Preparation method of silicon-carbon composite material by plasma modification, silicon-carbon composite material and application

Abstract

The present invention discloses a method for preparing a silicon-carbon composite material by plasma modification, the silicon-carbon composite material and its applications. It includes at least the following steps: Step S10) putting aminated porous carbon into a deposition chamber, passing silane gas through the deposition chamber to deposit nanosilicon on the aminated porous carbon to obtain a silicon-carbon precursor material; Step S20) transferring the silicon-carbon precursor material to a chamber for plasma modification, passing a halogen gas in the form of plasma, and depositing the generated halogen ions on the surface of the silicon-carbon precursor material to obtain a silicon-carbon precursor material coated with halogenated carbon; Step S30) stopping the passage of the halogen gas and passing a carbon source gas in the form of plasma. The prepared silicon-carbon composite material forms a structurally stable core-shell structure, greatly reduces the expansion problem of silicon, and can significantly improve the cycle performance of a battery applied therewith. In addition, the process of this application is simple, and by using the plasma method to modify the silicon-carbon material, it is easy to achieve mass preparation and large-scale industrialization.

Description

Technical Field

[0001] This application claims the priority of Chinese Patent Application No. 2023107730517, titled "Method for Preparing Silicon Carbon Composite Material by Plasma Modification, Silicon Carbon Composite Material and Application", filed with the Patent Office of the State Intellectual Property Office of China on June 27, 2023, and all of its contents are incorporated herein by reference.

[0002] The present invention belongs to the field of preparation of lithium-ion battery materials. Specifically, it relates to a method for preparing a silicon carbon composite material by plasma modification, and further to a silicon carbon composite material obtained by the preparation method and its application.

Background Art

[0003] Silicon carbon composite materials are widely used in high-energy density lithium-ion batteries due to their advantages such as high energy density and abundant material sources. The general preparation method mainly involves depositing nanosilicon on porous carbon by silane pyrolysis and coating amorphous carbon by vapor phase growth at a temperature of 700 - 1000°C. The silicon carbon composite material prepared by this method has a problem that the carbon structure coated on its outer layer is unstable, and due to the growth of silicon crystal grains in a temperature environment of 700 - 1000°C, silicon expands significantly, which has a great adverse effect on the cycle performance of the battery.

[0004] Therefore, the applicant of the present application wants to explore technical solutions to improve the above technical problems.

Summary of the Invention

[0005] In view of this, an object of the present invention is to provide a method for preparing a silicon-carbon composite material by plasma modification, the silicon-carbon composite material and its application. The prepared silicon-carbon composite material forms a structurally stable core-shell structure, greatly reduces the expansion problem of silicon, and can significantly improve the cycle performance of a battery using the same. Furthermore, the preparation method provided in the present application has a simple process, and by using the plasma method to modify the silicon-carbon material, it is easy to achieve mass preparation and large-scale industrialization.

[0006] The technical solution adopted in the present invention is as follows.

[0007] A method for preparing a silicon-carbon composite material by plasma modification, comprising: Step S10) of putting aminated porous carbon into a deposition chamber, passing silane gas with a flow rate of 100 to 1000 ml / min through the deposition chamber, passing the silane gas at a temperature of 400 to 600 °C for at least 30 minutes, and depositing nanosilicon on the aminated porous carbon to obtain a silicon-carbon precursor material; Step S20) of transferring the silicon-carbon precursor material obtained in step S10) to a plasma modification chamber, passing halogen gas in the form of plasma through the plasma modification chamber, depositing the generated halogen ions on the surface of the silicon-carbon precursor material to obtain a silicon-carbon precursor material coated with halogenated carbon; Step S30) of stopping the passage of the halogen gas and passing a carbon source gas in the form of plasma through the plasma modification chamber to obtain the silicon-carbon composite material, at least including the above steps.

[0008] Preferably, in step S20), as parameters of the plasma modification chamber, the vacuum degree is set to 1 to 10 Pa, the temperature is set to 300 to 600 °C, the output of the plasma method is set to 500 to 1000 W, and / or the flow rate of the halogen gas is set to 100 to 500 sccm and the passing time is set to at least 10 minutes.

