silicon-carbon material precursor.

[0074] The precursor was heated to 1200℃ in a tube furnace under N2 atmosphere protection at a rate of 2℃ / min and held for 1 hour. After carbonization, it was crushed and sieved through a 325-mesh sieve to obtain silicon-carbon anode material, and its electrochemical performance was tested.

[0075] Electrochemical performance test results show that it exhibits a discharge specific capacity of 1923 mAh / g at a current density of 0.1C, an initial charge-discharge efficiency of 80.01%, and still has a discharge specific capacity of 526 mAh / g after 100 cycles at a current density of 0.3C.

[0076] Comparative Example 2

[0077] Take 5g of naphthalene-based mesophase pitch (sieved through a 200-mesh sieve), 5g of nano-silicon, and 0.05g of carbon black, add them to 30g of phenyl silicone oil, heat to 300℃ under N2 purging, maintain the pressure of the reactor at 1MPa, stir at 50rpm and keep warm for 5h, and after cooling, obtain a low-viscosity emulsion liquid. The viscosity of the liquid measured by a rotational viscometer is 1622cps. After centrifuging to remove the dispersion medium, wash three times with benzene or acetone, and vacuum dry at 60℃ for 12h to obtain the silicon-carbon material precursor.

[0078] The precursor was heated to 1200℃ in a tube furnace under N2 atmosphere protection at a rate of 2℃ / min and held for 1 hour. After carbonization, it was crushed and sieved through a 325-mesh sieve to obtain silicon-carbon anode material, and its electrochemical performance was tested.

[0079] Electrochemical performance test results show that it exhibits a discharge specific capacity of 1952 mAh / g at a current density of 0.1C, an initial charge-discharge efficiency of 79.02%, and still has a discharge specific capacity of 436 mAh / g after 100 cycles at a current density of 0.3C.

[0080] As can be seen from the above examples and comparative examples, compared with the traditional physical ball milling and mixing of asphalt phase and silicon material, the emulsification method for preparing silicon-carbon composite materials significantly improves the first charge-discharge efficiency of the battery, reduces irreversible capacity, and improves the cycle stability of the battery.

[0081] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. Process for the preparation of a silicon-carbon negative electrode material by emulsion method, characterized in that: The method comprises the following steps: A. mixing mesophase pitch and heat-stable medium in a mass ratio of 1:3-9, dispersing under ultrasonic stirring in an inert gas atmosphere to obtain a mixture of mesophase pitch and heat-stable medium; B. mixing nano-silicon and the mixture obtained in step A in a mass ratio of 1:6-10, adding an additive, heating to 300-450℃ under an inert gas atmosphere, and performing a heat preservation reaction at a pressure of 0.5-2.0 MPa, and then cooling to obtain a low-viscosity emulsion liquid; the low-viscosity emulsion liquid is subjected to centrifugal separation, washing, and vacuum drying to obtain a silicon-carbon material precursor; C. carbonizing the silicon-carbon material precursor obtained in step B under an inert gas atmosphere, and then cooling, crushing, and sieving to obtain a silicon-carbon negative electrode material. In step A, the heat-stable medium is silicone oil. In step B, the additive is at least one of carbon black, graphene, and ceramic. In step B, the additive is added in an amount of 0.5-3%wt of the mesophase pitch. In step B, the rotation speed of the heat preservation reaction is 50-150 rpm.

2. The process for the preparation of silicon-carbon negative electrode material by emulsion method as claimed in claim 1 wherein: In step A, at least one of the following is satisfied: The mesophase pitch is at least one of petroleum-based mesophase pitch, coal tar-based mesophase pitch, and naphthalene-based mesophase pitch; The particle size of the mesophase pitch is -200 mesh; The heat-stable medium is at least one of methyl silicone oil, dimethyl silicone oil, ethyl silicone oil, phenyl silicone oil, methyl ethoxy silicone oil, methyl vinyl silicone oil, and methyl hydroxyl silicone oil.

3. The process for the preparation of silicon-carbon anode material by emulsion method as claimed in claim 1 wherein: In step A, the ultrasonic stirring and dispersing time is 1-3 h.

4. The process for preparing silicon-carbon anode material by emulsion method as claimed in claim 1 wherein: In step B, at least one of the following is satisfied: The median particle size of the nano-silicon is 40-150 nm; The heat preservation reaction time is 1-10 h.

5. The process for preparing silicon-carbon anode material by emulsion method as claimed in claim 1 wherein: In step B, the viscosity of the low-viscosity emulsion liquid is 500-1500 cps.

6. The process for preparing silicon-carbon anode material by emulsion method as claimed in claim 1 wherein: In step B, at least one of the following is satisfied: The washing is benzene or acetone washing for 3-5 times; The vacuum drying temperature is 60-100℃; The vacuum drying time is 8-12 h.

7. The process for the preparation of silicon-carbon negative electrode material by emulsion method as claimed in claim 1 wherein: In step C, at least one of the following is satisfied: The carbonization temperature is 900-1200℃; The carbonization time is 1-10 h; The sieving is passing through a 325 mesh sieve and taking undersize.

8. A silicon-carbon negative electrode material prepared by the emulsification method of any one of claims 1-7.

9. A lithium-ion battery negative electrode, characterized by, The silicon-carbon negative electrode material prepared by the emulsification method of any one of claims 1-7, or the silicon-carbon negative electrode material of claim 8, is prepared.

10. A lithium-ion battery, characterized by: The lithium ion battery negative electrode of claim 9 is used as a negative electrode.

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