[0009] Preferably, in the step S30), as parameters of the chamber for plasma method modification, the degree of vacuum is set to 1 to 10 Pa, the temperature is set to 300 to 600 °C, the output of the plasma method is set to 500 to 1000 W, and / or the flow rate of the carbon source gas is set to 100 to 500 sccm, and the passing time is set to at least 10 minutes.

[0010] Preferably, in the step S10), the method for preparing the aminated porous carbon is Step S11) of pre-acidifying the porous carbon with concentrated nitric acid to obtain acidified porous carbon, Step S12) of mixing the porous carbon acidified in step S11) with thionyl chloride and N,N-dimethylformamide and reacting at a temperature of 30 to 100 °C for at least 1 hour to obtain chlorinated porous carbon, Step S13) of reacting the chlorinated porous carbon obtained in step S12) with aniline to obtain amidated porous carbon as the aminated porous carbon, and including.

[0011] Preferably, the method for preparing the aminated porous carbon is Step S11) of adding the porous carbon to concentrated nitric acid, setting the mass ratio of the porous carbon to concentrated nitric acid to 1:200 to 500, and heating under reflux at a temperature of 30 to 100 °C for at least 1 hour to obtain acidified porous carbon, Step S12) of mixing the porous carbon acidified in step S11) with thionyl chloride and N,N-dimethylformamide, setting the mass ratio of the acidified porous carbon, thionyl chloride and N,N-dimethylformamide to 1:20 to 80:5 to 15, and reacting at a temperature of 30 to 100 °C for at least 1 hour to obtain chlorinated porous carbon, Step S13) of reacting the chlorinated porous carbon obtained in step S12) with aniline at a temperature of 0 to 40 °C for at least 1 hour to obtain amidated porous carbon as the aminated porous carbon, and the step of setting the mass ratio of the chlorinated porous carbon to aniline to 1:10 to 30, and including.

[0012] Preferably, in step S11), the acidified porous carbon is washed with deionized water and dried, and then proceed to step S12), and / or in step S12), the chlorinated porous carbon is washed with tetrahydrofuran and dried, and then proceed to step S13), and / or in step S13), the amidated porous carbon is washed with acetone until it becomes colorless.

[0013] Preferably, in step S20), the halogen gas is any one or any mixture of fluorine, chlorine, and bromine.

[0014] Preferably, in step S30), the carbon source gas is any one or any mixture of methane, ethylene, acetylene, and ethylene.

[0015] Preferably, it is a silicon-carbon composite material prepared by the method for preparing a silicon-carbon composite material by plasma modification as described above. Here, the silicon-carbon composite material includes a core-shell structure composed of a core and a shell. The core includes a nitrogen-doped silicon-carbon composite material, and the shell includes a halogenated carbon and amorphous carbon.

[0016] Preferably, it is the application of the silicon-carbon composite material as described above, and the silicon-carbon composite material is used as an active material raw material for manufacturing an electrode sheet of a battery, preferably as an active material raw material for manufacturing a negative electrode sheet of a lithium-ion battery.

[0017] In the present invention, by forming a chemical bond using the amino group on the surface of amidated porous carbon and the silicon radicals generated by thermal decomposition of silane gas, the stability of the core structure of the material is enhanced, the cycle performance of the battery applied with it is improved. Further, by passing a halogen gas in the form of plasma through the silicon-carbon precursor material (as the core structure) to form halogenated carbon coated on the surface of the silicon-carbon precursor material, compared with the general vapor-phase growth method, the diffusion of halogen ions inside the material can be promoted, the halogenation time can be significantly shortened, the halogenation temperature can be lowered, and the influence on the growth of silicon crystal grains can be reduced. Also, in this application, after forming the halogenated carbon, amorphous carbon located on the surface of the halogenated carbon is further formed in the form of plasma to form a shell structure composed of the halogenated carbon and the amorphous carbon, and by forming a core-shell structure that is structurally stable with the core structure of the material, the expansion problem of silicon can be significantly reduced, and the cycle performance of the battery applied with it can be significantly improved. Moreover, the preparation method provided in this application has a simple process, and by modifying the silicon-carbon material using the plasma method, it is easy to achieve mass preparation and large-scale industrialization.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0019] Referring to FIG. 1, this embodiment provides a method for preparing a silicon-carbon composite material by plasma modification, and at least includes the following operation steps of S10) to S30).

[0020] In step S10), the aminated porous carbon is placed in the deposition chamber, and silane gas with a flow rate of 100 to 1000 ml / min is passed through the deposition chamber (the silane gas is preferably a mixture of silane and an inert gas, where the volume ratio of silane to the inert gas is 1:5 to 15, more preferably 1:8 to 12). The silane gas is passed through at a temperature of 400 to 600 °C for at least 30 minutes (preferably 30 to 300 minutes) to deposit nanosilicon on the aminated porous carbon, obtaining a silicon-carbon precursor material.

[0021] In S20), the silicon-carbon precursor material obtained in step S10) is transferred to the chamber for plasma method modification, and a halogen gas is passed through the chamber for plasma method modification in the form of plasma. The generated halogen ions are deposited on the surface of the silicon-carbon precursor material to obtain a silicon-carbon precursor material coated with halogenated carbon. Preferably, in order to further promote the coating deposition effect of the halogenated carbon, in this step S20), as the parameters of the chamber for plasma method modification, the vacuum degree is set to 1 to 10 Pa, the temperature is set to 300 to 600 °C, the output of the plasma method is set to 500 to 1000 W, and / or the flow rate of the halogen gas is set to 100 to 500 sccm, and the passing time is set to at least 10 minutes, more preferably 10 to 60 minutes. Preferably, in this step S20), the halogen gas is any one or an arbitrary mixture of fluorine, chlorine, and bromine.

[0022] In S30), the passing of the halogen gas is stopped, and a carbon source gas is passed through the chamber for plasma method modification in the form of plasma to obtain a silicon-carbon composite material. Preferably, in order to further promote the coating deposition effect of amorphous carbon, in this step S30), as the parameters of the chamber for plasma method modification, the vacuum degree is set to 1 to 10 Pa, the temperature is set to 300 to 600 °C, the output of the plasma method is set to 500 to 1000 W, and / or the flow rate of the carbon source gas is set to 100 to 500 sccm, and the passing time is set to at least 10 minutes, more preferably 10 to 60 minutes. Preferably, in this step S30), the carbon source gas is any one or an arbitrary mixture of methane, ethylene, acetylene, and ethylene.

[0023] Preferably, in step S10) of this embodiment, the method for preparing the aminated porous carbon is as follows: Step S11) of pre-acidifying the porous carbon with concentrated nitric acid to obtain acidified porous carbon; Step S12) of mixing the porous carbon acidified in step S11) with thionyl chloride and N,N-dimethylformamide, reacting at a temperature of 30 to 100 °C for at least 1 hour to obtain chlorinated porous carbon; Step S13) of reacting the chlorinated porous carbon obtained in step S12) with aniline to obtain aminated porous carbon as the aminated porous carbon.

[0024] More preferably, in step S10) of this embodiment, the method for preparing the aminated porous carbon includes the following operation steps S11) to S13).

[0025] In S11), the porous carbon is added to concentrated nitric acid, the mass ratio of the porous carbon to the concentrated nitric acid is 1:200 to 500, and it is heated under reflux at a temperature of 30 to 100 °C for at least 1 hour, preferably 1 to 6 hours, to obtain acidified porous carbon. Preferably, in this step S11), the acidified porous carbon is washed with deionized water, filtered, and vacuum dried, and then proceed to step S12).

[0026] In S12), the porous carbon acidified in step S11) is mixed with thionyl chloride and N,N-dimethylformamide, the mass ratio of the acidified porous carbon, thionyl chloride and N,N-dimethylformamide is 1:20 to 80:5 to 15, and it is reacted at a temperature of 30 to 100 °C for at least 1 hour to obtain chlorinated porous carbon. Preferably, in this step S12), the chlorinated porous carbon is washed with tetrahydrofuran and dried, and then proceed to step S13).

[0027] In S13), the porous carbon chloride obtained in step S12) is reacted with aniline at a temperature of 0 to 40°C for at least 1 hour to obtain amidated porous carbon as aminated porous carbon. Here, the mass ratio of the porous carbon chloride to aniline is 1:10 to 30. Preferably, in this step S13), the amidated porous carbon prepared by the reaction is washed with acetone until it becomes colorless, and then used as the aminated porous carbon in step S10) of this example.

[0028] Preferably, it is a silicon-carbon composite material prepared by the method for preparing a silicon-carbon composite material by plasma modification as described above. Here, the silicon-carbon composite material includes a core-shell structure composed of a core and a shell. The core includes a nitrogen-doped silicon-carbon composite material, and the shell includes a halogenated carbon and amorphous carbon.

[0029] Preferably, it is the application of the silicon-carbon composite material as described above. The silicon-carbon composite material is used as an active material raw material for manufacturing an electrode sheet of a battery, preferably as an active material raw material for manufacturing a negative electrode sheet of a lithium-ion battery, but can be applied as needed.

[0030] So that those skilled in the art can easily understand the technical solutions of the present invention, the following clearly and completely describes the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Naturally, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts shall be included in the protection scope of the present invention.

[0031] Based on the above-described embodiments, the present application further provides the following specific Examples 1 to 3.

[0032] It should be noted that all of the specific Examples 1 to 3 prepared aminated porous carbon by the following steps S11) to S13).

[0033] In S11), 10 g of porous carbon was added to 300 g of concentrated nitric acid, heated under reflux at 80 °C for 3 hours, allowed to stand, washed and filtered with deionized water, and vacuum dried at 80 °C for 24 hours to obtain acidified porous carbon.

[0034] In S12), 1 g of the acidified porous carbon obtained in the previous step S11) was taken and added to 60 g of thionyl chloride, and at the same time 10 g of N,N-dimethylformamide was added. After reacting at 80 °C for 3 hours, it was washed with tetrahydrofuran (abbreviated as "THF") and dried to obtain chlorinated porous carbon.

[0035] In S13), 1 g of the chlorinated porous carbon obtained in the previous step S12) was reacted with 20 g of aniline at 20 °C for 3 hours, and then washed with acetone until it became colorless to obtain amidated porous carbon as aminated porous carbon.

[0036] Example 1: A silicon-carbon composite material was prepared by the following steps S10) to S30).

[0037] In step S10), 100 g of aminated porous carbon was placed in a deposition chamber. First, a silane mixed gas (volume ratio of silane gas: argon gas = 1:10) was passed through the deposition chamber. The temperature of the deposition chamber was set to 500 °C, the flow rate of the silane mixed gas was set to 50 ml / min, and the passing time was set to 90 minutes to deposit nanosilicon on the aminated porous carbon to obtain a silicon-carbon precursor material.

[0038] In step S20), 100 g of the silicon-carbon precursor material obtained in step S10) was transferred to a chamber for plasma modification, and chlorine gas was passed through the chamber for plasma modification in the form of plasma. Here, as the parameters of the chamber for plasma modification, the degree of vacuum was set to 5 Pa, the temperature was set to 400 °C, the output of the plasma method was set to 800 W, the flow rate of chlorine gas was set to 300 sccm, and the passing time was set to 30 minutes to deposit the generated chlorine ions on the surface of the silicon-carbon precursor material to obtain a silicon-carbon precursor material coated with carbon chloride.

[0039] In S30), the passage of chlorine gas is stopped, and methane gas is passed through the plasma reforming chamber in the form of plasma to obtain a silicon-carbon composite material. Here, as parameters of the plasma reforming chamber, the degree of vacuum is set to 5 Pa, the temperature is set to 400 °C, the output of the plasma method is set to 800 W, the flow rate of methane gas is set to 300 sccm, and the passing time is set to 30 minutes.

[0040] The silicon-carbon composite material obtained in Example 1 includes a core-shell structure composed of a core and a shell. Here, the core includes a nitrogen-doped silicon-carbon composite material, and the shell includes carbon chloride and amorphous carbon coated on the surface of the carbon chloride.

[0041] This application conducts an SEM test on the silicon-carbon composite material prepared in Example 1, and the test results are shown in Figure 2. As can be seen from Figure 2, the silicon-carbon composite material provided in Example 1 exhibits a spherical structure with a uniform particle size distribution and slight bonding, the size distribution of the material particles is reasonable, and the particle size of the particles is in the range of 1 to 5 μm.

[0042] Example 2: A silicon-carbon composite material was prepared by the following steps S10) to S30).

[0043] In step S10), 100 g of aminated porous carbon is placed in the deposition chamber. First, a silane mixed gas (volume ratio of silane gas: argon gas = 1:10) is passed through the deposition chamber. The temperature of the deposition chamber is set to 400 °C, the flow rate of the silane mixed gas is set to 10 ml / min, and the passing time is set to 300 minutes to deposit nanosilicon on the aminated porous carbon to obtain a silicon-carbon precursor material.

[0044] In step S20), 100 g of the silicon-carbon precursor material obtained in step S10) was transferred to the chamber for plasma modification, and fluorine gas was passed through the chamber for plasma modification in the form of plasma. Here, as the parameters of the chamber for plasma modification, the degree of vacuum was set to 1 Pa, the temperature was set to 300 °C, the output of the plasma method was set to 500 W, the flow rate of the fluorine gas was set to 100 sccm, and the passing time was set to 60 minutes. The generated fluorine ions were deposited on the surface of the silicon-carbon precursor material to obtain a silicon-carbon precursor material coated with fluorocarbon.

[0045] In S30), the passage of the fluorine gas was stopped, and ethylene gas was passed through the chamber for plasma modification in the form of plasma to obtain a silicon-carbon composite material. Here, as the parameters of the chamber for plasma modification, the degree of vacuum was set to 1 Pa, the temperature was set to 300 °C, the output of the plasma method was set to 500 W, the flow rate of the ethylene gas was set to 100 sccm, and the passing time was set to 60 minutes.

[0046] The silicon-carbon composite material obtained in this example includes a core-shell structure composed of a core and a shell. Here, the core includes a nitrogen-doped silicon-carbon composite material, and the shell includes fluorocarbon and amorphous carbon coated on the surface of the fluorocarbon.

[0047] Example 3: A silicon-carbon composite material was prepared by the following steps S10) to S30).

[0048] In step S10), 100 g of aminated porous carbon was placed in the deposition chamber. First, a silane mixed gas (volume ratio of silane gas:argon gas = 1:10) was passed through the deposition chamber. The temperature of the deposition chamber was set to 600 °C, the flow rate of the silane mixed gas was set to 100 ml / min, and the passing time was set to 30 minutes to deposit nanosilicon on the aminated porous carbon to obtain a silicon-carbon precursor material.

[0049] In step S20), 100 g of the silicon-carbon precursor material obtained in step S10) was transferred to the chamber for plasma modification, and bromine gas was passed through the chamber for plasma modification in the form of plasma. Here, as the parameters of the chamber for plasma modification, the degree of vacuum was set to 10 Pa, the temperature was set to 600 °C, the output of the plasma method was set to 1000 W, the flow rate of bromine gas was set to 500 sccm, and the passing time was set to 10 minutes. The generated bromine ions were deposited on the surface of the silicon-carbon precursor material to obtain a silicon-carbon precursor material coated with carbon bromide.

[0050] In S30), the passage of bromine gas was stopped, and acetylene gas was passed through the chamber for plasma modification in the form of plasma to obtain a silicon-carbon composite material. Here, as the parameters of the chamber for plasma modification, the degree of vacuum was set to 10 Pa, the temperature was set to 500 °C, the output of the plasma method was set to 1000 W, the flow rate of acetylene gas was set to 500 sccm, and the passing time was set to 10 minutes.

[0051] The silicon-carbon composite material obtained in Example 3 of the present invention includes a core-shell structure composed of a core and a shell. Here, the core includes a nitrogen-doped silicon-carbon composite material, and the shell includes carbon bromide and amorphous carbon coated on the surface of the carbon bromide.

[0052] Comparative Example 1: The other technical solutions of this Comparative Example 1 are the same as those of Example 1, but the difference is that in this Comparative Example 1, porous carbon (purchased directly) was used instead of the aminated porous carbon of Example 1.

[0053] Comparative Example 2: The other technical solutions of this Comparative Example 2 are the same as those of Example 1, but the difference is that in this Comparative Example 2, step S20) was omitted, and step S30) of Example 1 was replaced as follows.

[0054] In S30), 100 g of the silicon-carbon precursor material obtained in step S10) was transferred to a chamber for plasma modification, and ethylene gas was passed through the chamber for plasma modification in the form of plasma to obtain a silicon-carbon composite material. Here, as parameters of the chamber for plasma modification, the degree of vacuum was set to 1 Pa, the temperature was set to 300 °C, the output of the plasma method was set to 500 W, the flow rate of ethylene gas was set to 100 sccm, and the passing time was set to 60 minutes.

[0055] Comparative Example 3: Using the halogen-doped silicon-carbon nanomaterial disclosed in Example 1 of CN105047894A, it was prepared as follows. 10 g of silicon nanoparticles and 10 g of a carbon source were uniformly dispersed in 200 mL of an ethanol solution. The molar ratio of polyvinylidene fluoride, polyvinylidene chloride, and polytetrafluoroethylene was 1:2:1. After uniformly stirring, it was ball-milled for 3 hours and then placed in an oven at 100 °C and dried for 12 h. Finally, it was carbonized in a nitrogen atmosphere, the heating rate was 5 °C / min, the temperature was raised to 800 °C and then maintained at that temperature for 2 h. After cooling, a halogen-doped silicon-carbon nanomaterial was obtained.

[0056] In order to compare and verify the effects of the above examples and comparative examples, in this application, for the composite materials obtained in the above Examples 1 to 3 and Comparative Examples 1 to 3, the following physicochemical tests were performed.

[0057] (1) According to the Chinese national standard GB / T 38823-2020 'Silicon Carbon', the specific surface area and tap density of each silicon-carbon composite material were tested, the electrical conductivity of each silicon-carbon composite material was tested with a four-probe tester, and the silicon crystallite grains of each silicon-carbon composite material were tested by XRD. The test results are shown in Table 1 below.

[0058] (2) Button battery test:

[0059] The corresponding silicon-carbon composite materials in Examples 1 to 3 and Comparative Examples 1 to 3 were prepared as anode materials for lithium-ion batteries according to the following method to obtain button batteries.

[0060] Binder, conductive agent, and solvent were added to each corresponding silicon-carbon composite material, stirred to form a paste, coated on a copper foil, dried, and rolled to obtain a negative electrode sheet. The binder used was LA132, the conductive agent was SP (conductive carbon black), the solvent was NMP, and the usage ratio of the silicon-carbon composite material, SP, LA132, and NMP was 95 g: 1 g: 4 g: 220 mL. The electrolyte was a solution with LiPF6 as the electrolyte, with a concentration of 1 mol / L. Here, the solvent was a mixture of EC and DEC with a volume ratio of 1:1. A metallic lithium sheet was used as the counter electrode, and a polypropylene (PP) membrane was used as the diaphragm.

[0061] Each button battery was assembled in an argon-filled glove box and then its electrochemical performance was tested. Specifically, the electrochemical performance was tested using a Wuhan land CT2001A type battery tester, with a charge-discharge voltage range of 0.005 V to 2.0 V and a charge-discharge rate of 0.1 C. The test results are shown in Table 1 below.

[0062] Also, the negative electrode sheet of the above button battery was fully charged and expanded. The specific test process is as follows. The thickness D1 of the negative electrode sheet of the button battery after rolling was tested, and then the button battery was fully charged to 100% SOC to measure the fully charged thickness D2 of the negative electrode sheet. The expansion rate (expansion rate = (D2 - D1) / D1 * 100%) was calculated, and the test results are shown in Table 1 below. TIFF2025524265000002.tif88170

[0063] As can be seen from the data in Table 1 above, the silicon-carbon composite materials prepared in Examples 1 to 3 of this application are significantly superior to Comparative Examples 1 to 3 in terms of initial efficiency and expansion at full charge.

[0064] (3) Pouch performance test:

[0065] For the corresponding silicon-carbon composite materials in Examples 1 to 3 and Comparative Examples 1 to 3, 90% artificial graphite was doped as the negative electrode material (i.e., the negative electrode sheet), and the positive electrode ternary material (LiNi1 / 3 Co 1 / 3 Mn 1 / 3 (O2), an electrolyte, and a diaphragm were assembled to fabricate a 5 Ah pouch cell. Here, the diaphragm was celegard 2400, and the electrolyte was prepared as a LiPF6 solution (the solvent was a mixed solution of EC and DEC with a volume ratio of 1:1, and the concentration of LiPF6 was 1.3 mol / L), and a pouch cell was fabricated.

[0066] The following performance tests were conducted on each pouch cell.

[0067] a. Liquid absorption test: Using a 1 mL burette, V mL of the electrolyte was sucked up and dropped onto the surface of each negative electrode sheet one drop at a time. The time until the electrolyte was completely absorbed was measured as time t, and the liquid absorption rate S = V / t of the negative electrode sheet was calculated. The test results are shown in Table 2 below.

[0068] b. Liquid retention rate test: The theoretical liquid absorption amount m1 of the corresponding sheet was calculated from the parameters of each negative electrode sheet. The weight of the negative electrode sheet was weighed as m2, and then the negative electrode sheet was immersed in the electrolyte for 24 hours, and the weight of the negative electrode sheet was weighed as m3. The liquid absorption amount m3 - m2 of the negative electrode sheet was calculated, and The liquid retention rate of the formula = (m3 - m2) * 100% / m1 was calculated, and the test results are shown in Table 2 below. TIFF2025524265000003.tif42170

[0069] As can be seen from Table 2 above, the liquid absorption and liquid retention rates of the silicon-carbon composite materials provided in Examples 1 to 3 are superior to those of Comparative Examples 1 to 3.

[0070] c. Cycle performance test: For each fabricated pouch cell, a cycle performance test was carried out. Here, as the test conditions for the cycle performance test, the charge-discharge voltage range was 2.5 to 4.2 V, the temperature was 25 ± 3.0 °C, the charge-discharge rate was 1.0C / 1.0C, and the number of cycles was 500 times. The test results are shown in Table 3 below. TIFF2025524265000004.tif40170

[0071] As can be seen from Table 3 above, the cycle performance of the pouch lithium-ion batteries fabricated using the silicon-carbon composite materials provided in Examples 1 to 3 is significantly superior to that of Comparative Examples 1 to 3.

[0072] d. Rate performance test: For each of the fabricated pouch batteries, a rate performance test was conducted. Here, as the test conditions for the rate performance test, the charge-discharge voltage range was set to 2.5 to 4.2 V, the temperature was set to 25 ± 3.0 °C, charging was performed at 1.0C, 3.0C, 5.0C, and 10.0C, and discharging was performed at 1.0C. The test results are shown in Table 4 below. TIFF2025524265000005.tif121170

[0073] As can be seen from Table 4 above, the rate performance of the pouch lithium-ion batteries fabricated using the silicon-carbon composite materials provided in Examples 1 to 3 is significantly superior to that of Comparative Examples 1 to 3. That is, the pouch batteries fabricated using the silicon-carbon composite materials provided in Examples 1 to 3 have a shorter charging time.

[0074] The present invention is not limited to the details of the above exemplary embodiments, and it is obvious to those skilled in the art that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be regarded as exemplary and non-limiting from any perspective. The scope of the present invention is defined by the appended claims rather than the above description. Accordingly, all modifications that fall within the meaning and scope of equivalent elements of the claims are intended to be included in the present invention. Any reference numbers attached to the claims should not be regarded as limiting the scope of the claims.

[0075] Furthermore, as will be understood, although this specification is described according to embodiments, each embodiment does not necessarily include only one separate technical solution. Such a description method in this specification is only for clarifying the explanation. Those skilled in the art should understand this specification as a whole, and the technical solutions of each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. Put the aminated porous carbon into the deposition chamber, pass silane gas with a flow rate of 100 - 1000 ml / min through the deposition chamber, pass the silane gas at a temperature of 400 - 600 °C for at least 30 minutes, deposit nanosilicon on the aminated porous carbon to obtain a silicon-carbon precursor material (step S10); Transfer the silicon-carbon precursor material obtained in step S10 to the plasma reforming chamber, pass halogen gas in the form of plasma through the plasma reforming chamber, deposit the generated halogen ions on the surface of the silicon-carbon precursor material to obtain a silicon-carbon precursor material coated with halogenated carbon (step S20); A method for preparing a silicon-carbon composite material by plasma reforming, characterized by at least including stopping the passage of the halogen gas, passing a carbon source gas in the form of plasma through the plasma reforming chamber to obtain the silicon-carbon composite material (step S30).

2. In step S20), as parameters of the plasma reforming chamber, set the vacuum degree to 1 - 10 pa, the temperature to 300 - 600 °C, the output of the plasma method to 500 - 1000 W, and / or set the flow rate of the halogen gas to 100 - 500 sccm and the passing time to at least 10 minutes. The method for preparing a silicon-carbon composite material by plasma reforming according to claim 1.

3. In step S30), as parameters of the plasma reforming chamber, set the vacuum degree to 1 - 10 pa, the temperature to 300 - 600 °C, the output of the plasma method to 500 - 1000 W, and / or set the flow rate of the carbon source gas to 100 - 500 sccm and the passing time to at least 10 minutes. The method for preparing a silicon-carbon composite material by plasma reforming according to claim 1.

4. In step S10), the method for preparing the aminated porous carbon is as follows: Pre-acidify the porous carbon with concentrated nitric acid to obtain acidified porous carbon (step S11); Mix the porous carbon acidified in step S11) with thionyl chloride and N,N-dimethylformamide, react at a temperature of 30 - 100 °C for at least 1 hour to obtain chlorinated porous carbon (step S12); Step S13) of reacting the porous carbon chloride obtained in step S12) with aniline to obtain amidated porous carbon as the aminoated porous carbon, and a method for preparing a silicon-carbon composite material by plasma modification according to claim 1, characterized by comprising the same.

5. The method for preparing the aminoated porous carbon is as follows. Step S11) of adding porous carbon to concentrated nitric acid, setting the mass ratio of the porous carbon to concentrated nitric acid to 1:200 to 500, heating and refluxing at a temperature of 30 to 100 °C for at least 1 hour to obtain acidified porous carbon. Step S12) of mixing the acidified porous carbon obtained in step S11) with thionyl chloride and N,N-dimethylformamide, setting the mass ratio of the acidified porous carbon, thionyl chloride and N,N-dimethylformamide to 1:20 to 80:5 to 15, and reacting at a temperature of 30 to 100 °C for at least 1 hour to obtain porous carbon chloride. Step S13) of reacting the porous carbon chloride obtained in step S12) with aniline at a temperature of 0 to 40 °C for at least 1 hour to obtain amidated porous carbon as the aminoated porous carbon, and a step of setting the mass ratio of the porous carbon chloride to aniline to 1:10 to 30, and a method for preparing a silicon-carbon composite material by plasma modification according to claim 1, characterized by comprising the same.

6. In step S11), the acidified porous carbon is washed with deionized water and dried, and then proceed to step S12), and / or in step S12), the porous carbon chloride is washed with tetrahydrofuran and dried, and then proceed to step S13), and / or in step S13), the amidated porous carbon is washed with acetone until it becomes colorless, and a method for preparing a silicon-carbon composite material by plasma modification according to claim 4 or 5, characterized by the same.

7. In step S20), the halogen gas is any one or an arbitrary mixture of fluorine, chlorine, and bromine, and a method for preparing a silicon-carbon composite material by plasma modification according to claim 1, characterized by the same.

8. In step S30), the carbon source gas is any one or an arbitrary mixture of methane, ethylene, acetylene, and ethylene, and a method for preparing a silicon-carbon composite material by plasma modification according to claim 1, characterized by the same.

9. A silicon-carbon composite material, prepared by the method for preparing a silicon-carbon composite material by plasma modification according to any one of claims 1 to 8, comprising a core-shell structure composed of a core and a shell, wherein the core comprises a nitrogen-doped silicon-carbon composite material, and the shell comprises a carbon halide and amorphous carbon. The silicon-carbon composite material is characterized by the above.

10. The application of the silicon-carbon composite material according to claim 9, wherein the silicon-carbon composite material is used as an active material raw material for manufacturing an electrode sheet of a battery, preferably as an active material raw material for manufacturing a negative electrode sheet of a lithium-ion battery.

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